Load sensing hydraulic system and load sensing hydraulic system control method

Abstract

The application discloses a load-sensitive hydraulic system and a load-sensitive hydraulic system control method. The load-sensitive hydraulic system comprises a load-sensitive pump, a first valve, a second valve, a first actuating element, a second actuating element, a proportional valve and a selector valve. The first valve is a load-sensitive valve, and the second valve is an on-off directional valve. The first actuating element and the second actuating element are connected to a pump outlet of the load-sensitive pump through the first valve and the second valve respectively. An inductive oil port of the load-sensitive pump is in communication with a feedback port of the first valve and a proportional valve inlet of the proportional valve through the selector valve. The proportional valve inlet is connected to an oil circuit between the pump outlet and the second valve. A proportional valve outlet of the proportional valve is connected to an oil tank, and the opening degree of the proportional valve is adjustable. In the load-sensitive hydraulic system and the load-sensitive hydraulic system control method, the opening degree of the proportional valve is adjustable, so that the displacement of the load-sensitive pump can be adjusted through a simple structure, and the structure is simple and the cost is low.

Description

Technical Field

[0001] This application relates to the field of hydraulic technology, and in particular to a load-sensitive hydraulic system and a control method for the load-sensitive hydraulic system. Background Technology

[0002] In the fields of engineering machinery, coal mining machinery, shipbuilding, deep-sea operations, and aerospace, load-sensitive pump control systems have been widely used due to their excellent flow control performance, energy efficiency, and high efficiency. Please refer to... Figure 1 and Figure 2 The feedback port (LS port) of the multi-way valve 91 is connected to the pressure port of the load-sensitive pump 93. The load-sensitive pump 93 adjusts its output displacement according to the pressure at the feedback port. When there are multiple multi-way valves 91, the pressure from the feedback port of one of the multiple multi-way valves 91 is selected and fed back to the load-sensitive pump 93 via the shuttle valve 95. The displacement of the load-sensitive pump 93 is determined by the opening degree of the multi-way valves and must be used with load-sensitive multi-way valves. However, some actuators are equipped with ordinary on / off directional valves with a fixed valve opening. In this case, the load-sensitive regulation function will be lost. In the prior art, in order to achieve the speed change requirements of the actuator, a large number of flow and pressure control elements are usually required, which is costly. Summary of the Invention

[0003] In view of this, the purpose of this application is to provide a load-sensitive hydraulic system and a load-sensitive hydraulic system control method that can achieve speed regulation of actuators equipped with on / off directional valves and have low cost.

[0004] To achieve the above objectives, this application provides a load-sensitive hydraulic system, including a load-sensitive pump, a first valve, a second valve, a first actuator, a second actuator, a proportional valve, and a selector valve. The load-sensitive pump includes a pump outlet and a sensing port. The first valve is a load-sensitive valve and includes a feedback port. The second valve is a switching directional valve. The first actuator is connected to the pump outlet of the load-sensitive pump through the first valve. The second actuator is connected to the pump outlet of the load-sensitive pump through the second valve. The sensing port of the load-sensitive pump is selectively connected to either the feedback port of the first valve or the proportional valve inlet of the proportional valve through the selector valve, so as to adjust the displacement of the load-sensitive pump according to the feedback pressure of the feedback port or the pressure of the proportional valve inlet adjusted according to the opening degree of the proportional valve. The proportional valve inlet is connected to the oil line between the pump outlet of the load-sensitive pump and the second valve. The proportional valve outlet is connected to an oil tank, and the opening degree of the proportional valve is adjustable.

[0005] Optionally, a throttle valve is further provided between the proportional valve inlet and the load-sensitive pump outlet.

[0006] Optionally, the selection valve is a shuttle valve, which includes a first shuttle valve inlet, a second shuttle valve inlet, and a first shuttle valve outlet. The first shuttle valve inlet is connected to the feedback port of the first valve, the second shuttle valve inlet is connected to the proportional valve inlet of the proportional valve, and the first shuttle valve outlet is connected to the sensing port of the load-sensitive pump.

[0007] Optionally, the load-sensitive hydraulic system further includes a main oil circuit, a first branch circuit, and a second branch circuit. The main oil circuit is connected to the pump outlet of the load-sensitive pump, and the load-sensitive pump is used to supply oil to the main oil circuit. The first branch circuit and the second branch circuit are respectively connected to the main oil circuit and supplied with oil by the main oil circuit. The first valve and the first actuator are located on the first branch circuit, and the second valve and the second actuator are located on the second branch circuit.

[0008] Optionally, a switching valve is further provided between the proportional valve inlet and the load-sensitive pump outlet to connect or disconnect the proportional valve and the load-sensitive pump; the switching valve includes a switching valve inlet, a switching valve outlet, and a switching valve return port, the switching valve inlet being connected to the main oil circuit, the proportional valve inlet being connected to the switching valve outlet, and the switching valve return port being connected to the oil tank.

[0009] Optionally, a pressure compensator is also provided on the second branch. The pressure compensator is a pressure reducing valve. The oil inlet and oil outlet of the pressure reducing valve are respectively connected to the main oil circuit and the oil inlet of the second actuator. The two control terminals of the pressure reducing valve are respectively connected to the oil outlet of the pressure reducing valve and the oil inlet of the second actuator. The second valve is located between the pressure compensator and the second actuator.

[0010] Optionally, the second valve includes a first oil port, a second oil port, a third oil port, and a fourth oil port. A shuttle valve is also provided on the second branch. The shuttle valve includes a third shuttle valve inlet, a fourth shuttle valve inlet, and a second shuttle valve outlet. The first oil port is connected to the pressure compensator, the second oil port is connected to the oil tank, the third oil port is connected to the first working end of the second actuator, the fourth oil port is connected to the second working end of the second actuator, the third shuttle valve inlet is connected to the oil passage between the third oil port and the first working end of the second actuator, the fourth shuttle valve inlet is connected to the oil passage between the fourth oil port and the second working end of the second actuator, and the second shuttle valve outlet is connected to one control end of the pressure compensator. The other control end of the pressure compensator is connected to the first oil port. When the second valve is in its first position, the first oil port and the fourth oil port are connected, and the second oil port and the third oil port are connected; when the second valve is in its second position, the first oil port and the third oil port are connected, and the second oil port and the fourth oil port are connected; when the second valve is in its third position, the second oil port, the third oil port and the fourth oil port are connected to each other and disconnected from the first oil port.

[0011] Optionally, the selection valve is a directional valve; the directional valve includes a first directional port, a second directional port, and a third directional port, the first directional port being connected to the feedback port of the first valve, the second directional port being connected to the proportional valve inlet of the proportional valve, and the third directional port being connected to the sensing port of the load-sensitive pump; when the selection valve is in its first position, the second directional port and the third directional port are connected, and when the selection valve is in its second position, the first directional port and the third directional port are connected.

[0012] Optionally, the second valve is integrated on the first valve to form a multi-way valve. The load-sensitive hydraulic system also includes a main oil circuit, which is connected to the pump outlet of the load-sensitive pump. The load-sensitive pump is used to supply oil to the main oil circuit, and the main oil circuit supplies oil to the first valve and the second valve.

[0013] This application also provides a load-sensitive hydraulic system control method for controlling the aforementioned load-sensitive hydraulic system, the load-sensitive hydraulic system control method comprising: The oil output by the load-sensitive pump is controlled to reach the second actuator through the second valve, but not the first actuator. The selector valve is controlled to connect the sensing port of the load-sensitive pump to the proportional valve inlet. The opening degree of the proportional valve is adjusted according to the speed requirement of the second actuator to adjust the displacement of the load-sensitive pump.

[0014] In the load-sensitive hydraulic system and load-sensitive hydraulic system control method of this application, by setting an adjustable proportional valve, the displacement of the load-sensitive pump can be adjusted through a simple structure, which is simple in structure and low in cost. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a load-sensitive hydraulic system.

[0017] Figure 2 This is a schematic diagram of another load-sensitive hydraulic system.

[0018] Figure 3 This is a schematic diagram of the structure of a load-sensitive hydraulic system provided in an embodiment of this application.

[0019] Figure 4 This is a schematic diagram of a load-sensitive hydraulic system provided in another embodiment of this application. Detailed Implementation

[0020] The specific embodiments of this application will now be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of this application. Based on the description of this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0021] In the description of this application, unless otherwise expressly specified and limited, the terms "set," "install," "connect," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms based on the specific circumstances.

[0022] The terms “first,” “second,” “third,” etc., are used merely to distinguish numerical values ​​or elements with similar properties, rather than to indicate or imply relative importance or a specific order.

[0023] The terms “include,” “comprising,” or any other variation thereof are intended to cover non-exclusive inclusion, which includes not only the elements listed but also other elements not expressly listed.

[0024] This invention provides a load-sensitive hydraulic system, please refer to... Figure 3 One embodiment of the load-sensitive hydraulic system includes a load-sensitive pump 11, a first valve 13, a second valve 15, a first actuator 17, a second actuator 19, a proportional valve 21, and a selector valve 23. The load-sensitive pump 11 includes a pump outlet 111 and a sensing port 113. The first valve 13 is a load-sensitive valve and includes a feedback port 132. The second valve 15 is a switching directional valve. The first actuator 17 is connected to the pump outlet 111 of the load-sensitive pump 11 through the first valve 13, and the second actuator 19 is connected to the pump outlet 111 of the load-sensitive pump 11 through the second valve 15. The sensing port 113 of the load-sensitive pump 11 is selectively connected to either the feedback port 132 of the first valve 13 or the proportional valve inlet 212 of the proportional valve 21 via the selector valve 23, to adjust the displacement of the load-sensitive pump 11 according to the feedback pressure of the feedback port 132 or the pressure of the proportional valve inlet 212 adjusted according to the opening degree of the proportional valve 21. The proportional valve 21 has a proportional valve inlet 212 connected to the oil line between the pump outlet 111 of the load-sensitive pump 11 and the second valve 15, and a proportional valve outlet 214 connected to the oil tank. The opening degree of the proportional valve 21 is adjustable.

[0025] In the load-sensitive hydraulic system of this embodiment, the displacement of the load-sensitive pump can be adjusted through a simple structure by setting an adjustable proportional valve. The structure is simple and the cost is low. In particular, when it is necessary to add new actuators to the existing hydraulic system, the function of the load-sensitive valve can be achieved with simple hydraulic components without major modifications to the entire system or replacement of the original multi-way valve.

[0026] In this embodiment, a throttle valve 25 is also provided between the proportional valve inlet 212 of the proportional valve 21 and the pump outlet 111 of the load-sensitive pump 11. The pressures on both sides of the throttle valve 25 are different. The pressure at the end of the throttle valve 25 connected to the pump outlet 111 of the load-sensitive pump 11 is the output pressure of the load-sensitive pump 11. By setting the throttle valve 25, the pressure at the proportional valve inlet 212 of the proportional valve 21 can be changed according to the opening degree of the proportional valve 21.

[0027] In this embodiment, valve 23 is selected as a shuttle valve. The shuttle valve includes a first shuttle valve inlet, a second shuttle valve inlet, and a first shuttle valve outlet. The first shuttle valve inlet is connected to the feedback port 132 of the first valve 13, the second shuttle valve inlet is connected to the proportional valve inlet 212 of the proportional valve 21, and the first shuttle valve outlet is connected to the sensing port 113 of the load-sensitive pump 11. During operation, the port with the higher pressure between the first and second shuttle valve inlets is connected to the first shuttle valve outlet.

[0028] In this embodiment, the load-sensitive hydraulic system further includes a main oil circuit 27, a first branch circuit 29, and a second branch circuit 31. The main oil circuit 27 is connected to the pump outlet 111 of the load-sensitive pump 11, and the load-sensitive pump 11 supplies oil to the main oil circuit 27 when it is working. The first branch circuit 29 and the second branch circuit 31 are respectively connected to the main oil circuit 27 and are supplied with oil by the main oil circuit 27. The first valve 13 and the first actuator 17 are disposed on the first branch circuit 29, and the second valve 15 and the second actuator 19 are disposed on the second branch circuit 31. Specifically, the first valve 13 can be a multi-way valve, and the second valve 15 can be a three-position four-way valve. Specifically, the second actuator 19 is a hydraulic cylinder in this embodiment, but of course, the second actuator 19 can also be a hydraulic motor or other actuators.

[0029] In this embodiment, a switching valve 33 is further provided between the proportional valve inlet 212 of the proportional valve 21 and the pump outlet 111 of the load-sensitive pump 11 to connect or disconnect the proportional valve 21 and the load-sensitive pump 11. The switching valve 33 includes a switching valve inlet 332 and a switching valve outlet 334. The switching valve inlet 332 is connected to the main oil circuit 27, and the proportional valve inlet 212 is connected to the switching valve outlet 334 of the switching valve 33. In this embodiment, the switching valve 33 can be a solenoid valve, which is controlled by energizing or de-energizing the switching valve 33. Specifically, the switching valve 33 also includes a switching valve return port 336, which is connected to the oil tank. When the switching valve 33 is in its first position, the oil inlet 332 of the switching valve is closed, and the oil outlet 334 of the switching valve is connected to the oil return port 336 of the switching valve. When the switching valve 33 is in its second position, the oil inlet 332 of the switching valve is connected to the oil outlet 334 of the switching valve, and the oil return port 336 of the switching valve is closed.

[0030] In this embodiment, the first branch 29 is also provided with an overflow valve 35 for overflowing the first branch 29.

[0031] In this embodiment, a pressure compensator 37 is also provided on the second branch 31. The pressure compensator 37 is used to stabilize the flow rate of the second branch 31, so that the flow rate of the second branch 31 is not affected by the load of the second actuator 19. Specifically, the pressure compensator 37 can be a pressure reducing valve, which is used to maintain a constant pressure difference across the pressure reducing valve. More specifically, the inlet and outlet of the pressure reducing valve are respectively connected to the inlet of the main oil circuit 27 and the second actuator 19, and the two control terminals of the pressure reducing valve are respectively connected to the outlet of the pressure reducing valve and the inlet of the second actuator 19.

[0032] Specifically, the second valve 15 is located between the pressure compensator 37 and the second actuator 19. The second valve 15 includes a first oil port 151, a second oil port 152, a third oil port 153 and a fourth oil port 154. The second branch 31 is also provided with a shuttle valve 39, which includes a third shuttle valve inlet, a fourth shuttle valve inlet and a second shuttle valve outlet. The first oil port 151 is connected to the pressure compensator 37, the second oil port 152 is connected to the oil tank, the third oil port 153 is connected to the first working end of the second actuator 19 (e.g., the rodless chamber of the cylinder), the fourth oil port 154 is connected to the second working end of the second actuator 19 (e.g., the rod chamber of the cylinder), the third shuttle valve inlet is connected to the oil passage between the third oil port 153 and the first working end of the second actuator 19, the fourth shuttle valve inlet is connected to the oil passage between the fourth oil port 154 and the second working end of the second actuator 19, the second shuttle valve outlet is connected to one control end of the pressure compensator 37, and the other control end of the pressure compensator 37 is connected to the first oil port 151. The second valve 15 is located in its first position (…). Figure 3 When the valve is in its left position, the first oil port 151 and the fourth oil port 154 are connected, and the second oil port 152 and the third oil port 153 are connected; the second valve 15 is in its second position (…). Figure 3 When the valve is in its right position, the first oil port 151 and the third oil port 153 are connected, and the second oil port 152 and the fourth oil port 154 are connected; the second valve 15 is in its third position ( Figure 3 When the oil is in the middle position, the second oil port 152, the third oil port 153 and the fourth oil port 154 are connected to each other and disconnected from the first oil port 151.

[0033] In this embodiment, a hydraulic lock 41 is also provided on the second branch 29 to lock the second branch 29, so that the second actuator 19 remains stationary under a certain load. Specifically, the hydraulic lock 41 includes a first hydraulic lock control valve 412 and a second hydraulic lock control valve 414. The first hydraulic lock control valve 412 is located on the oil line between the third oil port 153 and the first working end of the second actuator 19. The first hydraulic lock control valve 412 includes a one-way valve that only allows oil to flow from the third oil port 153 to the second actuator 19. The second hydraulic lock control valve 414 is located on the oil line between the fourth oil port and the second working end of the second actuator 19. The second hydraulic lock control valve 414 includes a one-way valve that only allows oil to flow from the fourth oil port 154 to the second actuator 19. The control end of the first hydraulic lock control valve 412 is connected to the fourth oil port 154, and the control end of the second hydraulic lock control valve 414 is connected to the third oil port 153. When the second valve 15 is in its third position, the second actuator 19 is stationary under the action of the two check valves; when the second valve 15 is in its first position, the pressure oil from the main oil circuit 27 reaches the second working end of the second actuator 19 through the first oil port 151, the fourth oil port 154, and the check valve of the second hydraulic lock control valve 414, while simultaneously opening the check valve of the first hydraulic lock control valve 412 to drain oil; when the second valve 15 is in its second position, the pressure oil from the main oil circuit 27 reaches the first working end of the second actuator 19 through the first oil port 151, the third oil port 153, and the check valve of the first hydraulic lock control valve 412, while simultaneously opening the check valve of the second hydraulic lock control valve 414 to drain oil.

[0034] In this embodiment, the load-sensitive hydraulic system also includes an engine 43, which is connected to the load-sensitive pump 11 and is used to drive the load-sensitive pump 11 to work.

[0035] It is understood that the load-sensitive hydraulic system may include multiple first branches 29 and / or multiple second branches 31. It is understood that the output port of the first valve 13 may be connected to multiple first actuators 17, or only one first actuator 17 may be connected, and the number may be set as needed.

[0036] The working principle of the load-sensitive hydraulic system in this embodiment is briefly described below.

[0037] When the first actuator 17 needs to operate, the switching valve 33 is closed, the second valve 15 is in the neutral position, and the pressure oil output by the load-sensitive pump 11 to the main oil circuit 27 flows to the first branch 29 instead of the second branch 31. The pressure oil passes through the first valve 13 and reaches the first actuator 17. The first actuator 17 operates, while the second actuator 19 does not operate. At this time, the pressure at the inlet of the first shuttle valve of the selector valve 23 is greater than the pressure at the inlet of the second shuttle valve. Therefore, the oil at the inlet of the first shuttle valve flows to the outlet of the first shuttle valve, thereby feeding back the pressure at the feedback port 132 of the first valve 13, which reflects the load pressure, to the sensing port 113 of the load-sensitive pump 11. The load-sensitive pump 11 adjusts the displacement according to the load pressure. When the second actuator 19 needs to operate, the first valve 13 is closed, the switching valve 33 is open, and the second valve 15 is in the left or right position. The pressure oil output by the load-sensitive pump 11 to the main oil circuit 27 flows to the second branch 31 instead of the first branch 29. The pressure oil passes through the second valve 15 to reach the second actuator 19, which operates. The first actuator 17 does not operate. At this time, part of the oil in the main oil circuit 27 passes through the throttle valve 25 and the switching valve 33 to reach the proportional valve 21, and part of the oil flows back to the oil tank through the proportional valve 21. The pressure at the inlet of the first shuttle valve of the selector valve 23 is less than the pressure at the inlet of the second shuttle valve. Therefore, the oil at the inlet of the second shuttle valve flows to the outlet of the first shuttle valve. This allows the pressure at the inlet of the proportional valve, determined by the opening of the proportional valve 21, to be fed back to the sensing port 113 of the load-sensitive pump 11. The load-sensitive pump 11 adjusts its displacement according to the pressure at the inlet of the proportional valve, thereby regulating the speed of the second actuator 19. The opening degree of the proportional valve 21 can be adjusted according to the speed requirement of the second actuator 19.

[0038] Please refer to Figure 4 In another embodiment of the load-sensitive hydraulic system of this application, a throttle valve 25 is also provided between the proportional valve inlet 212 of the proportional valve 21 and the pump outlet 111 of the load-sensitive pump 11. The pressures on both sides of the throttle valve 25 are different. The pressure at the end of the throttle valve 25 connected to the pump outlet 111 of the load-sensitive pump 11 is the output pressure of the load-sensitive pump 11. By providing the throttle valve 25, the pressure at the proportional valve inlet 212 of the proportional valve 21 can be changed according to the adjustment of the opening degree of the proportional valve 21.

[0039] In this embodiment, the selector valve 23 is a directional control valve. The directional control valve includes a first directional control port, a second directional control port, and a third directional control port. The first directional control port is connected to the feedback port 132 of the first valve 13, the second directional control port is connected to the proportional valve inlet port 212 of the proportional valve 21, and the third directional control port is connected to the sensing port 113 of the load-sensitive pump 11. The selector valve 23 is in its first position (i.e., ...). Figure 4 When the valve is in its left position, the second and third reversing ports are connected, and the selector valve 23 is in its second position (i.e., the left position). Figure 4When the right position is in the middle, the first reversing oil port and the third reversing oil port are connected.

[0040] In this embodiment, the second valve 15 is integrated with the first valve 13 to form a multi-way valve. The load-sensitive hydraulic system also includes a main oil passage 27, which is connected to the pump outlet 111 of the load-sensitive pump 11. When the load-sensitive pump 11 is working, it supplies oil to the main oil passage 27. The main oil passage 27 supplies oil to the first valve 13 and the second valve 15. Specifically, the second actuator 19 is a hydraulic cylinder in this embodiment, but it can also be a hydraulic motor or other actuators. That is to say, in this embodiment, it is equivalent to... Figure 3 In the embodiment shown, the first branch 29 and the second branch 31 are merged, and the first valve 13 and the second valve 15 are integrated together.

[0041] In this embodiment, an overflow valve 35 is also provided on the main oil circuit 27 for overflowing the main oil circuit 27.

[0042] In this embodiment, a hydraulic lock 41 is also provided between the second actuator 19 and the second valve 15 to lock the corresponding oil circuit, so that the second actuator 19 remains stationary under a certain load. Specifically, the hydraulic lock 41 includes a first hydraulic lock control valve 412 and a second hydraulic lock control valve 414. The first hydraulic lock control valve 412 is located in the oil circuit between the second valve 15 and the first working end of the second actuator 19, and includes a one-way valve that only allows oil to flow from the second valve 15 to the second actuator 19. The second hydraulic lock control valve 414 is located in the oil circuit between the second valve 15 and the second working end of the second actuator 19, and includes a one-way valve that only allows oil to flow from the second valve 15 to the second actuator 19. The control end of the first hydraulic lock control valve 412 is connected to the oil circuit between the second valve 15 and the second working end, and the control end of the second hydraulic lock control valve 414 is connected to the oil circuit between the second valve 15 and the first working end. The working principle of the hydraulic lock 41 is similar to... Figure 3 The embodiments shown are similar and will not be described again here.

[0043] The working principle of the load-sensitive hydraulic system in this embodiment is briefly described below.

[0044] When the first actuator 17 needs to operate, the first valve 13 opens, the second valve 15 closes, and the selector valve 23 is in the right position. The pressure oil output by the load-sensitive pump 11 to the main oil circuit 27 passes through the first valve 13 without passing through the second valve 15. The pressure oil passes through the first valve 13 to reach the first actuator 17, and the first actuator 17 operates. The second actuator 19 does not operate. At this time, the first reversing port and the third reversing port of the selector valve 23 are connected, so that the pressure of the feedback port 132 of the first valve 13, which reflects the load pressure of the first actuator 17, is fed back to the sensing port 113 of the load-sensitive pump 11. The load-sensitive pump 11 adjusts the displacement according to the load pressure. When the second actuator 19 needs to operate, the first valve 13 closes, the second valve 15 opens, and the selector valve 23 is in the left position. The pressure oil output from the load-sensitive pump 11 to the main oil circuit 27 passes through the second valve 15 without passing through the first valve 13. The pressure oil then reaches the second actuator 19, causing the second actuator 19 to operate. The first actuator 17 does not operate. At this time, part of the oil in the main oil circuit 27 passes through the throttle valve 25 to the proportional valve 21, and part of the oil flows back to the oil tank through the proportional valve 21. The second and third reversing ports of the selector valve 23 are connected, thereby allowing the pressure at the proportional valve inlet, determined by the opening of the proportional valve 21, to be fed back to the sensing port 113 of the load-sensitive pump 11. The load-sensitive pump 11 adjusts its displacement according to the pressure at the proportional valve inlet, thereby regulating the speed of the second actuator 19. The opening of the proportional valve 21 can be adjusted according to the speed requirements of the second actuator 19.

[0045] This application also provides a load-sensitive hydraulic system control method for controlling the load-sensitive hydraulic system of the above embodiments. One embodiment of the load-sensitive hydraulic system control method includes: S11, the oil output by the load-sensitive pump 11 is controlled to reach the second actuator 19 through the second valve 15, but not to reach the first actuator 17. The control selector valve 23 connects the sensing oil port 113 of the load-sensitive pump 11 with the proportional valve inlet 212 of the proportional valve 21.

[0046] S13, adjust the opening of the proportional valve 21 according to the speed requirement of the second actuator 19 to adjust the displacement of the load-sensitive pump 11.

[0047] In this embodiment, the load-sensitive hydraulic system control method further includes: S15, the oil output by the load-sensitive pump 11 is controlled to reach the first actuator 17 through the first valve 13, but not the second actuator 19. The control selector valve 23 connects the sensing port 113 of the load-sensitive pump 11 with the feedback port 132 of the first valve 13, so that the displacement of the load-sensitive pump 11 is adjusted according to the pressure of the feedback port 132 of the first valve 13.

[0048] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A load-sensitive hydraulic system, characterized in that, The system includes a load-sensitive pump (11), a first valve (13), a second valve (15), a first actuator (17), a second actuator (19), a proportional valve (21), and a selector valve (23). The load-sensitive pump (11) includes a pump outlet (111) and a sensing port (113). The first valve (13) is a load-sensitive valve and includes a feedback port (132). The second valve (15) is a switching directional valve. The first actuator (17) is connected to the pump outlet (111) of the load-sensitive pump (11) through the first valve (13). The second actuator (19) is connected to the pump outlet (111) of the load-sensitive pump (11) through the second valve (15). The sensing port (113) of the load-sensitive pump (11) is selectively connected to the feedback port (132) of the first valve (13) and the proportional valve inlet (212) of the proportional valve (21) through the selection valve (23) to adjust the displacement of the load-sensitive pump (11) according to the feedback pressure of the feedback port (132) or the pressure of the proportional valve inlet (212) adjusted according to the opening of the proportional valve (21); wherein, the proportional valve inlet (212) of the proportional valve (21) is connected to the oil line between the pump outlet (111) of the load-sensitive pump (11) and the second valve (15), the proportional valve outlet (214) of the proportional valve (21) is connected to the oil tank, and the opening of the proportional valve (21) is adjustable.

2. The load-sensitive hydraulic system as described in claim 1, characterized in that, A throttle valve (25) is also provided between the proportional valve inlet (212) of the proportional valve (21) and the pump outlet (111) of the load-sensitive pump (11).

3. The load-sensitive hydraulic system as described in claim 1, characterized in that, The selector valve (23) is a shuttle valve, which includes a first shuttle valve inlet, a second shuttle valve inlet, and a first shuttle valve outlet. The first shuttle valve inlet is connected to the feedback port (132) of the first valve (13), the second shuttle valve inlet is connected to the proportional valve inlet (212) of the proportional valve (21), and the first shuttle valve outlet is connected to the sensing port (113) of the load-sensitive pump (11).

4. The load-sensitive hydraulic system as described in claim 3, characterized in that, The load-sensitive hydraulic system further includes a main oil circuit (27), a first branch circuit (29), and a second branch circuit (31). The main oil circuit (27) is connected to the pump outlet (111) of the load-sensitive pump (11). The load-sensitive pump (11) is used to supply oil to the main oil circuit (27). The first branch circuit (29) and the second branch circuit (31) are respectively connected to the main oil circuit (27) and supplied with oil by the main oil circuit (27). The first valve (13) and the first actuator (17) are located on the first branch circuit (29), and the second valve (15) and the second actuator (19) are located on the second branch circuit (31).

5. The load-sensitive hydraulic system as described in claim 4, characterized in that, A switching valve (33) is also provided between the proportional valve inlet (212) of the proportional valve (21) and the pump outlet (111) of the load-sensitive pump (11) to connect or disconnect the proportional valve (21) and the load-sensitive pump (11); the switching valve (33) includes a switching valve inlet (332), a switching valve outlet (334) and a switching valve return port (336), the switching valve inlet (332) is connected to the second branch (31), the proportional valve inlet (212) is connected to the switching valve outlet (334) of the switching valve (33), and the switching valve return port (336) is connected to the oil tank.

6. The load-sensitive hydraulic system as described in claim 4, characterized in that, The second valve (15) includes a first oil port (151), and a pressure compensator (37) is also provided on the second branch (31). The pressure compensator (37) is a pressure reducing valve. The oil inlet and oil outlet of the pressure reducing valve are respectively connected to the main oil circuit (27) and the first oil port (151). The two control ends of the pressure reducing valve are respectively connected to the oil outlet of the pressure reducing valve and the oil inlet of the second actuator (19). The second valve (15) is located between the pressure compensator (37) and the second actuator (19).

7. The load-sensitive hydraulic system as described in claim 6, characterized in that, The second valve (15) further includes a second oil port (152), a third oil port (153), and a fourth oil port (154). A shuttle valve (39) is also provided on the second branch (31). The shuttle valve (39) includes a third shuttle valve inlet, a fourth shuttle valve inlet, and a second shuttle valve outlet. The first oil port (151) is connected to the pressure compensator (37), the second oil port (152) is connected to the oil tank, the third oil port (153) is connected to the first working end of the second actuator (19), and the fourth oil port (154)... The second working end of the second actuator (19) is connected to the second working end of the third shuttle valve. The oil inlet of the third shuttle valve is connected to the oil passage between the third oil port (153) and the first working end of the second actuator (19). The oil inlet of the fourth shuttle valve is connected to the oil passage between the fourth oil port (154) and the second working end of the second actuator (19). The oil outlet of the second shuttle valve is connected to one control end of the pressure compensator (37). The other control end of the pressure compensator (37) is connected to the first oil port (151). When the second valve (15) is in its first position, the first oil port (151) and the fourth oil port (154) are connected, and the second oil port (152) and the third oil port (153) are connected; when the second valve (15) is in its second position, the first oil port (151) and the third oil port (153) are connected, and the second oil port (152) and the fourth oil port (154) are connected; when the second valve (15) is in its third position, the second oil port (152), the third oil port (153) and the fourth oil port (154) are connected to each other and disconnected from the first oil port (151).

8. The load-sensitive hydraulic system as described in claim 1, characterized in that, The selector valve (23) is a reversing valve; the reversing valve includes a first reversing port, a second reversing port and a third reversing port. The first reversing port is connected to the feedback port (132) of the first valve (13), the second reversing port is connected to the proportional valve inlet (212) of the proportional valve (21), and the third reversing port is connected to the sensing port (113) of the load-sensitive pump (11). When the selector valve (23) is in its first position, the second reversing port and the third reversing port are connected. When the selector valve (23) is in its second position, the first reversing port and the third reversing port are connected.

9. The load-sensitive hydraulic system as described in claim 8, characterized in that, The second valve (15) is integrated on the first valve (13) to form a multi-way valve. The load-sensitive hydraulic system also includes a main oil circuit (27), which is connected to the pump outlet (111) of the load-sensitive pump (11). The load-sensitive pump (11) is used to supply oil to the main oil circuit (27), which supplies oil to the first valve (13) and the second valve (15).

10. A control method for a load-sensitive hydraulic system, used to control the load-sensitive hydraulic system as described in any one of claims 1-9, characterized in that, The load-sensitive hydraulic system control method includes: The oil output by the load-sensitive pump (11) is controlled to reach the second actuator (19) through the second valve (15) and not reach the first actuator (17). The selector valve (23) is controlled to connect the sensing port (113) of the load-sensitive pump (11) with the proportional valve inlet (212) of the proportional valve (21). The opening of the proportional valve (21) is adjusted according to the speed requirement of the second actuator (19) to adjust the displacement of the load-sensitive pump (11).

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