Swingable Trigger Lock Member for Impact Stress Distribution
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Solution Overview
Problem
Existing trigger switches in electrical tools are prone to lock member breakage due to stress concentration at the root of the lock member when impact is applied, particularly in tools with a projecting handle, leading to potential detachment and failure.
Innovation Solution
A trigger switch design featuring a swingably attached lock member that can move multi-axially with respect to the trigger, incorporating outward and inward projections for enhanced engagement and regulation, allowing for a swinging range that distributes stress and prevents concentration at a specific point, thus preventing breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lock member is rigidly fixed to the trigger, then the trigger is securely locked in the pulled-in state, but stress concentrates at the root of the lock member causing breakage under impact
Solution Approach 1:
The lock member is changed from a rigidly fixed structure to a dynamically movable one, capable of swinging relative to the trigger around a rotation axis. This dynamic configuration allows the lock member to absorb impact forces through rotational movement rather than transmitting all stress to the root connection, preventing breakage while maintaining locking function through the engagement between outward projections on the lock member and inward projections on the trigger.
2Strength
If the lock member is made swingable to prevent stress concentration, then breakage is prevented, but the attachment complexity increases
Solution Approach 1:
The connection between the lock member and trigger is segmented into discrete engagement elements: outward projections on the lock member and inward projections on the trigger. This segmentation allows the lock member to swing freely while maintaining secure attachment through the interlocking projections, avoiding the need for complex hinges or pivot mechanisms.
Solution Approach 2:
The outward and inward projections act as intermediary elements that mediate between the swingable lock member and the stationary trigger. These projections enable both movements (swinging) and constraints (preventing detachment) without requiring complex attachment structures, simplifying the overall design.
3Strength
If the lock member can swing multi-axially, then stress distribution is improved, but the attachment mechanism becomes more complex
Solution Approach 1:
The lock member is designed with multi-axial swing capability, allowing rotation around a vertical axis and potential movement in multiple directions. This dynamic freedom enables the lock member to distribute stress across different orientations when subjected to impact forces from various directions, improving strength without complex active control mechanisms.
Solution Approach 2:
The outward projections on the lock member and inward projections on the trigger are asymmetrically configured to allow swinging motion in multiple directions while preventing detachment. The asymmetric geometry enables stress distribution across different axes while maintaining a simple passive attachment mechanism.
4Manufacturing precision
If precise processing is required for the swing connection, then the swinging range is controlled accurately, but manufacturing cost increases
Solution Approach 1:
The swing connection is designed to utilize the natural play and clearance between the outward projections and inward projections, rather than requiring precisely controlled gaps. The structure self-adjusts to provide adequate swinging range through the inherent geometry of the engagement elements, eliminating the need for high-precision machining or assembly.
Solution Approach 2:
Instead of designing for minimal clearance, the connection allows excessive play between the projections, which is sufficient to enable the required swinging motion. This partial precision approach reduces manufacturing complexity while providing adequate functional performance.
Data Source
AI summary
A trigger switch has a trigger arranged projected and biased to a front side in a housing, and a lock member projecting from a side of the trigger towards the housing, and being engaged with a lock button projecting to the side from the housing to fix the trigger in a pulled-in state. The lock member is swingably attached to the trigger.