Direct-Drive Power Tool Locking for Manual Torque Application
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Solution Overview
Problem
Conventional motorized power tools struggle with manual torque application due to the drive lug freely rotating, making it difficult to apply precise torque without spinning the motor, especially in tight spaces.
Innovation Solution
A gear system with a locking mechanism that allows the power tool to selectively lock the drive mechanism, enabling both motorized and manual torque applications by preventing the drive lug from rotating relative to the tool.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the drive lug is allowed to rotate freely for manual torque application, then the user can manually rotate the tool, but the gears will be back-driven and the motor will spin, failing to transfer torque to the work piece
Solution Approach 1:
The patent employs a dynamic locking mechanism that can switch between locked and unlocked states. The locking mechanism includes a locking member that can engage with a locking surface on the motor shaft, dynamically preventing rotation when needed for manual torque application, and disengaging when motorized operation is required. This dynamic state change allows the system to adapt to different operational modes.
Solution Approach 2:
The locking mechanism acts as an intermediary between the motor shaft and the drive portion. It mediates the rotational motion by selectively allowing or preventing the transfer of rotational energy. When engaged, the locking mechanism intercepts the back-driving force from manual rotation and prevents it from reaching the motor, thus protecting the motor while still allowing manual torque application at the drive lug.
2Adaptability or versatility
If a locking mechanism is added to prevent drive lug rotation for manual torque application, then torque can be applied manually, but the device complexity increases
Solution Approach 1:
The locking mechanism is merged with the existing motor shaft and drive portion structure. The locking member integrates with the motor shaft assembly, and the locking surface is formed as part of the motor shaft structure. This merging approach allows the locking function to be added without requiring entirely separate components, thereby reducing overall device complexity.
Solution Approach 2:
The locking mechanism is designed to be self-actuating through the user's existing actions. When the user applies manual torque to the drive lug, the resulting back-driving force automatically engages the locking mechanism through the interaction between the locking member and locking surface. No separate actuation mechanism or additional controls are needed, making the system self-serving and reducing complexity.
3Ease of operation
If the switch is disposed on the head of the tool for direction selection, then the tool can change rotational direction, but it becomes challenging to access the switch when the tool is engaged with a fastener in a tight space
Solution Approach 1:
The switch is repositioned from the head of the tool (one-dimensional access) to the body or handle portion of the tool (access from multiple dimensions). This dimensional relocation allows the user to access the switch from various angles and positions, particularly when the tool head is engaged in tight spaces. The switch becomes accessible from the side or rear of the tool rather than requiring access to the front head area.
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
Enables precise manual torque application by locking the drive mechanism, allowing users to apply torque manually while preventing gear back-driving and motor spinning, enhancing control over torque application.
Implementation Method 1
The gear assembly includes spur gears, bevel gears and/or a worm gear drive to create a desired gear ratio
Implementation Method 2
a locking mechanism adapted to selectively prevent rotation of at least one of the motor shaft, gear mechanism, and drive portion
Data Source
AI summary
A motorized tool with a direct drive mechanism and a locking mechanism that allows the tool to be used to apply a manual load or torque. The tool includes a drive lug adapted to be driven in first and second rotational directions via a gear assembly, a motor adapted to drive the gear assembly to thereby the drive lug for the application of motorized torque, and a locking mechanism that is adapted to allow application of manual torque by the drive lug.