Load sensing hydraulic circuit

Abstract

The application discloses a load-sensitive hydraulic circuit, which comprises a load-sensitive pump, a load-sensitive multi-way valve, a first oil cylinder, a control valve group, a first reversing valve, a second oil cylinder and a selection valve. The load-sensitive pump supplies oil to the first oil cylinder through the load-sensitive multi-way valve or supplies oil to the second oil cylinder through the control valve group and the first reversing valve. The load-sensitive multi-way valve comprises a first feedback port, the control valve group comprises a second feedback port, and the selection valve selectively connects the feedback oil port with the first feedback port or the feedback oil port with the second feedback port. The load-sensitive hydraulic circuit can supply oil to different oil cylinders through the load-sensitive multi-way valve and the control valve group, thereby meeting different action requirements of the oil cylinders. Meanwhile, the load-sensitive hydraulic circuit can share the same load-sensitive pump, thereby reducing the number of driving sources and hydraulic pumps and lowering production cost.

Description

Technical Field

[0001] This invention relates to the field of load-sensitive hydraulic control technology, and in particular to a load-sensitive hydraulic circuit. Background Technology

[0002] Rotary drilling rigs are construction machines suitable for hole-forming operations in building foundation engineering. They are mainly suitable for construction in soil layers such as sand, cohesive soil, and silty soil. They are widely used in various foundation constructions such as cast-in-place piles, continuous walls, and foundation reinforcement. They generally adopt hydraulic crawler telescopic chassis, self-lifting foldable drill mast, telescopic drill rod, automatic vertical detection and adjustment, and digital display of hole depth. The whole machine is generally operated by hydraulic pilot control and load sensing, and features easy and comfortable operation.

[0003] Rotary drilling rigs contain various types of hydraulic cylinders, such as luffing cylinders, bracing cylinders, and outrigger cylinders. Cylinders performing different actions typically have different operational requirements. For example, bracing cylinders require gradual flow rate adjustment to control the mast angle, while outrigger cylinders require rapid switching with high flow rates. Currently, different hydraulic pumps typically supply oil to cylinders with different functions, necessitating the installation of multiple pumps and resulting in high costs.

[0004] The preceding description is intended to provide general background information and does not necessarily constitute prior art. Summary of the Invention

[0005] The purpose of this invention is to provide a load-sensitive hydraulic circuit that can reduce the number of hydraulic pumps and has a lower cost.

[0006] This invention provides a load-sensitive hydraulic circuit, including a load-sensitive pump, a load-sensitive multi-way valve, a first cylinder, a control valve assembly, a first directional valve, a second cylinder, and a selector valve. The load-sensitive pump includes a pressure port and a feedback port. The load-sensitive multi-way valve and the control valve assembly are respectively connected to the pressure port of the load-sensitive pump. The first cylinder is connected to the load-sensitive multi-way valve. The first directional valve is connected between the control valve assembly and the second cylinder. The first directional valve is used to disconnect or connect the control valve assembly and the second cylinder. The load-sensitive pump supplies oil to the first cylinder through the load-sensitive multi-way valve, or supplies oil to the second cylinder through the control valve assembly and the first directional valve. The load-sensitive multi-way valve includes a first feedback port, and the control valve assembly includes a second feedback port. The selector valve selectively connects the feedback port to the first feedback port or the feedback port to the second feedback port.

[0007] In one embodiment, the load-sensitive multi-way valve includes a first oil inlet, a first oil return, a first working oil port, and a second working oil port. The first oil inlet is connected to the pressure oil port of the load-sensitive pump, the first oil return is connected to the oil tank, and the first working oil port and the second working oil port are respectively connected to the first chamber and the second chamber of the first oil cylinder.

[0008] In one embodiment, the load-sensitive multi-way valve further includes a control valve, a main valve, a first electro-proportional pressure reducing valve, and a second electro-proportional pressure reducing valve. The control valve is connected between the first oil inlet and the main valve to control the connection or disconnection between the first oil inlet and the main valve. The two control terminals of the main valve are respectively connected to the first electro-proportional pressure reducing valve and the second electro-proportional pressure reducing valve, so that the first electro-proportional pressure reducing valve and the second electro-proportional pressure reducing valve control the switching position, thereby connecting or disconnecting the output port of the control valve from the first working oil port or the second working oil port. The main valve is also used to connect or disconnect the first oil inlet from the first feedback port.

[0009] In one embodiment, the control valve includes a first position and a second position, and includes a first port, a second port, and a third port. The first oil inlet port is connected to the first port, the second port is connected to the control terminal of the control valve, and the third port is connected to the main valve. In the first position, the first port and the second port are connected; in the second position, the first port, the second port, and the third port are connected. The main valve includes a fourth position, a fifth position, and a sixth position, and includes a fourth port, a fifth port, a sixth port, a seventh port, an eighth port, and a ninth port. The fourth port is connected to the third port of the control valve, the fifth port is connected to the first oil return port, the sixth port is connected to the first working oil port, and the seventh port is connected to... The second working port, when in the fourth position, connects the fifth, sixth, and seventh ports; when in the fifth position, connects the fourth, seventh, and eighth ports; and connects the fifth, sixth, and ninth ports. When in the sixth position, the fourth, sixth, and eighth ports are connected; and the fifth, seventh, and ninth ports are also connected. The load-sensitive multi-way valve further includes a first shuttle valve and a second shuttle valve. The outlet of the first shuttle valve is connected to the first feedback port, and the two inlets of the first shuttle valve are respectively connected to the outlet of the second shuttle valve and the first return port. The two inlets of the second shuttle valve are respectively connected to the eighth and ninth ports of the main valve.

[0010] In one embodiment, the control valve group includes a second oil inlet, a second oil return port, and an oil output port. The second oil inlet is connected to the pressure port of the load-sensitive pump, the second oil return port is connected to the oil tank, and the oil output port is connected to the first directional valve to supply oil to the second cylinder through the first directional valve.

[0011] In one embodiment, the control valve group further includes a two-way cartridge valve, a second directional valve, and a third directional valve. The second directional valve is used to switch states to control the on / off state of the two-way cartridge valve. The on / off state of the two-way cartridge valve is used to disconnect or connect the second oil inlet port and the output oil port. The third directional valve is used to selectively connect the second oil return port and the second feedback port, and the second feedback port and the output oil port. The first directional valve, the second directional valve, and the third directional valve are all solenoid directional valves.

[0012] In one embodiment, the control valve group further includes a first throttling element, the first oil port of the two-way cartridge valve is connected to the second oil inlet of the control valve group, the second oil port of the two-way cartridge valve is connected to the output oil port, the second oil inlet is also connected to two oil chambers of the two-way cartridge valve respectively, and the first throttling element is connected between the two-way cartridge valve and the second directional valve.

[0013] In one embodiment, the second directional valve is a two-position two-way solenoid directional valve, with one port of the second directional valve connected to the two-way cartridge valve and the other port connected to the second return port and the third directional valve.

[0014] In one embodiment, the third directional valve includes a fourth port, a fifth port, a sixth port, and a seventh port. The fourth port is connected to the oil passage between the two-way cartridge valve and the output port via a second throttling element. The fifth port is connected to the second return port, and the sixth port is connected to the second feedback port. The third directional valve includes a seventh position and an eighth position. In the seventh position, the fourth port, the fifth port, the sixth port, and the seventh port are interconnected. In the eighth position, the fourth port is connected to the sixth port, and the fifth port is connected to the seventh port.

[0015] In one embodiment, the second hydraulic cylinder includes a third chamber and a fourth chamber; the first reversing valve includes an eighth port, a ninth port, a tenth port, and an eleventh port, wherein the eighth port is connected to the output port, the ninth port is connected to the oil tank, the tenth port is connected to the third chamber, and the eleventh port is connected to the fourth chamber; the first reversing valve includes a ninth position, a tenth position, and an eleventh position; in the ninth position, both the third and fourth chambers are connected to the oil tank, and the eighth port is disconnected from the ninth, tenth, and eleventh ports; in the tenth position, the eighth port is connected to the tenth port, and the ninth port is connected to the eleventh port; in the eleventh position, the eighth port is connected to the eleventh port, and the ninth port is connected to the tenth port.

[0016] In the load-sensitive hydraulic circuit provided by this invention, oil supply to different cylinders is achieved through load-sensitive multi-way valves and control valve groups, which can meet the different action requirements of the cylinders. At the same time, by achieving oil supply to different cylinders through load-sensitive multi-way valves and control valve groups, the same load-sensitive pump can be used, achieving the effect of single pump control of load-sensitive circuit and simple hydraulic resistance circuit, reducing the number of drive sources and hydraulic pumps used, and reducing production costs. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a state structure of a load-sensitive hydraulic circuit according to the first embodiment of the present invention.

[0018] Figure 2 for Figure 1 The diagram shows another state of the load-sensitive hydraulic circuit.

[0019] Figure 3 This is a schematic diagram of the load-sensitive hydraulic circuit according to the second embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of the load-sensitive hydraulic circuit according to the third embodiment of the present invention. Detailed Implementation

[0021] To further illustrate the technical methods and effects of the present invention in order to achieve the intended purpose, the specific implementation methods, structure, features and effects of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0022] To further illustrate the technical methods and effects of the present invention in order to achieve the intended purpose, the specific implementation methods, structure, features and effects of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0023] First Embodiment

[0024] Please refer to Figure 1 The load-sensitive hydraulic circuit of the first embodiment of the present invention includes a load-sensitive pump 11, a load-sensitive multi-way valve 13, a first cylinder 15, a control valve group 17, a first directional valve 19, a second cylinder 21, and a selector valve 23. The load-sensitive pump 11 includes a pressure port 112 and a feedback port 114. The load-sensitive multi-way valve 13 and the control valve group 17 are respectively connected to the pressure port 112 of the load-sensitive pump 11. The first cylinder 15 is connected to the load-sensitive multi-way valve 13. The first directional valve 19 is connected between the control valve group 17 and the second cylinder 21. The load-sensitive pump 11 supplies oil to the first cylinder 15 through the load-sensitive multi-way valve 13, or supplies oil to the second cylinder 21 through the control valve group 17 and the first directional valve 19. The load-sensitive multi-way valve 13 includes a first feedback port 130, the control valve group 17 includes a second feedback port 172, and the selector valve 23 selectively connects the feedback port 114 to the first feedback port 130 or the feedback port 114 to the second feedback port 172.

[0025] In this embodiment, a constant differential pressure valve is provided on the load-sensitive pump 11. The pressure Δp1 of the feedback port 114 is compared with the pressure difference Δp of the constant differential pressure valve on the load-sensitive pump 11. If Δp1 is greater than Δp, the displacement of the load-sensitive pump 11 is reduced. If Δp1 is less than Δp, the displacement of the load-sensitive pump 11 is increased. The ultimate goal is to maintain the two pressure differences equal so that the flow rate of the load-sensitive pump 11 is equal to the flow rate required by the actuator.

[0026] In this embodiment, the load-sensitive multi-way valve 13 includes a first oil inlet 131, a first oil return port 132, a first working oil port 133, and a second working oil port 134. The first oil inlet 131 is connected to the pressure oil port 112 of the load-sensitive pump 11, the first oil return port 132 is connected to the oil tank for oil return, and the first working oil port 133 and the second working oil port 134 are respectively connected to the first chamber 152 and the second chamber 154 of the first oil cylinder 15. Specifically, the load-sensitive multi-way valve 13 also includes a control valve 135, a main valve 136, a first electro-proportional pressure reducing valve 137, and a second electro-proportional pressure reducing valve 138. The control valve 135 is connected between the first oil inlet 131 and the main valve 136 to control the connection or disconnection between the first oil inlet 131 and the main valve 136. The two control terminals of the main valve 136 are respectively connected to the first electro-proportional pressure reducing valve 137 and the second electro-proportional pressure reducing valve 138, so that the first electro-proportional pressure reducing valve 137 and the second electro-proportional pressure reducing valve 138 control the switching position, thereby connecting or disconnecting the output port of the control valve 135 from the first working oil port 133 or the second working oil port 134. The main valve 136 is also used to connect or disconnect the first oil inlet 131 from the first feedback port 130.

[0027] Specifically, the control valve 135 includes a first position and a second position, and includes a first port, a second port, and a third port. The first oil inlet 131 is connected to the first port, the second port is connected to the control terminal of the control valve 135, and the third port is connected to the main valve 136. In the first position, the first port and the second port are connected, and in the second position, the first port, the second port, and the third port are connected.

[0028] Specifically, the main valve 136 includes a fourth position, a fifth position, and a sixth position, and includes a fourth port, a fifth port, a sixth port, a seventh port, an eighth port, and a ninth port. The fourth port is connected to the third port of the control valve 135, the fifth port is connected to the first return oil port 132, the sixth port is connected to the first working oil port 133, and the seventh port is connected to the second working oil port 134. In the fourth position, the fifth port is connected to the sixth and seventh ports to achieve oil return; in the fifth position, the fourth port is connected to the seventh and eighth ports, and the fifth port is connected to the sixth and ninth ports to supply oil to the first cylinder 15 through the second working oil port 134; in the sixth position, the fourth port is connected to the sixth and eighth ports, and the fifth port is connected to the seventh and ninth ports to supply oil to the first cylinder 15 through the first working oil port 133. By controlling the current applied to the first electro-proportional pressure reducing valve 137 and the second electro-proportional pressure reducing valve 138, the opening degree of the main valve 136 in the fifth and sixth positions can be controlled, thereby controlling the flow rate output to the first oil cylinder 15 and realizing the gradual adjustment of the flow rate.

[0029] Specifically, the load-sensitive multi-way valve 13 also includes a first shuttle valve 141 and a second shuttle valve 143. The outlet of the first shuttle valve 141 is connected to the first feedback port 130, and the two inlets of the first shuttle valve 141 are respectively connected to the outlet of the second shuttle valve 143 and the first return port 132. The two inlets of the second shuttle valve 143 are respectively connected to the eighth port and the ninth port of the main valve 136.

[0030] In this embodiment, the control valve assembly 17 includes a second oil inlet 173, a second oil return port 174, and an oil output port 175. The second oil inlet 173 is connected to the pressure oil port 112 of the load-sensitive pump 11, the second oil return port 174 is connected to the oil tank for oil return, and the oil output port 175 is connected to the first directional valve 19 to supply oil to the second cylinder 21 through the first directional valve 19. The control valve assembly 17 also includes a two-way cartridge valve 177, a first throttling element 178, a second directional valve 179, a third directional valve 181, and a second throttling element 183. The second directional valve 179 is used to switch states to control the on / off state of the two-way cartridge valve 177. The on / off state of the two-way cartridge valve 177 is used to disconnect or connect the second oil inlet 173 and the oil output port 175. The third directional valve 181 is used to selectively connect the second oil return port 174 and the second feedback port 172, and the second feedback port 172 and the oil output port 175. The first throttling element 178 is used to generate a pressure differential, and the second throttling element 183 is used for buffering. By setting a two-way cartridge valve, regardless of the system flow rate, on / off control can be achieved through the second directional valve 179, resulting in a simple structure.

[0031] Specifically, the first port 1772 of the two-way cartridge valve 177 is connected to the second inlet port 173 of the control valve assembly 17, and the second port 1774 is connected to the outlet port 175. The second inlet port 173 is also connected to the two oil chambers of the two-way cartridge valve 177. The first throttling element 178 is connected between the two-way cartridge valve 177 and the second directional valve 179. Specifically, in this embodiment, the two-way cartridge valve 177 is a pressure-type two-way cartridge valve.

[0032] Specifically, the second directional valve 179 is a two-position two-way solenoid directional valve. One port of the second directional valve 179 is connected to the two-way cartridge valve 177, and the other port is connected to the second return port 174 and the third directional valve 181.

[0033] Specifically, the third directional valve 181 is a solenoid directional valve, including a fourth port, a fifth port, a sixth port, and a seventh port. The fourth port is connected to the oil passage between the two-way cartridge valve 177 and the output port 175 via a second throttling element 183. The fifth port is connected to the second return port 174, and the sixth port is connected to the second feedback port 172. The third directional valve 181 has a seventh position and an eighth position. In the seventh position, the fourth, fifth, sixth, and seventh ports are interconnected. In the eighth position, the fourth port is connected to the sixth port, and the fifth port is connected to the seventh port. In this embodiment, the third directional valve 181 can be a three-position four-way solenoid valve, but only two of them are used. Due to the "H"-type neutral position function of the third directional valve 181, regardless of the neutral position function adopted by the first directional valve 19, the control valve group 17 can be depressurized, allowing the load-sensitive pump 11 to return to a small-displacement standby state.

[0034] In this embodiment, the first reversing valve 19 is used to disconnect or connect the output port 175 and the second cylinder 21. The second cylinder 21 includes a third chamber 212 and a fourth chamber 214. The first reversing valve 19 can connect the output port 175 to the third chamber 212 or the fourth chamber 214, thereby driving the second cylinder 21 to extend or retract.

[0035] Specifically, the first reversing valve 19 is a solenoid valve, which includes an eighth port, a ninth port, a tenth port and an eleventh port. The eighth port is connected to the output port 175, the ninth port is connected to the oil tank for oil return, the tenth port is connected to the third chamber 212, and the eleventh port is connected to the fourth chamber 214. The first directional valve 19 includes a ninth position, a tenth position, and an eleventh position. In the ninth position, the third chamber 212 and the fourth chamber 214 are both connected to the oil tank, and the eighth oil port is disconnected from the ninth, tenth, and eleventh oil ports. This is the neutral position, and the output oil port 175 does not supply oil to the second oil cylinder 21. Both the third chamber 212 and the fourth chamber 214 return oil. In the tenth position, the eighth oil port is connected to the tenth oil port, and the ninth oil port is connected to the eleventh oil port. At this time, the output oil port 175 supplies oil to the third chamber 212, and the fourth chamber 214 returns oil. In the eleventh position, the eighth oil port is connected to the eleventh oil port, and the ninth oil port is connected to the tenth oil port. At this time, the output oil port 175 supplies oil to the fourth chamber 214, and the third chamber 212 returns oil.

[0036] The following describes the working principle of the load-sensitive hydraulic circuit in this embodiment.

[0037] Please refer to Figure 1 In standby mode, the load-sensitive multi-way valve 13 does not switch, and neither the second directional valve 179 nor the third directional valve 181 is energized. The third directional valve 181 is in the first position. After the load-sensitive valve 11 is activated, the pressure at the first feedback port 130 of the load-sensitive multi-way valve 13 is depressurized, and the pressure at the first feedback port 130 can be considered zero. The pressure oil at the second feedback port 172 passes through the neutral position of the third directional valve 181 and returns to the oil tank without pressure from the second return port 174, and the pressure at the second feedback port 172 can also be considered zero. Therefore, the pressure at the feedback port 114 is zero, and the load-sensitive pump 11 operates at a small displacement, with its output pressure always being the predetermined pressure (for example, when the set pressure of the constant pressure differential valve of the load-sensitive pump 11 is 1.4 MPa, the output pressure of the load-sensitive pump 11 is 1.4 MPa).

[0038] When the first cylinder 15 is working, the load-sensitive pump 11 supplies pressure oil to the load-sensitive multi-way valve 13 through the first oil inlet 131. The pressure oil passes through the control valve 135 and reaches the main valve 136. Under the control of the first electro-proportional pressure reducing valve 137 and the second electro-proportional pressure reducing valve 138, the main valve 136 switches to the fifth or sixth position, so that the pressure oil is supplied to the first cylinder 15 through the main valve 136, thereby controlling the first cylinder 15 to work. During this process, the first feedback port 130 is connected to the eighth or ninth port of the main valve 136 through the first shuttle valve 141 and the second shuttle valve 143, and then connected to the first oil inlet 131 through the valve core structure of the main valve 136, thereby forming a pressure of about 1.4 MPa. This pressure is applied to the feedback port 114 of the load-sensitive pump 11 through the selector valve 23. At this time, the pressure difference Δp1 of the load-sensitive multi-way valve 13 is less than 1.4 MPa, and the load-sensitive pump 11 will increase its output flow until the first cylinder 15 starts to drive the load. The pressure difference on both sides of the load-sensitive multi-way valve 13 is maintained at 1.4 MPa, and the load-sensitive pump 11 maintains this displacement. When the valve core of the load-sensitive multi-way valve 13 returns to the neutral position, the first cylinder 15 stops working, and the pressure at the feedback port 114 of the load-sensitive pump 11 is relieved through the neutral position of the load-sensitive multi-way valve 13.

[0039] Please refer to Figure 2 When the second cylinder 21 is working, the first reversing valve 19, the second reversing valve 179, and the third reversing valve 181 are all energized. The pressure oil output by the load-sensitive pump 11 is depressurized to the oil tank through the two-way cartridge valve 177, the first throttling element 178, and the second reversing valve 179. Due to the pressure difference created by the setting of the first throttling element 178, the pressure in the lower chamber of the two-way cartridge valve 177 is greater than the pressure in the upper chamber, causing it to open. The pressure oil output by the load-sensitive pump 11 passes through the second throttling element 183 and the third reversing valve 181 to reach the second feedback port 172, and then through the selector valve 23 to reach the feedback oil port 114 of the load-sensitive pump 11. At the same time, the pressure oil output by the load-sensitive pump 11 passes through the two-way cartridge valve 177 and then through the output oil port 175 and the first reversing valve 19 to enter the second cylinder 21. At this time, the pressure difference Δp1 of the load-sensitive multi-way valve 13 is less than 1.4 MPa. The load-sensitive pump 11 will increase its output flow rate until the second cylinder 21 starts to drive the load. The pressure difference on both sides of the load-sensitive multi-way valve 13 is maintained at 1.4 MPa, and the load-sensitive pump 11 maintains this displacement. When the first reversing valve 19, the second reversing valve 179, and the third reversing valve 181 are de-energized, the second cylinder 21 stops operating, and the oil in the second feedback port 172 passes through the neutral position of the second reversing valve 181 and is depressurized from the second return port 174 to the oil tank, so that the load-sensitive pump 11 is in standby mode with a small arrangement.

[0040] In the load-sensitive hydraulic circuit of this invention, oil supply to different cylinders is achieved through a load-sensitive multi-way valve and a control valve group, which can meet the different action requirements of the cylinders. For example, in the first embodiment, the load-sensitive multi-way valve can provide pressure oil with gradually adjustable flow rate, while the control valve group can provide pressure oil with large flow rate and rapid switching. At the same time, by achieving oil supply to different cylinders through the load-sensitive multi-way valve and the control valve group, the same load-sensitive pump can be shared, achieving the effect of single pump control of the load-sensitive circuit and simple hydraulic resistance circuit, reducing the number of drive sources and hydraulic pumps used, and reducing production costs.

[0041] Second Embodiment

[0042] Please refer to Figure 3 The structure of the load-sensitive hydraulic circuit in the second embodiment of the present invention is basically the same as that in the first embodiment, except that in the second embodiment, the third directional valve 181 is a two-way four-way solenoid valve. Other structures in this embodiment are the same as in the first embodiment and will not be described again here.

[0043] In the load-sensitive hydraulic circuit of this invention, oil supply to different cylinders is achieved through a load-sensitive multi-way valve and a control valve group, which can meet the different action requirements of the cylinders. For example, in the first embodiment, the load-sensitive multi-way valve can provide pressure oil with gradually adjustable flow rate, while the control valve group can provide pressure oil with large flow rate and rapid switching. At the same time, by achieving oil supply to different cylinders through the load-sensitive multi-way valve and the control valve group, the same load-sensitive pump can be shared, achieving the effect of single pump control of the load-sensitive circuit and simple hydraulic resistance circuit, reducing the number of drive sources and hydraulic pumps used, and reducing production costs.

[0044] Third Embodiment

[0045] Please refer to Figure 4 The structure of the load-sensitive hydraulic circuit in the third embodiment of the present invention is basically the same as that in the first embodiment, except that in the third embodiment, the two-way cartridge valve 177 is a directional two-way cartridge valve.

[0046] In the load-sensitive hydraulic circuit of this invention, oil supply to different cylinders is achieved through a load-sensitive multi-way valve and a control valve group, which can meet the different action requirements of the cylinders. For example, in the first embodiment, the load-sensitive multi-way valve can provide pressure oil with gradually adjustable flow rate, while the control valve group can provide pressure oil with large flow rate and rapid switching. At the same time, by achieving oil supply to different cylinders through the load-sensitive multi-way valve and the control valve group, the same load-sensitive pump can be shared, achieving the effect of single pump control of the load-sensitive circuit and simple hydraulic resistance circuit, reducing the number of drive sources and hydraulic pumps used, and reducing production costs.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A load-sensitive hydraulic circuit, characterized in that, The system includes a load-sensitive pump (11), a load-sensitive multi-way valve (13), a first cylinder (15), a control valve assembly (17), a first directional valve (19), a second cylinder (21), and a selector valve (23). The load-sensitive pump (11) includes a pressure port (112) and a feedback port (114). The load-sensitive multi-way valve (13) and the control valve assembly (17) are respectively connected to the pressure port (112) of the load-sensitive pump (11). The first cylinder (15) is connected to the load-sensitive multi-way valve (13). The first directional valve (19) is connected between the control valve assembly (17) and the second cylinder (21). (19) is used to disconnect or connect the control valve group (17) and the second cylinder (21). The load-sensitive pump (11) supplies oil to the first cylinder (15) through the load-sensitive multi-way valve (13), or supplies oil to the second cylinder (21) through the control valve group (17) and the first reversing valve (19). The load-sensitive multi-way valve (13) includes a first feedback port (130). The control valve group (17) includes a second feedback port (172). The selection valve (23) selectively connects the feedback port (114) to the first feedback port (130) or the feedback port (114) to the second feedback port (172).

2. The load-sensitive hydraulic circuit as described in claim 1, characterized in that, The load-sensitive multi-way valve (13) includes a first oil inlet (131), a first oil return port (132), a first working oil port (133), and a second working oil port (134). The first oil inlet (131) is connected to the pressure oil port (112) of the load-sensitive pump (11), the first oil return port (132) is connected to the oil tank, and the first working oil port (133) and the second working oil port (134) are respectively connected to the first chamber (152) and the second chamber (154) of the first cylinder (15).

3. The load-sensitive hydraulic circuit as described in claim 2, characterized in that, The load-sensitive multi-way valve (13) further includes a control valve (135), a main valve (136), a first electro-proportional pressure reducing valve (137), and a second electro-proportional pressure reducing valve (138). The control valve (135) is connected between the first oil inlet (131) and the main valve (136) to control the connection or disconnection between the first oil inlet (131) and the main valve (136). The two control terminals of the main valve (136) are respectively connected to the first electro-proportional pressure reducing valve (137) and the second electro-proportional pressure reducing valve (138) so that the first electro-proportional pressure reducing valve (137) and the second electro-proportional pressure reducing valve (138) control the switching position, thereby connecting or disconnecting the output port of the control valve (135) from the first working oil port (133) or the second working oil port (134). The main valve (136) is also used to connect or disconnect the first oil inlet (131) from the first feedback port (130).

4. The load-sensitive hydraulic circuit as described in claim 3, characterized in that, The control valve (135) includes a first position and a second position, and includes a first port, a second port and a third port. The first oil inlet (131) is connected to the first port, the second port is connected to the control end of the control valve (135), and the third port is connected to the main valve (136). In the first position, the first port and the second port are connected, and in the second position, the first port, the second port and the third port are connected. The main valve (136) includes a fourth position, a fifth position and a sixth position, and includes a fourth port, a fifth port, a sixth port, a seventh port, an eighth port and a ninth port. The fourth port is connected to the third port of the control valve (135), the fifth port is connected to the first oil return port (132), the sixth port is connected to the first working oil port (133), and the seventh port is connected to the second working oil port (136). 4) In the fourth position, the fifth port is connected to the sixth port and the seventh port; in the fifth position, the fourth port is connected to the seventh port and the eighth port; in the sixth position, the fourth port is connected to the sixth port and the eighth port; in the sixth position, the fourth port is connected to the sixth port and the eighth port; in the sixth position, the fifth port is connected to the seventh port and the ninth port. The load-sensitive multi-way valve (13) also includes a first shuttle valve (141) and a second shuttle valve (143). The outlet of the first shuttle valve (141) is connected to the first feedback port (130). The two inlets of the first shuttle valve (141) are respectively connected to the outlet of the second shuttle valve (143) and the first return port (132). The two inlets of the second shuttle valve (143) are respectively connected to the eighth port and the ninth port of the main valve (136).

5. The load-sensitive hydraulic circuit as described in claim 1, characterized in that, The control valve assembly (17) includes a second oil inlet (173), a second oil return port (174), and an oil outlet (175). The second oil inlet (173) is connected to the pressure port (112) of the load-sensitive pump (11), the second oil return port (174) is connected to the oil tank, and the oil outlet (175) is connected to the first directional valve (19) to supply oil to the second cylinder (21) through the first directional valve (19).

6. The load-sensitive hydraulic circuit as described in claim 5, characterized in that, The control valve group (17) further includes a two-way cartridge valve (177), a second directional valve (179), and a third directional valve (181). The second directional valve (179) is used to switch states to control the on / off state of the two-way cartridge valve (177). The on / off state of the two-way cartridge valve (177) is used to disconnect or connect the second oil inlet (173) and the oil outlet (175). The third directional valve (181) is used to selectively connect the second return oil outlet (174) and the second feedback outlet (172), and the second feedback outlet (172) and the oil outlet (175). The first directional valve (19), the second directional valve (179), and the third directional valve (181) are all electromagnetic directional valves.

7. The load-sensitive hydraulic circuit as described in claim 6, characterized in that, The control valve assembly (17) further includes a first throttling element (178). The first oil port (1772) of the two-way cartridge valve (177) is connected to the second oil inlet (173) of the control valve assembly (17), and the second oil port (1774) is connected to the output oil port (175). The second oil inlet (173) is also connected to the two oil chambers of the two-way cartridge valve (177) respectively. The first throttling element (178) is connected between the two-way cartridge valve (177) and the second directional valve (179).

8. The load-sensitive hydraulic circuit as described in claim 6, characterized in that, The second directional valve (179) is a two-position two-way solenoid directional valve. One port of the second directional valve (179) is connected to the two-way cartridge valve (177), and the other port is connected to the second return port (174) and the third directional valve (181).

9. The load-sensitive hydraulic circuit as described in claim 8, characterized in that, The third directional valve (181) includes a fourth port, a fifth port, a sixth port, and a seventh port. The fourth port is connected to the oil passage between the two-way cartridge valve (177) and the output port (175) through a second throttling element (183). The fifth port is connected to the second return port (174), and the sixth port is connected to the second feedback port (172). The third directional valve (181) includes a seventh position and an eighth position. In the seventh position, the fourth port, the fifth port, the sixth port, and the seventh port are interconnected. In the eighth position, the fourth port is connected to the sixth port, and the fifth port is connected to the seventh port.

10. The load-sensitive hydraulic circuit as described in claim 5, characterized in that, The second oil cylinder (21) includes a third chamber (212) and a fourth chamber (214); the first reversing valve (19) includes an eighth oil port, a ninth oil port, a tenth oil port and an eleventh oil port, the eighth oil port is connected to the output oil port (175), the ninth oil port is connected to the oil tank, the tenth oil port is connected to the third chamber (212), and the eleventh oil port is connected to the fourth chamber (214); the first reversing valve (19) includes a ninth position, a tenth position and an eleventh position. In the ninth position, the third chamber (212) and the fourth chamber (214) are both connected to the oil tank, and the eighth oil port is disconnected from the ninth oil port, the tenth oil port and the eleventh oil port; in the tenth position, the eighth oil port is connected to the tenth oil port, and the ninth oil port is connected to the eleventh oil port; in the eleventh position, the eighth oil port is connected to the eleventh oil port, and the ninth oil port is connected to the tenth oil port.

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