A power steering axle driven by an in-wheel motor

Abstract

This invention discloses a power steering axle driven by hub motors, relating to the field of steering axle technology. The invention includes an axle body, a control arm mount, and wheel hub assemblies. The wheel hub assemblies are rotatably connected to the control arm mount via a control arm, and an angle detector is installed at the pivot point. The system also includes a gyroscope controller for differential torque control of the left and right hub motors based on deflection angle signals, enabling automatic correction of the driving direction. The axle is equipped with a steering assembly that drives the two wheel hub assemblies to deflect synchronously via a rack and pinion mechanism and steering linkage. The left and right hub motors are independently controlled by vector control drivers, achieving precise torque and speed adjustment. The system also includes independent brake calipers, enabling single-sided or dual-sided braking control to meet emergency avoidance and braking needs. Furthermore, when single-sided drive fails, the system can switch to single-sided drive and coordinate with the steering assembly to maintain vehicle operation.

Description

Technical Field

[0001] This invention relates to the field of steering axle technology, specifically to a power steering axle driven by a hub motor. Background Technology

[0002] Existing vehicle axle systems typically employ a centralized drive structure, where power is distributed to both wheels via an engine or motor through a driveshaft, differential, and other mechanisms. In this type of structure, the speed difference between the left and right wheels is primarily achieved passively through the differential mechanism, making precise active control of torque distribution difficult. When the vehicle is traveling in complex road conditions (such as variations in unilateral adhesion or uneven load), it is prone to directional deviation, requiring frequent steering corrections by the driver, resulting in poor control stability.

[0003] Meanwhile, traditional steering systems mostly employ mechanical linkages or hydraulic power steering, which limit their response speed and make steering accuracy reliant on mechanical backlash control, hindering the achievement of high-precision synchronous steering. Over long-term use, wear and assembly errors can easily lead to steering deviations. Regarding braking, current technologies typically use a unified braking system with synchronized braking of both wheels, making independent control on one side difficult. Therefore, in emergency obstacle avoidance situations, the vehicle's steering ability is limited, and it cannot achieve rapid obstacle avoidance through differential braking. Thus, existing technologies exhibit significant shortcomings in driving stability, steering accuracy, and braking flexibility. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention provides the following technical solution: a power steering axle driven by a hub motor, comprising an axle body, with swing arm seats for mounting wheel hub assemblies fixedly mounted at both ends of the axle body. A wheel hub assembly is movably mounted on each swing arm seat. Each wheel hub assembly includes a swing arm rotatably connected to the swing arm seat. An angle detector is positioned at the pivot point of the rotatable connection between the swing arm seat and the swing arm, and the angle detector monitors the deflection angle of the wheel hub assembly. The axle also includes a gyroscope controller, which sends a torque differential command to the hub motors in the two wheel hub assemblies based on the deflection signal output by the angle detector, thus correcting the driving direction. During straight-line driving, if the wheel motors unexpectedly deflect due to road conditions or load conditions, the vehicle gyroscope controller uses this mechanism to maintain the driving direction. The axle further includes a steering assembly, which actively controls the deflection angle of the two wheel hub assemblies on the swing arm seats. When the vehicle is completely stationary, the steering assembly provides a certain steering driving force to deflect the wheel motors and maintain the vehicle body stationary.

[0005] Preferably, the wheel hub assembly further includes brake pads rotatably mounted on the swing arm, the brake pads being coaxially fixed with the wheel hub motor; the wheel hub motor is rotatably mounted on the swing arm; wherein a brake caliper is fixedly mounted on the swing arm via a brake caliper bracket, and the brake caliper and brake pads constitute the braking part.

[0006] Preferably, the control arms in the two wheel hub assemblies are movably connected by a steering linkage, and the steering linkage is arranged parallel to the axle body.

[0007] Preferably, the steering assembly includes a steering control motor bracket and a steering slide block fixedly mounted on the axle body, wherein a steering slider is slidably mounted on the steering slide block; a steering control motor is fixedly mounted on the steering control motor bracket, and a gear is fixedly mounted on the output shaft of the steering control motor; a rack that meshes with the gear is fixedly mounted on the steering slider.

[0008] Preferably, a steering slide rod is fixedly installed on the steering linkage, the steering slide rod is arranged perpendicular to the steering linkage, and the steering slide rod slides through the steering slider.

[0009] Preferably, the hub motors in the left and right hub assemblies are driven by their respective vector control motor drivers to control the torque, angle, and speed of the hub motors, ensuring the forward and reverse rotation of the hub motors and torque control at zero speed, thereby ensuring the torque and speed balance of the hub motors on both sides of the axle body; the left and right vector control motor drivers simultaneously receive instructions from the gyroscope controller to drive the axle body forward, backward, and turn.

[0010] Compared with the prior art, the present invention has the following advantages: (1) By setting an angle detector at the pivot position of the swing arm and combining it with a gyroscope controller for closed-loop control, the present invention enables the vehicle to automatically correct its driving direction through the torque difference of the hub motor even if it is affected by uneven road surface or load offset during straight driving, thus significantly improving the vehicle's driving stability and reducing the driver's workload of frequently correcting the direction; (2) The present invention uses vector control drivers to independently control the left and right hub motors and coordinates them with a gyroscope controller to achieve precise distribution of torque, speed and angle, so that the vehicle has higher response accuracy and dynamic consistency during acceleration, deceleration and steering, avoiding the response lag problem in traditional mechanical transmission structures. (3) The present invention sets up a steering component and drives the steering linkage through a gear rack and slider linkage structure to achieve the deflection of the two wheel hub components; (4) The present invention uses an independently controlled brake caliper structure to enable the left and right wheel hub motors to perform braking control separately. In an emergency, the vehicle can be quickly deflected to avoid obstacles by locking one side, while the double-sided braking can achieve overall deceleration or stopping, greatly improving the vehicle's safety avoidance capability under complex working conditions; (5) The present invention adds fault redundancy control to the drive system. When one side wheel hub motor or driver fails, the system can automatically switch to single-side drive mode and combine with the steering component to maintain vehicle direction control, ensuring that the vehicle still has basic driving capability in the event of partial failure, and improving the reliability and safety of the whole vehicle system. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the overall structure of the present invention.

[0012] Figure 2 This is a schematic diagram of the steering component structure of the present invention.

[0013] Figure 3 This is a schematic diagram of the hub assembly structure of the present invention.

[0014] Figure 4 For the present invention Figure 3 Schematic diagram of the structure at point A in the middle.

[0015] Figure 5 This is a top view of the overall structure of the present invention.

[0016] Figure 6 This is a schematic diagram of the control flow of the present invention.

[0017] In the diagram: 101-Rack; 102-Steering control motor bracket; 103-Steering control motor; 104-Steering slide block; 105-Steering slider; 106-Steering slide rod; 107-Gear; 201-Wing arm; 202-Brake pad; 203-Brake caliper bracket; 204-Brake caliper; 205-Wheel hub motor; 301-Angle detector; 401-Axle body; 402-Wing arm bracket; 501-Steering linkage. Detailed Implementation

[0018] The following is in conjunction with the appendix Figures 1-6 The technical solution of the present invention will be further illustrated through specific embodiments.

[0019] This invention provides a power steering axle driven by a hub motor, comprising an axle body 401, with swing arm seats 402 fixedly mounted at both ends of the axle body 401 for mounting wheel hub assemblies. Each swing arm seat 402 has a wheel hub assembly movably mounted on it. Each wheel hub assembly includes a swing arm 201 rotatably connected to the swing arm seat 402. An angle detector 301 is located at the pivot point of the rotatable connection between the swing arm seat 402 and the swing arm 201, and is used to monitor the deflection angle of the wheel hub assembly. The axle also includes a gyroscope controller, which sends a torque differential command to the hub motors 205 in the two wheel hub assemblies based on the deflection signal output by the angle detector 301, causing the driving direction to return to center. During straight-line driving, if the wheel motors 205 unexpectedly deflect due to road conditions or load conditions, the vehicle gyroscope controller uses this mechanism to maintain the driving direction. Finally, the axle also includes a steering assembly, which actively controls the deflection angle of the two wheel hub assemblies on the swing arm seats 402. When the vehicle is completely stationary, the steering assembly provides a certain steering driving force to deflect the hub motor 205 and keep the vehicle stationary.

[0020] The angle detector 301 is not only an angle acquisition unit, but the signal it acquires under dynamic conditions includes differential angular velocity components and high-frequency vibration disturbance components. By performing frequency domain decomposition on this signal through a gyroscope controller, an equivalent estimate of the yaw rate of the axle system can be formed, thereby constructing a virtual inertial reference coordinate system. In this coordinate system, the electromagnetic torque output by the hub motor 205 can be decomposed into a driving component and a correction component. The correction component forms an additional yaw moment through differential control, achieving self-stabilizing control of the vehicle's direction.

[0021] When the hub motor 205 performs torque differential regulation, its internal magnetic flux distribution generates asymmetric disturbances. These disturbances are rapidly reconfigured through stator current space vector modulation, thus completing the redistribution of output torque in an extremely short time (milliseconds). This is a nonlinear, strongly coupled control system, and its stability depends on the system's real-time analysis capability of the feedback signal from the angle detector 301.

[0022] When the vehicle is stationary and turning, the steering assembly, through the meshing of gear 107 and rack 101, converts the rotational motion output by the steering control motor 103 into the linear displacement of the steering slider 105. This displacement is transmitted to the steering linkage 501 via the steering slide rod 106, driving the swing arm 201 to deflect around the swing arm seat 402. Since the hub motor 205 is at zero speed, its output is a purely static electromagnetic holding torque. This torque balances the static friction generated by contact with the ground, keeping the vehicle body stable and preventing displacement.

[0023] The axle body 401 plays a multi-directional load transfer role in the above control process. It not only bears the lateral force from the swing arm 201, but also the torque reaction force generated by the hub motor 205. Therefore, the axle body 401 must meet the requirements of high rigidity and fatigue resistance in its design to ensure that no structural deformation occurs under complex working conditions, thereby avoiding the accumulation of measurement errors of the angle detector 301.

[0024] The wheel hub assembly also includes a brake pad 202 rotatably mounted on the control arm 201, which is coaxially fixed to the wheel hub motor 205. The wheel hub motor 205 is rotatably mounted on the control arm 201. A brake caliper 204 is fixedly mounted on the control arm 201 via a brake caliper bracket 203, and the brake caliper 204 and the brake pad 202 form the braking unit. The control arms 201 in the two wheel hub assemblies are movably connected by a steering linkage 501, which is parallel to the axle body 401.

[0025] The braking unit, consisting of brake pads 202 and brake calipers 204, not only performs basic braking functions but also acts as a yaw stabilization actuator in differential control mode. When a single brake caliper 204 actuates, the hub motor 205 on that side rapidly transitions from rolling friction to sliding friction, causing the coefficient of friction to increase exponentially and resulting in a significant yaw moment. This yaw moment can be expressed as being determined by both the wheel track and the difference in braking force, and is essentially a controlled asymmetric friction-driven behavior. By adjusting the clamping force of the brake calipers 204, precise control of this yaw moment can be achieved, enabling the vehicle to maintain high-precision obstacle avoidance capabilities even under extreme conditions.

[0026] The steering assembly includes a steering control motor bracket 102 and a steering slide block 104 fixedly mounted on the axle body 401, wherein a steering slider 105 is slidably mounted on the steering slide block 104; a steering control motor 103 is fixedly mounted on the steering control motor bracket 102, and a gear 107 is fixedly mounted on the output shaft of the steering control motor 103; a rack 101 that meshes with the gear 107 is fixedly mounted on the steering slider 105. A steering slide rod 106 is fixedly mounted on the steering link 501, and the steering slide rod 106 is perpendicular to the steering link 501, wherein the steering slide rod 106 slidably passes through the steering slider 105.

[0027] The hub motors 205 in the left and right hub assemblies are driven by their respective vector control motor drivers to control the torque, angle, and speed of the hub motors 205, ensuring the forward and reverse rotation and torque control at zero speed, thereby ensuring the torque and speed balance of the hub motors 205 on both sides of the axle body 401; the left and right vector control motor drivers simultaneously receive instructions from the gyroscope controller to drive the axle body 401 forward, backward, and turn.

[0028] The hub motor 205 employs vector control, essentially decomposing the three-phase AC current into flux linkage and torque components through a coordinate transformation (Clark-Park transformation), thus achieving decoupled control. This control method allows the motor to output stable torque even at low or zero speeds, making it suitable for static steering and attitude maintenance. In differential drive mode, the torque difference between the left and right hub motors 205 directly affects the vehicle's yaw rate, a relationship described by the vehicle dynamics model. The gyroscope controller, based on feedback data from the angle detector 301, adjusts the torque difference in real time to ensure the vehicle maintains its target heading. In the event of a single-sided failure, the system shuts down the faulty hub motor 205 and boosts the output of the other motor, achieving an offset drive mode. In this mode, the steering assembly handles the primary directional control, while the motor output provides propulsion, forming a redundant control system. Compared to traditional differential systems, this avoids the complexity of mechanical differential mechanisms and achieves functional redundancy through software control, significantly improving the system's fault tolerance.

[0029] When the brake caliper 204 is activated, it impedes the rotation of the brake pad 202 and the hub motor 205. In case of emergency braking, the brake caliper 204 compresses and restricts the rotation of the brake pad 202, thereby slowing down the rotation of the hub motor 205. The two brake calipers 204 can be controlled independently, each restricting the rotation of its corresponding hub motor 205, thus achieving deceleration control for hub motors 205 at different positions. For example, in case of emergency braking and steering, only the brake caliper 204 corresponding to the left or right (one side) hub motor 205 can be activated, locking the hub motor 205. Due to inertia, the vehicle will veer towards the side with the locked hub motor 205 (the locked hub motor 205 changes from rolling friction to sliding friction with the ground, resulting in a significant increase in friction; while the other hub motor 205 still experiences rolling friction with the ground), thus avoiding a collision. When both brake calipers 204 are activated simultaneously, the overall deceleration or stopping of the vehicle can be controlled.

[0030] The hub motor 205 is an external rotor brushless DC motor with an outer diameter of 350mm, a slotted pole structure, a high-strength aluminum alloy rotor housing, and built-in neodymium iron boron permanent magnets. The stator is made of laminated silicon steel sheets, and the winding conductors are enameled copper wire. The rated speed is approximately 3000rpm, and the rated torque (example) is 400Nm (light vehicles) to 1500Nm (heavy vehicles). The protection rating is IP67. A threaded interface on the housing is used to install brake pads 202.

[0031] When the driver turns the steering wheel, the angle detector 301 outputs a steering angle signal. The gyroscope controller reads the steering angle and vehicle speed, and calculates the ideal wheel speed difference and torque distribution ratio of the left and right hub motors 205 based on the pre-calibrated Ackerman steering angle mapping and vehicle dynamics model. The gyroscope controller sends PWM commands to the left and right vector control motor drivers, causing the left and right hub motors 205 to output the corresponding torque.

[0032] If the left and right vector control motor drivers fail, the failed side will receive zero torque, while the other motor will provide normal torque. If one wheel hub motor 205 short-circuits or burns out, the system detects high current and automatically cuts off the drive, switching to single-side drive; its driving direction is controlled by the steering assembly. The system controls the rotation angle of the output shaft of the steering control motor 103 by controlling the vehicle's deflection direction. The output shaft of the steering control motor 103 drives the rack 101 and steering slider 105 to slide on the steering sliding seat 104 via the gear 107. The steering slider 105 drives the steering rod 106 and steering linkage 501 to move together, thereby causing the two wheel hub assemblies to swing on the swing arm seat 402. At the same time, the steering rod 106 and steering slider 105 slide relative to each other.

Claims

1. A power steering axle driven by an in-wheel motor, characterized by: The axle body (401) is included. Both ends of the axle body (401) are fixedly provided with swing arm seats (402) for mounting wheel hub assemblies. Each swing arm seat (402) is movably mounted with a wheel hub assembly. The wheel hub assembly includes a swing arm (201) rotatably connected to the swing arm seat (402). An angle detector (301) is provided at the pivot position of the rotatable connection between the swing arm seat (402) and the swing arm (201). The angle detector (301) is used to monitor the deflection angle of the wheel hub assembly. It also includes a gyroscope controller, which sends a torque differential command to the hub motors (205) in the two hub assemblies based on the deflection signal output by the angle detector (301) to straighten the driving direction; It also includes a steering assembly for actively controlling the deflection angle of the two wheel hub assemblies on the swing arm mount (402).

2. The power steering axle driven by a hub motor according to claim 1, characterized in that: The hub assembly also includes a brake pad (202) rotatably mounted on the swing arm (201), the brake pad (202) being coaxially fixed with the hub motor (205); the hub motor (205) is rotatably mounted on the swing arm (201); wherein a brake caliper (204) is fixedly mounted on the swing arm (201) via a brake caliper bracket (203), and the brake caliper (204) and the brake pad (202) constitute the braking part.

3. The power steering axle driven by a hub motor according to claim 2, characterized in that: The swing arms (201) in the two wheel hub assemblies are movably connected by a steering link (501), which is parallel to the axle body (401).

4. The power steering axle driven by a hub motor according to claim 3, characterized in that: The steering assembly includes a steering control motor bracket (102) and a steering slide seat (104) fixedly mounted on the axle body (401), wherein a steering slider (105) is slidably mounted on the steering slide seat (104); a steering control motor (103) is fixedly mounted on the steering control motor bracket (102), and a gear (107) is fixedly mounted on the output shaft of the steering control motor (103); a rack (101) that meshes with the gear (107) is fixedly mounted on the steering slider (105).

5. The power steering axle driven by a hub motor according to claim 4, characterized in that: A steering slide rod (106) is fixedly installed on the steering linkage (501). The steering slide rod (106) is perpendicular to the steering linkage (501), and the steering slide rod (106) slides through the steering slider (105).

6. The power steering axle driven by a hub motor according to claim 5, characterized in that: The hub motors (205) in the left and right hub assemblies are driven by their respective vector control motor drivers to control the torque, angle and speed of the hub motors (205) and ensure the forward, reverse and zero speed torque control of the hub motors (205); the left and right vector control motor drivers simultaneously receive instructions from the gyroscope controller to drive the axle body (401) forward, backward and turn.

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