A trailer rear axle braking energy recovery and auxiliary steering system and a control method thereof

Abstract

The application provides a trailer rear axle brake energy recovery and auxiliary steering system and a control method thereof, which comprises a detection unit, a control unit and an execution unit; the detection unit detects vehicle information, and the vehicle information comprises a brake signal, a steering wheel angle signal, a motor current / torque signal, a vehicle speed signal, a rear wheel angle signal and a battery SOC signal; the control unit allocates a working mode of the vehicle at the next moment according to the vehicle information and generates a control instruction; and the execution unit comprises a motor for executing the brake energy recovery mode or the rear axle auxiliary steering mode, and executes the vehicle control instruction according to the vehicle mode at the next moment. The application realizes the functions of brake energy recovery and rear axle auxiliary steering by using a single motor, which is helpful to realize the lightweight of the vehicle. Moreover, the maneuverability, the steering lightness, the driving stability and the energy recovery efficiency of the vehicle are significantly improved, so that the performance characteristics of the vehicle are comprehensively improved, and the range of the overall vehicle performance is widened.

Description

Technical Field

[0001] This invention belongs to the field of chassis control technology, and in particular relates to a trailer rear axle braking energy recovery and auxiliary steering system and its control method. Background Technology

[0002] New chassis configurations and control technologies are key technologies for realizing the intelligent development of automobiles. Core technologies in this area include brake energy recovery and rear axle assisted steering. These innovative configurations and advanced control technologies provide crucial support for improving vehicle performance, efficiency, and driving experience.

[0003] Vehicle regenerative braking technology is one of the key energy-saving and environmentally friendly technologies in the automotive industry. Its main purpose is to reduce energy waste, improve overall energy efficiency, and lower vehicle emissions through effective energy recovery. During braking, this technology converts a portion of the braking energy into electrical energy, which is then stored for acceleration or other applications when needed. Vehicle regenerative braking technology also positively impacts vehicle performance and driving experience. By converting braking energy into reusable electrical energy, it not only improves vehicle energy efficiency but also helps reduce carbon emissions. Therefore, the application of vehicle regenerative braking technology is not only significant for the sustainable development of the automotive industry but also provides drivers with a more environmentally friendly and enjoyable driving experience.

[0004] Rear-axle steering is an advanced technology that uses an electric drive mechanism to control the steering of the vehicle's rear wheels. The core of this technology lies in achieving precise control of the rear wheels through an electric actuator. Its main goal is to improve the overall stability and handling of the vehicle, thereby significantly enhancing driving safety and ride comfort. With rear-axle steering, the vehicle can more flexibly handle various driving situations. This includes improved stability at high speeds, reducing body roll caused by sharp turns, and increased handling at low speeds, making it easier for the driver to drive and park. Furthermore, this technology has significant advantages in improving driving safety, especially in dangerous situations such as sharp turns and emergency avoidance, effectively mitigating the vehicle's tendency to skid and reducing the risk of potential accidents. In terms of environmental protection, rear-axle steering can also reduce tire wear, thereby extending tire life, and by optimizing vehicle trajectory, reduce energy consumption, thus positively impacting the sustainability of automobiles.

[0005] However, existing technologies primarily focus on single research directions such as regenerative braking or rear-axle steering, lacking research on structural devices or related technologies that integrate these two technologies. In existing technologies, each technology is often studied and described independently, lacking in-depth analysis of their synergistic effects and overall impact within a holistic system. Therefore, a comprehensive research framework has not yet been established to effectively integrate regenerative braking and rear-axle steering technologies, thereby achieving a more comprehensive and synergistic improvement in vehicle dynamics performance.

[0006] Especially on trailers, a lot of kinetic energy is consumed during braking, making it extremely difficult to turn at low speeds or even make U-turns. Good driving stability is also required at high speeds. Therefore, it is especially necessary to improve its energy utilization, steering ease and driving stability. Summary of the Invention

[0007] To address the aforementioned technical problems, one objective of this invention is to provide a rear axle brake energy recovery and auxiliary steering system for trailers. This system utilizes a single motor to achieve both brake energy recovery and rear axle auxiliary steering, contributing to vehicle weight reduction. Furthermore, by significantly improving vehicle maneuverability, handling ease, driving stability, and energy recovery efficiency, it comprehensively enhances vehicle performance characteristics, thereby broadening the overall performance range of the vehicle.

[0008] One objective of this invention is to provide a control method for a rear axle brake energy recovery and auxiliary steering system of a trailer. By detecting vehicle information and allocating different working modes, the two functions of brake energy recovery and rear axle auxiliary steering are effectively combined to achieve better driving stability and efficient energy recovery.

[0009] Note that the description of these objectives does not preclude the existence of other objectives. One aspect of the invention does not require achieving all of the above objectives. Objectives other than those described above can be extracted from the description, drawings, and claims.

[0010] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0011] A trailer rear axle brake energy recovery and auxiliary steering system includes a detection unit, a control unit, and an execution unit;

[0012] The detection unit is used to detect vehicle information, which includes braking signals, steering wheel angle signals, motor current / torque signals, vehicle speed signals, rear wheel angle signals, and battery state of charge signals.

[0013] The control unit is connected to the detection unit and the execution unit respectively, and is used to allocate the vehicle's working mode for the next moment and generate control commands according to the vehicle information. The vehicle's working modes include normal mode, brake energy recovery mode and rear axle auxiliary steering mode.

[0014] The execution unit includes a motor that executes either a regenerative braking mode or a rear axle assisted steering mode. It is used to execute vehicle control commands according to the assigned vehicle mode for the next moment. When the vehicle enters the regenerative braking mode, the wheels drive the motor to rotate and the motor charges the battery. When the vehicle enters the rear axle assisted steering mode, the battery supplies power to the motor and the motor drives the wheels to assist in steering.

[0015] In the above scheme, the detection unit includes a brake pedal sensor, a steering wheel angle sensor, a motor current / torque sensor, a vehicle speed sensor, a rear wheel angle sensor, and a SOC sensor;

[0016] The brake pedal signal is used to detect the vehicle's brake pedal signal;

[0017] The steering wheel angle sensor is used to detect the steering wheel angle signal of the vehicle.

[0018] The motor current / torque sensor is used to detect the motor's current and torque;

[0019] The vehicle speed sensor detects the vehicle's speed signal;

[0020] The rear wheel steering angle sensor includes a left rear wheel steering angle sensor and a right rear wheel steering angle sensor. The left rear wheel steering angle sensor is used to detect the steering angle of the left rear wheel, and the right rear wheel steering angle sensor is used to detect the steering angle of the right rear wheel.

[0021] The SOC sensor is used to detect the battery's state of charge.

[0022] In the above scheme, the control unit includes an input module, a judgment module, and an output module;

[0023] The input module is used to receive vehicle information detected by the detection unit;

[0024] The judgment module is used to compare the vehicle information with preset conditions, determine whether the preset conditions are met, and generate a judgment result.

[0025] The output module is used to generate corresponding vehicle control commands based on the judgment result and output them to the actuator.

[0026] Furthermore, the judgment module compares the vehicle information with preset conditions to determine whether the preset conditions are met, and generates a judgment result, specifically including:

[0027] First condition: If the brake signal opening is 1, i.e., there is braking behavior, and the vehicle speed is greater than or equal to u, and the battery state of charge signal is less than SOC. 回收 Preset value, i.e., battery level below SOC. 回收 If the preset value is met, the result will be to enter the regenerative braking mode;

[0028] Second condition: If the first condition is not met, and the steering wheel angle is greater than or equal to δ, then the judgment result is to enter the rear axle auxiliary steering mode;

[0029] Third condition: If neither the first nor the second condition is met, then the system is judged to enter normal mode.

[0030] In the above scheme, the execution unit includes a symmetrically arranged fixed bushing, a steering tie rod, a gear and rack mechanism, a motor controller, a steering knuckle mechanism, a universal joint mechanism, a first clutch, a motor, a second clutch, a sector gear mechanism, and a battery;

[0031] The fixed bushing has a slot along the axial direction, and a gear and rack mechanism is provided at the slot.

[0032] The gear and rack mechanism is connected to one end of the steering tie rod;

[0033] The other end of the steering tie rod is connected to the steering knuckle mechanism;

[0034] One end of the steering knuckle mechanism is connected to the wheel, and the other end is connected to the universal joint mechanism, which is used to control the wheel's turning angle;

[0035] The other end of the universal joint mechanism is connected to one end of the first clutch, and is used to transmit power from the first clutch to the wheel;

[0036] The other end of the first clutch is connected to the motor and is used to control the power connection status between the motor and the wheel;

[0037] The other end of the motor is connected to one end of the second clutch, and the other end of the second clutch is connected to one end of the sector gear mechanism, which is used to control the power connection state between the motor and the sector gear mechanism.

[0038] The motor is also connected to a battery and a motor controller; the motor controller is also connected to a control unit and is used to control the motor torque; the battery is used to power the motor or to charge the motor.

[0039] The other end of the sector gear mechanism is connected to the gear and rack mechanism, which is used to transmit the power of the motor to the gear and rack mechanism and control the steering tie rod to move along the axial direction on the fixed bushing.

[0040] Furthermore, the execution unit executes vehicle control commands according to the allocated next-moment vehicle mode, including:

[0041] When the vehicle enters the regenerative braking mode, the first clutch engages and the second clutch disengages. The wheels drive the motor to rotate through the first clutch, and the motor charges the battery.

[0042] When the vehicle enters the rear axle assisted steering mode, the first clutch is disengaged and the second clutch is engaged. The battery powers the motor, which drives the steering tie rod to move along the axial direction on the fixed axle sleeve through the sector gear mechanism and the rack and pinion mechanism. The motor drives the wheels to assist in steering.

[0043] Furthermore, the rear axle assisted steering mode also includes a first mode and a second mode;

[0044] The first mode condition is that the vehicle speed is less than u. In this mode, the motor controller controls the motor, causing the steering tie rod to move away from the center of the fixed bushing.

[0045] The second mode condition is that the vehicle speed is greater than u. In this mode, the motor controller controls the motor, causing the steering tie rod to move towards the center of the fixed bushing.

[0046] A control method for the above-mentioned trailer rear axle brake energy recovery and auxiliary steering system includes the following methods:

[0047] Step S1: The detection unit is used to detect vehicle information, which includes braking signal, steering wheel angle signal, motor current / torque signal, vehicle speed signal, rear wheel angle signal and battery state of charge signal;

[0048] Step S2: Allocate the vehicle's operating mode for the next moment based on the vehicle information and generate control commands. The vehicle's operating modes include normal mode, regenerative braking mode, and rear axle steering assist mode.

[0049] Step S3: Execute vehicle control commands according to the allocated vehicle mode for the next moment. When the vehicle enters the regenerative braking mode, the wheels drive the motor to rotate and the motor charges the battery. When the vehicle enters the rear axle assisted steering mode, the battery supplies power to the motor and the motor drives the wheels to assist in steering.

[0050] The control method for the regenerative braking mode in the above scheme includes the following steps:

[0051] The detection unit detects the brake pedal signal, vehicle speed signal, and SOC signal, and transmits them to the control unit;

[0052] The control unit determines whether the conditions for entering the regenerative braking mode are met based on the input brake pedal signal, vehicle speed signal, and SOC signal. When the conditions for entering the regenerative braking mode are met, the clutch connecting the motor and the wheel engages, causing the rear axle to drive the motor to rotate through the clutch. When the conditions for entering the regenerative braking mode are not met, the regenerative braking mode is either not entered or exited.

[0053] The battery SOC signal is returned to the signal detection unit, which then sends it to the control unit. The control unit then re-determines whether the conditions for entering the regenerative braking mode are met.

[0054] The control method for the rear axle auxiliary steering mode in the above scheme includes the following steps:

[0055] The detection unit detects the steering wheel angle signal, the motor current / torque signal, the vehicle speed signal, and the rear wheel angle signal, and transmits them to the control unit;

[0056] The control unit determines whether the entry conditions for the rear axle auxiliary steering mode are met based on the input steering wheel angle signal, motor current / torque signal, vehicle speed signal, and rear wheel angle signal. When the entry conditions are met, further calculations are performed to determine the motor torque signal to be sent to the motor controller. Then, the motor adjusts the rear wheel posture. At the same time, the clutch connecting the motor and the sector gear mechanism engages during this process. The control unit controls the motor through the motor controller to drive the rear axle wheels to achieve auxiliary steering.

[0057] The motor's current / torque signal and the rear wheel steering angle signal are returned to the control unit, which then re-determines whether the conditions for entering the rear axle auxiliary steering mode are met.

[0058] Compared with the prior art, the beneficial effects of the present invention are:

[0059] According to one aspect of the present invention, two functions are achieved by a single motor: regenerative braking and rear axle assisted steering. This not only improves the overall performance of the vehicle but also contributes to the achievement of the vehicle's lightweighting goal.

[0060] According to one aspect of the present invention, in the braking energy recovery mode, the motor is used to recover energy, converting the kinetic energy generated during braking into electrical energy, which not only improves energy utilization efficiency but also helps to reduce carbon emissions.

[0061] According to one aspect of the present invention, in the rear axle assisted steering mode, when the vehicle speed is less than a preset value u, the vehicle is in low-speed steering. The motor controller controls the motor to distribute different torques, and the rear axle wheels are biased towards steering ease. The two steering tie rods move away from the center of the fixed axle sleeve, and the left and right rear axle wheels are in an outward yaw posture. Combined with the inward yaw posture of the front wheels, the vehicle can make a U-turn in a narrow and limited space. It can also achieve faster and smaller turning radius cornering when making low-speed left and right turns, with the rear wheels rotating in the opposite direction to the front wheels.

[0062] According to one aspect of the present invention, in the rear axle assisted steering mode, when the vehicle speed is greater than or equal to a preset value u, the motor controller controls the motor to distribute different torques, the rear axle wheels are steered towards driving stability, the two steering tie rods should move towards the center of the fixed axle sleeve, the left and right rear axle wheels are in an "inward" posture, the driving stability of the vehicle when driving straight at high speed is improved, and in emergency obstacle avoidance conditions, the rear wheels can also steer in the same direction as the front wheels, reducing body roll and instability, and helping to improve the stability and controllability of the vehicle.

[0063] Note that the description of these effects does not preclude the existence of other effects. One aspect of the invention does not necessarily have all the aforementioned effects. Effects other than those described above can be readily observed and extracted from the description, drawings, claims, etc. Attached Figure Description

[0064] Figure 1 This is a schematic diagram of one embodiment of the present invention.

[0065] Figure 2 This is a schematic diagram of the execution unit structure according to an embodiment of the present invention.

[0066] Figure 3 This is a logic diagram of a control unit according to an embodiment of the present invention.

[0067] Figure 4 This is a schematic diagram of the electrical energy that can be recovered in 2500s under the braking energy recovery mode of the present invention in the C-WTVC condition according to one embodiment of the present invention.

[0068] Figure 5 This is a schematic diagram comparing the SOC values ​​of a vehicle in regenerative braking mode and a vehicle without regenerative braking control under the C-WTVC condition according to an embodiment of the present invention within 2500s.

[0069] Figure 6 This is a schematic diagram of a vehicle in the first mode under the rear axle assisted steering mode according to an embodiment of the present invention.

[0070] Figure 7 This is a schematic diagram of the emergency obstacle avoidance working condition according to one embodiment of the present invention.

[0071] Figure 8 This is a comparison diagram of yaw rate under emergency obstacle avoidance conditions according to one embodiment of the present invention.

[0072] In the diagram: 1. Control unit; 2. Fixed bushing; 3. Left gear and rack mechanism; 4. Left motor controller; 5. Left rear wheel sensor; 6. Left steering knuckle mechanism; 7. Left universal joint mechanism; 8. Left first clutch; 9. Left motor; 10. Left second clutch; 11. Left sector gear mechanism; 12. Battery; 13. Right sector gear mechanism; 14. Right second clutch; 15. Right motor; 16. Right first clutch; 17. Right universal joint mechanism; 18. Right steering knuckle mechanism; 19. Right rear wheel sensor; 20. Right motor controller; 21. Right gear and rack mechanism; 22. Left steering tie rod; 23. Right steering tie rod. Detailed Implementation

[0073] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0074] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "front," "rear," "left," "right," "upper," "lower," "axial," "radial," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0075] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0076] Figure 1 The image shows a preferred embodiment of the trailer rear axle brake energy recovery and auxiliary steering system, which includes a detection unit, a control unit 1, and an execution unit.

[0077] The detection unit is used to detect vehicle information, which includes braking signals, steering wheel angle signals, motor current / torque signals, vehicle speed signals, rear wheel angle signals, and battery state of charge signals.

[0078] The control unit 1 is connected to the detection unit and the execution unit respectively, and is used to allocate the vehicle's working mode for the next moment and generate control commands according to the vehicle information. The vehicle's working modes include normal mode, brake energy recovery mode and rear axle auxiliary steering mode.

[0079] The execution unit includes a motor that executes either a regenerative braking mode or a rear axle assisted steering mode. It is used to execute vehicle control commands according to the assigned vehicle mode for the next moment. When the vehicle enters the regenerative braking mode, the wheels drive the motor to rotate and the motor charges the battery. When the vehicle enters the rear axle assisted steering mode, the battery supplies power to the motor and the motor drives the wheels to assist in steering.

[0080] The detection unit includes a brake pedal sensor, a steering wheel angle sensor, a motor current / torque sensor, a vehicle speed sensor, a rear wheel angle sensor, and a SOC sensor;

[0081] The brake pedal signal is used to detect the vehicle's brake pedal signal;

[0082] The steering wheel angle sensor is used to detect the steering wheel angle signal of the vehicle.

[0083] The motor current / torque sensor is used to detect the motor's current and torque;

[0084] The vehicle speed sensor detects the vehicle's speed signal;

[0085] The rear wheel steering angle sensor includes a left rear wheel steering angle sensor and a right rear wheel steering angle sensor, which are used to detect the steering angles of the left and right rear wheels, respectively;

[0086] The SOC sensor is used to detect the battery's state of charge.

[0087] By integrating information such as brake pedal signal, steering wheel angle signal, motor current / torque signal, vehicle speed signal, left and right front wheel angle signals, left and right rear wheel angle signals, and SOC signal, the vehicle's state can be more accurately determined to implement corresponding control strategies.

[0088] The control unit 1 includes an input module, a judgment module, and an output module; the input module is used to receive vehicle information detected by the detection unit; the judgment module is used to compare the vehicle information with preset conditions, determine whether the preset conditions are met, and generate a judgment result; the output module is used to generate corresponding vehicle control commands based on the judgment result and output them to the actuator.

[0089] The judgment module compares the vehicle information with preset conditions to determine whether the preset conditions are met, and generates a judgment result, specifically including:

[0090] First condition: If the brake signal opening is 1, i.e., there is braking behavior, and the vehicle speed is greater than or equal to u, and the battery state of charge signal is less than SOC. 回收 This means the battery charge is below the state of charge (SOC). 回收 If so, the result is to enter the braking energy recovery mode;

[0091] Second condition: If the first condition is not met, and the steering wheel angle is greater than or equal to δ, the result is to enter the rear axle auxiliary steering mode; Third condition: If neither the first nor the second condition is met, the result is to enter the normal mode.

[0092] Preferably, the vehicle speed u is 25-35km / h, and the battery SOC is... 回收 The steering wheel angle δ is 25-35°, with a range of 80-90%.

[0093] According to this embodiment, preferably, the vehicle speed u is 30km / h and the battery SOC is... 回收 The value is 90%, and the steering wheel angle δ is 30°;

[0094] Therefore, the preferred first condition is: if the brake signal opening degree is 1, that is, there is braking behavior, and the vehicle speed is greater than or equal to 30km / h, and the battery state of charge signal is less than 90%, that is, the battery charge is less than 90%, then the judgment result is to enter the braking energy recovery mode.

[0095] Second condition: If the first condition is not met, and the steering wheel angle is greater than or equal to 30°, the result is to enter the rear axle auxiliary steering mode;

[0096] Third condition: If neither the first nor the second condition is met, then the system is judged to enter normal mode.

[0097] like Figure 2 As shown, the execution unit includes a symmetrically arranged fixed bushing 2, a steering tie rod, a gear and rack mechanism, a motor controller, a steering knuckle mechanism, a universal joint mechanism, a first clutch, a motor, a second clutch, a sector gear mechanism, and a battery;

[0098] The fixed bushing 2 has a groove along the axial direction, and a gear and rack mechanism is provided at the groove.

[0099] The gear and rack mechanism is connected to one end of the steering tie rod;

[0100] The other end of the steering tie rod is connected to the steering knuckle mechanism;

[0101] One end of the steering knuckle mechanism is connected to the wheel, and the other end is connected to the universal joint mechanism, which is used to control the wheel's turning angle;

[0102] The other end of the universal joint mechanism is connected to one end of the first clutch, and is used to transmit power from the first clutch to the wheel;

[0103] The other end of the first clutch is connected to the motor and is used to control the power connection between the motor and the wheel;

[0104] The other end of the motor is connected to one end of the second clutch, and the other end of the second clutch is connected to one end of the sector gear mechanism, which is used to control the power connection state between the motor and the sector gear mechanism.

[0105] The motor is also connected to a battery and a motor controller; the motor controller is also connected to a control unit 1, and the motor controller is used to control the motor torque; the battery is used to power the motor or to charge the motor.

[0106] The other end of the sector gear mechanism is connected to the gear and rack mechanism, which is used to transmit the power of the motor to the gear and rack mechanism and control the steering tie rod to move along the axial direction on the fixed bushing 2.

[0107] According to this embodiment, preferably, the fixed bushing 2 is fixed and has two slots at each of its left and right ends for transmitting the power from the sector gear mechanism to the steering tie rod via the gear and rack mechanism. The fixed bushing 2 is tightly engaged with the steering tie rod mechanism, and the two steering tie rod mechanisms are restricted to only one degree of freedom: movement along the axis of the fixed bushing. Because the rear wheel steering angle does not need to be too large, the rack length does not need to be too long. Precisely designing the rack length to meet the rear wheel steering angle requirements also serves as a limit for the rack, preventing the rear wheels from generating excessive steering resistance torque that could affect the steering mechanism when the system is disturbed.

[0108] According to this embodiment, preferably, the symmetrically arranged execution units are divided into left and right sides. The left side includes a left gear and rack mechanism 3, a left motor controller 4, a left rear wheel sensor 5, a left steering knuckle mechanism 6, a left universal joint mechanism 7, a left first clutch 8, a left motor 9, a left second clutch 10, a left sector gear mechanism 11, and a left steering tie rod 22. The right side includes a right sector gear mechanism 13, a right second clutch 14, a right motor 15, a right first clutch 16, a right universal joint mechanism 17, a right steering knuckle mechanism 18, a right rear wheel sensor 19, a right motor controller 20, a right gear and rack mechanism 21, and a right steering tie rod 23.

[0109] The control unit 1 is connected to the detection unit, the left motor controller 4, the right motor controller 20, the left first clutch 8, the left second clutch 10, the right second clutch 14, and the right first clutch 16, respectively.

[0110] In this embodiment, there are two motors, namely the left motor 9 and the right motor 15. When the system is in the braking energy recovery mode, it can improve the energy recovery efficiency. When the system is in the rear axle auxiliary steering mode, it can control the left and right wheels to achieve independent steering.

[0111] The execution unit executes vehicle control commands according to the allocated next-moment vehicle mode, including:

[0112] When the vehicle enters the regenerative braking mode, the first clutch engages and the second clutch disengages. The wheels drive the motor to rotate through the first clutch, and the motor charges the battery.

[0113] When the vehicle enters the rear axle assisted steering mode, the first clutch is disengaged and the second clutch is engaged. The battery powers the motor, which drives the steering tie rod to move along the axial direction on the fixed axle sleeve 2 through the sector gear mechanism and the rack and pinion mechanism. The motor drives the wheels to assist in steering.

[0114] The rear axle assisted steering mode also includes a first mode and a second mode;

[0115] The first mode condition is that the vehicle speed is less than u. In this mode, the motor controller controls the motor, causing the steering tie rod to move away from the center of the bushing.

[0116] The second mode condition is that the vehicle speed is greater than or equal to u. In this mode, the motor controller controls the motor, causing the steering tie rod to move towards the center of the bushing.

[0117] like Figure 3As shown, for example, the detection unit detects the following signals: brake pedal opening signal, steering wheel angle signal δ, motor current / torque signal, vehicle speed u, front wheel angle signal, rear wheel angle signal, and battery status signal SOC. These input signals provide multifaceted information about vehicle operating conditions and driving operations, providing a comprehensive data foundation for the intelligent decision-making of control unit 1.

[0118] Control unit 1 receives the signal sent by the detection unit and first determines whether the conditions for entering the regenerative braking mode are met. The conditions for entering the regenerative braking mode are Break = 1, u ≥ 30 km / h, and SOC < 90%. Break = 1 means that the brake pedal opening is 1, that is, the driver has pressed the brake pedal once. u ≥ 30 km / h means that the vehicle speed is greater than or equal to 30 km / h. Regenerative braking is only performed when the vehicle is at a higher speed, because the recovery efficiency is low at low speeds and the motor torque is too large at low speeds, which can easily damage the mechanical structure. SOC < 90% means that regenerative braking is only performed when the battery charge is below 90%. When the charge is too high, priority is given to ensuring the vehicle's power performance. If the conditions for entering the regenerative braking mode are met, the left first clutch 8 and the right first clutch 16 are engaged, and the left second clutch 10 and the right second clutch 14 are disengaged. Power is transmitted from the wheels to the universal joint mechanism, and then from the universal joint mechanism to the motor through the clutches, and then from the motor to the battery. After that, the battery SOC signal is returned to control unit 1, and control unit 1 then re-determines the conditions based on the returned signal and other signals.

[0119] If the conditions for regenerative braking are not met, the system proceeds to the next stage to determine if the conditions for entering rear axle auxiliary steering mode are met. The entry condition for rear axle auxiliary steering mode is δ≥30°. δ≥30° means the driver's steering wheel angle is greater than or equal to 30°. If it is less than 30°, it is considered that the driver is slightly correcting the direction, avoiding frequent engagement of rear axle auxiliary steering mode due to slight corrections. If the entry condition for rear axle auxiliary steering mode is not met, the system exits, neither regenerative braking nor rear axle auxiliary steering mode is entered, the system does not operate, and the left first clutch 8, left second clutch 10, right second clutch 14, and right first clutch 16 are all disengaged. When the entry condition for rear axle auxiliary steering mode is met, the left second clutch 10 and right second clutch 14 engage, and the left first clutch 8 and right first clutch 16 engage. The battery powers the motor, and power is transmitted from the battery to the motor, then from the motor to the sector gear mechanism via the clutches, then from the sector gear mechanism to the rack and pinion mechanism, then from the rack and pinion mechanism to the steering tie rod, and finally from the steering tie rod to the steering knuckle mechanism. At this point, it is necessary to… Additionally, considering vehicle speed, when the speed is below 30 km / h, the vehicle is in low-speed steering. The motor controller distributes different torques to the left and right motors, and the rear axle wheels are biased towards light steering. The two steering tie rods should move away from the center of the fixed axle sleeve 2, and the left and right rear wheels adopt an "outward" posture, combined with the "inward" posture of the front wheels. This allows the vehicle to make U-turns in narrow and limited spaces, and also allows the rear wheels to rotate in the opposite direction to the front wheels when making low-speed left and right turns, achieving faster cornering with a smaller turning radius. When the speed is above or equal to 30 km / h, the motor... The controller controls the left and right motors to distribute different torques, and the rear axle wheels are steered towards driving stability. The two steering tie rods should move towards the center of the fixed axle sleeve 2, and the left and right rear axle wheels adopt an "inward" posture. The driving stability of the vehicle when driving straight at high speed is improved. In emergency obstacle avoidance situations, the rear wheels can also steer in the same direction as the front wheels, reducing body roll and instability, which helps to improve the stability and controllability of the vehicle. Then, the motor current / torque signal and the rear wheel steering angle signal are returned to the control unit 1, and the control unit 1 re-determines the conditions based on the returned signals.

[0120] The C-WTVC cycle is a test cycle used to test the fuel consumption of heavy-duty commercial vehicles in China. Its basic indicators include three parts: urban cycle, highway cycle, and expressway cycle. The C-WTVC cycle test conditions include vehicles of different types and characteristic mileage distribution coefficients. The corresponding cycle tests and fuel consumption calculations are carried out according to different vehicle models and design gross weights. This cycle is also applicable to the energy consumption test of electric vehicles.

[0121] In this embodiment, to verify the effectiveness of the present invention, a heavy commercial vehicle with a weight of 20t and a motor power of 100kW was selected.

[0122] like Figure 4 The schematic diagram shows the electrical energy that the present invention can recover in 2500s under the braking energy recovery mode under the C-WTVC operating condition. Under the above conditions, the present invention can recover approximately 1.6 kWh of electricity within 2500s.

[0123] like Figure 5 The diagram shows a comparison of the State of Charge (SOC) values ​​of a vehicle under the present invention in regenerative braking mode and a vehicle without regenerative braking control under the C-WTVC condition within 2500 seconds. For ease of comparison, the initial SOC value of both vehicles is set to 50%. It can be seen that the SOC value of the vehicle under the present invention decreases from 50% to about 38% in 2500 seconds, while the SOC value of the vehicle without regenerative braking control strategy decreases from 50% to about 36% in 2500 seconds.

[0124] Combination Figure 4 and 5 Therefore, it can be concluded that the braking energy recovery control strategy in this invention can effectively recover and store the energy consumed during braking, thereby improving energy utilization and reducing carbon emissions.

[0125] To verify the effectiveness of the first mode of the rear axle assisted steering mode of this invention, the aforementioned heavy commercial vehicle was used again. The system performance in low-speed steering mode was analyzed. Because the left and right wheels can steer independently, during a U-turn, the motor controller controls the left and right motors to distribute different torques, causing the two steering tie rods to move away from the center of the fixed axle sleeve. Figure 6 As shown, the left and right rear wheels are in an outward-pointing position, while the left and right front wheels are in an inward-pointing position when combined with the independent steering mechanism on the front axle. By controlling the differential speed of the eight wheels, the vehicle can turn around. This demonstrates that when the invention is applied to a real vehicle, the vehicle can operate more flexibly in a small and limited space, improving driving efficiency and convenience.

[0126] In addition, in such Figure 7 In the emergency obstacle avoidance situation shown, the present invention is in the second mode of the rear axle assisted steering mode, as shown. Figure 8 As shown, a comparison of the yaw rates of a vehicle in the second mode with rear axle steering assist and a vehicle without rear axle steering assist under emergency obstacle avoidance conditions reveals that the peak yaw rate of the vehicle with rear axle steering assist is lower than that of the vehicle without rear axle steering assist. Therefore, this invention can effectively improve vehicle driving stability.

[0127] This invention significantly improves vehicle maneuverability, handling ease, driving stability, and energy recovery efficiency, thereby comprehensively enhancing vehicle performance characteristics and broadening the overall range of vehicle performance. This invention integrates regenerative braking and assisted steering technologies on the rear axle of the vehicle, enabling these two technologies to work synergistically. This allows the vehicle to achieve superior maneuverability, easier handling, better driving stability, and more efficient energy recovery in different driving modes.

[0128] Example 2

[0129] A control method for a trailer rear axle brake energy recovery and auxiliary steering system according to Embodiment 1 includes the following methods:

[0130] Step S1: The detection unit is used to detect vehicle information, which includes braking signal, steering wheel angle signal, motor current / torque signal, vehicle speed signal, rear wheel angle signal and battery state of charge signal;

[0131] Step S2: Allocate the vehicle's operating mode for the next moment based on the vehicle information and generate control commands. The vehicle's operating modes include normal mode, regenerative braking mode, and rear axle steering assist mode.

[0132] Step S3: Execute vehicle control commands according to the allocated vehicle mode for the next moment.

[0133] The control method for the regenerative braking mode includes the following steps:

[0134] The detection unit detects the brake pedal signal, vehicle speed signal, and SOC signal, and transmits them to the control unit;

[0135] The control unit determines whether the conditions for entering the regenerative braking mode are met based on the input brake pedal signal, vehicle speed signal, and SOC signal. When the conditions for entering the regenerative braking mode are met, the clutch connecting the motor and the wheel engages, causing the rear axle to drive the motor to rotate through the clutch. When the conditions for entering the regenerative braking mode are not met, the regenerative braking mode is either not entered or exited.

[0136] The battery SOC signal is returned to the signal detection unit, which then sends it to the control unit. The control unit then re-determines whether the conditions for entering the regenerative braking mode are met.

[0137] The control method for the rear axle auxiliary steering mode includes the following steps:

[0138] The detection unit detects the steering wheel angle signal, the motor current / torque signal, the vehicle speed signal, and the rear wheel angle signal, and transmits them to the control unit;

[0139] The control unit determines whether the entry conditions for the rear axle auxiliary steering mode are met based on the input steering wheel angle signal, motor current / torque signal, vehicle speed signal, and rear wheel angle signal. When the entry conditions are met, further calculations are performed to determine the motor torque signal to be sent to the motor controller. Then, the motor adjusts the rear wheel posture. At the same time, the clutch connecting the motor and the sector gear mechanism engages during this process. The control unit controls the motor through the motor controller to drive the rear axle wheels to achieve auxiliary steering.

[0140] The motor's current / torque signal and the rear wheel steering angle signal are returned to the control unit, which then determines whether the conditions for entering the rear axle auxiliary steering mode are met.

[0141] This embodiment has the beneficial effects described in Embodiment 1, so it will not be repeated here.

[0142] It should be understood that although this specification is described according to various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

[0143] The detailed descriptions listed above are merely specific illustrations of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A trailer rear axle brake energy recovery and auxiliary steering system, characterized in that, It includes a detection unit, a control unit, and an execution unit; The detection unit is used to detect vehicle information, which includes braking signals, steering wheel angle signals, motor current / torque signals, vehicle speed signals, rear wheel angle signals, and battery state of charge signals. The control unit is connected to the detection unit and the execution unit respectively, and is used to allocate the vehicle's working mode for the next moment and generate control commands according to the vehicle information. The vehicle's working modes include normal mode, brake energy recovery mode and rear axle auxiliary steering mode. The execution unit includes a motor that executes either the regenerative braking mode or the rear axle auxiliary steering mode. It is used to execute vehicle control commands according to the vehicle's operating mode assigned for the next moment. When the vehicle enters the regenerative braking mode, the wheels drive the motor to rotate and the motor charges the battery. When the vehicle enters the rear axle auxiliary steering mode, the battery supplies power to the motor and the motor drives the wheels to assist in steering. The execution unit includes a symmetrically arranged fixed bushing (2), a steering tie rod, a gear and rack mechanism, a motor controller, a steering knuckle mechanism, a universal joint mechanism, a first clutch, a motor, a second clutch, a sector gear mechanism, and a battery; The fixed bushing (2) has a groove along the axial direction, and a gear and rack mechanism is provided at the groove. The gear and rack mechanism is connected to one end of the steering tie rod; The other end of the steering tie rod is connected to the steering knuckle mechanism; One end of the steering knuckle mechanism is connected to the wheel, and the other end is connected to the universal joint mechanism, which is used to control the wheel's turning angle; The other end of the universal joint mechanism is connected to one end of the first clutch, and is used to transmit power from the first clutch to the wheel; The other end of the first clutch is connected to the motor and is used to control the power connection status between the motor and the wheel; The other end of the motor is connected to one end of the second clutch, and the other end of the second clutch is connected to one end of the sector gear mechanism, which is used to control the power connection state between the motor and the sector gear mechanism. The motor is also connected to a battery and a motor controller; the motor controller is also connected to a control unit and is used to control the motor torque; the battery is used to power the motor or to charge the motor. The other end of the sector gear mechanism is connected to the gear and rack mechanism, which is used to transmit the power of the motor to the gear and rack mechanism and control the steering tie rod to move along the axial direction on the fixed bushing (2).

2. The trailer rear axle braking energy recovery and auxiliary steering system according to claim 1, characterized in that, The detection unit includes a brake pedal sensor, a steering wheel angle sensor, a motor current / torque sensor, a vehicle speed sensor, a rear wheel angle sensor, and a SOC sensor; The brake pedal signal is used to detect the vehicle's brake pedal signal; The steering wheel angle sensor is used to detect the steering wheel angle signal of the vehicle. The motor current / torque sensor is used to detect the motor's current and torque; The vehicle speed sensor detects the vehicle's speed signal; The rear wheel steering angle sensor includes a left rear wheel steering angle sensor and a right rear wheel steering angle sensor. The left rear wheel steering angle sensor is used to detect the steering angle of the left rear wheel, and the right rear wheel steering angle sensor is used to detect the steering angle of the right rear wheel. The SOC sensor is used to detect the battery's state of charge.

3. The trailer rear axle brake energy recovery and auxiliary steering system according to claim 1, characterized in that, The control unit includes an input module, a judgment module, and an output module; The input module is used to receive vehicle information detected by the detection unit; The judgment module is used to compare the vehicle information with preset conditions, determine whether the preset conditions are met, and generate a judgment result. The output module is used to generate corresponding vehicle control commands based on the judgment result and output them to the actuator.

4. The trailer rear axle brake energy recovery and auxiliary steering system according to claim 3, characterized in that, The judgment module compares the vehicle information with preset conditions to determine whether the preset conditions are met, and generates a judgment result, specifically including: First condition: If the brake signal opening is 1, i.e., there is braking behavior, and the vehicle speed is greater than or equal to u, and the battery state of charge signal is less than SOC. 回收 Preset value, i.e., battery level below SOC. 回收 If the preset value is met, the result will be to enter the regenerative braking mode; Second condition: If the first condition is not met, and the steering wheel angle is greater than or equal to δ, then the judgment result is to enter the rear axle auxiliary steering mode; Third condition: If neither the first nor the second condition is met, then the system is judged to enter normal mode.

5. The trailer rear axle brake energy recovery and auxiliary steering system according to claim 4, characterized in that, The execution unit executes vehicle control commands according to the allocated next-moment vehicle mode, including: When the vehicle enters the regenerative braking mode, the first clutch is engaged and the second clutch is disengaged. The wheels drive the motor to rotate through the first clutch, and the motor charges the battery. When the vehicle enters the rear axle assisted steering mode, the first clutch is disengaged and the second clutch is engaged. The battery powers the motor, and the motor drives the steering tie rod to move along the axial direction on the fixed bushing (2) through the sector gear mechanism and the gear rack mechanism. The motor drives the wheels to assist in steering.

6. The trailer rear axle brake energy recovery and auxiliary steering system according to claim 5, characterized in that, The rear axle assisted steering mode also includes a first mode and a second mode; The first mode condition is that the vehicle speed is less than u. In this mode, the motor controller controls the motor, causing the steering tie rod to move away from the center of the fixed bushing (2). The second mode condition is that the vehicle speed is greater than or equal to u. In this mode, the motor controller controls the motor, causing the steering tie rod to move towards the center of the fixed bushing (2).

7. A control method for a trailer rear axle braking energy recovery and auxiliary steering system according to any one of claims 1-6, characterized in that, Including the following methods: Step S1: The detection unit is used to detect vehicle information, which includes braking signal, steering wheel angle signal, motor current / torque signal, vehicle speed signal, rear wheel angle signal and battery state of charge signal; Step S2: Allocate the vehicle's operating mode for the next moment based on the vehicle information and generate control commands. The vehicle's operating modes include normal mode, regenerative braking mode, and rear axle steering assist mode. Step S3: Execute vehicle control commands according to the allocated vehicle mode for the next moment. When the vehicle enters the regenerative braking mode, the wheels drive the motor to rotate and the motor charges the battery. When the vehicle enters the rear axle assisted steering mode, the battery supplies power to the motor and the motor drives the wheels to assist in steering.

8. The control method for the trailer rear axle braking energy recovery and auxiliary steering system according to claim 7, characterized in that, The control method for the regenerative braking mode includes the following steps: The detection unit detects the brake pedal signal, vehicle speed signal, and SOC signal, and transmits them to the control unit; The control unit determines whether the conditions for entering the regenerative braking mode are met based on the input brake pedal signal, vehicle speed signal, and SOC signal. When the conditions for entering the regenerative braking mode are met, the clutch connecting the motor and the wheel engages, causing the rear axle to drive the motor to rotate through the clutch. When the conditions for entering the regenerative braking mode are not met, the regenerative braking mode is either not entered or exited. The battery SOC signal is returned to the signal detection unit, which then sends it to the control unit. The control unit then re-determines whether the conditions for entering the regenerative braking mode are met.

9. The control method for the trailer rear axle braking energy recovery and auxiliary steering system according to claim 7, characterized in that, The control method for the rear axle auxiliary steering mode includes the following steps: The detection unit detects the steering wheel angle signal, the motor current / torque signal, the vehicle speed signal, and the rear wheel angle signal, and transmits them to the control unit; The control unit determines whether the entry conditions for the rear axle auxiliary steering mode are met based on the input steering wheel angle signal, motor current / torque signal, vehicle speed signal, and rear wheel angle signal. When the entry conditions are met, further calculations are performed to determine the motor torque signal to be sent to the motor controller. Then, the motor adjusts the rear wheel attitude. At the same time, the clutch connecting the motor and the sector gear mechanism engages during this process. The control unit controls the motor through the motor controller to drive the rear axle wheels to achieve auxiliary steering. The motor's current / torque signal and the rear wheel steering angle signal are returned to the control unit, which then re-determines whether the conditions for entering the rear axle auxiliary steering mode are met.

Images