Extension method and system for driving chassis axle

Abstract

The invention provides an extension method and system for a driving chassis axle. The method comprises a normal extension mode, a resistance-meeting extension mode, a limit extension mode and a free extension mode. In the normal expansion mode process, when the pressure value of the expansion oil cylinder encounters obstacles and exceeds the set pressure of the system, the expansion oil cylinder is switched to the resistance expansion mode, after the expansion oil cylinder passes through the swing wheels, the pressure value is decreased, bridge expansion continues, and if the pressure value is not decreased, the expansion oil cylinder is switched to the limit expansion mode. The free expansion mode is that at least one wheel or axle is manually controlled by operating an equipment panel; the system comprises electromagnetic directional valves arranged on hydraulic pipelines of wheels and axles, corresponding balance valves and hydraulic locks, compensation valves are arranged between the electromagnetic directional valves and a main oil inlet pipeline, first overflow valves with the pressure value smaller than that of second overflow valves are arranged at the two ends of the electromagnetic directional valves at the extension bridge end, and graded protection is achieved. Through each single-control valve group and matched control logic, automatic de-trapping and successful bridge expansion in a limited area are realized.

Description

Technical Field

[0001] The invention relates to an expansion method for a traveling chassis axle, belonging to the technical field of aerial work platforms. Background Art

[0002] Aerial work platform is a common lifting tool used to lift workers to heights for maintenance and other work. It includes boom-type aerial work platforms and scissor-type aerial work platforms. The boom-type aerial work platform achieves stable bottom support through a stable chassis frame structure to ensure the safety of upper installation operations.

[0003] The chassis supports of existing boom-type aerial work platforms are usually of two types: mast-type and expanded bridge-type. The mast-type chassis support structure uses a vertically movable mast as the main support structure. The support process is cumbersome, and the stability is greatly affected by the strength of the ground. It causes great damage to the ground during road paving operations. The other wheel-type expanded bridge support structure, by expanding the axle at the bottom of the disc to the surrounding areas to raise the support reaction arm, improves the working range and stability of the upper body, and has been widely used in aerial operations.

[0004] However, when the working space is limited or the road conditions are poor, the conventional aerial work platform using the bridge expansion chassis cannot successfully expand the bridge, and can only use other methods or select other non-optimal positions to expand the bridge, which wastes time and affects work efficiency. Most of the existing aerial work platforms are sold in the form of leasing. The time cost for successful bridge expansion is extremely high. Therefore, in the actual application process, how to successfully expand the bridge in a limited working space is an urgent problem to be solved in order to reduce the time spent on the operation. Summary of the invention

[0005] Purpose of the invention: In view of the deficiencies in the prior art, the present invention provides a method and system for expanding a chassis axle. By setting each wheel and the expansion bridge to be controlled separately, a multi-degree-of-freedom bridge expansion operation is realized. Combined with an automatic escape method for obstructions encountered during the bridge expansion process and an extreme expansion method, rapid bridge expansion can be achieved, successful bridge expansion in a limited area, saving bridge expansion time and improving vehicle utilization.

[0006] Technical solution: A method for extending a traveling chassis axle, including a normal extension mode and an obstruction extension mode; The normal expansion mode is specifically: The vehicle stops after driving to the expansion area, and the operator starts the bridge expansion switch. After the controller receives the bridge expansion command, it expands the bridge. First, the wheel steering cylinder retracts and the wheel is turned to a position of 80°~90° with the expansion bridge. After the controller receives the information that the wheel steering is completed, it controls the expansion cylinder at the expansion bridge end to extend and push the expansion bridge to both sides with the hinge point of the expansion bridge and the frame as the center. The wheel moves until the expansion cylinder reaches the maximum stroke, and the bridge expansion is completed. The obstacle expansion mode is specifically: During the bridge expansion process in the normal expansion mode, when the wheel end encounters an obstacle that is difficult to cross during the bridge expansion process, according to the pressure signal detected by the pressure sensor installed in the expansion cylinder, when the pressure value of the expansion cylinder is greater than the system set pressure, it will enter the resistance expansion mode. The system set pressure is the theoretical working pressure calculated based on the thrust required for bridge expansion and the cylinder diameter of the expansion cylinder. The set value is 1.25~1.35 times the theoretical working pressure; The controller sends out instructions to control the wheel steering cylinder at the expansion bridge end that transmits the pressure signal change to rotate the wheel clockwise to the limit position, and then counterclockwise to the limit position, while the expansion cylinder continues to work; when the expansion cylinder pressure value is less than the system set pressure, the bridge continues to be expanded until the expansion cylinder reaches the maximum stroke and the bridge expansion is completed.

[0007] In the obstacle expansion mode, if the wheel fails to escape the obstacle after turning, it will enter the extreme expansion mode, specifically: When in the resistance expansion mode, after the wheel rotates clockwise to the limit position and then counterclockwise to the limit position, if the expansion cylinder pressure value is still greater than the system set pressure, it will enter the limit expansion mode; Stop the action of the expansion cylinder that transmits the pressure signal change, and other expansion cylinders expand the bridge normally to the maximum position to complete the bridge expansion operation.

[0008] It also includes a free control mode. After the operator starts the bridge expansion switch, if manual intervention is required, the operator can press the one-touch expansion button again to stop the current bridge expansion action. Activate at least one wheel or axle through the operation panel for individual control, adjust the wheel angle or extended axle rotation angle to a custom angle, the wheel angle custom adjustment range is from the minimum wheel steering angle to the maximum wheel steering angle of the current model, the extended axle angle custom adjustment range is from the minimum extended axle extension angle to the maximum extended axle extension angle of the current model, toggle the current angle expansion button to enter automatic expansion mode in the current state until the axle expansion is completed.

[0009] In the normal expansion mode, when the wheel steering angle is selected to be greater than or equal to 80° and less than 90°, it is a rapid bridge expansion. When the wheel steering angle reaches the set angle, the expansion bridge begins to expand, and the wheels continue to rotate until they are at 90° to the expansion bridge. During this period, the wheels move on the ground in a mixed form of sliding friction and rolling friction.

[0010] In the normal expansion mode, when the wheel steering angle is selected to be 90°, it is the tire protection and bridge expansion mode. When the wheel steering angle reaches the set angle of 90°, the expansion bridge begins to expand, and the wheel moves on the ground in the form of rolling friction.

[0011] A system for implementing a method for extending a traveling chassis axle comprises a vehicle frame, an extension axle hinged to the four corners of the vehicle frame, and wheels hinged to the ends of the extension axle, wherein the wheels are steered by a steering cylinder mounted on the extension axle, and the extension axle is extended and retracted by the extension cylinder, and is characterized in that: It also includes an electromagnetic reversing valve connected to each steering cylinder and expansion cylinder in a one-to-one correspondence, wherein the oil inlet and oil outlet of the electromagnetic reversing valve are respectively connected to the main oil inlet pipeline and the main oil return pipeline, a balancing valve is arranged on the pipeline between the steering cylinder and the corresponding electromagnetic reversing valve, and a hydraulic lock is arranged on the pipeline between the expansion cylinder and the corresponding electromagnetic reversing valve.

[0012] The present invention realizes individual control by setting valve groups corresponding to each steering wheel and the expansion bridge. In the case of obstacles and limited expansion space, the individual control has a higher degree of freedom and can realize various expansion bridge states without being restricted by the traditional left and right side associated hydraulic system. The wheels will generate opposite forces during the steering process. The balance valve has better load resistance and reduces the influence on the oil cylinder. The expansion bridge end uses a hydraulic lock to realize the positioning of the expansion bridge, thereby further realizing stable support after the expansion bridge.

[0013] A compensation valve is provided between the electromagnetic reversing valve and the main oil inlet pipeline. The compensation valves are connected through a compensation pipeline. A one-way valve is provided on the pipeline between the compensation valve and the compensation pipeline. The compensation pipeline is connected to the main oil return pipeline through an overflow port.

[0014] The compensation valve adjusts the oil flow rate rather than the oil pressure according to the opening ratio of the electromagnetic reversing valve. This is because during the wheel steering process, when a single wheel encounters resistance and the pressure increases, other wheels are unobstructed and the pressure is smaller. Controlling the oil inlet of the compensation valve by pressure will not give the blocked wheel enough power to get out of trouble. Controlling the oil flow rate by the opening size of the electromagnetic reversing valve can provide sufficient power support for the corresponding cylinder.

[0015] It also includes a first overflow valve connected to a pipeline connected to the main oil return pipeline and a solenoid reversing valve corresponding to the expansion cylinder at both ends and connected to the hydraulic lock.

[0016] By setting the first overflow valve, the protection of the hydraulic system of the expansion bridge is achieved.

[0017] A second overflow valve is provided between the main oil inlet pipeline and the main oil return pipeline, with two ends respectively connected to the main oil inlet pipeline and the main oil return pipeline. The set pressure value of the second overflow valve is higher than the pressure value set by the first overflow valve.

[0018] The pressure value of the second relief valve is set higher than that of the first relief valve. The purpose of the second relief valve is to protect the hydraulic system of the entire vehicle. When the pressure value in the pipeline is too large, the oil can return to the fuel tank from the main return oil pipeline. The pressure value is set greater than the first relief valve to ensure that when the wheel encounters an obstruction, the pressure value in the pipeline increases and it can work normally. The expansion axle is under a relatively low pressure state for pressure relief protection, thereby achieving effective protection of the expansion axle.

[0019] A wheel angle sensor is provided at the hinge point between the wheel and the expansion bridge, an expansion angle sensor is provided at the hinge point between the expansion bridge and the frame, and an oil pressure sensor is provided on each of the expansion cylinders.

[0020] By setting up wheel angle sensors, expansion angle sensors and oil pressure sensors, the steering angle, expansion angle and oil pressure values ​​are monitored in real time and transmitted to the vehicle control system. The system switches to different working conditions based on the data combination, ultimately achieving maximum bridge expansion.

[0021] Beneficial effects: The present invention realizes individual control by setting valve groups corresponding to each steering wheel and expansion bridge. In the case of obstacles and limited expansion space, the individual control has a higher degree of freedom and can realize multiple bridge expansion states without being restricted by the traditional left and right side associated hydraulic system. At the same time, in the present invention, when encountering obstacles during the bridge crossing process, it can automatically move to get out of trouble. When it is impossible to get out of trouble, it can also switch to the extreme expansion mode to maximize the bridge expansion and perform limited loading operations. Compared with traditional aerial work platforms, it has higher applicability and can also achieve bridge expansion in limited space, greatly improving vehicle utilization and saving bridge expansion time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0023] Figure 1 It is a structural diagram of the bottom vehicle of the present invention.

[0024] Figure 2This is a schematic diagram of the hydraulic control principle of the steering cylinder and the extension cylinder of the present invention.

[0025] Figure 3 It is a schematic diagram of the bridge expansion method in the prior art.

[0026] Figure 4 This is a schematic diagram of obstacles existing in the bridge expansion path of the present invention.

[0027] Figure 5 Schematic diagram of the incompletely extended state of the present invention, in which ①, ②, ③, and ④ respectively represent wheels connected to the running chassis axle that can realize independent rotation; A, B, and C respectively represent the extended positions that each wheel can reach under the incompletely extended working condition, wherein A is the non-extended position and C is the maximum extended position.

[0028] Figure 6 This is a schematic diagram of the non-complete expansion state of one side of the present invention.

[0029] Figure 7 This is a schematic diagram of the structure of the control device panel of the present invention. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] In the description of the present invention, it is necessary to understand that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0032] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0033] like Figure 3 The figure shows the expansion method of the prior art wheeled expansion bridge. First, the wheels are turned to a perpendicular state to the expansion bridge, and then the expansion bridge is driven to move to complete the expansion. The method is single and the expansion process cannot be manually intervened, but this solution ignores the influence of the road surface conditions. When the road surface is in an uneven state, the resistance during bridge expansion is complex and changeable. When the wheels are fixed perpendicular to the axle, the resistance of bridge expansion is affected by the road surface and is not necessarily the smallest. When the road surface condition is bad and the potholes are serious, the bridge expansion resistance may be greater than the maximum power of the bridge expansion, resulting in failure of bridge expansion.

[0034] After the expansion bridge is expanded, there is only one position condition, and the final position of each axle is fixed. The influence of space and ground conditions is ignored. When the space is small or the ground at the final target position sinks, the bridge may not be expanded to the right position, or it may become unsuitable for work.

[0035] like Figures 4 to 7 As shown, a method for extending a traveling chassis axle includes a normal extension mode and an obstacle extension mode; The normal expansion mode is specifically: After the vehicle reaches the expansion area, it stops. The operator starts the bridge expansion switch. After the controller receives the bridge expansion command, it expands the bridge. First, the steering cylinder 4 of the wheel 3 retracts and the wheel 3 is turned to a position of 80°~90° with the expansion bridge 2. After the controller receives the information that the wheel 3 has been turned, it controls the expansion cylinder 5 at the end of the expansion bridge 2 to extend and push the expansion bridge 2 to both sides with the hinge point of the expansion bridge 2 and the frame 1 as the center. The wheel 3 moves until the expansion cylinder 5 reaches the maximum stroke, and the bridge expansion is completed. The obstacle expansion mode is specifically: During the bridge expansion process in the normal expansion mode, when the wheel 3 ends encounter an obstacle that is difficult to cross during the bridge expansion process, according to the pressure signal detected by the pressure sensor installed in the expansion cylinder 5, when the pressure value of the expansion cylinder is greater than the system set pressure, it will enter the resistance expansion mode. The system set pressure, the setting logic is to calculate the thrust required for bridge expansion based on the structure, and the theoretical working pressure is calculated in combination with the cylinder diameter of the expansion cylinder. The setting value is 1.25~1.35 times the theoretical working pressure; the specific setting value in this embodiment is 1.3 times the theoretical working pressure; The controller sends out instructions to control the steering cylinder 4 of the wheel 3 at the end of the expansion bridge 2 that transmits the change of the pressure signal to rotate the wheel 3 in the clockwise direction to the limit position, and then rotate it counterclockwise to the limit position, while the expansion cylinder 5 continues to work; when the pressure value of the expansion cylinder is less than the system set pressure, the bridge continues to be expanded, and at the same time the steering cylinder 4 can choose to drive the wheel 3 to restore the perpendicular state to the axle, the wheel resistance is smaller, and the bridge expansion is more labor-saving, until the expansion cylinder 5 reaches the maximum stroke and the bridge expansion is completed.

[0036] In the obstacle expansion mode, if the wheel 3 fails to escape from the obstacle after being rotated, the vehicle enters the extreme expansion mode, which is as follows: When in the resistance expansion mode, after the wheel 3 rotates clockwise to the limit position and then counterclockwise to the limit position, if the expansion cylinder pressure value is still greater than the system set pressure, it will enter the limit expansion mode; Stop the action of the expansion cylinder that transmits the pressure signal change, and other expansion cylinders expand the bridge normally to the maximum position to complete the bridge expansion operation.

[0037] It also includes a free control mode. After the operator starts the bridge expansion switch, if manual intervention is required, the operator can press the one-touch expansion button again to stop the current bridge expansion action. Activate at least one wheel 3 or axle through the operation panel for individual control, adjust the wheel 3 angle or the extended axle 2 rotation angle to a custom angle, the wheel 3 angle custom adjustment angle range is from the minimum wheel 3 steering angle to the maximum wheel 3 steering angle of the current model, the extended axle 2 angle custom adjustment angle range is from the minimum extended axle 2 extension angle to the maximum extended axle 2 extension angle of the current model, toggle the current angle expansion button, enter the automatic expansion mode in the current state until the axle expansion is completed.

[0038] In the normal expansion mode, when the steering angle of the wheel 3 is selected to be greater than or equal to 80° and less than 90°, it is a rapid bridge expansion. When the steering angle of the wheel 3 reaches the set angle, the expansion bridge 2 begins to expand, and the wheel 3 continues to rotate until it is at 90° with the expansion bridge 2. During this period, the wheel 3 moves on the ground in a mixed form of sliding friction and rolling friction.

[0039] In the normal expansion mode, when the steering angle of the wheel 3 is selected to be 90°, it is tire protection and bridge expansion. When the steering angle of the wheel 3 reaches the set angle of 90°, the expansion bridge 2 begins to expand. At this time, the wheel 3 moves on the ground in the form of rolling friction.

[0040] like Figure 1 and 2 As shown, a system for extending a traveling chassis axle comprises a frame 1, an extension bridge 2 hinged to the four corners of the frame 1, and wheels 3 hinged to the ends of the extension bridge 2. The wheels 3 are steered by a steering cylinder 4 mounted on the extension bridge 2, and the extension bridge 2 is extended and retracted by an extension cylinder 5, and is characterized in that: It also includes an electromagnetic reversing valve 6 which is connected to each steering cylinder 4 and extension cylinder 5 in a one-to-one correspondence. The oil inlet and oil outlet of the electromagnetic reversing valve 6 are respectively connected to the main oil inlet pipeline and the main oil return pipeline. A balancing valve 7 is arranged on the pipeline between the steering cylinder 4 and the corresponding electromagnetic reversing valve 6, and a hydraulic lock 8 is arranged on the pipeline between the extension cylinder 5 and the corresponding electromagnetic reversing valve 6.

[0041] The present invention realizes individual control by setting valve groups corresponding to each steering wheel and the expansion bridge 2. In the case of obstacles and limited expansion space, the individual control has a higher degree of freedom and can realize various expansion bridge states without being restricted by the traditional left and right side associated hydraulic system; the wheel 3 will generate an opposite force during the steering process, and the balance valve 7 has better load resistance, which reduces the impact on the cylinder. The hydraulic lock 8 is used at the end of the expansion bridge 2 to realize the positioning of the expansion bridge 2, and further realize stable support after the expansion of the bridge.

[0042] A compensation valve 9 is provided between the electromagnetic reversing valve 6 and the main oil inlet pipeline. The compensation valves 9 are connected through a compensation pipeline. A one-way valve 10 is provided on the pipeline between the compensation valve 9 and the compensation pipeline. The compensation pipeline is connected to the main oil return pipeline through an overflow port 11.

[0043] The compensation valve 9 adjusts the oil flow rate rather than the oil pressure according to the opening ratio of the electromagnetic reversing valve 6. This is because during the steering process of the wheels 3, when a single wheel 3 encounters resistance and the pressure increases, the other wheels 3 are unobstructed and the pressure is relatively small. Controlling the oil intake of the compensation valve 9 by pressure will not provide the obstructed wheel 3 with enough power to escape. Controlling the oil flow rate by the opening size of the electromagnetic reversing valve 6 can provide sufficient power support for the corresponding cylinder.

[0044] It also includes a first overflow valve 12 whose two ends are respectively connected to the electromagnetic reversing valve 6 corresponding to the expansion cylinder 5 and the hydraulic lock 8 communication pipeline and the main oil return pipeline.

[0045] By providing the first overflow valve 12, the hydraulic system of the expansion bridge is protected.

[0046] A second overflow valve 13 is provided between the main oil inlet pipeline and the main oil return pipeline, with two ends respectively connected to the main oil inlet pipeline and the main oil return pipeline. The set pressure value of the second overflow valve 13 is higher than the pressure value set by the first overflow valve 12.

[0047] The pressure value of the second relief valve 13 is set higher than that of the first relief valve 12. The purpose of the second relief valve 13 is to protect the hydraulic system of the entire vehicle. When the pressure value in the pipeline is too large, the oil can return to the fuel tank from the main return oil pipeline. The pressure value is set greater than the first relief valve 12 to ensure that when the wheel 3 encounters an obstruction, the pressure value in the pipeline increases and it can work normally. The expansion bridge is under a relatively low pressure state for pressure relief protection, thereby realizing effective protection of the expansion bridge.

[0048] A wheel angle sensor is provided at the hinge point between the wheel 3 and the expansion bridge 2, an expansion angle sensor is provided at the hinge point between the expansion bridge 2 and the frame 1, and an oil pressure sensor 14 is provided on each of the expansion cylinders.

[0049] By setting up wheel angle sensors, expansion angle sensors and oil pressure sensors, the steering angle, expansion angle and oil pressure values ​​are monitored in real time and transmitted to the vehicle control system. The system switches to different working conditions based on the data combination, ultimately achieving maximum bridge expansion.

[0050] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the device disclosed in the embodiment, since it corresponds to the method disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0051] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for extending a chassis axle, characterized in that: Includes normal expansion mode and obstructed expansion mode; The normal expansion mode is specifically: After the vehicle reaches the expansion area, it stops. The operator starts the bridge expansion switch. After the controller receives the bridge expansion command, the bridge expansion is performed. First, the steering cylinder (4) of the wheel (3) retracts, and the wheel (3) is turned to a position of 80° to 90° with the expansion bridge (2). After the controller receives the information that the wheel (3) has been turned, it controls the expansion cylinder (5) at the end of the expansion bridge (2) to extend, and the expansion bridge (2) is pushed out to both sides with the hinge point of the expansion bridge (2) and the frame (1) as the center. The wheel (3) moves until the expansion cylinder (5) reaches the maximum stroke, and the bridge expansion is completed. The obstacle expansion mode is specifically: During the bridge expansion process in the normal expansion mode, when the wheel (3) encounters an obstacle that is difficult to cross during the bridge expansion process, according to the pressure signal detected by the pressure sensor installed on the expansion cylinder (5), when the pressure value of the expansion cylinder is greater than the system set pressure, the bridge enters the resistance expansion mode. The system set pressure is a theoretical working pressure calculated based on the thrust required for bridge expansion and the cylinder diameter of the expansion cylinder (5). The set value is 1.25 to 1.35 times the theoretical working pressure. The controller sends out a command to control the wheel (3) steering cylinder (4) at the end of the expansion bridge (2) that transmits the pressure signal change to rotate the wheel (3) in the clockwise direction to the limit position, and then rotate it counterclockwise to the limit position, while the expansion cylinder (5) continues to work; when the pressure value of the expansion cylinder is less than the system set pressure, the bridge continues to be expanded until the expansion cylinder (5) reaches the maximum stroke, and the bridge expansion is completed.

2. The method for extending a chassis axle according to claim 1, characterized in that: In the obstacle expansion mode, if the wheel (3) fails to escape from the obstacle after turning, the vehicle enters the extreme expansion mode, which is as follows: When in the resistance expansion mode, after the wheel (3) rotates clockwise to the limit position and then rotates counterclockwise to the limit position, if the expansion cylinder pressure value is still greater than the system set pressure, the system enters the limit expansion mode; Stop the action of the expansion cylinder that transmits the pressure signal change, and other expansion cylinders expand the bridge normally to the maximum position to complete the bridge expansion operation.

3. The method for extending a chassis axle according to claim 1, characterized in that: It also includes a free control mode. After the operator starts the bridge expansion switch, if manual intervention is required, the operator can press the one-touch expansion button again to stop the current bridge expansion action. At least one wheel (3) or axle is activated through the operation panel for individual control. After adjusting the wheel (3) angle or the extended axle (2) rotation angle to a custom angle, the wheel (3) angle custom adjustment angle range is from the minimum wheel (3) steering angle of the current vehicle model to the maximum wheel (3) steering angle, and the extended axle (2) angle custom adjustment angle range is from the minimum extended axle (2) extension angle of the current vehicle model to the maximum extended axle (2) extension angle, and the current angle expansion button is toggled to enter the automatic expansion mode in the current state until the axle expansion is completed.

4. The method for expanding a chassis axle according to claim 1, characterized in that: In the normal expansion mode, when the steering angle of the wheel (3) is selected to be greater than or equal to 80° and less than 90°, rapid bridge expansion is performed. When the steering angle of the wheel (3) reaches the set angle, the expansion bridge (2) begins to expand, and the wheel (3) continues to rotate until it is at a 90° angle to the expansion bridge (2). During this period, the wheel (3) moves on the ground in a mixed form of sliding friction and rolling friction.

5. The method for extending a chassis axle according to claim 1, characterized in that: In the normal expansion mode, when the steering angle of the wheel (3) is selected to be 90°, the tire protection bridge is expanded. When the steering angle of the wheel (3) reaches the set angle of 90°, the expansion bridge (2) begins to expand, and the wheel (3) moves on the ground in the form of rolling friction.

6. A system for implementing the method for extending a traveling chassis axle according to any one of claims 1 to 5, comprising a vehicle frame (1), an extension bridge (2) hinged to the four corners of the vehicle frame (1), and wheels (3) hinged to the ends of the extension bridge (2), wherein the wheels (3) are steered by a steering cylinder (4) mounted on the extension bridge (2), and the extension bridge (2) is extended and retracted by an extension cylinder (5), characterized in that: It also includes electromagnetic reversing valves (6) respectively connected to the steering cylinders (4) and the expansion cylinders (5) in a one-to-one correspondence, wherein the oil inlet and the oil outlet of the electromagnetic reversing valve (6) are respectively connected to a main oil inlet pipeline and a main oil return pipeline, a balancing valve (7) is arranged on the pipeline between the steering cylinder (4) and the corresponding electromagnetic reversing valve (6), and a hydraulic lock (8) is arranged on the pipeline between the expansion cylinder (5) and the corresponding electromagnetic reversing valve (6).

7. The system for implementing the method for expanding the chassis axle according to claim 6, characterized in that: A compensation valve (9) is provided between the electromagnetic reversing valve (6) and the main oil inlet pipeline. The compensation valves (9) are connected via a compensation pipeline. A check valve (10) is provided on the pipeline between the compensation valve (9) and the compensation pipeline. The compensation pipeline is connected to the main oil return pipeline via an overflow port (11).

8. The system for implementing the method for expanding the chassis axle according to claim 7, characterized in that: It also includes a first overflow valve (12) whose two ends are respectively connected to the electromagnetic reversing valve (6) corresponding to the expansion cylinder (5) and the hydraulic lock (8) communication pipeline and the main oil return pipeline.

9. The system for implementing the method for expanding the chassis axle according to claim 8, characterized in that: A second overflow valve (13) is provided between the main oil inlet pipeline and the main oil return pipeline, with two ends respectively connected to the main oil inlet pipeline and the main oil return pipeline. The set pressure value of the second overflow valve (13) is higher than the set pressure value of the first overflow valve (12).

10. The system for implementing the method for expanding the chassis axle according to claim 9, characterized in that: A wheel angle sensor is provided at the hinge point between the wheel (3) and the expansion bridge (2), an expansion angle sensor is provided at the hinge point between the expansion bridge (2) and the vehicle frame (1), and an oil pressure sensor (14) is provided on each of the expansion oil cylinders.

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