JP3764819B2 - Automatic reciprocating mechanism - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic reciprocating mechanism for automatically and repeatedly switching a direction switching valve, for example.
[0002]
[Prior art]
Conventionally, in order to continue the expansion and contraction operation of a hydraulic cylinder or the like with a constant cycle, for example, a direction switching valve that operates electromagnetically is used.
[0003]
When a high pressure is selectively supplied to the left and right oil chambers of the cylinder by the direction switching valve that supplies and discharges hydraulic oil from the hydraulic source, the piston moves according to the hydraulic pressure. The direction switching valve performs switching operation at a constant cycle by a signal, repeats and continues the operation of introducing a high pressure into one oil chamber and releasing the other oil chamber to the tank side. As a result, the cylinder repeatedly expands and contracts at a constant cycle.
[0004]
[Problems to be solved by the invention]
However, even if, for example, a proportional solenoid valve or an electrohydraulic 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 entire system becomes expensive.
[0005]
An object of the present invention is to provide an automatic reciprocating mechanism that automatically continues reciprocating at a certain cycle by a hydraulic mechanism.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, a piston is slidably accommodated in a body, 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 the piston is formed inside the piston. A small diameter portion of a coaxially stepped spool is slidably inserted, and the large diameter portion of the spool is freely slid within a certain range within the body, and a sliding surface with the piston on the spool The first port is selectively connected to the first passage provided in the piston, and the second port connects the second passage provided in the piston to the second pressure. The first passage is always in communication with a pump port formed in the body via the first pressure chamber, the second passage is always in communication with a tank port formed in the body, and the spool In the neutral position, the first port is the first pressure chamber When substantially shut off, the second port is also substantially shut off from the second pressure chamber, and when displaced from either position, the first and second ports communicate with one of the pressure chambers contrary to each other. The first and second port positions are set so that the end face of the small-diameter portion of the spool faces the piston inner chamber that is always in communication with the first pressure chamber, and the pressure chamber in the body faces the end face of the large-diameter portion of the spool. Is always communicated with the first port via a through passage provided in the spool, and a third port branched from the middle of the through passage and always communicated with the second pressure chamber is provided.
[0007]
In a second aspect based on the first aspect, the second pressure chamber is provided with a spring that presses the piston toward the first pressure chamber.
[0008]
According to a third invention, in the first or second invention, a variable throttle for controlling the amount of pressure oil introduced into the first pressure chamber is interposed in the pump port.
[0009]
According to a fourth aspect of the invention, there is provided a direction switching valve connected to a rod coupled to the piston of the automatic reciprocating mechanism of the first aspect of the invention, and the supply and discharge of hydraulic oil to and from the actuator is controlled by the direction switching valve. To do.
[0010]
[Operation and effect of the invention]
In the first invention, when a high pressure is introduced into the first pressure chamber, the spool is displaced by a certain amount toward the second pressure chamber, and the piston is pushed by the high pressure in the first pressure chamber so that the piston is on the low pressure side. Move toward the second pressure chamber.
[0011]
When the second port is closed and the first port is opened due to the movement of the piston, the second pressure chamber is shut off from the low pressure side, and high pressure is supplied from the first pressure chamber side through the through passage. As a result, the spool first moves by a certain amount to the opposite side based on the pressure receiving area difference between the large diameter portion and the small diameter portion, and opens the first port more greatly. For this reason, the second pressure chamber has the same pressure as the first pressure chamber, but the piston starts to move from the second pressure chamber toward the opposite first pressure chamber due to the difference between the left and right pressure receiving areas. .
[0012]
The first port is eventually throttled by the movement of the piston, and when the second port is opened, the pressure in the second pressure chamber decreases. For this reason, the pressure relationship between the left and right of the spool is reversed, the spool moves to the opposite side by a certain amount, and the first port is completely closed. For this reason, the second pressure chamber becomes low pressure, and the piston moves again toward the second pressure chamber. In this way, the piston automatically repeats reciprocating motion. Thus, automatic reciprocation can be performed only by continuously supplying high pressure to the first pressure chamber. Further, the stroke amount of the reciprocating motion is constant, so that the stroke does not change greatly even if the reciprocating frequency is increased.
[0013]
In the second invention, since the piston is held at the initial position by the spring when the operation is stopped, the movement can be surely started from the same direction when the operation is started.
[0014]
In the third invention, the speed of the reciprocating motion can be freely set by adjusting the flow rate with a variable throttle.
[0015]
In 4th invention, the cylinder corresponding to arbitrary loads can be reciprocated by reciprocating a direction switching valve with a fixed period.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention.
[0017]
1A is a pump, 1B is a tank, and 2 is a switching valve that is switched manually or electromagnetically. An automatic reciprocating mechanism 10 that reciprocates by supplying and discharging the hydraulic pressure is provided.
[0018]
In the automatic reciprocating mechanism 10, a piston 13 is slidably accommodated in a sliding hole 12 of a body 11, and a rod 19 integrally coupled to the piston 13 protrudes from an end of the body 11 to the outside. The piston 13 forms a pressure chamber 14 having a small pressure receiving area and a pressure chamber 15 having a large pressure receiving area on both sides thereof.
[0019]
A bottomed hole 16 is coaxially formed inside the piston 13 and the rod 19, and a small diameter portion of a spool 18 formed in a stepped shape is slidably inserted into the bottomed hole 16. The large-diameter portion 29 at the other end is freely slidably received in the sliding hole 17 provided coaxially in the body 11.
[0020]
A pump port P and a tank port T are disposed in the body 11 with a predetermined interval, and pressure oil is supplied and discharged through the switching valve 2. The pump port P is provided with a variable throttle 20 so that the supply flow rate can be adjusted.
[0021]
A first passage 21 communicating with the pump port P via a pressure chamber 14 on the outer periphery of the piston 13 and a second passage 22 constantly communicating with the tank port T are formed through both sides of the piston 13 in the radial direction. The first and second passages 21 and 22 open into the bottomed hole 16 inside the piston 13. The first passage 21 keeps the internal chamber 25 on the spool end face side of the bottomed hole 16 in a state of continuous communication with the pressure chamber 14.
[0022]
The spool 18 is formed with a first port 23 that can be selectively connected to the first passage 21, and the first port 23 penetrates the inside of the spool 18 to the opposite end in the axial direction. 24 and a third port 26 communicating with the pressure chamber 15 branches from the middle of the through passage 24.
[0023]
Further, an annular groove forming a second port 27 is formed on the outer periphery of the spool 18, and the second port 22 is selectively switched and connected to the pressure chamber 15 by the second port 27.
[0024]
On the other hand, the stepped large-diameter portion 29 at the left end of the spool 18 is freely slidably accommodated in the sliding hole 17 within a certain range, and the pressure receiving area A3 at the left end of the spool 18 is larger than the pressure receiving area A4 at the right end. It is getting bigger. An annular chamber 30 formed around the spool 18 on the smaller diameter side than the large diameter portion 29 is connected to the pressure chamber 28 facing the end surface of the large diameter portion 29, and is a passage formed in the body 11. The tank port T is always in communication via 31.
[0025]
A spring 35 that presses the piston 13 is interposed in the pressure chamber 15.
[0026]
Here, the operation of the above configuration will be described with reference to FIGS.
[0027]
First, assuming that the area of the left end of the piston 13 is A1 and the area of the right end is A2, the area obtained by adding the area A1 and the spool area A4 is set to be larger than the spool area A2. Further, the spool area A3 is set to be twice that of A4 (for convenience of explanation, it is set to twice, but this is not restrictive).
[0028]
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 of the pressure chamber 14 is the same as the pressure chamber 15 on the left side (the pressure is zero). The piston 13 is pressed to the right end wall by the spring 35. Note that the position of the spool 18 is not limited to the illustrated position, and may be any position.
[0029]
From this state, the switching valve 2 is switched to hold the high pressure to the pump port P.
[0030]
As a result, the pressure chamber 14 becomes high pressure. At this time, because the pressure chamber 15 and the annular chamber 30 are tank pressure, the spool 18 is immediately pushed to the left, and at the same time, the piston 13 moves against the spring 35 to the left. Start (see Figure 2).
[0031]
Note that when the spool 18 is positioned at the left end, the third port 26 maintains a communication state with the pressure chamber 15 through a fine throttle.
[0032]
In the process of moving the piston 13 to the left, the first passage 21 starts to communicate with the first port 23 and the second port 27 closes the communication with the pressure chamber 15.
[0033]
In the position of FIG. 3, both the first port 23 and the second port 27 are slightly opened, and when the piston 13 moves to either one from this position, one of the ports is further opened contrary to the other, Has become more closed.
[0034]
When the second port 27 is further closed and the first port 23 is further opened, the pressure in the pressure chamber 28 starts to rise, and the pressure in the pressure chamber 28 is the pressure in the internal chamber 25 (the same pressure as the pressure chamber 14). The force at both ends of the spool 18 balances when the pressure rises to half of the pressure, but the pressure in the pressure chamber 15 is lower than that in the inner chamber 25 and does not reach half yet at that point, and the piston 13 moves to the left as it is. Continue moving.
[0035]
When the pressure in the pressure chamber 28 rises above half of the pressure in the internal chamber 25, the spool 18 immediately moves to the right end of the annular chamber 30 as shown in FIG.
[0036]
As a result, the first port 23 is greatly opened and the third port 26 is also in communication with the pressure chamber 15, so that the pressure in the pressure chamber 15 rises to the same pressure due to the high pressure in the pressure chamber 14. As a result, the piston 13 starts to move in the opposite direction, that is, rightward by the pressing force from the pressure chamber 15 having a large pressure receiving area.
[0037]
In the process in which the piston 13 moves to the right side, the communication of the first port 23 to the high pressure side is reduced, and the pressure chamber 15 is opened to the low pressure side by the second port 27 as shown in FIG. The pressures in the chamber 28 and the pressure chamber 15 decrease, and when the pressure decreases to half of the high pressure side, the pressures at both ends of the spool balance, but the piston 13 continues to move further to the right due to the pressure receiving area difference.
[0038]
As a result, the second port 27 opens further and the pressure in the pressure chamber 15 and the pressure chamber 28 further decreases, so that the spool 18 is turned to the left as shown in FIG. It moves immediately until it comes into contact with the body 11.
[0039]
In this state, the first port 23 is closed, and the second port 27 connects the pressure chamber 15 to the tank side, so that the piston 13 is directed to the left opposite to the conventional state under the high pressure of the pressure chamber 14. Start moving. In this way, the piston 13 automatically repeats reciprocating motion.
[0040]
An example in which the direction switching valve is continuously reciprocated using the above automatic reciprocating mechanism will be described.
[0041]
As shown in FIG. 6, in the direction switching valve 50, a spool 52 is slidably inserted into a valve body 51, and 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.
[0042]
The body 51 of the direction switching valve 50 is provided with load ports 56 and 57 on the left and right sides of the pump port 55 as the center, and further with tank ports 58 and 59 on both outer sides thereof. The high pressure from 55 is selectively supplied to the left and right load ports 56 and 57, and hydraulic oil is discharged from either one to the tank port 58 or 59.
[0043]
Oil chambers 62 and 63 of a cylinder 61 are connected to the load ports 56 and 57, and when a high pressure is applied to one, the piston 64 moves in one direction, and when a high pressure is applied to the other, the piston 64 moves in the opposite direction. .
[0044]
Therefore, when the automatic reciprocating mechanism is operated with the pump port 55 kept at a high pressure and the tank ports 58 and 59 kept at a low pressure, the spool 52 reciprocates integrally with the rod 14. 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 contraction 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 load port 57 on the opposite side is connected to the tank port 59, and the cylinder 61 operates in the piston extension direction. .
[0045]
On the other hand, 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, so that the cylinder 61 is contracted in the opposite direction. Operate in the direction.
[0046]
When the directional control valve 50 is in the maximum right position (shown), both the load ports 56 and 57 are cut off, that is, the all-port block. In this state, the cylinder 61 extends and contracts from that position. Hold that position without. This position corresponds to the state of the automatic reciprocating mechanism 10 shown in FIG.
[0047]
Thus, according to the present invention, automatic reciprocation can be performed only by supplying hydraulic pressure. The reciprocating speed can be freely set by adjusting the flow rate with the variable throttle 20. Further, the stroke of the reciprocating motion is fixed, so that the stroke does not change greatly even if the reciprocating frequency is increased.
[0048]
In addition, about the load which does not exceed the thrust of piston 13, it is made to operate | move as a cylinder which reciprocates this directly. Of course, 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.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view for explaining the operating state.
FIG. 3 is a cross-sectional view illustrating the operating state.
FIG. 4 is a cross-sectional view illustrating the operating state.
FIG. 5 is a cross-sectional view illustrating the operating state.
FIG. 6 is a cross-sectional view showing another embodiment.
[Explanation of symbols]
1A Pump 2 Switching valve 10 Automatic reciprocating mechanism 13 Piston 14 Pressure chamber 15 Pressure chamber 18 Spool 21 First passage 22 Second passage 23 First port 24 Through passage 25 Internal chamber 27 Second port 28 Pressure chamber

Claims (4)

A piston is slidably mounted in the body, and a first pressure chamber having a small pressure receiving area and a second pressure chamber having a large pressure receiving area are defined at both ends of the piston, and are coaxially stepped inside the piston. A small-diameter portion of the spool is slidably inserted, and the spool large-diameter portion is slidably accommodated within a certain range within the body, and the spool opens to a sliding surface with the piston. A second port is provided, the first port is selectively connected to the first passage provided in the piston, and the second port is selectively switched from the second pressure chamber to the second passage provided in the piston. The first passage is always in communication with a pump port formed in the body via the first pressure chamber, the second passage is always in communication with a tank port formed in the body, and the first passage is in the neutral position of the spool. The port is substantially blocked from the first pressure chamber The second port is also substantially disconnected from the second pressure chamber, and when displaced from either position, the first and second ports communicate with one of the pressure chambers in a contradictory manner. 1. The second port position is set so that the end surface of the small-diameter portion of the spool faces the piston inner chamber that is always in communication with the first pressure chamber, and the pressure chamber in the body that faces the end surface of the large-diameter portion of the spool An automatic reciprocating mechanism characterized in that a third port is provided which always communicates with a port through a through passage provided in a spool and which branches from the middle of the through passage and communicates with the second pressure chamber at all times. The automatic reciprocating mechanism according to claim 1, wherein a spring for pressing the piston toward the first pressure chamber is interposed in the second pressure chamber. The automatic reciprocating mechanism according to claim 1 or 2, wherein a variable throttle for controlling an amount of pressure oil introduced into the first pressure chamber is interposed in the pump port. An automatic reciprocating mechanism comprising a directional switching valve connected to a rod coupled to a piston of the automatic reciprocating mechanism according to claim 1, wherein the supply and discharge of hydraulic fluid to and from the actuator is controlled by the directional switching valve. .

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