Dual Shaft Motor Torque Vectoring and Cooling

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Solution Overview

Problem

Existing motor vehicle drive units for electric vehicles face challenges in efficiently distributing torque between driven wheels, requiring differential transmissions and multi-speed reductions, which increase weight and cost, and are limited by motor rotor mechanical speed limits, affecting performance and usability.

Innovation Solution

A motor vehicle drive unit with an electric motor featuring a rotor and a counter-rotating main stator, an auxiliary stator for torque vectoring, and cooling fins within an air duct cover with an auxiliary fan, along with chain drive and gear drive reductions, enabling improved torque distribution and cooling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a differential transmission and multi-speed reduction gear are used to distribute torque between driven wheels, then torque distribution capability is improved, but vehicle weight and device complexity increase

Engineering Contradiction:
Improvetorque distribution capabilityVSAvoidvehicle weight
Core Design Contradiction:
Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent combines the functions of differential transmission and multi-speed reduction gear into a single integrated transmission system. The planetary gear mechanism serves both as a differential for torque distribution and as a reduction gear, eliminating the need for separate components and thereby reducing overall vehicle weight while maintaining torque distribution capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The planetary gear mechanism is designed to perform multiple functions simultaneously: it acts as a differential transmission for torque distribution between wheels, provides multi-speed reduction gearing, and enables torque vectoring. This multi-functionality reduces the number of separate components needed, thereby reducing vehicle weight and complexity.

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

2Productivity

If a multi-speed transmission is used to overcome motor speed limits, then performance and usability are improved, but cost and weight increase

Engineering Contradiction:
Improveperformance and usabilityVSAvoidtransmission weight
Core Design Contradiction:
ProductivityVSWeight of moving object

Solution Approach 1:

The patent merges the multi-speed transmission functionality into the planetary gear mechanism that also serves as a differential. By integrating multiple speed reduction stages within the differential structure, the system achieves multi-speed capability without requiring separate transmission components, thereby reducing overall weight and cost.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The planetary gear mechanism employs nested gear arrangements where multiple gear sets are contained within each other. This nesting allows multiple speed reduction stages to be compactly arranged within a single transmission housing, reducing the overall size and weight of the transmission system while providing multi-speed capability.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Ease of operation

If an auxiliary stator is added for torque vectoring, then vehicle control and steering capability are improved, but device complexity increases

Engineering Contradiction:
Improvevehicle control capabilityVSAvoidmotor structure complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The auxiliary stator is integrated into the existing motor structure to provide torque vectoring functionality. By making the stator capable of both generating primary torque and providing differential torque for steering control, the system achieves enhanced vehicle control capability without requiring completely separate control mechanisms, thereby limiting the increase in device complexity.

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

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 solution enhances torque vectoring for better vehicle control and steering, reduces wheel spin, and improves cooling efficiency, while minimizing weight and complexity, thereby enhancing performance and usability without increasing costs.

Implementation Method 1

cooling fins arranged at the periphery of the main rotatably mounted stator... enables improved cooling of the electric motor as the main rotatably mounted stator rotates through ambient air

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

cooling fins arranged at the periphery of the main rotatably mounted stator... enables improved cooling of the electric motor

Methodology Applied
Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

an auxiliary fan unit is provided for producing a flow of cooling air passing over the cooling fins within the air duct cover

Methodology Applied
Scientific EffectForced convection: Forced Convection

Implementation Method 4

an electric motor having a rotor and a main stator rotatably mounted to a support structure

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2578438B1Dual shaft motor
Publication Date: 2017.04.26 VOLVO CAR CORP
  • EP2578438B1 patent drawingFigure 1
  • EP2578438B1 patent drawingFigure 2

AI summary

Embodiments herein relate to a motor vehicle drive unit (1) and an automotive vehicle (17) comprising such a motor vehicle drive unit (1). An electric motor has a rotor (2) and a main stator (3) rotatably mounted to a support structure (4). A first transmission (5) provides an output to a first wheel axle shaft (6) from the rotor (2). A second transmission (7) provides an output to a second wheel axle shaft (8) from the main stator (3). An auxiliary stator (9) at least partially surrounds the main stator (3) and is held stationary relative to the main rotatably mounted stator (3). Means (10) are provided for controlling the auxiliary stator (9) to add or subtract power to the main rotatably mounted stator (3).