JP2022035748A - Actuator - Google Patents

Abstract

To provide an actuator capable of maintaining high reproductivity even when used in a side tilting state.SOLUTION: The actuator includes a cylinder body having a pressure flange, a body having a storage room for storing the cylinder body, a first diaphragm mounted to the rear end of the cylinder body to form a first pressure chamber in the storage room, a second diaphragm mounted to the front end of the cylinder body to form a second pressure chamber in the storage room, and a nozzle formed on the body and communicated with the second pressure chamber, and having an opening part facing a pressure flange to function as a flapper. Pressurized air is supplied to the first pressure chamber and the second pressure chamber to move the cylinder body to a position where inner pressures thereof are balanced.SELECTED DRAWING: Figure 1

Description

The present invention relates to an actuator, and particularly relates to an actuator that inputs a pressure and outputs a displacement corresponding to the input pressure.

There are piezo actuators and bellows actuators as so-called nanoactuators capable of ultra-fine positioning that obtains minute and highly accurate displacement.
The piezo actuator is composed of a piezoelectric element polarized in a predetermined direction, and by applying a voltage to the piezoelectric element, displacement is taken out by utilizing strain deformation. Since the piezo actuator has a large hysteresis, it is necessary to perform closed loop control. Further, since the development cost of the piezo actuator is high, the piezo actuator is limited to applications premised on mass production or applications where high cost can be tolerated, and cannot be used for applications not premised on mass production or low cost applications. Further, the piezo actuator has a drawback that a large displacement amount cannot be taken out unless the applied voltage is increased.

The bellows actuator is an actuator that feeds back the force applied to the bellows and the amount of strain of the bellows due to this force to control the position. The bellows actuator has a large temperature drift because the amount of strain determines the amount of movement. In addition, it is easily affected by disturbance noise, and closed-loop control is indispensable for improving accuracy. Therefore, there is a drawback that it is difficult to reduce the cost.

Japanese Patent No. 4690693

The position of the actuator of Patent Document 1 is determined by the balance of pressure such as air pressure, the temperature drift is small, and the actuator is not easily affected by disturbance noise. In addition, the hysteresis is small and it can be sufficiently used even in an open loop. Furthermore, by using a position sensor based on pressure such as air pressure, high accuracy can be ensured even in an open loop.
However, since the pressure balance depends on the spring constant of the elastic hinge mechanism formed on the body, there is a drawback that the reproducibility (large hysteresis) at the time of retreat deteriorates when used, for example, when it is laid on its side.

An object of the present invention is to propose an actuator capable of maintaining high reproducibility in both forward and backward movements.

The actuator according to the embodiment of the present invention has a cylinder body having a pressure flange, a body having a storage chamber for accommodating the cylinder body, and a first pressure chamber attached to the rear end of the cylinder body in the storage chamber. The first diaphragm to be formed, the second diaphragm attached to the front end of the cylinder body to form a second pressure chamber in the accommodation chamber, and the pressure flange formed in the body and communicating with the second pressure chamber. A nozzle having an opening that faces and functions as a flapper is provided, and compressed air is supplied to the first pressure chamber and the second pressure chamber, and the cylinder body is moved to a position where the internal pressures of the respective chambers are balanced. , Characterized by that.

The actuator according to the embodiment of the present invention includes a plunger fixed by sandwiching the second diaphragm on the front end surface of the cylinder body, and a base fixed by sandwiching the first diaphragm on the rear end surface of the cylinder body. It is characterized by having.

The actuator according to the embodiment of the present invention includes a pressure sensor communicating with the second pressure chamber and an electropneumatic regulator communicating with the first pressure chamber and the second pressure chamber, and the pressure sensor is the pressure sensor. The output pressure of the second pressure chamber is measured, the electropneumatic regulator supplies an input pressure to the first pressure chamber, and the input pressure is adjusted according to the measurement signal of the pressure sensor to control the cylinder body. It is characterized by positioning.

In the actuator according to the embodiment of the present invention, the body has the first body having the first pressure chamber and the second pressure chamber, and the outside of the first diaphragm is between the first body and the first body. It is characterized by comprising a second body that sandwiches the peripheral edge and a third body that sandwiches the outer peripheral edge of the second diaphragm between the first body.

In the actuator of the present invention, the position of the cylinder body is determined by the balance of pressure such as air pressure, the temperature drift is small, and it is not easily affected by disturbance noise. Further, for example, even when the product is laid on its side, high reproducibility can be maintained both when moving forward and when moving backward (hysteresis is small). Furthermore, the closed loop control enables positioning control with high accuracy on the order of nanometers.

It is a vertical sectional view which shows the actuator 1 which concerns on embodiment. It is a top view which shows the actuator 1. FIG. It is a schematic diagram which shows the structure at the time of closed-loop control of an actuator 1.

Hereinafter, the present invention will be described with reference to the illustrated embodiments.
1 and 2 are views showing the actuator 1 according to the present embodiment.
The actuator 1 includes a cylinder 10 having a substantially cylindrical shape and a body 20 having a substantially cubic shape. A storage chamber 30 for accommodating the cylinder 10 is formed in the body 20, and the cylinder 10 arranged in the storage chamber 30 moves slightly in the front-rear direction (vertical direction in FIG. 1).
The cylinder 10 and the body 20 are formed of, for example, stainless steel, carbon steel, an aluminum alloy, or the like.

The cylinder 10 includes a cylinder body 11, a base 14, and a plunger 15. From the front, the plunger 15, the cylinder body 11, and the base 14 are arranged in this order and connected by bolts (not shown).
The cylinder body 11 is a member housed in the substantially center (center) of the body 20 (storage chamber 30), and has a cylindrical rod 12 arranged on the front end side and a disk-shaped pressure arranged on the rear end side. It is composed of a flange 13. The rod 12 has a diameter of, for example, 15 mm, and the pressure flange 13 has a diameter of, for example, 26 mm.
A first diaphragm 17 is attached to the rear end surface of the pressure flange 13. A second diaphragm 18 is attached to the front end surface of the rod 12. The first diaphragm 17 and the second diaphragm 18 are thin metal plates (thin films).
The cylinder body 11 is housed in a second pressure chamber 32, which will be described later, in the storage chamber 30.

The base 14 is a disk-shaped member arranged on the rear end side of the body 20 (accommodation chamber 30), and is fixed to the rear end surface of the pressure flange 13 with the first diaphragm 17 interposed therebetween. The base 14 cooperates with the cylinder body 11 to sandwich the central portion of the first diaphragm 17. That is, the first diaphragm 17 is arranged between the cylinder body 11 and the base 14.
The base 14 has a smaller diameter than the pressure flange 13. The base 14 has a diameter of, for example, 20 mm.
The base 14 is housed in the first pressure chamber 31, which will be described later, in the storage chamber 30.

The plunger 15 is a cylindrical member arranged on the front end side of the body 20 (accommodation chamber 30), and is fixed to the front end surface of the rod 12 with the second diaphragm 18 interposed therebetween. The plunger 15 cooperates with the cylinder body 11 to sandwich the central portion of the second diaphragm 18. That is, the second diaphragm 18 is arranged between the cylinder body 11 and the plunger 15.
The plunger 15 has the same diameter as the rod 12. The plunger 15 has a diameter of, for example, 15 mm.
The plunger 15 is housed in a third room 35, which will be described later, in the storage room 30, and its front end portion protrudes from the body 20. A screw hole or the like for fixing an external device or the like is provided at the front end portion.

The body 20 is composed of a first body 21, a second body 22, and a third body 23. From the front, the third body 23, the first body 21, and the second body 22 are arranged in this order and connected by bolts. Further, the second body 22 is arranged so as to cover the outer periphery of the first body 21.
The first body 21 is a cylindrical member arranged substantially in the center (center) of the body 20, and has a second pressure chamber 32 for accommodating the cylinder body 11.
The second pressure chamber 32 is a space that penetrates the first body 21 in the front-rear direction, and includes a cylindrical first space 33 that accommodates the rod 12 and a cylindrical second space 34 that accommodates the pressure flange 13. .. The inner diameter of the first space 33 is smaller than the diameter (outer diameter) of the pressure flange 13. The second space 34 of the second pressure chamber 32 has an annular plane facing the rear end side and facing the pressure flange 13.
The supply pressure port 41 and the output pressure port 43 communicate with each other in the second pressure chamber 32.

The supply pressure port 41 and the output pressure port 43 open on the side surface of the body 20.
An orifice 42 is provided in the pneumatic path connecting the supply pressure port 41 to the second pressure chamber 32. The compressed air supplied to the supply pressure port 41 is decompressed by the orifice 42 and flows into the second pressure chamber 32.
The output pressure port 43 communicates with the downstream side (between the orifice 42 and the second pressure chamber 32) of the pneumatic path of the supply pressure port 41. That is, the pneumatic passage connecting the supply pressure port 41 to the second pressure chamber 32 branches in the vicinity of the second pressure chamber 32 and is connected to the second pressure chamber 32 and the output pressure port 43, respectively. As a result, compressed air having the same pressure as the compressed air enclosed in the second pressure chamber 32 flows into the output pressure port 43.

Further, the nozzle 45 communicates with the second pressure chamber 32. The nozzle 45 opens in the second space 34 of the second pressure chamber 32. Specifically, the nozzle 45 opens in the second pressure chamber 32 (second space 34) in an annular plane facing the rear end side and facing the pressure flange 13. That is, the opening 46 of the nozzle 45 faces the pressure flange 13 with a slight gap. As a result, the opening 46 of the nozzle 45 and the pressure flange 13 function as a nozzle flapper (air micrometer).
Further, the nozzle 45 opens on the side surface of the body 20. As a result, the compressed air sealed in the second pressure chamber 32 flows into the nozzle 45 through the opening 46 and is released to the atmosphere.

The second body 22 is a prismatic member fixed to the rear end surface of the first body 21 and has a first pressure chamber 31 for accommodating the base 14.
The second body 22 cooperates with the first body 21 to sandwich the outer peripheral edge of the first diaphragm 17. That is, the first diaphragm 17 is arranged between the first body 21 and the second body 22 to seal the first pressure chamber 31.
The first pressure chamber 31 is a space in which the front end surface of the second body 22 is dug in a circular shape toward the rear end side. A control pressure port 44 communicates with the first pressure chamber 31. The control pressure port 44 opens on the side surface of the body 20. The compressed air supplied to the control pressure port 44 flows into the first pressure chamber 31.

The third body 23 is a square plate-shaped member fixed to the front end surface of the first body 21, and has a third chamber 35 for accommodating the plunger 15.
The third body 23 cooperates with the first body 21 to sandwich the outer peripheral edge of the second diaphragm 18. That is, the second diaphragm 18 is arranged between the first body 21 and the third body 23 to seal the second pressure chamber 32.
The third chamber 35 is a cylindrical space that penetrates the third body 23 in the front-rear direction. The third chamber 35 opens to the front surface of the body 20. As a result, the third room 35 exposes the plunger 15.

As described above, the body 20 is formed with a storage chamber 30 for accommodating the cylinder 10. The accommodation chamber 30 includes a first pressure chamber 31, a second pressure chamber 32, and a third chamber 35. From the front, the third chamber 35, the second pressure chamber 32, and the first pressure chamber 31 are arranged in this order, and are partitioned by the first diaphragm 17 and the second diaphragm 18.
The first pressure chamber 31 is a closed space arranged rearward, and compressed air is supplied from the control pressure port 44.
The second pressure chamber 32 is a closed space arranged in the center. Compressed air is supplied from the supply pressure port 41. Further, the compressed air sealed in the second pressure chamber 32 flows out from the nozzle 45 and is released to the atmosphere.
Inside the body 20, O-rings are attached at a plurality of places to seal the first pressure chamber 31, the second pressure chamber 32, and the air passages communicating with these pressure chambers.

Due to the pressure fluctuation (internal pressure balance) of the first pressure chamber 31 and the second pressure chamber 32, the first diaphragm 17 and the second diaphragm 18 expand and contract and are displaced in the front-rear direction. With the displacement of the first diaphragm 17 and the second diaphragm 18, the base 14, the cylinder body 11, and the plunger 15 are integrated (that is, the cylinder 10) and move in the front-rear direction. As a result, the plunger 15 protruding from the front surface of the body 20 is displaced in the front-rear direction.

FIG. 3 is a schematic diagram showing a configuration when the actuator 1 is controlled in a closed loop.
A pressure sensor 51 is connected to the output pressure port 43. The pressure sensor 51 measures the internal pressure of the second pressure chamber 32 via the output pressure port 43. The measurement signal of the pressure sensor 51 is transmitted to the electropneumatic regulator 52.
An electropneumatic regulator 52 is connected to the supply pressure port 41 and the control pressure port 44. The electropneumatic regulator 52 is a proportional control valve, and is a device that continuously controls an air pressure proportional to an input signal (command signal). The primary side port of the electropneumatic regulator 52 and the supply pressure port 41 are connected, and the secondary side port and the control pressure port 44 are connected.

Next, the operation of the actuator 1 will be described.
First, the supply pressure Ps is supplied from the electropneumatic regulator 52 to the supply pressure port 41. The supply pressure Ps is depressurized at the orifice 42 and supplied to the second pressure chamber 32.
Next, the command signal CMD is input to the electropneumatic regulator 52, and the input pressure Pi proportional to the command signal CMD is supplied from the primary side port of the electropneumatic regulator 52. The input pressure Pi is supplied to the first pressure chamber 31 via the control pressure port 44.
When the input pressure Pi is supplied to the first pressure chamber 31, the cylinder 10 moves forward to reduce the distance (gap) between the opening 46 of the nozzle 45 and the pressure flange 13. As a result, the internal pressure (output pressure Po) of the second pressure chamber 32 rises.

The nozzle 45 (opening 46) and the pressure flange 13 function as a nozzle flapper. The nozzle 45 (opening 46) and the pressure flange 13 are also configured as an air micrometer (gap sensor, position sensor). The output pressure Po is exhausted to the outside of the body 20 via the nozzle 45 according to the distance (gap) between the opening 46 and the pressure flange 13.
Then, the gap between the opening 46 and the pressure flange 13 is uniquely determined so as to balance (balance) the upward pressing force due to the input pressure Pi and the downward pressing force due to the output pressure Po. That is, the cylinder 10 moves in the front-rear direction, the input pressure Pi and the output pressure Po are balanced, and the cylinder 10 is stopped (positioned).
The output pressure Po is measured by the pressure sensor 51 via the output pressure port 43 and fed back to the electropneumatic regulator 52. The electropneumatic regulator 52 accurately positions the cylinder 10 by integrating so that the offset between the command signal CMD and the measurement signal of the pressure sensor 51 is eliminated.
Therefore, the front end portion of the plunger 15 is displaced with respect to the body 20 according to the position in the front-rear direction of the cylinder 10. The actuator 1 takes out this displacement as an output.

As described above, since the positioning of the cylinder 10 of the actuator 1 is determined by the supply pressure Ps and the input pressure Pi, extremely simple control becomes possible.
Moreover, since the cylinder 10 is held by a pair of diaphragms 17 and 18, there is almost no hysteresis when moving in the front-rear direction, and yawing and pitching do not occur. That is, high reproducibility can be maintained both when moving forward and when moving backward.
Therefore, the actuator 1 can position the cylinder 10 on the order of nanometers. The resolution of the actuator 1 is, for example, 1/1000 or less, and when the movable distance of the cylinder 10 is 100 μm, the actuator 1 has a positioning accuracy of 10 nm or less. The movable distance of the cylinder 10 can be set by a combination of the inner diameter of the orifice 42 and the inner diameter of the nozzle 45 (opening 46).
Further, since the position of the cylinder 10 is determined by the balance of air pressure, the temperature drift is small and it is not easily affected by disturbance noise.
Further, it has a built-in air micrometer composed of a nozzle 45 (opening 46) and a pressure flange 13, so that high position accuracy can be ensured even in open loop control.
Further, the actuator 1 can realize linear control without complete hysteresis by using closed loop control.

Such an actuator 1 can be widely applied to various applications such as positioning the focus of an electron microscope, adjusting the focus of a lens on a stepper of a semiconductor manufacturing apparatus, and positioning an artificially fertilized egg.

The present invention is not limited to the above-described embodiment, and includes various modifications of the above-mentioned embodiment without departing from the spirit of the present invention. The specific shape, configuration, etc. given in the embodiment are merely examples, and can be changed as appropriate.

1 Actuator 10 Cylinder 11 Cylinder body
13 Pressure flange
14 base
15 Plunger
17 First diaphragm
18 Second diaphragm
20 body 21 first body
22 Second body
23 Third body
30 containment room
31 First pressure chamber
32 Second pressure chamber
41 Supply pressure port
42 Orifice
43 Output pressure port
44 Control pressure port
45 nozzle
46 opening
51 Pressure sensor
52 Electro-pneumatic regulator
Pi input pressure
Po output pressure
Ps supply pressure

Claims (4)

A cylinder body with a pressure flange and
A body having a storage chamber for accommodating the cylinder body, and
A first diaphragm attached to the rear end of the cylinder body to form a first pressure chamber in the accommodation chamber,
A second diaphragm attached to the front end of the cylinder body to form a second pressure chamber in the accommodation chamber,
A nozzle formed in the body, communicating with the second pressure chamber, and having an opening facing the pressure flange and functioning as a flapper.
Equipped with
An actuator characterized in that compressed air is supplied to the first pressure chamber and the second pressure chamber to move the cylinder body to a position where the internal pressures of the respective chambers are in equilibrium. A plunger fixed to the front end surface of the cylinder body with the second diaphragm sandwiched between them.
A base fixed to the rear end surface of the cylinder body with the first diaphragm sandwiched between them.
The actuator according to claim 1, wherein the actuator is provided. A pressure sensor communicating with the second pressure chamber and
An electropneumatic regulator communicating with the first pressure chamber and the second pressure chamber,
Equipped with
The pressure sensor measures the output pressure of the second pressure chamber and
The electropneumatic regulator is characterized in that an input pressure is supplied to the first pressure chamber, the input pressure is adjusted according to a measurement signal of the pressure sensor, and the cylinder body is positioned. Or the actuator according to 2. The body is
The first body having the first pressure chamber and
A second body having the second pressure chamber and sandwiching the outer peripheral edge of the first diaphragm between the first body and the second body.
A third body that sandwiches the outer peripheral edge of the second diaphragm between the first body and the third body.
The actuator according to any one of claims 1 to 3, wherein the actuator comprises.

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