Knocking Sensor Locking via Plastic Deformation

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Solution Overview

Problem

Existing knocking sensors generate metal powder during manufacturing, which can degrade the insulating properties between the piezoelectric element and metal shell, and are costly due to the use of nuts for locking the weight.

Innovation Solution

A knocking sensor design where the weight is locked to the metal shell using a protruding portion formed by plastic deformation of the cylindrical portion, eliminating the need for nuts and reducing manufacturing costs by processing the inner surface to prevent metal powder attachment to the piezoelectric element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a nut is used to lock the weight to the metal shell, then the locking function is achieved, but metal powder is generated during screwing which degrades the insulating property between the piezoelectric element and metal shell

Engineering Contradiction:

Improvelocking functionVSAvoidmetal powder generation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and eliminates the nut from the assembly by forming an integrated protruding portion directly on the metal shell. This removes the source of metal powder generation while maintaining the locking function through the protruding portion that engages with the weight and piezoelectric element assembly

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The protruding portion is formed as an integral part of the metal shell through plastic deformation, merging the locking feature with the shell structure itself. This eliminates separate locking components and their associated manufacturing issues while ensuring reliable mechanical engagement

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a nut is used to lock the weight, then the locking function is achieved, but the part costs increase due to the expensive nut component

Engineering Contradiction:

Improvelocking functionVSAvoidpart costs

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The locking feature is merged into the metal shell as an integrated protruding portion formed by plastic deformation. This eliminates the need for separate nut components, reducing part count and manufacturing costs while maintaining the locking function

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The metal shell itself provides the locking function through its own deformed protruding portion, rather than requiring external locking components. The shell serves its structural purpose while also providing the mechanical engagement feature

Inventive Principle:

Principle #25Self-service

3Object-affected harmful factors

If the protruding portion is formed by plastic deformation of the inner surface, then metal powder generation is prevented and insulating property is ensured, but the manufacturing process requires precise control

Engineering Contradiction:

Improvemetal powder attachment preventionVSAvoidplastic deformation control

Core Design Contradiction:

Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

Instead of forming the protruding portion from the outer surface (which would generate metal powder), the deformation is applied from the inner surface outward. This inverted approach prevents metal powder generation while achieving the required geometric precision through controlled plastic deformation

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The manufacturing process controls the plastic deformation parameters (force, duration, temperature) to achieve the precise protruding geometry needed for proper engagement. By controlling these parameters, the invention achieves both prevention of metal powder generation and the required manufacturing precision

Inventive Principle:

Principle #35Parameter changes

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 ensures excellent insulating properties and reduces costs by preventing metal powder generation and attachment to the piezoelectric element, while also improving anti-rust properties through plating and simplifying the manufacturing process.

Implementation Method 1

a piezoelectric element, and interposed between the flange portion and the weight

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a protruding portion that is protruded while being plastically deformed from an inner surface of the cylindrical portion outward in a circumferential direction, and contacts the upper surface of the weight to lock the weight

Methodology Applied

Scientific EffectPlastic deformation: Plasticity

Data Source

PatentUS9291518B2Knocking sensor

Publication Date: 2016.03.22 NITERRA CO LTD

AI summary

In a knocking sensor, including: a metal shell having a cylindrical portion, and a flange portion that is located on the cylindrical portion, and projected toward an outside of the cylindrical portion in a circumferential direction, an annular weight that is fitted onto an outer circumference of the cylindrical portion, and has an upper surface, an annular piezoelectric element that is fitted onto an outer circumference of the cylindrical portion, and interposed between the flange portion and the weight, and an insulating body that is interposed between the flange portion and the piezoelectric element, a protruding portion that is protruded while being plastically deformed from an inner surface of the cylindrical portion outward in a circumferential direction, and locks the weight in contact with the upper surface of the weight directly or through a member is disposed on an outer circumferential surface of the cylindrical portion.