JPH11303812A - Automatic reciprocating mechanism - Google Patents

Abstract

(57) Abstract: An automatic reciprocating mechanism for reciprocating a cylinder at a predetermined cycle only by a hydraulic mechanism is provided. A first pressure chamber (14) having a small pressure receiving area and a second pressure chamber (15) having a large pressure receiving area are defined at both ends of a piston (13).
And the stopper 17 is slidably penetrated into the spool 18. First and second ports 23 and 28 are provided on the sliding surfaces of the piston 13 and the spool 18, and a first passage 21 selectively connected to the first port 23 is provided in the first pressure chamber 1.
4, the pump port P is always in communication, and the second port 28 and the second pressure chamber 15 are selectively in communication. The first port 23 communicates with the second pressure chamber 15, and when the first port 23 is disconnected from the first pressure chamber 14 at the spool neutral position, the second port 28 is also disconnected from the second pressure chamber 15, When it is displaced either way from that position,
And the second port 23, 28 communicate with one of the pressure chambers reciprocally. The pressure receiving area on the first pressure chamber side of the spool 18 is set smaller than the pressure receiving area on the second pressure chamber side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic reciprocating mechanism for automatically and repeatedly switching a directional control valve.

[0002]

2. Description of the Related Art Conventionally, in order to continuously extend and retract a hydraulic cylinder or the like at a constant cycle, for example, a directional switching valve that operates electromagnetically is used.

When a high pressure is selectively supplied to the left and right oil chambers of a cylinder by a direction switching valve for supplying and discharging hydraulic oil from a hydraulic pressure source, the piston moves in accordance with the hydraulic pressure. The directional control valve performs a switching operation at a constant cycle according to a signal, and repeats and continues the operation of introducing high pressure into one oil chamber and releasing the other oil chamber to the tank side. Thereby, the cylinder repeats the expansion and contraction operation at a constant cycle.

[0004]

However, even if a proportional solenoid valve or an electro-hydraulic servo valve is used as such a hydraulic switching valve, it is not suitable for large flow rate and high pressure control, and the price of the whole system is low. It will be expensive.

An object of the present invention is to provide an automatic reciprocating mechanism that automatically reciprocates at a certain period by a hydraulic mechanism.

[0006]

According to a first aspect of the present invention, a piston is slidably housed in a body, and a first pressure chamber having a small pressure receiving area and a second pressure chamber having a large pressure receiving area are provided at both ends of the piston. A partition is formed, a spool is slidably provided coaxially inside the piston, and a stopper having one end fixed to the body is further coaxially slidably penetrated inside the spool. First and second sliding surfaces
And the first port is provided on the spool.
Selectively connecting the second port to a second passage or a second pressure chamber provided in the spool;
The first passage is always in communication with a pump port formed in the body through the first pressure chamber, and the second passage is always in communication with a tank port formed in the body, while the stopper restricts displacement of the spool to a certain extent. And the first
A port is communicated with the second pressure chamber, and when the first port is disconnected from the first pressure chamber in the spool neutral position, the second port is also disconnected from the second pressure chamber, and from the position, However, when the first and second ports are displaced, the first and second ports are set so that the first and second ports communicate with one of the pressure chambers reciprocally, and the pressure receiving area of the spool on the first pressure chamber side is reduced. It is characterized in that it is set smaller than the pressure receiving area on the second pressure chamber side.

According to a second aspect of the present invention, in the first aspect, a pedestal is provided at an end of the body opposite to the end of the spool facing the second pressure chamber, and these pedestals are provided when the spool comes into contact with the pedestal. An intermediate chamber is formed between the first chamber and the intermediate chamber. The intermediate chamber communicates with the first port.
Communicate with pressure chamber.

In a third aspect based on the first or second aspect, a spring for pressing a piston toward the first pressure chamber is interposed in the second pressure chamber.

In a fourth aspect based on the first to third aspects, the pump port is provided with a variable throttle for controlling an amount of pressure oil introduced into the first pressure chamber.

According to a fifth aspect of the present invention, there is provided the automatic reciprocating mechanism according to the first aspect of the present invention, further comprising a direction switching valve connected to the piston, and controlling the supply and discharge of hydraulic oil to and from the actuator by the direction switching valve. .

In a sixth aspect based on the fifth aspect, the directional control valve is configured to shut off the pair of load ports at the neutral position.

[0012]

In the first invention, when a high pressure is introduced into the first pressure chamber, the pool is displaced toward the second pressure chamber, and the spool comes into contact with the opposite cylinder end wall. When stopped, the second port communicates with the low pressure side, whereby the piston is moved toward the second pressure chamber by being pushed by the high pressure of the first pressure chamber.

When the second port is closed and the first port is opened by the movement of the piston, the second pressure chamber is shut off from the low pressure side and the high pressure is supplied from the first pressure chamber side. Move the spool to the opposite side until it contacts the stopper, and open the first port further. For this reason, the piston starts moving from the second pressure chamber to the opposite first pressure chamber from the difference in the left and right pressure receiving areas.

The movement of the piston eventually narrows the first port, and when the second port opens, the pressure in the second pressure chamber decreases. Therefore, the pressure relationship between the left and right sides of the piston is reversed this time, and the piston moves again toward the second pressure chamber. In this way, Biston automatically repeats the reciprocating movement. In this way, automatic reciprocation can be performed only by supplying hydraulic pressure. Further, the stroke of the reciprocating motion is fixed, so that the stroke does not change even if the reciprocating frequency increases.

According to the second aspect of the invention, by providing a pressure difference between the second pressure chamber and the intermediate chamber via the fixed throttle, when the movement of the piston is reversed, only the spool moves reliably in the opposite direction. It is possible to smoothly switch the hydraulic pressure.

In the third aspect, the piston is held at the initial position by the spring when the operation is stopped, so that the movement can be reliably started from the same direction when the operation is started.

In the fourth invention, the speed of the reciprocating motion can be freely set by adjusting the flow rate by a variable throttle.

According to the fifth aspect, the cylinder corresponding to an arbitrary load can be reciprocated by reciprocating the directional control valve at a constant cycle.

In the sixth aspect, the load can be stopped at the neutral position by using the directional control valve as an all-port block, and the range of application can be expanded.

[0020]

FIG. 1 shows an embodiment of the present invention.

Reference numeral 1A denotes a pump, 1B denotes a tank, 2 denotes a switching valve which is manually or electromagnetically switched, and provided with an automatic reciprocating mechanism 10 which reciprocates by supplying and discharging the hydraulic pressure.

In the automatic reciprocating mechanism 10, a piston 13 is freely slidably housed in a sliding hole 12 of a body 11, and a rod 19 integrally connected to the piston 13 projects outward from an end of the body 11. . And by the piston 13,
A pressure chamber 14 having a small pressure receiving area and a pressure chamber 15 having a large pressure receiving area are formed on both sides thereof.

A coaxial bottomed hole 16 is formed inside the piston 13 and the rod 19, and a stopper 17 projecting inward from the end of the body 11 is inserted into the bottomed hole 16. A spool 18 is slidably fitted on the outside. The large diameter portion 25 of the stopper 17 and the outer diameter of the spool 18 are formed to be the same,
6 is freely slidably inserted.

A pump port P and a tank port T are disposed at a predetermined interval in the body 11, and pressurized oil is supplied and discharged through the switching valve 2. A variable throttle 20 is provided at the pump port P so that the supply flow rate can be adjusted.

On both sides of the piston 13, a first passage 21 communicating with the pump port P via a pressure chamber 14 on the outer periphery thereof is provided.
And a second passage 22 that is always in communication with the tank port T is formed therethrough, and the first passage 21 is opened and closed by the relative position of the spool 18 and the piston 13. A first port 23 capable of connecting to the first passage 21 is formed in the spool 18, and the first port 23 is provided through a gap between a small diameter portion 24 formed on the outer periphery of the stopper 17 and the inner periphery of the spool. It communicates with the pressure chamber 15. Further, inside the stopper 17, there is provided a through passage 27 which communicates the small diameter portion 24 with the internal chamber 26 facing the right end of the stopper 17.

On the other hand, an enlarged flange portion 29 is formed at the left end of the spool 18, and a second port 28 is formed between the spool 18 and the sliding surface of the piston 13 by the flange portion 29. When 29 penetrates into the enlarged diameter hole 30 on the inner circumference of the piston, the communication between the pressure chamber 15 and the second passage 22 is cut off, and when it escapes, the pressure chamber 15 communicates with the second passage 22.

A pedestal 32 protrudes from the end wall 31 of the body 11 so as to face the flange portion 29 of the spool 18, and a cylindrical portion 33 for receiving the flange portion 29 is formed on the pedestal 32. When an intruder enters the cylindrical portion 33, an intermediate chamber 34 is formed therebetween. Also pedestal 3
2, a through hole 35 is opened, and the through hole 35 communicates with the pressure chamber 15 via a throttle 36. Piston 1 in pressure chamber 15
A spring 37 for urging the valve 3 rightward in the drawing (toward the pressure chamber 14) is provided.

Here, the operation of the above configuration will be described with reference to FIGS.

First, the area of the left end of the piston 13 is A1,
If the area of the bottomed hole 26 is A2, the area of the right end of the piston 13 is A3, the area of the left end of the spool 18 is A4, and the area of the right end of the spool is A5, A1 + A2> 2 × A3, and A
It is set so that 4 = 2 × A5.

As shown in FIG. 1, when the switching valve 2 is switched and the pump port P is switched to the tank side, the pressure in the pressure chamber 14 is equal to the tank pressure (the same as the pressure chamber 15 on the left side). Assuming that the pressure is zero), the spring 37
As a result, the piston 13 is pressed to the right end wall. The position of the spool 18 is not limited to the illustrated position,
Take any position.

From this state, the switching valve 2 is switched, and the pump port P is maintained so that a high pressure is introduced.

As a result, the pressure chamber 14 becomes high pressure. At this time, the pressure chamber 15 and the internal chamber 26 communicating therewith are pushed to the left until the spool 18 immediately contacts the pedestal 32 due to the tank pressure. Spring 37
Begins to move to the left (see FIG. 2).

As the piston 13 moves to the left,
The first passage 21 starts communicating with the first port 23 and the second port 28 closes the communication with the pressure chamber 15.

In the neutral position shown in FIG. 3, the first port 23 and the second port 28 are both closed, and when the piston 13 moves to either one from this position, one of the ports reciprocally moves. It opens and the other closes.

When the piston 13 moves in the same direction slightly from the neutral position due to the pressure difference between the left and right chambers, the first port 23 communicates with the passage 21 and the second port 28 is cut off from the pressure chamber 15, Therefore, the high pressure is transmitted from the intermediate chamber 34 to the left pressure chamber 15.

However, because of the presence of the fixed throttle 36, the pressure in the pressure chamber 15 does not immediately rise to the same level as the pressure chamber 14. During this time, when the pressure applied to the left end of the spool 18 becomes higher than half the pressure applied to the right end, only the spool 18 is moved from the left and right pressure receiving area differences as shown in FIG.
Move to the right until it touches 7.

As a result, the first port 23 is widely opened, and the intermediate chamber 34 and the pressure chamber 15 are in direct communication, and the pressure in the pressure chamber 15 is also increased by the pressure oil from the pressure chamber 14. In this way, the pressure applied to the left end of the piston 13 increases and eventually becomes the same, but since the pressure receiving area on the pressure chamber 15 side is larger than the pressure receiving area of the pressure chamber 14, the piston 13 Starts moving to the right.

When the piston 13 moves to the position shown in FIG. 5 and the second port 28 starts communicating with the pressure chamber 15 on the low pressure side and shuts off the first port 23 from the high pressure side, the pressure in the pressure chamber 15 is reduced. It is going down. When the pressure in the pressure chamber 15 becomes half that of the pressure chamber 14, the forces at both ends of the spool 18 are balanced due to the pressure receiving area, but the piston 13 moves further to the right due to the area difference. As a result, the second port 28 communicates greatly with the pressure chamber 15, and when the pressure in the pressure chamber 15 further decreases, the balance of the spool 18 is lost.
The spool 18 moves to the left as shown in FIG.

As a result, the pressure chamber 15 returns to the initial state.
Becomes low pressure, and the piston 13 starts to move again in the opposite direction, that is, toward the left side. Thus, the piston 13 automatically repeats the reciprocating motion.

An example in which the directional control valve is continuously reciprocated using the above-described automatic reciprocating mechanism will be described.

As shown in FIG. 6, the directional control valve 50 has a spool 52 slidably inserted into a valve body 51,
The left end of the spool 52 in the figure is connected to the rod 19 of the automatic reciprocating mechanism. Therefore, the spool 52 reciprocates left and right integrally with the rod 19.

The body 51 of the directional control valve 50 has a load port 56 and 57
Are provided, and tank ports 58 and 5 are provided on both outer sides thereof.
High pressure from the pump port 55 is selectively supplied to the left and right load ports 56 and 57 by the reciprocating motion of the spool 52, and the tank port 58 is supplied from one of the other.
Alternatively, the hydraulic oil is discharged to 59.

The oil chambers 62 and 63 of the cylinder 61 are connected to the load ports 56 and 57. The piston 64 moves in one direction when a high pressure acts on one side, and moves in the opposite direction when a high pressure acts on the other. Moves.

Accordingly, when the automatic reciprocating mechanism is operated while the pump port 55 is maintained at a high pressure and the tank ports 58 and 59 are maintained at a low pressure, the spool 52 reciprocates integrally with the rod 14, whereby, for example, 5
When 2 moves to the left from the position shown in the figure, first, the pump port 55 is connected to the left load port 57, the opposite load port 56 is connected to the tank port 58, and the cylinder 61 operates in the piston contracting direction. When the spool 52 further moves to the left and passes the neutral position, the pump port 55 and the load port 56 are connected, the opposite load port 57 is connected to the tank port 59, and the cylinder 61 operates in the piston extension direction. .

Conversely, when the spool 52 moves to the right and passes the neutral position, the load port 57 is connected to the pump port 55, and the other load port 56 is connected to the tank port 58. Operates in the opposite shrink direction.

When the directional control valve 50 is at the maximum right position (the state shown in the figure), both the load ports 56 and 57 are in the shut-off state, that is, the all-port block, and in this state, the cylinder 61 extends from that position. It keeps its position without shrinking. This position corresponds to the state of the automatic reciprocating mechanism 10 shown in FIG.

As described above, according to the present invention, automatic reciprocation can be performed only by supplying hydraulic pressure. In addition, the speed of the reciprocation is adjusted by adjusting the flow rate using a variable throttle.
Can be set freely. Further, the stroke of the reciprocating motion is fixed, so that the stroke does not change significantly even if the reciprocating frequency increases.

It should be noted that a load that does not exceed the thrust of the piston 13 is also operated as a cylinder that directly reciprocates it. Further, as described above, the cylinder corresponding to an arbitrary load can be reciprocated by reciprocating the direction switching valve 50 at a constant cycle via the rod 14 as described above.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view illustrating an operating state.

FIG. 3 is a cross-sectional view illustrating an operating state.

FIG. 4 is a cross-sectional view illustrating an operating state.

FIG. 5 is a cross-sectional view illustrating an operating state.

FIG. 6 is a cross-sectional view showing another embodiment.

[Explanation of symbols]

 Reference Signs List 1A Pump 2 Switching valve 3 Cylinder 4A Oil chamber 4B Oil chamber 10 Automatic reciprocating mechanism 13 Piston 14 First pressure chamber 15 Second pressure chamber 17 Stopper 18 Spool 21 First passage 22 Second passage 23 First port 28 Second port

Claims (6)

[Claims] A piston is slidably housed in a body, and a first pressure chamber having a small pressure receiving area and a second pressure chamber having a large pressure receiving area are formed at both ends of the piston, and are coaxially formed inside the piston. The spool is slidably provided freely, and a stopper having one end fixed to the body is further coaxially slidably penetrated into the inside of the spool, and first and second sliding surfaces are provided on the sliding surface of the piston and the spool. A second port for selectively connecting the first port to a first passage provided in the spool;
Port is selectively connected to a second passage or a second pressure chamber provided in the spool, and the first passage is always in communication with a pump port formed in the body via the first pressure chamber.
The passage always communicates with a tank port formed in the body, while the stopper restricts displacement of the spool to a certain extent, and communicates the first port with the second pressure chamber. When disconnected from the first pressure chamber, the second port is also disconnected from the second pressure chamber, and when displaced from either of the positions, the first and second ports are reciprocally opposed to each other. Setting the first and second port positions so as to communicate with the room,
An automatic reciprocating mechanism wherein the pressure receiving area of the spool on the first pressure chamber side is set smaller than the pressure receiving area of the spool on the second pressure chamber side. 2. A pedestal is provided at an end of the body opposite to an end of the spool facing the second pressure chamber, and an intermediate chamber is formed between the spool and the pedestal when the spool comes into contact with the pedestal. 2. The automatic reciprocating mechanism according to claim 1, wherein the chamber communicates with the first port while communicating with a second pressure chamber via a fixed throttle provided on a pedestal. 3. The automatic reciprocating mechanism according to claim 1, wherein a spring for pressing a piston toward the first pressure chamber is interposed in the second pressure chamber. 4. The automatic reciprocating mechanism according to claim 1, wherein a variable throttle for controlling an amount of pressure oil introduced into the first pressure chamber is interposed in the pump port. 5. The automatic reciprocating motion according to claim 1, further comprising a direction switching valve connected to a piston of the automatic reciprocating mechanism, wherein the direction switching valve controls the supply and discharge of hydraulic oil to and from the actuator. mechanism. 6. The automatic reciprocating mechanism according to claim 5, wherein said directional control valve is configured to shut off a pair of load ports at a neutral position thereof.