DE10323671A1 - Method for operating an internal combustion engine - Google Patents

Abstract

The invention relates to a method for operating an internal combustion engine with N cylinders, an injection valve being assigned to each of the cylinders and the injection valve being controlled with an electrical variable G representing the desired needle stroke in order to set a desired needle stroke. Assuming a certain air mass supplied to the cylinder, the setting of the desired needle stroke serves to set a desired lambda value for the internal combustion engine. Methods known from the prior art for setting the desired lambda value for a cylinder by setting a corresponding needle stroke do not take into account that the air mass supplied to the individual cylinders can be different. If this is the case, an unchanged needle stroke leads to an incorrect lambda value. In order to prevent such an undesirable incorrect lambda value setting, it is proposed according to the invention to determine the electrical variable G¶i¶ specifically for the cylinder, that is to say in particular taking into account the air mass actually supplied to the individual cylinder.

Description

The The invention relates to a method for operating an internal combustion engine and in particular to control their injectors. The The invention further relates to a control device for operating the internal combustion engine as well as a computer program for such a control device.

Methods for quantity error compensation of injection valves of internal combustion engines are known in principle in the prior art, for example from DE 100 11 690 C2 or the DE 100 12 025 A1 , The methods known from these publications relate in particular to the adaptation of quantity tolerances in high-pressure fuel injection valves in shift operation (λ> 1) of the internal combustion engine; they are universal, which means that they can be used with fuel injectors of different designs and functions.

in the With regard to future Internal combustion engines with optimized beam guidance are high-pressure fuel injection valves have been developed in which the flow or Amount of fuel to be injected into the combustion chamber of the internal combustion engine over the injection time ti and / or over the needle stroke NH of the injection valve i is controlled.

On Desired λ value with λ = relative Air mass relative fuel mass becomes with these high pressure injectors adjusted in that with the air mass assumed to be known a correspondingly required fuel mass in the form of a sufficient Fuel flow is realized. The required fuel flow is realized in that a desired needle stroke for a sufficient ti is set for a long time. The desired needle stroke is in turn realized in that the injection valve with a desired this Representing the needle stroke controlled electrical quantity becomes.

at traditional methods for controlling injection valves, which pursue the goal of setting a certain λ value, however ignore let that due to the design the air mass supply of the internal combustion engine can scatter individually to the cylinder. In internal combustion engines, the Air is often sucked in through just one suction pipe. The air mass is usually only measured globally at one point and then it is assumed that the same proportion of the global air mass is supplied to all cylinders.

constructive however, the individual cylinders of the internal combustion engine are conditioned geometrically different from the outlet of the intake manifold. From it can Differences in the air mass supplied to the individual cylinders result. These differences remain in the air mass flow respectively these air mass errors are not taken into account and will be the one for the desired λ value to be set If the needle stroke is not corrected accordingly, this leads to undesirable Errors in the control of the internal combustion engine or Injectors with regard to the desired λ value to be set. Also the procedures described in the publications cited above Adaption of quantity tolerances for high pressure injectors such possible Air mass error except Eight.

outgoing from this prior art it is the object of the invention to provide a Procedure, a control unit and a computer program for operating an internal combustion engine to develop in such a way that with them increased accuracy in the metering of fuel and the setting of λ by the injectors the internal combustion engine can be realized.

This Object is achieved by the method claimed in claim 1 solved. Accordingly, the invention provides the electrical size is cylinder-specific to determine.

electrical Sizes for Control of the injection valves of an internal combustion engine in the sense The invention is in particular an electrical voltage, an electrical Electricity or an amount of electrical charge.

Advantages of invention

The cylinder-specific determination according to the invention the electrical size the advantage that any differences in the individual cylinders air mass supplied to the internal combustion engine can be taken into account when controlling the injection valves. at Control of an injection valve with the cylinder-specific according to the invention electrical size ensures that the injector is in terms of actual, air mass supplied to the respective cylinder correct needle stroke is set in order to set a desired λ value exactly. In other words, through the use of the cylinder-specific electrical quantity the metering of fuel through the injection valve to any existing ones Differences in the air mass supplied to the individual cylinders with regard to the desired one λ value to be set corrected or adjusted.

On first advantageous embodiment for Determination of the cylinder-specific electrical quantity is in the patent claims 2 and 3 claims.

On second advantageous embodiment The object is to determine the cylinder-specific electrical quantity of the dependent Claim 4. The second embodiment offers opposite the first embodiment continue to have the advantage that it is possible in addition to those already mentioned above Air mass errors additionally also fuel errors, that is Differences in the amount of fuel supplied to each cylinder can be included in the determination of the cylinder-specific electrical quantity.

The for the two embodiments necessary λ values to determine the electrical quantity preferably determined by cylinder-specific individual lambda detection.

The The above task is still operated by a control unit an internal combustion engine and by a computer program for such control unit solved. The advantages of these two solutions correspond to those mentioned above with reference to the described method Benefits.

drawings

The Description are attached to two figures, whereby

1 a first and a second embodiment of the method according to the invention; and

2 a control device according to the invention for operating an internal combustion engine
illustrated.

description of the embodiments

The Invention is described below in the form of two exemplary embodiments described in detail on the figures.

The The invention relates to a method for operating an internal combustion engine with a plurality of N cylinders, each of the cylinders i with i = 1 - N at least one injector is assigned. With the injectors are high pressure injectors, in which the fuel flow both over the Needle stroke as well as over the injection duration ti is controlled.

To set a desired stroke in the injection valve assigned to cylinder i, this injection valve is controlled with an electrical variable G _i representing the desired stroke. According to the invention, this electrical quantity G _i is determined cylinder-specifically. As described above, the cylinder-specific determination of the electrical variable G _{i has} the advantage that the design-related actual air mass supplied to the cylinder i is taken into account when determining the electrical variable G _i and thus when setting the appropriate stroke and the corresponding λ value.

1 illustrates a first exemplary embodiment for determining the cylinder-specific electrical variable G _i , in particular the amount of charge. This method provides that the internal combustion engine is initially operated in a so-called homogeneous operation, that is to say for example at λ = 1 (method step a)).

It then becomes a so-called adaptation area in a subsequent step b) within which a reference operating point can be selected appropriately can. As long as this adaptation area has not been defined, is the inventive method discontinued and instead there is always a return to the process step a) instead.

To successful starting of the internal combustion engine in the adaptation area the reference operating point becomes within this adaptation range set. The reference operating point stands out in particular characterized in that the speed of the internal combustion engine as well as the fed to her relative air mass are quasi-stationary.

Furthermore, λ = 1 in the reference operating point, for example, and preferably all the injection valves of the internal combustion engine, but in particular the injection valve assigned to the cylinder i, are _actuated with a first electrical reference _variable G _{Ref1 i} , which represents the reference _operating point.

This control takes place during an injection time ti _Ref (method step c)) which also belongs to the reference _{operating point} .

As soon as this reference operating point is set, it is checked whether at the internal combustion engine a single cylinder λ measurement is active (process step d)). As long as this is not the case, the method according to the invention begins into a waiting loop, which is caused by a return to process step c) is realized.

However, if the single-cylinder λ measurement is active, it is used to determine an actual λ value for each cylinder, which is set when the respective cylinder is operating at the reference operating point. These measured actual λ values are _subsequently compared with a first reference λ value λ _Ref1 representing the reference _{needle stroke} which is assigned to the reference _{operating point} . If it turns out in this comparison that the actual λ value for a specific cylinder is initially not equal to the cylinder- _independent reference λ value λ _Ref1 , the electrical variable G with which the cylinder i is controlled is based on the electrical reference _quantity G _{Ref1 i is trimmed} by such an amount ΔG _i that the actual λ value becomes equal to the reference λ value λ _Ref1 .

The cylinder-specific electrical variable G _{i according to the invention} is then calculated as the sum of the first electrical reference _variable G _{Ref1 i} and the amount ΔG _i .

In another case, if the actual λ value is equal to the reference λ value λ _{Ref1 from the beginning} , the first electrical reference _quantity G _{Ref1 i is defined} as the cylinder- _specific electrical quantity G _i (method step e)).

As long as the actual λ value is not yet equal to the reference λ value, the amount ΔG _{i is changed} in a suitable manner; this is in 1 indicated by the return from process step f) to the beginning of process step d).

However, if the actual λ value is equal to the cylinder- _independent reference λ value λ _Ref1 for at least one cylinder under consideration, the cylinder- _specific electrical variable G _i determined for this cylinder is stored and used for the future activation of the corresponding injection valve.

The cylinder- _specific first electrical reference _quantity G _{Ref1 i} required for the first _exemplary embodiment just described for determining the cylinder- _specific electrical quantity G _{i according to the invention} is determined for the injection valve of the cylinder i by carrying out the following steps. First of all, a standardized internal combustion engine with N cylinders, which is equipped with standardized injection valves on each cylinder, is operated in the reference operating range. The injection time ti _{Ref is} chosen so that all N cylinders of the standardized internal combustion engine have a uniform λ value of preferably λ = 1. The first electrical reference _variables G _{Ref1 i} are then determined for each cylinder i in such a way that the standardized needle valve assigned to the cylinder i _{sets the} reference _needle stroke specified by the reference operating point.

1 also illustrates a second exemplary embodiment for determining the cylinder-specific electrical variable G _i . Process steps a), b), d), f) and g) are essentially unchanged from the first embodiment. The only difference in this second exemplary embodiment compared to the first exemplary embodiment is that the N cylinders of the internal combustion engine are not all uniformly equipped with non-standard injection valves, but that at least one of the N cylinders is equipped with a standard injection valve.

In method step c '), the operating point for the internal combustion engine equipped in this way is set in such a way that all N cylinders, regardless of the injection valves with which they are fitted, are controlled with a predetermined second electrical reference _variable G _Ref2 . This second electrical reference variable is usually preset at the factory.

In a modified method step e ') according to 1 a second reference λ value λ _Ref2 is then subsequently _determined as the actual λ value of that cylinder which is equipped with the standard injection valve when this cylinder is operated at the operating point.

Within process step e '), the cylinder-specific electrical variable G _i for at least one of the cylinders i with i = 1 - N is then determined as follows, except for the cylinder which is equipped with the standard valve: Trimming of the electrical variable based on the predetermined second electrical reference _quantity G _Ref2 in _{such a} way that the previously determined cylinder- _independent second reference λ value λ _{Ref2 is} set for the cylinder i. This determination of the cylinder-specific electrical variable sought may be carried out iteratively, which is indicated by the 1 shown return from step f) to the beginning of step d) is indicated.

When the second reference λ value has finally been set and the associated electrical variable G _i for the cylinder i has been determined accordingly, this cylinder-specific electrical variable i is stored (method step g)) and in the future activation of the internal combustion engine instead of only being imprecise , second electrical reference variable specified at the factory for realizing a corresponding needle stroke.

2 shows a control unit 100 for operating an internal combustion engine, in particular for controlling injection valves which are assigned to the cylinders of the internal combustion engine. The control unit 100 is trained on the one hand, the cylin to determine the specific electrical quantity G _i according to one of the methods described in exemplary embodiments 1 or 2. In addition, the control unit 100 via a storage device 110 in order to store the cylinder-specific electrical variable G _i determined according to the invention therein and to be able to access it when the injection valves are actuated in the future.

The methods according to the invention described in exemplary embodiments 1 and 2 can also be implemented at least in part as a computer program. These computer programs, or more precisely, their program code, preferably run on a control unit 100 assigned computing device 120 ( 2 ), for example a microprocessor.

The Computer program can possibly together with other computer programs Control and / or regulation of the internal combustion engine on a computer-readable disk be saved. For example, the disk a floppy disk, a compact disc or a so-called flash memory act. The computer program stored on the mobile data carrier can be sold as a product to a customer. In case of a Realization as a computer program, it is still possible that Computer program possibly together with other computer programs to control and / or regulate the internal combustion engine - without the aid of the mobile data carrier - via an electronic one Communication network, especially the Internet, as a product to transfer a customer and sell that way.

Claims (8)

Method for operating an internal combustion engine with a plurality of N cylinders, wherein at least one injection valve is assigned to each of the cylinders i with i = 1-N, the injection valve being used to set a desired stroke, preferably the full stroke, for the injection valve assigned to the cylinder i is controlled with an electrical variable G representing the desired stroke; characterized in that the electrical quantity (G _i ) is determined specifically for the cylinder. Method according to Claim 1, characterized in that the cylinder-specific electrical variable G _i for the injection valve assigned to the cylinder i _starts from a first cylinder- _specific electrical reference _variable G _{Ref1 i} , with which a standardized reference _{valve is actuated} at a reference _operating point in order to set a predetermined cylinder- _independent reference _{needle stroke} is determined by executing the following steps: 2a) operating the internal combustion engine at the reference operating point, the injection valve of the cylinder i initially being controlled with the first electrical reference _variable G _{Ref1 i} ; 2b) determining the actual λ value which is set in the control according to step 2a) in the injection valve of cylinder i; 2c) comparing the actual λ value with a first reference λ value λ _Ref1 representing the reference _{needle stroke} ; and 2d1) trimming the electrical quantity G, with which the injection valve assigned to the cylinder i is _actuated to set the desired stroke, starting from the electrical reference _quantity G _{Ref1 i} , by an amount ΔG _i such that the actual λ value is equal to that Reference λ value λ _Ref1 is determined and the cylinder- _specific electrical variable G _{i in} accordance with G i = G Ref1 i + ΔG i . if the actual λ value is not initially equal to the reference λ value λ _Ref1 ; or 2d2) Define the cylinder-specific electrical quantity G _i to: G i = G Ref1 i . if the actual λ value is equal to the reference λ value λ _Ref . Method according to Claim 2, characterized in that the cylinder- _specific first electrical reference _variable G _{Ref1 i} for the injection valve of the cylinder i is determined by performing the following steps: 3a) operating a standardized internal combustion engine with N cylinders, each of which is equipped with a standardized injection valve, in the reference operating point located in an adaptation range, at which the injection time ti _Ref is selected such that all N cylinders of the standardized internal combustion engine have a uniform λ value of preferably λ = 1; and 3b) determining the first cylinder- _specific electrical reference _quantity G _{Ref1 i in} such a way that the standardized injection valve assigned to the cylinder i adjusts itself to the predetermined reference _needle stroke. Method according to Claim 1, characterized in that the cylinder-specific electrical variable G _i for controlling the injection valve assigned to the cylinder i into the desired stroke is determined on the basis of a predetermined cylinder-specific second electrical reference _variable G _{Ref2 i} by performing the following steps: 4a) operating the Internal combustion engine with N cylinders in an operating point lying in an adaptation range, one of the cylinders i with i = 1 - N being equipped with a standard injection valve and the remaining N - 1 cylinders are each equipped with non-standardized injection valves and all N cylinders are initially _controlled uniformly with the predetermined second electrical reference _variable G _Ref2 , which corresponds to the cylinder- _specific electrical variable G _i for the standard injection valve assigned to cylinder i; 4b) determining a second reference λ value as the actual λ value of the cylinder equipped with the standard injection valve when this cylinder is operated at the operating point; 4c) Determining the cylinder-specific electrical variable G _i for at least one of the cylinders i with i = 1 - N, except for the cylinder which is equipped with the standard valve, by trimming the electrical variable, starting from the predetermined second electrical reference _variable G _Ref2 in in such a way that the second reference λ value determined in step 4b) is established for the cylinder i. Method according to one of the preceding claims 2-4, characterized characterized in that the cylinder-specific actual λ values and the reference λ values determined by individual lambda detection for the respective cylinder , the actual λ values one actual needle stroke each and the reference λ values each represent a reference needle stroke. Control unit ( 100 ) for operating an internal combustion engine with N cylinders, each of the cylinders with i = 1 - N being assigned at least one injection valve, by actuating the injection valve with an electrical variable (G _i ) representing a desired stroke for the injection valve, characterized in that the electrical quantity (G _i ) is cylinder-specifically defined. Control device according to claim 6, characterized by a memory device ( 110 ) for storing the cylinder-specific electrical quantities G _i . Computer program for a control device ( 100 ) for operating an internal combustion engine, characterized by program code which is suitable for carrying out the method according to one of claims 1-5 if it is carried out on a computing device (in particular the control device) 120 ), for example a microprocessor.