Clutch Assembly for Power Tools That Blocks Return-Stroke Fastener Rotation
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Solution Overview
Problem
Existing power tools, such as electric wrenches, require manual swinging of the grip during the return stroke to prevent fastener rotation, which is inefficient and can cause unintended loosening.
Innovation Solution
A power tool design incorporating a clutch assembly with first and second shaft locking assemblies that allow the drive shaft to remain stationary while the output shaft rotates in one direction, preventing the transmission shaft from rotating during the return stroke, using mechanisms like shaft locking rings, reversing wheels, and toggle blocks to control torque transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the power tool uses a motor to tighten or loosen the fastener, then the fastening operation can be automated, but during the return stroke the electric wrench drives the fastener to rotate which causes unintended loosening or rotation
Solution Approach 1:
The clutch assembly dynamically changes its locking state based on the rotation direction of the output shaft. During forward stroke, the first shaft locking assembly locks the transmission shaft to drive the fastener. During return stroke, the second shaft locking assembly locks the transmission shaft to prevent fastener rotation, while the first shaft locking assembly unlocks to allow relative rotation between output shaft and transmission shaft.
Solution Approach 2:
The clutch assembly acts as an intermediary mechanism between the motor and the fastener. It selectively engages or disengages the torque transmission path based on operation phase, controlling whether the transmission shaft rotates with the output shaft or remains locked stationary.
2Object-generated harmful factors
If the user manually swings the grip during return stroke to prevent fastener rotation, then unintended loosening is avoided, but the operation becomes inefficient and requires additional manual effort
Solution Approach 1:
The clutch assembly automatically performs the function of preventing fastener rotation during return stroke without requiring user intervention. The second shaft locking assembly self-activates when the output shaft rotates in reverse direction, locking the transmission shaft and preventing fastener rotation automatically.
3Power
If the first shaft locking assembly prevents the transmission shaft from rotating during forward stroke, then torque is effectively transmitted to the fastener, but the structure becomes more complex with multiple shaft locking assemblies
Solution Approach 1:
The clutch assembly serves multiple functions: during forward stroke, the first shaft locking assembly transmits torque to drive the fastener; during return stroke, the second shaft locking assembly prevents fastener rotation while the first shaft locking assembly allows relative rotation. This multi-functional design consolidates what would otherwise require separate mechanisms into a single integrated assembly.
Data Source
AI summary
A power tool includes a motor including a drive shaft; a clutch assembly; and a transmission assembly connecting the motor to the clutch assembly. The clutch assembly includes a first shaft locking assembly, a second shaft locking assembly, a transmission shaft, and a first output shaft, the first shaft locking assembly is sleeved on the transmission shaft and the first output shaft, and the second shaft locking assembly connects the transmission assembly to the first shaft locking assembly. When the drive shaft remains stationary and the first output shaft rotates along a first direction, the first shaft locking assembly prevents the transmission shaft from rotating. When the drive shaft remains stationary and the first output shaft rotates along a second direction, the first shaft locking assembly drives the transmission shaft to rotate, and the second shaft locking assembly prevents the transmission shaft and the first output shaft from rotating.