Throttle Lockout Assembly With Dissimilar Actions for Safe Trigger Cycling
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Solution Overview
Problem
The existing throttle lockout mechanisms in hand-held power equipment can be inadvertently actuated when the operator grasps the handle, leading to unsafe operation, and require repetitive dissimilar actions to cycle the throttle trigger, which is cumbersome.
Innovation Solution
A control assembly that requires a dissimilar enabling action to initially actuate the throttle lockout mechanism, allowing the throttle control member to be repeatedly actuated while the sensing member is in the actuated state without repeating the enabling action, using a combination of mechanical and electrical interlock assemblies such as catch mechanisms or keypads and switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a throttle lockout mechanism is provided on the handle portion to require actuation before throttle engagement, then safety is improved by preventing inadvertent actuation, but the risk of simultaneous compression of both lockout and throttle during grasping motion increases
Solution Approach 1:
The patent applies asymmetry by requiring dissimilar actions for different functions: a first dissimilar action (e.g., thumb pressure on a button) to actuate the sensing member, and a second dissimilar action (e.g., finger pull on the trigger) to actuate the throttle control member. This asymmetric control scheme prevents simultaneous actuation during grasping motion while maintaining safety.
Solution Approach 2:
The patent introduces an intermediary mechanism (the catch assembly with blocking portion and operative member) that mediates between the operator's input and the throttle control member. The blocking portion physically prevents the throttle control member from being actuated unless the catch assembly is first disengaged by the dissimilar action, thereby preventing inadvertent engagement.
2Object-affected harmful factors
If a dissimilar action is required to initially actuate the throttle lockout mechanism, then inadvertent actuation is prevented, but the operator burden increases due to repetitive enabling actions required to cycle the throttle trigger
Solution Approach 1:
The patent applies preliminary action by requiring the dissimilar enabling action only once to disengage the catch assembly and actuate the sensing member. After this preliminary action, the throttle control member can be repeatedly actuated without requiring repeated dissimilar actions, as the catch assembly remains disengaged and the sensing member stays actuated throughout continuous operation.
Solution Approach 2:
The patent applies dynamics by making the control system adaptive: after the initial dissimilar action disengages the catch assembly, the system transitions to a dynamic state where the throttle control member can be freely actuated without re-engaging the catch assembly, allowing seamless cycling during continuous operation.
3Ease of operation
If the throttle control member is made repeatedly operable after initial sensing member actuation, then ease of operation is improved by allowing seamless throttle cycling, but the risk of unintended actuation during normal handling increases
Solution Approach 1:
The patent applies segmentation by dividing the control mechanism into distinct functional segments: the catch assembly (with blocking portion and operative member) that prevents unintended actuation, and the sensing member/throttle control member pair that enables repeated operation. This segmentation allows the system to provide both safety and ease of operation simultaneously.
Data Source
AI summary
A hand-held power tool (100) may include an electric power source (110), an electric motor (120) selectively coupled to the electric power source (110), a working assembly (130) operably coupled to the electric motor (120) to perform a working function responsive to actuation of the electric motor (120), and a control assembly (140) operably coupled to the electric motor (120) to provide selective control over actuation of the electric motor (120). The control assembly (140) may be configured to provide the selective control based on performance of at least two dissimilar operator actions. The control assembly (140) may include a sensing member (210) and a throttle control member (200). The sensing member (210) may be configured to be operable to an actuated state responsive to an enabling action comprising a first of the two dissimilar operator actions. The throttle control member (200) may be configured to be repeatedly operable responsive to actuation of the throttle control member (200) while the sensing member (210) is in the actuated state. Actuation of the throttle control member (200) may include a second of the two dissimilar operator actions.