Auto-ignition timing control and calibration method
First Claim
1. A method of controlling an internal combustion engine when operating in a controlled auto-ignition mode, the method comprising the steps of:
- before the commencement of an engine compression phase determining a target crank angle from a predetermined data table and from current engine operating conditions, the data table providing a plurality of auto-ignition timing crank angle data relating to a plurality of engine operating conditions;
determining a plurality of engine operating parameters;
iteratively performing the steps of(i) utilizing the plurality of engine operating parameters, computing a predicted compression temperature which would be reached by the combustible charge at the target crank angle during the compression phase of the engine cycle;
(ii) comparing the predicted compression temperature with a target temperature;
(iii) modifying a computational value of at least one settable engine operating parameter;
(iv) returning to step (i) until a combination of parameters is found which would result in the predicted compression temperature matching the target temperature at the target crank angle; and
setting at least one of the actual engine operating parameters for the engine cycle in accordance with the final values ascertained by the iterative calculation process.
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Abstract
An auto-ignition timing control and calibration method for use in an internal combustion engine having more than one ignition modes including the mode of compression ignition of a premixed fuel/air mixture (CAI/HCCI), wherein when the engine is operating in the CAI/HCCI mode, in order to determine a prescribed setting or combination of settings of engine operating parameters necessary to achieve a target auto-ignition timing according to a predetermined auto-ignition timing map, the associated compression temperature trajectory of the cylinder charge with time, calculated in dependence on the initial and boundary conditions of the said charge subjected to the said prescribed setting or combination of settings of the said engine operating parameters, and further in dependence on the interim heat exchange processes affecting the said charge, is used for testing and verifying that the said trajectory reaches a target temperature at a target reference timing relative to TDC of the engine, and wherein the said target temperature and timing are predetermined by calibration.
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Citations
33 Claims
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1. A method of controlling an internal combustion engine when operating in a controlled auto-ignition mode, the method comprising the steps of:
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before the commencement of an engine compression phase determining a target crank angle from a predetermined data table and from current engine operating conditions, the data table providing a plurality of auto-ignition timing crank angle data relating to a plurality of engine operating conditions; determining a plurality of engine operating parameters; iteratively performing the steps of (i) utilizing the plurality of engine operating parameters, computing a predicted compression temperature which would be reached by the combustible charge at the target crank angle during the compression phase of the engine cycle; (ii) comparing the predicted compression temperature with a target temperature; (iii) modifying a computational value of at least one settable engine operating parameter; (iv) returning to step (i) until a combination of parameters is found which would result in the predicted compression temperature matching the target temperature at the target crank angle; and setting at least one of the actual engine operating parameters for the engine cycle in accordance with the final values ascertained by the iterative calculation process. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of controlling an internal combustion engine when operating in a controlled auto-ignition mode, the method comprising the steps of:
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before the commencement of an engine compression phase determining a target crank angle from a predetermined data table and from current engine operating conditions, the data table providing a plurality of auto-ignition timing crank angle data relating to a plurality of engine operating conditions; determining a plurality of engine operating parameters; iteratively performing the steps of (i) utilizing the plurality of engine operating parameters, computing the crank angle during the compression phase of the engine cycle at which a target compression temperature would be reached by the combustible charge; (ii) comparing the predicted crank angle with the target crank angle; (iii) modifying the computational value of at least one of the settable engine operating parameters; (iv) returning to step (i), until a combination of parameters is found which would result in the target compression temperature being reached at a predicted crank angle matching the target crank angle; and setting at least one of the actual engine operating parameters for the engine cycle in accordance with the final values ascertained by the iterative calculation process. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method of controlling a spark ignition internal combustion engine having variable compression ratio, the method comprising the steps of:
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determining a plurality of engine operating parameters; iteratively performing the steps of (i) utilizing the plurality of engine operating parameters, computing a predicted compression temperature which would be reached by the combustible charge at a target crank angle during the compression phase of the engine; (ii) comparing the predicted compression temperature with a threshold temperature, the threshold temperature being lower than the auto-ignition temperature of the charge; (iii) modifying the value of at least one of the operating parameters; (iv) returning to step (i), until a combination of parameters is found which would result in the predicted compression temperature not exceeding the threshold temperature; and
,setting at least one of the actual engine operating parameters for the engine cycle in accordance with the final values ascertained by the iterative calculation process such as to prevent engine knock. - View Dependent Claims (32, 33)
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Specification