JPH0749041Y2 - Fluid pressure continuously operated reciprocating actuator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a fluid pressure driven continuous operation type reciprocating actuator, and more particularly to an actuator for continuously reciprocating an output rod by receiving supply of pressurized air or hydraulic pressure. Regarding

[Prior Art] Conventionally, as a fluid pressure driven continuous operation type reciprocating actuator of this type, a spring return type single acting fluid pressure cylinder is incorporated in a housing, and a fluid pressure supply port and a discharge port are provided to a working chamber of the cylinder. Is selectively opened by the switching operation of the directional switching valve mechanism, and when the working chamber and the supply port are connected, the fluid pressure (usually compressed air) causes the piston and output rod to resist the return spring. When the piston is driven forward and the working chamber is communicated with the discharge port, the piston and the output rod are driven backward by the return spring, and the control fluid pressure flow passage is switched by the control valve mechanism linked to the piston to switch the directional valve. It is known that the mechanism is configured to be switched.

The applicant of the present application, as shown in Japanese Patent Publication No. 55-40761, puts into practical use a device that is small in size and light in weight, can be manufactured relatively inexpensively, and has excellent operational reliability and durability, while eliminating the drawbacks of the conventional device. Turned into

Briefly describing the reciprocating actuator A which the applicant of the present invention has put to practical use, as shown in FIG. 5, a fluid pressure cylinder 103 having a piston 101 and an output rod 102 is provided at the bottom of the housing 100, and the housing 100 is provided. Is provided with a switching valve mechanism 105 having a switching valve body 104, and a control valve mechanism 107 having a rod-shaped valve member 106 fixed to the central portion of the piston 101 is provided at the axial center of the upper portion of the housing 100. A fluid pressure supply port 108 is provided on the right side of the housing 100.
And a discharge port 109 is formed on the left side.

Further, in the housing 100, the forward motion chamber 110 is provided above the piston 101, and the annular switching valve portion of the switching valve body 104 is provided.
A pressure receiving chamber 112 communicating with the fluid pressure supply port 108 is provided on the upper side of 111, an annular gap 113 is provided on the outer peripheral side of the switching valve part 111, and an exhaust gap 114 is provided on the lower side of the switching valve part 111. The
An annular exhaust passage 116, which communicates with an exhaust port 109 via an exhaust passage 115, is provided on the outer peripheral side of the lower portion of the switching valve body 104.
A valve working chamber 117 is provided on the lower end side of 4.

In the reciprocating actuator A configured as described above, when the piston 101 is advanced at the retracted limit position shown in FIG. 5, the valve working chamber 117 is exhausted by the annular passage 120 and the passage 121 of the control valve mechanism 107. The switching valve body 104, which is communicated with the port 109, is driven downward by the fluid pressure of the pressure fluid supplied to the pressure receiving chamber 112, is located at the supply position shown in FIG. 5, and the exhaust gap 114 is sealed. , Forward movement moving room 110
Is connected to the fluid pressure supply port 108 via the pressure receiving chamber 112, the annular gap 113, and the passage 118, so that the piston 101 is driven to advance downward by the pressure fluid supplied to the outward motion chamber 110.
Further, when the piston 101 reaches the advance limit position and then moves backward, the control valve mechanism 107 causes the valve working chamber 117 to move to the passage 121.
And the valve member 106 is connected to the fluid pressure supply port 108 via the small diameter portion 106a, and then sealed in a pressure fluid filled state.
4 is driven upward by the pressure fluid supplied to the valve working chamber 117 and is switched to a discharge position for sealing the pressure receiving chamber 112, and the forward operation moving chamber 110 includes a passage 118, an exhaust gap 114, an annular exhaust passage 116, and an exhaust passage. Since it is connected to the exhaust port 109 via 115, the piston 10
1 is driven backward by the spring force of the return spring 119.

After that, when the piston 101 is driven to the backward limit position,
The forward operation moving chamber 110 is connected to the fluid pressure supply port 108 by the switching valve mechanism 105 and the control valve mechanism 107, and the reciprocating movement of the piston 101 is repeated in the same manner as above.

[Problems to be solved by the device]

The reciprocating actuator A is configured to drive the switching valve body 104 downward by the fluid pressure of the pressure fluid supplied to the pressure receiving chamber 112 to connect the forward operation moving chamber 110 to the fluid pressure supply port 108. For example, the case where the reciprocating actuator A is applied to a plunger type hydraulic pump will be described as an example.

Increasing the stroke of the switching valve body 104 to increase the pressure receiving chamber 112 and the exhaust clearance 114 to increase the supply flow rate of the pressure fluid to the forward operation moving chamber 110 and the discharge flow rate of the pressure fluid from the forward operation moving chamber 110. Thus, when the reciprocating cycle of the piston 101 is speeded up and the output of the hydraulic pump is increased, that is, the discharge amount is increased, the switching valve body 104 is switched from the exhaust position to the supply position during the switching operation of the switching valve body 104. On the way, the pressure fluid is divided into the forward motion chamber 110 and the exhaust clearance 114, and the fluid pressure acting from above on the switching valve portion 111 and the fluid pressure acting from below are balanced to stop the movement of the switching valve body 104. When the state is likely to occur and the switching valve body 104 is in the neutral state, the pressure fluid is not supplied to the outward motion chamber 110, and the reciprocating motion of the piston 101 is stopped. Therefore, there is a limit in increasing the stroke of the switching valve body 104 to speed up the reciprocating cycle of the piston 101, and there is a problem that the output of the reciprocating drive actuator cannot be increased.

Further, when the pressure fluid from the fluid pressure supply port 108 is made low to drive the piston 101 at a low pressure to reduce the discharge pressure of the hydraulic pump, the fluid pressure acting on the switching valve portion 111 is low, so that the piston 101 advances. During operation, the switching valve body 104 moves from the discharge position to the supply position at a low speed, and the neutral state of the switching valve body 104 is likely to occur as in the above case. Therefore, there is a limit to the low pressure drive of the piston 101, and there is a problem that the output of the reciprocating drive actuator cannot be reduced.

An object of the present invention is to provide a reciprocating actuator that operates reliably without the neutral state of the switching valve body occurring.

[Means for Solving the Problems]

A reciprocating actuator according to the present invention is provided with a fluid pressure cylinder having a piston and an output rod fixed to the piston in a housing, and a forward motion chamber for driving the piston to advance at least by fluid pressure in the fluid pressure cylinder. A return valve that drives the piston backward, and a switching valve body that can be selectively switched between a feed position connecting the forward motion chamber to the fluid pressure supply port and a discharge position connected to the discharge port, The switching valve mechanism is provided with a biasing means for biasing the switching valve body to the supply position, and a valve working chamber for switching the switching valve body to the discharge position by fluid pressure against the biasing force. The valve working chamber is connected to the discharge port when the piston is in the backward limit position and the valve is inserted between the backward limit position and the forward limit position via the valve member that extends from the Actuation In a fluid pressure driven continuous operation type reciprocating actuator which is provided with a control valve mechanism for sealing the valve and connecting the valve working chamber to the fluid pressure supply port when the piston is at the advance limit position. It is composed of a pressure receiving chamber for urging the body to the supply position by fluid pressure and a compression coil spring, and the urging force of this urging means is changed by the fluid pressure supplied from the fluid pressure supply port to the valve working chamber. It is set weaker than the fluid force acting on.

[Action]

In the fluid pressure driven continuous operation type reciprocating actuator according to the present invention, the valve working chamber is connected to the discharge port by the control valve mechanism when the piston is at the backward limit position while the pressure fluid is being supplied to the fluid pressure supply port. Therefore, the switching valve body is held at the supply position by the biasing means, the pressure fluid is supplied from the fluid pressure supply port to the forward movement moving chamber, and the piston is driven to advance by the fluid pressure in the forward movement moving chamber. The control valve mechanism seals the valve working chamber in the fluid pressure discharge state until the piston reaches the retreat limit position and the advance limit position, so that the switching valve body is held at the supply position.

After that, when the piston reaches the advance limit position, the valve working chamber is connected to the fluid pressure supply port by the control valve mechanism, and the switching valve body is displaced by the fluid pressure in the valve working chamber against the biasing force of the biasing means. Therefore, the forward moving chamber is connected to the discharge port, and the piston starts the backward drive by the returning means.

Here, the urging means is composed of a pressure receiving chamber for urging the switching valve body to the supply position by fluid pressure and a compression coil spring, and the urging force of the urging means supplies fluid pressure to the valve working chamber. Since the fluid pressure supplied from the mouth is set to be weaker than the fluid force acting on the switching valve body, the switching valve body switches to the discharge position against the biasing force of the biasing means by the fluid pressure in the valve working chamber. To be

Since the valve working chamber is sealed in the fluid pressure filled state until the piston reaches the retracted limit position from the advanced limit position, the switching valve body is held at the discharge position. Thus, when the piston reaches the retreat limit position, the valve operating chamber is connected to the discharge port by the control valve mechanism, the switching valve body is switched to the supply position by the urging means, and the above is repeated in the same manner as described above. It will be driven back and forth.

In the reciprocating actuator of the present invention, the urging means for urging the switching valve body to the supply position includes a compression spring, which is a relatively simple member, and a pressure receiving chamber for urging the switching valve body to the supply position by fluid pressure. Therefore, in order to increase the amount of pressure fluid supplied to the forward moving chamber and the discharge amount from the forward moving chamber, the movement stroke of the switching valve element between the supply position and the discharge position becomes long. However, the switching valve body is reliably switched from the discharge position to the supply position by the spring force of the spring and the fluid force of the fluid pressure in the pressure receiving chamber, so that the switching valve body is not in a neutral state.

Therefore, the reciprocating cycle of the piston can be speeded up, and the output of the reciprocating actuator can be greatly increased.

Further, even if the fluid pressure of the pressure fluid is low to drive the piston at a low pressure, the switching valve body is reliably switched from the discharge position to the supply position by the spring force of the spring and the fluid force of the fluid pressure in the pressure receiving chamber, and is in a neutral state. Never be.

Therefore, it becomes possible to drive the piston at low speed,
The output of the reciprocating actuator can be set to any size.

[Effect of device]

According to the fluid pressure drive continuous operation type reciprocating actuator according to the present invention, as described in the above section [Operation], the urging means for urging the switching valve body to the supply position is provided with the switching valve body. A pressure receiving chamber urged to the supply position by a compression coil spring, and the urging force of this urging means is applied to the switching valve body by the fluid pressure supplied from the fluid pressure supply port to the valve working chamber. Since it is set to be weaker than the physical strength, the problem that the switching valve body is in the neutral state is resolved, the reciprocating cycle speed can be increased, that is, the output can be greatly increased, and the piston can be driven by low pressure fluid. It becomes possible to set the output of the reciprocating actuator freely, large or small, and improve the versatility of the reciprocating actuator.
And the like. [Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

The present embodiment is an example of the case where the present invention is applied to an air-driven hydraulic pump in which a plunger is driven by a reciprocating actuator of a compressed air (hereinafter referred to as pressurized air) drive continuous operation type.

As shown in FIG. 1, the hydraulic pump HP includes a reciprocating actuator AC and a pump main body PC, and a housing 10 of the reciprocating actuator AC includes an upper housing 11, an intermediate housing 12, and a lower housing 13. Common bolt
It is configured by integrally connecting with 14.

A return air cylinder 20 is provided in the lower half of the housing 10, a piston 22 is mounted in a cylinder hole 21 of the air cylinder 20, and a plunger 24 is provided below an output rod 23 extending from the lower end of the piston 22. Formed and cylinder hole 21
A forward motion chamber 25 is formed above the piston 22 and a backward motion chamber 26 is formed below the piston 22.

A plunger hole 15 is provided in the lower housing 13, and the plunger 24 is driven into and out of the plunger hole 15 so that the suction port
The oil sucked from 16 into the plunger hole 15 via the suction check valve 17 is compressed by the plunger 24 and discharged to the discharge port 19 via the discharge check valve 18.

A pressurizing air supply port 3 to which pressurizing air (for example, 5.0 kg / cm ² G) is supplied from an external pressurizing air supply source is provided on an upper side portion of the housing 10, and inside the upper end portion of the housing 10. An exhaust chamber 5 communicating with the atmosphere via a muffler 4 serving as an exhaust port is formed therein.

Next, the switching valve mechanism 30 will be described.

On the upper surface of the partition wall 31 of the intermediate housing 12, the intermediate housing is
An annular member 32 housed in the inside 12 is fixed, and a pressurized air supply path 33 connected to the pressurized air supply port 3 is provided on the outer peripheral side of the annular member 32.
The switching valve body 35 is mounted inside the recess 34 of the partition wall 31 and the annular member 32, and the lower piston portion 36 at the lower end of the switching valve body 35 is mounted in the recess 34 in a hermetically slidable manner. At the same time, in the middle part of the switching valve body 35, an annular and flanged switching valve portion 37 is provided.
Is formed, the upper piston portion 38 of the upper end portion of the switching valve body 35 is fitted in the cylinder hole 39 of the annular member 32 in a hermetically slidable manner,
An annular exhaust passage 41 is formed between the switching valve portion 37 and the lower piston 36 on the outer peripheral portion of the switching valve body 35 by the exhaust passage 40 and is connected to the exhaust chamber 5. An annular exhaust passage 41 is formed on the outer peripheral side of the switching valve portion 37 by the passage 42a. An annular passage 42 that communicates with the forward movement moving chamber 25 is formed. The annular member 32 is formed with a first valve seat 44 on which the annular first valve surface 43 of the upper surface of the switching valve portion 37 abuts, and the partition wall 31 is the annular second valve surface 45 of the lower surface of the switching valve portion 37. A second valve seat 46 against which the switching valve element 35 is formed between the first valve surface 43 and the upper piston portion 38.
An annular pressure receiving chamber 48 connected to the pressurized air supply passage 33 is formed on the outer peripheral side by the passage 47, and the switching valve body 35 is elastically biased downward by a compression coil spring 49.

When the second valve surface 45 of the switching valve body 35 comes into contact with the second valve seat 46, the first valve surface 43 and the first valve seat 44 are opened, and the supply gap 51 is formed therebetween, and the forward movement moving chamber 25 Is the passage 42a, the annular passage 4
2, pressure receiving chamber 48, supply gap 51, passage 47 and pressurized air supply passage 3
3 is connected to the pressurized air supply port 3. Therefore, the position of the switching valve element 35 at this time is referred to as a supply position.

When the first valve surface 43 of the switching valve body 35 abuts on the first valve seat 44, the second valve surface 45 and the second valve seat 46 are opened to form an exhaust gap 52, and the forward operation moving chamber 25 passes through the passage. The exhaust chamber 5 is communicated with the exhaust chamber 42a, the exhaust gap 52, the annular passage 42, the annular exhaust passage 41, and the exhaust passage 40. Therefore, the position of the switching valve body 35 at this time is referred to as a discharge position.

The lower piston 36 of the switching valve body 35 and the recess 34 form a valve working chamber.
When the valve working chamber 50 is formed and the pressurized air is not supplied to the valve working chamber 50, the switching valve body 35 is provided with the pressurized air in the pressure receiving chamber 48 and the spring.
When the valve operating chamber 50 is urged to the supply position by 49 and pressurized air is supplied to the valve working chamber 50 as described later, the switching valve body 35 is switched to the discharge position.

Next, the control valve mechanism 60 will be described.

A rod-shaped valve member fixed to the center of the piston 22.
61 extends upward through the sliding hole 62 of the partition wall 31 and the insertion hole 63 of the switching valve body 35, and a small diameter portion 64 is formed in the middle of the valve member 61. A pair of upper and lower O-rings 65 and 66, which are pressed against the outer peripheral surface of the valve member 61 in an airtight manner, are attached to the peripheral portion, and the inner peripheral portion of the upper end of the insertion hole 63 is airtight to the outer peripheral surface of the valve member 61. An O-ring 67 that is pressed into a circular shape is installed, and a pressure air passage 68 that communicates with the pressure air supply port 3 is attached to the partition wall 31.
It is formed up to the outside of 65 and 66.

When the piston 22 is in the retracted limit position shown in FIG. 1, the small diameter portion 64 releases the O-ring 67, and the valve working chamber 50 is closed by the annular gap 69 outside the valve member 61 of the insertion hole 63. When the piston 22 is in communication with the exhaust chamber 5 and the piston 22 is in the advance limit position shown in FIG.
69 is sealed, the O-ring 65 is unsealed by the small diameter portion 64, the pressurized air passage 68 is communicated with the valve working chamber 50, and the piston 22 is between the retracted limit position and the advanced limit position. Sometimes the O-rings 65 and 67 seal the valve working chamber 50.

Next, the relief valve mechanism 80 and the supply valve mechanism 81 will be described.

This reciprocating actuator AC drives the piston 22 and the output rod 23 to advance by the pressurized air supplied to the forward movement moving chamber 25, and is also housed in the backward movement moving chamber 26 at all times.
The piston 22 and the output rod 23 are configured to be driven backward by pressurized air below a set pressure (for example, 0.5 kg / cm ² G) and above a second set pressure (for example, 0.4 kg / cm ² G). . Therefore, the relief valve mechanism 80 that performs a relief operation when the pressure of the pressurized air in the backward movement moving chamber 26 of the piston 22 is higher than the first set pressure, and the backward movement moving chamber 26 of the backward movement of the piston 22 A supply valve mechanism 81 for supplying pressurized air when the pressure of the pressurized air therein is less than the second set pressure is provided as follows.

An annular supply valve element 83 is fitted on the annular member 32 in the intermediate housing 12 so as to be slidable in an airtight manner, and an annular relief valve element 84 is provided on the upper housing 11 above the supply valve element 83.
Is fitted in an airtight and slidable manner, an annular third valve surface 85 is formed on the lower surface of the relief valve element 84, and the third valve surface 85 is in contact with the upper end portion of the supply valve element 83. 86 formed, supply valve body
An annular fourth valve surface 87 is formed on the upper surface of the middle outer peripheral step portion 83, and a fourth valve seat 83 with which the fourth valve surface 87 abuts is formed on the lower surface of the collar portion 89 of the upper housing 11, A first restricting portion 90 that restricts the lower limit position of the relief valve body 84 is formed on the upper surface of the portion 89, and a second restricting portion 91 that restricts the lower limit position of the supply valve body 83 is formed on the outer peripheral portion of the annular member 32. Has been done.

An annular pressure receiving chamber 92 is formed between the upper housing 11, the relief valve body 84 and the supply valve body 83, and the supply valve body 83 and the annular member 32 are formed.
An annular back pressure chamber 93 communicated with the annular pressure receiving chamber 92 by a communication hole 93a is formed therebetween, and the annular pressure receiving chamber 92 is provided with a passage 94, an annular passage 95 common to the bolt holes, and a hole at the lower end of the intermediate housing 12.
It is communicated with the return motion chamber 26 by 96.

Further, the relief valve body 84 is elastically biased downward by the first spring 97 which is a compression coil spring for setting the first set pressure, and the supply valve body 83 cooperates with the first spring 97 to set the second set pressure. A second spring 98, which is a compression coil spring for setting pressure, is elastically biased upward.

When the pressure of the pressurized air in the return motion chamber 26 is equal to or lower than the first set pressure and equal to or higher than the second set pressure, the relief valve body 84 and the supply valve body 83 maintain the state shown in FIG. Valve face 85 and third valve seat 86
And the fourth valve face 87 and the fourth valve seat 88 are closed.

When the pressure of the pressurized air in the return motion chamber 26 becomes higher than the first set pressure during the advancing operation of the piston 22, the relief valve body 84 moves upward due to the pressurized air in the annular pressure receiving chamber 92, and the third valve Face 85
However, since the pressurized air is released from the third valve seat 86, the pressure in the return motion chamber 26 is maintained at the first set pressure. When the pressure of the pressurized air in the reciprocating motion chamber 26 becomes lower than the second set pressure during the backward movement of the piston 22, the relief valve body 84 supplies the second spring 98 against the second spring 98 by the spring force of the first spring 97. Since the valve body 83 is pushed downward, the fourth valve face 87 separates from the fourth valve seat 88, and pressurized air is supplied from the pressurized air supply passage 33 to the annular pressure receiving chamber 92, so that the return motion chamber 26 Is maintained at the second set pressure.

A synthetic resin member having excellent wear resistance is embedded in the first to fourth valve faces 43, 45, 85, 87.

Next, the operation of the reciprocating actuator AC will be described.

With pressurized air being supplied to the pressurized air supply port 3,
Since the valve operating chamber 50 is connected to the exhaust chamber 5 by the control valve mechanism 60 when the piston 22 is in the backward limit position, the switching valve body 35 is in the supply position by the pressurized air in the pressure receiving chamber 48 and the urging force of the spring 49. The compressed air is supplied from the compressed air supply port 3 to the forward moving chamber 25, and the piston 22 resists the pressurized air in the backward moving chamber 26 by the pressurized air in the forward moving chamber 25. And driven to advance. The valve operating chamber is controlled by the control valve mechanism 60 until the piston 22 reaches the retracted limit position and the advanced limit position.
Since the valve 50 is sealed in the air pressure discharged state, the switching valve body 35 is held at the supply position. Therefore, as described above, the forward movement moving chamber 25
The pressurized air is continuously supplied to the piston 22, and the piston 22 is driven to advance. During this time, the air in the backward movement moving chamber 26 is pressurized, and when it becomes higher than the first set pressure, it is relieved by the relief valve mechanism 80, so that it is kept at the first set pressure.

After that, when the piston 22 reaches the advance limit position, the control valve mechanism 60 connects the valve working chamber 50 to the pressurized air supply port 3,
Since the switching valve body 35 is switched to the discharge position by the pressurized air in the valve working chamber 50 against the pressurized air in the pressure receiving chamber 48 and the biasing force of the spring 49, the forward operation moving chamber 25 is connected to the exhaust chamber 5. Is
The first set pressure air in the return motion chamber 26 causes the piston to move.
22 starts backward drive. When the switching valve body 35 is switched from the supply position to the discharge position, the pressure receiving area of the valve working chamber 50 is larger than the pressure receiving area of the pressure receiving chamber 48, and the switching valve body 35 is sufficiently resisted against the spring force of the spring 49. Since the driving force is set to be generated upward, the switching valve body 35 can be instantly switched to the discharge position without being in the neutral state. Piston 22
The valve working chamber 50 from the advance limit position to the retract limit position
Is sealed in a pressurized air filled state, so that the switching valve body 35 is held at the discharge position. When the air pressure in the reciprocating motion chamber 26 drops below the second set pressure that is less than or equal to the first set pressure in response to the retreat of the piston 22, the supply valve mechanism 81 opens to supply pressurized air to the reciprocating motion chamber 26. Therefore, the second set pressure is maintained, and the retreat of the piston 22 is continued. Thus, when the piston 22 reaches the retreat limit position, the valve operating chamber 50 is connected to the exhaust chamber 5 by the control valve mechanism 60, the switching valve body 35 is switched to the supply position, and the same operation is repeated thereafter, and the piston 22 reciprocates. Will be driven. When the switching valve body 35 is switched from the discharge position to the supply position, the spring 49 strongly drives the switching valve body 35 downward to instantaneously switch to the supply position, so that the switching valve body 35 is in the neutral state. There is no.

As is clear from the above description, the reciprocating actuator
In AC, pressurized air is supplied to and discharged from the forward motion chamber 25 by the switching valve mechanism 30 and the control valve mechanism 60 in synchronization with the reciprocating operation of the piston 22, and the relief valve mechanism 80 and the supply valve mechanism.
Since the compressed air equal to or lower than the first set pressure and equal to or higher than the second set pressure is constantly held in the backward movement chamber 26 by 81, the piston
22 continuously reciprocates, and the plunger 24 at the tip of the output rod 23 continuously reciprocates within the plunger hole 15. Therefore, in the hydraulic pump main body PC, oil suction and compression / discharge are continuously repeated.

As described above, in the hydraulic pump HP of the present embodiment, since the supply valve body 35 is biased to the supply position by the spring 49, when the switching valve body 35 is switched from the discharge position to the supply position. In addition, the switching valve body 35 is instantly and reliably switched to the supply position without being in a neutral state. Therefore,
By increasing the supply gap 51 and the exhaust gap 52, the neutral state of the switching valve body 35 does not occur even if the vertical movement stroke of the switching valve body 35 during the switching operation increases, and the forward movement chamber 25
Increase the supply flow rate and discharge flow rate of pressurized air to the piston
The 22 reciprocating cycles can be speeded up, and the discharge amount of the hydraulic pump can be greatly increased. Further, even if the piston 22 is driven at a low pressure by the low pressure air, the switching valve body 35 is instantaneously and reliably switched from the discharge position to the supply position by the spring 49, so that the low pressure of the piston 22 is reduced. Since reciprocating drive is possible, the discharge pressure of the hydraulic pump can be set low.

The spring 49 may be provided between the muffler 4 and the switching valve body 35, or the spring 49 may be provided in the pressure receiving chamber 48 to bias the switching valve body 35.

Next, a modified example of the above embodiment will be described with reference to FIGS. The same mechanisms as those in the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

<Modification 1> In place of the O-ring 67 of the control valve mechanism 60 of the above embodiment, a third
A control valve mechanism 60A as shown in the figure is provided.

The switching valve body 35A is provided with a tubular portion 100, and the tubular portion 100 has a valve hole 1
A second valve member 102 for opening and closing 01 is attached, a valve closing spring 103 made of a compression coil spring is attached to the muffler 4, and the second valve member 102 is elastically biased downward by the valve closing spring 103,
The rod-shaped valve member 61A fixed to the center of the piston 22 below the second valve member 102 is obtained by removing the portion above the lower end of the small diameter portion 64 of the valve member 61 of the above embodiment. Is.

The other parts of the control valve mechanism 60A are the same as those in the above-mentioned embodiment, and the description thereof will be omitted.

In the control valve mechanism 60A, when the piston 22 is at the retracted limit position as shown in the figure, the valve member 61A pushes up the second valve member 102 against the spring force of the valve closing spring 103 and opens the valve hole 101. Since the hole is formed, the valve working chamber 50 is connected to the exhaust chamber 5 via the annular gap 69, the valve hole 101, and the passage of the tubular portion 100.
Is held at the supply position, and when the piston 22 is at the advance limit position, the second valve member 102 is lowered by the valve closing spring 103 to close the valve hole 101 and the upper end of the valve member 61A is below the O-ring 66. As it is lowered to, the pressurized air passage 68 is communicated with the valve working chamber 50, the valve working chamber 50 is filled with pressurized air, and the switching valve body 35A is switched to the discharge position. The other operations are the same as those in the above-mentioned embodiment, so that the description thereof will be omitted.

<Modification 2> Instead of the switching valve portion 37 of the switching valve body 35 of the above-described embodiment, the switching valve mechanism 30B has an annular seal member 110 as shown in FIG.
A switching valve section (37B) having the above is provided in the switching valve body (35B). As shown in FIG. 4, when the switching valve body 35B is at the supply position, the seal member 110 abuts on the inner peripheral surface of the second valve seat 46B, and the forward movement moving chamber 25 moves the passage 42a, the annular passage 42, Annular gap 111, pressure receiving chamber 48,
The passage 47 and the pressurized air supply passage 33 communicate with the pressurized air supply port 3.

On the other hand, when the switching valve body 35B is switched to the discharge position, the seal member 110 comes into contact with the inner peripheral surface of the first valve seat 44B, and
The annular gap 111 is in communication with the annular exhaust passage 41, and the forward movement chamber 25 is in communication with the exhaust chamber 5 through the passage 42a, the annular passage 42, the annular gap 111, the annular exhaust passage 41, and the exhaust passage 40. The other operations are the same as those in the above-mentioned embodiment, and the description thereof will be omitted.

It should be noted that a spring-return-type single-action ethie cylinder may be applied instead of the air cylinder 20 of the present embodiment, and the relief valve mechanism 80 and the supply valve mechanism 81 may be omitted, and hydraulic pressure may be used instead of the pressurized air. . Further, the present invention can be applied to various devices using reciprocating drive such as a hydraulic pressure boosting pump and a gas pressure boosting pump in addition to the hydraulic pump.

[Brief description of drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of the hydraulic pump when the piston is at the backward limit position, and FIG. 2 is when the piston is at the forward limit position. FIG. 3 is a partial vertical sectional view of a hydraulic pump showing a modified example of the control valve mechanism. FIG. 4 is a partial vertical sectional view of a hydraulic pump showing a modified example of the switching valve mechanism. FIG. 1 is a longitudinal sectional view of a main part of a reciprocating actuator according to a conventional technique. AC ... Reciprocating actuator, 3 ... Pressurized air supply port,
5 ... Exhaust chamber, 10 ... Housing, 20 ... Double acting air cylinder, 22 ... Piston, 23 ... Output rod, 25 ... Forward working chamber, 26 ... Return working chamber, 30 ... Switching Valve mechanism, 35/35
B …… Switching valve body, 49 …… Spring, 50 …… Valve working chamber, 6
0 ・ 60A …… Control valve mechanism, 61 …… Valve member.

Claims (1)

[Scope of utility model registration request] 1. A fluid pressure cylinder having a piston and an output rod fixed to the piston is provided in a housing, and a forward motion chamber for advancing and driving the piston with at least fluid pressure is provided in the fluid pressure cylinder. And a switching valve body for selectively switching between a feed position for connecting the forward operation moving chamber to the fluid pressure supply port and a discharge position for connecting to the discharge port. A switching valve mechanism provided with a biasing means for biasing the supply position and a valve working chamber for switching the switching valve body to the discharge position by fluid pressure against the biasing force is provided, and extends from the piston to the switching valve body. Through the inserted valve member, connect the valve working chamber to the discharge port when the piston is in the backward limit position and seal the valve working chamber when the piston is between the backward limit position and the forward limit position. And the piston is the limit In a fluid pressure drive continuous operation type reciprocating actuator provided with a control valve mechanism for connecting the valve working chamber to the fluid pressure supply port when in the stationary position, the urging means is used to apply the switching valve body to the supply position by the fluid pressure. It is composed of a pressure receiving chamber for urging and a compression coil spring, and the urging force of this urging means is set to be weaker than the fluid force acting on the switching valve body by the fluid pressure supplied from the fluid pressure supply port to the valve working chamber. A fluid pressure drive continuous operation type reciprocating actuator characterized by the above.