Wheel-crawler dual-purpose transport vehicle and walking hydraulic system thereof

Abstract

The invention belongs to the field of transport vehicles, and discloses a wheel-track dual-purpose transport vehicle and a walking hydraulic system thereof, the walking hydraulic system comprises a hydraulic pump set, and the hydraulic pump set comprises a left pump and a right pump which are mutually independent; the wheel type running driving motor comprises a left wheel side motor driven by a left pump and a right wheel side motor driven by a right pump, and the left wheel side motor and the right wheel side motor are arranged at the two ends of a front axle and / or the two ends of a rear axle of the wheel-track dual-purpose transport vehicle respectively. The wheel-track dual-purpose transport vehicle can adapt to material transportation in a multi-working-condition environment, solves the problem of differential speed between turning wheels of the vehicle, ensures that normal use of the vehicle is not affected by slipping of tires on one side, also solves the problem that track steering cannot be effectively controlled, and also avoids the situation that when wheel type driving is switched, a motor speed reducer downwards swings, and the vehicle is damaged. Therefore, the problems that the pipeline and the motor are damaged easily due to insufficient ground clearance of the pipeline and the motor are solved, and the safety and the operation convenience of the vehicle are improved.

Description

Technical Field

[0001] This application belongs to the field of transport vehicles, specifically, it relates to a wheeled and tracked dual-purpose transport vehicle and its hydraulic system for travel. Background Technology

[0002] In the construction of power grids and mobile tower foundations, construction is often carried out in various terrains such as mountains, paddy fields, swamps, and river beaches. The transportation of construction materials has always been a problem for construction workers. Usually, multiple transfers are required before the materials are transported to the construction site by manpower or small machinery. Therefore, there is an urgent need for transportation equipment that can be transported at high speed on paved roads, can travel in paddy fields and swamps with extremely low ground pressure, and has high off-road climbing performance.

[0003] To address this, integrated wheel-track hybrid technology has emerged, enabling vehicles capable of switching between wheeled and tracked driving modes (i.e., dual-purpose wheel-track transport vehicles). These vehicles combine the speed advantages of wheeled vehicles with the maneuverability of tracked vehicles on complex terrain, making them particularly suitable for field operations in challenging environments. However, in actual operation, the hydraulic lines and motors of the chassis of dual-purpose wheel-track transport vehicles are prone to wear and damage, and the steering control is relatively poor, easily leading to slippage and other issues. Summary of the Invention

[0004] To overcome at least one of the aforementioned technical deficiencies, this application provides a wheel-track dual-purpose transport vehicle and its driving hydraulic system to adapt to material transportation in various working conditions and improve the safety, reliability, and ease of operation of the vehicle.

[0005] To achieve the above objectives, this application provides a walking hydraulic system for a wheeled and tracked dual-purpose transport vehicle, the walking hydraulic system comprising: The hydraulic pump unit consists of two independent left and right pumps; The wheel-type driving motor includes a left wheel-side motor driven by the left pump and a right wheel-side motor driven by the right pump, wherein the left wheel-side motor and the right wheel-side motor are respectively arranged at both ends of the front axle and / or both ends of the rear axle of the wheel-tracked transport vehicle.

[0006] In some embodiments, the walking hydraulic system includes: The track drive motor includes a left track motor driven by the left pump and a right track motor driven by the right pump; A switching valve assembly is used to switch the control of the left pump to supply oil to the left wheel-side motor or the left track motor, and to switch the control of the right pump to supply oil to the right wheel-side motor or the right track motor.

[0007] In some embodiments, the switching valve assembly includes: A cartridge valve assembly includes at least one cartridge valve disposed at each of the two ends of the left wheel-side motor, the right wheel-side motor, the left track motor, and the right track motor. An electromagnetic pilot valve is provided, wherein the first working port of the electromagnetic pilot valve is pilot-connected to the control chamber of the cartridge valve located at both ends of the oil ports of the left wheel-side motor and the right wheel-side motor, and the second working port is pilot-connected to the control chamber of the cartridge valve located at both ends of the oil ports of the left track motor and the right track motor.

[0008] In some embodiments, the switching valve assembly includes: The first shuttle valve is hydraulically connected to the two oil ports of the left pump at both ends; The second shuttle valve is hydraulically connected to the two oil ports of the right pump at both ends; The third shuttle valve is hydraulically connected at both ends to the oil outlet of the first shuttle valve and the oil outlet of the second shuttle valve, respectively, and the oil outlet of the third shuttle valve is hydraulically connected to the oil inlet of the electromagnetic pilot valve.

[0009] In some embodiments, the walking hydraulic system includes: The electromagnetic switching valve is used to control the on / off connection between the first oil port and the second oil port of the left wheel-side motor and the right wheel-side motor, respectively.

[0010] In some embodiments, the walking hydraulic system includes: A front and rear axle swing hydraulic system includes a front axle swing cylinder and a rear axle swing cylinder respectively connected to the front axle and the rear axle and used to drive the tracks to be suspended. A steering control system includes a steering cylinder for steering the front axle or the rear axle, which serves as a steering bridge.

[0011] In some embodiments, the walking hydraulic system includes a controller configured to: In response to the wheel drive switching signal, the front axle swing cylinder and the rear axle swing cylinder are controlled to suspend the track. Control the switching valve group to control the left pump to supply oil to the left wheel motor, and control the right pump to supply oil to the right wheel motor.

[0012] In some implementations, the controller is configured to: Confirm that the steering cylinder has started operating; Determine that the working oil circuit pressure difference between the left wheel-side motor and the right wheel-side motor reaches the set pressure difference; Control the electromagnetic switching valve to connect the first oil port of the left wheel-side motor to the first oil port of the right wheel-side motor, and to connect the second oil port of the left wheel-side motor to the second oil port of the right wheel-side motor.

[0013] In some implementations, the controller is configured to: It has been determined that the steering wheel is slipping. The electromagnetic switching valve is controlled to disconnect the first oil port connecting the left wheel-side motor and the first oil port connecting the right wheel-side motor, and to disconnect the second oil port connecting the left wheel-side motor and the second oil port connecting the right wheel-side motor.

[0014] In addition, this application also provides a wheeled and tracked dual-purpose transport vehicle, which includes the aforementioned walking hydraulic system of the wheeled and tracked dual-purpose transport vehicle.

[0015] In the wheel-track dual-purpose transport vehicle and its hydraulic system of this application, a dual-pump dual-motor configuration is adopted in the hydraulic structure layout. This abandons the traditional central drive configuration of the drive axle or the single-pump dual-motor configuration. The wheel-side drive motors are arranged at both ends of the front-drive or rear-drive vehicle instead of in the center of the axle. This avoids the problem of insufficient ground clearance of the pipelines and motors when switching to wheel drive due to the motor reducer swinging downwards, which can easily damage the pipelines and motors. Moreover, each wheel-side motor is driven by the hydraulic pump on the corresponding side, avoiding the risk of bottoming out and wear caused by the long hydraulic pipeline layout, thus improving the safety and reliability of vehicle driving. Furthermore, the independent control of the dual motors by the dual pumps further enhances the convenience of operation and control.

[0016] Other features and advantages of the embodiments of this application will be described in detail in the following detailed description section. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the embodiments of this application and form part of the specification. They are used together with the following detailed description to explain the embodiments of this application, but do not constitute a limitation on the embodiments of this application. In the drawings: Figure 1 This is a structural schematic diagram of a wheeled and tracked dual-purpose transport vehicle according to a specific embodiment of this application; Figure 2 for Figure 1 A schematic diagram of the steering axle in the diagram; Figure 3 This is a hydraulic schematic diagram of the walking hydraulic system of a wheeled and tracked dual-purpose transport vehicle according to a specific embodiment of this application; Figure 4 This is a schematic diagram of the control process of the controller in the walking hydraulic system of a wheeled and tracked transport vehicle according to a specific embodiment of this application.

[0018] Explanation of reference numerals in the attached figures Detailed Implementation

[0019] The specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this application.

[0020] The following description, with reference to the accompanying drawings, describes a wheeled and tracked transport vehicle and its hydraulic system for travel according to this application.

[0021] This application discloses a novel wheeled and tracked dual-purpose transport vehicle and its hydraulic system for travel. For example... Figure 1 , Figure 3 As shown, a specific embodiment of the walking hydraulic system 6 includes: The hydraulic pump assembly includes two independent left pump 61 and right pump 62; The wheel drive motor 66 includes a left wheel-side motor driven by a left pump 61 and a right wheel-side motor driven by a right pump 62. The left wheel-side motor and the right wheel-side motor are respectively arranged at both ends of the front axle and / or both ends of the rear axle of the wheel-tracked transport vehicle.

[0022] In this application, the wheel-track dual-purpose transport vehicle and its hydraulic system adopt a dual-pump, dual-motor configuration in the hydraulic structure layout. The wheel-side drive motors are arranged at both ends of the front-drive or rear-drive system rather than in the center of the axle. This avoids the problem of insufficient ground clearance of the pipelines and motors when switching to wheel drive due to the motor reducer swinging downwards, which could easily damage the pipelines and motors, thus improving the safety and reliability of the vehicle.

[0023] Specifically, many existing wheel-tracked dual-purpose transport vehicles employ an axle-drive central transmission scheme. This involves transmitting power to the center of the drive axle via a hydraulic motor and reducer, with the axle housing carrying a differential, and using mechanical transmission to achieve differential turning. However, during wheel-track switching, because the drive axle is lifted by a swing frame, the motor and reducer in the axle-drive central transmission scheme are connected to the drive axle from the center along the vehicle's axis. When switching to wheel drive, the motor and reducer swing downwards, resulting in insufficient ground clearance for the pipelines and motors, which can easily damage them. This application addresses this issue with a dual-pump, dual-motor configuration. The wheel-side motors are mounted at the ends of the axle, and each wheel-side motor is driven by a hydraulic pump on the corresponding side, avoiding the risk of bottoming out and wear caused by long hydraulic pipelines.

[0024] Based on the dual-pump, dual-motor configuration, the walking hydraulic system 6 in this embodiment also includes: The track drive motor 65 includes a left track motor driven by a left pump 61 and a right track motor driven by a right pump 62. The switching valve assembly is used to switch the control of the left pump 61 to supply oil to the left wheel-side motor or the left track motor, and to switch the control of the right pump 62 to supply oil to the right wheel-side motor or the right track motor.

[0025] In this embodiment, a dual-pump, four-motor wheel-track drive scheme is formed by using two pumps corresponding to the wheel-side motor and the track motor respectively. This effectively reduces the complexity of the track's driving control scheme in a single-pump scheme. Based on the dual-pump, dual-motor scheme, the wheel-track driving can be quickly switched using a reversing valve assembly. Specifically, the left pump 61 can be switched to supply oil to either the left wheel-side motor or the left track motor, and the right pump 62 can be switched to supply oil to either the right wheel-side motor or the right track motor.

[0026] In existing technologies using a single-pump, dual-motor solution, track steering cannot be effectively controlled when switching to tracked travel. This embodiment, employing a dual-pump, four-motor system, allows for tracked travel and steering by separately controlling the speeds of the left and right track motors using conventional methods. This approach is convenient and reliable. When traveling on wheels, if... Figure 2 As shown, either the front axle or the rear axle can be used as a steering axle. The steering axle includes steering wheels 11 at both ends of the axle body 12. The steering wheel controls the extension and retraction of the steering cylinder 13, which in turn drives the steering wheels 11 to turn through the steering tie rod 14.

[0027] The switching valve assembly is used to control the pump on the left or right side to supply oil to the corresponding wheel-side motor or track motor. Therefore, a conventional switching valve can be used for the switching valve assembly. However, in this embodiment, the switching valve assembly specifically includes: The cartridge valve assembly 63 includes at least one cartridge valve disposed at each end of the oil port of the left wheel-side motor, the right wheel-side motor, the left track motor and the right track motor; The electromagnetic pilot valve 64 has its first working port pilot-connected to the control chamber of the cartridge valve located at both ends of the oil ports of the left wheel-side motor and the right wheel-side motor, and its second working port pilot-connected to the control chamber of the cartridge valve located at both ends of the oil ports of the left track motor and the right track motor.

[0028] When a wheeled-tracked transport vehicle is in motion, the pumping flow rate of each pump is relatively large. If a conventional switching valve is used for reversing, the large flow of oil will cause significant impact on the valve core and valve port. Therefore, a high-flow-rate reversing valve is required, which has higher specifications and cost. This implementation method adopts... Figure 3 The effective combination of the two-position four-way electromagnetic pilot valve 64 and multiple cartridge valves shown allows for the control of large-flow cartridge valves with small flow rates, reducing impact and enabling rapid and smooth switching between wheel and track. It also avoids the defect of uncontrollable steering when the track is driven.

[0029] When hydraulically controlling each cartridge valve, the high-pressure pilot hydraulic oil can come from the working oil circuit of the motor in operation. See also Figure 3 The switching valve assembly in this embodiment further includes: The first shuttle valve 67 is hydraulically connected to the two oil ports of the left pump 61 at both ends; The second shuttle valve is hydraulically connected to the two oil ports of the right pump 62 at both ends; The third shuttle valve 68 is hydraulically connected at both ends to the oil outlet of the first shuttle valve 67 and the oil outlet of the second shuttle valve, respectively. The oil outlet of the third shuttle valve 68 is hydraulically connected to the oil inlet of the electromagnetic pilot valve 64.

[0030] Regardless of whether any of the left or right pumps is started or any of the four motors is in operation, at least one pump's end port is supplied with high-pressure oil. This high-pressure oil is controlled by a series of checks via the first shuttle valve 67, the second shuttle valve, and the third shuttle valve 68 before entering the inlet of the solenoid pilot valve 64. The oil then selectively enters the first and second working ports of the solenoid pilot valve 64, acting as a high-pressure pilot oil to control the closure of the corresponding four cartridge valves. Alternatively, an accumulator can be used as the pilot oil, always hydraulically connected to the inlet of the solenoid pilot valve 64.

[0031] In existing single-pump dual-motor solutions, if one tire slips, the power output to the other tire will be ineffective, potentially causing the vehicle to malfunction. Therefore, the walking hydraulic system 6 in this embodiment may further include: The electromagnetic switching valve 69 is used to control the on / off connection between the first oil port and the second oil port of the left wheel side motor and the right wheel side motor, respectively.

[0032] At this point, the front axle acts as a steering axle, and the rear axle experiences inter-wheel differential speed during cornering. This application addresses this by adding an electromagnetic switching valve 69 between the two wheel-side motors in the hydraulic system. During normal driving, the electromagnetic switching valve 69 is controlled to connect the oil circuits of the left and right motors, achieving automatic load distribution. When tire slippage occurs, the electromagnetic switching valve 69 is controlled to cut off the oil circuit between the left and right motors, preventing the entire machine from failing to drive normally due to unilateral tire slippage.

[0033] Therefore, by adding an electromagnetic switching valve 69 and its connecting pipeline between the left and right motors, differential speed between wheels can be achieved when the wheel-side motor drives steering. At the same time, it can solve the problem of no driving power when a single wheel slips. This avoids the problem of ineffective control of track steering or complex algorithm control when switching to track driving in a single-pump dual-motor scheme for wheel-track dual-purpose transport vehicles.

[0034] See Figure 3 The illustrated walking hydraulic system 6 may also include: The front and rear axle swing hydraulic system includes a front axle swing cylinder 71 and a rear axle swing cylinder 72, which are respectively connected to the front axle and the rear axle and are used to drive the tracks to be suspended. The steering control system includes a steering cylinder 13 for driving the front axle or rear axle, which serves as a steering bridge, to steer.

[0035] Thus, the left and right pumps can be used not only to drive the vehicle's movement, but also to drive steering and front and rear axle sway, that is, to control steering and wheel-track switching. Figure 3 In this system, the directional valve 74 switches between the front and rear axle swing hydraulic system and the steering control system. When switching to the front and rear axle swing hydraulic system, the front axle swing cylinder 71 and the rear swing cylinder 72 are controlled to raise the front and rear axle swing frames, suspending the tracks and bringing the tires to the ground, thus switching to wheeled travel mode. Conversely, switching to wheeled travel mode switches to tracked travel mode. When switching to wheeled travel mode, the directional valve 74 is controlled again to activate the steering control system with steering cylinder 13. The operator can control the extension and retraction of steering cylinder 13 via the steering wheel, which in turn drives the steering wheel 11 to steer via steering tie rod 14. (See [reference]). Figure 2 .

[0036] In a structural layout employing a dual-pump, dual-motor configuration, and as... Figure 3 Based on the integrated hydraulic system layout shown, this application can simplify, automate, and ensure high safety in the switching control of the walking mode and steering of the wheel-tracked transport vehicle, and effectively cope with working conditions such as steering pressure difference and steering slippage.

[0037] In this embodiment, the walking hydraulic system 6 may include a controller, which is configured to: In response to the wheel drive switching signal, the front axle swing cylinder 71 and the rear axle swing cylinder 72 are controlled to suspend the tracks. Control the switching valve group to control the left pump 61 to supply oil to the left wheel-side motor, and control the right pump 62 to supply oil to the right wheel-side motor.

[0038] See Figure 4 When the operator or the system automatically provides a wheel drive switching signal, the controller receives the signal and immediately controls the reversing valve 74, the front axle swing cylinder 71, the rear swing cylinder 72, etc., to suspend the tracks and keep the tires on the ground, thus switching from tracked travel mode to wheeled travel mode, achieving wheel drive switching control. Then, the controller controls the solenoid pilot valve 64 to switch to wheeled operation, that is, controls the left pump 61 to supply oil to the left wheel-side motor and the right pump 62 to supply oil to the right wheel-side motor. The oil circuit of the wheel travel drive motor 66 is opened, the motor starts working, and drives the vehicle in wheeled travel, while the track travel drive motor 65 does not work. It can be seen that once a wheel-track switching signal is given, the controller can control the electrical signals of various valves and cylinders to achieve automated process control.

[0039] During wheeled travel, in turning situations, the controller can further be configured as follows: Confirm that steering cylinder 13 has started working; Ensure that the pressure difference in the working oil circuits of the left wheel-side motor and the right wheel-side motor reaches the set pressure difference. Control the solenoid switching valve 69 to connect the first oil port of the left wheel side motor to the first oil port of the right wheel side motor, and to connect the second oil port of the left wheel side motor to the second oil port of the right wheel side motor.

[0040] It can be seen that when a steering pressure difference occurs, that is, when an inner and outer pressure difference occurs, as long as the inner and outer pressure difference reaches the preset set pressure difference, the control electromagnetic switching valve 69 can be automatically triggered to make the left and right wheel side motors conduct to each other, thereby automatically splitting the load, realizing differential speed between wheels, and synchronizing the two tires.

[0041] During driving, if slippage occurs on one side, the controller can also be configured to: It has been determined that the steering wheel is slipping. The control solenoid switching valve 69 cuts off the first oil port connecting the left wheel side motor and the first oil port connecting the right wheel side motor, and cuts off the second oil port connecting the left wheel side motor and the second oil port connecting the right wheel side motor.

[0042] The occurrence of steering slippage can be determined manually, or by a combination of preset wheel speed sensors, lateral acceleration sensors, or yaw rate sensors. This is well known to those skilled in the art and will not be elaborated upon here.

[0043] Once it is determined that the steering is slipping, the electromagnetic switching valve 69 can be controlled immediately to cut off the connection between the left and right wheel motors. That is, the first oil port connecting the left wheel motor and the first oil port connecting the right wheel motor are cut off, as well as the second oil port connecting the left wheel motor and the second oil port connecting the right wheel motor are cut off. This will allow the slipping wheel to regain power and prevent the machine from being unable to drive normally due to the slipping of one side of the tire.

[0044] This application also discloses a wheeled-tracked dual-purpose transport vehicle, which includes the aforementioned hydraulic system 6 for the wheeled-tracked dual-purpose transport vehicle. See also Figure 1 The dual-purpose wheeled and tracked transport vehicle, in terms of its functional structure, may include a tracked chassis system 2 and its front and rear wheeled drive systems 1. A material transport platform 4 is mounted on top of the tracked chassis system 2. The control system 3 controls the power system 5 and the walking hydraulic system 6.

[0045] As described above, the wheel-track dual-purpose transport vehicle of this application can adapt to material transportation in multiple working conditions, solve the problem of differential speed between turning wheels, thereby improving vehicle safety, economy and construction transfer efficiency, and ensuring that the normal use of the vehicle is not affected by the slippage of one tire.

[0046] Specifically, the wheel-track dual-purpose transport vehicle of this application adopts a dual-pump dual-motor configuration, which avoids the problem in the prior art where wheel-track dual-purpose vehicles using a single pump dual motor cannot effectively control track steering (or use complex algorithm control) when switching to track driving. It also avoids the problem that when switching to wheel drive, the motor reducer swings downward, resulting in insufficient ground clearance of pipelines and motors, which can easily damage pipelines and motors.

[0047] This invention employs a dual-pump, four-motor wheel-track drive system, with two pumps corresponding to the dual motors of the wheel and track respectively. This effectively reduces the complexity of the track-based driving control scheme found in single-pump systems. During wheel-track driving, the hydraulic system typically operates at a high flow rate, and using a high-flow-rate switching valve results in significant impact. This application replaces this with a low-flow-rate-controlled high-flow-rate switching valve, reducing impact and enabling rapid and smooth wheel-track switching. Furthermore, the addition of a switching valve and its piping between the left and right motors allows for differential speed control between the wheels when the wheel-side motors are used for steering, while also resolving the issue of single-wheel slippage and lack of driving power.

[0048] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0049] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between components; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0050] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0051] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A hydraulic system for the movement of a wheeled and tracked dual-purpose transport vehicle, characterized in that, The walking hydraulic system (6) includes: The hydraulic pump assembly includes a left pump (61) and a right pump (62) that are independent of each other. The wheel drive motor (66) includes a left wheel-side motor driven by the left pump (61) and a right wheel-side motor driven by the right pump (62), the left wheel-side motor and the right wheel-side motor being respectively arranged at both ends of the front axle and / or both ends of the rear axle of the wheel-tracked transport vehicle.

2. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to claim 1, characterized in that, The walking hydraulic system (6) includes: The track drive motor (65) includes a left track motor driven by the left pump (61) and a right track motor driven by the right pump (62). A switching valve assembly is used to switch the control of the left pump (61) to supply oil to the left wheel-side motor or the left track motor, and to switch the control of the right pump (62) to supply oil to the right wheel-side motor or the right track motor.

3. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to claim 2, characterized in that, The switching valve group includes: The cartridge valve assembly (63) includes at least one cartridge valve with an oil port at each end of the left wheel-side motor, the right wheel-side motor, the left track motor and the right track motor; The electromagnetic pilot valve (64) has its first working port pilot-connected to the control chamber of the cartridge valve located at both ends of the oil ports of the left wheel-side motor and the right wheel-side motor, and its second working port pilot-connected to the control chamber of the cartridge valve located at both ends of the oil ports of the left track motor and the right track motor.

4. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to claim 3, characterized in that, The switching valve group includes: The first shuttle valve (67) is hydraulically connected to the two oil ports of the left pump (61) at both ends; The second shuttle valve is hydraulically connected at both ends to the oil ports at both ends of the right pump (62); The third shuttle valve (68) is hydraulically connected at both ends to the oil outlet of the first shuttle valve (67) and the oil outlet of the second shuttle valve, respectively. The oil outlet of the third shuttle valve (68) is hydraulically connected to the oil inlet of the electromagnetic pilot valve (64).

5. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to any one of claims 2 to 4, characterized in that, The walking hydraulic system (6) includes: The electromagnetic switching valve (69) is used to control the on / off connection between the first oil port and the second oil port of the left wheel-side motor and the right wheel-side motor, respectively.

6. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to claim 5, characterized in that, The walking hydraulic system (6) includes: The front and rear axle swing hydraulic system includes a front axle swing cylinder (71) and a rear axle swing cylinder (72) respectively connected to the front axle and the rear axle and used to drive the tracks to be suspended. The steering control system includes a steering cylinder (13) for steering the front axle or the rear axle, which serves as a steering bridge.

7. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to claim 6, characterized in that, The walking hydraulic system (6) includes a controller, which is configured to: In response to the wheel drive switching signal, the front axle swing cylinder (71) and the rear axle swing cylinder (72) are controlled to suspend the track. Control the switching valve group to control the left pump (61) to supply oil to the left wheel-side motor, and control the right pump (62) to supply oil to the right wheel-side motor.

8. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to claim 7, characterized in that, The controller is configured to: Determine that the steering cylinder (13) starts working; Determine that the working oil circuit pressure difference between the left wheel-side motor and the right wheel-side motor reaches the set pressure difference; Control the electromagnetic switching valve (69) to connect the first oil port of the left wheel-side motor to the first oil port of the right wheel-side motor, and to connect the second oil port of the left wheel-side motor to the second oil port of the right wheel-side motor.

9. The hydraulic system for the wheeled and tracked dual-purpose transport vehicle according to claim 7, characterized in that, The controller is configured to: It has been determined that the steering wheel is slipping. Control the electromagnetic switching valve (69) to cut off the connection between the first oil port of the left wheel-side motor and the first oil port of the right wheel-side motor, and to cut off the connection between the second oil port of the left wheel-side motor and the second oil port of the right wheel-side motor.

10. A wheeled and tracked dual-purpose transport vehicle, characterized in that, The wheeled and tracked dual-purpose transport vehicle includes the walking hydraulic system (6) of the wheeled and tracked dual-purpose transport vehicle according to any one of claims 1 to 9.

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