Power Tool Clutch Spring Retainer Design
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Solution Overview
Problem
Existing power tool clutch mechanisms can suffer from reduced spring life and effectiveness due to twisting when the clutch ring rotates, which affects the torque transmission threshold and can lead to adverse events like fastener stripping or over-tightening.
Innovation Solution
A clutch assembly design where a spring retainer rotates together with the clutch adjustment ring, preventing twisting and maintaining axial stationarity, and a locking member transfers the holding force to the clutch face, allowing adjustable torque interruption based on output torque levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the clutch ring rotates to adjust the spring compression, then the torque threshold is adjustable, but the spring becomes twisted which reduces its life and effectiveness
Solution Approach 1:
The clutch mechanism is divided into separate functional components: the clutch ring for adjustment, the spring retainer for spring support, and the spring itself. This segmentation allows the spring retainer to rotate with the clutch ring while keeping the spring's functional end stationary, preventing twisting and maintaining reliability while preserving adjustability.
2Strength
If the spring is compressed to increase holding force, then torque transmission integrity is improved, but the spring becomes twisted when the clutch ring rotates
Solution Approach 1:
The spring retainer acts as an intermediary between the rotating clutch ring and the spring. It provides a stationary support point for the spring's functional end, allowing the clutch ring to rotate for adjustment without transmitting rotational motion to the spring, thereby maintaining both holding force and spring effectiveness.
3Measurement precision
If the locking member transfers holding force to the clutch face, then torque interruption control is improved, but the mechanism complexity increases
Solution Approach 1:
The locking member automatically engages and disengages based on the spring's holding force and the applied torque. When torque exceeds the threshold, the locking member is forced off the ramped surface, interrupting torque transmission. This self-acting mechanism provides precise torque control without requiring additional control systems, balancing precision with simplicity.
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 effectively prevents spring twisting, enhances clutch performance by maintaining torque transmission integrity, and reduces the risk of adverse events by allowing precise control over torque interruption.
Implementation Method 1
A spring is disposed between the clutch adjustment ring and the spring retainer
Implementation Method 2
The locking member is configured to transfer a holding force exerted by the spring to the clutch face
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A clutch (18) for a power tool (10) includes an adjustment ring (310) configured to move axially relative to the housing (12) of the tool (10) while being rotated relative to the housing (12). A spring retainer (390) is disposed axially rearward of the adjustment ring (310). The spring retainer (390) is coupled for rotation together with the adjustment ring (310) and configured to remain substantially axially stationary relative to the housing (12) when rotated. A spring (308) is disposed between the adjustment ring (310) and the spring retainer (390). A clutch face (222) is coupled to a portion of the transmission (16). A locking member (304) is disposed between the spring retainer (390) and the clutch face (222). The locking member (304) is configured to transfer a holding force exerted by the spring (308) to the clutch face (222). Rotation and axial movement of the adjustment ring (310) alters the holding force exerted by the spring (308). When an amount of output torque exceeds the holding force, torque transmission to the output spindle (20) is effectively interrupted.