JPH1030611A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform the rapid starting of the rod of a DC servo motor. SOLUTION: An air cylinder 4 and a voice coil type actuator 5 are arranged in a case 2 such that the rod 6 and the shaft 7 thereof are positioned vertically and on one and the same axis. The cylinder chamber 12 of the air cylinder 4 is communicated with the output port of a solenoid valve 16, and an energization amount and the energization direction of a current to energize the moving coil 26 of the voice coil type actuator are controlled by a servo controller 45. Further, a controller 47 is provided to be operated at the initial stage of energization when a shaft is moved downward from the servo controller 45 to the moving coil 26 and excite the solenoid of the solenoid valve 16. When, through energization, the moving coil is started to move downward, compressed air is fed to a cylinder chamber 12 and the rod 6 is moved downward, and the shaft 7 is pressed by the rod to accelerate downward movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator using a DC servo motor.

[0002]

2. Description of the Related Art A shaft for mounting work equipment, and an electromagnetic servo drive unit for vertically moving the shaft,
A DC servomotor that controls the energization of the coil of the electromagnetic servo drive unit by a servo controller to stop the shaft at a predetermined position is already known. This has the advantage that the stop position of the shaft can be precisely positioned by controlling the stop position. However, the DC servo motor has a problem that the start-up of the shaft is delayed due to the back electromotive force generated in the electromagnetic servo drive unit at the beginning of energization of the coil. This delay in start-up is an obstacle to speeding up work.

In addition, when the work is gripped or sucked and lifted by the working equipment with the shaft attached thereto, unlike the case where the stop position of the shaft is held, the amount of electricity supplied to the coil increases and the power consumption increases. Particularly, when the weight of the work is large, the amount of heat generated by the coil increases due to an increase in the amount of energization, so that it may be necessary to provide cooling means for the coil.

[0004]

A first object of the present invention is to provide a linear actuator in which the shaft of a DC servomotor moves down with good responsiveness.

A second object of the present invention is to provide the above linear actuator which consumes less power.

[0006]

In order to solve the above-mentioned first problem, a linear actuator according to the present invention has a shaft for mounting a working device, and an electromagnetic servo drive unit for moving the shaft up and down. A DC servomotor that controls energization of a coil of the electromagnetic servo drive unit by a controller to stop the shaft at a predetermined position; and a piston that moves up and down in the cylinder and its rod,
An air cylinder that lowers the rod by supplying compressed air to a cylinder chamber partitioned by a piston, and a linear actuator in which the rod and the shaft are arranged vertically on the same axis and installed in a case. The servo controller is provided with a compressed air supply unit that operates at the beginning of the current supply for moving the shaft down to the coil and supplies compressed air to the cylinder chamber. It is characterized in that a rod that moves downward with compressed air supplied to the cylinder chamber presses the shaft to accelerate the downward movement.

In order to solve the above first and second problems, a linear actuator according to the present invention has a shaft for mounting a working device, and an electromagnetic servo drive unit for moving the shaft up and down. A DC servomotor for controlling the energization of the coil of the electromagnetic servo drive unit to stop the shaft at a predetermined position; and a pair of cylinders having a piston moving up and down in the cylinder and its rod, and partitioned by the piston A linear actuator having a double-acting air cylinder for vertically moving the rod by supplying and discharging compressed air to and from the chamber, wherein the rod and the shaft are arranged vertically on the same axis and installed in a case. The rod and the shaft are connected so as to be integrally movable in the axial direction, and the pair of cylinder chambers are proportional to the amount of electricity supplied to the solenoid. A proportional electromagnetic pressure control valve for outputting air pressure is connected to each of the cylinders, and the servo controller is operated by applying a current for moving the shaft downward to the coil, and a pair of cylinders are controlled by controlling the amount of current supplied to the solenoid. Compressed air supply means for adjusting the air pressure supplied to and discharged from the chamber is provided, the shaft is pressed by a rod that moves downward by the supply of compressed air to the upper cylinder chamber, and the downward movement is accelerated. It is characterized in that the shaft at the lower movement position is pulled up by the rod which moves upward by the supply of the compressed air.

Further, in order to solve the same problem, a rod and a shaft in the linear actuator are relatively movably connected by a connector having an engaging portion engaged with each other by upward movement of the rod. Provided with compressed air supply means for supplying and discharging compressed air to and from the pair of cylinder chambers by supplying a current for lowering the shaft to the coil and supplying compressed air to the upper cylinder chamber. Pushing the shaft with a moving rod to accelerate its downward movement, engaging the above engaging portion with a rod that moves upward by supplying compressed air to the lower cylinder chamber, and pulling up the shaft at the lower movement position It is characterized by.

In order to solve the same problem, the sliding portion of the air cylinder in these linear actuators is supported by an air bearing in a floating state.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a case, a single-acting air cylinder and a voice coil type actuator which is an example of a DC servomotor are arranged vertically with their rod and shaft arranged on the same axis. . When a current is supplied from the servo controller to the movable coil of the voice coil type actuator to move the coil downward, at the beginning of the current supply, the controller, which is an example of compressed air supply means, operates to activate the cylinder chamber of the air cylinder. To supply compressed air to the shaft, whereby the lowering rod presses the shaft to accelerate the lowering. When the shaft moves down, the position signal is fed back to the servo controller, and the servo controller controls the amount and direction of current supply to the movable coil based on this signal to accurately stop the shaft at a desired stop position.

Further, when the rod of the double-acting air cylinder and the shaft of the voice coil type actuator are connected so as to be movable integrally, or they are connected so as to be relatively movable by a connector having an engaging portion, the compressed air supply is possible. The rod which moves down by the compressed air supplied to the upper cylinder chamber by the operation of the means presses the shaft to accelerate the lowering. When compressed air is supplied to the lower cylinder chamber by the compressed air supply means, the rod moves upward, thereby pulling up the shaft integrally connected to the rod, or moving the engaging portion by the upward movement of the rod to lower the shaft. Pull up the shaft. In these cases, even without energizing the moving coil,
Since the rod and shaft move upward due to the compressed air supplied to the lower cylinder chamber, power consumption does not increase even when a heavy work is lifted by the work equipment attached to the rod. Not much.

Further, since the sliding portions of these air cylinders are supported in a floating state by air bearings, and the sliding resistance of the sliding portions is almost eliminated, the rod can be quickly moved down by the compressed air. Can be accelerated more quickly.

[0013]

1 and 2 show a first embodiment of the present invention.
The linear actuator 1 includes a case 2, a cover 3 that covers an opening of the case 2, a single-acting air cylinder 4 installed in the upper part of the case 2, and a voice coil type that is an example of a DC servo motor installed in a lower part. An actuator 5 is provided, and a rod 6 of the air cylinder 4 and a shaft 7 of the voice coil type actuator 5 are arranged on the same axis. The air cylinder 4 includes a cylinder 9 formed in the case 2 and an end plate 10 that hermetically closes an opening thereof, a piston 11 and a rod 6 that reciprocate the cylinder 9 in an airtight manner, and a cylinder chamber defined by the piston 11. The air supply / discharge port 14 supplies / discharges compressed air to / from the cylinder chamber 12 and a respiratory port 15 opened to the respiratory chamber 13. An electromagnetic valve 16 is connected to the supply / discharge port 14.

The solenoid valve 16 has a supply port P, an output port A, and a discharge port R for compressed air, and switches the output port A between the supply port P and the discharge port R by exciting and releasing the solenoid 16a. The supply port P is connected to a compressed air source 18 via an air tank 17. Since the rod 6 presses the shaft 7 to accelerate its downward movement, the air cylinder 4 is smaller than the voice coil type actuator 5, and the stroke of the rod 6 is shorter than the stroke of the shaft 7. I have.

The voice coil type actuator 5 is shown in FIG.
As shown in FIG. 1, a magnetic frame 2 having a center yoke 21, bottom yokes 22 on both sides thereof, and side yokes 23 connecting both upper and lower ends of these yokes (see FIG. 1).
4, an electromagnetic servo drive unit 20 having magnets 25, 25 attached to the surface of the bottom yoke 22 on the center yoke side, and a movable coil 26 wound around the center yoke 21 and capable of moving up and down along the center yoke 21. The magnetic frame 24 is mounted on the bottom surface of the case 2 by mounting bolts (not shown) passing through the side yokes 23, 23. When a direct current is applied to the movable coil 26, the electromagnetic servo driver 20 moves the movable coil 26 up and down according to the Fleming's left hand rule. A coil holder 28 and a coil holder 29 formed of a non-magnetic material such as a synthetic resin are attached to the movable coil 26 by mounting screws 30, 30, and are attached to the coil holder 29 by appropriate means (not shown). A metal mover 31 is attached. A linear guide rail 32 is attached to the bottom surface of the case 2.
The linear guide 33 that moves along the linear guide rail 32 is attached to the moving element 31 by attaching screws 34.

A linear scale 36 is mounted on the wall surface of the case 2 opposite to the electromagnetic servo drive unit 20, and an encoder electric board 37 for reading the scale of the linear scale 36 and outputting a signal is mounted on the tip of the moving element 31. ing. The shaft 7 has a large-diameter portion and a small-diameter portion, and a male screw formed at the base end of the small-diameter portion is screwed into a female screw formed in a through hole of the mover 31, and a step portion is formed on the upper surface of the mover 31. An appropriate working tool (not shown) such as an air chuck or a suction pad is attached to the distal end of the small-diameter portion that is supported by the bearings 38 and protrudes out of the case 2 while being abutted.

A multi-pole connector 40 constituting a power and signal connector is provided on a side wall of the case 2, an intermediate connector 41 is provided on a mounting boss 2 a of the case 2, and a coil holder 2 is provided.
9, a connector 42 is attached by a mounting screw. The power receiving connector 43 and the intermediate connector 41 electrically connected to the multipolar connector 40, and the intermediate connector 41 and the connector 42 are all connected by a flat ribbon cable 44. It is electrically connected. A DC power supply 46 is connected to the multi-pole connector 40 via a servo controller 45. Servo controller 45
Is a device that supplies a DC with a controlled amount of current (current value) and a direction of current to the movable coil 26, whereby the movable coil 26 moves up and down. The encoder electric board 37 that moves integrally with the movable coil 26 is a linear scale 3
6 is read and the position signal of the shaft 7 is output.
This signal is fed back to the servo controller 45.

The servo controller 45 is connected to a controller 47 constituting a compressed air supply means.
The controller 47 operates at the beginning when a current for moving the movable coil 26 down is supplied from the servo controller 45 to excite the solenoid 16a to supply compressed air to the cylinder chamber 12, and the rod 6 moves downward. When the shaft 7 is pressed, the excitation of the solenoid 16a is released,
This is for discharging air from the cylinder chamber 12. Reference numeral 48 in FIG. 1 denotes a sliding seal made of an O-ring fitted on the outer periphery of the rod 6 and the piston 11.

In the first embodiment, the servo controller 4
When a current for moving the coil is moved upward from 5 to the movable coil 26, the movable coil 26 and the shaft 7 move upward to move the rod 6 of the air cylinder 4 upward. When a current is applied to the movable coil 26 to move the coil downward from the servo controller 45, the movable coil 26 and the shaft 7 start to move downward, and at the beginning of the energization, the controller 47 operates to excite the solenoid 16a of the solenoid valve 16. I do. As a result, the compressed air stored in the air tank 17 is promptly supplied from the solenoid valve 16 to the cylinder chamber 12, and the piston 11 and the rod 6 move down rapidly to press the shaft 7, so that the shaft 7 moves down. Is accelerated. Therefore, the shaft 7 is opposed to the back electromotive force of the electromagnetic servo drive 20.
Moves down with good responsiveness. When the shaft 7 moves down, the excitation of the solenoid 16a by the controller 47 is released, so that the cylinder chamber 12 communicates with the outside.

The movable coil 26 and the shaft 7 are smoothly moved up and down by being guided by the linear guide rail 32 and the linear guide 33. Then, an encoder electric board 37 attached to the moving element 31 reads the scale of the linear scale 36 and feeds back a position signal to the servo controller 45, and the servo controller 45 uses the feedback signal to determine the amount of current and the direction of current to the movable coil 26. By controlling, the shaft 7 is accurately stopped at a predetermined stop position. In this case, the amount of current supplied to the movable coil 26 is
It merely generates a force that balances the weight of the member that moves with the movable coil 26. When current is applied from the servo controller 45 to the movable coil 26 in a direction to move the coil upward, these move upward and return to the original position.

FIG. 3A shows the relationship between the amount of displacement of a shaft of a known voice coil type actuator and time.
(B) shows the relationship between the displacement amount of the rod 6 of the air cylinder 4 and time, and (C) shows the relationship between the displacement amount of the shaft 7 when the rod 6 presses the shaft 7 and time. The symbol a in FIG. 3 is the time when the movable coil 26 is energized. As is clear from the comparison between (A) and (C), the shaft 7 can be quickly moved downward by the rod 6 pressing the shaft 7.

The linear tutor is operated by an air chuck 49 (see FIG. 4) attached to the tip of the shaft 7.
It may be used as a transfer device for holding and transferring a work (not shown). In this case, the electromagnetic servo drive unit 2
Unlike the case where only the zero is moved upward, a current for moving the electromagnetic servo drive unit 20 upward against the weight of the work gripped by the air chuck 49 needs to be supplied to the movable coil 26. If the weight is heavy, the amount of current supplied to the movable coil 26 increases, and the power consumption increases. As a result, the amount of heat generated by the movable coil also increases.

FIG. 4 shows a second embodiment of the present invention which solves this problem. The linear actuator 51 of the second embodiment includes a double-acting air cylinder 52, and the rod 6 of the air cylinder 52 and the voice coil type. The shaft 7 of the actuator 5 is integrally connected by a connecting pin 53 without play in the axial direction, and an air chuck 49 is attached to a tip of the shaft 7 protruding from the case 2. In addition, a pair of cylinder chambers 54 partitioned by the piston 11
supply and discharge ports 55a and 55b communicating with
Proportional electromagnetic pressure control valves 56a, 56 capable of controlling output air pressure by the amount of electricity supplied to proportional solenoids 57a, 57b.
b is connected, and the amount of electricity supplied to the proportional solenoids 57a and 57b is controlled by a controller 58 constituting a compressed air supply unit. Another configuration of the second embodiment is the first configuration.
Since the present embodiment is the same as the embodiment, the same reference numerals are given to the same main parts in the drawings, and the detailed description is omitted.

In the second embodiment, the servo controller 4
5 to the movable coil 26 and a current to move the coil downward, and when the controller 58 energizes the proportional solenoid 57a of the proportional electromagnetic pressure control valve 56a, compressed air is supplied to the cylinder chamber 54a and the rod 6
Moves down, and the shaft 7 connected thereto also moves down. Therefore, the downward movement of the shaft 7 can be accelerated by the rod 6. When the shaft 7 moves down near a predetermined stop position, the energization of the proportional solenoid 57a is released to energize the proportional solenoid 57b, and the cylinder chamber 54b
Compressed air is supplied to the cylinder chamber 54, and the air pressure in the cylinder chamber 54 is adjusted by the controller 58 to an air pressure that generates an action force substantially balanced with the weight of the member that moves downward. Next, the amount of current supplied to the movable coil 26 and the direction of current supplied thereto are controlled by the servo controller 45, and the shaft 7 is accurately stopped at a predetermined stop position. When the energization of the movable coil 26 is released by the servo controller 45, the cylinder chamber 54
The rod 6 moves upward by the action force of the air pressure supplied to b, and the shaft 7 is pulled up.

In the second embodiment, since the acting force of the air pressure supplied to the cylinder chamber 54b below the double-acting air cylinder 52 is almost balanced with the weight of the working equipment such as the air chuck 49, the shaft 7 stops. The amount of current to the movable coil 26 for maintaining the position can be reduced.
Further, the shaft 7 is moved upward by the action force of the air pressure supplied to the cylinder chamber 54b.
Even if the weight of the work held by the
Since it is not necessary to supply a current for moving these to 6, power consumption is small and the amount of heat generated by the movable coil can be reduced.

In the second embodiment, the sliding seals 48 are provided on the outer periphery of the piston 11 and the rod 6 of the air cylinder 52.
Therefore, if the sliding resistance of the sliding seal is large, the downward movement of the rod 6 may be delayed. FIG. 5 shows a modification of the second embodiment in which this problem is solved. The air cylinder 62 of the linear actuator 61 has an air bearing on the outer peripheral surface of the piston 11 and the surface of the case 2 and the rod 6 of the end plate 10 facing each other. 63 are formed, and these circumferential grooves communicate with a compressed air source through a plurality of flow paths 64 and 65 that are opened at equal intervals in the circumferential direction of the circumferential grooves. The other configuration of the modified example is the same as that of the second embodiment, and the description is omitted.

In the above modification, since the piston 11 and the rod 6 of the air cylinder 62 are supported in a floating state by the air bearing 63, unlike those having the sliding seal 48, these sliding resistances are almost eliminated. Therefore, the rod 6 can be moved down more quickly. Further, since there is almost no sliding resistance of the air cylinder 52, the stop position of the shaft 7 can be accurately controlled even if the rod 6 and the shaft 7 are connected by the connecting pin 53.

FIG. 6 shows a third embodiment of the present invention. A connector 72 is attached to the rod 6 of the air cylinder 52 and the tip of the shaft 7 of the voice coil type actuator 5 in the linear actuator 71. The connector 72 includes a mounting portion 73 for mounting to the rod 6 and the shaft 7, and an engaging portion 74 on the opposite side that can be engaged with each other. These connectors 72, 72
When the rod 6 and the shaft 7 are in the upward movement position in the drawing, the mounting portion 73 and the engagement portion 74 respectively abut, and the rod 6
When the shaft 7 is moved downward, there is a relationship such that a slight gap is formed between the engaging portions 74, 74.

The cylinder chambers 54a, 5 of the air cylinder 52
The solenoid valve 76 for supplying and discharging compressed air to and from the pressure fluid supply port 4b includes a supply port P for pressure fluid, output ports A and B, and discharge ports EA and E.
B, and the supply port P is supplied by excitation of the solenoid 76a.
And the output port A, the output port B, and the discharge port EB, and the supply port P and the output port B, and the output port A, and the discharge port EA are connected by excitation of the solenoid 76b, and the excitation of these solenoids is released. At the set intermediate stop position, the output ports A and B communicate with the discharge ports EA and EB, respectively.
It is configured as a port valve, and the output ports A and B communicate with the supply / discharge ports 55a and 55b, respectively. The excitation and release of these solenoids 76a and 76b are controlled by the controller 77. Since the other configuration of the third embodiment is the same as that of the first embodiment, the same reference numerals are given to the same main parts in the drawing, and the detailed description is omitted.

In the third embodiment, when the solenoid valve 76 is at the intermediate stop position, when the servo controller 45 applies a current for moving the movable coil 26 to the movable coil 26, the movable coil 26 and the shaft 7 move upward. As a result, the engaging portion 74 comes into contact with the mounting portion 73 to move the rod 6 upward. When a current for moving the coil is moved downward from the servo controller 45 to the movable coil 26, the solenoid 76a is excited by the controller 77 at the beginning of the energization, so that compressed air is supplied to the cylinder chamber 54a and the rod 6 moves downward. The shaft 7 is brought into contact with the mounting portion 73 and the locking portion 74.
Is pressed to accelerate the downward movement. When the shaft 7 is pressed, the excitation of the solenoid 76a by the controller 77 is released, and the solenoid valve 76 returns to the intermediate stop position. The control of the stop position of the shaft 7 by the servo controller 45 after the lowering of the shaft is the same as that of the first embodiment. There is a gap.

The solenoid 76 is controlled by the controller 77.
When b is excited, the compressed air is supplied to the lower cylinder chamber 54b, and the rod 6 moves upward.
4 and 74 are engaged so that the shaft 7 moved down
Raised by Therefore, since it is not necessary to energize the movable coil 26 when the shaft 7 is moved upward, even if the weight of the work held by the air chuck 49 is heavy, power consumption is small and the amount of heat generated by the movable coil 26 is reduced. Can be smaller. The other operation of the third embodiment is the same as that of the first embodiment, and thus the description is omitted. Although not shown, the rod 6 and the piston 11 in the third embodiment can also be supported in a floating state by the air bearing 62 without the sliding seal 48.

[0032]

According to the linear actuator of the present invention, when a current for moving the coil of the DC servomotor is moved downward, the compressed air supply means operates to supply compressed air to the cylinder chamber. The downwardly moving rod presses the shaft of the DC servomotor to accelerate the downward movement, so that the shaft can be quickly moved downward. Also, since the air cylinder is a double-acting type, the working equipment and the work attached to the shaft are moved up by this air cylinder, so that even if they are heavy, power consumption is small and the amount of heat generated by the coil is small. can do. Furthermore, the sliding resistance of the air cylinder can be almost eliminated by the air bearing provided on the sliding portion of the air cylinder, whereby the rod moves down quickly and presses the shaft. Can move.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a first embodiment.

FIG. 2 is a sectional view taken along line AA of FIG.

FIGS. 3A to 3C are diagrams illustrating a relationship between a displacement amount of a shaft and time.

FIG. 4 is a vertical sectional front view of the second embodiment.

FIG. 5 is a longitudinal sectional front view of a main part of a modification of the second embodiment.

FIG. 6 is a vertical sectional front view of the third embodiment.

[Explanation of symbols]

 1, 51, 61, 71 Linear actuator 2 Case 4, 52, 62 Air cylinder 5 Voice coil type actuator 6 Rod 7 Shaft 11 Piston 12, 54a, 54b Cylinder chamber 20 Electromagnetic servo drive unit 26 Moving coil 45 Servo controller 47, 58 , 77 Controller 56a, 56b Proportional electromagnetic pressure control valve 57a, 57b Proportional solenoid 72 Connector 74 Engagement part

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Nobuhiro Fujiwara 4-2-2 Kinudai, Yawaharamura, Tsukuba-gun, Ibaraki Pref. SMC Corporation Tsukuba Technical Center

Claims (4)

[Claims] 1. A shaft for mounting a working device, and an electromagnetic servo drive unit for moving the shaft up and down, and a servo controller controls energization of a coil of the electromagnetic servo drive unit to move the shaft to a predetermined position. A direct-current servomotor for stopping the cylinder; and an air cylinder having a piston that moves up and down in the cylinder and a rod thereof, and an air cylinder that moves the rod downward by supplying compressed air to a cylinder chamber defined by the piston. And a shaft arranged on the same axis and up and down in the case and installed in the case, wherein the servo controller is operated at the beginning of the passage of current for moving the shaft down to the coil, A compressed air supply means for supplying compressed air to the cylinder chamber is provided, and is supplied to the cylinder chamber at the beginning of the energization of the coil. Linear actuator rod for downward movement with compressed air is to accelerate the downward movement presses the shaft, characterized in that. 2. A shaft for mounting a working device, and an electromagnetic servo drive unit for moving the shaft up and down, and a servo controller controls energization of a coil of the electromagnetic servo drive unit to move the shaft to a predetermined position. A double-acting air having a direct-current servomotor for stopping the piston; a piston moving vertically in the cylinder and its rod, and supplying and discharging compressed air to and from a pair of cylinder chambers defined by the piston. A linear actuator comprising a cylinder, wherein the rod and the shaft are arranged on the same axis and vertically and installed in a case, wherein the rod and the shaft are connected so as to be integrally movable in the axial direction, and Connect the proportional solenoid type pressure control valves that output air pressure proportional to the amount of electricity to the solenoid to the cylinder chamber, respectively. A compressed air supply means that is operated by applying a current to lower the shaft to the coil, and adjusts the air pressure supplied to and discharged from the pair of cylinder chambers by controlling the amount of electricity supplied to the solenoid; Pressing the shaft with the rod moving down by the supply of compressed air to the cylinder chamber accelerates the downward movement, and moving the shaft at the lower position with the rod moving up by the supply of compressed air to the lower cylinder chamber. A linear actuator characterized by lifting. 3. A shaft for mounting work equipment, and an electromagnetic servo drive unit for moving the shaft up and down, and a servo controller controls energization of a coil of the electromagnetic servo drive unit to move the shaft to a predetermined position. A double-acting air having a direct-current servomotor for stopping the piston; a piston moving vertically in the cylinder and its rod, and supplying and discharging compressed air to and from a pair of cylinder chambers defined by the piston. A linear actuator comprising a cylinder, wherein the rod and the shaft are disposed vertically on the same axis and installed in a case, wherein the rod and the shaft are engaged with each other by upward movement of the rod. The servo controller is connected to the servo controller so that the shaft can be moved downward by the coil. Compressed air supply means for supplying and discharging compressed air to a pair of cylinder chambers operated by electricity, and presses down the shaft with a rod that moves down by the supply of compressed air to the upper cylinder chamber to accelerate the downward movement A linear actuator characterized in that the engagement portion is engaged with a rod that moves upward by supply of compressed air to a lower cylinder chamber, and the shaft at the lower movement position is pulled up. 4. The air cylinder according to claim 1, wherein the sliding portion of the air cylinder is supported in a floating state by an air bearing.
A linear actuator according to claim 3.