Dual Electric Drive Axles With Offset Planetary Gear Packaging

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Solution Overview

Problem

The use of multiple electrified axles in vehicles presents challenges with manufacturing costs, vehicle handling, and axle structural integrity, particularly due to the need for separate electric motors for each drive wheel, which increases costs and complicates coordinated motor control.

Innovation Solution

A vehicle system with two electric drive axles featuring axially offset planetary gear sets rotationally coupled to electric motor-generators and differentials, allowing for a space-efficient arrangement and the use of similar gear sizes to reduce manufacturing costs, while enabling coordinated motor control for forward and reverse drive modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If separate electric motors are used for each drive wheel, then vehicle propulsion capability is improved, but manufacturing costs significantly increase

Engineering Contradiction:

Improvevehicle propulsion capabilityVSAvoidmanufacturing costs

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent combines multiple drive functions into a single electric motor per axle, using a differential mechanism to distribute power to multiple wheels. This merging approach maintains four-wheel drive capability while reducing the total number of motors required, thereby lowering manufacturing costs.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The electric motor is designed to perform multiple functions: providing propulsion power to all drive wheels through the differential, enabling both forward and reverse motion, and serving as a single control unit for coordinated axle operation. This multi-functionality reduces component count and manufacturing complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Ease of manufacture

If identical electrified axle housings are used in both front and rear, then manufacturing costs are reduced, but vehicle packaging constraints impede implementation

Engineering Contradiction:

Improvemanufacturing costsVSAvoidvehicle packaging

Core Design Contradiction:

Ease of manufactureVSArea of stationary object

Solution Approach 1:

The patent employs asymmetric orientation of the front and rear drive axles, with the front axle oriented in one direction and the rear axle oriented in the opposite direction. This asymmetric arrangement allows identical axle housings to be used while accommodating vehicle packaging constraints and optimizing space utilization.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The rear drive axle is oriented in the opposite direction to the front drive axle, effectively inverting the configuration. This inversion allows the use of identical axle assemblies while adapting to the specific packaging requirements of the vehicle layout.

Inventive Principle:

Principle #13The other way round (Inversion)

3Area of stationary object

If front and rear drive axles are re-oriented to fit packaging constraints, then vehicle packaging is optimized, but motor control coordination becomes more difficult

Engineering Contradiction:

Improvevehicle packagingVSAvoidmotor control coordination

Core Design Contradiction:

Area of stationary objectVSDevice complexity

Solution Approach 1:

The control system incorporates feedback mechanisms that monitor the rotational state and operational status of both front and rear electric motors. This feedback enables the controller to dynamically adjust motor commands, maintaining coordinated control despite the asymmetric orientation and packaging constraints.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The electric motors are controlled to provide universal functionality across different orientations, handling both forward and reverse drive modes through coordinated operation. The control system manages the complexity by treating the asymmetrically oriented axles as interchangeable units with standardized control protocols.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Volume of moving object

If planetary gear sets are positioned axially offset from motor-generators, then space efficiency is improved and susceptibility to road debris damage is reduced, but structural integrity requirements increase

Engineering Contradiction:

Improvespace efficiencyVSAvoidaxle structural integrity

Core Design Contradiction:

Volume of moving objectVSStrength

Solution Approach 1:

The patent positions the planetary gear sets in an axial offset arrangement relative to the motor-generators, transitioning from a coaxial to a spatial distribution. This dimensional repositioning improves space efficiency and protects components from road debris while the integrated axle housing maintains structural integrity through unified construction.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The axle housing is designed as an integrated structure that combines the motor mounting, gear set housing, and differential enclosure into a single unified component. This merging provides structural reinforcement that compensates for the offset positioning, maintaining axle strength while enabling the space-efficient layout.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11833898B2Vehicle system with multiple electric drive axles

Publication Date: 2023.12.05 DANA AUTOMOTIVE SYST GRP LLC

AI summary

Methods and systems are provided for a vehicle system. In one example, the vehicle system includes a first electric drive axle assembly and a second electric drive axle assembly. Each of the first and second axle assemblies has a gear train with a planetary gear set axially offset from a motor-generator and each planetary gear set is rotationally coupled to a differential.