Motorcycle Reverse Drive Transmission With Safe Bushing Engagement

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Motor vehicles, particularly motorcycles, lack an efficient reverse drive system, making it difficult to maneuver them, especially when heavy or on uneven terrain, as existing solutions are costly, complex, or unsafe.

Innovation Solution

A transmission unit with a reverse drive electric motor, a control bushing, and a driven transmission bushing connected via an actuator, allowing for controlled engagement and disengagement of reverse drive, utilizing a gear train and safety system to prevent reverse drive activation during forward motion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a gear box similar to automotive industry is used for reverse drive, then reverse drive capability is achieved, but device complexity and cost increase

Engineering Contradiction:
Improvereverse drive capabilityVSAvoidgear transmission complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent replaces the traditional mechanical gear box system with an electric motor system. The reverse drive electric motor (21) directly drives the control bushing (47) through an auxiliary drive (22), eliminating the need for complex gear transmissions while achieving reverse drive capability. This substitution of mechanical system with electromechanical system resolves the contradiction between reverse drive capability and device complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The shaft (23) of the driving wheel serves multiple functions: it transmits motion from the main drive for forward movement and also serves as the driven element for reverse drive when coupled with the driven transmission bushing (63). This multi-functionality allows the same mechanical component to serve both forward and reverse operations, reducing overall system complexity.

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

2Ease of operation

If an auxiliary electric motor with reduction gear and flexible shaft is used, then reverse drive is enabled, but device complexity and bulk increase

Engineering Contradiction:
Improvereverse drive capabilityVSAvoidsystem complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The patent extracts and eliminates the flexible shaft and intrinsically unsafe cardan shaft from the system. Instead, the reverse drive electric motor (21) is directly mounted on the case (17) and connected to the control bushing (47) through a rigid auxiliary drive (22), simplifying the mechanical connection and reducing system complexity while maintaining reverse drive capability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The reverse drive electric motor (21) and the auxiliary drive (22) are integrated directly into the transmission case (17), merging multiple components into a compact assembly. The control bushing (47) and driven transmission bushing (63) are coaxially arranged and integrated with the shaft (23), reducing the overall system bulk while enabling reverse drive.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If centrifugal masses are added for safety system, then reverse drive activation during forward motion is prevented, but device complexity increases

Engineering Contradiction:
Improvesafety against accidental reverse driveVSAvoidsafety system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The safety system uses centrifugal masses (84) that automatically respond to the rotational speed of the shaft (23). When the shaft rotates in forward direction above a threshold speed, the centrifugal masses move outward due to centrifugal force and mechanically block the engagement between control bushing (47) and driven transmission bushing (63). This self-acting mechanism prevents accidental reverse drive activation during forward motion without requiring external sensors or control systems, achieving reliability while minimizing added complexity.

Inventive Principle:
Principle #25Self-service

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 safe and efficient reverse drive operation without the need for complex gear transmissions, reducing costs and improving maneuverability on various terrains.

Implementation Method 1

The actuation element can comprise an anchor, movable by effect of the electromagnetic force generated by the magnet

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

The safety system comprises at least one centrifugal mass, and preferably a pair of centrifugal masses, rotating with the shaft of the driving wheel and movable radially with respect thereto, as a result of the centrifugal force

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3874181B1Transmission unit for motor vehicles with reverse drive and motor vehicle comprising the transmission unit
Publication Date: 2024.02.21 PIAGGIO & C SPA
  • EP3874181B1 patent drawingFigure 1
  • EP3874181B1 patent drawingFigure 2
  • EP3874181B1 patent drawingFigure 3

AI summary

The transmission unit (15) for motor vehicle (1) comprises a shaft (23) of the driving wheel, operatively connected to a main drive (19, 97) to control forward drive, and a reverse drive electric motor (21). The transmission unit further comprises a control bushing (47) rotated by the reverse drive electric motor (21), and a driven transmission bushing (63), operatively connected to the shaft (23) of the driving wheel. An actuator (121) is provided for controlling mutual coupling between the control bushing (47) and the driven transmission bushing (63) to transmit the motion of the reverse drive electric motor (21) to the shaft (23) of the driving wheel.