Internal combustion engine

Abstract

An internal combustion engine (1) operating in cycles, having: a plurality of piston-cylinder units (2), wherein each piston-cylinder unit (2) of the plurality of piston-cylinder units (2) is assigned an ignition device (3) which can be controlled regarding activation and selection of an ignition timing by an engine control (4), wherein a piston-cylinder unit (2), when the ignition device (3) is activated, produces a power by combustion of a gas-air mixture, which can be transmitted as a torque to a crankshaft (5) of the internal combustion engine (1) an intake stroke (6) and an exhaust stroke (7), each coupled to the plurality of piston-cylinder units (2) a supply device (8) for supplying a gas-air mixture under a boost pressure to the intake stroke (6) a signal detection device (9) for acquiring at least one signal which represents a power demand on the internal combustion engine (1) or from which a power demand on the internal combustion engine (1) can be calculated an engine control (4) for actuating actuators of the internal combustion engine (1), wherein the at least one signal can be fed to the engine control (4), and the engine control (4) is configured in a first operating mode to leave as many ignition devices (8) deactivated per cycle of the internal combustion engine in dependence on the currently present power demand, that the power of those piston-cylinder units (2), the ignition devices (8) of which are activated, results in a torque of the crankshaft (5) of the internal combustion engine (1) adapted to the currently present power demand
wherein the engine control (4) is configured to, in a second operating mode, for reducing a risk of deflagration due to unburned gas-air mixture present in the exhaust stroke (7) after a first number (N.sub.1) of cycles of the internal combustion engine (1), for a second number (N.sub.2) of cycles of the internal combustion engine (1), to have more piston-cylinder units (2) produce power per cycle by activating the assigned ignition devices (8) than would be required for the currently present power demand after the second number (N.sub.2) of cycles of the internal combustion engine (1), for a third number (N.sub.3) of cycles of the internal combustion engine (1), in dependence on a currently present power demand per cycle of the internal combustion engine (1), to have so many piston-cylinder units (2) produce power by activation of the assigned ignition devices (8) that this results in a torque of the crankshaft (5) adapted to the currently present power demand.

Claims

1. A system, comprising: a controller configured to control a power output of an internal combustion engine having a plurality of combustion chambers associated with a respective plurality of piston-cylinder assemblies, wherein the controller is configured to: control an ignition to skip firing in at least one combustion chamber of the plurality of combustion chambers for a first number of cycles; control the ignition to fire in the at least one combustion chamber of the plurality of combustion chambers for a second number of cycles after the first number of cycles; and control at least one actuator to reduce a power produced by firing in the at least one combustion chamber of the plurality of combustion chambers during the second number of cycles.

2. The system of claim 1, wherein the controller is configured to control the at least one actuator to reduce the power produced by at least: adjusting an ignition timing to a late setting for the at least one combustion chamber firing during the second number of cycles.

3. The system of claim 2, wherein the late setting of the ignition timing comprises a value between 0° and 30° before a piston of the at least one combustion chamber reaches a top dead center (TDC) position.

4. The system of claim 1, wherein the controller is configured to control the at least one actuator to reduce the power produced by at least: lowering a boost pressure in an intake stroke for the at least one combustion chamber firing during the second number of cycles.

5. The system of claim 4, wherein lowering the boost pressure in the intake stroke comprises at least partially closing a throttle valve.

6. The system of claim 4, wherein lowering the boost pressure in the intake stroke comprises at least partially bypassing a turbocharger of the internal combustion engine.

7. The system of claim 1, wherein the controller is configured to switch operation of the internal combustion engine between a first operating mode and a second operating mode in response to a change in a power demand and/or a rate of change in the power demand exceeding a threshold limit value, wherein the second operating mode includes at least a sequence of the first and second cycles.

8. The system of claim 1, wherein the controller is configured to repeat a sequence of the first and second number of cycles.

9. The system of claim 8, wherein the controller is configured to change the first number of cycles and/or the second number of cycles when repeating the sequence.

10. The system of claim 1, wherein the first number of cycles is greater than the second number of cycles.

11. The system of claim 10, wherein the first number of cycles is three and the second number of cycles is one.

12. The system of claim 1, wherein, during the second number of cycles, the controller is configured to control the ignition to fire in a first number of combustion chambers of the plurality of combustion chambers greater than needed to meet a power demand, and the controller is configured to control the at least one actuator to reduce the power produced by the first number of combustion chambers based on the power demand.

13. The system of claim 12, wherein, during a third number of cycles, the controller is configured to control the ignition to fire in a second number of combustion chambers of the plurality of combustion chambers adapted to meet the power demand.

14. The system of claim 13, wherein the controller is configured to not reduce the power produced by firing the second number of combustion chambers during the third number of cycles.

15. The system of claim 1, comprising the internal combustion engine having the plurality of piston-cylinder assemblies.

16. A method, comprising: controlling a power output of an internal combustion engine having a plurality of combustion chambers associated with a respective plurality of piston-cylinder assemblies, wherein controlling the power output comprises: controlling an ignition to skip firing in at least one combustion chamber of the plurality of combustion chambers for a first number of cycles; controlling the ignition to fire in the at least one combustion chamber of the plurality of combustion chambers for a second number of cycles after the first number of cycles; and controlling at least one actuator to reduce a power produced by firing in the at least one combustion chamber of the plurality of combustion chambers during the second number of cycles.

17. The method of claim 16, wherein controlling the at least one actuator to reduce the power produced by firing comprises: adjusting an ignition timing to a late setting for the at least one combustion chamber firing during the second number of cycles.

18. The method of claim 16, wherein controlling the at least one actuator to reduce the power produced by firing comprises: lowering a boost pressure in an intake stroke for the at least one combustion chamber firing during the second number of cycles.

19. The method of claim 16, wherein controlling the power output comprises switching operation of the internal combustion engine between a first operating mode and a second operating mode in response to a change in a power demand and/or a rate of change in the power demand exceeding a threshold limit value, wherein the second operating mode includes at least a sequence of the first and second cycles.

20. A system, comprising: an internal combustion engine having at least one combustion chamber associated with a respective piston-cylinder assembly; and a controller configured to control a power output of the internal combustion engine, wherein the controller is configured to: control an ignition to skip firing in the least one combustion chamber for a first number of cycles; control the ignition to fire in the at least one combustion chamber for a second number of cycles after the first number of cycles; and control at least one actuator to reduce a power produced by firing in the at least one combustion chamber during the second number of cycles.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the invention is discussed with reference to the figures.

(2) FIG. 1 schematically shows an internal combustion engine according to the invention.

(3) FIG. 2 schematically shows a genset according to the invention.

(4) FIG. 3 schematically shows an exemplary procedure in the case of load shedding according to a first embodiment.

(5) FIG. 4 schematically shows an exemplary procedure in the case of load shedding according to a second embodiment.

DETAILED DESCRIPTION

(6) FIG. 1 shows an internal combustion engine 1 according to the invention with a plurality of piston-cylinder units 2, wherein each piston-cylinder unit 2 is assigned an ignition device 3, which is controllable in terms of activation and selection of an ignition timing by an engine control 4, wherein a piston-cylinder unit 2, when the ignition device 3 is activated, produces power by combustion of a gas-air mixture, which power is transmittable as torque to a crankshaft 5 of the internal combustion engine 1.

(7) The internal combustion engine further comprises: an intake stroke 6 and an exhaust stroke 7, each coupled to the plurality of piston-cylinder units 2, wherein an optional catalyst 15 is arranged in the exhaust stroke 7 a supply device 8 for supplying a gas-air mixture under a boost pressure to the intake stroke 6 a signal detection device 9 for acquiring at least one signal which represents a power demand on the internal combustion engine 1 or from which a power demand on the internal combustion engine 1 can be calculated (here, the at least one signal of the signal detection device 9 is a rotational speed signal representing a rotational speed n of the crankshaft 5)

(8) The engine control 4 is used to control actuators of the internal combustion engine 1 (in the context of an open or closed control loop), wherein the at least one signal is feedable to the engine control 4, and the engine control 4 is configured in a first operating mode to leave so many ignition devices 3 deactivated per cycle of the internal combustion engine 1 depending on the currently present power demand, that the power of those piston-cylinder units 2, whose ignition devices 3 are activated, results in a torque of the crankshaft 5 of the internal combustion engine 1 adapted to the currently present power demand.

(9) The engine control 4 is further configured to, in a second operating mode for reducing a risk of deflagration due to unburned gas-air mixture present in the exhaust stroke 7 after a first number N1 of cycles of the internal combustion engine 1, for a second number N2 of cycles of the internal combustion engine 1, to have more piston-cylinder units 2 per cycle produce power by activating the assigned ignition devices 3 than would be required for the currently present power demand, and preferably thereby to control at least one actuator of the internal combustion engine 1 for reducing the power produced by a piston-cylinder unit 2 with activated ignition device 3 after the second number N2 of cycles of the internal combustion engine 1, for a third number N3 of cycles of the internal combustion engine 1, depending on a currently present power demand, to have so many piston-cylinder units 2 produce power per cycle of the internal combustion engine 1 by activating the assigned ignition devices 3 that a torque of the crankshaft 5 is obtained, which is adapted to the currently present power demand.

(10) The engine control 4 is further configured to switch from the first operating mode to the second operating mode when a predetermined first criterion is met—preferably when a change in the power demand and/or its rate of change exceeds a predetermined limit value. Thereby, it is preferably provided that the engine control 4 is configured to change from the second operating mode to the first operating mode depending on the fulfillment of a predeterminable second criterion.

(11) The engine control 4 is configured to repeat the sequence of the first number N1, second number N2 and third number N3 of cycles of the internal combustion engine 1 in the second operating mode.

(12) The engine control system 4 is configured so as to carry out activation of at least one actuator in the second operating mode for reducing the power produced by a piston-cylinder unit 2 with activated ignition device 3 by lowering the boost pressure in the intake stroke 6, in this case by means of an actuator: in the form of a throttle valve 10 arranged in or in front of the intake stroke 6, wherein preferably a boost pressure-dependent limit value is provided for a minimum closed position of the throttle valve 10, and it is provided that the throttle valve 10 is actuated in such a way that a closed position of the throttle valve 10 remains at or above the limit value, and/or in the form of a blow-by valve 11 of a turbocharger 12 arranged in or in front of the intake stroke 6.

(13) The engine control 4 is configured so as to carry out controlling of at least one actuator for reducing the power produced by a piston-cylinder unit 2 with activated ignition device 3 in the second operating mode, by adjusting the ignition timing to late for at least one of the piston-cylinder units 2 with activated ignition device 3.

(14) The engine control 4 is configured so as not to reduce, in the second operating mode for the third number N3 of cycles of the internal combustion engine 1, the power produced by a piston-cylinder unit 2 with activated ignition device 3.

(15) The engine control 4 is configured so as to activate all ignition devices 3 in the second operating mode for the second number N2 of cycles of the internal combustion engine 1, and/or to carry out an adjustment of the ignition timing to late for a plurality, preferably for all, of the piston-cylinder units 2 with activated ignition device 3.

(16) FIG. 2 shows the internal combustion engine 1 of FIG. 1 as part of a genset 13 with an electrical generator 14 mechanically coupled to the crankshaft 5 of the internal combustion engine 1. The power demand on the internal combustion engine 1 results from a load which can be connected or is connected to the electrical generator 14 via a switching device 16 (shown here in the form of a three-phase power grid 17).

(17) Those events that lie along a line in the different graphs of FIGS. 3 and 4, as viewed vertically, take place at the same time.

(18) FIG. 3 shows how the second operating mode is performed during load shedding in a first embodiment.

(19) In the top graph “load over time” of FIG. 3, the power demand on the internal combustion engine 1 is first at a certain level, and the engine control 4 is in the first operating mode, in which it is configured so as to leave so many ignition devices 3 deactivated per cycle of the internal combustion engine 1, depending on the power demand currently present, that the power of those piston-cylinder units 2 whose ignition devices 3 are activated, results in a torque of the crankshaft 5 of the internal combustion engine 1 adapted to the power demand currently present. Depending on the power demand, the number of deactivated ignition devices 3 may be zero or greater than zero.

(20) At a certain point in time, the power demand on internal combustion engine 1 suddenly collapses, which is shown in the graph “load over time” by a sudden reduction of the load.

(21) In the present embodiment, the occurrence of the change in power demand exceeding a predetermined limit value (either measured directly or detected via an increase in rotational speed) triggers a change in the operating mode of the engine control 4 from the first operating mode to the second operating mode.

(22) In this second operating mode, such a number of ignition devices 3 are first deactivated for a number N1 of cycles that the increase n in rotational speed is limited (this produces the first maximum in the graph “rotational speed n over time”). After the number N1 of cycles, the engine control 4 allows more piston-cylinder units 2 per cycle to provide power by activating the assigned ignition devices 3 for a second number N2 of cycles than would be required for the currently present power demand. Although this results in a renewed increase in rotational speed n, the risk of uncontrolled deflagration is reduced. The number N3 is selected to be zero in this embodiment.

(23) This sequence of N1 cycles and N2 cycles is repeated three times here as an example. Then, two sequences of N1 cycles and N2 cycles follow, in each of which fewer ignition devices 3 are deactivated during the N1 cycles of a sequence than during the N1 cycles of the immediately preceding sequence. The numbers N1 and N2 of cycles do not change in this embodiment. Then the engine control 4 changes again to the first operating mode.

(24) The graphs “ignition timing over time”, “actuators over time” and “boost pressure over time” show optional flanking measures (these do not all have to be carried out together, although this is imaginable) for controlling at least one actuator to reduce the power produced by a piston-cylinder unit 2 with activated ignition device 3, in this case adjusting the ignition timings to late and/or influencing the boost pressure by changing the position of a throttle valve and/or actuating a blow-by valve. Due to the lowering of the boost pressure, the number of deactivated ignition devices 3 in the first operating mode before and after the changes in the power demand can be the same (not mandatory), e.g. equal to zero, since the lower load is taken into account by the lowered boost pressure.

(25) FIG. 4 shows how, in a load shedding in a second embodiment, the second operating mode is carried out, wherein here, in contrast to the embodiment of FIG. 3, the numbers N1 and N2 of cycles are not necessarily kept constant, but are changed over time, e.g. depending on the at least one signal of the signal detection device 9.

LIST OF REFERENCE SIGNS

(26) 1 internal combustion engine 2 piston-cylinder unit 3 ignition device 4 engine control 5 crankshaft 6 intake stroke 7 exhaust stroke 8 supply device for gas-air mixture 9 signal detection device 10 throttle valve 11 blow-by valve 12 turbocharger 13 genset 14 electrical generator 15 catalyst 16 switching device 17 power grid N.sub.1 first number of cycles N.sub.2 second number of cycles N.sub.3 third number of cycles n crankshaft rotational speed