WO2004016931A1

WO2004016931A1 - Method for improving the true running of an internal combustion engine

Info

Publication number: WO2004016931A1
Application number: PCT/DE2003/002005
Authority: WO
Inventors: Klaus Joos; Thomas Frenz; Markus Amler
Original assignee: Robert Bosch Gmbh
Priority date: 2002-07-25
Filing date: 2003-06-17
Publication date: 2004-02-26
Also published as: JP4327721B2; DE10233778A1; DE50309265D1; JP2005533969A; EP1527267B1; EP1527267A1

Abstract

Disclosed is a method for improving the true running of internal combustion engines, especially internal combustion engines with jet-guided petrol direct injection, wherein the true running is substantially improved by means of a variation of the lift of the injection valves.

Description

Method for improving the concentricity of an internal combustion engine

State of the art

The invention relates to a method for compensating for torque differences between the cylinders

Internal combustion engine, wherein the fuel injection system of the internal combustion engine has an injection valve with a variable stroke for each cylinder.

Due to the unavoidable manufacturing tolerances of components of the fuel injection system and the internal combustion engine, the individual cylinders of the internal combustion engine emit a different output or a different torque despite the same activation of the injection valves. This manifests itself in a non-circular running of the internal combustion engine, in particular in the part-load range and when idling.

DE 33 36 028 AI is a device for influencing control variables of an internal combustion engine known, with the help of the output of the individual cylinders individually regulated and approximated. This results in the desired smooth running of the internal combustion engine. The output control of the individual cylinders of the internal combustion engine is carried out by varying the injection duration.

In modern engine concepts, especially in internal combustion engines with spray-guided direct gasoline injection, a variation of the injection duration is not readily possible, since the injection duration has an influence on the mixture formation. As a result, the mixture formation can be negatively influenced by changing the injection duration and the ignition of the mixture formed in the combustion chamber cannot take place at the right time.

Advantages of the invention

The method according to the invention for compensating for differences in the cylinders of one

Internal combustion engine, the fuel injection system of the internal combustion engine having an injection valve with a variable stroke for each cylinder, the partial torques output by the cylinders of the internal combustion engine being recorded, a cylinder equalization factor being formed for each cylinder and the stroke of the injection valves depending on the cylinder

Corrected cylinder equalization factor allows an improvement in the concentricity of the internal combustion engine without changing the injection duration. Since the injection duration remains unchanged, the mixture formation in the combustion chambers of the internal combustion engine also does not change, so that there is no deterioration in the mixture formation and the ignition of the mixture. Since injectors with a variable stroke are already being used in series production, the method according to the invention can be implemented without additional costs, apart from the costs for programming the control unit.

It has proven to be particularly advantageous if electrically controlled injection valves, in particular piezo valves with injection nozzles opening outwards, are used as injection valves, since these have the

Injection quantity per unit of time by correcting the stroke of the injection valve as a function of

Cylinder equality factor can be done. The stroke can be corrected by correcting the control voltage or the charge applied to the piezo actuator. In the following, only a correction of the control voltage is spoken of in connection with the invention. This always means a correction of the load.

The conversion of the correction factor into a control voltage or a charge can also be done indirectly, for example by B. a target flow value or a target needle stroke or a target actuator stroke is corrected and this target value is then converted into a control voltage or a charge.

Correction of the control voltage is particularly simple if the control voltage is corrected by multiplication by the cylinder equalization factor. In these refinements of the method according to the invention, no changes to the injection system are necessary, with the exception of reprogramming the control unit. It has proven to be advantageous if the cylinder equalization factor is limited to a maximum value and a minimum value, so that the change in the valve lift of the injection valves is restricted to a range within which the valve lift can be controlled with sufficient precision.

If the cylinder equalization factor is greater than the present maximum value or smaller than the present minimum value, one can according to the following regulations

Correction factor for the injection duration can be calculated:

- The correction factor for the injection duration is 1.0 if the cylinder equalization factor is smaller than the maximum value and larger than the minimum value.

- The correction factor is equal to the quotient of the cylinder equalization factor and the maximum value if the cylinder equalization factor is greater than the maximum value.

The correction factor is equal to the quotient of the cylinder equalization factor and the minimum value if the cylinder equalization factor is less than the maximum value.

With these additional method steps, a good concentricity of the internal combustion engine can also be achieved if the tolerances of the internal combustion engine or the injection valves are relatively large. First, the concentricity is improved by changing the stroke of the injection valves. When this possibility has been exhausted, the small remaining correction range, which lies outside the maximum value and the minimum value of the cylinder equalization factor, is changed the injection duration covered. This change in the injection duration is relatively small and has no adverse effect on the mixture formation and the operating behavior of the internal combustion engine.

It has proven to be advantageous if the required injection quantity of the cylinder is multiplied by the correction factor and then converted into a cylinder-specific injection time.

The desired improvement in the smooth running of the internal combustion engine can also be achieved by a computer program or a control device for an internal combustion engine, which operate according to one of the previously described methods.

Further advantages and advantageous refinements of the invention can be found in the following drawing, its description and the patent claims.

drawing

The drawing shows:

Fig. 1: a block diagram of a first

Embodiment of the method according to the invention;

2 shows a block diagram of a second exemplary embodiment of the invention

process;

Fig. 3: a block diagram of the division of the

Cylinder equalization factor in a change in the charge or voltage and a change in Injection duration;

Fig. 4: a block diagram of the change in

Injection duration of the method according to the invention; and

5: an example of a variable stroke with a high pressure injection valve actuated by means of a piezo actuator.

Description of the execution example

Fig. 1 shows a block scarf. > ιld, based on which a first example of execution. 1 of the method according to the invention is described

Depending on the load requirements for the internal combustion engine (not shown), an electrically operated injection valve (not shown) with a control voltage Uansteuer,;., O. a charge Q _x driven. The index 'i' s-eιt for the number one

Cylinder. I = 1 to n if 'n' is the number of cylinders in the internal combustion engine. This is to express that the? "-: Your voltage ü _AnΞt your, or the charge Q in dependence; z of further parameters, which are not to be discussed further in connection with the invention, can be individually determined for each cylinder Z _± .

During the operation of the p-nkraftmaschine 5 are discharged from the cylinders of the internal combustion engine part moments Mo., the stungsabgabe to the TOTAL ^~ l of the internal combustion engine adder detected. The detection of the partial moments J. "eight must necessarily include a direct measurement, but it can, for example also the observation and measurement of the rotational speed of the crankshaft and a relation of this rotational speed with the ignition times of the cylinders of the internal combustion engine. If the partial torques Mi of the cylinders Z differ from one another within a working stroke of the internal combustion engine, the cylinder equalization factor is then formed for each cylinder, so that the smooth running of the internal combustion engine is improved taking into account the cylinder equalization factor.

In Fig. 1, the cylinder adjustment factor is designated FZ _GS T, _I. This Zyl_ "equality factor FZGST, _α will usually be different for jecl-_ι cylinder Z.

In order to arrive at a corrected control voltage U _A control, or a charge Q _{x of} the injector (not shown) of the cylinder Zi and, in consequence, a corrected stroke of the injector, the

Control voltage UAns-expensive, i, or the charge Q _x with the cylinder equalization factor FSGST, _a . multiplied. The product of the control voltage g U ^ control, ι and cylinder equalization factor F _3G sτ, i is the corrected control voltage or the charged charge.

2 shows a further exemplary embodiment of the method according to the invention as a block diagram. The main difference to the exemplary embodiment according to Fi i. 1 is that the cylinder equalization factor FZGST, i by a maximum value FZGST, Ma. and a 'minimum value F _ZG sτ, Mm is limited in a limiter 1.

The limiter 1 has that shown in FIG. 2 Characteristic curve, ie if the cylinder equalization factor is less than the minimum value F _ZG sτ, _Mm , the cylinder _{equalization factor} F _ZGST , _. is set equal to the minimum value FZGST, Mm and if the cylinder equalization factor FZGST, I is greater than the maximum value F _ZGST , Ma, the

Cylinder _{equalization factor} F _ZGST , _X equal to the maximum value FZGST, Ma.- replaced. Otherwise the remains

Cylinder _{equalization factor} F _{ZGST ι} unchanged. With the cylinder equalization factor F _ZG sτ _ι possibly changed by the limiter 1, in the same way as explained with reference to FIG. 1, the control voltage Ü drive, i, or the charge Q of the injection valve (not shown) is converted into a corrected control voltage, or a corrected charge (not shown) is converted.

3 describes the method which is used when the cylinder equalization factor F _ZG sτ is greater than the maximum value F _ZG sτ, Max or less than the minimum value FZGST, Mm. The basic idea behind this addition to the method is that the difference in the output of the cylinders Z _{x, which} cannot be compensated for by the stroke of the injection valve, occurs through a change in the cylinder-specific injection duration F _τ _ _e χnsprxt-., I.

For this purpose, it is checked whether the cylinder equalization factor

FZGST, I is greater than the maximum value F _ZG sτ, Ma. If this test is negative, a correction factor F _τ _emsprιtz is set to 1.0 for the duration of the injection. If the test is positive, the correction factor F _τ _eχnspri:, 1 is obtained by forming a quotient from the

Cylinder equalization factor F _ZG S _Γ , _X and the maximum value FZGST, Ma: formed.

By this measure, the part of the cylinder equalization factor that is not by a Change in the stroke of the injection valve can be taken into account by increasing the injection duration. The correction factor F _τ _exnsprxtz, x is greater than 1.0 in the case described last.

In parallel, it is checked whether the

Cylinder equalization factor F _2G sτ, smaller than the minimum value F _ZGST , xn. If this test is negative, the correction factor F _τ _ _e χnsprxtz, is set to 1.0. If this test is positive, the correction factor

from the quotient of the cylinder _{equalization factor} F _ZGS T, _X and the minimum value F _ZGST , Mn. In the last case described, the correction value F _τ _exnsprχtz, x now has a value less than 1.0.

4 shows how the injection time is corrected as a function of the correction factor Fτ_ _e χnΞ _P rχ z.

It is assumed that due to the

Load requirements for the internal combustion engine and other operating parameters a certain required amount of fuel is calculated by the control unit of the internal combustion engine. This required amount of fuel is multiplied by the correction factor F _τ _exnsprxtz, x, and an injection time for the cylinder Z concerned is then calculated from this multiplied required amount of fuel. Thus, even with cylinders whose operating behavior shows great differences due to manufacturing tolerances, very smooth running can be achieved, namely that part of the differences is compensated for by a cylinder-specific variation of the valve lift of the injection valves and the remaining part by a cylinder-specific variation of the injection duration of the injection valves. 5 schematically shows an injection valve 3 which is suitable for carrying out the method according to the invention. However, the invention is not restricted to this type of injection valve 3. The

Injection valve 3 consists of a nozzle body 5 in which a nozzle needle 7 is guided. At an end 9 of the injection valve 3 which projects into the combustion chamber of an internal combustion engine (not shown), a sealing seat (not shown) is formed in the nozzle body 5, which cooperates with the nozzle needle 7 such that when the nozzle needle 7 is opened, i.e. is moved to the left in the position shown of the injection valve 3, the nozzle needle 7 lifts from the sealing seat, not shown. A spiral spring 11, which is supported at one end on the nozzle body 5 and at the other end on the nozzle needle 7, moves the nozzle needle 7 into its sealing seat (not shown) when the injection valve 3 is switched off.

The nozzle needle 7 and thus that is actuated

Injection valve 3 by a piezo actuator 13. Between the piezo actuator 13 and the nozzle needle 7, an intermediate piston 15 is arranged, which, like the nozzle needle 7, is guided in the nozzle body 5. The area 17 of the nozzle body 5 indicated by the dashed circle 5, in which both the nozzle needle 7 and the intermediate piston 15 are guided, also serves as a hydraulic coupler between the piston 15 and the nozzle needle 7. The space between the piston 15 and the nozzle needle 7 is filled with fuel and transmits the rapid control movements, which are transmitted from the piezo actuator 13 to the intermediate piston 15, directly to the nozzle needle 7.

If the distance between the nozzle needle 7 and If intermediate piston 15 changes slowly, a certain amount of fuel leakage occurs between nozzle needle 7 and intermediate piston 15 on the one hand and nozzle body 5 in area 17, so that the changes in the distance between nozzle needle 7 and intermediate piston 15 are compensated for. The cause of changes in length of the injection valve 3 and consequently also the distance between the nozzle needle 7 and the intermediate piston 15 can be temperature changes of the injection valve 3.

A second spiral spring 19 presses the piston 15 against the piezo actuator 13, so that these two components are always connected to one another without play.

The fuel injector 3 is supplied with fuel via a fuel supply 21.

Claims

Expectations

1. A method for compensating for the differences in the cylinder moieties (Z _χ , with i = 1 to m)

Internal combustion engine, the fuel injection system of the internal combustion engine having an injection valve (3) with a variable stroke for each cylinder (Z _χ ), characterized by the following method steps:

- Detection of the partial torques (M ₁ ) delivered by the cylinders (Z _χ ) of the internal combustion engine,

- _Forming a cylinder _{equalization factor} (F _ZGST _ _α ) for each cylinder (Z and

Correcting the stroke of the injection valve (3) assigned to the cylinder [Z0 as a function of the cylinder equalization factor (F "_{C;; T (1} ).

2. The method according to claim 1, characterized in that the stroke of the injection valve (3) is corrected by correcting a control _voltage (U _{an3t =} , _{u = rι of} the injection valve (3) as a function of the cylinder _{equalization factor} (F _ZGSTι ).

3. The method according to claim 2, characterized in that the drive voltage (U _o.) By multiplication by the cylinder equalization factor _is corrected (F _{ZGST 1).}

4. The method according to any one of claims 1 to 3, characterized in that the cylinder _{equalization factor} (F _{ZGST; 1} ). Is limited to a maximum value (F _{ZGST / Ma} ).

5. The method according to any one of claims 1 to 4, characterized in that the cylinder _{equalization factor} ( ^F _ZGST , ^au ^ a minimum value (F _{ZGST (Hιn} ) is limited.

6. The method according to any one of claims 4 or 5, characterized in that a correction factor (F _{τ eιnsprltZ / 1} ) for the injection _{duration is} calculated according to the following regulations:

- The correction factor (F _{τ eιnsprιt} - ₍₁ ) is equal to 1.0 if the cylinder _{equalization factor} (F _ZGSTji ). _Is smaller than the maximum value (F_ _{GST ria} .) And larger than the minimum value (F ^L ZGST, Mιn) ' ^J i - ^Ö st ^L.

- The correction factor (F _{τ βιnSDrιt} - ₍₁ ) is equal to the quotient of the cylinder _{equalization factor (} F _{ZGST (1} ) and maximum value

(F _ZGSTMa ) if the cylinder _{equalization factor} (F _ZGSTfla ) is _greater than the maximum value (F _ZGSTιMa ,).

- The correction factor (F _{τ = JLnsDr} , _r . _{# 1} ) is equal to the quotient of the cylinder _{equalization factor} (F _zG ). _{And the} minimum value (F _ZGSTMιn ) if the cylinder _{equalization factor (} F _{ZG3T (1} ) is smaller than the minimum value (F _7rsτ,. _n ) is.

7. The method according to claim 6, characterized in that the required injection _{quantity of} the cylinder (Z is multiplied by the correction factor (F _{τ sιnsprιt :: ιi} ) and then converted into a cylinder- _specific injection time ^T _E i _nsPr . _T -_.

8. The method according to any one of the preceding claims, characterized in that it is provided for use in internal combustion engines with gasoline direct injection, in particular with spray-guided gasoline direct injection.

9. Computer program, characterized in that it works according to one of the preceding methods.

10. Computer program according to claim 9, characterized in that it can be stored on a storage medium.

11. Control device for an internal combustion engine, in particular for an internal combustion engine with gasoline direct injection, characterized in that it works according to one of the methods according to one of claims 1 to 8.