Load Sensor Switch Merging for Electric Tool Actuation

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Solution Overview

Problem

Conventional electric tools with load sensors require a mechanical wakeup switch that complicates operation and increases tool size due to the need for two sets of switches, limiting stroke reduction and complicating waterproofing and dustproofing.

Innovation Solution

A tool configuration using a load sensor that allows activation of a control unit and control of electric components with a single set of switches, employing a pressure-sensitive conductive elastic member and substrate with a sealing cover to reduce the stroke of the switch manipulation part and improve component arrangement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a mechanical wakeup switch is used to activate the control unit from a powered-off state, then the control unit can be activated, but the switch manipulation part requires a relatively large stroke and two sets of switches are needed, increasing device complexity

Engineering Contradiction:
Improveactivation of control unitVSAvoidnumber of switches
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the wakeup switch function and the load sensor function into a single integrated switch assembly. The load sensor serves dual purposes: it acts as both the wakeup switch to activate the control unit from powered-off state and the load sensor to control the electric component speed. This eliminates the need for separate wakeup switch and load sensor, reducing device complexity while maintaining reliable control unit activation.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The load sensor is designed to perform multiple functions: it serves as the wakeup switch for activating the control unit when power is cut off, and simultaneously functions as the load sensor for controlling the motor speed during operation. This multi-functionality reduces the total number of components needed while ensuring reliable operation in both powered-off and powered-on states.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a mechanical wakeup switch with contact points is used, then the control unit can be activated, but the stroke of the switch manipulation part is increased, limiting stroke reduction

Engineering Contradiction:
Improveactivation of control unitVSAvoidstroke of switch manipulation part
Core Design Contradiction:
ReliabilityVSLength of moving object

Solution Approach 1:

The patent replaces the traditional mechanical wakeup switch with contact points with an electronic load sensor-based activation system. Instead of using mechanical contact points that require significant displacement, the load sensor detects load changes electronically through a strain gauge or similar sensor, enabling wakeup switch functionality with minimal manipulation stroke.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If two sets of switches are arranged in the tool, then both wakeup and load control functions are achieved, but the size of the tool is increased, restricting component arrangement

Engineering Contradiction:
Improveswitch functionsVSAvoidtool size
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent combines the wakeup switch and load sensor into a single integrated assembly, eliminating the need for two separate switch mechanisms. The load sensor assembly includes both the wakeup functionality and the load detection functionality, significantly reducing the space required in the tool housing and allowing more flexible component arrangement.

Inventive Principle:
Principle #5Merging (Combining)

4Adaptability or versatility

If two sets of switches are used, then both wakeup and load control are achieved, but the switch structure becomes complicated, making it difficult to ensure water-proofness and dust-proofness

Engineering Contradiction:
Improveswitch functionsVSAvoidswitch structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent integrates the wakeup switch and load sensor into a single compact assembly with unified sealing structure. This reduces the number of separate switch housings and sealing interfaces that would need to be protected against water and dust, simplifying the overall sealing design and improving water-proofness and dust-proofness.

Inventive Principle:
Principle #5Merging (Combining)

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 reduces the stroke of the switch manipulation part, decreases tool size, and simplifies waterproofing and dustproofing, enabling easier control of electric components with reduced complexity.

Implementation Method 1

a load sensor converting a load into a voltage is applied to a switch of an electric tool

Methodology Applied
Scientific EffectLoad sensor conversion: Piezoresistive Effect

Implementation Method 2

The load sensor includes a pressure-sensitive conductive elastic member and a substrate

Methodology Applied
Scientific EffectPressure-sensitive conduction: Piezoresistive Effect

Data Source

PatentEP3388202B1tool
Publication Date: 2021.04.28 MAX CO LTD
  • EP3388202B1 patent drawingFigure 1
  • EP3388202B1 patent drawingFigure 2
  • EP3388202B1 patent drawingFigure 3

AI summary

A tool includes a switch and a handle. The switch is configured to cause an electric component to operate. The handle is held by a hand to manipulate the switch. The switch includes a switch manipulation part to be manipulated, and a load sensor. The load sensor is configured to receive a pressing force through the switch manipulation part. The load sensor includes a pressure-sensitive conductive elastic member in which conductive particles are dispersed in a non-conductive elastic material.