Working Machine Drive Train Braking Control

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Solution Overview

Problem

Existing drive trains for working machines, particularly electric drive trains, struggle to provide sufficient braking torque or recuperation torque when descending a slope at high speeds, leading to impermissible acceleration.

Innovation Solution

A method for operating a drive train of a working machine that includes a drive motor, a service brake, and an assisting brake. The drive motor is coupled to at least one wheel, and the assisting brake is automatically actuated if impermissible acceleration occurs, with the actuation adjusted based on the required braking torque and thermal load on the brake.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the drive motor operates in recuperation mode to provide braking torque, then energy is recovered and braking effect is provided, but insufficient braking torque is generated when descending steep slopes at high speeds

Engineering Contradiction:

Improveenergy recoveryVSAvoidbraking torque

Core Design Contradiction:

Use of energy by moving objectVSForce

Solution Approach 1:

The patent combines the drive motor's braking torque with the assisting brake's mechanical braking force to achieve sufficient total braking effect when descending steep slopes at high speeds, while still utilizing recuperation mode for energy recovery when conditions permit

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The control system dynamically switches between recuperation mode, mechanical braking mode, and combined braking mode based on real-time operating conditions including slope gradient, speed, and thermal load, optimizing both energy recovery and braking performance

Inventive Principle:

Principle #15Dynamics

2Reliability

If the assisting brake is continuously actuated to prevent impermissible acceleration, then braking effect is ensured, but thermal load on the brake increases leading to potential damage

Engineering Contradiction:

Improvebraking reliabilityVSAvoidthermal load on brake

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

The control system continuously monitors thermal load on the assisting brake and adjusts braking strategy accordingly, reducing or eliminating assisting brake actuation when thermal load exceeds safe thresholds while maintaining braking reliability through alternative strategies

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The control system applies assisting brake in periodic intervals rather than continuous operation, allowing thermal dissipation between braking events while still achieving the required braking effect to prevent impermissible acceleration

Inventive Principle:

Principle #19Periodic action

3Device complexity

If the drive train uses only electric braking components, then system complexity is reduced, but sufficient braking torque cannot be provided on steep slopes at high speeds

Engineering Contradiction:

Improvebraking system complexityVSAvoidbraking torque

Core Design Contradiction:

Device complexityVSForce

Solution Approach 1:

The assisting brake serves multiple functions: providing additional braking torque when needed, serving as a parking brake, and acting as a safety backup, thereby justifying its inclusion despite increased system 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 method effectively counteracts impermissible acceleration by providing sufficient braking torque, reducing the risk of damage to the drive train components and ensuring safe operation of the working machine.

Implementation Method 1

the drive motor (12) is drive-coupled to at least one wheel (10) of the working machine (1), so that a braking torque of the drive motor (12) counteracts a downhill slope force acting on the working machine (1)

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the assisting brake is actuated in accordance with a required braking torque

Methodology Applied

Scientific EffectFriction: Friction

Data Source

PatentUS20250198121A1Method for operating a drive train of a working machine, electrified drive train, and working machine

Publication Date: 2025.06.19 ZF FRIEDRICHSHAFEN AG

AI summary

A method for operating a drive train of a working machine, the drivetrain having a drive motor, a service brake, and an assisting brake, wherein a drive coupling is between the drive motor of the drive train and at least one wheel of the working machine such that a braking torque of the drive motor counteracts a downhill slope force acting on the working machine. Automated actuation of the assisting brake is undertaken if the working machine is subject to an impermissible acceleration, where the assisting brake is actuated in accordance with a required braking torque and in accordance with a thermal loading of the assisting brake. The assisting brake is configured as a spring-pressurized and hydraulically or pneumatically releasable brake. An electrified drive train and a corresponding working machine are also disclosed.