Power Tool Interlock Mechanism Preventing Unintentional Activation
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Solution Overview
Problem
The existing power tools face operability issues when the interlock mechanism fails, causing simultaneous operation of the start and lock operation members, which complicates handle position and direction adjustments, leading to unintentional tool activation.
Innovation Solution
The power tool incorporates a modified interlock mechanism that allows the start operation member to move to the start position while preventing the lock operation member from locking, ensuring intentional operation and preventing unintentional tool activation, along with a design that allows the second unit to rotate with respect to the first unit for adjusting handle position and direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an interlock mechanism is provided to prevent simultaneous operation of start and lock operation members, then tool activation safety is improved, but device complexity increases
Solution Approach 1:
The patent introduces a control unit as an intermediary that mediates between the start operation member and lock operation member. Instead of direct mechanical interlocking, the control unit receives signals from both operation members and processes them according to predetermined conditions, thereby preventing simultaneous operation while maintaining operational flexibility and reducing mechanical complexity
Solution Approach 2:
The patent replaces the traditional mechanical interlock mechanism with an electronic control system. The control unit uses electrical signals and logic circuits to achieve the interlocking function, eliminating complex mechanical linkages, moving parts, and physical constraints while maintaining the safety function
2Ease of operation
If the second unit is allowed to rotate with respect to the first unit for handle adjustment, then ease of operation is improved, but the risk of unintentional tool activation increases
Solution Approach 1:
The patent implements feedback control where the control unit continuously monitors the states of both operation members and adjusts the power supply accordingly. When the lock operation member is operated during handle adjustment, the control unit detects this state and prevents power supply to the prime mover, providing feedback-based protection against unintentional activation while allowing free rotation for adjustment
Solution Approach 2:
The patent enables dynamic control of the power supply based on real-time operational context. The system adapts its behavior: allowing start operation when the lock member is in normal position, but blocking start operation when the lock member is being operated. This dynamic response allows handle adjustment freedom while preventing unintentional activation
Data Source
AI summary
A power tool is provided with a first unit, a second unit rotatable with respect to the first unit, a lock operation member and a lock cooperative switch. The lock operation member is configured to be operated by the user between a lock position and an unlock position, and configured to prevent rotation of the first and second units at the lock position and allow the rotation between the first and second units at the unlock position. The lock cooperative switch is disposed on the supply circuit of energy to the prime mover, and configured to enable the supply circuit when the lock operation member is at the lock position and cutoff the supply circuit when the lock operation member is at the unlock position.