Hybrid Axle Torque Distribution for Stable Driver-Demand Matching

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Solution Overview

Problem

Existing methods for distributing torque between the front and rear axles of hybrid vehicles often result in torque applied being greater than the driver's demand, leading to potential accidental damage and instability.

Innovation Solution

A method involving successive iterations to calculate and limit torque for each axle, ensuring the sum of torques applied corresponds to the driver's request, with minimum and maximum torque values defined as functions of the overall torque, ensuring stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If torque is limited on the rear axle to ensure vehicle stability, then vehicle stability is improved, but the overall torque applied may exceed driver demand causing untimely acceleration

Engineering Contradiction:

Improvevehicle stabilityVSAvoidoverall torque applied

Core Design Contradiction:

Stability of the object's compositionVSPower

Solution Approach 1:

The control system continuously monitors the torques applied to front and rear axles and adjusts the torque distribution in real-time. The feedback loop ensures that the sum of torques matches the driver's demand while maintaining stability constraints on each axle individually.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The torque distribution system dynamically adjusts the torque limits and allocation between axles based on current vehicle conditions and driver demand. The minimum and maximum torque values are defined as functions of overall torque, allowing adaptive response to changing operating conditions.

Inventive Principle:

Principle #15Dynamics

2Ease of operation

If torque distribution is controlled independently on front and rear axles, then ease of control is improved, but device complexity increases due to multiple control branches

Engineering Contradiction:

Improvetorque controlVSAvoidcontrol system structure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The control system is divided into separate control branches for front and rear axles, each with its own torque calculation and limitation logic. This segmentation allows independent optimization of each axle's torque distribution while maintaining overall system coordination through the iterative calculation process.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP3268255B1Method for distributing torque between the wheelsets of a motor vehicle

Publication Date: 2023.10.25 STELLANTIS AUTO SAS

Figure 1
Figure 2~3

AI summary

In this method for distributing a reference overall torque (Cglobal) between the wheelsets of a vehicle, a first branch (20) comprises a step involving subtracting (22) an optimal torque (Car_opti) from the reference overall torque (Cglobal) so as to obtain a first reference torque (Cav) to be applied to a first wheelset and a second branch (30) comprises steps consisting in subtracting (31) an estimated torque (Cav_estim) associated with the first wheelset from the reference overall torque (Cglobal) so as to obtain a second reference torque (Car) to be applied to a second wheelset, then in limiting (32) the second reference torque (Car) between a minimum torque and a maximum torque both of which are predefined. The first branch (20) further comprises a step consisting in limiting (21) the optimal torque (Car_opti) between the minimum torque and the maximum torque before calculating the first torque (Cav).