Rechargeable Electric Tool Voltage Warning and Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rechargeable electric tools face issues due to the memory effect in secondary batteries, which reduces battery capacity over time, and are rendered unusable in low temperature environments due to premature power supply interruption.
Innovation Solution
A rechargeable electric tool with a voltage comparing device and a warning system that allows continued operation after voltage reduction warnings, enabling multiple uses before battery replacement and preventing premature power supply interruption, even in low temperatures, and allowing full discharge to mitigate memory effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the reference voltage is set higher than the discharge end voltage to prevent over-discharge, then the battery is protected from damage, but the battery capacity is gradually reduced due to the memory effect when repeatedly charged in a shallow depth of discharge state
Solution Approach 1:
The patent applies dynamics by making the reference voltage adjustable rather than fixed. The control circuit can dynamically set the reference voltage to different levels, allowing it to be higher than the discharge end voltage during normal operation to prevent over-discharge, and temporarily lowered to allow full discharge when needed to eliminate memory effects. This dynamic adjustment resolves the contradiction between protecting the battery and maintaining full capacity.
2Reliability
If the power supply to the motor is stopped when the battery voltage is lowered to the reference voltage, then the battery is protected from over-discharge, but the electric tool becomes unusable in cold and low temperature environments where the battery voltage is naturally lowered
Solution Approach 1:
The patent uses dynamics by making the reference voltage adaptable to operating conditions. In low temperature environments where battery voltage naturally drops, the control circuit can adjust the reference voltage threshold to account for this temperature effect, preventing false over-discharge interruptions while still protecting the battery during normal operation. This dynamic adaptation resolves the contradiction between battery protection and usability in cold environments.
3Reliability
If the power supply to the motor is interrupted when the warning is indicated, then the battery is protected from over-discharge, but the user loses the ability to perform multiple operations before battery replacement
Solution Approach 1:
The patent applies dynamics by allowing the reference voltage to be temporarily lowered during operation, enabling the motor to continue running even after the initial voltage warning. This dynamic adjustment allows users to complete multiple operations before battery replacement is necessary, while still maintaining battery protection through the overall voltage monitoring system. The system dynamically balances protection with productivity needs.
Data Source
AI summary
A rechargeable electric tool includes a warning device which monitors a voltage of a power source battery and indicates a warning by means of an LED or a buzzer when the power source voltage is reduced to be equal to or lower than a reference voltage. The tool is configured such that, even when the warning is indicated, a control to interrupt a power supply to a motor is not performed, thereby enabling a usual operation in response to an activating operation on a trigger switch.