Hybrid Vehicle Torque Control for Cornering Consistency

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Solution Overview

Problem

Existing vehicle operation methods, particularly in hybrid vehicles, fail to maintain a consistent target torque during cornering, leading to undesirable changes in vehicle acceleration due to differing torque effects on steered and unsteered axles, which can be unpleasant for the driver.

Innovation Solution

The method involves correcting the partial drive torque of the steered and non-steered axles based on the distance between the wheels and the vehicle's center of rotation or steering angle, ensuring that the target torque is maintained by redistributing torque between the axles, using a control unit to adjust wheel torques accordingly, and employing a combination of drive units like internal combustion engines and electric motors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If high torques are applied to both steered and non-steered axles during cornering, then the vehicle acceleration changes undesirably due to different lever ratios, but reducing torque on one axle compromises the target torque implementation

Engineering Contradiction:
Improvetarget torque implementationVSAvoidvehicle acceleration consistency
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The control unit dynamically adjusts the distribution of target torque between steered and non-steered axles based on steering angle and lever ratio parameters. By changing the torque distribution parameters in real-time according to cornering conditions, the system maintains consistent vehicle acceleration while implementing the driver's requested target torque.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The system uses feedback from steering angle sensors and torque measurements to continuously monitor the actual vehicle acceleration during cornering. The control unit compares the actual acceleration with the desired acceleration and adjusts the torque distribution between axles to eliminate deviations, ensuring the target torque is implemented correctly.

Inventive Principle:
Principle #23Feedback

2Reliability

If the target torque is freely redistributed between steered and non-steered axles, then the compensation for cornering effects is optimized, but the system complexity increases

Engineering Contradiction:
Improvecornering compensation accuracyVSAvoidtorque distribution control
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The control unit performs multiple functions: it manages torque distribution between axles, calculates lever ratios based on steering angle, compensates for cornering effects, and coordinates both steered and non-steered drive units. By consolidating these functions in a single control system, the patent achieves optimized cornering compensation without proportionally increasing system complexity.

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

3Reliability

If partial drive torque is corrected as a function of distance from center of rotation, then the differentiated acceleration behavior is compensated, but the computational requirements increase

Engineering Contradiction:
Improveacceleration behavior compensationVSAvoidcomputing power requirements
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The control unit pre-calculates lever ratios and torque distribution factors based on steering angle before cornering occurs or at the onset of cornering. By preparing compensation parameters in advance rather than calculating them in real-time during dynamic cornering, the system reduces computational power requirements while maintaining accurate acceleration behavior compensation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2421734B1Method and device for operating a vehicle, in particular a hybrid vehicle
Publication Date: 2013.04.17 ROBERT BOSCH GMBH
  • EP2421734B1 patent drawingFigure 1
  • EP2421734B1 patent drawingFigure 2~3

AI summary

The invention relates to a method for operating a vehicle, in particular a hybrid vehicle, wherein at least one of the axes (7, 13) of the vehicle is driven by a power plant (5, 11), whereby the vehicle is accelerated by a predefined theoretical torque, by transferring a partial driving torque to at least one axis (7, 13) and the wheels (8, 9, 14, 15) coupled to it. In order to transfer the theoretical torque desired by a driver also into the corresponding acceleration of the vehicle, the partial driving torque of the steered (7) and/or non-steered axis (13) is corrected such that the vehicle is accelerated by the predefined theoretical torque.