JP4514324B2 - Hydraulic control valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control valve capable of minimizing internal leakage when holding a cylinder load, for example.
[0002]
[Prior art]
The conventional hydraulic control valve shown in FIG. 3 has a pair of cylinder ports a and b and a tank passage 4 formed in the valve body 1. The rod side chamber 41 of the cylinder C is connected to the cylinder port a, and the bottom side chamber 40 of the cylinder C is connected to the cylinder port b.
A spool hole 5 is formed in the valve body 1, and a spool 6 is slidably incorporated in the spool hole 5. When the spool 6 is in the neutral position shown in the drawing, the supply passages 2 and 3 and the neutral passage 9 are kept in communication with each other, and the discharge oil of the pump P guided through the supply passages 2 and 3 at this time is maintained. Is returned to the tank T via the neutral passage 9.
Note that both ends of the spool 6 face the pilot chambers 7 and 8.
[0003]
The valve body 1 is formed with U-shaped flow paths 10 and 11, and the cylinder ports a and b communicate with the spool hole 5 through the U-shaped flow paths 10 and 11.
Also, the valve body 1 is formed with assembly holes 12 and 13 for communicating the upper and lower portions of the U-shaped flow paths 10 and 11. The pilot check valves 14 and 15 are incorporated in these assembly holes 12 and 13.
These pilot check valves 14 and 15 incorporate springs 18 and 19 in their back pressure chambers 16 and 17 and press the poppets 20 and 21 against the seat portions 22 and 23 by their elastic force. In this way, the communication between the cylinder ports a and b and the spool hole 5 is normally blocked.
[0004]
The cylinder ports a and b communicate with the back pressure chambers 16 and 17 of the pilot check valves 14 and 15 through throttles 32 and 33, respectively. The load pressure of the cylinder C is guided to the back pressure chambers 16 and 17 through the throttles 32 and 33.
If the load pressure of the cylinder C is guided to the back pressure chambers 16 and 17 in this way, the poppets 20 and 21 are firmly pressed against the seat portions 22 and 23. For this reason, the holding pressure of the cylinder C does not act on the spool hole 5.
Therefore, when the spool 6 is maintained at the neutral position shown in the figure and the load of the cylinder C is maintained, the pressure oil in the bottom side chamber 40 of the cylinder C is passed through the sliding surface between the spool hole 5 and the spool 6. Does not leak to the tank side.
[0005]
Further, one ends of discharge passages 24 and 25 are communicated with the back pressure chambers 16 and 17 of the pilot check valves 14 and 15, respectively. The other ends of the discharge passages 24 and 25 are opened in the spool hole 5.
On the other hand, the spool 6 is formed with main annular grooves 26 and 27, pilot discharge annular grooves 28 and 29, and internal passages 30 and 31.
One end of each of the internal passages 30 and 31 is opened to the pilot discharge annular grooves 28 and 29, respectively. The other ends of the internal passages 30 and 31 are opened on the sliding surface of the spool 6. However, the other ends of the internal passages 30 and 31 are closed when the spool 6 is in the neutral position shown in the figure.
[0006]
Now, when pilot pressure is introduced to one pilot chamber 7, the spool 6 moves to the right in the drawing. When the spool 6 is thus switched, the communication between the supply passages 2 and 3 and the neutral passage 9 is blocked, and one supply passage 2 communicates with the main annular groove 26 via the notch 34. Therefore, the pressure oil from the pump P acts on the pilot check valve 14 to open the pilot check valve 14.
Accordingly, the pressure oil from the pump P is supplied to the bottom side chamber 40 of the supply passage 2 → notch 34 → main annular groove 26 → flow path 10 → cylinder port b → cylinder C.
[0007]
When the spool 6 moves as described above, the discharge passage 25 and the internal passage 31 communicate with each other. Therefore, the back pressure chamber 17 of the pilot check valve 15 communicates with the tank passage 4, and the fluid in the back pressure chamber 17 flows into the tank via the discharge passage 25 → the internal passage 31 → the pilot discharge annular groove 29 → the tank passage 4. Returned. When a pressure loss occurs in the throttle 33 due to such a flow and the pressure in the back pressure chamber 17 becomes low, the poppet 21 moves over the spring force of the spring 19 and the pilot check valve 15 opens.
When the pilot check valve 15 is opened, the pressure oil in the rod side chamber 41 of the cylinder C is discharged to the tank via the cylinder port a → the flow path 11 → the main annular groove 27 → the notch 35 → the tank passage 4.
As described above, the cylinder C extends.
[0008]
Contrary to the above, when the spool 6 is switched to the left, the communication between the supply passages 2 and 3 and the neutral passage 9 is interrupted, and the one supply passage 3 and the pilot check valve 15 communicate with each other via the notch 37. To do. The pilot check valve 15 is opened by the pressure oil from the supply passage 3, and the pressure oil is supplied to the rod side chamber 41 of the cylinder C.
Further, since the discharge passage 24 and the internal passage 30 communicate with each other by the movement of the spool 6, the back pressure chamber 16 of the pilot check valve 14 communicates with the tank passage 4 this time. Then, when the fluid in the back pressure chamber 16 is returned to the tank via the discharge passage 24 → the internal passage 30 → the pilot discharge annular groove 28 → the tank passage 4, pressure loss occurs in the throttle 32, and the back pressure chamber 16. The pressure of becomes low.
[0009]
As a result, the poppet 20 moves over the spring force of the spring 18 and the pilot check valve 14 opens. When the pilot check valve 14 is opened, the pressure oil in the bottom side chamber 40 of the cylinder C is discharged to the tank via the cylinder port b → the flow path 10 → the main annular groove 26 → the notch 36 → the tank passage 4.
As described above, the cylinder C contracts.
[0010]
[Problems to be solved by the invention]
In the above conventional example, in order to incorporate the pilot check valve into the cylinder ports a and b, the flow paths 10 and 11 have to be made to have a U-shape, and there is a problem that the manufacturing cost increases accordingly.
In addition, the pilot check valve must be assembled in the back of the cylinder ports a and b, and there is a problem that the assembling work is difficult.
An object of the present invention is to provide an inexpensive hydraulic control valve that has a simple flow path and can be easily assembled with a pilot check valve.
[0011]
[Means for Solving the Problems]
According to the present invention, a pair of cylinder ports, a supply passage, a tank passage, and a spool hole are formed in the valve body, and a spool is slidably incorporated in the spool hole, and the supply to the valve body In a hydraulic control valve that incorporates a pilot check valve that allows only flow from the passage to the cylinder port, an assembly hole is formed on the side of the valve body that communicates with the cylinder port from the overlapping surface on which other valve blocks overlap. The pilot check valve is assembled in the assembly hole, and the assembly hole is closed by the overlapping surface of the other valve block, while the annular recess formed in the inner periphery of the spool hole, the annular recess and the back pressure chamber of the pilot check valve And a communication passage that opens on the surface of the spool. It is or to communicate with the tank passage and the annular recess in accordance with the switching position of the spool, characterized in that a configuration or to block the communication.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
A spool hole 50 is formed in the valve body B, and a spool 51 is slidably incorporated in the spool hole 50.
In addition, a supply oil passage 52 is formed in the valve body B and communicates with the spool hole 50.
The diameter of the opening of the supply oil passage 52 communicated with the spool hole 50 is made smaller than the diameter of the spool 51.
[0013]
A pair of cylinder ports 53 and 54 are provided on both sides of the supply oil passage 52, and the cylinder ports 53 and 54 are communicated with the spool hole 50.
Further, tank passages T1, T2 are formed next to the cylinder ports 53, 54, and these tank passages T1, T2 are also communicated with the spool hole 50.
[0014]
The spool 51 is formed with main annular grooves 55 and 56 that always communicate with the cylinder ports 53 and 54. Annular metering notches 57, 58 are formed on one end side of the main annular grooves 55, 56, and discharge notches 59, 60 are formed on the other end side.
On the left side of the discharge notch 59 of the spool 51 in the drawing, slits 61, 62a, 62b corresponding to the communication passages of the present invention are formed with their positions shifted in the axial direction.
[0015]
Further, passages 63 and 64 for communicating the cylinder ports 53 and 54 with the spool hole 50 are formed, and a pilot check valve V is incorporated in one of the passages 63.
As shown in FIG. 2, the pilot check valve V is formed with an assembly hole 65 from the side surface of the valve body B. The assembly hole 65 communicates with the passage 63, and a poppet 66 and a spring 67 are connected to the assembly hole 65. It is composed by incorporating.
Since the assembly hole 65 is formed from the side surface of the valve body B, the processing of the hole can be simplified compared to the conventional example in which the assembly hole is formed in the cylinder port.
Further, since the poppet 66 and the spring 67 incorporated in the assembly hole 65 can also be incorporated directly from the side surface of the valve body B, the assembly work is compared with the conventional case where the poppet 66 and the spring 67 must be incorporated into the assembly hole through the cylinder port. Can also be done easily.
[0016]
Although not shown, another valve block is overlapped on the side surface of the valve block B. Then, the assembly hole 65 is closed by the mating surfaces of the other superimposed blocks.
[0017]
The poppet 66 is normally pressed against the seat portion 68 by the elastic force of the spring 67. By pressing the poppet 66 against the seat portion 68 in this way, the communication between the cylinder port 53 and the spool hole 50 is completely blocked.
Further, a back pressure chamber 74 is formed in the poppet 66, and a small hole 75 is formed continuously with the back pressure chamber 74.
Further, the poppet 66 is formed with a through hole 69 communicating with the back pressure chamber 74 and a throttle 70 communicating with the small hole 75 in the radial direction. And the opening part of these through-holes 69 and the aperture | diaphragm | restriction 70 is each opened to the annular grooves 71 and 72 formed in the poppet 66.
[0018]
The valve body B incorporating the poppet 66 is formed with a discharge passage 100 as shown in FIG. 1, one of which communicates with the assembly hole 65 and the other formed on the inner periphery of the spool hole 50. 73 is communicated.
As shown in FIG. 1, when the spool 51 is in the neutral position, the communication between the annular recess 73 and the tank passage T1 is interrupted. However, when the spool 51 moves to the left in the drawing, the spool 51 is formed on the spool 51. The annular recess 73 and the tank passage T1 communicate with each other through the slits 61, 62a and 62b.
[0019]
On the other hand, at both ends of the valve body B, plate-like closing members 80 and 81 are fixed by bolts 83, and the spool holes 50 are closed by these closing members 80 and 81 to form pilot chambers 84 and 85.
Pilot passages 86 and 87 are connected to the pilot chambers 84 and 85, respectively. The pilot pressure controlled by the pressure reducing valves 88 and 89 is guided to the pilot chambers 84 and 85 through the pilot passages 86 and 87, respectively.
The pressure reducing valves 88 and 89 are controlled by proportional solenoids 90 and 91, respectively.
[0020]
In the pilot chambers 84 and 85, main springs 92 and 93 are incorporated, and one ends thereof are inserted into axial holes 94 and 95 formed in the spool 51.
The main springs 92 and 93 maintain a free length when the spool 51 is in a neutral position, and in this free length state, one end abuts against the closing members 80 and 81 and the other end is at the bottom of the axial holes 94 and 95. It is in contact. Therefore, the elastic force of the main springs 92 and 93 is not acting on the spool 51 in the neutral position.
[0021]
On the other hand, small diameter portions 96 and 97 are formed on both ends of the spool 51. Further, enlarged diameter portions 98 and 99 are formed on the opening side of the spool hole 50. Centering springs S and S are incorporated between the small diameter portions 96 and 97 and the enlarged diameter portions 98 and 99.
These centering springs S, S have a smaller spring constant than the main springs 92, 93, and are given a predetermined elastic force in a state where the spool 51 is in the neutral position. The spring receiving members 78 and 79 provided on the outer periphery of the spool 51 are pressed against the stepped portion 77 formed on the spool 51 and the stopper portion 76 formed on the valve body B by the elastic force of the centering springs S and S. Yes. The neutral position of the spool 51 is held by the elastic force of the centering springs S and S.
[0022]
Next, the operation of this embodiment will be described.
As shown in the figure, when the spool 51 is held in the neutral position and the load of the cylinder C is held, the load pressure of the bottom side chamber 40 of the cylinder C is reduced from the cylinder port 53 to the throttle 70 → the small hole 75 → the back pressure chamber. The poppet 66 is led to the sheet portion 68 by the pressure.
Therefore, the communication between the cylinder port 53 and the spool hole 51 is completely blocked by the pilot check valve V, and the pressure oil in the bottom side chamber 40 of the cylinder C leaks through the gap between the spool 51 and the spool hole 50. Do not do. That is, the load of the cylinder C can be reliably held.
[0023]
When pilot pressure is guided to the pilot chamber 85 from the above state, thrust in the left direction of the drawing is applied to the spool 51. When the thrust in the left direction of the spool 51 overcomes the elastic force of the centering spring S on the left side of the drawing, the spool 51 moves in the left direction of the drawing while deflecting the centering spring S and the main spring 92. .
When the spool 51 moves in the left direction, first, the annular recess 73 and the tank passage T1 communicate with each other through the slit 61. Therefore, the pressure oil in the back pressure chamber 74 of the pilot check valve V is returned to the tank T via the through hole 71 → the annular groove 69 → the discharge passage 100 → the annular recess 73 → the slit 61 → the tank passage T1. When such a flow causes a pressure loss in the throttle 70 and the pressure in the back pressure chamber 74 becomes low, the poppet 66 moves over the spring force of the spring 67 and the pilot check valve V opens.
[0024]
Further, when the spool 51 further moves to the left from the above state, the cylinder port 54 and the supply passage 52 communicate with each other through the metering notch 58, and the cylinder port 53 and the tank passage T1 communicate with each other.
Therefore, the pressure oil from the pump P is supplied to the rod side chamber 41 of the supply passage 52 → metering notch 58 → main annular groove 56 → passage 64 → cylinder port 54 → cylinder C. The return fluid from the bottom chamber 40 of the cylinder C is discharged to the tank T via the cylinder port 53 → passage 63 → pilot check valve V → main annular groove 55 → discharge notch 59 → tank passage T1.
As described above, the cylinder C contracts.
When the spool 51 is moved in the right direction in the drawing, the cylinder C expands, but the substantial movement is the same as that in the case where the spool 51 is moved in the left direction. .
[0026]
According to this embodiment, since the assembly hole is formed from the side surface of the valve body B, the passage 63 communicating the cylinder port and the spool hole does not have to be U-shaped. Therefore, the manufacturing cost can be made lower than that of the conventional example in which the flow path has a U-shape.
In addition, since the assembly hole is directly opened on the side surface of the valve body, the assembly work of the pilot check valve can be simplified. That is, assembly work efficiency can be increased.
In this embodiment, the pilot check valve V is incorporated only in one of the passages 63, but the pilot check valve may be incorporated in the other passage 64 in a symmetrical shape.
[0027]
【The invention's effect】
According to the present invention, since the assembly hole is formed from the side surface of the valve body and communicated with the cylinder port, the pilot check valve can be incorporated without using a U-shaped passage as in the prior art. it can.
In this way, the manufacturing cost can be reduced by the simplification of the shape of the passage.
Further, since the pilot check valve can be directly assembled into the assembly hole from the portion opened on the side surface of the valve body, the pilot check valve can be easily assembled.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment.
FIG. 2 is a cross-sectional view of a main part.
FIG. 3 is a cross-sectional view showing a conventional example.
[Explanation of symbols]
B Valve body V Pilot check valve T1, T2 Tank passage 50 Spool hole 51 Spool 52 Supply passage 53, 54 Cylinder ports 61, 62 Slit 65 Assembly hole 73 Annular recess 74 Back pressure chamber 100 Discharge passage

Claims (1)

The valve body, and a pair of cylinder ports, a supply passage, a tank passage, forming a spool bore, with incorporated slidably the spool in the spool hole, to the valve body, said cylinder port from said supply passage in the hydraulic control valve incorporating a pilot check valve which allows the flow only to, a side of the valve body to form an assembly hole communicated with the cylinder port from the superposed surfaces overlaying another valve block, the assembling hole Assemble the pilot check valve to the other valve block and close the assembly hole with the overlapping surface of the other valve block. A passage and a communication passage opened on the surface of the spool. Or to communicate with the tank passage and the annular recess in accordance with the repositioned, the hydraulic control valve being characterized in that a configuration or to block the communication.

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