JPH07259801A - Air servocylinder system - Google Patents

Abstract

PURPOSE:To provide an air servocylinder system which can realize excellent position precision, the speed precision of super slow speed drive and followability. CONSTITUTION:In the case of an air servocylinder system having a pneumatic pressure cylinder 1; control valves 6, 7 to control fluid pressure; a control circuit to control signals to the control valves 6, 7; and a position detecting means 2 that detects the drive position of the pneumatic pressure cylinder 1 and conducts feedback to the control circuit, the control valves are solenoid valves that conduct time opening/closing action according to pulse frequency, and these solenoid valves are made up of a solenoid valve 6 for feeding that carries out the feeding of air to a pressure chamber in the pneumatic pressure cylinder 1 and a solenoid valve 7 for discharge that carries out the discharge of the air of the pressure chamber, and the control circuit possesses an amplification means 4 to amplify a difference between the position sensor signal of the position detecting means 2 and an input signal inputted from the outside so as to command a free piston position to the control valves 6, 7; and a pulse conversion means 5 to convert a signal from the amplification means 4 into a pulse signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder unit driven by air pressure. More specifically, it can be driven at an extremely low speed, and can achieve accurate position accuracy including stop at an intermediate position and high response performance. The present invention relates to a position control cylinder unit provided.

[0002]

2. Description of the Related Art Conventionally, fluid pressure cylinder units have been used for conveying articles in a wide range of fields including semiconductor manufacturing equipment. This is because, for example, in the field of semiconductor manufacturing, it is necessary to transfer wafers or wafer cassettes between or within various types of manufacturing equipment.
Here, in many cases, high positional accuracy is required for wafer transportation. This is because, particularly in the process of processing a fine circuit on a wafer, the quality of positioning accuracy has a great influence on the product yield. Further, since the semiconductor manufacturing process is extremely disliked by the generation of particles and the impact on the wafer due to its nature, high positional accuracy is still required even at ultra-low speed driving. In such a case, a method of using a pulse motor or the like other than the pneumatic cylinder as a drive source is conceivable, but the size becomes large and the cost increases considerably. Therefore, there is a demand for a transfer device using a pneumatic cylinder that can be reduced in size and cost.

Here, in FIG. 12, the actual fairness is 5-42.
1 shows a conventional air servo cylinder system disclosed by Japanese Patent No. 242. A load 51 is provided at the tip of a rod 52d engaged with a piston 52c in a double-acting pneumatic cylinder 52 that drives the load 51. The double-acting pneumatic cylinder 52 is partitioned by a piston 52c into a head side pressure chamber 52a and a rod side pressure chamber 52b.
Then, the head side pressure chamber 52a and the rod side pressure chamber 52
b is an electropneumatic proportional valve 5 for adjusting the pressure.
3, 54 are connected, and an air source 55 is connected to each.

On the other hand, a linear movement type potentiometer 56 for detecting the current position of the load 1 as an analog signal is provided on the rod side. A microcomputer 58 is connected to the potentiometer 56 via an A / D converter 57. Further, the microcomputer 58 includes a floppy disk drive 59,
An error indicator 60 for displaying an error between a measured value and a set value and a D / A converter 61 for converting a digital signal into an analog signal are connected. Furthermore, this D / A converter 6
1 through the PID controller 62, the electropneumatic proportional valve 53,
It is connected to the servo amplifier 63 connected to 54.
The electro-pneumatic proportional valves 53, 54 are valves having a function of adjusting the valve opening in proportion to a given voltage value.

The air servo cylinder system having such a structure operates as follows. Electro-pneumatic proportional valve 53,5
By the opening / closing operation of 4, the air pressure supplied from the air source 55 is adjusted. First, a target stop position is set in the microcomputer 58 from the floppy disk drive 59. Then, the current position of the load 51 is detected by the potentiometer 56, and the detection signal is input to the microcomputer 58 by interrupt processing via the A / D converter. Here, the error from the target stop position is calculated,
The control voltage signal is output.

The control voltage signal is converted into an analog voltage signal by the D / A converter 61, and then the PID controller 6
2 is input to the servo amplifier 63. Then, as a current signal from the servo amplifier 63, the electropneumatic proportional valves 53, 5
No. 4 solenoid, the air pressure is supplied to one of the pressure chambers 52a and 52b in the pneumatic cylinder 52, and the piston 52c is driven by exhausting air from the other.
At the end of driving, a plurality of signals that decrease in sequence are applied as intermittent pulses to the electropneumatic proportional valve to gradually reduce the speed so as to accurately stop at the target stop position.

[0007]

However, the conventional air servo cylinder system described above has the following problems. For example, no consideration is given to the ultra-low speed drive required in the wafer transfer device of semiconductor manufacturing equipment, etc., and when the ultra-low-speed drive is performed by the pneumatic cylinders according to these conventional techniques, repeated pop-out phenomenon, so-called step slip phenomenon occurs , The piston shows a stepped movement and a smooth drive cannot be obtained.

Therefore, this phenomenon will be described with reference to the general piston shown in FIG. Consider a state in which the pneumatic cylinder in FIG. 13 is driven leftward at a constant speed (hereinafter, referred to as a steady state). In this steady state, the thrust force F4 in FIG. 13 is slightly larger than the thrust force F3, and the driving force due to the difference between the thrust force F4 and the thrust force F3 balances with the friction force Fg corresponding to the velocity V, so that the constant velocity (V) sliding is achieved. It is in motion.

It is assumed that the sliding speed changes from this state to a speed V1 which is slightly higher than the speed V due to some disturbance. Then, since the frictional force Fh corresponding to the speed V1 is smaller than the frictional force Fg, the driving force due to the difference between the thrust F4 and the thrust F3 overcomes the frictional force Fh, and the piston is further accelerated. At this time, the piston is rapidly accelerated and exerts a nonnegligible effect on the pressure P3 and the pressure P4 in the working chamber in the figure. That is, since the working chamber 3 is compressed, the pressure P3 becomes high, while the working chamber 4 expands, so the pressure P4 becomes low. As a result, the thrust F4 becomes smaller and the thrust F3 becomes larger.

When the magnitude relationship between the thrust F4 and the thrust F3 is reversed, the piston is decelerated and the sliding speed is reduced. Then, as the sliding speed decreases, the frictional force increases, so that the speed is further decelerated, and the vehicle comes to a stop or a state close to stop. Then, when the piston is stopped (or in a state close to the stop), in order to restart the piston, in order to overcome the frictional force F01 larger than the frictional force Fg, the driving force larger than the driving force in the steady state is used. Is required. When such a large driving force is applied, the sliding speed does not settle to the speed V in the steady state, the piston is excessively accelerated, and such speed change is repeated.

Therefore, in the above-mentioned conventional air servo cylinder system, the speed of the plurality of signals which are sequentially decreased at the end of driving is gradually reduced by intermittent pulses to prevent overrun as much as possible. It does not correspond to the speed change, and it becomes difficult to maintain a stable speed, the followability is poor, and as a result, the position accuracy decreases. In particular, a wafer transfer mechanism of a semiconductor manufacturing apparatus (especially, a photo exposure apparatus such as a stepper) requires a positioning accuracy of a submicron level depending on a processing dimension of a circuit pattern, and therefore, a driving speed of about several mm / sec or less. You need speed. Therefore,
Using such a step drive as it is for wafer transfer,
It is not possible to obtain the required positional accuracy. Further, collisions between the wafer and the wafer holder or the wafer cassette occur many times, which may cause generation of particles which are not preferable in semiconductor manufacturing and defects inside the wafer.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an air servo cylinder system which can realize excellent position accuracy, speed accuracy of ultra-low speed drive, and followability. To do.

[0013]

SUMMARY OF THE INVENTION An air servo cylinder system of the present invention comprises an ultra-low speed pneumatic cylinder and a pneumatic cylinder made of a material having a property that the coefficient of friction increases as the sliding speed increases with the packing of the piston unlubricated. A control valve that controls the air pressure supplied to the control valve, a control valve drive circuit that controls the drive of the control valve, and position detection means that detects the drive position of the pneumatic cylinder. In an air servo cylinder system that feeds back to a control circuit to control the driving position of a pneumatic cylinder, the control valve is a solenoid valve that opens and closes in time according to a pulse frequency, and supplies pneumatic pressure to a pressure chamber in the pneumatic cylinder. A supply solenoid valve for supplying air pressure from a source, and a discharge solenoid valve for discharging air pressure in the pressure chamber, The control circuit uses an amplifying means for amplifying a difference between an input signal input from the outside for instructing the control valve of an arbitrary piston position and a position sensor signal of the position detecting means, and the amplified signal. And a pulse conversion means for converting into a pulse signal for driving the control valve. Further, in the air servo cylinder system of the present invention, the control valve controls the supply solenoid valve, the discharge solenoid valve, the supply solenoid valve, and the air pressure supplied or discharged from the discharge solenoid valve. Driven,
And a main valve for controlling the air pressure from an air pressure supply source that is supplied to the pressure chamber in the pneumatic cylinder.

[0014]

In the air servo cylinder system of the present invention having the above construction, the position detecting means detects the piston position in the pneumatic cylinder and outputs it as a position sensor signal. Then, an input signal for commanding an arbitrary piston position to the cylinder and a position sensor signal from the position detecting means are input to the control circuit. In the control circuit, the amplification means amplifies the difference between the input signal and the position sensor signal, the amplified signal is input to the pulse conversion means, and the pulse conversion means performs pulse conversion on the signal input from the amplification means. Input to control valve. Then, in the control valve, the supply solenoid valve and the discharge solenoid valve are opened and closed according to the pulse frequency of the input pulse signal, the air pressure from the air pressure supply source is supplied to the pressure chamber of the pneumatic cylinder, Alternatively, it is discharged.

In the present invention having the above-mentioned structure, as the packing which takes charge of the air-pressure seal between the piston and the cylinder, a material whose friction coefficient increases with an increase in sliding speed is used, and the packing part is lubricated. To use. Therefore, the occurrence of step slips can be dealt with immediately, and high speed accuracy and position accuracy are possible.
Further, in the air servo cylinder system of the present invention, the main valve for controlling the air pressure supplied from the air pressure supply source to the pneumatic cylinder is further provided, and the supply solenoid valve and the discharge solenoid valve are used to supply or discharge the air pressure to the main valve. Driven by. Since air pressure is supplied by the main valve, a highly responsive drive can be performed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment embodying the air servo cylinder system of the present invention will be described below with reference to the drawings.
First, the entire control system of the air servo cylinder system of this embodiment will be described with reference to FIG. In FIG.
The air servo cylinder system has the following configuration. The piston position of the pneumatic cylinder 1 is detected by outputting a voltage signal proportional to the position of the piston of the pneumatic cylinder 1 to an ultra-low speed single acting pneumatic cylinder (hereinafter simply referred to as "pneumatic cylinder") 1. The potentiometer 2 is attached. Then, an air supply solenoid valve 6 for adjusting the air pressure supplied to the pneumatic cylinder 1,
A discharge solenoid valve 7 is connected to the pneumatic cylinder 1 and is configured to supply or discharge pneumatic pressure.

Further, an amplifier 3 for fine adjustment of control characteristics
Is connected to the potentiometer 2, and a proportional gain 4 for amplifying the difference between the input signal from the controller 9 and the position sensor signal from the amplifier 3 is connected to each. A pulse converter 5 that performs pulse conversion on the amplified signal from the proportional gain 4 is connected to each of the air supply solenoid valve 6 and the discharge solenoid valve 7. An air cylinder 8 connected to the supply solenoid valve 6 supplies air pressure to the pneumatic cylinder 1.

Next, pneumatic cylinders and the like constituting the air servo cylinder system will be described with reference to the drawings. FIG. 2 is a perspective view showing the appearance of the pneumatic cylinder. 3 is a side view of the pneumatic cylinder from the left side. The pneumatic cylinder has a potentiometer 2 on top.
The solenoid valves for supply and discharge (hereinafter, simply referred to as "electromagnetic valve") 6, 7 and the control circuit 10 are fixed and integrated. The control circuit 10 incorporates the amplifier 3, the proportional gain 4 and the pulse conversion means 5, which have the function of controlling the opening and closing of the solenoid valves 6 and 7, and the details thereof will be described later. To do. On the other hand, in FIG. 3, a cover 11 is provided on the pneumatic cylinder 1 so as to cover the potentiometer 2 and the like. The cover 11 is provided with an electric signal connector for supplying an input signal from the controller 9 and an adjusting means for adjusting the potentiometer 3. In addition to the cover, an air supply port 13 for taking in the air pressure from the air cylinder and an air discharge port 14 for releasing the air pressure in the air cylinder 2 to the atmosphere are provided.

FIG. 4 shows a sectional view of the pneumatic cylinder 1 and the potentiometer 3 mounted on the pneumatic cylinder 1. Pneumatic cylinder 1 is cylinder housing 2
1, the outer shape is formed. The cylinder housing 21 has a piston drive chamber 25 formed by a sealing ring 24.
And a connection chamber 26 for connecting the piston rod 23 to the potentiometer 3. The piston drive chamber 25 is fitted with the piston 22 slidably fitted in the axial direction, and further the pressure chamber 25a and the working chamber 2 are inserted.
5b and separated. Here, the pressure chamber 25a is a space partitioned by the sealing ring 24 and the piston 22, and has a port 27 to which air pressure adjusted by the solenoid valves 6 and 7 is supplied. On the other hand, the working chamber 25b
Is a space partitioned by the piston 25 and the sealing lid 29, and a return spring 28 for urging the piston 25 toward the pressure chamber 15a is held.

The piston 22 has an annular groove 3 on its outer peripheral surface.
0 is formed, and two ring-shaped packings 31 for sealing the air pressure are superposed and fitted therein. Also,
The piston rod 23 fixed through the center of the piston 22 is provided through the sealing ring 24 and the sealing lid 29. An annular groove 32 is formed on the inner peripheral surface of the sealing ring 24.
Is formed, and two ring-shaped packings 33 for sealing the air pressure are superposed and fitted therein. On the other hand, on the inner peripheral surface of the sealing lid 29, a detent 34 made of an annular rubber is provided so that the piston rod 23 does not rotate when the piston 22 is driven. In addition, the connection chamber 26,
It is closed by a lid 35.

No lubricant is used for sliding between the ring-shaped packing 31 and the inner wall of the cylinder housing 21, and the ring-shaped packing 31 is unlubricated.
It is made of a fluororesin here, which is made of a material having a property that its friction coefficient increases as the sliding speed increases. In the pneumatic cylinder 1, the supply of the air pressure from the air cylinder 8 is adjusted by the solenoid valve 6, and then the pressure chamber 2
Receive at 5a. On the other hand, when the pressure in the pressure chamber 25a is too high, it is discharged to the atmosphere by the solenoid valve 7. Therefore,
When the air pressure supplied to the pressure chamber 25a changes due to the change in the valve opening of the solenoid valves 6 and 7, the piston 22 moves to the pressure chamber 2
It moves to a predetermined position by the balance between the pressure of 5a and the urging force of the return spring 28.

A potentiometer 2 is provided above the pneumatic cylinder 1. The potentiometer 2 is interlocked with the piston rod 23 of the pneumatic cylinder 1 and thus monitors the position of the piston 22 in the pneumatic cylinder 1. A potentiometer 2 has a built-in variable resistor (not shown). A resistance rod 36 extends from the variable resistance to the right in the figure. The resistance rod 36 is slidable in the axial direction, and the secondary voltage is changed by changing the contact position inside the variable resistor. The end of the piston rod 23 inside the connecting chamber 26 and the end of the resistance rod 31 are mechanically connected via a connecting bar 37. Therefore, the piston rod 2
When the piston rod 23 is driven and slides in the axial direction, the resistance rod 36 also slides in the axial direction and changes the secondary voltage. 2 of such variable resistance
The next voltage is input to the proportional gain 4 as an output signal of the potentiometer 2 indicating the current position of the piston 22 of the pneumatic cylinder 2 with an input signal from the controller 9 via the amplifier 3 as shown in FIG.

Next, the operation of the air servo cylinder system having the above construction will be described. First, the controller 9 determines the piston position of the pneumatic cylinder 1 based on the transportation procedure according to the production plan, compares this with the signal from the amplifier 3 as a reference signal, and transmits it to the proportional gain 4. The proportional gain 4 amplifies the difference between the two signals, inputs the amplified signal to the pulse converter 5, converts the amplified signal into a pulse signal, and transmits the pulse signal to the solenoid valves 6 and 7 as an open / close signal. The solenoid valves 6 and 7 adjust the pressure in the pressure chamber by opening and closing for a time corresponding to the pulse frequency. Then, the air pressure in the pneumatic cylinder 2, that is, the pressure chamber 25a is adjusted by supplying or discharging the pulsed air pressure by opening / closing the valve at the pulse frequency.

Therefore, the pneumatic cylinder 1 operates as follows. First, consider a case where the state in which a high pressure is supplied to the pressure chamber 25a is lowered to a low pressure. At this time, in the pneumatic cylinder 1, when the pressure in the pressure chamber 25a decreases, the balance of the force acting on the piston 22 is broken, and the urging force of the return spring 28 exceeds. For this reason piston 2
2 moves to the left again to a position where the pressure in the pressure chamber 25a and the urging force of the return spring 28 balance each other. That is, the piston 22 and the sealing ring are in contact with each other.

Next, consider the case where the pressure is increased from a state where a low pressure is supplied to the pressure chamber 25a to a high pressure. At this time, in the pneumatic cylinder 1, the piston 22 and the sealing ring are initially in contact with each other. When the pressure in the pressure chamber 25a rises, the force balance acting on the piston 22 is broken, and the pressure in the pressure chamber 25a exceeds. Therefore, the piston 22 moves to a position where the pressure in the pressure chamber 25a and the urging force of the return spring 28 are balanced. That is, in the pneumatic cylinder 1, the piston 22 moves to the right and enters the state shown in FIG.

Next, the measurement result of the position accuracy of the air servo cylinder system of this embodiment will be described. The measurement was performed by changing the command signal from the overall controller 9 to 0V → 5V or 5V → 0V and measuring the position of the piston 22 in the pneumatic cylinder 2 at this time. The measurement results are shown in the graph of FIG. In the graph of FIG. 5, the command signal voltage is plotted on the horizontal axis and the piston stroke is plotted on the vertical axis. The solid line is for extrusion (0 V → 5 V) and the broken line is for suction (5 V → 0 V).
It is a measurement result in. According to FIG. 5, the piston stroke changes from 0 mm to 45 mm with respect to the change of the command voltage from 0 V to 5 V, and the linearity is also good. Further, since the solid line and the broken line in the figure are not substantially separated from each other, it can be understood that the hysteresis component in the movement of the piston 22 can be ignored. From these, it can be understood that the position accuracy of the air servo cylinder is excellent.

Further, a comparison will be made with the case where a high precision potentiometer is used. FIG. 6 is a measurement of the positional accuracy of the piston at the time of extrusion, and FIG. 7 is a comparison of hysteresis. First, as shown in FIG. 6, when a conventional potentiometer is used, a positional deviation of 0.4% at maximum occurs, whereas in the present embodiment, a maximum of 0.2% occurs. Yes, the accuracy is doubled. Next, regarding the hysteresis, as shown in FIG. 7, in the case of using the conventional potentiometer, a shift of about 0.2% occurs, whereas in the present embodiment, it is almost 0.1.
It is a percentage, and it can be understood that the positional accuracy is excellent. Also, by using an ultra-low speed pneumatic cylinder for the pneumatic cylinder, step slick can be effectively prevented,
This is also a factor in improving the above-mentioned positional accuracy.

Next, the actual measurement result of the followability of the air servo cylinder system of this embodiment at ultralow speed will be described with reference to FIG. For the measurement, the command signal given from the controller 9 is changed from 0V → 5V (FIG. 8 (a)) or 5V → 0.
It was performed by setting the signal of V (FIG. 8B) and recording the output value of the potentiometer 2 at that time. The piston speed at this time is 0.6 mm / sec. Further, FIGS. 8A and 8B are graphs showing the time change between the command value (curve A) from the controller 9 and the output value of the potentiometer 3 (curve B) at that time.

From this figure, in any case, it can be seen that the output value of the potentiometer 2 in the air servo cylinder system is 1V → 5V or 5V → 1V, and the linearity is also good. . In particular, it can be understood that the air servo cylinder system has a good followability since no delay is seen with respect to the command signal. The output value of the potentiometer 2 does not cause hunting or overshoot. From these facts and the results of FIG. 5, the air servo cylinder system can be used even in the velocity range of about 0.6 mm / sec.
It is understood that the position accuracy and the speed accuracy are excellent.

Next, a second embodiment of the air servo cylinder system of the present invention will be described. FIG. 9 is a diagram showing the entire control system of the air servo cylinder system of this embodiment. In this embodiment, the same parts as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted. In this embodiment, a main valve 41 is connected to the supply solenoid valve 6 and the discharge solenoid valve 7. The air cylinder 8 is connected to the input port of the main valve 41, and the pneumatic cylinder 1 is connected to the output port.

Next, the structure of the main valve 41 will be described. FIG. 10 is a view showing a cross section of the main valve 41. A supply / exhaust hole 43 connected to the supply solenoid valve 6 and the discharge solenoid valve 7 is formed on the upper surface of the main valve body 42, and communicates with the diaphragm chamber 44. The diaphragm chamber 44 is distinguished from the space below by the diaphragm 45. A vent hole 46 to the outside of the main valve body 42 is provided in the space below it so that the fluid can freely flow. However, the distinction from the space below is blocked by a diaphragm 45 extending around a diaphragm plate 47 formed by a pressing portion 48 extending downward at the center. And the diaphragm plate 4
Below the pressing portion 48 provided at the bottom of the spring 7, the spring 4
The valve body 50 biased upward by 9 is in contact with the valve seat 51 by the biasing force. As a result, the flow path 52 formed in the main valve body 42 becomes
It was distinguished into the 3 side and the output port 54 side.

According to the air servo cylinder system of this embodiment having such a configuration, the output signal from the proportional gain 4 is converted into a pulse signal by the pulse converter 5,
The supply solenoid valve 6 and the discharge solenoid valve 7 are driven to supply or discharge the air pressure into the diaphragm chamber 44 of the main valve 41. At this time, the diaphragm 45 moves up and down due to the pressure adjustment in the diaphragm chamber 44, and at the same time, the pressing portion 48 below the diaphragm plate 47 also moves. Therefore, the valve body 50 arranged at the lower end of the pressing portion 48 is moved up and down against the biasing force of the spring 49. As a result, the air pressure supplied from the air cylinder 8 to the input port 53 flows through the flow path 52, and the air pressure of a predetermined pressure is further supplied from the output port 54 to the pneumatic cylinder 1 to control the piston position.

The air servo cylinder system of this embodiment is excellent in position accuracy and driving stability similar to those of the first embodiment, and becomes a high response servo cylinder by using the main valve 41. Therefore, FIG. 11 shows a comparison of the response of this embodiment with that without the main valve. Here, FIG. 7A is according to this embodiment, and FIG. 8B is one without the main valve. From now on, the conventional one is fully driven by the piston 22 (45 m
m) requires about 2 seconds, but in the case of the present embodiment, the entire driving can be performed in about 1.2 seconds.

Although the embodiment of the air servo cylinder system of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made.
For example, instead of the ultra-low speed pneumatic cylinder used in the embodiment, a bellovram type pneumatic cylinder can be used. Further, for example, instead of the potentiometer used in the embodiment, a magnetic linear scale or an optical linear scale,
Alternatively, it is possible to use a rotary encoder in consideration of space saving.

[0035]

In the air servo cylinder system of the present invention having the above structure, the control valve is a solenoid valve that opens and closes in time according to the pulse frequency, and the pressure chamber in the pneumatic cylinder is supplied with air pressure from the air pressure supply source. The control circuit is composed of a supply solenoid valve for supplying the air pressure and a discharge solenoid valve for discharging the air pressure in the pressure chamber.The control circuit inputs an input signal from the outside in order to command the control valve to an arbitrary piston position. And a position converting means for amplifying a difference between the position sensor signal of the position detecting means and a pulse converting means for converting the amplified signal into a pulse signal for driving the control valve. , It became possible to provide a position control cylinder unit that can realize the speed accuracy of ultra-low speed drive and its followability. Further, in the air servo cylinder system of the present invention, the control valve is connected to the supply solenoid valve, the discharge solenoid valve, and an air pressure supply source, and includes the supply solenoid valve and the discharge solenoid valve. Driven,
Since the main valve is configured to supply air pressure to the pressure chamber in the pneumatic cylinder, it is possible to provide the one having excellent position accuracy and driving stability and high response performance.

[Brief description of drawings]

FIG. 1 is a diagram showing an entire control system of an air servo cylinder system according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing the outer appearance of the air servo cylinder system according to the first embodiment of the present invention.

FIG. 3 is a side view from the left of the air servo cylinder system according to the first embodiment of the present invention.

FIG. 4 is a sectional view of a pneumatic cylinder and a potentiometer provided on the pneumatic cylinder according to the first embodiment of the present invention.

FIG. 5 is a graph showing a measurement result of position accuracy of the air servo cylinder system according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a graph in which the positional accuracy of a piston at the time of extrusion is measured.

FIG. 7 is a diagram showing a graph showing hysteresis of a piston.

FIG. 8 is a diagram showing a graph showing an actual measurement result of trackability at an ultra-low speed.

FIG. 9 is a diagram showing an entire control system of an air servo cylinder system according to a second embodiment of the present invention.

FIG. 10 is a view showing a cross section of a main valve.

FIG. 11 is a diagram showing a graph showing the response of the piston.

FIG. 12 is a diagram showing an entire control system of a conventional air servo cylinder system.

FIG. 13 is a cross-sectional view showing a structure of a seal portion of an example of a pneumatic cylinder.

[Explanation of symbols]

 1 Pneumatic cylinder 2 Potentiometer 3 Amplifier 4 Proportional gain 5 Pulse converter 6 Solenoid valve for supply 7 Solenoid valve for discharge 8 Air cylinder

Claims (2)

[Claims] 1. An ultra-low speed pneumatic cylinder made of a material having a property that a packing of a piston is in a non-lubricated state and a friction coefficient increases with an increase in sliding speed, a control valve for controlling an air pressure supplied to the pneumatic cylinder, and a control It has a control valve drive circuit for controlling the drive of the valve and position detection means for detecting the drive position of the pneumatic cylinder, and feeds back the position information detected by the position detection means to the control circuit to control the drive position of the pneumatic cylinder. In the air servo cylinder system, the control valve is a solenoid valve that opens and closes according to a pulse frequency, and a supply solenoid valve that supplies air pressure from an air pressure supply source to a pressure chamber in the pneumatic cylinder, And a discharge solenoid valve for discharging the air pressure of the pressure chamber, and the control circuit commands the control valve to set an arbitrary piston position. Amplifying means for amplifying a difference between the inputted input signal the position sensor signal of the position detecting means from the outside in order,
An air servo cylinder system comprising: a pulse conversion unit that converts the amplified signal into a pulse signal for driving the control valve. 2. The air servo cylinder system according to claim 1, wherein the control valve supplies from the supply solenoid valve, the discharge solenoid valve, the supply solenoid valve and the discharge solenoid valve. Is driven by the discharged air pressure, and is constituted by a main valve for controlling the air pressure from an air pressure supply source which supplies the pressure chamber in the pneumatic cylinder.