Wheel Bearing Sensor Cap Elastic Seal Design
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Solution Overview
Problem
Existing wheel bearing apparatuses with integrated rotation speed detecting systems face challenges in maintaining long-term sealability due to thermal expansion differences and potential peeling or scratches during assembly, leading to reduced assembly workability and seal integrity.
Innovation Solution
A wheel bearing apparatus design featuring a pulser ring with magnetic characteristics and a cup-shaped sensor cap made of anti-corrosion steel, with an elastic member to maintain a consistent air gap and prevent seal deterioration, along with a thinned wall portion for precise positioning and enhanced magnetic flux density, ensuring improved assembly workability and sealability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a rotation speed sensor is built into the wheel bearing, then the size of the wheel bearing apparatus is reduced and adjustment complexity is eliminated, but sealability deteriorates due to thermal expansion differences and assembly-related peeling or scratches
Solution Approach 1:
The sensor cap is divided into a fitting portion for press-fit insertion into the outer member and a bottom portion that extends radially inward. This segmentation allows the sensor cap to be installed separately from the bearing assembly, maintaining the seal structure while accommodating the rotation speed sensor without compromising sealability.
Solution Approach 2:
The sensor cap acts as an intermediary component between the outer member and the rotation speed sensor. It provides a press-fit connection that accommodates thermal expansion differences and prevents direct contact between the sensor and bearing components, thereby eliminating assembly-related peeling or scratches while maintaining sealability.
2Ease of manufacture
If the sensor cap is press-fit into the outer member, then assembly workability is improved, but sealability may deteriorate due to peeling from thermal expansion differences
Solution Approach 1:
The sensor cap is designed with a press-fit connection that accommodates thermal expansion differences through elastic deformation. The fit portion is pressed into the outer member with controlled interference, allowing the material to elastically deform and seal the gap without peeling, even under thermal stress.
Solution Approach 2:
The sensor cap is formed from a material that combines ease of press-fit assembly with resistance to thermal expansion. This composite material property allows the cap to be easily installed while maintaining seal integrity under varying temperature conditions, preventing peeling at the joint.
3Measurement precision
If the wall thickness of the sensor cap is reduced for precise positioning, then magnetic flux density is enhanced, but structural strength may be compromised
Solution Approach 1:
The sensor cap features a thinned wall portion specifically at the location where precise positioning is needed for the rotation speed sensor. This local thinning enhances magnetic flux density and positioning precision without compromising the overall structural strength of the sensor cap, as other regions maintain sufficient thickness for mechanical integrity.
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
The solution effectively prevents seal deterioration from thermal expansion and assembly-related issues, enhancing the accuracy and durability of the rotation speed detection while maintaining robust sealability and assembly efficiency.
Implementation Method 1
An elastic member is pressed and elastically deformed between the fitting portion of the sensor cap and the end of the outer member
Implementation Method 2
A pulser ring is adapted to be fit onto the outer circumference of the inner ring. The pulser ring has magnetic characteristics alternately and equidistantly varying along its circumferential direction
Implementation Method 3
The sensor cap includes a cylindrical fitting portion to be press-fit into the end of the outer member
Data Source
AI summary
A wheel bearing apparatus incorporating a rotation speed detecting apparatus has an outer member, an inner member, double row rolling elements, a pulser ring, a cup-shaped sensor cap and a rotation speed sensor. The sensor cap is press-formed from anti-corrosion steel sheet into a cup-shaped configuration with a cylindrical fitting portion, to be press-fit into the end of the outer member, and a bottom portion, extending radially inward from the fitting portion to cover the inner-side end of the inner member. The rotation speed sensor is oppositely arranged so that it abuts or is positioned in close proximity to the bottom portion and accordingly the pulser ring. The rotation speed sensor and pulser ring oppose one another a predetermined axial air gap via the bottom portion. An elastic member is pressed and elastically deformed between the fitting portion of the sensor cap and the end of the outer member.