Load sensing valve

Abstract

Provided is a load sensing valve that can improve the responsiveness of the main spool while avoiding enlargement. 【Solution means】The load sensing valve 100 includes a valve housing 200, a rotary valve 310 that extracts a constant flow rate from the primary pressure circuit via a flow regulator valve and controls the bleed-off flow rate according to the rotational position of the rotary spool to secure a secondary pressure, a main spool 3 that supplies the secondary pressure discharged from the rotary spool to the left and right caps 210A and 210B via spool hollow passages 18 and 37 and switches the flow path by the secondary pressure, and a rotary solenoid 300 that drives the rotary spool. As a result, since the pressure loss due to bleed-off via a fixed orifice from the primary pressure circuit is used as the secondary pressure, the secondary pressure is independent of the torque of the rotary solenoid, so the responsiveness of the main spool can be improved while avoiding enlargement of the solenoid.

Description

Technical Field

[0001] This specification discloses a technology related to a load sensing valve.

Background Art

[0002] Patent Document 1 describes a multi-connected type load sensing valve used in multiple connections. In the load sensing valve of Patent Document 1, a pressure compensation spool is arranged in a direction orthogonal to the main spool. Patent Document 2 describes a technology for controlling the position of the main spool using a proportional solenoid.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a load sensing valve, while avoiding enlargement, an improvement in the responsiveness of the main spool is required. In the prior art, in order to oppose the secondary pressure and the thrust of the solenoid to the pressure reducing valve spool, when the diameter of the pressure reducing valve spool is enlarged for the purpose of improving responsiveness, there is a problem that the solenoid needs to be enlarged.

Means for Solving the Problems

[0005] One form of the load sensing valve disclosed in this specification includes a valve housing, a rotary valve that extracts a constant flow rate from a primary pressure circuit via a flow regulator valve and controls the bleed-off flow rate according to the rotational position of a rotary spool to ensure a secondary pressure, a main spool that supplies the secondary pressure discharged from the rotary spool to left and right caps via a spool hollow passage and switches the flow path by the secondary pressure, and a rotary solenoid that drives the rotary spool. According to the load sensing valve of this form, since the pressure loss due to bleed-off via a fixed orifice from the primary pressure circuit is used as the secondary pressure, the secondary pressure is independent of the torque of the rotary solenoid, so the responsiveness of the main spool can be improved while avoiding an increase in the size of the solenoid.

[0006] In the above-described load sensing valve, the rotary valve may be provided between a pair of cylinder ports provided in the valve housing. According to the load sensing valve of this form, simplification of the configuration for ensuring the secondary pressure can be achieved.

[0007] The above-described load sensing valve may further include a pressure compensation valve connected to a flow path formed between it and another adjacent load sensing valve. According to the load sensing valve of this form, simplification of the configuration for pressure compensation can be achieved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0009] FIG. 1 is an explanatory view showing a load sensing valve 100. FIG. 2 is an enlarged cross-sectional view showing a rotary valve 310. FIG. 3 is an enlarged cross-sectional view showing a cross-section M-M of the rotary valve 310. FIG. 4 is an enlarged cross-sectional view showing a cross-section N-N of the pressure compensation valve 400.

[0010] The load sensing valve 100 is a multi-connected type device used by connecting a plurality of them in series. The load sensing valve 100 includes a valve housing 200, a main spool 3, a rotary valve 310, a rotary solenoid 300, and a pressure compensation valve 400. The main spool 3 is configured to be slidable within the valve housing 200 by a secondary pressure secured by the rotary valve 310.

[0011] The valve housing 200 includes tie rod holes 205, 207, a mating surface 208, and tank circuits 280A, 280B. The tie rod holes 205, 207 are through holes for passing tie rods for connecting to other valve housings 200. The mating surface 208 is a surface that contacts another valve housing 200. A prechamber 25 of the pressure compensation valve 400 is formed on the surface 208 as a flow path formed between adjacent other load sensing valves 100. Thereby, simplification of the configuration for pressure compensation can be achieved.

[0012] The rotary valve 310 extracts a constant flow rate from the primary pressure circuit via a flow regulator valve 8 and controls the bleed-off flow rate according to the rotational position of the rotary spool 2 to secure a secondary pressure. The rotary solenoid 300 drives the rotary spool 2.

[0013] The rotary valve 310 is provided between a pair of cylinder ports A and B provided in the valve housing 200. The main spool 3 has a hollow passage 37 and a hollow passage 18. The hollow passage 37 is a first hollow passage connecting between the cap 210A and the rotary valve 310. The hollow passage 18 is a second hollow passage connecting between the cap 210B and the rotary valve 310. Thereby, simplification of the configuration for securing the secondary pressure can be achieved.

[0014] In FIG. 1, the rotation angle of the shaft 1 of the rotary solenoid 300 is 0°. In FIG. 1, the rotary spool 2 in the rotary valve 310 is in a neutral position. In FIG. 1, the position of the main spool 3 is in a neutral position.

[0015] The rotary spool 2 is held in the neutral position by the torsion spring 36. In this state, the oil passage 6 of the primary pressure annular groove 5 of the sleeve 4 is blocked from the oil passage 7 of the rotary spool 2.

[0016] When the shaft 1 rotates clockwise by exciting the rotary solenoid 300, the blockage between the oil passage 6 and the oil passage 7 is released. Thereby, the oil flowing into the flow regulator valve 8 flows through the fixed orifice 9 into the groove oil passage 10.

[0017] The pressure upstream of the fixed orifice 9 acts on the front chamber of the flow regulator valve 8 via the damper 11. The pressure downstream of the fixed orifice 9 acts on the rear chamber of the flow regulator valve 8. The control flow rate of the flow regulator valve 8 is adjusted by the strength of the spring 12.

[0018] The control land 35 of the flow regulator valve 8 keeps the pressure difference between the upstream side and the downstream side of the fixed orifice 9 constant. The control land 35 performs throttle control at the edge with the rotary spool 2.

[0019] When the rotational angle of the shaft 1 is relatively small, the control flow rate of the groove oil passage 10 flows from the bleed-off hole 13 through the groove oil passage 14 to the tank oil passage 15.

[0020] As the rotational angle of the shaft 1 increases, the groove oil passage 10 connects to the oil passage 16 of the sleeve 4. As a result, the groove oil passage 10 passes through the oil passage 17 of the valve housing 200 and is connected to the cap 210B via the hollow passage 18 of the main spool 3.

[0021] The oil discharged from the cap 210A flows through the hollow passage 37 of the main spool 3 and the oil passage 38 of the valve housing 200, and then through the groove oil passage 39 of the rotary valve 310 to the tank oil passage 15.

[0022] When the rotational angle of the shaft 1 is not large enough, the groove oil passage 10 hardly constricts the bleed-off hole 13. Therefore, the pressure in the secondary pressure circuit is relatively low and yields to the reaction force of the spring 19A. As a result, the main spool 3 is in a neutral state.

[0023] When the rotational angle of the shaft 1 is further increased, the groove oil passage 10 starts to constrict the bleed-off hole 13. Therefore, the pressure in the secondary pressure circuit becomes relatively high. As a result, the main spool 3 moves toward the cap 210A side (right direction in FIG. 1).

[0024] When the main spool 3 moves toward the cap 210A side and the orifice 21 of the control flow rate land 20 in the main spool 3 opens, the pump flow rate flows in from the parallel circuit 230. This pump flow rate passes through the oil passage 22 and flows to the pressure compensation spool 23 in the pressure compensation valve 400.

[0025] The oil that pushes up the pressure compensation spool 23 flows out from the cylinder port B through the oil passage 24 via the land of the main spool 3, and the return oil returns from the cylinder port A to the tank circuit.

[0026] At this time, the pressure in the upstream unloading valve front chamber (not shown) acts on the front chamber 25 of the pressure compensation spool 23. The pressure in the oil passage 24 acts on the rear chamber 26 of the pressure compensation spool 23 via the oil passages 27, 28, check valve 29 and damper 40. Further, the pressure in the rear chamber 26 acts on the unloading valve rear chamber (not shown) via the oil passages 30, 31 and high pressure selection circuits 32, 33.

[0027] The control flow rate of the main spool 3 is determined by the control pressure of the unloading valve and the opening area of the control flow rate land 20.

[0028] When the load pressure in other sections is higher than that in this section by simultaneous operation, the check valve 29 is closed by the pressure in the high pressure selection circuit 32. Then, the front chamber 25 of the pressure compensation spool 23 and the oil passage 24 are controlled in a direction to be narrowed, and the pressure downstream of the orifice 21 of the main spool 3 rises. Thereby, the control pressure of the unloading valve is kept constant.

[0029] The pressure compensation spool 23 opens when the pressure in the front chamber 25 is higher than the pressure in the rear chamber 26. Therefore, the pressure compensation spool 23 also functions as a load check valve. Similarly, since the spool 34 also opens and closes the high pressure selection circuit 32 in the oil passages 30 and 31 at the control land 35, leakage to the unloading valve side can also be prevented.

[0030] According to the load sensing valve 100 described above, since the pressure loss due to bleed-off from the primary pressure circuit through the fixed orifice 9 is used as the secondary pressure, the secondary pressure is independent of the torque of the rotary solenoid 300. Therefore, while avoiding the enlargement of the solenoid 300, the responsiveness of the main spool 3 can be improved.

[0031] The technology disclosed in this specification is not limited to the above-described embodiments, examples, and variations, and can be implemented in various configurations without departing from the spirit thereof. For example, among the technical features in the above-described embodiments, examples, and variations, those corresponding to the technical features in each form described in the summary of the invention column can be appropriately replaced and combined in order to solve some or all of the above-described problems or to achieve some or all of the above-described effects. In addition, technical features not described as essential in this specification can be appropriately deleted.

[0032] For example, the fixed orifice 9 of the flow regulator valve 8 may be opened and closed by the rotary spool 2, and the bleed-off hole 13 may be fixed.

[0033] Further, by providing a groove oil passage on the mating surface 208 of the valve housing 200, an oil passage may be configured between the cap 210A and the rotary valve 310 without providing the hollow passage 37 in the main spool 3. Also, by providing a groove oil passage on the mating surface 208 of the valve housing 200, an oil passage may be configured between the cap 210B and the rotary valve 310 without providing the hollow passage 18 in the main spool 3. As a result, the number of lands of the valve housing 200 can be reduced. Also, the spool stroke can be increased. Also, the pressure loss and the leakage amount of the spool can be reduced.

Explanation of Reference Numerals

[0034] 1... shaft 2... rotary spool 3... main spool 4... sleeve 5... primary pressure annular groove 6... oil passage 7... oil passage 8... flow regulator valve 9... fixed orifice 10... groove oil passage 11... damper 12... spring 13... bleed-off hole 14... groove oil passage 15…Tank oil passage 16…Oil passage 17…Oil passage 18…Hollow passage 19A…Spring 20…Control flow land 21…Orifice 22…Oil passage 23…Pressure compensation spool 24…Oil passage 25…Front chamber 26…Rear chamber 27…Oil passage 28…Oil passage 29…Check valve 30…Oil passage 31…Oil passage 32…High-pressure selection circuit 34…Spool 35…Control land 36…Torsion spring 37…Hollow passage 38…Oil passage 39…Grooved oil passage 40…Damper 100…Load sensing valve 200…Valve housing 205…Tie rod hole 208…Fitting surface 210A…Cap 210B…Cap 230…Parallel circuit 280A…Tank circuit 300…Solenoid 300…Rotary solenoid 310…Rotary valve 400…Pressure compensation valve A…Cylinder port B…Cylinder port

Claims

1. A load sensing valve, A valve housing; A rotary valve that extracts a constant flow rate from the primary pressure circuit through a flow regulator valve and controls the bleed-off flow rate according to the rotational position of the rotating spool to ensure secondary pressure; a main spool that supplies the secondary pressure discharged from the rotary spool to the left and right caps through a spool hollow passage and switches the flow path according to the secondary pressure; a rotary solenoid for driving the rotary spool; A load sensing valve comprising:

2. 2. The load sensing valve according to claim 1, The rotary valve is a load sensing valve disposed between a pair of cylinder ports provided in the valve housing.

3. The load sensing valve according to claim 1 , further comprising a pressure compensation valve connected to a flow path formed between the load sensing valve and another adjacent load sensing valve.

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