A walking split-flow system of a wheel type hydraulic excavator

Abstract

A walking split-flow system of a wheel type hydraulic excavator comprises a walking directional valve and a walking motor; a hydraulic oil tank is connected to a hydraulic pump through an oil pipe, an outlet end of the hydraulic pump is connected to the walking directional valve through an oil inlet pipe, and the walking directional valve is connected to the hydraulic oil tank through an oil return pipe; the walking motor is connected to the walking directional valve through a connecting pipe; the system further comprises a walking split-flow valve; when the walking directional valve is switched to a forward position and the walking split-flow valve is in an open state, pressure oil pumped from the hydraulic pump is supplied to the walking motor through two oil paths of the walking directional valve and the walking split-flow valve; and oil return of the walking motor flows back to the hydraulic oil tank through the two oil paths of the walking directional valve and the walking split-flow valve. By increasing the walking split-flow valve and the walking directional valve in the main control valve in parallel use, the hydraulic oil flow capacity of the walking system is increased, the pressure loss of the hydraulic oil in the main control valve is reduced, the vehicle driving speed reaches the expected target, and the energy loss is reduced to an acceptable range.

Description

Technical Field

[0001] This invention relates to the field of excavator technology, and more particularly to a travel diversion system for a wheeled hydraulic excavator. Background Technology

[0002] Currently, the main control valve used in the hydraulic system of wheeled hydraulic excavators can only be equipped with a maximum machine weight of about 20t and a maximum travel speed of about 40km / h. The maximum hydraulic oil flow capacity of the control travel linkage is about 200L. If it is necessary to improve the travel speed and other performance, it is greatly limited.

[0003] Increasing the maximum driving speed necessitates increasing the flow rate. However, the main control valve has limited flow capacity, and increasing the system flow rate will inevitably increase energy loss at the main control valve, limiting acceleration, increasing heat generation in the hydraulic system, and reducing its efficiency during driving. Once the flow rate reaches a certain level, even increasing engine power will not further increase the driving speed. Summary of the Invention

[0004] The main objective of this invention is to propose a travel diversion system for wheeled hydraulic excavators, which aims to solve the aforementioned technical problems.

[0005] To achieve the above objectives, this invention proposes a travel diversion system for a wheeled hydraulic excavator, comprising a travel directional valve and a travel motor; a hydraulic oil tank is connected to a hydraulic pump via an oil pipe, and the outlet end of the hydraulic pump is connected to the travel directional valve via an oil inlet pipe; the travel directional valve is connected to the hydraulic oil tank via a return oil pipe; the travel motor and the travel directional valve are connected via a connecting pipe; the system also includes a travel diversion valve connected to the oil inlet pipe, the oil return pipe, and the connecting pipe; when the travel directional valve is switched to the forward position and the travel diversion valve is in the open state, the pressurized oil pumped from the hydraulic pump supplies oil to the travel motor through both the travel directional valve and the travel diversion valve; the return oil from the travel motor flows back to the hydraulic oil tank through both the travel directional valve and the travel diversion valve.

[0006] Preferably, the travel directional valve is a Y-type three-position six-way hydraulic directional valve; the travel diverter valve is a hydraulic two-position four-way spool valve; the valve stems of the travel directional valve and the travel diverter valve are controlled by the same forward pilot oil circuit.

[0007] Preferably, the travel directional valve has A, B, E, and F ports. When the travel directional valve is in the neutral position, ports A and B are both connected to port F; when in the forward position, ports E and B are connected, and ports A and F are connected; when in the reverse position, ports E and A are connected, and ports F and B are connected. The travel diversion valve has G, H, M, and N ports. When the travel diversion valve is in the closed state, ports G and H are disconnected, and ports M and N are disconnected; when in the open state, ports G and H are connected, and ports M and N are connected. The connecting pipe includes a first oil pipe and a second... Oil pipes; the travel motor has a first interface and a second interface; the outlet end of the inlet pipe is connected to port E of the travel directional valve; one end of the first oil pipe is connected to port B of the travel directional valve, and the other end is connected to the first interface of the travel motor; one end of the second oil pipe is connected to port A of the travel directional valve, and the other end is connected to the second interface of the travel motor; port G of the travel diverter valve is connected to the inlet pipe through a first branch pipe; port H is connected to the first oil pipe through a second branch pipe; port M is connected to the second oil pipe through a third branch pipe; and port D is connected to the return oil pipe through a fourth branch pipe.

[0008] Preferably, a first one-way valve is provided on the first branch pipe.

[0009] Preferably, a safety valve is connected between the oil inlet pipe and the oil return pipe. The safety valve is a pilot-operated relief valve. A second check valve is provided on the inlet pipe of the safety valve.

[0010] Preferably, the travel directional valve also has C and D ports; when the travel directional valve is in the neutral position, ports C and D are connected; when it is in the forward or reverse position, ports C and D are disconnected; a fifth branch pipe is provided on the oil inlet pipe and connected to port C, and a sixth branch pipe is connected to port D. The outlet end of the sixth branch pipe is connected to the oil return pipe, and a first throttle valve is provided on the sixth branch pipe; an overflow valve is connected in parallel at the first throttle valve, and the pressure of the overflow valve is 31.4 bar.

[0011] Preferably, a third check valve is provided on the oil inlet pipe; the third check valve is located between the connection point of the fifth branch pipe and the oil inlet pipe and the E port of the travel reversing valve.

[0012] Preferably, a second throttle valve is provided inside the travel reversing valve. When the travel reversing valve is in the neutral position, port A is connected to port B and then connected to port F through the second throttle valve.

[0013] Preferably, a motor safety valve is connected between the first and second interfaces of the travel motor. This motor safety valve consists of two relief valves connected in opposite directions. The outlets of the two relief valves converge and are connected to the variable hydraulic motor inside the travel motor. The variable hydraulic motor is connected to the hydraulic oil tank through a drain pipe. A check valve is connected in parallel to each relief valve.

[0014] Preferably, the opening pressure of the travel diversion valve stem is controlled at the moment when the travel directional valve stem is about to close.

[0015] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0016] (1) In view of the current situation of the main control valve of wheeled hydraulic excavators, and the requirement to significantly increase the overall vehicle speed, this invention increases the hydraulic oil flow capacity of the walking system by adding a walking diverter valve and the walking directional valve in the main control valve in parallel, thereby reducing the pressure loss of hydraulic oil in the main control valve, so that the vehicle speed can reach the expected target and the energy loss can be reduced to an acceptable range.

[0017] (2) The system principle provided by this invention is relatively simple. It only requires adding a travel diverter valve and corresponding pipelines to the existing hydraulic system of a wheeled hydraulic excavator, and the increased cost is not significant. By adjusting the opening curve of the travel diverter valve and controlling its opening timing and performance, the energy loss of the system can be greatly reduced at high speeds without changing the operating performance of the original main control valve. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram showing the travel directional valve in the neutral position and the travel diversion valve in the closed position of the travel diversion system of the wheeled hydraulic excavator provided by the present invention.

[0020] Figure 2 A schematic diagram showing the flow of pressure oil in the forward-moving state of the wheeled hydraulic excavator travel diversion system provided by the present invention;

[0021] Figure 3 A schematic diagram showing the flow of pressure oil in the reverse position of the wheeled hydraulic excavator travel diversion system provided by the present invention;

[0022] Figure 4 This is a diagram showing the opening pressure and time control of the traveling diversion valve and the traveling reversing valve in this invention.

[0023] Reference numerals: 1. Travel directional valve; 2. Travel motor; 2a. First interface; 2b. Second interface; 3. Travel diverter valve; 4. Hydraulic pump; 5. Hydraulic oil tank; 6. Inlet pipe; 7. Return pipe; 8. Connecting pipe; 8a. First oil pipe; 8b. Second oil pipe; 9. Safety valve; 10. First branch pipe; 11. Second branch pipe; 12. Third branch pipe; 13. Fourth branch pipe; 14. First check valve; 15. Second check valve; 16. Third check valve; 17. Fifth branch pipe; 18. Sixth branch pipe; 19. First throttle valve; 20. Relief valve; 21. Second throttle valve; 22. Motor safety valve; 23. Drain pipe; 24. Filter. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0026] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed by this invention.

[0027] Combination Figures 1 to 3As shown, a travel diversion system for a wheeled hydraulic excavator includes a travel directional valve 1 and a travel motor 2. A hydraulic oil tank 5 is connected to a hydraulic pump 4 via an oil pipe. A filter 24 is installed on the oil pipe between the hydraulic pump 4 and the hydraulic oil tank 5 to remove impurities. The outlet end of the hydraulic pump 4 is connected to the travel directional valve 1 via an oil inlet pipe 6. The travel directional valve 1 is connected to the hydraulic oil tank 5 via a return oil pipe 7. The travel motor 2 is connected to the travel directional valve 1 via a connecting pipe 8. The system also includes a travel diversion valve 3 connected to the oil inlet pipe 6, the oil return pipe 7, and the connecting pipe 8. When the travel directional valve 1 is switched to the forward position and the travel diversion valve 3 is in the open state, the pressurized oil pumped from the hydraulic pump 4 supplies oil to the travel motor 2 through both the travel directional valve 1 and the travel diversion valve 3. The return oil from the travel motor 2 flows back to the hydraulic oil tank 5 through both the travel directional valve 1 and the travel diversion valve 3. By using the travel diverter valve 3 in parallel with the travel reversing valve 1, the hydraulic oil flow capacity of the travel system is increased, and the pressure loss of the hydraulic oil is reduced, so that the vehicle travel speed can reach the expected target while the energy loss can be reduced to an acceptable range.

[0028] Combination Figure 1 and Figure 4 As shown, the travel directional valve 1 is a Y-type three-position six-way hydraulic directional valve; the travel diverter valve 3 is a hydraulic two-position four-way spool valve; the valve stems of the travel directional valve 1 and the travel diverter valve 3 are controlled by the same forward pilot oil circuit. Through theoretical analysis and repeated practical vehicle testing, the opening pressure of the travel diverter valve 3 is controlled at the moment when the valve stem of the travel directional valve 1 is about to close, thus maintaining the vehicle's original good handling performance. When the expected driving speed is reached, the power loss of the hydraulic system is reduced by approximately 50kW after installing the travel diverter valve 3, which has significant economic value. Specifically, the opening pressure and timing control of the travel directional valve 1 and the travel diverter valve 3 are as follows: Figure 4 As shown in the figure, curve Q represents the opening pressure and time control curve of travel directional valve 1, and curve P represents the opening pressure and time control curve of travel diversion valve 3. Travel directional valve 1 opens at a pressure of 5 bar and quickly opens completely at 25 bar, i.e., at time t1. Correspondingly, the opening pressure of travel diversion valve 3 is 22 bar, and it quickly opens completely at time t1.

[0029] Combination Figures 1 to 3As shown, in this embodiment, the travel reversing valve 1 has interfaces A, B, E, and F. When the travel reversing valve 1 is in the neutral position, both ports A and B are connected to port F; when it is in the forward position (i.e., in the right position), ports E and B are connected, and ports A and F are connected; when it is in the reverse position (i.e., in the left position), ports E and A are connected, and ports F and B are connected. The travel diversion valve 3 has interfaces G, H, M, and N. When the travel diversion valve 3 is in the closed state, ports G and H are disconnected, and ports M and N are disconnected; when it is in the open state, ports G and H are connected, and ports M and N are connected. The connecting pipe 8 includes a first oil pipe 8a and a second oil pipe 8b; the travel motor 2 has a first interface 2a and a second interface 2b.

[0030] The outlet end of the oil inlet pipe 6 is connected to port E of the travel reversing valve 1.

[0031] One end of the first oil pipe 8a is connected to port B of the travel reversing valve 1, and the other end is connected to the first port 2a of the travel motor 2.

[0032] One end of the second oil pipe 8b is connected to port A of the travel reversing valve 1, and the other end is connected to the second port 2b of the travel motor 2.

[0033] The travel diversion valve 3 has its G port connected to the inlet pipe 6 via the first branch pipe 10; its H port connected to the first oil pipe 8a via the second branch pipe 11; its M port connected to the second oil pipe 8b via the third branch pipe 12; and its D port connected to the return oil pipe 7 via the fourth branch pipe 13. A first check valve 14 is provided on the first branch pipe 10, ensuring that pressurized oil can only flow into the travel diversion valve 3 in one direction.

[0034] Combination Figures 1 to 3 As shown, a safety valve 9 is connected between the oil inlet pipe 6 and the oil return pipe 7. This safety valve 9 is a pilot-operated relief valve. A second check valve 15 is installed on the inlet pipe of the safety valve 9. By installing the safety valve 9, when the oil pressure in the oil inlet pipe 6 is too high, the safety valve 9 will overflow, preventing excessive pressure from damaging the travel directional valve 1 and the travel diverter valve 3. In addition, by installing the second check valve 15, the pressurized oil flows in one direction, preventing the pressurized oil from returning from the safety valve 9 to the oil inlet pipe 6.

[0035] Combination Figure 1As shown, the travel directional valve 1 also has ports C and D; when the travel directional valve 1 is in the neutral position, ports C and D are connected; when in the forward and reverse positions, ports C and D are disconnected; a fifth branch pipe 17 is provided on the oil inlet pipe 6 and connected to port C, and a sixth branch pipe 18 is connected to port D. The outlet end of the sixth branch pipe 18 is connected to the return oil pipe 7, and a first throttle valve 19 is provided on the sixth branch pipe 18; an overflow valve 20 is connected in parallel to the first throttle valve 19, and the pressure of the overflow valve 20 is 31.4 bar. By setting the fifth branch pipe 17, the sixth branch pipe 18, and the overflow valve 20 connected in parallel to the first throttle valve 19, the oil inlet pressure in the oil inlet pipe 6 can always be maintained at 31.4 bar when the travel directional valve 1 is in the neutral position. The purpose of setting the first throttle valve 19 and the overflow valve 20 is to establish oil pressure in the oil inlet pipe 6.

[0036] Combination Figure 1 As shown, a third check valve 16 is provided on the oil inlet pipe 6; the third check valve 16 is located between the connection point of the fifth branch pipe 17 and the oil inlet pipe 6 and the E port of the travel reversing valve 1. By providing the third check valve 16, backflow of pressurized oil into the oil inlet pipe 6 is prevented.

[0037] Combination Figure 1 As shown, a second throttle valve 21 is installed inside the travel directional valve 1. When the travel directional valve 1 is in the neutral position, port A is connected to port B, and then through the second throttle valve 21, it is connected to port F. The purpose of setting the second throttle valve 21 is to act as a load resistance, preventing the pressurized oil in the travel motor 2 from flowing back into the hydraulic oil tank 5 quickly.

[0038] In this embodiment, combined with Figures 1 to 3 As shown, a motor safety valve 22 is connected between the first port 2a and the second port 2b of the travel motor 2. This motor safety valve 22 consists of two relief valves connected in opposite directions. The outlets of the two relief valves converge and connect to the variable displacement hydraulic motor inside the travel motor 2. The variable displacement hydraulic motor is connected to the hydraulic oil tank 5 via a drain pipe 23. A check valve is connected in parallel to each relief valve. By setting the motor safety valve 22, when the oil pressure inside the travel motor 2 is too high, the pressurized oil directly passes through the motor safety valve 22, and then through the variable displacement hydraulic motor and the drain pipe 23 to relieve pressure, thus preventing damage to the travel motor 2.

[0039] In this embodiment, the reversing valve 1, the safety valve 9, the first throttle valve 19, the second throttle valve 21, the second check valve 15, and the third check valve 16 together constitute the main control valve structure.

[0040] The working principle of the wheeled hydraulic excavator travel diversion system provided by this invention is as follows:

[0041] Combination Figure 1 As shown, when the wheeled hydraulic excavator is stationary, the travel directional valve 1 is in the neutral position, and the travel diverter valve 3 is closed. At this time, ports A and B of the travel directional valve 1 are connected to port F, while ports C and D are connected. All ports of the travel diverter valve 3 are disconnected. Therefore, under the action of the hydraulic pump 4, the oil enters the inlet pipe 6, passes through the fifth branch pipe 17, and ports C and D of the travel directional valve 1, and then flows back to the hydraulic oil tank 5 through the sixth branch pipe 18. By utilizing the first throttle valve 19 installed on the sixth branch pipe 18 and the relief valve 20 connected in parallel to the first throttle valve 19, and the pressure of the relief valve 20 is 31.4 bar, the pressure in the inlet pipe 6 can be maintained at 31.4 bar. When the pressure exceeds 31.4 bar, the safety valve 9 plays the role of overflow pressure relief. In addition, when the travel reversing valve 1 is in the neutral position, after the A port is connected to the B port, it is connected to the F port through the second throttle valve 21. The purpose of the second throttle valve 21 is to act as a load resistance to prevent the pressure oil in the travel motor 2 from flowing back into the hydraulic oil tank 5 quickly.

[0042] Combination Figure 2 As shown, when the wheeled hydraulic excavator is in the forward position, under the control of the forward pilot oil circuit, the travel directional valve 1 is in the right position, and the travel diverter valve 3 is in the open position. At this time, ports E and B of the travel directional valve 1 are connected, ports A and F are connected, and ports C and D are disconnected. Furthermore, ports G and H of the travel diverter valve 3 are connected, and ports M and N are connected. The flow of the pressurized oil is as follows... Figure 2 As indicated by the arrows. Specifically, after the pressurized oil from the hydraulic pump 4 enters the inlet pipe 6, it is split into two supply lines at the first branch pipe 10:

[0043] The first oil supply is as follows: after the pressure oil passes through the first one-way valve 14 on the first branch pipe 10, it enters the G port of the travel diversion valve 3, and then flows out from the H port of the travel diversion valve 3 and enters the first oil pipe 8a. It merges with the pressure oil flowing through the travel reversing valve 1 and supplies oil to the first interface 2a of the travel motor 2, driving the travel motor 2 to rotate forward and making the wheeled hydraulic excavator move forward.

[0044] The first oil supply is as follows: the pressurized oil passes through the inlet pipe 6 and the third check valve 16 and enters the E port of the travel directional valve 1. After flowing out from the B port of the travel directional valve 1, it enters the first oil pipe 8a and merges with the pressurized oil flowing through the travel diversion valve 3 to supply oil to the first port 2a of the travel motor 2, driving the travel motor 2 to rotate forward and making the wheeled hydraulic excavator move forward.

[0045] When the oil pressure in the oil inlet pipe 6 is too high, the safety valve 9 will cause an overflow to prevent the excessive pressure from damaging the travel reversing valve 1 and the travel diverter valve 3.

[0046] The return oil circuit is as follows: the pressurized oil flowing through the travel motor 2 exits from the second port 2b of the travel motor 2, passes through the second oil pipe 8b, and then splits into two paths. One path of return oil passes through the third branch pipe 12 and enters the M port of the travel diverter valve 3, then exits from the N port and passes through the fourth branch pipe 13 into the return oil pipe 7 and flows back to the hydraulic oil tank 5. The other path of return oil enters from the second oil pipe 8b into the A port of the travel directional valve 1, then exits from the F port and enters the return oil pipe 7 and flows back to the hydraulic oil tank 5.

[0047] Therefore, during travel, the high-pressure oil pumped from the hydraulic pump 4 supplies oil to the travel motor 2 through both the travel directional valve 1 and the travel diversion valve 3. This reduces the pressure loss of the hydraulic oil at the main control valve, allowing the vehicle to reach the expected speed while keeping energy loss within an acceptable range.

[0048] Combination Figure 3 As shown, when the wheeled hydraulic excavator is in reverse, the travel directional valve 1 is in the left position, and the travel diversion valve 3 is closed. At this time, all ports in the travel diversion valve 3 are disconnected. Meanwhile, ports E and A of the travel directional valve 1 are open, ports F and B are open, and ports C and D are closed. The flow of the pressurized oil is as follows... Figure 3 As indicated by the arrows in the diagram. Specifically, pressurized oil passes through the inlet pipe 6 and the third check valve 16 before entering port E of the travel directional valve 1. It then flows out from port A of the travel directional valve 1 and into the second oil pipe 8b, supplying oil to the second port 2b of the travel motor 2. This drives the travel motor 2 to reverse, causing the wheeled hydraulic excavator to move backward. When the oil pressure in the inlet pipe 6 is too high, the safety valve 9 creates an overflow effect, preventing excessive pressure from damaging the travel directional valve 1 and the travel diverter valve 3.

[0049] The return oil circuit of the wheeled hydraulic excavator in the reverse position is as follows: the pressurized oil after flowing through the travel motor 2 flows out from the first port 2a of the travel motor 2, enters the B port of the travel reversing valve 1 after passing through the first oil pipe 8a, and then flows out from the F port into the return oil pipe 7 and flows back to the hydraulic oil tank 5.

[0050] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A travel diversion system for a wheeled hydraulic excavator, comprising a travel directional valve (1) and a travel motor (2); a hydraulic oil tank (5) is connected to a hydraulic pump (4) via an oil pipe, and the outlet end of the hydraulic pump (4) is connected to the travel directional valve (1) via an oil inlet pipe (6); and the travel directional valve (1) is connected to the hydraulic oil tank (5) via a return oil pipe (7); the travel motor (2) and the travel directional valve (1) are connected via a connecting pipe (8); characterized in that: It also includes a travel flow divider valve (3) connected to the oil inlet pipe (6), the oil return pipe (7), and the connecting pipe (8); The travel directional valve (1) is a Y-type three-position six-way hydraulic directional valve; the travel diversion valve (3) is a hydraulic two-position four-way slide valve; the valve stems of the travel directional valve (1) and the travel diversion valve (3) are controlled by the same forward pilot oil circuit; The travel reversing valve (1) has A, B, E and F ports. When the travel reversing valve (1) is in the neutral position, ports A and B are connected to port F. When it is in the forward position, ports E and B are connected, and ports A and F are connected. When it is in the reverse position, ports E and A are connected, and ports F and B are connected. The walking diversion valve (3) has G, H, M and N interfaces. When the walking diversion valve (3) is in the closed state, the G port is disconnected from the H port and the M port is disconnected from the N port; when it is in the open state, the G port is connected to the H port and the M port is connected to the N port. The connecting pipe (8) includes a first oil pipe (8a) and a second oil pipe (8b); the walking motor (2) has a first interface (2a) and a second interface (2b). The outlet end of the oil inlet pipe (6) is connected to the E port of the travel reversing valve (1); one end of the first oil pipe (8a) is connected to the B port of the travel reversing valve (1), and the other end is connected to the first port (2a) of the travel motor (2). One end of the second oil pipe (8b) is connected to port A of the travel reversing valve (1), and the other end is connected to the second port (2b) of the travel motor (2). The G port of the traveling diverter valve (3) is connected to the oil inlet pipe (6) through the first branch pipe (10); the H port is connected to the first oil pipe (8a) through the second branch pipe (11); the M port is connected to the second oil pipe (8b) through the third branch pipe (12); and the D port is connected to the return oil pipe (7) through the fourth branch pipe (13). By using the travel diverter valve (3) in parallel with the travel directional valve (1), the hydraulic oil flow capacity of the travel system is increased, and the pressure loss of the hydraulic oil is reduced. The opening pressure of the valve stem of the travel diversion valve (3) is controlled at the moment when the valve stem of the travel reversing valve (1) is about to end opening; When the travel directional valve (1) is switched to the forward position and the travel diversion valve (3) is in the open state, the pressure oil pumped out by the hydraulic pump (4) supplies oil to the travel motor (2) through the two oil circuits of the travel directional valve (1) and the travel diversion valve (3); the return oil of the travel motor (2) flows back to the hydraulic oil tank (5) through the two oil circuits of the travel directional valve (1) and the travel diversion valve (3).

2. The travel diversion system for a wheeled hydraulic excavator as described in claim 1, characterized in that: A first check valve (14) is provided on the first branch pipe (10).

3. The travel diversion system for a wheeled hydraulic excavator as described in claim 1, characterized in that: A safety valve (9) is connected between the oil inlet pipe (6) and the oil return pipe (7). The safety valve (9) is a pilot-operated relief valve. A second check valve (15) is installed on the inlet end of the safety valve (9).

4. The travel diversion system for a wheeled hydraulic excavator as described in claim 1, characterized in that: The travel reversing valve (1) is also equipped with ports C and D; when the travel reversing valve (1) is in the neutral position, ports C and D are connected; when it is in the forward or backward position, ports C and D are disconnected; a fifth branch pipe (17) is provided on the oil inlet pipe (6) and connected to port C, and a sixth branch pipe (18) is connected to port D. The outlet end of the sixth branch pipe (18) is connected to the oil return pipe (7), and a first throttle valve (19) is provided on the sixth branch pipe (18); an overflow valve (20) is connected in parallel at the first throttle valve (19), and the pressure of the overflow valve (20) is 31.4 bar.

5. The travel diversion system for a wheeled hydraulic excavator as described in claim 4, characterized in that: A third check valve (16) is provided on the oil inlet pipe (6); the third check valve (16) is located between the connection point of the fifth branch pipe (17) and the oil inlet pipe (6) and the E port of the travel reversing valve (1).

6. The travel diversion system for a wheeled hydraulic excavator as described in claim 1, characterized in that: A second throttle valve (21) is provided inside the travel reversing valve (1). When the travel reversing valve (1) is in the neutral position, port A is connected to port B and then connected to port F through the second throttle valve (21).

7. The travel diversion system for a wheeled hydraulic excavator as described in claim 1, characterized in that: A motor safety valve (22) is connected between the first interface (2a) and the second interface (2b) of the walking motor (2). The motor safety valve (22) consists of two relief valves connected in opposite directions. The outlets of the two relief valves converge and are connected to the variable hydraulic motor inside the walking motor (2). The variable hydraulic motor is connected to the hydraulic oil tank (5) through the drain pipe (23). A check valve is connected in parallel to each relief valve.

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