CN106368830B

CN106368830B - Method for determining a transient compensation in an internal combustion engine with an intake manifold and direct injection

Info

Publication number: CN106368830B
Application number: CN201610584086.6A
Authority: CN
Inventors: R.帕森; O.阿本德罗特; P.埃克特; A.布劳
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-07-23
Filing date: 2016-07-22
Publication date: 2022-02-25
Anticipated expiration: 2036-07-22
Also published as: CN106368830A; DE102015213893A1

Abstract

The invention relates to a method for determining a transient compensation in an internal combustion engine (100) having an intake manifold injection and a direct injection, wherein a first correction quantity is determined taking into account a change in a load demand on the internal combustion engine (100), wherein a second correction quantity is determined taking into account a change in a distribution over the intake manifold injection and the direct injection, and wherein a total correction quantity for the transient compensation is determined taking into account the first correction quantity and the second correction quantity.

Description

Method for determining a transient compensation in an internal combustion engine with an intake manifold and direct injection

Technical Field

The present invention relates to a method for determining a transient compensation in an internal combustion engine having an intake pipe injection and a direct injection, and to a computing unit and a computer program for carrying out the method.

Background

One possible method for fuel injection in gasoline engines is intake manifold injection, which is increasingly being replaced by direct fuel injection. The latter method results in a significantly better fuel distribution in the combustion chamber and thus in a better power yield at lower burn-up. DE 102007005381 a1 discloses, for example, a method for transition compensation during intake manifold injection, in which different possible fuel types are taken into account during fuel metering.

Furthermore, there are also gasoline engines with a combination of intake manifold injection and direct injection, so-called dual systems (Dualsystem). This is particularly advantageous in the case of increasingly stringent emissions requirements or emission limits, since intake manifold injections, for example, in the average load range result in better emission values than direct injections.

However, deviations in the fuel-air mixture, for example due to incorrect fuel metering in dynamic transitions between different assignments to the two operating modes or in the event of a change in the load demand, often lead not only to a deterioration in the exhaust emission values but also to a power loss which can possibly be felt by the driver.

However, the transitions of the two paths, that is to say the transitions of the fuel metering of the two injection systems, must be coordinated with one another, which becomes increasingly difficult as the degrees of freedom with regard to possible transitions in different internal combustion engines increase, since the coordination of the fuel metering between the two paths is necessary in order to achieve the best possible emission values.

Disclosure of Invention

According to the invention, a method for determining a transition compensation in an internal combustion engine having an intake manifold injection and a direct injection, as well as a computing unit and a computer program for carrying out the method are proposed with the features of the independent patent claims. Advantageous embodiments are the subject matter of the dependent claims and the following description.

The method according to the invention is used to determine a transient compensation in an internal combustion engine, in particular a gasoline engine, having an intake manifold injection and a direct injection. Here, the first correction amount is determined in consideration of a change in the load demand on the internal combustion engine, and the second correction amount is determined in consideration of a change in the distribution between intake pipe injection and direct injection. Then, a total correction amount for the transient compensation is determined taking into account the first correction amount and the second correction amount.

Transition compensation is referred to herein as: for each injection system, a surplus (Mehrmenge) or a shortage (Mindermenge) of fuel is determined and used in relation to the amount of fuel actually required by the current operating point. The reason for this is that, for example, in the event of a change in the load demand and thus in the event of a change in the throttle position in the air intake line as a result of changing pressure conditions, temperature conditions and/or flow conditions, the proportion of the change in the wall of the air intake line is deducted from the quantity of fuel injected. This is similarly dependent on the temperature of the cylinder, for example on the inner wall of the combustion chamber. This should be corrected in the sense of an emission-optimized operation of the internal combustion engine.

Now, with the method according to the invention, in addition to the change in the load demand, when the transient compensation is determined, as is also usually done in existing injection systems only, the change in the distribution of the total fuel quantity to be measured to the intake manifold injection and the direct injection (between 0% and 100%, respectively) can also be taken into account. By determining the respective correction amounts for the change in the load demand and the change in the distribution separately from one another, it is possible in particular to take account separately of typical physical causes for the associated change, since these causes do not necessarily have the same effect on both types of change, that is to say the change in the load demand and the change in the distribution of the fuel quantity to both injection types. It is also possible in a very simple manner to take account of a pure change in the distribution while the load demand remains unchanged, since in this case the first correction quantity can simply be set to zero.

In the determination of the first correction amount, separate partial correction amounts for the intake pipe injection and the direct injection are preferably taken into account. Therefore, the change of the load demand can be more accurately studied. For example, the required correction amount may be different for each of intake pipe injection and direct injection in different rotation speed ranges based on a change in the load demand.

The second correction amount is advantageously determined taking into account the temperature of the intake manifold of the internal combustion engine, the temperature of the combustion chamber of the internal combustion engine and/or the temperature difference between the intake manifold and the combustion chamber. The required correction amount can therefore also be determined more precisely, since the formation of a wall film on the intake pipe and/or the inner wall of the combustion chamber, which is a cause of the transient compensation, can also depend on the temperature of the component in question (and also on the temperature of the intake pipe in the case of direct injection, which also has an influence on the formation of a wall film in the combustion chamber in the case of direct injection). In particular, the temperature difference between the intake pipe and the combustion chamber can also be relevant in the case of a change in the distribution, i.e. for the second correction amount, since the wall film formation here shifts from the intake pipe to the combustion chamber or from the combustion chamber to the intake pipe.

Advantageously, when determining the first and/or second correction variable, an operating parameter specific to the internal combustion engine is taken into account. For example, certain operating limits, maximum rotational speeds, idling rotational speeds or the like may be taken into account. The type of intake manifold injection may also be considered here, that is to say, for example, with fuel injectors for a plurality of combustion chambers or with individual fuel injectors for each combustion chamber. This enables a more accurate and simpler determination of the transition compensation. Such operating parameters can in particular also be registered in the control unit, for example within the framework of the setting parameters, on which control unit the method is carried out, for example. In particular, by separately determining the correction for the change in the load demand and the change in the distribution, a simple design of the software for the motor control can be achieved, which can be adapted very easily to different internal combustion engines.

The driving characteristics of a motor vehicle having an internal combustion engine are preferably taken into account when determining the first and/or second correction amounts. Different driving modes of the driver, for example, such as fuel-saving or sport (sport) driving modes, with the corresponding best possible compensation of transitions, can therefore be taken into account.

The geometry of the internal combustion engine is preferably taken into account when determining the first and/or second correction quantities. The geometry of the internal combustion engine may include, in particular, the area of the intake pipe and/or the inner side of the combustion chamber and/or the position of the fuel injector relative to the intake pipe and/or the position of the fuel injector relative to the combustion chamber. Since these geometries may influence the associated correction quantities. Thus, for example, the diameter of the intake manifold and the distance of the fuel injector in the intake manifold from the intake valve determine the amount of fuel required to build or remove the wall film. In this way, the transition compensation can be performed more accurately.

The computing unit according to the invention, for example a control unit, in particular a motor control unit, of a motor vehicle, is designed, in particular in terms of programming, for carrying out the method according to the invention.

The implementation of the method in the form of a computer program is also advantageous, since this results in particularly low costs, in particular when the implemented controller is also used for other tasks and is therefore always present. Suitable data carriers for supplying the computer program are, in particular, magnetic, optical and electrical memories, such as, for example, hard disks, flash memories, EEPROMs, DVDs and others. Downloading of the program via a computer network (internet, ethernet, etc.) is also possible.

Other advantages and design aspects of the invention will appear from the description and the accompanying drawings.

Drawings

The invention is illustrated schematically in the drawings by means of embodiments and is described hereinafter with reference to the drawings.

Fig. 1a and 1b schematically show two internal combustion engines which can be considered for the method according to the invention;

FIG. 2 schematically shows a cylinder of an internal combustion engine, which cylinder may be considered for the method according to the invention;

fig. 3 shows schematically in a diagram a switchover between two operating points of the internal combustion engine with a change in load demand and a change in distribution;

fig. 4 shows a schematic representation of the procedure of the method according to the invention in a preferred embodiment.

Detailed Description

Fig. 1a shows schematically and in a simplified manner an internal combustion engine 100 which can be considered for the method according to the invention. The internal combustion engine 100 has, for example, four combustion chambers 103 and an intake pipe 106 connected to each of the combustion chambers 103.

The intake manifold 106 has a fuel injector 107 for each combustion chamber 103, which is arranged in each section of the intake manifold shortly before the combustion chamber. The fuel injector 107 is thus used for intake pipe injection. Furthermore, each combustion chamber 103 has a fuel injector 111 for direct injection.

Fig. 1b shows schematically and in a simplified manner another internal combustion engine 200, which can be considered for the method according to the invention. The internal combustion engine 100 has, for example, four combustion chambers 103 and an intake pipe 206 connected to each of the combustion chambers 103.

The intake manifold 206 has a common fuel injector 207 for all combustion chambers 103, which is arranged in the intake manifold, for example, shortly after a throttle valve, which is not shown here. The first fuel injector 207 is thus used for intake pipe injection. Furthermore, each combustion chamber 103 has a fuel injector 111 for direct injection.

The two

internal combustion engines

100 and 200 shown thus have a so-called dual system, that is to say intake manifold injection and direct injection. The only difference is in the type of intake pipe injection. During the intake manifold injection shown in fig. 1a, for example, a fuel metering for each combustion chamber is allowed, which, as can be used, for example, in higher-value internal combustion engines, the intake manifold injection shown in fig. 1b is simpler in terms of its structure and its actuation. Both of the illustrated internal combustion engines may be, in particular, gasoline engines.

Fig. 2 shows a cylinder 102 of an internal combustion engine 100 schematically and in a simplified manner, but in greater detail than fig. 1 a. The cylinder 102 has a combustion chamber 103 which is enlarged or reduced by the movement of a piston 104. The present internal combustion engine may in particular be a gasoline engine.

The cylinder 102 has an intake valve 105 to allow air or an air-fuel mixture to enter the combustion chamber 103. The air is delivered via an air inlet pipe 106 of the air delivery system, on which a fuel injector 107 is located. The intake air is allowed to enter the combustion chamber 103 of the cylinder 102 via the intake valve 105. A throttle valve 112 in the air delivery system is used to adjust the desired mass flow of air into the cylinder 102.

The internal combustion engine may also be operated during intake pipe injection. Fuel is injected into the intake pipe 106 during this intake pipe injection by means of the fuel injector 107, so that an air-fuel mixture is formed there, which is allowed to enter the combustion chamber 103 of the cylinder 102 via the intake valve 105.

The internal combustion engine may also be operated during direct injection. For this purpose, a fuel injector 111 is mounted on the cylinder 102 so as to inject fuel directly into the combustion chamber 103. In such direct injection, an air-fuel mixture required for combustion is directly formed in the combustion chamber 103 of the cylinder 102.

The cylinder 102 is also provided with an ignition device 110 to generate an ignition spark in the combustion chamber 103 in order to initiate combustion.

The combustion exhaust is expelled from the cylinder 102 via the exhaust discharge section 108 after combustion. The discharge takes place in dependence on the opening of an exhaust valve 109 which is also arranged on the cylinder 102. The intake and

exhaust valves

105, 109 are opened and closed to effect four-stroke operation of the engine 100 (viertaktbettrie) in a known manner.

The internal combustion engine 100 can be operated with direct injection, with intake manifold injection or in hybrid operation. This makes it possible to select the respective optimum operating mode for operating the internal combustion engine 100 as a function of the current operating point. The internal combustion engine 100 can therefore be operated, for example, in an intake pipe injection mode when it is operated at a relatively low speed and a relatively low load, and in a direct injection mode when it is operated at a high speed and a high load. Beyond a large operating range, it is still sensible to operate the internal combustion engine 100 in hybrid operation, in which the fuel quantity to be supplied to the combustion chamber 103 is supplied in portions by intake manifold injection and direct injection.

Furthermore, a computer unit designed as a controller 115 is provided for controlling the internal combustion engine 100. Controller 115 may cause internal combustion engine 100 to be operated in direct injection, intake pipe injection, or hybrid operation.

The operating mode (fuel temperature) of the internal combustion engine 100, which is explained in more detail with reference to fig. 2, can also be transmitted to the internal combustion engine 200 with the following differences: only one common fuel injector is provided for all combustion chambers or cylinders. In the case of an intake manifold injection or in the case of a hybrid operation, therefore, a single fuel injector in the intake manifold is permanently actuated.

Fig. 3 schematically shows a switching between two operating points of the internal combustion engine with a change in the load demand and a change in the distribution. For this purpose, a distribution a between 0 and 1 is shown, which distribution describes the portion of the direct injection in the present case, and a load demand L for the internal combustion engine between 0% and 100% is shown.

Exemplary shown at operating point B₁To operating point B₂The switching between includes both the change in load demand Δ L and the change in distribution Δ a.

Fig. 4 shows a block diagram of a method according to the invention in a preferred embodiment.

First, it can be checked whether there is a change Δ L in the load demand on the internal combustion engine, whether there is a change Δ a in the distribution of the intake pipe injection and the direct injection, or whether there are both changes.

If there is only a change Δ L or two changes in the load demand, a first correction quantity Δ M can be determined₁. If, for example, a higher load is required, more fuel must be metered into the combustion chamber. However, since a wall film is formed in the intake manifold from the fuel, which increases in the intake manifold as the fuel proportion in the air-fuel mixture increases, a portion of the injected fuel must be used to build up the wall film. Nevertheless, in order to still achieve the desired fuel quantity in the internal combustion chamber, a first correction quantity Δ M must be passed₁Here, the excess amount is adapted to the amount of fuel to be injected.

In the case of a wall membrane in the combustion chamber, the wall membrane is likewise dependent on the quantity of fuel injected or the fuel fraction in the air-fuel mixture in the combustion chamber. In this case, in the determination of the first fuel quantity, a distinction can be made between the two injection modes, i.e. two partial correction values can be determined, which are compared with the first correction value Δ M₁Taken together. This is a very simple calculation, for example in the case of using only one injection mode.

If there is only a change Δ A in the distribution or there are two changes, a second correction quantity Δ M can be determined₂. If, for example, a switchover is made from a pure intake pipe injection to a direct injection, the wall film in the intake pipe is eliminated and the eliminated fuel reaches the combustion chamber. Then it must be taken into account for this purposeThe shortfall is used for transition compensation.

If, for example, switching from direct injection to intake pipe injection or mixed operation, an excess of fuel is required in order to build up a wall film in the intake pipe. In particular, the temperatures of the intake manifold and of the combustion chamber or their temperature differences can also be taken into account in the case of a change in the distribution, since the combustion chamber is significantly hotter than the intake manifold and therefore has an influence on the quantity of fuel to be injected, for example by the viscosity of the fuel (kraft ffviskost ä t).

Now, the first correction quantity Δ M₁And a second correction quantity DeltaM₂As they have just been found, can be mutually calculated, thus obtaining the total correction quantity Δ M. For the case where only one of the two variations is present, the respective other correction quantity may simply be set to zero.

It can be seen here that, by separately determining the two correction variables, it is also possible to take into account very simply changes only in the load demand and in particular also changes only in the distribution.

The correction variable for each change can be determined, for example, within the framework of a test on an engine test stand, wherein, for example, the continuous operation is switched between different load requirements and between different assignments. In this case, it may be expedient to determine the correction variables as a function of the changes, wherein in the test only a few support points (St ü tzpunkte) for the function are determined and then the function is interpolated.

Claims

1. Method for determining a transient compensation in an internal combustion engine (100, 200) having intake pipe injection and direct injection,

a first correction amount (Delta M) is obtained in consideration of a change (Delta L) in a load demand for an internal combustion engine (100, 200)₁），

A second correction quantity (Delta M) is determined taking into account the change (Delta A) in the distribution between the intake pipe injection and the direct injection₂) And an

Wherein a total correction amount (Δ M) for the transient compensation is determined in consideration of the first correction amount and the second correction amount,

wherein the formation of a wall film on the intake pipe and/or the inner wall of the combustion chamber is responsible for the transition compensation.

2. Method according to claim 1, wherein the first correction quantity (Δ M) is determined₁) Separate partial corrections for the intake pipe injection and the direct injection are taken into account.

3. Method according to claim 1 or 2, wherein the second correction quantity (Δ M) is determined₂) Taking into account the temperature of an intake pipe (106, 206) of the internal combustion engine (100, 200), the temperature of a combustion chamber (103) of the internal combustion engine (100, 200) and/or the temperature difference between the intake pipe (106, 206) and the combustion chamber (103).

4. Method according to claim 1 or 2, wherein the first correction quantity (Δ M) is determined₁) And/or the second correction quantity (Δ M)₂) Operating parameters specific to the internal combustion engine (100, 200) are taken into account.

5. Method according to claim 1 or 2, wherein the first correction quantity (Δ M) is determined₁) And/or the second correction quantity (Δ M)₂) The driving behavior of a motor vehicle having the internal combustion engine (100, 200) is taken into account.

6. Method according to claim 1 or 2, wherein the first correction quantity (Δ M) is determined₁) And/or the second correction quantity (Δ M)₂) Taking into account the geometry of the internal combustion engine (100, 200).

7. The method according to claim 6, wherein the geometrical dimensions of the internal combustion engine (100, 200) comprise the area of the intake pipe (106, 206) and/or the inside of the combustion chamber (103) and/or the position of the fuel injector (107, 207) with respect to the intake pipe (106, 206) and/or the position of the fuel injector (111) with respect to the combustion chamber (103).

8. A computing unit (115) arranged for performing the method according to any of the preceding claims.

9. Machine-readable storage medium with a computer program stored thereon, which, when executed on a computing unit (115) according to claim 8, causes the computing unit (115) to carry out the method according to any one of claims 1 to 7.