Wheel Speed Sensor Asymmetric Mounting Base Resin Shrinkage
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Solution Overview
Problem
Conventional wheel speed sensors with asymmetric geometry experience resin shrinkage differences during molding, leading to unstable sensor unit projection directions and reduced measurement accuracy due to angular changes between the mounting base and sensor unit.
Innovation Solution
A wheel speed sensor design featuring a mounting base with two contacting parts and a sensor unit projecting between them, along with a fixing member that presses the mounting base to the vehicle, stabilizes the sensor unit's direction and corrects angular changes caused by resin shrinkage, ensuring accurate rotation speed measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sensor unit projects asymmetrically from the mounting base, then the sensor can be mounted on the vehicle, but resin shrinkage causes angular changes that reduce measurement accuracy
Solution Approach 1:
The patent applies asymmetry by intentionally designing the sensor unit's projection direction to be inclined at a predetermined angle relative to the mounting base, rather than perpendicular. This asymmetric configuration compensates for the resin shrinkage that occurs during molding, ensuring that the sensor unit's actual projection direction after shrinkage aligns correctly with the vehicle's reference direction for accurate measurement.
2Ease of manufacture
If resin molding is used to integrate the sensor unit with the mounting base, then manufacturing is simplified, but differential cooling rates cause shrinkage and destabilize the sensor unit's projection direction
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-compensating for the resin shrinkage that will occur during molding. The sensor unit is designed with a predetermined inclination angle that anticipates the shrinkage effect, so that after the resin cools and shrinks, the sensor unit's projection direction automatically aligns with the desired reference direction without requiring additional adjustment steps.
3Device complexity
If the sensor unit projects perpendicular to the mounting base, then the geometry is simple, but resin shrinkage causes angular deviations that mars measurement accuracy
Solution Approach 1:
The patent applies parameter changes by modifying the projection angle parameter of the sensor unit from the conventional perpendicular (90 degrees) to a predetermined inclined angle. This parameter change compensates for the resin shrinkage effect, ensuring that the sensor unit's actual projection direction after molding aligns correctly with the vehicle's reference direction for accurate rotation detection.
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 stabilizes the sensor unit's direction and maintains accurate attachment, enhancing the measurement accuracy of wheel speed by correcting angular changes and preventing positional shifts during resin molding.
Implementation Method 1
resin cooling speed varies with portions of the resin during the resin molding process, which produces difference in shrinkage of the resin and destabilizes the direction of projection of the sensor unit from the mounting base
Data Source
AI summary
A wheel speed sensor capable of stabilizing a projecting posture of a sensor unit when attached to a vehicle is provided. The wheel speed sensor includes a mounting base providing a first contacting part and a second contacting part when attached to the vehicle to come into contact with the vehicle at two positions of the first contacting part and the second contacting part, the sensor unit projecting from a position between the first contacting part and the second contacting part and inclining toward the first contacting part, the sensor unit being resin molded integrally with the mounting base and including a signal detection device provided in a distal end of the sensor unit, and a fixing member pressing and fixing the mounting base to the vehicle at a position between the first contacting part and the sensor unit.