Knocking Sensor Resin Coating Curvature for Seal Durability
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Solution Overview
Problem
Existing knocking sensors face challenges in maintaining sufficient seal durability and forming grooves for improved sealing, particularly with resin coatings, which can lead to separation due to heat shrinkage and vibration in internal combustion engines.
Innovation Solution
The knocking sensor incorporates a piezoelectric element and a support member with a resin coating that features curved portions extending from the outside portion towards the base end side, engaging with annular grooves or projections to limit shrinkage and prevent separation, ensuring durable sealing even under thermal stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two grooves are provided on the outer circumference of the support member to improve sealing property, then the sealing property between support member and resin coating is improved, but the groove formation becomes difficult and seal durability is insufficient
Solution Approach 1:
The patent applies curvature by forming the resin coating to extend along the outer circumference of the support member in a curved manner, wrapping around the support member. This curved configuration improves sealing effectiveness while avoiding the manufacturing difficulties associated with forming grooves in the rigid support member.
Solution Approach 2:
The patent changes the parameter of the sealing structure from rigid grooves formed in the support member to a flexible resin coating that can be molded into a curved shape. This parameter change allows the sealing structure to adapt to the support member's geometry without requiring difficult groove formation processes.
2Reliability
If the resin coating is extended to cover the outer circumference of the support member, then the sealing property is improved, but the resin coating becomes prone to separation due to heat shrinkage
Solution Approach 1:
The resin coating is formed with a curved configuration that extends along the outer circumference of the support member. This curved shape allows the resin to wrap around the support member effectively, maintaining sealing property while the curvature itself helps accommodate thermal expansion and contraction, reducing separation risk.
Solution Approach 2:
The resin coating functions as a flexible shell that conforms to the outer circumference of the support member. This flexible configuration allows the coating to accommodate thermal shrinkage and vibration without separating from the support member, maintaining both sealing property and stability under thermal stress.
3Device complexity
If the support member structure is simplified, then the device complexity is reduced, but the ability to ensure sufficient seal durability is compromised
Solution Approach 1:
The patent uses a composite structure combining the support member with a resin coating material. This composite approach allows the support member to maintain a relatively simple structure while the resin coating provides the necessary sealing and durability functions, achieving both simplified complexity and improved reliability.
Solution Approach 2:
The patent changes the material parameter from单一的金属或刚性材料 to a combination of support member and resin coating. This parameter change enables the system to achieve sufficient seal durability through the resin's flexible and adhesive properties without requiring complex structural modifications to the support member itself.
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
This configuration effectively prevents resin coating separation from the support member, enhancing the durability of the seal and maintaining accurate vibration detection in high-temperature environments and cyclic cooling-heating conditions.
Implementation Method 1
a piezoelectric element; a support member having a support body portion, the support body portion including a support surface directly or indirectly supporting the piezoelectric element
Data Source
AI summary
A knocking sensor which includes: a piezoelectric element; a support member having a support body portion, the support body portion including a support surface directly or indirectly supporting the piezoelectric element; and a resin coating covering the piezoelectric element and at least a part of the support member, the resin coating having an outside portion covering an outer circumference of the piezoelectric element and an outer circumference of the support body portion. The support body portion of the support member has a first engagement portion on the base end side thereof. The resin coating has a curved portion which extends from the outside portion toward the interfacial direction inner side, and curves toward the base end side of the support body portion. Further, the curved portion includes a second engagement portion which engages the first engagement portion.