Clutch Spring Damping in Power Transmission Cam Mechanisms

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Solution Overview

Problem

Existing power transmission devices for motorcycles require frequent maintenance due to wear of rubber components used for generating sliding resistance, increasing the number of components and leading to issues like impact noise when cam surfaces abut.

Innovation Solution

A power transmission device utilizing a clutch spring to generate rotational resistance by sliding on a restricting member or spring seat, eliminating the need for dedicated rubber components and reducing maintenance, while suppressing impact noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a resistant member made of rubber material is used to generate sliding resistance, then rotational resistance can be generated when the pressure member rotates relative to the clutch member, but the number of components increases and maintenance frequency increases due to wear

Engineering Contradiction:
Improverotational resistance generationVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the resistant member with the existing pressure member by providing a resistant layer on the outer circumferential surface of the pressure member. This integration eliminates the need for a separate resistant member component while maintaining the rotational resistance generation function, thereby reducing the number of components and maintenance requirements

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The pressure member is given multiple functions: it provides axial pressing force through its pressing portion and generates rotational resistance through the resistant layer on its outer circumferential surface. This multi-functionality eliminates the need for dedicated resistant members, reducing component count while maintaining reliability

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If a resistant member made of rubber material is used to generate sliding resistance, then rotational resistance can be generated, but maintenance needs increase due to considerable wear of the rubber material

Engineering Contradiction:
Improverotational resistance generationVSAvoidmaintenance frequency
Core Design Contradiction:
ReliabilityVSEase of repair

Solution Approach 1:

By integrating the resistant layer directly onto the pressure member, the invention eliminates the need for separate resistant members that would require independent maintenance. The resistant layer becomes part of the pressure member structure, simplifying maintenance procedures and reducing maintenance frequency

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The invention changes the material parameter by using a resistant layer with wear-resistant properties on the pressure member surface. This parameter change improves durability and reduces maintenance needs while maintaining the rotational resistance generation function

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If clearance is provided between cam surfaces of the press-contact assisting cam or back-torque limiting cam, then the cams can rotate relative to each other, but impact or hitting noise occurs when the cam surfaces abut on each other

Engineering Contradiction:
Improvecam rotation capabilityVSAvoidimpact noise
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The resistant layer acts as an intermediary element between the cam surfaces. When the cam surfaces abut, the resistant layer provides cushioning and damping, preventing direct metal-to-metal contact and the resulting impact noise, while still allowing the necessary rotation capability

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The resistant layer is pre-applied to the pressure member surface before cam contact occurs. This beforehand cushioning prepares the interface to absorb impact energy and prevent noise-generating direct contact when the cam surfaces abut during operation

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 spring effectively adds rotational resistance and suppresses impact noise without additional dedicated members, enhancing reliability and reducing maintenance needs.

Implementation Method 1

the clutch spring is capable of generating rotational resistance by the one end being allowed to slide on a surface of the restricting member

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3660348B9Power transmission device
Publication Date: 2023.07.05 FCC KK
  • EP3660348B9 patent drawingFigure 1
  • EP3660348B9 patent drawingFigure 2
  • EP3660348B9 patent drawingFigure 3

AI summary

Rotational resistance can be added to the rotation of a pressure member relative to a clutch member by using a clutch spring, and impact or hitting noise accompanied when cam surfaces of a press-contact assisting cam or a back torque limiting cam abut on each other can be suppressed without employing any other dedicated member. The present power transmission device includes a clutch spring 8, which, when a pressure member rotates relative to a clutch member owing to clearance between cam surfaces of a press-contact assisting cam or a back torque limiting cam, can generate rotational resistance by one end 8a sliding on a surface 10a of a restricting member 10 while a side surface is held in the longitudinal direction.