Locking Pliers Handle Mechanism Prevents Unintentional Release
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Solution Overview
Problem
Locking pliers with overcenter linkage often unintentionally spring open when bumped or disturbed, leading to disengagement from work pieces due to the spring's bias towards the jaw-opening position.
Innovation Solution
A lock member is introduced that requires sequential movement in two different directions to transition between locking and release configurations, preventing unintentional unlocking by engaging a linkage latch or pivot latch to secure the linkage in the overcenter locked position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a spring is used to bias the linkage towards the jaw-opening position, then the pliers can easily release from the work piece, but the pliers may unintentionally spring open when bumped or disturbed
Solution Approach 1:
The release mechanism is segmented into two distinct movements: first moving the lock member axially to disengage from the engagement surface, then rotating it to the released position. This segmentation prevents accidental single-direction movements from triggering release, while still allowing intentional two-step release operations.
Solution Approach 2:
The lock member transitions from a static locked position to a dynamic two-step release process. The mechanism incorporates both axial and rotational degrees of freedom, creating a dynamic release sequence that requires deliberate user action rather than passive disturbance.
2Device complexity
If a simple latch mechanism is used, then the device complexity is reduced, but the mechanism cannot prevent unintentional unlocking
Solution Approach 1:
The lock member features asymmetric geometry with a specific engagement surface oriented at a defined angle relative to the longitudinal axis. This asymmetric design ensures that only a specific sequence of axial movement followed by rotation can disengage the latch, preventing accidental unlocking from random disturbances.
Solution Approach 2:
The engagement surface acts as an intermediary element between the lock member and the linkage system. This intermediate feature requires both axial displacement and rotational movement to overcome, serving as a mechanical gatekeeper that prevents unintentional release while maintaining overall mechanism simplicity.
Data Source
AI summary
A pair of pliers includes an upper structure, a lower structure including a lower handle, an over center linkage, and a lock member. The lock member is movable between a locking configuration and a release configuration. When the lock member is in the locking configuration, it prevents pivoting movement of the lower handle from a closed configuration and retains jaws of the pliers in a closed position. When the lock member is in the release configuration, it enables the lower handle to be moved away from the closed configuration and allows the jaws to move to an open position. Movement of the lock member from the locking configuration to the release configuration requires sequential movement of the lock member in a first direction and then in a second direction. The second direction is different than the first direction.