JPH10220420A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator for controlling the operation of a missile launcher, having a multi-stage control function as well as a transmission function for each stage control. SOLUTION: Regarding an actuator formed out of a cylinder 20 and a piston 30 for operating a missile launcher, a cylinder 20 has a large diameter part 21 and a small diameter part 22 jointed to each other in a lengthwise direction. Also, a projection 24 extending along a lengthwise direction is formed on cylinder internal surface. The piston 30 is formed out of a piston body 31 sealed and coupled to the cylinder 20 and a piston rod 32, and has a recess 20a extending in a lengthwise direction. Furthermore, the projection 24 is slidably sealed in and coupled to the recess 20a, and a free cylinder 50 with lengthwise large and small outer diameter parts 51 and 52 is slidably sealed in and coupled to the jointed part of the large and small diameter parts 21 and 22 of the cylinder 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator comprising a cylinder and a piston housed in the cylinder so as to be movable in its longitudinal direction, and having fluid chambers formed on both sides of the piston. More specifically, the present invention relates to an actuator suitable for operating a missile launcher, which can hold a piston in a fixed position and change a moving speed during the stroke of the piston.

[0002]

2. Description of the Related Art An actuator which is mounted on an aircraft and operates a missile launcher for firing a missile from the aircraft will be described as an example.

In general, an actuator for operating an aircraft missile launcher arbitrarily operates a plurality of positions such as a storage position in an aircraft or in the vicinity of an airframe, a storage position and another standby position. That is, normally, such an actuator for a missile launcher needs to be operated slowly until the “storage position → standby position”, and instantly to push the missile until the “standby position → launch position”. .

Further, it is necessary to wait at a standby position until a missile is fired. For this purpose, it is necessary to hold the output piston at the third position where the contracted position is in the middle of the stroke to the extended position.

In order to realize such an operation, conventionally, a combination of a single-stage actuating actuator which moves between a contracted position and an extended position at a constant speed and injection by gunpowder, or servo control of the actuator is used. is there.

[0006]

However, in the former method in which the explosive is used in combination with the explosive, there are problems in terms of maintainability and safety, such as the time required for loading the explosive and the danger of explosion.

[0007] On the other hand, the latter, in which the actuator is servo-controlled, has a problem in cost due to a proportional control valve, a stepless position detector, and the like for making a hydraulic servo.

[0008] In addition, the missile launcher, by its nature,
The transition from the standby state to the firing state needs to be performed promptly, and the operating speed of the piston at a specific position is high, so that a large amount of hydraulic oil needs to be supplied instantaneously. When an actuator is designed with this large flow rate, valves and passages (piping)
Etc. became very large, and there were problems in cost and weight. This problem also affected the size of the working fluid supply source on the fuselage side.

As a countermeasure, there is a case where an accumulator is provided outside the actuator in order to compensate for a shortage of the working fluid supply capacity. However, when the accumulator ruptures for some reason (for example, impact), there is a risk that the fragments are scattered and the aircraft is damaged.

[0010] As described above, adding explosives to the actuator or making it servo-driven has problems in terms of maintainability, safety, and cost.

In addition, in the conventional actuator, when the self-weight addition or the like is applied when the supply of the fluid pressure is stopped or when the pressure supply source fails, the piston starts to move because it has no drag, and the missile launcher is stopped while the vehicle is parked. There is a problem that it comes out by its own weight. As a countermeasure, there is a method of providing a lock mechanism on the actuator, but the structure is complicated and there is a problem in cost.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an actuator having at least one of the following functions while solving the problems associated with the above-mentioned prior art.

(1) Multi-stage control function (2) Shift function for each stage control of multi-stage control function (3) Built-in accumulator (protection function) (4) Function to suppress flow rate of working fluid (5) Piston when hydraulic pressure is OFF Restraint function

[0014]

According to the present invention, there is provided an actuator comprising a cylinder and a piston housed in the cylinder so as to be movable in a longitudinal direction thereof, wherein a fluid chamber is formed on both sides of the piston. Has a large-diameter portion and a small-diameter portion connected in the longitudinal direction, and a protruding portion extending in the longitudinal direction of the cylinder protrudes from the end face on the small-diameter portion side into the cylinder. A recess formed of a piston body slidably and sealingly fitted to the inner diameter portion and a piston rod protruding from the piston body and extending in a longitudinal direction from an end face located on the small inner diameter side of the cylinder is formed. The cylinder has a large and small outside diameter portion in the longitudinal direction at a connecting portion of the large and small inside diameter portions of the cylinder, which is slidably and sealingly fitted to the protrusion. Cylinder to achieve the actuator by the object, characterized in that a can communicate with the discharge passage of the intermediate portion of the large and small outer diameter portion of the free cylinder with fitted slidably sealed to the cylinder.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, an accumulator having a gas chamber and a hydraulic chamber may be provided in communication with a pipeline for supplying a working fluid to a fluid chamber of a cylinder. By providing the (accumulator) and storing the working fluid in this accumulator in advance, it is possible to smoothly supply a large flow of the working fluid at the time of high-speed operation of the piston and to move the piston at high speed when necessary. it can.

In this case, the protruding portion of the cylinder is formed in a cylindrical shape, and a piston defining a gas chamber and a hydraulic pressure chamber of the accumulator is slidably and sealingly fitted in the cylindrical portion. Is also good. By doing so, the required pressurized working fluid can be stored inside the actuator, and the accumulator can be prevented from being damaged by an unexpected force acting from outside the actuator, which is preferable.

Further, in the present invention, an accumulator having a gas chamber and a hydraulic chamber may be provided in communication with a pipe for discharging the working fluid from the fluid chamber of the cylinder, and the working fluid from the fluid chamber may be provided. When the pressure exceeds a certain level, the working fluid is temporarily stored, so that a large amount of working fluid can be discharged smoothly when the piston operates at high speed, and the piston can be moved at high speed when necessary. it can.

In the actuator of the present invention, it is preferable that both the fluid chambers are connected to a three-position switching valve, and the operation of the actuator is controlled by operating the three-position switching valve. In addition, since a pilot check valve that closes when the pressure in the fluid chamber is low is provided in a pipe connected to the fluid chamber on the large inner diameter side of the cylinder of the actuator, the pressure Can be stored, and even when the supply of the pressurized fluid is stopped, the pilot check valve eliminates leakage of the fluid, and the piston rod can be held in that state.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 3 shows a structure of a missile launcher operated by the actuator according to the present invention.

The missile launcher is provided on the body 1 such as the body or wing of an airplane (fighter), and the launcher base 2 can be moved up and down from the body 1 by the structure described below. Missile 3 on launcher stand 2
Is installed so that it can be fired.

In the steady state, the launcher base 2 is located at the storage position of the body 1. When the missile 3 is to be fired, the launcher base 2 is projected from the storage position to a standby position below and stands by in this state. Further, when actually firing the missile 3, it moves to a firing position further below the standby position, and fires the missile 3 there.

In order to reduce the effect on the airframe 1 when the missile 3 is fired and to increase the accuracy of the missile 3, it is necessary to move the missile 3 to the firing position which is farther from the storage position. In such a missile launcher,
The movement from the storage position to the standby position has a relatively long time, but the movement from the standby position to the firing position needs to be performed in a very short time.

FIG. 4 shows an example of the moving state of the missile launcher. 4, the horizontal axis represents the time axis, and the vertical axis represents the position of the launcher table 2.

In FIG. 4, normally, the missile 3 is the airframe 1
It is in a nearby storage position. When the need to fire the missile 3 arises as described above, the launcher table 2 moves from the storage position to the intermediate standby position at a relatively low speed (step 1 down mode).

When the missile 3 is fired, it is necessary to rapidly move from the standby position to the fired position in a very short time (step 2 down mode). Note that in FIG. 4, the vehicle is immediately moved from the standby position to the firing position (that is, the step 1 down mode and the step 2 down mode are directly connected). However, until the launch
In many cases, the launcher table 2 is held as it is at the standby position. It may also return from the standby position to the storage position without firing.

In the case of firing, the step 2 down mode from the standby position to the firing position needs to be moved within a short time of competing for a minute, that is, the step 1 which is the movement from the storage position to the standby position. It is necessary to move to the firing position much faster than in the down mode.

Then, after the firing is completed, there is no need to rush to the storage position, so it is sufficient to return slowly.

The structure of the missile launcher shown in FIG. 3 will be briefly described. The launcher base 2 and the body 1 are connected by two links L and M having the same length and provided in an intersecting manner. The midpoints of the two links L and M are connected to each other by a pin P so as to be pivotable with each other.

The body L side of one link L is swingably supported by a pin A with respect to a fixed point of the body 1, and the other end of the link L is swingably pin-coupled to the launcher base 2 by a pin B. ing.

The tip of the other link M is swingably connected to a pin D slidably provided in a guide (not shown) extending horizontally from the pin A of the machine body 1, The other end of the link M is swingably connected to the launcher base 2 by a pin C.

In the missile launcher device having the above-described configuration, by moving the pin D of the link L in the horizontal direction along the guide, the pin C at the other end of the link L is moved.
Moves along a line extending vertically from the pin A of the body 1. By this. The launcher base 2 pin-coupled to the pins B and C always moves up and down in parallel with the body 1.

The cylinder-side rear end of the actuator 10 according to the present invention is pivotally connected to the body 1 by a pin F and the tip of a piston rod is connected to a link M by a pin E. The opening / closing angle between them is controlled so that the launcher table 2 is moved up and down.

Next, an actuator 10 according to the present invention will be described with reference to FIG. The actuator 10 includes a cylinder 20 and a piston 30 housed in the cylinder 20 so as to be movable in the longitudinal direction. Fluid chambers a and b are formed on both sides of the piston 30. As mentioned above,
The right end of the cylinder 20 is pin-connected to the body 1 by a pin F. The piston 30 includes a piston body 31 and a piston rod 32 connected to the piston body 31. The tip of the piston rod 32 is pin-connected to the link M by the pin E as described above.

In FIG. 1, the cylinder 20 is composed of a large-diameter portion 21 having a large diameter and a small-diameter portion 22 having a small diameter, and an intermediate portion between the large- and small-diameter portions 21 and 22 is connected while forming a step 23. It has become.

A protrusion 24 projects from the right end of the cylinder 20 into the cylinder 20. On the other hand, the piston body 31 is adapted to fit into the small-diameter portion 22 of the cylinder 20, and the space between the small-diameter portion 22 of the cylinder 20 and the peripheral surface of the piston body 31 is sealed by an O-ring 41. 31 is slidable with respect to the small diameter portion 22. A recess 20 a is formed in the piston 20 and extends partway from the right end.
a is adapted to fit with the protrusion 24 of the cylinder 20. Projection 24 of cylinder 20 and recess 20 of piston
Also, an O-ring 42 is mounted between the protruding portion 24a and the piston 30a, so that the piston 30 and the protruding portion 24 are fitted slidably in a sealed manner.

The left end of the piston rod 32 has an opening 2 formed in the end face 25 on the large inner diameter side of the cylinder 20.
5a is slidably and sealingly fitted via an O-ring 45.

The cylinder 2 is further provided inside the cylinder 20.
The free piston 50 fits between the large-diameter portion 21 and the small-diameter portion 22 at zero. The free piston 50 has a large outer diameter portion 51 fitted to the large diameter portion 21 and a small diameter portion 2 of the cylinder 20.
2 and a small outer diameter portion 52 to be fitted thereto is connected, and a step 53 is formed between the large and small outer diameter portions 51 and 52. O-rings 43 and 44 are respectively mounted between the large and small outer diameter portions 51 and 52 of the free piston 50 and the large and small diameter portions 21 and 22 of the cylinder, and the free piston 50 is slidably fitted to the cylinder 20 in a sealed manner. I agree.

The cylinder large diameter portion 21 of the cylinder 20
(A part of the fluid chamber a formed on the left side of the piston main body 31) communicates with the outlet port 60a of the three-position switching valve 60 via the check valve 70 and the pipeline 71. Also,
Fluid chamber b formed on the right side of piston body 31 of cylinder 20 (part of cylinder small diameter portion 21 of cylinder 20)
Communicates with the other outlet port 60b of the three-position switching valve 60 via the conduit 72. The input side port 60c of the three-position switching valve 60 communicates with a supply line 80 for supplying high-pressure fluid, and the discharge side port 60d communicates with a discharge line 85 for returning return fluid. In addition, a discharge path 86 communicates between the discharge pipe line 85 and an intermediate portion of the free piston 50.

A thermal relief valve 75 is provided between the above described pipe line 71 connected to the large diameter portion 21 of the cylinder 20 and the discharge line 86 connected to the intermediate portion of the free piston 50. When the pressure in the fluid chamber a becomes excessive due to heat, the pressure is released by the thermal relief valve 75 to prevent an accident.

The supply line 80 to the three-position switching valve 60 includes:
An accumulator 90 having a boundary between the gas and the working fluid is connected. A charge valve 91 and a pressure transducer 92 are provided on the gas side of the accumulator 90. When the supply working fluid is stored in the accumulator 90 in advance and necessary, It can be supplied.

The discharge line 8 from the three-position switching valve 60
An accumulator 95 having a boundary between gas and working fluid is connected to 5, and the discharged working fluid can be temporarily stored in the accumulator 95 by the pressure from the discharge pipe 85.

The operation of the embodiment of the actuator of the present invention having the above-mentioned structure and shown in FIG. 1 will be described below. The two # 1 and # 2 solenoids 6 of the three-position switching valve 60
Table 1 shows the relationship between ON / OFF of 1a and 61b and the operation state of the actuator.

[0043]

[Table 1] (Storage mode) # 1 solenoid 61 of three-position switching valve 60
a is OFF, # 2 solenoid 61b is ON or OFF
At this time, the three-position switching valve 60 is in the storage mode position shown in FIG. At this time, the high pressure port 60 of the three-position switching valve 60
a is the fluid chamber a of the actuator 10 and the low pressure port 60
b is connected to the fluid chamber b, and a contraction force of the piston determined by an area difference between the inner diameter B2 of the small diameter portion 22 of the cylinder 20 and the outer diameter d1 of the piston rod 32 acts on the piston, and the piston rod 32 contracts.

When the supply of the hydraulic pressure is cut off at the contracted position, the control pressure to the pilot check valve 70 is also cut off, and the check valve 70 seals the fluid chamber a and prevents the piston 30 from extending. And restrain the piston 30.

If the working fluid in the sealed fluid chamber a thermally expands and the pressure in the fluid chamber a rises excessively, the thermal relief valve 75 operates to release the working fluid in the fluid chamber a, and the cylinder 20 To prevent rupture.

(Step 1 down mode) The # 1 solenoid 61a of the three-position switching valve 60 is ON, and the # 2 solenoid 6
When 1b is turned off, the three-position switching valve 60 enters the step 1 down mode. At this time, the three-position switching valve 60
High pressure port 60a and both fluid chambers a and b are connected to each other, and the difference in pressure receiving area facing both fluid chambers a and b of the piston main body 31;
That is, the pressure receiving area of the piston body 31 facing the fluid chamber a is the difference between the inner diameter B2 of the small diameter portion 22 of the cylinder 20 and the outer diameter d1 of the piston rod 32, and the pressure receiving area of the piston body 31 facing the fluid chamber b is 20 is the difference between the inner diameter B2 of the small-diameter portion 22 and the outer diameter d2 of the protruding portion 24 of the cylinder 20, the piston pressure receiving area = (B2-d2)-(B2-d1) =
A force obtained by multiplying d1-d2 by the working fluid pressure acts on the piston body 31, and the piston 30 starts to move in the extension direction.

At this time, since the fluid chamber a is pressurized, the free piston 50 provided in the fluid chamber a has a difference in area between both end faces, that is, an inner diameter B1 of the large diameter portion 21 of the cylinder 20. The difference from the inner diameter B2 of the small diameter portion 22, that is, B1-
A force obtained by multiplying the pressure receiving area of B2 by the working fluid pressure acts, and the free piston 50 is pushed rightward in FIG.
The stopper is formed in the cylinder 20 by being pressed against the step portion 23 between the large and small inner diameter portions 21 and 22 of the cylinder 20.
In this case, the output of the free piston 50 for the stopper is larger than the output of the output piston 20 (that is, the output of the free piston 50 for the stopper).
B1-B2> d1-d2), the inner diameter B1 of the large diameter portion 21 and the inner diameter B2 of the small diameter portion 22, the outer diameter d1 of the piston rod 32, and the outer diameter d2 of the protrusion 24 of the cylinder 20 of the cylinder 20. Because each is selected,
When both pistons 20 and 50 hit each other, the output piston 20 stops. Thus, the actuator 10 can be held at the step 1 down position.

(Step 2 down mode) The # 1 and # 2 solenoids 61a and 61b of the three-position switching valve 60 are both ON.
, The high pressure port 60a and the fluid chamber b are connected, and the low pressure port 60b and the fluid chamber a are connected. Immediately after this, first, the restraining force of the free piston 50 in the fluid chamber a connected to the low-pressure port 60b is lost, and the high-pressure working fluid flows into the fluid chamber b to press the output piston 30. Elongates.

At this time, when the piston 30 is operated instantaneously, there is a limit in supply / discharge of the working fluid. For this reason, the high pressure supply side makes up for the shortage of the working fluid by simultaneously pushing out the working fluid accumulated in the accumulator 90 by the charge valve 91 and the pressure transducer 92.

The low pressure side temporarily accumulates a large amount of working fluid discharged instantaneously in the accumulator 95, and gradually discharges the working fluid after the operation of the output piston 30 is completed. In this way, the actuator 10 that can cope with the instantaneous large flow rate is established.

(Up Mode) Steps 1 and 2 described above
From any position, the # 1 solenoid 61a of the three-position switching valve 60 is turned off, and the # 2 solenoid 61b is turned on / O.
By switching to the FF, the piston can be switched to the storage mode, whereby the high-pressure port 60a of the three-position switching valve 60 is connected to the fluid chamber a of the actuator 10 and the low-pressure port 60b is connected to the fluid chamber b. The contraction force of the piston determined by the area difference between the inner diameter B2 of the portion 22 and the outer diameter d1 of the piston rod 32 acts on the piston,
The piston rod 32 contracts.

[0052]

Another embodiment In the embodiment of FIG. 1 described above, an accumulator 90 for supplying a large amount of pressurized fluid is provided outside the actuator 10, but in the embodiment shown in FIG. An air gap is provided between the part 24 and the piston rod 32 to form an accumulator similar to the accumulator 90 shown in FIG.

That is, in FIG. 2, the protruding portion 24 protruding from the right end face of the cylinder 20 is cylindrical, and the piston rod is provided outside the cylindrical protruding portion 24 in the same manner as in the above-described embodiment. 32 are slidably and sealingly fitted.

A piston 93 defining a gas chamber and a hydraulic chamber of the accumulator 90 is slidably and sealingly fitted through an O-ring 46 inside the cylindrical projection 24. The protrusion 24 is a concentric double cylinder, and a gas pressure supply path 94 extending in the longitudinal direction is formed between the two cylinders.

The chamber on the left side of the accumulator 90 piston 93 is a gas chamber g. The gas chamber g is a cylinder 20
The port 24b near the left end of the projection 24 is connected to a charge valve 91 and a pressure transducer 92 via a gas pressure supply path 94.

The right side of the piston 93 is a working fluid chamber p. The working fluid chamber p is provided with a port 24 a formed on the wall surface of the cylindrical upper projection 24 of the cylinder 20 and a pipe 87.
Through the supply line 80.

In the same manner as in the above-described embodiment, the actuator 1
0 is operated quickly, this accumulator 90
The working fluid stored in the working fluid chamber p is supplied to the working fluid chamber b of the actuator 10 so that the piston rod 32 of the actuator 10 can move quickly.

Reference numerals 6a and 6b in FIG. 2 denote switches composed of, for example, limit switches for checking the piston position.

Since the other structure of this embodiment is the same as that of the embodiment shown in FIG. 1, the same components are denoted by the same reference numerals and their description is omitted.

In the above description, the present invention is applied to the missile launcher actuator 10. However, the present invention is applicable to the hydraulic actuator 10 in general.
In particular, the control actuator 1 of the missile launcher described above
It is optimal as 0.

[0061]

As is apparent from the above description, the present invention has the following effects. (1) Multi-stage control of the actuator became possible. (2) It is possible to set the operation speed / output of the actuator for each control stage. (3) The working fluid can be suppressed instantaneously, so that the weight of the body and the weight of the actuator are reduced and the cost is reduced. (4) Malfunction due to its own weight when the supply of hydraulic pressure is stopped can be prevented.

Further, according to the embodiment of the present invention shown in FIG. 2, the following effects are also obtained. (5) Accumulator protection improves reliability /
The ballistic resistance is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an embodiment of the present invention.

FIG. 2 is a sectional view showing another specific embodiment of the present invention.

FIG. 3 is an operation explanatory view of a missile launcher using the actuator 10 according to the present invention.

FIG. 4 is a diagram showing the operation of the missile launcher shown in FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Airframe 2 Launcher stand 3 Missile 10 Actuator 20 Cylinder 20a Depression 21 Large diameter part 22 Small diameter part 23 Step 24 Projection part 30 Piston 31 Piston main body 32 Piston rod 50 Free piston 51 Large outside diameter part 52 Small outside diameter part 53 Step part 60 Three-position switching valve 60a Outlet port 60b Outlet port 60c Input side port 60d Discharge side port 61a # 1 solenoid 61b # 2 solenoid 70 Check valve 71 Pipe 72 Pipe 75 Thermal relief valve 80 Supply pipe 85 Discharge pipe 86 Discharge path 90 accumulator 91 charge valve 92 pressure transducer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takashi Nishina 3175 Showa-cho, Kanazawa-ku, Yokohama-shi, Kanagawa Japan Aircraft Co., Ltd.

Claims (7)

[Claims] 1. An actuator for operating a missile launcher, comprising a cylinder and a piston housed in the cylinder so as to be movable in a longitudinal direction thereof, and a fluid chamber is formed on both sides of the piston. The inner diameter portion and the small inner diameter portion are connected in the longitudinal direction, and a protrusion extending in the longitudinal direction of the cylinder projects from the end surface on the small inner diameter portion side into the cylinder, and the piston is a small inner diameter portion of the cylinder. A concave portion is formed which comprises a piston body slidably and sealingly fitted to the piston body and a piston rod protruding from the piston body and extends longitudinally from an end face located on the small inner diameter side of the cylinder. The cylinder has a large and small outer diameter portion in the longitudinal direction at a connecting portion between the large and small inner diameter portions of the cylinder. An actuator characterized in that a free cylinder is slidably and sealingly fitted to the cylinder and an intermediate portion of a large and small outer diameter portion of the free cylinder can communicate with a discharge path. 2. An actuator comprising a cylinder and a piston housed in the cylinder so as to be movable in a longitudinal direction thereof, wherein a fluid chamber is formed on both sides of the piston. Are connected in the longitudinal direction, and a protruding portion extending in the longitudinal direction of the cylinder protrudes from the end face on the side of the small inner diameter portion into the cylinder, and the piston is slidably and sealingly fitted to the small inner diameter portion of the cylinder. A recess formed of a mating piston body and a piston rod protruding from the piston body and extending in a longitudinal direction from an end face located on the small inner diameter side of the cylinder, and the recess is slidably sealed to the protrusion. A free cylinder that has a large and small outside diameter part in the longitudinal direction at the connection part of the large and small inside diameter part of the cylinder is slidable on this cylinder. An actuator, which is hermetically fitted and is capable of communicating an intermediate portion between the large and small outer diameter portions of the free cylinder with a discharge passage. 3. The actuator according to claim 1, wherein an accumulator having a gas chamber and a hydraulic chamber is provided in communication with a pipe for supplying a working fluid to a fluid chamber of the cylinder. . 4. A projecting portion of the cylinder is formed in a cylindrical shape, and a piston defining a gas chamber and a hydraulic chamber of the accumulator is slidably and sealingly fitted in the cylindrical portion. The actuator according to claim 3, characterized in that: 5. The actuator according to claim 1, wherein both fluid chambers of the cylinder are connected to a three-position switching valve. 6. The pilot check valve according to claim 1, wherein a pilot check valve that closes when the pressure in the fluid chamber is low is provided in a pipe connected to the fluid chamber on the large inner diameter side of the cylinder. An actuator according to any one of the preceding claims. 7. An accumulator having a gas chamber and a hydraulic chamber is provided in communication with a pipe for discharging a working fluid from a fluid chamber of the cylinder.
The actuator according to any one of claims 6 to 6.