Electric Motor Bearing Preload Stabilization via Load-Receiving Surface
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Solution Overview
Problem
Existing electric motors with annular springs fail to effectively restrain bearings from vertical movement, leading to repeated flexural deformation and degradation, which disrupts the preload and affects the bearing's performance, especially in vertical motors installed on vehicles like hydraulic excavators.
Innovation Solution
The electric motor design includes a lower bearing fixed to both the motor shaft and housing to prevent axial displacement, with an annular spring applying a downward preload to the upper bearing and a load-receiving surface to counteract upward thrust loads, stabilizing the preload and reducing annular spring degradation through controlled axial movement within an adjustment gap.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an annular spring is used to apply preload to the bearing, then the rigidity of the bearing is improved, but the annular spring undergoes repeated large flexural deformation leading to degradation
Solution Approach 1:
A load-receiving surface is introduced as an intermediary component between the upper bearing and the housing. This surface receives upward thrust loads from the upper bearing, preventing these loads from being transmitted to the annular spring. The annular spring thus only needs to maintain preload without counteracting thrust loads, significantly reducing its flexural deformation and degradation while maintaining bearing rigidity through proper preload application.
2Stability of the object's composition
If the annular spring is designed to counteract thrust loads, then the bearing preload is maintained, but the spring force must be large increasing the spring's size and complexity
Solution Approach 1:
The load-receiving surface acts as a mediator that separates the functions of thrust load support and preload maintenance. By providing a dedicated surface to receive thrust loads from the upper bearing, the system eliminates the need for the annular spring to counteract these loads. This division of function allows the use of a smaller, simpler annular spring that only needs to generate sufficient force for preload, thereby reducing device complexity while maintaining preload stability.
3Adaptability or versatility
If the lower bearing is not fixed to prevent axial displacement, then the motor shaft can accommodate thermal expansion, but the bearing cannot maintain proper preload under vertical loads
Solution Approach 1:
The system is segmented into distinct functional zones: the lower bearing assembly handles thermal expansion accommodation through controlled axial movement of the motor shaft relative to the housing, while the upper bearing assembly with the load-receiving surface handles preload maintenance. The load-receiving surface on the housing provides a fixed reference point for preload application, ensuring that vertical loads do not compromise the preload force while the lower bearing remains free to accommodate thermal effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively stabilizes the preload on the bearing, reduces the annular spring's degradation, and enhances the motor's rigidity by allowing a smaller spring force to apply a required preload, while facilitating easier installation and adjustment of the annular spring.
Implementation Method 1
an annular spring applying a downward preload to the upper bearing
Implementation Method 2
The lower bearing is fixed to the motor shaft and the housing to be restrained from axial displacement relative to the motor shaft and the housing
Implementation Method 3
The housing has a load-receiving surface receiving an upward thrust load from the upper bearing, the upward thrust load overcoming the preload
Data Source
AI summary
Provided is an electric motor capable of stabilizing a preload applied to a bearing by an annular spring and effectively retarding degradation of the annular spring. The electric motor includes a motor shaft, a rotor, a stator, a housing containing the rotor and the stator in a posture where the motor shaft extends vertically, an upper bearing and a lower bearing supporting the motor shaft, and an annular spring applying a downward preload to the upper bearing. The lower bearing is fixed to the motor shaft and the housing. The housing has a load-receiving surface receiving an upward thrust load overcoming the preload from the upper bearing.