Handheld Work Apparatus Throttle Trigger Latch Mechanism
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Solution Overview
Problem
Existing handheld work apparatuses, such as top-handle chain saws, allow the engaging of the starting position without the throttle trigger being pressed, which is undesirable.
Innovation Solution
The apparatus includes a throttle trigger with a starting position and a non-actuated position, a throttle trigger lock, and an operating-mode selector with latch elements that prevent engagement of the starting position unless the throttle trigger is actuated, ensuring the operating-mode selector can only be moved when the throttle trigger is pressed, using a combination of pivot paths and latch elements to secure the starting position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the operating-mode selector is freely pivotable without throttle trigger actuation, then the starting position can be engaged without pressing the throttle trigger, but this creates a safety hazard allowing accidental activation
Solution Approach 1:
The patent requires preliminary action by actuating the throttle trigger before the operating-mode selector can be engaged in the starting position. The latch element is positioned such that it can only engage with the throttle trigger's latch-receiving element when the throttle trigger is in its actuated state, thereby preventing accidental engagement without intentional throttle activation.
Solution Approach 2:
The patent introduces a latch element and latch-receiving element as intermediary components between the operating-mode selector and the throttle trigger. These intermediaries create a mechanical coupling that only allows engagement when the throttle trigger is properly actuated, serving as a mediator that enforces the safety condition while enabling the desired operation.
2Reliability
If the second latch element is positioned inside the pivot path of the first latch element, then secure latching is achieved, but the operating-mode selector cannot be freely pivoted when throttle trigger is not actuated
Solution Approach 1:
The patent employs dynamic positioning of the latch element relative to the pivot path. When the throttle trigger is actuated, the second latch element moves into the pivot path of the first latch element, enabling secure latching. When the throttle trigger is not actuated, the second latch element remains outside the pivot path, allowing free pivoting of the operating-mode selector. This dynamic arrangement resolves the contradiction between secure latching and free pivoting.
Data Source
AI summary
The invention relates to a handheld work apparatus having a handle. A throttle trigger and a throttle trigger lock are arranged on the handle. An operating-mode selector having an off position, an operating position and a starting position is provided. The selector, trigger lock and the trigger are pivotally mounted. A first latching element is provided on the selector and a second latching element is provided on the trigger element, which coact in the starting position of the selector and the starting position of the trigger and hold the trigger in its starting position. To ensure that the starting position of the selector can only be engaged when the trigger is actuated, the second latching element lies outside of the pivot path of the first latching element in the non-actuated position of the trigger.