초록 ▼

An internal combustion engine that can be operated in compression ignition mode, comprising a fuel injector (2) for each cylinder; a fuel injection control unit (4) for controlling fuel injection quantity and a piston (5) in each cylinder whose compression action causes a mixture of air and fuel to

An internal combustion engine that can be operated in compression ignition mode, comprising a fuel injector (2) for each cylinder; a fuel injection control unit (4) for controlling fuel injection quantity and a piston (5) in each cylinder whose compression action causes a mixture of air and fuel to be ignited. The engine is further provided with inlet and outlet valves (6, 7) and sensors (12-16) for measuring various engine operating parameters, is disclosed. During compression ignition mode, the control unit controls the fuel injector to perform a first fuel injection before, and a second fuel injection after top dead center of the piston stroke during or after a negative valve overlap period. A method for operating the engine and a computer readable storage device (4) having stored therein data representing instructions executable by a computer to implement a compression ignition for an internal combustion engine is also described.

대표청구항 ▼

The invention claimed is: 1. An internal combustion engine provided with at least one cylinder (1) and comprising: a fuel injector (2), through which fuel is injected into a combustion chamber (3), for each cylinder; a fuel injection control unit (4) that controls fuel injection quantity per combus

The invention claimed is: 1. An internal combustion engine provided with at least one cylinder (1) and comprising: a fuel injector (2), through which fuel is injected into a combustion chamber (3), for each cylinder; a fuel injection control unit (4) that controls fuel injection quantity per combustion cycle injected through each fuel injector; a piston (5) in the engine cylinder whose compression action causes a mixture of air and fuel within the combustion chamber to be ignited; at least one inlet valve (6) for admitting gas which includes fresh air into said cylinder; at least one exhaust valve (7) for exhausting combusted gases from said cylinder; at least one sensor for measuring an engine operation parameter; wherein during compression ignition mode, the exhaust valve is arranged to be closed before top dead center during an exhaust stroke of the piston and the intake valve is arranged to be opened after top dead center during an induction stroke of the piston, in order to retain residual exhaust gas, and the fuel injection control unit is arranged to control the fuel injection quantity so as to perform a first fuel injection before top dead center of the piston exhaust stroke and to perform at least one further fuel injection in the interval after top dead center of the piston stroke and before top dead center of a subsequent piston compression stroke. 2. The internal combustion engine according to claim 1, wherein the amount of fuel injected during said first and second injection is determined by the fuel injection control unit on the basis of comparison between predetermined limit values for an engine knock signal and a combustion stability signal transmitted from said at least one sensor. 3. The internal combustion engine according to claim 2, wherein the retained residual exhaust gas has a lambda-value of λ >1. 4. The internal combustion engine according to claim 2, wherein an in-cylinder pressure sensor is arranged to transmit a signal representative of both engine knock and combustion stability. 5. The internal combustion engine according to claim 2, wherein an engine knocking sensor and an engine stability sensor are arranged to transmit signals representative of engine knock and engine stability respectively. 6. An internal combustion engine according to claim 5, wherein the engine knocking sensor is a pressure sensor. 7. An internal combustion engine according to claim 5, wherein said engine stability sensor is an acceleration sensor. 8. The internal combustion engine according to claim 2, wherein the total amount of fuel injected during the first injection and a further injection is substantially constant. 9. The internal combustion engine according to claim 8, wherein if the knock signal and the stability signal are below their predetermined limit values, the fuel injection control unit is arranged to reduce the amount injected during the first injection. 10. An internal combustion engine according to claim 8, wherein if the knock signal and the stability signal are above their predetermined limit values, the fuel injection control unit is arranged to increase the amount injected during the first injection. 11. The internal combustion engine according to claim 8, wherein if the knock signal is above its predetermined limit value and the stability signal is below its predetermined limit value, the fuel injection control unit is arranged to reduce the amount injected during the first injection. 12. The internal combustion engine according to claim 8, wherein if the knock signal is below a predetermined limit value and the stability signal is above a predetermined limit value, the fuel injection control unit is arranged to increase the amount injected during the first injection. 13. The internal combustion engine according to claim 12, wherein if it is detected that a combustion peak pressure occurs earlier than a predetermined point in time, the fuel injection control unit is arranged to increase the amount of fuel injected during the first injection for the subsequent combustion cycle. 14. The internal combustion engine according to claim 12, wherein if it is detected that a combustion peak pressure occurs later than a predetermined point in time, the fuel injection control unit is arranged to increase the amount of fuel injected during the first injection for the cycle following the subsequent combustion cycle. 15. The internal combustion engine according to claim 8, wherein the first injection is a pilot injection and the second injection is a main injection. 16. The internal combustion engine according to claim 15, wherein that quantity of the first injection is preferably greater than zero but less than 45% of the total amount of injected fuel. 17. The internal combustion engine according to claim 1, wherein the cylinder is provided with a sparking unit that is arranged to sustain a spark during compression ignition mode. 18. A method for operating an internal combustion engine provided with at least one cylinder and operable in compression ignition mode, said engine comprising a fuel injector, through which fuel is injected into a combustion chamber, for each cylinder, a fuel injection control unit that controls fuel injection quantity per combustion cycle injected through each fuel injector, a piston in the engine cylinder whose compression action causes a mixture of air and fuel within the combustion chamber to be ignited during compression ignition mode, at least one inlet valve for admitting gas which includes fresh air into said cylinder, at least one exhaust valve for exhausting combusted gases from said cylinder, at least one sensor for measuring an engine operation parameter, the method comprising: adjusting opening and closing timings of the inlet valve and the exhaust valve so that the piston moving within the cylinder performs an intake phase, a compression phase, an expansion phase, an exhaust phase and an exhaust retaining phase; and during the exhaust retaining phase of the compression ignition: closing the exhaust valve before top dead center during an exhaust stroke of the piston and opening the intake valve after top dead center during an induction stroke of the piston; controlling the fuel injection control unit so as to perform a first fuel injection before top dead center of the piston stroke, which fuel reacts with excess oxygen from the previous combustion, and controlling the fuel injection control unit so as to perform at least one further fuel injection in the interval after top dead center of the piston stroke and before top dead center of a subsequent piston compression stroke. 19. The method according to claim 18, further comprising comparing each of the knock signal and the stability signal with a respective predetermined limit value, and reducing the amount injected during the first injection if both signals are below their predetermined limit values. 20. The method according to claim 18, further comprising comparing each of the knock signal and the stability signal with a respective predetermined limit value, and increasing the amount injected during the first injection if both signals are above their predetermined limit values. 21. The method according to claim 18, further comprising comparing each of the knock signal and the stability signal with a respective predetermined limit value, and reducing the amount injected during the first injection if the knock signal is above its predetermined limit value and the stability signal is below its predetermined limit value. 22. The method according to claim 18, further comprising comparing each of the knock signal and the stability signal with a respective predetermined limit value, and increasing the amount injected during the first injection if the knock signal is below a predetermined limit value and the stability signal is above a predetermined limit value. 23. The method according to claim 22, further comprising detecting a combustion peak pressure timing and comparing the actual timing of the peak pressure with a predicted timing of peak pressure, and increasing the amount of fuel injected during the first injection for the subsequent combustion cycle if the actual timing occurs earlier than said predicted timing. 24. The method according to claim 22, further comprising detecting a combustion peak pressure timing and comparing the actual timing of the peak pressure with a predicted timing of peak pressure, and increasing the amount of fuel injected during the first injection for the cycle following the subsequent combustion cycle if the actual timing occurs later than said predicted timing.