Engine Start Control Using Predicted Top Dead Centers
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Solution Overview
Problem
Existing methods for controlling the start of an internal combustion engine often result in unnecessary assisted starts due to a coarse threshold based on current engine speed, leading to accelerated wear of the electric motor used for starting, as the response time is not instantaneous and oversizes the threshold for autonomous starts.
Innovation Solution
A method that predicts the number of top dead centers remaining before zero engine speed is reached, allowing for a more precise choice between assisted and autonomous starts by comparing this prediction to a predetermined threshold, thereby reducing unnecessary assisted starts and motor wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the threshold for autonomous start is based on current engine speed, then the control method is simple, but the threshold is oversized leading to unnecessary assisted starts and increased motor wear
Solution Approach 1:
The system performs preliminary calculation of the number of top dead centers remaining before zero speed is reached, using the formula N_TDC = (J * ω^2) / (2 * τ_loss). This predictive action allows the system to anticipate the engine's deceleration trajectory and make accurate start mode decisions before the actual event occurs, avoiding oversized thresholds and unnecessary assisted starts.
Solution Approach 2:
The invention changes the control parameter from current engine speed alone to a combination of current speed and predicted top dead centers remaining. This parameter transformation enables more precise threshold setting for autonomous start authorization, reducing false positives and unnecessary electric motor activation.
2Loss of time
If the threshold is oversized to account for response time delay, then the response time uncertainty is covered, but unnecessary assisted starts occur and motor wear increases
Solution Approach 1:
The system uses feedback from the engine's current speed and torque characteristics to continuously update the prediction of top dead centers remaining. This closed-loop approach compensates for response time variations without requiring oversized thresholds, as the prediction adapts to actual engine behavior rather than relying on fixed conservative margins.
Solution Approach 2:
By calculating the predicted number of top dead centers in advance using the engine's current dynamic state, the system proactively determines the appropriate start mode before the deceleration event completes. This eliminates the need to add time buffers that would otherwise be required to account for response delays, thereby preventing unnecessary assisted starts and reducing motor wear.
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 enables more accurate control of engine restarts, reducing the number of unnecessary assisted starts and consequently minimizing the wear on the electric motor used for assisted starts.
Implementation Method 1
an electric motor rotates the shaft of the heat engine
Implementation Method 2
the motor shaft continues to rotate for a few moments (for example a few hundred milliseconds) after the request to stop the motor because of its inertia
Data Source
AI summary
The invention relates to a method for controlling the start-up of an internal combustion heat engine, said method comprising: controlling (56) assisted start-up of the heat engine wherein an electric motor rotates the shaft of the heat engine; and alternately, controlling (54) independent start-up of the heat engine wherein use is made solely of the residual rotation of the engine shaft which continues to rotate by the inertia thereof since the last stoppage of the engine, characterized in that the method comprises: predicting (46) the number of top dead center positions remaining before reaching a zero engine speed; and choosing (52) between assisted or independent control on the basis of said predicted number of positions.