JP2007146908A - Vacuum pressure adjusting system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To drive an adjusting member for setting a stop position of a piston for driving a valve member by a compact and inexpensive electric motor. <P>SOLUTION: This vacuum pressure adjusting system is provided with a valve main body part 1 for opening and closing a valve seat 14 between main ports 11 and 12 by the valve member 15, a fluid pressure driving part 2 having the piston 16 for opening, closing, and operating the valve member, a valve opening adjusting part 3 for setting opening of the valve member by the adjusting member 41 driven by the electric motor 45, a solenoid valve device 4 for supplying and draining pilot fluid into/from the fluid pressure driving part 2 and draining pilot fluid at non-current carrying time, and a controller for controlling opening of the valve member. Output of a load detection means for detecting rotation load of the electric motor and a control order from the outside are inputted into the controller, and the controller controls, based on such inputs, a position of the adjusting member so that it becomes a specified position by control of driving current to the electric motor and controls pilot fluid pressure by driving the solenoid valve device based on them. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vacuum pressure control system used for depressurization of a vacuum chamber for chemical reaction in a physics and chemistry machine or the like.

For example, in a semiconductor manufacturing apparatus, physicochemical processing is performed in a vacuum chamber. At this time, a vacuum pump is used to depressurize the vacuum chamber, and an external flow path connecting the vacuum pump and the vacuum chamber is opened and closed. A vacuum pressure control valve is used to form a vacuum pressure control system.
For example, as described in Patent Document 1, the vacuum pressure regulating valve includes two ports connected to a vacuum pump and a vacuum chamber, an internal flow path connecting the ports, and the internal flow path. A valve member formed therein, a valve member for opening and closing the valve seat, and a piston for opening and closing the valve member, and the valve opening degree of the valve member is set by position control of the piston. By compensating for the change in the vacuum pressure in the vacuum chamber, the inside of the chamber is maintained at the required vacuum pressure.

In order to be able to adjust the opening degree of the valve member in such a vacuum pressure regulating valve easily, quickly and accurately, the vacuum pressure regulating valve of Patent Document 1 is provided with an adjusting shaft driven by an electric motor. Thus, the piston is driven to a position where it comes into contact with the adjusted adjustment shaft.
In general, when the opening degree of the vacuum pressure adjusting valve is adjusted by the electric motor alone, it can be accurately performed.

However, when the electric motor is used alone, the driving force of the valve member is lost when the power supply is shut off, so that there is a problem that the valve opening is held at that position in the event of a power failure.
Further, in the vacuum pressure regulating valve as described in Patent Document 1, the piston connected to the valve member is configured to be driven to a position where the piston contacts the adjustment shaft that is driven and adjusted by the electric motor. Therefore, it is necessary to drive the electric motor in a state where the piston is pressed against the adjustment shaft with a strong pressing force. To enable this driving, the electric motor is made to have a relatively large output. The conversion mechanism that converts the rotational motion of the motor into a reciprocating linear motion needs to withstand the pressure contact force. Therefore, a small and inexpensive electric motor or conversion mechanism cannot be used. It was necessary to consider measures.

JP 2005-76829 A

The technical problem of the present invention is that a vacuum pressure adjustment system that enables a small and inexpensive electric motor to drive an adjustment member for setting a stop position of a pressure receiving member that drives a valve member with pilot fluid pressure. Is to provide.
Another technical problem of the present invention is that the pressing force of the pressure receiving member and the adjusting member using the electric motor can be kept substantially constant, and thereby the opening degree of the valve member can be controlled quickly and accurately. An object of the present invention is to provide a vacuum control system with good controllability.

  Another technical problem of the present invention is to use a detection means for detecting a drive current supplied to the electric motor as a load detection means attached to the electric motor for driving the adjusting member. Means for detecting a pressing force between the pressure receiving member and the adjusting member by causing the encoder attached to the valve to have a function as a position sensor for detecting the position of the pressure receiving member for determining the opening degree of the valve member It is to provide a vacuum pressure control system that is structurally simplified as compared with the case where a general position sensor (linear sensor) is provided for detecting the position of the pressure receiving member.

  In order to solve the above problems, the present invention is provided with first and second main ports for connection to a vacuum chamber and a vacuum pump, a flow path connecting both the main ports, and a valve seat in the flow path. A valve housing provided in the valve housing for opening and closing the valve seat, a valve shaft extending from the valve member in the axial direction of the valve housing and having a tip reaching the fluid pressure drive unit, and the valve A valve main body having a return spring that biases the member toward the closing direction of the valve seat, a pressure receiving member attached to the tip of the valve shaft, and a fluid pressure in a direction in which the valve member opens to the pressure receiving member. The fluid pressure drive unit having a pressure receiving chamber to be operated, and a pilot port for supplying and discharging pilot fluid to and from the pressure receiving chamber, an adjustment member that contacts the back of the pressure receiving member, and the adjustment unit A vacuum pressure adjusting valve having a valve opening degree adjusting unit having an electric motor that continuously drives back and forth to an arbitrary position via a rotation-linear motion conversion mechanism. And at least an output of a load detection means for detecting the rotational load of the electric motor, an output of an encoder for detecting the rotation amount of the electric motor, and an external control command, In a vacuum pressure regulation system configured by adding a controller for controlling the driving of the electric motor and the electromagnetic valve device, the controller has the following functions: It is.

  That is, the controller supplies a driving current necessary for the electric motor based on the control command, and controls the position of the adjusting member given by the output of the encoder to be a specified position; and It is detected whether the rotational load of the electric motor according to the pressing force between the adjusting member and the pressure receiving member given by the output of the load detecting means is between a set upper limit value and a lower limit value. When deviating between the upper and lower limit values, a control signal is output to the solenoid valve device so that pilot fluid pressure for pressing the pressure receiving member and the adjusting member with the force between the upper and lower limit values is supplied to the pressure receiving chamber. It is configured to have a function of operating the electric motor in a state in which the pilot fluid pressure control is performed and the pressure receiving member and the adjustment member are pressed with the force between the upper and lower limit values.

In a preferred embodiment of the vacuum pressure regulating system according to the present invention, the pilot fluid pressure includes an action force of the return spring, an action force based on the pressure in the vacuum chamber acting on the valve member, and the adjustment member and the pressure receiving member. It is set so as to generate a pressing force corresponding to the sum of the bias that is always applied in between.
Further, the fluid pressure driving part can be constituted by a cylinder part, and the pressure receiving member can be constituted by a piston.

  In another preferred embodiment of the vacuum pressure regulation system of the present invention, a detection means for detecting a drive current supplied to the electric motor is used as the load detection means for the electric motor, and the position control of the electric motor is performed in the controller. The driving current of the electric motor detected by the detection means during driving for the upper limit value and the lower limit value of the current setting value corresponding to the upper limit value and the lower limit value of the rotational load due to the pressing force of the adjustment member and the pressure receiving member, If it deviates between the upper and lower limit values, a control signal for causing the drive current of the electric motor to be between the upper and lower limit values of the current set value is detected. For detecting the position of a pressure receiving member that has a function of outputting to a valve device, or an encoder that detects the amount of rotation of the electric motor, and gives the opening of the valve member to the encoder To retain the function as a location sensor.

  In another preferred embodiment of the vacuum pressure control system of the present invention, the solenoid valve device is composed of a plurality of two-port solenoid valves for supply and exhaust, and the input side of the solenoid valve for supply is pneumatic. And the output side of the exhaust solenoid valve is connected to the atmosphere, and the output side of the supply solenoid valve and the input side of the exhaust solenoid valve are connected to the pilot port, or the solenoid valve The device comprises a three-position three-port solenoid valve, the input side of the solenoid valve is connected to a pneumatic source, the output side of the solenoid valve is connected to the pilot port, and the exhaust side of the solenoid valve is opened to the atmosphere.

Furthermore, in another preferred embodiment of the vacuum pressure regulation system of the present invention, the controller is an electric motor and a controller so that the vacuum pressure detected by a pressure sensor provided in the vacuum chamber becomes a set pressure of the vacuum chamber. Those having the function of controlling the drive of the electromagnetic valve device are used.
In this case, the controller previously holds a set speed and a set acceleration for evacuation, and immediately after the start of the control operation, the speed of change in the vacuum pressure in each control cycle is slowly increased by the set acceleration. Through an acceleration control region where the vacuuming operation is started gently, it is possible to provide a control function for performing control so that the set speed is maintained after the change speed of the vacuum pressure reaches the set speed.

In the vacuum pressure regulation system of the present invention having the above-described configuration, a setting input for the vacuum pressure of the vacuum chamber is given to the controller, and based on this, a drive current for driving the adjustment member from the controller to a predetermined position is generated. When sent to the electric motor, the motor is driven and a signal corresponding to the position of the adjusting member is fed back to the controller from the encoder attached thereto, and the servo mechanism operates so that the motor always stops at the designated position. .
In the controller, the vacuum pressure detected by the pressure sensor provided in the vacuum chamber is compared with a preset pressure value of the vacuum chamber, and the position of the adjusting member is adjusted so that the vacuum chamber becomes the set pressure. It can also be controlled.

  On the other hand, the controller controls the position of the adjusting member in order to operate the pressure receiving member such as a piston in the fluid pressure driving unit and the adjusting member that positions the pressure receiving member with a substantially constant force. Depending on the position of the pressure receiving member determined by the formula, [the acting force of the return spring + the acting force based on the pressure in the vacuum chamber acting on the valve member etc. + the force of the bias that is always applied between the adjusting member and the pressure receiving member A control signal is output from the controller to the solenoid valve device so as to supply the pilot fluid pressure that generates a force against the pressure to the pressure receiving chamber.

As a result, the pressure receiving member is driven to a position where it is pressed against the adjusting member with a substantially constant force by the pilot fluid pressure, and is always pressed against the adjusting member with the force corresponding to the bias. This is because the driving force that the electric motor counters against the acting force by canceling the acting force based on the acting force of the return spring and the pressure in the vacuum chamber acting on the valve member with the pilot air pressure acting on the pressure receiving member. It is possible to use a small motor that can output a slight force as an electric motor.
Further, the controller controls the pressure receiving member and the adjustment member so that the pressure receiving member is operated in a state in which the pressure receiving member and the adjustment member are always pressed with a force of a substantially constant bias, so that the rotation amount of the electric motor is attached to the electric motor. The encoder that detects the pressure can function as a position sensor that detects the position of the pressure receiving member that determines the opening of the valve.

  Further, in the above vacuum pressure control system, the pressing force of the pressure receiving member against the adjusting member varies depending on the pressure of the pilot fluid supplied to the pressure receiving chamber of the fluid pressure driving unit, but when the electric motor is driven, the pressing force Since the rotational load detected by the load detection means (drive current detection means) of the electric motor increases or decreases according to the force, the controller sets the drive current applied to the electric motor between the upper limit value and the lower limit value. When it is detected whether it deviates from the range between the upper and lower limit values, a signal for operating the solenoid valve device is output from the controller, and in the solenoid valve device, [acting force of the return spring + The pilot fluid pressure that generates a force that opposes the (acting force based on the pressure in the vacuum chamber acting on the valve member + the force corresponding to the bias that always acts between the adjusting member and the pressure receiving member) A small electric motor can be used because the pressure receiving member and the adjustment member are always pressed with a substantially constant force supplied to the pressure chamber, and the drive from the electric motor such as a rotation-linear motion conversion mechanism to the adjustment member is also possible. Even if the configuration of the force transmission portion is reduced in size, the adjustment member can be made to perform an intended operation.

According to the vacuum pressure regulation system of the present invention described in detail above, the adjustment member for setting the stop position of the pressure receiving member that drives the valve member with the pilot fluid pressure is driven by a small and inexpensive electric motor. In addition, the pressing force of the pressure receiving member and the adjusting member using the electric motor can be kept substantially constant, and thereby the opening degree of the valve member can be controlled quickly and accurately.
Further, as a load detection means attached to the electric motor for driving the adjusting member, a detection means for detecting a drive current supplied to the electric motor is used, and the valve member is opened to an encoder attached to the electric motor. Since it has a function as a position sensor for detecting the position of the pressure receiving member that determines the degree, a means for detecting the pressing force is provided between the pressure receiving member and the adjusting member, or the position of the pressure receiving member is detected. Therefore, it is possible to obtain a vacuum pressure control system that is structurally simplified as compared with the case where a general position sensor is provided.

FIG. 1 shows a typical embodiment of a vacuum pressure regulating valve used in a vacuum pressure regulating system according to the present invention, and FIG. 2 shows an overall configuration example of a vacuum pressure regulating system including the vacuum pressure regulating valve. .
The vacuum pressure adjusting valve includes a valve main body 1 including a valve member 15 that opens and closes a flow path 13 between first and second main ports 11 and 12, and a piston 16 that opens and closes the valve member 15. 2 and a valve opening degree adjusting unit 3 for setting the opening degree of the valve member 15. The vacuum pressure adjusting valve is connected to the fluid pressure driving unit 2 as shown in FIG. An electromagnetic valve device 4 that supplies and discharges fluid is connected to a controller that controls the opening degree of the valve member 15 based on a control command, a load of an electric motor 45 described later, information on the position of the piston 16, and the like.

  More specifically, the hollow valve housing 10 in the valve main body 1 is connected to the first main port 11 for connection to the vacuum chamber 5 and the vacuum pump 6 as shown in FIG. And a flow path 13 connecting the main ports 11 and 12 is formed inside the valve housing 10 as shown in FIG. A valve seat 14 is formed so that the main port 11 surrounds the opening 11 a that opens to the flow path 13.

Inside the valve housing 10, the poppet type valve member 15 that opens and closes the valve seat 14 is provided coaxially with the valve seat 14. The valve member 15 has a disk shape, and a valve seal member 17 made of an annular rubber elastic material that contacts and separates from the valve seat 14 is attached to a portion near the outer periphery thereof.
A valve shaft 20 is attached to the center of the back surface of the valve member 15. The valve shaft 20 extends along the central axis of the valve housing 10 and is connected to the valve main body 1 so as to be fluid. It penetrates through a partition wall 31 of a cylinder housing 30 that partitions the pressure drive unit 2, and its tip extends into the fluid pressure drive unit 2 and is connected to the piston 16.

  Further, a spring seat 22 is provided on the back surface of the valve member 15, and the valve member 15 is directed in the closing direction of the valve seat 14 between the spring seat 22 and a seat plate 32 that contacts the partition wall 31. A coiled return spring 23 is provided for biasing. The valve member 15 is provided with a telescopic bellows 24 formed of a corrosion-resistant material so as to surround the valve shaft 20 and the return spring 23 on the back surface. While isolating, the fluid pressure drive unit 2 side of the flow path 13 is sealed.

  The fluid pressure drive unit 2 includes the cylinder housing 30 that is coaxially coupled to the valve housing 10. The cylinder housing 30 integrally includes the partition wall 31 and has a cylinder hole 33 therein. The piston 16 is slidably accommodated in the cylinder hole 33 via a seal member 34. As described above, the valve shaft 20 slidably penetrates the partition wall 31 and extends into the cylinder hole 33, and the piston 16 is connected to the tip thereof. A pressure receiving chamber 37 is formed between the piston 16 and the partition wall 31 on one surface side of the piston 16, and the pressure receiving chamber 37 is connected to a pilot port 38 opened on the side surface of the cylinder housing 30. The chamber 39 on the other surface side of the piston 16 is open to the outside.

  In the above embodiment, the valve shaft 20 in the fluid pressure drive unit 2 is driven by the piston 16 attached to the tip of the fluid pressure drive unit 2, but the fluid pressure drive unit 2 places the piston 16 in the cylinder hole 33. The pressure receiving chamber 37 is not limited to the slidably inserted configuration, and a pressure receiving member such as a bellowram or a bellows is provided, and a pressure receiving chamber 37 is formed by which the pressure of the valve member 15 is applied by the pressure receiving member. A pilot port 38 for supplying and discharging pilot fluid can be opened in the pressure receiving chamber 37.

  The valve opening degree adjusting unit 3 is incorporated in a cover block 40 coupled to the end of the cylinder housing 30, and has a cylindrical adjustment member 41 whose tip abuts behind the piston 16, and an electric motor. The rotation-linear motion conversion mechanism 47 is provided between the output shaft 46 of the rotation 45 and the rotation shaft 43 that is rotationally driven via gears 42a and 42b meshing with each other. The rotation-linear motion conversion mechanism 47 converts the rotation of the rotary shaft 43 into a linear motion in the axial direction, and drives the adjustment member 41 forward and backward in a stepless manner to an arbitrary position.

The electric motor 45 is a motor that can rotate forward and reverse, and includes load detection means (not shown) that detects the rotational load of the output shaft 46 and outputs the signal to the controller. The load detection means detects the drive current itself of the electric motor 45, or detects whether the drive current exceeds an upper limit or lower limit of a preset setting range, and sends the data to the controller. Can be configured as input.
The electric motor 45 is provided with an encoder (not shown) for detecting the amount of rotation. This encoder has a function as a position sensor for detecting the position of the piston 16 that opens and closes the valve member 15. Therefore, the position of the adjustment member 41 is given to the controller by the output.

The rotation-linear motion conversion mechanism 47 that converts the forward / reverse rotational motion of the electric motor 45 into a reciprocating linear motion is a moving element (on the adjustment member 41) that rotates the ball screw shaft portion 43a in the rotational shaft 43. It is composed of a ball screw that is converted into a linear motion of a ball screw nut) 51.
Note that the adjustment member 41 and the moving element 51 have a rotation restriction for slidingly engaging with a guide shaft 52 installed in the cover block 40 in parallel with the screw shaft portion 43a so as not to rotate. Portions 41a and 51a are provided.
Further, the adjustment member 41 is not limited to the one driven by the rotation-linear motion conversion mechanism 47 formed of the above-described ball screw, and the drive of the electric motor 45 is converted into the linear motion, and the piston 16 or the like Any member may be used as long as it is pressed behind the pressure receiving member so as to follow the pressure receiving member.

  As shown in FIG. 2, the electromagnetic valve device 4 includes two 2-port electromagnetic valves 62a and 62b for supply and exhaust, and the input side of the supply solenoid valve 62a operates the piston 16. It is connected to an air pressure source 65 via a pressure regulating valve 63 that can set the maximum pressure to be set, the output side of the exhaust solenoid valve 62b is opened to the atmosphere, the output side of the solenoid valve 62a for supply and the exhaust The input side of the electromagnetic valve 62 b for use is connected to the pilot port 38 through a pipe line 66. Actually, the output pressure of the pressure regulating valve 63 includes the acting force of the return spring 23, the acting force based on the pressure in the vacuum chamber 5 acting on the valve member 15, and the adjusting member 41 and the pressure receiving member (piston 16). It is necessary to determine mainly the maximum value of the total force of the bias that is always applied during the period, and also taking into consideration the influence of friction and the like in the fluid pressure drive unit 2.

  The two-port solenoid valves 62a and 62b are controlled to be opened and closed by a control signal from the controller, but the pilot fluid supplied from the air pressure source 65 to the pressure receiving chamber 37 is cut off by the supply solenoid valve 62a. Further, the pilot fluid discharged from the pressure receiving chamber 37 is cut off by the electromagnetic valve 62b for exhaust, and the pressure of the pressure receiving chamber 37 is controlled. The electromagnetic valves 62a and 62b are arranged in one three position. It can be configured as a three-port electromagnetic direction switching valve. In this case, a single three-position three-port solenoid valve is used in place of the two-port solenoid valves 62a and 62b, and the solenoid valve is connected to the pilot port 38 so that compressed air from the air pressure source 65 can be supplied and discharged. become. In addition to the on-off valves, analog valves can be used as the supply and exhaust solenoid valves.

The controller generally includes control commands such as an output of a load detection means and an encoder attached to the electric motor 45, an output of a vacuum pressure sensor 60 for detecting the pressure in the vacuum chamber 5, and a set pressure from the outside. Signals are input, and the drive of the electric motor 45 and the electromagnetic valve device 4 is controlled based on these signals.
More specifically, the controller supplies a necessary drive current to the electric motor 45 based on the control command, and controls the position of the adjustment member 41 given by the output of the encoder to be a designated position. When driving for position control and position control of the electric motor 45, the rotation of the electric motor 45 according to the pressing force between the adjustment member 41 and the pressure receiving member (piston 16) given by the output of the load detection means. When it is detected whether the load (drive current) is between the set upper limit value and the lower limit value, and it deviates from the range between the upper and lower limit values, the adjustment member 41 and the piston 16 are moved. Pilot fluid pressure control is performed to output a control signal to the solenoid valve device 4 so that a pilot fluid pressure for pressing with the force between the upper and lower limit values is supplied to the pressure receiving chamber 37. Te is an adjustment member 41 and the piston 16 has a function to operate the electric motor in a state of pressing by the bias component of the force between the upper and lower limit values.

  Therefore, the pilot fluid pressure supplied to the pressure receiving chamber 37 is based on the acting force of the return spring 23 corresponding to the position of the piston 16 determined by the position of the adjusting member 41 and the pressure in the vacuum chamber 5 acting on the valve member 15. This corresponds to the sum of the force, the bias force that is always applied between the adjusting member 41 and the pressure receiving member (piston 16), and the friction in the fluid pressure driving unit 2.

More specifically, the control by the controller will be described. First, a control command including a setting input for the vacuum pressure of the vacuum chamber is given to the controller, and based on the control command, the adjustment member 41 is moved from the controller to a predetermined position. When a driving current for driving is sent to the electric motor 45, the motor is driven, and a signal corresponding to the position of the adjusting member 41 is fed back to the controller from an encoder attached thereto, and the motor is always in a designated position. Servo mechanism operates to stop. Even if the position of the adjustment member 41 is shifted due to disturbance or the like, the correction operation is immediately performed, and the position control of the adjustment member 41 is performed.
In the controller, the vacuum pressure detected by the pressure sensor 60 provided in the vacuum chamber 5 is compared with a preset pressure setting value of the vacuum chamber 5 so that the vacuum chamber 5 becomes the set pressure. The position of the adjustment member 41 is controlled by driving the electric motor 45.

  On the other hand, the piston 16 is operated in a state where it is always pressed against the adjusting member 41 with a substantially constant force, and therefore, according to the position of the piston 16 determined by the position of the adjusting member 41, [acting force of the return spring 23+ The pressure receiving chamber 37 generates a pilot fluid pressure that generates a force that opposes the acting force based on the pressure of the vacuum chamber 5 acting on the valve member and the like + the force of the bias that always acts between the adjusting member 41 and the piston 16. A control signal is output from the controller to the supply or exhaust solenoid valves 62a and 62b.

  As a result, the piston 16 is driven to a position where it is pressed against the adjustment member 41 with a substantially constant force by the pilot fluid pressure, and is always pressed against the adjustment member 41 with the force of the bias. This cancels out the acting force based on the acting force of the return spring 23 and the pressure of the vacuum chamber 5 acting on the valve member 15 with the acting force due to the pilot air pressure acting on the piston 16, so that the electric motor 45 has their force. It is not necessary to have a driving force that opposes the acting force, and it is possible to use a small motor that can output a slight force as the electric motor 45. As a result, the vacuum pressure regulating valve can be reduced in size, which is advantageous not only in installation but also in power. In addition, since the controller controls the piston 16 so that the piston 16 is operated with the piston 16 and the adjustment member 41 being pressed with a substantially constant force, the controller is attached to the electric motor 45 to detect the rotation amount of the electric motor. The encoder that performs this function can be made to function as a position sensor that detects the position of the piston that determines the opening of the valve.

  Further, as described above, the servo mechanism operates so as to move the adjustment member 41 to a predetermined position by the electric motor 45. Therefore, if the position of the adjustment member is shifted due to a disturbance or the like, the motor is immediately used for the correction operation. While the motor is driven, the pressing force of the piston 16 against the adjusting member 41 varies depending on the pressure of the pilot fluid supplied to the pressure receiving chamber 37 of the fluid pressure driving unit 2. Is driven, the drive current of the electric motor 45 increases or decreases according to the pressing force, and the magnitude of the drive current to the electric motor 45 can be regarded as the magnitude of the disturbance.

  Therefore, in the controller, it is detected whether or not the drive current applied to the electric motor 45 is within the certain range, and if it is less than the set lower limit value, is the piston 16 pressed against the adjustment member 41? Since it is unclear whether a signal for operating the supply solenoid valve 62 a is output, the pilot fluid pressure is supplied to the pressure receiving chamber 37 to drive the piston 16 against the adjusting member 41. Further, when it is determined that an excessive pressing force is applied because the drive current applied to the electric motor 45 exceeds the set value upper limit value, a signal for operating the electromagnetic valve 62b for exhaust is output from the controller. The pilot fluid pressure in the pressure receiving chamber 37 is reduced to reduce the pressing force.

  As a result, the pressure receiving chamber 37 always has [the acting force of the return spring + the acting force based on the pressure in the vacuum chamber acting on the valve member or the like + the bias amount that is always applied between the adjusting member and the pressure receiving member. The pilot fluid pressure that opposes the force] is supplied, and the piston 16 and the adjustment member 41 are always pressed with a force of a substantially constant bias.

  Further, as described above, the controller controls the piston 16 and the adjustment member 41 in the fluid pressure drive unit 2 to always operate with the substantially constant force, so that the electric motor 45 is operated. The attached encoder can function as a position sensor for the piston 16 that determines the opening degree of the valve member 15, and even if a general position sensor (linear sensor) is not incorporated in the fluid pressure drive unit 2, The position of the piston 16, that is, the position of the valve member 15 can be recognized by the controller, and the structure can be greatly simplified as compared with the case where a general position sensor is used.

  Furthermore, when adjusting the vacuum pressure of the vacuum chamber 5 in the vacuum pressure adjusting system, the controller uses a pressure signal from the vacuum pressure sensor 60 in the vacuum chamber 5 and a pressure set value given to the controller. And the control signal of the position of the adjusting member 41 for appropriately setting the opening degree of the valve member 15 is output to the electric motor 45, whereby the electric motor 45 rotates forward or reversely, and the adjusting member 41 Is moved to the designated position, and the drive of the electromagnetic valve device is controlled as described above, and the vacuum chamber 5 is maintained at the desired vacuum pressure.

In the vacuum pressure adjusting system, when the controller compares the pressure signal from the vacuum pressure sensor 60 with the pressure setting value and performs feedback control of the vacuum pressure in the vacuum chamber 5, the opening degree of the valve member 15 is as described above. In this case, it is desirable to provide the controller with the following control function.
That is, the controller previously holds a set speed (vacuum pressure change speed) and a set acceleration (change speed of the vacuum pressure change speed) for evacuation in advance, and immediately after the start of the control operation at time t1, as shown in FIG. , The speed of change of the vacuum pressure in each control cycle T slowly increases due to the set acceleration, and as a result, the vacuuming operation of the vacuum chamber 5 does not suddenly change and starts gently. After the time t4 when the change speed of the vacuum pressure reaches or exceeds the set speed due to the accumulation of the speed change due to the set acceleration after passing through the acceleration control region including a certain control cycle determined by various conditions, Controlled to maintain set speed.

Specifically, the control of the change in the vacuum pressure is performed by internally calculating the position of the adjustment member 41 corresponding to the target pressure from the pressure change obtained by the calculation by the controller, and by controlling the position of the adjustment member 41 by the electric motor 45. Is called. The position control by the electric motor 45 can be performed with relatively good control because there is no nonlinear element due to the compressibility of air as compared with the pneumatic control.
Then, by controlling the position of the minute displacement of the adjustment member 41 with the electric motor 45 immediately after the start of the control operation in this way, it is possible to perform control to increase the degree of vacuum stably and smoothly without causing a sudden change in pressure.

  As a control means for feedback control of the vacuum pressure in the vacuum chamber in the range from atmospheric pressure to high vacuum pressure, the controller uses an internal command for the vacuum pressure value calculated based on the target vacuum pressure change rate set in the controller. And sequentially changing the internal command as a target value of the feedback control, thereby executing the feedback control as follow-up control and changing the vacuum pressure in the vacuum chamber at a target vacuum pressure change rate. It has been proposed (see Japanese Patent No. 3606754).

However, in this method, if an error occurs with respect to the target pressure in a certain control cycle, the error is integrated and increased from the target speed by adding the next change pressure to the pressure in which the error has occurred. In addition, if the change pressure is added to the calculated target pressure to obtain the target pressure, there is a possibility that inconvenience such as hunting around the target speed may occur.
On the other hand, by performing the control having the acceleration control region based on the set acceleration described above, not only such inconvenience is caused, but also the control for evacuating smoothly immediately after the start of the operation can be performed.

  Moreover, in the said vacuum pressure regulation system, the effect | action based on the repulsive force which arises in the compression state by the return spring of the valve seal member 17 which consists of a rubber elastic material attached to the valve member 15, and the pressure of the vacuum chamber which acts on the valve member 17 Since the balance position between the force and the valve seal member 17 is a complete seal position (zero point), the gap between the valve seat 14 and the valve seal member 17 can be adjusted from as close to zero as possible. The range of pressure control that can be implemented is expanded.

  Although the embodiment of the vacuum pressure control system of the present invention has been described in detail above, the present invention is not limited to the above-described embodiments and the like, and departs from the spirit of the invention described in the claims of the present invention. Various changes can be made in the design without departing from the scope.

The structure of the valve for vacuum pressure regulation in the vacuum pressure regulation system which concerns on this invention is shown, The left half is sectional drawing which shows the valve closing state of a valve member, and the right half shows the valve opening state. It is a block diagram of the vacuum pressure regulation system which concerns on this invention. It is typical explanatory drawing for demonstrating control of the change of the vacuum pressure in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Valve main part 2 Fluid pressure drive part 3 Valve opening degree adjustment part 4 Electromagnetic valve device 5 Vacuum chamber 6 Vacuum pump 10 Valve housing 11 1st main port 12 2nd main port 13 Flow path 14 Valve seat 15 Valve member 16 Piston 20 Valve shaft 23 Return spring 37 Pressure receiving chamber 38 Pilot port 41 Adjustment member 45 Electric motor 47 Rotation-linear motion conversion mechanism 60 Vacuum pressure sensor 62a Supply two-port solenoid valve 62b Exhaust two-port solenoid valve

Claims (9)

First and second main ports for connecting to a vacuum chamber and a vacuum pump, a flow path connecting both the main ports, a valve housing provided with a valve seat in the flow path, and provided in the valve housing A valve member that opens and closes the valve seat, a valve shaft extending from the valve member in the axial direction of the valve housing and having a tip reaching the fluid pressure drive unit, and the valve member facing the valve seat closing direction. A valve main body having a return spring to be energized,
A pressure receiving member attached to the tip of the valve shaft; a pressure receiving chamber for applying a fluid pressure in a direction in which the valve member opens to the pressure receiving member; and a pilot port for supplying and discharging pilot fluid to and from the pressure receiving chamber. The fluid pressure drive unit, and
A valve opening degree adjuster having an adjustment member that contacts the back of the pressure receiving member, and an electric motor that drives the adjustment member steplessly back and forth to an arbitrary position via a rotation-linear motion conversion mechanism;
The vacuum pressure regulating valve is configured by providing
In the above vacuum regulating valve,
An electromagnetic valve device for supplying and discharging pilot fluid to and from the pressure receiving chamber; and
At least the output of the load detection means for detecting the rotational load of the electric motor, the output of the encoder for detecting the rotation amount of the electric motor, and an external control command are input, and based on these, the electric motor and the electromagnetic A controller for controlling the drive of the valve device,
In a vacuum pressure regulation system configured by attaching
Position control in which the controller supplies necessary drive current to the electric motor based on the control command and controls the position of the adjustment member given by the output of the encoder to be a specified position, and the load detection Detecting whether or not the rotational load of the electric motor according to the pressing force between the adjusting member and the pressure receiving member given by the output of the means is between a set upper limit value and a lower limit value. A pilot that outputs a control signal to the solenoid valve device so that a pilot fluid pressure for pressing the pressure receiving member and the adjusting member with the force between the upper and lower limit values is supplied to the pressure receiving chamber when deviating between the lower limit values. Fluid pressure control is performed, thereby having a function of operating the electric motor in a state where the pressure receiving member and the adjustment member are pressed with a force between the upper and lower limit values.
Vacuum pressure regulation system characterized by that. The pilot fluid pressure corresponds to the sum of the action force of the return spring, the action force based on the pressure in the vacuum chamber acting on the valve member, and the bias component that always acts between the adjustment member and the pressure receiving member. To generate a pressing force
The vacuum pressure regulating system according to claim 1. As a load detection means of the electric motor, a detection means for detecting a drive current supplied to the electric motor is used.
In the controller, the driving current of the electric motor detected by the detecting means during driving for position control of the electric motor is a current corresponding to the upper limit value and the lower limit value of the rotational load due to the pressing force between the adjustment member and the pressure receiving member. When it is detected whether the set value is between the upper limit value and the lower limit value, and it deviates between the upper and lower limit values, the drive current of the electric motor is between the upper and lower limit values of the current set value. A function to output a control signal to the solenoid valve device
The vacuum pressure regulation system according to claim 1 or 2, characterized by the above-mentioned. The electric motor is provided with an encoder for detecting the rotation amount, and the encoder has a function as a position sensor for detecting the position of the pressure receiving member that gives the opening degree of the valve member.
The vacuum pressure regulation system according to any one of claims 1 to 3. The fluid pressure driving part is constituted by a cylinder part, and the pressure receiving member is constituted by a piston;
The vacuum pressure regulation system according to any one of claims 1 to 4. The solenoid valve device includes a plurality of two-port solenoid valves for supply and exhaust, the input side of the supply solenoid valve is connected to a pneumatic pressure source, and the output side of the exhaust solenoid valve is connected to the atmosphere. Open, the output side of the solenoid valve for air supply and the input side of the solenoid valve for exhaust are connected to the pilot port,
The vacuum pressure regulation system according to any one of claims 1 to 5. The solenoid valve device is composed of a three-position, three-port solenoid valve, the input side of the solenoid valve is connected to a pneumatic source, the output side of the solenoid valve is connected to the pilot port, and the exhaust side of the solenoid valve is open to the atmosphere Being
The vacuum pressure regulation system according to any one of claims 1 to 5. The controller has a function of controlling the driving of the electric motor and the electromagnetic valve device so that the vacuum pressure detected by the pressure sensor provided in the vacuum chamber becomes the set pressure of the vacuum chamber.
The vacuum pressure regulation system according to any one of claims 1 to 7. When the controller performs feedback control of the vacuum pressure in the vacuum chamber by comparing the pressure signal from the pressure sensor and the pressure set value,
The controller holds the set vacuum speed and set acceleration in advance, and immediately after the start of the control operation, the set acceleration accelerates the rate of change of the vacuum pressure in each control cycle slowly, and the vacuum chamber vacuum operation is performed. Through an acceleration control region that is gently started, a control function is provided to control the vacuum pressure change rate so as to maintain the set speed after reaching the set speed.
The vacuum pressure regulating system according to claim 8.

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