Motor Device Temperature-Adaptive Over-Discharge Detection
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Solution Overview
Problem
The operable range of power tools using rechargeable batteries is narrowed due to temperature variations affecting the resistance of internal resistors, leading to premature power supply stoppages, even under normal operating conditions.
Innovation Solution
A control circuit that adjusts determination values for over-discharge detection based on usage environment temperature, using a higher value (V1) at higher temperatures and a lower value (V2) at lower temperatures to prevent unnecessary power supply stoppages, ensuring stable operation across varying temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed determination value is used for over-discharge detection, then the detection method is simple, but the operable range is narrowed due to temperature variations
Solution Approach 1:
The determination value for over-discharge detection is changed from a fixed value to a dynamic value that varies with temperature. The control unit adjusts the determination value based on the detected temperature, allowing the system to adapt to different environmental conditions and prevent premature power cutoffs while maintaining detection functionality.
2Adaptability or versatility
If the determination value is lowered to account for temperature effects, then the operable range is extended, but the risk of false abnormality detection increases
Solution Approach 1:
The control unit continuously monitors the temperature and uses this feedback to dynamically adjust the determination value. By establishing a correlation between temperature and appropriate determination values, the system maintains accurate abnormality detection across different temperature conditions, preventing both false positives and false negatives.
3Reliability
If power supply is stopped early to protect the battery, then battery protection is ensured, but the productivity of the power tool is reduced
Solution Approach 1:
The system changes the parameter used for over-discharge detection from a fixed voltage threshold to a temperature-dependent voltage threshold. By adjusting the determination value according to temperature conditions, the system maintains proper battery protection while avoiding premature power cutoffs under normal operating conditions, thus preserving productivity.
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
This approach stabilizes the operable range of power tools by accurately determining over-discharge conditions based on temperature-dependent voltage changes, preventing premature power cutoffs and extending the tool's operational range, especially in low-temperature environments.
Implementation Method 1
a temperature detection element that detects the usage environment temperature
Implementation Method 2
a voltage detection circuit that detects the voltage of the rechargeable battery
Data Source
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AI summary
The disclosed motor device contains: an electric motor that operates by receiving a power supply from a secondary battery; a voltage detection unit that detects the voltage of the secondary battery; a determination unit that determines anomalies on the basis of the comparison between determination values (V1, V2) and the voltage of the secondary battery detected by the voltage detection unit; a control unit that controls the operation of the electric motor in accordance with the determination results of the determination unit; and a temperature detection unit that detects the temperature of the use environment. The determination unit alters the determination values (V1, V2) in accordance with the temperature detected by the temperature detection unit, and conducts anomaly determination on the basis of the altered determination values.