Brake Pedal Pressure Logic for Engine Start-Stop Control

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Solution Overview

Problem

Current automatic start-stop systems for internal combustion engines in vehicles often switch off the engine in undesirable situations, such as at turning lanes or stop signs, and require the driver to continuously press the brake pedal to prevent engine restart, leading to discomfort and inefficiency, especially in vehicles with automatic transmissions.

Innovation Solution

A method that allows the driver to prevent automatic engine shutdown by pressing the brake pedal harder when the engine is switched off, activating a switch-on preventer, and uses a holding function to maintain the vehicle's standstill without continuous brake pedal pressure, enabling the driver to take their foot off the pedal and restart the engine by pressing the accelerator when ready.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the internal combustion engine is automatically switched off when the vehicle is braked to a standstill, then fuel consumption is reduced, but the driver cannot prevent unwanted shutdown in situations like turning lanes or stop signs

Engineering Contradiction:
Improvefuel consumptionVSAvoiddriver control
Core Design Contradiction:
Loss of energyVSEase of operation

Solution Approach 1:

The system performs preliminary evaluation of traffic situation parameters (turning lane detection, stop sign detection, traffic light detection) before automatically switching off the engine. This preliminary action prevents unwanted shutdowns by identifying situations where the vehicle should remain ready for immediate movement, thus resolving the contradiction between fuel savings and driver control.

Inventive Principle:
Principle #10Preliminary action

2Object-generated harmful factors

If the internal combustion engine is switched off automatically, then pollutant emissions are reduced, but the vehicle may roll away without continuous brake pressure

Engineering Contradiction:
Improvepollutant emissionsVSAvoidvehicle stability
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The holding function serves as a reliable intermediary mechanism that ensures vehicle stability when the engine is switched off. It automatically maintains the vehicle in a stationary state without requiring continuous driver input, thus resolving the contradiction between emission reduction and vehicle stability by providing automated reliability assurance.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The holding function operates autonomously to maintain vehicle stationary position after the engine shutdown. It self-regulates the braking force needed to prevent rolling without continuous driver intervention, enabling the system to serve itself in maintaining stability while the engine remains off for emission reduction.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2358990B1Method for automatic start and stop of a combustion engine
Publication Date: 2017.09.20 BAYERISCHE MOTOREN WERKE AG
  • EP2358990B1 patent drawingFigure 1

AI summary

The invention relates to a method and to a corresponding device for automatically turning off and starting an internal combustion engine in a motor vehicle by means of a start-stop unit, which automatically turns off the internal combustion engine when the vehicle is braked to a stop and is held at a stop by actuation of the brake pedal, and which automatically starts it when the internal combustion engine is automatically turned off and the actuated brake pedal is released. The invention is characterized in that automatic starting of the internal combustion engine by releasing the brake can be prevented when the internal combustion engine has been automatically turned off, by first depressing the brake pedal harder with the internal combustion engine being turned off.