JP5909738B2 - Exhaust system and exhaust device control method - Google Patents

Description

  The present invention relates to an exhaust system configured to include a plurality of exhaust devices connected to an exhaust target via a connection pipe, and an exhaust device control method for controlling the exhaust device in such an exhaust system.

  For example, in the following patent document, air in the holding head is sucked and exhausted from the holding head by a vacuum pump connected to a wafer holding head (decompression suction mechanism: hereinafter also simply referred to as “holding head”). A workpiece suction device configured to suck and hold a suction target (workpiece: wafer) by a holding head is disclosed.

  In this case, when exhausting gas (air) from a plurality of exhaust targets (such as the above-mentioned holding head) in this type of device, the exhaust device (decompression pump) has insufficient exhaust capability and exhausts a required amount of gas. May be difficult to do. In that case, it is possible to exhaust a sufficient amount of gas from multiple exhaust targets by adopting a large exhaust device (exhaust device with high exhaust capacity) that can exhaust a large amount of gas. When the operating state of the machine changes (for example, the number of holding heads used has decreased) and it is no longer necessary to exhaust a large amount of gas, power is unnecessarily consumed by operating the large exhaust system. In addition, the vacuum pressure in the pipe connecting each exhaust target and the exhaust device becomes excessively high, which may cause a large burden on the exhaust device. Therefore, the applicant connects a plurality of exhaust devices in parallel to the exhaust target and changes the operation state of each exhaust device according to the load amount, thereby exhausting a small amount of air (gas). In various states up to the state where a large amount of air (gas) is exhausted, an exhaust system has been developed that can exhaust air from an exhaust target by sucking air at a vacuum pressure within a preset vacuum pressure range.

  Specifically, as shown in FIG. 1, in the exhaust system 1x developed by the applicant (hereinafter, the components of the exhaust system 1x will be described by adding “x” to the end of the reference numerals), the inverter Rotational speed variable type in which the rotational speed can be changed (the exhaust amount of air can be changed) according to the frequency of power supplied from the circuits 3ax to 3cx (hereinafter also referred to as “inverter circuit 3x” when these are not distinguished) Vacuum pumps 2ax to 2cx (hereinafter also referred to as "vacuum pump 2x" when they are not distinguished), power supply to the vacuum pump 2ax by the inverter circuit 3ax, power supply to the vacuum pump 2bx by the inverter circuit 3bx, and an inverter By controlling the power supply to the vacuum pump 2cx by the circuit 3cx, the operating state of each vacuum pump 2x is changed, And a control unit 5x for adjusting the amount of exhaust air from the exhaust target of the whole air system 1x.

  In the exhaust system 1x, each vacuum pump 2x is connected to an exhaust target via the connection pipe 6, and as an example, the control unit 5x receives a sensor signal from the pressure sensor 4x disposed in the connection pipe 6. Based on this, a configuration is adopted in which the vacuum pressure in the connection pipe 6 is measured, and the inverter circuit 3x is controlled in accordance with the measurement result to adjust the air exhaust amount. Specifically, when the air is exhausted from the exhaust target by the exhaust system 1x, the control unit 5x controls the operation state of each vacuum pump 2x as shown in FIG. The air is exhausted from the exhaust target by sucking air so that the vacuum pressure becomes a vacuum pressure within a preset vacuum pressure range.

  In this case, in the figure, when the vacuum pressure in the connecting pipe 6 is higher than the vacuum pressure in the above vacuum pressure range (that is, when it is necessary to reduce the load and reduce the amount of air exhausted). : At the time of the exhaust amount reduction process), the control unit 5x shows the rotation speed of each vacuum pump 2x in the left diagram in correspondence with the required exhaust amount. Further, in the same figure, when the vacuum pressure in the connecting pipe 6 is lower than the vacuum pressure in the above-described vacuum pressure range (that is, when the load increases and the amount of exhausted air needs to be increased): The right figure shows at what rotation speed the control unit 5x rotates each vacuum pump 2x during the exhaust amount increase process) in correspondence with the required exhaust amount.

  It is known that in a rotation speed variable exhaust device such as the vacuum pump 2x, it is difficult to sufficiently exhaust gas in an operation state below a predetermined rotation speed. For this reason, when using the exhaust device with variable rotational speed, the lower limit of the rotational speed capable of exhausting to maintain the required vacuum pressure and, for example, the exhaust device is not damaged or the service life is not reduced. The upper limit of the rotational speed is defined, and the operation is performed at the rotational speed within the rotational speed range between the defined lower limit and the upper limit. Hereinafter, as an example, each vacuum pump 2x in the exhaust system 1x will be described assuming that the upper limit of the rotational speed is 100% and the lower limit of the rotational speed is defined as 30%. Further, in order to facilitate understanding of the operating principle of the exhaust system 1x, it is assumed that the exhaust capacities (the exhaust amount of air when operating at the same rotational speed) of the vacuum pumps 2ax to 2cx are equal to each other.

  In this exhaust system 1x, as an example, in a state where the vacuum pumps 2ax to 2cx are each operated at a rotation speed of 100% (the exhaust amount of air by the exhaust system 1x is the exhaust amount AMx), the load is reduced and the vacuum is reduced. When the pressure rises, the control unit 5x executes an exhaust amount reduction process, and controls each inverter circuit 3x according to the exhaust amount required for the load amount, as shown in the left diagram, to each vacuum. The number of rotations of the pump 2x is decreased. At this time, the total exhaust amount of the operating vacuum pumps 2ax to 2cx is equal to the total exhaust amount when the vacuum pumps 2ax and 2bx are operated at 100% rotation speed (that is, the vacuum pumps 2ax to 2cx). Are controlled at a rotational speed of approximately 66.7%, respectively (the state of the exhaust amount Aax)), when the exhaust amount of air by the exhaust system 1x needs to be further reduced, the control unit 5x includes the inverter circuit 3cx. Is controlled to stop the vacuum pump 2cx, and the inverter circuits 3ax and 3bx are controlled to increase the rotation speeds of the vacuum pumps 2ax and 2bx to 100%, respectively. The circuits 3ax and 3bx are controlled to reduce the rotation speeds of the vacuum pumps 2ax and 2bx, respectively.

  In addition, the total exhaust amount of the vacuum pumps 2ax and 2bx, which are continuously operated in a state where the vacuum pump 2cx is stopped, is equal to the exhaust amount when the vacuum pump 2ax is operated at a rotational speed of 100% ( That is, when it is necessary to further reduce the amount of air exhausted by the exhaust system 1x in a state where the vacuum pumps 2ax and 2bx are each operated at a rotation speed of 50% (state of the exhaust amount Abx), the control unit 5x The inverter circuit 3bx is controlled to stop the vacuum pump 2bx, and the inverter circuit 3ax is controlled to increase the rotation speed of the vacuum pump 2ax to 100%. Reduce the speed. Further, air is exhausted by the exhaust system 1x in a state where the vacuum pump 2ax, which is continuously operated in a state where the vacuum pumps 2cx, 2bx are stopped, is operated at a rotation speed of 30% (a state where the exhaust amount is Acx). When the amount needs to be further reduced, the control unit 5x controls the inverter circuit 3ax to stop the vacuum pump 2ax.

  On the other hand, when the air needs to be exhausted in a state where all of the vacuum pumps 2ax to 2cx are stopped, the control unit 5x executes the exhaust amount increasing process and controls the inverter circuit 3ax to perform the vacuum. The operation of the pump 2ax is started. At this time, the vacuum pump 2ax starts operating at a rotation speed of 30% and exhausts air with an exhaust amount Bax. Next, the control unit 5x controls the inverter circuit 3ax according to the required exhaust amount to increase the rotation speed of the vacuum pump 2ax. At this time, when it is necessary to further increase the amount of air exhausted by the exhaust system 1x in a state where the number of rotations of the vacuum pump 2ax reaches 100% (state of the exhaust amount Bbx), the control unit 5x 3ax is controlled to reduce the rotational speed of the vacuum pump 2ax to 50%, and the inverter circuit 3bx is controlled to operate the vacuum pump 2bx at a rotational speed of 50%. Thus, the inverter circuits 3ax and 3bx are controlled to increase the rotation speeds of the vacuum pumps 2ax and 2bx, respectively.

  Further, when it is necessary to further increase the amount of air exhausted by the exhaust system 1x when the rotation speeds of the vacuum pumps 2ax and 2bx reach 100% (state of the exhaust amount Bcx), the control unit 5x The circuits 3ax and 3bx are controlled to reduce the rotational speeds of the vacuum pumps 2ax and 2bx to about 66.7%, respectively, and the inverter circuit 3cx is controlled to operate the vacuum pump 2cx at a rotational speed of about 66.7%. After that, the inverter circuits 3ax to 3cx are controlled according to the required exhaust amount to increase the rotation speeds of the vacuum pumps 2ax to 2cx, respectively.

  In order to facilitate understanding of the operating principle of the exhaust system 1x, the amount of air exhausted by the exhaust system 1 is gradually reduced from the exhaust amount AMx to the exhaust amount Acx (A0x), and then the exhaust amount is reduced. Although the control procedure (change procedure of the operating state) of each vacuum pump 2x by the control unit 5x when gradually increasing from Bax (B0x) to the exhaust amount BMx has been described, actually, for example, the exhaust amount AMx to the exhaust amount After the control to reduce the exhaust amount within the range up to Aax is performed, the load increases and the vacuum pressure decreases, and the control to increase the exhaust amount within the range from the exhaust amount Bcx to the exhaust amount BMx accordingly Or after the control to increase the displacement in the range from the displacement Bbx to the displacement Bcx, the load decreases and the vacuum pressure increases. Control for reducing emissions or performed in the range of emissions Aax to an exhaust amount Abx depending. Thereby, in the exhaust system 1x developed by the applicant, the operating state of each vacuum pump 2x is changed as appropriate, so that it is within the range from the exhaust amount AMx to the exhaust amount A0x (within the range from the exhaust amount B0x to the exhaust amount BMx). ), It is possible to exhaust air from the exhaust target with any required displacement.

Japanese Patent No. 4446246 (pages 7-12, FIGS. 1-6)

  However, the exhaust system 1x developed by the applicant and the control method of each vacuum pump 2x in the exhaust system 1x have the following problems to be improved. That is, in the exhaust system 1x disclosed by the applicant, the total exhaust amount of the operating vacuum pumps 2ax to 2cx is equal to the total exhaust amount when the vacuum pumps 2ax and 2bx are operated at 100% rotation speed, respectively. When it is necessary to reduce the displacement in the same operation state, the vacuum pump 2cx is stopped and the rotation speeds of the vacuum pumps 2ax and 2bx are increased, and the total displacement of the operating vacuum pumps 2ax and 2bx is The vacuum pump 2bx is stopped and the rotational speed of the vacuum pump 2ax is reduced when it is necessary to reduce the exhaust amount in an operation state equal to the total displacement when the vacuum pump 2ax is operated at 100% rotational speed. The structure to raise is adopted.

  Therefore, in the exhaust system 1x developed by the applicant, the range from 2/3 of the range from the exhaust amount AMx that can be realized to the exhaust amount Acx (A0x) (from the exhaust amount Aax to the exhaust amount Acx (A0x)). Range), the vacuum pump 2cx is controlled to be in a stopped state. When the exhaust amount is to be reduced, the exhaust amount (for example, in FIG. 7) that can be dealt with by reducing the rotation speed of the vacuum pumps 2ax to 2cx. The vacuum pump 2cx is stopped in spite of the displacement (A2x). Further, the vacuum pumps 2cx and 2bx are stopped in a range of 1/3 of the range from the exhaust amount AMx to the exhaust amount Acx (A0x) that can be realized (the range from the exhaust amount Abx to the exhaust amount Acx (A0x)). When the exhaust amount is to be reduced, the vacuum pumps 2ax and 2bx can be reduced by reducing the rotational speed of the vacuum pumps 2ax and 2bx, even if the exhaust amount can be dealt with (for example, the exhaust amount A4x in FIG. 7). The vacuum pump 2bx is stopped together with the pump 2cx.

  In this case, in the exhaust system 1x developed by the applicant, the exhaust amount is increased in a state where the air is exhausted with the exhaust amount reduced to any of the amounts in the left diagram of FIG. 7 by executing the exhaust amount reduction process. When the necessity arises, the exhaust amount increasing process is started in a manner corresponding to the exhaust amount at that time in the right figure. For this reason, for example, when it is necessary to reduce the exhaust amount in a state where the air is exhausted at the exhaust amount A1x in the left figure, the exhaust amount reduction process is started, and the rotation speed of the vacuum pumps 2ax to 2cx is reduced. When the exhaust amount is reduced to the exhaust amount Aax, the vacuum pump 2cx is stopped, and then, when the air is exhausted at the exhaust amount A2x, the load fluctuates and the exhaust amount is reduced. When it is necessary to increase to B1x, the exhaust amount increasing process is started in the form of the exhaust amount B2x in the right figure, and the exhaust amount is increased to the exhaust amount Bcx by increasing the rotation speed of the vacuum pumps 2ax and 2bx. Then, the operation of the vacuum pump 2cx is started.

  However, as described above, the variable rotation speed exhaust device mounted in this type of system is difficult to exhaust gas sufficiently in an operating state below a predetermined rotation speed. Therefore, even in the exhaust system 1x developed by the applicant, when the operation of the vacuum pump 2cx is started when the exhaust amount has increased to the exhaust amount Bcx by increasing the rotation speed of the vacuum pumps 2ax, 2bx, Since a sufficient amount of air cannot be exhausted until the rotational speed of the pump 2cx increases to 30% or higher, a certain amount of air can be exhausted with the required exhaust amount B1x. It will take time.

  Similarly, for example, when it is necessary to reduce the exhaust amount in the state where the air is exhausted at the exhaust amount A3x in the left figure, the exhaust amount reduction process is started, and the rotation speed of the vacuum pumps 2ax and 2bx is decreased. The vacuum pump 2bx is stopped when the exhaust amount is reduced to the exhaust amount Abx and the air is exhausted at the exhaust amount A4x, and then the load fluctuates and the exhaust amount is reduced. When it is necessary to increase to B3x, the exhaust amount increasing process is started in the form of the exhaust amount B4x in the right figure, and the vacuum is increased when the exhaust amount increases to the exhaust amount Bbx by increasing the rotation speed of the vacuum pump 2ax. The operation of the pump 2bx will be started. However, a sufficient amount of air cannot be exhausted until the rotational speed of the vacuum pump 2bx that has started operation increases to a rotational speed of 30% or more, so that the air can be exhausted with the required exhaust amount B3x. It takes a certain amount of time to reach a proper state.

  Thus, in the exhaust system 1x developed by the applicant, when it is necessary to reduce the displacement, it is possible to cope with the problem by reducing the rotational speed of the operating vacuum pump 2x. Since the control for stopping one of the pumps 2x is performed, the exhaust amount range for controlling one or two of the vacuum pumps 2x to be stopped is slightly widened. Therefore, in the exhaust system 1x developed by the applicant, the exhaust amount range in which the operation of the vacuum pump 2x in the stopped state needs to be started when the exhaust amount needs to be increased is slightly widened. There is a current situation in which the frequency at which a certain amount of time is required until the air can be exhausted with the exhausted amount is somewhat high. For this reason, it is preferable to improve this point.

  The present invention has been made in view of the problems to be improved, and a main object of the present invention is to provide an exhaust system and an exhaust device control method capable of rapidly increasing the exhaust amount to a required amount.

In order to achieve the above object, an exhaust system according to claim 1 is provided between a first rotation speed defined in advance and a second rotation speed defined in advance that is higher than the first rotation speed. A variable number of rotation type (N is a natural number of 2 or more) exhaust device configured to be operable at the number of rotations and exhausting gas from an exhaust target through a connection pipe, and when the load decreases Exhaust gas that changes the operating state of the exhaust device to reduce the exhaust amount of the gas and performs exhaust amount reduction processing and changes the operating state of the exhaust device to increase the exhaust amount of the gas when the load increases An exhaust system comprising: a control unit that maintains the vacuum pressure in the connection pipe at a vacuum pressure within a preset vacuum pressure range by performing a volume increasing process, wherein the exhaust system is equal to or higher than the first rotational speed. In advance, the rotation speed is lower than the second rotation speed. The determined third rotational speed is defined as the lower limit of the range in which the rotational speed of each exhaust device is changed during the exhaust amount reduction processing, depending on the number of operating exhaust devices when the exhaust amount reduction processing is executed. The control unit operates M of the N exhaust devices (M is a natural number of 2 or more and N or less) to operate (M-1) of the M exhaust devices. The M exhaust devices are configured to be controllable in a plurality of operating states in which the gas is exhausted with a displacement smaller than the exhaust amount of the gas when operated at the second rotational speed , When the exhaust amount of the gas is reduced in the operation state of the plurality of units, the rotation speeds of the L exhaust units (L is a natural number equal to or less than M) of the M exhaust units are set to When the rotation speed is higher than the third rotation speed, the M The first process of reducing at least the number of rotations of the L exhaust devices is performed as the exhaust amount reduction process without stopping the exhaust devices, and the number of rotations of the L exhaust devices specified in advance is determined. At the third rotational speed, one of the L exhaust devices and one of the exhaust devices other than the L exhaust devices operating at the third rotational speed A second process of stopping any one and increasing the number of revolutions of at least one of the exhaust devices that continue to operate is executed as the exhaust amount reduction process.

  The exhaust system according to claim 2 is the exhaust system according to claim 1, wherein the third rotational speed when the number of operating exhaust devices is M = 2 is equal to the first rotational speed. It is prescribed.

  The exhaust system according to claim 3 is the exhaust system according to claim 1 or 2, wherein a predetermined fourth rotational speed that is higher than the third rotational speed and equal to or less than the second rotational speed is The upper limit of the range in which the rotational speed of each exhaust device is changed during the exhaust amount increasing process is defined according to the number of operating exhaust devices when the exhaust amount increasing process is performed, and the control unit When increasing the amount, when at least one of the exhaust devices is in a stopped state and the rotational speed of at least one of the operating exhaust devices is lower than the fourth rotational speed, The third process of increasing the rotational speed of the exhaust device operating at a lower speed than the fourth rotational speed is executed as the exhaust amount increasing process without starting the operation of the exhaust apparatus in the stopped state. Then In addition, when at least one of the exhaust devices is in a stopped state and all the rotational speeds of the exhaust devices in operation are the fourth rotational speed, the operation of one of the exhaust devices in the stopped state is performed And a fourth process for reducing the rotational speed of at least one of the exhaust apparatuses in operation is executed as the exhaust amount increasing process.

  According to a fourth aspect of the present invention, in the exhaust system according to the third aspect, all of the fourth rotational speeds for each operating number are defined to be equal to the second rotational speed.

  An exhaust system according to a fifth aspect is the exhaust system according to any one of the first to fourth aspects, wherein the control unit operates at a higher speed than the third rotational speed in the exhaust amount reduction process. When there are a plurality of exhaust devices that are present, all the rotational speeds of the plurality of exhaust devices that are operating at a higher speed than the third rotational speed are decreased. Note that the control of “reducing all the rotational speeds of the plurality of exhaust devices” includes not only the control of “reducing all the rotational speeds of the plurality of exhaust devices equally” but also “ This includes the control of “reducing all the rotation speeds of the apparatus by different reduction amounts”.

  An exhaust system according to a sixth aspect is the exhaust system according to any one of the first to fifth aspects, wherein the control unit includes a plurality of exhaust devices in operation in the exhaust amount reduction processing and the exhaust amount increase processing. When present, all the rotational speeds of the exhaust devices are controlled to the same rotational speed.

  An exhaust system according to a seventh aspect is the exhaust system according to any one of the first to fourth aspects, wherein the control unit operates at a higher speed than the third rotational speed in the exhaust amount reduction process. Without changing the rotation speed of at least one of the plurality of exhaust apparatuses operating at a higher speed than the third rotation speed when there are a plurality of the exhaust apparatuses, Reduce the rotational speed of at least one of the other.

  An exhaust system according to claim 8 is the exhaust system according to any one of claims 1 to 7, further comprising a pressure sensor that is disposed in the connection pipe and detects a vacuum pressure in the connection pipe. The control unit specifies the vacuum pressure in the connection pipe based on the sensor signal output from the pressure sensor, and the specified vacuum pressure is higher than the vacuum pressure in the preset vacuum pressure range. When it is determined that the load has decreased when the pressure increases, the exhaust amount reduction process is executed, and the specified vacuum pressure falls to a vacuum pressure lower than the vacuum pressure within the preset vacuum pressure range It is determined that the load has increased, and the exhaust amount increasing process is executed.

  An exhaust system according to a ninth aspect is the exhaust system according to any one of the first to eighth aspects, wherein the control unit is configured such that the number of operating the exhaust devices is one and the number of rotations of the one is the third. When the load decreases in the state of the number of rotations, the state where the one exhaust device is operated at the third number of rotations is maintained.

The exhaust device control method according to claim 10 is operable at a rotation speed between a first rotation speed defined in advance and a second rotation speed defined in advance that is higher than the first rotation speed. The load is reduced in the exhaust system that is configured to include the N rotation speed variable type exhaust devices (N is a natural number of 2 or more) that exhausts gas from the exhaust target through the connection pipe. Sometimes, the exhaust gas amount is reduced by changing the operating state of the exhaust device to reduce the exhaust amount of the gas, and when the load increases, the operating state of the exhaust device is changed to reduce the exhaust amount of the gas. An exhaust device control method for maintaining the vacuum pressure in the connection pipe at a vacuum pressure within a preset vacuum pressure range by executing an exhaust amount increasing process to increase, wherein Lower than the second rotational speed The predetermined third rotational speed is set as a lower limit of a range in which the rotational speed of each exhaust device is changed during the exhaust amount reduction processing, depending on the number of operating exhaust devices when the exhaust amount reduction processing is executed. In addition, by operating M of the N exhaust devices (M is a natural number of 2 or more and N or less), (M-1) of the M exhaust devices are operated as the second. The exhaust system configured to be able to control the M exhaust devices in a plurality of operating states in which the gas is exhausted with an exhaust amount smaller than the exhaust amount of the gas when operated at a rotational speed of As a target, when the exhaust amount of the gas is reduced in the operation state of the plurality of units , the rotation of the L units (L is a natural number equal to or less than M) of the M units of the exhaust units that are designated in advance. The number is higher than the third rotational speed At the time of rotation, without stopping the M exhaust devices, at least a first process for reducing the rotational speed of the L exhaust devices is executed as the exhaust amount reduction process. When the rotational speed of the exhaust device is the third rotational speed, the third rotational speed of the exhaust devices other than the L exhaust devices and the exhaust devices other than the L exhaust devices. A second process of stopping any one of the operating units and increasing the rotational speed of at least one of the exhaust units that continue to operate is executed as the exhaust amount reduction process.

  An exhaust device control method according to an eleventh aspect is the exhaust device control method according to the tenth aspect, wherein a predetermined fourth speed that is higher than the third rotational speed and equal to or less than the second rotational speed is provided. The rotational speed is defined as the upper limit of the range in which the rotational speed of each exhaust device is changed during the exhaust amount increasing process according to the number of operating exhaust devices during the exhaust amount increasing process, and the exhaust of the gas When increasing the amount, when at least one of the exhaust devices is in a stopped state and the rotational speed of at least one of the operating exhaust devices is lower than the fourth rotational speed, The third process of increasing the rotational speed of the exhaust device operating at a lower speed than the fourth rotational speed is executed as the exhaust amount increasing process without starting the operation of the exhaust apparatus in the stopped state. Do Both operations of one of the exhaust devices in the stopped state when at least one of the exhaust devices is in the stopped state and all the rotational speeds of the exhaust devices in operation are the fourth rotational speed. And a fourth process for reducing the rotational speed of at least one of the exhaust apparatuses in operation is executed as the exhaust amount increasing process.

  In the exhaust system according to claim 1 and the exhaust device control method according to claim 10, (M-1) of the M exhaust devices are operated by operating M of the N exhaust devices. When reducing the amount of gas exhausted in a state where the gas is exhausted with a smaller amount of exhaust than the amount of gas exhausted when operating at the second rotational speed, L of the M exhaust devices When the rotation speed of the pre-designated exhaust device is higher than the third rotation speed, the first process of reducing the rotation speed of at least L exhaust devices without stopping the M exhaust devices Is executed as the exhaust amount reduction process, and when the number of rotations of the L predetermined exhaust devices is the third number of rotations, one of the L exhaust devices and the exhaust other than the L exhaust devices One of the devices operating at the third rotational speed With stops, to run as an exhaust amount reduction process a second process that raises at least one rotational speed of the exhaust system that is continues to operate.

  Therefore, according to the exhaust system according to claim 1 and the exhaust device control method according to claim 10, in the exhaust amount reduction process, the number of rotations of the L predesignated exhaust devices is the operation at the third rotation number. Until it becomes a state, the operated exhaust system is maintained without stopping, so the total exhaust amount by the operating exhaust system continues to operate when one of them is stopped Compared to the configuration and method of stopping one exhaust system when the exhaust system to be operated is equal to the total exhaust amount when operating at 100% rotation speed, control is made to operate a large number of exhaust systems. Exhaust amount range to be performed, that is, when it is necessary to increase the exhaust amount, there is a sufficient control range in which the exhaust amount can be increased only by increasing the number of revolutions of the exhaust device in which the operated state is maintained Since it can be widened, the frequency of exhausting the gas with the required displacement can be reduced to reduce the frequency of a certain amount of time, and the displacement can be increased quickly to the required amount. Can do.

  According to the exhaust system of the second aspect, the third rotational speed when the number of operating exhaust devices is M = 2 is defined as the rotational speed equal to the first rotational speed. Since the exhaust device is kept operating until the rotational speed of the exhaust device decreases to the first rotational speed defined as the lower limit, the third rotational speed is set higher than the first rotational speed. Compared to the configuration and method specified for rotation, the frequency of exhausting the gas to the required amount is further reduced by reducing the frequency at which a certain amount of time is required before the gas can be exhausted with the required displacement. Can be increased more quickly.

  In the exhaust system according to claim 3 and the exhaust device control method according to claim 11, when the exhaust amount of gas is increased, at least one exhaust device is in a stopped state and out of operating exhaust devices. When the rotational speed of at least one of the exhaust systems is lower than the fourth rotational speed, the exhaust apparatus that is operating at a lower rotational speed than the fourth rotational speed is started without starting the operation of the exhaust apparatus in the stopped state. When the third process for increasing the rotational speed is executed as the exhaust amount increasing process, at least one exhaust device is in a stopped state, and all the rotational speeds of the operating exhaust devices are the fourth rotational speed. Then, the fourth process of starting the operation of one of the stopped exhaust devices and reducing the rotational speed of at least one of the exhaust devices in operation is executed as the exhaust amount increasing process.

  Therefore, according to the exhaust system of claim 3 and the exhaust device control method of claim 11, the exhaust amount for stopping the exhaust device in the exhaust amount reduction process and the operation of the exhaust device in the exhaust amount increase process are started. Since the amount of exhaust is different, when the gas should be exhausted with the same amount of exhaust as these, the control to stop the exhaust device and the control to start the operation of the exhaust device are repeatedly executed in small increments. As a result, the frequency at which a certain amount of time is required until the gas can be exhausted with the required exhaust amount is further reduced, and the exhaust amount is reduced to the required amount. Can be increased more quickly.

  According to the exhaust system of the fourth aspect, since all of the fourth rotational speeds for each operation number are defined as the rotational speeds equal to the second rotational speed, the rotational speed of the exhaust device is increased during the exhaust amount increasing process. However, since the state where the exhaust device in the stopped state is stopped is maintained until the second rotational speed defined as the upper limit is increased, the fourth rotational speed is set to be lower than the second rotational speed. Compared with the specified configuration and method, the frequency of starting the operation of the exhaust device in the stopped state is further reduced, so that it takes a certain amount of time before the gas can be exhausted with the required exhaust amount. The frequency can be further reduced and the displacement can be increased more quickly to the required amount.

  According to the exhaust system of claim 5, in the exhaust amount reduction processing, when there are a plurality of exhaust devices operating at a higher speed than the third rotational speed, the exhaust system operates at a higher speed than the third rotational speed. By reducing all the rotational speeds of a plurality of exhaust devices, the stress applied to each exhaust device during exhaust processing can be made to be the same level. It is possible to avoid a situation where it is significantly reduced compared to any other.

  According to the exhaust system of the sixth aspect, in the exhaust amount reduction process and the exhaust amount increase process, when there are a plurality of operating exhaust apparatuses, all the rotational speeds of the exhaust apparatuses are controlled to the same rotational speed. A configuration / method for controlling one of the exhaust devices to change only one of the other rotational speeds while fixing the rotational speed of one of the exhaust apparatuses to a constant rotational speed, Compared to the configuration and method for controlling to different speeds, the operating state of each exhaust device can be easily changed according to the required exhaust amount.

  According to the exhaust system of claim 7, in the exhaust amount reduction process, when there are a plurality of exhaust devices operating at a higher speed than the third rotational speed, the exhaust system operates at a higher speed than the third rotational speed. By reducing the rotational speed of at least one other of the plurality of exhaust devices without changing the rotational speed of at least one of the exhaust devices, for example, the rotational speed of each exhaust device is made different from each other. Unlike the configuration and method of controlling to change, it is only necessary to change only the rotation speed of the other exhaust devices while fixing the rotation speed of one of the exhaust devices to a constant rotation speed. The operating state of each exhaust device can be easily changed according to the required exhaust amount.

  According to the exhaust system of claim 8, the vacuum pressure in the connection pipe is specified based on the sensor signal output from the pressure sensor, and the specified vacuum pressure is within a preset vacuum pressure range. When the pressure rises to a higher vacuum pressure, it is determined that the load has decreased, and the exhaust amount reduction processing is executed, and the specified vacuum pressure is lowered to a vacuum pressure lower than the vacuum pressure within the preset vacuum pressure range. By determining that the load has increased and executing the exhaust amount increase process, the load amount can be identified reliably and easily, and the amount of gas exhausted by the exhaust system can be accurately adjusted to the required exhaust amount. can do.

  According to the exhaust system of claim 9, when the number of operating exhaust devices is one and the load decreases when the number of rotations of the one exhaust device is the third rotation number, the one exhaust device By maintaining the state in which the engine is operated at the third rotational speed, when the load increases and it becomes necessary to increase the displacement, it is only necessary to increase the rotational speed of the exhaust device that continues the operation. Since the displacement can be increased, the displacement can be increased more quickly to the required amount.

It is a block diagram which shows the structure of the exhaust system 1x which concerns on embodiment of this invention, and the exhaust system 1x which the applicant has developed. It is a flowchart of the exhaust amount adjustment process 10 performed by the control part 5 in the exhaust system 1 which concerns on embodiment of this invention. It is explanatory drawing for demonstrating an example of the operation state of the vacuum pumps 2a-2c at the time of execution of the exhaust_gas | exhaustion amount adjustment process 10 (exhaust_gas | exhaustion amount reduction process and exhaust_gas | exhaustion amount increase process) by the exhaust system 1 which concerns on embodiment of this invention. FIG. 5 is a diagram showing the number of rotations (operation state) of the vacuum pumps 2a to 2c in association with the required exhaust amount. Explanation for explaining an example of other operation states of the vacuum pumps 2a to 2c during the execution of the exhaust amount adjustment processing 10 (exhaust amount increase processing and exhaust amount reduction processing) by the exhaust system 1 according to the embodiment of the present invention. It is a figure, and is a figure showing each rotation speed (operating state) of vacuum pumps 2a-2c in association with a required exhaust amount. Explanation for explaining another example of the operation state of vacuum pumps 2a to 2c at the time of execution of exhaust amount adjustment processing 10 (exhaust amount reduction processing and exhaust amount increase processing) by exhaust system 1 according to the embodiment of the present invention. It is a figure, and is a figure showing each rotation speed (operating state) of vacuum pumps 2a-2c in association with a required exhaust amount. It is explanatory drawing for demonstrating another example of the operation state of the vacuum pumps 2a-2c at the time of execution of the exhaust gas amount adjustment process 10 (exhaust gas volume reduction process) by the exhaust system 1 which concerns on embodiment of this invention. FIG. 6 is a diagram showing the respective rotation speeds (operation states) of the vacuum pumps 2a to 2c in association with the required exhaust amount. It is explanatory drawing for demonstrating an example of the operation state of vacuum pump 2ax-2cx at the time of execution of the exhaust_gas | exhaustion amount reduction process and exhaust_gas | exhaustion amount increase process by the exhaust system 1x which the applicant developed, Comprising: Each of vacuum pumps 2ax-2cx It is the figure which represented the rotation speed (operating state) of this in correspondence with the required exhaust amount.

  Hereinafter, embodiments of an exhaust system and an exhaust device control method will be described with reference to the accompanying drawings.

  First, the configuration of the exhaust system 1 will be described with reference to the accompanying drawings.

  The exhaust system 1 shown in FIG. 1 is an example of an “exhaust system” and includes vacuum pumps 2a to 2c (hereinafter also referred to as “vacuum pump 2” when not distinguished from each other), inverter circuits 3a to 3c (hereinafter referred to as these). Are also referred to as “inverter circuit 3”), the pressure sensor 4 and the control unit 5 are provided, and the air in various containers such as an injection molding machine, a suction holding device, a vacuum packaging machine, and a box and a bag are supplied. Air is exhausted from the exhaust target by supplying air (an example of “gas”) from each exhaust pump (not shown) such as a tool to be degassed by each vacuum pump 2 (vacuum pressure is supplied to the exhaust target) To be able to). In this case, in the exhaust system 1, the vacuum pumps 2 are connected in parallel to the exhaust target via connection pipes 6 (an example of “connection pipes”).

  The vacuum pump 2 is an “inverter-controlled vacuum pump” which is an example of a “rotational speed variable exhaust device”, and includes electric power P2a to P2c (hereinafter referred to as distinction) supplied from each inverter circuit 3 as described later. When not, it is configured to include a motor that rotates at a rotational speed (rotational speed) corresponding to the frequency of “electric power P2” as a power source. In this case, in the exhaust system 1 of the present example, as an example, a vacuum pump having a rated frequency of operating power of 60 Hz is used as a power source, and the exhaust capabilities per rotation speed are equal to each other (a vacuum pump having the same exhaust capability). ) Constitutes each vacuum pump 2. Note that the number of “exhaust devices” constituting the “exhaust system” is not limited to the configuration of this example with N = 3, and includes N = 2 or N = 4 or more. An “exhaust system” can be configured.

  Further, as described above, the “variable rotational speed exhaust device” such as the vacuum pump 2 is in a state where it is difficult to sufficiently exhaust air in an operating state below a predetermined rotational speed. Therefore, in the exhaust system 1 of this example, the rotation speed (an example of “second rotation speed”) when the power P2 having the rated frequency (60 Hz) is supplied to each vacuum pump 2 is 100% of the upper limit. 30% of the rotation speed (an example of “first rotation speed”) is defined as a lower limit, and each vacuum pump 2 is operated at a rotation speed between 30% and 100%. It is prescribed. As an example, in the exhaust system 1 of this example, the exhaust amount when the engine is operated at 100% rotational speed is the same, and the exhaust amount when the engine is operated at 30% rotational speed is also the same. Each vacuum pump 2 is constituted by a vacuum pump.

  In this case, the “first rotational speed” defined for the “exhaust device” is the “lower rotational speed of the rotational speed range in which a sufficient amount of gas (air) can be exhausted” as in the above example. Without limitation, “a minimum number of revolutions in the range of revolutions with a large amount of exhaust per power consumption (high energy efficiency)” or “a sufficient amount of lubricating oil in the case of adopting a scraping-type lubrication mechanism” It can be arbitrarily defined by the manufacturer or user according to various standards such as “the number of rotations that can be lifted”. Similarly, the “second rotational speed” defined for the “exhaust device” is not limited to “the rotational speed when operating power having a rated frequency is supplied to the power source” as in the above example. , “Maximum number of revolutions per revolution of power consumption range (high energy efficiency)”, “Maximum number of revolutions within the range of revolutions that does not significantly reduce the service life”, “ According to various standards such as “the upper limit of the number of revolutions in the range of small revolutions” and “the number of revolutions arbitrarily set for the purpose of reducing power consumption when an exhaust system with sufficient exhaust capacity is adopted” It can be defined arbitrarily by the user.

  In the exhaust system 1 of the present example, as an example, the “third rotational speed” as the lower limit of the range in which the rotational speed of each vacuum pump 2 is changed during the exhaust amount reduction process described later is executed as the exhaust amount reduction process. It is defined according to the number of operating “exhaust devices” at the time. Specifically, in the exhaust system 1 of the present example, when the exhaust amount reduction process is executed, the “third” in the state in which M = 3 vacuum pumps 2a to 2c are operating (the number of operating units is 3). The “rotational speed” is defined as 55%, and the “first” in the state where the M = 2 vacuum pumps 2a and 2b are operating (the number of operating units is 2) when the exhaust amount reduction processing is executed. The number of rotations of “3” is defined as 30% of the number of rotations equal to the above “first number of rotations”.

  As for the “third rotational speed”, any rotational speed different from the above example is satisfied as long as the condition of “the first rotational speed or higher and lower than the second rotational speed” is satisfied. Can be specified in numbers. In this case, when the “third rotational speed” is defined as a different rotational speed according to the number of operating “exhaust devices” at the time of execution of the exhaust amount reduction process, at least “exhaust It is preferable that the “third rotational speed” when the number of operating devices of the “device” is M = 2 is defined as the rotational speed equal to the “first rotational speed”. As a result, as compared with the case where the “third rotation speed” is defined to be higher than the “first rotation speed”, only one “exhaust device” is operating in the exhaust amount reduction processing. Can be sufficiently reduced. In addition, the “third rotation speed” can be set to the same rotation speed regardless of the number of operating “exhaust devices” when the exhaust amount reduction process is executed.

  Further, in the exhaust system 1 of the present example, the “fourth rotational speed” as the upper limit of the range in which the rotational speed of each vacuum pump 2 is changed during the exhaust amount increasing process described later is the above “second rotational speed (this In the example, the rotation speed is equal to “100% rotation speed”). As for the “fourth rotational speed”, if the condition “higher than the third rotational speed and equal to or lower than the second rotational speed” is satisfied, the rotation is different from the “second rotational speed”. Can be specified in numbers. In addition, when the number of “exhaust devices” is three or more as in this example, the “fourth rotational speed” varies depending on the number of operating “exhaust devices” during execution of the exhaust amount increasing process. It can also be specified in numbers. However, as will be described later, in order to reduce the frequency of restarting the operation of the stopped vacuum pump 2b or vacuum pump 2c, the "fourth rotational speed" is set to "4" regardless of the number of operating "exhaust devices". It is preferable that the rotation speed is equal to the “second rotation speed”.

  The inverter circuit 3 constitutes a “control unit” in combination with the control unit 5 and changes the frequency of the electric power P2a that the inverter circuit 3a supplies to the vacuum pump 2a in accordance with the control signal S3a from the control unit 5. 3b changes the frequency of the power P2b supplied to the vacuum pump 2b according to the control signal S3b from the control unit 5, and the frequency of the power P2c supplied to the vacuum pump 2c by the inverter circuit 3c according to the control signal S3c from the control unit 5 Each vacuum pump 2 is operated at an arbitrary rotation number between 30% and 100% by changing the above (the rotation number of each vacuum pump 2 is controlled).

  In this example in which each vacuum pump 2 is operated with the rotation speed when the power P2 of 60 Hz as the rated frequency is supplied as 100% rotation speed, each vacuum pump 2 is operated at 55% rotation speed. In addition, when the inverter circuit 3 supplies the power P2 of 33 Hz to each vacuum pump 2, and when each vacuum pump 2 is operated at a rotation speed of 30%, the inverter circuit 3 supplies the power P2 of 18 Hz to each vacuum pump 2. Supply. The pressure sensor 4 is an example of a “pressure sensor”, and is disposed in a connection pipe 6 that connects each vacuum pump 2 and an exhaust target to each other, and detects a vacuum pressure in the connection pipe 6 to detect the pressure. A sensor signal S4 corresponding to the vacuum pressure is output.

  As described above, the control unit 5 forms a “control unit” in combination with each inverter circuit 3 and controls the exhaust system 1 in a comprehensive manner. Specifically, as will be described later, the control unit 5 executes an exhaust amount adjustment process 10 shown in FIG. 2, and sets the vacuum pressure in the connection pipe 6 based on the sensor signal S4 output from the pressure sensor 4. When specifying (measuring), the load decreases when the specified vacuum pressure rises to a vacuum pressure higher than the vacuum pressure within the preset vacuum pressure range (an example of “preset vacuum pressure range”) It is determined that the load has increased, and when the specified vacuum pressure has decreased to a vacuum pressure lower than a vacuum pressure within a preset vacuum pressure range, it is determined that the load has increased. The above-mentioned “preset vacuum pressure range” allows air to be exhausted at a sufficient vacuum pressure required for the exhaust target, and places a heavy burden on each part of the exhaust system 1 (each vacuum pump 2 and the like). It is preset as a range of vacuum pressure not to be applied.

  Further, the control unit 5 increases the load according to the load amount specified based on the sensor signal S4 (that is, the vacuum pressure in the connection pipe 6 increases to a vacuum pressure higher than the above-described vacuum pressure range). The control signals S3a to S3c (hereinafter also referred to as “control signal S3” when not distinguished) are output to each inverter circuit 3 to change the operating state of each vacuum pump 2, and the exhaust system 1 as a whole. When the load increases (that is, when the vacuum pressure in the connection pipe 6 decreases to a vacuum pressure lower than the above vacuum pressure range) ), The control signal S3 is output to each inverter circuit 3 to change the operating state of each vacuum pump 2, and the “exhaust amount increasing process” for increasing the exhaust amount of air as the entire exhaust system 1 is executed. In Ri, to maintain the vacuum pressure in the connection pipe 6 to the vacuum pressure in the vacuum pressure range. The specific contents of the “exhaust amount reduction process” and “exhaust amount increase process” will be described in detail later.

  Next, the exhaust processing (vacuum pressure supply processing) of air from the exhaust target by the exhaust system 1 will be described with reference to the accompanying drawings.

  In the exhaust system 1, the control unit 5 executes the exhaust amount adjustment processing 10 shown in FIG. 2, and specifies the vacuum pressure in the connection pipe 6, and the specified vacuum pressure is within the allowable range for the target vacuum pressure. Whether or not the pressure is applied (vacuum pressure monitoring process) is repeatedly executed at regular time intervals. Specifically, the control unit 5 specifies (measures) the vacuum pressure in the connection pipe 6 based on the sensor signal S4 output from the pressure sensor 4 (step 11). Next, the control unit 5 determines whether or not the specified vacuum pressure is a vacuum pressure within an allowable range with respect to the target vacuum pressure (step 12). At this time, when the specified vacuum pressure is a vacuum pressure within an allowable range with respect to the target vacuum pressure, the control unit 5 does not change the operation state of each vacuum pump 2 (while maintaining the current operation state). Returning to step 11, the vacuum pressure is specified based on the sensor signal S4 from the pressure sensor 4.

  On the other hand, when the vacuum pressure specified in step 11 has increased to a vacuum pressure higher than the allowable range for the target vacuum pressure (step 12), the control unit 5 determines that the load has decreased and executes an exhaust amount reduction process. To do. Specifically, the control unit 5 first specifies the operating state (current operating state) of each vacuum pump 2 at the time when it is determined that the load has decreased (step 13), and then specified in step 11 above. The operation state (target operation state) of each vacuum pump 2 necessary for setting the vacuum pressure within the allowable range with respect to the target vacuum pressure is specified (step 14).

  Further, the control unit 5 outputs the control signals S3a to S3c to the inverter circuits 3a to 3c according to the specified target operation state, thereby supplying the power P2a from the inverter circuit 3a to the vacuum pump 2a, the inverter circuit The operating state of each vacuum pump 2 is changed by changing the supply state of power P2b from 3b to the vacuum pump 2b and the supply state of power P2c from the inverter circuit 3c to the vacuum pump 2c (step 15). As a result, the amount of air exhausted through the connection pipe 6 is reduced, and the vacuum pressure specified based on the sensor signal S4 from the pressure sensor 4 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure (step). 11, 12).

  Further, when the vacuum pressure specified in step 11 falls to a vacuum pressure lower than the allowable range for the target vacuum pressure (step 12), the control unit 5 determines that the load has increased and executes an exhaust amount increasing process. To do. Specifically, the control unit 5 first specifies the operating state (current operating state) of each vacuum pump 2 at the time when it is determined that the load has increased (step 13), and then specified in step 11 above. The operation state (target operation state) of each vacuum pump 2 necessary for setting the vacuum pressure within the allowable range with respect to the target vacuum pressure is specified (step 14).

  Further, the control unit 5 outputs the control signals S3a to S3c to the inverter circuits 3a to 3c according to the specified target operation state, thereby supplying the power P2a from the inverter circuit 3a to the vacuum pump 2a, the inverter circuit The operating state of each vacuum pump 2 is changed by changing the supply state of power P2b from 3b to the vacuum pump 2b and the supply state of power P2c from the inverter circuit 3c to the vacuum pump 2c (step 15). As a result, the amount of air exhausted through the connecting pipe 6 increases, and the vacuum pressure specified based on the sensor signal S4 from the pressure sensor 4 becomes a vacuum pressure within an allowable range with respect to the target vacuum pressure (step). 11, 12).

  Thus, in the exhaust system 1 of this example, by changing the operating state of each vacuum pump 2 according to the load amount, a small amount of air is exhausted in the same manner as the conventional exhaust system 1x developed by the applicant. In various states from a state where the air is exhausted to a state where a large amount of air is exhausted, it is possible to exhaust air from the exhaust target through the connection pipe 6 with a vacuum pressure within a preset vacuum pressure range. .

  Next, the exhaust amount reduction processing and the exhaust amount increase processing in the exhaust system 1 will be specifically described with reference to the attached drawings.

  When the air is exhausted from the exhaust target by the exhaust system 1 of this example, the control unit 5 controls the operating state of each vacuum pump 2 as shown in FIG. The air is exhausted so that the vacuum pressure is within the allowable range with respect to the target vacuum pressure. In this case, when the vacuum pressure in the connection pipe 6 specified based on the sensor signal S4 from the pressure sensor 4 is higher than the vacuum pressure within the allowable range with respect to the target vacuum pressure (that is, FIG. When the load is reduced and it is necessary to reduce the amount of air exhausted), the control unit 5 rotates the vacuum pumps 2 according to the required exhaust amount. It is shown in the figure. Further, in the figure, when the vacuum pressure in the connection pipe 6 is lower than the vacuum pressure within the allowable range for the target vacuum pressure (that is, it is necessary to increase the load and increase the amount of air exhausted). In the right figure, the control unit 5 rotates the vacuum pumps 2 at a rotation speed corresponding to the required exhaust amount. Furthermore, also in FIGS. 4 to 6 to be referred to later, the rotational speed at which the controller 5 rotates each vacuum pump 2 is shown in correspondence with the required exhaust amount.

  In the exhaust system 1, as an example, the load is applied in a state where M = 3 vacuum pumps 2 a to 2 c are operated at a rotational speed of 100% (the exhaust amount of air by the exhaust system 1 is an exhaust amount AM). When the vacuum pressure increases and the vacuum pressure rises, the control unit 5 executes the exhaust amount reduction process, and as shown in the left diagram of FIG. 3, the inverter circuit according to the exhaust amount required for the load amount 3a-3c are controlled and the rotation speed of each vacuum pump 2a-2c is reduced, respectively.

  At this time, in the exhaust system 1 of the present example, when the control unit 5 reduces the exhaust amount of air in a state where the M = 3 vacuum pumps 2a to 2c are operated, the respective vacuum pumps 2a to 2c. When the rotation speed of each of the cylinders is higher than the rotation speed of about 66.7% (in FIG. 3, when the amount of air that is less than the displacement AM and larger than the displacement A1 is exhausted), Without stopping any of the pumps 2a to 2c, the control signals S3a to S3c are output to the inverter circuits 3a to 3c, and the frequencies of the electric power P2a to P2c supplied to the vacuum pumps 2a to 2c are reduced equally. And an example of the control of reducing the rotation speeds of the vacuum pumps 2a to 2c equally (“when there are a plurality of operating exhaust apparatuses, all the rotation speeds of the exhaust apparatuses are controlled to the same rotation speed”). . Thereby, the exhaust amount of the air as the whole exhaust system 1 reduces.

  In addition, when the control unit 5 reduces the amount of air exhausted in a state where M = 3 vacuum pumps 2a to 2c are operated, each of the vacuum pumps 2a to 2c (“L pre-designated exhausts”). The number of rotations is 55% as the “third rotation number” when the rotation number of the “device” is an example of L = 3) and the rotation number is about 66.7% or less and the number of operating units is three. (In FIG. 3, in the state of exhausting an amount of air that is equal to or less than the displacement A1 and larger than the displacement Aa: “By operating M of the N exhaust devices, In an example of “a state in which air is exhausted with a smaller exhaust amount than that when the (M-1) units of the M exhaust devices are operated at the second rotational speed”. The control signals are sent to the inverter circuits 3a to 3c without stopping any of the vacuum pumps 2a to 2c. The rotation speed of the vacuum pumps 2a to 2c as "L exhaust devices" is reduced by equally reducing the frequency of the electric power P2a to P2c supplied to the vacuum pumps 2a to 2c by outputting 3a to S3c, respectively. Other equal control (an example of “first processing”, in which “when there are a plurality of exhaust devices in operation, all the rotational speeds of the exhaust devices are controlled to the same rotational speed”) One case). As a result, the amount of air exhausted as a whole of the exhaust system 1 is further reduced.

  Further, the controller 5 rotates the vacuum pumps 2a to 2c as "L exhaust devices" when reducing the amount of air exhausted while M = 3 vacuum pumps 2a to 2c are operating. When the number of revolutions is 55% as the “third revolution number” when the number of operating units is three (in FIG. 3, when the air of the exhaust amount Aa is exhausted), the inverter The control signal S3c is output to the circuit 3c to stop the supply of the electric power P2c to the vacuum pump 2c, thereby stopping the vacuum pump 2c (an example of “one of L exhaust devices”) and the inverter circuit 3a. , 3b to output the control signals S3a, S3b to increase the frequency of the electric power P2a, P2b supplied to the vacuum pumps 2a, 2b, thereby changing the rotation speed of the vacuum pumps 2a, 2b that are continuously operated. 5% of the rotational speed is increased to the 82.5% rotational speed (an example of a "second process").

  In this case, in the exhaust amount reduction process, the vacuum pump 2c is stopped when it is necessary to reduce the exhaust amount in a state where L = 3 vacuum pumps 2a to 2c are operating at a rotation speed of 55%. In the exhaust system 1 of the example, as compared with the exhaust system 1x developed by the applicant, the vacuum pump 2c is controlled to operate in the range from the exhaust amount A1 to the exhaust amount Aa in the left diagram of FIG. The control range to be widened. Next, the control unit 5 outputs the control signals S3a and S3b to the inverter circuits 3a and 3b according to the required exhaust amount, and decreases the frequency of the electric power P2a and P2b supplied to the vacuum pumps 2a and 2b. As a result, the rotational speed of the vacuum pumps 2a and 2b is reduced. As a result, the amount of air exhausted as a whole of the exhaust system 1 is further reduced.

  Further, in the exhaust system 1 of this example, when the control unit 5 reduces the amount of air exhausted in a state where M = 2 vacuum pumps 2a and 2b are operating, the rotation of both vacuum pumps 2a and 2b is performed. When the number of revolutions is higher than the number of revolutions of 50% (in FIG. 3, when the amount of air that is less than the displacement Aa and larger than the displacement A2 is exhausted), the vacuum pumps 2a and 2b Without stopping both, the vacuum pumps 2a, 3b are equally reduced by outputting the control signals S3a, S3b to the inverter circuits 3a, 3b and reducing the frequency of the electric power P2a, P2b supplied to the vacuum pumps 2a, 2b equally. Further, another example of the control of reducing the rotational speed of 2b equally (“when there are a plurality of operating exhaust apparatuses, all the rotational speeds of the exhaust apparatuses are controlled to the same rotational speed”). . As a result, the amount of air exhausted as a whole of the exhaust system 1 is further reduced.

  Further, when the control unit 5 reduces the amount of air exhausted in a state where M = 2 vacuum pumps 2a and 2b are in operation, both the vacuum pumps 2a and 2b (“L pre-designated exhausts”). It is another example of “apparatus”, and the rotation speed of L = 2) is 50% or less and the rotation speed is 30% as the “third rotation speed” when the number of operating units is two. At the time of high rotation (in FIG. 3, in a state where an amount of air less than the displacement A2 and larger than the displacement Ab is exhausted: “M units by operating M of the N exhaust devices” In another example of “the state in which air is exhausted with a smaller exhaust amount than the exhaust amount of air when the (M-1) bases of the exhaust devices of the above are operated at the second rotational speed” The control signals to the inverter circuits 3a and 3b without stopping any of the vacuum pumps 2a and 2b The frequency of the electric power P2a and P2b supplied to each vacuum pump 2a and 2b by outputting 3a and S3b is equally reduced, so that the number of rotations of the vacuum pumps 2a and 2b as “L exhaust devices” is reduced. (Equal to another example of the “first process” in which control is performed to control all the rotational speeds of the exhaust devices to the same rotational speed when there are a plurality of exhaust devices in operation). Yet another example). As a result, the amount of air exhausted as a whole of the exhaust system 1 is further reduced.

  Further, the control unit 5 rotates the vacuum pumps 2a and 2b as “L exhaust devices” when reducing the amount of air exhausted in a state where M = 2 vacuum pumps 2a and 2b are operating. When the number of revolutions is 30% as the “third revolution number” when the number of operating units is two (in FIG. 3, when the exhaust air Ab is exhausted), the inverter The control signal S3b is output to the circuit 3b to stop the supply of the electric power P2b to the vacuum pump 2b, thereby stopping the vacuum pump 2b (another example of “one of the L exhaust devices”) and the inverter By increasing the frequency of the electric power P2a supplied to the vacuum pump 2a by outputting the control signal S3a to the circuit 3a, the rotation speed of the vacuum pump 2a that is continuing the operation is reduced from 30% to 60%. rotation It is raised to (another example of the "second process").

  In this case, in the exhaust amount reduction process, the vacuum pump 2b is stopped when it is necessary to reduce the exhaust amount in a state where L = 2 vacuum pumps 2a and 2b are operating at a rotation speed of 30%. In the exhaust system 1 of the example, as compared with the exhaust system 1x developed by the applicant, the vacuum pump 2b is controlled to operate in the range from the exhaust amount A2 to the exhaust amount Ab in the left diagram of FIG. The control range to be widened. Next, the control unit 5 outputs the control signal S3a to the inverter circuit 3a according to the required displacement, and decreases the frequency of the power P2a supplied to the vacuum pump 2a, thereby rotating the rotation speed of the vacuum pump 2a Reduce. As a result, the amount of air exhausted as a whole of the exhaust system 1 is further reduced.

  In this case, although different from the exhaust system 1 of the present example, when the “third rotation speed” when the number of operating units is two is defined to be higher than the “first rotation speed”, the vacuum system The vacuum pump 2b is stopped before the rotation speed of the pumps 2a and 2b is reduced to 30%. Therefore, when such a configuration is adopted, the exhaust amount range to be controlled so that both the vacuum pumps 2a and 2b are operated is the exhaust amount from the exhaust amount Aa to the exhaust amount Ab in the above example. It becomes a range narrower than the range, and the displacement range to be controlled in a state where the vacuum pump 2b is stopped becomes wider than in this example. Accordingly, when it is necessary to increase the amount of air exhausted, only one vacuum pump 2a is operating, that is, the operation of another vacuum pump 2 must be started to increase the amount of exhaust. As a result of the increase in the frequency of being unable to perform such a state, there is a risk that it may take a long time before the air can be exhausted with a necessary exhaust amount.

  On the other hand, in the exhaust system 1 of this example, as described above, when the number of operating units is two, the “third rotation number” is equal to the “first rotation number” (in this example, 30%). Therefore, in the exhaust system 1 of the present example, when the “third rotation speed” when the number of operating units is two is defined to be higher than the “first rotation speed” (the rotation speeds of the vacuum pumps 2a and 2b). Unlike the configuration in which the vacuum pump 2b is stopped before the pressure decreases to 30%), a plurality of vacuum pumps 2 (in this example, the vacuum pump 2) covers a sufficiently wide exhaust amount range from the exhaust amount Aa to the exhaust amount Ab. The state in which the pumps 2a, 2b) are operating can be maintained. For this reason, when it becomes necessary to increase the exhaust amount of air in a state where the air is exhausted within the range from the exhaust amount Aa to the exhaust amount Ab, as will be described later, the vacuum pumps 2a, 2b which are not in the stopped state are described later. It is possible to increase the exhaust amount quickly without requiring a long time until the required exhaust amount can be exhausted by increasing the rotational speed of the engine within the range where the upper limit is 100%. It has become.

  In the exhaust amount reduction processing, when M = 3 vacuum pumps 2a to 2c are operating and L = M = the number of vacuum pumps 2a to 2c is three and the number of operating units is three. The process of stopping the vacuum pump 2c among the three vacuum pumps 2a to 2c is executed as the "second process" at 55% of the "third rotation number" In the state where M = 3 vacuum pumps 2a to 2c are operating, focusing on the number of rotations of L = 2 vacuum pumps 2a and 2b, Any one of L = 2 vacuum pumps 2a, 2b and L = 2 vacuum pumps 2a, 2b other than the vacuum pumps 2a, 2b when the rotation speed is 55% The process of stopping the operation of the process is executed as a “second process” or M = 3 vacuum pumps 2 ˜2c is in operation, paying attention to the rotation speed of L = 1 vacuum pump 2a, and when this rotation speed is 55%, L = 1 vacuum pump 2a and L = A process of stopping the operation of one of the vacuum pumps 2b and 2c other than the single vacuum pump 2a can be executed as a “second process”.

  Similarly, in the exhaust amount reduction process, when M = 2 vacuum pumps 2a and 2b are operating, the number of rotations of L = M = 2 vacuum pumps 2a and 2b is 2 units. The process of stopping the vacuum pump 2b of the L = 2 vacuum pumps 2a and 2b is executed as the "second process" when the rotation speed is 30%, which is the "third rotation speed" In the state in which M = 2 vacuum pumps 2a and 2b are operating, attention is paid to the rotation speed of L = 1 vacuum pump 2a. The process of stopping the operation of L = 1 vacuum pump 2a and any vacuum pump 2b other than L = 1 vacuum pump 2a at the rotation speed of 30% is referred to as “second process”. Can be executed.

  Further, the control unit 5 is in a state in which only the vacuum pump 2a is operating and the rotation speed of the vacuum pump 2a is 30% as the "first rotation speed" (in FIG. When it is necessary to further reduce the amount of air exhausted (for example, when it is no longer necessary to exhaust air because the exhaust target is stopped), control is performed by the inverter circuit 3a. By maintaining the frequency of the electric power P2a supplied to the vacuum pump 2a by outputting the signal S3a, the state in which the vacuum pump 2a is operated at the rotation speed of 30% as the “third rotation speed” is maintained. At this time, since the vacuum pumps 2b and 2c are stopped and the vacuum pump 2a is operating at a rotation speed of 30%, the vacuum pressure in the connecting pipe 6 becomes excessively high. As a result, the connection pipe 6 is maintained in a vacuum state, so that exhaust from the exhaust target can be started immediately when the load increases.

  On the other hand, when the vacuum pump 2a operates at a rotation speed of 30% and the vacuum pumps 2b and 2c are stopped, it becomes necessary to exhaust air (for example, when the operation of the exhaust system 1 starts or stops) When the operation of the exhaust target in the state is resumed and the vacuum pressure in the connection pipe 6 is reduced to a vacuum pressure lower than the vacuum pressure within the allowable range with respect to the target vacuum pressure), the control unit 5 By executing the increase process and outputting the control signal S3a to the inverter circuit 3a, the rotational speed of the vacuum pump 2a is increased according to the required exhaust amount as shown in the right diagram of FIG.

  Specifically, the controller 5 determines that the vacuum pressure in the connection pipe 6 specified based on the sensor signal S4 from the pressure sensor 4 is lower than the vacuum pressure within the allowable range for the target vacuum pressure. When specified (when it is necessary to further increase the displacement), the vacuum pumps 2b and 2c are stopped and the rotational speed of the operating vacuum pump 2a is 100% as the "fourth rotational speed". When the rotation speed is lower than the rotation speed (when the air is exhausted within the range from the exhaust amount Ba to the exhaust amount Bb in FIG. 3), the operation of the vacuum pumps 2b and 2c in the stopped state is started. In addition, by outputting the control signal S3a to the inverter circuit 3a and increasing the frequency of the electric power P2a supplied to the vacuum pump 2a, the rotation speed is lower than 100% as the “fourth rotation speed”. Working It increases the rotational speed of the vacuum pump 2a (an example of the "third process"). Thereby, the exhaust amount of the air as the whole exhaust system 1 increases.

  At this time, although different from this example, in the above-described exhaust amount reduction processing, when the vacuum pump 2a is stopped when the required exhaust amount is less than the exhaust amount Ac, the load is subsequently increased. The operation of the vacuum pump 2a is resumed when it becomes necessary to increase the exhaust amount. However, since it is difficult to exhaust a sufficient amount of air until the number of rotations of the vacuum pump 2a in a stopped state increases to a certain number of rotations (30% rotation number), it corresponds to the increase in load. It becomes difficult to increase the displacement quickly. On the other hand, in the exhaust system 1 of the present example, as described above, even when the required exhaust amount is less than the exhaust amount Ac, the state in which the vacuum pump 2a is operated at the rotation speed of 30% is maintained. Therefore, it is possible to quickly increase the exhaust amount to a required amount only by increasing the rotational speed of the vacuum pump 2a in response to an increase in load.

  Further, the vacuum pumps 2b and 2c are in a stopped state, and the rotation speed of the vacuum pump 2a in operation (an example of “all the rotation speeds of the exhaust device in operation”) is 100 as the “fourth rotation speed”. When it is necessary to further increase the exhaust amount in the state of the rotational speed of% (the state in which air is exhausted with the exhaust amount Bb in the figure), the control unit 5 outputs the control signal S3b to the inverter circuit 3b. By starting the supply of electric power P2b to the vacuum pump 2b, the vacuum pump 2b that has been stopped is started to operate at a rotation speed of 50%, and a control signal S3a is output to the inverter circuit 3a to generate a vacuum. By reducing the frequency of the electric power P2a supplied to the pump 2a, the number of revolutions of the vacuum pump 2a that has been operating at 100% number of revolutions is reduced to 50% ("fourth process"). One example).

  Next, the control unit 5 outputs the control signals S3a and S3b to the inverter circuits 3a and 3b according to the required exhaust amount without starting the operation of the vacuum pump 2c in the stopped state, and outputs the vacuum pumps 2a and 2b. The rotation speeds of the vacuum pumps 2a and 2b are equally increased by equally increasing the frequencies of the electric power P2a and P2b supplied to the power supply (this is another example of the “third process” and “ Another example of control that “when a plurality of exhaust devices are present, all the rotational speeds of the exhaust devices are controlled to the same rotational speed”). Thereby, the exhaust amount of the air as the whole exhaust system 1 further increases from the exhaust amount Bb to the exhaust amount Bc.

  Furthermore, the vacuum pump 2c is in a stopped state, and all the operating vacuum pumps 2a and 2b are operating at a rotation speed of 100% as the “fourth rotation speed” (in FIG. When it is necessary to further increase the displacement in the state where the air is being exhausted), the control unit 5 outputs the control signal S3c to the inverter circuit 3c to start the supply of the power P2c to the vacuum pump 2c. As a result, the stopped vacuum pump 2c starts operating at a rotational speed of about 66.7%, and the control signals S3a and S3b are output to the inverter circuits 3a and 3b and supplied to the vacuum pumps 2a and 2b. By reducing the frequency of the electric power P2a and P2b to be reduced, the rotation speed of the vacuum pumps 2a and 2b that were operated at 100% rotation speed is reduced to about 66.7% respectively. To (another example of the "fourth process").

  Next, the control unit 5 outputs the control signals S3a to S3c to the inverter circuits 3a to 3c according to the required exhaust amount, and equally increases the frequency of the electric power P2a to P2c supplied to the vacuum pumps 2a to 2c. To increase the rotational speeds of the vacuum pumps 2a to 2c equally (this is still another example of the “third process”, and “when there are a plurality of operating exhaust devices, all of the exhaust devices are Still another example of control of “controlling the number of rotations to the same number of rotations”). Thereby, the exhaust amount of the air as the whole exhaust system 1 further increases from the exhaust amount Bc to the exhaust amount BM.

  In this case, although different from the exhaust system 1 of this example, the rotation speed of the vacuum pump 2a is reduced to 100% by defining the “fourth rotation speed” to be lower than the “second rotation speed”. When the configuration / method for starting the operation of the vacuum pump 2b before it rises is adopted, the exhaust amount range in which the exhaust amount should be adjusted with the vacuum pump 2b stopped is the exhaust amount B0 (Ba) in the above example. The exhaust amount range from to the exhaust amount Bb is narrower than the exhaust amount range, and the exhaust amount range to be controlled so that the vacuum pump 2b is operated is wider than the control example of this example. Further, as described above, it is difficult for a “rotational speed variable exhaust device” such as the vacuum pump 2 to exhaust a sufficient amount of air until the rotational speed increases to some extent. Therefore, when the “fourth rotational speed” is defined to be lower than the “second rotational speed”, the operation of the vacuum pump 2b in the stopped state is caused when it is necessary to increase the air exhaust amount. Therefore, there is a risk that the frequency of incurring a situation that requires a certain amount of time before the air can be exhausted with a necessary exhaust amount may be increased.

  Similarly, by defining the “fourth rotational speed” to be lower than the “second rotational speed”, the operation of the vacuum pump 2c before the rotational speed of the vacuum pumps 2a and 2b increases to 100%. When the configuration / method for starting the engine is employed, the exhaust amount range in which the exhaust amount should be adjusted while the vacuum pump 2c is stopped is the exhaust amount range from the exhaust amount B0 (Ba) to the exhaust amount Bc in the above example. The exhaust amount range to be controlled in a state where the vacuum pump 2c is operated becomes wider than the control example of this example. Therefore, when the “fourth rotational speed” is defined to be lower than the “second rotational speed”, the operation of the vacuum pump 2c in the stopped state is caused when it is necessary to increase the air exhaust amount. Therefore, there is a risk that the frequency of incurring a situation that requires a certain amount of time before the air can be exhausted with a necessary exhaust amount may be increased.

  On the other hand, in the exhaust system 1 of the present example, as described above, the “fourth rotational speed” is defined as the rotational speed equal to the “second rotational speed” (in this example, 100% rotational speed). Has been. Therefore, in the exhaust system 1 of this example, unlike the case where the “fourth rotational speed” is defined to be lower than the “second rotational speed”, a sufficient amount from the exhaust amount B0 (Ba) to the exhaust amount Bb is sufficient. The state in which the operation of the vacuum pump 2b is stopped over a wide exhaust amount range can be maintained, and the vacuum pump over a sufficiently wide exhaust amount range from the exhaust amount B0 (Ba) to the exhaust amount Bc. The state in which the operation of 2c is stopped can be maintained.

  For this reason, when it becomes necessary to increase the amount of air exhausted in a state where the vacuum pump 2b is stopped by the above-described exhaust amount reduction processing, the rotation speed of the vacuum pump 2a is started without starting the operation of the vacuum pump 2b. It is necessary to increase the amount of air exhausted in a state where the vacuum pump 2c is stopped, and the exhaust amount range for controlling air to be exhausted from the exhaust target with a necessary amount of exhaust only by raising In this case, the exhaust amount range for controlling the exhaust air to be exhausted from the exhaust target with a necessary exhaust amount only by increasing the rotational speed of the vacuum pumps 2a and 2b without starting the operation of the vacuum pump 2c is sufficient. Since it is wide, the frequency with which it is necessary to start the operation of the vacuum pump 2b and the vacuum pump 2c in a stopped state is reduced, and the air can be exhausted with a necessary exhaust amount. In it is possible to rapidly increase the amount of exhaust without requiring a long time.

  In order to facilitate understanding of the operating principle of the exhaust system 1, the amount of air exhausted by the exhaust system 1 is gradually reduced from the exhaust amount AM to the exhaust amount Ac (A0), and then the exhaust amount is reduced. Although the control procedure (the procedure for changing the operating state) of each vacuum pump 2a to 2c by the control unit 5 when gradually increasing from Ba (B0) to the exhaust amount BM has been described, actually, the exhaust amount reducing process is executed The exhaust amount increasing process is executed before the exhaust amount is reduced to the exhaust amount A0, or the exhaust amount reducing process is executed before the exhaust amount is increased to the exhaust amount BM during the execution of the exhaust amount increasing process. To do.

  In this case, in the exhaust system 1x developed by the applicant, the exhaust amount is increased in a state where the air is exhausted with the exhaust amount reduced to any of the amounts in the left diagram of FIG. 7 by executing the exhaust amount reduction process. When the necessity arises, the exhaust amount increasing process is started in a manner corresponding to the exhaust amount at that time in the right figure. Further, in the exhaust system 1x developed by the applicant, it is necessary to reduce the exhaust amount in a state where the air is exhausted with the exhaust amount increased to any one of the right figure by executing the exhaust amount increasing process. Sometimes, the exhaust amount reduction process is started in a manner corresponding to the exhaust amount at that time in the left figure.

  In this case, in this type of exhaust system, the load fluctuates little by little according to the operating state of the exhaust target. Therefore, in the exhaust system 1x developed by the applicant, it is necessary to exhaust air with, for example, the exhaust amounts Aax and Bcx in order to set the vacuum pressure in the connection pipe 6 within the allowable range with respect to the target vacuum pressure. There is a need to control the vacuum pump 2cx to stop when the load slightly decreases with a change in the operating state of the exhaust target, and to start the operation of the vacuum pump 2cx when the load increases slightly. There is a current situation that the frequency of starting the operation of the vacuum pump 2cx is increased. Similarly, in order to set the vacuum pressure in the connection pipe 6 to a vacuum pressure within an allowable range with respect to the target vacuum pressure, for example, when it is necessary to exhaust air at the exhaust amount Abx, Bbx, It is necessary to control the vacuum pump 2bx to stop when the load slightly decreases along with the change of the operating state, and to start the operation of the vacuum pump 2bx when the load increases slightly. There is a current situation that the frequency of making it increase.

  On the other hand, in the exhaust system 1 of this example, the load increases and the vacuum pressure decreases after the control for reducing the exhaust amount is performed within the range from the exhaust amount AM to the exhaust amount A1 in the left diagram of FIG. When it is necessary (when it is necessary to increase the exhaust amount), the exhaust that increases the rotational speed of the vacuum pumps 2a to 2c in a mode from the exhaust amount Bc to the exhaust amount BM shown in the right diagram of FIG. A volume increase process is performed. In addition, when the load increases and the vacuum pressure decreases after the control for reducing the exhaust amount is performed within the range from the exhaust amount A1 to the exhaust amount Aa in the left figure (when it is necessary to increase the exhaust amount) ) Includes an exhaust amount increase process (in operation) in which the number of rotations of the vacuum pumps 2a to 2c is increased in a range from the exhaust amount B2 (Aa) to the exhaust amount Bc (A1) shown in the left diagram of FIG. The control is performed to increase the exhaust amount without stopping the vacuum pumps 2a to 2c), and then the vacuum pumps 2a to 2c are controlled in a manner within the range from the exhaust amount Bc to the exhaust amount BM shown in the right diagram of FIG. Exhaust amount increase processing for increasing the rotational speed is performed. Therefore, in this exhaust system 1, when the exhaust amount is increased from the range from the exhaust amount AM to the exhaust amount Aa, it is possible to maintain the state in which the vacuum pumps 2a to 2c are operated.

  Furthermore, when the load increases and the vacuum pressure decreases after the control for reducing the exhaust amount is performed within the range from the exhaust amount Aa to the exhaust amount A2 in the left diagram of FIG. 3 (the exhaust amount needs to be increased). When it occurs), an exhaust amount increasing process for increasing the rotational speed of the vacuum pumps 2a and 2b is performed in a manner within the range from the exhaust amount Bb to the exhaust amount B2 shown in the right figure. In addition, when the load increases and the vacuum pressure decreases after the control for reducing the exhaust amount is performed within the range from the exhaust amount A2 to the exhaust amount Ab in the left figure (when it is necessary to increase the exhaust amount) ) Includes an exhaust amount increasing process (in operation) in which the number of rotations of the vacuum pumps 2a and 2b is increased in a manner within the range from the exhaust amount B1 (Ab) to the exhaust amount Bb (A2) shown in the left diagram of FIG. The control is performed to increase the exhaust amount without stopping the vacuum pumps 2a and 2b), and then the vacuum pumps 2a and 2b are controlled in a manner within the range from the exhaust amount Bb to the exhaust amount B2 shown in the right diagram of FIG. Exhaust amount increase processing for increasing the rotational speed (control for increasing the exhaust amount without stopping the operating vacuum pumps 2a and 2b) is performed. Therefore, in the exhaust system 1, when the exhaust amount is increased from the range from the exhaust amount Aa to the exhaust amount Ab, it is possible to maintain the state in which the vacuum pumps 2a and 2b are operated.

  Furthermore, in the exhaust system 1 of the present example, for example, the control is performed to increase the exhaust amount within the range from the exhaust amount Ba (B0) to the exhaust amount B1 in the right diagram of FIG. When the pressure rises (when it is necessary to reduce the displacement), the number of rotations of the vacuum pump 2a is in a mode within the range from the displacement amount Ab to the displacement amount Ac (A0) shown in the left diagram of FIG. Exhaust amount reduction processing is performed to reduce the above. Further, when the load is reduced and the vacuum pressure is increased after the control for increasing the exhaust amount is performed within the range from the exhaust amount B1 to the exhaust amount Bb in the right figure (when it is necessary to reduce the exhaust amount) ) Includes an exhaust amount reduction process for reducing the rotational speed of the vacuum pump 2a in a mode within the range from the exhaust amount A2 (Bb) to the exhaust amount Ab (B1) shown in the right diagram of FIG. 2b and 2c is controlled to reduce the exhaust amount without starting the operation), and thereafter, the vacuum pump 2a is in a mode within the range from the exhaust amount Ab to the exhaust amount Ac (A0) shown in the left diagram of FIG. Exhaust amount reduction processing is performed to reduce the rotational speed. Therefore, in the exhaust system 1, when the exhaust amount is reduced from the range from the exhaust amount Ba (B0) to the exhaust Bb, it is possible to maintain the state where the vacuum pumps 2b and 2c are stopped. .

  Further, when the load is reduced and the vacuum pressure is increased after the control for increasing the exhaust amount is performed within the range from the exhaust amount Bb to the exhaust amount B2 in the right diagram of FIG. 3 (the exhaust amount needs to be reduced). When it occurs), an exhaust amount reduction process for reducing the rotational speed of the vacuum pumps 2a and 2b is performed in a mode from the exhaust amount Aa to the exhaust amount A2 shown in the left figure. Also, when the load is reduced and the vacuum pressure is increased after the control for increasing the exhaust amount is performed within the range from the exhaust amount B2 to the exhaust amount Bc in the right figure (when it is necessary to reduce the exhaust amount) ) Includes an exhaust amount reduction process for reducing the number of revolutions of the vacuum pumps 2a and 2b in a mode within the range from the exhaust amount A1 (Bc) to the exhaust amount Aa (B2) shown in the right diagram of FIG. The control of reducing the exhaust amount without starting the operation of the vacuum pump 2c) is performed, and then the vacuum pumps 2a and 2b are operated in a manner within the range from the exhaust amount Aa to the exhaust amount A2 shown in the left diagram of FIG. Exhaust amount reduction processing for reducing the rotational speed (control to reduce the exhaust amount without starting the operation of the stopped vacuum pump 2c) is performed. Therefore, in the exhaust system 1, when the exhaust amount is reduced from the range from the exhaust amount Bb to the exhaust amount Bc, it is possible to maintain the state where the vacuum pump 2c is stopped.

  As described above, in the exhaust system 1 and the exhaust device control method in the exhaust system 1, (M−1) of the M vacuum pumps 2 are operated by operating M of the N vacuum pumps 2. When reducing the amount of air exhausted in a state where the air is exhausted by a smaller exhaust amount than the amount of air exhausted when the table is operated at the “second rotational speed”, the M vacuum pumps 2 When the rotation speed of the L vacuum pumps 2 designated in advance is higher than the “third rotation speed”, at least L vacuum pumps 2 are not stopped without stopping the M vacuum pumps 2. The “first process” for reducing the number of rotations is executed as the exhaust amount reduction process, and when the number of rotations of the L predetermined vacuum pumps 2 is the “third number of rotations”, the L vacuum pumps 1 of 2 and L vacuum pumps 2 Stop one of the external vacuum pumps 2 operating at the “third rotational speed” and increase the rotational speed of at least one of the vacuum pumps 2 that continue to operate. The “second process” to be performed is executed as the exhaust amount reduction process.

  Therefore, according to the exhaust system according to claim 1 and the exhaust device control method according to claim 9, the rotation speed of the vacuum pump 2 corresponding to “L pre-specified exhaust devices” in the exhaust amount reduction processing. The operation state is maintained without stopping the operating vacuum pump 2 until the operation state of “the third rotation speed” is reached, so that the total exhaust amount by the vacuum pumps 2ax to 2cx is the vacuum pump. The vacuum pump 2cx is stopped when the total displacement is equal to the total displacement when 2ax and 2bx are operated at 100%, and the total displacement of the vacuum pumps 2ax and 2bx is 100% of the vacuum pump 2ax The vacuum pump 2c and the vacuum pump 2b are operated in comparison with the configuration and method in which the vacuum pump 2bx is stopped when the displacement becomes equal to the displacement when the engine is operated at the number of revolutions. When it is necessary to increase the exhaust amount range to be controlled, that is, when the exhaust amount needs to be increased, the exhaust amount is increased only by increasing the number of rotations of the vacuum pump 2c and the vacuum pump 2b in which the operated state is maintained. Since the control range that can be widened can be sufficiently widened, the frequency at which a certain amount of time is required until the air can be exhausted with the required exhaust amount is reduced to the required amount. The displacement can be increased quickly.

  Further, according to the exhaust system 1 and the exhaust device control method in the exhaust system 1, when the number of operating the vacuum pumps 2 is M = 2 (in the above example, when the vacuum pumps 2a and 2b are operating). ) Is defined to be equal to the "first rotation speed" (30% rotation speed in this example). Since the state in which the vacuum pump 2b is operated is maintained until the rotational speed decreases to the “first rotational speed” defined as the lower limit of the rotational speed of the “exhaust device” mounted in the exhaust system 1, Compared to the configuration / method in which the “third rotation speed” is defined to be higher than the “first rotation speed”, it takes a certain amount of time to exhaust the air with the required exhaust amount. Reduce the frequency further to the required amount. The exhaust amount can be increased more rapidly.

  Further, in the exhaust system 1 and the exhaust device control method in the exhaust system 1, when increasing the amount of air exhausted, at least one of the vacuum pumps 2 is in a stopped state and out of operating vacuum pumps 2 When the rotation speed of at least one of the two is lower than the “fourth rotation speed”, the operation of the vacuum pump 2 in a stopped state is started at a lower rotation speed than the “fourth rotation speed”. The “third process” for increasing the rotational speed of the vacuum pump 2 is executed as the exhaust amount increasing process, and at least one of the vacuum pumps 2 is stopped and all of the vacuum pumps 2 in operation are in operation. When the rotation speed is the “fourth rotation speed”, the operation of one of the stopped vacuum pumps 2 is started, and the rotation speed of at least one of the operating vacuum pumps 2 is decreased. 4th To perform the management "as the exhaust amount increase processing.

  Therefore, according to the exhaust system 1 and the exhaust device control method in the exhaust system 1, the exhaust amount for stopping the vacuum pump 2 during the exhaust amount reduction process (in this example, the exhaust amounts Aa and Ab in the embodiment of FIG. 3) Since the exhaust amount (in this example, the exhaust amounts Bb and Bc in the embodiment of FIG. 3) for starting the operation of the vacuum pump 2 in the exhaust amount increasing process is different, the exhaust amount is about the same as these exhaust amounts. As a result, it is possible to preferably avoid the situation where the control for stopping the vacuum pump 2 and the control for starting the operation of the vacuum pump 2 are repeatedly executed in small increments when the exhaust gas is to be exhausted. With this, it is possible to further reduce the frequency at which a certain amount of time is required until the air can be exhausted, and to increase the exhaust amount more quickly to the required amount.

  Further, according to the exhaust system 1 and the exhaust device control method in the exhaust system 1, all of the “fourth rotational speeds” for each operation number are specified to be equal to the “second rotational speed”. Thus, in the exhaust amount increase process, the vacuum pump 2 is stopped until the rotational speed increases to the “second rotational speed” defined as the upper limit of the rotational speed of the “exhaust device” mounted in the exhaust system 1. Since the state where the vacuum pump 2 is stopped is maintained, the vacuum pump in the stopped state is compared with the configuration / method in which the “fourth rotational speed” is defined to be lower than the “second rotational speed”. Since the frequency of starting the operation of 2 is further reduced, the exhaust amount can be increased more rapidly to the required amount.

  Further, according to the exhaust system 1 and the exhaust device control method in the exhaust system 1, when there are a plurality of vacuum pumps 2 operating at a higher speed than the “third rotational speed” in the exhaust amount reduction process. In addition, by reducing the respective rotational speeds of the vacuum pumps 2 operating at a higher speed than the “third rotational speed”, the stress applied to the vacuum pumps 2 during the exhaust processing can be made substantially equal. Therefore, it is possible to avoid a situation in which the useful life of any one of the vacuum pumps 2 is significantly reduced compared to any other.

  Further, according to the exhaust system 1 and the exhaust device control method in the exhaust system 1, when there are a plurality of operating vacuum pumps 2 in the exhaust amount reduction processing and the exhaust amount increase processing, the rotation of each vacuum pump 2 is rotated. Configuration and method for controlling so that only one of the other rotational speeds is changed while fixing the rotational speed of each of the vacuum pumps 2 to a constant rotational speed by controlling the number to the same rotational speed In addition, the operation state of each vacuum pump 2 can be easily changed according to the required exhaust amount as compared with a configuration / method in which the rotation speed of each vacuum pump 2 is controlled to be different from each other. it can.

  Further, according to the exhaust system 1 and the exhaust device control method in the exhaust system 1, the vacuum pressure in the connection pipe 6 is specified based on the sensor signal S4 output from the pressure sensor 4, and the specified vacuum pressure is determined. When the pressure rises to a vacuum pressure higher than the vacuum pressure within the preset vacuum pressure range, it is determined that the load has decreased, the exhaust amount reduction process is executed, and the specified vacuum pressure is set to the preset vacuum pressure. It is determined that the load has increased when the vacuum pressure is lower than the vacuum pressure within the range, and the exhaust amount increasing process is executed, so that the load amount can be reliably and easily specified to exhaust the air by the exhaust system 1. The amount can be precisely adjusted to the required displacement.

  Further, according to the exhaust system 1 and the exhaust device control method in the exhaust system 1, only the vacuum pump 2a is operating, and the rotation speed of the vacuum pump 2a is 30% as the "third rotation speed". When the load decreases in the state of the number of rotations, when the vacuum pump 2a is kept operating at the number of rotations of 30%, it is necessary to increase the load and increase the displacement. Since the amount of exhaust can be increased only by increasing the number of rotations of the vacuum pump 2a that continues to operate, the amount of exhaust can be increased more rapidly to the required amount.

  The configuration of the “exhaust system” and the specific contents of the “exhaust device control method” are not limited to the configuration of the exhaust system 1 and the example of the control method of the vacuum pumps 2 a to 2 c in the exhaust system 1. . For example, when there are a plurality of vacuum pumps 2 in operation in the exhaust amount reduction process and the exhaust amount increase process, the control for decreasing the number of rotations of each vacuum pump 2 and the control for increasing the number of vacuum pumps 2 (in this example, (Execution of control for setting the respective rotation speeds of the vacuum pump 2 to the same rotation speed), in place of such a configuration and method, the exhaust amount reduction processing of the aspect shown in the left diagram of FIG. A configuration and method for executing the exhaust amount increasing process shown in the right figure can be employed.

  In this case, in the aspect relating to the method for controlling the rotational speed of the vacuum pumps 2a to 2c shown in the figure, during the exhaust amount reduction process, when the exhaust amount is within the range from the exhaust amount AM to the exhaust amount Aa in the left diagram, "N 100 is a “second rotational speed” with the rotational speed of one of the vacuum pumps 2 a to 2 c (in this example, the vacuum pump 2 a) corresponding to the “exhaust device of the base” as the “fourth rotational speed”. Control (first process) is performed to gradually reduce the rotational speed of the vacuum pumps 2b and 2c in accordance with the required exhaust amount while maintaining the rotational speed at%.

  Further, the vacuum pumps 2b and 2c as “L pre-specified exhaust devices” are operating at a rotation speed of 30% which is a “first rotation speed” as a “third rotation speed”. When it is necessary to further reduce the exhaust amount in a state where the air is exhausted in the state of the exhaust amount Aa, the vacuum pump 2c as “one of the L exhaust devices” is stopped and the vacuum is reduced. Control (second process) is performed to reduce the rotation speed of the pump 2a to 80% and increase the rotation speed of the vacuum pump 2b to 80%, and then the vacuum pumps 2a and 2b are executed. Is controlled so as to be gradually reduced in accordance with the required exhaust amount (range from the exhaust amount Aa to the exhaust amount Ab). When the exhaust amount is within the range from the exhaust amount Ab to the exhaust amount Ac (A0), the same control as that shown in the left diagram of FIG.

  In the mode of FIG. 5, in the exhaust amount increasing process, when the exhaust amount is within the range from the exhaust amount Bc to the exhaust amount BM in the right diagram, the vacuum pumps 2 a to 2 c corresponding to “N exhaust devices”. The vacuum pump 2b, while maintaining the rotation speed of one of the two (in this example, the vacuum pump 2a) at the rotation speed of 100% that is the “second rotation speed” as the “fourth rotation speed” Control (third process) for gradually increasing the rotational speed of 2c according to the required exhaust amount is executed. When the exhaust amount is within the range from the exhaust amount Ba (B0) to the exhaust amount Bc, the same control as that shown in the right diagram of FIG.

  In this case, in the exhaust amount reduction process, the vacuum pump 2c is stopped when it is necessary to reduce the exhaust amount in a state where the rotational speed of the vacuum pumps 2b and 2c is 30%. Compared to the exhaust system 1x developed by the applicant, the control range for controlling the vacuum pump 2c to operate is widened by the range from the exhaust amount A1 to the exhaust amount Aa in FIG.

  Further, in the example of the rotational speed control shown in FIG. 5 as well, in the same manner as the above-described example of the rotational speed control described with reference to FIGS. 3 and 4, within the range from the exhaust amount Aa to the exhaust amount Ab in the left diagram. Operation of the vacuum pumps 2a to 2c in a mode (rotational speed control for increasing the exhaust amount from the exhaust amount Ab to the exhaust amount Aa) different from the exhaust amount increasing process in the right figure when it is necessary to increase the exhaust amount from The state is controlled. Further, when it becomes necessary to increase the exhaust amount from within the range from the exhaust amount Ab to the exhaust amount Ac in the left diagram, an aspect different from the exhaust amount increasing process in the right diagram (exhaust from the exhaust amount Ac to the exhaust amount Ab) The operation state of the vacuum pumps 2a to 2c is controlled by a rotation speed control for increasing the amount).

  Similarly, when it becomes necessary to reduce the exhaust amount from within the range from the exhaust amount Ba to the exhaust amount Bb in the right diagram of FIG. 5, a mode different from the exhaust amount increasing process of the left diagram (from the exhaust amount Bb). The operation state of the vacuum pumps 2a to 2c is controlled by a rotational speed control that reduces the exhaust amount to the exhaust amount Ba. Further, when it becomes necessary to reduce the exhaust amount from within the range from the exhaust amount Bb to the exhaust amount Bc in the right diagram, an aspect different from the exhaust amount increasing process in the left diagram (exhaust from the exhaust amount Bc to the exhaust amount Bb) The operation state of the vacuum pumps 2a to 2c is controlled by the rotational speed control for reducing the amount.

  According to the exhaust system configured as described above and the exhaust device control method in the exhaust system, there are a plurality of vacuum pumps 2 operating at a higher speed than the “third rotational speed” in the exhaust amount reduction process. Sometimes the rotation speed of at least one of the plurality of vacuum pumps 2 operating at a higher speed than the “third rotation speed” is reduced without changing the rotation speed of at least one other pump pump 2. Thus, for example, unlike the configuration / method of controlling the rotation speed of each vacuum pump 2 to be different from each other, one of the vacuum pumps 2 is fixed at a constant rotation speed. However, since only one of the other rotational speeds needs to be changed, the operation state of each vacuum pump 2 can be easily changed according to the required exhaust amount.

  Further, it is possible to adopt a configuration / method for executing the exhaust amount reduction process of the aspect shown in the left diagram of FIG. 6 and the exhaust amount increase process of the right diagram. In this case, in the aspect relating to the method for controlling the rotational speed of the vacuum pumps 2a to 2c shown in the figure, during the exhaust amount reduction process, when the exhaust amount is within the range from the exhaust amount AM to the exhaust amount Aa in the left diagram, "N The number of rotations of two of the vacuum pumps 2a to 2c (in this example, vacuum pumps 2a and 2b) corresponding to the “base exhaust device” is “second number of rotations” as “fourth number of rotations”. Control (first process) is executed to gradually reduce the rotational speed of the vacuum pump 2c in accordance with the required exhaust amount while maintaining a certain rotational speed of 100%.

  In addition, the vacuum pump 2c as “L pre-designated exhaust devices” is operating at a rotation speed of 30% which is the “first rotation speed” as the “third rotation speed” (exhaust When it is necessary to further reduce the exhaust amount in a state where the air is exhausted in the state of the amount Aa), the rotation speed of the vacuum pump 2c is maintained at 30% and the rotation speed of the vacuum pump 2a is set to 100. %, The control (first process) for gradually decreasing the rotational speed of the vacuum pump 2b according to the required exhaust amount is executed (from the exhaust amount Aa to the exhaust amount Ab). range).

  Furthermore, the vacuum pump 2b as “L pre-designated exhaust devices” is operating at a rotation speed of 30% which is the “first rotation speed” as the “third rotation speed” (exhaust When it is necessary to further reduce the exhaust amount in a state where the air is exhausted in the state of the amount Ab), “one of the exhaust devices other than the L exhaust devices operating at the third rotational speed is used. The vacuum pump 2c is stopped and the rotation speed of the vacuum pump 2b is increased to 60% while maintaining the rotation speed of the vacuum pump 2a at 100% (second processing). Thereafter, control is performed to gradually reduce the rotational speed of the vacuum pump 2b in accordance with the required exhaust amount (range from the exhaust amount Ab to the exhaust amount Ac).

  In addition, the vacuum pump 2b as “L pre-designated exhaust devices” is operating at a rotation speed of 30% which is the “first rotation speed” as the “third rotation speed” (exhaust When it is necessary to further reduce the exhaust amount in a state where the air is exhausted in the state of the amount Ac), the rotation speed of the vacuum pump 2b is maintained at 30% and the rotation speed of the vacuum pump 2a is required. In accordance with the exhaust amount, a control for gradually decreasing is performed (range from the exhaust amount Ac to the exhaust amount Ad). When the exhaust amount is within the range from the exhaust amount Ad to the exhaust amount Ae (A0), the same control as the aspect within the range from the exhaust amount Ab to the exhaust amount Ac (A0) in the left diagram of FIG. 3 is executed. Therefore, the description is omitted.

  Further, in the mode of FIG. 6, in the exhaust amount increasing process, when the exhaust amount is in the range from the exhaust amount Bb to the exhaust amount Bc in the right diagram, the rotation speed of the vacuum pump 2 b is set to “third rotation speed”. The control (third process) for gradually increasing the rotation speed of the vacuum pump 2a according to the required exhaust amount is performed while maintaining the rotation speed of 30% that is the "first rotation speed" of The Further, the vacuum pump 2a is operated at a rotation speed of 100% which is the “second rotation speed” as the “fourth rotation speed” (air is exhausted in the state of the exhaust amount Bc). When it is necessary to further increase the exhaust amount in the state), the rotational speed of the vacuum pump 2b is gradually increased according to the required exhaust amount while maintaining the rotational speed of the vacuum pump 2a at 100%. Control to increase (third process) is executed (range from the exhaust amount Bc to the exhaust amount Bd).

  Further, the vacuum pump 2b is operating at a rotation speed of 100% which is the "second rotation speed" as the "fourth rotation speed" (air is exhausted in the state of the exhaust amount Bd). When it is necessary to further increase the amount of exhaust gas in the state), the vacuum pump 2c is started to operate at a rotation speed of 30%, the rotation speed is maintained at a rotation speed of 30%, and the rotation of the vacuum pump 2a is performed. Control (fourth process) is performed to reduce the rotational speed of the vacuum pump 2b to 70% while maintaining the rotational speed at 100%, and then the rotational speed of the vacuum pump 2b is required. A control for gradually increasing the exhaust gas according to the exhaust amount to be performed is performed (range from the exhaust amount Bd to the exhaust amount Be). Further, the vacuum pump 2b is operating at a rotation speed of 100% which is the “second rotation speed” as the “fourth rotation speed” (air is exhausted in the state of the exhaust amount Be). When the pumping amount needs to be further increased in a state where the vacuum pumps 2a and 2b are rotated at a rotation speed of 100%, the rotation speed of the vacuum pump 2c is adjusted according to the required exhaust amount. Control for gradually increasing (third process) is executed (range from the exhaust amount Be to the exhaust amount BM).

  According to the exhaust system configured as described above and the exhaust device control method in the exhaust system, there are a plurality of vacuum pumps 2 operating at a higher speed than the “third rotational speed” in the exhaust amount reduction process. Sometimes the rotation speed of at least one of the plurality of vacuum pumps 2 operating at a higher speed than the “third rotation speed” is reduced without changing the rotation speed of at least one other pump pump 2. Thus, for example, unlike the configuration / method of controlling the rotation speed of each vacuum pump 2 to be different from each other, one of the vacuum pumps 2 is fixed at a constant rotation speed. However, since only one of the other rotational speeds needs to be changed, the operation state of each vacuum pump 2 can be easily changed according to the required exhaust amount.

  Further, in the exhaust system 1 including N = 3 “exhaust devices” of the vacuum pumps 2 a to 2 c, the “first rotational speed” and the “second rotational speed” of the vacuum pumps 2 a to 2 c are equal to each other. Although the example prescribed | regulated to the rotation speed was demonstrated, "1st rotation speed" is a minimum of the rotation speed range for each "exhaust device", and "2nd rotation speed" is each "exhaust device". Since this is the upper limit of each rotation speed range, these rotation speeds can be defined as different rotation speeds for each “exhaust device”. Similarly, the “third rotation speed” is equal to or higher than the “first rotation speed” for each “exhaust device” and lower than the “second rotation speed” for each “exhaust device”. If so, it is possible to define different rotational speeds for each “exhaust device”, and the “fourth rotational speed” is also equal to or less than the “second rotational speed” for each “exhaust device”. In addition, if the rotation speed is higher than the “third rotation speed” for each “exhaust device”, it is possible to define a different rotation speed for each “exhaust device”.

  Furthermore, although the control part 5 gave and demonstrated the structure which specifies the magnitude | size of a load with the vacuum pressure in the piping 6 for a connection specified based on sensor signal S4 from the pressure sensor 4, the reduction | decrease and increase of load were demonstrated as an example. The configuration / method for detection is not limited to this. For example, the vacuum pressure in the connection pipe 6 is measured based on the sensor signal S4 from the pressure sensor 4, and the measurement result (vacuum pressure) or the measurement result is measured. A device (not shown) that outputs the specified load amount to the “exhaust system” is provided separately from the “exhaust system” to detect a decrease or increase in load, and output from the exhaust target. It is also possible to adopt a configuration / method for identifying a load applied to the “exhaust system” based on the “signal indicating the operating state”.

  Further, a configuration / method for controlling the number of revolutions of each vacuum pump 2 by changing the frequency of the electric power supplied from the inverter circuit 3 by adopting the vacuum pump 2 using an inverter control type motor as a power source will be given as an example. For example, a variable voltage control type “rotary speed variable exhaust device” that uses a motor whose rotational speed changes according to the voltage of the supplied power as a power source is adopted and supplied to the “exhaust device”. It is also possible to employ a configuration / method for controlling the rotational speed by changing the voltage of the power to be generated. In addition, an example in which only the “rotational speed variable exhaust device” is provided has been described, but in addition to N “variable rotational speed exhaust devices”, one or more than two units The "rotational speed fixed type exhaust device (exhaust device that operates at a constant rotational speed with the supply of electric power)" can also be configured (not shown).

DESCRIPTION OF SYMBOLS 1 Exhaust system 2a-2c Vacuum pump 3a-3c Inverter circuit 4 Pressure sensor 5 Control part 6 Connection piping 10 Exhaust amount adjustment process AM, Aa, Ab ... A0, B0, Ba, Bb ... BM exhaust amount P2a-P2c Electric power S3a to S3c Control signal S4 Sensor signal

Claims (11)

It is configured to be operable at a rotation speed between a first rotation speed specified in advance and a predetermined second rotation speed higher than the first rotation speed. N number of rotation speed variable type exhaust devices (N is a natural number of 2 or more) exhausting gas through
When the load decreases, the exhaust device operation state is changed to reduce the exhaust amount of the gas, and the exhaust amount reduction processing is executed. When the load increases, the exhaust device operation state is changed to change the gas An exhaust system including a control unit that maintains the vacuum pressure in the connection pipe at a vacuum pressure within a preset vacuum pressure range by executing an exhaust amount increase process for increasing the exhaust amount of
As the lower limit of the range in which the predetermined third rotational speed that is equal to or higher than the first rotational speed and lower than the second rotational speed changes the rotational speed of each exhaust device during the exhaust amount reduction processing Defined according to the number of operating exhaust systems when exhaust volume reduction processing is executed,
The control unit operates (M-1) of the M exhaust devices by operating M of the N exhaust devices (M is a natural number of 2 to N). The M exhaust devices are configured to be controllable to a plurality of unit operating states in which the gas is exhausted with an exhaust amount smaller than the exhaust amount of the gas when operated at a rotational speed of 2. When the exhaust amount of the gas is reduced in the operation state of a plurality of units, the number of rotations of the L exhaust units (L is a natural number equal to or less than M) of the M exhaust units is set to the first number. When the number of revolutions is higher than 3, the first exhaust gas reduction process is performed as the exhaust amount reduction process, without stopping the M exhaust units, and at least the first process of reducing the revolutions of the L exhaust units. The number of rotations of the L designated exhaust devices is the third number. In the case of the rotational speed, one of the L exhaust devices and one of the exhaust devices other than the L exhaust devices operating at the third rotational speed are stopped. And an exhaust system that executes a second process for increasing the rotational speed of at least one of the exhaust devices that is continuously operating as the exhaust amount reduction process.   2. The exhaust system according to claim 1, wherein the third rotational speed when the number of operating exhaust devices is M = 2 is defined as a rotational speed equal to the first rotational speed. The upper limit of the range in which the predetermined fourth rotational speed that is higher than the third rotational speed and equal to or lower than the second rotational speed changes the rotational speed of each exhaust device during the exhaust amount increasing process. It is defined according to the number of operating exhaust devices at the time of executing the exhaust amount increasing process,
When the control unit increases the exhaust amount of the gas, at least one of the exhaust devices is in a stopped state, and the rotational speed of at least one of the exhaust devices in operation is the fourth speed. When the rotational speed is lower than the rotational speed, the third rotational speed of the exhaust apparatus operating at a lower speed than the fourth rotational speed is increased without starting the operation of the exhaust apparatus in the stopped state. The process is executed as the exhaust amount increasing process, and when at least one exhaust device is in the stopped state and all the rotational speeds of the exhaust devices in operation are the fourth rotational speed, The fourth process of starting the operation of one of the exhaust devices and reducing the rotational speed of at least one of the exhaust devices in operation is executed as the exhaust amount increasing process. Exclusion of 2 System.   4. The exhaust system according to claim 3, wherein all of the fourth rotation speeds for each operation number are defined to be equal to the second rotation speed.   The control unit operates at a higher speed than the third rotational speed when there are a plurality of the exhaust devices operating at a higher speed than the third rotational speed in the exhaust amount reduction process. The exhaust system according to any one of claims 1 to 4, wherein all of the rotation speeds of the plurality of exhaust devices are decreased.   In the exhaust amount reduction process and the exhaust amount increase process, the control unit controls all the rotational speeds of the exhaust apparatuses to the same rotational speed when there are a plurality of operating exhaust apparatuses. An exhaust system according to any one of the above.   The control unit operates at a higher speed than the third rotational speed when there are a plurality of the exhaust devices operating at a higher speed than the third rotational speed in the exhaust amount reduction process. 5. The rotation speed of at least one other of the plurality of exhaust devices is reduced without changing the rotation speed of at least one of the plurality of exhaust devices. 5. Exhaust system. A pressure sensor that is disposed in the connection pipe and detects a vacuum pressure in the connection pipe;
The control unit specifies a vacuum pressure in the connection pipe based on a sensor signal output from the pressure sensor, and the specified vacuum pressure is higher than a vacuum pressure in the preset vacuum pressure range. When the vacuum pressure is increased, it is determined that the load is reduced, and the exhaust amount reduction process is executed. The specified vacuum pressure is lowered to a vacuum pressure lower than the vacuum pressure within the preset vacuum pressure range. The exhaust system according to any one of claims 1 to 7, wherein the exhaust amount increasing process is executed by determining that the load has sometimes increased.   When the number of operating exhaust devices is one and the load decreases when the number of rotations of the one exhaust device is the third number of rotations, the control unit removes the one exhaust device from the third exhaust device. The exhaust system according to any one of claims 1 to 8, wherein the exhaust system maintains a state of being operated at a rotational speed of. It is configured to be operable at a rotation speed between a first rotation speed specified in advance and a predetermined second rotation speed higher than the first rotation speed. In an exhaust system configured with N rotation-variable exhaust devices (N is a natural number of 2 or more) that exhaust gas through the exhaust system, the operating state of the exhaust device is changed when the load decreases. By executing an exhaust amount reducing process for reducing the exhaust amount of the gas and executing an exhaust amount increasing process for changing the operating state of the exhaust device to increase the exhaust amount of the gas when the load increases. An exhaust device control method for maintaining the vacuum pressure in the connection pipe at a vacuum pressure within a preset vacuum pressure range,
A predetermined third rotation speed that is equal to or higher than the first rotation speed and lower than the second rotation speed is set as a lower limit of a range in which the rotation speed of each exhaust device is changed during the exhaust amount reduction processing. Each of the exhaust devices is defined according to the number of operating exhaust devices when the exhaust amount reduction processing is performed, and the M exhaust devices (M is a natural number of 2 or more and N or less) of the N exhaust devices are operated. Multiple-unit operation state in which the gas is exhausted with an exhaust amount smaller than the exhaust amount of the gas when the (M-1) units of the M exhaust devices are operated at the second rotational speed. For the exhaust system configured to control the M exhaust devices at the same time, when the exhaust amount of the gas is reduced in the operation state of the plurality of exhaust devices, L of the M exhaust devices ( L is a natural number of M or less) When the rotational speed of the exhaust device is higher than the third rotational speed, the first process of reducing at least the rotational speed of the L exhaust devices without stopping the M exhaust devices is performed. When the number of rotations of the L exhaust devices specified in advance is the third number of rotations, the exhaust amount reduction processing is executed as one of the L exhaust devices and the L exhausts. Stop any one of the exhaust devices other than the device that is operating at the third rotational speed, and increase the rotational speed of at least one of the exhaust devices that continue to operate An exhaust device control method for executing the second process to be performed as the exhaust amount reduction process.   An upper limit of a range in which the rotational speed of each exhaust device is changed during the exhaust amount increase processing by using a predetermined fourth rotational speed that is higher than the third rotational speed and less than or equal to the second rotational speed. As defined in accordance with the number of operating exhaust devices when the exhaust amount increasing process is performed, and when increasing the exhaust amount of the gas, at least one exhaust device is in a stopped state and operates When the rotational speed of at least one of the exhaust devices in the inside is lower than the fourth rotational speed, the operation of the exhaust apparatus in the stopped state is not started, and the rotational speed is higher than the fourth rotational speed. A third process for increasing the rotational speed of the exhaust device operating at a low speed is executed as the exhaust amount increasing process, and at least one of the exhaust devices is stopped and the exhaust in operation Equipment When all the rotation speeds are the fourth rotation speed, the operation of one of the exhaust devices in a stopped state is started, and the rotation speed of at least one of the exhaust devices in operation is decreased. The exhaust device control method according to claim 10, wherein the fourth processing is executed as the exhaust amount increase processing.

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