Electric Drive Train Torque Vectoring via Clutch Segmentation

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Solution Overview

Problem

Existing drive trains for electrically drivable motor vehicles, particularly those with four-wheel drive, face inefficiencies in energy consumption and driving dynamics, especially in critical situations requiring stabilizing interventions.

Innovation Solution

A drive train configuration with two electric machines, two gearings, and three switchable clutches allows for either differential-driven or individual wheel drive modes, enabling torque vectoring without energy loss, by controlling the engagement of clutches and electric machines to optimize energy use and driving dynamics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a single electric machine drives both axle sections via a differential, then energy consumption is reduced, but individual wheel control and torque vectoring capability are lost

Engineering Contradiction:

Improveenergy consumptionVSAvoidindividual wheel control capability

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The drive train is segmented into two independent drive paths: one electric machine with gearing can drive both axle sections through the differential (energy-efficient mode), while the other electric machine can independently drive individual axle sections (control mode). The three clutches enable selective engagement of these paths, allowing the system to switch between energy conservation and individual wheel control based on driving conditions.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different operating modes using three switchable clutches. The first clutch connects/disconnects the first electric machine from the differential, while the second and third clutches connect/disconnect the second electric machine to individual axle sections. This dynamic reconfiguration allows optimal performance adaptation between energy efficiency and driving dynamics control.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If torque vectoring is achieved through differential braking, then individual wheel control is possible, but energy loss occurs due to braking engagement

Engineering Contradiction:

Improvetorque vectoring capabilityVSAvoidenergy loss through braking

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical braking-based torque vectoring system with an electrically-driven torque vectoring system. The second electric machine, connected to axle sections via the second and third clutches, can independently apply torque to individual wheels without requiring braking engagement. This electrical torque application achieves the same torque vectoring effect while eliminating the energy losses associated with friction braking.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If two electric machines with full independent control are used, then driving dynamics and individual wheel control are optimized, but device complexity increases

Engineering Contradiction:

Improvedriving dynamics controlVSAvoidnumber of clutches and control systems

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The first electric machine serves multiple functions: it can drive both axle sections through the differential for energy-efficient normal driving, and can be selectively disconnected when individual wheel control is needed. The second electric machine provides supplemental torque and enables torque vectoring when engaged with specific axle sections. The three clutches are multi-functional, enabling various drive configurations including normal drive, individual wheel drive, and torque vectoring modes, thereby managing complexity through versatile component design.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9221334B2Drive train of a solely electrically driven motor vehicle having two electric motors

Publication Date: 2015.12.29 DR ING H C F PORSCHE AG

AI summary

A drive train (1) of a solely electrically driven motor has an axle (2) with first and second axle sections (4, 5) connected to different outputs of a differential (35). The drive train also has a first and second electric motors (13, 14) that co-operate with first and second transmissions (15) respectively to drive the axle (2). A first clutch can connect the first transmission (15) to an entry wheel (34) of the differential (35) for driving the two axle sections (4, 5) of the axle (2). A second clutch (37) can connect the first transmission (15) to the first axle section (4) while the first clutch (36) is open and a third clutch (38) can connect the second transmission (16) to a second axle section (5) while the first clutch (36) is open.