Knocking Sensor Resistor Silicone Coating Heat Resistance
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Solution Overview
Problem
The metal film resistor in existing non-resonant knocking sensors experiences significant damage due to heat, leading to resistance deviations caused by fusion between the epoxy resin coating and the nylon-6,6 material, resulting in poor heat resistance.
Innovation Solution
A knocking sensor design featuring a resistor with an outer coating film made of silicone resin, which has a higher thermal deformation temperature than the case material, preventing fusion and maintaining resistance value stability, along with an inner coating film to manage molten plating metal and reduce resistance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an epoxy resin outer coating film is used on the metal film resistor, then the resistor is protected and covered, but the resin fuses with nylon-6,6 case material under heat application causing damage
Solution Approach 1:
The patent changes the material parameter of the outer coating film from epoxy resin to silicone resin, which has a higher thermal deformation temperature. This parameter change allows the coating to withstand higher temperatures during case formation and thermal cycling without fusing to the nylon-6,6 case material, thereby resolving the heat resistance issue while maintaining protective function.
Solution Approach 2:
The patent uses a composite material structure where silicone resin serves as the outer coating film material combined with the metal film resistor and nylon-6,6 case. This composite approach leverages the high heat resistance of silicone resin to protect the resistor assembly from thermal damage during manufacturing and operation.
2Reliability
If the outer coating film is applied to cover the metal film, then the metal film is protected, but the coating separates from the resistor body under thermal cycling
Solution Approach 1:
The patent changes the thermal deformation temperature parameter of the outer coating film material from epoxy resin (lower temperature) to silicone resin (higher temperature). This parameter change ensures the coating maintains its structural integrity and adhesion to the resistor body during thermal cycling, preventing separation while continuing to protect the metal film.
3Ease of manufacture
If high heat is applied during case formation, then the case is formed, but the epoxy resin outer coating film fuses to the case and metal film
Solution Approach 1:
The patent changes the thermal deformation temperature parameter of the outer coating film from epoxy resin to silicone resin. This material parameter change allows the coating to withstand the high heat applied during case formation without fusing to the case or metal film, enabling easy manufacturing while maintaining coating 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 design enhances the heat resistance of the knocking sensor by preventing separation of the outer coating film from the resistor body and maintaining consistent resistance values, even under thermal cycling conditions.
Implementation Method 1
The knocking sensor has a piezoelectric element as a sensor element
Data Source
AI summary
Provided is a knocking sensor with a support member, a piezoelectric element, a pair of electrode parts, a resistor and a case. The resistor has a resistor body formed with a metal film and connected in parallel to the pair of electrode parts. The resistor also has an outer coating film applied to cover the metal film. The outer coating film is formed of a resin material having a higher thermal deformation temperature than that of a resin material of the case.