Double-cab two-shaft electric logistics vehicle steering system and control method thereof

Abstract

The invention discloses a steering system of a double-cab two-shaft electric logistics vehicle and a control method of the steering system. The system is composed of a steering oil tank, an electric steering pump, a proportional electromagnetic valve, an integrated controller, a whole vehicle controller, a 24V storage battery, a power battery, a first steering wheel, a first steering column, a first steering wheel steering angle sensor, a first steering oil cylinder, a first wheel steering angle sensor, a first steering drive axle, a second steering wheel, a second steering column and a second steering wheel steering angle sensor. The first steering oil cylinder, the second steering oil cylinder, the second wheel steering angle sensor, the second steering drive axle and the first limiting device are arranged on the base; the system is good in steering control effect and high in controllability; a selection button can be configured according to needs, and is used for switching two steering modes of single-shaft deflection wheel steering and two-shaft wheel simultaneous deflection steering, so that a vehicle can realize a smaller turning radius, and the passing capacity of a curve is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of logistics vehicle steering systems, and in particular to a steering system for a dual-cab, dual-axle electric logistics vehicle and a control method thereof. Background Art

[0002] With the development of vehicle technology, electric logistics vehicles are becoming more and more popular. Short-distance electric logistics vehicles are mostly two-axle vehicles with hydraulic power steering and single-axle tire deflection steering. The driver can control the steering gear through the steering wheel according to the vehicle's travel needs and then control the vehicle's steering. In certain specific occasions, the space is small, and conventional single-cab electric logistics vehicles can only drive forward and drive backward; based on the needs of material loading and unloading, steering action is also required when backing up; single-cab vehicles have poor visibility when backing up, and considering the safety needs of material transfer, the vehicle is required to have a double cab. If the double steering gear controls the deflection steering of the single-axle tire closest to the cab, when the deflection of the axle tire on this end is manually controlled, the deflection of the axle tire on the other end is controlled by the steering gear. When it is not controlled, it cannot be in absolute zero position, affecting the direction control of the vehicle. Although there are commercially available wire-controlled steering units that support steering wheel operation, their allowable steering loads are small and cannot be applied to large logistics vehicles. There is also a mature complete set of full-hydraulic steering control solutions for both unmanned and manned driving in the agricultural machinery industry. The solution includes an electronic steering wheel, a main controller, a valve group and a wheel angle sensor. However, due to its specific application scenarios, it has high costs, many related components and many related control strategies, and cannot be simplified for application to other types of vehicles. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide a steering system for a dual-cab, two-axle electric logistics vehicle.

[0004] Another object of the present invention is to provide a control method for a steering system of a dual-cab, two-axle electric logistics vehicle.

[0005] The present invention mainly solves the problem that the existing steering control method cannot be conveniently, effectively and cost-effectively applied to a double-cab two-axle electric logistics vehicle.

[0006] The technical solution provided by the present invention is: a steering system for a dual-cab two-axle electric logistics vehicle, which is special in that it is composed of a steering oil tank, an electric steering pump, a high-pressure filter, a proportional solenoid valve, an integrated controller, a vehicle controller, a 24V battery, a power battery, a first steering wheel, a first steering column, a first steering wheel angle sensor, a first steering cylinder, a first wheel angle sensor, a first steering drive axle, a second steering wheel, a second steering column, a second steering wheel angle sensor, a second steering cylinder, a second wheel angle sensor, a second steering drive axle, a first limit device, and a first limit device; The steering oil tank, electric steering pump, high-pressure filter, proportional solenoid valve, integrated controller, vehicle controller, 24V battery, power battery, first steering drive axle, and second steering drive axle are respectively connected to the frame of a double-cab two-axle electric vehicle; the first steering wheel and the first steering column are installed in the first cab of the vehicle; the first steering wheel angle sensor is fixedly connected to the first steering column; the first limit device is fixedly connected to the first steering column; the second steering wheel and the second steering column are installed in the second cab of the vehicle; the second steering wheel angle sensor is fixedly connected to the second steering column; the second limit device is fixedly connected to the second steering column; the first wheel angle sensor is installed in the first steering drive axle; the second wheel angle sensor is installed in the second steering drive axle; the fixed end of the first steering cylinder is connected to the first steering drive axle axle housing of the electric vehicle, and the extended end of the first steering cylinder is connected to the steering knuckle arm of the first steering drive axle; the fixed end of the second steering cylinder is connected to the second steering drive axle axle housing of the electric logistics vehicle, and the extended end of the second steering cylinder is connected to the steering knuckle arm of the second steering drive axle; The steering oil tank is communicated with the oil inlet of the electric steering pump via an oil inlet pipeline; the oil outlet of the electric steering pump is communicated with the oil inlet of the high-pressure filter via a high-pressure pipeline; the oil outlet of the high-pressure filter is communicated with the oil inlet of the proportional solenoid valve; the oil return port of the proportional solenoid valve is communicated with the steering oil tank via an oil return pipeline; the proportional solenoid valve comprises two control circuits, the A1 and B1 ports of the first control circuit are communicated with the oil ports of the rodless chamber and the rod chamber of the first steering cylinder respectively via a high-pressure pipeline, and the A2 and B2 ports of the second control circuit of the proportional solenoid valve are communicated with the oil ports of the rod chamber and the rodless chamber of the second steering cylinder respectively via a high-pressure pipeline; The electric steering pump is electrically connected to the integrated controller via a high-voltage line, and the integrated controller is connected to the power battery via a high-voltage line; The electronic control module, integrated controller, vehicle controller, power battery, first steering wheel angle sensor, first wheel angle sensor, second steering wheel angle sensor, and second wheel angle sensor of the proportional solenoid valve are electrically connected to the 24V battery via a low-voltage power supply line, and the electronic control module, integrated controller, vehicle controller, power battery, first steering wheel angle sensor, first wheel angle sensor, second steering wheel angle sensor, and second wheel angle sensor of the proportional solenoid valve are connected to the CAN line of the vehicle via a CAN line.

[0007] Furthermore, the integrated controller includes at least one high-voltage power distribution module, one DC / AC module, and one DC / DC module; the power battery outputs high-voltage direct current to the high-voltage power distribution module in the integrated controller, the high-voltage power distribution module distributes the high-voltage direct current to the DC / AC module and the DC / DC module, the DC / AC module outputs high-voltage alternating current to the electric steering pump, and the DC / DC module provides a stable low-voltage DC power supply to the vehicle's electrical components while charging the 24V battery.

[0008] Furthermore, the proportional solenoid valve is a multi-module assembled valve group controlled by CAN communication, which includes two control circuits. The first control circuit controls the action of the first steering cylinder, and the second control circuit controls the action of the second steering cylinder, thereby realizing independent control of the wheels of the first steering drive axle and the second steering drive axle when the vehicle is turning.

[0009] Furthermore, the first wheel turning angle sensor and the second wheel turning angle sensor use a single-turn absolute encoder to provide feedback on the wheel deflection angle for closed-loop control of the wheel deflection.

[0010] Furthermore, the first steering wheel angle sensor and the second steering wheel angle sensor are multi-turn absolute encoders; the first steering wheel angle sensor is used to provide feedback on the first steering wheel angle for steering control of the first steering drive axle; the second steering wheel angle sensor is used to provide feedback on the second steering wheel angle for steering control of the second steering drive axle.

[0011] Furthermore, the first limiting device is used to limit the number of rotations of the first steering wheel; and the second limiting device is used to limit the number of rotations of the second steering wheel.

[0012] A control method for a steering system of a dual-cab two-axle electric logistics vehicle of the present invention is characterized by comprising the following steps: aThe driver controls the vehicle to start; the integrated controller, vehicle controller, and BMS integrated in the power battery are powered on and start self-checking; after the self-checking passes, the vehicle controller controls the high voltage on the integrated controller, and the DC / AC module in the integrated controller controls the operation of the electric steering pump. The hydraulic oil in the steering tank flows to the proportional solenoid valve through the high-pressure filter and then back to the steering tank through the electric steering pump, preparing for steering; the DC / DC module in the integrated controller charges the 24V battery; b. The driver controls the vehicle to perform logistics tasks; the driver is located in the first cab and turns the first steering wheel. The first steering wheel angle sensor detects the rotation angle of the first steering wheel and transmits it to the vehicle controller via the CAN line. After receiving the information from the first steering wheel angle sensor, the vehicle controller communicates with the proportional solenoid valve to control the first control circuit of the proportional solenoid valve to operate, thereby controlling the extension and contraction of the first steering cylinder to drive the wheel deflection of the first steering drive axle to achieve vehicle steering or wheel return. The first wheel angle sensor monitors the wheel angle of the first steering drive axle in real time and transmits the angle information to the vehicle controller; during this process, the vehicle controller ensures that the number of rotations of the first steering wheel corresponds to the degree of wheel deflection of the first steering drive axle by real-time monitoring of the data of the first steering wheel angle sensor and the first wheel angle sensor; at the same time, the wheels of the second steering drive axle are controlled to be in the zero offset position through the data detected by the second wheel angle sensor; the first limit device limits the number of rotations of the first steering wheel; The driver is located in the second cab and turns the second steering wheel. The second steering wheel angle sensor detects the rotation angle of the second steering wheel and transmits it to the vehicle controller via the CAN line. After receiving the information from the second steering wheel angle sensor, the vehicle controller communicates with the proportional solenoid valve to control the action of the second control circuit of the proportional solenoid valve, thereby controlling the extension and retraction of the second steering cylinder to drive the wheel deflection of the second steering drive axle to achieve vehicle steering or wheel return. The second wheel angle sensor monitors the wheel angle of the second steering drive axle in real time and transmits the angle information to the vehicle controller. During this process, the vehicle controller ensures that the number of rotations of the second steering wheel corresponds to the degree of wheel deflection of the second steering drive axle by real-time monitoring the data of the second steering wheel angle sensor and the second wheel angle sensor. At the same time, the wheels of the first steering drive axle are controlled to be in the zero offset position through the data detected by the first wheel angle sensor. The second limit device limits the number of rotations of the second steering wheel.

[0013] Beneficial effects of the present invention: 1. The steering control of the dual-cab electric logistics vehicle is realized in a simple and easy-to-control way, reducing the cost of logistics vehicles; 2. The wire-controlled steering adopts a proportional solenoid valve as the control valve, which can conveniently control the valve core opening according to the steering wheel rotation speed and then control the oil flow rate of the steering cylinder to achieve variable speed control of the steering cylinder action speed; based on the separate control of the front and rear steering cylinders, two steering modes, single-axis deflection wheel steering and two-axle wheel simultaneous deflection steering, can be realized with strong controllability; when the two-axle wheels are deflected and steered at the same time, the vehicle's turning radius is reduced, the curve passing ability is improved, and the performance is enhanced; 3. Based on multi-sensor feedback and combined with the steering control process, the vehicle steering is ensured to be accurate, making the entire steering control process more adaptive and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a system block diagram of the present invention; Figure 2 is a top view schematic diagram of the present invention installed on a vehicle; Figure 3 is a side view schematic diagram of the present invention installed on a vehicle; Figure 4 It is a schematic diagram of the connection between the steering oil cylinder and the steering drive axle of the present invention; Figure 5 It is a schematic diagram of the installation position of the angle sensor of the present invention.

[0015] Wherein: 1 steering oil tank, 2 electric steering pump, 3 high pressure filter, 4 proportional solenoid valve, 5 integrated controller, 6 vehicle controller, 724V battery, 8 power battery, 9 first steering wheel, 10 first steering column, 11 first steering wheel angle sensor, 12 first steering cylinder, 13 first wheel angle sensor, 14 first steering drive axle, 15 second steering wheel, 16 second steering column, 17 second steering wheel angle sensor, 18 second steering cylinder, 19 second wheel angle sensor, 20 second steering drive axle, 21 first limit device, 22 first limit device. DETAILED DESCRIPTION

[0016] For better understanding and implementation, the present invention is further described in detail below with reference to the accompanying drawings.

[0017] like Figure 1 , 2 , 3, 4, and 5, a steering system for a dual-cab two-axle electric logistics vehicle comprises a steering oil tank 1, an electric steering pump 2, a high-pressure filter 3, a proportional solenoid valve 4, an integrated controller 5, a vehicle controller 6, a 24V battery 7, a power battery 8, a first steering wheel 9, a first steering column 10, a first steering wheel angle sensor 11, a first steering cylinder 12, a first wheel angle sensor 13, a first steering drive axle 14, a second steering wheel 15, a second steering column 16, a second steering wheel angle sensor 17, a second steering cylinder 18, a second wheel angle sensor 19, a second steering drive axle 20, a first limit device 21, and a first limit device 22; The integrated controller 5 includes at least one high-voltage power distribution module, one DC / AC module, and one DC / DC module; the power battery 8 outputs high-voltage direct current to the high-voltage power distribution module in the integrated controller 5, and the high-voltage power distribution module distributes the high-voltage direct current to the DC / AC module and the DC / DC module. The DC / AC module outputs high-voltage alternating current to the electric steering pump 2, and the DC / DC module provides a stable low-voltage direct current power supply to the vehicle electrical components while charging the 24V battery 7; The proportional solenoid valve 3 is a multi-module assembly valve group controlled by CAN communication, which includes two control circuits. The first control circuit controls the action of the first steering cylinder 12, and the second control circuit controls the action of the second steering cylinder 18, so as to realize independent control of the wheels of the first steering drive axle 14 and the second steering drive axle 20 when the vehicle is turning; The first wheel angle sensor 13 and the second wheel angle sensor 19 use a single-turn absolute encoder to provide feedback on the wheel deflection angle for closed-loop control of the wheel deflection; The first steering wheel angle sensor 11 and the second steering wheel angle sensor 17 are multi-turn absolute encoders; the first steering wheel angle sensor 11 is used to provide feedback on the angle of the first steering wheel 9 for steering control of the first steering drive axle 14; the second steering wheel angle sensor 17 is used to provide feedback on the angle of the second steering wheel 15 for steering control of the second steering drive axle 20; The first limit device 21 is used to limit the number of rotations of the first steering wheel 9; the second limit device 22 is used to limit the number of rotations of the second steering wheel 15; The steering oil tank 1, the electric steering pump 2, the high-pressure filter 3, the proportional solenoid valve 4, the integrated controller 5, the vehicle controller 6, the 24V battery 7, the power battery 8, the first steering drive axle 14, and the second steering drive axle 20 are respectively connected to the frame of the double-cab two-axle electric vehicle; the first steering wheel 9 and the first steering column 10 are installed in the first cab of the vehicle; the first steering wheel angle sensor 11 is fixedly connected to the first steering column 10; the first limit device 21 is fixedly connected to the first steering column 10; the second steering wheel 15 and the second steering column 16 are installed in the second cab of the vehicle; the second steering wheel angle sensor 17 is connected to the second The steering column 16 is fixedly connected; the second limit device 22 is fixedly connected to the second + steering column 16; the first wheel angle sensor 13 is installed in the first steering drive axle 14; the second wheel angle sensor 19 is installed in the second steering drive axle 20; the fixed end of the first steering cylinder 13 is connected to the axle housing of the first steering drive axle 14 of the electric vehicle, and the extended end of the first steering cylinder 12 is connected to the steering knuckle arm of the first steering drive axle 14; the fixed end of the second steering cylinder 18 is connected to the axle housing of the second steering drive axle 20 of the electric logistics vehicle, and the extended end of the second steering cylinder 18 is connected to the steering knuckle arm of the second steering drive axle 20; The steering oil tank 1 is connected to the oil inlet of the electric steering pump 2 through the oil inlet pipeline; the oil outlet of the electric steering pump 2 is connected to the oil inlet of the high-pressure filter 3 through the high-pressure pipeline; the oil outlet of the high-pressure filter 3 is connected to the oil inlet of the proportional solenoid valve 4; the oil return port of the proportional solenoid valve 4 is connected to the steering oil tank 1 through the oil return pipeline; the proportional solenoid valve 4 includes two control circuits, the A1 and B1 ports of the first control circuit are connected to the oil ports of the rodless chamber and the rod chamber of the first steering cylinder 12 through the high-pressure pipeline, and the A2 and B2 ports of the second control circuit of the proportional solenoid valve 4 are connected to the oil ports of the rod chamber and the rodless chamber of the second steering cylinder 18 through the high-pressure pipeline. The electric steering pump 2 is electrically connected to the integrated controller via a high-voltage line; the integrated controller 5 is electrically connected to the power battery 8 via a high-voltage line; The proportional solenoid valve 4, the integrated controller 5, the vehicle controller 6, the power battery 8, the first steering wheel angle sensor 11, the first wheel angle sensor 13, the second steering wheel angle sensor 17, and the second wheel angle sensor 19 are electrically connected to the 24V battery 7 via a low-voltage power line, and the proportional solenoid valve 4, the integrated controller 5, the vehicle controller 6, the power battery 8, the first steering wheel angle sensor 11, the first wheel angle sensor 13, the second steering wheel angle sensor 17, and the second wheel angle sensor 19 are connected to the vehicle CAN line via a CAN line.

[0018] The present invention discloses a steering system for a dual-cab two-axle electric logistics vehicle, wherein a steering oil tank 1 is used to store hydraulic oil; an electric steering pump 2 pressurizes the hydraulic oil in the steering oil tank 1 and transmits it to a proportional solenoid valve 4; the proportional solenoid valve 4 controls the flow direction of the high-pressure oil and controls the actions of the first steering oil cylinder 12 and the second steering oil cylinder 18; the first steering oil cylinder 12 is extended and retracted under the action of the high-pressure oil to drive the wheel deflection of the first steering drive axle 14, and the second steering oil cylinder 18 is extended and retracted under the action of the high-pressure oil to drive the wheel deflection of the second steering drive axle 20; an integrated controller 5 controls the operation of the electric steering pump 2; a vehicle controller 6 receives and processes information from a steering wheel angle sensor 11 and a second steering wheel angle sensor 17 to control the action of the proportional solenoid valve 4 and thus control the steering of the vehicle; a 24V battery 7 provides a low-voltage power supply to the steering system electrical appliances; a power battery 8 provides a high-voltage power supply to the integrated controller 5; a first wheel angle sensor 13 detects the wheel angle of the first steering drive axle 14 and transmits the angle information to the vehicle controller 6, and a second wheel angle sensor 19 detects the wheel angle of the second steering drive axle 20 and transmits the angle information to the vehicle controller 6.

[0019] A control method for a steering system of a dual-cab two-axle electric logistics vehicle of the present invention specifically comprises the following steps: a The driver controls the vehicle to start; the 24V battery 7 provides 24V power to the proportional solenoid valve 4, the integrated controller 5, the vehicle controller 6, the power battery 8, the first steering wheel angle sensor 11, the first wheel angle sensor 13, the second steering wheel angle sensor 17, and the second wheel angle sensor 19, and the integrated controller 5, the vehicle controller 6, and the BMS integrated in the power battery 8 start and self-check; after the self-check passes, the vehicle controller 6 controls the high voltage on the integrated controller 5, and the DC / AC module in the integrated controller 5 controls the operation of the electric steering pump 2, and the hydraulic oil in the steering tank 1 flows to the proportional solenoid valve 4 after the action of the electric steering pump 2 and the high-pressure filter 3, and then flows back to the steering tank 1, so as to prepare for steering, and at the same time, the DC / DC module in the integrated controller 5 charges the 24V battery; b The driver controls the vehicle to perform logistics tasks; when the driver is in the first cab, he turns the first steering wheel 9 according to control needs, and the first steering wheel angle sensor 11 detects the rotation angle of the first steering wheel 9 and transmits it to the vehicle controller 6 via the CAN line. After receiving the information from the first steering wheel angle sensor 11, the vehicle controller 6 communicates with the proportional solenoid valve 4 to control the operation of the proportional solenoid valve 4. The proportional solenoid valve 4 controls the flow direction of the high-pressure oil from the electric steering pump 2 to control the first steering cylinder 12. The first steering cylinder 12 expands and contracts under the action of the high-pressure oil to drive the wheel deflection of the first steering drive axle 14 to achieve vehicle steering or wheel return. The first wheel angle sensor 13 monitors the first steering drive axle in real time. 14 wheel angle and transmits the angle information to the vehicle controller 6. During this process, the vehicle controller 6 ensures that the number of turns of the first steering wheel 9 corresponds to the wheel deflection degree of the first steering drive axle 14 by real-time monitoring the data of the first steering wheel angle sensor 11 and the first wheel angle sensor 13. At the same time, the data detected by the second wheel angle sensor 19 controls the wheels of the second steering drive axle 20 to be in a zero-bias position, which conforms to the conventional driving habit of controlling the cab to steer the nearest axle; the existence of the first limit device 21 limits the number of turns of the first steering wheel 9. At the same time, the more the first steering wheel 9 rotates in one direction, the greater the damping force, which prompts the driver to have a clear understanding of the number of turns and wheel angles; When the driver is in the second cab, he turns the second steering wheel 15 according to control needs. The second steering wheel angle sensor 17 detects the rotation angle of the second steering wheel 15 and transmits it to the vehicle controller 6 via the CAN line. After receiving the information from the second steering wheel angle sensor 17, the vehicle controller 6 communicates with the proportional solenoid valve 4 to control the action of the proportional solenoid valve 4. The proportional solenoid valve 4 controls the flow direction of the high-pressure oil from the electric steering pump 2 to control the second steering cylinder 18. The second steering cylinder 18 retracts and contracts under the action of the high-pressure oil to drive the wheel deflection of the second steering drive axle 20 to achieve vehicle steering or wheel return. The second wheel angle sensor 19 monitors the wheel angle of the second steering drive axle 20 in real time and The steering angle information is transmitted to the vehicle controller 6; during this process, the vehicle controller 6 ensures that the number of turns of the second steering wheel 15 corresponds to the degree of wheel deflection of the second steering drive axle 20 by real-time monitoring the data of the second steering wheel angle sensor 17 and the second wheel angle sensor 19. At the same time, the data detected by the first wheel angle sensor 13 controls the wheels of the first steering drive axle 14 to be in a zero-bias position, which conforms to the conventional driving habit of controlling the cab to steer the nearest axle; the presence of the second limit device 22 limits the number of turns of the second steering wheel 15. At the same time, the more the second steering wheel 15 turns in one direction, the greater the damping force, which prompts the driver to have a clear understanding of the number of steering turns and wheel angles.

[0020] The above specific implementation methods are further detailed descriptions of the present invention, and it cannot be determined that the specific embodiments of the present invention are limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, and the above structures should be regarded as belonging to the protection scope of the present invention.

Claims

1. A steering system for a dual-cab, two-axle electric logistics vehicle, characterized in that: It is composed of a steering oil tank (1), an electric steering pump (2), a high-pressure filter (3), a proportional solenoid valve (4), an integrated controller (5), a vehicle controller (6), a 24V storage battery (7), a power battery (8), a first steering wheel (9), a first steering column (10), a first steering wheel angle sensor (11), a first steering oil cylinder (12), a first wheel angle sensor (13), a first steering drive axle (14), a second steering wheel (15), a second steering column (16), a second steering wheel angle sensor (17), a second steering oil cylinder (18), a second wheel angle sensor (19), a second steering drive axle (20), a first limit device (21), and a second limit device (22); The steering oil tank (1), the electric steering pump (2), the high-pressure filter (3), the proportional solenoid valve (4), the integrated controller (5), the vehicle controller (6), the 24V storage battery (7), the power battery (8), the first steering drive axle (14), and the second steering drive axle (20) are respectively connected to the frame of the double-cab two-axle electric vehicle; the first steering wheel (9) and the first steering column (10) are installed in the first cab of the vehicle; the first steering wheel angle sensor (11) is fixedly connected to the first steering column (10); the first limit device (21) is fixedly connected to the first steering column (10); the second steering wheel (15) and the second steering column (16) are installed in the second cab of the vehicle; the second steering wheel angle sensor (1 7) is fixedly connected to the second steering column (16); the second limit device (22) is fixedly connected to the second steering column (16); the first wheel angle sensor (13) is installed in the first steering drive axle (14); the second wheel angle sensor (19) is installed in the second steering drive axle (20); the fixed end of the first steering cylinder (12) is connected to the bridge housing of the first steering drive axle (14) of the electric vehicle, and the extended end of the first steering cylinder (12) is connected to the steering knuckle arm of the first steering drive axle (14); the fixed end of the second steering cylinder (18) is connected to the bridge housing of the second steering drive axle (20) of the electric logistics vehicle, and the extended end of the second steering cylinder (18) is connected to the steering knuckle arm of the second steering drive axle (20); The steering oil tank (1) is connected to the oil inlet of the electric steering pump (2) via an oil inlet pipeline; the oil outlet of the electric steering pump (2) is connected to the oil inlet of the high-pressure filter (3) via a high-pressure pipeline; the oil outlet of the high-pressure filter (3) is connected to the oil inlet of the proportional solenoid valve (4); the oil return port of the proportional solenoid valve (4) is connected to the steering oil tank (1) via the oil return pipeline; the proportional solenoid valve (4) comprises two control circuits, the A1 and B1 ports of the first control circuit are connected to the oil ports of the rodless chamber and the rod chamber of the first steering cylinder (12) via a high-pressure pipeline, respectively, and the A2 and B2 ports of the second control circuit of the proportional solenoid valve (4) are connected to the oil ports of the rod chamber and the rodless chamber of the second steering cylinder (18) via a high-pressure pipeline, respectively. The electric steering pump (2) is electrically connected to an integrated controller (5) via a high-voltage line, and the integrated controller (5) is connected to a power battery (8) via a high-voltage line; The electronic control module of the proportional solenoid valve (4), the integrated controller (5), the vehicle controller (6), the power battery (8), the first steering wheel angle sensor (11), the first wheel angle sensor (13), the second steering wheel angle sensor (17), and the second wheel angle sensor (19) are electrically connected to the 24V battery (7) via a low-voltage power line, and the electronic control module of the proportional solenoid valve (4), the integrated controller (5), the vehicle controller (6), the power battery (8), the first steering wheel angle sensor (11), the first wheel angle sensor (13), the second steering wheel angle sensor (17), and the second wheel angle sensor (19) are connected to the vehicle CAN line via a CAN line.

2. The steering system of a dual-cab two-axle electric logistics vehicle according to claim 1, characterized in that: The integrated controller (5) comprises at least one high-voltage power distribution module, one DC / AC module, and one DC / DC module; the power battery (8) outputs high-voltage direct current to the high-voltage power distribution module in the integrated controller (5); the high-voltage power distribution module distributes the high-voltage direct current to the DC / AC module and the DC / DC module; the DC / AC module outputs high-voltage alternating current to the electric steering pump (2); the DC / DC module provides a stable low-voltage direct current power supply to the vehicle electrical components while charging the 24V storage battery (7).

3. The steering system of a dual-cab two-axle electric logistics vehicle according to claim 1, characterized in that: The proportional solenoid valve (3) is a multi-module assembly valve group controlled by CAN communication, comprising two control circuits, wherein the first control circuit controls the action of the first steering cylinder (12), and the second control circuit controls the action of the second steering cylinder (18), thereby realizing independent control of the wheels of the first steering drive axle (14) and the second steering drive axle (20) when the vehicle is turning.

4. The steering system of a dual-cab two-axle electric logistics vehicle according to claim 1, characterized in that: The first wheel rotation angle sensor (13) and the second wheel rotation angle sensor (19) use a single-turn absolute value encoder to provide feedback on the wheel deflection angle for closed-loop control of the wheel deflection.

5. The steering system of a dual-cab two-axle electric logistics vehicle according to claim 1, characterized in that: The first steering wheel angle sensor (11) and the second steering wheel angle sensor (17) are multi-turn absolute encoders; the first steering wheel angle sensor (11) is used to provide feedback on the angle of the first steering wheel (9) for steering control of the first steering drive axle (14); the second steering wheel angle sensor (17) is used to provide feedback on the angle of the second steering wheel (15) for steering control of the second steering drive axle (20).

6. The steering system of a dual-cab two-axle electric logistics vehicle according to claim 1, characterized in that: The first limiting device (21) is used to limit the number of rotations of the first steering wheel (9); and the second limiting device (22) is used to limit the number of rotations of the second steering wheel (15).

7. The control method of the steering system of a dual-cab two-axle electric logistics vehicle according to any one of claims 1 to 6, characterized in that: The following steps are involved: a. The driver controls the vehicle to start; the integrated controller (5), the vehicle controller (6), and the BMS integrated in the power battery (8) are powered on and start and self-check; after the self-check is passed, the vehicle controller (6) controls the integrated controller (5) to supply high voltage, and the DC / AC module in the integrated controller (5) controls the electric steering pump (2) to operate, and the hydraulic oil in the steering oil tank (1) flows to the proportional solenoid valve (4) after the action of the electric steering pump (2) and passes through the high-pressure filter (3) and then flows back to the steering oil tank (1), so as to prepare for steering; the DC / DC module in the integrated controller (5) charges the 24V battery; b. The driver controls the vehicle to perform logistics tasks; the driver is located in the first cab and turns the first steering wheel (9); the first steering wheel angle sensor (11) detects the rotation angle of the first steering wheel (9) and transmits the information to the vehicle controller (6) via the CAN line; after receiving the information from the first steering wheel angle sensor (11), the vehicle controller (6) communicates with the proportional solenoid valve (4) to control the first control circuit of the proportional solenoid valve (4) to operate, thereby controlling the first steering oil cylinder (12) to extend and retract to drive the wheel of the first steering drive axle (14) to deflect, thereby realizing vehicle steering or wheel return; the first wheel angle sensor (13) real-time monitoring of the wheel angle of the first steering drive axle (14) and transmitting the angle information to the vehicle controller (6); in this process, the vehicle controller (6) ensures that the number of rotations of the first steering wheel (9) corresponds to the degree of wheel deflection of the first steering drive axle (14) by real-time monitoring of the data of the first steering wheel angle sensor (11) and the first wheel angle sensor (13); at the same time, the wheel of the second steering drive axle (20) is controlled to be in a zero-bias position through the data detected by the second wheel angle sensor (19); the first limit device (21) limits the number of rotations of the first steering wheel (9); The driver is located in the second driving cab and turns the second steering wheel (15); the second steering wheel angle sensor (17) detects the rotation angle of the second steering wheel (15) and transmits the rotation angle to the vehicle controller (6) via a CAN line; after receiving the information from the second steering wheel angle sensor (17), the vehicle controller (6) communicates with the proportional solenoid valve (4) to control the operation of the second control circuit of the proportional solenoid valve (4), thereby controlling the extension and retraction of the second steering oil cylinder (18) to drive the wheel deflection of the second steering drive axle (20), thereby achieving vehicle steering or wheel return; the second wheel angle sensor (19) monitors the wheel angle of the second steering drive axle (20) in real time and transmits the angle information to the vehicle controller (6). During this process, the vehicle controller (6) ensures that the number of revolutions of the second steering wheel (15) corresponds to the degree of wheel deflection of the second steering drive axle (20) by real-time monitoring the data of the second steering wheel angle sensor (17) and the second wheel angle sensor (19); at the same time, the wheels of the first steering drive axle (14) are controlled to be in a zero-bias position through the data detected by the first wheel angle sensor (13). The second limit device (22) limits the number of revolutions of the second steering wheel (15).

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