JP7225438B2 - Temperature control device and control method for auxiliary combustion chamber included in ignition device for internal combustion engine - Google Patents

Description

The present invention relates to a temperature control device and control method for an auxiliary combustion chamber under fuel supply of an ignition device included in an internal combustion engine.

In order to improve the thermal efficiency of internal combustion engines, it is known, in particular in the case of gasoline or gas engines, to utilize ignition devices which include 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 igniting the resulting air-fuel mixture in the chamber. The secondary combustion chamber is connected to the primary combustion chamber through fine orifices so that combustion within the secondary combustion chamber flows from the secondary combustion chamber into the primary combustion chamber and undergoes multiple reactions that ignite the air-fuel mixture. leading to sexual jets. 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, the use of precombustion as described above can result in increased particulate emissions. For example, fuel injection into the subcombustion chamber at hot conditions may lead to residue buildup on the subcombustion chamber injector surfaces. This residue build-up can in turn lead to increased particulate emissions. Additionally, fuel injected into the primary combustion chamber can self-ignite on the hot outer surfaces of the secondary combustion chambers and can cause thermal damage to the engine. The temperature in the primary combustion chamber increases with increasing engine load, and the temperature in the secondary combustion chamber also increases due to heat transfer from the primary combustion chamber to the secondary combustion chamber. Thus, for example, during high load conditions of the engine, high temperature conditions can be expected.

For example, during high load conditions, to avoid thermal damage to the auxiliary combustion chamber and the engine, cooling measures are taken to suppress auto-ignition on the auxiliary combustion chamber surfaces at high temperatures and to reduce heat in the auxiliary combustion chamber. Techniques have been proposed to avoid damage. In this connection, it has been proposed to lower the temperature in the secondary combustion chamber by additionally injecting fuel into the secondary combustion chamber after combustion has occurred. Vaporization of the additionally injected fuel cools the inside of the auxiliary combustion chamber.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2018-91267) discloses a control device for an internal combustion engine having a sub-combustion chamber under fuel supply, and after completion of combustion in the sub-combustion chamber, second / additional injection to reduce the temperature of the injector in the subcombustion chamber.

However, as noted above, performing an additional/secondary injection into the secondary combustion chamber may result in increased particulate emissions/excessive particulate emissions, especially under high engine load conditions. may invite.

JP 2018-91267 A

The subject matter described herein aims to provide a control unit and control method for efficiently cooling the subcombustion chamber without increasing the particulate emissions of the combustion engine.

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

The control unit for controlling the internal combustion engine may be configured to control the injection into the secondary combustion chamber and/or the main combustion chamber of the internal combustion engine, or the injection of the fuel quantity, depending on the temperature of the secondary combustion chamber. This injection is preferably an additional injection that occurs after the combustion-friendly fuel injection. Such additional injections shall be referred to as "cooling injections" in the following description, and the term "injection" shall generally refer to cooling injections, unless expressly used otherwise. do.

In other words, the controller may perform a control process that includes "determining" whether fuel should be injected into the secondary combustion chamber or into the primary combustion chamber (for cooling). This "decision step" may be taken depending on the temperature of the secondary combustion chamber. Further, it may be possible to execute a combined injection in which fuel is injected into the main combustion chamber and the sub-combustion chamber.

Regarding the mode/state of an ignition system with secondary combustion chamber fuel injectors, with respect to the terminology used in the following description, the mode or operation of injecting fuel into the secondary combustion chamber is referred to as the "active mode" and the fuel is injected into the primary combustion chamber. Note that the mode or operation that injects into the chamber is referred to as the "passive mode."

The internal combustion engine includes at least one cylinder, at least one main combustion chamber (abbreviated "main chamber"), at least one intake port, at least one main fuel injector, and ignites an air-fuel mixture in the main combustion chamber. may comprise at least one igniter that The ignition system may comprise 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.

If the temperature in the secondary combustion chamber is above a predetermined temperature, the control unit controls the main fuel injector to perform injection into the main combustion chamber (cooling injection) during the compression stroke of the internal combustion engine. Preferably, said predetermined temperature may have a value in the range of 100°C to 250°C. The predetermined temperature or its value or range of values may be set according to the location of the subcombustion chamber that establishes that temperature. More preferably, the range may be set between 150°C and 200°C.

In the case described above, the ignition device is operated in passive mode, so that no fuel is (nearly) injected (directly) into the subcombustion chamber during the cooling injection.

As mentioned above, during high engine load conditions, the additional/cooling injection into the subcombustion chamber can result in undesirably large amounts of particulate emissions. The present subject matter avoids this by utilizing additional fuel injection into the main combustion chamber ("main chamber" for short) to cool the secondary combustion chamber. Specifically, when the piston is moving upward and a cooling injection into the main chamber is performed, at least a small amount of the injected fuel flows into the subcombustion chamber and vaporizes therein, while the injected fuel The other (larger) portion of is vaporized in the main combustion chamber. Vaporization of the fuel cools the sub-combustion chamber. Preferably, the start of the cooling injection into the main combustion chamber is piloted at the end of the compression stroke, when the cylinder temperature is rising due to the preceding compression (may be called "post-stroke injection"). . This leads to rapid fuel vaporization, which in turn effectively lowers the temperature of the mixture in and around the secondary combustion chamber. Preferably, the cooling injection ends before ignition timing, otherwise pressure build-up in the chamber may prevent injected fuel from entering the secondary combustion chamber.

For the aforementioned inflow or transfer of injected fuel from the main chamber into the subcombustion chamber, the cooling injection is ignited by the control unit at a point in time when the pressure in the subcombustion chamber is lower than the pressure in the main combustion chamber. Provided that this can be improved. Said pressure differential between the primary chamber and the secondary combustion chamber may support the transfer of fine fuel droplets and cooled air-fuel mixture into the secondary combustion chamber.

Pressure sensors may be provided in both chambers to determine the pressure in the primary and secondary combustion chambers. With respect to the subcombustion chamber, a measuring spark plug with a pressure sensor next to/proximate/near the center electrode may be utilized, as described above. It may also be possible to install a small self-contained pressure sensor in the secondary combustion chamber. A semi-permanent, commonly known pressure sensor can be utilized to measure the pressure in the main combustion chamber.

Alternatively, during the testing phase of the engine, it may be possible to determine the optimum crank angle region in which cooling injection should be performed. This test phase can include all relevant operating points, and the optimum crank angle value determined thereby can be stored as a characteristic curve or map in the control unit.

Additionally, the control unit may adjust the amount of fuel to be injected into the main combustion chamber for cooling depending on the temperature of the secondary combustion chamber. If multiple cooling injections are to be carried out, which is preferably possible within the framework of the subject matter of the present application, the amount of fuel to be injected during the cooling injections is the secondary combustion for the first cooling injection into the main combustion chamber. It may be adjusted for the reaction of the chamber. For example, if the temperature of the sub-combustion chamber drops after the first cooling injection, the amount of fuel injected during the second cooling injection is reduced, or after the first cooling injection, the temperature of the sub-combustion chamber rises. If it rises further or remains constant, it may be increased.

Specifically, for example, if the sub-combustion chamber temperature does not decrease after the initial (post-process) cooling injection containing, for example, 1% of the total amount of fuel injected into the main combustion chamber (the total amount is the amount of fuel injected for combustion purposes and the amount of fuel injected for cooling injection), the amount of fuel may be increased to 1.5% or 2% of the total fuel amount, respectively. If the subcombustion chamber temperature remains constant, the amount of injected fuel may be further increased until the limits of post-cooling fuel injection relying on hydrocarbons and/or particulate emissions are reached. The maximum amount of fuel injected into the main combustion chamber for cooling during the compression stroke is preferably in the range of 4% to 10% of the total fuel amount and is in the range of 5% to 7% thereof. is more preferable. Also, for example, if the sub-combustion chamber temperature drops but does not fall below a predetermined temperature (threshold), the amount of fuel injected to cool the sub-combustion chamber may be reduced according to the temperature gradient. Alternatively, when the sub-combustion chamber temperature drops rapidly, the injected fuel amount is reduced by a large value such as 1% of the total fuel amount, while when the sub-combustion chamber temperature drops slowly, the injected fuel The amount may be reduced by a small amount such as 0.3% of the total fuel amount.

Further, the control unit may control the secondary combustion chamber fuel injectors to perform cooling injection into the secondary combustion chambers depending on the temperature of the secondary combustion chambers. For example, if the cooling injection into the main combustion chamber does not result in a temperature drop in the subcombustion chamber and/or if the subcombustion chamber temperature exceeds another/second temperature threshold that causes thermal damage, the subcombustion chamber A cooling injection to the may be performed. Under such (emergency/exceptional) circumstances, the igniter is switched to active mode and thermal damage to the subcombustion chamber due to uncontrolled self-ignition caused by the hot surfaces of the subcombustion chamber and thus the To avoid engine damage, a small amount of fuel may be injected into the subcombustion chamber without concern for possible increases in particulate emissions. The amount of fuel injected into the subcombustion chamber may preferably be in the range 1% to 5% of the total fuel amount, most preferably in the range 2% to 4%. The second temperature threshold for initiating injection into the subcombustion chamber (active mode) is preferably higher than the first temperature threshold and depends on the location of the subcombustion chamber determining the temperature. , in the range of 200°C to 500°C. Most preferably, it may be in the range of 300°C to 400°C.

By initiating active mode, the (after-process) cooling injection into the main combustion chamber may be completely stopped, or a continuous transition from passive to active mode may be performed. In the latter case, the amount of fuel injected into the primary combustion chamber at the end of the compression stroke may be reduced continuously or stepwise, with the amount of fuel injected into the secondary combustion chamber being continuously Alternatively, it may be increased stepwise. It is also possible to combine active and passive modes by injecting a first fuel quantity into the main combustion chamber and a second fuel quantity directly into the secondary combustion chamber.

Furthermore, the control unit may determine the temperature of the secondary combustion chamber on the basis of measured temperatures and/or characteristic parameters stored as characteristic curves or maps in the control unit.

Preferably, the subcombustion chamber temperature is measured using at least one temperature sensor permanently mounted in the subcombustion chamber or on the walls of the subcombustion chamber. For example, a temperature sensor installed within the subcombustion chamber can measure the gas temperature within the chamber. Alternatively, or in addition, the temperature of the subcombustion chamber walls can be used as a reference temperature for the subcombustion chamber temperature. In this case, the temperature sensor may for example be mounted on the lower surface of the secondary combustion chamber wall facing the main combustion chamber.

Alternatively or additionally, the pressure in the secondary combustion chamber may be measured by a pressure sensor integrated in the spark plug, for example. By measuring the pressure rise in the precombustion chamber, it is possible to estimate the heat release in the chamber, which in turn has a good correlation with the assumed gas temperature in the precombustion chamber and the temperature of the precombustion chamber walls. will provide

Furthermore, temperature sensors or pressure sensors may be provided only during test phases in which the engine is run under all relevant boundary conditions. During the test phase, the gas temperature in the subcombustion chamber and/or the subcombustion chamber wall temperature and/or the subcombustion chamber pressure may vary, for example, at different engine loads and speeds, different spark timings, different air/fuel ratios, different intake air. It can be measured at temperature and pressure, various EGR ratios, various valve timings, and so on. The characteristic subcombustion chamber temperature determined during the test phase can be continuously measured by the control unit or, depending on the calculated parameters, stored in the control unit as a characteristic curve or map.

Additionally, the characteristic subcombustion chamber temperature may be determined by performing CFD simulations, taking into account all possible boundary conditions at the relevant engine operating point. The temperature values determined by the simulation may also be stored in the control unit as characteristic curves or maps.

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 igniting an air-fuel mixture in the main combustion chamber. a method for controlling an internal combustion engine having at least one ignition device and at least one control unit for, the ignition device comprising a spark plug, an auxiliary combustion chamber fuel injector and at least one in an auxiliary combustion chamber wall. a secondary combustion chamber connected to the primary combustion chamber via an orifice, and the amount of fuel to be injected into the secondary combustion chamber and/or into the primary combustion chamber (for cooling), depending on the temperature of the secondary combustion chamber, is: It may be controlled by a control unit.

According to the subject matter described herein, at least a portion of the injected fuel is transferred into the secondary combustion chamber when the temperature of the secondary combustion chamber is higher than a (first) predetermined temperature, and A cooling injection may be performed by the main fuel injector into the main combustion chamber during the compression stroke of the internal combustion engine to cool the secondary combustion chamber with latent heat.

Preferably, when the pressure in the secondary combustion chamber is lower than the pressure in the primary combustion chamber, cooling injection into the primary combustion chamber during the compression stroke is directed to the primary fuel injector to support fuel transfer into the secondary combustion chamber. may be performed by

Additionally, during the compression stroke, the amount of fuel for cooling injection into the primary combustion chamber may be adjusted by the primary fuel injectors depending on the temperature of the secondary combustion chamber. This makes it possible, after the initial cooling injection into the main combustion chamber, to adjust the amount of fuel to be injected according to the evolution of the auxiliary combustion chamber temperature.

If a further increase in the amount of cooling injection fuel introduced into the main combustion chamber does not lead to a decrease in the auxiliary combustion chamber temperature, or if the auxiliary combustion chamber temperature exceeds the second temperature threshold, the temperature of the auxiliary combustion chamber Injection into the subcombustion chamber may be performed by the subcombustion chamber fuel injector depending on the .

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 igniting an air-fuel mixture in the main combustion chamber. An internal combustion engine having at least one ignition device, the ignition device being a secondary combustion chamber coupled to the primary combustion chamber via a spark plug, a secondary combustion chamber fuel injector, and at least one orifice in the secondary combustion chamber. and the internal combustion engine may have a control unit as described above.

Further, the presently claimed subject matter is also a computer program product storable in memory containing instructions which, when executed by a computer or computing unit, cause a computer to perform the above-described method or aspects thereof, as well as , a computer readable (storage) medium containing instructions for causing a computer to perform the method or aspects thereof.
Effect of the invention

In summary, a control unit and method for controlling the temperature of an auxiliary combustion chamber fueled by an igniter contained within an internal combustion engine provides an efficient and efficient operation at high engine loads without increasing particulate emissions. cooling. This is achieved by performing targeted cooling injections into the main combustion chamber and/or into the secondary combustion chambers, depending on the secondary combustion chamber temperature.

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; 4 schematically shows different fuel injection modes depending on subcombustion chamber temperature; 4 schematically shows different fuel injection modes depending on subcombustion chamber temperature; 4 schematically shows different fuel injection modes depending on subcombustion chamber temperature; Fig. 4 schematically shows various injected fuel quantities during an engine cycle as a function of subcombustion chamber temperature; Fig. 4 schematically shows various injected fuel quantities during an engine cycle as a function of subcombustion chamber temperature; Fig. 4 schematically shows various injected fuel quantities during an engine cycle as a function of subcombustion chamber temperature; 4 illustrates the pressure curves and associated pressure differentials established within the subcombustion chamber and the main combustion chamber; A flow chart is shown in this application as an example of a claim control method.

FIG. 1 schematically shows an exemplary cylinder 100 of an internal combustion engine, not otherwise specified, having two or more cylinders 100 . The engine may have, for example, two, three, four, six, eight or fewer 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 temperature sensor (not shown) may be disposed in or on the secondary combustion chamber (10c).

Spark plug 10a of 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 a part thereof, is coupled inside the main combustion chamber 1, which makes it possible to inject fuel into the chamber. 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 or the high or low pressure fueling of the port fuel injectors 9 is not discussed. The main fuel injection may be performed by 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. 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 multiple control units 11 controlling sub-groups of units under control, one control unit 11-1 controlling only the ignition device 10 and the other control unit 11-2 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, at least one temperature sensor (not shown) may be provided in the auxiliary combustion chamber 10c or on the auxiliary combustion chamber wall 10d of the ignition device 10 (see FIG. 2). This temperature sensor allows monitoring of the characteristic subcombustion chamber temperature for timely initiation of subcombustion chamber cooling measures to prevent engine damage.

Furthermore, pressure sensors, not shown, may be arranged, for example, in the walls of the main combustion chamber 1 and/or in the auxiliary combustion chamber 10c of the ignition device 10. FIG. Measuring the pressure in the main combustion chamber 1 and/or in the subcombustion chamber 10c allows feedback combustion control to be achieved and also provides additional information about the conditions in both chambers to guide the subcombustion chamber cooling measures. It will also improve.

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 the sub-combustion chamber wall 10d, and the reactive jet generated by the sub-combustion chamber combustion is introduced into the main combustion chamber 1 into the sub-combustion chamber wall. An orifice 10e is provided.

Furthermore, at least one temperature sensor (not shown) may be provided in the sub-combustion chamber 10c and/or on the sub-combustion chamber wall 10d. A temperature sensor arranged in the subcombustion chamber in a manner that makes it possible to measure the gas temperature in the chamber, first makes it possible to deduce the temperature of the components of the subcombustion chamber from the gas temperature, and then the temperature of the subcombustion chamber. It may be useful for deriving information about the quality of chamber combustion. Alternatively, or in addition, a temperature sensor mounted on the sub-combustion chamber wall 10d can supply its associated temperature. In this case, the temperature sensor may be mounted, for example, close to the orifice 10e in the lower surface of the sub-combustion chamber wall 10d, as this is where the highest temperature is expected. This makes it possible to obtain information about the temperature rise of the sub-combustion chamber wall at an early stage. In order to protect the sensor from damage due to overheating, it may be possible to place the temperature sensor on the subcombustion chamber wall at a distance from the tip of the subcombustion chamber 10c.

Alternatively or additionally, it may be possible to arrange at least one temperature sensor on the spark plug 10b, for example on the center electrode and/or on the ground electrode of the spark plug. Alternatively or additionally, at least one temperature sensor may be mounted on the tip of the secondary combustion chamber fuel injector 10a. A temperature sensor at this location would be able to provide information, among other things, about the expected increase in particulate emissions due to subcombustion chamber injection.

The shape of the sub-combustion chamber 10c is not limited to the shape illustrated 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 position of orifices 10e in sub-combustion chamber wall 10d are not limited to the example illustrated in FIG. The secondary combustion chamber 10c may be provided with a plurality of orifices 10e disposed at various locations within the secondary combustion chamber wall 10d and having various diameters. 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) 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-3c schematically illustrate various fuel injection modes depending on the secondary combustion chamber temperature _Tpc . FIG. 3a shows that the secondary combustion chamber temperature T _pc remains below the (first) temperature threshold T ₁ , no secondary combustion chamber cooling is required, and the main injection (combustion ) is executed only once. Alternatively or additionally, the main injection or at least part of the main injection that contributes to combustion may be introduced into the intake port 4 . FIG. 3b illustrates the situation where the subcombustion chamber temperature _TPC lies between predetermined first and second temperatures (thresholds) _T1 and _T2 . In this case, the cooling injection into the main chamber 1 is performed at the end of the compression stroke, more precisely at a predetermined crank angle before top dead center firing FTDC. Proper injection timing is related to ignition timing as described in connection with FIG. Furthermore, FIG. 3c shows that the sub-combustion chamber temperature _TPC exceeds the threshold value _T2 , and during the intake stroke, in addition to the main chamber injection (contributing to combustion), the cooling injection into the sub-combustion chamber 10c is It illustrates the case where it is executed immediately before firing FTDC.

Figures 4a-4c schematically show different amounts of injected fuel during the engine cycle as a function of the subcombustion chamber temperature _TPC . If the auxiliary combustion chamber temperature _TPC remains below the first temperature threshold _T1 , the entire fuel quantity is injected into the main combustion chamber 1 during the intake stroke. Alternatively, or in addition, all or at least a portion of the fuel quantity for combustion may be injected into the intake port 4 . If the subcombustion chamber temperature _TPC is above the threshold _T1 , a portion of the total fuel quantity introduced into the main chamber 1 or intake port 4 is injected during the compression stroke to achieve a cooling effect. As schematically illustrated in FIG. 4b, said fuel quantity for cooling increases with increasing subcombustion chamber temperature _TPC . At least part of the fuel injected after the compression stroke cools the sub-combustion chamber 10c and also contributes to heat release within the main chamber 1 . Thus, increasing the amount of fuel during the compression stroke can reduce the injected fuel during the intake stroke, as schematically illustrated in Figure 4a. If the secondary combustion chamber temperature _TPC is above the threshold value _T2 , as schematically illustrated in FIG. 4c, a cooling injection into the secondary combustion chamber 10c is performed. The dashed line shown in FIG. 4c illustrates the quantity of injected fuel required in the subcombustion chamber 10c if no cooling injection was performed into the main combustion chamber 1 during the compression stroke.

FIG. 5 illustrates the pressure curves measured in the subcombustion chamber 10c and the main chamber 1 and the resulting pressure differences. From FIG. 5, it can be derived that the post-process cooling injection introduced into the main combustion chamber 1 should be executed before combustion within the sub-combustion chamber 10c is started. Otherwise, the flow of injected fuel into the secondary combustion chamber 10 was blocked due to the pressure increase in the chamber. In FIG. 5, the post-process injection cycle into the sub-combustion chamber starts at a certain angle before the top dead center firing FTDC, and the time point when the pressure difference between the main combustion chamber pressure P _cyl and the sub-combustion chamber pressure P _prechamber drops. It is exemplified that it ends with . This may be the case when ignition is carried out by the spark plug 10b and then combustion in the secondary combustion chamber 10c is started. Thus, it may also be possible to establish injection timing at the latest possible point in time relative to ignition timing. Furthermore, in order to efficiently cool the subcombustion chamber 10c, the cooling injection into the main chamber 1 should be started as late as possible. The start of the cooling injection may thus be determined as a function of the latest possible end time of said injection and the quantity of fuel to be injected.

Pressure sensors may be installed in both chambers to establish the pressure in the main chamber 1 and the pressure in the subcombustion chamber 10c. For the secondary combustion chamber 10c, a measuring spark plug with a pressure sensor next to the center electrode may be used. It may also be possible to utilize a small pressure sensor that can be mounted within the secondary combustion chamber 10c. For measuring the pressure in the main combustion chamber 1, generally known pressure sensors for semi-permanent use are available.

Alternatively, it may be possible to establish the ideal period of post-cooling injection into the main chamber 1 during the engine test phase. In this test phase, all relevant operating points are taken into account and the determined optimum crank angle range for the post-process injection into the main combustion chamber 1 is stored in the control unit 11 as a characteristic curve or map. good too.

FIG. 6 illustrates a flow chart showing an example of a claim control method in the present application. As long as the secondary combustion chamber temperature T _PC remains within the permissible range, the fuel mass m _{f_PC} injected into the secondary combustion chamber as well as the fuel mass m _{f_MC_CS} injected into the main combustion chamber during the compression stroke are set to zero ( Steps S100, S101), the temperature thresholds _T1 and _T2 are checked periodically every time step Δt. The time step Δt for monitoring the subcombustion chamber temperature T _PC may preferably lie in the range 10 ms to 1000 ms, most preferably in the range 50 ms to 500 ms. If the secondary combustion chamber temperature _TPC is above the second threshold temperature _T2 , _{increase the secondary combustion chamber fuel mass mf_PC by} a predetermined value _{Δmf_PC} at each time step Δt until a predetermined limit value mF_PCmax is reached ( step S102). The predetermined value Δm _{f_PC} may preferably be in the range 0.1% to 1% of the total fuel mass, most preferably in the range 0.3% to 0.7% of the total fuel mass. Further, the predetermined limit value _{mF_PCmax} may be 5% of the total fuel mass, most preferably 4% of the total fuel mass. The second threshold temperature _T2 is preferably in the range 200° C. to 400° C., most preferably in the range 250° C. to 350° C., depending on the location of the secondary combustion chamber that establishes the temperature. good.

If the secondary combustion chamber fuel mass _{mf_PC} exceeds the limit value _{mF_PCmax} and the secondary combustion chamber temperature _TPC still remains above the threshold value _T2 , the power supply is preferably in the range 1 kW to 10 kW, most preferably 2 kW to 5 kW. The engine power P is reduced by a predetermined value ΔP that may be within the range (step S103). A power reduction is performed after each time step Δt as long as the engine power P does not fall below a predetermined threshold P _min . If the engine power is below the threshold _Pmin , an error is detected that results in the engine running in limp home mode or shutting down completely (step S104). In this connection, the engine power limit value P _min may preferably lie in the range 85% to 98% of rated power, most preferably in the range 90% to 95% of rated power.

If the secondary combustion chamber temperature _TPC does not exceed the temperature threshold _T2 , but exceeds the temperature threshold _T1 , the fuel mass _{mf_MC_CS} injected into the main combustion chamber during the compression stroke for cooling is limited to a predetermined limit value m It is increased by the value Δm _{f_MC_CS} at each time step Δt until _{F_MC_CSmax} is reached (step S105). The predetermined value m _{f_MC_CS} may preferably be in the range 1%-20% of the total fuel mass, most preferably in the range 10%-15% of the total fuel mass. Furthermore, the predetermined limit value _{mF_MC_CSmax} may lie in the range 10% to 50% of the total fuel mass, most preferably in the range 20% to 40% thereof.

When the limit value m _{F_MC_CSmax} is exceeded, m _{f_MC_CS} is set to zero to stop the post-process cooling injection into the main combustion chamber 1 (step S106), and the amount of injected fuel m By increasing _{f_PC} by the value _{Δmf_PC} , the auxiliary combustion chamber cooling injection is switched on (step S102). In the following steps, the same procedure as described for the state T _PC >T ₂ is performed. In this connection, instead of setting m _{f_MC_CS} to zero, the amount of fuel injected into the main combustion chamber 1 and the amount of fuel injected into the sub-combustion chamber 10c are changed continuously or stepwise in parallel. By increasing, it may be possible to perform a continuous transition from post-process main chamber injection to sub-combustion chamber injection. Another possibility is to introduce a first fuel quantity into the main combustion chamber 1 and a second fuel quantity directly into the subcombustion chamber 10c, thus providing a combination of both cooling injections.

Generally, all features of the various embodiments, aspects and examples disclosed herein and shown in the accompanying figures may be combined in part or in whole. In addition, the inventive subject matter described herein is intended to include such combinations as would be obvious to a person skilled in the art without inventive activity.

Also, it should be noted that the detailed description and accompanying drawings merely illustrate the principles of the methods, apparatus and systems presented herein. Accordingly, those skilled in the art will appreciate that various constructions which embody the principles of the claimed subject matter herein and are encompassed within its spirit and scope, even though not expressly described or represented herein, can be devised. It should be understood that it is possible.

Summarizing again, the present subject matter is dependent on the secondary combustion chamber temperature by introducing a targeted cooling injection into the primary combustion chamber during the compression stroke and/or by introducing a targeted cooling injection into the secondary combustion chamber. By introducing a defined cooling injection, an unacceptably high temperature in the subcombustion chamber is avoided. Introducing cooling injection into the main combustion chamber at the end of the compression stroke helps control secondary combustion chamber temperature without increasing particulate emissions. Upward movement of the piston transfers at least a portion of the injected fuel into the subcombustion chamber so that the injected fuel can vaporize and cool the subcombustion chamber. Accordingly, direct cooling injection into the secondary combustion chamber, which can lead to increased particulate emissions, is avoided by the present subject matter over a wide operating range of the engine, and this direct cooling injection reduces the temperature of the secondary combustion chamber. is too hot.

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 (10)

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 a control unit (11) for an internal combustion engine comprising at least one ignition device (10) configured to ignite an air-fuel mixture in
Said ignition device (10) is connected to said main combustion chamber (1) 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). ) and a sub-combustion chamber (10c) connected to
The control unit (11) is configured to control fuel injection into the sub-combustion chamber (10c) and/or the main combustion chamber (1) according to the temperature of the sub-combustion chamber (10c) , controlling said main fuel injector (8) to inject fuel into said main combustion chamber (1) when the pressure in said secondary combustion chamber (10c) is lower than the pressure in said main combustion chamber (1); A control unit (11), characterized in that it is arranged to carry out injection . When the temperature of the secondary combustion chamber (10c) is above a predetermined temperature, the control unit (11) controls the main fuel injector (8) to 2. A control unit (11) according to claim 1, characterized in that it is arranged to carry out an injection into the combustion chamber (1). 2. The control unit (11) is configured to adjust the amount of fuel injected into the main combustion chamber (1) according to the temperature of the auxiliary combustion chamber ( 10c ). or a control unit (11) according to 2 .
(11). Claim 1, characterized in that the temperature of the auxiliary combustion chamber (10c) is determined based on the temperature to be measured and/or on the basis of characteristic parameters stored in the control unit as characteristic curves or maps. 4. Control unit (11) according to at least one of claims 1 to 3 . 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 control unit (11), the method for controlling an internal combustion engine comprising:
Said ignition device (10) is connected to said main combustion chamber (1) 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). ) and a sub-combustion chamber (10c) connected to
fuel injection into the sub-combustion chamber (10c) and/or into the main combustion chamber (1) is controlled by the control unit (11) according to the temperature of the sub-combustion chamber (10c) ;
injection into said main combustion chamber (1) is carried out by said main fuel injector (8) when the pressure in said secondary combustion chamber (10c) is lower than the pressure in said main combustion chamber (1); A method for controlling an internal combustion engine, characterized by: Injection into the main combustion chamber (1) is performed by the main fuel injector (8) during the compression stroke of the internal combustion engine when the temperature of the secondary combustion chamber (10c) is above a predetermined temperature. 6. A method for controlling an internal combustion engine according to claim 5 , characterized in that: 7. The method according to claim 5 or 6 , characterized in that the amount of fuel injected into the main combustion chamber (1) is adjusted by the control unit (11) according to the temperature of the auxiliary combustion chamber (10c). A method for controlling the described internal combustion engine. 5- , characterized in that the injection into the subcombustion chamber (10c) is performed by the subcombustion chamber fuel injector (10b) depending on the temperature of the subcombustion chamber (10c). 8. A method for controlling an internal combustion engine according to at least one of 7 . Internal combustion engine comprising at least one control unit (11) according to at least one of claims 1-4 . A computer program product storable in memory comprising instructions which, when executed by a computer, cause said computer to perform the method of at least one of claims 5-8 .

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