Hammer Drill Dual-Sensor Torque Detection
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Solution Overview
Problem
Existing hammer drills inaccurately detect excessive reaction torque when a tool bit is unintentionally locked, leading to potential uncontrollability of the tool body during operation.
Innovation Solution
A hammer drill equipped with a first sensor to detect torque on the tool bit and a second sensor to detect motion of the tool body, utilizing an electromagnetic clutch as a torque transmission interrupting mechanism, which interrupts torque transmission when preset thresholds are met, ensuring accurate detection and prevention of uncontrollable states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotation sensor is used to predict future uncontrollability of the tool body, then the tool body uncontrollability can be prevented, but false detection may occur when the user intentionally moves the tool body
Solution Approach 1:
The detection function is segmented into two independent sensors: a rotation sensor for detecting tool body rotation and a torque sensor for detecting tool bit torque. This segmentation allows the system to distinguish between intentional user movements (which may cause tool body rotation but not excessive torque) and unintentional locking conditions (which cause both rotation and excessive torque), thereby eliminating false detections while maintaining reliability.
Solution Approach 2:
The torque sensor acts as an intermediary verification mechanism between the rotation sensor detection and the torque transmission interruption. By introducing this intermediate detection layer, the system can confirm whether detected rotation is due to actual uncontrollability or intentional user movement, preventing false positive interruptions while ensuring reliable safety detection.
2Reliability
If the torque transmission interrupting mechanism is activated to prevent uncontrollability, then operational safety is improved, but torque transmission may be interrupted during normal intentional operations
Solution Approach 1:
The control logic is segmented to require simultaneous satisfaction of two conditions (tool body rotation threshold AND tool bit torque threshold) before activating the torque transmission interrupting mechanism. This segmented control approach ensures that normal intentional operations (which satisfy only one condition) do not trigger interruption, while actual uncontrollable conditions (satisfying both conditions) do trigger the safety mechanism, thus maintaining both safety and operation continuity.
3Device complexity
If a single sensor is used to detect tool body motion, then the device complexity is reduced, but the measurement precision of reaction torque detection deteriorates
Solution Approach 1:
The detection system is segmented into two specialized sensors: a rotation sensor specifically for detecting tool body rotational motion and a torque sensor specifically for detecting tool bit torque. This segmentation provides superior measurement precision for reaction torque detection compared to using a single general-purpose sensor, as each sensor is optimized for its specific measurement function.
Solution Approach 2:
The dual-sensor system serves multiple functions: the rotation sensor detects tool body rotation for safety monitoring, the torque sensor detects tool bit torque for uncontrollability detection, and together they enable accurate distinction between intentional and unintentional operations. This multi-functionality justifies the increased device complexity by providing comprehensive monitoring capabilities that a single sensor cannot achieve.
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
The solution reliably detects excessive reaction torque, preventing the tool body from becoming uncontrollable by maintaining or interrupting torque transmission based on sensor readings, thus enhancing operational safety and accuracy.
Implementation Method 1
an electromagnetic clutch that is disposed in a rotary drive path of the rotary drive mechanism and can transmit torque and can interrupt the torque transmission between the motor and the tool bit
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Provided is a power tool which is capable of more reliably detecting excessive reaction torque acting on a tool body. More specifically, provided is a handheld power tool which causes a tip tool (119) to rotate so as to carry out a predetermined machining operation, the handheld power tool comprising a tool body (103), a motor (111) which is housed in the tool body (103) and causes the tip tool (119) to rotate, a first sensor (151) which detects the torque state of the tip tool (119), a second sensor (159) which detects the motion state of the tool body (103), and a torque cut-off mechanism (134) which cuts off the transmission of torque between the motor (111) and the tip tool (119). The torque cut-off mechanism (134) is configured to cut off the transmission of torque on the condition that the first sensor (151) and the second sensor (159) respectively detect a preset threshold value for the first sensor (151) and the second sensor (159).