JPH09100889A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an actuator capable of surely connected to a load, by providing a pair of long holes, facingly with each other, into which, together with a connecting hole, a connecting pin is inserted, and being long in a tube core direction; on a movable tube. SOLUTION: When a connecting tool 24 is rotatably operated to a movable tube 22, while a tool is engaged with a tool engaging part 28; since the connecting tool 24 is forwarded/retreated in a tube core direction by the action of position adjusting female and male screw parts 25 and 27, the position of the connecting part 24, in a tube core direction to the movable tube 22, can be freely adjusted. By this position adjusting, the position of the connecting hole 29 of the connecting tool 24 is matched to the position of the connecting hole 32 of a bracket 31, and then a connecting pin 30 is inserted into the long holes 26 of the movable tube 22, the connecting hole 29 of the connecting tool 24, and the connecting hole 32 of the bracket 31, to stop the falling of the connecting pin 30 by a split pin 33. By this insertion of the connecting pin 30, a condition is formed, wherein the connecting pin 30 is engaged with both the long holes 26, 26 of the movable tube 22, thereby the connecting tool 24 becomes a condition, wherein it is whirl-stopped to the movable tube 22 to be prevented from loosely moving in an axis direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator, and more particularly to an electric feed screw type actuator, which is effective for use in, for example, linearly reciprocating a heavy load.

[0002]

2. Description of the Related Art Conventionally, in an electric feed screw type actuator used for lifting and lowering a load, a connector having a pin insertion hole at a tip portion of a moving barrel which is linearly reciprocated by driving a motor. Is fixedly attached, and the connector fixed to the tip of the moving cylinder is aligned with the load bracket, the pin is inserted into the pin insertion hole of the connector and the bracket A lead screw actuator is configured to be coupled to the load. Note that, as a document describing an electric feed screw type actuator equipped with such a connecting tool, there is, for example, Japanese Patent Application Laid-Open No. 6-109094.

[0003]

However, in the above-mentioned conventional actuator, since the connecting member is fixed to the movable barrel, the position of the connecting member of the actuator with respect to the bracket of the load is small when connecting the actuator to the load. However, if they are misaligned, the connecting pin cannot be inserted into the pin insertion hole of the connecting tool and the bracket, and the actuator cannot be connected to the load.

An object of the present invention is to provide an actuator that can be reliably connected to a load.

[0005]

An actuator according to the present invention is an actuator in which a movable barrel which is linearly reciprocated by a motor is coupled to a load by a coupling tool, and the coupling tool is provided at a tip end of the movable barrel in a cylinder center direction. The position of the connector is screwed so that the connecting pin has a connecting hole for inserting the connecting pin. The long holes of are opened facing each other.

[0006]

[Operation] When connecting the actuator to the load,
When the position of the pin insertion hole of the connector of the actuator with respect to the pin insertion hole on the load side is deviated, the connector is rotated with respect to the moving barrel to rotate the axis of the pin insertion hole of the connector with respect to the moving barrel. The axial position is adjusted. With this position adjustment, the pin insertion hole of the connector and the pin insertion hole on the load side are aligned, and the connection pin is inserted into the elongated hole of the movable barrel, the pin insertion hole of the connection device, and the pin insertion hole on the load side. To be done. Since the connecting pin is inserted into both the long holes of the movable barrel while being inserted into the connector and the pin insertion hole on the load side, the connecting pin is in a state of being prevented from rotating by the connecting pin to the movable barrel. As a result, the connecting tool is prevented from moving in the axial direction of the movable barrel, and the mounting position of the movable barrel with respect to the load is maintained.

[0007]

1 is a vertical sectional view showing an actuator according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing a main part thereof with a part cut and a part omitted. FIG. 3 is an explanatory diagram for explaining the operation of the connecting tool. FIG. 4 is an explanatory diagram for explaining the position adjusting action of the position regulating member.

In this embodiment, the actuator according to the present invention is configured as a general-purpose actuator mounted on various loads. Since the actuator 1 has versatility, there is a possibility that the connecting position may change with respect to the load of the connecting tool. The actuator 1 according to the present embodiment includes a housing 2, a motor mounting portion 3 in which a forward / reverse rotatable motor 12 is mounted is provided in the housing 2, and the shaft 1 as a feed screw shaft is provided.
The shaft insertion portion 4 through which the shaft 5 is inserted is opened. A worm gear speed reducer 13 is connected to the output shaft side of the motor 12. Output shaft 14 of worm gear speed reducer 13
Extend in a direction orthogonal to the axis of the shaft insertion portion 4.

The housing 2 has a pair of left and right shells 5, 5
It is configured by combining. Both shells 5 and 5 are made of resin and are formed in a substantially rectangular dish shape that is symmetrical with respect to each other. The motor mounting portion 3 and the shaft insertion portion 4 are formed on the mating surfaces that are aligned in the middle. ing. Both shells 5 and 5 are fastened together by a screw member (not shown) in a state where they are assembled in the middle, and are formed outside one end (hereinafter referred to as front end) opening of the shaft insertion portion 4. A metal band 7 is fitted around the fitting portion 6. The band 7 prevents the left and right shells 5, 5 from opening in the shaft insertion portion 4 in the left-right direction. Further, an assembling hole 8 for assembling the actuator 1 to a load is recessed in the side surface of one shell 5. By inserting the support shaft 9 from the side, the assembling hole 8 can support the actuator 1 rotatably around the support shaft 9.

A male screw portion 16 for feeding is formed on the front side of the shaft 15 inserted through the shaft insertion portion 4 of the housing 2. A nut 18 is mounted to be able to move forward and backward. In addition, the shaft insertion portion 4 of the housing 2
The support cylinder 19 has a shaft 1 on the outside of the nut 18.
5 are arranged concentrically with each other, are sandwiched by the left and right shells 5, 5, and are prevented from coming off by the fixing portion 20. The nut 18 is fitted in the support cylinder 19 so as to be slidable in the cylinder center direction.

A movable cylinder 22 is attached to the shaft 15 of the nut 18.
Also, the connector 24 is arranged concentrically with the support cylinder 19 and is connected by a screw coupling portion 23, and a connecting tool 24 for connecting the actuator 1 to a load (not shown) is provided at the front end of the moving cylinder 22.
Is mounted so that the connection position with respect to the load can be adjusted. That is, the position adjusting female screw portion 25 is engraved on the inner periphery of the front end portion of the moving barrel 22, and a pair of elongated holes 26 extending in the cylinder center direction are provided at the center position of the position adjusting female screw portion 25 in the axial center direction. , Are provided so as to face each other and extend in the cylinder center direction. The connecting tool 24 is the moving tube 22.
Is formed in a cylindrical shape having an outer diameter substantially equal to, and a position adjusting male screw portion 27 is engraved on the circumference. Connector 24
A tool engaging portion 28 for engaging a tool such as a spanner is chamfered and integrally formed at one end of the connector 24, and a connecting hole for inserting a connecting pin at the other end of the connector 24. 29
Is pierced in the direction orthogonal to the axis and opened.

The connecting member 24 is mounted on the front end of the movable cylinder 22 so that the position in the axial direction can be adjusted by screwing the position adjusting male screw portion 27 into the position adjusting female screw portion 25. At the same time, by adjusting the rotational position, the connecting hole 29 is aligned with both the long holes 26. The outer diameter of the connecting hole 29 and the widths of both the long holes 26, 26 in the lateral direction are set to be equal to each other, and are set to be substantially equal to the outer diameter of the connecting pin 30. The connecting pin 30 is set to be insertable into the elongated hole 26 and the connecting hole 29, and is also set to be insertable into the connecting hole 32 formed in the bracket 31 on the load side. On the outside of 31, the collar portion 30 a and the split pin 33 are configured to be prevented from coming off.

When the connecting member 24 is connected to the load, the nut 18 and the moving cylinder 22 are prevented from rotating with respect to the supporting cylinder 19. The rotation of the nut 18 is stopped, and the nut 18 moves linearly with respect to the support cylinder 19 as the nut 18 advances and retreats.

A cylindrical nut stopper 35 is coaxially arranged and fixed to the front end of the shaft 15, and the nut stopper 35 is slidably supported on the inner peripheral surface of the moving shaft 22. ing. A position regulating member 36, which also functions as a damper, is fixed to the inner periphery of the front end portion of the movable barrel 22 near the rear end from the position adjusting female screw portion 25 so that the position can be adjusted. That is, the position regulating member 36 is made of an elastic material such as rubber or resin and is formed in a columnar shape having an outer diameter equal to the inner diameter of the moving barrel 22. An insertion hole 37 for inserting a rivet is formed in the rear end portion of the position regulating member 36 in a direction orthogonal to the axis. Further, a concave portion 38 for escaping the convex portion of the shaft 15 protruding from the nut stopper 35 is recessed in the rear end surface of the position regulating member 36. On the other hand, an insertion hole 39 for inserting a rivet is formed at a position appropriately separated from the position adjusting female screw portion 25 at the front end portion of the support cylinder 22 so as to penetrate in a direction orthogonal to the cylinder center.

Then, with the connecting tool 24 removed and the insertion holes 37 and 39 aligned with a mounting jig (not shown), the position regulating member 36 is inserted into the movable cylinder 22. The insertion holes 37 and 3 are inserted through the front end opening.
The rivet 40 is inserted through the rivet 9 and is caulked, so that the movable barrel 22 is fixed to the desired adjustment position shown in FIG. In FIG. 4, L is an assembly span, S
Is the stroke of the actuator, and B is the position regulating member 3 corresponding to the dimensional difference between the assembly span L and the stroke S.
6 is a position adjustment dimension.

A cylindrical cap 41 having an inward flange at the front and rear ends is fitted to the front end of the support cylinder 19. It is engaged with the groove and fixed to the support cylinder 19. The cap 41 seals the inside of the support cylinder 19 by slidingly contacting the inner circumference of the flange portion on the front end side with the outer circumference of the moving cylinder 22.

A circular ring-shaped front partition part 4 is provided substantially at the center of the shaft insertion part 4 of the housing 2 in the axial direction.
2 is provided so as to project inward in the radial direction.
The step end surface of the male screw portion 16 of the shaft 15 is inserted and abutted in the recess 42a that is recessed in the front end surface of the shaft 2. An accommodation chamber 43 for accommodating a brake plate and the like is formed in a circular hollow chamber having a diameter slightly larger than that of the support cylinder 19 behind the front partition 42 of the shaft insertion portion 4.
That is, a brake plate, a one-way clutch, a thrust bearing, a stopper and a spacer are arranged in this order from the front end side in the accommodation chamber 43, and the components thereof are the accommodation chamber 4
It is fitted on the outer periphery of the controlled shaft portion 44 of the shaft 15 inserted through the shaft 3.

The brake plate 45 is formed in a circular ring shape using a resin such as nylon, and is loosely fitted to the front end of the outer periphery of the controlled shaft portion 44. The brake plate 45 is prevented from rotating on the shaft insertion portion 4 by a concavo-convex joint portion 46 formed between the front end surface of the brake plate 45 and the rear end surface of the partition wall portion 42. A roller type one-way clutch 48 is mounted on the outer periphery of the controlled shaft portion 44 of the shaft 15 at the rear side of the brake plate 45.

Although a detailed description and illustration are omitted, the one-way clutch 48 of the roller type has a clutch case (hereinafter referred to as a case) 48a formed in a cylindrical shape.
A wedge-shaped groove 48b recessed in the inner peripheral surface of the case 48a
And a roller 48c rotatably housed in the wedge-shaped groove 48b and rotatably contacting the outer peripheral surface of the controlled shaft portion 44.
The roller 48c displaces the case 48a in the wedge-shaped groove 48b toward the large diameter side to allow idling of the case 48a with respect to the shaft 15, and when the shaft 15 is reversed, the roller 48c displaces in the wedge-shaped groove 48b toward the large diameter side. The case 48 a is configured to rotate integrally with the shaft 15 by exerting a wedge effect.

Further, the front end face of the one-way clutch 48 is pressed against the rear end face of the adjacent brake plate 45 on the front side. A grease reservoir groove 47 is recessed in a square annular groove shape on the pressing surface of the brake plate 45 with the one-way clutch 48, and grease (not shown) is applied between the pressing surfaces. . Grease reservoir groove 4
Since 7 is formed in the shape of a square annular groove, the grease applied between the pressing surfaces of the brake plate 45 and the one-way clutch 48 is evenly spread over the entire surface. The frictional force between the pressing surfaces of the brake plate 45 and the one-way clutch 48 is larger than the reverse rotation acting force on the shaft 15 from the load side, and the difference between them is the reverse rotation driving force from the motor side. It is set to be smaller than. That is, when the one-way clutch 48 is reversely rotated by the driving force of the motor 12, slippage occurs between the pressing surfaces of the brake plate 45 and the one-way clutch 48, while the one-way clutch 48 drives the nut 18 side. It is set so that slip does not occur between the pressing surfaces when the force is reversed by force.

A thrust rolling bearing 49 is fitted at a position adjacent to the outer periphery of the controlled shaft portion 44 of the shaft 15 behind the one-way clutch 48, and the thrust rolling bearing 49 is positioned adjacent to the rear of the one-way clutch 48. The movement in the axial direction is restricted by the stopper 50 fitted to the shaft.

A radial rolling bearing 53 is fixed adjacent to a rear side of the rear partition wall 52, which is adjacent to the rear side of the storage chamber 43 in the shaft insertion portion 4, opposite to the storage chamber 43. Shaft 1 by radial rolling bearing 53
The rear end portion of 5 is rotatably supported. Shaft 15
Rear partition 5 of the radial rolling bearing 53 on the outer periphery of the
At the position opposite to 2, the driven bevel gear 55 has the washer 5
4 are sandwiched and fitted, and one of them is taken and joined so as to rotate integrally.

A driven-side bevel gear 56 is meshed with the driven-side bevel gear 55. The driven-side bevel gear 56 is an output shaft of the worm gear reduction device 13 disposed in the housing 2 so as to be orthogonal to the shaft insertion portion 4. 14 so as to rotate integrally therewith. That is, the rotational driving force of the motor 12 installed in the motor mounting portion 3 of the housing 2 is transmitted to the driven bevel gear 55 via the output shaft 14 of the worm gear speed reducer 13 and the driving bevel gear 56. Has become
Therefore, the shaft 15 is driven to rotate forward and backward by the motor 12.

Next, the operation will be described. In advance, the actuator 1 is installed between the fixed end and the free end of the load. For example, the housing 2 of the actuator 1 is rotatably supported by the support shaft 9 inserted into the assembly hole 8 being pivotally supported at the fixed end of the load, and the movable cylinder 22 of the actuator 1 is supported at the free end of the load. Bracket 3 to connector 24
When the connecting pin 30 inserted in 1 is inserted, it is rotatably supported.

After the actuator 1 is thus installed between the fixed end and the free end of the load, for example, as shown in FIG.
When the motor 12 is driven to rotate in the forward direction from the above state, the driving force of the motor 12 passes through the worm gear speed reducer 13, the driving-side bevel gear 56, and the driven-side bevel gear 55, and the shaft 1
5 is transmitted. Since the roller 48c of the one-way clutch 48 does not engage with the wedge-shaped groove 48b during normal rotation of the shaft 15, the clutch case 48a idles with respect to the shaft 15 and the shaft 15 relatively rotates as it is. When the shaft 15 is normally rotated by the motor 12, the nut 18 is advanced along the support cylinder 19, so that the movable cylinder 22 connected to the nut 18 is pushed out of the support cylinder 19. The forward movement of the movable barrel 22 drives the load connected to the connector 24 of the movable barrel 22.

When the movable cylinder 22 extends by a predetermined stroke required by the load, the motor 12 is driven by an automatic stop device or the like provided in a drive electric circuit (not shown) of the motor 12.
The operation of is automatically stopped.

When the operation of the motor 12 is stopped, the load acts on the nut 18 via the moving cylinder 22 as a force for retracting the nut 18 (or a pulling force when the load acts as a tensile load on the actuator). Therefore, a force for rotating the shaft 15 in the reverse direction (hereinafter, referred to as a load side reverse rotation acting force) is in a state of being acted by the action of the female screw portion 17 of the nut 18 and the feed male screw portion 16 of the shaft 15. . When the load-side reverse rotation acting force acts on the shaft 15, the roller 48c of the one-way clutch 48 is engaged with the wedge-shaped groove 48b, so that the shaft 15 and the case 48a of the one-way clutch 48 are integrally rotated. . However, the case 48a of the one-way clutch 48 is pressed against the brake plate 45,
Since the brake plate 45 is fixed to the housing 2, it cannot rotate. In this case, the case 48a of the one-way clutch 48 is stopped by the friction force acting on the brake plate 45 between the pressing surfaces of the two. As a result, the shaft 15 that is about to rotate integrally with the case 48a of the one-way clutch 48 cannot rotate. That is,
Since the shaft 15 is fixed to the housing 2 via the one-way clutch 48, the reverse rotation is prevented against the reverse rotation acting force from the load side. Therefore, the load can be kept driven by the actuator 1.

Thereafter, when the motor 12 is rotated in the reverse direction, the reverse rotation driving force of the motor 12 is transmitted to the shaft 15 via the worm gear speed reducer 13, the driving side bevel gear 56, and the driven side bevel gear 55. It When the shaft 15 rotates in the reverse direction, the roller 48c of the one-way clutch 48 engages with the wedge-shaped groove 48b, so that the shaft 15 and the case 48a of the one-way clutch 48 rotate together. And the case 48 of the one-way clutch 48
Since a is pressed against the brake plate 45, and the brake plate 45 is fixed to the housing 2, it cannot rotate. However, the reverse rotation driving force and the load side reverse rotation acting force from the motor side for forcibly rotating the shaft 15 in the reverse direction by the driving force of the motor 12 are generated between the case 48 a of the one-way clutch 48 and the brake plate 45. Since the anti-rotation force due to the frictional force acting between the pressing surfaces exceeds the case 48a of the one-way clutch 48,
It will be in a state of slipping between and. As a result, the shaft 15 can rotate in the reverse direction together with the case 48a of the one-way clutch 48.

When the shaft 15 is driven in the reverse rotation in this manner, the nut 18 screwed forwardly and backwardly into the male screw portion 16 and prevented from rotating by the support cylinder 19 is retracted along the support cylinder 19. Therefore, the movable cylinder 22 connected to the nut 18 is drawn into the support cylinder 19. By the backward movement of the moving barrel 22, the load connected to the connecting tool 24 of the moving barrel 22 is moved back.

When the load is returned to its original position, the motor 12 is automatically stopped. In the state where the nut 18 returns to the original retracted position, the load is normally mechanically supported by the support tool (not shown), and therefore the reverse rotational force from the load side is not applied to the shaft 15. .
However, even if a reverse rotation acting force is applied to the shaft 15 from the load side in the state of returning to the retracted position, the reverse rotation of the shaft 15 is reliably prevented by the above-described operation. The reverse rotation preventing effect is similarly exhibited even when the nut 18 is stopped in the middle of the male screw portion 16.

The actuator according to this embodiment is constructed so as to be suitable for use when the load acts as a tensile load. In the actuator used when the load acts as a compressive load, the direction of the male screw part for feeding the shaft is opposite to that of the tensile load,
The layout of the one-way clutch, brake plate, etc. is reversed.

By the way, when the actuator 1 is assembled to a load (not shown), for example, as shown in FIG.
When the position of the connector 24 with respect to the connecting hole 32 of the bracket 31 is displaced by the interval E as shown in FIG. It cannot be connected to the bracket 31.

In this embodiment, since the connecting tool 24 is mounted on the movable barrel 22 so that its position can be adjusted,
Even in such a case, the connector 24 is attached to the bracket 31.
Can be connected. That is, in the state where the connecting pin 30 is pulled out from the long hole 26 of the moving barrel 22 and the connecting hole 29 of the connecting tool 24, the connecting tool 24 is moved to the tool engaging portion 2.
When a tool (not shown) is engaged with 8 and is rotated with respect to the moving barrel 22, the connector 24 is moved to the position adjusting female screw portion 2
5 and the position adjusting male screw portion 27 move forward and backward in the direction of the cylinder center, as shown in FIG.
The position of the connector 24 in the axial direction with respect to the moving barrel 22 can be freely adjusted. By this position adjustment, the position of the connecting hole 29 of the connecting tool 24 is changed to the connecting hole 3 of the bracket 31.
After being aligned at the position of 2, the connecting pin 30 is inserted into the long hole 26 of the movable barrel 22, the connecting hole 29 of the connecting tool 24, and the connecting hole 32 of the bracket 31, as shown in FIG. 3C. Then, the connecting pin 30 is prevented from coming off by the split pin 33. By inserting the connecting pin 30, the connecting pin 3
Since 0 is in a state of being engaged with both elongated holes 26, 26 of the moving barrel 22, the connecting tool 24 is in a state of being prevented from rotating with respect to the moving barrel 22, and the connecting tool 24 is then moved in the axial direction. Doing so has been blocked.

As described above, according to this embodiment,
Since the connector 24 is attached to the movable barrel 22 so that its position can be adjusted, an error in the connection position between the connector 24 and the load bracket 31 can be absorbed.
The actuator 1 can be assembled to a load having an arbitrary assembly span, and as a result, the versatility of the actuator 1 can be enhanced. Further, since the error in the connecting position between the connecting tool 24 and the load bracket 31 is absorbed by the position of the connecting tool 24 in the direction of the cylinder center with respect to the moving cylinder 22, it is not necessary to lose the effective stroke of the actuator 1 and the actuator The performance can be fully utilized.

[0035]

As described above, according to the present invention,
Since the position of the connecting tool is adjustable with respect to the moving cylinder, the error in the connecting position with the load of the connecting tool can be absorbed. Therefore, the actuator is mounted on the load having an arbitrary assembly span. And as a result,
The versatility of the actuator can be improved. Also,
Since the error of the connecting position with the load of the connecting tool is absorbed by the position of the connecting tool in the direction of the cylinder center with respect to the moving tube, the effective stroke of the actuator is not lost and the performance of the actuator can be fully utilized. .

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing an actuator according to an embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a main part thereof with some parts cut away and some parts omitted.

FIG. 3 is an explanatory diagram for explaining the operation of the connecting tool.

FIG. 4 is an explanatory diagram for explaining a position adjusting action of a position regulating member.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Actuator, 2 ... Housing, 3 ... Motor mounting part, 4 ... Shaft insertion part, 5 ... Shell, 6 ... Fitting part, 7
... band, 8 ... assembly hole, 9 ... support shaft, 12 ... motor, 1
3 ... Worm gear speed reducer, 14 ... Output shaft, 15 ... Shaft, 16 ... Male screw part for feeding, 17 ... Female screw part, 18 ...
Feed nut, 19 ... Support tube, 20 ... Fixed section, 22 ... Moving tube, 23 ... Screw coupling section, 24 ... Coupling tool, 25 ... Position adjusting female thread section, 26 ... Long hole, 27 ... Position adjusting male thread section , 28 ... Tool engaging part, 29 ... Connection hole, 30 ... Connection pin, 31 ... Bracket, 32 ... Connection hole, 33 ... Split pin,
35 ... Nut stopper, 36 ... Position regulation member, 37 ... Insertion hole, 38 ... Recessed portion, 39 ... Insertion hole, 40 ... Rivet, 4
DESCRIPTION OF SYMBOLS 1 ... Cap, 42 ... Front partition part, 43 ... Storage chamber, 44
... Controlled shaft portion, 45 ... Brake plate, 46 ... Concavo-convex coupling portion, 47 ... Grease reservoir groove, 48 ... One-way clutch, 49 ... Thrust rolling bearing, 50 ... Stopper, 52
... rear partition wall portion, 53 ... radial rolling bearing, 54 ... washer, 55 ... driven bevel gear, 56 ... driving bevel gear.

Claims (1)

[Claims] 1. A shaft, which is rotatably supported by being inserted into a shaft insertion portion of a housing, is configured to be driven to rotate forward and backward by a motor, and a male screw portion formed on the outer periphery of the shaft has a shaft. In an actuator in which a female screw member connected to a moving barrel that moves in the axial direction is screwed so as to be able to move forward and backward, a connecting tool is screwed into the distal end of the moving barrel so that the position in the axial direction of the barrel can be adjusted. A connecting hole through which the connecting pin is inserted is formed in the connecting member, and a pair of long holes extending in the cylinder center direction through which the connecting pin is inserted together with the connecting hole are formed in the moving cylinder so as to face each other. An actuator characterized in that