Clutch Unit C-Shaped Spring and Friction Ring Design
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Solution Overview
Problem
Conventional clutch units experience noise issues due to the outer centering spring climbing onto an inclined portion during lever operation and disengagement of the inner centering spring from the retainer, while also facing challenges with maintaining a consistent fastening allowance between the friction ring and output shaft, leading to vibration when excessive torque is applied.
Innovation Solution
The clutch unit employs a C-shaped band plate-like spring member with specific lock portions and an inclined stationary-side member design to prevent the elastic member from climbing, and uses polybutylene terephthalate for the friction ring to maintain a consistent fastening allowance, ensuring reliable torque transmission and reduced vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the outer centering spring is provided between the lever-side outer ring and the cover, then the lever-side outer ring can be restored to the neutral state, but the elastic member climbs onto the inclined portion of the cover during lever operation causing noise
Solution Approach 1:
The patent extracts the problematic inclined portion from the cover structure. By removing the inclined portion that caused the elastic member to climb, the noise-generating mechanism is eliminated while preserving the cover's primary function of housing and supporting the clutch components.
Solution Approach 2:
The patent introduces a stepped portion as an intermediary structure between the elastic member and the cover. This stepped portion acts as a physical barrier or stop that prevents the elastic member from climbing onto the inclined portion, thereby eliminating the noise issue while maintaining the restorative function of the elastic member.
2Ease of operation
If the inner centering spring is provided between the retainer and the cover, then the retainer can be restored to the neutral state, but the inner centering spring disengages from the retainer during operation
Solution Approach 1:
The patent applies asymmetry by making the inner diameter of the retainer larger than the outer diameter of the inner centering spring. This creates a clearance or gap between the spring and retainer inner wall, which prevents the spring from disengaging during operation while still allowing it to function effectively in restoring the retainer to the neutral state.
Solution Approach 2:
The patent designs the retainer and spring dimensions in advance during the design phase, establishing the size relationship (inner diameter of retainer > outer diameter of spring) before operation begins. This preliminary dimensional configuration ensures that the spring remains engaged with the retainer throughout operation, preventing disengagement issues.
3Power
If the friction ring is press-fitted to the output shaft with fastening allowance, then rotational resistance can be generated, but the fastening allowance reduces over time causing vibration under excessive torque
Solution Approach 1:
The patent changes the material parameter of the friction ring by selecting polybutylene terephthalate, a material with specific properties that maintain dimensional stability and fastening allowance over time. This material selection ensures that the friction ring can consistently generate rotational resistance without experiencing significant fastening allowance reduction even under excessive torque conditions.
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 noise and disengagement issues, providing a comfortable lever operation and maintaining rotational resistance, thus enhancing the reliability and durability of the clutch unit.
Implementation Method 1
an elastic member provided between the input-side member and the stationary-side member, for accumulating an elastic force obtained by torque input from the input-side member and for restoring the input-side member to a neutral state with the accumulated elastic force through releasing of the torque input from the input-side member
Implementation Method 2
a friction ring serving as a braking member... Due to a frictional force generated between an inner peripheral surface 122e of the annular recessed portion 22b of the output shaft 22 and the friction ring 129 with the fastening allowance, rotational resistance is imparted to the output shaft 122
Data Source
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AI summary
Provided is a clutch unit, comprising: a lever-side clutch portion for controlling transmission and interruption of rotational torque to an output side through lever operation; and a brake-side clutch portion for transmitting torque input from the lever-side clutch portion to the output side and for interrupting torque reversely input from the output side, wherein: the lever-side clutch portion comprises an outer centering spring (19) provided between a lever-side outer ring to be rotated through the lever operation and a cover (24) restricted in rotation, for accumulating an elastic force obtained by torque input from the lever-side outer ring and for restoring the lever-side outer ring to a neutral state with the accumulated elastic force through releasing of the torque input from the input-side member, the outer centering spring (19) comprising a band plate-like spring member having a C-shape, the cover (24) comprising an inclined portion (24g) which abuts on the outer centering spring (19) and swells to the outer centering spring (19) side; and under a state in which the outer centering spring (19) is assembled, an inner diameter of the outer centering spring (19) is arranged on an outer side of an outermost diameter of the inclined portion (24g) of the cover (24).