Rear Drive Unit Motor Mounting for Hybrid Vehicles

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Solution Overview

Problem

Current Kinetic Energy Recovery Systems (KERS) in hybrid electric motor vehicles face challenges in reducing costs, fuel consumption, and environmental impact, while also requiring improved packaging efficiency and power delivery.

Innovation Solution

A mechanical all-wheel drive system is implemented, where the electrical motor/generator is coupled to an input shaft connected to a planetary gear set, with a spur gear unit and disconnect clutch, allowing for efficient power transmission and regenerative braking, and enabling easier installation and space optimization around the rear drive unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the motor/generator assembly is positioned above the rear final drive unit with the end casing extending through the sub frame aperture, then packaging space is optimized and conflicting requirements from suspension, exhaust, and fuel systems are resolved, but installation and replacement of the motor/generator becomes complex requiring disassembly of major parts

Engineering Contradiction:
Improvepackaging space utilizationVSAvoidinstallation and replacement of motor/generator
Core Design Contradiction:
Volume of moving objectVSEase of repair

Solution Approach 1:

The rear drive unit is divided into separable modules: the motor/generator assembly can be detached from the rear final drive unit as independent components. The connection interface includes a motor/generator support structure that can be disconnected without disassembling major structural parts of the rear drive unit, enabling easier installation and replacement while maintaining the compact integrated positioning.

Inventive Principle:
Principle #1Segmentation

2Loss of energy

If Kinetic Energy Recovery Systems are implemented in hybrid electric motor vehicles, then fuel consumption and environmental impact are reduced, but costs and system complexity increase

Engineering Contradiction:
Improvefuel consumptionVSAvoidsystem complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The motor/generator assembly is merged with the rear final drive unit to form an integrated power transmission system. The motor/generator is positioned above the rear final drive unit with direct mechanical coupling through the end casing and sub frame aperture, combining the energy recovery function with the existing drive mechanism to reduce overall system complexity while maintaining fuel efficiency benefits.

Inventive Principle:
Principle #5Merging (Combining)

3Power

If the motor/generator assembly is integrated with the rear final drive unit, then power and torque delivery is enhanced, but installation complexity and space constraints increase

Engineering Contradiction:
Improvepower and torque deliveryVSAvoidinstallation ease
Core Design Contradiction:
PowerVSEase of operation

Solution Approach 1:

A motor/generator support structure serves as an intermediary component between the motor/generator assembly and the rear final drive unit. This support structure includes a motor/generator mounting structure that facilitates easier installation and removal of the motor/generator while maintaining the integrated configuration for enhanced power and torque delivery.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

This solution simplifies the installation and replacement of the motor/generator, enhances power and torque delivery, and allows for efficient use of vehicle space, while enabling regenerative braking without radical changes to the rear drive unit or additional testing.

Implementation Method 1

a first planetary gear set (40) working as a first gear/transmission ratio in the RDU (10)

Methodology Applied
Scientific EffectGear meshing: Gear

Implementation Method 2

a spur gear unit (50) working as a second gear/transmission ratio in the RDU (10)

Methodology Applied
Scientific EffectSpur gear transmission: Gear

Data Source

PatentEP2851227B1A rear drive unit for a hybrid electric motor vehicle
Publication Date: 2017.05.17 VOLVO CAR CORP
  • EP2851227B1 patent drawingFigure 1
  • EP2851227B1 patent drawingFigure 2
  • EP2851227B1 patent drawingFigure 3

AI summary

A rear drive unit (10) for a hybrid electric motor vehicle (1), the rear drive unit (10) comprising a rear link/drive shaft (20) and an electrical motor/generator (30).