Electric Power Tool Motor Lock Detection Control
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Solution Overview
Problem
Existing electric power tools may falsely determine a motor lock state due to large operation inputs, leading to incorrect lock state determinations and potential motor damage.
Innovation Solution
The electric power tool incorporates a counter, reset device, reference time changing device, lock state determination device, and invalidation device to prevent false lock state determinations by adjusting the reference time and invalidating counting operations based on operation inputs, ensuring accurate motor lock state assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the lock determination time is shortened to improve responsiveness, then the motor lock detection speed is improved, but false lock state determinations occur due to large operation inputs
Solution Approach 1:
The patent applies dynamics by making the lock determination time variable rather than fixed. The control device dynamically adjusts the lock determination time based on the operation amount of the trigger switch: when the operation amount is small, a longer lock determination time is used to avoid false detections; when the operation amount is large, a shorter lock determination time is used for faster response. This dynamic adjustment resolves the contradiction between detection speed and accuracy.
Solution Approach 2:
The patent changes the parameter of lock determination time based on the operation amount parameter. By establishing a correspondence between operation amount and lock determination time, the system adapts the timing parameter to different operating conditions, preventing false lock state determinations while maintaining appropriate detection speed for each scenario.
2Measurement precision
If the counter is reset to zero after each determination cycle, then the counting operation can continue accurately, but the counter value may immediately reach the lock determination time when a shorter lock determination time is newly selected, causing false determination
Solution Approach 1:
The patent applies preliminary action by having the control device determine whether to invalidate the counting operation before selecting a new lock determination time. When the operation amount changes significantly, the system preemptively invalidates the current counting operation before a new, shorter lock determination time is applied, preventing the counter from immediately reaching the new threshold and causing false determinations.
Solution Approach 2:
The patent applies preliminary anti-action by invalidating the counting operation in advance when conditions suggest a false determination might occur. This countermeasure prevents the harmful effect of false lock state determination by stopping the counting process before it can reach the newly selected shorter lock determination time.
Data Source
AI summary
A lock state occurrence determination apparatus includes a counter, a reset device, a reference time changing device, a lock state determination device, and an invalidation device. The invalidation device performs, in a case where a false determination of occurrence of a lock state of a motor is caused by the lock state determination device due to an operation input to operate a rotation speed of the motor, at least one of a first invalidation operation to invalidate the lock state determination device and a second invalidation operation to invalidate continuation of a counting operation by the counter.