Lockable Electric Switch for Power Tools

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Solution Overview

Problem

Existing electric power tools, such as hammer drills, face challenges in implementing a locking mechanism for operating modes due to the need for mechanical deflection and significant installation space, especially when using anti-vibration hand grips, which complicates dustproofing and increases the tool's size.

Innovation Solution

An electric switch with a first and second switching device that can be adjusted between different modes, allowing for automatic return to previous positions using restoring forces, enabling a compact and stable design that can be locked in certain modes, reducing the need for separate locking devices and minimizing installation space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a locking mechanism is implemented using a rigid coupling arrangement between the operating mode switch and locking device, then the locking function is achieved, but the hand grip housing cannot be fully decoupled from the tool housing regarding vibrations and considerable installation space is required

Engineering Contradiction:

Improvelocking functionVSAvoidmechanical deflection requirement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The switching device is divided into two independent parts: a first switching device for mode selection and a second switching device for locking functionality. This segmentation allows each part to perform its specific function independently without requiring complex mechanical coupling, thereby achieving the locking function while maintaining full decoupling capability of the hand grip housing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A magnetic coupling mechanism acts as an intermediary between the first and second switching devices. The magnetic field transmits the switching signal without requiring direct mechanical contact or rigid coupling, enabling the locking function to be achieved while allowing full vibration decoupling between the hand grip housing and tool housing.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a lever mechanism is used to couple the locking device to the operating mode switch, then the locking function is achieved, but considerable installation space is required

Engineering Contradiction:

Improvelocking functionVSAvoidinstallation space

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The mechanical lever mechanism is replaced with a magnetic coupling system. The magnetic field allows signal transmission and locking control without requiring physical levers or mechanical linkages, dramatically reducing the installation space required while maintaining reliable locking functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If the operating mode switch is rigidly coupled to the locking device, then the locking function is achieved, but dustproofing becomes difficult and the hand grip housing cannot be fully decoupled from vibrations

Engineering Contradiction:

Improvelocking functionVSAvoiddust penetration

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The magnetic field serves as an intermediary that can penetrate through dust-proof seals and barriers. This allows the locking signal to be transmitted through the sealed boundary between the hand grip housing and tool housing without requiring physical openings or compromises in the dustproof design.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

By separating the switching devices into independent components that communicate magnetically, each housing can be independently sealed against dust penetration while maintaining full locking functionality. The magnetic coupling does not require physical connections that would compromise the seals.

Inventive Principle:

Principle #1Segmentation

4Reliability

If a separate locking device is used, then the locking function is achieved, but the device complexity and installation space increase

Engineering Contradiction:

Improvelocking functionVSAvoidnumber of components

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The locking functionality is merged with the operating mode switch by using a second switching device that is magnetically coupled to the first switching device. This integration allows the locking function to be achieved without requiring a completely separate locking mechanism, reducing overall device complexity while maintaining reliability.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9508497B2Lockable electric switch

Publication Date: 2016.11.29 ROBERT BOSCH GMBH

AI summary

An electric switch, in particular for an electric power tool, in particular a hammer drill, comprises a first switching device and a second switching device, wherein the first switching device can be adjusted by adjusting a first mechanical signaling means from a first switched state to a second switched state, wherein the second switching device can be adjusted by adjusting a second electrical or mechanical signaling means from a third switched state in which the electric switch acts as a pushbutton into a fourth switched state in which the switch acts as a rocker switch. The disclosure further relates to an electrical power tool having an electric switch according to the disclosure.