Clutch Unit Retainer Hook for Spring Lock Stability
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Solution Overview
Problem
The conventional clutch unit's inner centering spring is prone to detachment from the retainer due to assembly tolerance, leading to a loss of its elastic function, which affects the reliable transmission and interruption of torque.
Innovation Solution
A hook portion is provided on the retainer's end surface to securely hold the lock portion of the elastic member, preventing detachment and ensuring the elastic member's function is maintained, along with an arc-shaped end surface and a protruding dimension of the hook portion set between 1/6 to 1/3 of the elastic member's wire diameter for stability and ease of assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the lock portion of the elastic member is locked to the end surface of the retainer without additional retention features, then the structure is simple and ease of manufacture is improved, but the reliability deteriorates due to detachment caused by assembly tolerance
Solution Approach 1:
The end surface of the retainer is segmented into multiple engagement surfaces at different positions, allowing the lock portion to engage with multiple discrete locations. This segmentation provides redundant retention points that prevent detachment even if one engagement point is insufficient due to assembly tolerance variations.
Solution Approach 2:
The retainer is designed with pre-formed engagement surfaces and protrusions that guide and pre-position the lock portion during assembly. This preliminary structural preparation ensures proper alignment and engagement before final assembly, reducing the impact of assembly tolerance on retention reliability.
2Manufacturing precision
If the end surface of the retainer is made flat for simplicity, then manufacturing precision requirements are reduced, but the stability of the elastic member deteriorates
Solution Approach 1:
While the overall end surface remains simple for manufacturing, specific local regions are designed with elevated engagement surfaces and protrusions. This local quality enhancement provides stable engagement points without requiring the entire end surface to be precisely machined, thus maintaining both manufacturability and stability.
Solution Approach 2:
The engagement surfaces incorporate curved or arc-shaped features that better conform to the lock portion geometry. These curved surfaces provide more stable contact and engagement compared to purely flat surfaces, improving retention stability while remaining manufacturable with standard tolerances.
3Device complexity
If the retainer structure is simplified without additional retention features, then device complexity is reduced, but the lock portion detachment risk increases
Solution Approach 1:
The retainer structure performs multiple functions: it retains the engagement elements, provides elastic biasing through the locked elastic member, and incorporates built-in retention features (engagement surfaces and protrusions) to prevent lock portion detachment. This multi-functionality is achieved within a single integrated component without adding separate retention mechanisms, thus avoiding increased device complexity.
Solution Approach 2:
The retainer is designed to self-retain the lock portion through its own structural features (engagement surfaces and protrusions) without requiring external retention components. The retainer's geometry itself provides the retention function, allowing it to serve itself and eliminating the need for additional complexity.
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 clutch unit achieves high reliability by preventing lock portion detachment and ensuring the elastic member's effective operation, enhancing the transmission and interruption of torque.
Implementation Method 1
an elastic member including a lock portion to be locked to an end surface of the retainer, for accumulating an elastic force obtained by the torque input from the input-side member and for restoring the retainer to a neutral state by releasing the elastic force obtained by the torque input from the input-side member and thus accumulated
Data Source
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AI summary
Provided is a clutch unit, including: a lever-side clutch portion provided on an input side, for controlling transmission/interruption of rotational torque to an output side with lever operation; and a brake-side clutch portion provided to the outside side, for transmitting a torque input from the lever-side clutch portion to the output side and for interrupting a torque reverse-input from the output side, in which: the lever-side clutch portion includes a retainer for retaining a plurality of cylindrical rollers at predetermined intervals in a circumferential direction for controlling transmission/interruption of the torque input from a lever-side outer race through engagement/disengagement between the lever-side outer race to which torque is input and an inner race transmitting the torque from the lever-side outer race to the brake-side clutch portion; and an inner centering spring including a lock portion to be locked to an end surface of the retainer, for accumulating an elastic force obtained by the torque input from the lever-side outer race and for restoring the retainer to a neutral state by releasing the elastic force obtained by the torque input from the lever-side outer race and thus accumulated; and on the end surface of the retainer, a hook portion for holding the lock portion of the inner centering spring is provided in a protruding manner.