WO2017036682A1

WO2017036682A1 - Method for determining the evaporated portion of a fuel quantity applied by way of port fuel injection

Info

Publication number: WO2017036682A1
Application number: PCT/EP2016/067881
Authority: WO
Inventors: Thomas Kuhn; Claus Wundling; Timm Hollmann; Udo Schulz; Rainer Ecker
Original assignee: Robert Bosch Gmbh
Priority date: 2015-09-03
Filing date: 2016-07-27
Publication date: 2017-03-09
Also published as: CN107923329A; CN107923329B; DE102015216863A1; KR20180048962A; KR102517253B1

Abstract

The invention relates to a method for determining the evaporated portion of a fuel quantity applied by way of port fuel injection in the inlet manifold (106) of an aspirated direct-injection internal combustion engine (100). According to said method, an air quantity to be introduced into the combustion chamber (103) for a combustion cycle is determined, a fuel-air mixture quantity to be introduced into the combustion chamber (103) for a combustion cycle is determined, and the evaporated portion of the fuel quantity applied by way of port fuel injection in the inlet manifold (106) is determined taking into consideration the air quantity and the fuel-air mixture quantity.

Description

description

title

A method for determining the vaporized portion of an amount of fuel deposited by port injection

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

A 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 EP 1 555 418 A1, for example, a method for such a dual system is known in which a correction of a metered by means of intake manifold fuel quantity by a change zuzumes- by direct injection zuzumes- amount of fuel is sent after a change in the load request has been recognized to the internal combustion engine after calculating the amount of fuel for the intake manifold 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 computing 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 fraction 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 ratio to be introduced into the combustion chamber for the combustion cycle. Mixture amount (in particular as a difference of these quantities) can be determined. 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, it is possible to recalculate from the vaporized fraction by means of an evaporation model to the originally deposited or injected fraction. In particular, so that the amount of fuel in a further way, in addition, for example, to determine the injection duration and the flow rate of the fuel injector concerned, are determined. 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 sold can be determined very accurately.

Preferably, a set to be deducted by means of intake manifold target fuel quantity is checked taking into account the determined amount of fuel. Thus, for example, any errors in the metering of fuel can be detected very easily. While, for example, in a pure intake manifold injection the amount of fuel introduced 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 by changing a driving time and / or an opening duration of a respective fuel! be corrected. 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 in terms of consumption and emission potential.

It is advantageous if the vaporized portion of the amount of fuel and / or the amount of fuel is controlled to a desired value taking into account the evaporated portion or the determined fuel quantity. For this purpose, for example, a control period of the relevant fuel! Njektors be used as a manipulated variable. In this way, the emission levels can be easily improved. A deviation of a total amount of fuel to be delivered by means of intake manifold injection and direct injection is preferably 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 regard to desired emission values is less than one with regard to

Load requirement of the internal combustion engine is necessary amount of fuel. Thanks to the dual system, it is thus very easy and fast to compensate for the insufficient amount of fuel. Advantageously, taking into account the determined evaporated portion of the fuel quantity, a distribution of a total amount of fuel to be introduced into the combustion chamber is determined on intake manifold injection and direct injection. 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, which is about the Pressure sensor determined filling higher than that determined by 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

Figures 1 a and 1 b show schematically two internal combustion engines, which can be used for a method according to the invention. Figure 2 shows schematically a cylinder of an internal combustion engine, which can be used for a method according to the invention.

FIG. 3 shows schematically a determination of a quantity of fuel by means of a method according to the invention in a preferred embodiment.

Embodiment (s) of the invention

FIG. 1 a shows schematically and simplified 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 has four combustion chambers 103 and a suction tube 106, which is connected to each of the combustion chambers 103.

The intake manifold 106 has a fuel for each combustion chamber 103! Njektor 107, 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 has a fuel! Njektor 1 1 1 for a direct injection on.

FIG. 1 b shows schematically and in simplified form 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 has four combustion chambers 103 and a suction tube 206, which is connected to each of the combustion chambers 103.

The intake manifold 206 has in this case for all combustion chambers 103 a common fuel injector 207, which is arranged in the intake manifold, for example, shortly after a throttle valve, not shown here. The first fuel! Njektor 207 thus serves a port injection. Furthermore, each combustion chamber 103 has a fuel injector 1 1 1 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 intake manifold injection shown in Figure 1 a individual fuel metering allowed for each combustion chamber, as can be used, for example, for higher quality internal combustion engines, the intake manifold injection shown in Figure 1 b is simpler in construction and its control. The two internal combustion engines shown may in particular be gasoline engines.

2, a cylinder 102 of the internal combustion engine 100 is schematically and simplified, but shown in more detail than in Figure 1 a. The cylinder 102 has a combustion chamber 103 which is enlarged or reduced by 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 admit air or an air-fuel mixture into the combustion chamber 103. The air is supplied via the suction pipe 106 of an air supply system to which the fuel injector 107 is located. Sucked air is admitted via the inlet valve 105 into the combustion chamber 103 of the cylinder 102. A throttle valve 12 in the air supply system serves 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 aid of the fuel injector 107, fuel is injected into the intake manifold 106 in the course of this intake manifold injection, so that an air-fuel mixture forms there, which is introduced into the combustion chamber 103 of the cylinder 102 via the intake valve 105.

The internal combustion engine can also be operated in the course of a direct injection. For this purpose, the fuel injector 1 1 1 is attached to the cylinder 102 to inject fuel directly into the combustion chamber 103. In this direct injection, the air-fuel mixture required for combustion is formed directly in the combustion chamber 103 of the cylinder 102.

The cylinder 102 is further provided with an ignition device 110 for generating a spark to start combustion in the combustion chamber 103. Combustion exhaust gases are expelled from the cylinder 102 via an exhaust removal section 108 after combustion. The ejection is dependent on the opening of an exhaust valve 109, which is also arranged on the cylinder 102. Inlet and exhaust valves 105, 109 are opened and closed to perform a four-stroke operation of the engine 100 in a known manner.

The internal combustion engine 100 can be operated with direct injection, with intake pipe injection or in a mixing operation. This allows the selection of the optimum operating mode for operating the internal combustion engine 100 depending on the current operating point. For example, the engine 100 may be operated in a port injection mode 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. Over a wide operating range, however, it makes sense to operate the internal combustion engine 100 in a mixed operation in which the amount of fuel to be supplied to the combustion chamber 103 is supplied proportionally by intake manifold injection and direct injection.

Furthermore, an air mass sensor 140 and an intake manifold pressure sensor 150 are provided in the intake pipe 106. The air mass sensor 140 may be, for example, a hot-film air mass meter whose mode of operation is known per se and which will not be explained in more detail here.

Furthermore, a computing unit designed as a control unit 1 15 for controlling the internal combustion engine 100 is provided. The control unit 15 can operate the internal combustion engine 100 in the direct injection, the intake manifold injection or the mixed operation. The air mass sensor 140 and the Saugrohrdruck- sensor 150 may be connected by a suitable connection to the control unit 1 15.

The operation of the internal combustion engine 100, which is explained in more detail with reference to FIG. 2, can also be transferred to the internal combustion engine 200, only with the engine 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 Figure 3, a determination of a fuel quantity by means of a method according to the invention in a preferred embodiment is shown schematically. First, an air quantity ML, which is to be introduced into the combustion chamber for a combustion cycle, is determined. For this purpose, for example, the air mass sensor 140 shown in FIG. 2 can be used. In particular, an air flow in the intake manifold 106 can be detected with the air mass sensor. By taking into account the opening duration of the inlet valve 105, it is therefore very easy to determine, for example, the air quantity ML relevant for the combustion cycle.

Furthermore, a fuel-air mixture quantity MKL, which is to be introduced into the combustion chamber for the combustion cycle, is determined. For this purpose, for example, the intake manifold pressure sensor 150 shown in FIG. 2 can be used. In particular, with the intake manifold pressure sensor, for example, a pressure difference between a time before introduction of the fuel by the fuel injector 107 into the intake manifold 106 and a time thereafter can be determined. 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 Μκ and the fuel-air mixture amount MKL 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, can from this evaporated fraction, the actually deposited in the intake manifold amount of fuel Μκ, which has been deposited by the fuel injector 107 and thus by the intake manifold injection into the intake manifold. The amount of fuel Μκ can now be used for example to check or plausibility of an associated target fuel quantity. Such a check can in particular also be carried out for the same combustion cycle. Furthermore, the amount of fuel Μκ can also be used to correct the setpoint

Injection amount, for example, be used on a change in the driving time 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, as shown, for example, in Figure 1 b, in the determination of the relevant for a combustion chamber air volume and fuel-air mixture amount, a division of the respective quantities must be considered in several combustion chambers.

Claims

claims

1 . Method for determining the vaporized portion of an amount of fuel (Μκ) of an internal combustion engine (100, 200) with intake manifold injection and direct injection which is emitted by intake manifold injection in the intake manifold (106), whereby an air quantity (ML) to be introduced into a combustion chamber (103) for a combustion cycle is determined,

wherein a for the combustion cycle in the combustion chamber (103) to be introduced fuel-air mixture amount (MKL) is determined, and

wherein, taking into account the amount of air (ML) and the fuel-air mixture amount (MKL) of the vaporized portion of the by means of intake manifold injection in the intake manifold (106) remote fuel amount (Μκ) is determined.

2. The method of claim 1, wherein from the vaporized portion of the deposited by means of the intake manifold fuel quantity (Μκ) is determined.

3. The method of claim 2, wherein from the vaporized portion taking into account an evaporation model, the offset by means of the intake manifold injection amount of fuel (Μκ) is determined.

4. The method of 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 charge of the combustion chamber (103) and / or Valve timing are taken into account.

5. The method according to any 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 (Μκ).

6. The method according to any one of claims 2 to 5, wherein a set by means of intake manifold injection target fuel quantity is corrected taking into account the determined amount of fuel (Μκ) for at least one subsequent combustion cycle.

7. The method of claim 6, wherein the target fuel amount by a change in a drive time and / or an opening duration of a respective fuel! Njektors (107) is corrected.

8. The method according to any one of claims 2 to 7, wherein the evaporated portion of the amount of fuel (Μκ) is controlled taking into account the determined amount of fuel (MK) to a desired value.

9. The method according to any one of the preceding claims, wherein a deviation of a deductible by means of intake manifold injection and direct injection total fuel amount, taking into account the vaporized portion of the determined fuel quantity is corrected by means of the direct injection.

10. The method according to any one of the preceding claims, wherein taking into account the vaporized portion of the determined amount of fuel (MK), a division of a total amount of fuel to be deducted on intake manifold injection and direct injection is determined.

1 1. Method according to one of the preceding claims, wherein the for the combustion cycle in the combustion chamber (103) to be introduced air quantity (ML) by means of an air mass sensor (140) is determined.

12. The method according to any one of the preceding claims, wherein for the combustion cycle in the combustion chamber to be introduced fuel-air mixture amount (MKL) by means of a Saugrohrdrucksensors (150) is determined.

13. Arithmetic unit (1 15), which is adapted to perform a method according to any one of the preceding claims.

14. Computer program, which causes a computing unit (1 15) to perform a method according to one of claims 1 to 12, when it is executed on the arithmetic unit (1 15).

15. A machine-readable storage medium having a computer program stored thereon according to claim 14.