Ratchet Trigger Switch for Fixed Pull Position Speed Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional trigger switches for power tools cannot fix the trigger at any pull-in position, limiting the ability to maintain a constant drive speed during operation.
Innovation Solution
A trigger switch design featuring a movable engagement member with ratchet teeth and a restraint engagement member with a ratchet pawl, along with an urging member, allows the trigger to be fixed at any position through engagement, enabling constant speed operation by preventing movement in the opposite direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional locking member is used to lock the trigger in an on state, then the trigger can be locked in a pulled position, but the trigger cannot be fixed at any arbitrary pull-in position to maintain constant drive speed
Solution Approach 1:
The engagement mechanism is segmented into multiple discrete ratchet teeth on the movable engagement member and corresponding ratchet pawls on the restraint engagement member. This segmentation allows the trigger to be fixed at multiple discrete positions along its travel, enabling constant speed operation at various drive levels while maintaining a relatively simple overall structure.
Solution Approach 2:
The movable engagement member with ratchet teeth acts as an intermediary between the trigger and the restraint engagement member. It translates the continuous movement of the trigger into discrete engagement positions, allowing precise positioning without requiring complex direct locking mechanisms between the trigger and housing.
2Reliability
If the restraint engagement member prevents movement in the opposite direction from any position, then constant speed operation is enabled, but the device structure becomes more complex
Solution Approach 1:
The restraint engagement member is designed to dynamically engage and disengage based on trigger position. The ratchet pawl can freely engage with ratchet teeth at any position to prevent backward movement, but can be easily disengaged when forward movement is needed. This dynamic behavior provides reliable constant speed maintenance while keeping the mechanism simple through passive elastic engagement rather than active control.
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 the trigger to be securely fixed at any position, allowing for consistent drive speed control and efficient operation of power tools.
Implementation Method 1
the movable engagement member includes ratchet teeth arranged along a movement direction, the restraint engagement member includes a ratchet pawl, and the ratchet teeth of the movable engagement member and the ratchet pawl of the restraint engagement member engage so that the movable engagement member and the restraint engagement member engage
Implementation Method 2
the restraint engagement member includes an urging member that urges the ratchet pawl toward the ratchet teeth
Data Source
AI summary
A trigger switch TS includes a trigger that moves in a pulling direction in response to pressure of a pulling operation and moves in an opposite direction to the pulling direction in response to being released from the pressure. The trigger switch TS includes a lock guide 6 (movable engagement member) that moves in conjunction with movement of the trigger, and a ratchet ring 7 (restraint engagement member) that engages with the lock guide 6 to prevent movement of the lock guide 6 in the opposite direction to the pulling direction. The ratchet ring 7 allows the lock guide 6 to move in the pulling direction, and engages with the lock guide 6 to prevent movement in the opposite direction from a position to which the lock guide 6 is moved in the pulling direction.