JP5215831B2 - Pressure control device and flow rate control device - Google Patents

Description

  The present invention relates to a pressure control device that controls the pressure of a gas and a flow rate control device that uses a pressure-controlled gas.

In an electropneumatic regulator including an air supply solenoid valve and an exhaust solenoid valve, an air supply solenoid valve and an exhaust solenoid valve are connected by respective pulse signals generated based on the detected pressure of the output port and the target pressure. There is one that controls the detected pressure of the output port to the target pressure by simultaneously opening and closing and controlling the pressure of the pilot chamber formed in the main valve (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 7-36551

  By the way, in the electropneumatic regulator of patent document 1, the electromagnetic valve is driven to open and close by a pulse signal having a predetermined period, and the time for opening the electromagnetic valve changes according to the energization ratio in each period. Here, when the electromagnetic valve is driven in a certain cycle, the operation of the electromagnetic valve may be momentarily stopped or delayed due to the biting of a foreign object or an increase in frictional force. In this case, since the deviation between the detected pressure and the target pressure increases, the solenoid valve is driven by a pulse signal for reducing the increased deviation in the next cycle. However, the electromagnetic valve may not operate even with such a pulse signal. In this case, the electromagnetic valve needs to be driven with a pulse signal for reducing the deviation in the next cycle. For this reason, there is a possibility that a state in which the deviation between the detected pressure and the target pressure is large continues for a long time.

  The present invention has been made in view of the above circumstances, and in a pressure control device including an electromagnetic valve that is driven to open and close by a pulse signal having a predetermined period, when a deviation between a detected gas pressure and a target pressure increases. The main object of the present invention is to provide a pressure control device that can quickly reduce the deviation and a flow rate control device that uses a pressure-controlled gas.

  In order to solve the above-described problems, a first aspect of the invention relates to a solenoid valve for air supply that is connected to a gas supply source and is opened and closed by a pulse signal having a predetermined period, and a connection passage to the solenoid valve for air supply And an exhaust solenoid valve that is opened and closed by a pulse signal having the predetermined cycle, a discharge passage that leads out the gas from the connection passage, and the gas in the connection passage or in the discharge passage And a pulse signal for driving the supply solenoid valve and the exhaust solenoid valve in each cycle in order to set the detected pressure of the gas by the pressure detection means to a target pressure. A first pulse generating means for generating based on a deviation between the detected gas pressure and the target pressure, and the supply air on condition that a deviation between the detected gas pressure and the target pressure is not less than a determination value. And a second pulse generating means for changing the pulse signal generated by the first pulse generating means so as to reduce the deviation in a period in which the solenoid valve and the exhaust solenoid valve are driven. And

  According to the first aspect of the present invention, the gas supplied from the gas supply source is supplied to the gas supply source because it is connected to the gas supply source and is opened and closed by a pulse signal having a predetermined period. The flow rate is controlled by a solenoid valve. Since the exhaust solenoid valve is connected to the supply solenoid valve via a connection passage and is opened and closed by a pulse signal having the predetermined period, the gas flowing through the supply solenoid valve is exhausted. Is used to control the flow rate. And since it has the derivation | leading-out channel | path which guide | derived the said gas from the said connection channel | path, the gas by which the pressure was controlled by the flow control of the solenoid valve for supply and the solenoid valve for exhaust_gas | exhaustion is guide | induced to the lead-out passage.

  A pressure detection means for detecting the pressure of the gas in the connection passage or the lead-out passage; and for setting the gas detection pressure by the pressure detection means to a target pressure, First pulse generation means for generating the pulse signal for driving the exhaust solenoid valve in each cycle based on the deviation between the detected gas pressure and the target pressure is provided. The air solenoid valve and the exhaust solenoid valve are driven to open and close in each cycle, and the detected pressure of the derived gas is controlled to be the target pressure.

  Further, on the condition that the deviation between the detected gas pressure and the target pressure is equal to or greater than a determination value, the deviation is reduced in a cycle in which the supply solenoid valve and the exhaust solenoid valve are driven. Since the second pulse generating means for changing the pulse signal generated by the first pulse generating means is provided, for example, the electromagnetic valve does not operate due to some abnormality, and the deviation between the detected pressure and the target pressure is greater than or equal to the determination value. In this case, the solenoid valve is driven by the pulse signal changed so as to reduce the deviation. As a result, the possibility that the solenoid valve operates in the period driven by the changed pulse signal is increased, so that the deviation can be quickly reduced when the deviation between the detected gas pressure and the target pressure increases. it can. In order to reduce the deviation, the pulse signal generated by the first pulse generation unit is changed. The pulse signal generated by the first pulse generation unit so as to reduce the deviation is used. Or generating a pulse signal so that the deviation is smaller than the pulse signal generated by the first pulse generating means.

  In a second aspect based on the first aspect, the determination value is a value that can detect that the supply solenoid valve or the exhaust solenoid valve does not operate over two periods of the pulse signal. Therefore, the abnormality of the electromagnetic valve can be detected in a short period of two cycles of the pulse signal, and the deviation between the detected gas pressure and the target pressure can be reduced more quickly.

  According to a third invention, in the first or second invention, the second pulse generating means continues the state where the deviation is equal to or greater than the determination value for a determination period set shorter than the predetermined period. Further, the pulse signal generated by the first pulse generating means is changed under the above condition.

  According to the third aspect of the present invention, since the further condition for changing the pulse signal generated by the first pulse generating means is that the state where the deviation is equal to or greater than the determination value continues for the determination period or more, the deviation is The pulse signal can be changed after more reliably determining that the value is equal to or greater than the determination value. Furthermore, since this determination period is set to be shorter than the predetermined period, the period in which the state starts is included regardless of when the state in which the deviation is greater than or equal to the determination value starts in one period of the pulse signal. The determination can be completed within two cycles at the latest. As a result, it is possible to change the pulse signal that drives the solenoid valve in a faster cycle while more reliably determining that the deviation is greater than or equal to the determination value.

  According to a fourth aspect of the present invention, there is provided a pressure control device according to any one of the first to third aspects, and a flow rate adjusting means for adjusting a flow rate of a fluid based on a pressure applied by the gas supplied from the pressure control device. And a flow rate detecting means for detecting the flow rate of the fluid, and the target pressure of the gas based on a deviation between the detected flow rate and the target flow rate so that the detected flow rate of the fluid by the flow rate detecting means becomes a target flow rate And setting means for setting.

  According to the fourth invention, the flow rate of adjusting the flow rate of the fluid based on the pressure applied by the gas supplied from the pressure control device according to any of the first to third inventions and the gas supplied from the pressure control device. Therefore, the flow rate of the fluid is adjusted by the flow rate adjusting means based on the pressure controlled by the pressure control device. And a flow rate detecting means for detecting the flow rate of the fluid, and the target pressure of the gas based on a deviation between the detected flow rate and the target flow rate so that the detected flow rate of the fluid by the flow rate detecting means becomes a target flow rate. Since the pressure control device controls the gas pressure so that the target pressure is set in this manner, the detected flow rate of the fluid is controlled to be the target flow rate. Note that the flow rate detection means for detecting the flow rate of the fluid includes one that indirectly detects the flow rate of the fluid by detecting the pressure of the fluid.

  Here, when the deviation between the detected flow rate of the fluid and the target flow rate becomes large due to some abnormality, for example, the target pressure of the gas derived from the pressure control device is set based on the increased deviation. However, when an abnormality occurs in the pressure control device, the detected flow rate of the fluid adjusted by the flow rate adjusting means is not properly controlled so that the detected pressure of the gas derived from the pressure control device becomes the target pressure. It is difficult to quickly reach the target flow rate.

  In this respect, since the fourth invention includes the pressure control device according to any one of the first to third inventions, the deviation is rapidly reduced when the deviation between the detected gas pressure and the target pressure is increased. be able to. As a result, even if an abnormality occurs in the pressure control device, the detected flow rate of the fluid adjusted by the flow rate adjusting means can be quickly set to the target flow rate.

  Hereinafter, an embodiment embodying a pressure control device according to the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram showing an overall configuration of a chemical liquid supply circuit including a pressure control device.

  As shown in FIG. 1, this circuit is provided with a chemical pump 21 for sucking and discharging chemical liquid. The chemical pump 21 is composed of, for example, a diaphragm pump or a bellows pump. The chemical liquid stored in the chemical liquid tank X is sucked by the chemical liquid pump 21 through the suction pipe 31 constituting the chemical liquid suction passage.

  On the discharge side of the chemical liquid pump 21, a discharge pipe 32 constituting a chemical liquid discharge passage is connected. A pilot regulator 22 as a flow rate adjusting means is provided on the downstream side of the discharge pipe 32. The chemical liquid discharged from the chemical liquid pump 21 is adjusted to a predetermined flow rate by the pilot regulator 22 and discharged to the wafer 23. The downstream end of the discharge pipe 32 is a discharge nozzle 32 a that discharges the chemical liquid to the wafer 23.

  The pilot regulator 22 applies an operating pressure with the air derived from the electropneumatic regulator 40 and adjusts the flow rate of the chemical solution based on the operating pressure. Specifically, the pilot regulator 22 adjusts the flow rate of the chemical solution by displacing the diaphragm by air supplied to the pilot chamber and driving a valve body connected to the diaphragm. The electropneumatic regulator 40 adjusts the operating pressure of the pilot regulator 22 by controlling the supply and discharge of air to the pilot regulator 22. The pilot regulator 22 and the electropneumatic regulator 40 are connected by an air passage 35, and air for adjusting the operation pressure flows through the air passage 35. The electropneumatic regulator 40 constitutes a pressure control device that controls the pressure of the gas to be led out, and the air passage 35 constitutes a lead-out passage that leads out the gas.

  Further, in the discharge pipe 32, a flow rate sensor 71 is provided between the chemical solution pump 21 and the pilot regulator 22 as flow rate detection means for detecting the flow rate of the chemical solution.

  The flow rate controller 60 is an electronic control unit mainly composed of a microcomputer including a CPU and various memories. In addition to the target flow rate of the chemical solution being input to the flow rate controller 60 from a management computer that manages and manages the system, the detected flow rate of the chemical solution detected by the flow rate sensor 71 is sequentially input. The flow rate controller 60 drives the electropneumatic regulator 40 based on these inputs, and performs flow rate feedback control so that the detected flow rate matches the target flow rate.

  The flow rate controller 60 calculates a deviation between the target flow rate input from the management computer and the detected flow rate detected by the flow rate sensor 71, and performs calculation processing such as PID calculation based on the deviation, to the electropneumatic regulator 40. On the other hand, the target pressure as the operation pressure is output. The electropneumatic regulator 40 adjusts the operation pressure for controlling the pilot regulator 22 by controlling the supply and discharge of air to the pilot regulator 22 based on the target pressure from the flow rate controller 60. By repeatedly executing such processing, the detected flow rate of the chemical solution is converged to the target flow rate. The flow rate controller 60 constitutes setting means for setting the target pressure of gas.

  Next, an outline of the electropneumatic regulator 40 will be described based on the circuit diagram of FIG.

  The electropneumatic regulator 40 is connected to the pilot regulator 22 by an air passage 35, and adjusts an operation pressure for controlling the pilot regulator 22 by controlling supply and discharge of air to the pilot regulator 22.

  The electropneumatic regulator 40 includes an air supply solenoid valve 43 on the air supply side and an exhaust electromagnetic valve 44 on the air discharge side. The electromagnetic valves 43 and 44 are driven to open and close by a pulse signal having a predetermined period to perform air circulation and shut-off. Specifically, the amount and period during which the plunger, which is the valve body of the electromagnetic valves 43 and 44, is displaced to the open state changes according to the energization ratio in each cycle. For example, the pulse signal has a period of several tens of ms, and the ratio of the energization time in this period changes in the range of 0 to 100%. These solenoid valves 43 and 44 are normally closed solenoid valves that shut off air when not energized.

  The supply solenoid valve 43 and the exhaust solenoid valve 44 are connected by a connection passage 46, and the air passage 35 is connected to the connection passage 46. The air can be supplied to and discharged from the air passage 35.

  In addition, a pressure sensor 72 is provided in the connection passage 46 that connects the air supply solenoid valve 43 and the exhaust solenoid valve 44, and an operation pressure for controlling the pilot regulator 22 is provided in the connection passage 46. The pressure sensor 72 detects the air pressure. This detected pressure is output to the pressure controller 41. The pressure sensor 72 may be provided in the air passage 35. The pressure sensor 72 constitutes pressure detection means for detecting the gas pressure in the connection passage or the outlet passage.

  The pressure controller 41 is an electronic control unit mainly composed of a microcomputer including a CPU and various memories. In addition to the target pressure as the operation pressure being input from the flow rate controller 60, the detected pressure detected by the pressure sensor 72 is sequentially input to the pressure controller 41. The pressure controller 41 drives the solenoid valves 43 and 44 based on these inputs, and performs feedback control so that the detected pressure of air matches the target pressure.

  Specifically, the pressure controller 41 generates a pulse signal for driving the air supply solenoid valve 43 and the exhaust solenoid valve 44 in each cycle in order to set the detected pressure of air by the pressure sensor 72 to a target pressure. The PID calculation is performed based on the deviation between the detected pressure and the target pressure. For example, when increasing the air pressure, the rate of opening the supply solenoid valve 43 within one cycle of the pulse signal is increased, and the amount of air supplied to the air passage 35 through the supply solenoid valve 43 is increased. In addition, the ratio of opening the exhaust solenoid valve 44 within one cycle of the pulse signal is decreased, and the amount of air discharged from the air passage 35 through the exhaust solenoid valve 44 is decreased.

  Here, as shown in FIG. 3, when the solenoid valves 43 and 44 are normal (solid line), the plunger displacement of the solenoid valves 43 and 44 increases in proportion to the energization ratio in each cycle of the pulse signal. However, when any abnormality occurs in the solenoid valves 43 and 44 (broken line), the plunger displacement of the solenoid valves 43 and 44 is not proportional to the energization ratio in each cycle of the pulse signal. For example, when the solenoid valve 44 is driven with a pulse signal having a duty D1 in a certain cycle, it is assumed that the operation of the plunger of the solenoid valve 44 is temporarily stopped due to the biting of a foreign object or an increase in frictional force. In this case, since the deviation between the detected pressure input from the pressure sensor 72 and the target pressure input from the flow controller 60 increases, the pulse signal of duty D2 is used to reduce the increased deviation in the next cycle. Thus, the electromagnetic valve 44 is driven. However, since the plunger of the electromagnetic valve 44 hardly operates even with the pulse signal with the duty D2, in this case, the electromagnetic valve 44 needs to be driven with the pulse signal for reducing the deviation in the next cycle. For this reason, there is a possibility that a state in which the deviation between the detected pressure and the target pressure is large continues for a long time.

  Therefore, in the present embodiment, the deviation is reduced in the cycle in which the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven on condition that the deviation between the detected air pressure and the target pressure is equal to or greater than the determination value. As described above, the pulse signal generated by performing the PID calculation is changed. Below, the procedure of the air pressure control by the electropneumatic regulator 40 is demonstrated with reference to the flowchart of FIG. This process is repeatedly executed by the pressure controller 41 with a predetermined cycle.

  As shown in FIG. 4, first, the target pressure Pt is input (step 110). Specifically, the target pressure Pt set by the flow controller 60 is input to the pressure controller 41. After the target pressure Pt is input in this way, the detected pressure Pd is input (step 120). Specifically, the detected air pressure Pd detected by the pressure sensor 72 is input to the pressure controller 41.

  Subsequently, a pressure deviation ΔP between the detected pressure Pd and the target pressure Pt is calculated (step 130), and a pulse signal Db for driving each electromagnetic valve is generated based on the pressure deviation ΔP (step 140). Specifically, the pressure controller 41 includes a pulse signal Db (duty Dbi) for driving the air supply solenoid valve 43 in each cycle and an exhaust solenoid valve 44 to set the detected pressure Pd to the target pressure Pt. A pulse signal Db (duty Dbe) that is driven in a cycle is generated by performing a PID calculation based on a deviation ΔP between the detected air pressure Pd and the target pressure Pt. For example, when the air pressure is increased, the ratio of opening the supply electromagnetic valve 43 within one cycle of the pulse signal Db is increased, that is, the duty Dbi of the pulse signal Db for driving the supply electromagnetic valve 43 is increased. The amount of air supplied to the air passage 35 through the air supply solenoid valve 43 is increased. At the same time, the ratio of opening the exhaust solenoid valve 44 within one cycle of the pulse signal Db is decreased, that is, the duty Dbe of the pulse signal Db for driving the exhaust solenoid valve 44 is reduced to reduce the air through the exhaust solenoid valve 44. The amount of air discharged from the passage 35 is reduced.

  After the pulse signal Db is generated in this way, it is determined whether or not the pressure deviation ΔP is greater than or equal to a determination value Rp (step 150). Here, the determination value Rp indicates that the supply solenoid valve 43 or the exhaust solenoid valve 44 did not operate over one cycle or several cycles with respect to the cycle of the pulse signal Db for driving them, or the operation was delayed. For example, a value that can detect that the supply solenoid valve 43 or the exhaust solenoid valve 44 did not operate over two periods of the pulse signal Db. That is, if the plunger of the supply solenoid valve 43 or the exhaust solenoid valve 44 is temporarily stopped and does not operate, the supply or discharge of air cannot be performed properly. Deviation ΔP between detected pressure Pd and target pressure Pt increases. Then, after removing the influence of the detection error of the pressure sensor 72 and the delay until the detection, the determination value Rp is set to a value that can detect such a state at an early stage.

  If it is determined in the above determination that the pressure deviation ΔP is not equal to or greater than the determination value Rp (step 150: NO), the supply solenoid valve 43 and the exhaust solenoid valve 44 are determined by the pulse signal Db (duty Dbi and duty Dbe). Are driven (step 160). That is, when it is determined that the pressure deviation ΔP is not equal to or greater than the determination value Rp, there is no abnormality in the supply solenoid valve 43 and the exhaust solenoid valve 44, and the detected air pressure Pd is close to the target pressure Pt. The value is considered to be controlled. Therefore, the supply solenoid valve 43 and the exhaust solenoid valve are generated by the pulse signal Db (duty Dbi and duty Dbe) generated by performing the PID calculation based on the deviation ΔP between the detected air pressure Pd and the target pressure Pt. 44 are respectively driven.

  On the other hand, when it is determined in the above determination that the pressure deviation ΔP is greater than or equal to the determination value Rp (step 150: YES), it is determined whether or not the duration T of that state is equal to or greater than the determination period Rt (step). 170). Specifically, the timer counter starts counting when it is determined that the pressure deviation ΔP is equal to or greater than the determination value Rp, and the duration T is equal to or greater than the determination period Rt depending on whether the count is equal to or greater than the determination value. It is determined whether or not. Here, the determination period Rt is set to be shorter than several tens of milliseconds, which is the cycle of the pulse signal Db, and is set to several milliseconds, for example. That is, the determination period Rt is set to a value that can more reliably determine that the state in which the pressure deviation ΔP is equal to or greater than the determination value Rp continues. Furthermore, since this determination period Rt is set to be shorter than the cycle of the pulse signal Db, the cycle in which the state starts is set regardless of when the state in which the deviation is greater than or equal to the determination value Rp starts in one cycle. Including the determination can be completed within two cycles at the latest. If it is determined that the pressure deviation ΔP is not greater than or equal to the determination value Rp, the timer counter is reset.

  In the above determination, when it is determined that the duration T in which the pressure deviation ΔP is equal to or greater than the determination value Rp is not equal to or greater than the determination period Rt (step 170: NO), the pulse signal Db (duty Dbi and duty Dbe) Thus, the supply solenoid valve 43 and the exhaust solenoid valve 44 are respectively driven (step 160). That is, when it is determined that the duration T of the state where the pressure deviation ΔP is equal to or greater than the determination value Rp is not equal to or greater than the determination period Rt, the pressure deviation ΔP returns to a state where the pressure deviation ΔP is smaller than the determination value Rp in a relatively short period. Alternatively, it is considered that the pressure deviation ΔP may return to a state where it is smaller than the determination value Rp. Therefore, the pulse signal Db is not immediately changed, and the supply electromagnetic valve 43 and the exhaust electromagnetic valve 44 are driven by the pulse signal Db, and control is performed according to the subsequent state.

  On the other hand, in the above determination, when it is determined that the duration T in which the pressure deviation ΔP is equal to or greater than the determination value Rp is equal to or greater than the determination period Rt (step 170: YES), the pulse signal Db is corrected and the pulse is corrected. A signal Dr is generated (step 180). That is, when it is determined that the duration T in which the pressure deviation ΔP is equal to or greater than the determination value Rp is equal to or greater than the determination period Rt, the operation of the supply solenoid valve 43 or the exhaust solenoid valve 44 is stopped or delayed. It is considered that it is desirable to restore these operations at a faster cycle. For this reason, the pulse signal Db (duty Dbi and duty Dbe) generated by the PID calculation is changed so that the pressure deviation ΔP is reduced in the period in which the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven. To do. Specifically, the duty Dbi and the duty Dbe generated by the PID calculation are respectively increased or decreased so as to reduce the deviation ΔP. For example, when the detected air pressure Pd is higher than the target pressure Pt, it is necessary to shorten the period for opening the supply solenoid valve 43 and lengthen the period for opening the exhaust solenoid valve 44. Therefore, the duty Dbi of the supply solenoid valve 43 is reduced and the duty Dbe of the exhaust solenoid valve 44 is increased. As a mode of increasing / decreasing the duty Dbi and the duty Dbe, a predetermined correction value may be added or subtracted, or the predetermined correction value may be multiplied or subtracted. The duty Dri obtained by correcting the duty Dbi and the duty Dre obtained by correcting the duty Dbe are set as the corrected pulse signal Dr.

  After correcting the pulse signal Db and generating the pulse signal Dr in this way, the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven by the pulse signal Dr (step 190). That is, the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven by the pulse signal Dr (duty Dri and duty Dre), respectively. Accordingly, since the possibility that the supply solenoid valve 43 and the exhaust solenoid valve 44 operate in the period driven by the pulse signal Dr increases, the pressure deviation ΔP between the air detection pressure Pd and the target pressure Pt can be quickly determined. Can be small.

  As described above, the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven by the pulse signal Db (step 160), or the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven by the pulse signal Dr. After this (step 190), this process is temporarily terminated. In addition, the process of steps 110-140 is equivalent to the process as a 1st pulse production | generation means, and the process of step 150,170,180 is equivalent to the process as a 2nd pulse production | generation means.

  Next, the operation mode of the electropneumatic regulator 40 by the air pressure control will be described with reference to the time chart of FIG. For comparison, the operation modes of the conventional electropneumatic regulator are shown in FIGS. 5A to 5E, and the operation modes of the electropneumatic regulator 40 of the present invention are shown in FIGS. 5F to 5J.

  From time t0 to time t1, both the conventional electropneumatic regulator and the electropneumatic regulator 40 of the present invention use the pulse signal Db generated by the PID calculation based on the pressure deviation ΔP between the detected pressure Pd and the target pressure Pt. The supply solenoid valve 43 and the exhaust solenoid valve 44 are driven. Then, as shown in FIGS. 5E and 5J, the pressure deviation ΔP between the target pressure Pt and the detected pressure Pd is controlled to be a value near “0”.

  At time t1, when an abnormality occurs in the exhaust solenoid valve 44, the plunger operation of the exhaust solenoid valve 44 stops during that period, and the plunger displacement becomes “0” as shown in FIGS. "become. For this reason, air is not discharged through the exhaust electromagnetic valve 44, and the pressure deviation ΔP between the detected pressure Pd and the target pressure Pt increases as shown in FIGS. 5 (e) and 5 (j). In the next cycle, as shown in FIGS. 5A, 5C, 5F, and 5H, the pulse signal Db (by PID calculation is performed so as to reduce the pressure deviation ΔP thus increased. Duty Dbi0 and Duty Dbe0) are generated to drive the supply solenoid valve 43 and the exhaust solenoid valve 44, respectively. However, even if the exhaust solenoid valve 44 is driven by the pulse signal Db having the duty Dbe0 generated in this way, the plunger of the exhaust solenoid valve 44 remains stopped as shown in FIGS. 5 (d) and (i). Does not work.

  In the next cycle, in the conventional electropneumatic regulator, as shown in FIGS. 5A and 5C, the supply solenoid valve 43 and the exhaust solenoid valve 44 are respectively turned on by the pulse signal Db (duty Dbi1 and duty Dbe1). Although driven, the plunger of the exhaust solenoid valve 44 remains stopped and does not operate. For this reason, as shown in FIG. 5E, the pressure deviation ΔP is increased by the amount by which the supply solenoid valve 43 is driven to open. In contrast, in the electropneumatic regulator 40 of the present invention, as shown in FIG. 5 (j), it is detected that the pressure deviation ΔP is equal to or greater than the determination value Rp at time t2. At time t3, since the duration T of the state becomes equal to or longer than the determination period Rt, the pulse signal Db (duty Dbi1 and duty Dbe1) generated by the PID calculation as shown in FIGS. ) Is changed to the pulse signal Dr (duty Dri1 and duty Dre1). Accordingly, the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven by the pulse signal Dr (duty Dri1 and duty Dre1), respectively, and the plunger of the exhaust solenoid valve 44 is driven at time t4 as shown in FIG. 5 (i). Operation resumes. Further, since the air supply solenoid valve 43 is not driven to open, the pressure deviation ΔP is suppressed from increasing as shown in FIG.

  In the next cycle, in the conventional electropneumatic regulator, as shown in FIGS. 5A and 5C, the pulse signal Db (duty Dbi2 and duty) is calculated by the PID calculation so as to reduce the pressure deviation ΔP that is further increased. Dbe2) is generated, and the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven. Then, as shown in FIG. 5D, the operation of the plunger of the exhaust solenoid valve 44 is resumed at time t5. On the other hand, in the electropneumatic regulator 40 of the present invention, as shown in FIGS. 5 (f) and 5 (h), the supply solenoid valve 43 and the exhaust solenoid valve 44 by the pulse signal Dr (duty Dri2 and duty Dre2). Is driven, and the pressure deviation ΔP rapidly decreases as shown in FIG.

  According to the configuration of the present embodiment described in detail above, the following excellent effects can be obtained.

  Since the air supply solenoid valve 43 is connected to an air supply source and driven to open and close by a pulse signal having a predetermined cycle, the flow rate of the air supplied from the air supply source is controlled by the air supply solenoid valve 43. Is done. Since the exhaust solenoid valve 44 is connected to the supply solenoid valve 43 via the connection passage 46 and is opened and closed by a pulse signal having a predetermined period, the air flowing through the supply solenoid valve 43 is exhausted. The flow rate is controlled by the electromagnetic valve 44. Since the air passage 35 is provided to lead out air from the connection passage 46, the air whose pressure is controlled by the flow rate control of the supply solenoid valve 43 and the exhaust solenoid valve 44 is led out to the air passage 35.

  Further, a pressure sensor 72 for detecting the pressure of air in the connection passage 46, and an air supply solenoid valve 43 and an exhaust solenoid valve 44 are provided for setting the air detection pressure Pd by the pressure sensor 72 to the target pressure Pt. Since the pulse signal Db that is driven in the cycle is provided with the pressure controller 41 that generates the PID calculation based on the pressure deviation ΔP between the detected air pressure Pd and the target pressure Pt, the air is supplied by the pulse signal Db thus generated. The solenoid valve 43 for exhaust and the solenoid valve 44 for exhaust are driven to open and close in each cycle, and the detected pressure Pd of the derived air is controlled to become the target pressure Pt.

  Further, on the condition that the pressure deviation ΔP between the air detection pressure Pd and the target pressure Pt is equal to or greater than the determination value Rp, the pressure deviation ΔP in the cycle in which the supply solenoid valve 43 and the exhaust solenoid valve 44 are driven. Since the pressure controller 41 corrects the pulse signal Db generated by the PID calculation to the pulse signal Dr so that the electromagnetic valves 43 and 44 do not operate due to some abnormality, for example, the detected pressure Pd and the target pressure Pt When the pressure deviation ΔP becomes equal to or greater than the determination value Rp, the electromagnetic valves 43 and 44 are driven by the pulse signal Dr that has been changed to reduce the pressure deviation ΔP. As a result, there is a high possibility that the solenoid valves 43 and 44 operate in the period driven by the pulse signal Dr. Therefore, when the pressure deviation ΔP between the air detection pressure Pd and the target pressure Pt increases, the pressure deviation ΔP Can be quickly reduced.

  The determination value Rp of the pressure deviation ΔP is set to a value that can detect that the supply solenoid valve 43 or the exhaust solenoid valve 44 does not operate over two cycles of the pulse signal Db. By detecting an abnormality in the supply solenoid valve 43 or the exhaust solenoid valve 44 in a short period of two cycles of Db, the deviation ΔP between the air detection pressure Pd and the target pressure Pt can be reduced more quickly.

  Since it is a further condition for changing the pulse signal Db generated by the PID calculation that the pressure deviation ΔP is equal to or greater than the determination value Rp, the pressure deviation ΔP is equal to or greater than the determination value Rp. The pulse signal Db can be changed after more reliably determining that there is. Further, since this determination period Rt is set shorter than the cycle of the pulse signal Db, regardless of the timing when the state in which the pressure deviation ΔP is greater than or equal to the determination value Rp starts within one cycle of the pulse signal Db, The determination can be completed within two cycles at the latest including the cycle at which the state starts. As a result, it is possible to change the pulse signal Db for driving the solenoid valves 43 and 44 in an earlier cycle while more reliably determining that the pressure deviation ΔP is equal to or greater than the determination value Rp.

  Since both the duty Dbi of the pulse signal Db for driving the supply solenoid valve 43 and the duty Dbe of the pulse signal Db for driving the exhaust solenoid valve 44 are changed, the supply solenoid valve 43 and the exhaust solenoid Expansion of the pressure deviation ΔP due to normal driving of the valves 44 can be suppressed.

  Since it includes the electropneumatic regulator 40 and the pilot regulator 22 that adjusts the flow rate of the chemical based on the pressure applied by the air supplied from the electropneumatic regulator 40, the pilot is based on the pressure controlled by the electropneumatic regulator 40. The flow rate of the chemical solution is adjusted by the regulator 22. A flow rate sensor 71 that detects the flow rate of the chemical solution, and a flow rate controller 60 that sets the target pressure Pt of air based on the deviation between the detected flow rate and the target flow rate so that the detected flow rate of the chemical solution by the flow rate sensor 71 becomes the target flow rate. Therefore, the electro-pneumatic regulator 40 controls the air pressure so that the target pressure Pt is set in this way, and the detected flow rate of the chemical solution is controlled to be the target flow rate.

  Here, for example, when the deviation between the detected flow rate of the chemical liquid and the target flow rate becomes large due to some abnormality, the target pressure Pt of air derived from the electropneumatic regulator 40 is set based on the increased deviation. The However, when an abnormality occurs in the electropneumatic regulator 40, the air detection pressure Pd derived from the electropneumatic regulator 40 is not appropriately controlled to be the target pressure Pt, and is adjusted by the pilot regulator 22. It becomes difficult to quickly set the detection flow rate of the chemical solution to the target flow rate.

  In this respect, since the electropneumatic regulator 40 that performs the air pressure control described above is provided in this embodiment, when the pressure deviation ΔP between the detected air pressure Pd and the target pressure Pt increases, the pressure deviation ΔP is quickly reduced. can do. As a result, even if an abnormality occurs in the electropneumatic regulator 40, the detected flow rate of the chemical liquid adjusted by the pilot regulator 22 can be quickly set to the target flow rate.

  The present invention is not limited to the above embodiment, and may be implemented as follows, for example.

  In the above-described embodiment, the flow rate sensor 71 that detects the flow rate of the chemical solution is employed as the flow rate detection unit that detects the flow rate of the fluid. However, the pressure sensor that detects the flow rate of the chemical solution indirectly by detecting the pressure of the chemical solution is used. It can also be adopted.

  In the above embodiment, air is used as the gas used when the electropneumatic regulator 40 adjusts the operating pressure. However, other gases such as nitrogen may be used.

  In the above embodiment, the pulse signal Db generated by the PID calculation is further provided that the state where the pressure deviation ΔP is equal to or greater than the determination value Rp continues for the determination period Rt set shorter than the cycle of the pulse signal Db. However, this condition can be omitted. That is, the pulse signal Db generated by the PID calculation may be changed immediately on condition that the pressure deviation ΔP is equal to or greater than the determination value Rp. In this case, since it is not necessary to wait for the determination period to elapse, there is a possibility that the pulse signal Db can be changed in an earlier cycle, and the pressure deviation ΔP can be reduced more quickly.

  In the above embodiment, both the duty Dbi of the pulse signal Db for driving the air supply electromagnetic valve 43 and the duty Dbe of the pulse signal Db for driving the exhaust electromagnetic valve 44 are changed. Of the duty Dbi and the duty Dbe, Only one of them may be changed.

  In the above embodiment, the pulse signal Dr is generated by correcting the pulse signal Db generated by the PID calculation so as to reduce the pressure deviation ΔP. However, the pressure deviation ΔP is smaller than the pulse signal Db generated by the PID calculation. The pulse signal Dr may be generated so as to be small. That is, the pulse signal Dr may be generated separately from the pulse signal Db generated by the PID calculation, and the pulse signal Dr may be generated so that the pressure deviation ΔP is smaller than the pulse signal Db.

  In the above embodiment, the pulse signal Db for driving the supply solenoid valve 43 and the exhaust solenoid valve 44 is generated by the PID calculation based on the pressure deviation ΔP between the detected pressure Pd and the target pressure Pt. Based on the deviation ΔP, the pulse signal Db can be generated by other calculation processing such as PI calculation.

  In the above-described embodiment, the electropneumatic regulator 40 is configured to derive air to the diaphragm type flow rate adjusting device, but may be configured to derive air to the air cylinder type flow rate adjusting device. Moreover, if it is an apparatus using the gas by which the pressure was controlled, the pressure control apparatus of this invention is applicable with respect to apparatuses other than a flow volume adjustment apparatus.

The circuit diagram which shows the whole structure of a chemical | medical solution supply circuit provided with a pressure control apparatus. The circuit diagram which shows the outline of an electropneumatic regulator. The graph which shows the relationship between the energization ratio to a solenoid valve, and the plunger displacement of a solenoid valve. The flowchart which shows the procedure of air pressure control. The time chart which shows the operation | movement aspect of a pressure control apparatus.

Explanation of symbols

  35 ... an air passage as a lead-out passage, 40 ... an electropneumatic regulator as a pressure control means, 43 ... an electromagnetic valve for supply, 44 ... an electromagnetic valve for exhaust, 72 ... a pressure sensor as a pressure detection means.

Claims (4)

An air supply solenoid valve connected to a gas supply source and driven to open and close by a pulse signal having a predetermined period;
An exhaust solenoid valve connected to the supply solenoid valve via a connection passage and driven to open and close by a pulse signal having the predetermined period;
A lead-out passage for leading out the gas from the connection passage;
Pressure detecting means for detecting the pressure of the gas in the connecting passage or the outlet passage;
In order to set the detected pressure of the gas by the pressure detecting means to the target pressure, the pulse signal for driving the supply solenoid valve and the exhaust solenoid valve in each cycle is set between the gas detection pressure and the target pressure. First pulse generating means for generating based on the deviation;
It on condition that the deviation between the detected pressure and the target pressure of the gas is equal to or larger than the reference value, as the air supply solenoid valve and the exhaust solenoid valve is reduced Oite the deviation periodically driven, And a second pulse generating means for changing the pulse signal generated by the first pulse generating means.   2. The determination value is set to a value capable of detecting that the supply solenoid valve or the exhaust solenoid valve does not operate over two cycles of the pulse signal. The pressure control device described in 1.   The second pulse generation means is generated by the first pulse generation means on the condition that the state where the deviation is equal to or greater than the determination value continues for a determination period set shorter than the predetermined period. The pressure control device according to claim 1, wherein the pulse signal is changed. The pressure control device according to any one of claims 1 to 3,
Flow rate adjusting means for adjusting the flow rate of the fluid based on the pressure applied by the gas supplied from the pressure control device;
Flow rate detection means for detecting the flow rate of the fluid;
Setting means for setting the target pressure of the gas based on a deviation between the detected flow rate and the target flow rate so that the detected flow rate of the fluid by the flow rate detection unit becomes a target flow rate. Control device.

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