DE102015216863A1 - A method for determining the vaporized portion of an amount of fuel deposited by port injection - Google Patents

Abstract

The invention relates to a method for determining the vaporized portion of an amount of fuel deposited by means of intake manifold injection in the intake manifold (106) in an internal combustion engine (100) with intake manifold injection and direct injection, wherein a for a combustion cycle in the combustion chamber (103) to be introduced air quantity is determined, wherein a the amount of fuel-air mixture to be introduced into the combustion chamber (103) is determined, and wherein, taking into account the amount of air and the fuel-air mixture amount, the vaporized portion of the amount of fuel deposited in the intake manifold (106) by suction tube injection is determined.

Description

The present invention relates to a method for determining the vaporized portion of an amount of fuel deposited by means of intake manifold injection in the intake manifold in an internal combustion engine with intake manifold injection and direct injection and a computing unit and a computer program for its implementation.

State of the art

One possible method of fuel injection in gasoline engines is the intake manifold injection, which is increasingly being replaced by direct fuel injection. The latter method leads to significantly better fuel distribution in the combustion chambers and thus to better power output with lower fuel consumption.

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 ever stricter emission requirements or emission limit values, since intake manifold injection, for example, results in better emission values at medium load ranges than direct injection. In the full load range, however, the direct injection allows, for example, a reduction in the so-called knocking.

From the EP 1 555 418 A1 For example, a method for such a dual system is known in which a correction of an amount of fuel metered by intake manifold injection is made by changing the amount of fuel to be metered by direct injection after recognizing a change in the load request to the internal combustion engine after calculating the amount of fuel for the port injection.

Disclosure of the invention

According to the invention, a method for determining the vaporized portion of an amount of fuel deposited by means of intake manifold injection as well as a computer unit and a computer program for carrying it out with the features of the independent patent claims are proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

With the method according to the invention, the vaporized portion of an amount of fuel deposited or injected in the intake manifold by means of intake manifold injection in an internal combustion engine with intake manifold injection and direct injection can be calculated from an air quantity to be introduced into the combustion chamber for a combustion cycle and a fuel / air mixture to be introduced into the combustion chamber for the combustion cycle. Quantity (in particular as the difference between these quantities). This value can be used, for example, as an actual value for a combustion-related regulation, since the vaporized portion is usually also supplied to the combustion chamber. Alternatively or additionally, can be recalculated from the vaporized portion by means of an evaporation model to the originally deposited or injected portion. In particular, the amount of fuel can thus be determined in a further way, in addition, for example, for determining the duration of injection and the flow rate of the relevant fuel injector. This recalculated value can, for example, also be used as the actual value for a control, for example regarding the injection, or for plausibility of values obtained in a different manner.

Advantageously, a temperature, a pressure and / or a wall film of fuel in the intake manifold, a temperature or a rotational speed of the internal combustion engine, an air charge of the combustion chamber and / or valve timing are taken into account in the evaporation model. In this way, the amount of fuel removed can be determined very accurately.

Preferably, a set fuel quantity to be delivered by means of intake manifold injection is checked taking into account the determined fuel quantity. Thus, for example, any errors in the fuel metering can be detected very easily. While, for example, in a pure intake manifold injection, the introduced amount of fuel can also be checked by means of a lambda probe or the assessment of the exhaust gas, this is not possible with a dual system, since in the exhaust gas, the fuel quantities of intake manifold injection and direct injection would be tested together.

Advantageously, a desired fuel quantity to be delivered by means of intake manifold injection is corrected taking into account the determined fuel quantity for at least one subsequent combustion cycle. Conveniently, the desired fuel quantity can be corrected by changing a drive duration and / or an opening duration of a relevant fuel injector. In this way, for example, fuel pre-storage effects in the intake manifold, the associated passage of fuel through the combustion chamber and the concomitant increase in HC emissions can be avoided. The amount of fuel introduced by intake manifold injection can thus be optimized with regard to the consumption and emission potential.

It is advantageous if the vaporized portion of the fuel quantity and / or the fuel quantity is controlled to a desired value, taking into account the vaporized portion or the determined fuel quantity. For this purpose, for example, a control duration of the relevant fuel injector can be used as a manipulated variable. In this way, the emission levels can be easily improved.

Preferably, a deviation of a total amount of fuel to be delivered by means of intake manifold injection and direct injection is corrected taking into account the determined fuel quantity by means of the direct injection. This is advantageous, in particular, when a proportion of vaporized fuel permissible with respect to desired emission values is less than an amount of fuel required with regard to the load requirement of the internal combustion engine. Thanks to the dual system, it is thus very easy and fast to compensate for the insufficient amount of fuel.

Advantageously, a distribution of a total amount of fuel to be introduced into the combustion chamber on intake manifold injection and direct injection is determined, taking into account the determined evaporated fraction of the fuel quantity. This makes it particularly easy to determine an optimal distribution among the injection types, in particular with regard to the emission values, which can later be reused. In particular, load and / or dynamic dependencies of the internal combustion engine can also be taken into account. In addition, engine aging processes, component drift, deviations in a component exchange, fuel quality differences and environmental influences such as, for example, differences in air humidity can be compensated for.

It is advantageous if the amount of air to be introduced into the combustion chamber for the combustion cycle is determined by means of an air mass sensor. For example, a hot-film air mass meter can be used as air mass sensor. Since an air mass meter is usually present anyway in an internal combustion engine or in the intake manifold, the amount of air, i. the amount or mass of pure air without fuel, are determined very easily and quickly.

Preferably, the fuel-air mixture amount to be introduced into the combustion chamber for the combustion cycle is determined by means of an intake manifold pressure sensor and in particular taking into account an evaporation model. For this purpose, a pressure-based filling determination can be used. Here, for example, on the basis of the intake manifold pressure, the throttle valve opening, the engine speed and the intake air temperature, the air charge is determined. Since the evaporating fuel quantity leads to an increase in pressure, the charge determined via the pressure sensor is higher than that determined via the air flow meter. The difference corresponds to the evaporated fuel quantity. It takes advantage of the fact that the pressure in the intake manifold increases after the introduction of the fuel, which forms a fuel-air mixture with the air. Taking into account a vaporization model and, for example, the temperature, the rotational speed and a wall film of fuel in the intake manifold or a model to do so, the fuel-air mixture amount can be determined very easily. Such intake manifold pressure sensor is usually present anyway.

An arithmetic unit according to the invention, e.g. a control unit, in particular an engine control unit, of a motor vehicle is, in particular programmatically, configured 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 with reference to an embodiment of the drawing and will be described below with reference to the drawing.

Brief description of the drawings

1a and 1b schematically show two internal combustion engines, 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 a determination of an amount of fuel by 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 shown which one for a inventive method can be used. 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 on 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, an air mass sensor 140 and an intake manifold pressure sensor 150 in the intake pipe 106 intended. In the air mass sensor 140 For example, it may be a hot-film air mass meter whose mode of operation is known per se and is not to be explained in more detail here.

Furthermore, one is as a control unit 115 trained computing unit for controlling 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. The air mass sensor 140 and the intake manifold pressure sensor 150 can by a suitable connection to the control unit 115 be connected.

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 actuated.

In 3 schematically a determination of an amount of fuel by means of a method according to the invention is shown in a preferred embodiment. First, an amount of air M _L , which is to be introduced for a combustion cycle in the combustion chamber, determined.

For this purpose, for example, in 2 shown air mass sensor 140 be used. In particular, with the air mass sensor, an air flow in the intake manifold 106 be recorded. By taking into account the opening time of the inlet valve 105 Thus, for example, the amount of air M _L relevant for the combustion cycle can be determined very simply.

Furthermore, a fuel-air mixture amount M _KL , which is to be introduced for the combustion cycle in the combustion chamber, determined. For this purpose, for example, in 2 shown intake manifold pressure sensor 150 be used. In particular, with the intake manifold pressure sensor, for example, a pressure difference between a time before introduction of the fuel through the fuel injector 107 in the suction pipe 106 and one time thereafter. Since the fuel, as far as it evaporates, mixes with the air in the intake manifold, the pressure in the intake manifold is increased.

The amount of air M _K and the fuel-air mixture amount M _KL can now be offset against each other, so as to obtain the vaporized and introduced into the combustion chamber fuel amount. By a suitable evaporation model, in which in particular a temperature in the intake manifold, a speed of the internal combustion engine and a wall film model, which describes itself depositing on the inner wall of the intake manifold fuel, can be considered, from this evaporated fraction, the actually deposited in the intake manifold amount of fuel M _K can be determined by the fuel injector 107 and thus was deposited by the intake manifold injection into the intake manifold.

The amount of fuel M _K can now be used, for example, for checking or plausibility of an associated desired fuel quantity. Such a check can in particular also be carried out for the same combustion cycle.

Furthermore, the fuel quantity M _{K can} also be used to correct the desired injection quantity, for example via a change in the activation duration of the relevant fuel injector. It is understood that such a correction is only possible for subsequent combustion cycles.

It should be noted that in the case of an internal combustion engine with only one fuel injector in the intake manifold for several or all combustion chambers, such as, for example, in 1b is shown, in the determination of the relevant for a combustion chamber air volume and fuel-air mixture amount, a division of the respective amounts must be considered in several combustion chambers.

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

• EP 1555418 A1 [0004]

Claims (15)

Method for determining the vaporized portion of a by means of intake manifold injection in the intake manifold ( 106 ) offset fuel quantity (M _K ) of an internal combustion engine ( 100 . 200 ) with intake manifold injection and direct injection, wherein one for a combustion cycle in a combustion chamber ( 103 ) amount of air to be introduced (M _L ) is determined, with one for the combustion cycle in the combustion chamber ( 103 ) To be introduced air-fuel mixture amount (M _KL) is determined, and wherein (M _L), taking account of the air amount and the air-fuel mixture amount (M _KL) the evaporated portion of the (by means of intake manifold in the intake manifold 106 ) offset fuel quantity (M _K ) is determined. The method of claim 1, wherein from the vaporized portion of the offset by means of the intake manifold injection amount of fuel (M _K ) is determined. A method according to claim 2, wherein, taking into account an evaporation model, the amount of fuel (M _K ) deposited by means of the intake manifold injection is determined from the vaporized portion. Method according to claim 3, wherein in the evaporation model a temperature, a pressure and / or a wall film of fuel in the intake manifold ( 106 ), a temperature or a rotational speed of the internal combustion engine ( 100 ), an air filling of the combustion chamber ( 103 ) and / or valve timing are taken into account. Method according to one of claims 2 to 4, wherein a to be set off by means of intake manifold target fuel quantity is checked taking into account the determined amount of fuel (M _K ). Method according to one of claims 2 to 5, wherein a set fuel quantity to be set by means of intake manifold fuel quantity is corrected taking into account the determined amount of fuel (M _K ) for at least one subsequent combustion cycle. Method according to claim 6, wherein the desired fuel quantity is determined by a change of a driving duration and / or an opening duration of a respective fuel injector ( 107 ) is corrected. Method according to one of claims 2 to 7, wherein the evaporated portion of the amount of fuel (M _K ) is controlled taking into account the determined amount of fuel (M _K ) to a desired value. Method according to one of the preceding claims, wherein a deviation of a total fuel quantity to be delivered by means of intake manifold injection and direct injection is corrected taking into account the vaporized portion of the determined fuel quantity by means of the direct injection. Method according to one of the preceding claims, wherein taking into account the vaporized portion of the determined amount of fuel (M _K ), a division of a total amount of fuel to be deducted on intake manifold injection and direct injection is determined. Method according to one of the preceding claims, wherein the for the combustion cycle in the combustion chamber ( 103 ) To be introduced quantity of air (M _L) by means of an air mass sensor ( 140 ) is determined. Method according to one of the preceding claims, wherein the fuel-air mixture quantity (M _KL ) to be introduced into the combustion chamber for the combustion cycle is determined by means of an intake manifold pressure sensor ( 150 ) is determined. 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 12, when it on the computing unit ( 115 ) is performed. A machine-readable storage medium having a computer program stored thereon according to claim 14.

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