Engine Torque Control via Friction-Based Integral Limiting
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Solution Overview
Problem
Internal combustion engines face challenges in maintaining operational reliability, particularly during load shedding, due to abrupt load changes and the difficulty in managing rpm fluctuations, which can lead to safety-critical issues like emergency stops.
Innovation Solution
The method involves limiting the I component of the rpm controller to a lower limit value calculated based on friction torque, and limiting the set torque value to this lower limit, using a friction torque map that accounts for virtual temperature and actual rpm, to stabilize engine operation during load shedding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the I component of the rpm controller is not limited, then the engine can respond freely to load changes, but abrupt load changes cause significant rpm fluctuations and increase correction time
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the lower limit value of the I component based on friction torque calculations. The limit value is determined from a friction torque map using virtual temperature and actual rpm, allowing the control system to adapt the integral component's behavior according to current engine operating conditions and friction characteristics during load shedding events.
Solution Approach 2:
The patent implements feedback by continuously monitoring actual rpm and using it to calculate friction torque through the friction torque map. The friction torque calculation depends on virtual temperature and actual rpm values, creating a closed-loop system that adjusts the I component limit based on real-time engine state, thereby reducing rpm fluctuations during load changes.
2Adaptability or versatility
If the set torque value is not limited to the lower limit, then the engine operates with full control range, but rpm fluctuations increase and correction time extends
Solution Approach 1:
The patent applies dynamics by making the lower limit value dynamic rather than fixed. The limit is calculated in real-time based on friction torque, which varies with operating conditions. This dynamic adjustment allows the control system to optimize the balance between control range and correction time according to current engine state, reducing unnecessary restrictions during normal operation while providing protection during load shedding.
3Device complexity
If friction torque is not accurately accounted for, then the control system is simpler, but rpm stability during load shedding deteriorates
Solution Approach 1:
The patent uses friction torque as an intermediary parameter to bridge the gap between engine operating conditions and control actions. The friction torque map acts as a mediator that translates physical friction characteristics into control limit values, allowing the system to account for friction effects without directly controlling friction forces. This intermediary approach maintains rpm stability while keeping the control system relatively simple.
Data Source
AI summary
A method for the torque-oriented control of an internal combustion engine, in which a sum torque (MSUM) is calculated from a set torque value (MSW) and a friction torque (MF). A set injection quantity (mSL) for driving the internal combustion engine is calculated from the sum torque (MSUM) and an actual rpm value (nIST) by the use of an efficiency map (WKF). The set torque value (MSW) is calculated by way of an rpm controller with at least PI behavior from an rpm control deviation (e) between the set rpm value (nSL) and the actual rpm value (nIST), and the I component of the rpm controller is limited to a lower limit value (uGW), which is determined as a function of the friction torque (MF) (uGW=f(MF)).