Electric Tool Cumulative Interlock for Dual-Accessory Detection

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Solution Overview

Problem

Existing electric tools lack a mechanism to ensure power supply to the motor is permitted only when both a side handle and a cover accessory are properly attached, limiting design flexibility and requiring multiple sensors for detection.

Innovation Solution

An electric tool design that includes a first and second intermediate member, a first interlock member, and a sensor to detect cumulative displacement, allowing power supply only when both accessories are attached, reducing the need for multiple sensors and enhancing design flexibility.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple sensors are used to detect attachment of different accessories, then detection reliability is improved, but device complexity increases

Engineering Contradiction:

Improvedetection reliabilityVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A single sensor is designed to detect the attachment status of multiple different accessories (side handle and cover) by receiving signals from multiple intermediate members. The sensor serves multiple functions: detecting side handle attachment via the first intermediate member and detecting cover attachment via the second intermediate member, thereby reducing component count while maintaining detection reliability

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

Intermediate members (first intermediate member and second intermediate member) are introduced as mediators between the accessories and the single sensor. These intermediates transmit mechanical displacement signals from different accessories to the same sensor, enabling one sensor to indirectly detect multiple attachment states without requiring direct sensing of each accessory

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If multiple sensors are installed to detect each accessory attachment, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:

Improveattachment detection precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The single sensor is configured to perform multiple detection tasks with equal precision by receiving distinct displacement signals from different intermediate members. It can precisely detect whether the side handle is attached (via first intermediate member displacement) and whether the cover is attached (via second intermediate member displacement), achieving multi-purpose measurement precision without the cost of multiple sensors

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The detection functions for side handle attachment and cover attachment are merged into a single sensor system. The sensor combines multiple detection capabilities in one component, reducing the total number of parts and simplifying manufacturing assembly while maintaining the precision needed for each individual attachment detection

Inventive Principle:

Principle #5Merging (Combining)

3Measurement precision

If separate detection mechanisms are used for each accessory, then detection accuracy is improved, but the number of parts increases

Engineering Contradiction:

Improvedetection accuracyVSAvoidnumber of parts

Core Design Contradiction:

Measurement precisionVSQuantity of substance

Solution Approach 1:

The single sensor serves as a universal detection device that can accurately detect the attachment status of both the side handle and the cover. By designing the sensor to receive displacement signals from multiple intermediate members, it performs multiple detection functions with one component, reducing the total part count while maintaining detection accuracy for each accessory type

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The intermediate members act as signal transmission mediators that convert the attachment status of different accessories into standardized displacement signals that the single sensor can process. This intermediary mechanism allows one sensor to accurately detect multiple attachment states without requiring direct contact with or separate sensing for each accessory, thereby reducing the number of parts

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12384001B2Electric tool

Publication Date: 2025.08.12 MAKITA CORP

AI summary

An electric tool includes a motor, a first intermediate member configured to be displaced when a first accessory is attached to a first attachment portion, a second intermediate member configured to be displaced when a second accessory is attached to a second attachment portion, and a first interlock member. The first interlock member mechanically moves in conjunction with the respective displacements of the first intermediate member and the second intermediate member. The first interlock member is displaced in the same direction between when the first accessory is attached and when the second accessory is attached, and is cumulatively displaced when the first accessory and the second accessory are attached. The electric tool is configured in such a manner that power supply to the motor is permitted only in a state that the first interlock member is cumulatively displaced.