JP7509604B2 - Actuator - Google Patents

Description

The present invention relates to an actuator, and in particular to an actuator that inputs pressure and outputs a displacement according to this input pressure.

Piezo actuators and bellows actuators are so-called nanoactuators that are capable of ultrafine positioning to extract minute and highly accurate displacements.
A piezoelectric actuator is composed of a piezoelectric element polarized in a specific direction, and by applying a voltage to this piezoelectric element, it utilizes the distortion to extract a displacement. Piezo actuators require closed-loop control due to their large hysteresis. In addition, due to the high development costs, piezoelectric actuators are limited to applications that assume mass production or applications that can tolerate high costs, and cannot be used for applications that do not assume mass production or low-cost applications. Furthermore, piezoelectric actuators have the disadvantage that they cannot extract a large amount of displacement unless a high voltage is applied.

A bellows actuator is an actuator that performs position control by feeding back the force applied to the bellows and the amount of distortion of the bellows caused by this force. Bellows actuators are subject to large temperature drift because the amount of distortion determines the amount of movement. They are also easily affected by external noise, and closed-loop control is essential to improve accuracy. For these reasons, they have the disadvantage that it is difficult to reduce costs.

Japanese Patent No. 4690693

The actuator of Patent Document 1 determines its position by the balance of pressures such as air pressure, has small temperature drift, and is not easily affected by disturbance noise. In addition, it has small hysteresis and can be used sufficiently 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, because the pressure balance depends on the spring constant of the elastic hinge mechanism formed in the body, there is a drawback in that, for example, when used lying on its side, the repeatability during backward movement (large hysteresis) deteriorates.

The present invention aims to propose an actuator that can maintain high repeatability both when moving forward and backward.

The actuator according to an embodiment of the present invention comprises a cylinder body having a pressure flange, a body having a storage chamber for storing the cylinder body, a first diaphragm attached to the rear end of the cylinder body to form a first pressure chamber in the storage chamber, a second diaphragm attached to the front end of the cylinder body to form a second pressure chamber in the storage chamber, and 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, and is characterized in that it supplies compressed air 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 balanced.

The actuator according to the embodiment of the present invention is characterized by comprising a plunger fixed to the front end surface of the cylinder body with the second diaphragm sandwiched therebetween, and a base fixed to the rear end surface of the cylinder body with the first diaphragm sandwiched therebetween.

The actuator according to the embodiment of the present invention is characterized in that it comprises a pressure sensor communicating with the second pressure chamber and an electro-pneumatic regulator communicating with the first pressure chamber and the second pressure chamber, the pressure sensor measures the output pressure of the second pressure chamber, and the electro-pneumatic regulator supplies an input pressure to the first pressure chamber and adjusts the input pressure according to a measurement signal from the pressure sensor to position the cylinder body.

The actuator according to an embodiment of the present invention is characterized in that the body includes a first body having the first pressure chamber, a second body having the second pressure chamber and sandwiching the outer periphery of the first diaphragm between the first body, and a third body having the outer periphery of the second diaphragm between the first body.

The actuator of the present invention determines the position of the cylinder body by the balance of air pressure and other pressures, has small temperature drift, and is not easily affected by disturbance noise. Furthermore, even if the actuator is turned over on its side, it can maintain high repeatability both when moving forward and backward (small hysteresis). Furthermore, closed-loop control allows for positioning control with high precision on the order of nanometers.

1 is a vertical cross-sectional view showing an actuator 1 according to an embodiment. FIG. 2 is a plan view showing the actuator 1. FIG. 2 is a schematic diagram showing a configuration when the actuator 1 is subjected to closed-loop control.

Hereinafter, the present invention will be described with reference to the illustrated embodiments.
1 and 2 are diagrams showing an actuator 1 according to this embodiment.
The actuator 1 comprises a substantially cylindrical cylinder 10 and a substantially cubic body 20. A housing chamber 30 for housing the cylinder 10 is formed in the body 20, and the cylinder 10 disposed in the housing chamber 30 moves slightly in the front-rear direction (the up-down direction in FIG. 1 ).
The cylinder 10 and the body 20 are formed from, for example, stainless steel, carbon steel, aluminum alloy, or the like.

The cylinder 10 includes a cylinder body 11, a base 14, and a plunger 15. The plunger 15, the cylinder body 11, and the base 14 are arranged in this order from the front, and are connected by bolts (not shown).
The cylinder main body 11 is a member accommodated in the approximate center (central portion) of the body 20 (accommodation chamber 30), and is composed of a cylindrical rod 12 disposed at the front end side and a disk-shaped pressure flange 13 disposed at the rear end side. 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 plates (membrane) made of metal.
The cylinder body 11 is accommodated in a second pressure chamber 32 (described later) of the accommodation chamber 30 .

The base 14 is a disk-shaped member disposed 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 sandwiched between the base 14 and the cylinder main body 11 to hold the center portion of the first diaphragm 17. In other words, the first diaphragm 17 is disposed between the cylinder main 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 accommodated in a first pressure chamber 31 (described later) of the accommodation 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 sandwiched between them. The plunger 15 cooperates with the cylinder main body 11 to hold the center of the second diaphragm 18. In other words, the second diaphragm 18 is arranged between the cylinder main 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 accommodated in a third chamber 35 (described later) of the accommodation chamber 30, and its front end portion protrudes from the body 20. This front end portion is provided with a screw hole or the like for fixing an external device or the like.

The body 20 is composed of a first body 21, a second body 22, and a third body 23. The third body 23, the first body 21, and the second body 22 are arranged in this order from the front and are connected by bolts. In addition, 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 disposed substantially in the center (centre) of the body 20 and has a second pressure chamber 32 that accommodates the cylinder main body 11 .
The second pressure chamber 32 is a space that penetrates the first body 21 in the front-rear direction, and is composed of 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 flat surface facing the pressure flange 13 toward the rear end side.
The second pressure chamber 32 is connected to a supply pressure port 41 and an output pressure port 43 .

The supply pressure port 41 and the output pressure port 43 open to the side of the body 20 .
An orifice 42 is provided in the air pressure path connecting the supply pressure port 41 to the second pressure chamber 32. The compressed air supplied to the supply pressure port 41 is reduced in pressure 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 air pressure path of the supply pressure port 41. In other words, the air pressure path connecting the supply pressure port 41 to the second pressure chamber 32 branches near the second pressure chamber 32 and connects to the second pressure chamber 32 and the output pressure port 43. As a result, compressed air of the same pressure as the compressed air sealed in the second pressure chamber 32 flows into the output pressure port 43.

Further, a nozzle 45 communicates with the second pressure chamber 32. The nozzle 45 opens into the second space 34 of the second pressure chamber 32. More specifically, the nozzle 45 opens into an annular plane in the second pressure chamber 32 (second space 34) facing the rear end side and facing the pressure flange 13. That is, an opening 46 of the nozzle 45 faces the pressure flange 13 across a small gap. As a result, the opening 46 of the nozzle 45 and the pressure flange 13 function as a nozzle flapper (air micrometer).
Furthermore, the nozzle 45 opens to 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 from the opening 46 and is released to the atmosphere.

The second body 22 is a quadrangular prism-shaped member fixed to the rear end surface of the first body 21 , and has a first pressure chamber 31 that houses the base 14 .
The second body 22 cooperates with the first body 21 to sandwich the outer periphery of the first diaphragm 17. In other words, the first diaphragm 17 is disposed 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 formed by hollowing out the front end surface of the second body 22 in a circular shape toward the rear end side. A control pressure port 44 is connected to the first pressure chamber 31. The control pressure port 44 opens to a side surface of the body 20. Compressed air supplied to the control pressure port 44 flows into the first pressure chamber 31.

The third body 23 is a rectangular plate-shaped member fixed to the front end surface of the first body 21 , and has a third chamber 35 that houses the plunger 15 .
The third body 23 cooperates with the first body 21 to sandwich the outer periphery of the second diaphragm 18. In other words, the second diaphragm 18 is disposed 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 chamber 35 exposes the plunger 15.

As described above, the body 20 is formed with the accommodation chamber 30 that accommodates the cylinder 10. The accommodation chamber 30 is made up of the first pressure chamber 31, the second pressure chamber 32, and the third chamber 35. The third chamber 35, the second pressure chamber 32, and the first pressure chamber 31 are arranged in this order from the front, and are partitioned by the first diaphragm 17 and the second diaphragm 18.
The first pressure chamber 31 is a sealed space located at the rear, and compressed air is supplied from a control pressure port 44 .
The second pressure chamber 32 is a sealed space located in the center. Compressed air is supplied from a supply pressure port 41. The compressed air sealed in the second pressure chamber 32 flows out from a nozzle 45 and is released to the atmosphere.
O-rings are attached at a number of locations inside the body 20 to seal the first pressure chamber 31, the second pressure chamber 32 and the air passages communicating with these pressure chambers.

The first diaphragm 17 and the second diaphragm 18 expand and contract due to pressure fluctuations (internal pressure balance) in the first pressure chamber 31 and the second pressure chamber 32, displacing in the front-rear direction. As the first diaphragm 17 and the second diaphragm 18 displace, the base 14, the cylinder body 11, and the plunger 15 move in the front-rear direction as a unit (i.e., the cylinder 10). As a result, the plunger 15 protruding from the front surface of the body 20 displaces in the front-rear direction.

FIG. 3 is a schematic diagram showing a configuration when the actuator 1 is subjected to closed-loop control.
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. A measurement signal of the pressure sensor 51 is transmitted to the electropneumatic regulator 52.
An electro-pneumatic regulator 52 is connected to the supply pressure port 41 and the control pressure port 44. The electro-pneumatic regulator 52 is a proportional control valve, and is a device that continuously controls air pressure proportional to an input signal (command signal). The primary side port of the electro-pneumatic regulator 52 is connected to the supply pressure port 41, and the secondary side port is connected to the control pressure port 44.

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 reduced in the orifice 42 and is supplied to the second pressure chamber 32.
Next, a command signal CMD is input to the electro-pneumatic regulator 52, causing the electro-pneumatic regulator 52 to supply an input pressure Pi proportional to the command signal CMD from the primary side port of the electro-pneumatic 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, reducing the distance (gap) between the opening 46 of the nozzle 45 and the pressure flange 13. This causes the internal pressure (output pressure Po) of the second pressure chamber 32 to increase.

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). Depending on the distance (gap) between the opening 46 and the pressure flange 13, the output pressure Po is exhausted to the outside of the body 20 via the nozzle 45.
The gap between the opening 46 and the pressure flange 13 is uniquely determined so that the upward pressing force due to the input pressure Pi and the downward pressing force due to the output pressure Po are balanced (equilibrium). In other words, the cylinder 10 moves in the front-rear direction, the input pressure Pi and the output pressure Po are balanced, and the cylinder 10 stops (is positioned).
The output pressure Po is measured by a pressure sensor 51 via the output pressure port 43 and fed back to an electro-pneumatic regulator 52. The electro-pneumatic regulator 52 performs integration so as to eliminate an offset between the command signal CMD and the measurement signal of the pressure sensor 51, thereby accurately positioning the cylinder 10.
Therefore, the front end of the plunger 15 is displaced relative to the body 20 depending on the position of the cylinder 10 in the front-rear direction. The actuator 1 outputs this displacement.

In this way, the positioning of the cylinder 10 of the actuator 1 is determined by the supply pressure Ps and the input pressure Pi, making it possible to perform extremely simple control.
Moreover, since the cylinder 10 is held by a pair of diaphragms 17 and 18, there is almost no hysteresis during forward and backward movement, and no yawing or pitching occurs. In other words, high reproducibility can be maintained both when moving forward and 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).
In addition, since the position of the cylinder 10 is determined by the balance of air pressure, the temperature drift is small and the cylinder is not easily affected by disturbance noise.
In addition, an air micrometer formed by the nozzle 45 (opening 46) and the pressure flange 13 is built in, so that high positional accuracy can be ensured even with open loop control.
Furthermore, the actuator 1 can achieve linear control completely free of hysteresis by using closed loop control.

Such an actuator 1 can be widely used for a variety of purposes, such as positioning the focus of an electron microscope, adjusting the focus of a lens on a stepper in semiconductor manufacturing equipment, and positioning an egg for artificial insemination.

The present invention is not limited to the above-described embodiment, and includes various modifications to the above-described embodiment without departing from the spirit of the present invention. The specific shapes and configurations given in the embodiments are merely examples, and can be modified 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 (3)

a cylinder body having a pressure flange;
a body having a chamber for accommodating the cylinder body;
a first diaphragm attached to a rear end of the cylinder body to form a first pressure chamber in the accommodation chamber;
a second diaphragm attached to a 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;
a plunger fixed to a front end surface of the cylinder body with the second diaphragm sandwiched therebetween;
a base fixed to a rear end surface of the cylinder body with the first diaphragm sandwiched therebetween;
Equipped with
An actuator comprising: a cylinder body that is movable to a position where the internal pressures of the first pressure chamber and the second pressure chamber are balanced by supplying compressed air to the first pressure chamber and the second pressure chamber. a cylinder body having a pressure flange;
a body having a chamber for accommodating the cylinder body;
a first diaphragm attached to a rear end of the cylinder body to form a first pressure chamber in the accommodation chamber;
a second diaphragm attached to a 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;
a pressure sensor communicating with the second pressure chamber and measuring an output pressure of the second pressure chamber;
an electropneumatic regulator communicating with the first pressure chamber and the second pressure chamber;
Equipped with
supplying compressed air to the first pressure chamber and the second pressure chamber to move the cylinder body to a position where the internal pressures of the first pressure chamber and the second pressure chamber are balanced ;
The actuator , characterized in that the electropneumatic regulator supplies an input pressure to the first pressure chamber and adjusts the input pressure in response to a measurement signal from the pressure sensor to position the cylinder body. a cylinder body having a pressure flange;
a body having a chamber for accommodating the cylinder body;
a first diaphragm attached to a rear end of the cylinder body to form a first pressure chamber in the accommodation chamber;
a second diaphragm attached to a 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
supplying compressed air to the first pressure chamber and the second pressure chamber to move the cylinder body to a position where the internal pressures of the first pressure chamber and the second pressure chamber are balanced ;
The body includes:
a first body having the first pressure chamber;
a second body having the second pressure chamber and sandwiching an outer periphery of the first diaphragm between the second body and the second body;
a third body that sandwiches an outer periphery of the second diaphragm between the third body and the first body;
An actuator comprising: