JP7225439B2 - CONTROL DEVICE AND CONTROL METHOD OF IGNITION DEVICE WITH AUXILIARY COMBUSTION CHAMBERS UNDER FUEL SUPPLY OF INTERNAL COMBUSTION ENGINE - Google Patents

Description

The present invention relates to a control unit and method for controlling an ignition device with a fueled auxiliary combustion chamber of an internal combustion engine, the control unit injecting a reactive jet flowing from the auxiliary combustion chamber into the main combustion chamber. control power.

In order to increase the combustion efficiency of an internal combustion engine, it is beneficial to use an ignition device with a secondary combustion chamber under fuel supply. The high ignition energy of such igniters is provided by the precombustion occurring in the subcombustion chamber. This precombustion is initiated by injecting a small amount of fuel into the subcombustion chamber and thereby igniting the resulting air-fuel mixture in the chamber. Since the sub-combustion chamber is connected to the main combustion chamber through a fine orifice, combustion in the sub-combustion chamber produces a reactive jet, and this jet flows from the sub-combustion chamber into the main combustion chamber, of air-fuel mixture. This reactive jet typically spreads throughout the main combustion chamber to provide multiple ignition spots that enable reliable ignition of even very lean air/fuel mixtures.

However, there are several barriers that can compromise the reliability of subcombustion chamber ignition over the life of the internal combustion engine. For example, the use of rich gas mixtures and high temperatures in the subcombustion chamber can lead to coking of the injector tip face or subcombustion chamber orifice. Combustion residue build-up on the injector tip can even lead to deterioration of the injected fuel flow, which in turn can result in a weakening of the reactive jet produced by secondary combustion chamber combustion. For this reason, it would be preferable to be able to detect the injection force of the reactive jet. This makes it possible to introduce countermeasures against deterioration of the injected fuel flow. In addition, injection power is also affected by environmental conditions of the engine. For example, under cold conditions and low loads, the cold sub-combustion chamber body will steal a lot of energy from the sub-chamber fuel and jets, thus hindering the stability of the sub-combustion chamber combustion. By controlling the injection power, it is possible to improve the subcombustion chamber combustion even under the difficult environmental conditions mentioned above.

Conventionally, monitoring jet power requires complex and expensive means/apparatus, especially if the monitoring process involves identifying a precise value representing the thermal energy contained in the jet.

EP 3 392 487 A1 discloses a control method for a precombustion chamber gas engine used as a power generating engine. The force of the torch jet/reactive jet injected from the subcombustion chamber into the main combustion chamber is a function of the difference or ratio of the pressure in the subcombustion chamber to the pressure in the main combustion chamber. This means that it is necessary to detect the pressure in the main combustion chamber as well as the pressure in the subcombustion chamber in order to establish a value representing the torch force. Although semi-permanent pressure sensors into the primary combustion chamber are available, equipping the secondary combustion chambers with pressure sensors remains a difficult task, resulting in significant labor and expense. Furthermore, due to the limited space in the sub-combustion chamber, only extremely small pressure sensors with lower accuracy, less durability and less durability than commonly used pressure sensors can be installed.

Patent Document 1: European Patent Publication No. 3392487

In view of the above, the present invention provides a control system to ensure reliable operation of the secondary combustion chamber ignition under all environmental conditions and to ensure this over the service life of the engine without adding mechanical complexity to the control unit. The object is to provide a unit and its method.

The above problems are solved by the subject matter of the independent claims. Preferred embodiments are also described by the dependent claims.

A control unit for controlling the internal combustion engine controls the injection force of the reactive jet flowing from the auxiliary combustion chamber into the main combustion chamber. Preferably, the control is performed using feedback control. As used herein, "reactive jet" is understood as a jet of hot fluid or fluid-like substance discharged/blown/pushed from the secondary combustion chamber through an orifice in the secondary combustion chamber into the primary combustion chamber. sea bream. This hot fluid is preferably gas produced by secondary combustion chamber combustion including combustion products such as free radicals, carbon monoxide and hydrocarbons. A "reactive jet" may also be understood as a (turbulent) flame jet escaping through an orifice from the secondary combustion chamber into the main combustion chamber.

The injection power of the reactive jet may be or include ignition energy of the reactive jet, e.g., thermal energy, kinetic energy and/or chemical energy stored in the combustion products of subcombustion chamber combustion. such as energy.

The term "control" consists of a feedback control of the injection force, which in particular comprises a target (preset) parameter representing the injection force and an actual/determined/measured current parameter representing the injection force. and adjustment of at least one parameter affecting subcombustion chamber combustion to eliminate differences between target (preset) parameters representing injection power and actual/current parameters representing injection power. shall include

An internal combustion engine (abbreviated "combustion engine", "engine") comprises at least one cylinder, at least one main combustion chamber (abbreviated "main chamber"), at least one intake port, and at least one main fuel It may consist of an injector, at least one determining means for detecting high frequency oscillations in the main combustion chamber, and at least one ignition device for igniting the air-fuel mixture in the main combustion chamber.

The ignition system may consist of a spark plug, a secondary combustion chamber fuel injector, and a secondary combustion chamber coupled to the primary combustion chamber via at least one orifice in the secondary combustion chamber wall.

The control unit may be arranged to determine the injection power of the reactive jet using at least one determining means configured to detect high frequency oscillations in the main combustion chamber. At least one determining means may be a pressure sensor and/or a knock sensor and/or a torque sensor. A high frequency vibration may be a vibration having a frequency above 500 Hz.

A reactive jet entering the main combustion chamber may induce a shock wave that spreads throughout the main combustion chamber. The higher the ignition energy of the reactive jet (the "injection force" described above), the greater the amplitude of the induced shock wave. In other words, the shock wave resulting from the entry of the reactive jet into the main combustion chamber may be used to establish a parameter representing injection power.

Shock waves induced by reactive jets that rapidly escape the secondary combustion chamber and spread throughout the main combustion chamber are detectable as pressure oscillations on the cylinder pressure signal. Accordingly, a cylinder pressure sensor commonly utilized to control combustion timing in internal combustion engines may be suitable for determining high frequency oscillations caused by jets entering the main combustion chamber. Due to its high natural frequency, piezoelectric pressure sensors can be used to measure dynamic pressure and minute pressure fluctuations. Alternatively, or in addition, the vibrations induced by the reactive jet can be evaluated using knock sensors commonly installed in various gasoline engines to detect noise vibrations in the structure itself due to knock vibration combustion. .

According to the findings of the inventors of the present application, the frequency corresponding to the shock wave induced by the reactive jet is covered by the frequency range of typical knock sensors, but exhibits a different deviation when compared to the knocking vibration. .

With a suitable evaluation of the knock sensor signal, it is therefore possible to distinguish between vibrations caused by reactive jets and vibrations caused by knocking. Alternatively, or in addition, a torque sensor may be utilized that also allows dynamic pressure measurements to be performed, for example with a frequency range of up to 10 kHz. For example, engine torque may be measured by a torque measuring flange fixed to the engine crankshaft.

Compared to other means of determination, the use of pressure sensors, especially when provided on more than one cylinder, has the advantage that the injection power of each cylinder can be adjusted individually and precisely. Knock sensors can also assign detected vibrations to different cylinders, but are less accurate than using individual pressure sensors for each cylinder. However, knock sensors are already available in engines, so the use of knock sensors is beneficial because evaluation efforts need only be devoted to accurately detecting vibrations induced by reactive jets. The torque oscillations detectable by the torque-measuring flange arise from all-cylinder pressure fluctuations and may be sufficient to control the average injection power.

Furthermore, the control unit may determine a characteristic parameter representing the injection force of the reactive jet on the basis of the detected high-frequency oscillations in the main combustion chamber. During engine operation, the ignition energy of the reactive jet is difficult to determine and therefore difficult to access for feedback control. May be used as a controlled variable or target value. As used herein, this "variable under control" may be the actual/current characteristic parameter and the target value may be the value according to the target (preset) characteristic parameter.

In order to establish/evaluate/calculate the characteristic parameters, the control unit analyzes the detected high-frequency vibrations in a given time range for a given number of engine cycles using a bandpass filter with a given frequency band. A filtered signal may thus be generated, and a characteristic parameter may be determined by determining the maximum absolute amplitude of the filtered signal for each of a predetermined number of engine cycles. Furthermore, the control unit may calculate an average value of the identified maximum absolute amplitudes, and the calculated average value may be a characteristic parameter.

The predetermined time range preferably starts 60° before top dead center firing (FTDC) and may end 60° after FTDC, most preferably starting at ignition timing and cranking at maximum cylinder pressure. May end at an angle. The bandpass filter may preferably have a frequency range of 1 kHz to 20 kHz, most preferably 4 kHz to 10 kHz. The number of filtered engine cycles may preferably range from 50 cycles to 500 cycles, most preferably from 100 cycles to 300 cycles.

Alternatively or additionally, the control unit utilizes a bandpass filter with a predetermined frequency band to filter by analyzing high frequency vibrations detected in a predetermined time range for a predetermined number of engine cycles. A processed signal may be generated, and a characteristic parameter is determined by identifying peak frequencies of the filtered signal for each of a predetermined number of engine cycles and calculating a distribution of the identified peak frequencies. Alternatively, the calculated distribution may be a characteristic parameter.

The predetermined time range preferably starts 60° before FTDC and may end 60° after FTDC, most preferably starting at ignition timing and ending at crank angle of maximum cylinder pressure. good. The bandpass filter may preferably have a frequency range from 1 kHz to 20 kHz, most preferably from 4 kHz to 10 kHz. The number of engine cycles to be filtered may preferably range from 50 cycles to 500 cycles, most preferably from 100 cycles to 300 cycles.

A frequency analysis may be performed for each of a predetermined number of engine cycles to identify the peak frequency of the filtered signal for each engine cycle, which may be the frequency with the highest intensity. Frequency analysis may preferably be a Fast Fourier Transform (FET) cycle. A peak frequency distribution may be calculated by counting the number of engine cycles at the specified peak frequency. If a knock sensor is used to detect high-frequency oscillations in the main combustion chamber, the frequency deviation may preferably be used as a characteristic parameter.

The control unit may adjust the injection power by adjusting/controlling the amount of fuel injected into the secondary combustion chamber and/or the injection timing of the secondary combustion chamber fuel injectors. Alternatively or additionally, the control unit may adjust the injection power by adjusting the injection timing of the main fuel injectors and/or the ignition energy supplied to the spark plugs. In this connection, the injection power is adjusted on the basis of the difference between the actual/current characteristic parameter and the predetermined target characteristic parameter. As used herein, actual/current characteristic parameters may be characteristic parameters calculated/determined based on currently measured engine cycles including high frequency vibrations. In order to determine the actual/current characteristic parameters with sufficient accuracy, it is necessary to record a certain number of engine cycles and determine the average value of the maximum absolute amplitude specified and/or the peak frequency distribution. Yes (see already established engine cycle number range). Predetermined target characteristic parameters may be determined during the test phase of the internal combustion engine in the manner described above and stored as characteristic curves or maps in the control unit.

As noted above, the injection power of the reactive jet can be defined as the ignition energy contained within the reactive jet that escapes from the secondary chamber into the primary chamber as a result of the combustion occurring within the secondary chamber. In other words, the heat release of the subcombustion chamber combustion creates the ignition energy of the reactive jet. In general, all combustion heat release is dependent on the injected fuel mass and the lower heating value of the fuel. As a result, the fuel mass contributing to subcombustion chamber combustion may be a suitable parameter to influence injection power. Injecting an increased amount of fuel into the subcombustion chamber may increase heat release within the chamber and increase injection power. In addition to the overall heat release of subcombustion chamber combustion, its heat release rate can also affect injection power. The heat release rate is dependent on the pressure and temperature conditions in the subcombustion chamber, which can be influenced, for example, by the injection timing of the subcombustion chamber fuel injectors, the injection timing of the main fuel injectors, and/or the ignition energy supplied to the spark plugs. may be relied upon. For example, increasing the electrical ignition energy supplied to the spark plug by the ignition coil results in an increased heat release rate, which in turn leads to increased pressure and temperature within the subcombustion chamber. As a result, increasing the electrical ignition energy supplied to the spark plug will increase the ignition energy of the reactive jet.

Further, the presently claimed subject matter includes at least one cylinder, at least one main combustion chamber, at least one intake port, at least one main fuel injector, and detecting high frequency vibrations within the main combustion chamber. and at least one control unit, which may exhibit the technical features described above, and a main fuel injector through a spark plug, a secondary combustion chamber fuel injector and at least one orifice in the secondary combustion chamber wall. and at least one ignition device with a secondary combustion chamber connected to the combustion chamber.

Furthermore, the presently claimed subject matter may encompass a method for controlling an internal combustion engine as described above, wherein the injection power of the reactive jet entering the main combustion chamber from the secondary combustion chamber is controlled by the control method described above. controlled by the unit.

The injection force may be represented by a characteristic parameter based on high frequency oscillations within the main combustion chamber sensed by determining means such as pressure sensors, knock sensors and/or torque sensors.

The method utilizes a bandpass filter with a predetermined frequency band to generate a filtered signal by analyzing high frequency vibrations detected over a predetermined time range for a predetermined number of engine cycles. Alternatively, for each predetermined number of engine cycles, the maximum absolute amplitude of the filtered signal may be determined, and the characteristic parameter determined by averaging the determined maximum absolute amplitudes.

Alternatively or additionally, the method utilizes a bandpass filter with a predetermined frequency band to analyze high frequency vibrations detected over a predetermined time range for a predetermined number of engine cycles, The filtered signal may be generated, and for each of a predetermined number of engine cycles, a peak frequency of the filtered signal is identified and the characteristic parameter is determined by calculating the distribution of the identified peak frequencies. may be

Next, the amount of fuel injected into the sub-combustion chamber and/or the injection timing of the sub-combustion chamber fuel injector may be adjusted based on the difference between the current characteristic parameter and a predetermined target characteristic parameter.

Alternately or additionally adjusting the injection timing of the main fuel injector and/or the ignition energy supplied to the spark plug (10a) based on the difference between the current characteristic parameter and the predetermined target characteristic parameter. may be

Further, the presently claimed subject matter is directed to a computer program product storable in a memory, containing instructions which, when executed by a computer or computing unit, cause the computer to perform the above-described method or aspects thereof; In some cases, it may encompass a computer readable (storage) medium containing instructions for causing a computer to carry out the method or aspects thereof.

In summary, the subject matter described herein relates to a control unit and method for controlling an ignition device with a fueled secondary combustion chamber of an internal combustion engine, wherein the control unit controls the primary combustion chamber from the secondary combustion chamber. It controls the injection force of the reactive jet flowing into the combustion chamber. The injection power may be the ignition energy of reactive jets produced by subcombustion chamber combustion. Since the ignition energy can be difficult to measure during engine operation, the alternative is to detect pressure oscillations in the main combustion chamber induced by the ignition energy of the reactive jets. The measurement may be performed by commonly used determining means such as pressure sensors, knock sensors, or the like. Based on the sensed pressure oscillations, specific parameters representing the injection force suitable for use as the variable under control in the feedback control may be calculated. This leads to a control concept that reduces complexity and makes it possible to ensure the efficiency and emissions limits of the internal combustion engine with high reliability over its service life.

The subject matter claimed herein will now be described in greater detail below on the basis of at least one preferred embodiment with reference to the accompanying exemplary schematic drawings.

1 schematically shows a cylinder of an internal combustion engine having an ignition device with a fueled secondary combustion chamber; FIG. FIG. 2 schematically shows an ignition device; An example of a cylinder pressure curve to be measured when using an ignition device with a conventional spark plug is illustrated. An example of a cylinder pressure curve to be measured when using an ignition device with a conventional spark plug is illustrated. 4 illustrates an example of a measured cylinder pressure curve when using an ignition device with a subcombustion chamber under fuel supply; 4 illustrates an example of a measured cylinder pressure curve when using an ignition device with a subcombustion chamber under fuel supply; Figures 4a-4f illustrate the effect of increasing the secondary combustion chamber fuel mass on the filtered cylinder pressure curve. 4 illustrates an example of a filtered cylinder pressure curve and maximum cylinder pressure amplitude for increasing amounts of fuel injected into the subcombustion chamber; 4 illustrates an example of a filtered cylinder pressure curve and maximum cylinder pressure amplitude for increasing amounts of fuel injected into the subcombustion chamber; 4 illustrates an example showing the correlation between the amount of fuel injected into the subcombustion chamber and the average maximum cylinder pressure amplitude imaged over a predetermined number of cycles. 4 illustrates an example filtered pressure curve plotted over crank angle for increasing amounts of fuel injected into the subcombustion chamber. 4 illustrates an example of filtered pressure curves plotted over frequency for increasing amounts of fuel injected into the subcombustion chamber; An example showing the deviation of the peak frequency when the amount of fuel injected into the sub-combustion chamber is increased is illustrated. 4 illustrates an example filtered torque curve and maximum torque amplitude for increasing amounts of fuel injected into the subcombustion chamber; 4 illustrates an example filtered torque curve and maximum torque amplitude for increasing amounts of fuel injected into the subcombustion chamber; 4 illustrates an example showing the correlation between the amount of fuel injected into the subcombustion chamber and the average maximum torque amplitude imaged over a predetermined number of cycles. 4 illustrates a flow chart describing an example for determining a characteristic parameter that correlates to jet force of a reactive jet; 4 illustrates a flow chart describing an example for determining a characteristic parameter that correlates to jet force of a reactive jet; 4 illustrates a flow chart describing an example for determining a characteristic parameter that correlates to jet force of a reactive jet;

FIG. 1 schematically illustrates an exemplary cylinder 100 of an internal combustion engine, not otherwise specified, which may have two or more cylinders 100 . The engine may have, for example, two, three, four, six, eight or less or more cylinders 100 . The engine has at least one piston 2 driven by a crankshaft (not shown) via a connecting rod 3 for repeated reciprocating motion within a cylinder 100 forming a main combustion chamber within the cylinder.

An (air) intake port 4 with an intake valve 6 and an exhaust port 5 with an exhaust valve 7 are connected to the main combustion chamber 1 . Outside air is drawn into the main combustion chamber 1 through the intake port 4 . Exhaust gases are discharged from the combustion chamber 1 through an exhaust port 5 . An ignition device 10 comprising a spark plug 10a, a secondary combustion chamber fuel injector 10b and a secondary combustion chamber 10c is mounted in an internal combustion engine.

A spark plug 10a of the ignition device 10 may be electrically coupled to an ignition coil (not shown). Spark plug 10a in combination with an ignition coil preferably forms a spark igniter that provides variable spark duration or multi-spark ignition. An internal combustion engine may have one or more ignition devices 10 . Preferably, each cylinder 100 has at least one ignition device 10 . An ignition device 10, or at least a portion thereof, is coupled inside the main combustion chamber 1 so that a reactive jet (indicated by dashed lines) can be introduced into the main combustion chamber. Furthermore, a direct fuel injector 8, or at least part thereof, is mounted inside the main combustion chamber 1 for the purpose of injecting fuel directly into the combustion chamber, thereby increasing the efficiency of the engine. This direct fuel injector 8 may preferably be an electrohydraulic fuel injector or a piezoelectric fuel injector. Additionally, a port fuel injector 9 is connected to the intake port 4 of the cylinder 100 . The high pressure fueling of the direct fuel injectors 8 and the high or low pressure fueling of the port fuel injectors 9 are not disclosed. The main fuel injection may be performed by either the direct main fuel injector 8 or the port main fuel injector 9, or may be shared between both injectors.

FIG. 1 also shows a control unit 11 for controlling the ignition device. This control unit 11 is electrically connected to the ignition system 10, the direct main fuel injectors 8 and/or the port main fuel injectors 9 and controls a plurality of units/injectors/actuators. In this connection, the control unit 11 receives signals from a plurality of sensors such as intake air quantity and intake air temperature, coolant temperature, crank angle, cylinder pressure, knock signal and the like. The control unit 11 may be, for example, an engine control unit (ECU).

Also, the control unit 11 may be another control unit, and the signal line connection between the control unit 11 and the unit under control may be different from the example shown in FIG. For example, there may be a plurality of control units 11 controlling subgroups of units under control, one control unit 11-1 controlling only the ignition device 10 and another control unit 11-1 controlling only the ignition device 10. 2 may be configured such that only the fuel injectors 8 and 9 are controlled. Furthermore, if there are multiple control units 11, these control units 11 may be interconnected hierarchically or in some other manner. Alternatively, a single control unit 11 may be provided which encompasses all control functions for the actuators.

Furthermore, the internal combustion engine may be provided with determination means for detecting high-frequency oscillations in the main combustion chamber 1 . For example, at least one pressure sensor, at least one knock sensor and/or at least one torque sensor (not shown) may be arranged, for example in/on the wall of the main combustion chamber 1 and/or directly on the crankshaft of the engine. may be set. Measurement and analysis of the high-pressure oscillations inside the main combustion chamber 1 generated by secondary combustion chamber combustion makes it possible to perform feedback control on the injection force of the secondary combustion chamber jets, thereby ensuring high efficiency over the service life of the engine. quality and emission limits are ensured.

Additionally, the subcombustion chamber 10c may be provided with at least one pressure sensor and/or at least one temperature sensor to provide additional information regarding conditions within the subcombustion chamber.

FIG. 2 shows a schematic diagram of the ignition device 10 . The ignition device 10 includes a fuel injector 10a, a spark plug 10b, and an auxiliary combustion chamber 10c. The sub-combustion chamber 10c is separated from the main combustion chamber 1 by a sub-combustion chamber wall 10d having an orifice 10e for introducing a reactive jet generated by combustion in the sub-combustion chamber into the main combustion chamber 1. there is Additionally, the secondary combustion chamber 10c may be provided with at least one pressure sensor and/or at least one temperature sensor to provide additional information regarding conditions within the secondary combustion chamber. Alternatively, or in addition, other components of the ignition system, such as fuel injectors 10a, spark plugs 10b, or subcombustion chamber walls 10d, may have temperature A sensor may be provided.

The shape of the sub-combustion chamber 10c is not limited to the shape shown in FIG. 2, and can be designed in various shapes such as a hemispherical shape, a conical shape, a cylindrical shape, or a combination thereof. Furthermore, the number, geometry and location of orifices 10e in sub-combustion chamber wall 10d are not limited to the example illustrated in FIG. The sub-combustion chamber 10c may be provided with a plurality of orifices 10e having various diameters disposed at various locations within the sub-combustion chamber wall 10d. The secondary combustion chamber injector 10a may be coupled to either the high pressure fuel supply or the low pressure fuel supply of the engine (not shown) to inject a different fuel than that injected into the main combustion chamber 1, or It may be connected to a separate fuel supply (not shown). The spark plug 10b may be contained within the ignition device 10 or electrically coupled to an ignition coil (not shown) which may be located elsewhere in the engine remote from the ignition device 10. FIG. Preferably, one ignition coil may be provided for each ignition device 10 , but it may be possible to provide a single ignition coil for a plurality of ignition devices 10 .

Figures 3a-3d show constant engine operating points when using a conventional spark plug (Figures 3a and 3b) and when using an ignition device with a secondary combustion chamber under fuel (Figures 3c and 3d), respectively. 4 shows a comparison of example cylinder pressures measured in the main combustion chamber 1 at . Comparing the measured cylinder pressure curves shown in FIGS. 3a and 3c, using an igniter with a subcombustion chamber under fuel narrows the deviations for the start of combustion and the peak cylinder pressure and reduces the duration of combustion. becomes clear that is shortened. This improves combustion stability and efficiency. Looking closely at the cylinder curve illustrated in Figure 3c, for example, a high-pass filter (see Figure 3d) allows oscillations to be discerned on a single pressure curve that appears to filter a representative portion of the measured pressure signal. . In this example, the crank angle region of 60° before FDTC and 60° after FTDC is cut out from the measured pressure signal and filtered by a bandpass filter with a frequency range of 4 kHz to 10 kHz. The filtered pressure signal shown in FIG. 3b, imaged using a conventional spark plug, does not exhibit significant pressure oscillations at the recorded operating points, but does not exhibit significant pressure oscillations when using secondary combustion chamber ignition. The corresponding signal presents strong oscillations of high amplitude. Such unique vibration amplitudes are found only in spark ignition in the case of knocking. However, the pressure oscillations illustrated in FIG. 3d are not knock-induced, but are due to the rapid escape of the reactive jet through the orifice 10e of the subcombustion chamber 10c, creating a shock wave within the main combustion chamber 1. It is.

As can be seen in Figures 4a-4f, the maximum amplitude of said pressure oscillations can be influenced by the amount of fuel injected into the secondary combustion chamber 10c. Figures 4a-4f present band-pass filtered pressure curves imaged at constant load and combustion timing, with continuously increasing amounts of fuel injected into the subcombustion chamber. It is clear that the maximum amplitude of pressure oscillations increases with increasing fuel mass. By increasing the amount of fuel injected into the subcombustion chamber, the heat release when burning the mixture in the chamber is greater, which results in higher injection power. Thus, as discussed above, the fuel mass injected into the subcombustion chamber may be appropriate in adjusting the injection power of the reactive jet.

Figures 5a-5c illustrate how the filtered cylinder pressure curve is processed to generate characteristic parameters that can be correlated to injection power. The pressure oscillation amplitude is not robust from cycle to cycle, so a single maximum amplitude is not a representative indicator. Therefore, it is necessary to evaluate the average value of a certain number of cycles. In addition, relevant time intervals for establishing characteristic parameters, such as the time interval from ignition timing to peak pressure position, must be considered.

In view of the above, the results of various processing steps are illustrated in Figures 5a-5c. The vibration curve illustrated in Figure 5a is generated by determining the absolute values of the associated bandpass filtered pressure curves illustrated in Figures 4a, 4c and 4e. To obtain the maximum absolute pressure amplitude illustrated in FIG. 5b, a predetermined number of engine cycles are analyzed to determine the maximum vibration amplitude for each selected cycle. Next, the average value of the determined maximum vibration amplitudes is calculated. As can be clearly deduced from FIG. 5c, the boost in injection force caused by increasing subcombustion chamber fuel mass is identifiable as a cycle average during the increase in maximum pressure oscillation amplitude.

Another method for post-processing the recorded cylinder pressure curve with the aim of obtaining characteristic parameters describing the injection power is illustrated in FIGS. 6a-6c. These figures illustrate the results of FFT analysis performed on the measured pressure curve.

FIG. 6a illustrates the bandpass filtered pressure curve plotted over the measured crank angle, while FIG. 6b illustrates the measured crank angle plotted over the frequency range of the pressure signal. Comparing the measurements performed with increasing sub-chamber injection masses m _{f_pc1} to m _{f_pc3} reveals an increase in intensity at 7000 kHz with increasing sub-chamber fuel mass. This finding is also confirmed by the frequency deviation illustrated in FIG. 6c. It is evident from FIG. 6c that the relative number of cycles exhibiting a peak at 7000 kHz increases with increasing subcombustion chamber fuel mass. Therefore, it can be said that the peak frequency deviation is used as a characteristic parameter for expressing the injection force.

Figures 7a-7c illustrate the same procedure as described in connection with Figures 5a-5c, with only the cylinder pressure signal replaced by the torque sensor signal. FIG. 7a illustrates the absolute value of the bandpass filtered torque curve. To obtain the maximum absolute torque amplitude illustrated in FIG. 7b, a predetermined number of engine cycles are analyzed to determine the maximum vibration amplitude for each selected cycle. The mean value of the determined maximum vibration amplitudes is then calculated.

Similar to FIG. 5c, it is also evident from FIG. 7c that the injection force boost caused by increasing the sub-combustion chamber fuel mass can be identified as a cycle average during the increase in maximum torque oscillation amplitude. This means that the torque measurement is likewise suitable as a cylinder pressure measurement to detect the injection force of the reactive jet produced by the subcombustion chamber combustion. However, the torque oscillations detectable by the torque-measuring flange arise from pressure fluctuations in all cylinders and can therefore only be sufficient to control the average injection power. In contrast, evaluating the pressure signal of each cylinder allows injection forces to be corrected individually.

Figures 8a-8c illustrate an example sequence of steps to be performed in order to evaluate the measured data from the various determination means in order to obtain a characteristic parameter that quantifies the injection force.

FIG. 8a shows an example of an evaluation method using a cylinder pressure signal. To carry out the method steps S100 to S103, it is necessary to record the cylinder pressure curve based on a certain number of cycles for each engine operating point. Once at least one cycle has been imaged, step S100 can be executed to shorten the timebase of the measured cylinder pressure signal to the crank angle range from ignition timing to peak firing pressure. Then, in step S101, the shortened signal is filtered, for example, by a bandpass filter with a frequency between 4 kHz and 10 kHz. At step S102, the maximum amplitude of the filtered signal is determined and recorded. This process is repeated until the maximum pressure oscillation amplitude is established for a predetermined number of cycles N for each operating point. Next, the average value of the maximum pressure oscillation amplitude suitable to represent the injection force of the reactive jet produced by the subcombustion chamber combustion is calculated.

FIG. 8b shows an example evaluation method using knock signals already available in the control unit and adapted to the relevant time range. After applying an appropriate bandpass filter (step S200), using FFT analysis, peak frequencies are identified for each engine cycle and stored in control unit 11 (step S201). This process is repeated until a predetermined number of engine cycles N have been analyzed. Then, by evaluating the peak frequency distribution, it becomes possible to characterize the injection force due to the dominant frequency maximum cycle in the cycle.

FIG. 8c illustrates processing similar to the post-processing of the pressure sensor signal, except utilizing a torque sensor instead of a pressure sensor. After recording the cycle-based torque signal for at least one engine cycle, step S300 can be executed in which the time base of the measured torque signal is now shortened to a limited crank angle range from ignition timing to peak firing pressure. be done. Then, in step S301, the shortened signal is filtered, for example, by a bandpass filter with a frequency range of 4 kHz to 10 kHz. At step S302, the maximum amplitude of the filtered signal is identified and stored. This process is repeated for a predetermined number of cycles N for each operating point until the maximum torque oscillation amplitude is determined. Next, an average cycle-based amplitude maximum value suitable to represent the injection power of the secondary combustion chamber jet averaged over all cylinders is calculated.

Summarizing again, the subject matter of the present application is to provide a control unit and method for controlling the injection power of the reactive jet flowing into the main combustion chamber 1 from the secondary combustion chamber 10c. The injection force can be correlated to detectable pressure oscillations generated within the main combustion chamber 1 as the jet escapes the secondary combustion chamber 10c. The actual injection force can be adjusted accurately according to the detected difference between the actual injection force and the target injection force. This adjustment is performed by changing parameters that affect combustion in the sub-combustion chamber, such as the amount of fuel injected into the sub-combustion chamber 10c, the fuel injection timing for that amount of fuel, and/or the ignition timing. The use of feedback control to adjust secondary combustion parameters makes it possible to ensure the efficiency and emissions limits of an internal combustion engine over its service life.

1 Main combustion chamber 2 Piston 3 Connecting rod 4 Intake port 5 Exhaust port 6 Intake valve 7 Exhaust valve 8 Direct injection main fuel injection 9 Port main fuel injector 10 Ignition device 10a Spark plug 10b Sub-combustion chamber fuel injector 10c Sub-combustion chamber 10d Sub-combustion chamber wall 10e - Orifice, 11... Control unit, 100... Cylinder

Claims (14)

at least one cylinder (100), at least one main combustion chamber (1), at least one intake port (4), at least one main fuel injector (8, 9), said main combustion chamber (1 ) and at least one ignition device (10) arranged to ignite the air-fuel mixture in said main combustion chamber (1). a control unit (11) for
Said ignition device (10) is connected to said main combustion chamber (10) through a spark plug (10a), a secondary combustion chamber fuel injector (10b) and at least one orifice (10e) in a secondary combustion chamber wall (10d). 1) with a sub-combustion chamber (10c) connected to
configured to control the injection force of the reactive jet flowing from the sub-combustion chamber (10c) into the main combustion chamber (1) ,
A control unit (11) characterized in that it is configured to determine a characteristic parameter representing the injection force based on the detected high-frequency vibration in the main combustion chamber . Control unit (11) according to claim 1, characterized in that said at least one determining means is a pressure sensor, a knock sensor and/or a torque sensor. generating a filtered signal by analyzing the detected high-frequency vibration over a predetermined time range for a predetermined number of engine cycles using a bandpass filter with a predetermined frequency band;
determining the maximum absolute amplitude of the filtered signal for each of the predetermined number of engine cycles and determining the characteristic parameter by averaging the determined maximum absolute amplitude;
3. Control unit (11) according to claim 1 or 2 , characterized in that said calculated mean value is said characteristic parameter. generating a filtered signal by analyzing the detected high-frequency vibration over a predetermined time range for a predetermined number of engine cycles using a bandpass filter with a predetermined frequency band;
determining the characteristic parameter by identifying a peak frequency of the filtered signal and calculating a distribution of the identified peak frequencies for each of the predetermined number of engine cycles;
Control unit (11) according to at least one of the preceding claims, characterized in that said calculated distribution is said characteristic parameter. The injection force is adjusted by adjusting the amount of fuel injected into the sub-combustion chamber and/or the injection timing of the sub-combustion chamber fuel injector (10b),
Control unit (11) according to at least one of the preceding claims, characterized in that the injection force is adjusted on the basis of the difference between a current characteristic parameter and a predetermined target characteristic parameter. The injection force is adjusted by adjusting the injection timing of the main fuel injectors (8, 9) and/or the ignition energy supplied to the spark plug (10a). Control unit (11) according to at least one of the preceding claims, characterized in that it is adjusted on the basis of the difference between the characteristic parameter and the predetermined target characteristic parameter. at least one cylinder (100), at least one main combustion chamber (1), at least one intake port (4), at least one main fuel injector (8, 9), said main combustion chamber (1 ), at least one control unit (11) according to at least one of claims 1 to 6 , and air-fuel in said main combustion chamber (1). and at least one ignition device (10) configured to ignite the mixture,
Said ignition device (10) is connected to said main combustion chamber (10) through a spark plug (10a), a secondary combustion chamber fuel injector (10b) and at least one orifice (10e) in a secondary combustion chamber wall (10d). 1), characterized in that it comprises an auxiliary combustion chamber (10c) connected to 1). The control unit (11) according to at least one of claims 1 to 7 controls the injection force of the reactive jet flowing into the main combustion chamber (1) from the sub-combustion chamber (10c). Control method for controlling an internal combustion engine according to claim 7 , characterized in that. 9. The control method according to claim 8, wherein said injection force is represented by a characteristic parameter based on said detected high-frequency vibration in said main combustion chamber. generating a filtered signal by analyzing the detected high frequency vibrations over a predetermined time range for a predetermined number of engine cycles using a bandpass filter with a predetermined frequency band;
wherein for each of said predetermined number of engine cycles said characteristic parameter is determined by identifying a maximum absolute amplitude of said filtered signal and calculating an average value of said determined maximum absolute amplitude; The control method according to claim 8 or 9 . generating a filtered signal by analyzing the detected high frequency vibrations over a predetermined time range for a predetermined number of engine cycles using a bandpass filter with a predetermined frequency band;
9. The characteristic parameter is determined by identifying peak frequencies of the filtered signal and calculating a distribution of the identified peak frequencies for each of the predetermined number of engine cycles. 11. The control method according to at least one of 10 . The amount of fuel injected into the sub-combustion chamber (10c) and/or the injection timing of the sub-combustion chamber fuel injector (10b) is adjusted based on the difference between a current characteristic parameter and a predetermined target characteristic parameter. The control method according to at least one of claims 8 to 11 , characterized in that: characterized in that the injection timing of the main fuel injectors (8, 9) and/or the ignition energy supplied to the spark plug (10a) is adjusted based on the difference between the current characteristic parameter and the predetermined target characteristic parameter. The control method according to at least one of claims 8 to 12 , wherein A computer program product storable in a memory containing instructions which, when executed by a computer, cause said computer to perform the method of at least one of claims 8 to 13 relating to a control method.

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