Ball Bearing Preload Device with Hollow Elastic Member
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Solution Overview
Problem
Existing preload structures for ball bearings, which rely solely on a coil spring around a motor shaft, face challenges in uniformly applying preload due to the need for end surface flattening and difficulty in assembly caused by the coil spring's elastic force, and the enclosed nature of the spring makes it hard to recognize or replace.
Innovation Solution
A preload device featuring a hollow elastic member with holders that regulate the spring's extension and separation, allowing the spring to be exposed and easily handled, with claw parts for engagement and flange parts for contact, enabling controlled preload application to the ball bearing without direct contact with the spring ends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a coil spring is provided around a shaft and the ball bearing is directly preloaded by an end surface of the coil spring, then preload can be applied to the ball bearing, but it is necessary to flatten the end surface of the coil spring so as to uniformly apply the preload and the assembling becomes difficult because the ball bearing is pressed and thus returned due to the elastic force of the coil spring returning to its free length
Solution Approach 1:
A holder is introduced as an intermediary component between the coil spring and the ball bearing. The holder has a flat pressing surface that contacts the ball bearing outer ring, while the coil spring contacts the holder's elastic pressing surface. This mediator resolves the contradiction by providing a flat contact surface for uniform preload distribution without requiring the coil spring end surface to be flattened, and the holder structure allows controlled compression to overcome the spring's elastic rebound force during assembly.
Solution Approach 2:
The preload application system is segmented into distinct components: the coil spring (elastic member), the holder (with flange and pressing surface), and the ball bearing. This segmentation allows each component to perform its specific function optimally - the spring provides elastic force, the holder provides a stable platform with flat contact surface, and the bearing receives uniform preload - thereby solving both the uniformity and assembly difficulty issues.
2Manufacturing precision
If the coil spring is enclosed in the inner and outer cylinders, then the end surfaces of the coil spring are not directly contacted to the bearings so that it is not necessary to flatten the end surfaces, but when the bearing device is provided in a cylinder, it is not possible to release the lock state, and therefore, the elastic force of the coil spring is still an obstacle in assembling the shaft and the bearing
Solution Approach 1:
The coil spring is extracted from the enclosed cylinder structure and repositioned to be located in the hollow portion of the holder. This extraction allows the spring to be accessible for compression during assembly while still maintaining its function of providing uniform preload through the holder's pressing surface. The spring is no longer trapped inside cylinders, enabling assembly operations while preserving preload uniformity.
3Manufacturing precision
If the coil spring is enclosed in the inner and outer cylinders, then it is not possible to recognize whether or not the coil spring is provided or a type of the coil spring at a later time, so that it is not possible to appropriately apply the preload
Solution Approach 1:
The coil spring is extracted from the enclosed structure and positioned in the hollow portion of the holder, making it externally visible. This allows inspection and recognition of the spring's presence and type, enabling appropriate preload application decisions, while the holder structure ensures uniform preload distribution is maintained.
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
Facilitates easy handling and appropriate preload application to ball bearings, reducing assembly difficulties and allowing visual inspection of the spring, thus ensuring consistent preload without the need for end surface flattening and improving assembly precision.
Implementation Method 1
a coil spring provided around a rotational shaft of a motor and the like, and the elastic force of the coil spring is used to apply preload to the ball bearing
Data Source
AI summary
A constant preload device of a ball bearing is provided. The preload device includes an elastic member having a hollow shape with openings at both sides in an elastic direction, and two holders inserted into the openings at the both sides of the elastic member, respectively. Each holder includes a flange part configured to contact an end portion of the opening, into which the holder is inserted, to regulate an extension of the elastic member in the elastic direction, and a claw part configured to engage with the other holder to regulate separation from the other holder. The holders are engaged to each other by the claw parts such that the elastic member is exposed from the holders. When the preload device applies preload to the ball bearing, the ball bearing contacts the preload device only at an outer ring of the ball bearing.