Dual-Start Actuator Power Tool Safety Mechanism
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Solution Overview
Problem
Power tools, such as open-end wrenches, pose operator hazards due to pinch points, and existing dual start actuators are cumbersome, inconvenient, and often defeated by operators, leading to ergonomic issues and increased costs.
Innovation Solution
A dual-start-actuator system with a rotatable tubular sleeve and magnetically actuated switch, requiring both switches to be activated within a short time frame to initiate and complete a power tool cycle, ensuring the operator's hands are safely positioned and preventing mechanical override.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual start actuators are positioned at preferred locations on the tool body, then safety function is improved, but physical size and weight of the tool increase
Solution Approach 1:
The patent combines the secondary start actuator function with the existing trigger mechanism. The trigger serves dual purposes: as the primary start actuator and as the secondary start actuator when pulled to full displacement. This merging eliminates the need for a separate secondary actuator component, thereby avoiding additional weight while maintaining the safety function.
Solution Approach 2:
The trigger mechanism is designed to perform multiple functions: it acts as the primary start actuator when pulled to the first position, and as the secondary start actuator when pulled to the second (full) position. This multi-functionality allows the same component to fulfill safety requirements without adding extra parts that would increase tool weight.
2Reliability
If dual start actuators are positioned at preferred locations on the tool body, then safety function is improved, but the tool size increases
Solution Approach 1:
The patent combines the secondary start actuator function with the existing trigger mechanism. The trigger serves dual purposes: as the primary start actuator and as the secondary start actuator when pulled to full displacement. This merging eliminates the need for a separate secondary actuator component, thereby avoiding additional length while maintaining the safety function.
3Reliability
If electrical wires are routed to the electrical switch for the secondary start actuator, then the safety function is enabled, but wiring complexity and cost increase
Solution Approach 1:
The patent combines the secondary start actuator function with the existing trigger mechanism. The trigger serves dual purposes: as the primary start actuator and as the secondary start actuator when pulled to full displacement. This merging eliminates the need for a separate secondary actuator component, thereby avoiding additional length while maintaining the safety function.
4Ease of operation
If operators can mechanically restrain the secondary start actuator in its ON position, then ease of operation is improved, but safety function is defeated
Solution Approach 1:
The patent implements a dynamic trigger mechanism where the trigger can be pulled to different positions: a first position for normal operation and a second (full) position to activate the secondary start actuator. The trigger is spring-biased to return to its initial position, preventing mechanical restraint in the ON position. This dynamic design allows easy operation while maintaining safety function.
Solution Approach 2:
The patent incorporates a spring mechanism that automatically returns the trigger to its initial position after actuation. This preliminary anti-action prevents the trigger from being mechanically restrained in the ON position, as the spring continuously exerts a restoring force. This ensures the safety function cannot be defeated while maintaining ease of operation.
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
The system effectively discourages operators from contacting pinch points, allows efficient tool operation, reduces ergonomic burden, and simplifies manufacturing and maintenance while preventing unintended start-ups.
Implementation Method 1
magnetically actuated switch
Data Source
Figure 1~2
Figure 3~4
AI summary
A power tool system includes a two-handed power tool having first and second start actuators, one for each hand of an operator. A controller prevents the power tool from initiating an operating cycle unless both actuators are turned ON to reduce the possibility of the operator's hands being disposed in a hazardous position during operation of the power tool. To discourage manual override of the dual-start-switch system, the controller prevents the power tool from initiating an additional operating cycle until both actuators have been switched OFF and then ON again. The second actuator includes a tubular sleeve that extends over part of the power tool to allow the sleeve to slide axially relative to the power tool between ON and OFF positions. Axial movement of the sleeve from its OFF position to its ON position turns ON the second start actuator.