Eccentric shaft sleeve structure of brushless motor

Abstract

The invention discloses an eccentric shaft sleeve structure of a brushless motor, the eccentric shaft sleeve comprises a rotating step and a shaft sleeve body, the rotating step is of a regular hexagon step structure with the side length of 17mm, and the side edge of the regular hexagon corresponding to the minimum eccentric distance direction of a shaft sleeve inner ring is provided with an arc-shaped guide surface used for circumferential error-proofing positioning; the shaft sleeve body is of an eccentric structure, different eccentric distances are set according to different products, a mistake-proof through groove is formed in the lower end face of the shaft sleeve body, and the mistake-proof through groove is a through rectangular groove opening. According to the invention, accurate adjustment of the center distance is realized through the eccentric distance, noise and temperature rise caused by tolerance fluctuation are inhibited, and the consistency of the performance of a motor product is improved; by means of the standardized adjusting interface and the built-in mistake-proof design, the assembling efficiency and the percent of pass are improved, and the worm-wheel shaft torque output device is completely suitable for automatic and large-scale production and is suitable for all occasions where torque output needs to be conducted through a worm-wheel shaft.

Description

Technical Field

[0001] This invention belongs to the field of worm gear reducer motors, specifically relating to an eccentric bushing structure for a brushless motor. Background Technology

[0002] The current structure of a brushless motor mainly includes a stator assembly, a rotor assembly, a worm gear assembly, a reducer housing assembly, and a pressure cap assembly. The torque of the rotor assembly is transmitted to the worm gear shaft via worm gear meshing, and the power output is achieved from this shaft. In the reducer housing assembly, the output shaft sleeve and the worm gear shaft of the worm gear assembly use a clearance fit, primarily serving lubrication and wear resistance functions.

[0003] However, existing reducer housings use a uniform wall thickness design for the output shaft bushing, resulting in a fixed structure that lacks the ability to effectively adjust and compensate for accumulated tolerances generated during parts machining and assembly. This structural defect causes the transmission center distance of the worm gear to passively change due to tolerance fluctuations, leading to instability in the transmission system's operation. This directly manifests as poor consistency in key performance indicators such as motor noise and temperature rise, affecting the overall reliability of the product and the user experience.

[0004] like Figure 4-5 The diagram shows the structure and assembly method of an existing stepped output shaft bushing. The main structure of this stepped bushing 1 includes a stepped bushing step 101 and a stepped bushing body 102. The stepped bushing body 102 is fixed to the inner wall 201 of the output shaft hole of the reducer housing 2 using an interference fit. The lower end face 103 of the stepped bushing 1 fits against the end face 202 of the reducer housing, serving as an axial limit. However, this bushing structure has limitations: its stepped bushing body 102 uses a uniform wall thickness design, functionally only preventing wear between the worm gear shaft and the reducer housing and maintaining the basic fit clearance; it lacks the ability to adjust the core parameter of the transmission system—the center distance of the worm gear. Due to the inevitable accumulation of dimensional tolerances in the manufacturing of the reducer housing 2 and related parts such as the rotor components, the actual center distance after assembly will passively fluctuate within a large range. This fluctuation directly leads to poor product consistency and triggers two typical meshing failures: When the center distance is too large, the backlash between the worm gear and the worm increases accordingly, causing abnormal noise during motor commutation, and in severe cases, even tooth shaving and other failure modes. When the center distance is too small, the worm gear and the worm mesh too tightly, with virtually no clearance, which not only significantly increases meshing noise but also reduces the motor's operating temperature rise performance due to increased frictional losses.

[0005] In summary, the existing equal wall thickness bushing structure has become a key bottleneck restricting product performance and consistency because it cannot actively compensate for and adjust the center distance. Summary of the Invention

[0006] The purpose of this invention is to provide an eccentric bushing structure for a brushless motor. By redesigning the bushing structure, this invention achieves precise adjustment of the center distance through eccentricity, effectively suppressing noise and temperature rise caused by tolerance fluctuations, and significantly improving the consistency of motor performance. Its standardized adjustment interface and built-in error-proof design significantly improve assembly efficiency and yield rate, making it fully suitable for automated and large-scale production. As a universal component, this structure is suitable for all applications requiring torque output via a worm gear shaft.

[0007] The technical solution of this invention is: An eccentric bushing structure for a brushless motor, the eccentric bushing comprising a rotating step and a bushing body, the rotating step being a regular hexagonal step structure with a side length of 17mm, and an arc-shaped guide surface for circumferential anti-misalignment positioning provided on the side of the regular hexagon corresponding to the direction of minimum eccentricity of the inner ring of the bushing; the bushing body is an eccentric structure, and different eccentricities are set by rotating at different angles according to the dimensional tolerances of different products; an anti-misalignment through groove is provided on the lower end face of the bushing body, the anti-misalignment through groove being a through rectangular slot.

[0008] Furthermore, the rotating step is used in conjunction with a standard socket tool to achieve manual rotational adjustment.

[0009] Furthermore, the bushing body is interference-fitted with the inner hole of the reducer housing. By rotating, the actual installation position of the worm gear shaft can be changed, thereby achieving continuous adjustment of the center distance within a certain range. This structure is used to compensate for the cumulative tolerance of the parts.

[0010] Furthermore, the anti-misalignment groove forms a sliding fit with the guide strip in the automated feeding mechanism, limiting the direction of the bushing during the conveying process, thereby enabling automated feeding in a defined direction.

[0011] This invention has the following characteristics: 1. The bushing structure has been changed from a traditional concentric design to an eccentric structure. By setting a fixed eccentricity and ensuring an interference fit with the inner hole of the reducer housing, the center distance of the worm gear can be continuously adjusted within a specific range by rotating the bushing. This is the core invention, aiming to actively compensate for dimensional chain tolerances and improve product performance consistency.

[0012] 2. The rotation drive structure of the bushing is designed as a regular hexagonal step, which matches the dimensions of the standard sleeve tool, providing an effective means for manual rotation adjustment to change the center distance.

[0013] 3. On the hexagonal step, a specific arc-shaped guide surface is provided corresponding to the direction of minimum eccentricity of the inner ring of the bushing. This structure, in conjunction with the installation fixture, constitutes a mechanical error-proofing mechanism, ensuring that the eccentricity direction of all bushings is consistent during initial assembly, thus establishing a unified benchmark for subsequent precise adjustments.

[0014] 4. An axially continuous rectangular anti-misalignment groove is added to the end of the bushing. This structure is designed for automated assembly. By cooperating with the guide strip in the feeding mechanism, it limits the circumferential phase of the bushing during the conveying and pressing process, ensuring the uniformity and reliability of assembly angles in mass production. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the eccentric bushing of the present invention; Figure 2 This is a bottom-view isometric view of the eccentric bushing of the present invention; Figure 3 This is a diagram showing the fit between the eccentric bushing and the reducer housing of the present invention; Figure 4 This is a schematic diagram of an existing stepped bushing; Figure 5 This is a diagram showing the fit between the existing stepped bushing and the reducer housing.

[0016] The markings in the diagram are: 1. Stepped bushing, 2. Reducer housing, 3. Eccentric bushing, 101. Stepped bushing step, 102. Stepped bushing body, 103. Lower end face of the step, 201. Inner hole of the reducer housing, 202. End face of the reducer housing, 301. Rotating step, 302. Bushing body, 303. Arc-shaped guide surface, 304. Anti-misalignment groove. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] like Figure 1-3As shown, an eccentric bushing structure for a brushless motor is disclosed. The eccentric bushing 3 includes a rotating step 301, a bushing body 302, and an anti-misalignment groove 304. The rotating step 301 is a regular hexagonal step structure with a side length of 17mm, used to cooperate with a standard sleeve tool to achieve manual rotation adjustment. On the side of the hexagon corresponding to the direction of minimum eccentricity of the inner ring of the bushing, there is an arc-shaped guide surface 303. This structure cooperates with the installation fixture to form a mechanical anti-misalignment, ensuring that the initial phase of all bushings is consistent during assembly. The bushing body 302 is an eccentric structure, with different eccentricities set according to different products. The bushing is interference-fitted with the inner hole 201 of the reducer housing. By rotating, the actual installation position of the worm gear shaft can be changed, thereby achieving continuous adjustment of the center distance within a certain range. By measuring the backlash and unidirectional rotational current of the motor, it can be determined whether the center distance is within the appropriate range. If it is not within the design requirements, by rotating the eccentric bushing step 301, the eccentric bushing body 302 of the eccentric structure will rotate within the inner hole 201 of the reducer housing. After rotation, the center distance can be increased or decreased, thereby adjusting the current and backlash to stabilize the meshing critical dimension area. This structure is used to compensate for the cumulative tolerance of parts, stabilize the center distance to the design value, thereby improving the consistency of product performance and avoiding abnormal noise, tooth shaving, and abnormal temperature rise caused by center distance deviation. The anti-misalignment groove 304 is a through rectangular groove perpendicular to the arc-shaped anti-misalignment guide surface 303, opened on the lower end face of the bushing body 302. This groove forms a sliding fit with the guide bar in the automated feeding mechanism, limiting the direction of the bushing during the conveying process, ensuring that all bushings entering the pressing station have a consistent circumferential phase, and ensuring the uniformity of the assembly angle.

[0019] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a reasonably structured and easily adjustable eccentric bushing. Through its unique eccentric structural design, this bushing achieves continuous adjustment of the center distance, effectively compensating for part tolerances and significantly improving motor noise and temperature rise performance. Its standardized adjustment interface facilitates operation using common tools, simplifying the assembly process. The built-in error-proof structure ensures the uniqueness of the assembly direction, avoiding the risk of misassembly. The overall structure is simple and reliable, requiring no additional positioning parts, improving product consistency while reducing production costs, and is fully suitable for automated assembly and mass production.

[0020] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

Claims

1. An eccentric shaft sleeve structure of a brushless motor, characterized by: The eccentric shaft sleeve (3) comprises a rotating step (301) and a sleeve body (302), the rotating step (301) is a regular hexagon step structure with a side length of 17 mm, and a circular arc guide surface (303) for circumferential mistake-proof positioning is arranged on the side corresponding to the minimum eccentricity direction of the inner ring of the sleeve; the sleeve body (302) is an eccentric structure, and different eccentric distances are set by rotating different angles according to the size tolerance of different products; a mistake-proof through slot (304) is formed in the lower end surface of the sleeve body (302), and the mistake-proof through slot (304) is a through rectangular notch.

2. The eccentric shaft sleeve structure of a brushless motor according to claim 1, characterized in that: The rotating step (301) is used for cooperating with a standard sleeve tool and realizing manual rotation adjustment.

3. The eccentric shaft sleeve structure of a brushless motor according to claim 1, characterized in that: The sleeve body (302) is in interference fit with the inner hole of the reducer shell, the actual installation position of the worm shaft is changed by rotation, and continuous adjustment of the center distance in a certain range is realized, and this structure is used for compensating the cumulative tolerance of parts.

4. The eccentric shaft sleeve structure of a brushless motor according to claim 1, characterized in that: The mistake-proof through slot (304) is in sliding fit with a guide strip in an automatic feeding mechanism, and is used for limiting the direction of the sleeve in the conveying process.

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