Control of an internal combustion engine in transient operating mode

Abstract

The present invention provides a method for avoiding knocking in an internal combustions engine, preferably in a gasoline engine with a high compression ratio and a variable valve train which is able to perform EIVC, by injecting a non-combustible fluid into the intake port and/or in the cylinder during a transient operating mode.

Claims

1. A method for controlling an internal combustion engine with at least one cylinder, at least one non-combustible fluid injector configured to inject a non-combustible fluid into the internal combustion engine and at least one controller, comprising controlling the injection device to inject the non-combustible fluid into the internal combustion engine when the internal combustion engine operates in a transient operating mode, and detecting and/or predicting the start and the duration of the transient operating mode, and activating the injector to inject non-combustible fluid when the start of the transient operating mode is determined and/or at the predicted start of the transient operating mode.

2. The method according to claim 1, further comprising controlling a variable valve train of the internal combustion engine configured to vary a valve opening/closing timing, wherein the variable valve train is configured to switch the intake valve closing timing from a first crank angle to a second crank angle, with the second crank angle being larger than the first crank angle; or wherein the variable valve train is configured to switch the intake valve closing timing from a third crank angle to a fourth crank angle, with the fourth crank angle being smaller than the third crank angle.

3. The method according to claim 1, further comprising controlling a variable valve train configured to vary an amount of internal residual gas from a first residual gas value to a second residual gas value, wherein the second residual gas value is larger than the first residual gas value.

4. The method according to claim 1, further comprising injecting water during a switching period during which it is switched from or to an early or late intake valve closing timing.

5. The method according to claim 1, further comprising decreasing an amount of injected non-combustible fluid from a first combustion cycle of the transient operating mode to a subsequent combustion cycle of the transient operating mode.

6. The method according to claim 1, further comprising decreasing an injection period of non-combustible fluid from the first combustion cycle of the transient operating mode to a subsequent combustion cycle of the transient operating mode.

7. The method according to claim 1, wherein the controller splits the total amount of the injected non-combustible fluid and injects it over a plurality of multiple injections.

8. The method according to claim 7, wherein the controller decreases the number of multiple injections of the non-combustible fluid from the first combustion cycle of the transient operating mode to a subsequent combustion cycle of the transient operating mode.

9. The method according to claim 7, wherein the controller decreases the injection period of each injection of the multiple in-jections of the non-combustible fluid from the first combustion cycle of the transient operating mode to a subsequent combustion cycle of the transient operating mode.

10. The method according to claim 1, further comprising increasing the ignition energy of the spark ignition from a predefined first ignition energy value to a predefined second energy value when injection of non-combustible fluid is performed.

11. The method according to claim 10, further comprising decreasing the predefined second ignition energy value of the spark ignition from the first combustion cycle of the transient operating mode combustion cycle of the transient operating mode.

12. The method according to claim 10, further comprising increasing the predefined ignition energy of the spark ignition by providing a predefined longer spark duration or by providing a predefined number of multiple spark ignitions.

13. A control device for an internal combustion engine with at least one cylinder and at least one non-combustible fluid injector configured to inject a non-combustible fluid into the internal combustion engine, wherein the control device is configured to: control the injection device to inject the non-combustible fluid into the internal combustion engine when the internal combustion engine operates in a transient operating mode; detect and/or predict the start and the duration of the transient operating mode; and activate the injector to inject non-combustible fluid when the start of the transient operating mode is determined and/or at the predicted start of the transient operating mode.

14. The control device of claim 13, further comprising an internal combustion engine with at least one cylinder and at least one non-combustible fluid injector configured to inject a non-combustible fluid into the internal combustion engine.

15. A non-transitory computer program product operable for implementing a method for controlling an internal combustion engine with at least one cylinder, at least one non-combustible fluid injector configured to inject a non-combustible fluid into the internal combustion engine and at least one controller, the computer program product comprising a non-transitory storage medium executable by a processor to perform the program steps of: controlling the injection device to inject the non-combustible fluid into the internal combustion engine when the internal combustion engine operates in a transient operating mode, and detecting and/or predicting the start and the duration of the transient operating mode, and activating the injector to inject non-combustible fluid when the start of the transient operating mode is determined and/or at the predicted start of the transient operating mode.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 depicts a schematic view of a cylinder of an internal combustion engine.

(2) FIG. 2 shows a schematic view of a water injection device.

(3) FIG. 3 illustrates a diagram with a schematic trend of fuel consumption as a function of water/fuel ratio.

(4) FIG. 4 shows a schematic valve angle diagram with two different intake valve angles.

(5) FIG. 5 depicts a signal-time-diagram with a schematic trend of air mass and intake valve closing.

(6) FIG. 6a schematically shows one of different intake valve curves dependent on the variabilities of the intake valve train.

(7) FIG. 6b schematically shows one of different intake valve curves dependent on the variabilities of the intake valve train.

(8) FIG. 6c schematically shows one of different intake valve curves dependent on the variabilities of the intake valve train.

(9) FIG. 6d schematically shows one of different intake valve curves dependent on the variabilities of the intake valve train.

(10) FIG. 7a illustrates by means of a flow chart examples of a sequence of method steps.

(11) FIG. 7b illustrates by means of a flow chart examples of a sequence of method steps.

(12) FIG. 8a schematically shows one of different valve strategies for trapping residual gas in the cylinder.

(13) FIG. 8b schematically shows one of different valve strategies for trapping residual gas in the cylinder.

(14) FIG. 8c schematically shows one of different valve strategies for trapping residual gas in the cylinder.

(15) FIG. 8d schematically shows one of different valve strategies for trapping residual gas in the cylinder.

(16) FIG. 9a depicts one of examples of different injection strategies for a split injection of water.

(17) FIG. 9b depicts one of examples of different injection strategies for a split injection of water.

(18) FIG. 9c depicts one of examples of different injection strategies for a split injection of water.

(19) FIG. 9d depicts one of examples of different injection strategies for a split injection of water.

DESCRIPTION OF EMBODIMENTS

(20) FIG. 1 depicts an exemplary cylinder 100 of an otherwise unspecified internal combustion engine, which may have more than one cylinder 100. The engine may, for example, have two, three, four, six, eight or less/more cylinders 100. The cylinder 100 comprises a combustion chamber 1 in which a piston 2 with a connecting rod 3 is disposed allowing it to travel. The connecting rod 3 is connected to a crankshaft (not depicted) that can be a crankshaft as known.

(21) An (air) intake port 4 with an intake valve 6 as well as an exhaust port 5 with an exhaust valve 7 are connected to the combustion chamber 1. Ambient air is drawn into the combustion chamber 1 through the intake port 4. Exhaust gases are discharged from the combustion chamber 1 via the exhaust port 5. A spark ignition unit 12 comprising a spark plug 12a and an ignition coil 12b is attached to the internal combustion engine. The spark ignition unit 12 preferably offers a variable spark duration or multi-spark ignition. The internal combustion engine (or briefly: “combustion engine” or “engine”) may have one or more spark ignition units 12. Preferably, it has at least one spark ignition unit(s) 12 per cylinder 100. The spark plug 12a as well as a fuel injector 8, or at least parts thereof, are connected to the inside of the combustion chamber 1 so that a spark and fuel can be introduced/injected into the combustion chamber 1. The high-pressure fuel supply of the fuel injector 8 is not depicted. The fuel injector 8 may preferably be a direct fuel injector 8. Further, the fuel injector 8 may preferably be an electrohydraulic fuel injector or a piezoelectric fuel injector. The internal combustion engine may be equipped with one or more intake valve phasing actuator(s) 10 and/or one or more exhaust valve phasing actuator(s) 11. The intake valve phasing actuator 10 is preferably used for realizing early intake valve closing. The exhaust valve phasing actuator 11 is preferably used for adjusting residual gas and/or for varying an exhaust valve opening timing. The valve phasing actuators 10, 11 are preferably hydraulic actuators or electric actuators. Other means for controlling the intake and exhaust valve opening/closing timings may be applied in addition or alternatively. Even further, if not otherwise indicated in the aspects described below, the herein claimed subject-matter may also entail an internal combustion engine which does not have an intake/exhaust valve opening/closing timing means.

(22) Further, a non-combustible liquid injector 9 is connected to the intake port 4 of the cylinder 100. Since most preferably the liquid to be injected is water, even though other liquids having a high evaporation enthalpy may be used as well, the term “water injector” is used as one specific example for a non-combustible liquid injector 9. The water injector 9 may be a low-pressure injector with an injection pressure of up to 3 bar or a high-pressure injector with an injection pressure of more than 3 bar. As an alternative to the water injector 9 connected to the intake port 4 (as shown in FIG. 1), or in addition thereto, one or more water injectors 9 may be connected to the cylinder wall 14 of one cylinder 100 to inject water directly into the combustion chamber 1.

(23) FIG. 1 further shows a controller 13 which is electrically connected to the spark ignition unit 12, the valve phasing actuators 10, 11, the direct fuel injector 8 and the water injector 9. The controller 13 controls the multiple units/injectors/actuators. The controller 13 may, for example, be the engine control unit (ECU). The controller 13 may also be any other control unit, and signal line connections between the controller 13 and the controlled units may differ from the example of FIG. 1. For example, there may be a plurality of controllers 13 which may control subgroups of the controlled units, e.g. one controller 13-1 may control only fuel injectors, another controller 13-2 may control only water injectors 9 and so on. Even further, if there is a plurality of controllers 13, these controllers 13 may be interconnected with each other hierarchically or in another way.

(24) Further, pressure sensors which are not shown may be disposed in the combustion chamber wall 14 so that the pressure within the combustion chamber 1 can be measured. Measuring the pressure within the combustion chamber 1 can support a feedback control of the amount of water to be injected. For example, the amount of water to be injected by the injector 9 may be determined by a feedforward control within the controller 13 in accordance with predefined internal combustion engine states. E.g., the feedforward control may use a map, a table or the like to determine the amount of water to be injected depending on the engine state, which may be defined by parameters and which are used to look up the amount of water to be injected. The parameters may be the load of the engine and the rotational speed based on which the amount of water may be read from the lookup map, table or the like. The amount of water to be injected which was set by the feedforward control may, subsequently, be corrected based on the real pressure within the combustion chamber 1. This may include that the feedforward control assumes that the combustion phase of the combustion cycle is “on time”, i.e. neither ahead of the timing nor delayed, and that this assumption may not correspond to the real conditions because the combustion phase of the combustion cycle may be delayed. Such a deviation between the target timing and the real timing of the combustion phase may then be compensated by a feedback control which is used to correct/adapt the water amount determined by the feedforward control. For example, the timing may be determined by comparing a target pressure at a specific point within the combustion cycle, e.g. the point of 50% total burn rate (MFB50), with the real pressure measured by the pressure sensor at this point. The point may be determined by the crank angle value or the like. The technical benefit of the feedback control is that especially in case of a delayed timing water can be saved which has to be carried in a water tank 15 of the vehicle.

(25) FIG. 2 shows a water injection device 101 of an aspect in which the non-combustible fluid is water. The water injection device 101 has a water tank 15, a water pump 16 which can supply water from the water tank 15 to the water injector 9 via a water pipe/tube 17. The water injector 9 and the water pump 16 are electrically connected with the controller 13 via signal lines 18. The controller 13 may, inter alia, control the injection pulse width/time, the injection pressure and/or the injection timing. For example, the controller 13 may be adapted to vary the injection pulse width/time so that the amount of water being injected into the engine may be varied. As described above, the water injector 9 may be arranged so that water may be injected directly into the combustion chamber 1. Alternatively or additionally, the water injector 9 may be connected to the intake port 4 so that water may be injected into the stream of air sucked into the combustion chamber 1. The water may further be injected so as to form a mixture of air and water.

(26) The water injection device 101 according to FIG. 2 is a schematic example which may include further non-shown and/or optional members, such as a fluid rail for connecting multiple water injectors 9, such as sensors for temperature, pressure and the like, such as further signal lines, such as further water lines/tubes for recirculation of water or the like, such as valves, and/or such as further actuators, pumps and the like.

(27) The diagram in FIG. 3 illustrates a schematic trend of fuel consumption as a function of water/fuel ratio. At high loads, e.g. at rated power, it may be difficult to run a spark ignited gasoline combustion engine with an optimized combustion phasing because the earliest possible ignition angle is limited by engine knocking. The here described water injection into the intake port 4 and/or in the cylinder 100 during the intake stroke leads to a drop of the gas temperature in the cylinder 100 which allows for an optimized combustion phasing and avoids enrichment of the air-fuel mixture. Therefore, a significant reduction of the fuel consumption is achievable with the claimed water injection, especially at high engine loads.

(28) FIG. 4 schematically shows a switching of the intake valve crank angle from a first intake valve angle IVA.sub.1 to a second intake valve angle IVA.sub.2 (from left to right part of FIG. 4), whereas IVA.sub.1 represents an early intake valve closing and IVA.sub.2 represents an intake valve closing which may be applied when a higher volumetric efficiency is required (no EIVC). The switching may for example be carried out when changing from a low or mid load of the engine to high load. The exhaust valve angle EVA stays constant in this schematic diagram but may also be changed. The switching of the intake valve angle as shown in FIG. 4 can cause a rise of the compression end temperature in the cylinder 100 which could lead to undesirable knocking. In such a situation, the here described controlled water injection during the valve angle switching suppresses the knocking. In other words, the method of suppressing knocking by water injection can beneficially applied, e.g., in the scenario during a switching of the (intake) valve angle closing/opening timing. One example for such an application scenario during the valve angle switching is shown by FIG. 4, and the water injection may be performed until the end of the switching period, i.e. until the switching of the valve timing is completed.

(29) FIG. 5 depicts a signal-time-diagram with a schematic trend of the air mass (solid line) and the intake valve closing timing (dotted line). When the intake valve closing timing changes to a larger crank angle the air mass in the cylinder 100 upsurges during the valve timing change/switching. One can see an overshoot of the air mass before the intake valve closing reaches its final value. The event of that overshoot usually corresponds to an incidence of knocking, because the rapidly increasing air mass leads to a rise in the cylinder temperature (not depicted). This knocking can be prevented by the here described water injection method, and the water injection may be performed until the air flow variation has decreased or the air flow is stable again.

(30) The FIGS. 6a-d illustrate examples for intake valve curves caused by different variabilities in the intake valve train to realize an early intake valve closing. The presented method of injecting water during a switching of the valve timing can also be applied within an engine providing the following switching/changing options. FIG. 6a shows a change in the phasing of the intake valve 6, which results in an earlier intake valve closing but also in an earlier intake valve opening and therefore in a larger valve overlap of the intake 6 and the exhaust valve 7. Dependent on the pressure drop between exhaust 5 and intake port 4, the larger valve overlap may lead to an unwanted increase of internal residual gas. For de-throttling at part load a high amount of residual gas may be useful but at light load it may lead to unstable combustion. Therefore, using a cam phaser may enable an early intake valve closing only in a limited part of the engine map and a throttle plate may be still necessary to control the load of the gasoline engine. As a further step to a higher variability, FIG. 6b shows a change in the intake valve lift besides the change in the intake valve phasing. Such a valve train may allow for an early intake valve closing in a wide range of the engine map and is able to control the load and the residual gas by changing the valve lift. FIG. 6c depicts intake valve curves of an intake valve train which includes two valve profiles with different valve lifts (IV.sub.1, IV.sub.2) in which IV.sub.2 offers the additional possibility to vary the length of the intake valve opening time. At high load the valve curve IV.sub.1 may be in use whereas at part and low load the valve train may be switched to IV.sub.2. Finally, in FIG. 6d a fully variable intake valve train is depicted, which may allow for varying the valve timing, the valve lift and the length of the valve opening time.

(31) The flow chart of FIG. 7a shows an example for a possible sequence of steps when a transient operating mode was detected. The transient operating mode may be detected by the controller 13 based on a change of the load of the engine and/or the rotational speed. For example, the controller 13 may detect that a change rate (a variation over time) of the load and/or the rotational speed exceeds a predefined threshold which is interpreted as a transient operating mode. The duration of the transient operating mode may be defined to be the period during which the change rate is over the threshold value. Assuming that the transient operating mode was detected (see step S100 in FIG. 7a), FIG. 7a now shows an application scenario of the presented method which includes the water injection during a valve timing switching, for example a change from a miller cycle to a non-miller cycle or the like. The detection of a switching period may be performed, as one possible example, by comparing the actual value of the valve timing, e.g. expressed via a crank angle or the like, with the input target value (cf. FIG. 5). If the two values differ from each other or if they differ by more than a predetermined threshold, it may be detected, e.g. by the controller 13, in step S101 and above described comparison that a switching period has started and water injection is initiated in step S102. Otherwise, step S103, the water injection may not be initiated. However, in other examples of the here described method, water may anyways be injected, for example, if water shall always be injected during a transient operating mode, i.e. irrespective whether a switching of the valve timing takes place or not. After step S103, a comparison of the actual valve timing value and the target value is again carried out and if the difference of the values is not below the threshold, switching is detected to continue. Otherwise, the end of the switching period is detected or predicted to be close and the water injection is stopped in step S104.

(32) The above example of FIG. 7a shows the example that water is injected during a valve switching action. However, water injection may alternatively or additionally be carried out during other conditions, such as when a rapid acceleration (an acceleration above a predefined threshold) in an engine with internal EGR is detected or during a change of the amount of residual gas in the cylinder 100. Further, the switching period may be detected differently compared to step S101, e.g. based on engine performance parameters or the like.

(33) The flow chart of FIG. 7b shows a further example for a sequence of steps of the present method. Starting with a stationary operating point and a determined intake valve closing IVC.sub.s (S200), the controller 13 checks whether the pedal-value gradient ΔPV is larger than a threshold value ΔPV.sub.TH. If this is the case, the controller 13 determines that a transient operating mode (TOM) was detected and predicts the change in the intake valve closing timing ΔIVC.sub.p (S201). In the next step S202, the switching of the intake valve starts. If ΔIVC is larger than a threshold value ΔIVC.sub.TH, the controller 13 activates water injection (S204). If ΔIVC is smaller than the threshold value ΔIVC.sub.TH the water injection will not be activated by the controller (S203). As long as the actual intake valve closing angle does not reach the target intake valve closing IVC.sub.s+ΔIVC.sub.p the transient operating mode TOM is activated and water is injected if the predicted change of the intake valve closing ΔIVC.sub.p was larger than the threshold ΔIVC.sub.TH. When the intake valve closing reaches the target value IVC.sub.s+ΔIVC.sub.p the controller 13 determines the end of intake valve switching (S205) by means of an optional knocking sensor (not depicted) which is electrically connected to the controller 13, whether knocking occurs or not. If knocking occurs, the controller 13 performs water injection (S207), if not, no water will be injected.

(34) In the above example, it should be understood that some steps may be left out and/or repeated. For example, the method may only include the steps of detecting whether a transient operating mode is present and activating water injection which means that only steps S200, and S204 would be carried out. Further, the detecting of a transient operating mode may not only be carried out as described in connection with step 201 above. Instead of the pedal value or in addition thereto, other indicators for a transient operating mode may be used, such as speed or acceleration of the vehicle, engine load or engine rotational speed, and the like. For example, several checking steps may be carried out subsequently or in parallel to determine whether a transient operating mode has occurred.

(35) Further, the steps after S205 may be left out, too. Even further, the detection of a valve closing timing switching may be carried out in a different way. For example, in S202 it may be detected by a comparison that the target valve switching timing and the present valve switching timing are different from each other which may be interpreted as the beginning of a switching period and the water injection step S204 may be started (see e.g. FIG. 7a). In the same way it may be determined without a knocking sensor whether the switching period is still active, and, as soon as the switching period is detected to end, the water injection may be stopped.

(36) Further, instead of or in combination with the water injection during early/late intake valve closing switching as described above, the water injection step may include to detect whether an acceleration above a pre-set threshold is detected especially when the engine has an internal EGR system, and the water may be injected during the rapid acceleration. In this case, the corresponding steps of FIG. 7 (especially the steps between S201-S205) would be replaced or additional steps would be added.

(37) The water injection may also be varied which is further described below.

(38) The FIGS. 8a-d schematically depict different intake and exhaust valve curves to realize different strategies of trapping residual gas in the cylinder 100. FIG. 8a shows a valve timing with an early intake valve opening during the exhaust stroke which leads to a large valve overlap before gas exchange top dead center (GTDC). During this large valve overlap exhaust gas is pressed into the intake manifold, as long as the exhaust pressure is higher than the intake pressure. FIG. 8b shows a valve timing in which the exhaust valve 7 closes late during the intake stroke which leads to a large valve overlap before gas exchange top dead center (GTDC). This late exhaust valve closing causes that exhaust gas is drawn out of the exhaust port 5 back into the cylinder 100. In FIG. 8c a valve timing is depicted which shows a second opening of the exhaust valve 7 during the intake stroke, so that exhaust gas is re-aspirated into the cylinder 100. In FIG. 8d the residual gas is trapped in the cylinder 100 by an early closing of the exhaust valve 7 (e.g. 90 degrees before GTDC) and a late opening of the intake valve 6 (e.g. 90 degrees after GTDC), which causes a negative valve overlap. Whereas the valve timing depicted in FIG. 8a results in the coolest residual gas temperature, the valve timing shown in FIG. 8d leads to the hottest residual gas temperature of all shown valve timing strategies. Responsible for that are the wall heat losses of the gas in the exhaust 5 and the intake port 4, which are the highest when the exhaust gas flows back from the exhaust port 5 to the intake port 4 and the lowest when no gas flow takes place. In spark ignited gasoline engines the valve strategies schematically depicted in FIGS. 8a and 8b may be preferably used, which may result in moderate residual gas temperatures at low load. Nevertheless, using the valve overlap schematically depicted in FIG. 8b at mid load, which may be useful to reduce pumping losses, knocking may appear. Particularly in transient operating mode the risk of knocking may be present because of the delayed response behaviour of the valve actuator 10, 11. Therefore, the water injection during the transient operating mode as described is an effective measure to suppress knocking in that situation.

(39) FIGS. 9a-d illustrate four possible examples of a water split injection during the transient operating mode. FIG. 9a shows the injection signals WI of four and two injections respectively with the same injection period. The multiple injections take place during the opening time of the intake valve IV because the examples in FIG. 9a and FIG. 9b represent a port water injection. Since in the first cycle of the transient operating mode a higher amount of water may be needed, the number of injections may be reduced from four injections in the first cycle to two injections in a subsequent cycle x. In FIG. 9b the same injection pattern as in FIG. 9a is shown for the first cycle of the transient operating mode. Instead of reducing the number of injections FIG. 9b shows four injections with a reduced injection period to decrease the total amount of injected water in a subsequent cycle x. In another aspect of the present application the injection periods in the first and in a subsequent cycle may have different length, e.g. a first long injection period followed by multiple shortened injection periods or vice versa. Furthermore, in a subsequent cycle the number of injections and the injection period may be reduced. The number of injections may vary from 1 to 5 and the injection period may be in a range of 0.5 ms to 5 ms. The previously described injection patterns may also be realized with a direct water injection DWI. Additionally, a direct water injection DWI allows for multiple water injections in the compression stroke, as shown in FIGS. 9c and 9d. Parallel to the examples shown in FIG. 9a and 9b, in FIG. 9c, the number of injections is halved in a subsequent cycle x, whereas FIG. 9d shows a reduced injection period for an equal number of injections as in the first cycle. The former described variations of the injection period and the number of injections may also be realized when the water is injected during the compression stroke. It should be noted that increasing the first water injection period, and then gradually decreasing the injection period beneficially stabilizes the water supply to the cylinder 100. Splitting the water injection into multiple injection actions during one combustion cycle, may promote the evaporation of the water which avoids adhesion to the cylinder wall 14. If the amount of water is determined in advance, the knocking suppression and the stability of the combustion can be ensured well, and, if the described feedback control of the amount of water is used in addition, it can be ensured even better. The combustion stability can be further improved if the ignition energy during the water injection according to the here described method is increased. Energy can however be saved if the ignition energy is gradually decreased from a first ignition to the subsequent ones.

(40) It is summarized that the present subject-matter especially enables an improved suppression of knocking in internal combustion engines by water injection during transient engine operating modes. For example, a preferred aspect covers a combination of a miller cycle engine with water injection and water injection during the early or late intake valve closing switching. Further, during a rapid acceleration, the water injection is used especially when the engine has an internal EGR system.

(41) While the above describes a particular order of operations performed by certain aspects and examples, it should be understood that such order is exemplary, as alternatives may perform the operations in a different order, combine certain operations, overlap certain operations, or the like. References in the specification to a given aspect indicate that the aspect described may include a particular feature, structure, or characteristic, but every aspect may not necessarily include the particular feature, structure, or characteristic. The features which are described herein and which are shown by the Figures may be combined. The herein described and claimed subject-matter shall also entail these combinations as long as they fall under scope of the independent claims.

(42) It should again be noted that the description and drawings merely illustrate the principles of the proposed methods, devices and systems. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the claimed subject-matter and are included within its spirit and scope.

(43) Furthermore, it should be noted that steps of various above-described methods and components of described systems can be performed by programmed computers. Herein, some embodiments are also intended to cover program storage devices, e.g., digital data storage media, which are machine or computer readable and encode machine-executable or computer-executable programs of instructions, wherein said instructions perform some or all of the steps of said above-described methods. The program storage devices may be, e.g., digital memories, magnetic storage media such as a magnetic disks and magnetic tapes, hard drives, or optically readable digital data storage media. The embodiments are also intended to cover computers programmed to perform said steps of the above-described methods.

(44) In addition, it should be noted that the functions of the various elements described herein may be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software. When provided by a processor, the functions may be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which may be shared. Moreover, explicit use of the term “processor” or “controller” should not be construed to refer exclusively to hardware capable of executing software, and may implicitly include, without limitation, digital signal processor (DSP) hardware, network processor, application specific integrated circuit (ASIC), field programmable gate array (FPGA), read only memory (ROM) for storing software, random access memory (RAM), and non-volatile storage. Other hardware, conventional and/or custom, may also be included.

(45) Finally, it should be noted that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the claimed subject-matter. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudo code, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

(46) Again summarizing, the present subject-matter/method offers an effective concept to avoid engine knocking in a transient operating mode by injecting a non-combustible fluid, which is preferably a liquid and most preferably water. The method enables high compression ratios even in charged gasoline engines without drawbacks regarding acceleration response and fuel consumption in transient driving situations.

REFERENCE SIGNS LIST

(47) 1 combustion chamber 2 piston 3 connecting rod 4 intake port 5 exhaust port 6 intake valve 7 exhaust valve 8 fuel injector 9 non-combustible fluid/water injector 10 intake valve phasing actuator 11 exhaust valve phasing actuator 12 spark ignition 12a spark plug 12b ignition coil 13 controller 14 cylinder wall 15 (water) tank 16 (water) pump 17 (water) pipe 100 cylinder 101 (water) injection device ISFC indicated specific fuel consumption GTDC gas exchange top dead center ITDC ignition top dead center BDC bottom dead center IV intake valve EV exhaust valve IVA intake valve angle EVA exhaust valve angle IVC intake valve closing IVL intake valve lift WI water injection PWI port water injection DWI direct water injection TOM transient operating mode