Handheld Power Tool Dual-Handle Safety Switch
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Solution Overview
Problem
Handheld power tools used for high-torque applications are ergonomically challenging and pose safety hazards due to their weight distribution and the risk of the operator's hand being pinched between the reaction arm and workpiece, with existing solutions either not addressing these issues effectively or increasing tool complexity and bulkiness.
Innovation Solution
A handheld power tool design featuring a second supporting handle structure with a switch that requires simultaneous operation of both handles to supply energy to the motor, ensuring ergonomic handling and safety by ensuring the second hand supports the front gear unit, thus reducing strain and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a front gear unit is used to provide high torque levels, then the torque capability is improved, but the weight distribution shifts towards the front end making the tool less ergonomic
Solution Approach 1:
A supporting handle structure is introduced as an intermediary element between the user's hand and the front gear unit. This handle allows the user to support the front end of the tool without direct contact with the reaction arm, thereby maintaining ergonomic balance while preserving high torque capability.
Solution Approach 2:
The supporting handle is equipped with a second switch that requires simultaneous operation with the first switch to activate the motor. This self-service mechanism ensures that the user must properly grip both handles before the tool can operate, automatically enforcing ergonomic usage and preventing improper handling.
2Ease of operation
If the operator supports the tool at the front end by holding the front gear unit, then ergonomics are improved, but safety hazard increases due to risk of hand pinching between reaction arm and joint/workpiece
Solution Approach 1:
The supporting handle acts as a mediator that allows the user to support the front gear unit without direct hand contact with the reaction arm area. This intermediary structure provides the necessary ergonomic support while eliminating the pinching hazard by keeping the user's hand away from the dangerous zone between the reaction arm and workpiece.
Solution Approach 2:
The second switch mounted on the supporting handle creates a self-enforcing safety mechanism. The motor will not operate unless the user is properly gripping both the main handle and the supporting handle, ensuring that the hand is positioned safely away from the reaction arm before power is applied.
3Ease of operation
If handles are added to provide two-hand grip, then ergonomics and safety are improved, but tool complexity and bulkiness increase
Solution Approach 1:
The supporting handle structure serves multiple functions simultaneously: it provides ergonomic support for the front gear unit, mounts a safety switch, and acts as a structural element of the tool. This multi-functionality reduces the need for separate components, thereby limiting the increase in complexity despite adding the second handle.
Solution Approach 2:
The supporting handle combines several elements into a single integrated structure: the handle itself, the mounting for the second switch, and the support mechanism for the front gear unit. By merging these functions into one component rather than adding separate elements, the increase in complexity is minimized.
Data Source
AI summary
A handheld power tool includes a housing in which a motor coupled to an outgoing axle defining an axial direction is arranged, a front gear unit at a front end thereof, a first handle portion and a second supporting handle structure arranged at the front end of the housing and extending in a direction parallel to the axial direction in order to allow a user to support the tool at the front gear, and a first switch and a second switch configured to control a supply of energy to the motor. The handheld power tool is configured to require the user of the power tool to simultaneously operate the first switch and the second switch in order for energy to be supplied to the motor, and the second switch is arranged at the second supporting handle structure.