Loader hydraulic system and loader

Abstract

The invention discloses a loader hydraulic system and a loader. The system comprises a steering pump, a working pump and a confluence switching valve used for conducting flow distribution on the output flow of the steering pump and the output flow of the working pump. An outlet of the steering pump is connected with an inlet of the priority valve, an outlet I of the priority valve is connected with an inlet of the steering gear, an outlet II is connected with an inlet I of the confluence switching valve, and a working port of the steering gear is connected with the steering oil cylinder; an outlet of the working pump is connected with a second inlet of the confluence switching valve, an outlet of the confluence switching valve is connected with an inlet of the multi-way valve, and a working opening of the multi-way valve is connected with the working oil cylinder. The requirement of a power system for the total flow can be lowered, pressure loss caused by different loads in the composite action process can be reduced, and energy saving is achieved.

Description

Technical Field

[0001] This invention belongs to the field of loader technology, specifically relating to a loader hydraulic system and a loader. Background Technology

[0002] In existing technologies, there are two main technical approaches for load-sensitive hydraulic systems in loaders. One approach uses a split-flow system, where the steering pump supplies steering flow and the working pump supplies working flow, avoiding combined operating conditions and resulting in lower energy consumption. However, to ensure the working flow requirements, the working pump has a large displacement and high cost, placing higher demands on the overall power system. The other approach uses a combined-flow system, where the steering pump supplies both working and steering flow, and the working pump supplies working flow separately. This greatly reduces the total system flow and lowers the power system requirements, but the presence of combined steering and working conditions results in more energy loss. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a loader hydraulic system and a loader that can reduce the power system's requirements for total flow rate and reduce pressure loss due to different loads during complex operations, thereby achieving energy savings.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, a hydraulic system for a loader is provided, comprising: a steering pump, a working pump, and a flow-distributing valve for distributing the output flow of the steering pump and the working pump; the outlet of the steering pump is connected to the inlet of a priority valve, the outlet one of the priority valve is connected to the inlet of the steering gear, the outlet two of the priority valve is connected to the inlet one of the flow-distributing valve, and the working port of the steering gear is connected to a steering cylinder; the outlet of the working pump is connected to the inlet two of the flow-distributing valve, the outlet of the flow-distributing valve is connected to the inlet of a multi-way valve, and the working port of the multi-way valve is connected to the working cylinder.

[0005] Furthermore, the control port of the steering pump is connected to the second control port of the priority valve; the control port of the working pump is connected to the second control port of the merging switching valve and the first control port of the multi-way valve; the third control port of the priority valve is connected to the first control port of the merging switching valve, and the first control port of the priority valve is connected to the control port of the steering gear; the inlet of the pilot oil source valve is connected to the second control port of the multi-way valve, and the outlet of the pilot oil source valve is connected to the third control port of the multi-way valve; the return ports of the priority valve, the pilot oil source valve, and the merging switching valve are connected to the oil tank.

[0006] Furthermore, the merging switching valve is equipped with a return spring, and the return spring control pressure p1 satisfies the following conditions: p1 < p3; Where p3 is the control pressure of the working pump.

[0007] Furthermore, the steering pump control pressure p2 satisfies the following conditions: p4 < p2; Where p4 is the spring control pressure of the priority valve.

[0008] Furthermore, the working pump control pressure p3 satisfies the following conditions: ; Where n is the engine speed, V1 is the steering pump displacement, V2 is the working pump displacement, and C d ρ is the fluid flow coefficient, A is the maximum area of ​​the boom lifting valve core, and ρ is the hydraulic oil density.

[0009] Furthermore, when neither the steering cylinder nor the working cylinder is in motion, the hydraulic oil output by the working pump acts on the non-spring chamber of the merging switching valve, driving the merging switching valve to the diversion position. The inlet of the merging switching valve is not connected to the outlet, and the control port of the merging switching valve is connected to the return port. The pressure at the control port of the steering pump is relieved through the control port of the priority valve, the control port of the priority valve, the control port of the merging switching valve, and the return port of the merging switching valve. At this time, the steering pump is not affected by the working pump.

[0010] Furthermore, when the steering cylinder is not moving and the working cylinder is moving, as the multi-way valve gradually opens, the displacement of the working pump gradually increases. Since the working pump control pressure p3 is greater than the control pressure p1 of the merging switching valve reset spring, the merging switching valve is in the diversion position. At this time, the steering pump is in the low-pressure minimum displacement state. When the multi-way valve gradually opens until the working pump reaches its maximum displacement, it is in the underflow state. The pressure difference between the working pump outlet pressure and the working pump control port pressure gradually decreases. When the pressure difference is less than p1, the merging switching valve switches to the merging position. At this time, the control port one and control port two of the merging switching valve are connected, and the displacement of the steering pump begins to gradually increase. When the working system reaches the system pressure, the pressure difference between the working pump outlet pressure and the working pump control port pressure is equal to p3. The working pump changes to minimum displacement operation. Since p3 > p1, the merging switching valve switches to the diversion position again, and the steering pump control port is depressurized. At this time, the steering pump is in the low-pressure minimum displacement state.

[0011] Furthermore, when the steering cylinder and the working cylinder work simultaneously, as the multi-way valve gradually opens, the working pump displacement gradually increases. Since the working pump control pressure p3 > p1, the merging switching valve is still in the diversion position under the flow saturation state. At this time, the steering pump supplies oil to the steering system alone and is not affected by the workload. When the multi-way valve gradually opens until the working pump reaches its maximum displacement, it is in a low flow state. The pressure difference between the working pump outlet and the working pump control port gradually decreases. When the pressure difference is less than p1, the merging switching valve is in the merging position. At this time, the control port one and control port two of the merging switching valve are connected, and the steering pump supplies oil to both the steering system and the working system at the same time.

[0012] In a second aspect, a loader is provided, the loader being equipped with the loader hydraulic system described in the first aspect.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention sets up a merging switching valve for distributing the output flow of the steering pump and the working pump; and connects the outlet of the steering pump to the inlet of the priority valve, the outlet one of the priority valve to the inlet of the steering gear, the outlet two of the priority valve to the inlet one of the merging switching valve, and the working port of the steering gear to the steering cylinder; the outlet of the working pump is connected to the inlet two of the merging switching valve, the outlet of the merging switching valve is connected to the inlet of the multi-way valve, and the working port of the multi-way valve is connected to the working cylinder. This can reduce the power system's requirements for total flow and reduce pressure loss caused by different loads during compound actions, thereby achieving energy saving. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of a loader hydraulic system provided in an embodiment of the present invention; In the diagram: 1. Steering pump; 2. Working pump; 3. Pilot oil supply valve; 4. Priority valve; 5. Steering gear; 6. Merging switching valve; 7. Multi-way valve; 8. Oil tank. Detailed Implementation

[0015] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0016] Example 1 like Figure 1 As shown, a loader hydraulic system includes: a steering pump 1, a working pump 2, a pilot oil source valve 3, a priority valve 4, a steering gear 5, a flow switching valve 6, a multi-way valve 7, and an oil tank 8; the flow switching valve 6 is used to distribute the output flow of the steering pump 1 and the working pump 2; the multi-way valve 7 is an electrically controlled multi-way valve.

[0017] The outlet of steering pump 1 is connected to port P (inlet of priority valve) of priority valve 4. Port CF (outlet one of priority valve) of priority valve 4 is connected to port P (inlet of steering gear) of steering gear 5. Port EF (outlet two of priority valve) is connected to port P1 (inlet one of merging switching valve) of merging switching valve 6. The working port of steering gear 5 is connected to steering cylinder. The outlet of working pump 2 is connected to port P2 (inlet two of merging switching valve) of merging switching valve 6. Port A (outlet of merging switching valve) of merging switching valve 6 is connected to port P (inlet of multi-way valve) of multi-way valve 7. The working port of multi-way valve 7 is connected to working cylinder.

[0018] The X port (control port of the steering pump 1) of steering pump 1 is connected to the LS2 port (control port 2 of the priority valve) of priority valve 4.

[0019] The X port (control port of the working pump 2) is connected to the LS2 port (control port 2 of the merging switching valve 6) and the LS port (control port 1 of the multi-way valve 7).

[0020] The LS3 port (control port three of the priority valve) of the priority valve 4 is connected to the LS1 port (control port one of the merging switching valve) of the merging switching valve 6, and the LS1 port (control port one of the priority valve) of the priority valve 4 is connected to the LS port (control port of the steering gear) of the steering gear 5.

[0021] The P port (inlet of the pilot oil source valve) of the pilot oil source valve 3 is connected to the Mp port (control port two of the multi-way valve) of the multi-way valve 7, and the A port (outlet of the pilot oil source valve) of the pilot oil source valve 3 is connected to the Pst port (control port three of the multi-way valve) of the multi-way valve 7. The L port of priority valve 4 (the return port of priority valve), the T port of pilot oil source valve 3 (the return port of pilot oil source valve), and the T port of confluence switching valve 6 (the return port of confluence switching valve) are connected to oil tank 8.

[0022] The merging switching valve is equipped with a return spring, and the return spring control pressure p1 meets the following conditions: p1 < p3; Where p3 is the control pressure of the working pump, MPa; p1 is the control pressure of the resetting spring of the confluence switching valve, MPa.

[0023] When the entire machine is not in operation (neither the steering cylinder nor the working cylinder is in operation), the outlet pressure p3 of the working pump 2 is greater than p1. This pressure value acts on the non-spring chamber of the confluence switching valve 6. The confluence switching valve 6 is in the upper position (diverting position). The P1 port of the confluence switching valve 6 is disconnected from the A port of the confluence switching valve 6, and the LS1 port of the confluence switching valve 6 is connected to the T port of the confluence switching valve 6. The X port pressure of the steering pump 1 can be relieved through the LS1 port of the confluence switching valve 6 (the hydraulic oil of the X port of the steering pump 1 flows sequentially through the LS2 port of the priority valve 4, the LS3 port of the priority valve 4, the LS1 port of the confluence switching valve 6, and the T port of the confluence switching valve 6). At this time, the steering pump 1 is not affected by the working system.

[0024] When the machine is only working (steering cylinder not moving, working cylinder moving), as the multi-way valve gradually opens, the displacement of working pump 2 gradually increases. Since the control pressure of working pump 2, p3 > p1, the flow switching valve 6 is still in the upper position under the flow saturation state. At this time, steering pump 1 is still in the low pressure minimum displacement state. When the multi-way valve gradually opens until working pump 2 reaches the maximum displacement, it is in the underflow state. The pressure difference between the outlet of working pump 2 and the X port of working pump 2 gradually decreases. When it is less than p1, the flow switching valve 6 is in the lower position (flow merging position). At this time, the LS1 port and LS2 port of the flow switching valve 6 are connected, and the displacement of steering pump 1 begins to gradually increase.

[0025] When the working system reaches the system pressure, the pressure difference between the pump port of working pump 2 and the X port of working pump 2 is equal to p3. Working pump 2 becomes the minimum displacement. Since p3 > p1, the flow switching valve 6 switches to the upper position again, and the X port of steering pump 1 is depressurized. At this time, steering pump 1 is in the low pressure minimum displacement position.

[0026] When the entire machine is simultaneously steering and working (steering cylinder and working cylinder are working at the same time), as the multi-way valve port gradually opens, the displacement of working pump 2 gradually increases. Since the control pressure of working pump p3 > p1, the flow switching valve 6 is still in the upper position under the state of flow saturation. At this time, steering pump 1 supplies oil to the steering system alone and is not affected by the working load. When the multi-way valve port gradually opens until the working pump reaches its maximum displacement, it is in the state of underflow. The pressure difference between the outlet of working pump 2 and the X port of working pump 2 gradually decreases. When it is less than p1, the flow switching valve 6 is in the lower position. At this time, the LS1 port and LS2 port of the flow switching valve 6 are connected. At this time, steering pump 1 supplies oil to both the steering system and the working system at the same time. Due to the load difference, the priority valve 4 performs pressure compensation, resulting in a certain pressure loss.

[0027] When the boom lifting valve port reaches its maximum area, in order to ensure that the working pump 2 can reach its maximum displacement, the control pressure p3 of the working pump 2 must satisfy the following relationship: ; Where p3 is the working pump control pressure, MPa; n is the engine speed, r / min; V1 is the steering pump displacement, mL / r; V2 is the working pump displacement, mL / r; C d Where A is the fluid flow coefficient, A is the maximum area of ​​the boom lifting valve core, and ρ is the hydraulic oil density (kg / m³). 3 .

[0028] When the machine is only turning (steering cylinder is activated, working cylinder is not activated), steering pump 1 needs to overcome the spring control pressure p4 of priority valve 4. Therefore, in order to further reduce the pressure loss of priority valve 4, the control pressure p4 of priority valve 4 must satisfy the following relationship: p4 < p2; Where p4 is the priority valve spring control pressure, MPa; p2 is the steering pump control pressure, MPa.

[0029] At this time, when the merging switching valve 6 is in the lower position and the steering pump 1 supplies oil to the working system, the pump port pressure is greater than p4, so the priority valve 4 will have the lowest pressure loss.

[0030] This invention pertains to load-sensitive hydraulic systems. When a loader is simultaneously steering and working, the flow distribution of the pump is controlled by a confluence switching valve to reduce pressure loss caused by different loads during combined actions, thereby achieving energy saving.

[0031] Example 2 Based on the loader hydraulic system described in Embodiment 1, this embodiment provides a loader equipped with the loader hydraulic system described in Embodiment 1.

[0032] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydraulic system for a loader, characterized in that, include: Steering pump (1), working pump (2), and a flow-distributing valve (6) for distributing the output flow of steering pump (1) and working pump (2); the outlet of steering pump (1) is connected to the inlet of priority valve (4), the outlet of priority valve (4) is connected to the inlet of steering gear (5), the outlet of priority valve (4) is connected to the inlet of flow-distributing valve (6), and the working port of steering gear (5) is connected to steering cylinder; the outlet of working pump (2) is connected to the inlet of flow-distributing valve (6), the outlet of flow-distributing valve (6) is connected to the inlet of multi-way valve (7), and the working port of multi-way valve (7) is connected to working cylinder.

2. The loader hydraulic system according to claim 1, characterized in that, The control port of the steering pump (1) is connected to the control port of the priority valve (4); The control port of the working pump (2) is connected to the control port 2 of the confluence switching valve (6) and the control port 1 of the multi-way valve (7); The control port 3 of the priority valve (4) is connected to the control port 1 of the merging switching valve (6), and the control port 1 of the priority valve (4) is connected to the control port of the steering gear (5); The inlet of the pilot oil source valve (3) is connected to the control port 2 of the multi-way valve (7), and the outlet of the pilot oil source valve (3) is connected to the control port 3 of the multi-way valve (7). The return port of the priority valve (4), the return port of the pilot oil source valve (3), and the return port of the confluence switching valve (6) are connected to the oil tank (8).

3. The loader hydraulic system according to claim 2, characterized in that, The merging switching valve is equipped with a return spring, and the return spring control pressure p1 meets the following conditions: p1 < p3; Where p3 is the control pressure of the working pump.

4. The loader hydraulic system according to claim 2, characterized in that, The steering pump control pressure p2 must meet the following conditions: p4 < p2; Where p4 is the spring control pressure of the priority valve.

5. The loader hydraulic system according to claim 2, characterized in that, The working pump control pressure p3 must meet the following conditions: ； Where n is the engine speed, V1 is the steering pump displacement, V2 is the working pump displacement, and C d ρ is the fluid flow coefficient, A is the maximum area of ​​the boom lifting valve core, and ρ is the hydraulic oil density.

6. The loader hydraulic system according to claim 2, characterized in that, When neither the steering cylinder nor the working cylinder moves, the hydraulic oil output by the working pump (2) acts on the non-spring chamber of the merging switching valve (6), driving the merging switching valve (6) to the diversion position. The inlet of the merging switching valve (6) is not connected to the outlet of the merging switching valve (6), and the control port of the merging switching valve (6) is connected to the return port of the merging switching valve (6). The pressure of the control port of the steering pump (1) is depressurized through the control port of the priority valve (4), the control port of the priority valve (4), the control port of the merging switching valve (6), and the return port of the merging switching valve (6). At this time, the steering pump (1) is not affected by the working pump (2).

7. The loader hydraulic system according to claim 6, characterized in that, When the steering cylinder is not moving and the working cylinder is moving, as the valve port of the multi-way valve (7) gradually opens, the displacement of the working pump (2) gradually increases. Since the control pressure p3 of the working pump is greater than the control pressure p1 of the resetting spring of the confluence switching valve, the confluence switching valve (6) is in the diversion position. At this time, the steering pump (1) is in the low-pressure minimum displacement state. When the valve port of the multi-way valve (7) gradually opens until the working pump (2) reaches the maximum displacement, it is in the underflow state. The pressure difference between the outlet pressure of the working pump and the control port pressure of the working pump gradually decreases. When the pressure difference is less than p1, the merging switching valve (6) switches to the merging position. At this time, the control port one and control port two of the merging switching valve (6) are connected, and the displacement of the steering pump (1) begins to gradually increase. When the working system reaches the system pressure, the pressure difference between the working pump outlet pressure and the working pump control port pressure is equal to p3. The working pump (2) changes to minimum displacement operation. Since p3 > p1, the merging switching valve (6) switches to the diversion position again, and the control port of the steering pump (1) is depressurized. At this time, the steering pump (1) is in low pressure minimum displacement.

8. The loader hydraulic system according to claim 6, characterized in that, When the steering cylinder and the working cylinder work at the same time, as the multi-way valve port gradually opens, the displacement of the working pump (2) gradually increases. Since the control pressure p3 of the working pump (2) is greater than p1, the merging switching valve (6) is still in the diversion position under the flow saturation state. At this time, the steering pump (1) supplies oil to the steering system alone and is not affected by the working load. When the multi-way valve port gradually opens until the working pump (2) reaches the maximum displacement, it is in the underflow state. The pressure difference between the outlet of the working pump (2) and the control port of the working pump (2) gradually decreases. When the pressure difference is less than p1, the merging switching valve (6) is in the merging position. At this time, the control port one and control port two of the merging switching valve (6) are connected, and the steering pump (1) supplies oil to the steering system and the working system at the same time.

9. A loader, characterized in that, The loader is equipped with the loader hydraulic system as described in any one of claims 1 to 8.

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