DE102015213894A1 - Method for introducing fuel into a combustion chamber of an internal combustion engine with intake manifold injection and direct injection - Google Patents

Abstract

The invention relates to a method for introducing fuel into a combustion chamber of an internal combustion engine with intake manifold injection and direct injection, wherein an offset by means of intake manifold injection and introduced into the combustion chamber first fuel quantity (M1) is determined, and wherein, when the first amount of fuel (M1) by means of intake manifold injection in the combustion chamber to be introduced target fuel quantity (MZ) falls below, a difference between the target fuel quantity (MZ) and the first fuel quantity (M1) corresponding second fuel quantity (M2) determined and is specified for the direct injection for introduction into the combustion chamber.

Description

The present invention relates to a method for introducing fuel into a combustion chamber of an internal combustion engine with intake manifold injection and direct injection, and to a computing unit and a computer program for its implementation.

State of the art

One possible method of fuel injection in gasoline engines is intake manifold injection (SRE), which is increasingly being replaced by direct fuel injection (DI). The latter method leads to significantly better fuel distribution in the combustion chambers and thus to better power output with lower fuel consumption, for example. At medium part load, while the first example. At low loads due to the mixture formation in fuel consumption is advantageous.

Furthermore, there are also gasoline engines with a combination of intake manifold injection and direct injection, a so-called dual system. This is particularly advantageous in the light of increasingly stringent emission requirements or emission limit values, because intake manifold injection, for example, results in better emission values at medium load ranges than direct injection.

However, a deviation in the fuel-air mixture, for example due to incorrect fuel metering, usually results in both a deterioration of the exhaust emission values and, if appropriate, noticeable performance losses for the driver. Likewise, it may, for example, due to an excessive amount of fuel to so-called. Fat misfires come, which can lead to damage to individual components of the internal combustion engine.

From the DE 10 2010 038 625 A1 For example, a method of calibrating port fuel injectors is known to reduce emissions due to poor fuel-air ratios in the combustion chamber. For this purpose, measured values of air-fuel ratios in mixed operation are compared with those of pure direct injection.

Disclosure of the invention

According to the invention, a method is proposed for introducing fuel into a combustion chamber of an internal combustion engine with intake manifold injection and direct injection, as well as a computing unit and a computer program for carrying it out with the features of the independent patent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

An inventive method is used for introducing fuel into a combustion chamber of an internal combustion engine, in particular a gasoline engine, with intake manifold injection and direct injection. In such a combination of intake manifold injection and direct injection one speaks also of a so-called dual system. In this case, an offset by means of intake manifold injection and introduced into the combustion chamber first fuel quantity is determined, and it is when the first amount of fuel by means of intake manifold injection into the combustion chamber to be introduced target fuel quantity, a difference between the target fuel amount and the first fuel amount corresponding second fuel amount determined and specified for the direct injection for introduction into the combustion chamber.

In the intake manifold injection fuel is introduced by means of one or more fuel injectors in the intake manifold, in which forms a fuel-air mixture and is guided into combustion chambers of the internal combustion engine. Since the fuel-air mixture in the intake pipe still has to travel a certain way, the amount of fuel to be introduced into the combustion chamber must be deposited well in advance of an ignition point in the combustion chamber through the corresponding fuel injector in the intake manifold, i. be introduced into the suction pipe. In normal operation, the desired amount of fuel is usually introduced into the combustion chamber as a result, in which the best possible air-fuel ratio prevails in the combustion chamber with respect to possible exhaust gases during combustion.

However, for example, changes due to a rapid or short-term speed change the time or the crankshaft angle at which the amount of fuel would have to be discontinued. The amount of fuel removed is at least substantially proportional to the injection duration. However, since the crankshaft angle at which the intake valves close to the combustion chamber is reached earlier at a higher rotational speed, it is no longer possible to introduce the entire amount of sediment from the intake manifold injection into the combustion chamber. This is also referred to as injection termination of the intake manifold injection. A subsequent correction of the beginning of the deducted by the intake manifold fuel quantity is then no longer possible. The consequence here would thus be, for example, a poor combustion due to poor mixture formation and thus poor emission levels. In addition, for example, the performance of the internal combustion engine may differ from the expected or desired value.

The inventive method uses the possibility of a dual system, ie an internal combustion engine with intake manifold injection and Direct injection, that in addition to the intake manifold injection also the direct injection can be used to introduce fuel into the combustion chamber. In particular, the invention makes use of the fact that the time, which is for the deposition of fuel to be introduced into the combustion chamber, in the direct injection timing behind the corresponding time in the intake manifold injection. In this way, therefore, due to an injection termination too low, offset by the intake manifold injection and introduced into the combustion chamber, fuel quantity can be corrected by the direct injection. In this way, better emission values and better performance of the internal combustion engine can be achieved.

It should be noted that this method is independent of a predictive division of the injection quantity of each intake manifold and direct injection. In the case of pure intake manifold injection, only the second fuel quantity can be provided by the direct injection. In a mixed operation, the second amount of fuel may be provided by the direct injection in addition to an amount of fuel to be provided anyway.

Preferably, the first amount of fuel is determined repeatedly or continuously at the latest from the time at which settling of fuel by means of the intake manifold injection begins. Preferably, the determination of the first amount of fuel can also be carried out already after the command to a controller for discontinuing the fuel. In this way, as early as possible, a deviation between the target fuel quantity and the actually offset, i. the first, fuel quantity determined and taken into account accordingly. In addition, it can be ensured that a missing, i. the second, fuel quantity still timely communicated to the direct injection and can also be introduced.

Advantageously, the target amount of fuel is determined taking into account a speed of the internal combustion engine and / or a load request to the internal combustion engine. In this way, the first amount of fuel can be determined as accurately as possible. In particular, in the case of rapid or short-term speed changes, it is thus possible to react to a changed amount of fuel that can be introduced into the combustion chamber. Based on the speed can be relatively easily the time between the start of settling and closing time of the intake valve and thus the first amount of fuel can be determined.

It is advantageous if the second quantity of fuel is predetermined after an injection termination for the direct injection for introduction into the combustion chamber. In this way, for example, a signal or a command to the direct injection or an associated power amplifier can be transmitted to their control. If an information or a signal that announces an injection termination in the intake manifold injection already exists in a motor control, this can be used very easily for this purpose.

Preferably, the first amount of fuel and the second amount of fuel are provided for introduction into the combustion chamber during the same injection cycle and are in particular also introduced. In this way, a fuel quantity that is too low, provided by the intake manifold injection, can be corrected as quickly as possible, that is to say still in the same injection cycle, whereby optimization of the emission values can take place as quickly as possible.

It is advantageous if the first fuel quantity and / or the target fuel quantity is reset or deleted after each injection cycle and / or after a restart of the internal combustion engine. In this way it can be ensured that erroneous or old information is used by mistake.

Advantageously, if the first fuel quantity does not deviate significantly or not significantly from the target fuel quantity, no second fuel quantity is specified for the direct injection. In this way, no unnecessary computing power, eg. An exporting control device, claimed.

Preferably, the determination of the first fuel quantity, the target fuel quantity and / or the second fuel quantity is performed only as long as there is no error in the port injection and / or the direct injection. This can be prevented that, for example, due to incorrect injections, a correction of the insufficient amount of fuel is carried out incorrectly and, for example. Too much fuel is introduced into the combustion chamber, which would be worse with respect to the emission levels than too little Kraftsoff.

It is advantageous if the determination of the first fuel quantity, the target fuel quantity and / or the second fuel quantity is performed separately for each of a plurality of combustion chambers of the internal combustion engine. In this way, the different time windows for the introduction of fuel for the different combustion chambers can be taken into account.

An arithmetic unit according to the invention, for example a control unit, in particular an engine control unit, of a motor vehicle is, in particular programmatically, adapted to perform a method according to the invention.

Also, the implementation of the method in the form of a computer program is advantageous because this causes very low costs, especially if an executive controller is still used for other tasks and therefore already exists. Suitable data carriers for providing the computer program are in particular magnetic, optical and electrical memories, such as e.g. Hard drives, flash memory, EEPROMs, DVDs, etc. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

The invention is illustrated schematically by means of embodiments in the drawing and will be described below with reference to the drawing.

Brief description of the drawings

1a and 1b each schematically show an internal combustion engine, which can be used for a method according to the invention.

2 schematically shows a cylinder of an internal combustion engine, which can be used for a method according to the invention.

3 schematically shows an introduction of fuel into a combustion chamber of an internal combustion engine for intake manifold and direct injection at different speeds of the internal combustion engine.

4 shows schematically the determination of fuel quantities in a method according to the invention in a preferred embodiment.

Embodiment (s) of the invention

In 1a is schematic and simplifies an internal combustion engine 100 which can be used for a method according to the invention. By way of example, the internal combustion engine 100 four combustion chambers 103 and a suction tube 106 on which to each of the combustion chambers 103 connected.

The suction tube 106 points for each combustion chamber 103 a fuel injector 107 on, which is located in the respective section of the suction pipe just before the combustion chamber. The fuel injectors 107 thus serve a port injection. Furthermore, each combustion chamber 103 a fuel injector 111 for a direct injection on.

In 1b is schematic and simplifies another internal combustion engine 200 which can be used for a method according to the invention. By way of example, the internal combustion engine 100 four combustion chambers 103 and a suction tube 206 on which to each of the combustion chambers 103 connected.

The suction tube 206 points for all combustion chambers 103 a common fuel injector 207 on, for example, is arranged in the intake manifold shortly after a throttle valve, not shown here. The first fuel injector 207 thus serves a port injection. Furthermore, each combustion chamber 103 a fuel injector 111 for a direct injection.

Both shown internal combustion engines 100 and 200 thus have a so-called dual system, ie via intake manifold injection and direct injection. The difference is only in the type of intake manifold injection. While, for example, the in 1a shown intake manifold injection a fuel metering allowed individually for each combustion chamber, as can be used, for example, for higher quality internal combustion engines, which is in 1b shown intake manifold injection easier in their design and their control. The two internal combustion engines shown may in particular be gasoline engines.

In 2 is a cylinder 102 the internal combustion engine 100 schematic and simplified, but more detailed than in 1a shown. The cylinder 102 has a combustion chamber 103 by moving a piston 104 is increased or decreased. The present internal combustion engine may in particular be a gasoline engine.

The cylinder 102 has an inlet valve 105 on to air or an air-fuel mixture in the combustion chamber 103 involved. The air gets over the suction pipe 106 supplied to an air supply system, at which the fuel injector 107 located. Sucked air is via the inlet valve 105 in the combustion chamber 103 of the cylinder 102 admitted. A throttle 112 in the air supply system is used to set the required air mass flow into the cylinder 102 ,

The internal combustion engine can be operated in the course of a port injection. With the help of the fuel injector 107 In the course of this intake manifold injection fuel is in the intake manifold 106 injected so that there forms an air-fuel mixture, via the inlet valve 105 in the combustion chamber 103 of the cylinder 102 is admitted.

The internal combustion engine can also be operated in the course of a direct injection. For this purpose, the fuel injector 111 to the cylinder 102 attached to fuel directly into the combustion chamber 103 inject. In this direct injection, the air-fuel mixture required for combustion is directly in the combustion chamber 103 of the cylinder 102 educated.

The cylinder 102 is still with an ignition device 110 provided to start combustion in the combustion chamber 103 to create a spark.

Combustion gases are removed from the cylinder after combustion 102 via a Abgasabführungsabschnitt 108 pushed out. The ejection is dependent on the opening of an exhaust valve 109 also on the cylinder 102 is arranged. Inlet and outlet valves 105 . 109 are opened and closed to a four-stroke operation of the internal combustion engine 100 perform in a known manner.

The internal combustion engine 100 can be operated with direct injection, with intake manifold injection or in mixed operation. This allows the choice of the optimal operating mode for operating the internal combustion engine 100 depending on the current operating point. So can the internal combustion engine 100 for example, in a port injection operation when operated at a low speed and a low load, and may be operated in a direct injection mode when operated at a high speed and a high load. However, over a wide operating range it makes sense to use the internal combustion engine 100 operate in a mixed operation in which the combustion chamber 103 supplied amount of fuel is supplied proportionately through intake manifold injection and direct injection.

Furthermore, one is as a control unit 115 trained computing unit to control the internal combustion engine 100 intended. The control unit 115 can the internal combustion engine 100 in the direct injection, the intake manifold injection or the mixed operation operate.

In relation to 2 explained in more detail operation of the internal combustion engine 100 can also be applied to the internal combustion engine 200 transferred, only with the difference that only one common fuel injector is provided for all combustion chambers or cylinders. In the case of intake manifold injection or in a mixed operation, therefore, the single fuel injector in the intake manifold is permanently activated.

In 3 schematically a introduction of fuel into a combustion chamber of an internal combustion engine for intake manifold and direct injection at different speeds n in 1 / min of the internal combustion engine is shown. For this purpose, angle windows are represented as a function of a crankshaft angle φ.

With φ _UT , φ _OT , φ ' _UT and φ _Z are shown angles corresponding to a first bottom dead center, a top dead center, a second bottom dead center and an ignition point, whereby an assignment of the windows shown to an injection and ignition sequence in an internal combustion engine possible is.

With 301 and 311 the maximum injection windows for intake manifold and direct injection are shown. It can be seen that the injection window 311 opposite the injection window 301 shifted backwards, which can be explained by the time that the fuel needs to pass through the intake manifold. With 320 a combined injection window is shown, as it is for a dual system, ie intake manifold and direct injection, given.

With 302 . 303 . 304 and 305 Injections for intake manifold injection are now shown by way of example at speeds of 1000, 2000, 4000 and 7000 rpm. It can clearly be seen that due to the higher speeds, earlier injection (in terms of angle) is needed to achieve the desired amount of fuel before closing the intake valve.

Furthermore, it can be seen that the end of each of the injector injection injections is always at least approximately at the same angular position. The reason for this is the closing of the inlet valve. Accordingly, the higher speed injections must begin earlier.

With 312 . 313 . 314 and 315 Injections for direct injection are now shown as examples at speeds of 1000, 2000, 4000 and 7000 rpm. The introduced by these injections into the combustion chamber fuel amounts corresponding to those with the injections 302 . 303 . 304 and 305 introduced fuel quantities, if instead of the intake manifold direct injection is used. The injection durations are shorter here than in the intake manifold injection, since the flow rate in the direct injection can be greater.

It can be seen that while the duration of the injections in the direct injections varies less with respect to the rotational speed, the injections take place much later than with the intake manifold injection. The reason for this is that the fuel can be introduced directly into the combustion chamber.

In 4 schematically is the determination of fuel quantities in a method according to the invention in a preferred embodiment shown. For this purpose, quantities of fuel are shown schematically as blocks.

By way of example, at a speed of 2000 rpm, an amount of fuel to be introduced into the combustion chamber by means of intake manifold injection and the associated start of the injection are determined at the angle φ ₁ , which is suitable for the speed 2000 rpm.

From the angle φ ₁ is now started to sell fuel into the intake manifold. In this case, only fuel which has reached the inlet valve up to an angle φ ₂ , to which the inlet valve closes, can be introduced into the combustion chamber. The amount of fuel actually introduced or introduced into the combustion chamber then corresponds to the first fuel quantity M ₁ . The first amount of fuel M ₁ is determined at the latest at the beginning of the settling, ie from the angle φ ₁ continuously, as would be necessary for a current speed.

Shortly before or when the angle φ _{2 is reached} , that is to say when the intake valve closes, a speed of 4000 rpm is reached, which would already correspond to a start of the settling of fuel at angle φ ₀ , as is the case with the target fuel quantity shown M _{Z is} shown. Such a change is not only possible at angle φ ₂ , but should have been known before the angle φ _o . Thus, an injection termination occurs, so that the first fuel quantity M _{1 is} smaller than the target fuel quantity M _Z.

Now, by comparing the target fuel amount M _Z and the first fuel amount M ₁ , that is actually introduced into the combustion chamber or introduced fuel amount, a difference fuel amount .DELTA.M be determined, which would be introduced in addition to the first fuel amount M ₁ in the combustion chamber , but can no longer be introduced by means of intake manifold injection. From this difference fuel quantity .DELTA.M can now be determined a second amount of fuel M ₂ , as they can be introduced by means of the direct injection into the combustion chamber.

It should be noted that the second fuel amount M _{2 of} course includes the same amount of fuel as the differential fuel amount .DELTA.M. However, a different injection duration may be necessary, since with direct injection, a different flow rate than in the intake manifold injection may be possible.

The second amount of fuel M ₂ can now be introduced to the angle φ ₂ or possibly shortly thereafter by means of the intake manifold injection into the combustion chamber. In contrast to the intake manifold injection can be introduced into the combustion chamber by means of the direct injection even after the angle φ ₂ nor fuel, as the 3 can be seen.

In particular, it should be emphasized that the determination of the first amount of fuel should already take place during the settling of the first amount of fuel in order to transfer the required second amount of fuel to the control of the direct injection in good time. The first amount of fuel can be determined, for example, even before the end of the settling of the first amount of fuel by, for example, based on an anticipated speed curve or a load request to the ignition angle or time in the combustion chamber einbringbare amount of fuel is determined.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102010038625 A1 [0005]

Claims (12)

Method for introducing fuel into a combustion chamber ( 103 ) an internal combustion engine ( 100 . 200 ) with intake manifold injection and direct injection, wherein a remote by means of intake manifold injection and into the combustion chamber ( 103 ₁ ), and wherein, when the first fuel quantity (M ₁ ) falls below a target fuel quantity (M _Z ) to be introduced into the combustion chamber by means of intake manifold injection, one of a difference between the target fuel quantity (M _Z ) and the first fuel quantity (M ₁ ) corresponding second fuel quantity (M ₂ ) determined and for the direct injection for introduction into the combustion chamber ( 103 ) is given. The method of claim 1, wherein the first amount of fuel (M ₁ ) is determined repeatedly or continuously at the latest from the time at which a discontinuation of fuel by means of the intake manifold injection begins. Method according to claim 1 or 2, wherein the first quantity of fuel (M ₁ ) takes into account a rotational speed of the internal combustion engine ( 100 ) and / or a load request to the internal combustion engine ( 100 ) is determined. Method according to one of the preceding claims, wherein the second fuel quantity (M ₂ ) after a injection termination for the direct injection for introduction into the combustion chamber ( 103 ) is given. Method according to one of the preceding claims, wherein the first fuel quantity (M ₁ ) and the second fuel quantity (M ₂ ) for introduction into the combustion chamber ( 103 ) are provided during the same injection cycle and introduced. Method according to one of the preceding claims, wherein the first fuel quantity (M ₁ ) and / or the target fuel quantity (M _Z ) after each injection cycle and / or after a restart of the internal combustion engine ( 100 ) is reset or deleted. Method according to one of the preceding claims, wherein, if the first fuel quantity (M ₁ ) does not deviate significantly or not substantially from the target fuel quantity (M _Z ), no second fuel quantity for the direct injection is specified. Method according to one of the preceding claims, wherein the determination of the first fuel quantity (M ₁ ), the target fuel quantity (M _Z ) and / or the second fuel quantity (M ₂ ) is only carried out as long as no error in the intake manifold injection and / or Direct injection is present. Method according to one of the preceding claims, wherein the determination of the first fuel quantity (M ₁ ), the target fuel quantity (M _Z ) and / or the second fuel quantity (M ₂ ) for each of a plurality of combustion chambers ( 103 ) of the internal combustion engine ( 100 ) is carried out separately. Arithmetic unit ( 115 ), which is adapted to perform a method according to any one of the preceding claims. Computer program comprising a computing unit ( 115 ) to perform a method according to any one of claims 1 to 9, when it on the computing unit ( 115 ) is performed. Machine-readable storage medium with a computer program stored thereon according to claim 11.

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