Hydraulic walking system and hydraulic walking vehicle

Abstract

The application discloses a hydraulic walking system and a hydraulic walking vehicle. The hydraulic walking system comprises a main pump control module, a first variable control valve, a second variable control valve, a self-feedback control valve, a left walking module and a right walking module. The main pump control module comprises a main pump. The main pump is connected with a first oil port of the right walking module through a first throttling hole of the first variable control valve. The main pump is connected with a first oil port of the left walking module through a second throttling hole of the first variable control valve. A second oil port of the right walking module is connected with a third throttling hole of the self-feedback control valve. A second oil port of the left walking module is connected with a fourth throttling hole of the self-feedback control valve. The self-feedback control valve is connected with the second variable control valve. The second variable control valve is connected with the first variable control valve through a variable piston. The application realizes self-feedback adjustment of flow distribution, makes control more accurate, and effectively avoids walking deviation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic walking, in particular to a hydraulic walking system and a hydraulic walking vehicle. BACKGROUND

[0002] The hydraulic walking system is a system for realizing mechanical movement by using hydraulic principle, which is mainly composed of a hydraulic pump, a hydraulic motor, a hydraulic cylinder, a hydraulic valve and an oil tank, and is widely used in various engineering machines and has the characteristics of flexibility, high efficiency and stability.

[0003] At present, the relationship between the volumetric efficiency and the pressure of the hydraulic walking system is that the greater the load, the higher the pressure of the hydraulic walking system, the lower the volumetric efficiency, and the less the actual motor work liquid. Due to the influence of road conditions and other external factors, the pressure of the two walking hydraulic systems fluctuates, the volumetric efficiency differs, the actual working flow of the two walking motors changes, the two sides of the vehicle wheel deviate from the set speed, and walking deviation occurs. In addition, if the internal friction pair of the hydraulic walking system is worn during operation, the volumetric efficiency decreases, and the attenuation degree of the two sides of the system is inconsistent, which will also cause the actual flow of the two walking systems to deviate, thereby causing walking deviation. On the other hand, considering the road conditions (such as mud), the left and right drive wheels may slip, which may also cause the actual walking speed of the two sides to deviate from the theoretical value, thereby causing walking deviation. SUMMARY

[0004] The present application provides a hydraulic walking system and a hydraulic walking vehicle to solve the problem that the actual walking motor speed of the two sides deviates due to the change of the current volumetric rate or the unilateral wheel slip, thereby causing the whole vehicle to deviate.

[0005] According to an aspect of the present application, a hydraulic walking system is provided, which comprises a main pump control module, a first variable control valve, a second variable control valve, a self-feedback control valve, a left walking module and a right walking module. The main pump control module comprises a main pump, the main pump is connected with a first oil port of the right walking module through a first throttle hole of the first variable control valve, and the main pump is connected with a first oil port of the left walking module through a second throttle hole of the first variable control valve. The throttle area of the first throttle hole and the throttle area of the second throttle hole are adjusted to control the flow of the hydraulic oil output by the main pump before the hydraulic oil is divided to the motors through the first throttle hole and the second throttle hole. The second oil port of the right walking module is connected with a third throttle hole of the self-feedback control valve, and the second oil port of the left walking module is connected with a fourth throttle hole of the self-feedback control valve. The self-feedback control valve is connected with the second variable control valve. The throttle area of the third throttle hole and the throttle area of the fourth throttle hole are adjusted by adjusting the position of the valve core of the self-feedback control valve to control the back pressure of the low-pressure side hydraulic oil after the low-pressure side hydraulic oil is throttled through the third throttle hole and the fourth throttle hole. The back pressure is used as a feedback signal to make the hydraulic oil move the valve core of the second variable control valve to control the oil inlet logic of the first variable control valve to move the valve core of the first variable control valve, so as to control the flow distribution of the main pump, so that the low-pressure side hydraulic oil flow after the hydraulic oil drives the motor to work is maintained at a flow theoretical value, and the actual working speed of the motors on both sides is maintained at a theoretical value. The second variable control valve is connected with the first variable control valve through a variable piston.

[0006] Optionally, the left walking module comprises a left walking inlet valve block, a left walking motor and a left walking back oil valve block. The hydraulic oil output by the main pump is divided to the left walking motor through the second throttle hole. After the hydraulic oil drives the left walking motor to work, the low-pressure side back oil of the left walking motor flows into the fourth throttle hole of the self-feedback control valve through the left walking back oil valve block.

[0007] The right walking module comprises a right walking inlet valve block, a right walking motor and a right walking back oil valve block. The hydraulic oil output by the main pump is divided to the right walking motor through the first throttle hole. After the hydraulic oil drives the right walking motor to work, the low-pressure side back oil of the right walking motor flows into the third throttle hole of the self-feedback control valve through the right walking back oil valve block.

[0008] Optionally, when walking straight, the position of the self-feedback control valve spool is adjusted so that the orifice throttling area of the third throttling orifice and the orifice throttling area of the fourth throttling orifice are the same, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third throttling orifice and the fourth throttling orifice is the same, which is used as a feedback signal of the self-feedback control valve, the position of the second variable control valve spool is adjusted, the oil path logic of the first variable control valve is adjusted, and then the position of the first variable control valve spool is adjusted, so that the flow distribution of the hydraulic oil into the first oil port of the left motor and the first oil port of the right motor is adjusted, and the back flow of the hydraulic oil on the low pressure side of the motor after the hydraulic oil pushes the motor to work is maintained at a flow theoretical value, so that the actual working speeds of the two motors are the same.

[0009] Optionally, when the pressure of the high pressure oil port of the right walking motor is less than the pressure of the high pressure oil port of the left walking motor, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third throttling orifice is greater than the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth throttling orifice, and then the first force of the second variable control valve spool is less than the second force.

[0010] Wherein, the first force = the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth throttling orifice The cross-sectional area of the force of the second variable control valve spool;

[0011] The second force = the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third throttling orifice The cross-sectional area of the force of the second variable control valve spool.

[0012] Optionally, when the first force of the second variable control valve is less than the second force, the first variable control valve is adjusted to move, so that the orifice throttling area of the first throttling orifice becomes smaller, the orifice throttling area of the second throttling orifice becomes larger, the flow of the hydraulic oil output by the main pump before being distributed to the motors becomes smaller, the flow of the hydraulic oil output by the main pump before being distributed to the motors becomes larger, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third throttling orifice becomes smaller, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth throttling orifice becomes larger, and then the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third throttling orifice is equal to the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth throttling orifice.

[0013] Optionally, when the pressure of the high pressure oil port of the right walking motor is greater than the pressure of the high pressure oil port of the left walking motor, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third throttling orifice is less than the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth throttling orifice, and then the first force of the second variable control valve is greater than the second force.

[0014] Wherein, the first force = the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth throttling orifice Second variable control valve spool force cross-sectional area;

[0015] Second force = back pressure of motor low pressure side hydraulic oil after throttling through third throttle hole Second variable control valve spool force cross-sectional area.

[0016] Optionally, when the first force of the second variable control valve is greater than the second force, the first variable control valve is adjusted to move, so that the throttle hole throttling area of the first throttle hole becomes larger, the throttle hole throttling area of the second throttle hole becomes smaller, the flow of the main pump output hydraulic oil after passing through the first throttle hole and before the motor becomes larger, the flow of the main pump output hydraulic oil after passing through the second throttle hole and before the motor becomes smaller, the back pressure of the motor low pressure side hydraulic oil after throttling through the third throttle hole becomes larger, the back pressure of the motor low pressure side hydraulic oil after throttling through the fourth throttle hole becomes smaller, until the back pressure of the motor low pressure side hydraulic oil after throttling through the third throttle hole is equal to the back pressure of the motor low pressure side hydraulic oil after throttling through the fourth throttle hole.

[0017] Optionally, the hydraulic walking system further comprises a pilot pump and an electric proportional pressure reducing valve, the main pump is connected with the pilot pump, the pilot pump is connected with the electric proportional pressure reducing valve, and the electric proportional pressure reducing valve is connected with the self-feedback control valve.

[0018] Optionally, the left walking module comprises a left motor driven wheel and a first rotation speed sensor, the left motor driven wheel is connected with the first rotation speed sensor, the right walking module comprises a right motor driven wheel and a second rotation speed sensor, the right motor driven wheel is connected with the second rotation speed sensor, based on the ratio of the rotation speed value detected by the first rotation speed sensor and the rotation speed value detected by the second rotation speed sensor, the electric proportional pressure reducing valve control current is adjusted to control the movement of the self-feedback control valve spool.

[0019] According to another aspect of the present application, a hydraulic walking vehicle is provided, which comprises the hydraulic walking system of any one of the embodiments of the present application.

[0020] The technical scheme of the embodiment of the present application, the hydraulic walking system comprises a main pump control module, a first variable control valve, a second variable control valve, a self-feedback control valve, a left walking module and a right walking module, the main pump control module comprises a main pump, the main pump is connected with a first oil port of the right walking module through a first throttle hole of the first variable control valve, the main pump is connected with a first oil port of the left walking module through a second throttle hole of the first variable control valve, the flow of the hydraulic oil output by the main pump after passing through the first throttle hole and the second throttle hole is controlled by adjusting the throttle hole throttling area of the first throttle hole and the throttle hole throttling area of the second throttle hole, a second oil port of the right walking module is connected with a third throttle hole of the self-feedback control valve, a second oil port of the left walking module is connected with a fourth throttle hole of the self-feedback control valve, the self-feedback control valve is connected with the second variable control valve, the back pressure of the low-pressure side hydraulic oil after passing through the third throttle hole and the fourth throttle hole is controlled by adjusting the throttle hole throttling area of the third throttle hole and the throttle hole throttling area of the fourth throttle hole, the valve core position of the second variable control valve is adjusted, the throttle hole throttling area of the first throttle hole and the throttle hole throttling area of the second throttle hole are controlled, so that the low-pressure side hydraulic oil return flow after the hydraulic oil drives the motor to work is maintained at a flow theoretical value, the load low-pressure side return flow is used as a feedback signal to perform self-feedback adjustment on the flow distribution, no matter whether the load changes or the volumetric efficiency decays, the flow distribution is always performed according to the set proportion, the rotation speed of the two sides of the wheels is accurately controlled, accurate steering is realized, and walking deviation is avoided, further, the second variable control valve is connected with the first variable control valve through a variable piston, left and right wheel differential control of the one-pump double-motor hydrostatic walking unit is realized, and the accurate control of straight walking or walking steering is ensured.

[0021] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it intended to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creating laborious work.

[0023] Figure 1 is a structure and basic control principle schematic diagram of a hydraulic walking system according to the embodiment of the present application;

[0024] Figure 2 is a structure and hydraulic principle schematic diagram of a hydraulic walking system according to the embodiment of the present application;

[0025] Figure 3 is a hydraulic oil circuit and valve core position schematic diagram of the hydraulic walking system in a straight walking theoretical state according to an embodiment of the present application;

[0026] Figure 4 is a hydraulic oil circuit and valve core position schematic diagram of the hydraulic walking system in a left running deviation or left steering case according to an embodiment of the present application;

[0027] Figure 5 is a hydraulic oil circuit and valve core position schematic diagram of the hydraulic walking system in a right running deviation or right steering case according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] In order to make the personnel in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a 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 labor should belong to the scope of protection of the present application.

[0029] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily have to describe a specific order or sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0030] Figure 1 A structural schematic diagram of a hydraulic walking system is provided for the embodiments of the present application, and the present embodiment can be applied to a pump and double-motor hydraulic walking control case. As shown in Figure 1As shown, the hydraulic walking system includes a main pump control module, a first variable control valve 200, a second variable control valve 300, a self-feedback control valve 400, a left walking module 500 and a right walking module 600. The main pump control module includes a main pump 100. The main pump 100 is connected to a first oil port of the left walking module 500 through a second throttle hole of the first variable control valve 200. The main pump 100 is connected to a first oil port of the right walking module 600 through a first throttle hole of the first variable control valve 200. By adjusting throttle hole throttling areas A1 and A2 of the first and second throttle holes, the flow of the hydraulic oil output by the main pump 100 after passing through the first and second throttle holes is controlled. A second oil port of the left walking module 500 is connected to a fourth throttle hole of the self-feedback control valve 400. A second oil port of the right walking module 600 is connected to a third throttle hole of the self-feedback control valve 400. The self-feedback control valve 400 is connected to the second variable control valve 300. By adjusting the position of the valve core of the self-feedback control valve 400, the throttle hole throttling areas A3 and A4 of the third and fourth throttle holes are adjusted to control the back pressure of the low-pressure side hydraulic oil after passing through the third and fourth throttle holes. The back pressure serves as a feedback signal to make the hydraulic oil push the valve core of the second variable control valve 300 to move, so as to control the oil inlet logic of the first variable control valve 200 to make the valve core of the first variable control valve 200 move, thereby controlling the flow distribution of the main pump 100. The low-pressure side hydraulic oil flow after the hydraulic oil pushes the motor to work is maintained at a flow theoretical value, so that the actual working speed of the motors on both sides is maintained at a theoretical value. The second variable control valve 300 is connected to the first variable control valve 200 through a variable piston 700.

[0031] The main pump 100 provides hydraulic oil required for work. The pressure of the hydraulic oil is determined by the load. Specifically, the main pump 100 outputs a road of hydraulic oil, which is divided into two roads by the first variable control valve 200, to the left walking module 500 and the right walking module 600 to drive the modules to work.

[0032] The first and second throttle holes of the first variable control valve 200 can be variable throttle holes. The throttle hole throttling areas A1 and A2 of the first and second throttle holes can change with the movement of the valve core of the first variable control valve 200. Similarly, the third and fourth throttle holes of the self-feedback control valve 400 can be variable throttle holes. The throttle hole throttling areas A3 and A4 of the third and fourth throttle holes can change with the movement of the valve core of the self-feedback control valve 400. The relationship between the movement direction of the valve core and the throttle hole throttling area is shown in Table 1.

[0033] Table 1 Relationship between movement direction of valve core and throttle hole throttling area

[0034]

[0035] In the embodiment, the self-feedback control valve 400 can self-feedback regulate the flow distribution, always output the flow in the set proportion regardless of the change of the load, drive the wheels, and has the wheel slip control compensation strategy, realizes the accurate differential control, and specifically: after the driver operates the steering wheel or handle to issue the walking instruction (or steering angle), the hydraulic walking vehicle ECU controls the corresponding actuator of the hydraulic walking system based on the walking instruction; when the deviation occurs, the self-feedback control valve 400 is used to adjust the low-pressure side hydraulic oil return flow of the motor after the hydraulic oil pushes the motor to work to the theoretical value, so as to complete the deviation control.

[0036] Continuing to refer to Figure 1 and Figure 2 As shown, on the basis of the above, the left walking module 500 includes a left walking inlet valve block 501, a left walking motor 502, and a left walking return valve block 503. The hydraulic oil output by the main pump 100 is branched to the left walking motor 502 after passing through the second throttle hole. After the hydraulic oil pushes the left walking motor 502 to work, the low-pressure side return oil of the left walking motor 502 flows into the fourth throttle hole of the self-feedback control valve 400 through the left walking return valve block 503.

[0037] The right walking module 600 includes a right walking inlet valve block 601, a right walking motor 602, and a right walking return valve block 603. The hydraulic oil output by the main pump 100 is branched to the right walking motor 602 after passing through the first throttle hole. After the hydraulic oil pushes the right walking motor 602 to work, the low-pressure side return oil of the right walking motor 602 flows into the third throttle hole of the self-feedback control valve 400 through the right walking return valve block 603.

[0038] Among them, the left walking inlet valve block 501 and the right walking inlet valve block 601 control the inlet direction of the walking motor, the left walking return valve block 503 and the right walking return valve block 603 control the low-pressure side return direction of the walking motor, and the left walking inlet valve block 501, the right walking inlet valve block 601, the left walking return valve block 503 and the right walking return valve block 603 are matched to realize the forward and reverse rotation control of the left and right walking motors, and the whole vehicle is controlled to realize the walking actions such as forward, backward, and original turning.

[0039] In the embodiment, the left walking inlet valve block 501, the right walking inlet valve block 601, the left walking return valve block 503, and the right walking return valve block 603 are controlled to cooperate to make the left and right walking motors rotate forward and reverse, and the low-pressure side return oil of the corresponding left and right walking motors can be feedback regulated by the self-feedback control valve 400.

[0040] Specifically, the main pump 100 outputs hydraulic oil through the second throttle hole and then is distributed to the left travel motor 502, that is, q2 is the flow before the hydraulic oil is distributed to the left travel motor 502 after passing through the second throttle hole, and after the hydraulic oil drives the left travel motor 502 to work, the low-pressure side of the left travel motor 502 returns oil through the left travel return valve block 503 and flows into the fourth throttle hole of the self-feedback control valve 400, that is, q4 is the low-pressure side hydraulic oil return flow after the hydraulic oil drives the motor to work.

[0041] The main pump 100 outputs hydraulic oil through the first throttle hole and then is distributed to the right travel motor 602, that is, q1 is the flow before the hydraulic oil is distributed to the right travel motor 602 after passing through the first throttle hole, and after the hydraulic oil drives the right travel motor 602 to work, the low-pressure side of the right travel motor 602 returns oil through the right travel return valve block 603 and flows into the third throttle hole of the self-feedback control valve 400, that is, q3 is the low-pressure side hydraulic oil return flow after the hydraulic oil drives the motor to work.

[0042] Continuing to refer to Figure 1 , Figure 2 and Figure 3 , on the basis of the above, when traveling in a straight line, the position of the valve core of the self-feedback control valve 400 is adjusted so that the throttle hole throttling area A3 of the third throttle hole and the throttle hole throttling area A4 of the fourth throttle hole are the same, the back pressure of the low-pressure side hydraulic oil after passing through the third throttle hole and the fourth throttle hole after the main pump 100 passes through the first throttle hole and the second throttle hole and then flows to the motor to work is controlled to be the same, which is the feedback signal of the self-feedback control valve 400, the position of the valve core of the second variable control valve 300 is adjusted to adjust the oil way logic of the first variable control valve 200, and then the position of the valve core of the first variable control valve 200 is adjusted to control the flow distribution of the hydraulic oil entering the first oil port of the left motor and the first oil port of the right motor, so that the low-pressure side hydraulic oil return flow after the hydraulic oil drives the motor to work is maintained at the flow theoretical value, and then the actual working speed of the motors on both sides is the same, and straight-line travel is achieved.

[0043] Specifically, when traveling in a straight line, refer to Figure 3 , which is the ideal state of the oil way and the positions of the valve cores of the first variable control valve 200, the second variable control valve 300 and the self-feedback control valve 400 when traveling in a straight line, at this time, the electric proportional pressure reducing valve current is the middle current , and the pilot pressure after the pressure reducing valve is , the valve core positions of the second variable control valve 300 and the self-feedback control valve 400 are both in the middle state, that is, the throttling area A3 of the third throttling hole is equal to the throttling area A4 of the fourth throttling hole, the flow q3 in front of the diverter motor after passing through the third throttling hole is equal to the flow q4 in front of the diverter motor after passing through the fourth throttling hole, the return oil back pressure P3 generated after throttling through the third throttling hole is equal to the return oil back pressure P4 generated after throttling through the fourth throttling hole, further, after the hydraulic oil pushes the left travel motor 502 to work, the low-pressure side hydraulic oil return oil flow q4 is equal to the low-pressure side hydraulic oil return oil flow q3 after the hydraulic oil pushes the right travel motor 602 to work, then the left travel motor 502 and the right travel motor 602 have the same rotational speed, and the whole vehicle is in an ideal straight line travel.

[0044] Continue to see Figure 1 、 Figure 2 and Figure 4 As shown, on the basis of the above, when the pressure P2 of the high-pressure oil port of the right travel motor is less than the pressure P1 of the high-pressure oil port of the left travel motor, the return oil back pressure P3 generated by the hydraulic oil on the low-pressure side of the motor after throttling through the third throttle hole is greater than the return oil back pressure P4 generated by the hydraulic oil on the low-pressure side of the motor after throttling through the fourth throttle hole, then the first force F1 on the valve core of the second variable control valve 300 is less than the second force F2; wherein, the first force F1 = the return oil back pressure P4 generated by the hydraulic oil on the low-pressure side of the motor after throttling through the fourth throttle hole The cross-sectional area of ​​the second variable control valve core; the second force F2 = the return oil back pressure P3 generated by the hydraulic oil on the low-pressure side of the motor after throttling through the third throttle hole The force-bearing cross-sectional area of ​​the valve core of the second variable control valve.

[0045] Specifically, under the straight-line walking condition, if the load of the left walking motor 502 becomes larger, that is, the high-pressure oil port pressure P2 of the right walking motor is less than the high-pressure oil port pressure P1 of the left walking motor, at this time, due to the increase in the pressure on the side of the left walking motor 502, the volumetric efficiency becomes low, and the low-pressure side hydraulic oil return flow q4 after the hydraulic oil pushes the left walking motor to work is less than the low-pressure side hydraulic oil return flow q3 after the hydraulic oil pushes the right walking motor to work, and the return oil back pressure P3 generated after the hydraulic oil on the low-pressure side of the motor is throttled through the third throttle hole is greater than the return oil back pressure P4 generated after the hydraulic oil on the low-pressure side of the motor is throttled through the fourth throttle hole, then the speed of the left walking motor 502 is lower than the speed of the right walking motor 602, and the whole vehicle tends to deviate to the left, and the first force F1 of the second variable control valve 300 is less than the second force F2.

[0046] On the basis of the above, since the first force F1 of the second variable control valve 300 is smaller than the second force F2, the second variable control valve 300 generates a leftward force F3 due to the different effective areas of the large and small piston chambers of the variable piston 700. Specifically, the leftward force F3 = the final return tank pressure of the hydraulic oil P The small piston cavity of the variable piston 700 is subjected to force.

[0047] Continuing to refer to Figure 1 , Figure 2 and Figure 4 , on the basis of the above, when the first force F1 of the second variable control valve 300 is less than the second force F2, the throttle hole throttling area A1 of the first throttle hole is adjusted to be smaller, the throttle hole throttling area A2 of the second throttle hole is adjusted to be larger, the flow q1 of the hydraulic oil output by the main pump 100 after passing through the first throttle hole and before the motor is smaller, the flow q2 of the hydraulic oil output by the main pump 100 after passing through the second throttle hole and before the motor is larger, the back oil pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole is smaller, the back oil pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole is larger, until the back oil pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole is equal to the back oil pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole, that is, the spool position of the second variable control valve 300 at this time is in the neutral state, the spool of the first variable control valve 200 stops moving left, and then the left deflection variable self-feedback adjustment of the hydraulic walking system ends.

[0048] Continuing to refer to Figure 1 , Figure 2 and Figure 5 , on the basis of the above, when the high-pressure oil port pressure P2 of the right walking motor is greater than the high-pressure oil port pressure P1 of the left walking motor, the back oil pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole is less than the back oil pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole, then the first force F1 of the second variable control valve 300 is greater than the second force F2.

[0049] Specifically, in the straight walking working condition, if the load of the right walking motor 602 becomes larger, that is, the high-pressure oil port pressure P1 of the right walking motor is greater than the high-pressure oil port pressure P2 of the left walking motor, at this time, because the pressure on the right walking motor 602 side becomes larger, the volumetric efficiency becomes lower, the low-pressure side hydraulic oil return flow q4 after the hydraulic oil pushes the left walking motor 502 to do work is greater than the low-pressure side hydraulic oil return flow q3 after the hydraulic oil pushes the right walking motor to do work, the back oil pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole is less than the back oil pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole, then the speed of the left walking motor 502 is higher than the speed of the right walking motor 602, the vehicle has a tendency to run to the right, and the first force F1 of the second variable control valve 300 is greater than the second force F2.

[0050] On the basis of the above, since the first force F1 of the second variable control valve 300 is greater than the second force F2, at this time, the right force F3 is generated due to the second variable control valve 300 returning to the large piston cavity side of the variable piston 700 to the oil tank, specifically: the right force F3 = the final oil tank pressure P of the hydraulic oil (the force area of the large piston cavity of the variable piston 700 - the force area of the small piston cavity).

[0051] Continuing to refer to Figure 1 , Figure 2 and Figure 5 , on the basis of the above, when the first force F1 of the second variable control valve 300 is greater than the second force F2, the throttle hole throttle area A1 of the first throttle hole becomes larger, the throttle hole throttle area A2 of the second throttle hole becomes smaller, the flow rate q1 of the hydraulic oil output by the main pump 100 before the shunt motor becomes larger after passing through the first throttle hole, the flow rate q2 of the hydraulic oil output by the main pump 100 before the shunt motor becomes smaller after passing through the second throttle hole, the back pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole becomes larger, the back pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole becomes smaller, until the back pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole is equal to the back pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole, that is, at this time, the spool position of the second variable control valve 300 is in the neutral state, the spool of the first variable control valve 200 stops moving to the right, and the left bias variable self-feedback regulation of the hydraulic travel system ends.

[0052] Continuing to refer to Figure 3 , Figure 4 , Figure 5 , in actual straight travel, since the loads of the left travel motor 502 and the right travel motor 602 fluctuate at any time, the second variable control valve 300 spool oil way is dynamically switched in three states at any time in straight travel.

[0053] Continuing to refer to Figures 1 to 5 , on the basis of the above, the hydraulic travel system further comprises a pilot pump 102 and an electric proportional pressure reducing valve 800, the main pump 100 is connected with the pilot pump 102, the pilot pump 102 is connected with the electric proportional pressure reducing valve 800, and the electric proportional pressure reducing valve 800 is connected with the self-feedback control valve 400.

[0054] Among them, the electric proportional pressure reducing valve 800 can reduce the fixed pressure hydraulic oil of the pilot pump 102 to the required pressure according to the current size, and the current size and the output pressure are in a linear relationship.

[0055] In the embodiment, the output pressure of the electric proportional pressure reducing valve 800 is adjusted by controlling the current Ic, and then the throttle area A3 of the third throttle hole and the throttle area A4 of the fourth throttle hole are adjusted, and finally the hydraulic oil return flow on the low pressure side after the left traveling motor is driven by the hydraulic oil is equal to the hydraulic oil return flow on the low pressure side after the right traveling motor is driven by the hydraulic oil, so that the differential steering of the left and right wheels is realized.

[0056] By controlling the pressure after the electric proportional pressure reducing valve 800, the position of the valve core of the self-feedback control valve 400 is changed, the throttle area A3 of the third throttle hole and the throttle area A4 of the fourth throttle hole are adjusted, and the back pressure change of the hydraulic oil on the low pressure side of the motor after passing through the third throttle hole and the fourth throttle hole is adjusted.

[0057] Among them, the back pressure of the hydraulic oil on the low pressure side of the right traveling motor 602 after passing through the third throttle hole is related to the throttle area A3 of the third throttle hole of the valve core of the self-feedback control valve 400; the back pressure of the hydraulic oil on the low pressure side of the left traveling motor 502 after passing through the fourth throttle hole is related to the throttle area A4 of the fourth throttle hole of the valve core of the self-feedback control valve 400.

[0058] The ratio of the throttle area A3 of the third throttle hole to the throttle area A4 of the fourth throttle hole = the low pressure side return flow of the right traveling motor 602 and the left traveling motor 502 = the speed ratio of the right traveling motor 602 and the left traveling motor 502, so that the speed ratio of the left traveling motor 502 and the right traveling motor 602 is controlled by controlling the pressure after the electric proportional pressure reducing valve.

[0059] Specifically, referring to Figure 1 , Figure 2 , Figure 3 and Figure 4 , when the hydraulic traveling system is switched from straight traveling to left steering, the throttle area A3 of the third throttle hole is greater than the throttle area A4 of the fourth throttle hole, and the back pressure change of the hydraulic oil on the low pressure side of the motor after passing through the third throttle hole and the fourth throttle hole is adjusted as a feedback signal to adjust the position of the valve core of the second variable control valve 300, control the valve core of the first variable control valve 200 to move, make the distribution flow q1 of the right traveling motor 602 greater than the distribution flow q2 of the left traveling motor 502, make the speed of the right traveling motor 602 higher than the speed of the left traveling motor 502, and the hydraulic traveling system steers to the left.

[0060] When steering to the left, continue to refer to Figure 3 and 4 , which show the oil circuit switching from the ideal state of straight traveling to the left steering state of the hydraulic traveling system, at this time, the current of the electric proportional pressure reducing valve 800 is increased, the pressure after the pressure reducing valve When the hydraulic walking system is switched from straight walking to right steering, the third throttle hole throttling area A3 is smaller than the fourth throttle hole throttling area A4, the back pressure of the hydraulic oil flowing through the third throttle hole and the fourth throttle hole is changed, which is used as a feedback signal to adjust the spool position of the second variable control valve 300, control the spool movement of the first variable control valve 200, make the distribution flow q1 of the right walking motor 602 smaller than the distribution flow q2 of the left walking motor 502, make the speed of the right walking motor 602 lower than the speed of the left walking motor 502, and the hydraulic walking system steers to the right. Figure 4 When the hydraulic walking system is switched from straight walking to right steering, the third throttle hole throttling area A3 is smaller than the fourth throttle hole throttling area A4, the back pressure of the hydraulic oil flowing through the third throttle hole and the fourth throttle hole is changed, which is used as a feedback signal to adjust the spool position of the second variable control valve 300, control the spool movement of the first variable control valve 200, make the distribution flow q1 of the right walking motor 602 smaller than the distribution flow q2 of the left walking motor 502, make the speed of the right walking motor 602 lower than the speed of the left walking motor 502, and the hydraulic walking system steers to the right.

[0061] Specifically, as shown in Figure 1 , Figure 2 , Figure 3 and Figure 5 When the hydraulic walking system is switched from straight walking to right steering, the third throttle hole throttling area A3 is smaller than the fourth throttle hole throttling area A4, the back pressure of the hydraulic oil flowing through the third throttle hole and the fourth throttle hole is changed, which is used as a feedback signal to adjust the spool position of the second variable control valve 300, control the spool movement of the first variable control valve 200, make the distribution flow q1 of the right walking motor 602 smaller than the distribution flow q2 of the left walking motor 502, make the speed of the right walking motor 602 lower than the speed of the left walking motor 502, and the hydraulic walking system steers to the right.

[0062] When the hydraulic walking system is switched from straight walking to right steering, the third throttle hole throttling area A3 is smaller than the fourth throttle hole throttling area A4, the back pressure of the hydraulic oil flowing through the third throttle hole and the fourth throttle hole is changed, which is used as a feedback signal to adjust the spool position of the second variable control valve 300, control the spool movement of the first variable control valve 200, make the distribution flow q1 of the right walking motor 602 smaller than the distribution flow q2 of the left walking motor 502, make the speed of the right walking motor 602 lower than the speed of the left walking motor 502, and the hydraulic walking system steers to the right. Figure 3 , Figure 5As shown, the hydraulic walking system switches from the ideal state of straight walking to the right turning state, at this time the current of the electric proportional pressure reducing valve 800 is reduced, the pilot pressure after the pressure reducing valve is reduced The spool of the self-feedback control valve 400 moves to the left, at this time the throttling area A3 of the third throttling hole is reduced and the throttling area A4 of the fourth throttling hole is increased, at the moment of right turning switching, the flow rates q3 and q4 are the same, but because A3 is reduced and A4 is increased, the back pressure P3 generated after throttling through the third throttling hole is greater than the back pressure P4 generated after throttling through the fourth throttling hole, at this time the first force F1 of the second variable control valve 300 is less than the second force F2, at this time the oil circuit schematic is as shown, Figure 5 At this time, the first throttling area A1 of the first throttling hole is reduced and the throttling area A2 of the second throttling hole is increased, at this time the flow rate q1 flowing into the first oil port of the right walking motor 602 through A1 is reduced and the flow rate q2 flowing into the first oil port of the left walking motor 502 through A2 is increased, at this time the speed of the right walking motor 602 is reduced and the speed of the left walking motor 502 is increased, the hydraulic walking system starts to turn to the right. Further, because q1 is reduced and q2 is increased, at this time the back pressure P3 generated after throttling through the third throttling hole is reduced and the back pressure P4 generated after throttling through the fourth throttling hole is increased, until P3 and P4 are equal, at this time the spool position of the second variable control valve 300 returns to the neutral state, the spool of the first variable control valve 200 stops moving to the left, and q1 and q2 stop changing.

[0063] Continuing to refer to Figures 1 to 5 As shown, on the basis of the above, the left walking module 500 includes a left motor driven wheel 504 and a first speed sensor 505, the left motor driven wheel 504 is connected with the first speed sensor 505, the right walking module 600 includes a right walking driven wheel 604 and a second speed sensor 605, the right walking driven wheel 604 is connected with the second speed sensor 605, based on the ratio of the speed value detected by the first speed sensor 505 and the speed value detected by the second speed sensor 605, the control current of the electric proportional pressure reducing valve 800 is adjusted, the size of the pilot oil entering the self-feedback control valve 400 is adjusted to compensate the speed of the left walking motor 502 and the right walking motor 602, so as to control the movement of the spool of the self-feedback control valve 400.

[0064] Specifically, when the ratio of the rotational speed value detected by the first rotational speed sensor 505 to the rotational speed value detected by the second rotational speed sensor 605 is greater than the theoretical value, the control current of the electric proportional pressure reducing valve 800 is increased, at this time, the spool of the self-feedback control valve 400 moves, the throttle hole throttling area A3 of the third throttle hole is increased, and the throttle hole throttling area A4 of the fourth throttle hole is decreased, at this time, the back pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole is smaller than the back pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole, at this time, the first force of the spool of the second variable control valve 300 is greater than the second force, at this time, the spool of the second variable control valve 300 moves, so that the spool of the first variable control valve 200 moves, the throttle hole throttling area A1 of the first throttle hole is increased, and the throttle hole throttling area A2 of the second throttle hole is decreased, at this time, the flow rate q1 of the hydraulic oil output by the main pump 100 before the motor is increased after the hydraulic oil output by the main pump 100 passes through the first throttle hole, and the flow rate q2 of the hydraulic oil output by the main pump 100 before the motor is decreased after the hydraulic oil output by the main pump 100 passes through the second throttle hole, so that the rotational speed of the left traveling motor 502 is reduced, and the rotational speed of the right traveling motor 602 is increased, at this time, the ratio of the rotational speed value detected by the first rotational speed sensor 505 to the rotational speed value detected by the second rotational speed sensor 605 is reduced, until the ratio is equal to the theoretical value, at this time, the spool of the second variable control valve 300 returns to the neutral position, and the spool of the first variable control valve 200 stops moving.

[0065] When the ratio of the rotational speed value detected by the first rotational speed sensor 505 to the rotational speed value detected by the second rotational speed sensor 605 is less than the theoretical value, the control current of the electric proportional pressure reducing valve 800 is decreased, at this time, the spool of the self-feedback control valve 400 moves, the throttle hole throttling area A3 of the third throttle hole is decreased, and the throttle hole throttling area A4 of the fourth throttle hole is increased, at this time, the back pressure P3 generated after the low-pressure side hydraulic oil of the motor passes through the third throttle hole is greater than the back pressure P4 generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole, at this time, the first force of the spool of the second variable control valve 300 is less than the second force, at this time, the spool of the second variable control valve 300 moves, so that the spool of the first variable control valve 200 moves, the throttle hole throttling area A1 of the first throttle hole is decreased, and the throttle hole throttling area A2 of the second throttle hole is increased, at this time, the flow rate q1 of the hydraulic oil output by the main pump 100 before the motor is decreased after the hydraulic oil output by the main pump 100 passes through the first throttle hole, and the flow rate q2 of the hydraulic oil output by the main pump 100 before the motor is increased after the hydraulic oil output by the main pump 100 passes through the second throttle hole, so that the rotational speed of the left traveling motor 502 is increased, and the rotational speed of the right traveling motor 602 is reduced, at this time, the ratio of the rotational speed value detected by the first rotational speed sensor 505 to the rotational speed value detected by the second rotational speed sensor 605 is increased, until the ratio is equal to the theoretical value, at this time, the spool of the second variable control valve 300 returns to the neutral position, and the spool of the first variable control valve 200 stops moving.

[0066] It should also be noted that when operating in muddy walking conditions, there is a situation where the driving wheel slips. The speed r1 of the left motor driven wheel 504 and the speed r2 of the right walking driven wheel 604 in the hydraulic walking system are inconsistent with the driving wheel speed. At this time, the hydraulic walking system deviates. When it is detected that r1:r2 is different from the theoretical value of the driving wheel, the output compensation current △Ic is used to compensate the hydraulic walking system.

[0067] Specifically, when r1:r2 is greater than the theoretical value of the driving wheel, it is necessary to reduce the speed of the left driving wheel and increase the speed of the right driving wheel. At this time, a compensation current △Ic is issued, and the actual control current is Ic+△Ic. At this time, the current of the electric proportional pressure reducing valve increases, and the pilot pressure Ps after the electric proportional pressure reducing valve increases. The valve core of the self-feedback control valve 400 moves to the right. At this time, the throttling area A3 of the throttling hole of the third throttle increases, and the throttling area A4 of the throttling hole of the fourth throttle hole decreases. Because A3 increases and A4 decreases, the return oil back pressure P3 generated after throttling through the third throttle hole is less than the return oil back pressure P4 generated after throttling through the fourth throttle hole. At this time, the first force F1 of the second variable control valve 300 is greater than the second force F2. At this time, the oil circuit principle diagram is as follows: Figure 5 As shown, at this time, the valve core of the first variable control valve 200 moves to the right, the throttling area A1 of the first throttling hole becomes larger, and the throttling area A2 of the second throttling hole becomes smaller. At this time, the flow q2 flowing into the first oil port of the left travel motor 502 through A2 becomes smaller, and the flow q1 flowing into the first oil port of the right travel motor 602 through A1 becomes larger. At this time, the speed of the left travel motor 502 becomes smaller, and the speed of the right travel motor 602 becomes larger, r1:r2 becomes smaller, until r1:r2 are equal to the theoretical value, and △Ic becomes 0.

[0068] Specifically, when r1:r2 is less than the theoretical value of the driving wheel, it is necessary to increase the speed of the left driving wheel and reduce the speed of the right driving wheel. At this time, a compensation current △Ic is issued. At this time, the actual control current is Ic-△Ic. At this time, the current of the electric proportional pressure reducing valve decreases, and the pilot pressure Ps after the electric proportional pressure reducing valve decreases. The valve core of the self-feedback control valve 400 moves to the left. At this time, the throttling area A3 of the throttling hole of the third throttle is reduced, and the throttling area A4 of the throttling hole of the fourth throttle is increased. However, due to the decrease in A3 and the increase in A4, the return oil back pressure P3 generated after throttling through the third throttle hole is greater than the return oil back pressure P4 generated after throttling through the fourth throttle hole. At this time, the first force F1 of the second variable control valve 300 is less than the second force F2. At this time, the oil circuit principle diagram is as follows: Figure 4As shown, at this time, the first variable control valve 200 moves left, the throttle hole throttling area A1 of the first throttle hole becomes smaller, the throttle hole throttling area A2 of the second throttle hole becomes larger, at this time, the flow q1 flowing into the first oil port of the right walking motor 602 through A1 becomes smaller, the flow q2 flowing into the first oil port of the left walking motor 502 through A2 becomes larger, at this time, the rotating speed of the left walking motor 502 becomes larger, the rotating speed of the right walking motor 602 becomes smaller, r1:r2 becomes larger, until r1:r2 is equal to the theoretical value, ΔIc becomes 0.

[0069] In addition, it should be noted that when the hydraulic walking system does not have an electric proportional pressure reducing valve or a pilot pump, a certain pressure of hydraulic oil required for variable can be obtained by connecting an external oil source, i.e., an external control pilot oil.

[0070] Continuing to refer to Figures 1 to 5 As shown, on the basis of the above, the hydraulic walking system further comprises a selection check valve 103, and the main pump 100 is connected with the second variable control valve 300 and the variable piston 700 through the selection check valve 103.

[0071] The selection check valve 103 can compare the hydraulic oil pressure of the pilot pump and the main pump 100, automatically select the oil source with high pressure, drive the variable valve core to be variable, and avoid the problem that the system main pump 100 pressure is too low and cannot push the controller valve core to be variable.

[0072] The variable piston 700 is a piston force surface through which the hydraulic oil generates an axial force on the valve core, and then drives the first variable control valve 200 to move axially through the feedback rod, so as to control the flow distribution ratio.

[0073] The embodiment of the present application further provides a hydraulic walking vehicle, and the hydraulic walking vehicle comprises the hydraulic walking system of any one of the embodiments of the present application.

[0074] The hydraulic walking system provided by the embodiment of the present application comprises a main pump control module, a first variable control valve, a second variable control valve, a self-feedback control valve, a left walking module and a right walking module. The main pump control module comprises a main pump. The main pump is connected with a first oil port of the right walking module through a first throttle hole of the first variable control valve, and is connected with a first oil port of the left walking module through a second throttle hole of the first variable control valve. The flow of the hydraulic oil output by the main pump after passing through the first throttle hole and the second throttle hole is controlled by adjusting the throttle area of the first throttle hole and the throttle area of the second throttle hole. The second oil port of the left walking module is connected with a fourth throttle hole of the self-feedback control valve, and the second oil port of the right walking module is connected with a third throttle hole of the self-feedback control valve. The self-feedback control valve is connected with the second variable control valve. The back pressure of the hydraulic oil on the low pressure side of the motor after passing through the third throttle hole and the fourth throttle hole is controlled by adjusting the throttle area of the third throttle hole and the throttle area of the fourth throttle hole. The position of the valve core of the second variable control valve is adjusted to maintain the back flow of the hydraulic oil on the low pressure side at a theoretical value after the hydraulic oil pushes the motor to work. The second variable control valve is connected with the main pump through a variable piston. The present application can solve the problem of vehicle deviation caused by the deviation of the actual two walking motor speeds of the walking system due to the change of the volume rate or the single wheel slip, and realize self-feedback adjustment of the flow distribution, so that the control is more accurate and the walking deviation is effectively avoided.

[0075] It should be understood that the various forms of flow shown above can be used to reorder, add or delete steps. For example, the steps described in the present application can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions of the present application can be achieved, and the present application is not limited herein.

[0076] The above detailed description does not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent replacement and improvement within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A hydraulic travel system, characterized in that, The left walking module comprises a left walking inlet valve block, a left walking motor, and a left walking return valve block, the main pump output hydraulic oil is split to the left walking motor after passing through the second throttle hole, and the low-pressure side return oil of the left walking motor after the hydraulic oil drives the left walking motor to work flows into the fourth throttle hole of the self-feedback control valve.

2. The hydraulic travel system of claim 1, wherein, The right walking module comprises a right walking inlet valve block, a right walking motor, and a right walking return valve block, the main pump output hydraulic oil is split to the right walking motor after passing through the first throttle hole, and the low-pressure side return oil of the right walking motor after the hydraulic oil drives the right walking motor to work flows into the third throttle hole of the self-feedback control valve. The right walking module comprises a right walking inlet valve block, a right walking motor, and a right walking return valve block, the main pump output hydraulic oil is split to the right walking motor after passing through the first throttle hole, and the low-pressure side return oil of the right walking motor after the hydraulic oil drives the right walking motor to work flows into the third throttle hole of the self-feedback control valve.

3. The hydraulic travel system of claim 1, wherein, When walking in a straight line, the self-feedback control valve core position is adjusted so that the orifice throttling area of the third orifice and the orifice throttling area of the fourth orifice are the same, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the first orifice and the second orifice and then flows through the third orifice and the fourth orifice is controlled to be the same, which is used as a feedback signal of the self-feedback control valve, the second variable control valve core position is adjusted to adjust the oil way logic of the first variable control valve, and then the first variable control valve core position is adjusted to control the flow distribution of the hydraulic oil into the first oil port of the left motor and the first oil port of the right motor, so that the back flow of the hydraulic oil on the low pressure side of the motor after the hydraulic oil pushes the motor to work is maintained at a flow theoretical value, and the actual working speed of the motors on both sides is the same.

4. The hydraulic travel system of claim 1, wherein, When the high pressure oil port pressure of the right walking motor is less than the high pressure oil port pressure of the left walking motor, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third orifice is greater than the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth orifice, and then the first force of the second variable control valve core is less than the second force; The first stress = the back pressure of the oil return generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole The second variable control valve spool stress cross-sectional area The second force borne by the motor low-pressure side hydraulic oil after throttling through the third throttle hole to generate back oil pressure The second variable control valve spool force cross-sectional area.

5. The hydraulic travel system of claim 4, wherein, When the first force of the second variable control valve core is less than the second force, the first variable control valve is adjusted to make the orifice throttling area of the first orifice smaller and the orifice throttling area of the second orifice larger, the flow of the hydraulic oil output by the main pump before being distributed to the motors becomes smaller after flowing through the first orifice, the flow of the hydraulic oil output by the main pump before being distributed to the motors becomes larger after flowing through the second orifice, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third orifice becomes smaller, and the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth orifice becomes larger, until the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third orifice is equal to the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth orifice.

6. The hydraulic travel system of claim 1, wherein, When the high pressure oil port pressure of the right walking motor is greater than the high pressure oil port pressure of the left walking motor, the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the third orifice is less than the back pressure of the hydraulic oil on the low pressure side of the motor after the hydraulic oil flows through the fourth orifice, and then the first force of the second variable control valve core is greater than the second force; The first stress = the back pressure of the oil return generated after the low-pressure side hydraulic oil of the motor passes through the fourth throttle hole The second variable control valve spool stress cross-sectional area The second force borne by the motor low-pressure side hydraulic oil after throttling through the third throttle hole to generate back oil pressure The second variable control valve spool force cross-sectional area.

7. The hydraulic travel system of claim 6, wherein, When the first force of the second variable control valve is greater than the second force, the first variable control valve is adjusted to move, so that the throttle hole area of the first throttle hole becomes larger, the throttle hole area of the second throttle hole becomes smaller, the flow of the main pump output hydraulic oil before the motor after passing through the first throttle hole becomes larger, the flow of the main pump output hydraulic oil before the motor after passing through the second throttle hole becomes smaller, the back pressure generated by the low pressure side hydraulic oil of the motor after passing through the third throttle hole becomes larger, the back pressure generated by the low pressure side hydraulic oil of the motor after passing through the fourth throttle hole becomes smaller, until the back pressure generated by the low pressure side hydraulic oil of the motor after passing through the third throttle hole is equal to the back pressure generated by the low pressure side hydraulic oil of the motor after passing through the fourth throttle hole.

8. The hydraulic walking system of claim 1, wherein, The hydraulic walking system further comprises a pilot pump and an electric proportional pressure reducing valve, the main pump is connected with the pilot pump, the pilot pump is connected with the electric proportional pressure reducing valve, and the electric proportional pressure reducing valve is connected with the self-feedback control valve.

9. The hydraulic walking system of claim 1, wherein, The left walking module comprises a left motor driven wheel and a first rotation speed sensor, the left motor driven wheel is connected with the first rotation speed sensor, the right walking module comprises a right motor driven wheel and a second rotation speed sensor, the right motor driven wheel is connected with the second rotation speed sensor, and the electric proportional pressure reducing valve control current is adjusted based on the ratio of the rotation speed value detected by the first rotation speed sensor and the rotation speed value detected by the second rotation speed sensor, so as to control the movement of the valve core of the self-feedback control valve.

10. A hydraulic walk behind vehicle characterized by, The hydraulic walking vehicle comprises the hydraulic walking system according to any one of claims 1-9.

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