Power Tool Gear Shift Actuator Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power tools often stop prematurely due to battery voltage drops caused by internal resistance and wire resistance, leading to over-discharging, even when the battery state of charge is sufficient, as high current demands lower the battery voltage below a predetermined threshold.
Innovation Solution
A power tool with a motor, battery, and a control unit that includes a voltage sensor, torque detector, and gear shift actuator, which adjusts the speed reduction ratio of the power transmission unit based on detected load torque and battery voltage, shifting to higher ratios when voltage drops to prevent motor shutdown and reduce internal resistance influence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the motor is driven with high discharge current to maintain operation, then the motor can continue operating, but the battery voltage drops below the predetermined threshold causing premature shutdown
Solution Approach 1:
The power transmission unit dynamically adjusts the speed reduction ratio based on detected battery voltage levels. When voltage drops occur during operation, the system automatically shifts to a higher speed reduction ratio to reduce motor current demand, thereby maintaining operation while preserving battery voltage above the shutdown threshold.
Solution Approach 2:
The system changes the operational parameters by adjusting the speed reduction ratio in response to battery voltage conditions. This parameter change allows the motor to operate at lower current draws when battery voltage sags, preventing premature shutdown while maintaining productivity.
2Speed
If the speed reduction ratio is kept low to maintain high rotation speed, then the motor operates efficiently, but the discharge current increases causing voltage drop and premature shutdown
Solution Approach 1:
The system dynamically adjusts the speed reduction ratio based on battery voltage conditions. When voltage drops are detected, the system automatically increases the speed reduction ratio, which reduces rotation speed but also reduces current demand, thereby maintaining battery voltage stability and preventing shutdown.
Solution Approach 2:
The system takes preliminary action by detecting battery voltage trends and proactively adjusting the speed reduction ratio before the voltage drops below the shutdown threshold. This prevents the harmful effect of premature shutdown by counteracting voltage drops before they become critical.
3Quantity of substance
If the battery voltage threshold is set low to allow full battery usage, then battery capacity is maximized, but the motor stops prematurely due to voltage drop under load
Solution Approach 1:
The system uses dynamic adjustment of the speed reduction ratio to allow the motor to operate continuously even when battery voltage approaches lower thresholds. By automatically increasing the speed reduction ratio when voltage drops occur, the system can utilize more of the battery capacity while maintaining productive operation.
Solution Approach 2:
The control unit continuously monitors battery voltage and uses this feedback to adjust the speed reduction ratio in real-time. This feedback mechanism allows the system to optimize battery usage by adapting to changing voltage conditions, thereby maximizing both battery capacity utilization and motor operation duration.
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 solution allows continuous use of the power tool by reducing the impact of internal resistance and preventing over-discharging, enhancing operability by maintaining tool functionality even when battery voltage approaches the threshold.
Implementation Method 1
a voltage sensor that detects a battery voltage of the battery
Implementation Method 2
The power transmission unit reduces the rotation speed of the rotational power obtained from the motor
Implementation Method 3
A gear shift actuator that shifts a speed reduction ratio of the power transmission unit
Implementation Method 4
a torque detector that detects a load torque applied to the output shaft
Implementation Method 5
a motor that generates rotational power
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A power tool includes a control unit (23) that controls a gear shift actuator (27) to increase the speed reduction ratio of the power transmission unit (22) as the battery voltage detected by the voltage sensor (S) becomes less than or equal to a predetermined voltage when the speed reduction ratio of the power transmission unit (22) is low. By increasing the speed reduction ratio in this manner, the influence of the internal resistance of a battery pack (12) may be reduced. This allows for the power tool may to be continuously used and improves the operability. Further, the control unit (23) stops driving the motor (21) as the battery voltage of the battery (12) detected by the voltage sensor (S) becomes less than or equal to a predetermined voltage when the speed reduction ratio of the power transmission unit (22) is relatively high.