Skip-Fire Engine Torque Control During Cylinder Transition Events
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Solution Overview
Problem
Skip-fire engine operations in combustion engines, such as asymmetric injection and cylinder deactivation, lead to increased noise, vibration, and harshness (NVH) due to strong torque fluctuations during transitions.
Innovation Solution
A method for defining cylinder torque demand during transitions by adjusting fuel injection dynamically, using a 'dynamic factor' that compensates for torque loss during transitions from one pattern to another, involving a transitioning phase with a fuel quantity adjustment that differs from the initial and final fuel quantities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If skip-fire engine operation is implemented to reduce fuel consumption and emissions, then fuel efficiency is improved, but noise, vibration, and harshness increase due to strong torque fluctuations
Solution Approach 1:
The patent applies dynamics by implementing a transitioning phase with dynamically adjusted fuel quantities that adapt during the transition from one firing pattern to another. The fuel injection system dynamically modifies the fuel quantity for transitioning fire events based on the torque loss from preceding or succeeding skip fire events, creating a smooth, time-varying transition that eliminates abrupt torque changes and reduces NVH effects.
Solution Approach 2:
The patent changes the parameter of fuel quantity during the transitioning phase. The fuel injection amount is modified from the first fuel quantity (in the first pattern) to the second fuel quantity (in the second pattern) through intermediate transitioning fuel quantities. This parameter change compensates for torque loss and maintains smooth torque output throughout the transition, preventing the torque fluctuations that cause NVH.
2Stability of the object's composition
If fuel injection is dynamically adjusted during transitioning phase, then torque oscillations are reduced, but fuel injection complexity increases
Solution Approach 1:
The patent implements feedback by using the known torque loss from preceding or succeeding skip fire events to determine the appropriate fuel quantity adjustment for transitioning fire events. The control system calculates the required fuel quantity based on the torque deficit that would otherwise occur, creating a closed-loop control mechanism that maintains stable torque output during transitions.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and applying the transitioning fuel quantity before the actual transition completes. The fuel injection is adjusted in advance during the transitioning phase to compensate for the upcoming or recent torque loss, ensuring smooth torque delivery without waiting for torque fluctuations to occur.
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 reduces torque oscillations and minimizes NVH effects by maintaining a smoother transition between active and inactive cylinders, ensuring consistent engine torque output.
Implementation Method 1
a combustion engine having a number N of cylinders... with a first fuel quantity for each fire event in the first cycle... with a second fuel quantity for each fire event in the second cycle
Data Source
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AI summary
A method for defining cylinder torque demand during transitions in skip-fire engine operation of a combustion engine having a number N of cylinders, the method comprising: firing the engine in first cycles of a first pattern of N events, that defines for each cylinder of the engine a fire or skip fire event in one cycle of the first cycles, with a first fuel quantity for each fire event in the first cycle; transitioning the engine to firing the engine in second cycles of a second pattern of N events of fire and skip fire events for each cylinder, with a second fuel quantity for each fire event in the second cycle; carrying out one or more transitioning fire events, in transitioning from the first to the second pattern, with a dynamic fuel quantity, to compensate for torque loss of a preceding or succeeding skip fire event of said fire event, wherein the adjustment differs from the first and/or second fuel quantity.