Sensor Unit Resin-Molded Portion Connection Stability
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Solution Overview
Problem
Conventional sensor units face issues where the polymer body may come off from the lead conductor, leading to instability and potential failure in measuring fluid temperatures.
Innovation Solution
A sensor unit design featuring a resin-molded portion that covers the base and intermediate portions of conductive members, with a through-hole and bent portions to reinforce the connection, preventing the resin from detaching and enhancing mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a polymer body is molded on a lead conductor connected to a temperature sensor element, then the sensor unit can be manufactured with simple structure, but the polymer body may come off from the lead conductor
Solution Approach 1:
The lead conductor is divided into three distinct portions: base end portion, intermediate portion, and tip end portion. This segmentation allows the resin-molded portion to specifically cover and secure the base end and intermediate portions while leaving the tip end exposed, creating a structured connection that prevents detachment without requiring complex overall design
Solution Approach 2:
The invention introduces a through-hole in the intermediate portion of the lead conductor, adding a dimensional feature (hole through the conductor) that enables the resin to penetrate and mechanically interlock with the conductor. This dimensional change transforms the simple surface molding into a three-dimensional anchored structure, preventing the polymer body from coming off
2Strength
If the resin-molded portion covers the entire conductive member, then connection strength is improved, but leakage currents increase and device size increases
Solution Approach 1:
The resin-molded portion is selectively applied only to specific regions of the lead conductor (base end portion and intermediate portion) rather than covering the entire conductor. This local quality approach provides sufficient connection strength at the critical connection points while leaving the tip end portion exposed, thereby reducing the surface area that could generate leakage currents
Solution Approach 2:
The tip end portion of the lead conductor is extracted from the resin-molded portion and left exposed. This extraction removes the potential source of leakage currents from the insulated region while maintaining the structural integrity and connection strength through the resin-secured base end and intermediate portions
3Reliability
If the resin-molded portion is securely attached to the conductive member, then connection reliability is improved, but the structure becomes more complex
Solution Approach 1:
The lead conductor is segmented into base end portion, intermediate portion, and tip end portion, with the resin-molded portion specifically covering the base end and intermediate portions. This segmentation creates a naturally anchored structure where the resin secures the conductive member through the defined portions without requiring additional complex fastening mechanisms
Solution Approach 2:
The through-hole in the intermediate portion adds a dimensional feature that enables the resin to penetrate and mechanically interlock with the lead conductor. This creates a three-dimensional anchored connection that significantly improves reliability while maintaining simplicity in the overall structure, as the anchoring is achieved through the molding process itself rather than additional components
Data Source
AI summary
A sensor unit according to the present disclosure includes: a sensor element; a pair of conductive members that extend in parallel with each other from the sensor element; and a resin-molded portion that covers part of the pair of conductive members. The pair of conductive members each includes: a base end portion connected to the sensor element; a tip end portion on an opposite side to the base end portion; and an intermediate portion that is a part between the base end portion and the tip end portion, the intermediate portion including a through-hole. The resin-molded portion covers the base end portion and the intermediate portion while the tip portion is exposed.