Motorcycle Synchronized Transmission for Engine Brake Retention

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Solution Overview

Problem

Synchronized transmissions in vehicles often lose engine brake effect at high speeds, making vehicle control difficult due to the disengagement of pulleys on the driven shaft, which can lead to reduced control and safety issues.

Innovation Solution

A synchronized transmission system with axial actuation synchronizers that manage the engagement and disengagement of toothed wheels and belts to maintain engine brake effect across varying speeds, ensuring consistent power transmission and control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If pulleys on the driven shaft are disengaged to allow free rotation, then the transmission can switch between different speed ratios, but the engine brake effect is lost during descending or high-speed conditions

Engineering Contradiction:
Improvespeed ratio variationVSAvoidvehicle control
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The transmission system dynamically switches between two operational modes: a first configuration where pulleys are disengaged for free rotation enabling speed ratio variation, and a second configuration where pulleys are engaged to maintain engine brake effect. This dynamic reconfiguration allows the system to adapt to different driving conditions while maintaining both adaptability and reliability as needed.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the engagement parameter of the pulleys on the driven shaft between two states: disengaged (allowing free rotation and speed variation) and engaged (maintaining connection for engine brake effect). This parameter change enables the transmission to resolve the contradiction between adaptability and reliability by selecting the appropriate state based on driving conditions.

Inventive Principle:
Principle #35Parameter changes

2Ease of operation

If a one-way clutch is used to allow free wheel rotation, then speed changes can be implemented, but reversibility cannot be excluded which compromises control

Engineering Contradiction:
Improvespeed changeVSAvoidvehicle control
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The invention extracts the one-way clutch mechanism from the transmission system and replaces it with a different configuration that achieves speed change functionality without the reversibility problem. By removing the problematic component and substituting it with an alternative mechanism, the system maintains ease of operation while eliminating the control compromise.

Inventive Principle:
Principle #2Taking out (Extraction)

3Speed

If pulleys are disengaged from the driven shaft, then high-speed operation is enabled, but engine brake effect is removed

Engineering Contradiction:
Improvehigh-speed operationVSAvoidengine brake effect
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The system dynamically adjusts the engagement state of pulleys based on operating conditions. At high speeds, the pulleys can be disengaged to enable free rotation and speed variation, while a second set of pulleys or the same pulleys in a different configuration remain engaged to maintain engine brake effect when needed, resolving the contradiction between speed capability and brake effectiveness.

Inventive Principle:
Principle #15Dynamics

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 system allows for improved vehicle control and maintains the engine brake effect even at high speeds by actively managing the synchronization of toothed wheels and belts, enhancing safety and control during descending or high-speed conditions.

Implementation Method 1

at least one belt therebetween

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3548376B1Synchronized transmission, in particular for motorcycles
Publication Date: 2022.11.09 PIAGGIO & C SPA
  • EP3548376B1 patent drawingFigure 1~2
  • EP3548376B1 patent drawingFigure 3
  • EP3548376B1 patent drawingFigure 4

AI summary

A synchronized transmission (200), which can be 5 used aboard a vehicle and in particular a motorcycle, wherein the craknkshaft (202) actuated by the engine (106) and the driven shaft, connected to a rear wheel (105), are substantially parallel therebetween, the driven shaft (205) receiving the 10 motion from a primary shaft (53) kinematically connected to the craknkshaft (202), wherein the primary shaft (53) has at least one toothed wheel (61), which transmits the motion to said driven shaft (205), arranged on a driven bushing (76) 15 assembled on the primary shaft (53), the primary shaft (53) comprising a passing-through axial channel (45) wherein an actuation stem (70) is inserted, comprising a clutch (74), acting on said driven bushing (76) and actuated axially through 20 said stem (70), which makes said driven bushing (76) integral to the motion transmission so as to exclude the reversibility of the free wheel (62) itself.