JPH11166507A - Reciprocating actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a reciprocating operation at high speed in a reciprocating actuator. SOLUTION: A single rod type piston 12 is slidingly fitted to a cylinder main body 11 and a return spring 19 for a resetting is provided in the rod 13 side of the piston 12. In the cylinder main body 11, a working fluid chamber 21 is provided in the side of the piston 12 having no rod 13 side and working fluid is supplied to and exhausted from the working fluid chamber 21 by a fluid control part 22. In the fluid control part 22, a movable valve element 31 is axially movably fitted to a valve main body 24 having a supply port 35 and an exhaust port 36 for the working fluid. Either the supply port 35 or the exhaust port 36 communicates with the working fluid chamber 31. The movable valve element 31 has a protruding part 44 pressed by the piston 12 moving upward and moved backward from the working fluid chamber 21 and a pressure receiving surface 45 opposite thereto. The pressure receiving surface 45 receives the supply of the working fluid from the working fluid chamber 21 via a communicating pipe 51 and a spring receiver 54 at the stroke end position of the piston 12 moving downward to operate the movable valve element 31 downward.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating actuator for driving a reciprocating pump or the like.

[0002]

2. Description of the Related Art As shown in Japanese Patent Publication No. 7-81550, a single-rod type piston slidably fitted in a cylinder body is used to form a working fluid chamber on one side of the piston and a piston in the cylinder body. A reciprocating type in which a working fluid chamber on the other side is defined and a working fluid whose direction is controlled by a fluid control unit provided adjacent to the cylinder body to the working fluid chambers on both sides thereof is controlled to be supplied and discharged. There is an actuator.

[0003]

In this conventional reciprocating actuator, the working fluid is alternately supplied to the working fluid chamber on one side of the piston and the working fluid chamber on the other side of the piston.
Although the force can be exerted by the forward operation and the return operation, the time required for fluid supply requires both reciprocating operations.

On the other hand, when a reciprocating pump or the like is driven by this reciprocating actuator, many pumps do not necessarily require a large force in both reciprocating operations, but rather increase the flow rate by increasing the number of reciprocating operations.

The present invention has been made in view of the above points, and has as its object to achieve a high-speed reciprocating operation in a reciprocating actuator.

[0006]

According to the first aspect of the present invention, there is provided a cylinder body, a single rod type piston slidably fitted in the cylinder body, and a piston provided on the rod side of the piston. A return spring for the return operation, a working fluid chamber provided on the side of the cylinder body without the rod of the piston, and a fluid control unit that controls supply and discharge of the working fluid to and from the working fluid chamber, The fluid control unit includes a valve body having a supply port and a discharge port for a working fluid,
A movable valve body that is fitted movably in the axial direction of the valve body and communicates one of a supply port and a discharge port of the working fluid with the working fluid chamber, and the movable valve body projects into the working fluid chamber. A convex portion which is pressed by the piston moved by the return force of the return spring and operates in a direction to retract the movable valve body from the working fluid chamber, and a stroke end position of the piston moved by the working fluid against the return spring. A reciprocating actuator comprising: a pressure receiving surface portion that receives a fluid pressure of a working fluid guided from a working fluid chamber to a side opposite to a convex portion of the movable valve body and operates the movable valve body toward the working fluid chamber.

The working fluid chamber communicates with the working fluid discharge port in a state where the convex portion of the movable valve body projects into the working fluid chamber. Therefore, the piston returns from the working fluid chamber while performing a return operation by a return spring. Extrude the working fluid. When the piston comes into contact with the convex portion of the movable valve body and pushes the movable valve body, the movable valve body switches to a state in which the supply port of the working fluid communicates with the working fluid chamber. Thereby, the piston operates against the return spring by the working fluid supplied to the working fluid chamber from the supply port. Then, when the piston moves to the stroke end position, the working fluid in the working fluid chamber is guided to the pressure receiving surface of the movable valve body, and the movable valve body receives the fluid pressure of the working fluid, switches to the working fluid chamber direction, and moves. The state returns to the initial state in which the convex portion of the valve body projects into the working fluid chamber.

According to a second aspect of the present invention, in the reciprocating actuator according to the first aspect, the movable valve body is provided with a neutral stop preventing mechanism for preventing the movable valve body from stopping at the neutral position. Are one spring receiving body provided integrally with the valve body, the other spring receiving body fitted to the movable valve body, and both ends of the wire with respect to a central shaft formed at the center of the wire. Are formed in a substantially C shape by bending the end shafts formed in the direction opposite to each other, and the center shaft is turned to one spring receiver and the end shafts at both ends are turned to the other spring receiver, respectively. And a wire spring movably fitted thereto.

The movable valve body is urged by a substantially C-shaped wire spring to one of a position for supplying the working fluid to the working fluid chamber and a position for discharging the working fluid from the working fluid chamber. The movable valve body is prevented from stopping at a neutral position other than any of them. In the wire spring, the central shaft portion functions as a rotation support shaft for the spring receiving body on the valve body side, and the end shaft portions at both ends curved in the directions facing each other rotate with respect to the spring receiving body on the movable valve body side. Functions as a pivot.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to an embodiment shown in the drawings.

As shown in FIGS. 1 to 3, a single rod-shaped piston 12 is slidably fitted in a cylinder body 11. The rod 13 of the piston 12 is drawn downward through a spring receiving plate 14 screwed into the lower opening of the cylinder body 11, and is connected to a pump shaft of a reciprocating pump (not shown).

The piston 12 has a seal member 16 having wear resistance sandwiched between a pair of holding plates 15 and is integrated by a bolt 17 screwed into an end of a rod 13.

A spring fitting groove 18 is provided on the upper surface side of the spring receiving plate 14, and a lower end of a return spring 19 for returning operation is fitted into the spring fitting groove 18, The upper end is engaged with the lower surface of the piston 12.

The rod of the piston 12 in the cylinder body 11
A working fluid chamber 21 is provided on the side without 13, and a fluid control unit 22 that controls supply and discharge of a working fluid to and from the working fluid chamber 21 is provided.

The fluid control section 22 has a lower end convex portion 25 of a valve body 24 fitted in an upper hole 23 of the cylinder body 11 via a seal member 26 such as an O-ring. hole
27 has a cylindrical sleeve 28 for sealing members such as O-rings
A movable valve element 31 in the form of a spool is fitted in the inner hole of the sleeve 28 through seal members 32, 33,
It is fitted slidably in the axial direction via 34.

The valve body 24 has a working fluid supply port 35 and a discharge port 36 on one side and the other side thereof.
Is a circumferential groove 37, a radial hole 38, and an axial hole communicating one of the supply port 35 and the discharge port 36 with the working fluid chamber 21.
Has 39. The sleeve 28 has a circumferential groove communicating the supply port 35 and the discharge port 36 of the valve body 24 with the circumferential groove 37 of the movable valve body 31.
41 and a radial hole 42.

In the lower part of the movable valve element 31, a convex part 44 is formed integrally with the working fluid chamber 21 through a sealing member 43 such as an O-ring fitted to the lower convex part 25 of the valve body 24. Convex part
44 is pressed by the piston 12 moved upward by the restoring force of the return spring 19 to move the movable valve element 31 to the working fluid chamber.
Operates in the direction to retract from 21. The protrusion 44 has the axial hole 39 formed therein. The axial hole 39 is open to the working fluid chamber 21.

At a relatively upper portion of the movable valve body 31, a pressure receiving surface portion 45 is provided.
Is provided. The pressure receiving surface portion 45 is provided on the piston 12 moved downward by the working fluid against the return spring 19.
At the stroke end position (the position indicated by a two-dot chain line in FIG. 3) of the movable fluid, the fluid pressure of the working fluid guided from the working fluid chamber 21 to the side opposite to the convex portion 44 of the movable valve 31 is applied. 31 is operated in the direction of the working fluid chamber 21, that is, downward.

That is, one working fluid port 46 is provided in the cylinder body 11 slightly above the stroke end position of the piston 12 that has moved down, while the other working fluid port 47 is provided on the upper side surface of the valve body 24. Provided with these working fluid ports
46 and 47 are communicated with each other through a communication pipe 51 connected by an elbow fitting 48 and a tightening screw pipe 49, and an upper working fluid port 47 is provided at an upper end of the valve body 24. Through the inner peripheral groove 53 of the upper hole 52, the lateral hole 55 of the spring receiving body 54 fitted in the upper hole 52, and the movable valve body fitting shaft hole 56 formed in the center of the spring receiving body 54, The pressure receiving surface 45 communicates with the pressure receiving surface 45.

A cover plate 58 closely attached to the upper end surface of the valve body 24 via a sealing member 57 such as an O-ring is bolted to the cylinder body 11 through the cover plate 58 and the valve body 24.
The sleeve 28 and the spring receiver 54 are fixed in the valve main body 24.

A neutral stop prevention mechanism 61 is provided above the movable valve element 31 to prevent the movable valve element 31 from stopping at the neutral position.

As shown in FIG. 4, the neutral stop preventing mechanism 61 includes one spring receiving member 54 integrally fitted into the upper hole 52 of the valve body 24 as described above, and a movable valve. The upper shaft 62 is slidably fitted to the upper shaft 62 of the body 31.
The spring receiving body 64 includes a spring receiving body 64 that is locked by a nut 63 screwed into the spring receiving body 64, and a pair of wire springs 65 provided between the spring receiving bodies 54 and 64.

Each of the wire springs 65 is configured such that both ends of the wire are curved in a direction facing each other with respect to a center shaft 71 linearly formed at the center of the wire, and are linearly parallel to the center shaft 71. By forming the end shaft portions 72 of the spring receiving members 72, the center shaft portions 71 are formed into a substantially C-shape. The linear grooves 74 of the body 64 are rotatably fitted respectively.

Next, the operation of the illustrated embodiment will be described.

As shown in FIG. 1, the convex portion of the movable valve body 31
With the 44 protruding into the working fluid chamber 21, the working fluid chamber 21
Axial hole 39, radial hole 38 and sleeve 28 of movable valve element 31
Because it communicates with the outlet 36 through the radial hole 42 etc.
The piston 12 pushes out a working fluid such as air from the working fluid chamber 21 while performing a return operation by a return spring 19.

During this return operation, for example, a pump (not shown) connected to the rod 13 of the piston 12 performs a suction operation with a relatively light load.

As shown in FIG. 2, when the piston 12 comes into contact with the convex portion 44 of the movable valve body 31 and pushes up the movable valve body 31, as shown in FIG. The state is switched to a state in which the working fluid supply port 35 communicates with the working fluid chamber 21.

That is, the working fluid supply port 35 passes through the radial hole 42 of the sleeve 28, the circumferential groove 37 between the seal members 33 and 34 of the movable valve body 31, the radial hole 38, the axial hole 39, and the like. It communicates with the working fluid chamber 21.

As a result, the working fluid such as compressed air supplied from the supply port 35 to the working fluid chamber 21 causes the piston 12 to move downward against the return spring 19.

At the time of this piston operation, the working fluid pressure supplied to the working fluid chamber 21 from the supply port 35 acts on the upper surface of the large-diameter piston 12, so that the piston 12 is pushed down by the working fluid pressure. , A reciprocating pump (not shown) connected to the rod 13 can be strongly driven, and the pump can perform a discharge operation that causes a large load.

When the piston 12 moves to the stroke end position 12a as shown by a two-dot chain line in FIG. 3, the working fluid in the working fluid chamber 21 is supplied from the working fluid port 46 to the communication pipe 51,
Working fluid port 47, inner peripheral groove 53 of upper hole 52, spring receiver
Through the horizontal hole 55 of 54, it is guided on the upper end shaft portion 62 of the movable valve body 31, further, it is guided to the pressure receiving surface portion 45 of the movable valve body 31 through the movable valve body fitting shaft hole 56, and this working fluid is Then, the upper end shaft portion 62 and the pressure receiving surface portion 45 of the movable valve body 31 are pressed downward.

On the other hand, the pressure receiving area of the working fluid pressure that presses the movable valve element 31 upward is the convex part 44 surrounded by the seal member 43.
, And is smaller than the pressure receiving area for pressing the upper end shaft portion 62 and the pressure receiving surface portion 45 downward, so that the force for pressing the movable valve element 31 downward is superior.

Therefore, the movable valve element 31 is switched in the direction of the working fluid chamber 21 due to the unbalance of the working fluid pressure, and the first state in which the convex portion 44 of the movable valve element 31 projects into the working fluid chamber 21. (The state shown in FIG. 1).

In such a reciprocating operation, the neutral stop prevention mechanism 61 is provided with a substantially C-shaped wire spring 65 for supplying the working fluid to the working fluid chamber 21 or discharging the working fluid from the working fluid chamber 21. By biasing the movable valve element 31 to either one of them, the movable valve element 31 is prevented from stopping at a neutral position other than any one of them.

At this time, the center axis 71 of the wire spring 65 functions as a rotation support shaft for the spring receiver 54 on the valve body 24 side, and the end shafts of both ends curved in the directions facing each other. The portion 72 functions as a rotation support shaft for the spring receiver 64 on the movable valve body 31 side.

As described above, the working fluid chamber 21 controlled to supply and discharge the working fluid by the fluid control unit 22 is provided only on one side of the piston 12, and the returning operation of the piston 12 is performed by the return spring.
19, the fluid control unit 22 has the movable valve element 31 that switches instantaneously in conjunction with the operation of the piston 12 by the convex part 44 and the pressure receiving surface part 45, so that the reciprocating motion of the reciprocating actuator High-speed operation can be achieved.

Further, since the working fluid only needs to be supplied to one side of the piston 12, the consumption of the working fluid can be reduced to almost half that of the conventional actuator, and the working fluid supply source such as an air compressor can be reduced in size. Can, and
In the case of the same amount of working fluid consumption as in the past, a reciprocating operation speed almost twice that of the conventional actuator can be obtained.

For example, in a conventional reciprocating actuator for alternately supplying a working fluid to working fluid chambers formed on both sides of a piston, a reciprocating operation of about 200 times / min is a limit. With the reciprocating actuator of (1), a high-speed reciprocating operation close to an oscillation state of about 500 times / minute can be performed.

At this time, the stronger the return spring 19, that is, the greater the spring constant of the return spring 19, the higher the speed of the reciprocating operation.

[0040]

According to the first aspect of the present invention, a working fluid chamber whose supply and discharge of working fluid is controlled by the fluid control unit is provided only on one side of the piston, and the return operation of the piston is performed at a high speed by the return spring. In addition, since the fluid control unit has the movable valve element that switches instantaneously in conjunction with the operation of the piston by the convex part and the pressure receiving surface part, the reciprocating actuator can achieve high-speed reciprocating operation.

Further, since it is sufficient to supply the working fluid to only one side of the piston, the consumption of the working fluid can be greatly reduced as compared with the consumption of the conventional actuator. Further, the reciprocating operation speed can be greatly improved as compared with the conventional actuator.

According to the second aspect of the present invention, the movable valve body is stopped at the neutral position by the substantially C-shaped wire spring in which the central shaft portion and the end shaft portions at both ends function as rotation support shafts. The neutral stop preventing mechanism for avoiding the problem can be formed very simply.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a reciprocating actuator according to an embodiment of the present invention during a piston return operation.

FIG. 2 is a cross-sectional view of the same actuator immediately before the end of a piston return operation.

FIG. 3 is a cross-sectional view when the piston of the actuator is switched to a state in which the piston is operated by a working fluid.

FIG. 4 is a sectional view showing a neutral stop prevention mechanism of the actuator.

[Explanation of symbols]

 11 Cylinder body 12 Piston 13 Rod 19 Return spring 21 Working fluid chamber 22 Fluid control unit 24 Valve body 31 Movable valve body 35 Supply port 36 Discharge port 44 Convex part 45 Pressure receiving surface part 54 One spring receiver 61 Neutral stop prevention mechanism 64 The other Spring holder 65 Wire spring 71 Central shaft 72 End shaft

Claims (2)

[Claims] 1. A cylinder body, a single rod-shaped piston slidably fitted in the cylinder body, a return spring for return operation provided on a rod side of the piston, and a cylinder body. A working fluid chamber provided on the side of the piston without the rod, and a fluid control unit for controlling the supply and discharge of the working fluid to and from the working fluid chamber, the fluid control unit comprising a supply port and a discharge port for the working fluid. And a movable valve body fitted movably in the axial direction of the valve body and communicating one of a supply port and a discharge port of the working fluid with the working fluid chamber. A projecting portion which is pushed by a piston which is protruded into the working fluid chamber and moved by the restoring force of the return spring to actuate the movable valve body in a direction to retreat from the working fluid chamber, and a working flow against the return spring. A pressure-receiving surface portion that receives the fluid pressure of the working fluid guided from the working fluid chamber to the opposite side of the convex portion of the movable valve body from the working fluid chamber at the stroke end position of the piston moved, and operates the movable valve body toward the working fluid chamber. A reciprocating actuator comprising: 2. The movable valve body includes a neutral stop preventing mechanism for preventing the movable valve body from stopping at a neutral position, the neutral stop preventing mechanism includes one spring receiving body provided integrally with the valve body, By bending the other spring receiving body fitted to the movable valve body and the end shafts formed at both ends of the wire with respect to the center shaft formed at the center of the wire in directions opposite to each other. It is formed in a substantially C-shape, and comprises a wire spring in which a central shaft portion is rotatably fitted to one spring receiving body and both end shaft portions are rotatably fitted to the other spring receiving body. The reciprocating actuator according to claim 1.