Vehicle Deceleration Control Using Regenerative and Friction Braking

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Solution Overview

Problem

Existing motor vehicle systems face challenges in providing sufficient deceleration torque, especially at low relative speeds, leading to wear on friction braking systems and discomfort due to deceleration jerks.

Innovation Solution

The method involves activating the friction braking system and operating the electric drive machine as a generator to generate deceleration torque, with the system adapting torque based on relative speed using predefined threshold values and characteristic curves to ensure comfortable and efficient deceleration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the friction braking system is activated to generate deceleration torque at low relative speeds, then sufficient deceleration torque is provided, but wear on the friction braking system increases

Engineering Contradiction:

Improvedeceleration torqueVSAvoidwear on friction braking system

Core Design Contradiction:

ForceVSLoss of substance

Solution Approach 1:

The patent converts the harmful effect of friction braking (wear) into a beneficial energy recovery process by operating the electric drive machine as a generator during deceleration. The kinetic energy that would otherwise be lost as heat and wear is instead converted into electrical energy stored in the energy storage device, eliminating wear while providing deceleration torque.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent replaces the mechanical friction braking system with an electromagnetic braking system (electric drive machine operating as generator). This substitution eliminates direct contact friction and wear while maintaining the ability to generate deceleration torque through electromagnetic forces.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of energy

If the electric drive machine operates as a generator to generate deceleration torque, then braking energy is recovered and friction braking system wear is reduced, but sufficient deceleration torque cannot be ensured at low relative speeds

Engineering Contradiction:

Improvebraking energy recoveryVSAvoiddeceleration torque at low speeds

Core Design Contradiction:

Loss of energyVSForce

Solution Approach 1:

The patent segments the deceleration torque generation into two distinct phases: a first deceleration phase using the electric drive machine as generator for energy recovery, and a second deceleration phase using the friction braking system for final stopping. This segmentation allows each system to operate in its optimal performance range.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent dynamically switches between different braking mechanisms based on the current operating conditions (speed, torque requirements). The control system adjusts the proportion of generator braking versus friction braking in real-time, optimizing both energy recovery and deceleration performance across the entire speed range.

Inventive Principle:

Principle #15Dynamics

3Reliability

If deceleration torque is applied at low relative speeds, then vehicle control is maintained, but deceleration jerks cause driver discomfort

Engineering Contradiction:

Improvevehicle controlVSAvoiddriver comfort

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent applies beforehand cushioning by using the friction braking system to provide a gradual, controlled deceleration in the low-speed phase, cushioning the transition to complete stop. This prevents sudden jerks and maintains comfort while ensuring vehicle control is maintained throughout the deceleration process.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

This approach allows for efficient deceleration and reduced wear on the friction braking system by recovering braking energy, providing adaptable and comfortable deceleration processes, and maintaining vehicle control at low speeds.

Implementation Method 1

the electric drive machine of the drive system is operated as a generator to generate the deceleration torque

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the friction braking system is activated to generate the deceleration torque

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS20250010855A1Method for operating a motor vehicle, control unit, motor vehicle

Publication Date: 2025.01.09 ROBERT BOSCH GMBH

AI summary

A method for operating a motor vehicle, which includes a drive system, including an electric drive machine, a friction braking system and an actuating element. The actuating element is continuously movable between a first end state and a second end state, a position of the actuating element in the first end state corresponding to a percentage value of 0%, and the position of the actuating element in the second end state corresponding to a percentage value of 100%. An acceleration torque for the motor vehicle is predefined if the positon has a percentage value that is greater than a predefined threshold value, and a deceleration torque for the motor vehicle being predefined if the position has a percentage value that is less than the threshold value. The friction braking system is activated in such a way that the friction braking system generates at least partially the predefined deceleration torque.