DE102008054773A1 - Retarded ignition angle limiting value correcting method for otto engine, involves determining irregular operation measure, and correcting retarded ignition angle limiting value by control ignition angle based on measure - Google Patents

Abstract

The method involves providing a required ignition angle for operating an internal combustion engine (2). The internal combustion engine is controlled with a control ignition angle, which is based on the required ignition angle and a retarded ignition angle limiting value that defines an adjustable ignition point for maximum permissible irregular operation of the engine. An irregular operation measure is determined by the control angle, where the measure indicates irregular operation of the engine. The retarded value is corrected by the control angle based on the determined measure. Independent claims are also included for the following: (1) a device for correcting a retarded ignition angle limiting value for an internal combustion engine (2) a computer program comprising instructions executed by a data processing unit to perform a method for correcting a retarded ignition angle limiting value for an internal combustion engine.

Description

Technical area

The The invention relates to internal combustion engines, in particular to methods for Limiting a late adjustment a firing angle by a spark ignition angle limit.

State of the art

At the Operating Otto internal combustion engines can torque changes be implemented in different ways. These possibilities include in the reducing direction u. a. a throttling of the air supply, a Adjustment of the ignition angle and injection fades one or more cylinders.

Especially the throttling of the air supply provides a relatively slow engagement path for the torque change for Therefore, quick torque interventions are preferably adjustments in practice the ignition angle used, which almost instantaneous torque changes can be implemented.

Of the Structure of a torque reserve is a measure of the engine control, where - ever according to the size of the item to be provided Torque reserve - the firing angle reduced while keeping the engine torque constant is, d. H. after late is shifted by a rapid increase in the ignition angle, d. H. moving one early, realize a fast torque build-up in sufficient height to be able to. Thereby can forthcoming and expected torque requirements of auxiliary equipment, such as B. an air conditioner, or sporadic torque requirements be prepared and almost immediately by an immediate early shift the ignition angle be accurately compensated. The determination of the engine operation and the Providing the torque reserve necessary ignition angle is known in the Way in the engine control unit carried out.

Usually is a late ignition angle limit as lower limit (late limit) for the firing angle operating point defined for standard motors, that depends on the border, up to which the internal combustion engine has sufficient smoothness or from which the internal combustion engine has too high a rough running. D. h., The required ignition angle falls below the Spätzündwinkelgrenzwert, is an elevated one Given probability of misfiring or one Combustion no longer takes place completely. Therefore, usually the required ignition angle to the late ignition angle limit value limited.

however can this Spätzündwinkelgrenzwert on the Lifespan of the internal combustion engine vary, with new internal combustion engines the rough running limit usually is set further than that of aged combustion engines the case is. This is mainly because older internal combustion engines through Wear or Deposits tend to run less smoothly. In addition, work also tolerances in the production of internal combustion engines the motor-individual limit value for the Spätzündwinkel off.

It is therefore an object of the present invention, a method and a device available on the one hand, the retardation of ignition angles limited to avoid unruly operation of the internal combustion engine and on the other hand the potential of retarding the firing angle best possible exhausted becomes.

Disclosure of the invention

These Task is by the method for correcting a Spätzündwinkelgrenzwertes an internal combustion engine according to claim 1 and by the device and the engine system according to the siblings claims solved.

Further advantageous embodiments of the invention are specified in the dependent claims.

• – Vorgeben eines geforderten Zündwinkels zum Betreiben des Verbrennungsmotors;
• – Ansteuern des Verbrennungsmotors mit einem Ansteuer-Zündwinkel, der von dem geforderten Zündwinkel und von dem Spätzündwinkelgrenzwert abhängig ist, wobei der Spätzündwinkelgrenzwert eine Angabe für einen Zündwinkel darstellt, der einen spätest einstellbaren Zündzeitpunkt für eine maximal zulässige Laufunruhe des Verbrennungsmotors definiert;
• – Ermitteln eines Laufunruhemaßes, das eine Laufunruhe des Verbrennungsmotors angibt, bei dem Ansteuer-Zündwinkel;
• – Korrigieren des Spätzündwinkelgrenzwertes abhängig von dem ermittelten Laufunruhemaß bei dem Ansteuer-Zündwinkel.

According to a first aspect, a method is provided for correcting or adapting a spark advance angle limit value for an internal combustion engine to be controlled by means of a specification of an ignition angle. The method comprises the following steps:

• - Specifying a required ignition angle for operating the internal combustion engine;
• - driving the internal combustion engine with a drive firing angle that is dependent on the required firing angle and the Spätzündwinkelgrenzwert, the Spätzündwinkelgrenzwert represents an indication of a firing angle that defines a latest adjustable ignition timing for maximum allowable engine noise;
• - Determining a Laufunruhemaßes that indicates a rough running of the engine, at the driving firing angle;
• - Correcting the Spätzündwinkelgrenzwertes depending on the determined Laufunruhemaß at the driving firing angle.

One idea of the above method consists in correcting or adapting the conventionally set limit for late ignition angles during operation of the internal combustion engine, so that a value corresponding to the instantaneous state of the Ver combustion engine optimal Spätzündwinkelgrenzwert can be provided. The optimal Spätzündwinkelgrenzwert corresponds to a limit to which a possible exposure-free operation of the engine is possible, ie to which indicates the Laufunruhemaß that the engine can be operated with just enough quietness.

Farther may correct the spark advance angle limit with the aid of a firing angle correction value carried out become. In particular, the ignition angle correction value be selected depending on the Laufunruhemaß.

According to one embodiment can at a required ignition angle, the later ignition point defined as the late ignition angle limit, the internal combustion engine first with the late ignition angle limit value controlled as drive firing angle and then the drive firing angle and the late ignition angle limit in the direction of the required ignition angle be tracked until the appropriately determined running noise level reaches a predetermined limit, the maximum allowable Defined unrest, reached.

Farther can the Spätzündwinkelgrenzwert with the required ignition angle be equated or compared to a firing angle with one to the required ignition angle later ignition point be set if that when reaching the required ignition angle through the drive firing angle determined running disturbance measure is smaller as the default limit.

Farther can at a required ignition angle, the one earlier ignition timing defined as the late ignition angle limit, the internal combustion engine with the required ignition angle as the driving ignition angle controlled and the Laufunruhemaß at the driving firing angle be determined, the Spätzündwinkelgrenzwert to the required ignition angle or to a firing angle, the former ignition as the required ignition angle is defined, if corrected at the drive firing angle determined run disorder one specified limit, which defines the maximum allowable running noise exceeds.

It can be provided that the process is continuous or too fixed times or depending on engine conditions, in particular depending on a moment intervention is performed.

Further can the specification of the required ignition angle according to a Request to build up a torque reserve or a fast Torque reduction performed become.

Farther may correct the spark advance angle limit operating point or operating range depends carried out become.

• – eine Einrichtung zum Vorgeben eines geforderten Zündwinkels zum Betreiben des Verbrennungsmotors;
• – eine Einrichtung zum Ansteuern des Verbrennungsmotors mit einem Ansteuer-Zündwinkel, der von dem geforderten Zündwinkel und von dem Spätzündwinkelgrenzwert abhängig ist, wobei der Spätzündwinkelgrenzwert eine Angabe für einen Zündwinkel darstellt, der einen spätest einstellbaren Zündzeitpunkt für eine maximal zulässige Laufunruhe des Verbrennungsmotors definiert;
• – eine Einrichtung zum Ermitteln eines Laufunruhemaßes, das eine Laufruhe des Verbrennungsmotors angibt, bei dem Ansteuer-Zündwinkel;
• – eine Einrichtung zum Korrigieren des Spätzündwinkelgrenzwertes abhängig von dem ermittelten Laufunruhemaß.

According to a further aspect, an apparatus is provided for correcting a spark ignition angle limit value for an internal combustion engine to be controlled with the aid of a specification of an ignition angle. The device comprises:

• - means for setting a required ignition angle for operating the internal combustion engine;
• A means for driving the internal combustion engine having a drive firing angle dependent on the required firing angle and the spark retard angle limit, the retarded firing limit representing an indication of a firing angle defining a latest adjustable spark timing for maximum allowable engine rotor noise;
• A means for determining a running disturbance indicative of smooth running of the internal combustion engine at the driving firing angle;
• - A device for correcting the Spätzündwinkelgrenzwertes depending on the determined Laufunruhemaß.

According to one Another aspect is an engine system with an internal combustion engine and the above device.

According to one another aspect is provided by a computer program that, if it is performed on a data processing unit, the above method performs.

Brief description of the drawings

preferred embodiments will be explained in more detail with reference to the following drawings. Show it:

1 a schematic representation of an engine system with an internal combustion engine; and

2 a flow diagram illustrating a method for correcting a Spätzündwinkelgrenzwertes.

Description of embodiments

1 shows a schematic representation of an engine system 1 with a gasoline engine as an internal combustion engine 2 , The internal combustion engine 2 is by means of control signals AS, in an engine control unit 3 be generated, driven. The drive signals AS serve to provide an output variable of the internal combustion engine predetermined by a default variable VG 2 , The output can be a speed, a torque ment, engine power or the like. The default variable VG may, for example, a driver's desired torque and / or other input variables, such. B. specifications about upcoming torque interventions, speed specifications, engine performance specifications and the like.

The drive signals AS serve to the internal combustion engine 2 to control so that the default variable VG is implemented as possible, ie that of the internal combustion engine 2 provided output corresponds. For this purpose, the control signals AS can be a control signal for a throttle valve, an injection signal for determining times and durations of injection of fuel or for determining an injection quantity of fuel to be injected, either into a suction pipe of the internal combustion engine 2 or directly into the cylinder of the internal combustion engine 2 include. Furthermore, the control signals AS an ignition signal, by which the timing for igniting a spark plug in a corresponding cylinder of the internal combustion engine 2 is specified. The timing of the ignition signal determines an ignition angle ZW, which is the angle of a crankshaft of the internal combustion engine 2 relative to a top dead center indicates the piston movement in a cylinder.

From the internal combustion engine 2 Motor sizes MG are recorded with the help of sensors and these in the engine control unit 3 provided in a suitable manner, so that the engine control unit 3 the control of the internal combustion engine 2 can perform according to the current operating state or according to the current operating point. Such engine quantities MG may include the rotational speed, the temperature, the air charge, pressures in the air supply system and / or in the cylinder a lambda value and the like.

Around a quick moment intervention to reduce the delivered Torque or to build up a torque reserve to realize is usually the ignition angle reduced, d. H. the ignition point will be late shifted, so the thermal efficiency of the internal combustion engine to reduce. In this way, either the output torque be reduced or it can be built up a torque reserve. The structure of the torque reserve is carried out while maintaining the delivered torque. This is the deterioration of the efficiency by an increase offset the air flow, so that the retardation of the ignition angle carried out torque neutral can be.

However, the ignition angle is basically not arbitrarily adjustable late, but is limited by a limit, by the rough running behavior of the internal combustion engine 2 is determined. This limit value has hitherto been determined by a fixed predetermined ignition angle limit value, which is spaced apart from the value above which uneven running behavior occurs in the case of an unaged reference internal combustion engine with a safety margin or tolerance interval.

According to the proposed method, the spark ignition angle limit value is corrected and thereby substantially permanently to the current state of the internal combustion engine 2 customized.

In 2 a flow chart illustrating the method for correcting the Spätzündwinkelgrenzwertes is shown. The method begins with a step S1, in which a firing angle from the engine control unit 3 is provided, resulting from the desired instantaneous control of the internal combustion engine 2 results. It is checked in step S1 whether a late shift of the ignition angle ZW is requested (alternative: yes) or not (alternative: no). There are various possibilities and cases are conceivable in which the ignition angle ZW is reduced compared to its optimum value, that is adjusted to late, so as to realize a specific engine operation. Often, the ignition angle ZW torque neutral is retarded to build up a so-called torque reserve, so that when connecting an accessory immediately an additional drive torque can be provided by a corresponding early shift of the firing angle.

In a following step S2, which is carried out in the presence of a request for a retard of the ignition angle ZW, it is checked whether the provided ignition angle is in the operating range permitted by the current late ignition angle limit value or not. Ie. It is checked whether the provided ignition angle ZW is greater than or equal to the Spätzündwinkelgrenzwert at the current operating point of the internal combustion engine 2 or smaller than the late ignition angle limit value at the current operating point of the internal combustion engine 2 , The current operating point or operating range can be defined by a rotational speed or a rotational speed range and / or a current load or a current load range and / or a torque or a torque range. The acceptable with respect to just allowable uneven running late sparkle differ z. T. significantly depending on the engine operating range.

If it is determined in step S2 that the ignition angle is later (smaller) than the Spätzündwinkelgrenzwert at the current operating point or in the current operating range (alternative: no), it is still checked in step S3 whether the required ignition angle to build a Mo reserves or has been requested due to a rapid torque reduction. If it is the structure of a torque reserve (alternative: Yes), then in a step S4 first drive signals AS for the internal combustion engine 2 generated and output to the latter, wherein the control signals AS correspond to the applicable for the operating point or operating range in step S2 uneven running limit.

In a subsequent step S5, a running disturbance measure is provided or determined. The running disturbance measure represents an indication that indicates how evenly the internal combustion engine 2 runs or works, ie a measure of whether z. B. misfires occur or there is a Drehzahlunregelmäßigkeit. The running disturbance gauge is defined to be indicative of deteriorated combustion behavior in the internal combustion engine 2 can show. Depending on the definition, a running rest gauge can also be used instead of the running wheel interference.

In step S6, a query is made as to whether the running irregularity is sufficiently quiet running behavior of the internal combustion engine 2 signaled, z. By determining whether the rotational speed irregularity is less than a previous threshold or whether the fraction of combustion misfires with respect to the total number of combustions is above a threshold level. If sufficient running smoothness is determined in step S6 (alternative: yes), then in a step S7 the delayed ignition angle limit value is incrementally extended (reduced), eg reduced, for a later time. B. by a Zündwinkeldifferenz ΔZW approximately between 0.5 and 2 degrees. This process ends at the latest where either the Sollspätzündwinkel or an absolute Spätzündwinkelimimit is reached.

From step S7, it returns to step S1. If the requirement of the ignition angle, which leads to a retardation of the ignition angle, still exists, the method is continued after step S1 to step S2, from which step is continued to step S3, if the requested ignition angle is below the new running noise limit. In step S4, drive signals AS for the thus reduced uneven running limit value are then sent to the internal combustion engine 2 provided. The internal combustion engine 2 is then operated with a (lower) firing angle going beyond the original imprecision threshold. In step S5, the run disturbance is then again provided.

Becomes determined in step S6 that the necessary smoothness is not more is given (alternative: no) or that the Laufunruhe too becomes big, so at a step S8, the spark ignition angle limit value on the last detected ignition angle adjusted, in which a sufficient smoothness was present, and it is returned to step S1.

If, in step S2, the requested ignition angle is greater (ie more positive) or equal to the uneven running limit determined by the operating point or operating range (alternative: yes), then the ignition angle ZW provided is first of all supplied to the internal combustion engine in a step S10 2 output.

In Step S11, the Laufunruhemaß is determined and in step S12 checks if at the set ignition angle a sufficient smoothness is given. This is not the case (Alternative: No), so in step S13, the Spätzündwinkelgrenzwert incrementally, e.g. By ΔZW, in the direction of early moved (enlarged) and the ignition angle to be set accordingly adjusted, if this after changing the Spätzündwinkelgrenzwerts beyond this late ignition angle limit lies. If there is sufficient smoothness in step S12, then is returned to step S1.

The Process steps S4 to S8 are therefore for relatively slow torque requests preferably used (especially in the formation of a torque reserve). For fast torque reduction requests requesting large spark advance angles however, (alternative: no, step S3) is via an optional step S9 has jumped to step S10, in which case the ignition angle is set even if this is over the late ignition angle limit lies. The optional step S9 may serve to update the current one firing angle to a firing angle to limit the previous (previous inflow) firing angle only by a certain ignition angle difference, such as B. 3 ° KW below. Thus, the required torque reduction dynamic to be accurately set. Should the running disturbance measure misfiring, d. H. a big Uneven running, indicate in S11, responds accordingly in S12.

The above-described method for correcting the spark advance angle limit value represents only one of a number of possible correction methods. However, in the formation of a torque reserve, setting an ignition angle that is later (smaller) than the ignition angle indicated by the spark ignition angle limit value is initially the latter as the ignition angle the internal combustion engine is specified and then a successive approach to that of the engine control unit 3 required ignition angle ZW is carried out as long as the Laufunruhemaß, which is preferably determined continuously during each combustion process, a no longer found sufficient. It is assumed the last ignition angle at which a sufficient smoothness was present. Is already an insufficient smoothness when setting the late ignition angle limit as ignition angle ZW for the internal combustion engine 2 determined, the ignition angle of Spätzündwinkelgrenzwertes is correspondingly increased and accordingly also the internal combustion engine 2 provided firing angle increased until a sufficient smoothness, indicated by the Laufunruhemaß achieved.

Especially during a cold run of the internal combustion engine 2 , in which frequently a motorized heating of the catalyst is provided, a significant retardation of the ignition angle may be required. If the above procedure for correcting the rough running limit is reduced, the range of the catalyst heating required to pass an exhaust test may be limited. In order to meet the set requirements, restricting the range later to firing angles could be indicated by more than a certain amount, for example, by a spark retard limit limit that is limited from the original value. B. by a visual display. This diagnostic result could also be output to an external test device.

Next the late ignition angle limit, which is permanently corrected in the manner described above, can be fixed predetermined adaptation limits can be provided, the u. a. also physical Limits for possible firing angle define. A correction of the rough running limit over this firmly predetermined adaptation limits is preferably prevented, there outside In this area, the learning process would be implausible.

Basically, there are different late ignition angle limits for different operating ranges of the internal combustion engine 2 expected. When changing the operating point or operating range of the internal combustion engine, for. B. by speed change or a load / torque change, the respective correction value of Spätzündwinkelgrenzwertes stored for the previous operating range and the corresponding correction value of Spätzündwinkelgrenzwertes retrieved for the newly occupied operating range and corrected according to the adaptation method.

As an additional adaptation algorithm, an integration method can be used, wherein the current Spätzündwinkelgrenzwert the ignition angle dependent on the operating range is shifted by means of a Zündwinkeldifferenz ΔZW. The following applies: ΔZW (load, speed) = k · ∫ t 0 (ALU - BLU) dt where k is an integration constant, BLU is an indication of a base limit running disturbance, ie, a generally required maximum running noise, and ALU is an indication of a current running noise (eg, the standard deviation of the engine speed). Ie. In this example, the running noise is assumed as a running disturbance measure. Of course, the smoothness can be used as Laufunruhemaß taking into account the sign.

The Integration constant k describes the sign-conformant conversion in a Zündwinkelmaß. The sign convention for ΔZW is such that at k> 0 the current one Zündwinkelgrenze early (Direction positive) is pulled, otherwise moved late or maintained.

Preferably If the integration constant k is assigned different amounts according to the situation, d. H. k has different amounts depending on Sign of the difference between the current uneven ALU and the base border runoff BLU. This will achieve that the late ignition angle limit the ignition angle slowly increase the range Runniness approximates.

If however, one firing angle which leads to a bad smoothness, should the area of the Run unrest quickly leave again (larger amount for k).

• – wenn der absolute Adaptionsgrenzenbereich des Zündwinkels verlassen wird,
• – bei negativem Argument (d. h. ALU < BLU),
• – aktuellem Zündwinkel diesseits der aktuellen Laufruhe(zündwinkel)grenze: hier darf keine Verschiebung stattfinden, da keine Veranlassung dafür gegeben ist.

In particular, k, by setting the value 0, ensures that the otherwise permanent integration over the time t or over the operating cycles of the internal combustion engine is aborted in the following cases (integrator stop):

• If the absolute adaptation limit range of the ignition angle is left,
• - if the argument is negative (ie ALU <BLU),
• - Current ignition angle on this side of the current smoothness (ignition angle) limit: here, no shift may take place, since there is no reason for it.

Of the Initial value for the late ignition angle limit in a new internal combustion engine should correspond to the one who for a reference engine in a calibration phase under standard conditions has been determined.

Analogous For example, a recursive algorithm may be provided in which the ignition angle difference is the late ignition angle limit compared to the preset delayed ignition angle limit value is postponed, depending of a weighted difference between the reference runtime and the current running discomfort.

The method for correcting the delayed ignition angle limit value can be performed permanently, temporarily or at predetermined times. Outside the times during which the correction method is applied, the spark ignition angle applies limit as the absolute limit of the ignition angle to be set.

at the embodiments described herein correspond to smaller ignition angles a later one ignition timing and vice versa. It is of course also possible to embodiments to modify so that earlier ignition times are defined by smaller ignition angle or by larger ignition angle latter ignition To be defined.

Claims (12)

Method for correcting a spark advance angle limit value for an internal combustion engine to be controlled with the aid of a specification of an ignition angle ( 2 ), comprising the following steps: predetermining (S1) a required ignition angle (ZW) for operating the internal combustion engine ( 2 ); - driving (S4) of the internal combustion engine ( 2 ) with a triggering firing angle which is dependent on the required firing angle and on the spark retard angle limit value, the retarded firing limit value representing an ignition angle indicative of a most recently adjustable firing point for maximum allowable running noise of the internal combustion engine ( 2 ) Are defined; Determining (S5) a running disturbance that causes a running noise of the internal combustion engine ( 2 ) indicates at the drive firing angle; - Correcting (S7) the Spätzündwinkelgrenzwertes depending on the determined Laufunruhemaß at the driving firing angle. The method of claim 1, wherein said correcting of the delayed ignition angle limit value with the aid of a firing angle correction value carried out becomes. The method of claim 2, wherein the ignition angle correction value is selected depending on the Laufunruhemaß. Method according to one of claims 1 to 3, wherein at a required ignition angle (ZW), which defines a later ignition point than the Spätzündwinkelgrenzwert, the internal combustion engine ( 2 ) is first controlled with the Spätzündwinkelgrenzwert as the triggering firing angle, and then the driving firing angle and the Spätzündwinkelgrenzwert in the direction of the required ignition angle (ZW) are tracked until the appropriately determined Laufunruhemaß reaches a predetermined limit, which defines the maximum allowable running noise. The method of claim 4, wherein the late ignition angle limit with the required ignition angle (ZW) is equated or compared to a firing angle with one to the required ignition angle later ignition timing is set, if that when reaching the required ignition angle by the drive firing angle determined running disturbance measure smaller is the default limit. Method according to one of claims 1 to 5, wherein at a required ignition angle (ZW), which defines an earlier ignition time than the Spätzündwinkelgrenzwert, the internal combustion engine ( 2 ) is controlled with the required ignition angle (ZW) as the driving ignition angle and the Laufunruhemaß is determined at the driving firing angle, the Spätzündwinkelgrenzwert is corrected to the required firing angle or to a firing angle that defines an ignition timing earlier than the required firing angle, if the running disturbance measure determined at the driving firing angle exceeds a predetermined limit value defining the maximum allowable running disturbance. Method according to one of claims 1 to 6, wherein the method continuously or at fixed times or depending on Engine conditions, in particular dependent from a moment's intervention. Method according to one of claims 1 to 7, wherein the pretending the required ignition angle (ZW) according to a Request to build up a torque reserve and / or a fast Torque reduction performed becomes. Method according to one of claims 1 to 8, wherein the correcting of the delayed ignition angle limit value operating point or operating range dependent is performed. Device for correcting a retarded ignition angle limit value for an internal combustion engine to be controlled with the aid of a specification of an ignition angle ( 2 ), comprising: - means for setting a required ignition angle (ZW) for operating the internal combustion engine ( 2 ); - a device for controlling the internal combustion engine ( 2 ) having a drive firing angle that is dependent on the required firing angle (ZW) and the spark retard angle limit, the retarded firing threshold representing an indication of a firing angle that defines a latest adjustable spark timing for maximum allowable engine noise; A device for determining a running irregularity that causes a running noise of the internal combustion engine ( 2 ) indicates at the drive firing angle; - A device for correcting the Spätzündwinkelgrenzwertes depending on the determined Laufunruhemaß at the driving firing angle. Engine system with an internal combustion engine ( 2 ) and a device according to claim 10. Computer program that when it is on a computing device accomplished is a method according to a the claims 1 to 9 executes.