Hydraulic control valve and variable displacement hydraulic pump having the same

Abstract

Embodiments of the present invention disclose a hydraulic control valve and a displacement hydraulic pump. The hydraulic control valve includes a valve body and a spool. The valve body includes: a first chamber formed in the valve body on one side in the axial direction of the valve chamber and communicating with the valve chamber, and a first outlet and a second outlet for outputting control fluid. The spool can be in a first position relative to the valve body, move from the first position to the second position by using a first pressure in the first chamber, and move from the second position to the third position by using a second pressure greater than the first pressure in the first chamber. When the spool is in the first position, the input passage is disconnected from the outlet. When the spool is in the second position, the input passage is connected to the first outlet and disconnected from the second outlet. And when the spool is in the third position, while maintaining the state where the input passage is connected to the first outlet, the input passage is connected to the second outlet. This hydraulic control valve can achieve a low overshoot function.

Description

Technical Field

[0001] Embodiments of the present invention relate to a hydraulic control valve and a variable displacement hydraulic pump having the hydraulic control valve. Background Art

[0002] Generally, the flow rate of a variable displacement hydraulic pump is controlled by a hydraulic control valve of the variable displacement hydraulic pump. However, the current hydraulic control valve has a slow response, and the spool often generates a large overshoot during the adjustment process. Summary of the Invention

[0003] An object of embodiments of the present invention is to provide a hydraulic control valve and a variable displacement hydraulic pump having the hydraulic control valve, thereby improving the performance of the hydraulic control valve and the variable displacement hydraulic pump, for example.

[0004] Embodiments of the present invention provide a hydraulic control valve, including: a valve body, the valve body including: a valve cavity extending in the axial direction in the valve body; a first cavity formed in the valve body on one side in the axial direction of the valve cavity and communicating with the valve cavity; an input channel for inputting fluid; and a plurality of output ports for outputting control fluid, the plurality of output ports including a first output port and a second output port; and a spool disposed in the valve cavity of the valve body, wherein: the spool can be in a first position relative to the valve body, move from the first position in a direction away from the first cavity to a second position by using a first pressure in the first cavity, and move from the second position in a direction away from the first cavity to a third position by using a second pressure greater than the first pressure in the first cavity, when the spool is in the first position, the input channel is disconnected from the plurality of output ports, when the spool is in the second position, the input channel is connected to the first output port among the plurality of output ports and disconnected from the second output port among the plurality of output ports, and when the spool is in the third position, while maintaining the state where the input channel is connected to the first output port among the plurality of output ports, the input channel is connected to the second output port among the plurality of output ports.

[0005] According to an embodiment of the present invention, from the time when the input channel starts to communicate with the first output port until the input channel starts to communicate with the second output port, the stroke of the spool is between 0.01 mm and 0.5 mm.

[0006] According to an embodiment of the present invention, the valve body further includes a return port for returning fluid to the fuel tank, when the spool is in the first position, the first output port among the plurality of output ports is connected to the return port, and when the spool is in the second position and the third position, the first output port among the plurality of output ports is disconnected from the return port.

[0007] According to an embodiment of the present invention, the hydraulic control valve further includes: an input port for inputting fluid and communicating with the input channel, wherein: when the valve core is in the first position, the input port is disconnected from a plurality of output ports; when the valve core is in the second position, the input port is connected to a first output port among the plurality of output ports and disconnected from a second output port among the plurality of output ports; and when the valve core is in the third position, while maintaining the state that the input port is connected to the first output port among the plurality of output ports, the input port is connected to the second output port among the plurality of output ports.

[0008] According to an embodiment of the present invention, the valve core includes: a first end portion facing the first chamber; a second end portion opposite to the first end portion; an axial hole axially extending from the first end portion of the valve core between the first end portion and the second end portion; a first recess and a second recess formed on the outer periphery of the valve core; and a first communication hole and a second communication hole respectively communicating the axial hole with the first recess and the second recess, wherein the first recess and the second recess respectively form a first working chamber and a second working chamber with the inner wall of the valve chamber of the valve body, the input port communicates with the first working chamber, when the valve core is in the second position, the input port is connected to the first output port among the plurality of output ports through the first working chamber, and when the valve core is in the third position, while maintaining the state that the input port is connected to the first output port among the plurality of output ports through the first working chamber, the input port is connected to the second output port among the plurality of output ports through the first working chamber, the first communication hole, the axial hole, the second communication hole and the second working chamber.

[0009] According to an embodiment of the present invention, the input port communicates with the first chamber through the first working chamber, the first communication hole and the axial hole.

[0010] According to an embodiment of the present invention, the valve body further includes a second chamber formed in the valve body on the other side in the axial direction of the valve chamber and communicating with the valve chamber, and the hydraulic control valve further includes: a spring, the spring is disposed in the second chamber of the valve body for pushing the valve core toward the first chamber of the valve body, and the valve core can move relative to the valve body toward the first chamber under the push of the spring to the first position.

[0011] According to an embodiment of the present invention, the hydraulic control valve further includes: a plurality of input ports communicating with the input passage and leading to the valve cavity, the plurality of input ports including a first input port and a second input port. When the spool is in the first position, the plurality of input ports are disconnected from the plurality of output ports. When the spool is in the second position, the first input port among the plurality of input ports is connected to the first output port among the plurality of output ports and the plurality of input ports are disconnected from the second output port among the plurality of output ports. And when the spool is in the third position, while maintaining the connection between the first input port among the plurality of input ports and the first output port among the plurality of output ports, the second input port among the plurality of input ports is connected to the second output port among the plurality of output ports.

[0012] According to an embodiment of the present invention, the spool includes: a first recess and a second recess formed on the outer periphery of the spool, the first recess and the second recess respectively form a first working chamber and a second working chamber with the inner wall of the valve cavity of the valve body, the first input port among the plurality of input ports communicates with the first working chamber, and the second input port among the plurality of input ports communicates with the second working chamber. When the spool is in the second position, the first input port among the plurality of input ports is connected to the first output port among the plurality of output ports through the first working chamber. And when the spool is in the third position, while maintaining the connection between the first input port among the plurality of input ports and the first output port among the plurality of output ports through the first working chamber, the second input port among the plurality of input ports is connected to the second output port among the plurality of output ports through the second working chamber.

[0013] An embodiment of the present invention further provides a variable displacement hydraulic pump, including: the above-mentioned hydraulic control valve; a variable displacement hydraulic pump main body, the output port of the variable displacement hydraulic pump main body is connected to the input passage of the hydraulic control valve; and a pump servo system, the pump servo system is connected to at least one of the plurality of output ports of the hydraulic control valve to control the displacement of the variable displacement hydraulic pump main body.

[0014] According to an embodiment of the present invention, the variable displacement hydraulic pump further includes: a constant power valve, the constant power valve is connected to the pump servo system for controlling the power of the variable displacement hydraulic pump main body, the constant power valve includes: a first input port and a second input port for inputting fluid, wherein the first input port communicates with the output port of the variable displacement pump main body, and the second input port communicates with the first output port among the plurality of output ports of the pressure control valve; and an output port for outputting fluid connected to the pump servo system, wherein the second output port among the plurality of output ports of the hydraulic control valve is directly connected to the pump servo system.

[0015] A hydraulic control valve according to an embodiment of the present invention and a variable displacement hydraulic pump having the same can improve the performance of the hydraulic control valve and the variable displacement hydraulic pump, for example. Description of the Drawings

[0016] Figure 1 is a schematic cross-sectional view of a hydraulic control valve according to an embodiment of the present invention:

[0017] Figure 2 is a schematic cross-sectional view of a hydraulic control valve according to another embodiment of the present invention:

[0018] Figure 3 is a schematic cross-sectional view of a hydraulic control valve according to still another embodiment of the present invention:

[0019] Figure 4 is an integrated Figure 1 schematic cross-sectional view of the hydraulic control valve and the constant power valve shown according to an embodiment of the present invention:

[0020] Figure 5 is an integrated Figure 2 schematic cross-sectional view of the hydraulic control valve and the constant power valve shown according to another embodiment of the present invention:

[0021] Figure 6 is an integrated Figure 3 schematic cross-sectional view of the hydraulic control valve and the constant power valve shown according to still another embodiment of the present invention:

[0022] Figure 7 is a schematic diagram of a variable displacement hydraulic pump according to an embodiment of the present invention;

[0023] Figure 8 is a schematic diagram of a variable displacement hydraulic pump according to another embodiment of the present invention; and

[0024] Figure 9 is according to an embodiment of the present invention Figure 1 schematic cross-sectional view of the shown hydraulic control valve when the spool is in the first position;

[0025] Figure 10 is according to an embodiment of the present invention Figure 1 schematic cross-sectional view of the shown hydraulic control valve when the spool is in the second position; and

[0026] Figure 11 is according to an embodiment of the present invention Figure 1 schematic cross-sectional view of the shown hydraulic control valve when the spool is in the third position. Detailed Description

[0027] See Figures 1 to 6 、Figures 9 to 11 , according to an embodiment of the present invention, the hydraulic control valve 100 includes a valve body 10 and a spool 20. The valve body 10 includes: a valve chamber 11 extending in the axial direction in the valve body 10; a first chamber 101 formed in the valve body 10 on one side in the axial direction of the valve chamber 11 and communicating with the valve chamber 11; an input passage 3 for inputting fluid; and a plurality of output ports 41, 42 for outputting control fluid, the plurality of output ports 41, 42 including a first output port 41 and a second output port 42. The spool 20 is disposed in the valve chamber 11 of the valve body 10. As Figure 1 , 3 , as shown in FIGS. 4, 6, 9-11, the input passage 3 communicates with the first chamber 101, or as Figure 2 , 5 shown, a separate actuation fluid passage 6 for inputting actuation fluid communicates with the first chamber 101. Refer to Figures 9 to 11 , the spool 20 can be in a first position relative to the valve body 10 (refer to Figure 9 ), and move from the first position in a direction away from the first chamber 101 to a second position (refer to Figure 10 ) by using the first pressure in the first chamber 101, and move from the second position in a direction away from the first chamber 101 to a third position (refer to Figure 11 ) by using a second pressure greater than the first pressure in the first chamber 101. When the spool 20 is in the first position (refer to Figure 9 ), the input passage 3 is disconnected from the plurality of output ports 41, 42. When the spool 20 is in the second position (refer to Figure 10 ), the input passage 3 is connected to the first output port 41 among the plurality of output ports 41, 42 and disconnected from the second output port 42 among the plurality of output ports 41, 42, and when the spool 20 is in the third position (refer to Figure 11 ), while maintaining the state that the input passage 3 is connected to the first output port 41 among the plurality of output ports 41, 42, the input passage 3 is connected to the second output port 42 among the plurality of output ports 41, 42. The valve body 10 further includes a return port 5 for returning fluid to the fuel tank. When the spool 20 is in the first position (refer to Figure 9 ), the first output port 41 among the plurality of output ports 41, 42 is connected to the return port 5, and when the spool 20 is in the second and third positions (refer to Figure 10 , 11 ), the first output port 41 among the plurality of output ports 41, 42 is disconnected from the return port 5, that is, the plurality of output ports 41, 42 are disconnected from the return port 5. The valve body 10 further includes: an output passage (refer to Figure 7); or a plurality of output channels that are respectively connected to the plurality of output ports 41 and 42 and are used for outputting control fluid (see Figure 8 ).

[0028] According to an embodiment of the present invention, see Figures 1 to 6 , Figures 9 to 11 , from the time when the input channel 3 starts to be connected to the first output port 41 until the input channel 3 starts to be connected to the second output port 42, the stroke of the valve core 20 is between 0.01 mm and 0.5 mm.

[0029] According to an embodiment of the present invention, see Figures 1 to 6 , Figures 9 to 11 , the hydraulic control valve 100 further includes: an input port 30 that is connected to the input channel 3 and leads to the valve cavity 11. When the valve core 20 is in the first position, the input port 30 is disconnected from the plurality of output ports 41 and 42. When the valve core 20 is in the second position, the input port 30 is connected to the first output port 41 among the plurality of output ports 41 and 42 and is disconnected from the second output port 42 among the plurality of output ports 41 and 42. And when the valve core 20 is in the third position, while maintaining the state where the input port 30 is connected to the first output port 41 among the plurality of output ports 41 and 42, the input port 30 is connected to the second output port 42 among the plurality of output ports 41 and 42. See Figure 1 , the valve core 20 includes: a first end 21 facing the first cavity 101; a second end 22 opposite to the first end 21; an axial hole 23 axially extending from the first end 21 of the valve core 20 to between the first end 21 and the second end 22; a first recess 24 and a second recess 25 formed on the outer periphery of the valve core 20; and a first communication hole 26 and a second communication hole 27 that respectively communicate the axial hole 23 with the first recess 24 and the second recess 25. The first recess 24 and the second recess 25 respectively form a first working cavity 51 and a second working cavity 52 with the inner wall of the valve cavity 11 of the valve body 10, and the input port 30 is connected to the first working cavity 51. When the valve core 20 is in the second position, the input port 30 is connected to the first output port 41 among the plurality of output ports 41 and 42 through the first working cavity 51. And when the valve core 20 is in the third position, while maintaining the state where the input port 30 is connected to the first output port 41 among the plurality of output ports 41 and 42 through the first working cavity 51, the input port 30 is connected to the second output port 42 among the plurality of output ports 41 and 42 through the first working cavity 51, the first communication hole 26, the axial hole 23, the second communication hole 27 and the second working cavity 52. See Figures 1 to 3 , Figures 9 to 11 , the valve core 20 further includes a third recess 28 formed on the outer periphery of the valve core 20. The third recess 28 forms a third working cavity 53 with the inner wall of the valve cavity 11 of the valve body 10, and the third working cavity 53 is connected to the return port 5. SeeFigure 9 When the valve spool 20 is in the first position, the first output port 41 communicates with the third working chamber 53, so that the first output port 41 communicates with the return port 5.

[0030] According to some embodiments of the present invention, referring to Figure 1 , 4 , 9-11, the input port 30 communicates with the first chamber 101. For example, the input port 30 communicates with the first chamber 101 through the first working chamber 51, the first communication hole 26 and the axial hole 23.

[0031] According to some other embodiments of the present invention, referring to Figure 3 , the communication channel 35 connects the input channel 3 with the first chamber 101.

[0032] According to embodiments of the present invention, referring to Figures 1 to 6 , Figures 9 to 11 , the valve body 10 further includes a second chamber 102 formed in the valve body 10 on the other side in the axial direction of the valve chamber 11 and communicating with the valve chamber 11, and the hydraulic control valve 100 further includes: a spring 7, the spring 7 is disposed in the second chamber 102 of the valve body 10 for pushing the valve spool 20 toward the first chamber 101 of the valve body 10, and the valve spool 20 can move relative to the valve body 10 to the first position under the push of the spring 7 toward the first chamber 101.

[0033] According to some other embodiments of the present invention, referring to Figure 2 , 3, 5, 6, the hydraulic control valve 100 further includes: a plurality of input ports 31, 32 for inputting fluid and communicating with the input passage 3, and the plurality of input ports 31, 32 include a first input port 31 and a second input port 32. When the spool 20 is in the first position, the plurality of input ports 31, 32 are disconnected from the plurality of output ports 41, 42. When the spool 20 is in the second position, the first input port 31 among the plurality of input ports 31, 32 is communicated with the first output port 41 among the plurality of output ports 41, 42 and the plurality of input ports 31, 32 are disconnected from the second output port 42 among the plurality of output ports 41, 42. And when the spool 20 is in the third position, while maintaining the state that the first input port 31 among the plurality of input ports 31, 32 is communicated with the first output port 41 among the plurality of output ports 41, 42, the second input port 32 among the plurality of input ports 31, 32 is communicated with the second output port 42 among the plurality of output ports 41, 42. According to an example of the present invention, the spool 20 includes: a first recess 24 and a second recess 25 formed on the outer periphery of the spool 20, and the first recess 24 and the second recess 25 respectively form a first working chamber 51 and a second working chamber 52 with the inner wall of the valve chamber 11 of the valve body 10. The first input port 31 among the plurality of input ports 31, 32 is communicated with the first working chamber 51, and the second input port 32 among the plurality of input ports 31, 32 is communicated with the second working chamber 52. When the spool 20 is in the second position, the first input port 31 among the plurality of input ports 31, 32 is communicated with the first output port 41 among the plurality of output ports 41, 42 through the first working chamber 51. And when the spool 20 is in the third position, while maintaining the state that the first input port 31 among the plurality of input ports 31, 32 is communicated with the first output port 41 among the plurality of output ports 41, 42 through the first working chamber 51, the second input port 32 among the plurality of input ports 31, 32 is communicated with the second output port 42 among the plurality of output ports 41, 42 through the second working chamber 52.

[0034] As Figure 7 shown, the variable displacement hydraulic pump 200 according to an embodiment of the present invention includes: the above-mentioned hydraulic control valve 100, a variable displacement hydraulic pump main body 201, and a pump servo system 8. The output port of the variable displacement hydraulic pump main body 201 is connected to the input passage 3 of the hydraulic control valve 100. The pump servo system 8 is connected to at least one of the plurality of output ports 41, 42 of the hydraulic control valve 100 to control the displacement of the variable displacement hydraulic pump main body 201.

[0035] See Figure 4 , 7, the pressure fluid at the outlet of the variable displacement pump body 201 (such as a variable displacement piston pump) passes through the flow passage in the valve body 10 to the input passage 3, and enters the first chamber 101 through the input passage 3, the input port 30, the first working chamber 51, the first communication hole 26 and the axial hole 23. The fluid in the first chamber 101 acts on the left end of the valve core 20, and the right end of the valve core 20 is acted on by the spring 7. When the pressure of the fluid in the first chamber 101 can push the valve core 20 to make the valve core 20 in the second position, the input port 30 is connected to the first output port 41 among the plurality of output ports 41, 42, then the hydraulic control valve 100 comes into play, and the pressure fluid goes to the control cylinder of the variable displacement pump body 201, and the displacement of the variable displacement pump body 201 decreases. In some working conditions, for example, when the external load suddenly increases, it is necessary to quickly reduce the displacement of the variable displacement pump body 201 to reduce the load impact. If the displacement of the variable displacement pump body 201 cannot be quickly reduced and the pressure at the outlet of the variable displacement pump body 201 continues to rise, for example, when it is necessary to quickly reduce the displacement of the variable displacement pump body 201 of the mechanical equipment to quickly reduce the traveling speed of the tool connected to the hydraulic cylinder of the mechanical equipment, the pressure of the fluid in the first chamber 101 pushes the valve core 20 to move further to the right, and the valve core 20 is in the third position. While keeping the input port 30 connected to the first output port 41 among the plurality of output ports 41, 42, the input port 30 is connected to the second output port 42 among the plurality of output ports 41, 42. The second output port 42 delivers the high-pressure fluid to the control cylinder of the variable displacement pump body 201. The control cylinder of the variable displacement pump body 201 obtains a more sufficient flow rate, and the variable displacement pump body 201 reaches a small displacement faster, reducing the pressure increase amount.

[0036] According to this embodiment, in the steady-state operation (when the flow rate is stable and small), the first output port 41 can meet the requirements. However, when the system is in dynamic operation, sometimes the required flow rate changes greatly, so the valve core needs to provide a large flow rate. At this time, there will be a large overshoot in the valve core stroke, and this overshoot should be avoided in the hydraulic system. By setting the second output port 42, when the valve core overshoots, the flow rate can be output through the first output port 41 and the second output port 42 at the same time. After that, the valve core will not continue to rush violently in the direction away from the first position. Thus, the overshoot of the valve core stroke can be controlled within a very small range. When the valve core returns to the steady-state operation, it returns to the state where only the first output port 41 outputs.

[0037] See Figure 8 , which is related to Figure 7Similar, but the variable displacement hydraulic pump 200 further includes a constant power valve 9. The constant power valve 9 is connected to the pump servo system 8 and is used to control the power of the variable displacement hydraulic pump main body 201. For example, to make the power of the variable displacement hydraulic pump main body 201 substantially constant. The constant power valve 9 includes: a first input port 91 and a second input port 92 for inputting fluid, and an output port 93 for outputting fluid connected to the pump servo system 8. The first input port 91 is communicated with the output port of the variable displacement pump main body 201, and the second input port 92 is communicated with the first output port 41 among the plurality of output ports 41, 42 of the hydraulic control valve 100. The second output port 42 among the plurality of output ports 41, 42 of the hydraulic control valve 100 is directly connected to the pump servo system 8 without passing through the constant power valve 9.

[0038] When the variable displacement hydraulic pump 200 includes a hydraulic control valve 100 and a constant power valve 9, the working principle of the hydraulic control valve 100 is the same as that of Figure 7 the hydraulic control valve 100 shown therein. When the pressure of the fluid in the first chamber 101 of the hydraulic control valve 100 can push the valve core 20 to make the valve core 20 in the second position, the input port 30 is connected to the first output port 41 among the plurality of output ports 41, 42, and the pressure fluid needs to be input into the control cylinder of the variable displacement pump main body 201 through the constant power valve 9. If the valve core of the constant power valve 9 is in Figure 8 the left position in, it will hinder the input of the pressure fluid into the control cylinder of the variable displacement pump main body 201, and the variable displacement pump main body 201 cannot quickly reduce the displacement. When the displacement of the variable displacement pump main body 201 cannot be quickly reduced and the pressure of the output port of the variable displacement pump main body 201 continues to rise, the pressure of the fluid in the first chamber 101 of the hydraulic control valve 100 pushes the valve core 20 to move further to the right, and the valve core 20 is in the third position. While keeping the input port 30 connected to the first output port 41 among the plurality of output ports 41, 42, the input port 30 is connected to the second output port 42 among the plurality of output ports 41, 42. The second output port 42 directly (without passing through the constant power valve 9) conveys the high-pressure fluid to the control cylinder of the variable displacement pump main body 201. Thus, the variable displacement pump main body 201 can reach a small displacement faster, and the increase in pressure is reduced. In addition, the function of reducing overshoot described in the previous embodiment can also be achieved.

[0039] The hydraulic control valve 100 and the variable displacement hydraulic variable displacement pump main body 201 according to the embodiment of the present invention can achieve a low overshoot function. The first output port is the normal output port, and the second output port is the overshoot output port. The starting position of the overshoot output port can be adjusted according to the actual flow demand.

[0040] The hydraulic control valve 100 and the variable displacement hydraulic pump main body 201 according to the embodiments of the present invention have multiple output ports provided, which improves the flow gain and reduces the overshoot of the spool. In addition, when operating normally, the first output port 41 operates and the leakage does not increase. When integrated with other valves, the second output port 42 can be directly connected to the control cylinder of the variable displacement pump servo system without interfering with other valves. In this way, the interference of other valves is reduced.

[0041] Although the output ports 41 and 42 of the hydraulic control valve 100 are described in the above embodiments, the hydraulic control valve 100 may include more output ports, such as three, four or more output ports.

Claims

1. A hydraulic control valve, comprising: a valve body, the valve body comprising: a valve cavity extending axially in the valve body; a first cavity formed in the valve body on one side in the axial direction of the valve cavity and communicating with the valve cavity; an input channel for inputting fluid; and a plurality of output ports for outputting control fluid, the plurality of output ports including a first output port and a second output port; and a valve spool, the valve spool being disposed in the valve cavity of the valve body, wherein: the valve spool can be in a first position relative to the valve body, move from the first position in a direction away from the first cavity to a second position by the first pressure in the first cavity, and move from the second position in a direction away from the first cavity to a third position by a second pressure greater than the first pressure in the first cavity, when the valve spool is in the first position, the input channel is disconnected from the plurality of output ports, when the valve spool is in the second position, the input channel is connected to the first output port among the plurality of output ports and disconnected from the second output port among the plurality of output ports, and when the valve spool is in the third position, while maintaining the state that the input channel is connected to the first output port among the plurality of output ports, the input channel is connected to the second output port among the plurality of output ports.

2. The hydraulic control valve according to claim 1, wherein: from the time when the input channel starts to communicate with the first output port until the input channel starts to communicate with the second output port, the stroke of the valve spool is between 0.01 mm and 0.5 mm.

3. The hydraulic control valve according to claim 1, wherein: the valve body further includes a return port for returning fluid to the fuel tank. When the valve spool is in the first position, the first output port among the plurality of output ports is connected to the return port, and when the valve spool is in the second position and the third position, the first output port among the plurality of output ports is disconnected from the return port.

4. The hydraulic control valve according to claim 1, further comprising: an input port for inputting fluid and communicating with the input channel, wherein: when the valve spool is in the first position, the input port is disconnected from the plurality of output ports, when the valve spool is in the second position, the input port is connected to the first output port among the plurality of output ports and disconnected from the second output port among the plurality of output ports, and when the valve spool is in the third position, while maintaining the state that the input port is connected to the first output port among the plurality of output ports, the input port is connected to the second output port among the plurality of output ports.

5. The hydraulic control valve according to claim 4, wherein: the valve spool includes: a first end portion facing the first cavity; a second end portion opposite to the first end portion; an axial hole axially extending from the first end portion of the valve spool between the first end portion and the second end portion; a first recess and a second recess formed on the outer periphery of the valve spool; and a first communication hole and a second communication hole respectively communicating the axial hole with the first recess and the second recess. The first recess and the second recess respectively form a first working cavity and a second working cavity with the inner wall of the valve cavity of the valve body, and the input port communicates with the first working cavity. when the valve spool is in the second position, the input port is connected to the first output port among the plurality of output ports through the first working cavity, and When the spool is in the third position, while maintaining the state where the input port is connected to the first output port among the multiple output ports through the first working chamber, the input port is connected to the second output port among the multiple output ports through the first working chamber, the first communication hole, the axial hole, the second communication hole, and the second working chamber.

6. The hydraulic control valve according to claim 5, wherein: The input port is connected to the first chamber through the first working chamber, the first communication hole, and the axial hole.

7. The hydraulic control valve according to claim 1 or 3, wherein: The valve body further includes a second chamber formed in the valve body on the other side in the axial direction of the valve chamber and communicating with the valve chamber, and The hydraulic control valve further includes: a spring, the spring is disposed in the second chamber of the valve body for pushing the spool toward the first chamber of the valve body, and the spool can move relative to the valve body to the first position under the push of the spring toward the first chamber.

8. The hydraulic control valve according to claim 1, further comprising: Multiple input ports communicating with the input passage and leading to the valve chamber, the multiple input ports including a first input port and a second input port, When the spool is in the first position, the multiple input ports are disconnected from the multiple output ports, When the spool is in the second position, the first input port among the multiple input ports is connected to the first output port among the multiple output ports and the multiple input ports are disconnected from the second output port among the multiple output ports, and When the spool is in the third position, while maintaining the state where the first input port among the multiple input ports is connected to the first output port among the multiple output ports, the second input port among the multiple input ports is connected to the second output port among the multiple output ports.

9. The hydraulic control valve according to claim 8, wherein: The spool includes: A first recess and a second recess formed on the outer periphery of the spool, the first recess and the second recess respectively form a first working chamber and a second working chamber with the inner wall of the valve chamber of the valve body, the first input port among the multiple input ports is connected to the first working chamber, and the second input port among the multiple input ports is connected to the second working chamber, When the spool is in the second position, the first input port among the multiple input ports is connected to the first output port among the multiple output ports through the first working chamber, and When the spool is in the third position, while maintaining the state where the first input port among the multiple input ports is connected to the first output port among the multiple output ports through the first working chamber, the second input port among the multiple input ports is connected to the second output port among the multiple output ports through the second working chamber.

10. A variable displacement hydraulic pump, comprising: The hydraulic control valve according to claims 1 to 9; A variable displacement hydraulic pump main body, an output port of the variable displacement hydraulic pump main body is connected to the input passage of the hydraulic control valve; and A pump servo system, the pump servo system is connected to at least one of the multiple output ports of the hydraulic control valve to control the displacement of the variable displacement hydraulic pump main body.

11. The variable displacement hydraulic pump according to claim 10, further comprising: A constant power valve, which is connected to the pump servo system and is used to control the power of the variable displacement hydraulic pump main body. The constant power valve includes: A first input port and a second input port for inputting fluid, wherein the first input port is communicated with the output port of the variable displacement hydraulic pump main body, and the second input port is communicated with the first output port among the multiple output ports of the hydraulic control valve; and An output port connected to the pump servo system for outputting fluid, wherein the second output port among the multiple output ports of the hydraulic control valve is directly connected to the pump servo system.

Images