JP3764582B2 - Automatic switching valve device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an automatic switching valve that automatically and repeatedly expands and contracts a cylinder.
[0002]
[Prior art]
Conventionally, for example, a switching valve as shown in FIG. 6 is used to continue the expansion and contraction operation of the hydraulic cylinder or the like with a constant cycle.
[0003]
A switching valve 2 for supplying and discharging hydraulic oil from the hydraulic source 1 is provided. When high pressure is selectively supplied to the oil chambers 4A and 4B of the cylinder 3 by the switching valve 2, the piston 5 is changed according to the hydraulic pressure. Move. For example, the switching valve 2 performs switching operation at a constant cycle by a signal (not shown), repeatedly introduces a high pressure into one oil chamber 4A, and releases the other oil chamber 4B to the tank side. Thereby, the cylinder 3 repeats the expansion and contraction operation 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 switching valve that performs switching operation in a certain cycle only by a hydraulic mechanism, and an object thereof is to solve such a problem.
[0006]
[Means for Solving the Problems]
In the first invention, a main spool is slidably mounted in a valve body, first and second pressure chambers are provided at both ends of the main spool, and reciprocating displacement is performed according to a pressure difference between the pair of pressure chambers. The main spool is configured so that the pump port and the tank port are selectively switched and connected to the pair of cylinder ports respectively, while the main spool is coaxially slidably accommodated in the pilot spool, Both ends of the pilot spool protrude from both sides of the main spool so as to be able to come into contact with stoppers on the inner wall of the valve body, while the pilot spool selectively communicates with the first pressure chamber according to the displacement. And a second port that is selectively in communication with the second pressure chamber, and the first port is in the pilot spool neutral position. When the first port is disconnected from the first pressure chamber, the second port is also disconnected from the second pressure chamber, and when displaced from either position, the first and second ports are either The first and second port positions are set so as to communicate with the pressure chamber, the first port is always in communication with the second pressure chamber, and the second port is connected to the low pressure side port of the main spool. The first pressure chamber is connected to the low pressure side and the first pressure chamber is connected to the high pressure side, while the pressure receiving area on the first pressure chamber side of the main spool and pilot spool is smaller than the pressure receiving area on the second pressure chamber side. To do.
[0007]
In a second aspect based on the first aspect, the first pressure chamber is connected to the high pressure side via a variable throttle.
[0008]
According to a third aspect, in the first or second aspect, the pressure receiving area on the first pressure chamber side of the main spool and the pilot spool is set to ½ of the pressure receiving area on the second pressure chamber side.
[0009]
In a fourth aspect based on the first to third aspects, the first pressure chamber is provided with an auxiliary piston as a stopper that protrudes to receive a pressure of the pressure chamber and press the pilot spool by a predetermined amount. .
[0010]
According to a fifth invention, in the first to fourth inventions, when the main spool is displaced to the maximum extent toward the auxiliary piston, the cylinder port is in a blocking position with respect to all of the pump port and the tank port. To.
[0011]
According to a sixth invention, in the first to fifth inventions, a spring for biasing the main spool toward the first pressure chamber is provided.
[0012]
In a seventh aspect based on the first to sixth aspects, the second pressure chamber is provided with a stopper that contacts the pilot spool, and the stopper is connected to the first port opened on the end surface of the pilot spool. A passage that can be connected to the through passage is formed, and this passage communicates with the second pressure chamber via a fixed throttle.
[0013]
[Operation and effect of the invention]
In the first invention, when high pressure is introduced into the first pressure chamber, both the main spool and the pilot spool are displaced toward the second pressure chamber, and the pilot spool comes into contact with the stopper on the opposite cylinder end wall. The pilot spool is switched by the continued movement of the main spool, the second port is closed, the second pressure chamber is shut off from the low pressure side, and the first port is opened to stop the first pressure chamber. Side high pressure is introduced into the second pressure chamber. As a result, the main spool and the pilot spool are integrally displaced to the opposite side. When the pilot spool comes into contact with the stopper of the cylinder end wall on the opposite side and stops, the pilot spool is switched by the continuous movement of the main spool in the same direction, the first port is closed, and the low pressure side is closed. The second port that communicates opens. As a result, the main spool and the pilot spool are again displaced in opposite directions, and such reciprocating motion is continued.
[0014]
With such reciprocation of the main spool, a pair of cylinder ports are selectively switched between the pump port and the tank port, thereby controlling the supply and discharge of hydraulic oil and reciprocating the cylinder connected to the cylinder port. Be made.
[0015]
During this reciprocating movement, the main spool is always displaced to the left and right ends, so that the spool stroke does not become small even if the reciprocating frequency is increased, so that the high pressure and the low pressure can always be switched reliably.
[0016]
In the second invention, by adjusting the control flow rate introduced into the first pressure chamber, the displacement speed of the main spool, in other words, the frequency can be changed, and the switching operation can be performed at a frequency as required.
[0017]
In the third aspect of the invention, the pressure receiving area on the second pressure chamber side is doubled with respect to the first pressure chambers of the main spool and the pilot spool, so that hydraulic fluid is supplied from the first pressure chamber to the second pressure chamber. The speed when shrinking while discharging into the chamber is the same as the speed when expanding the first pressure chamber, and the reciprocating speed can be made the same.
[0018]
In the fourth and fifth aspects of the invention, the main spool and the pilot spool are moved to the initial position by the auxiliary piston when the control is started, and the main spool is displaced to the all-port lock position by the backward movement of the auxiliary piston when the control is stopped. The degree of freedom is increased accordingly.
[0019]
In the sixth aspect of the invention, when the pressure is released when the control is stopped, the main spool is displaced by the spring toward the first pressure chamber to the movement limit, and can be reliably returned to the initial position.
[0020]
In the seventh aspect of the invention, when the pilot spool comes into contact with the stopper, the pressure is transmitted through the fixed throttle thereafter, so that a differential pressure is generated between the second pressure chamber and the movement of the pilot spool is ensured. Can be controlled.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows an embodiment of the present invention.
[0022]
1A is a pump, 1B is a tank, 2 is a switching valve that switches manually or electromagnetically, 3 is a cylinder, 4A and 4B are oil chambers, 5 is a piston, and the oil chambers 4A and 4B of the cylinder 3 have high and low pressures. And an automatic switching valve 10 for selectively extending and contracting the cylinder 3 in a predetermined cycle.
[0023]
In the automatic switching valve 10, a main spool 13 is slidably accommodated in a sliding hole 12 of the valve body 11, and a pilot spool 14 is coaxially and freely slidably inserted into the main spool 13.
[0024]
An auxiliary cylinder 15 is formed at the right end of the valve body 11 in the figure, and an auxiliary piston 16 is disposed on the auxiliary cylinder 15. A rod 17 provided integrally with the auxiliary piston 16 contacts the right end of the pilot spool 14. It touches.
[0025]
A first pressure chamber 18 is formed at the end of the sliding hole 12 located on the right side of the main spool 13, and a second pressure chamber 19 is formed on the left side, and is interposed in the left pressure chamber 19. The main spool 13 is urged to the right by the spring 20.
[0026]
The valve body 11 is provided with a pump port P1 at the center, a pair of cylinder ports C1 and C2 on both sides thereof, and a pair of tank ports T1 and T2 located on both outer sides thereof.
[0027]
As will be described later, the pump port P1 is connected to the pump 1A via the switching valve 2, and the tank ports T1 and T2 are connected to the tank 1B. The cylinder ports C1 and C2 are connected to the oil chambers 4A and 4B of the cylinder 3.
[0028]
In order to selectively connect the pump port P1 and the tank ports T1 and T2 to the cylinder ports C1 and C2, an annular supply port A is provided on the outer periphery of the main spool 13, and a load port B1 is provided on both sides thereof. And a load port B2 are formed. A return port R communicating with the left pressure chamber 19 is provided on the side of the load port B1.
[0029]
A control port P2 into which a control pressure is introduced is provided further outside the tank port T2 on the right side of the valve body 11, and a variable throttle 22 is provided to adjust the flow rate of the control port P2. The high pressure that has passed is introduced into the right pressure chamber 18.
[0030]
The auxiliary piston 16 is provided with a through passage 23 that penetrates the rod 17 in the axial direction, and guides the control pressure of the pressure chamber 18 to the cylinder chamber 15 </ b> A on the right side of the piston 16. The cylinder chamber 15B on the left side of the piston 16 communicates with the tank port T2 via a passage 24 provided in the valve body 11.
[0031]
The pilot spool 14 inserted coaxially into the main spool 13 is formed with swelled portions 25 and 26 at both ends thereof, thereby preventing further displacement of the pilot spool 14.
[0032]
An annular port 27 that selectively communicates with the pressure chamber 18 is formed on the outer periphery near the right end of the pilot spool 14, and an annular port 28 that selectively communicates with the pressure chamber 19 is also formed near the left end. . These ports 27 and 28 close together when the pilot spool 14 is in a neutral position with respect to the main spool 13, but when the pilot spool 14 is displaced slightly to the right from that position, the annular port 27 communicates with the pressure chamber 18, and conversely When displaced to the left, the annular port 28 communicates with the pressure chamber 19. A through passage 30 that penetrates the pilot spool 14 in the axial direction is connected to the port 27, and always communicates with the left pressure chamber 19 through the through passage 30.
[0033]
The pressure chamber 19 is provided with a stopper 33 that comes into close contact with the left end surface of the pilot spool 14 when the pilot spool 14 is displaced. The stopper 33 is provided with a passage 34 that opens on the extension of the through passage 30. The pressure chamber 19 communicates with a fixed throttle 35 interposed therebetween.
[0034]
Further, the shaft hole 37 of the main spool 13 that accommodates the pilot spool 14 is formed as a stepped hole, and the diameter of the portion communicating with the left pressure chamber 19 is increased. The outer diameter of the left end is increased, so that the cross-sectional area A3 at the left end is set larger than the cross-sectional area A4 at the right end. Here, for example, the cross-sectional area A3 is set to be twice that of A4.
[0035]
Similarly, the main spool 13 and its sliding hole 12 are also formed in a stepped shape, and the cross-sectional area A1 at the left end of the main spool 13 is set larger than the cross-sectional area A2 at the right end. Here, the cross-sectional area A1 is set to be larger than twice A2, but the range exceeding twice is appropriately set as necessary.
[0036]
Next, the operation will be described with reference to FIGS. 1 and 2 to 5.
[0037]
When the state shown in FIG. 1, that is, when the switching valve 2 is held on the drain side, all the ports are drained on the low pressure side. Therefore, the main spool 13 is illustrated in FIG. It has moved to the right end.
[0038]
In this position, the cylinder ports C1 and C2 are held at a shut-off position that does not communicate with the pump port P1 and any of the tank ports T1 and T2, and become a so-called all-port block position. Can be restrained.
[0039]
When the switching valve 2 is switched from this state, high pressure is led to the pump port P1 and the control port P2, and the tank ports T1 and T2 are connected to the tank side. Due to the control pressure acting on the control port P2, the pressure in the pressure chamber 18 rises, which acts on the cylinder chamber 15A on the right side of the auxiliary piston 16, thereby pushing the auxiliary piston 16 to the left, and at the same time The main spool 13 and the pilot spool 14 are also pushed leftward by this pressure. Since the pressure chamber 19 on the opposite side is connected to the tank side, the pressing force to the left overcomes the repulsive force of the spring 20 and the main spool 13 and the pilot spool 14 start moving to the left integrally. .
[0040]
As shown in FIG. 2, the stroke of the auxiliary piston 16 is constant and stops immediately. Thereafter, the main spool 13 and the pilot spool 14 are further displaced integrally by the pressure acting on the pressure chamber 18. This is the initial operation at the start of operation. Since the auxiliary piston 16 remains stopped at this position after the operation is started, the subsequent operation is repeated using the auxiliary piston 16 as a stopper as described later (see FIG. 5).
[0041]
Due to the displacement of the main spool 13, the pump port P1 communicates with the cylinder port C2 via the load port B2, and the other cylinder port C1 communicates with the tank port T1 via the load port B1, so that the oil chamber 4B of the cylinder 3 The pressure becomes high, the oil chamber 4A becomes low pressure, and the piston 5 operates to the left in the drawing, that is, to the cylinder contraction side.
[0042]
This state continues until the intermediate point of displacement of the main spool 14, and when the main spool 13 is further displaced toward the pressure chamber 19 past this point, as shown in FIG. The load port B2 is blocked from each other, and the cylinder port C2 communicates with the right tank port T2. Similarly, the cylinder port C1 is disconnected from the load port B1 and communicates with the supply port A. Therefore, the cylinder port C1 has a high pressure and the cylinder port C2 has a low pressure, and the piston 5 of the cylinder 3 operates in the opposite direction, that is, in the extending side.
[0043]
Eventually, when the left end of the pilot spool 14 is fitted and abutted with the stopper 33 and stops, only the main spool 13 is pushed to the left as it is. As a result, the annular port 28 of the pilot spool 14 is closed, the amount of hydraulic oil escaped from the left pressure chamber 19 is reduced, the main spool 13 is decelerated, and the pressure in the pressure chamber 19 is half the pressure in the pressure chamber 18. Thus, the forces acting on the left and right ends of the pilot spool 14 become equal (see FIG. 3).
[0044]
At this time, since the pressure in the pressure chamber 19 ′ is lower than the pressure in the pressure chamber 19 because of the fixed throttle 35, the main spool 13 is pushed further to the left. Therefore, when the pressure in the pressure chamber 19 becomes more than half that of the pressure chamber 18, the pressure receiving area of the pilot spool 14 is doubled on the pressure chamber 19 side until the pilot spool 14 comes into close contact with the main spool 13. It is instantly pushed to the right and opens the annular port 27 greatly. As a result, the high pressure in the pressure chamber 18 is introduced into the pressure chamber 19 on the opposite side via the through passage 30 and the return port R is also closed at this time, so that the pressure in the pressure chamber 19 is increased to the same pressure as the pressure chamber 18. (See FIG. 4).
[0045]
Even if the pressure chamber 19 has the same pressure as the other pressure chamber 18, the pressure receiving area of the main spool 13 is more than twice on the pressure chamber 19 side, so that the main spool 13 is also directed to the right. Displace.
[0046]
Due to the displacement of the main spool 13, when the intermediate point is passed, the cylinder port C1 that has been connected to the pump port P1 so far communicates with the tank port T1, and at the same time, the cylinder port C2 on the opposite side is connected to the tank port T1. What communicated with port T2 is switched to communication with pump port P1.
[0047]
Therefore, the pressure relationship between the oil chambers 4A and 4B of the cylinder 3 is reversed from the time when the intermediate point is passed, and what has been operating on the extension side is switched to the operation on the contraction side again.
[0048]
When the main spool 14 is displaced to the right as it is and the right end of the pilot spool 14 comes into contact with the end surface of the rod 17 of the auxiliary piston 16, the pilot spool 14 stops at that position. Displacement continues until closes.
[0049]
Then, as shown in FIG. 5, when the pilot spool 14 is in the neutral position and the pressure in the pressure chamber 19 is less than half that of the pressure chamber 18, the pressure acting on the left and right ends of the pilot spool 14 becomes equal. At this time, since the cross-sectional area A1 of the main spool 13 exceeds 2 times A2, when the main spool 13 is slightly displaced in the same direction, the opposite annular port 28 is opened and the pressure chamber is opened via the return port R. The pressure at 19 drops below half the pressure in the pressure chamber 18.
[0050]
For this reason, the pilot spool 14 moves instantaneously until it comes into contact with the main spool 13 on the opposite side, and the annular port 28 is greatly opened, and the pressure chamber 19 communicates with the tank port T1 and becomes a low pressure. Therefore, the main spool 13 also begins to move to the left integrally and returns to the state shown in FIG.
[0051]
As a result, the cylinder port C2 is now switched from high pressure to low pressure at the midpoint of displacement of the main spool 13, and the cylinder port C1 is switched from low pressure to high pressure. Switch from side to extension side operation.
[0052]
In this way, the main spool 13 of the automatic switching valve 10 repeats reciprocating motion according to the flow rate supplied to the control port P2, and the cylinder ports C1 and C2 are alternately communicated with the pump port P1, thereby The cylinder 3 is expanded and contracted at a rate of once per reciprocation of the main spool 13.
[0053]
When the control flow rate is changed by the variable throttle 22, the frequency characteristic of the main spool 13 changes accordingly, and the faster the reciprocating motion is performed as the flow rate increases.
[0054]
In this case, since the main spool 13 is always displaced to the left and right ends during the reciprocating motion, the spool stroke is not reduced even if the reciprocating frequency is increased, so that the high pressure and the low pressure can always be switched reliably.
[0055]
When the cross sectional areas of the main spool 13 and the pilot spool 14 are set to (A1 + A3) :( A2 + A4) ≈2: 1, respectively, the pressure receiving section of the pressure chamber 18 is almost half of the pressure receiving section of the pressure chamber 19, and the pressure chamber When 19 expands, hydraulic oil flows from the pressure chamber 18 side. Therefore, when the spool returns to the pressure chamber 18 side, the volume reduction corresponds to the expansion of the pressure chamber 19 and flows into the pressure chamber 18. If the flow rate is constant, the speeds when the pressure chamber 18 expands and contracts substantially coincide. For this reason, the timing of the pressure switching by the automatic switching valve 10 can be made substantially constant.
[0056]
In the operation stop state, the cylinder ports C1 and C2 can be kept in a state where both ports are shut off, that is, in an all-port block state, so that the operation of the cylinder 3 is stopped at that position. You can also.
[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 an explanatory diagram of a conventional example.
[Explanation of symbols]
1A Pump 2 Switching valve 3 Cylinder 4A Oil chamber 4B Oil chamber 10 Automatic switching valve 11 Valve body 13 Main spool 14 Pilot spool 16 Auxiliary piston 18 Pressure chamber 19 Pressure chamber 20 Spring 22 Variable throttle 27 Annular port (first port)
28 Annular port (second port)
33 Stopper 35 Fixed iris

Claims (7)

A main spool is slidably accommodated in the valve body, first and second pressure chambers are provided at both ends of the main spool, and a pair of main spools are reciprocally displaced according to the pressure difference between the pair of pressure chambers. The pump port and the tank port are selectively switched and connected to the cylinder port respectively, while the pilot spool is slidably accommodated coaxially on the main spool. The pilot spool protrudes from both sides of the main spool so as to be able to come into contact with the stopper on the inner wall of the valve body, while the pilot spool has a first port selectively communicating with the first pressure chamber according to the displacement, A second port in selective communication with the first pressure chamber, and the first port is connected to the first pressure chamber in the neutral position of the pilot spool. When disconnected, the second port is also disconnected 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 as described above, and the first port is always in communication with the second pressure chamber, and the second port is connected to the low pressure side via the low pressure side port of the main spool. The first pressure chamber is connected to the high pressure side, and the pressure receiving area of the main spool and the pilot spool on the first pressure chamber side is smaller than the pressure receiving area on the second pressure chamber side. Automatic switching valve device.   The automatic switching valve device according to claim 1, wherein the first pressure chamber is connected to a high pressure side through a variable throttle.   3. The automatic switching valve device according to claim 1, wherein a pressure receiving area on the first pressure chamber side of the main spool and the pilot spool is set to ½ of a pressure receiving area on the second pressure chamber side. The automatic pressure according to any one of claims 1 to 3, wherein the first pressure chamber is provided with an auxiliary piston as a stopper that protrudes to receive a pressure in the pressure chamber and press the pilot spool by a predetermined amount. Switching valve device.   The cylinder port according to any one of claims 1 to 4, wherein the cylinder port is in a blocking position with respect to all of the pump port and the tank port when the main spool is displaced to the maximum extent toward the auxiliary piston. Automatic switching valve device.   The automatic switching valve device according to any one of claims 1 to 5, further comprising a spring that biases the main spool toward the first pressure chamber.   The second pressure chamber is provided with a stopper that comes into contact with the pilot spool, and this stopper is formed with a passage that can be connected to a through-passage that is connected to the first port that opens at the end surface of the pilot spool. The automatic switching valve device according to any one of claims 1 to 6, wherein the automatic switching valve device communicates with the second pressure chamber via a fixed throttle.

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