Wheel Speed Sensor Waterproofing via Segmented Resin Sealing
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Solution Overview
Problem
Conventional wheel speed sensors using Hall ICs face challenges in maintaining a waterproof structure when bundling multiple electric wires, as the synthetic resin used for sealing cannot fuse with the wire harness resin, leading to potential moisture infiltration, especially when branching electric wires for connection to multiple electronic components.
Innovation Solution
A wheel speed sensor design incorporating a waterproofing member with through holes and elastic properties, which is fixed to the resin molded portion using engagement mechanisms, preventing moisture infiltration through the holes and allowing for bundling of electric wires without fusing the resin, thereby maintaining a waterproof seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the synthetic resin covering the wire harness is embedded in the synthetic resin forming the outer jacket of the wheel speed sensor to create a waterproof structure, then moisture infiltration is prevented, but this fusion is not possible when multiple electric wires are bundled in a single wire harness
Solution Approach 1:
The invention divides the waterproofing function into separate components: the outer jacket resin and the wire harness covering resin are kept separate and not fused together. Instead, each maintains its own waterproof barrier function, allowing the wire harness to bundle multiple wires while the outer jacket provides waterproof sealing for the sensor components.
Solution Approach 2:
The invention extracts the waterproofing function from the resin fusion mechanism. Rather than relying on the fusion of outer jacket resin and wire harness covering resin to achieve waterproofing, the design allows these resins to remain separate, with the outer jacket resin providing waterproof protection without requiring chemical or physical fusion with the wire harness covering.
2Ease of manufacture
If heat-shrinkable tubing is used to bundle and cover branching electric wires, then wire harnessing is achieved, but moisture infiltration occurs through the electric wires when fused to the wheel speed sensor resin
Solution Approach 1:
The invention segments the waterproofing function from the wire bundling function. The outer jacket resin provides waterproof sealing independently, while the heat-shrinkable tubing provides wire bundling and insulation independently. These functions are not fused together, eliminating the moisture infiltration pathway that would exist if they were chemically or physically bonded.
Solution Approach 2:
The invention introduces an intermediary relationship where the outer jacket resin and heat-shrinkable tubing interact mechanically (through embedding) but not chemically (no fusion). This intermediary positioning allows both components to maintain their respective functions while working together to provide overall waterproof protection.
3Reliability
If the synthetic resin of the wire harness is fused with the synthetic resin forming the outer jacket of the wheel speed sensor, then a sealed structure is created, but this prevents adaptation when multiple wires need to be bundled
Solution Approach 1:
The invention segments the sealing function from the wire harness structure. The outer jacket resin provides sealing integrity for the sensor components without requiring fusion with the wire harness covering resin. This segmentation allows the wire harness to adopt complex multi-wire configurations while the outer jacket maintains its sealing function independently.
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 moisture infiltration into the wheel speed sensor, enabling the bundling of electric wires into a single harness without compromising the waterproof integrity, even when branching for connection to multiple electronic components.
Implementation Method 1
a magnetoelectric transducer that detects a change in a magnetic field due to rotation of a rotor together with a wheel, converts the change into an electrical signal and outputs the electrical signal from the terminals
Implementation Method 2
the waterproofing member is an elastic member
Data Source
AI summary
A wheel speed sensor capable of preventing moisture from infiltrating the inside and a wire harness that is connected to the wheel speed sensor, which has a configuration in which a waterproofing member mounted on electric wires that are connected to a Hall IC and a covering member that covers the waterproofing member are embedded in an outer jacket portion. The covering member is formed of a material easily fused to the outer jacket portion. A groove is formed in the outer circumferential face of the waterproofing member, a protrusion is formed on the inner circumferential surface of the covering member, and the waterproofing member is prevented from moving in the axial direction by engaging the groove and the protrusion.