JP4874576B2 - Flow control system - Google Patents

Description

  The present invention relates to a flow rate control system using a flow meter that is applied to, for example, control of a chemical flow rate at a minute flow rate in a wafer cleaning line of a semiconductor manufacturing apparatus.

Conventionally, in order to measure the flow rate of a liquid flowing in a flow path, a flow meter connected in-line in a fluid circuit has been widely used. In such a flow meter, a differential pressure type is known in which an orifice, a venturi nozzle, a pitot tube, or the like is installed at an appropriate position in a flow path, and a flow rate is measured from a differential pressure generated by the restriction. Since such a differential pressure type flow meter is normally used in a region where the flow of liquid becomes turbulent, the flow velocity becomes large and cavitation is likely to occur in the throttle mechanism.
In addition to the pressure loss problem, the differential pressure type flow meter described above has a problem of increasing the cost of ensuring processing accuracy. For example, a pair of probes provided with slits opened in the flow path are provided. A configuration has been proposed in which a differential pressure between fluids flowing into both probes is detected. This differential pressure type flow meter is a flow meter according to the dynamic pressure measurement principle, and it is said that the measurement accuracy is improved and the structure is simple and can be manufactured at low cost. (For example, see Patent Document 1)
JP 11-316144 A

  By the way, the conventional differential pressure type flow meter described above has a problem that bubbles are generated on the downstream side (secondary side) constricted by the orifice when the outlet side is installed in a fluid flow path that is open to the atmosphere. The generated bubbles are likely to stay in the pressure sensor installed on the secondary side and flow together after being accumulated to some extent. Therefore, the generation of such bubbles not only adversely affects the flow rate measurement accuracy in the minute flow rate range. For example, when the fluid flow path is a wafer cleaning line of a semiconductor manufacturing apparatus, a problem arises in that the product is adversely affected by the cleaning liquid containing bubbles generated by the differential pressure flow meter dropping on the wafer. In order to prevent the generation of such bubbles, in the current wafer cleaning line or the like, the actual situation is that a back pressure is applied to the orifice of the differential pressure type flow meter. The minute flow rate here is approximately 1 lit./min. Or less.

In general, various devices connected to the flow path have a hole in a block-like body, and the hole is used as a part of the flow path. When the flow path is bent, the entire flow path cannot be created by a single drilling process. In such a case, a plurality of flow paths are formed along each linear portion of the flow path with respect to the body. By forming a hole and refilling unnecessary openings (openings other than the inlet and outlet of the flow path) of these holes using plugs, etc., from the inlet to the outlet of the flow path in the body A hole leading to it is formed.
However, in the body having such a configuration, a space is formed in addition to the originally required flow path at the hole backfilling portion, so that fluid stays easily in this portion.

From such a background, it is desired to develop a flow meter that can prevent or suppress the generation of bubbles and that can ensure sufficient measurement accuracy in a minute flow rate range and is less likely to cause retention of fluid or bubbles. .
The present invention has been made in view of the above circumstances, and its object is to prevent or suppress the generation of bubbles, enabling flow measurement with excellent measurement accuracy in a minute flow rate range, An object of the present invention is to provide a flow rate control system using a flow meter in which bubbles do not easily stay.

In order to solve the above problems, the present invention employs the following means.
A flow meter according to a reference example of the present invention is a flow meter that measures a minute flow rate of a liquid flowing in a fluid flow path whose outlet environment is a constant pressure, and is connected to an outlet side end portion of the fluid flow path. A flow rate measurement pipe section having a predetermined length with a flow passage cross-sectional area smaller than that of the flow path and having a constant pressure at the outlet environment, and an upstream of the flow measurement pipe section installed near the outlet of the fluid flow path. The pressure detection means for detecting the pressure of the liquid on the side and the pressure / flow rate conversion means for calculating the flow rate from the fluid pressure detected by the pressure detection means are provided.
Moreover, in the flow meter of the reference example of the present invention , it is preferable that the constant pressure in the outlet environment is atmospheric pressure due to release to the atmosphere.
In addition, about the said flow-measurement pipe line part, the measured value of flow volume can be stabilized by setting the exit position higher than a pressure detection means.

According to the above-described flowmeter of the reference example of the present invention , the predetermined length is connected to the outlet side end portion of the fluid flow channel, and the flow channel cross-sectional area is set smaller than the fluid flow channel and the outlet environment is set to a constant pressure. A flow rate measuring pipe section, a pressure detecting means installed near the outlet of the fluid flow path to detect the pressure of the liquid on the upstream side of the flow measuring pipe section, and a flow rate from the fluid pressure detected by the pressure detecting means. Since the pressure / flow rate conversion means for calculation is provided, a differential pressure is generated by narrowing the cross-sectional area of the flow rate by a predetermined length of the flow rate measurement conduit, and the flow rate is calculated based on this differential pressure. It becomes a differential pressure type flow meter that can do. In addition, the flow rate measurement pipe part of the reference example of the present invention does not cause a sudden increase in the cross-sectional area of the flow path immediately after throttling, and has a rectifying section of a predetermined length, so that bubbles are generated. Since the generated fluid is easily lost in the rectifying section, the amount of bubbles that reach the outlet and flow out with the fluid can be greatly reduced.
If the exit environment is an atmospheric pressure that is open to the atmosphere, the bubbles that have flowed out diffuse into the atmosphere and disappear.

The above-described flow rate measurement pipe line section preferably has a tube length L of about 50 cm to 3 m and an inner diameter d of 2 mm or less in order to accurately measure a minute flow rate of about 1 ml / min. . Further, the inner diameter d of the flow rate measuring pipe section is more preferably 1 mm or less, and the optimum inner diameter d is 0.5 mm or less.
In addition, the material for the flow rate measurement pipe line portion is not particularly limited as long as it can form a long and narrow flow path. However, when applied to a semiconductor manufacturing apparatus, PFA, PTFE of thermoplastic resin is used because of chemical resistance. It is preferable to employ an engineering plastic called PEEK (peak), and since it is excellent in mechanical strength, heat resistance and chemical resistance, it can prevent thermal deformation that causes measurement errors.
And since the above flow meter has high measurement accuracy of minute flow rate and can minimize the generation of bubbles, especially when mixing chemical solution with minute flow rate in pure water in the cleaning line of semiconductor manufacturing equipment It is suitable for the chemical liquid flow rate control.

Further, the flow control system according to the present invention includes a flow control valve, the flow meter described in the reference example of the present invention, the flow control valve and the flow meter on one side, and the flow rate inside. A block-shaped body provided with a fluid flow path connecting the control valve and the flow meter, and the fluid flow path from the region where the flow control valve on one surface is installed toward the inside of the body The first inclined flow path gradually toward the area where the flow meter is installed, and gradually toward the area where the flow control valve is installed as it goes from the area where the flow meter on the one surface is installed to the inside of the body. It has the 2nd inclined flow path connected to the front-end | tip of a 1st inclined flow path, It is characterized by the above-mentioned.

In the flow control system configured as described above, the flow control valve and the flow meter described in the reference example of the present invention are configured to share the same body. That is, in this flow control system, since the flow control valve and the flow meter are integrated, handling is easy.
The flow rate control valve and the flow meter are provided on one side of the body and are connected by a fluid flow path provided in the body.

In the fluid flow path, a region connecting the flow control valve and the flow meter has a substantially V-shape formed by a first inclined flow path and a second inclined flow path that are inclined with respect to one surface of the body. Yes.
That is, in the fluid flow path, the region connecting the flow control valve and the flow meter is configured by two inclined holes provided from one side of the body, and the shape of the fluid flow path becomes simple. It is difficult for fluid to stay in the fluid flow path.
Also, in this way, the region connecting the flow control valve and the flow meter in the fluid flow path is created by forming two inclined holes, and no backfilling of the holes is necessary, so the body Processing is minimal and easy to manufacture.

In this flow control system, at least a part of the fluid flow path may be inclined so as to be positioned above the inlet side than the inlet side.
In the flow rate control system configured as described above, at least a part of the fluid flow path is inclined so that the outlet side is positioned higher than the inlet side. The buoyancy of the bubble that has flowed in acts on the outlet side of the fluid flow path.
For this reason, even when the flow rate of the fluid flowing in the fluid flow path is very small, the bubbles easily move to the outlet side of the fluid flow path, and the bubbles are less likely to stay in the fluid flow path.

The flow rate control system further includes a pedestal on which the body is placed on an upper surface, and the upper surface of the pedestal gradually rises from the inlet side of the fluid channel toward the outlet side of the fluid channel. It may be made into the inclined surface which faces.
In the flow control system configured as described above, since the upper surface of the pedestal is inclined, the body placed on the pedestal is positioned on the outlet side of the fluid flow path as compared to the state without the pedestal. Becomes higher.
Thus, in the fluid flow path in the body, the position of the outlet side is high in the region where the height of the inlet side and the outlet side is equal, and in the region where the inlet side is higher than the outlet side, the inlet side and the outlet side In any region, the bubbles easily move to the outlet side of the fluid flow path, and the bubbles are less likely to stay.

  In the above flow control system, the flow control valve includes a motor attached to the body, and a valve body connected to a rotation shaft of the motor via a screw portion, and the motor A positioning reference surface is provided on the body, and a fixing member for fixing the motor to the body is provided. The fixing member receives the positioning reference surface of the motor and receives at least one of the position and orientation of the rotating shaft. You may have the positioning surface which positions the said motor in the state suitable for the drive of the said valve body.

In such a flow rate control system, the positioning reference surface of the motor is brought into contact with the positioning surface of the fixing member provided on the body, so that the position or orientation of the rotation shaft of the motor, or both the position and orientation are determined. Since the valve body is in a state suitable for driving, the position adjustment work or the direction adjustment work of the motor with respect to the body, or both the position adjustment work and the direction adjustment work are unnecessary.
For this reason, this flow control system can easily and quickly perform high-precision assembly at the time of manufacturing and maintenance, regardless of the technical level of the assembly operator, and is excellent in productivity and workability. Or, variation in assembly accuracy for each maintenance operation can be reduced, and the performance as a flow control valve can be maintained at a high level.

  Here, the positioning reference surface can be composed of one or more curved surfaces, or a plurality of planes in which at least one surface is directed in a direction different from the other surfaces. When the positioning reference surface is a curved surface, the positioning surface is configured by a curved surface having the same curvature as that of the curved surface and the direction of the curvature is reversed. When the positioning reference surface is a plurality of flat surfaces, the positioning surface is also constituted by a plurality of flat surfaces corresponding to the positioning reference surfaces.

  Further, in the flow rate control system having the positioning reference surface and the positioning surface, the positioning reference surface of the motor of the flow control valve forms a cylindrical surface or a cylindrical inner surface parallel to the rotation axis, and the positioning of the fixing member is performed. When the surface is parallel to the driving direction of the valve body and forms a cylindrical inner surface or a cylindrical surface having the same shape as the positioning reference surface, the position of the rotary shaft is determined when the positioning surface receives the positioning reference surface. And orientation may be positioned.

In this flow control system, when the positioning reference surface of the motor of the flow control valve is a cylindrical surface, the positioning surface of the fixing member is a cylindrical inner surface substantially the same shape as the positioning reference surface. Is inserted into the inner peripheral side of the positioning surface of the fixing member and the motor and the fixing member are engaged with each other, thereby positioning the motor with respect to both the position and the direction of the motor.
In this flow control system, when the positioning reference surface of the motor of the flow control valve is a cylindrical inner surface, the positioning surface of the fixing member is a cylindrical surface substantially the same shape as the positioning reference surface. By positioning the positioning surface on the inner peripheral side of the positioning reference surface of the motor and engaging the motor and the fixing member, positioning is performed for both the position and orientation of the motor with respect to the body.

  That is, in this flow control system, the motor of the flow control valve and the fixed member are coupled by a so-called inlay, so that the position and orientation of the motor with respect to the body can be positioned simply by connecting the motor and the fixed member. It can be done and is easy to manufacture.

Further, the flow rate control system having the positioning reference surface and the positioning surface is configured so that the flow rate control valve reaches the end of the operating range while allowing the valve body to move within a preset operating range. You may have a stopper which receives a body and controls the movement outside the said operation range.
In this flow control system, the operating range of the valve body is predetermined, and when the valve body reaches the end of the operating range (boundary between the operating range and the outside of the operating range), the valve body is received by the stopper, Since further movement of the valve body is restricted, problems such as biting of the threaded portion are surely prevented.
In this flow control valve, the preset operating range is the substantial movable range of the valve body.

  Further, the flow rate control system having the positioning reference surface and the positioning surface has a control device that controls the operation of the motor, and the control device has at least the valve body in the vicinity of the end of its movable range. When moving toward the end, the motor is operated with the first driving torque, and when the valve body is separated from the end of the movable range, the motor is larger than the first driving torque. It may be configured to operate with the second driving torque.

In the flow control system configured as described above, when the valve body of the flow control valve is separated from the end of the movable range, the control device that controls the operation of the motor moves the valve body to the end of the movable range. The motor is operated with a second driving torque larger than the driving torque (first driving torque).
As a result, in this flow control system, even if the screw portion is caught when the valve body of the flow control valve moves to the end of the movable range, this biting can be easily eliminated.

Here, the driving torque of the motor is proportional to the magnitude of the driving current input to the motor.
Therefore, when the control device moves the valve body to the end of the movable range, the motor drive current output limit value is set to the first limit value, and when the valve body is moved away from the end of the movable range. Is configured to set the output limit value to a second limit value that is larger than the first limit value, so that the driving torque of the motor when the valve body is separated from the end of the movable range, the valve body is moved to the movable range. The driving torque of the motor when moving to the end of the motor can be made larger.

In general, the motor has a higher torque for driving the rotating shaft as the rotating shaft rotates at a lower speed.
Therefore, when the control device moves the valve body to the end of the movable range, the rotating shaft of the motor is rotated at the first rotational speed, and when the valve body is separated from the end of the movable range, the first rotation is performed. When the valve body is moved from the end of the movable range to the end of the movable range by moving the valve body to the end of the movable range by adopting a configuration that rotates at a second rotational speed lower than the speed. The driving torque of the motor can be made larger.

  In the flow rate control system having the positioning reference surface and the positioning surface, the valve body of the flow rate control valve constitutes a needle of a needle valve, and the motor is proportional to the number of pulses of the input pulse signal. It is a stepping motor that rotates the rotation shaft by an angle, and is provided with a control device that controls the position of the valve body by controlling the operation of the motor. A pulse signal having a pulse number sufficient to rotate the rotary shaft at an angle necessary for the valve body to move from one end of the movable range to the other end is input to the motor, and the rotary shaft is stopped at the position where the rotary shaft is stopped. The valve body may be determined to be positioned at the other end of the movable range, and thereafter, the position of the valve body may be controlled within the movable range.

  In this flow control system, instead of specifying the position of the valve body of the flow control valve using a rotary encoder, the valve body is temporarily moved to the other end of the movable range at an appropriate time such as when the power is turned on. After calibration, obtain the amount of rotation of the rotating shaft after position calibration based on the number of pulses of the pulse signal input to the motor, and then the valve body from the other end of the movable range based on the information on the amount of rotation. Is determined, and the current position of the valve body is specified.

Specifically, in the flow rate control system according to the present invention, when the control device calibrates the position of the valve body of the flow rate control valve, the angle required for the valve body to move from one end of the movable range to the other end (this A pulse signal having a predetermined number of pulses is input to the motor so that the rotation shaft of the motor is rotated by an angle (obtained from design information of the flow control valve).
As a result, when the rotation of the rotating shaft is completed, the valve element is positioned at the other end of the movable range regardless of the position (initial position) at the start of the position calibration operation. If the valve body is located at a position other than one end of the movable range at the time of starting position calibration of the valve body, before the rotating shaft rotates by an angle corresponding to all pulses of the pulse signal input to the motor. Since the valve element arrives at the other end of the movable range and cannot move any more, the rotating shaft does not rotate thereafter regardless of the number of remaining pulses.

After the valve body is positioned at the other end of the movable range in this way, the control device determines that the valve body is positioned at the other end of the movable range, and the position control of the valve body is performed within the movable range. Done.
Within the movable range, the rotation shaft rotates at an angle corresponding to all the pulses of the pulse signal input to the motor, so that a certain relationship is established between the number of pulses of the pulse signal and the position of the valve element.
Thus, in this flow control system, after the valve body of the flow control valve is once positioned at the other end of the movable range, the position of the valve body is specified based on the number of pulses of the pulse signal input to the motor thereafter. Therefore, the position of the valve body can be accurately grasped without using a rotary encoder.

Here, the control device may be configured to rotate the rotating shaft in a direction in which the valve body moves toward an open side of the movable range when the position of the valve body is calibrated.
In the flow rate control system configured as described above, when the position of the valve body of the flow rate control valve is calibrated, the valve body constituting the needle of the needle valve is the open side of the movable range, that is, another member constituting the needle valve. Therefore, even if the position calibration of the valve body is repeated, the valve body and the needle valve body are less likely to be worn.

  In the flow rate control system for calibrating the position of the valve body, the control device causes the motor to perform a first driving torque when the valve body moves toward the end portion in the vicinity of the end portion of the movable range. When the valve body is separated from the end of the movable range, the motor may be operated with a second driving torque larger than the first driving torque.

In the flow control system configured as described above, when the valve body of the flow control valve is separated from the end of the movable range, the control device that controls the operation of the motor moves the valve body to the end of the movable range. The motor is operated with a second driving torque larger than the driving torque (first driving torque).
As a result, in this flow control valve, even if the screw portion is bitten when the valve element moves to the end of the movable range, this biting can be easily eliminated.

In the above-described flow rate control system of the present invention, a thrust bearing that receives a thrust load applied to the rotating shaft may be provided outside the motor body of the motor.
In the flow control system configured as described above, the thrust load transmitted to the rotary shaft via the valve body and the screw portion when the valve body of the flow control valve receives fluid pressure is provided outside the motor body. Therefore, the load applied to the support structure of the rotating shaft in the motor is reduced, and the performance of the motor can be maintained over a long period of time.

According to the above-described flowmeter of the reference example of the present invention, a differential pressure is generated by narrowing the flow path cross-sectional area by a flow measuring pipe portion having a predetermined length, and the flow rate is calculated based on the differential pressure. In addition to the fact that there is no sudden expansion of the cross-sectional area of the flow path, it has a rectifying section of a predetermined length that is a laminar flow, so that it reaches the outlet and together with the fluid The amount of bubbles that flow out is greatly reduced, enabling highly accurate flow rate measurement. In other words, the laminar flow can prevent or suppress the generation of bubbles due to cavitation, and can provide a remarkable effect of providing a flowmeter capable of measuring a flow rate with excellent measurement accuracy in a minute flow rate range. . Further, even if bubbles are generated, there is no place (a stepped portion or the like) where the bubbles stay in the flow rate measuring pipe portion. According to experiments by the inventors, it has been confirmed that the flow rate can be measured within an error range of ± 10% even in a minute flow rate region of about 1 ml / min.
In addition, since the generation of bubbles is reduced in the flow meter of the reference example of the present invention, if this is applied to control of the chemical injection amount in the cleaning line of the semiconductor manufacturing apparatus, the product ( The adverse effect on the wafer and the like) is improved, the occurrence of defective products is reduced, and the remarkable effect of greatly improving the yield is obtained.

In addition, according to the flow control system of the present invention, problems such as biting of the screw portion that drives the valve body of the flow control valve are reliably prevented.
Further, according to the flow control system of the present invention, the position of the valve body of the flow control valve can be accurately grasped without using an expensive rotary encoder.

[ Reference example ]
Hereinafter, a flow meter according to a reference example of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a flow meter according to this reference example . This flow meter 10 measures the minute flow rate of the liquid flowing through the fluid flow path 1 with the outlet open to the atmosphere, and the opening is adjusted in the vicinity of the end portion 1a on the outlet side of the fluid flow path 1. A flow rate control valve 2 for controlling the fluid flow rate and a pressure sensor 3 serving as a pressure detection means for detecting the pressure of the liquid are provided. The fluid pressure detected by the pressure sensor 3 is input to a pressure detection control unit (hereinafter referred to as “control unit”) 4 serving as a pressure / flow rate conversion unit. The pressure sensor 3 employed here is not particularly limited as long as the fluid pressure can be detected. For example, a piezoelectric pressure sensor or a capacitance pressure sensor is preferable.

The control unit 4 calculates the flow rate of the fluid according to the detection value of the pressure sensor 3, and outputs an opening degree control signal of the flow rate control valve 2 according to the difference between the calculated flow rate and a predetermined set flow rate. That is, if the flow control valve 2 is an automatic control valve that can be operated remotely, the flow control is performed in accordance with the opening control signal output from the control unit 4 in combination with the flow meter 10 of the reference example of the present invention. A minute flow control system can be constructed.
The end portion 1a on the outlet side of the fluid flow channel 1 is set to a flow rate measuring pipe section (a predetermined length L) in which the flow channel cross-sectional area is set smaller than that of the fluid flow channel 1 and the outlet side is open to the atmosphere. (Hereinafter referred to as “pipe section”) 5 is connected. The pipe line part 5 has a function of generating a differential pressure by reducing the cross-sectional area of the flow path. This differential pressure is obtained by calculating the difference between the detected value of the pressure sensor 3 which is the upstream (primary) pressure of the pipe section 5 and the predetermined atmospheric pressure which becomes constant when the air is released to the atmosphere.

  In the flow meter 10 having the above-described configuration, the flow rate that changes in accordance with the opening degree of the flow control valve 2 is reduced by the pressure loss caused by being throttled by the pipe line portion 5 having the predetermined length L, and the fluid flow path 1. Due to the relatively large pressure loss caused by flowing the inner diameter d having a small flow path cross-sectional area by a predetermined length L, the pressure of the flow decreases, and the outlet pressure becomes a value that balances with the atmospheric pressure. Therefore, the control unit 4 calculates the flow rate based on the correlation between the differential pressure and the flow rate stored in advance based on the differential pressure generated between the upstream fluid pressure detected by the pressure sensor 3 and the downstream atmospheric pressure. The flow rate of the liquid flowing through the path 1 and the pipe line part 5 can be calculated. The inner diameter d of the pipe section 5 may be set so that the liquid flow becomes a laminar flow in consideration of various conditions such as a flow rate range to be measured.

  Moreover, since the pipe line part 5 is provided with the flow path used as the rectification | straightening area of the predetermined length L, the liquid which flows between this was restrict | squeezed from the fluid flow path 1 to the pipe line part 5, and the flow-path cross-sectional area decreased. The turbulence of the flow caused by this can be eliminated. Further, unlike the restriction by the orifice of the prior art, the restriction by the pipe section 5 does not change the flow passage cross-sectional area on the downstream side to the outlet to the atmosphere, so in other words, the flow passage cross-sectional area as in the downstream of the orifice. Does not increase rapidly, it is possible to prevent or suppress the generation of bubbles due to cavitation or the like. Even when relatively few bubbles are generated by the restriction, the amount of bubbles is reduced by providing the rectifying section, and further, the amount of bubbles is not retained in the rectifying section, and the air is released from the outlet. It disappears as it flows out and diffuses into the atmosphere.

Here, the outlet 5a of the pipe line part 5 is not particularly limited to be horizontal with the position (pressure measurement point) where the pressure sensor 3 performs pressure detection, but in order to further stabilize the measurement value of the flow rate measurement. For example, it is most preferable to set an upward slope in the flow direction so that the position is higher than the pressure measurement point, for example, ascending to the right on the paper surface.
This is because a pressure loss caused by the fluid flow up to the outlet 5a and a back pressure obtained by adding the head pressure due to the height difference act on the pressure measurement point, so that the force for pushing out the liquid by setting the outlet 5a side high. Further, since the force of the back pressure acts in the opposite direction, the flow rate can be stably controlled by appropriately adjusting the balance.
In addition, since the pressure cannot be lowered from the atmospheric pressure by adjusting the opening of the valve, if the position of the outlet 5a is set lower than the pressure measurement point, a minute flow rate range (specifically, pressure loss generated in the pipeline portion < The head pressure difference) cannot be controlled, and therefore the flow rate tends to become unstable.

As described above, the flow meter 10 configured to form the differential pressure by the pipe line portion 5 does not need to measure the secondary side (downstream side) pressure for differential pressure calculation. The cost can be reduced by reducing the number to one less than two. In addition, since the pressure on the secondary side where bubble generation is a problem can be used, it is not necessary to measure the pressure because the atmospheric pressure is constant. Therefore, the pressure value does not fluctuate due to the influence of bubbles. Is possible.
For this reason, even if the liquid flow rate is very small, it is possible to accurately measure the flow rate with little error. For example, a very small liquid flow rate of about 1 ml / min. Can be measured within an error range of ± 10%. It becomes possible.

Further, in order to accurately measure a minute flow rate of, for example, about 1 ml / min. In the laminar flow state, the above-described pipe line portion 5 has a predetermined tube length L of about 50 cm to 3 m and an inner diameter d of 2 mm or less. Is preferred. Further, the inner diameter d that is more preferable for accurate flow measurement is 1 mm or less, and the optimum inner diameter d for accurate flow measurement is 0.5 mm or less.
In addition, a metal pipe or a plastic pipe can be adopted as the material for the flow rate measuring pipe section. However, as a more preferable material, an engineering plastic called PEEK (peak) of a thermoplastic resin may be adopted. Since this PEEK is excellent in mechanical strength, heat resistance and chemical resistance, it is possible to prevent fluctuations in the inner diameter d due to thermal deformation or the like causing measurement errors.

Here, FIG. 3 shows the results of experiments on the relationship between the pressure detection value of the pressure sensor 3 and the actual flow rate of the flow meter 10 of the reference example of the present invention described above using the experimental apparatus configured as shown in FIG. In the experimental apparatus shown in FIG. 2, the same components as those of the flow meter 10 described above are denoted by the same reference numerals.
In this experiment, water is used as the liquid 21 flowing through the fluid flow path 1. This liquid (water) is stored in a sealed tank 22, pressurized from above the liquid surface with a gas (nitrogen gas: N 2) 23, and pushed out to the fluid flow path 1 whose end opens into the liquid. is doing. The pressurizing gas 23 is stored in a pressure vessel, adjusted to a predetermined pressure via a pressure controller 24, and then supplied into the tank 22 through a gas flow path 25. As the flow rate control valve 2, a motor driven needle valve is used.

On the other hand, the fluid flow rate flowing out from the pipe line part 5 of the flow meter 10 is received by the container 27 having an upper opening placed on the electronic balance 26, and its weight change is measured and converted into a volume. Since the liquid is water, the flow rate per unit time is obtained by determining the volume change with 1 g as 1 ml.
Here, various conditions of the experiment are shown below.
1) Liquid used Water 2) Water temperature 23 ° C
3) Air temperature 21 ℃
4) Primary pressure (upstream pressure of flow control valve 2) 100 kPa
5) Fluid flow pipe (primary pipe) 1/4 inch (name)
6) Material for flow rate measurement (secondary piping) PTFE
7) Flow rate measuring pipe (secondary pipe) diameter 3Φ (outer diameter) /0.5Φ (inner diameter)
8) Flow rate measuring pipe (secondary pipe) length 3m
9) Pressure when the flow control valve is closed -0.75kPa
(When the outlet 5a of the flow rate measurement pipe part 5 is bent downward, and the liquid used remains in the pipe part)

The experiment was performed by the following procedure using the above experimental apparatus and conditions.
As preparation before the start of the experiment, the tank 22 is filled with a predetermined amount of liquid (water) 21 and sealed, and a supply system of gas (N2) 23 is connected. At this time, the flow control valve is fully closed. From this state, the pressure controller 24 is operated to supply a gas 23 having a predetermined pressure into the tank 22 to pressurize the inside of the tank 22.
Next, when the flow control valve 2 is opened, the liquid 21 pressurized to the gas 23 flows through the fluid flow path 1 and the flow control valve 2. At this time, the pressure detection control unit 4 receiving the input of the pressure detection value controls the opening degree of the flow control valve 2 so that the detection value of the pressure sensor 3 becomes a predetermined set pressure. The flow rate is calculated based on the result of measuring the weight change of the liquid 21 flowing down into the container 27 with the electronic balance 26 after setting the pressure to the set pressure.

The experimental results obtained by sequentially changing the set pressure in this way are shown in FIG. In this case, in the flow rate range (2 to 10 ml / min.), It can be seen from the calculated Reynolds number that the flow in the pipe section 5 is a laminar flow. Note that the pressure (horizontal axis) here is an increased pressure based on the closing pressure (−0.75 kPa) of the flow control valve 2 described above as a reference (0 point), and the set pressure changes every 2.5 kPa. The flow rate is shown on the vertical axis.
According to this experimental result, the relationship between the pressure and the flow rate is a straight line that rises to the right. Therefore, if the pressure is detected by the pressure sensor 3, the flow rate can be easily calculated from the straight line of the experimental result. That is, in the flow meter 10 of the reference example of the present invention, the characteristics as shown in FIG. The flow rate can be calculated with high accuracy. The flow control valve 2 is indispensable for the construction of the flow control system, but if only the function as a flow meter is desired, it can be a manual on-off valve or can be omitted.

By the way, the flow meter 10 described above has high measurement accuracy of a minute flow rate and can suppress the generation of bubbles to a minimum. Therefore, particularly in a cleaning line of a semiconductor manufacturing apparatus, a minute flow chemical solution is mixed with pure water. It is suitable for the chemical liquid flow rate control. When this flow meter 10 is applied to a cleaning line of a semiconductor manufacturing apparatus, the liquid flowing through the fluid flow path 1 becomes a chemical solution mixed with pure water. Specific examples of the chemical solution include sulfuric acid, hydrofluoric acid (hydrofluoric acid), hydrogen peroxide water, and the like. The cleaning water mixed with pure water by flowing these chemicals at a predetermined minute flow rate is applied to the wafer. Washing is performed by flowing down.
In this case, the cleaning liquid main line through which pure water flows is an exit environment for liquid (chemical solution), and this exit environment is maintained at a predetermined constant pressure. Therefore, since the flow of pure water for injecting the chemical liquid by connecting the pipe line portion 5 is a predetermined constant pressure flow, the flow rate is determined by only one pressure sensor 3 as in the case of opening to the atmosphere. Measurements can be made. That is, the differential pressure may be calculated from the difference between the detected value of the pressure sensor 3 and the predetermined pressure, or in order to calculate the differential pressure more accurately, as in the above-described experiment, all of the flow control valve 2 is calculated. The differential pressure from the detected value of the pressure sensor 3 may be calculated based on the closing pressure.

As described above, when the flow meter 10 of the reference example of the present invention is employed in the wafer cleaning line of the semiconductor manufacturing apparatus, not only can the amount of chemical flow injected at a minute flow rate be accurately controlled, but also the generation of bubbles and the accumulated bubbles. Therefore, it is possible to prevent or suppress the cleaning water containing bubbles from flowing down onto the wafer and adversely affecting the product. Therefore, the generation of defective products in the semiconductor manufacturing apparatus can be reduced and the yield can be improved.

As described above, the flow meter 10 according to the reference example of the present invention is configured to flow a liquid through the flow rate measurement pipe portion 5 having a predetermined length L to reduce the flow path cross-sectional area and detect the pressure value detected by the pressure sensor 3. Since a differential pressure is generated during this period, and the flow rate is calculated based on this differential pressure, the flow rate of a minute flow rate that flows in a laminar flow state can be measured with high accuracy. Moreover, since the flow rate measurement pipe part 5 of the reference example of the present invention includes a rectifying section having a predetermined length L, not only can the generation of bubbles be suppressed, but also after a small amount of generated bubbles has accumulated. There is no such thing as a collective outflow.
And since the above flow meter has high measurement accuracy of minute flow rate and can minimize the generation of bubbles, especially when mixing chemical solution with minute flow rate in pure water in the cleaning line of semiconductor manufacturing equipment It is suitable for the chemical liquid flow rate control. Moreover, even when used for measuring the flow rate of a liquid that foams itself due to the saturation vapor pressure, such as hydrogen peroxide, for example, the generation of bubbles due to the passage of the flow meter 10 is suppressed in the same manner as other liquids. Is done.

In addition, when pressure loss increases in a piping flow path, a flow meter, etc., a high pressure is required on the primary side. Therefore, it is necessary to increase the performance (performance) of the pump and the compressor, and the flow path and Since advanced specifications are required for the pressure resistance strength and sealing performance of the equipment, the cost increases as a result. For this reason, a flow meter with no pressure loss is usually ideal. However, since the flow meter 10 of the reference example of the present invention described above is premised on use near the use point (atmospheric release or outlet pressure is sufficiently low), pressure loss does not become a problem, and the flow path If the pressure loss is positively generated by narrowing the cross-sectional area from the fluid flow path 1 to the pipe line section 5, the measurement level of the pressure value with respect to the minute flow rate can be increased, and more accurate measurement is possible. .

First Embodiment
Hereinafter, an embodiment of a flow control system according to the present invention will be described with reference to the drawings.
As shown in FIG. 4, the flow rate control system 100 according to the present embodiment uses a flow rate control valve 110 instead of the flow rate control valve 2 in the flow meter 10 shown in the reference example . The main feature is that the flow meter 3 is provided on one surface side (in this embodiment, the upper surface side) of the block-shaped body 112 in which the fluid flow path 101 is provided.
Hereinafter, the same or the same configuration as the flow meter 10 shown in the reference example is indicated by the same reference numeral, and detailed description thereof is omitted.

The flow control valve 110 is constituted by a drive unit 111, the body 112, a base 113 (pedestal), and a diaphragm needle (valve element) 114 as main elements.
The drive unit 111 includes a motor 115, a coupling 116, a slider 117, a stopper 118, a packing 119, a diaphragm cover 120, a spring (biasing means) 121, a cover flange 122, and a cover 123. Is.

The motor 115 is composed of, for example, a stepping motor, and a rotating shaft 115 a that protrudes downward and is rotated forward and backward by electric power supplied via the cable 129 is provided at the center of the lower surface of the motor 115. A flat seat surface 115b is formed on a part of the rotating shaft 115a, and a front end surface of a hexagon socket head set screw 130 described later comes into contact with the seat surface 115b.
As shown in FIG. 5, the coupling 116 is formed with a concave portion 116 a that receives the rotation shaft 115 a at the center thereof, and a convex portion 116 b that protrudes downward from the lower end portion thereof. A cylindrical member having a substantially T-shape. Further, a male screw portion 116c is formed on the outer surface of the convex portion 116b, and is screwed with a female screw portion 117a of the slider 117 described later.

  A through hole 116d for receiving the hexagon socket set screw 130 is provided on the side wall of the coupling 116 that forms the recess 116a. The surface of the through hole 116d is formed on the surface of the hexagon socket set screw 130. A female screw portion that is screwed with the male screw portion is formed. The male screw portion of the hexagon socket head set screw 130 is screwed with the female screw portion of the through hole 116d, and the hexagon socket head set screw 130 is in contact with the seat surface 115b of the rotating shaft 115a. The coupling 116 is fixed to the rotating shaft 115a of the motor 115 by screwing the hole set screw 130 into the through hole 116d.

The slider 117 moves up and down along the motor shaft 131 extending downward from the lower end surface of the motor 115, and an inner peripheral surface in contact with the outer peripheral surface of the motor shaft 131 at both ends (left and right end portions in the drawing) 117 b. A bifurcated portion (not shown) is provided.
The upper central portion of the slider 117, the first recess 117c for receiving the convex portion 116b is formed of the coupling 116, and on the surface thereof, to a male threaded portion 116c and the screwing protrusion 1 1 6b female A threaded portion 117a is formed. Further, a concave groove 117d having a ring shape in a plan view is provided on the outer side in the radial direction of the female screw portion 117a in the circumferential direction so that one end surface (the lower end surface in the drawing) of the spring 121 is accommodated. ing.

On the other hand, a second concave portion 117e that receives the convex portion 118a of the stopper 118 is formed in the lower center portion of the slider 117, and a female screw portion 118b that engages with the male screw portion 118b of the convex portion 118a is formed on the surface thereof. A threaded portion 117f is formed.
The slider 117 configured as described above is moved up and down along the motor shaft 131 by the coupling 116 that rotates together with the rotating shaft 115 a of the motor 115.
The motor shaft 131 is fixed to the cover flange 122 via a screw 132.

The stopper 118 has a substantially T-shape in sectional view, in which a concave portion 118c for receiving the central portion of the diaphragm needle 114 is formed at the central portion, and a convex portion 118a that protrudes upward from the upper end portion is formed. It is a cylindrical member having. Further, a male screw portion 118b is formed on the outer surface of the convex portion 118a, and is screwed with the female screw portion 117f of the slider 117.
That is, the stopper 118 is fixed to the slider 117 when the convex portion 118 a is screwed into the second concave portion 117 e of the slider 117, and moves up and down together with the slider 117.
When the convex portion 118a of the stopper 118 is screwed into the second concave portion 117e of the slider 117, the inner peripheral end portion of the packing 119 is sandwiched between the stopper 118 and the slider 117 and fixed. .

The packing 119 is a donut-shaped member in plan view having a round hole through which the convex portion 118a of the stopper 118 passes at the center thereof, and is made of, for example, fluorine rubber (FKM). The packing 119 is fixed by sandwiching the inner peripheral end portion between the stopper 118 and the slider 117 and sandwiching the outer peripheral end portion between the diaphragm cover 120 and the cover flange 122.
The diaphragm cover 120 and the cover flange 122 are fixed to the body 112 and the base 113 through a pan head screw 133 (see FIG. 4).

The diaphragm cover 120 has a through hole 120a that guides the outer peripheral surface of the side wall that forms the recess 118c of the stopper 118 at the center, and has a recess 120b at the center of the upper surface, and has an upper surface and a lower surface. It has the communicating path 120c which connects.
In addition, a concave groove 120 d is provided on the lower surface of the diaphragm cover 120 to accommodate a convex portion 114 a formed in a ring shape upward at the outer peripheral end portion of the diaphragm needle 114.

  The spring 121 is disposed between a spring receiver 134 provided on the lower end surface of the motor 115 and the concave groove 117d of the slider 117, and is a compression that constantly biases the slider 117 downward (toward the cover flange 122). This is a coil spring, so that backlash between the female threaded portion 117a of the slider 117 and the male threaded portion 116c of the coupling 116 is reduced (or eliminated).

  The cover flange 122 has a through hole 122a that guides the outer peripheral surface of the side wall that forms the first recess 117c of the slider 117 at the center, and the outer peripheral end of the packing 119 between the lower surface and the upper surface of the diaphragm cover 120. It is comprised so that may be inserted | pinched. In addition, a recess 122 b that houses the head of the screw 132 is provided at the lower end of the cover flange 122.

  As shown in FIG. 4, the cover 123 is disposed in contact with the upper portion of the body 112 and accommodates the above-described driving unit 11 therein. A cable packing 135 is provided between the cover 123 and the cable 129, and an O-ring 136 is provided between the cover 123, the body 112, and the diaphragm cover 120. The cable packing 135 and the O-ring 136 are made of, for example, fluoro rubber (FKM).

The body 112 is formed in a substantially rectangular parallelepiped block shape, such as PTFE (polytetrafluoroethylene), PCTFE (polychlorotrifluoroethylene), PFA (tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer), etc. It consists of a fluororesin material.
Further, a fluid inlet portion 141 is provided on one side surface (left side surface in the drawing) of the body 112, and a fluid outlet portion is provided on the other side surface (right side surface in the drawing) located on the opposite side of the fluid inlet portion 141. 142 is provided.

  As shown in FIGS. 4 and 5, the upper surface of the body 112 is provided with a port 143 that communicates with the fluid inlet portion 141 on one side surface thereof, and communicates with the fluid outlet portion 142 on the other side surface side. Port 144 is provided. These ports 143 and 144 are connected via a connection path 145 provided in the body 112.

  The port 143 includes a needle housing portion 143a that receives the needle portion 114b of the diaphragm needle 114 when the diaphragm needle 114 is closed (shown by a solid line in the drawing), and the diaphragm needle 114 that is closed when the diaphragm needle 114 is closed. The diaphragm housing portion 143b is in contact with the lower surface of the diaphragm portion 114c.

The needle accommodating portion 143a is formed of a recess having a circular shape in plan view, and the bottom surface forms a horizontal plane, and a fluid inlet 141a communicating with the fluid inlet portion 141 is formed at the center thereof. In the present embodiment, the fluid inlet portion 141 and the port 143 are a first flow composed of a horizontal portion extending substantially horizontally from the fluid inlet portion 141 to directly below the fluid inlet 141a and a vertical portion extending substantially vertically upward from the horizontal portion. They are connected by a path 141b.
The diaphragm housing portion 143b is formed radially outside the needle housing portion 143a and above the bottom surface of the needle housing portion 143a, and gradually decreases in depth from the radially inner side toward the radially outer side. This is a mortar-like space that is formed to have a donut shape in plan view. Further, a fluid outlet 143c communicating with the connection path 145 is formed in the diaphragm housing portion 143b.
On the upper surface of the body 112, a concave groove 112a is provided in the outer peripheral end of the diaphragm needle 114 to accommodate a convex portion 114d formed in a ring shape downward.

The port 144 is formed of a recess opened on the upper surface of the body 112, and a fluid inlet 144a communicating with the connection path 145 is formed on one side surface of the body 112 on the bottom surface thereof. A fluid outlet 142 a communicating with the fluid outlet 142 is formed. In the present embodiment, the port 144 and the fluid outlet 142 are a second flow composed of a vertical part extending substantially vertically downward from the fluid outlet 142a and a horizontal part extending substantially horizontally from the lower end of the vertical part to the fluid outlet 142. They are connected by a path 142b.
The port 144 constitutes a part of the fluid flow path 1 between itself and the sensor main body 3a by receiving the sensor main body 3a of the pressure sensor 3 therein. That is, in this embodiment, the pressure sensor 3 is configured to measure the pressure of the fluid in the region between the port 144 and the sensor main body 3a.

A sensor holder 3 b that covers the sensor body 3 a housed in the boat 144 is attached to the upper surface of the body 112.
The lower part of the sensor holder 3b has a disc shape that covers the peripheral edge of the port 144 on the upper surface of the body 112 in an airtight and liquid tight manner.
Here, the sensor main body 3 a is connected to a cable 129 a connected to the control unit 4 with its signal line drawn out to the upper surface side of the sensor holder 3 b through the sensor holder 3 b.
A protective cover 3c is provided on the upper part of the sensor holder 3b to cover the connection portion between the signal line of the sensor main body 3a and the cable 129a.

  The connection path 145 for connecting the ports 143 and 144 includes a first inclined channel 145a that gradually moves toward the port 144 side from the fluid outlet 143c of the port 143 toward the inside of the body (lower surface side), and a fluid inlet 144a of the port 144. A second inclined flow path 145b that gradually goes to the port 143 side and is connected to the lower end of the first inclined flow path 144 as it goes to the lower surface side of the body 112 is provided.

A discharge port (not shown) is provided on another side surface of the body 112 (the back surface in FIG. 4), and the discharge port and the diaphragm cover 120 are formed on another side surface of the body 112. A discharge passage (not shown) communicating with the communication passage 120c is provided. In addition, a duck bill is arranged in the discharge path. This duckbill is a so-called check valve made of, for example, fluoro rubber (FKM).
The base 113 is a plate-like member disposed in contact with the lower surface of the body 112, and a recess 113 a that accommodates the head of the pan head screw 133 is provided at the lower end portion thereof.

  The base 113 is configured such that the body 112 is fixedly mounted on the upper surface 113a, and the upper surface 113a increases from one side of the body 112 toward the other side (that is, the fluid flow path in the body 112). (In the direction from the entrance side to the exit side), the slope is gradually inclined upward.

  According to the flow control system 100 configured as in the present embodiment, the flow control valve 110 and the pressure sensor 3 share the same body 112. That is, in this flow control system 100, since the flow control valve 110 and the pressure sensor 3 are integrated, handling is easy.

Further, the flow control valve 110 and the pressure sensor 3 are provided on the upper surface side of the body 112 and are connected by a fluid flow path provided in the body 112.
In the fluid flow path in the body 112, a region (connection path 145) connecting the flow control valve 110 and the pressure sensor 3 is a first inclined flow path 145a and a second inclined flow path that are inclined with respect to one surface of the body 112. 145b, and is substantially V-shaped.
That is, in the fluid flow path in the body 112, the region connecting the flow control valve 110 and the pressure sensor 3 is configured by two inclined holes provided from the upper surface side of the body 112. The shape of the path becomes simple, and it is difficult for fluid to stay in the fluid flow path.
Further, in this way, the region connecting the flow control valve 110 and the pressure sensor 3 in the fluid flow path in the body 112 is created by forming two inclined holes, and no backfilling of the holes is required. Therefore, the processing of the body 112 is minimized, and the manufacturing is easy.

In this flow control system 100, the upper surface of the base 113 on which the body 112 is placed is an inclined surface that gradually goes upward from the inlet side of the fluid channel toward the outlet side of the fluid channel.
As a result, the horizontal part of the first flow path 141b and the horizontal part of the second flow path 142b constituting the fluid flow path in the body 112 placed on the base 113 are positioned at the outlet side from the position on the inlet side. The height of the first inclined flow path 145a decreases between the inlet side and the outlet side.
For this reason, the bubbles generated in the horizontal portions of the first and second flow paths 141b and 142b, or the bubbles flowing into the horizontal portions, have their buoyancy acting toward the outlet side of the fluid flow path. Becomes easier to move to the outlet side of the fluid flow path, and bubbles are less likely to stay.

Moreover, in the high first inclined flow path 145a among the fluid flow paths in the body 112, the height difference between the inlet side and the outlet side is reduced, so that the bubbles move to the outlet side by the fluid flowing in the fluid flow path. This makes it easier for bubbles to stay in the fluid flow path.
For this reason, even when the flow rate of the fluid flowing in the fluid flow path is very small, the bubbles easily move to the outlet side of the fluid flow path, and the bubbles are less likely to stay in the fluid flow path.

In addition, the inclination angle θ with respect to the horizontal plane of the upper surface 113a of the base 113 can be an arbitrary angle of 90 ° or less. The larger the inclination angle θ, the higher the bubble discharging effect.
Here, instead of using the upper surface 113a of the base 113 as an inclined surface as in the present embodiment, the outlet side of each part of the fluid flow path in the body 112 is made higher than the inlet side, or the outlet side is designed to be the inlet side. The same effect can be obtained by designing the area that must be set lower than the above in order to minimize the height difference between the outlet side and the inlet side.

Further, according to the flow control system 100 configured as in the present embodiment, the user operates the motor 115 of the flow control valve 110 so that the rotating shaft 115a of the motor 115 moves in one direction (for example, FIG. When it is rotated clockwise (as viewed from the side), the coupling 116 rotates in one direction together with the rotating shaft 115a. When the coupling 116 rotates, the slider 117 coupled via the male threaded portion 116c of the coupling 116 and the female threaded portion 117a of the slider moves upward (increases) along the motor shaft 131. When the slider 117 rises, the needle portion 114b and the diaphragm portion 114c of the diaphragm needle 114 connected to the slider 117 via the stopper 118 rise together toward the fully open state (the state indicated by the two-dot chain line in FIG. 5). . As the needle portion 114b rises, a gap is created between the fluid inlet 141a and the needle portion 114b, the valve is opened (open), and the fluid flows into the port 143, and the inside of the port 143 The filled fluid sequentially flows out toward the fluid outlet portion 142 through the fluid outlet 143c.
When it is desired to reduce the fluid flow rate or to close the valve itself, the motor 115 is operated to move the rotating shaft 115a of the motor 115 in the other direction (for example, counterclockwise as viewed from above in FIG. 4). You can rotate it.

According to the flow control valve 110 according to the present embodiment configured as described above, the spring 121 always applies a downward biasing force (in the direction in which the needle portion 114b of the diaphragm needle 114 is closed) to the slider 117. Since the backlash between the female screw portion 117a and the male screw portion 116c of the coupling 116 is reduced (or eliminated), it is possible to prevent (or eliminate) the occurrence of hysteresis in the flow rate. .
FIG. 7A shows a state in which the rotary shaft 115a is rotated in the closing direction after the flow rate control valve 110 according to the present embodiment is closed from the closed state by rotating the rotary shaft 115a three times in the opening direction. Is a graph in which the flow rate is measured for each rotation angle of the rotating shaft 115a, where the x mark in the graph is a measured value when opening from the closed state, and the Δ mark in the graph is when closing from the open state. The measured value is shown.
FIG. 7B shows a state in which the flow control valve that does not include the spring 121 that applies the downward biasing force to the slider 117 is rotated from the closed state to the fully opened state by rotating the rotary shaft 115a three times in the opening direction. It is a graph which shows the result of having rotated 115a in the closing direction, and having performed the same measurement as Fig.7 (a), the * mark in a graph is a measured value when opening from a closed state, and ● in a graph The mark indicates the measured value when closing from the open state.
Thus, according to the flow control valve 110 in which the downward biasing force is always applied to the slider 117 by the spring 121, the flow rate difference due to opening and closing of the valve, that is, the flow rate hysteresis can be greatly reduced or eliminated. .

Further, since the fluid outlet 143c is provided above the port 143, that is, above the fluid inlet 141a, generation of bubbles in the port 143 can be reduced or almost eliminated.
Further, a convex portion 114a is provided upward at the outer peripheral end of the diaphragm needle 114, and a convex portion 114d is provided downward. These convex portions 114a and 114d are respectively provided on the diaphragm cover 120. Since the concave groove 120d and the concave groove 112a of the body 112 are received in close contact with each other, the flow of the (liquid) fluid from the lower side to the upper side of the diaphragm needle 114 can be prevented.

  Furthermore, since a packing 119 is provided in which the inner peripheral end is sandwiched between the slider 117 and the stopper 118 and the outer peripheral end is sandwiched between the diaphragm cover 120 and the cover flange 122. One side (the lower side in the figure) of the packing 119 and the other side (the upper side in the figure), that is, the diaphragm needle 114 side and the motor 115 side can be completely separated, and in the space in which the motor 115 is housed. In addition, it is possible to reliably prevent the vaporized (liquid or gaseous) fluid (for example, a chemical solution such as hydrofluoric acid) from entering.

  Furthermore, since the body 112 is provided with a communication passage 120c communicating with the outside of the flow control valve 110, a gaseous fluid (chemical solution such as hydrofluoric acid, hydrochloric acid, nitric acid, etc.) accumulated on one surface side of the packing 119 is provided. Gas) can be quickly discharged to the outside, and the movement of the diaphragm needle 114 can be prevented from being hindered. Further, the communication passage 120c serves as a breathing port, and the movement of the diaphragm needle 114 can be made smooth.

[ Second Embodiment]
Another embodiment of the flow control system according to the present invention will be described with reference to FIG.
The flow control system in the present embodiment is mainly characterized in that the flow control valve 150 is used instead of the flow control valve 110 in the flow control system 100 shown in the first embodiment. The flow control valve 150 is different from that of the first embodiment described above in that a spring 51 is provided instead of the spring 121. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment mentioned above.

  The spring 51 in this embodiment is a compression coil spring provided between the slider 117 and the cover flange 122, and always urges the slider 117 upward (toward the motor 115). As a result, backlash between the female threaded portion 117a of the slider 117 and the male threaded portion 116c of the coupling 116 is reduced (or eliminated).

According to the flow control valve 150 according to the present embodiment configured as described above, the direction of the force that the fluid passing through the port 143 exerts on the diaphragm needle 114 coincides with the direction in which the spring 51 urges the slider 117. Therefore, the fluctuation of the backlash between the female screw portion 117a and the male screw portion 116c due to the pressure difference of the fluid can be substantially eliminated, so that the flow rate difference due to opening and closing of the valve, that is, the flow rate hysteresis can be substantially eliminated.
Since other effects are the same as those of the first embodiment described above, description thereof is omitted here.

In the first and second embodiments described above, the rotating shaft 115a and the slider 117 are connected via the coupling 116, but the present invention is not limited to such a configuration. It is also possible to eliminate the coupling 116 by providing a male screw portion directly on the outer surface of the rotating shaft 115a.
As a result, the distance between the motor 115 and the slider 117 can be shortened, the longitudinal lengths (lengths in the longitudinal direction) of the flow control valves 110 and 150 can be shortened, and the valve can be downsized. Can be planned.

[ Third Embodiment]
Hereinafter, another embodiment of the flow control system according to the present invention will be described with reference to FIGS.
The flow control system shown in the present embodiment is mainly characterized in that the flow control valve 160 is used instead of the flow control valve 150 in the flow control system shown in the second embodiment. The flow control valve 160 is mainly characterized in that in the flow control valve 150 shown in the second embodiment, the mounting structure of the motor 115 with respect to the body 112 is changed. Hereinafter, members that are the same as or the same as those of the flow control valve 150 shown in the second embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In the flow control valve 160 shown in the present embodiment, as a fixing member for fixing the motor 115 to the body 112, instead of the diaphragm cover 120, the cover flange 122, and the motor shaft 131, a diaphragm cover in which a part of the configuration is changed. 170, a cover flange 172, and a housing 181 are used.

In the present embodiment, the lower end of the motor 115 is provided with a cylindrical portion 162 that is coaxial with the rotating shaft 115a and protrudes downward from the lower surface 115c, and the outer peripheral surface of the cylindrical portion 162 is the first positioning reference surface 163. ing.
The lower surface 115c of the motor 115 is a plane that is substantially orthogonal to the rotating shaft 115a.
The housing 181 is a substantially cylindrical member into which the rotating shaft 115a of the motor 115 is inserted and allows the slider 117 to be displaced vertically.

An inner flange 182 into which the cylindrical portion 162 of the motor 115 is inserted is provided at the upper end of the housing 181, and an annular ridge 183 that protrudes downward from the lower end surface is provided at the lower end. Yes. In the present embodiment, the inner flange 182 and the protrusion 183 are coaxial with the axis of the housing 181.
The inner peripheral surface of the inner flange 182 has a cylindrical inner surface shape whose inner diameter is substantially the same as the outer diameter of the cylindrical portion 162 of the motor 115, and this inner peripheral surface defines the first positioning reference surface 163 of the motor 115. The first positioning surface 186 for positioning the motor 115 so as to be coaxial with the axis of the inner flange 182 is formed.
Further, the inner peripheral surface of the protrusion 183 is a second positioning reference surface 187 having a cylindrical inner surface coaxial with the first positioning surface 186.

The cover flange 172 is provided with a cylindrical portion 173 protruding upward on the upper surface thereof coaxially with the through hole 122a, and an annular protrusion 174 protruding downward on the lower surface.
The cylindrical portion 173 is inserted on the inner peripheral side of the protrusion 183 of the housing 181, and the outer peripheral surface thereof forms a cylindrical surface having substantially the same diameter as the inner diameter of the protrusion 183 of the housing 181. The outer peripheral surface is a cylindrical second positioning surface 175 that receives the second positioning reference surface 187 of the housing 181 and positions the housing 181 so as to be coaxial with the through hole 122a.
Here, on the upper surface of the cover flange 172, the annular portion located on the outer peripheral side of the columnar portion 173 is a plane substantially orthogonal to the through hole 122a.
Further, the inner peripheral surface of the protrusion 174 is a third positioning reference surface 176 having a cylindrical inner surface coaxial with the second positioning surface 175, and the front end surface (lower end surface) of the protrusion 174 is a through hole 122a. The plane is substantially perpendicular to the plane.

The diaphragm cover 170 is provided with a cylindrical portion 177 protruding upward on the upper surface thereof so as to be coaxial with the through hole 120a.
The cylindrical portion 177 is inserted on the inner peripheral side of the ridge 174 of the cover flange 172, and the outer peripheral surface thereof forms a cylindrical surface having the same diameter as the inner diameter of the ridge 174 of the cover flange 172. The outer peripheral surface is a third positioning surface 179 that receives the third positioning reference surface 176 of the cover flange 172 and positions the cover flange 172 so as to be coaxial with the through hole 120a.

Here, on the upper surface of the diaphragm cover 170, the annular portion located on the outer peripheral side of the cylindrical portion 177 is a plane substantially orthogonal to the through hole 120a.
The outer peripheral surface of the diaphragm cover 170 is received by the inner surface of the cover 123 attached to the body 112, and is positioned so that the through hole 120a is coaxial with the diaphragm needle 114.

A guide pin 184 is installed on the upper surface of the cover flange 172 so as to be substantially parallel to the axis of the rotating shaft 115 a of the motor 115. The slider 117 has an inner peripheral surface of the bifurcated portion and an outer peripheral surface of the motor shaft 131. Instead of this, the guide pin 184 is in contact with the outer peripheral surface, thereby preventing the rotating shaft 115a and the slider 117 from rotating.
A stopper 185 is provided at the upper end of the guide pin 184 so as to protrude from the upper surface of the slider 117 and receive the upper surface of the slider 117.
The stopper 185 receives the slider 117 before the slider 117 comes into contact with the base of the convex portion 116b of the coupling 116 when the slider 117 is lifted by rotating the rotating shaft 115a of the motor 115, and the slider 117 or more. The increase of 117 is regulated.

In the flow control valve 160 configured as described above, the first positioning reference of the motor 115 is obtained by inserting the cylindrical portion 162 of the motor 115 into the inner flange 182 of the housing 181 when the motor 115 is assembled to the body 112. The surface 163 is received by the first positioning surface 186 of the housing 181, and the rotation shaft 115 a of the motor 115 is coaxial with the axis of the inner flange 182 of the housing 181 and the protrusion 183.
In this state, the cylindrical portion 173 of the cover flange 172 is inserted into the inner peripheral side of the protrusion 183 of the housing 181 so that the second positioning reference surface 187 of the housing 181 is received by the second positioning surface 175 of the cover flange 172. Thus, the protrusion 183 of the housing 181 is coaxial with the cylindrical portion 173, the protrusion 174, and the through hole 122a of the cover flange 172. That is, the rotating shaft 115a of the motor 115 is coaxial with the cylindrical portion 173, the protrusion 174, and the through hole 122a of the cover flange 172.

In this state, the columnar portion 177 of the diaphragm cover 170 is inserted into the inner peripheral side of the protrusion 174 of the cover flange 172 so that the third positioning reference surface 176 of the cover flange 172 becomes the third positioning surface 179 of the diaphragm cover 170. The protrusion 174 of the cover flange 172 is coaxial with the cylindrical portion 177 and the through hole 120a of the diaphragm cover 170. That is, the rotating shaft 115a of the motor 115 is coaxial with the cylindrical portion 177 and the through hole 120a of the diaphragm cover 170.
Since the diaphragm cover 170 is positioned with respect to the body 112 such that the through hole 120a is coaxial with the diaphragm needle 114, the rotating shaft 115a of the motor 115 is also coaxial with the diaphragm needle 114.

As described above, in the flow control valve 160 shown in the present embodiment, the motor 115, the housing 181, the cover flange 172, and the diaphragm cover 170 are joined together by so-called inlays, so that by simply connecting these members, Since both the position and orientation of the motor 115 with respect to 112 are positioned and are in a state suitable for driving the diaphragm needle 114, position adjustment work and orientation adjustment work of the motor 115 with respect to the body 112 become unnecessary.
For this reason, the flow control valve 160 can be easily and quickly assembled with high accuracy regardless of the technical level of the assembly operator at the time of manufacture and maintenance, and thus has excellent productivity and workability. Variations in assembly accuracy for each product or each maintenance operation can be reduced, and the performance as a flow control valve can be maintained at a high level.

Here, each positioning reference surface is not limited to the cylindrical surface or the cylindrical inner surface as described above, but one or more curved surfaces, or at least one surface is directed in a direction different from the other surfaces. It can be constituted by a plurality of planes. When the positioning reference surface is a curved surface, the corresponding positioning surface is configured by a curved surface having the same curvature as the curved surface and the direction of the curvature being opposite.
When the positioning reference surfaces provided on the motor and the fixed member are a plurality of planes, the positioning surfaces of the members coupled thereto are also constituted by a plurality of planes corresponding to the positioning reference surfaces.

Further, in this flow control valve 160, since the stopper 185 is provided on the guide pin 184 that prevents the slider 117 from rotating, when the slider 117 is lifted, the root of the convex portion 116b of the slider 117 and the coupling 116 is provided. Interference is prevented, problems such as these bites are reliably prevented, and a satisfactory operation can always be performed.
The characteristic configuration of the present embodiment can be applied not only to the flow control valve 150 shown in the second embodiment but also to the flow control valve 110 shown in the first embodiment.

[ Fourth Embodiment]
Hereinafter, another embodiment of the flow control system according to the present invention will be described with reference to FIG.
The flow control system shown in the present embodiment is mainly characterized in that the flow control valve 190 is used instead of the flow control valve 160 in the flow control system shown in the third embodiment.
The flow control valve 190 is mainly characterized in that, in the flow control valve 160 shown in the third embodiment, a thrust bearing 191 that receives a thrust load applied to the rotating shaft 115a is provided outside the motor body 15d of the motor 115. is there. Hereinafter, the same or identical members as those of the flow control valve 150 shown in the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

In the present embodiment, a thrust bearing 191 is provided between the lower surface of the cylindrical portion 162 of the motor 115 and the upper surface of the coupling 116.
In the flow control valve 190 configured as described above, when the diaphragm needle 114 receives fluid pressure, it should be transmitted to the rotary shaft 115a through the diaphragm needle 114, the slider 117, and the coupling 116. The thrust load is received by the thrust bearing 191 provided outside the motor main body 15d and released to the motor main body 15d. Therefore, the load applied to the support structure of the rotating shaft 115a in the motor 115 is reduced, and the motor 115 can be used for a long time. The performance can be maintained.
The characteristic configuration of this embodiment is not limited to the flow control valve 160 shown in the third embodiment, but the flow control valve 110 shown in the first embodiment and the flow control valve 150 shown in the second embodiment. Can be applied to.

[ Fifth Embodiment]
Hereinafter, another embodiment of the flow control system according to the present invention will be described with reference to FIGS. 11 and 12.
The flow control system shown in this embodiment is mainly characterized in that the flow control valve 201 is used as the flow control valve in the flow control system shown in any of the first , second , third , and fourth embodiments. It is what.
The flow control valve 201 is a flow control valve shown in any one of the first , second , third , and fourth embodiments. The motor 115 is a stepping motor and a control device 202 that controls the operation of the motor 115 is provided. Is the main feature.
When the position of the diaphragm needle 114 is calibrated, the control device 202 has a pulse signal with the number of pulses sufficient to rotate the rotation shaft 115a of the motor 115 at an angle necessary for the diaphragm needle 114 to move from one end of the movable range to the other end. Is input to the motor 115, and it is determined that the diaphragm needle 114 is located at the other end of the movable range at the position where the rotating shaft 115a is stopped. Thereafter, the position of the diaphragm needle 114 is controlled within the movable range. It is said that.

Specifically, the controller 202 calibrates the position of the diaphragm needle 114 so that the angle necessary for the diaphragm needle 114 to move from one end to the other end of the movable range (this angle is determined from the design information of the flow control valve 201). A pulse signal having a predetermined number of pulses is input to the motor 115 so that the rotation shaft 115a of the motor 115 is rotated as much as possible.
In this embodiment, as shown in FIG. 12, the controller 202 calibrates the position of the diaphragm needle 114, the rotating shaft 115 a on the open side of the movable range of the diaphragm needle 114 (FIG. 4, FIG. 5, FIG. 6). The diaphragm needle 114 is moved to the fully open position by rotating in the direction of movement toward the upper side in FIGS.

  Thereby, when the rotation of the rotating shaft 115a is completed, the diaphragm needle 114 is positioned at the other end of the movable range regardless of the position (initial position) at the start of the position calibration operation. When the diaphragm needle 114 is located at a position other than one end of the movable range at the time of starting the position calibration of the diaphragm needle 114, the rotation shaft 115a has an angle corresponding to all the pulses of the pulse signal input to the motor 115. Before the rotation, the diaphragm needle 114 arrives at the other end of the movable range and cannot move any further, and thereafter, the rotating shaft 115a does not rotate regardless of the remaining number of pulses.

After the diaphragm needle 114 is positioned at the other end of the movable range in this manner, the control device 202 determines that the diaphragm needle 114 is positioned at the other end of the movable range, and the diaphragm needle 114 is within the movable range. Position control is performed.
In the present embodiment, the control device 202 inputs a pulse signal having a pulse number sufficient to move the diaphragm needle 114 to one end (fully closed position) of the movable range after the rotating shaft 115a stops, and rotates the motor 115. The position where the shaft 115a is stopped is set as the origin of position control of the diaphragm needle 114, and thereafter, the diaphragm needle 114 is moved within a preset operation range to perform necessary control.

When the diaphragm needle 114 is within the movable range, the rotation shaft rotates at an angle corresponding to all the pulses of the pulse signal input to the motor 115, so that the number of pulses of the pulse signal and the position of the diaphragm needle 114 are A certain relationship is established between them.
Thereby, in the flow control valve 201 of the present embodiment, once the diaphragm needle 114 is positioned at the other end of the movable range, the position of the diaphragm needle 114 is determined based on the number of pulses of the pulse signal input to the motor 115 thereafter. Thus, the position of the diaphragm needle 114 can be accurately grasped without using a rotary encoder.

  Further, in the present embodiment, when the position of the diaphragm needle 114 is calibrated, the diaphragm needle 114 is moved toward the open side of the movable range, that is, in a direction that avoids interference with the needle accommodating portion 143a of the flow control valve 201. Therefore, even if the position calibration of the diaphragm needle 114 is repeated, the diaphragm needle 114 and the body 112 are hardly damaged.

Here, when the technique shown in the present embodiment is applied to the flow rate control valve shown in the first or second embodiment, the control device 202 is connected to the end portion at least near the end of the movable range of the diaphragm needle 114. When the diaphragm needle 114 moves away from the end of the movable range, the rotating shaft 115a of the motor 115 is moved to the first driving torque. It is good also as a structure rotated with a 2nd driving torque larger than this.

In this case, when the diaphragm needle 114 is moved away from the end of the movable range, the control device 202 that controls the operation of the motor 115 drives the driving torque (first torque when moving the diaphragm needle 114 to the end of the movable range. The motor 115 is operated with a second driving torque larger than (one driving torque).
Thereby, in this flow control valve, even if the screw portion is caught when the diaphragm needle 114 moves to the end of the movable range, this biting can be easily eliminated.

The driving force of the motor 115 is proportional to the driving current supplied to the motor 115.
Therefore, when the control device 202 moves the diaphragm needle 114 to the end of the movable range, the output limit value of the drive current of the motor 115 is set to the first limit value V1, and the diaphragm needle 114 is moved to the end of the movable range. The control described above can be realized by setting the output limit value to the second limit value V2 that is larger than the first limit value V1 when separating from the first limit value.

Further, the motor 115 increases the torque for driving the rotating shaft 115a as the rotating shaft 115a rotates at a lower speed.
Therefore, when the control device 202 moves the diaphragm needle 114 to the end of the movable range, the rotating shaft 115a of the motor 115 is rotated at the first rotation speed R1, and the diaphragm needle 114 is separated from the end of the movable range. In some cases, the above-described control can be realized by rotating at a second rotation speed R2 lower than the first rotation speed R1.

  In addition, this invention is not limited to embodiment mentioned above, In the range which does not deviate from the summary of this invention, it can change suitably.

It is a block diagram showing a flowmeter according to a reference example of the present invention. It is a block diagram which shows the experimental apparatus of the flowmeter which concerns on the reference example of this invention. It is a graph of the case result obtained with the experimental apparatus of FIG. It is a longitudinal section showing the flow control system concerning a 1st embodiment of the present invention. It is a principal part enlarged view of FIG. It is a figure which shows the flow control valve of the flow control system which concerns on 2nd Embodiment of this invention, Comprising: It is a figure similar to FIG. It is a graph which shows the relationship between the rotation angle of the rotating shaft of a motor, and flow volume, Comprising: (a) is the measurement result measured using the flow control valve shown in FIG.4 and FIG.5, (b) is the conventional flow control valve. It is the measurement result measured using. It is a longitudinal cross-sectional view which shows the flow control valve of the flow control system concerning 3rd Embodiment of this invention. FIG. 8 is a partially enlarged view of FIG. 7. It is a longitudinal cross-sectional view which shows the flow control valve of the flow control system which concerns on 4th Embodiment of this invention. It is a block diagram which shows the flow control valve of the flow control system which concerns on 5th Embodiment of this invention. It is a figure which shows operation | movement of the flow control valve shown in FIG.

DESCRIPTION OF SYMBOLS 1 Fluid flow path 1a End 2 Flow control valve 3 Pressure sensor (pressure detection means)
4 Pressure detection control unit (pressure / flow rate conversion means)
5 Flow Measurement Pipeline 10 Flowmeter 100 Flow Control System 110 Flow Control Valve 112 Body 113 Base (Pedestal)
114 Diaphragm needle (valve)
115 Motor 115a Rotating shaft 115d Motor body 116c Male thread part 117a Female thread part 119 Packing 121 Spring (biasing means)
123 Cover 141 Fluid inlet 142 Fluid outlet 145a First inclined channel 145b Second inclined channel 150 Flow rate control valve 151 Spring (biasing means)
160 Flow control valve 163 First positioning reference surface 170 Diaphragm cover (fixing member)
172 Cover flange (fixing member)
175 Second positioning surface 176 Third positioning reference surface 179 Third positioning surface 180 Housing (fixing member)
186 First positioning surface 187 Second positioning reference surface 190 Flow rate control valve 191 Thrust bearing 201 Flow rate control valve 202 Control device

Claims (11)

A flowmeter for measuring a minute flow rate of a liquid flowing through a fluid flow path having a constant pressure in an outlet environment, connected to the outlet side end of the fluid flow path, and having a flow channel cross-sectional area smaller than the fluid flow path And a pressure detection unit configured to detect the pressure of the liquid upstream of the flow rate measurement pipe unit by being installed in the vicinity of the outlet of the fluid flow channel and a predetermined length of the flow rate measurement pipe unit with the outlet environment as a constant pressure. means, a flow meter for ingredients Bei pressure / flow rate conversion means, a for calculating the flow rate from the fluid pressure detected by said pressure detecting means,
A flow control valve;
A block-like body in which the flow control valve and the flow meter are provided on one side and a fluid flow path for connecting the flow control valve and the flow meter is provided inside;
A first inclined channel that gradually moves from the region where the flow control valve on the one surface is installed toward the inside of the body toward the region where the flow meter is installed;
A second inclined channel that gradually goes from the region where the flow meter on the one surface is installed toward the inside of the body toward the region where the flow control valve is installed and is connected to the tip of the first inclined channel; Have
It has a pedestal on which the body is placed on the upper surface,
The flow rate control system according to claim 1, wherein the upper surface of the pedestal has an inclined surface that gradually goes upward as it goes from the inlet side of the fluid channel to the outlet side of the fluid channel . The flow rate control system according to claim 1, wherein the flow meter has a constant pressure in the outlet environment that is an atmospheric pressure due to release to the atmosphere. 3. The flow rate control system according to claim 1, wherein at least a part of the fluid flow path is inclined so that an outlet side is positioned higher than an inlet side. 4. The flow control valve, a motor attached to the body;
A valve body connected via a screw portion to the rotating shaft of the motor;
A positioning reference surface is provided on the motor,
A fixing member for fixing the motor to the body is provided,
A positioning surface that receives the positioning reference surface of the motor and positions the motor so that at least one of the position and orientation of the rotating shaft is suitable for driving the valve body; It has, The flow control system in any one of Claim 1 to 3 characterized by the above-mentioned. The positioning reference surface of the motor is a cylindrical surface or a cylindrical inner surface parallel to the rotation axis;
The positioning surface of the fixing member forms a cylindrical inner surface or a cylindrical surface that is parallel to the driving direction of the valve body and has the same shape as the positioning reference surface, and the positioning surface receives the positioning reference surface The flow rate control system according to claim 4 , wherein the position and orientation of the rotating shaft are positioned. Having a stopper that receives the valve element that has reached the end of the operating range while restricting the movement of the valve element within a preset operating range and restricts the movement out of the operating range. The flow rate control system according to claim 4 or 5 , characterized by the above. A control device for controlling the operation of the motor;
The control device operates the motor with the first driving torque at least when the valve body moves toward the end in the vicinity of the end of the movable range,
When the valve body is spaced from the end of the movable range, the flow rate control as claimed in claim 4 or 5, characterized in that for operating the motor at a greater second drive torque than the first drive torque system. The valve body constitutes a needle of a needle valve;
The motor is a stepping motor that rotates the rotating shaft by an angle proportional to the number of pulses of the input pulse signal;
A controller for controlling the position of the valve body by controlling the operation of the motor is provided;
When the position of the valve body is calibrated, the control device outputs a pulse signal having a pulse number sufficient to rotate the rotary shaft at an angle necessary for the valve body to move from one end to the other end of the movable range. Enter
It is determined that the valve body is located at the other end of the movable range at a position where the rotation shaft is stopped, and thereafter, the position control of the valve body is performed within the movable range. Item 7. The flow control system according to any one of Items 4 to 6 . 9. The flow rate according to claim 8, wherein the control device rotates the rotating shaft in a direction in which the valve body moves toward an open side of the movable range when the position of the valve body is calibrated. Control system. The control device operates the motor with the first driving torque when at least the valve body moves toward the end in the vicinity of the end of the movable range,
When the valve body is spaced from the end of the movable range, the flow rate control as claimed in claim 8 or 9, characterized in that for operating said motor at a second drive torque greater than the first driving torque system. Flow control system according to claim 4 1 0, characterized in that the motor body outside of the motor, provided with a thrust bearing which receives the thrust load applied to the rotating shaft.

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