Electromagnetic Clutch Positioning for Compact Impact Tools
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Solution Overview
Problem
Existing impact power tools face challenges in reducing the size of the clutch while effectively preventing excessive reaction torque from acting on the tool body when the tool bit is unintentionally locked, as the clutch is typically large due to its placement in the power transmitting mechanism.
Innovation Solution
The impact tool incorporates a clutch positioned in a high-speed low-torque region before the motor's rotation speed reduction, equipped with a torque sensor or speed/acceleration sensor to detect excessive torque, allowing for timely interruption of torque transmission and featuring an electromagnetic clutch design for size reduction and easy control, with a separate clutch housing to prevent lubricant slippage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clutch is disposed in the power transmitting mechanism where rotation speed is reduced, then the clutch can effectively prevent reaction torque, but the size of the clutch is increased to allow transmission of high torque
Solution Approach 1:
Instead of placing the clutch in the low-speed high-torque region (after gear reduction) as in conventional designs, this patent inverts the approach by positioning the clutch in the high-speed low-torque region (before gear reduction). The clutch interrupts torque transmission at the motor output shaft where torque is still low, preventing excessive reaction torque from propagating through the power transmitting mechanism to the tool body. This inversion allows the clutch to remain small in size while still achieving effective reaction torque prevention.
2Volume of moving object
If the clutch is disposed in a high-speed low-torque region, then the clutch size is reduced, but the torque transmission capability must be maintained
Solution Approach 1:
The clutch performs preliminary action by interrupting torque transmission at an early stage in the power flow path, before the torque is amplified through gear reduction. By detecting excessive reaction torque at the motor output shaft and immediately disconnecting the clutch, the system prevents excessive torque from developing further down the power transmitting mechanism. This preliminary interruption maintains adequate torque transmission capability for normal operation while keeping the clutch size small.
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 configuration reduces the clutch's size and weight while effectively preventing excessive reaction torque, allowing for a more compact and efficient impact tool design.
Implementation Method 1
an electromagnetic clutch disposed on the clutch shaft and serving to transmit or interrupt transmission of torque from the motor output shaft to the clutch shaft
Data Source
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AI summary
Disclosed is a striking tool technology that contributes to reducing clutch sizes. The striking tool causes a tool bit (119) to perform a striking operation in the long axis direction and to perform a rotational operation about the long axis, thereby causing the tool bit (119) to carry out a predetermined machining operation. The striking tool comprises a tool body (103); a motor (111) which is housed in the tool body (103) and drives the tool bit (119); and a clutch (134) which, on a route where the torque of the motor (111) is transmitted to the tool bit (119), is disposed in a high rotational speed and low torque region that is a stage prior to where the rotational speed of the motor (111) is reduced, which transmits the torque of the motor (111) to the tool bit (119) in a normal state, and which cuts off the transmission of torque generated about the tool bit long axis in the tool body (103) if the torque exceeds a predetermined torque level.