Vehicle Acceleration Control via Demand Limit Filtering
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Solution Overview
Problem
Existing vehicle acceleration control systems for internal combustion engines face challenges in managing acceleration aggressiveness and torque bumps, particularly when transitioning from smoke-limited to un-smoke-limited conditions, leading to non-linear torque feel during acceleration.
Innovation Solution
A method and system that determine a demand limit based on a smoke limit, user-selected acceleration profile, and a predetermined step quantity, controlling fuel injectors to achieve a subsequent demand limit that smooths acceleration and avoids torque bumps by filtering the fuel quantity demand, ensuring a consistent and controlled acceleration profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the fuel quantity demand is increased to achieve faster acceleration, then the acceleration speed improves, but torque bumps and non-linear torque feel occur during acceleration
Solution Approach 1:
The control system pre-determines a series of demand limits before acceleration begins, based on the selected acceleration profile. These demand limits are calculated in advance to prevent torque bumps, ensuring smooth acceleration from the start without requiring real-time corrections during the acceleration event.
Solution Approach 2:
The system dynamically adjusts the demand limit based on current engine operating conditions, including current demand, smoke limits, and turbocharger state. The control circuit determines subsequent demand limits by comparing multiple factors (current demand, smoke limit, and predetermined step quantities) and selecting the appropriate limit to maintain smooth acceleration throughout the transition.
2Productivity
If the acceleration profile is made more aggressive to improve productivity, then the acceleration time decreases, but torque bumps and operator comfort deteriorate
Solution Approach 1:
The system offers multiple pre-configured acceleration profiles (e.g., conservative, moderate, aggressive) that define different rates of demand increase. Operators can select the desired profile based on conditions, and the control system adjusts the demand limit progression accordingly, balancing acceleration speed with smoothness for optimal operator comfort and productivity.
3Power
If the demand limit is increased beyond the smoke limit to achieve higher power output, then the power increases, but smoke emissions and engine reliability worsen
Solution Approach 1:
The control system continuously monitors engine operating conditions and turbocharger state to determine the current smoke limit. The demand limit is adjusted based on feedback from these conditions, allowing the engine to operate at maximum power without exceeding smoke emissions thresholds. The system adapts the demand limit in real-time as turbocharger boost increases and smoke limits are reached.
Data Source
AI summary
A method for controlling acceleration of a vehicle having an internal combustion engine includes determining a first demand limit based on a smoke limit of the engine; determining a second demand limit based on a user-selected acceleration profile; retrieving a previous demand limit from a memory; and determining a third demand limit by adding a predetermined step quantity to the previous demand limit. The method further includes outputting the lesser of the first demand limit, the second demand limit, and the third demand limit as a subsequent demand limit. The method further includes controlling the engine with a control circuit to achieve the subsequent demand limit such that the vehicle accelerates from a speed associated with the previous demand limit to a speed associated with the subsequent demand limit.