Coasting Mode Simulation via Engine Drag Torque Compensation
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Solution Overview
Problem
Conventional motor vehicles with internal combustion engines and manual or automatic transmissions face challenges in activating or deactivating a coasting operating mode without automatic clutch opening, limiting fuel-saving benefits and driver control.
Innovation Solution
Simulating a coasting operating mode by partially compensating engine drag torque with a controlled fuel/air mixture, allowing the vehicle to roll without perceptible engine drag torque, while maintaining driver control and avoiding transmission rattling or unintended acceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the drivetrain is opened automatically to eliminate engine drag torque, then fuel consumption is reduced, but the device complexity increases due to automatic clutch mechanisms
Solution Approach 1:
The driver manually operates the clutch to engage/disengage the drivetrain based on their own driving needs and perception of coasting conditions, eliminating the need for complex automatic sensing and control systems while achieving similar fuel-saving benefits
Solution Approach 2:
The automatic control system is extracted from the system, leaving only the manual clutch operation and driver decision-making, thereby simplifying the device complexity while maintaining the essential coasting function
2Loss of energy
If the drivetrain is opened to achieve coasting mode, then fuel efficiency improves, but the reliability decreases due to potential transmission rattling and unintended acceleration
Solution Approach 1:
The driver continuously monitors vehicle behavior and road conditions, providing real-time feedback through manual clutch operation to maintain stable transmission engagement only when appropriate, thereby preventing rattling and unintended acceleration while preserving fuel efficiency
Solution Approach 2:
The clutch engagement state dynamically adapts to varying driving conditions based on driver assessment, allowing the system to transition between engaged and disengaged states flexibly to maintain both fuel efficiency and transmission reliability
3Device complexity
If the clutch is kept closed to maintain simple control, then device complexity is reduced, but the fuel consumption increases due to engine drag torque
Solution Approach 1:
The driver takes direct responsibility for operating the clutch based on their own judgment of when coasting is beneficial, eliminating complex automatic control systems while enabling fuel-saving coasting operation through simple manual intervention
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
Enables fuel-efficient coasting without automatic clutch opening, providing similar driving sensations and fuel savings as conventional coasting modes, while preventing transmission issues and ensuring safe operation on varying road conditions.
Implementation Method 1
so much fuel/air mixture is fed to the internal combustion engine that the engine drag torque is largely but not completely compensated
Data Source
AI summary
The invention relates to a method and a device for operating a motor vehicle with an internal combustion engine in a coasting operating mode in which the motor vehicle rolls essentially in a propulsionless fashion and essentially without a perceptible engine drag torque on an essentially level road if there is no propulsion request or braking request from a driver of the motor vehicle. According to the invention, the coasting operating mode is not brought about by automatically opening the drivetrain but rather is simulated with the clutch closed in that so much air/fuel mixture is fed to the internal combustion engine that the engine drag torque is largely but not completely compensated.