Handheld Power Tool Extension Unit for Torque and Weight Trade-off
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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 and the need for heavy front gear units and reaction arms, especially when dealing with screws in hard-to-reach positions.
Innovation Solution
A handheld power tool design featuring a lightweight extension unit attached between the motor housing and the torque multiplier unit, allowing for reduced weight and improved ergonomics, with a telescopic option for enhanced reach and safety by positioning the reaction arm closer to the screw joint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If heavy front gear units (torque multipliers) are used to provide high torque levels, then the required torque is achieved, but the weight of the tool increases and weight distribution shifts towards the front end, worsening ergonomics
Solution Approach 1:
The tool is divided into distinct functional modules: motor housing, extension unit, and torque multiplier unit. This segmentation allows each component to be optimized independently, with the torque multiplier being a self-contained unit that can be positioned away from the motor housing, reducing the overall weight impact on ergonomics while maintaining high torque capability.
Solution Approach 2:
The extension unit introduces a new spatial dimension by extending the output shaft axially away from the motor housing. This dimensional change allows the torque multiplier to be positioned at the end of the extension rather than directly coupled to the motor, redistributing weight along the tool's length and improving balance and operator comfort.
2Length of moving object
If the output shaft is extended with an extender to reach screws in hard to reach positions, then reach is improved, but the extension must withstand high torque levels making it heavy
Solution Approach 1:
The extension function is separated from the torque transmission function. The extension unit serves only as a positional offset for the output shaft, while the torque multiplier unit handles all high-torque operations. This segmentation allows the extension unit to be made from lightweight materials with smaller diameter, as it does not need to transmit high torque.
Solution Approach 2:
The extension unit acts as an intermediary component that connects the motor housing to the torque multiplier unit. It provides the necessary reach extension while transferring only low-torque rotational motion, allowing the use of lightweight materials such as aluminum or composite materials instead of heavy steel required for direct torque transmission.
3Stability of the object's composition
If a reaction arm is positioned at the power tool to withstand high torques, then torque stability is improved, but the operator's hand risks getting squeezed or pinched between the reaction arm and work piece, creating safety hazards
Solution Approach 1:
The reaction arm is extracted from the power tool assembly and repositioned to attach directly to the work piece or work environment. This separation removes the safety hazard from the operator's vicinity while maintaining the necessary torque stability, as the reaction arm now provides leverage against the work piece itself rather than the tool housing.
Solution Approach 2:
The reaction arm is repositioned in space to attach to the work piece rather than the tool. This spatial repositioning changes the geometry of the torque application, allowing the reaction force to be applied at a distance from the operator's hand, eliminating the pinching hazard while maintaining torque stability through extended leverage.
Data Source
Figure 1
Figure 2
AI summary
The present specification relates to a hand held power tool (1) comprising a motor housing (10) in which a motor coupled to an outgoing shaft defining an axial direction is arranged. A torque multiplier unit (20) extending in the axial direction. The hand held power tool further comprising an extension unit (30) arranged to extend in the axial direction and attached between the motor housing (10) at a front end (10a) thereof and the torque multiplier unit (20) at a back end (20b) thereof. The extension unit (30) drivingly connects the rotor to an input axis (40) of the torque multiplier unit (30).