Engine Drag Torque Control via Road Friction Data
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Solution Overview
Problem
Conventional engine drag-torque control methods fail to adapt to instantaneous driving situations and varying road conditions, leading to potential skidding of drive wheels and instability in motor vehicles, especially on slippery surfaces.
Innovation Solution
The method dynamically adjusts the maximum engine drag torque based on the current coefficient of friction determined by a satellite-based navigation system, which queries and updates a central database for real-time friction data, allowing for early intervention in low-friction conditions and optimizing engine management to prevent wheel skidding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a maximum engine drag torque is preset to prevent wheel skidding, then vehicle stability is improved, but the control cannot adapt to changing road conditions leading to potential skidding on slippery surfaces
Solution Approach 1:
The patent implements dynamic adjustment of the maximum engine drag torque based on real-time road friction conditions. The control parameter (maximum drag torque) is no longer fixed but continuously adapted according to the actual road surface friction coefficient detected by the navigation system and database, making the system responsive to changing environmental conditions.
Solution Approach 2:
The system establishes a feedback loop where road friction information is continuously obtained through satellite-based navigation and database queries, then used to adjust the engine drag torque control parameters. This closed-loop approach ensures the control system responds to actual road conditions rather than relying on preset values.
2Ease of manufacture
If engine drag-torque control is carried out using conventional preset values, then implementation is simple, but the control is not adapted to instantaneous driving situations and varying road conditions
Solution Approach 1:
The patent introduces a central database as an intermediary between the vehicle's navigation system and the engine control unit. This database stores road friction coefficient information and provides it to the control system, enabling adaptive drag torque control without requiring complex direct sensing infrastructure at each vehicle.
Solution Approach 2:
The system leverages the existing satellite-based navigation system already present in most modern vehicles for its primary positioning function, and repurposes it to also provide location data for querying road friction conditions. This multi-functional use of existing infrastructure reduces additional hardware requirements.
3Speed
If the maximum engine drag torque is increased to improve response time, then wheel skidding prevention is enhanced, but the risk of exceeding force-transmission capability and causing instability increases
Solution Approach 1:
The patent dynamically changes the maximum drag torque parameter based on the detected road friction coefficient. On high-friction surfaces, higher drag torque can be applied for faster response, while on low-friction surfaces, the maximum drag torque is reduced to prevent wheel skidding. This parameter adaptation resolves the contradiction between response speed and stability.
Data Source
AI summary
A method for operating a motor vehicle that has at least one driving engine which is operatively connected to at least one drive wheel and is controlled as a function of an accelerator-pedal position in order to generate a drive torque, an engine drag-torque control being carried out to avoid skidding of the drive wheel when the accelerator pedal is moved in the direction of a neutral position. It is provided that a maximum permissible engine drag torque is specified to the engine drag-torque control as a function of a currently effective coefficient of friction of the road surface which is determined as a function of a present position of the motor vehicle.