A motor for a brake-by-wire system

Abstract

The utility model relates to motor technical field, concretely relates to a kind of wire control brake system motor, including shell, MR magnetic ring, rotor shaft, stator, upper bearing, lower bearing and cover plate, the cover plate is set in the upper end of the shell, the rotor shaft is set in the shell, the stator is fixedly installed in the shell and surrounds the outside of the rotor shaft;The rotor shaft is rotatably supported between the shell and the cover plate by upper bearing and lower bearing;The MR magnetic ring is fixedly set on the rotor shaft;The upper bearing is self-lubricating bearing, the inner ring of self-lubricating bearing is interference fit with the rotor shaft, the outer ring of self-lubricating bearing is transition fit with the cover plate.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, specifically to a motor for a brake-by-wire system. Background Technology

[0002] Existing motors typically consist of components such as a housing, stator, upper bearing, lower bearing, cover plate, MR magnetic ring, and rotor shaft. The forming processes for each component are as follows: the housing is usually die-cast, the cover plate is rolled, and the rotor shaft is formed by low-temperature cold extrusion. Regarding bearing selection, current solutions generally use deep groove ball bearings at both the upper and lower support positions.

[0003] The assembly process of the above-mentioned motor assembly usually includes the following steps: First, press the upper bearing onto the rotor shaft; then, press the cover plate onto the rotor shaft; next, press the lower bearing and stator into the housing respectively; then, press the assembled rotor sub-assembly (including rotor shaft, upper bearing and cover plate) into the housing, and complete the assembly with the lower bearing and stator; finally, press the MR magnetic ring into the designated position.

[0004] However, in practice, the applicant has discovered that the existing technical solution has at least the following shortcomings:

[0005] Firstly, precise control of the pressing force is required during the process of pressing the upper bearing into the rotor shaft. Insufficient pressing force may result in a loose fit; excessive pressing force can easily damage the raceways and rolling elements inside the deep groove ball bearing, leading to abnormal bearing noise and vibration, ultimately negatively impacting the NVH (noise, vibration, and harshness) performance of the motor. This pressing process is complex and places high demands on production equipment and process control.

[0006] Secondly, deep groove ball bearings have relatively high manufacturing costs, which to some extent increases the overall material cost of the motor assembly.

[0007] In summary, existing motor structures suffer from complex assembly processes, susceptibility to damage to key components (bearings) affecting performance, and high manufacturing costs. Therefore, it is necessary to improve existing technologies to provide a motor assembly solution that is simpler in structure, easier to assemble, lower in cost, and more reliable in performance. Utility Model Content

[0008] The purpose of this utility model is to provide a motor for a brake-by-wire system, in order to solve the problems of complex assembly process, easy damage to key components (bearings) affecting performance, and high manufacturing cost in the existing motor structure.

[0009] To achieve the above objectives, this utility model provides the following technical solution:

[0010] A motor for a brake-by-wire system includes a housing, an MR magnetic ring, a rotor shaft, a stator, an upper bearing, a lower bearing, and a cover plate. The cover plate is disposed at the upper end of the housing, the rotor shaft is disposed within the housing, and the stator is fixedly installed inside the housing and surrounds the outside of the rotor shaft. The rotor shaft is rotatably supported between the housing and the cover plate via the upper and lower bearings. The MR magnetic ring is fixedly disposed on the rotor shaft. The upper bearing is a self-lubricating bearing, with its inner ring having an interference fit with the rotor shaft and its outer ring having a transition fit with the cover plate.

[0011] Optionally, the mating surface between the self-lubricating bearing and the rotor shaft is provided with lubricating grease.

[0012] Alternatively, the self-lubricating bearing is a rolled bearing.

[0013] Alternatively, the lower bearing may be a deep groove ball bearing.

[0014] Alternatively, the rotor shaft may be a hollow shaft formed by cryogenic cold extrusion.

[0015] Alternatively, the housing may be die-cast.

[0016] Alternatively, the cover plate may be rolled into shape.

[0017] Alternatively, the rotor shaft may be provided with a bearing shoulder for axial positioning by abutting against the end face of the self-lubricating bearing.

[0018] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0019] Through the above technical solutions, the self-lubricating bearing has a simple structure, which can reduce the material cost of core motor components to a certain extent. Based on the structural characteristics of the self-lubricating bearing itself and the transition fit with the cover plate, the precision control requirements for the pressing force during the press-fitting process are much lower than those for easily damaged deep groove ball bearings. This makes the assembly process simpler and faster, reduces reliance on high-precision assembly equipment, and reduces the risk of parts being scrapped due to improper assembly, thereby improving production efficiency and product quality.

[0020] Self-lubricating bearings inherently possess excellent vibration damping and noise reduction characteristics. The transition fit reduces stringent requirements on component machining tolerances, preventing assembly stress from excessively tight fits or wobbling from excessively loose fits, thus reducing abnormal vibration and noise.

[0021] The overall structural layout of the motor in this wire-controlled braking system, such as the stator surrounding the rotor, bearings distributed at both ends of the shaft for support, and the MR magnetic ring fixed on the shaft, constitutes a compact and mechanically well-distributed whole. This ensures the mechanical stability of the motor during operation, making power transmission and signal feedback stable and reliable, and meeting the high reliability requirements of the wire-controlled system for the actuator. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the exemplary embodiments of this utility model, the drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this utility model and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0023] Figure 1 A three-dimensional structural schematic diagram of the motor in one embodiment of the brake-by-wire system provided by this utility model;

[0024] Figure 2 A cross-sectional view of the motor in one embodiment of the brake-by-wire system provided by this utility model;

[0025] Figure 3 A schematic diagram of the structure of a self-lubricating bearing in a motor of a brake-by-wire system provided by this utility model in one embodiment.

[0026] The attached diagram shows the following components and their corresponding names: 1-Housing, 2-MR magnetic ring, 3-Self-lubricating bearing, 4-Rotor shaft, 5-Stator, 6-Deep groove ball bearing, 7-Cover plate. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be noted that while the description of these embodiments is intended to aid in understanding the present invention, it does not constitute a limitation thereof. The specific structural and functional details disclosed herein are only for describing exemplary embodiments of the present invention. However, the present invention may be embodied in many alternative forms and should not be construed as being limited to the embodiments described herein.

[0028] According to a specific embodiment of this disclosure, a motor for a brake-by-wire system is provided. Figures 1 to 3 Specific embodiments thereof are shown.

[0029] See Figures 1 to 3As shown, the motor of this wire-controlled braking system includes a housing 1, an MR magnetic ring 2, a rotor shaft 4, a stator 5, an upper bearing, a lower bearing, and a cover plate 7. The cover plate 7 is located at the upper end of the housing 1. The rotor shaft 4 is located inside the housing 1, and the stator 5 is fixedly installed inside the housing 1 and surrounds the outside of the rotor shaft 4. The rotor shaft 4 is rotatably supported between the housing 1 and the cover plate 7 by the upper and lower bearings. The MR magnetic ring 2 is fixedly installed on the rotor shaft 4. The upper bearing is a self-lubricating bearing 3, with its inner ring having an interference fit with the rotor shaft 4 and its outer ring having a transition fit with the cover plate 7.

[0030] The working process of the motor in the brake-by-wire system is as follows: When current flows into the stator 5 fixed inside the housing 1, a rotating magnetic field is generated. This rotating magnetic field acts on the rotor shaft 4 and drives it to rotate, thereby converting electrical energy into mechanical energy and outputting it. During this process, the rotor shaft 4 is stably supported by the upper self-lubricating bearing 3 and the lower bearing. The inner ring of the self-lubricating bearing 3 is interference-fitted with the rotor shaft 4 to ensure that the two rotate synchronously without relative slippage; its outer ring is transition-fitted with the cover plate 7, providing radial support while allowing for minor deformation or tolerance adjustment to ensure smooth rotation. The MR magnetic ring 2 fixed on the rotor shaft 4 rotates with the shaft. The changes in its magnetic field are detected by external sensors, thereby accurately acquiring the rotor's position and speed signals, forming a closed-loop control system to achieve precise control of the motor's operating state.

[0031] Through the above technical solution, the self-lubricating bearing 3 has a simple structure, which can reduce the material cost of the core components of the motor to a certain extent. Based on the structural characteristics of the self-lubricating bearing 3 itself and the transition fit adopted with the cover plate 7, the precision control requirements for the pressing force during the pressing process are much lower than those for the easily damaged deep groove ball bearing 6, making the assembly process simpler and faster, reducing the dependence on high-precision assembly equipment, reducing the risk of parts being scrapped due to improper assembly, thereby improving production efficiency and product quality.

[0032] The self-lubricating bearing 3 itself has excellent vibration damping and noise reduction characteristics. Based on the transition fit, it can reduce the stringent requirements on the machining tolerances of the parts, avoid assembly stress caused by excessive tightness or wobbling caused by excessive looseness, and reduce abnormal vibration and noise.

[0033] The overall structural layout of the motor in this linear braking system, such as the stator 5 surrounding the rotor, the bearings distributed at both ends of the shaft for support, and the MR magnetic ring 2 fixed on the shaft, constitutes a compact and mechanically well-distributed whole, ensuring the mechanical stability of the motor during operation and making power transmission and signal feedback stable and reliable.

[0034] It should be noted that the directional terms used, such as "inner" and "outer," refer to "inner" and "outer" relative to the outline of the component. "Inner" refers to the direction towards the inside of the component, and "outer" refers to the direction away from it. Furthermore, it should be noted that the terms used, such as "first" and "second," are used to distinguish one element from another and do not indicate sequence or importance. Moreover, in the following descriptions with accompanying drawings, the same reference numerals in different drawings represent the same element.

[0035] In the preferred embodiment provided in this disclosure, the mating surface between the self-lubricating bearing 3 and the rotor shaft 4 is provided with lubricating grease. Based on the characteristics of the self-lubricating bearing 3, the pre-lubricated grease at the friction pair interface between it and the rotor shaft 4 forms a more stable and sufficient double lubricating film during the initial startup of the motor and throughout its operation. This reduces starting torque, making the motor start-up smoother and easier, and effectively reduces wear on the bearing and journal during long-term operation, thereby extending the service life of the motor's core moving parts. The presence of lubricating grease fully fills the microscopic gaps in the mating surface, acting as a buffer to absorb and suppress the high-frequency micro-vibrations and impacts generated during the operation of the rotor shaft 4, and reducing frictional noise. This effect, combined with the inherent noise reduction characteristics of the self-lubricating bearing 3, works together to further improve the overall noise, vibration, and harshness (NVH) performance of the motor beyond simple superposition, ensuring the quietness and smoothness of the motor during operation.

[0036] Specifically, the self-lubricating bearing 3 is a rolled bearing. By directly rolling metal strip into shape using a high-precision mold, the self-lubricating bearing 3 is not only made up of the raw material cost and manufacturing cost of a single bearing, but also facilitates large-scale, high-speed automated production, thereby effectively reducing the overall material cost of the motor assembly from the source.

[0037] Furthermore, rolled bearings are structurally more conducive to maintaining lubrication and optimizing performance. When working in conjunction with pre-applied lubricating grease on the mating surfaces, they help the grease to be distributed more evenly and remain at the friction interface for a longer period, thus providing a more durable and stable lubrication effect, further promoting the improvement of motor NVH performance and reducing wear.

[0038] The self-lubricating bearing 3, which is rolled into shape, has a certain radial flexibility, which allows it to better adapt to the dimensional tolerance fluctuations of the mating parts when it is pressed into the rotor shaft 4 and achieves interference and transition fit with the cover plate 7. This effectively compensates for minor deviations in machining or assembly, ensures that a uniform and stable contact stress is formed between the bearing and the shaft, and between the bearing and the housing hole, avoids jamming caused by excessive tightness or abnormal noise caused by excessive looseness, and improves the consistency and reliability of assembly.

[0039] In this disclosure, the lower bearing is a deep groove ball bearing 6. This creates a hybrid bearing configuration of "self-lubricating upper bearing and deep groove ball bearing lower bearing," thereby optimizing the distribution of load-bearing capacity and improving system reliability. Specifically, during motor operation, the lower end of the rotor shaft 4 typically bears a larger radial load and a potential axial load. The deep groove ball bearing 6 has high precision, high rigidity, and excellent bidirectional axial load-bearing capacity, providing extremely stable and reliable support for the lower end of the rotor shaft 4. This ensures the positioning accuracy and operational stability of the core rotating components of the motor under complex stresses, avoiding the insufficient rigidity or axial movement problems that may occur when using a sliding bearing alone. Thus, it comprehensively ensures the long-term mechanical reliability of the motor.

[0040] In this disclosure, the rotor shaft 4 is a hollow shaft formed by low-temperature cold extrusion. This allows the shaft metal material to undergo plastic deformation below its recrystallization temperature, resulting in a work hardening effect. This effectively improves the surface strength, hardness, and fatigue life of the rotor shaft 4 without increasing material weight or cost. Simultaneously, cold extrusion molding provides extremely high dimensional consistency and positional accuracy, ensuring an interference fit between the rotor shaft 4 and the inner ring of the self-lubricating bearing 3. This facilitates a more uniform and reliable fit with the inner ring of the lower bearing, providing a guarantee for reducing vibration and noise (NVH) and achieving smooth and quiet operation of the motor.

[0041] In one embodiment, the housing 1 is die-cast. Based on the characteristics of die casting, the problems of cumbersome processes, weak connection strength, and large cumulative dimensional errors associated with assembling multiple parts by welding or screws are avoided. This enhances the overall rigidity and structural integrity of the housing 1 as the core load-bearing and structural reference component of the motor, giving the housing 1 extremely high dimensional accuracy. This provides an accurate installation reference for the subsequent assembly processes of pressing in the stator 5, pressing in the lower bearing, and installing the cover plate 7, which is beneficial for ensuring the uniformity of the air gap between the stator and rotor and the coaxiality of the bearing system.

[0042] In one embodiment provided in this disclosure, the cover plate 7 is formed by rolling. The rolling process allows for the high-precision and high-consistency forming of a bearing housing or flange structure for accommodating and supporting the outer ring of the self-lubricating bearing 3. Furthermore, the edges of the rolled cover plate 7 can be easily designed with flanges or snap-fit ​​structures for connection, enabling the cover plate 7 to be quickly and reliably fixed to the housing 1 through simple press-fitting, snap-fitting, or a small number of screws. This simplifies the final assembly process and improves production efficiency.

[0043] In this disclosure, the rotor shaft 4 is provided with a bearing shoulder for abutting against the end face of the self-lubricating bearing 3 for axial positioning. The end face of the bearing shoulder abuts against the end face of the self-lubricating bearing 3 to achieve its axial positioning.

[0044] Specifically, during the press-fitting of the self-lubricating bearing 3, the operator only needs to press the bearing in until its end face is tightly fitted with the end face of the bearing shoulder to complete both radial press-fitting and axial positioning in one go. This provides a clear and intuitive physical stop point for the assembly process, completely eliminating the tedious steps of repeated measurement or adjustment due to uncertain press-fitting depth. This not only greatly improves assembly efficiency but also ensures the consistency of axial dimensions of all products after assembly, reducing assembly quality fluctuations caused by human error.

[0045] The above specific embodiments further illustrate the purpose, technical solution and beneficial effects of this utility model. It should be understood that the above are only specific embodiments of this utility model and are not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A motor for a wire-controlled braking system, comprising a housing, an MR magnetic ring, a rotor shaft, a stator, an upper bearing, a lower bearing, and a cover plate, wherein the cover plate is disposed at the upper end of the housing, the rotor shaft is disposed within the housing, and the stator is fixedly installed within the housing and surrounds the outside of the rotor shaft; the rotor shaft is rotatably supported between the housing and the cover plate by the upper and lower bearings; the MR magnetic ring is fixedly disposed on the rotor shaft; characterized in that, The upper bearing is a self-lubricating bearing, with its inner ring having an interference fit with the rotor shaft and its outer ring having a transition fit with the cover plate.

2. The motor of the brake-by-wire system according to claim 1, characterized in that, The mating surface between the self-lubricating bearing and the rotor shaft is provided with lubricating grease.

3. The motor of the brake-by-wire system according to claim 1, characterized in that, The self-lubricating bearing is a rolled bearing.

4. The motor of the brake-by-wire system according to claim 1, characterized in that, The lower bearing is a deep groove ball bearing.

5. The motor of the brake-by-wire system according to claim 1, characterized in that, The rotor shaft is a hollow shaft formed by low-temperature cold extrusion.

6. The motor of the brake-by-wire system according to claim 1, characterized in that, The shell is formed by die casting.

7. The motor of the brake-by-wire system according to claim 1, characterized in that, The cover plate is rolled into shape.

8. The motor of the brake-by-wire system according to claim 1, characterized in that, The rotor shaft is provided with a bearing shoulder for axial positioning by abutting against the end face of the self-lubricating bearing.

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