A split-flow control dual-pump hydraulic system

Abstract

The application discloses a kind of dual-pump hydraulic systems of flow distribution control, including sequentially connected hydraulic pump and the steering gear, tilting cylinder, hoist cylinder being communicated with hydraulic pump by multi-way valve, the multi-way valve includes steering priority valve, tilt valve, hoist valve, flow distribution valve;The oil outlet of the first oil pump is communicated with the steering priority valve, and the oil outlet valve port of the steering priority valve is respectively communicated with the steering gear, flow distribution oil circuit, the flow distribution oil circuit includes parallelly arranged oil supply oil circuit and oil return oil circuit, the oil supply oil circuit is communicated with the hoist valve, tilt valve, and flow distribution valve is provided on the oil return oil circuit, and the application is by setting two oil pumps respectively for steering and tilting, steering is realized by priority valve, front and rear tilting is realized by tilt valve, steering and tilting loop are independent of each other, combined operation is not interfered with each other, when combined operation, avoid the problems of steering lag and tilting deceleration, reduce system energy consumption simultaneously.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicle hydraulic system, and particularly relates to a split-flow control double-pump hydraulic system. BACKGROUND

[0002] The industrial vehicle hydraulic system generally includes basic functions such as steering, lifting and tilting. At present, the medium-tonnage vehicles generally adopt a large-displacement single pump to supply oil. The maximum flow of the system is designed according to the lifting demand. However, the flow demand of steering and tilting is far less than that of lifting. In actual work, the flow of steering and tilting is excessive, and energy is wasted seriously.

[0003] In the single-pump system, steering and tilting are in series connection. When they are operated jointly, there is mutual interference, and problems such as steering lag and tilting speed reduction occur, and the operation comfort is poor. At the same time, in order to meet the stringent emission requirements, the engine can only output large torque at high speed. At low speed, the torque is small, and the power response is slow. However, the industrial vehicle requires the engine to provide sufficient torque at low speed to drive the hydraulic system to complete the full-load operation. At this time, the engine is prone to stall, which causes the vehicle to be unable to work normally. SUMMARY

[0004] The present application aims to provide a split-flow control double-pump hydraulic system to solve the problems in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme.

[0006] A split-flow control double-pump hydraulic system comprises a hydraulic pump and a steering gear, a tilting cylinder and a lifting cylinder connected in sequence through a multi-way valve. The hydraulic pump comprises a first oil pump and a second oil pump. The multi-way valve comprises a steering priority valve, a tilting valve, a lifting valve and a split-flow valve.

[0007] The oil outlet end of the first oil pump is in communication with the steering priority valve. The oil outlet valve ports of the steering priority valve are in communication with the steering gear and a split-flow oil path respectively. The split-flow oil path comprises a supply oil path and a return oil path arranged in parallel. The supply oil path is in communication with the lifting valve and the tilting valve. The split-flow valve is arranged on the return oil path. The oil outlet end of the second oil pump is in communication with the lifting valve and the tilting valve.

[0008] As a further scheme of the present application, oil suction filters are arranged at the oil inlet ends of the first oil pump and the second oil pump, and the oil inlet ends of the first oil pump and the second oil pump are in communication with a hydraulic oil tank through the oil suction filters.

[0009] As a further scheme of the present application, the oil outlet end of the steering priority valve is in communication with a steering controller. The steering controller is connected with a steering cylinder. The steering gear is a closed-center load-sensing steering gear.

[0010] As a further scheme of the present application: the EF oil port of the steering priority valve is connected with a flow detection valve for detecting the flow of the EF oil port of the steering priority valve, the a oil port of the flow detection valve is communicated with the EF oil port of the steering priority valve, and the b oil port of the flow detection valve is communicated with the split and combined flow oil path.

[0011] As a further scheme of the present application: the split and combined flow valve spring cavity is provided with an unloading valve, the inlet of the unloading valve is connected with the split and combined flow valve spring cavity, the a oil port of the flow detection valve is connected with the left cavity of the unloading valve, the right cavity of the unloading valve is provided with a spring and connected with the b oil port of the flow detection valve, and the valve core of the unloading valve is in a normal open position.

[0012] As a further scheme of the present application: the oil supply pipeline is provided with a one-way valve at one end close to the flow detection valve.

[0013] As a further scheme of the present application: the lifting valve is communicated with the lifting oil cylinder, and the tilting valve is communicated with the tilting oil cylinder.

[0014] As a further scheme of the present application: the multi-way valve is provided with a return oil port T, one end of the return oil port T is connected with a hydraulic oil tank, and the other end of the return oil port T is communicated with the return oil ends of the steering priority valve, the return oil pipeline, the lifting valve and the tilting valve.

[0015] Compared with the prior art, the present application has the following beneficial effects:

[0016] 1. The present application is provided with two oil pumps for steering and tilting, realizes steering through a priority valve and realizes front and rear tilting through a tilting valve, the steering and tilting circuits are independent of each other, and the joint operation does not interfere with each other, the problems of steering lag and tilting deceleration are avoided during the joint operation, the system energy consumption is reduced, and when the lifting oil cylinder moves, the double-pump combined flow is realized to ensure the maximum lifting speed. When the engine is at low speed, the double-pump split flow is realized, one of the pumps is connected with the oil tank, and the system driving torque is reduced.

[0017] 2. Under the condition of high speed of the engine, the double-pump combined flow is supplied to the lifting oil cylinder during the lifting action to realize the maximum speed of the system; when the engine is at low speed, the steering oil supply pump is unloaded to the oil tank, and the other oil pump supplies the lifting and tilting to reduce the system driving torque and prevent the engine from stalling; during the tilting action, a small displacement oil pump always supplies oil, and the flow is all entered into the tilting oil cylinder without energy loss, the system is energy-saving, and the problem of the original single-pump system that the flow is too large, only a small part of the oil is entered into the tilting oil cylinder, and most of the oil is overflowed from the overflow valve to the oil tank, and the system is seriously heated is solved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1The hydraulic system principle schematic diagram for the embodiment is shown in the figure;

[0019] In the figure: 1-hydraulic oil tank, 2-oil suction filter, 3-first oil pump, 4-steering gear, 5-second oil pump, 6-multiplex valve, 61-steering priority valve, 62-flow detection valve, 63-flow dividing valve, 64-unloading valve, 65-lifting valve, 66-inclination valve, 7-inclination oil cylinder, 8-lifting oil cylinder, 9-steering oil cylinder. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0021] Please refer to Figure 1 In the embodiments of the present application, a double-pump hydraulic system for flow dividing and combining includes a hydraulic oil tank 1, an oil suction filter 2, a first oil pump 3 and a second oil pump 5, a multiplex valve 6, an inclination oil cylinder 7, a lifting oil cylinder 8, a steering oil cylinder 9, a steering gear 4, and the multiplex valve 6 includes a steering priority valve 61, a flow detection valve 62, a flow dividing valve 63, an unloading valve 64, a lifting valve 65, and an inclination valve 66.

[0022] The multiplex valve 6 is provided with an oil port P1, the oil port P1 is communicated with an oil outlet end of the first oil pump 3, the oil liquid is supplied to the steering gear 4 through the steering priority valve 61 as needed, the excess oil liquid flows to an a oil port of the flow detection valve 62 through an EF oil port, the flow detection valve 62 is used for detecting the flow of the EF oil port, a b oil port of the flow detection valve 62 is connected with a supply oil pipeline and a return oil pipeline, the supply oil pipeline is provided with a one-way valve, the one-way valve is communicated with the lifting valve 65 and the inclination valve 66 after the one-way valve, the hydraulic oil can only flow from the flow detection valve 62 to the lifting valve 65 and the inclination valve 66 through the one-way valve, the return oil pipeline is provided with the flow dividing valve 63, a spring cavity of the flow dividing valve 63 is provided with the unloading valve 64, an oil inlet of the unloading valve 64 is connected with the spring cavity of the flow dividing valve 63, the a oil port of the flow detection valve 62 is connected with a left cavity of the unloading valve 64, a right cavity of the unloading valve 64 is provided with a spring and connected with the b oil port of the flow detection valve 62, a valve core of the unloading valve 64 is in a normal open position, the multiplex valve 6 is provided with an oil port P2, the oil port P2 is connected with the second oil pump 5, and the oil liquid is supplied to the lifting valve 65 and the inclination valve 66, the multiplex valve 6 is provided with a return oil port T, one end of the return oil port T is connected with the hydraulic oil tank 1, and the other end of the return oil port T is communicated with the steering priority valve 61, the return oil pipeline, the lifting valve 65 and the inclination valve 66.

[0023] When the vehicle is running, the first oil pump 3 outlet oil first passes through the multi-way valve 6 oil port P1 into the priority valve 61, due to the CF oil port of the steering gear 4 is closed, under the action of the differential pressure △P1 on the steering priority valve 61, the valve core of the steering priority valve 61 moves upward, the P1 port oil flows to the flow detection valve 62 through the EF port, and finally returns to the hydraulic oil tank 1 through the lifting valve 65 and the tilt valve 66. The second oil pump 5 outlet oil directly returns to the hydraulic oil tank 1 through the lifting valve 65 and the tilt valve 66.

[0024] When the vehicle needs to steer, the P oil port of the steering gear 4 is connected with the L or R port of the steering cylinder 9, and the load pressure of the steering cylinder 9 is fed back to the spring cavity of the steering priority valve 61 through the Ls oil port of the multi-way valve 6, pushing the valve core of the steering priority valve 61 to move downward, the steering priority valve 61 supplies oil to the steering gear 4, and the vehicle steering is completed.

[0025] When the lifting is operated at low speed of the engine, the oil flows from the a oil port to the b oil port of the flow detection valve 62, and the differential pressure through the flow detection valve 62 is zero due to the small flow, the pressures of the a oil port and the b oil port are equal, the unloading valve 64 is always in the always-on position under the action of the spring force, the feedback pressure of the lifting cylinder 8 is connected with the T oil port of the multi-way valve 6, and under the action of the high pressure of the b port, the valve core of the split-flow valve 63 moves rightward, connecting the b port with the T oil port of the multi-way valve 6. At this time, the first oil pump 3 outlet oil returns to the hydraulic oil tank 1 directly from the split-flow valve 63 through the EF oil port of the steering priority valve 61, so that the first oil pump 3 only works at low pressure of steering, and the second oil pump 5 outlet oil supplies lifting alone. At low speed and low torque of the engine, the second oil pump 5 works at large torque, the first oil pump 3 works at low torque, the driving torque of the hydraulic system is reduced, and the engine is prevented from stalling at low speed.

[0026] When the lifting is operated at high speed of the engine, the oil flows from the a oil port to the b oil port of the flow detection valve 62, and the differential pressure △P is formed between the a port and the b port, at this time, the pressure of the a oil port is introduced to the left cavity of the unloading valve 64, and the pressure of the b oil port is introduced to the spring cavity of the unloading valve 64. Under the action of the differential pressure △P, the valve core moves rightward to compress the spring, the feedback pressure of the lifting cylinder 8 is disconnected with the T oil port, and the feedback pressure is connected with the spring cavity of the split-flow valve 63 at the same time, pushing the valve core of the split-flow valve 63 to move leftward, disconnecting the P1 port with the hydraulic oil tank 1. At this time, the oil of the P1 and P2 oil ports of the multi-way valve 6 is forced to flow together, realizing the maximum flow output of the lifting valve 65, and meeting the requirement of the maximum lifting speed of the vehicle.

[0027] When the tilt is operated, the second oil pump 5 outlet oil passes through the tilt valve 66 to the tilt cylinder 7 through the lifting valve 65, the split-flow valve 63 spring cavity is connected with the T oil port of the multi-way valve 6 through the c port of the lifting valve 65, under the action of the high pressure of the b oil port, the spool of the split-flow valve 63 moves to the right, the b oil port is connected with the T oil port of the multi-way valve 6, at this time, the first oil pump 3 oil passes through the steering priority valve 61 and then directly returns to the hydraulic oil tank 1 through the split-flow valve 63, the second oil pump 5 is used for tilting alone, the first oil pump 3 is unloaded and returned to the hydraulic oil tank, the original single pump system is a large displacement oil pump for tilting, and the excess oil is overflowed back to the tank through the safety valve, the system is seriously heated, and the split-flow system of the embodiment can reduce the system energy consumption.

[0028] When the steering and tilt are combined, the first oil pump 3 outlet oil flows to the steering gear 4 through the steering priority valve 61, the excess oil directly returns to the hydraulic oil tank 1 through the split-flow valve 63, and the second oil pump 5 outlet oil flows to the tilt cylinder 7 through the tilt valve 66, so that the steering and tilt are independently supplied by two independent oil pumps, and the problems of steering blockage and tilt speed reduction in the single pump system during combined operation of the steering and tilt are avoided.

[0029] It is apparent for those skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, and the present application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and range of equivalents of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.

[0030] In addition, it should be understood that although the present specification is described in terms of embodiments, not every embodiment contains only one independent technical solution, and the description of the specification is only for the sake of clarity, and those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be combined appropriately to form other embodiments that those skilled in the art can understand.

Claims

1. A dual-pump hydraulic system with flow splitting and merging control, comprising a hydraulic pump connected in sequence and a steering gear (4), a tilting cylinder (7), and a lifting cylinder (8) connected to the hydraulic pump via a multi-way valve (6), characterized in that, The hydraulic pump includes a first oil pump (3) and a second oil pump (5), and the multi-way valve (6) includes a steering priority valve (61), a tilt valve (66), a lifting valve (65), and a flow divider / merge valve (63). The oil outlet of the first oil pump (3) is connected to the steering priority valve (61), and the oil outlet of the steering priority valve (61) is connected to the steering gear (4) and the merging and splitting oil circuit respectively. The merging and splitting oil circuit includes a supply oil circuit and a return oil circuit arranged in parallel. The supply oil circuit is connected to the lifting valve (65) and the tilt valve (66). The return oil circuit is provided with a merging and splitting valve (63). The oil outlet of the second oil pump (5) is connected to the lifting valve (65) and the tilt valve (66). The steering priority valve (61) has an EF port connected to a flow detection valve (62) for detecting the flow rate at the EF port of the steering priority valve (61). The a port of the flow detection valve (62) is connected to the EF port of the steering priority valve (61), and the b port of the flow detection valve (62) is connected to the merging and splitting flow circuit. The merging and splitting flow valve (63) has a relief valve (64) in its spring cavity. The inlet of the relief valve (64) is connected to the spring cavity of the merging and splitting flow valve (63). The flow detection valve (62) has port a connected to the left chamber of the unloading valve (64). The right chamber of the unloading valve (64) is provided with a spring and is connected to port b of the flow detection valve (62). The valve core of the unloading valve (64) is in the normally open position. The multi-way valve (6) is provided with return port T. One end of return port T is connected to the hydraulic oil tank (1), and the other end of return port T is connected to the return end of the steering priority valve (61), the return pipeline, the lifting valve (65), and the tilt valve (66).

2. The dual-pump hydraulic system with flow splitting and merging control according to claim 1, characterized in that, Both the first oil pump (3) and the second oil pump (5) are equipped with oil suction filters (2) at their oil inlet ends, and both the first oil pump (3) and the second oil pump (5) are connected to the hydraulic oil tank (1) through the oil suction filters (2).

3. The dual-pump hydraulic system with flow splitting and merging control according to claim 1, characterized in that, The oil outlet of the steering priority valve (61) is connected to the steering gear (4), and the steering gear (4) is connected to the steering cylinder (9). The steering gear (4) is a closed-center load-sensing steering gear.

4. The dual-pump hydraulic system with flow splitting and merging control according to claim 1, characterized in that, A one-way valve is provided at one end of the oil supply pipeline near the flow detection valve (62).

5. A dual-pump hydraulic system with flow splitting and merging control according to claim 1, characterized in that, The lifting valve (65) is connected to the lifting cylinder (8), and the tilting valve (66) is connected to the tilting cylinder (7).

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