Dual-Actuator Switch Mechanism for Power Tool Safety

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Solution Overview

Problem

Existing power tools lack effective mechanisms to prevent accidental starts, which can lead to user injuries, particularly in devices with sharp cutting blades.

Innovation Solution

A handheld power tool design featuring dual actuators and a motion transfer device that requires both actuators to be engaged simultaneously to actuate the switch, ensuring that the power tool can only be activated when both handles are gripped, thereby reducing the likelihood of accidental starts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a single actuator is used to activate the power tool, then the ease of operation is improved, but the safety is worsened due to the risk of accidental starts

Engineering Contradiction:
Improveease of operationVSAvoidsafety
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The single actuation function is segmented into two separate actuators (first actuator and second actuator) that must both be engaged to activate the power tool. This segmentation divides the activation process into multiple independent steps, reducing the risk of accidental activation while maintaining operational simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system requires preliminary engagement of both actuators before the power tool can be activated. The motion transfer device is positioned such that it can only actuate the switch after both actuators have been engaged, ensuring that safety conditions are met before operation begins.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If dual actuators are added to prevent accidental starts, then the safety is improved, but the device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The two actuators are merged through a common motion transfer device that translates the engagement of both actuators into a single switch actuation event. This merging approach consolidates the control logic into a single mechanical pathway, reducing the overall system complexity despite having two actuators.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The motion transfer device serves as an intermediary mechanism between the two actuators and the switch. It mediates the interaction by converting the combined engagement of both actuators into the necessary motion to actuate the switch, simplifying the control architecture.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the motion transfer device requires both actuators to be engaged simultaneously, then the safety is improved by preventing accidental starts, but the ease of operation is reduced

Engineering Contradiction:
ImprovesafetyVSAvoidease of operation
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The system dynamically responds to the engagement state of both actuators. The motion transfer device is designed to only actuate the switch when both actuators are engaged simultaneously, creating a dynamic safety mechanism that adapts to user intent while maintaining operational ease through intuitive dual-handle engagement.

Inventive Principle:
Principle #15Dynamics

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 dual-actuator mechanism ensures that the power tool can only be operated when both handles are engaged, significantly reducing the risk of accidental activation and enhancing user safety.

Implementation Method 1

the motion transfer device moves linearly to actuate the switch... when only the first or the second actuator is engaged by the user and moved from the first position to the second position, the motion transfer device moves angularly

Methodology Applied
Scientific EffectMechanical motion transformation: Mechanical Advantage

Data Source

PatentEP3827929A1Switch for power tool
Publication Date: 2021.06.02 TECHTRONIC CORDLESS GP
  • EP3827929A1 patent drawingFigure 1
  • EP3827929A1 patent drawingFigure 2
  • EP3827929A1 patent drawingFigure 3

AI summary

The invention relates to a handheld power tool (10) including: a body (12); an electric motor (50) mounted in the body (12); a switch (40) mounted in the body (12) and to deliver electric power to the motor (50) when activated; a first actuator (20) mounted in the body (12) and engaged by a user to be moved by the user from a first position to a second position; a second actuator (220) mounted in the body (12) and engaged by the user to be moved by the user from a first position to a second position; and a motion transfer device (30) engageable by both actuators, to actuate the switch when both the actuators are in the second position.