Methods for low emission, controlled temperature combustion in engines which utilize late direct cylinder injection of fuel
First Claim
1. A method for combustion in a fuel combustion engine which utilizes late direct injection of fuel into a combustion chamber, comprising:
- maintaining oxygen concentration in a charge-air mixture for combustion within a desired oxygen concentration range;
compressing the charge-air mixture;
determining the resulting boost pressure of the compressed charge-air mixture;
taking the compressed charge-air mixture into the combustion chamber;
directly injecting a quantity of fuel into the combustion chamber responsive to the determined boost pressure of the compressed charge-air mixture; and
combusting the fuel and charge-air mixture in the combustion chamber.
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Abstract
The present invention provides a method for close control and adjustment of in-cylinder oxygen concentration levels together with boost adjustments in such a way as to minimize harmful emissions during transients in engines which utilize late direct cylinder injection of fuel. In this invention, EGR flow rates are adjusted by means of an EGR control valve in a closed loop, linked fashion together with boost pressure changes during transients, to maintain intake charge-air oxygen concentration and boost levels within critical ranges for controlled temperature, low emission combustion. Furthermore, in order to minimize harmful emissions during rapid transient changes in operating conditions, changes in fuel feed into the cylinder are made to wait for or follow changes in the boost level of charge-air into the cylinder for combustion. This addresses a problem in diesel engines, during acceleration, of having temporary fuel levels in excess of desired fuel/oxygen ratios during transients, with the result of increased PM levels from insufficient oxygen for rapid, complete combustion. In this invention, temporary fuel levels do not exceed desired fuel/oxygen ratios during transients, by means of controlling fuel feed responsive to the level of boost of charge-air being taken into the cylinder for combustion.
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Citations
21 Claims
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1. A method for combustion in a fuel combustion engine which utilizes late direct injection of fuel into a combustion chamber, comprising:
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maintaining oxygen concentration in a charge-air mixture for combustion within a desired oxygen concentration range;
compressing the charge-air mixture;
determining the resulting boost pressure of the compressed charge-air mixture;
taking the compressed charge-air mixture into the combustion chamber;
directly injecting a quantity of fuel into the combustion chamber responsive to the determined boost pressure of the compressed charge-air mixture; and
combusting the fuel and charge-air mixture in the combustion chamber. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of operating an internal combustion engine, in a motor vehicle, which utilizes direct injection of fuel into a combustion chamber, comprising:
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combining recirculated exhaust gas with ambient air to form a charge-air mixture;
adjusting the oxygen concentration of the charge-air mixture, if necessary, to fall within a desired oxygen concentration range;
determining a demand for power to be produced by the internal combustion engine;
determining a desired charge-air boost pressure corresponding to said demand for power;
compressing the charge-air mixture to, or nearer to, the desired charge-air boost pressure;
determining the boost pressure of the compressed charge-air mixture;
taking the compressed charge-air mixture into a cylinder of the engine for combustion;
determining a desired quantity of fuel for combustion corresponding to the determined charge-air boost pressure of the compressed charge-air mixture;
injecting the desired quantity of fuel directly into the engine cylinder; and
combusting the fuel and charge-air mixture within the engine cylinder. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A direct injection internal combustion engine, comprising:
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a plurality of cylinders, each cylinder providing a combustion chamber;
an exhaust gas recirculation system in operative communication with said cylinders, for combining with ambient air a portion of exhaust gas produced from said combustion chambers to form a charge-air mixture, and returning said charge-air mixture to said cylinders for combustion;
a boost system in operative communication with said exhaust gas recirculation system, for compressing said ambient air or charge-air mixture before taking in said charge-air mixture into said cylinders for combustion;
a fuel injection system in operative communication with the cylinders, for injecting fuel into each of said cylinders for combustion;
a controller for adjusting operation of the exhaust gas recirculation system, boost system and fuel injection system, programmed to;
(1) make adjustments to said exhaust gas recirculation system to control the oxygen concentration of the charge-air mixture to within a target range;
(2) make adjustments to said boost system to control the boost pressure of the charge-air mixture responsive to a demand for power from the engine; and
(3) regulate the amount of fuel injected into each cylinder responsive to the boost pressure of the charge-air mixture. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification