Electric Vehicle Powertrain Layout With Forward Motor and Swing Arm

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Solution Overview

Problem

Existing vehicle designs limit the freedom in the layout of drive motors by swing arms and require complex configurations for transmitting power to rear wheels, restricting space utilization and assembly/maintenance efficiency.

Innovation Solution

A vehicle design utilizing an endless power transmission member to connect the drive motor with rear wheels, positioning the motor forward of the swing arms, allowing for increased layout freedom and efficient space utilization, with a motor fixing bracket for easy assembly and improved rigidity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the drive motor is positioned behind the swing arm to directly drive the rear wheel, then the power transmission structure is simple, but the layout freedom of the drive motor is limited and space utilization is reduced

Engineering Contradiction:
Improvelayout freedom of drive motorVSAvoidpower transmission structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

An endless power transmission member (chain) is introduced as an intermediary between the drive motor and rear wheel. This allows the drive motor to be positioned forward of the swing arm while still transmitting power to the rear wheel, resolving the contradiction between layout freedom and direct drive simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Area of stationary object

If the drive motor is positioned forward of the swing arm with endless power transmission, then layout freedom is improved, but the power transmission structure becomes more complex

Engineering Contradiction:
Improvespace utilizationVSAvoidpower transmission structure
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The power transmission system utilizes the lateral dimension by routing the endless power transmission member through the swing arm area laterally, allowing the drive motor to be positioned forward while efficiently utilizing available space without excessive complexity.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of operation

If the drive motor is directly connected to the rear wheel, then the power transmission path is short, but the motor position is constrained by the swing arm location

Engineering Contradiction:
Improveassembly and maintenanceVSAvoidmotor position flexibility
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The endless power transmission member serves as a mediator that decouples the drive motor from direct connection to the rear wheel, enabling the motor to be positioned forward of the swing arm while maintaining functional connection through the power transmission chain.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Stability of the object's composition

If the drive motor is positioned forward of the swing arm, then mass can be concentrated around the center of gravity, but the power transmission requires an endless transmission member

Engineering Contradiction:
Improvevehicle stabilityVSAvoidpower transmission system
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The endless power transmission member acts as a flexible intermediary that allows the drive motor to be positioned forward of the swing arm near the vehicle's center of gravity, improving stability while accepting the added complexity of the chain transmission system.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP4201720B1vehicle
Publication Date: 2026.03.04 YAMAHA MOTOR CO LTD
  • EP4201720B1 patent drawingFigure 1
  • EP4201720B1 patent drawingFigure 2
  • EP4201720B1 patent drawingFigure 3

AI summary

A vehicle includes upper frames, lower frames, a front frame, a rear frame, a pair of rear wheels, a drive motor to drive the pair of rear wheels, a battery to supply electric power to the drive motor, an endless power transmission to connect the drive motor with the pair of rear wheels, a pivot shaft attached to the rear frame, a swing arm supported pivotably by the pivot shaft and supporting the pair of rear wheels, a straddled seat at a higher position than the drive motor, and a bar handle provided at a higher position than the straddled seat. The drive motor is located farther forward than the swing arm.