JP2676111B2 - Fluid pressure continuously operated reciprocating actuator - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid pressure driven continuously operating 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 this type of fluid pressure driven continuous operation type reciprocating actuator, a spring return type single acting fluid pressure cylinder is incorporated in the housing, and a directional switching valve is provided for the fluid pressure supply port and the discharge port with respect to the working chamber of the cylinder. When the working chamber and the supply port are communicated with each other, the piston and the output rod are driven to advance against the return spring by the fluid pressure (usually compressed air) when the mechanism is switched. When the working chamber communicates 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 switching valve mechanism. It is known to be configured so as to cause it.

As disclosed in Japanese Patent Publication No. 55-40761, the applicant of the present invention puts into practical use a device which is small in size and light in weight, can be manufactured at a relatively low cost, and has excellent operational reliability and durability, while eliminating the drawbacks of the conventional device. Turned into

[Problems to be solved by the invention]

The reciprocating actuator has a structure in which the piston and the output rod are driven to advance by the fluid pressure supplied to the working chamber, and the piston and the output rod are reset by the return spring. Remaining.

The case where the above reciprocating actuator is applied to an actuator for driving a plunger type hydraulic pump will be described as an example. The total length of the reciprocating stroke of the piston and the length of the returning spring in the maximum compression state for accommodating the returning spring. Since the above spring accommodating chamber must be provided, the actuator becomes larger, and if the reciprocating cycle of the piston is accelerated to increase the output, that is, the discharge amount of the hydraulic pump, the return spring becomes unable to follow and the return spring is damaged. Since there is a limit to speeding up, and when the stroke of the piston and output rod is increased to increase the discharge amount of the hydraulic pump, the spring length of the return spring increases, so a large return spring is required and the overall size increases. If the spring force of the return spring is increased in order to improve the followability of the return spring, Force is reduced and the discharge pressure of the hydraulic pump is reduced, and the versatility of the hydraulic pump is reduced due to the inability to drive with low fluid pressure, and the piston is driven forward against the spring force of the return spring. Therefore, there are various problems such that a considerable part of the power of the pressure fluid as the driving force source is wasted, that is, the energy loss becomes large.

An object of the present invention is to provide a fluid pressure driven continuous operation type reciprocating actuator capable of returning and driving a piston by fluid pressure instead of a return spring.

[Means for solving the problem]

A fluid pressure driven continuous operation type reciprocating actuator according to the present invention is provided with a double acting fluid pressure cylinder having a piston and an output rod fixed to the piston in a housing, and the piston is fluidly advanced to the fluid pressure cylinder. A forward motion moving chamber to be driven and a backward motion moving chamber to drive the piston backward by fluid pressure are provided, and the forward motion moving chamber is selectively provided as a supply position connecting to the fluid pressure supply port and a discharge position connecting to the discharge port. A switching valve body that can be switched to a switch position, a biasing means that biases the switching valve body to the supply position, and a valve working chamber that switches the switching valve body to the discharge position by fluid pressure against the biasing force. A valve mechanism is provided, and the valve working chamber is connected to the discharge port when the piston is at the backward limit position and the piston is at the backward limit position and the forward limit position through the valve member that extends from the piston and is inserted into the switching valve body. When it is between A control valve mechanism that seals the working chamber and connects the valve working chamber to the fluid pressure supply port when the piston is at the advance limit position is provided with the fluid pressure of the pressure receiving chamber that communicates with the valve working chamber of the control valve mechanism. Equipped with a movable valve body that is urged to close and opened by a spring.When the piston moves forward, it opens with a spring force to connect the return motion chamber to the discharge port and closes it when the piston moves backward. An on-off valve mechanism for valve operation is provided, and when the above-mentioned on-off valve mechanism is closed, it is driven by the movable valve body to open the valve to connect the return motion chamber to the fluid pressure supply port and when the on-off valve mechanism is opened, the valve is closed by a spring. The supply valve mechanism is provided.

[Action]

In the fluid pressure driven continuous operation type reciprocating actuator according to the present invention, when the piston is in the retracted limit position while the pressure fluid is being supplied to the fluid pressure supply port, the valve working chamber is set to the discharge port by the control valve mechanism. Since it is connected, the switching valve body is held at the supply position by the urging means, the pressure fluid is supplied from the fluid pressure supply port to the forward operation moving chamber, and at this time, the valve working chamber is connected to the discharge port. Therefore, the pressure fluid is not supplied to the pressure receiving chamber communicating with the valve working chamber, the movable valve element of the opening / closing valve mechanism is opened by the spring force, the return motion chamber is connected to the discharge port, and the piston moves forward. The advancing drive is started by the fluid pressure in the room. Since the valve operating chamber is sealed in the pressure fluid discharge state by the control valve mechanism until the piston reaches the retreat limit position and the advance limit position, the switching valve body is held at the supply position. Therefore, as described above, the pressurized fluid is supplied to the forward motion chamber, and the piston is continuously advanced.

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. The forward-moving chamber is connected to the discharge port. On the other hand, since the valve working chamber is connected to the fluid pressure supply port, the pressure fluid is supplied to the pressure receiving chamber, and the fluid pressure causes the movable valve element of the opening / closing valve mechanism to close against the spring force and the supply valve mechanism. Since the valve is driven to open and the backward movement moving chamber is connected to the fluid pressure supply port, the piston starts backward movement by the fluid pressure in the backward movement moving chamber. Until the piston reaches the retreat limit position, the pressure receiving chamber is filled with the pressure fluid, the opening / closing valve mechanism is closed, and the supply valve mechanism is kept in the valve open state by the movable valve body, so that the backward drive of the piston is continued. 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, and the piston is reciprocally driven in the same manner as above.

In the reciprocating actuator of the present invention, since the pressure fluid is supplied into the backward moving chamber and the piston is driven backward by the fluid pressure, the return spring can be omitted and the reciprocating motion of the piston can be eliminated. The stroke can be freely designed to be large or small as required,
Since the reciprocating motion chamber can be formed in a small working chamber required for the reciprocating stroke of the piston, the reciprocating actuator can be downsized. In addition, since the return motion chamber is connected to the discharge port when the piston moves forward, the energy loss of the pressure fluid can be eliminated and the output of the reciprocating actuator can be increased. Since the pressure fluid is supplied to the chamber from the pressure fluid supply port, the backward driving force of the piston can be increased, the backward movement of the piston can be speeded up, and the reciprocating cycle can be speeded up.

〔The invention's effect〕

According to the fluid pressure driven continuous operation type reciprocating actuator according to the present invention, as described in the above [Operation], the reciprocating motion chamber is discharged through the opening and closing valve mechanism and the supply valve mechanism when the piston advances. Connected to the piston and configured to supply backward pressure by supplying pressure fluid to the backward movement chamber when the piston moves backward, the spring can be omitted, energy loss of the pressure fluid can be eliminated, and the reciprocating cycle speed can be increased. The output can be increased, the reciprocating stroke of the piston can be freely designed to be large or small according to need, the reciprocating motion chamber can be downsized, and the reciprocating actuator can be downsized. The versatility of can be improved, and other effects can be obtained.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

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. It is configured by integrally connecting with a common bolt 14.

A double-acting 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 the output rod 23 extending from the lower end of the piston 22. Formed and cylinder hole
A forward motion chamber 25 is formed on the upper side of the piston 22 of the 21, and a backward motion chamber 26 is formed on the lower side of the piston 22.

A plunger hole 15 is provided in the lower housing 13,
The plunger 24 is driven into and out of the plunger hole 15, and the oil sucked into the plunger hole 15 from the suction port 16 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. To be done.

The upper side of the housing 10 is provided with a pressurized air supply port 3 to which pressurized air (for example, 5.0 kg / cm ² G) is supplied from an external pressurized air supply limit. 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.

An annular member 32 housed in the intermediate housing 12 is fixed to the upper surface of the partition wall 31 of the intermediate housing 12, and the annular member 32
On the outer peripheral side of the pressurizing air supply path connected to the pressurizing air supply port 3
33 is formed, a switching valve body 35 is mounted inside the recess 34 of the partition wall 31 and the annular member 32, and a 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. In addition, in the middle part of the switching valve body 35, an annular and flanged switching valve portion 37
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 spring 49.

When the second valve surface 45 of the switching valve element 35 comes into contact with the second valve seat 46, the space between the first valve surface 43 and the first valve seat 44 is opened, and the forward movement moving chamber
The passage 25a, the annular passage 42, the pressure receiving chamber 48, the passage 47 and the pressurized air supply passage 33 communicate with 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 contacts the first valve seat 44, the second valve surface 45 and the second valve seat 46 are opened, and the forward movement moving chamber
25 is a passage 42a, an annular passage 42, an annular exhaust passage 41 and an exhaust passage 40.
To communicate with the exhaust chamber 5. Therefore, the position of the switching valve body 35 at this time is referred to as a discharge position.

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

 Next, the control valve mechanism 60 will be described.

The rod-shaped valve member 61 fixed to the central portion of the piston 22 is inserted through the sliding hole 62 of the partition wall 31 and the insertion hole 63 of the switching valve body 35 to extend upward, and the middle portion of the valve member 61. Has a small diameter part 64
A pair of upper and lower O-rings 65 and 66, which are airtightly pressed against the outer peripheral surface of the valve member 61, are attached to the inner peripheral portion of the sliding hole 62, and the inner peripheral portion of the upper end of the insertion hole 63 is formed. An O-ring 67, which is pressed against the outer peripheral surface of the valve member 61 in an airtight manner, is attached to the partition wall 31, and a pressurized air passage 68 communicating with the pressurized 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,
The valve working chamber 50 is communicated with the exhaust chamber 5 by an annular gap 69 outside the valve member 61 in the insertion hole 63, and when the piston 22 is at the advance limit position shown in FIG. When the O-ring 65 is unsealed from the small diameter portion 64 and the pressurized air passage 68 is communicated with the valve working chamber 50, both are closed when the piston 22 is between the retreat limit position and the advance limit position. The valve working chamber 50 is sealed by the O-rings 65 and 67.

Next, the opening / closing valve mechanism 70 and the supply valve mechanism 71 will be described.

This reciprocating actuator AC connects the forward motion chamber 25 to the pressurized air supply port 3 and the backward motion chamber 26 to the exhaust chamber 5 to drive the piston 22 and the output rod 23 to advance, and The moving chamber 25 is connected to the exhaust chamber 5, and the backward moving chamber 26
Is connected to the pressurized air supply port 3,
And the output rod 23 is driven backward. Therefore, the opening / closing valve mechanism 70 that opens when the piston 22 advances and connects the return motion chamber 26 to the exhaust chamber 5 and closes when the piston 22 moves backward, and the valve opening / closing mechanism 70 that closes when the opening / closing valve mechanism 70 closes. A supply valve mechanism 71 that connects the operation chamber 26 to the pressurized air supply port 3 and is driven to close when the opening / closing valve mechanism 70 opens.
Are provided as follows.

An annular cylinder member 72 is fitted and mounted in the upper housing 11, and an annular movable valve element 74 is airtightly slidably mounted in an annular cylinder portion 73 composed of the housing 11 and the annular cylinder member 72. The movable valve body 74 is elastically urged upward by a first spring 75 formed of a compression coil spring, and an annular supply valve body 76 is airtightly slidably fitted onto the annular member 32.
Further, it is elastically biased upward by a second spring 77 which is a compression coil spring.

An annular third valve surface 78 is formed on the lower surface of the movable valve body 74,
A third valve seat abutting against the third valve face 78 is provided on the upper end portion of the supply valve body 76.
79 is formed, an annular fourth valve surface 80 is formed on the upper surface of the middle portion of the supply valve body 76, and a fourth valve seat abutting the fourth valve surface 80 is formed on the lower surface of the flange portion 81 of the upper housing 11. 82 is formed, collar part
A first restricting portion 83 that restricts the lower limit position of the movable valve body 74 is formed on the upper surface of 81, and a second restricting portion 84 that restricts the lower limit position of the supply valve body 76 is formed on the outer peripheral portion of the annular member 32. ing.

An annular pressure receiving chamber 85 is formed between the annular cylinder member 72 and the upper surface of the movable valve body 74, and a vent hole 86 is formed in a side portion of the upper housing 11 so as to communicate with the annular pressure receiving chamber 85.
Is connected by a connecting pipe 87 to the pressurized air passage 50a connected to the valve working chamber 50 as shown in FIG.

When the piston 22 is in the retracted limit position, the annular pressure receiving chamber 85
Since pressurized air is not supplied from the valve operating chamber 50 to the valve operating chamber 50, the movable valve element 74 and the supply valve element 76 are in the state shown in FIG. 1, and the movable valve element 74 is driven upward by the first spring 75. Valve face
78 is separated from the third valve seat 79, and the supply valve body 76 is the second spring.
It is driven upward by 77 and the space between the fourth valve surface 80 and the fourth valve seat 82 is closed, and the return motion chamber 26 is provided with the hole 8 at the lower end of the intermediate housing 12.
8, common annular passage 89, passage 90 and outlet 91 with bolt holes
Is connected to the exhaust chamber 5.

When the piston 22 is at the advance limit position, the movable valve body 74 and the supply valve body 76 are in the state shown in FIG. 2, and the movable valve body 74 is supplied from the valve working chamber 50 to the annular pressure receiving chamber 85. The compressed air is driven downward against the spring force of the first spring 75 and the second spring 77, the third valve surface 78 and the third valve seat 79 are closed, and the supply valve body 76 is moved downward by the movable valve body 74. Since it is pushed, the fourth valve face 80 separates from the space between the fourth valve seats 82, and the return motion chamber 26 is connected to the pressurized air supply passage 33.

A synthetic resin member having excellent wear resistance is embedded in the first to fourth valve faces 43, 45, 78, 80.

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

When the piston 22 is at the backward limit position while the pressurized air is being supplied to the pressurized air supply port 3, the control valve mechanism
Since the valve working chamber 50 is connected to the exhaust chamber 5 by 60, the switching valve body 35 is held at the supply position by the pressurized air in the pressure receiving chamber 48 and the urging force of the spring 49, and the pressurized air is supplied by the pressurized air. The piston 22 is supplied from the port 3 to the forward movement moving chamber 25, and the piston 22 is driven to advance by the pressurized air in the forward movement moving chamber 25. The control valve mechanism 60 seals the valve operating chamber 50 in the air pressure exhausted state until the piston 22 reaches the retracted limit position and the advanced limit position, so that the switching valve body 35 is held at the supply position. Therefore,
As described above, the supply of the pressurized air to the outward motion chamber 25 is continued, and the piston 22 is driven to advance. During this time, the pressurized air is not supplied to the annular pressure receiving chamber 85 communicating with the valve working chamber 50 through the ventilation hole 86, the connecting pipe 87 and the pressurized air passage 50a, so that the movable valve body 74 is moved upward by the first spring 75. Driven third
The valve face 78 is separated from the third valve seat 79, and the return motion chamber 26 is exhausted to the exhaust port 91.
The state of being communicated with, that is, maintained at atmospheric pressure.

After that, when the piston 22 reaches the advanced 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 5 against the pressurized air in the pressure receiving chamber 48 and the urging force of the spring 49, the forward operation moving chamber 25 is connected to the exhaust chamber 5. To be done. On the other hand, when the valve working chamber 50 is connected to the pressurized air supply port 3, pressurized air is supplied to the annular pressure receiving chamber 85, and the movable valve element 74 driven downward by the pressurized air moves the first spring 75. Since the supply valve body 76 is driven downward against the spring force of the second spring 77, the fourth valve surface 80 is separated from the fourth valve seat 82, and the return motion chamber 26 is connected to the pressurized air supply port 3. Pressurized air is supplied. The piston 22 starts the backward drive by the pressurized air in the backward movement moving chamber 26. Since the valve working chamber 50 is sealed in the pressurized air filled state until the piston 22 reaches the retracted limit position from the advanced limit position, the switching valve body 35 is held at the discharge position. Until the piston 22 reaches the backward limit position, the annular pressure receiving chamber 85 is filled with the pressurized air, and the fourth valve face 80 is kept away from the fourth valve seat 82. The compressed air is continuously supplied, and the backward drive of the piston 22 is continued. Thus, when the piston 22 reaches the backward limit position, the control valve mechanism
The valve working chamber 50 is connected to the exhaust chamber 5 by 60, and the switching valve body 35
Is switched to the supply position, and the above is repeated in the same manner as described above, so that the piston 22 is reciprocally driven.

As is clear from the above description, in the reciprocating actuator AC, the switching valve mechanism 30 and the control valve mechanism 60 supply / exhaust the pressurized air to / from the forward moving chamber 25 in synchronization with the reciprocating operation of the piston 22. The on-off valve mechanism 70 and the supply valve mechanism 71
Due to this, the backward movement working chamber 26 is connected to the exhaust chamber 5 when the piston 22 is driven forward, and is connected to the pressurized air supply passage 33 when the piston 22 is driven backward, so that the piston 22 repeats reciprocating motion continuously. Plunger at the tip of output rod 23
24 repeats reciprocating motion continuously 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 piston 22 is configured to be driven backward by the pressurized air, it is possible to omit the return spring for driving the piston 22 backward. The reciprocating cycle can be speeded up to increase the output of the reciprocating actuator AC, and the reciprocating stroke of the piston 22 can be freely designed to be large or small as necessary. Since the size can be made as small as necessary for the reciprocating stroke of 22, the hydraulic pump HP itself can be downsized. Moreover, it is possible to drive by supplying low-pressure pressurized air to the pressurized supply port 3.

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> Instead of the opening / closing valve mechanism 70 and the supply valve mechanism 71 of the above-described embodiment,
As shown in FIG. 4, the spool valve mechanism 100 may be provided in the lower housing 13, and the return motion chamber 26 may be selectively switched between the pressurized air supply port 3 and the exhaust port 5 for connection. .

Explaining the spool valve mechanism 100, the valve chamber 101 is recessed from the lower end surface of the lower housing 13, a spool valve body 102 is slidably mounted in the valve chamber 101, and a return valve is provided on the upper end side of the valve chamber 101. A sliding hole 103 that is continuous with the motion chamber 26 is formed,
A screw member 104 is provided on the lower end side of the valve chamber 101 by being screwed to the lower housing 13, and a spool valve body 102 is provided on the upper part of the valve chamber 101.
10 consisting of a compression coil spring that urges the
5, the lower part of the valve chamber 101 is formed in the pressure receiving chamber 106. Inside the housing 10, the valve chamber 101 is provided with a pressurized air supply passage 3
Exhaust passage communicating with the supply passage 107 connected to 3 and the exhaust chamber 5.
108 is formed, and the air passage 1 that communicates the pressure receiving chamber 106 from the lower end surface of the lower housing 13 with the valve working chamber 50 via the connecting pipe.
09 is formed.

In the spool valve mechanism 100, when the valve working chamber 50 is filled with the pressurized air, the pressure receiving chamber 106 is supplied with the pressurized air, and the spool valve body 102 is the spring of the spring 105 as shown in FIG. Driven upward against the force, the supply path 107
Is connected to a passage hole 110 formed in the spool valve body 102,
The exhaust passage 108 is sealed by the lower land of the spool valve body 102, and pressurized air is supplied to the backward movement moving chamber 26. When the valve working chamber 50 is connected to the exhaust chamber 5, the spool valve body 102 is driven downward by the spring 105, the supply passage 107 is sealed by the upper land of the spool valve body 102, and the exhaust passage 108 is connected to the spool valve. The backward movement chamber 26 is connected to the ventilation hole 110 of the body 102 and communicates with the exhaust chamber 5.

As described above, by providing the spool valve mechanism 100 by effectively utilizing the lower housing 13, the opening / closing valve mechanism 70.
It is possible to omit the annular cylinder member 72, the movable valve body 74, the first spring 75, the supply valve body 76, and the second spring 77, which are relatively large members that configure the supply valve mechanism 71, and to replace the hydraulic pump HP itself. Further, it becomes possible to make it smaller and lighter.

The spool valve mechanism 100 may be unitized and fixed to the housing 10 of the hydraulic pump HP without being provided in the lower housing 13.

<Modification 2> Instead of the control valve mechanism 60 of the above embodiment, a control valve mechanism 60A as shown in FIG. 5 is provided.

The switching valve body 35A is provided with a tubular portion 120, the tubular portion 120 is provided with a second valve member 122 for opening and closing the valve hole 121, and the muffler 4 is provided with a valve closing spring 123 made of a compression coil spring.
The second valve member 122 is elastically biased downward by the valve closing spring 123, and the rod-shaped valve member 61A, which is below the second valve member 122 and fixed to the central portion of the piston 22, is the same as in the above embodiment. The portion above the lower end of the small diameter portion 64 of the valve member 61 is removed.

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, the valve member 61A causes the valve closing spring 123
Since the second valve member 122 is pushed up and the valve hole 121 is opened against the spring force of the valve working chamber 50, the valve working chamber 50 has the annular gap 69, the valve hole 121, and the tubular portion 120.
Since it is connected to the exhaust chamber 5 via the passage of
A is held at the supply position, and when the piston 22 is at the advance limit position, the second valve member 122 is lowered by the valve closing spring 123 to close the valve hole 121 and the upper end portion of the valve member 61A becomes O.
As it descends below the ring 66, the pressurized air passage 68 communicates with the valve operating chamber 50, the valve operating 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 3> In place of the switching valve portion 37 of the switching valve body 35 of the above embodiment, a fourth
As shown in the figure, in the switching valve mechanism 30B, a switching valve portion 37B having an annular seal member 130 is provided in the switching valve body 35B.
As shown in FIG. 4, when the switching valve body 35B is in the supply position, the sealant 130 abuts on the inner peripheral surface of the second valve seat 46B, and the forward movement moving chamber 25 receives the passage 42a, the annular passage 42, The annular air gap 131, the 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 130 abuts on the inner peripheral surface of the first valve seat 44B, and the annular gap 131 is in communication with the annular exhaust passage 41, and the forward movement is performed. The chamber 25 includes the passage 42a, the annular passage 42, and the annular gap 13
1. The exhaust chamber 5 is communicated with 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.

[Brief description of the drawings]

1 to 5 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 longitudinal sectional view of the hydraulic pump of FIG. 3, FIG. 3 is a front view of a connecting pipe or the like that connects the valve working chamber and the pressure receiving chamber, and FIGS. 4 to 6 are modifications of this embodiment. 4 is a sectional view of a spool valve mechanism, FIG. 5 is a partial sectional view of a hydraulic pump showing a modified example of a control valve mechanism, and FIG. 6 is a partial sectional view of a hydraulic pump showing a modified example of a switching valve portion. AC ... Reciprocating actuator, 3 ... Pressurized air supply port,
4 ... muffler, 5 ... exhaust chamber, 10 ... housing, 20 ...
… Double acting air cylinder, 22 …… Piston, 23 …… Output rod, 25 …… Forward moving chamber, 26 …… Reverse operating chamber, 30 …… Switching valve mechanism, 35 / 35B …… Switching valve body, 49 ...... Spring, 50
...... Valve working chamber, 60 / 60A ...... Control valve mechanism, 61 ...... Valve member, 70 ...... Open / close valve mechanism, 71 ...... Supply valve mechanism, 74 ...... Movable valve body, 75 ...... First spring, 76 ...... Supply valve body, 77 ……
2nd spring, 85 ... Annular pressure receiving chamber, 100 ... Spool valve mechanism.

Claims (1)

(57) [Claims] 1. A double-acting fluid pressure cylinder having a piston and an output rod fixed to the piston is provided in a housing, and a forward-moving moving chamber for advancing and driving the piston by fluid pressure is provided in the fluid pressure cylinder. A return motion chamber that is driven backward by pressure is provided, and a switching valve body that can be selectively switched between a supply position that connects the forward motion chamber to the fluid pressure supply port and a discharge position that connects to the discharge port, and this switching valve body. A switching valve mechanism including a biasing means for biasing the 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 is provided, and the switching valve mechanism extends from the piston and switches. The valve working chamber is connected to the discharge port when the piston is at the backward limit position through the valve member inserted through the valve body, and the valve working chamber is opened when the piston is between the backward limit position and the forward limit position. Sealed and piston is in the advanced position Control valve mechanism that connects the valve working chamber to the fluid pressure supply port, the valve is actuated by the fluid pressure of the pressure receiving chamber communicating with the valve actuating chamber of the control valve mechanism to be closed and opened by a spring. An opening / closing valve mechanism for opening the valve by spring force when the piston moves forward to connect the return motion chamber to the discharge port and closing the valve when the piston moves backward. A supply valve mechanism is provided, which is driven to open by a movable valve element when the valve is closed, connects the return motion chamber to a fluid pressure supply port, and is driven to be closed by a spring when the opening / closing valve mechanism is opened. Fluid pressure continuously operated reciprocating actuator.