Planetary Reduction Gear Bearing Preload Adjustment
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Solution Overview
Problem
Existing reduction assemblies face challenges in precisely positioning planetary gears due to the need for geometrically precise bearing placement, requiring specialized components and operations to correct for tolerance errors.
Innovation Solution
A reduction group with a ring gear, central sun gear, and planetary gears, utilizing oblique ball or roller bearings positioned in an 'O'-shaped arrangement, adjustable via a threaded coupling and locking means, allowing axial clearance adjustment to simplify assembly and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If planetary gears are mounted on planetary gear shaft with bearings, then the gear can rotate freely, but the bearing positioning requires geometrically precise placement and specialized components to correct tolerance errors
Solution Approach 1:
The patent introduces a corrective element (intermediary component) between the bearing and the planetary gear shaft that absorbs and compensates for dimensional errors. This corrective element acts as a mediator that allows standard bearings to be used while still achieving the required geometric precision through the intermediate corrective component.
Solution Approach 2:
The patent employs corrective elements with specific dimensional parameters designed to compensate for tolerance variations. By changing the parameters of these intermediary components (such as thickness, diameter, or positioning features), the system can accommodate standard bearings with normal tolerances while maintaining the required geometric precision for operational stability.
2Ease of manufacture
If standard bearings with normal tolerances are used, then manufacturing cost is reduced, but production tolerance errors must be corrected with specialized components
Solution Approach 1:
The corrective element serves as an intermediary that bridges the gap between standard bearings with normal tolerances and the precision requirements of the planetary gear system. This allows manufacturers to use off-the-shelf bearings while the corrective element handles the tolerance compensation, eliminating the need for specialized precision bearings.
Solution Approach 2:
The corrective element is designed as a simple, inexpensive component that can be easily manufactured and replaced if necessary. Rather than investing in expensive precision bearings or complex adjustment mechanisms, the system uses a simple corrective element that absorbs tolerance errors at minimal cost and complexity.
3Reliability
If bearings are positioned with high precision, then operational stability is maintained, but production operations become limited and require error recuperation
Solution Approach 1:
The corrective element acts as a mediator that decouples the bearing positioning from the critical geometric requirements. By introducing this intermediary component, the system maintains operational stability through the corrective element rather than through precise bearing placement, thereby simplifying production operations and improving assembly productivity.
Solution Approach 2:
The corrective elements are pre-manufactured with specific dimensional characteristics that compensate for expected tolerance variations. This preliminary preparation of corrective elements with built-in compensation features eliminates the need for complex error correction operations during assembly, thereby improving productivity while maintaining reliability.
Data Source
Figure 1a~1b
Figure 1a'
Figure 2
AI summary
The invention consists in a reduction group (1) for a vehicle and in a reduction assembly (900) that comprises said reduction group (1). The reduction group (1) comprises a ring gear (2), a central sun gear (3), a planetary gear holder (4) and at least one planetary gear (5) on the planetary gear holder (4) . Each planetary gear (5) comprises a gear (50) meshed externally with the ring gear (2) and internally with the central sun gear (3), a planetary gear shaft (51) fixed to the planetary gear holder (4) and a pair of bearings (55) supporting the gear (50) on the planetary gear shaft (51) . The planetary gear shaft (51) and the planetary gear holder (4) are engaged through adjustment means (6) in such a way that the planetary gear shaft (51) is axially adjustable on the planetary gear holder (4) in an operational configuration in which it performs an axial tightening action on the pair of bearings (55) exhibiting an axial clearance (T) adapted to allow the rotation of the pair of bearings (55).