Engine Brake Activation Threshold Based on Output Shaft Speed

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Solution Overview

Problem

Continuous braking systems in commercial vehicles face challenges in precisely setting continuous braking torque due to differing torque dependencies on output shaft speed and engine speed, leading to inefficient activation and deactivation of engine braking devices, which results in noise pollution and reduced precision.

Innovation Solution

A method and device that determine the switch-on and switch-off conditions of the engine brake based on output shaft speed-dependent torque threshold values, comparing them with requested braking torque, allowing for optimized activation and deactivation times to minimize unnecessary switching and noise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the engine brake is activated early to ensure sufficient braking torque, then the braking precision is improved, but noise pollution increases due to frequent activation and deactivation

Engineering Contradiction:

Improvebraking torque precisionVSAvoidnoise pollution

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the traditional mechanical switching decision with an electronic control system that calculates torque threshold values based on output shaft speed. The control unit determines whether to activate the engine brake by comparing the current braking torque requirement against calculated threshold values, substituting mechanical intuition with precise electronic computation to optimize both braking precision and noise reduction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent dynamically changes the activation threshold parameter based on output shaft speed. The torque threshold value is not fixed but varies with the operating conditions (output shaft speed), allowing the system to activate the engine brake at optimal moments that balance braking precision requirements with noise reduction goals.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If the engine brake is activated late to reduce noise, then noise pollution is reduced, but the braking torque precision deteriorates

Engineering Contradiction:

Improvenoise pollutionVSAvoidbraking torque precision

Core Design Contradiction:

Object-affected harmful factorsVSMeasurement precision

Solution Approach 1:

The patent makes the activation threshold dynamic rather than static. The torque threshold value changes continuously with output shaft speed, allowing the system to adapt to varying operating conditions. This dynamic approach enables late activation at low speeds (reducing noise) while maintaining precise braking control when needed.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The control unit continuously monitors the current braking torque and compares it against the dynamically calculated threshold value. This feedback mechanism ensures that the engine brake is activated at the precise moment when it becomes necessary, balancing noise reduction with braking precision requirements.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If the engine brake is frequently activated and deactivated to maintain optimal braking torque, then the braking precision is improved, but the system reliability deteriorates due to increased wear and noise

Engineering Contradiction:

Improvebraking torque precisionVSAvoidsystem reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The control unit calculates the torque threshold value in advance based on the current output shaft speed and braking requirements. By determining the optimal activation point beforehand through computation, the system avoids frequent reactive switching, thereby maintaining braking precision while reducing wear and improving reliability.

Inventive Principle:

Principle #10Preliminary action

4Measurement precision

If the engine brake is kept activated for long periods to maintain braking torque, then the braking precision is maintained, but noise pollution increases

Engineering Contradiction:

Improvebraking torque precisionVSAvoidnoise pollution

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent uses electronic control to precisely determine the minimum activation period needed to achieve the desired braking torque. By substituting mechanical continuous operation with electronically controlled intermittent operation, the system maintains braking precision while minimizing noise pollution through optimized activation duration.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentEP2123500B1Method and device for determining the activation and deactivation condition for a motor brake of a long-term brake assembly of a vehicle, in particular a commercial vehicle

Publication Date: 2010.09.22 MAN TRUCK & BUS SE

Figure 1

AI summary

The method involves stopping a permanent brake torque at an output shaft of an output strand by a brake torque depending on the given driving parameters. The brake torque is requested by a control equipment of a permanent brake system of an engine brake unit and by a retarding unit. The activation and deactivation of the engine brake unit is given as a function of a torque threshold value. The torque threshold value is determined as a function of the output shaft rotation speed. An independent claim is included for a device for executing switching on and switching off requirements determining method for an engine brake unit of a permanent brake system of a vehicle.