Rechargeable Grinder Switch Lock-Off Mechanism

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Solution Overview

Problem

In electric tools like rechargeable grinders, elongated operating members can be deflected by external forces, accidentally turning the switch ON due to the lack of effective locking mechanisms, leading to erroneous operations.

Innovation Solution

The design incorporates a pivotable operating member with a lock-off member that restricts movement in a normal state and releases the restriction to allow operation only when intended, ensuring the switch is not activated by deflection, eliminating the need for a reinforcing member.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a lock-off member is provided to prevent accidental operation, then safety is improved, but the operating member can still be deflected by external force and turn the switch ON

Engineering Contradiction:

ImprovesafetyVSAvoiddeflection by external force

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The switch system is divided into two independent switches (first switch and second switch) that must both be activated to operate the motor. The lock-off member is configured to operate the second switch, while a separate operating member operates the first switch. This segmentation ensures that accidental deflection of the operating member cannot activate both switches simultaneously, thereby preventing erroneous operation while maintaining safety.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a reinforcing member is added to prevent deflection, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improveprevention of erroneous operationVSAvoidstructural reinforcement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of reinforcing the operating member structurally, the patent segments the switch activation function into two separate switches. This functional segmentation eliminates the need for additional reinforcing members while achieving the same reliability goal of preventing erroneous operation from deflection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The lock-off member acts as an intermediary that controls the second switch independently. By introducing this intermediary element that must be deliberately operated, the system prevents accidental activation without requiring the operating member itself to be structurally reinforced against deflection.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the switch is arranged between the pivotal movement supporting point and the lock-off member, then accidental activation is prevented, but the structure becomes more complex

Engineering Contradiction:

Improveprevention of accidental switch ONVSAvoidswitch arrangement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The switch control function is segmented into two separate switches positioned at different locations. The first switch is positioned to be operated by the operating member's movement, while the second switch is positioned to be operated by the lock-off member. This spatial segmentation prevents accidental activation while distributing the control function across multiple points.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS9978541B2Electric tool

Publication Date: 2018.05.22 MAKITA CORP

AI summary

A rechargeable grinder includes a brushless motor, a main body housing configured to accommodate the brushless motor, a main switch and a micro switch configured to distribute power to the brushless motor, and a switch lever capable of moving with respect to the main switch and the micro switch, wherein a lock off lever capable of operating the micro switch in association with movement of the switch lever toward a switch is provided so as to be movable between a lock release position in which the micro switch can be operated and a lock position in which the micro switch cannot be operated.