Shaft Locking Assembly for Easier Power Tool Bit Changes
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Solution Overview
Problem
Handheld power tools require frequent accessory replacement, which is cumbersome due to the need for one-handed operation of shaft locking components, complicating the process and user experience.
Innovation Solution
A power tool design featuring a shaft locking assembly with multiple locking portions and an execution portion that can be easily switched between locked and unlocked states using a single operation assembly, allowing for safer and more efficient tool bit replacement without continuous one-handed operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional shaft locking components are used requiring one-handed operation, then the power tool structure is simple, but the accessory replacement process becomes cumbersome and user-unfriendly
Solution Approach 1:
The shaft locking assembly is segmented into distinct functional components: locking portions (with multiple locking positions), an execution portion (actuator), and a first locking assembly. This segmentation allows each component to perform its specific function independently, enabling safe two-handed operation where one hand holds the tool and the other operates the locking mechanism, thereby simplifying accessory replacement without excessive complexity
Solution Approach 2:
The execution portion acts as an intermediary mechanism between the user's manual input and the locking portions. When the execution portion moves to a first position, it engages with the locking portions to lock the drive shaft; when moved to a second position, it releases the locking portions. This intermediary mechanism translates simple user input into reliable locking/unlocking actions, improving ease of operation while maintaining controlled complexity
2Reliability
If multiple locking portions are added to improve safety during accessory replacement, then user safety improves, but the locking assembly complexity increases
Solution Approach 1:
The locking portions are designed with multiple locking positions that serve different functions: one position locks the drive shaft for safe accessory replacement, while other positions may accommodate different operational modes or accessory types. This multi-functionality approach allows a single locking assembly structure to provide enhanced safety through multiple locking states without proportionally increasing overall device complexity
Solution Approach 2:
The first locking assembly is merged with the execution portion and locking portions into an integrated shaft locking assembly. By combining these components into a unified structure rather than separate mechanisms, the patent achieves reliable safety functionality through coordinated operation of multiple parts while avoiding the complexity that would result from entirely separate locking systems
3Reliability
If the execution portion is designed to engage with multiple locking portions, then the locking mechanism becomes more reliable, but the operational complexity increases
Solution Approach 1:
The execution portion is designed to automatically engage with the appropriate locking portion based on its position, without requiring the user to manually select or coordinate multiple locking actions. When the execution portion moves to the first position, it self-engages with the locking portions; when moved to the second position, it self-releases. This self-service mechanism reduces operational complexity by eliminating the need for coordinated one-handed manipulation of multiple locking elements, while maintaining reliability through deterministic engagement
Data Source
AI summary
A power tool includes a shaft locking assembly and an electric motor. The shaft locking assembly includes a first state where a chuck is restrained from rotating and a second state where the chuck is released to rotate. The shaft locking assembly includes multiple locking portions and an execution portion. The multiple locking portions are formed on or connected to a drive shaft or the chuck. The execution portion is optionally engaged with at least one locking portion. When the execution portion moves to a first position, the execution portion is engaged with the at least one locking portion such that the shaft locking assembly is in the first state. The electric motor includes a stop state where the first position is in the at least one locking portion when the electric motor stops.