Clutch Back-Torque Cam Layout for Stable Engine Braking

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Solution Overview

Problem

Existing power transmission devices for two-wheeled vehicles risk damaging components due to load during power transmission, particularly when using a cam mechanism for engine braking, as the pin may be subjected to stress when the weight member moves to a radially outer position.

Innovation Solution

A power transmission device with a back torque transmission cam that brings driving clutch plates and driven clutch plates into press contact without relying on the pin, using a torque transmission portion on the clutch members to transmit rotational force directly, and a movement amount restriction portion to control the second clutch member's movement, allowing stable power transmission and engine braking without overloading the pin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the cam mechanism (long hole and pin) is used to bring clutch plates into press contact for engine braking, then engine brake can be applied, but the pin may be damaged by load during power transmission

Engineering Contradiction:
Improveengine braking capabilityVSAvoidpin durability
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The clutch mechanism is divided into two independent systems: a cam mechanism for engine braking and a torque transmission portion for power transmission. This segmentation allows each component to be optimized for its specific function, preventing the pin from bearing transmission loads.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The function of transmitting rotational force during power transmission is extracted from the cam mechanism and assigned to a dedicated torque transmission portion. This removes the harmful load from the pin while preserving the cam mechanism's engine braking function.

Inventive Principle:
Principle #2Taking out (Extraction)

2Productivity

If the weight member is moved to radially outer position and pressure member to actuation position, then power transmission is enabled, but the pin may be overloaded during this transition

Engineering Contradiction:
Improvepower transmission efficiencyVSAvoidcomponent durability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The torque transmission portion acts as an intermediary mechanism that handles the load during the transition when the weight member moves to the radially outer position. This mediator protects the pin from overload while enabling efficient power transmission.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If the cam mechanism is used for both engine braking and power transmission, then device complexity is reduced, but component damage risk increases

Engineering Contradiction:
Improvemechanism simplicityVSAvoidcomponent durability
Core Design Contradiction:
Device complexityVSStrength

Solution Approach 1:

The clutch mechanism achieves multi-functionality through specialized components: the cam mechanism handles engine braking while the torque transmission portion handles power transmission. This functional specialization prevents component damage while maintaining reasonable system complexity.

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

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

Enables stable power transmission and engine braking by ensuring the driving clutch plates and driven clutch plates are in press contact when the pressure member is at a non-actuation position, reducing the risk of component damage and maintaining reliable operation even when the weight member is at a radially outer position.

Implementation Method 1

a weight member (8) being movable from a radially inner position to a radially outer position by a centrifugal force due to rotation of the clutch housing

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP4160038B1Power transmission device
Publication Date: 2025.03.26 FCC KK
  • EP4160038B1 patent drawingFigure 1
  • EP4160038B1 patent drawingFigure 2
  • EP4160038B1 patent drawingFigure 3

AI summary

There is provided a power transmission device that can apply engine brake by transmitting a rotational force on the side of a wheel to the side of an engine by bringing driving clutch plates and driven clutch plates into press contact with each other when a pressure member is located at a non-actuation position, and that allows power transmission to be performed stably when a weight member is moved to a radially outer position and the pressure member is moved to an actuation position. The power transmission device includes a clutch member, comprising a first clutch member (4a), a second clutch member (4b), a back torque transmission cam that can bring the driving clutch plates (6) and the driven clutch plates (7) into press contact with each other by moving the second clutch member (4b) when a rotational force is input to the first clutch member (4a) via an output shaft (3) when the pressure member (5) is located at the non-actuation position, and a torque transmission portion that can transmit a rotational force transmitted to the second clutch member (4b) to the first clutch member (4a) not via the back torque transmission cam.