JPH0792084B2 - Pulse-air pressure converter - Google Patents

Description

TECHNICAL FIELD The present invention relates to a pulse-pneumatic pressure converter.

[Prior Art] Along with the digitalization of control, a pulse-pneumatic pressure converting device for converting a pulse signal into an air pressure signal has been proposed in order to control pneumatic equipment such as a cylinder device or a diaphragm device by a digital signal. ing. This pulse-air pressure converter converts a pulse signal based on a setting signal into an air pressure signal, and uses the conversion result as a feedback signal for the setting signal.

[Problems to be Solved by the Invention] However, in the conventional pulse-air pressure conversion device, the air pressure at the air pressure output end, which is output to the external pneumatic device, is current-exchanged and used as a feedback signal for the setting signal. . Therefore, since the feedback signal is affected by the air consumption of the pneumatic equipment or the delay of the air pressure output change speed due to the air piping capacity, the pulse signal precedes the setting signal, and the overshoot of the air pressure signal as the output occurs. , Hunting occurs and lacks stability.

That is, in order to control the operating end in a pulse-pneumatic pressure converter that converts a pulse signal into an air pressure signal (output pressure) as input, it depends on the dead time of the operating end operation for the command signal that is always present at the pneumatic operating end. It is necessary to change the output pressure. On the other hand, in the prior art such as Japanese Patent Laid-Open No. 59-164401, the motor is driven by an electric signal (pulse signal, etc.) and the output pressure is generated by a cam device and a servo device connected to the motor. , It is only outputting. With this, the output pressure cannot be changed according to the dead time of the operation end operation, and the operation of the operation end causes overshoot and hunting, and stable control at an accurate position is impossible.

In addition, since the capacity of the air pressure generated by the servo device in the air pressure converter is small, capacity amplification by the booster is devised. However, the volume of air pressure generated by the servo device is much smaller than the volume of the booster input chamber, and dead time is generated in the booster. Particularly when the output pressure changes in the increasing direction, a large amount of dead time occurs due to insufficient input pressure capacity. In the prior art, by arranging an air pressure converter without a booster near the operating end, the output pipe was shortened and the output pressure was transmitted as quickly as possible, but stable control is impossible due to the influence of vibration from the operating end or , Using booster,
I had to use it with a lot of dead time. This is not a fundamental solution.

It is an object of the present invention to output a stable air pressure signal that follows a pulse signal without delay and does not cause overshoot or hunting.

[Means for Solving the Problems] The present invention provides a pulse-converting pulse signal to a pneumatic signal.
In the air pressure conversion device, a DC motor driven by a pulse signal corresponding to a deviation value between a setting signal and a feedback signal, and a back pressure nozzle facing the servo cam according to a rotation angle of a servo cam rotating in conjunction with the DC motor. A servo device that adjusts the back pressure to generate an air pressure corresponding to the rotation angle of the servo cam, a feedback unit that current-exchanges the air pressure generated by the servo device, and transmits the conversion result as a feedback signal, and a servo device. And a booster device for generating an air pressure signal for capacity-amplifying the generated air pressure to output to the outside, and the pulse signal supplied for driving the DC motor is selectively limited in partial pressure. , The rotation speed of the DC motor can be switched and set, and the booster device is supplied with the air pressure generated by the servo device. A chamber and an output chamber air pressure signal for outputting to the outside is generated, it includes through diaphragm, the input chamber and the output chamber is obtained by the so are connected with each other by an orifice.

[Operation] According to the present invention, the DC motor is driven by the pulse signal corresponding to the deviation amount between the setting signal and the feedback signal, and the servo cam of the servo device is opposed to the servo cam under the condition of rotating in synchronization with the DC motor. Back pressure The back pressure of the nozzle is adjusted, the air pressure corresponding to the rotation angle of the servo cam, that is, the pulse signal is generated, and this air pressure is returned as a feedback signal that is current-exchanged by the feedback means to obtain the desired air pressure. The obtained air pressure is capacity-amplified by the booster device and output to the external pneumatic equipment.

Here, in the present invention, since the current exchange result of the air pressure generated by the servo device is used as the feedback signal, the feedback signal is the air consumption amount of the pneumatic equipment or the air pressure output change speed depending on the air piping capacity. Is almost unaffected by the delay. Therefore, the air pressure signal follows the pulse signal without delay and is output in a stable state without overshoot or hunting.

Since the present invention uses the DC motor, the output value of the air pressure signal maintains the value before the pulse input loss even when the pulse input signal is lost. Therefore, unlike a conventional electro-pneumatic conversion device driven by a solenoid motor, when the input signal is lost, the motor core does not swing up to a pressure position where the motor core is in the parallel position, which is a fatal accident in pneumatic equipment. There is no possibility of causing.

And according to this invention, there exist the following effects especially.

This pulse-pneumatic pressure converter corresponds to the dead time of the operation of the operating end with respect to the command signal that is always present at the pneumatic operating end, so the motor rotation speed can be easily changed by the motor speed switching setter. The air pressure change speed can be set according to the operating speed of the.

This pulse-air pressure converter can reduce the dead time when the pressure of the input chamber is supplied from the output chamber by passing it through the input chamber and the output chamber of the booster device. The pressure can be transmitted through the diaphragm, and the error in the input / output pressure can be greatly reduced. That is, since the booster device is provided, a stable air pressure with little dead time and error can be output even when the booster device is arranged at a long distance from the operating end, and very stable operating end control can be performed.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing a servo device, FIG. 3 is a schematic diagram showing a servo cam and a back pressure nozzle, and FIG. 4 is a booster device. FIG.

In FIG. 1, 1 is a pulse-air pressure conversion device,
This pulse-air pressure converter 1 is a motor speed setter 1
0, DC motor 20, servo device 30, pressure sensor 40, voltage-current conversion amplifier 50, booster device 60. Further, in FIG. 1, 70 is a controller.

The controller 70 has a setting signal 81 and a feedback signal 82.
In response, the pulse signal 83 corresponding to the deviation amount of both signals 81 and 82
Is supplied to the motor speed setting device 10 of the pulse-air pressure conversion device 1.

The motor speed setting device 10 receives the pulse signal 83 from the controller 70. The motor speed setting device 10 resistance-divides the pulse voltage of the pulse signal 83 by the selection operation of the changeover switch, and supplies the pulse signal 84 whose voltage is limited by this to the DC motor 20. That is, the motor speed setting device 10
The pulse signal 83 supplied from the controller 70 for driving the DC motor 20 is selectively divided and limited in voltage.
By changing and setting the rotation speed of, the change speed of the air pressure signal 85, which will be described later, is adjusted to a value suitable for the pneumatic equipment.

The DC motor 20 is driven by the pulse signal 84 supplied from the motor speed setting device 10, and drives the servo device 30. Here, the DC motor 20 has a built-in reduction gear, and as shown in FIG. 2, a servo cam 31 is connected to its output shaft 21. As a result, the DC motor 20 is
It suppresses overrun due to inertia of 31.

The servo device 30 regulates the back pressure of the back pressure nozzle 32 facing the servo cam 31 according to the rotation angle of the servo cam 31 that rotates in conjunction with the DC motor 20.

The supply air 86 is supplied to the back pressure nozzle 32 through the line 87, the pressure of which is set by the pressure reducing valve 33, and the flow rate of which is limited by the orifice 34. The pressure reducing valve 33 is installed to reduce the influence of the pressure fluctuation of the supply air 86. The back pressure of the back pressure nozzle 32 regulated by the rotation of the servo cam 31 corresponds to the rotation angle of the servo cam 31 due to the closed loop circuit of the back pressure bellows 35 and the feedback spring 36, for example 0.2 to.
The air pressure will be 1.0 kg / cm ² . That is, for example, when a pulse signal instructing an increase in air pressure is transmitted to the DC motor 20, the servo cam 31 rotates in a direction in which the flow of the back pressure nozzle 32 is suppressed. As a result, the back pressure of the back pressure nozzle 32 increases, and the nozzle back pressure stretches the back pressure bellows 35 against the force of the feedback spring 36. The back pressure nozzle 32 is fixed to the movable portion of the back pressure bellows 35, and moves the back pressure nozzle 32 to the end of the servo cam 31 as the back pressure bellows 35 extends. The back pressure nozzle 32 has a servo cam 31 as shown in FIG.
When reaching the end of, the back pressure of the nozzle stops increasing, and the bellows pressure and the force of the feedback spring 36 are balanced. The nozzle back pressure is, for example, 0.2 to 1.0 kg / cm ² described above at equilibrium.

Here, in order to minimize the delay of the pressure change speed of the air pressure signal 85 due to the air piping capacity to the external air equipment and the air consumption capacity of the air equipment, the back pressure bellows 35 is connected to the line. It is being fed back by 88. Also, due to the abnormalities in the external pneumatic equipment or the air piping to them, the back pressure bellows 35 immediately contracts due to the presence of the piping of the above line 88, and the back pressure of the back pressure nozzle 32 is increased. As a result, the feedback signal 82 increases abnormally, and it is possible to detect the occurrence of an abnormal state of the pneumatic equipment or the like. In the embodiment of the present invention, the air pressure generated by the servo device 30, that is, the back pressure of the back pressure nozzle 32 may be directly supplied to the back pressure bellows 35.

The air pressure of, for example, 0.2 to 1.0 Kg / cm ² generated by the servo device 30 is sent to the pressure sensor 40 through the line 89. The air pressure sent to the pressure sensor 40 is proportionally changed to a voltage, and is proportionally converted to a current of, for example, 4 to 20 mA DC by a voltage-current conversion amplifier 50. That is, the pressure sensor 40 and the voltage-current conversion amplifier 50 constitute the feedback means of the present invention, and the current of 4 to 20 mA DC is the above-mentioned feedback signal.
It is returned to the controller 70 as 82. The voltage-current conversion amplifier 50 has a range adjustment circuit 51 and a zero adjustment circuit 52, and enables the range and zero adjustment of the feedback signal 82.

As a result, the air pressure generated by the servo device 30 is converted to a value corresponding to the setting signal 81 so that the deviation amount between the setting signal 81 and the feedback signal 82 becomes zero and supplied to the booster device 60 from the line 90. To be done. That is, the air pressure generated by the servo device 30 is capacity-amplified by the booster device 60 under the same pressure condition and output as the air pressure signal 85.

The booster device 60, as shown in FIG.
An input chamber 61 to which the air pressure generated by is supplied, and an output chamber 62 in which an air pressure signal 85 for output to the outside is generated,
It is provided via diaphragms 63 and 64, and the input chamber 61 and the output chamber 62 are connected by an orifice 65. That is, in the booster device 60, when the air pressure increases, the air pressure in the input chamber 61 also increases and the diaphragm 63
The inner valve 66 is pushed down via. When the inner valve 66 is lowered, the air supply port 67 is opened and the supply air 86 flows into the output chamber 62 to increase the pressure of the output chamber 62. When the pressure in the output chamber 62 increases, the inner valve 66 is pushed up via the diaphragm 64, the air supply port 67 is closed, and the pressure increase in the output chamber 62 is stopped. Further, when the pressure in the output chamber 62 becomes equal to or higher than the pressure in the input chamber 61, the exhaust port 68 opens and exhausts. At this point, the input chamber pressure (force acting on the diaphragm 63) and the output chamber pressure (force acting on the diaphragm 64) are in equilibrium, and the capacity is amplified by the supply air 86, for example.
An output chamber pressure of 0.2 to 1.0 Kg / cm ² can be output as the air pressure output signal 85. Here, since the booster device 60 has the orifice 65, the input chamber pressure and the output chamber pressure can be finally surely equalized, and the pneumatic signal 85 can be stabilized.

That is, according to the pulse-air pressure conversion device 1, the pulse signal 83 corresponding to the setting signal 81 is pressure-converted into the air pressure signal 85 and output as the operation signal for the external pneumatic equipment.

In the pulse-pneumatic pressure converter 1, electric parts such as the motor speed setting device 10, the DC motor 20, the pressure sensor 40, the voltage-current conversion amplifier 50, and the external conductor connection terminal are housed in the flameproof container 100. Satisfies the explosion-proof specifications.
Further, the range adjustment and zero adjustment unit of the feedback signal 82 provided in the voltage-current conversion amplifier 50 can be adjusted from the outside while satisfying the pressure-proof and explosion-proof specifications.

Next, the operation of the above embodiment will be described.

According to the above embodiment, the setting signal 81 and the feedback signal
The DC motor 20 is driven by the pulse signals 83 and 84 corresponding to the deviation amount of 82, and the servo cam 31 of the servo device 30 is rotated in conjunction with the DC motor 20. The back pressure is adjusted to generate an air pressure corresponding to the rotation angle of the servo cam 31, that is, a pulse signal, and this air pressure is converted into a feedback signal by a pressure sensor 40 as a feedback means and a voltage-current conversion amplifier 50. A desired air pressure is obtained by returning the air pressure to the device, and the obtained air pressure is capacity-amplified by the booster device 60 and output to an external pneumatic device.

Here, in the above embodiment, since the current conversion result of the air pressure generated by the servo device 30 is used as the feedback signal 82, the feedback signal 82 depends on the air consumption of the pneumatic equipment or the air piping capacity. It is hardly affected by the delay in the air pressure output change speed. Therefore, the pneumatic signal 85 follows the pulse signal without delay and is output in a stable state without overshoot or hunting.

In the above embodiment, since the DC motor 20 is used, even when the pulse input signal is lost, the air pressure signal 85
The output value of is maintained at the value when the pulse input is lost. Therefore, unlike a conventional electro-pneumatic conversion device driven by a solenoid motor, when the input signal is lost, the motor core does not swing up to a pressure position where the motor core is in the parallel position, which is a fatal accident in pneumatic equipment. There is no possibility of causing.

Further, according to the above embodiment, the air output capacity becomes large,
It is also possible to control multiple pneumatic devices at the same time.

That is, according to this embodiment, the following operational effects are obtained.

The pulse-pneumatic pressure converter 1 corresponds to the dead time of the operation end operation with respect to the command signal that is always present at the pneumatic operation end. Therefore, the rotation speed of the motor 20 is set to the motor speed switching setter.
It can be easily changed by 10, and as a result, the air pressure change speed can be set according to the operating speed of the operating end.

In the pulse-air pressure converter 1, the dead time in which the pressure of the input chamber 61 is supplied from the output chamber 62 can be shortened by passing the input chamber 61 and the output chamber 62 of the booster device 60, and the orifice 65 is further provided in the communicating passage. Input room by using 61
The pressure can be transmitted through the diaphragms 63 and 64, and the error in the input / output pressure can be greatly reduced. That is, since the booster device 60 is provided, a stable air pressure with little dead time and error can be output even when the booster device 60 is arranged at a long distance from the operating end, and very stable operating end control can be performed.

[Advantages of the Invention] As described above, according to the present invention, it is possible to output a stable pneumatic signal that follows a pulse signal without delay and does not cause overshoot or hunting.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing a servo device, FIG. 3 is a schematic diagram showing a servo cam and a back pressure nozzle, and FIG. 4 is a sectional view showing a booster device. Is. 1-Pulse-pneumatic pressure converter, 20-DC motor, 30
…… Servo device, 31 …… Servo cam, 32 …… Back pressure nozzle, 40 …… Pressure sensor, 50 …… Voltage-current conversion amplifier,
60 …… Booster device, 61 …… Input room, 62 …… Output room, 6
3, 64 …… diaphragm, 65 …… orifice, 81 …… setting signal, 82 …… feedback signal, 83,84 …… pulse signal, 85 …… pneumatic signal, 100 …… flameproof container.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshimichi Sato 511 Haraki, Nirayama-cho, Takata-gun, Shizuoka Japan Nippon Bale Co., Ltd. (56) References JP-A-59-164401 (JP, A) JP-A-61- 26493 (JP, A)

Claims (1)

[Claims] 1. A pulse-pneumatic pressure converting device for converting a pulse signal into an air pressure signal, a DC motor driven by a pulse signal according to a deviation value between a setting signal and a feedback signal, and a servo cam rotating in conjunction with the DC motor. The back pressure of the back pressure nozzle facing the servo cam is adjusted according to the rotation angle of the servo device, and the servo device that generates the air pressure corresponding to the rotation angle of the servo cam and the air pressure generated by the servo device are exchanged with current. It has a feedback means for transmitting this conversion result as a feedback signal, and a booster device for capacity-amplifying the air pressure generated by the servo device to generate an air pressure signal for output to the outside. The pulse signal supplied for this purpose is selectively limited in voltage division, and the rotation speed of the DC motor can be switched and set. The input device is provided with an input chamber to which the air pressure generated by the servo device is supplied and an output chamber to generate an air pressure signal for output to the outside through a diaphragm. Is a pulse-air pressure conversion device characterized by being connected by an orifice.