Switch-Operating Mechanism for Powered Cutting Tool

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Solution Overview

Problem

Existing powered pruning tools often inadvertently remain switched on, leading to unnecessary power drain and risk of accidental operation due to inadequate switch mechanisms.

Innovation Solution

A switch-operating mechanism with a lever biased towards the first position by a spring, featuring a second biasing mechanism that increases the required force by 15-60% when moving between positions, an interlock for storage, a lever guard, and lever-position-detection switches to control power supply, ensuring safe and efficient operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a simple on/off switch is used, then the tool is easy to operate, but the risk of inadvertent operation increases

Engineering Contradiction:
Improveswitch operationVSAvoidaccidental activation prevention
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The switch mechanism requires the user to perform a specific preliminary action (pressing the button while moving the lever) before the tool can be activated. This preliminary action ensures intentional operation and prevents inadvertent activation during normal handling or storage.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The button acts as an intermediary element between the user's intent and the tool's activation. By requiring simultaneous engagement of the button and lever, the mechanism introduces an intermediate step that confirms intentional operation before power is supplied to the motor.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the tool remains switched on for convenient operation, then ease of use is improved, but power drain increases

Engineering Contradiction:
Improvereadiness to operateVSAvoidbattery drain
Core Design Contradiction:
Ease of operationVSLoss of energy

Solution Approach 1:

Each activation requires a deliberate preliminary action of pressing the button, which prevents the tool from remaining in a switched-on state unintentionally. The mechanism naturally returns to the off position when the button is released, conserving battery power when the tool is not actively being used.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If a multi-position switch mechanism is implemented, then safety against accidental operation is improved, but device complexity increases

Engineering Contradiction:
Improveswitch safetyVSAvoidswitch mechanism
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The combined lever-button mechanism serves multiple functions: it acts as both the operational switch and the safety interlock. The same lever that controls blade movement also controls power supply when combined with the button press, eliminating the need for separate safety switches and reducing overall complexity.

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

Solution Approach 2:

The patent merges the power switch function and the safety interlock function into a single integrated mechanism. The lever and button work together as a unified control system that simultaneously manages both operational control and safety prevention, reducing the number of separate components needed.

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

The mechanism prevents accidental activation, conserves power, and allows for safe storage and easy one-finger operation, reducing the risk of unintended tool use and battery drain.

Implementation Method 1

the lever is operatively-biased towards the first position by a first biasing means. Preferably, the first biasing means is a spring.

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

the lever includes a second biasing means which is activated in response to the lever being moved, in use, between the second and third positions. Suitably, activation of the second biasing means increases a force required to operate the lever

Methodology Applied
Scientific EffectSpring: Spring

Data Source

PatentEP2159529B1Powered cutting tool
Publication Date: 2014.06.04 ROBERT BOSCH GMBH
  • EP2159529B1 patent drawingFigure 1~2
  • EP2159529B1 patent drawingFigure 3~4
  • EP2159529B1 patent drawingFigure 5

AI summary

The present invention relates to a switch-operating mechanism. In particular, the present invention relates to a switch-operating mechanism for a power tool, such as a pruning tool. We describe a switch-operating mechanism for a powered tool comprising a working head (14) having first and second cutter members (15,20), wherein the switch-operating mechanism further comprises a lever (13) moveable between first, second and third operative positions. In operation, positioning of the lever in the first operative position provides a 'power off mode' in which the power supply is disconnected; movement of the lever into the second operative position causes the at least one of the cutter members (15) to move to a first blade position; and movement of the lever into the third operative position causes the at least one of the cutter members (15) to move to a second blade position.