Electric Tool Clutch Control for Accurate Fastening Torque
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Solution Overview
Problem
Existing electric tools struggle with accurately controlling fastening torque, leading to the potential over-tightening of screws, bolts, or nuts due to the inertial force of the motor after torque detection.
Innovation Solution
An electric tool with a clutch mechanism that switches between transmitting and interrupted states based on torque detection, using electronic control to quickly adjust the clutch mechanism, thereby reducing the rotation of the tool and preventing over-tightening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the motor is stopped by controlling the drive current when fastening torque is reached, then the motor unit can be stopped in principle, but the motor takes time to stop due to inertial force causing over-tightening
Solution Approach 1:
The clutch mechanism extracts the load-carrying function from the motor system. When the clutch disengages, it separates the motor's rotational inertia from the fastening mechanism, allowing the motor to coast to a stop without continuing to drive the fastening operation. This extraction of the load path resolves the contradiction by enabling timely torque control while accommodating the motor's inherent stopping delay.
Solution Approach 2:
The clutch mechanism acts as an intermediary between the motor and the fastening mechanism. It mediates the torque transmission by engaging when torque is needed and disengaging when torque limit is reached. This intermediary component allows the motor to stop independently while the clutch controls the actual torque application to the fastening member, achieving both timely response and accurate torque control.
2Measurement precision
If a clutch mechanism is added to quickly interrupt torque transmission, then torque control accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical clutch actuation systems with electromagnetic control. The clutch is engaged or disengaged by controlling the drive current to the motor, eliminating the need for separate mechanical actuators, linkages, or springs. This substitution maintains the torque control function while significantly simplifying the overall device structure.
Solution Approach 2:
The drive current control system performs multiple functions: it drives the motor during normal operation and simultaneously serves as the actuation mechanism for the clutch. By making the electrical control system universal, the patent eliminates dedicated mechanical clutch actuation components, reducing device complexity while maintaining effective torque control.
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 electric tool achieves precise torque control by quickly switching the clutch mechanism to the interrupted state, minimizing the chances of over-tightening fastening members and improving accuracy.
Implementation Method 1
An electromagnet 91 includes a magnetic pole 911
Implementation Method 2
A first positioning member 71 adjacent to the first position is composed of a ferromagnetic material to attract the permanent magnet
Data Source
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Figure 2
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AI summary
An object of the present disclosure is to control an electric tool more accurately according to torque. An electric tool (1) includes a holder (11), a motor (15), a transmission mechanism (3), a torque detection unit, a clutch mechanism (C1), and a controller. The holder (11) is configured to hold a tip tool (12) thereon. The transmission mechanism (3) transmits torque of the motor (15) to the holder (11). The torque detection unit detects the torque transmitted from the motor (15) to the holder (11). The clutch mechanism (C1) is switchable from a transmitting state where the torque of the motor (15) is transmitted to the holder (11) to an interrupted state where no torque of the motor (15) is transmitted to the holder (11), and vice versa. The controller switches, when a predetermined condition about the torque detected by the torque detection unit is satisfied, the clutch mechanism (C1) from the transmitting state to the interrupted state.