Engine Inertia Control for Drivetrain Mode Transitions
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Solution Overview
Problem
During mode changes in a motor vehicle's drivetrain, such as from coasting to traction mode, inertia causes uncomfortable jolting and mechanical noises due to the mismatch in rotational speeds of gear teeth, leading to abrupt changes in coupling moments.
Innovation Solution
A method that determines the theoretical and actual inertia of the drivetrain, accelerates the engine's rotational speed to quickly overcome inertia, and reduces the rotational speed when the difference becomes less than a threshold, synchronizing the output speed with the drivetrain to minimize jolting and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the engine rotational speed is increased quickly to overcome inertia during mode change, then the response time is reduced and productivity is improved, but this causes abrupt changes in coupling moments that lead to uncomfortable jolting and mechanical noises
Solution Approach 1:
The controller predicts the upcoming inertia event based on detected operating parameters (engine speed, transmission output speed, gear state) and prepares the engine rotational speed in advance. By calculating the expected inertia magnitude and timing, the system adjusts the engine speed proactively before the actual mode change occurs, ensuring smooth transition without abrupt coupling moment changes that cause jolting and noise.
Solution Approach 2:
The system continuously monitors actual operating parameters during mode transitions and compares them with predicted values. Based on this feedback, the controller dynamically adjusts the engine rotational speed to maintain optimal transition characteristics. The feedback loop ensures that the engine speed is adjusted precisely according to actual inertia conditions, preventing both excessive speed changes that cause jolting and insufficient adjustments that delay response.
2Object-affected harmful factors
If the engine rotational speed is reduced to synchronize with drivetrain output speed, then mechanical noises and jolting are reduced, but the response time and acceleration performance deteriorate
Solution Approach 1:
The controller calculates the required engine rotational speed adjustment in advance based on predicted inertia events and transmission state. By preparing the speed adjustment before the mode change occurs, the system ensures that the engine is already at the optimal speed when the transition happens, eliminating the need for corrective speed reductions that would cause delays and mechanical noises.
Solution Approach 2:
The system dynamically adjusts engine rotational speed based on real-time operating conditions, including current speed, load, and predicted mode transitions. Rather than using fixed speed limits, the controller continuously optimizes the engine speed trajectory to balance noise reduction with rapid response, allowing the system to adapt its dynamics to each specific operating scenario.
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
This approach allows for smooth acceleration and reduces undesirable noises and jolting by quickly overcoming inertia and synchronizing rotational speeds, enhancing the driving experience.
Implementation Method 1
gear wheels in the transmission and other coupling elements, for example side shafts and the dual-mass flywheel, must undergo a certain amount of inertia
Data Source
AI summary
A method for controlling an engine in a motor vehicle includes determining a theoretical inertia of a drivetrain during a change of an operating mode of the engine, detecting an actual inertia in the drivetrain during the change of the operating mode, and increasing a rotational speed of the engine in response to detecting the actual inertia. The method further includes detecting an inertia overcome, determining a difference between the theoretical inertia and the inertia overcome, and reducing the rotational speed of the engine if the difference becomes less than a threshold value.