Steering system of mining dump truck and control method of steering system

Abstract

The invention discloses a steering system of a mining dump truck. The steering system comprises a front steering axle, a rear steering drive axle, a steering control mechanism and a steering controller. The steering control mechanism drives the front steering axle to steer, and the steering controller controls the rear steering drive axle to steer according to the steering angle of the front steering axle; the front steering axle and the rear steering axle are respectively provided with a front axle angle sensor and a rear axle angle sensor which are in signal connection with the steering controller. The control method comprises the steps of system hardware self-checking, front steering angle value obtaining, rear steering starting condition judging, rear steering starting and the like. The method has the beneficial effects that the power performance and the steering performance are considered at the same time; meanwhile, steering requirements are accurately obtained, and the steering stability of the whole vehicle is ensured. The redundancy design of the double-emergency steering system can provide steering force on the premise of ensuring safety, and the rear emergency steering system can work for a long time and then return to a factory for maintenance until an operation task is completed, so that the reliability of the whole steering system is improved.

Description

Technical Field

[0001] The invention relates to a vehicle steering system and a control method thereof, in particular to a steering system of a mining dump truck and a control method thereof, and belongs to the technical field of engineering vehicles. Background Art

[0002] Mining transport vehicles are one of the main material transportation equipment in the mining process. The mining environment is harsh, and there are many slopes and turns on the transportation route. Mining dump trucks are multi-bridge transport vehicles. In this environment with many turns, the large turning radius of the vehicle will cause inconvenience in turning.

[0003] Axles are divided into four types according to the driving mode: steering axle, driving axle, steering driving axle and supporting axle. Steering axle and supporting axle are both driven axles. Most cars are front-engine rear-drive, so the front axle is the steering axle and the rear axle is the driving axle; while for front-engine front-drive cars, the front axle becomes the steering driving axle and the rear axle serves as the supporting axle.

[0004] However, as a heavy-duty transport vehicle, a mining dump truck is usually a multi-axle structure. In order to improve the steering performance, a double steering axle structure combining a front steering axle and a rear steering axle is usually adopted, but the mutual coordination and matching of the double steering axles is a technical difficulty.

[0005] In order to improve the steering capability without sacrificing the power performance, the existing solution adopts a solution combining a front steering axle with a rear steering drive axle, but the rear steering drive axle uses a rotary platform to drive an ordinary drive axle.

[0006] For example, Chinese patent CN218505638U discloses a power unit with load-bearing and steering functions and a new energy heavy-duty dump truck. The power unit with load-bearing and steering functions includes a bracket, an electric drive assembly, a drive axle, a subframe, a slewing support and a cylinder. When the power unit is applied to the dump truck, the slewing support is used to connect to the whole vehicle bracket of the dump truck, the drive axle obtains power through the electric drive assembly, and the bracket for fixing the drive axle is hinged with the subframe. Based on this, through the arrangement of the bracket and the slewing support, the whole vehicle bracket of the dump truck and the drive axle can have a rotatable and swingable connection relationship. During the operation of the dump truck, the rotation of the slewing support can drive the subframe and the front frame to generate a rotation angle, and the subframe can form a certain angle with the whole vehicle frame, so that the lateral force generated by the friction between the front wheel and the ground can provide sufficient steering force for the whole vehicle, improve the steering flexibility of the whole vehicle, and reduce the power demand for the electric drive assembly.

[0007] The comparative document adopts a scheme in which a subframe connects the drive axle and the vehicle frame to achieve the effect that the rear axle has steering and driving capabilities. However, in this scheme, the rear axle rotates around the slewing support, and the entire rear axle rotates passively as a whole through the relative rotation of the bracket and the slewing support, causing sliding friction between the tire and the ground, which leads to severe tire wear.

[0008] In addition, due to the large load capacity of mining dump trucks, vehicle steering stability is also an important performance requirement for the entire vehicle. In order to reduce the turning radius, the solution of synchronous steering of the front and rear axles can effectively reduce the turning radius. The optimal solution is that the wheels of the front and rear steering axles are tangent to the turning radius after turning. Since the front and rear steering axles are not symmetrically distributed relative to the center of the vehicle frame, in order to achieve the best steering effect, the steering angles of the front and rear steering axles are different when they are synchronously turned, but the steering is opposite. In the above-mentioned comparative documents, the overall rotation of the rear axle forms an angle relative to the vehicle frame, and the front and rear axles cannot be on the same turning trajectory. In addition, the two different steering principles and control systems cannot achieve synchronous coordination. The inability of the front and rear steering axles to steer synchronously will seriously affect the steering stability of the vehicle. Summary of the invention

[0009] Purpose of the invention: The purpose of the present invention is to provide a steering system and a control method for a mining dump truck in view of the problems existing in the prior art. The present invention adopts a solution combining a front steering axle and a rear steering drive axle to solve the problem of the contradiction between the power performance requirements and the turning radius of the mining dump truck, and both the front and rear axles adopt an integral steering axle structure, the rear axle adopts a steering axle independently driven by an electric motor, and the steering mechanism of the rear steering drive axle is the same as that of the front steering axle, thereby realizing coordinated control of the front steering axle and the rear steering drive axle, and improving the steering stability of the whole vehicle.

[0010] Technical solution: A steering system for a mining dump truck, comprising a front steering axle, a rear steering drive axle, a steering control mechanism and a steering controller; the front steering axle and the rear steering drive axle are respectively located at the front and rear ends of the frame; the steering control mechanism drives the front steering axle to steer, and the steering controller controls the steering of the rear steering drive axle according to the steering angle of the front steering axle; the front steering axle is provided with a front axle angle sensor, and the front axle angle sensor is connected to the steering controller signal; the rear steering drive axle is provided with a rear axle angle sensor, and the rear axle angle sensor is connected to the steering controller signal.

[0011] When the vehicle turns around or turns at a large angle, the present invention drives the front steering axle to turn through the steering control mechanism, and the steering controller controls the synchronous steering of the rear steering drive axle according to the steering angle of the front steering axle. The front steering axle and the rear steering drive axle have the same steering angle and opposite steering to achieve the same walking track of the front and rear steering wheels, thereby improving the steering stability of the vehicle while reducing the turning radius of the vehicle. The rear axle adopts an integral steering axle structure to improve the load-bearing performance and adopts the same hydraulically driven steering linkage mechanism as the front axle, so as to achieve synchronous matching of the front and rear steering; at the same time, the rear steering drive axle is equipped with an independent motor drive device to become a steering drive axle, which realizes the steering and provides driving force at the same time, while the existing technology adopts the slewing support steering, which has the problems of severe tire wear and unstable steering, so the present invention takes into account both the power performance and the steering performance. The steering angle of the front steering axle can be measured more directly and accurately through the front axle angle sensor, and the steering of the rear steering drive axle can be controlled by the steering controller. The rear axle angle sensor can timely feedback the steering of the rear steering drive axle, and the steering controller can timely correct the steering angle to ensure the steering stability of the vehicle.

[0012] Preferably, in order to further ensure the steering stability of the whole vehicle, a left front wheel angle sensor and a right front wheel angle sensor for measuring the rotation angles of the left and right wheel hubs are respectively provided on both sides of the front steering axle, and the left front wheel angle sensor and the right front wheel angle sensor are connected to the steering controller signal; a left rear wheel angle sensor and a right rear wheel angle sensor for measuring the rotation angles of the left and right wheel hubs are respectively provided on both sides of the rear steering drive axle, and the left rear wheel angle sensor and the right rear wheel angle sensor are connected to the steering controller signal.

[0013] Since the road conditions on which mining dump trucks travel are very complex, the steering angles of the wheel hubs on both sides of the front steering axle are often inconsistent. There are two reasons for the inconsistent steering angles: First, the steering wheel is impacted due to poor road conditions, causing the impacted steering wheel to deflect. However, since the steering mechanism is a connecting rod mechanism with a small steering deviation, if the deviation is too large, it indicates a steering axle failure. The deviation of the two steering wheels will also affect the steering controller's judgment of the actual steering angle requirement, and thus the steering angle of the rear steering drive axle cannot be controlled. Second, the angle sensor fails, resulting in the measurement data being inconsistent with the actual steering angle. Therefore, in order to quickly and accurately troubleshoot and accurately obtain steering requirements, four angle sensors that measure the rotation angle of the wheel hub are installed.

[0014] Preferably, in order to ensure the reliability of front and rear steering, a front steering hydraulic drive device is provided between the steering control mechanism and the front steering axle, and the steering control mechanism drives the front steering axle to steer through the front steering hydraulic drive device, and the front steering hydraulic drive device is connected to a front steering system pressure sensor connected to the steering controller signal; a rear steering hydraulic drive device is provided between the steering controller and the rear steering drive axle, and the steering controller drives the rear steering drive axle to steer through the rear steering hydraulic drive device, and the rear steering hydraulic drive device is connected to a rear steering system pressure sensor connected to the steering controller signal.

[0015] Both the front steering hydraulic drive device and the rear steering hydraulic drive device are driven hydraulically. Firstly, it is more convenient and reliable to obtain the oil for driving the front and rear steering respectively from the existing steering hydraulic system. Secondly, by separately monitoring the system pressure of the two steering hydraulic drive devices, the respective steering failures can be discovered in time to ensure the reliability of the front and rear steering.

[0016] Preferably, in order to further improve the reliability of the steering system, a front emergency steering system connected in parallel with the front steering hydraulic drive device is provided between the steering control mechanism and the front steering axle, and the steering controller controls the access of the front emergency steering system; the front emergency steering system includes an independently operated front emergency motor and a front emergency steering pump; A rear emergency steering system connected in parallel with the rear steering hydraulic drive device is provided between the steering controller and the rear steering drive axle, and the steering controller controls the access of the rear emergency steering system; the rear emergency steering system includes an independently operated rear emergency motor and a rear emergency steering pump.

[0017] When the steering system fails, the emergency steering system will be activated. First, the steering controller determines the specific faulty system based on the front and rear angle sensors and the front and rear pressure sensors. Because the front steering is the main steering system, when the current steering fails, the steering controller will activate the front emergency steering system to ensure that the front steering axle continues to work, and at the same time alarm the entire machine, the entire machine slows down until it stops, and the steering angle of the front steering axle returns to the straight-ahead state. When the front steering failure is detected, the state of the rear steering drive axle is detected, and the rear steering drive axle is controlled to return to the straight-ahead state.

[0018] When the rear steering fails, the steering controller will start the rear emergency steering system and continue to provide hydraulic power to complete the rear steering normally. Since the rear steering is an auxiliary steering, it can continue to work when the pressure value of the rear steering system is not lower than the set safety value; however, when the pressure value of the rear steering system is lower than the set safety value, it is necessary to stop the machine for maintenance immediately. Because when the rear emergency steering system is started, the pressure value of the rear steering system still cannot meet the working pressure value of the rear steering drive axle, which means that the rear emergency steering system or the entire rear steering system has failed; if the rear steering drive axle is currently in the steering state, the rear steering drive axle cannot be restored to a safe straight state, affecting the stability of the vehicle.

[0019] A method for controlling a steering system of a mining dump truck comprises the following steps: Step 1: System hardware self-check: After the vehicle is started, the steering controller will self-check the system hardware. After the self-check passes, it will proceed to step 2. Step 2: Obtain the front steering angle value. The driver operates the steering control mechanism to drive the front steering axle to steer. The steering controller obtains the measurement value of the front axle angle sensor and proceeds to step 3. Step 3: Determine the rear steering start condition. The steering controller compares the obtained front axle angle sensor measurement value with the set rear axle steering start threshold. If the front axle angle sensor measurement value is greater than the rear axle steering start threshold, the process proceeds to step 4. If the front axle angle sensor measurement value is not greater than the rear axle steering start threshold, the process returns to step 2. Step 4: start the rear steering, the steering controller controls the steering of the rear steering drive axle through the rear steering hydraulic drive device, the steering angle of the rear steering drive axle is equal to the measured value of the front axle angle sensor obtained, and the steering is opposite; when the steering angle of the rear steering drive axle is not greater than the rear axle steering start threshold, the steering angle of the rear steering drive axle is reset to zero, and the process returns to step 2; Step 5. End. After the vehicle is turned off, the steering controller performs a self-check on the system hardware and shuts down after the self-check passes.

[0020] The front steering axle steering of the present invention serves as the main steering steering. The steering controller determines the steering intention by taking the measured front steering axle steering angle as input. When the vehicle is traveling in a straight line and the main steering is slightly turned to correct the driving trajectory, the rear steering drive axle maintains a straight-ahead state and does not turn along with the main steering. When the vehicle turns at a large angle or makes a U-turn, the rear steering drive axle and the front steering axle maintain synchronous steering with equal steering angles and opposite steering directions. When the turn or U-turn is completed, the rear steering drive axle resumes the straight-ahead state.

[0021] The present invention determines the steering intention through the steering angle of the main steering, so as to avoid oversteering of the rear steering drive axle, avoid tail swinging or swaying of the whole vehicle when traveling straight, and improve the stability of the whole vehicle in the straight-ahead state; when a large-angle steering is required, the steering angles of the front steering axle and the rear steering drive axle are kept consistent, so that the movement trajectories of the front and rear wheels overlap, thereby improving the steering performance; at the same time, the rear axle is a steering drive axle, which can provide driving force while steering, and avoid tire slippage and wear.

[0022] Preferably, in order to accurately obtain the steering angle of the main steering, the method for obtaining the front steering angle value in step 2 is as follows: S2.1. Obtain the steering angles of the wheel hubs on both sides of the front steering axle, and the steering controller reads the angle value of the left front wheel angle sensor A and the angle value of the right front wheel angle sensor B ; S2.2. Compare the steering angles of the wheels on both sides, and the steering controller compares the angle difference ; When the angle difference is greater than the normal threshold, it is determined as a system failure and an alarm is issued; when the angle difference is within the normal threshold, proceed to the next step; S2.3, calculate the steering angle and take the angle value of the left front wheel angle sensor A and the angle value of the right front wheel angle sensor B The average value ( A + B ) / 2, which is output to the steering controller as the front steering angle value.

[0023] When a vehicle is driving in complex road conditions, the wheels on both sides of the front steering axle may deviate from the steering direction. Since the steering hubs on both sides are connected by a connecting rod, if the steering angle difference between the steering hubs on both sides is greater than the normal threshold, which is usually set to 0.5︒, it means that the front steering axle is faulty and needs to be repaired in time; if the steering angle difference between the steering hubs on both sides is within the normal threshold, the true main steering steering angle can be obtained more accurately by taking the average value, thereby accurately controlling the steering of the rear steering drive axle.

[0024] Preferably, in order to further ensure the stability and safety of vehicle steering, the step three of judging the rear steering start condition also includes the determination of the vehicle speed. If the current vehicle speed is greater than the set speed threshold, starting the rear steering is prohibited; if the current vehicle speed is within the set speed threshold range, entering step four to start the rear steering.

[0025] Since the present invention relates to the steering system of a mining dump truck, when the vehicle's own weight and load are both large, and the road conditions of the mining truck are also very bad, in order to ensure the stability and safety of the vehicle's steering, the vehicle needs to perform a large angle turn at a low speed. The step three of judging the rear steering start condition also includes the determination of the vehicle speed. If the current vehicle speed is greater than the set speed threshold, the rear steering is prohibited from being started; if the current vehicle speed is within the set speed threshold range, the step four is entered to start the rear steering. The higher the speed, the larger the required turning radius. Therefore, by limiting the vehicle speed as the judging rear steering start condition of the present invention, the steering stability of the vehicle can be further improved.

[0026] Preferably, in order to ensure the reliability of the steering of the rear steering drive axle, the method of starting the rear steering in step 4 is as follows: S4.1, issuing a rear steering command, the steering controller issues a steering command to the rear steering hydraulic drive device according to the front steering angle value output in step 3; S4.2. Obtain the steering angles of the wheel hubs on both sides of the rear steering drive axle. The rear steering hydraulic drive device drives the steering wheel hubs on both sides of the rear steering drive axle to steer. The steering controller obtains the angle value of the left rear wheel angle sensor. C and the angle value of the right rear wheel angle sensor D ; S4.3, compare the steering angles of the wheels on both sides, and the steering controller compares the angle difference ; When the angle difference is greater than the normal threshold of the steering angle difference of the rear steering drive axle, it is determined to be a rear axle system failure and an alarm is issued; when the angle difference is within the normal threshold range of the steering angle difference of the rear steering drive axle, proceed to the next step; S4.4, confirm the rear axle steering angle, when the angle value of the left rear wheel angle sensor C Or the angle value of the right rear wheel angle sensor D Equal to the front steering angle value E When , the rear axle steering is completed.

[0027] By obtaining the angle value of the left rear wheel angle sensor C and the angle value of the right rear wheel angle sensor D The steering state of the rear steering drive axle can be determined accurately and timely, and fault monitoring can be performed, thereby improving the steering reliability of the rear steering drive axle.

[0028] Preferably, in order to ensure the reliability of front and rear steering, the step 1 system hardware self-check includes the detection of the front steering system pressure sensor and the rear steering system pressure sensor. The steering controller obtains the pressure value P of the front steering hydraulic system through the front steering system pressure sensor. 前 , The steering controller obtains the pressure value P of the rear steering hydraulic system through the rear steering system pressure sensor. 后 , When P 前 and / or P 后 Not greater than the minimum steering system pressure value P min When the steering controller issues a fault alarm; When P 前 and P 后 Both are greater than the minimum steering system pressure value P min , the system hardware self-test passed.

[0029] Both the front steering hydraulic drive device and the rear steering hydraulic drive device are driven hydraulically. Firstly, it is more convenient and reliable to obtain the oil for driving the front and rear steering respectively from the existing steering hydraulic system. Secondly, by separately monitoring the system pressure of the two steering hydraulic drive devices, the respective steering failures can be discovered in time to ensure the reliability of the front and rear steering.

[0030] Preferably, in order to further improve the reliability of the steering system, when the steering system fails, the emergency steering system is activated, and the specific control method is as follows: When P 前 and P 后 Not greater than the minimum steering system pressure value P min When the front emergency steering system and the rear emergency steering system are activated at the same time; the steering controller issues a fault alarm, and the vehicle slows down until it stops; the front steering axle returns to the straight-ahead state, and the front emergency steering system stops working; the rear steering drive axle cuts off power output and returns to the straight-ahead state, and the rear emergency steering system stops working; When P 前 Not greater than the minimum steering system pressure value P min When the vehicle is in a straight-ahead state, the current state of the rear steering drive axle is determined. If the vehicle is in a straight-ahead state, the front emergency steering system is activated separately. The rear steering drive axle cuts off power output and maintains a straight-ahead state. The steering controller issues a fault alarm, and the vehicle decelerates until it stops. The front steering axle returns to a straight-ahead state, and the front emergency steering system stops working. If the rear steering drive axle is currently in the steering state, the front emergency steering system and the rear steering hydraulic drive device are activated at the same time; the steering controller issues a fault alarm, and the vehicle slows down until it stops; the front steering axle returns to the straight-ahead state, and the front emergency steering system stops working; the rear steering drive axle cuts off power output and returns to the straight-ahead state, and the rear steering hydraulic drive device stops working; When P 后 Not greater than the minimum steering system pressure value P minWhen the rear emergency steering system is activated separately, the steering controller issues a fault alarm and the vehicle operates normally; when the measured value of the front axle angle sensor is greater than the rear axle steering activation threshold, it is determined whether the current vehicle speed is within the vehicle speed threshold range. If the current vehicle speed is greater than the set vehicle speed threshold, the activation of the rear steering is prohibited; if the current vehicle speed is within the set vehicle speed threshold range, the rear emergency steering system drives the rear steering drive axle to steer.

[0031] When the steering system fails, the emergency steering system will be activated. First, the steering controller determines the specific faulty system based on the front and rear angle sensors and the front and rear pressure sensors. Because the front steering is the main steering system, when the current steering fails, the steering controller will activate the front emergency steering system to ensure that the front steering axle continues to work, and at the same time alarm the entire machine, the entire machine slows down until it stops, and the steering angle of the front steering axle returns to the straight-ahead state. When the front steering failure is detected, the state of the rear steering drive axle is detected, and the rear steering drive axle is controlled to return to the straight-ahead state.

[0032] When the rear steering fails, the steering controller will start the rear emergency steering system and continue to provide hydraulic power to complete the rear steering normally. Since the rear steering is an auxiliary steering, it can continue to work when the pressure value of the rear steering system is not lower than the set safety value; however, when the pressure value of the rear steering system is lower than the set safety value, it is necessary to stop the machine for maintenance immediately. Because when the rear emergency steering system is started, the pressure value of the rear steering system still cannot meet the working pressure value of the rear steering drive axle, which means that the rear emergency steering system or the entire rear steering system has failed; if the rear steering drive axle is currently in the steering state, the rear steering drive axle cannot be restored to a safe straight state, affecting the stability of the vehicle.

[0033] Beneficial effects: The present invention can improve the steering stability of the whole vehicle while reducing the turning radius of the whole vehicle; can achieve synchronous matching of front and rear steering; can provide driving force while achieving steering, avoiding the problems of severe tire wear and unstable steering in the prior art. The present invention takes into account both power performance and steering performance.

[0034] Four angle sensors that measure the wheel hub rotation angles are installed separately to monitor the steering angles of the four steering wheels, which can quickly and accurately eliminate faults and accurately obtain steering requirements to ensure the steering stability of the entire vehicle.

[0035] Front and rear pressure sensors are used to determine the specific faulty system. The redundant design of the dual emergency steering system can provide steering force while ensuring safety. The rear emergency steering system can work for a long time until the task is completed and then returned to the factory for repair, thus improving the reliability of the entire steering system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] 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.

[0037] Figure 1 This is the control principle diagram of the present invention; Figure 2 It is a schematic diagram of the structural arrangement of the present invention; Figure 3 A top view of the structure arrangement of the present invention; Figure 4 It is a turning schematic diagram of the present invention; Figure 5 It is a steering schematic diagram of the prior art; Figure 6 This is a control flow chart of the present invention; Figure 7 It is the work flow chart of the emergency system of the present invention. DETAILED DESCRIPTION

[0038] 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.

[0039] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "horizontal", "top", "bottom", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0040] 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. Embodiment 1

[0041] like Figure 1 , 2 As shown in 3, a steering system of a mining dump truck includes a front steering axle 1, a rear steering drive axle 2, a steering control mechanism 3 and a steering controller 4; the front steering axle 1 and the rear steering drive axle 2 are respectively located at the front and rear ends of a frame 5; the steering control mechanism 3 drives the front steering axle 1 to steer, and the steering controller 4 controls the steering of the rear steering drive axle 2 according to the steering angle of the front steering axle 1, and the front steering axle 1 is provided with a front axle angle sensor 6, and the front axle angle sensor 6 is connected to the steering controller 4 by signal; the rear steering drive axle 2 is provided with a rear axle angle sensor 7, and the rear axle angle sensor 7 is connected to the steering controller 4 by signal.

[0042] When the vehicle turns around or turns at a large angle, the steering mechanism 3 drives the front steering axle 1 to turn, and the steering controller 4 controls the rear steering drive axle 2 to turn synchronously according to the steering angle of the front steering axle 1. Figure 4 As shown, the front steering axle 1 and the rear steering drive axle 2 have the same steering angle and opposite steering to achieve the same walking track of the front and rear steering wheels, thereby improving the steering stability of the vehicle while reducing the turning radius of the vehicle. The rear axle adopts an integral steering axle structure to improve load-bearing performance and uses the same hydraulically driven steering linkage mechanism as the front axle, so as to achieve synchronous matching of the front and rear steering; at the same time, the rear steering drive axle 2 is equipped with an independent motor drive device to become a steering drive axle, realizing steering and providing driving force at the same time. Figure 5 As shown, the prior art uses slewing support steering, which has the problems of severe tire wear and unstable steering. Therefore, the present invention takes into account both power performance and steering performance. The front axle angle sensor 6 can more directly and accurately measure the steering angle of the front steering axle 1, and the steering controller 4 controls the steering of the rear steering drive axle 2. The rear axle angle sensor 7 can timely feedback the steering of the rear steering drive axle 2, and the steering controller 4 can timely correct the steering angle to ensure the steering stability of the whole vehicle.

[0043] In order to further ensure the steering stability of the vehicle, a left front wheel angle sensor 61 and a right front wheel angle sensor 62 for measuring the rotation angles of the left and right wheel hubs are respectively provided on both sides of the front steering axle 1. The left front wheel angle sensor 61 and the right front wheel angle sensor 62 are connected to the steering controller 4 by signal. A left rear wheel angle sensor 71 and a right rear wheel angle sensor 72 for measuring the rotation angles of the left and right wheel hubs are respectively disposed on both sides of the rear steering drive axle 2 . The left rear wheel angle sensor 71 and the right rear wheel angle sensor 72 are connected to the steering controller 4 by signals.

[0044] Since the road conditions on which mining dump trucks travel are very complex, the steering angles of the wheel hubs on both sides of the front steering axle are often inconsistent. There are two reasons for the inconsistent steering angles: First, the steering wheel is impacted due to poor road conditions, causing the impacted steering wheel to deflect. However, since the steering mechanism is a connecting rod mechanism with a small steering deviation, if the deviation is too large, it indicates a steering axle failure. The deviation of the two steering wheels will also affect the steering controller's judgment of the actual steering angle requirement, and thus the steering angle of the rear steering drive axle cannot be controlled. Second, the angle sensor fails, resulting in the measurement data being inconsistent with the actual steering angle. Therefore, in order to quickly and accurately troubleshoot and accurately obtain steering requirements, four angle sensors that measure the rotation angle of the wheel hub are installed.

[0045] In order to ensure the reliability of front and rear steering, a front steering hydraulic drive device 11 is provided between the steering control mechanism 3 and the front steering axle 1. The steering control mechanism 3 drives the front steering axle 1 to steer through the front steering hydraulic drive device 11. The front steering hydraulic drive device 11 is connected to a front steering system pressure sensor 12 which is connected to the signal of the steering controller 4. A rear steering hydraulic drive device 21 is provided between the steering controller 4 and the rear steering drive axle 2. The steering controller 4 drives the rear steering drive axle 2 to steer via the rear steering hydraulic drive device 21. The rear steering hydraulic drive device 21 is connected to a rear steering system pressure sensor 22 which is signal-connected to the steering controller 4.

[0046] The front steering hydraulic drive device 11 and the rear steering hydraulic drive device 21 are both driven hydraulically. Firstly, it is more convenient and reliable to obtain the oil for driving the front and rear steering respectively from the existing steering hydraulic system. Secondly, by separately monitoring the system pressure of the two steering hydraulic drive devices, the respective steering failures can be discovered in time to ensure the reliability of the front and rear steering. Embodiment 2

[0047] like Figure 1As shown, in order to further improve the reliability of the steering system, a front emergency steering system 13 connected in parallel with the front steering hydraulic drive device 11 is provided between the steering control mechanism 3 and the front steering axle 1, and the steering controller 4 controls the access of the front emergency steering system 13; the front emergency steering system 13 includes an independently operated front emergency motor and a front emergency steering pump; A rear emergency steering system 23 connected in parallel with the rear steering hydraulic drive device 21 is provided between the steering controller 4 and the rear steering drive axle 2. The steering controller 4 controls the access of the rear emergency steering system 23; the rear emergency steering system 23 includes an independently operated rear emergency motor and a rear emergency steering pump.

[0048] When the steering system fails, the emergency steering system will be activated. First, the steering controller 4 determines the specific faulty system based on the front and rear angle sensors and the front and rear pressure sensors. Because the front steering is the main steering system, the steering controller 4 will activate the front emergency steering system when the current steering fails to ensure that the front steering axle 1 continues to work, and at the same time alarm the entire machine, the entire machine slows down until it stops, and the steering angle of the front steering axle 1 is restored to the straight-ahead state. When the front steering failure is detected, the state of the rear steering drive axle 2 is detected, and the rear steering drive axle 2 is controlled to return to the straight-ahead state.

[0049] When the rear steering fails, the steering controller 4 will start the rear emergency steering system 23 and continue to provide hydraulic power to complete the rear steering normally. Since the rear steering is an auxiliary steering, the operation can continue when the pressure value of the rear steering system is not lower than the set safety value; however, when the pressure value of the rear steering system is lower than the set safety value, it is necessary to immediately shut down for maintenance. Because when the rear emergency steering system 23 is started, the pressure value of the rear steering system still cannot meet the working pressure value of the rear steering drive axle 2, which means that the rear emergency steering system 23 or the entire rear steering system has failed; if the rear steering drive axle 2 is currently in a steering state, the rear steering drive axle 2 cannot be restored to a safe straight state, affecting the stability of the vehicle. Embodiment 3

[0050] like Figure 4 and 6 As shown, a control method for a steering system of a mining dump truck comprises the following steps: Step 1: System hardware self-check: after the vehicle is started, the steering controller 4 performs a self-check on the system hardware. After the self-check passes, the process proceeds to step 2. Step 2: Obtain the front steering angle value. The driver operates the steering control mechanism 3 to drive the front steering axle 1 to steer. The steering controller 4 obtains the measurement value of the front axle angle sensor 6 and proceeds to step 3. Step 3: Determine the rear steering start condition. The steering controller 4 compares the obtained measurement value of the front axle angle sensor 6 with the set rear axle steering start threshold. If the measurement value of the front axle angle sensor 6 is greater than the rear axle steering start threshold, the process proceeds to step 4. If the measurement value of the front axle angle sensor 6 is not greater than the rear axle steering start threshold, the process returns to step 2. Step 4: Start the rear steering. The steering controller 4 controls the steering of the rear steering drive axle 2 through the rear steering hydraulic drive device 21. The steering angle of the rear steering drive axle 2 is equal to the measured value of the front axle angle sensor 6 and the steering direction is opposite. When the steering angle of the rear steering drive axle 2 is not greater than the rear axle steering start threshold, the steering angle of the rear steering drive axle 2 is reset to zero and the process returns to step 2. Step 5: End. After the vehicle is turned off, the steering controller 4 performs a self-check on the system hardware, and the power is cut off and the system is shut down after the self-check passes.

[0051] The steering of the front steering axle 1 of the present invention is used as the main steering steering. The measured front steering axle steering angle is used as input, and the steering controller 4 determines the steering intention. When the vehicle is traveling in a straight line and the main steering is slightly turned to correct the driving trajectory, the rear steering drive axle 2 maintains a straight-moving state and does not turn with the main steering; when the vehicle turns at a large angle or makes a U-turn, the rear steering drive axle 2 and the front steering axle 1 maintain synchronous steering with equal steering angles and opposite steering directions. When the transition or U-turn is completed, the rear steering drive axle resumes the straight-moving state.

[0052] The present invention determines the steering intention by the steering angle of the main steering, which can avoid oversteering of the rear steering drive axle 2, avoid the phenomenon of tail swinging or swaying of the whole vehicle when it is moving straight, and improve the stability of the whole vehicle in the straight-moving state; when a large-angle steering is required, by keeping the steering angles of the front steering axle 1 and the rear steering drive axle 2 consistent, such as Figure 4 As shown, the movement trajectories of the front and rear wheels are overlapped, which improves the steering performance. At the same time, the rear axle is a steering drive axle, which can provide driving force while steering to avoid tire slippage and wear.

[0053] In order to accurately obtain the steering angle of the main steering, the method for obtaining the front steering angle value in step 2 is as follows: S2.1. Obtain the steering angles of the wheel hubs on both sides of the front steering axle 1, and the steering controller 4 reads the angle value of the left front wheel angle sensor 61 A and the angle value of the right front wheel angle sensor 62 B ; S2.2, compare the steering angles of the wheels on both sides, and the steering controller 4 compares the angle difference ; When the angle difference is greater than the normal threshold, it is determined as a system failure and an alarm is issued; when the angle difference is within the normal threshold range, proceed to the next step; S2.3, calculate the steering angle, and take the angle value of the left front wheel angle sensor 61 Aand the angle value of the right front wheel angle sensor 62 B The average A + B / 2, as the front steering angle value E Output to the steering controller 4.

[0054] When a vehicle is driving in complex road conditions, the wheels on both sides of the front steering axle 1 may deviate from the steering direction. Since the steering hubs on both sides are connected by a connecting rod, if the steering angle difference between the steering hubs on both sides is greater than the normal threshold, which is usually set to 0.5︒, it indicates that the front steering axle 1 has a fault and needs to be repaired in time; if the steering angle difference between the steering hubs on both sides is within the normal threshold, the real main steering steering angle can be obtained more accurately by taking the average value, thereby accurately controlling the steering of the rear steering drive axle.

[0055] In order to further ensure the stability and safety of vehicle steering, the step three of judging the rear steering start condition also includes the determination of the vehicle speed. If the current vehicle speed is greater than the set speed threshold, starting the rear steering is prohibited; if the current vehicle speed is within the set speed threshold range, entering step four to start the rear steering.

[0056] Since the present invention relates to the steering system of a mining dump truck, when the vehicle's own weight and load are both large, and the road conditions of the mining truck are also very bad, in order to ensure the stability and safety of the vehicle's steering, the vehicle needs to perform a large angle turn at a low speed. The step three of judging the rear steering start condition also includes the determination of the vehicle speed. If the current vehicle speed is greater than the set speed threshold, the rear steering is prohibited from being started; if the current vehicle speed is within the set speed threshold range, the step four is entered to start the rear steering. The higher the speed, the larger the required turning radius. Therefore, by limiting the vehicle speed as the judging rear steering start condition of the present invention, the steering stability of the vehicle can be further improved.

[0057] In order to ensure the reliability of the steering of the rear steering drive axle, the method of starting the rear steering in step 4 is as follows: S4.1, issuing a rear steering command, the steering controller 4 issues a steering command to the rear steering hydraulic drive device 21 according to the front steering angle value output in step 3; S4.2, obtain the steering angles of the wheel hubs on both sides of the rear steering drive axle 2, the rear steering hydraulic drive device 21 drives the steering wheel hubs on both sides of the rear steering drive axle 2 to steer, and the steering controller 4 obtains the angle value of the left rear wheel angle sensor 71 C and the angle value of the right rear wheel angle sensor 72 D ; S4.3, compare the steering angles of the wheels on both sides, and the steering controller 4 compares the angle difference ; When the angle difference is greater than the normal threshold of the steering angle difference of the rear steering drive axle 2, it is determined to be a rear axle system failure and an alarm is issued; when the angle difference is within the normal threshold range of the steering angle difference of the rear steering drive axle 2, proceed to the next step; S4.4, confirm the rear axle steering angle, when the angle value of the left rear wheel angle sensor 71 C Or the angle value of the right rear wheel angle sensor 72 D Equal to the front steering angle value E When , the rear axle steering is completed. Embodiment 4

[0058] like Figure 7 As shown, the pressure value P of the front steering hydraulic system 前 is a, the pressure value of the rear steering hydraulic system is P 后 is b, the minimum steering system pressure value P min 0.6Mpa, the front emergency steering system is M, and the rear emergency steering system is N; In order to ensure the reliability of front and rear steering, the step 1 system hardware self-check includes the detection of the front steering system pressure sensor 12 and the rear steering system pressure sensor 22. The steering controller 4 obtains the pressure value P of the front steering hydraulic system through the front steering system pressure sensor 12. 前 , The steering controller 4 obtains the pressure value P of the rear steering hydraulic system through the rear steering system pressure sensor 22. 后 , When P 前 and / or P 后 Not greater than the minimum steering system pressure value P min When , the steering controller 4 issues a fault alarm; When P 前 and P 后 Both are greater than the minimum steering system pressure value P min , the system hardware self-test passed.

[0059] The front steering hydraulic drive device 11 and the rear steering hydraulic drive device 21 are both driven hydraulically. Firstly, it is more convenient and reliable to obtain the oil for driving the front and rear steering respectively from the existing steering hydraulic system. Secondly, by separately monitoring the system pressure of the two steering hydraulic drive devices, the respective steering failures can be discovered in time to ensure the reliability of the front and rear steering.

[0060] In order to further improve the reliability of the steering system, when the steering system fails, the emergency steering system is activated. The specific control method is as follows: When P 前 and P 后 Not greater than the minimum steering system pressure value P minWhen the front emergency steering system 13 and the rear emergency steering system 23 are started at the same time; the steering controller 4 issues a fault alarm, and the vehicle decelerates until it stops; the front steering axle 1 returns to the straight-ahead state, and the front emergency steering system 13 stops working; the rear steering drive axle 2 cuts off the power output and returns to the straight-ahead state, and the rear emergency steering system 23 stops working; When P 前 Not greater than the minimum steering system pressure value P min When the current state of the rear steering drive axle 2 is determined, if it is in a straight-ahead state, the front emergency steering system 13 is activated separately, the rear steering drive axle 2 cuts off power output and maintains a straight-ahead state, the steering controller 4 issues a fault alarm, and the vehicle decelerates until it stops; the front steering axle 1 returns to a straight-ahead state, and the front emergency steering system 13 stops working; If the rear steering drive axle 2 is currently in a steering state, the front emergency steering system 13 and the rear steering hydraulic drive device 21 are simultaneously started; the steering controller 4 issues a fault alarm, and the vehicle decelerates until it stops; the front steering axle 1 returns to a straight-ahead state, and the front emergency steering system 13 stops working; the rear steering drive axle 2 cuts off power output and returns to a straight-ahead state, and the rear steering hydraulic drive device 21 stops working; When P 后 Not greater than the minimum steering system pressure value P min When the rear emergency steering system 23 is started separately, the steering controller 4 issues a fault alarm, and the vehicle operates normally; when the measurement value of the front axle angle sensor 6 is greater than the rear axle steering start threshold, it is determined whether the current vehicle speed is within the vehicle speed threshold range. If the current vehicle speed is greater than the set vehicle speed threshold, the start of the rear steering is prohibited; if the current vehicle speed is within the set vehicle speed threshold range, the rear emergency steering system 23 drives the rear steering drive axle 2 to steer.

[0061] When the steering system fails, the emergency steering system will be activated. First, the steering controller 4 determines the specific faulty system based on the front and rear angle sensors and the front and rear pressure sensors. Because the front steering is the main steering system, the steering controller 4 will activate the front emergency steering system when the current steering fails to ensure that the front steering axle 1 continues to work, and at the same time alarm the entire machine, the entire machine slows down until it stops, and the steering angle of the front steering axle 1 is restored to the straight-ahead state. When the front steering failure is detected, the state of the rear steering drive axle 2 is detected, and the rear steering drive axle 2 is controlled to return to the straight-ahead state.

[0062] When the rear steering fails, the steering controller 4 will start the rear emergency steering system 23 and continue to provide hydraulic power to complete the rear steering normally. Since the rear steering is an auxiliary steering, the operation can continue when the pressure value of the rear steering system is not lower than the set safety value; however, when the pressure value of the rear steering system is lower than the set safety value, it is necessary to immediately shut down for maintenance. Because when the rear emergency steering system 23 is started, the pressure value of the rear steering system still cannot meet the working pressure value of the rear steering drive axle 2, which means that the rear emergency steering system or the entire rear steering system has failed; if the rear steering drive axle 2 is currently in a steering state, the rear steering drive axle 2 cannot be restored to a safe straight state, affecting the stability of the vehicle.

[0063] 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.

[0064] 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 steering system for a mining dump truck, comprising a front steering axle (1), a rear steering drive axle (2), a steering control mechanism (3) and a steering controller (4); the front steering axle (1) and the rear steering drive axle (2) are respectively located at the front and rear ends of a vehicle frame (5); the steering control mechanism (3) drives the front steering axle (1) to steer, and the steering controller (4) controls the rear steering drive axle (2) to steer according to the steering angle of the front steering axle (1), characterized in that: The front steering axle (1) is provided with a front axle angle sensor (6), and the front axle angle sensor (6) is connected to the steering controller (4) via a signal; The rear steering drive axle (2) is provided with a rear axle angle sensor (7), and the rear axle angle sensor (7) is connected to the steering controller (4) via a signal.

2. The steering system of a mining dump truck according to claim 1, characterized in that: A left front wheel angle sensor (61) and a right front wheel angle sensor (62) for measuring the rotation angles of the left and right wheel hubs are respectively provided on both sides of the front steering axle (1), and the left front wheel angle sensor (61) and the right front wheel angle sensor (62) are connected to the steering controller (4) via signals; A left rear wheel angle sensor (71) and a right rear wheel angle sensor (72) for measuring the rotation angles of the left and right wheel hubs are respectively provided on both sides of the rear steering drive axle (2), and the left rear wheel angle sensor (71) and the right rear wheel angle sensor (72) are connected to the steering controller (4) via signals.

3. The steering system of a mining dump truck according to claim 2, characterized in that: A front steering hydraulic drive device (11) is provided between the steering control mechanism (3) and the front steering axle (1), and the steering control mechanism (3) drives the front steering axle (1) to steer via the front steering hydraulic drive device (11), and the front steering hydraulic drive device (11) is connected to a front steering system pressure sensor (12) that is signal-connected to the steering controller (4); A rear steering hydraulic drive device (21) is provided between the steering controller (4) and the rear steering drive axle (2); the steering controller (4) drives the rear steering drive axle (2) to steer via the rear steering hydraulic drive device (21); and the rear steering hydraulic drive device (21) is connected to a rear steering system pressure sensor (22) that is signal-connected to the steering controller (4).

4. The steering system of a mining dump truck according to claim 3, characterized in that: A front emergency steering system (13) connected in parallel with the front steering hydraulic drive device (11) is provided between the steering control mechanism (3) and the front steering axle (1), and the steering controller (4) controls the access of the front emergency steering system (13); the front emergency steering system (13) comprises an independently operated front emergency motor and a front emergency steering pump; A rear emergency steering system (23) connected in parallel with the rear steering hydraulic drive device (21) is provided between the steering controller (4) and the rear steering drive axle (2); the steering controller (4) controls the access to the rear emergency steering system (23); the rear emergency steering system (23) comprises an independently operated rear emergency motor and a rear emergency steering pump.

5. A method for controlling a steering system of a mining dump truck according to claim 4, characterized in that: The following steps are involved: Step 1: System hardware self-check: after the vehicle is started, the steering controller (4) performs a self-check on the system hardware. After the self-check passes, the process proceeds to step 2. Step 2: obtaining a front steering angle value, the driver operates the steering control mechanism (3) to drive the front steering axle (1) to steer, the steering controller (4) obtains a measurement value of the front axle angle sensor (6), and then proceeds to step 3; Step 3: determining the rear steering start condition, the steering controller (4) compares the obtained measurement value of the front axle angle sensor (6) with the set rear axle steering start threshold; If the value measured by the current axle angle sensor (6) is greater than the rear axle steering start threshold, then the process proceeds to step 4; if the value measured by the current axle angle sensor (6) is not greater than the rear axle steering start threshold, then the process returns to step 2; Step 4: start the rear steering, the steering controller (4) controls the steering of the rear steering drive axle (2) through the rear steering hydraulic drive device (21), the steering angle of the rear steering drive axle (2) is equal to the measured value obtained by the front axle angle sensor (6), and the steering is opposite; when the steering angle of the rear steering drive axle (2) is not greater than the rear axle steering start threshold, the steering angle of the rear steering drive axle (2) is reset to zero, and the process returns to step 2; Step 5: End. After the vehicle is turned off, the steering controller (4) performs a self-check on the system hardware and shuts down after the self-check passes.

6. The control method of the steering system of a mining dump truck according to claim 5, characterized in that: The method for obtaining the front steering angle value in step 2 is as follows: S2.

1. Obtain the steering angles of the wheel hubs on both sides of the front steering axle (1). The steering controller (4) reads the angle value of the left front wheel angle sensor (61). A and the angle value of the right front wheel angle sensor (62) B ; S2.

2. Compare the steering angles of the wheels on both sides, and the steering controller (4) compares the angle difference ; When the angle difference is greater than the normal threshold, it is judged as a system failure and an alarm is issued; When the angle difference is within the normal threshold range, proceed to the next step; S2.3, calculate the steering angle and obtain the angle value of the left front wheel angle sensor (61) A and the angle value of the right front wheel angle sensor (62) B The average value ( A + B ) / 2, as the front steering angle value E Output to the steering controller (4).

7. The control method of the steering system of a mining dump truck according to claim 5, characterized in that: The step three of judging the rear steering start condition also includes determining the vehicle speed. If the current vehicle speed is greater than the set speed threshold, starting the rear steering is prohibited; if the current vehicle speed is within the set speed threshold range, entering step four to start the rear steering.

8. The control method of the steering system of a mining dump truck according to claim 6 or 7, characterized in that: The method of turning after starting in step 4 is as follows: S4.1, issuing a rear steering command, the steering controller (4) issues a steering command to the rear steering hydraulic drive device (21) according to the front steering angle value output in step 3; S4.2, obtaining the steering angles of the wheel hubs on both sides of the rear steering drive axle (2), the rear steering hydraulic drive device (21) drives the steering wheel hubs on both sides of the rear steering drive axle (2) to steer, and the steering controller (4) obtains the angle value of the left rear wheel angle sensor (71) C and the angle value of the right rear wheel angle sensor (72) D ; S4.

3. Compare the steering angles of the wheels on both sides, and the steering controller (4) compares the angle difference ; When the angle difference is greater than the normal threshold of the steering angle difference of the rear steering drive axle (2), it is determined to be a rear axle system failure and an alarm is issued; When the angle difference is within the normal threshold range of the steering angle difference of the rear steering drive axle (2), proceed to the next step; S4.4, confirm the rear axle steering angle, when the angle value of the left rear wheel angle sensor (71) C Or the angle value of the right rear wheel angle sensor (72) D Equal to the front steering angle value E When , the rear axle steering is completed.

9. The control method of the steering system of a mining dump truck according to claim 5, characterized in that: The step 1 is a system hardware self-test, including the detection of the front steering system pressure sensor (12) and the rear steering system pressure sensor (22). The steering controller (4) obtains the pressure value P of the front steering hydraulic system through the front steering system pressure sensor (12). 前 , The steering controller (4) obtains the pressure value P of the rear steering hydraulic system through the rear steering system pressure sensor (22). 后 , When P 前 and / or P 后 Not greater than the minimum steering system pressure value P min When , the steering controller (4) issues a fault alarm; When P 前 and P 后 Both are greater than the minimum steering system pressure value P min , the system hardware self-check has passed.

10. The control method of the steering system of a mining dump truck according to claim 9, characterized in that: When the steering system fails, the emergency steering system is activated. The specific control method is as follows: When P 前 and P 后 Not greater than the minimum steering system pressure value P min When the front emergency steering system (13) and the rear emergency steering system (23) are activated simultaneously; the steering controller (4) issues a fault alarm, and the vehicle decelerates until it stops; the front steering axle (1) returns to a straight-ahead state, and the front emergency steering system (13) stops working; the rear steering drive axle (2) cuts off power output and returns to a straight-ahead state, and the rear emergency steering system (23) stops working; When P 前 Not greater than the minimum steering system pressure value P min When the current state of the rear steering drive axle (2) is determined, if it is in a straight-ahead state, the front emergency steering system (13) is activated alone, the rear steering drive axle (2) cuts off power output and maintains a straight-ahead state, the steering controller (4) issues a fault alarm, and the vehicle decelerates until it stops; the front steering axle (1) returns to a straight-ahead state, and the front emergency steering system (13) stops working; If the rear steering drive axle (2) is currently in a steering state, the front emergency steering system (13) and the rear steering hydraulic drive device (21) are simultaneously activated; the steering controller (4) issues a fault alarm, and the vehicle decelerates until it stops; the front steering axle (1) returns to a straight-ahead state, and the front emergency steering system (13) stops working; the rear steering drive axle (2) cuts off power output and returns to a straight-ahead state, and the rear steering hydraulic drive device (21) stops working; When P 后 Not greater than the minimum steering system pressure value P min When the vehicle is in a normal state, the rear emergency steering system (23) is activated separately, the steering controller (4) issues a fault alarm, and the vehicle operates normally; When the measurement value of the front axle angle sensor (6) is greater than the rear axle steering start threshold, it is determined whether the current vehicle speed is within the vehicle speed threshold range. If the current vehicle speed is greater than the set vehicle speed threshold, the start of rear steering is prohibited; if the current vehicle speed is within the set vehicle speed threshold range, the rear emergency steering system (23) drives the rear steering drive axle (2) to steer.

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