Engine Speed Control via Integral Threshold for Thermal Protection

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Solution Overview

Problem

Existing methods for controlling internal combustion engine speed fail to prevent thermal overloading, particularly during stationary or low-speed operations, as they allow prolonged operation at speeds just below the limiting speed, leading to potential thermal damage.

Innovation Solution

A device and method that monitor and limit engine speed by integrating speed values over time, automatically reducing speed to a predetermined limit when an integral threshold is reached, with adjustable thresholds and weightings to account for varying conditions, and provide warning signals to inform the driver.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If the engine speed is allowed to operate continuously just below the limiting speed, then the engine can maintain continuous operation, but thermal overloading and potential thermal damage occur

Engineering Contradiction:
Improvecontinuous operationVSAvoidthermal loading
Core Design Contradiction:
Duration of action of moving objectVSTemperature

Solution Approach 1:

The control device integrates engine speed values over time and proactively reduces engine speed before thermal damage occurs. By monitoring the integral of speed values and comparing them against a threshold, the system takes preliminary action to reduce speed when thermal loading becomes excessive, preventing thermal damage rather than reacting after damage has occurred.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors engine speed and integrates it over time to assess thermal loading. This feedback mechanism allows the control device to adjust engine speed dynamically based on accumulated thermal stress, creating a closed-loop control system that prevents thermal overloading while maintaining continuous operation.

Inventive Principle:
Principle #23Feedback

2Temperature

If the engine speed is limited to prevent thermal overloading, then thermal damage is prevented, but engine performance and productivity are reduced

Engineering Contradiction:
Improvethermal protectionVSAvoidengine performance
Core Design Contradiction:
TemperatureVSProductivity

Solution Approach 1:

The engine speed limit is not fixed but dynamically adjusted based on the integral of speed values over time. The control device continuously integrates actual engine speed values and compares them against a threshold, allowing the system to maintain higher speeds when thermal loading is low and reduce speed only when necessary, optimizing the balance between performance and thermal protection.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the operational parameters of engine speed based on accumulated thermal stress. By monitoring the integral of speed values and adjusting the speed limit dynamically, the system optimizes engine performance while preventing thermal overloading, rather than applying a static speed limit that would continuously reduce productivity.

Inventive Principle:
Principle #35Parameter changes

3Temperature

If a static speed limit is applied, then thermal overloading is prevented, but the engine cannot operate continuously at optimal speeds

Engineering Contradiction:
Improvethermal protectionVSAvoidoperational flexibility
Core Design Contradiction:
TemperatureVSAdaptability or versatility

Solution Approach 1:

The speed limit is transformed from a static value to a dynamic parameter that adapts to actual operating conditions. The control device continuously integrates engine speed values over time and adjusts the speed limit based on the accumulated integral, allowing the engine to operate at optimal speeds most of the time while automatically reducing speed only when thermal loading becomes excessive.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system performs preliminary integration of speed values to assess thermal loading trends before taking corrective action. This allows the engine to maintain flexible operation under normal conditions while proactively preventing thermal overloading through early speed reduction when the integral threshold is approached.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2118473B1Device and method for controlling an internal combustion engine of a motor vehicle
Publication Date: 2018.09.05 BAYERISCHE MOTOREN WERKE AG
  • EP2118473B1 patent drawingFigure 1~2

AI summary

The invention relates to a method for controlling an internal combustion engine of a motor vehicle, comprising means for monitoring and limiting the rotational speed of the internal combustion engine, said means being designed such that, beginning at a predetermined first rotational speed threshold, an integral formation of the present rotational speed values over time occurs and, upon reaching a predetermined integral threshold value, an automatic limitation of the rotational speed occurs.