Driver-Drill Electronic Clutch Control Across Speed Ranges
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Solution Overview
Problem
Existing driver-drills lack the ability to select clutch-actuation torques in low-speed mode that are higher than those in high-speed mode, and they struggle to detect the operating speed range and screwdriving mode in a compact design, especially when using electronic clutches.
Innovation Solution
A driver-drill with a speed change mechanism and a controlling means that allows for higher clutch-actuation torques in low-speed mode, along with a sensor system to detect the operating speed range and mode, using a magnetic sensor to detect the position of the speed change internal gear and a controller to modify motor control accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical clutch mechanism with a coil spring is used to provide clutch operation, then the clutch-actuation torque can be adjusted by manually rotating a clutch ring, but the clutch-actuation torques are always the same regardless of whether the driver-drill is operating in high speed range or low speed range
Solution Approach 1:
The patent replaces the mechanical clutch mechanism with an electronic clutch system. The controller monitors motor current (which correlates with output torque) and stops motor rotation when the current reaches a prescribed value, eliminating the need for mechanical clutch components like coil springs and clutch rings while achieving torque-based control.
Solution Approach 2:
The patent changes the control parameter from mechanical torque transmission to electrical current monitoring. By monitoring motor current as a proxy for output torque and using electronic control to stop rotation at preset current thresholds, the system achieves adaptable clutch-actuation torques for different speed ranges without mechanical complexity.
2Extent of automation
If an electronic clutch is used with a controller that monitors output torque, then the clutch operation can be controlled electronically, but it is necessary to electrically detect whether the driver-drill has been set to operate in screwdriving mode and whether high-speed mode or low-speed mode has been selected
Solution Approach 1:
The patent makes the existing magnetic sensor serve multiple functions: it detects both the speed change internal gear position (to determine high-speed or low-speed mode) and the action mode changing ring position (to detect screwdriving mode). This multi-functionality eliminates the need for separate detection systems while achieving full automation.
Solution Approach 2:
The patent enables the single magnetic sensor to self-serve multiple detection purposes by detecting the positions of different components (speed change internal gear and action mode changing ring) at different times or in different contexts, reducing the overall system complexity while maintaining automated control.
3Measurement precision
If sensors are added to detect speed change internal gear position and action mode, then the driver-drill can detect operating modes, but the overall size of the housing may have to increase
Solution Approach 1:
The patent makes the existing magnetic sensor multi-functional by using it to detect both the speed change internal gear position and the action mode changing ring position. This eliminates the need for additional sensors that would increase housing volume, while maintaining precise detection of operating modes through the sensor's ability to monitor multiple components.
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
Enables higher clutch-actuation torques in low-speed mode and compact detection of speed and mode, improving usability and design efficiency.
Implementation Method 1
a magnetic sensor to detect the position of the speed change internal gear
Data Source
AI summary
A driver-drill (1) includes: a controller (32), which stops rotation of a brushless motor (9) when a torque applied to a spindle (26) reaches a prescribed clutch-actuation torque; and a dial (65), which is capable of specifying, to the controller (32), the setting of the prescribed clutch-actuation torque within a prescribed high-low range of values. In the controller (32), a relationship between clutch-actuation torques and each value in the high-low range is set such that, in a first range in which the values are low, changes in the clutch-actuation torques are the same in the low-speed mode and in the high-speed mode and such that, in a second range outside of the first range, the clutch-actuation torques in the low-speed mode are higher than in the high-speed mode.