Electric Tool Clutch Design for Precise Fastening Torque
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Solution Overview
Problem
Existing electric rotary tools face challenges in accurately controlling torque, leading to potential over-tightening of fastening members due to inertial forces persisting after the motor stops, which can result in excessive torque application.
Innovation Solution
An electric tool design incorporating a motor, a holder, a transmission mechanism, a torque detector, an electronic clutch, and an inhibiting mechanism that prevents the transmission of inertial force from the motor to the holder upon activation of the electronic clutch, ensuring precise torque control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the motor unit is stopped based on calculated fastening torque, then the fastening torque control is improved, but the inertial force causes the motor to continue running and results in over-tightening
Solution Approach 1:
The patent extracts the harmful inertial force from the system by introducing a one-way clutch mechanism that separates the motor's rotational motion from the fastening mechanism. When the motor stops, the one-way clutch disengages, preventing the inertial force from being transmitted to the fastening member, thus eliminating over-tightening while maintaining torque control accuracy.
Solution Approach 2:
The one-way clutch acts as an intermediary mechanism between the motor and the fastening mechanism. It allows torque transmission during normal operation but blocks inertial force transmission when the motor stops, serving as a mediator that resolves the contradiction between torque control and inertial force effects.
2Duration of action of stationary object
If the motor unit continues running due to inertial force after stopping, then the motor stopping time is extended, but the fastening torque exceeds the preset value
Solution Approach 1:
The one-way clutch extracts the harmful extension of motor running time by mechanically disconnecting the fastening mechanism from the motor's inertial motion. This allows the motor to coast to a stop without transmitting additional torque to the fastening member, maintaining precision while accommodating the natural deceleration period.
3Manufacturing precision
If a one-way clutch is introduced to inhibit inertial force transmission, then the torque control accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent employs a simple, inexpensive one-way clutch mechanism that, while adding a component, uses a well-established, reliable, and cost-effective solution. The one-way clutch is a mature technology that provides the necessary torque control improvement without requiring complex control systems or expensive components.
4Speed
If the electronic clutch is activated to stop the motor, then the torque control response is improved, but the inertial force continues to affect the holder
Solution Approach 1:
The one-way clutch serves as a mechanical intermediary that complements the electronic clutch's electrical control. When the electronic clutch activates to stop the motor, the one-way clutch simultaneously prevents inertial force transmission to the holder, providing dual protection against over-tightening while maintaining rapid response.
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 effectively reduces the chances of over-tightening by inhibiting inertial force transmission, thereby enhancing the accuracy of torque control in electric tools.
Implementation Method 1
an idle structure which allows relative rotation between a first rotary shaft and a second rotary shaft in a rotational direction of the motor, but which inhibits relative rotation between the first rotary shaft and the second rotary shaft in a rotational direction opposite to the rotational direction of the motor
Data Source
AI summary
An electric tool includes a motor, a holder, a transmission mechanism, a torque detector, an electronic clutch, and an inhibiting mechanism. The holder is configured to hold a tip tool thereon. The transmission mechanism transmits motive power of the motor to the holder. The torque detector detects a torque value about output torque provided by the tip tool. The electronic clutch is activated when a predetermined condition about the torque value detected by the torque detector is satisfied and thereby controls the motor to make the motor stop running. The inhibiting mechanism is interposed between the motor and the holder. The inhibiting mechanism inhibits transmission of inertial force from the motor to the holder in response to activation of the electronic clutch.