DE10141842A1 - Method, computer program, control and / or regulating device for operating an internal combustion engine, and internal combustion engine - Google Patents

Abstract

According to the invention, the exhaust gases of an internal combustion engine are supplied to a catalyst. The invention aims at reducing fuel consumption with a novel catalyst, and at achieving a high degree of conversion with a used catalyst. Therefor, the internal engine exhaust gas energy depends on the current capacity (SO2) of the catalyst.

Description

State of the art

The invention initially relates to a method for operating an internal combustion engine in which the exhaust gases Catalyst are supplied.

Such a process is known from the market. It will for example in internal combustion engines with petrol Direct injection used. With these the Fuel directly from the respective combustion chambers assigned injectors into the combustion chambers of the Internal combustion engine injected. such Internal combustion engines can be operated in a so-called "shift operation" work. In this the air supply is largely dethrottled. Furthermore, the fuel is in the Combustion chambers injected only in the area of the spark plug there is an ignitable mixture, whereas the rest Combustion chamber has little or no fuel.

In "homogeneous mode", in which the internal combustion engine can also work, the fuel is in the Mainly distributed homogeneously in the combustion chamber. The exhaust gases are over from the combustion chambers of this internal combustion engine an exhaust pipe removed and fed to a catalyst. In this catalyst is harmful emissions, which in Exhaust gases are contained in less harmful or converted harmless emissions.

For the conversion of harmful exhaust gas components however, the catalyst has a certain minimum temperature exhibit. At this minimum temperature after a cold start to reach the internal combustion engine as quickly as possible hence engine efficiency for a given time for example, by shifting the ignition timing deteriorated late by a predetermined, fixed amount and thus increases the exhaust gas temperature. This will again accelerates the heating of the catalyst. A however, higher temperature means higher exhaust gas energy. Because this energy is not converted into useful power the overall efficiency of the internal combustion engine is lower. Ultimately, this measure also Fuel consumption of the internal combustion engine increases.

The object of the present invention is a method of the type mentioned in such a way that the Fuel consumption when operating the internal combustion engine is lowered.

This task is initiated in a procedure mentioned type in that the exhaust gas energy of Internal combustion engine from the current performance of the Catalyst depends.

Advantages of the invention

Basically, the conversion rate, that is Performance of today's catalysts, including theirs Age dependent. At the same time, the conversion rate is too of an aged catalyst better at higher temperatures than at low temperature. To also use an "old" Catalyst to achieve a conversion rate which compliance with today's emissions standards is therefore made possible So far the internal combustion engine like this set them with poorer efficiency works as the optimal efficiency. This gives a higher exhaust gas energy. This heats the catalytic converter so that even with an old catalytic converter another one sufficient conversion rate is ensured.

The measure according to the invention is such a measure fundamental and rigid deterioration of the Efficiency of the internal combustion engine no longer required. In the present invention, the Exhaust gas energy from the internal combustion engine instead always so set that for each state of aging of the Catalyst its temperature just high enough is that the necessary conversion is possible. The Internal combustion engine can therefore, as long as the catalyst is still "Young" is and also comparatively lower Temperature a high conversion rate or Performance, with high efficiency and operate accordingly low exhaust gas energy. On However, high efficiency of the internal combustion engine means at the same time reduced fuel consumption.

The measure according to the invention is thus during a significant part of the life of the internal combustion engine or the catalyst fuel consumption Internal combustion engine lowered. At the same time ensures that the exhaust gas passes over the catalyst total lifespan roughly with that energy (temperature, Speed, duration, etc.) which is is at least required to maintain a temperature of To generate catalyst with a desired Conversion rate can be achieved. It goes without saying that the inventive method equally Internal combustion engines with gasoline direct injection as well for those with intake manifold injection can.

Another advantage of the method according to the invention is that partially damaged or severely aged catalysts the exhaust and thus the The catalyst temperature is set sufficiently high can be that the required conversion rate from Catalyst is still achieved. This will Risk of misdiagnosis of the catalyst eliminated, see above that prevents unnecessary replacement of the catalyst can be.

Under the term "exhaust gas energy" the parameters are here Exhaust gas temperature, exhaust gas mass flow, and / or duration of the Effect of the exhaust gases understood on the catalyst. Under the term "age" or "aging" is not necessarily understood a period or an operating period, but in general, the decline in catalytic ability of the catalyst. You could simplify this as Denote wear. The aging is also dependent on the type of operation of the internal combustion engine. So lead high exhaust gas temperatures and exhaust gas mass flow rates at one increased aging. A catalytic converter is aging rapidly also due to misfires, for example in succession misfires (damage to the ignition system) or insufficient fuel supply (empty tank).

Advantageous developments of the invention are in Subclaims specified.

First, it is suggested that the current Performance of the catalyst with a reference Performance is compared and the exhaust energy of the Internal combustion engine depending on the extent of the deviation current performance from the reference Performance is changed. Such a process is easy to implement in software.

It is particularly preferred if the current Efficiency of the catalyst due to its current Oxygen storage capacity and the reference Performance through a reference oxygen Storage capacity can be expressed. The oxygen The storage capacity of a catalytic converter can easily be changed Lambda values at the inlet and outlet of the catalytic converter be determined. The corresponding lambda probes are at usual catalysts available anyway, so that Perform this procedure without additional components is possible. The cost of running the The inventive method are thus small.

It is also proposed that the exhaust gas energy at Cold start and / or at low load the Internal combustion engine depending on the current one Efficiency of the catalyst is increased. In this If the fuel consumption is increased, at the same time, however, it is ensured that - in the event the cold start - the operating temperature of the catalytic converter so that that of modern emissions standards is increasing rapidly required conversion rates can be reached quickly can. At low loads, the lower Amount of exhaust gas the temperature of the catalytic converter drop. By the measure according to the invention prevents the The temperature of the catalyst drops so far that none sufficient conversion is guaranteed.

The measure according to the invention also improves the quality in the diagnosis of the catalyst, for example in a Emission test after ECE test cycle, improved: At this emissions test, which is mandatory in Europe, is relative large proportions with low load. Through the Measure according to the invention is avoided that the Catalyst diagnosis in a normal operating range Internal combustion engine reports no errors because the exhaust gas and catalyst temperature is still sufficiently high in Emission test, in which areas with low load are also checked are displayed, however, an excessive catalyst aging becomes.

Because the temperature of the catalyst at the transition of Internal combustion engine from high load to low load, however hardly drops suddenly, it can be provided that the Exhaust gas energy is only increased when the phase with low load is longer than a certain period of time. This prevents a short-term Operation, for example, at idle, which affects the Temperature of the catalyst has little or no effect, already an increase in exhaust gas energy with the associated increase in fuel consumption is initiated.

The change in exhaust gas energy can be caused by a change the efficiency of the internal combustion engine, in particular by changing the ignition angle and / or the speed and / or the mixture composition and / or at least another filling-changing parameter. All these measures are possible without costs for additional components are incurred. But it is also conceivable for example the use of exhaust gas recirculation which can also raise the temperature of the exhaust gases.

It is easy to implement in terms of software Carrying out the method according to the invention when the extent of the change in efficiency of the Internal combustion engine is determined via a characteristic curve in which is the deviation of the current performance of the Catalyst from the reference efficiency is fed.

In an advantageous embodiment of the invention It is also proposed that if the Deviation of the current performance of the Catalyst from the reference efficiency one reached and / or exceeded a certain value An entry is made in a fault memory and / or Message is generated. By the measure according to the invention account is taken of the fact that the increase in Exhaust gas energy through appropriate measures at the Motor control is not possible to any extent. Deviates from the current performance of the catalyst the reference performance so much that the desired conversion rate through a still reasonable Deterioration in efficiency and the corresponding Increase in exhaust gas energy is no longer achievable, this means that the desired exhaust gas limit value with the existing catalyst at least in the current one Operating range of the internal combustion engine no longer reached can be.

By entering an error memory, a person which the engine is waiting for in such a case. You can then decide whether a Replacement of the catalyst to correct the problem is required. A message, which for example to a dashboard of a motor vehicle is generated in which the internal combustion engine is installed, informed also the user of the internal combustion engine about the current one Status of the catalyst.

The invention also relates to a computer program which is suitable for performing the above method if it is running on a computer. It becomes special preferred if the computer program is on a memory, is stored in particular on a flash memory.

The invention further relates to a control and / or Control device for operating an internal combustion engine. at this is proposed to include memory on which a computer program of the above type is stored is.

An internal combustion engine is also part of the invention a catalyst. To with such an internal combustion engine the desired conversion rate of the catalyst in all Operating areas and as long as possible ensure the internal combustion engine and at the same time the To reduce fuel consumption of the internal combustion engine suggested that the exhaust gas energy of the internal combustion engine of the current performance of the catalyst depends.

In further training, it is proposed that the At least one catalyst at the inlet and one at the outlet has a lambda probe, and one of the current ones Efficiency of the catalyst corresponding current Oxygen storage capacity of the catalyst from the Signals from the lambda sensors at the input and output of the Catalyst is determined.

It is particularly advantageous if the internal combustion engine with a control and / or regulating device of the above type Is provided.

drawing

Below is a particularly preferred one Embodiment of the invention with reference to the enclosed drawing explained in detail. In the drawing demonstrate:

Figure 1 is a schematic representation of an internal combustion engine with gasoline direct injection and a catalyst.

FIG. 2 is a flowchart showing a method by which the internal combustion engine of FIG. 1 is operated;

FIG. 3 shows a diagram in which the oxygen storage capacity of the catalytic converter of the internal combustion engine of FIG. 1 is plotted over time; and

Fig. 4 is a graph in which the exhaust gas temperature of the internal combustion engine of Fig. 1 is plotted against time.

Description of the embodiment

In Fig. 1, an internal combustion engine is identified overall by reference numeral 10. It comprises a plurality of combustion chambers, of which only one combustion chamber is shown in FIG. 1 with reference number 12 . Combustion air is supplied to the combustion chamber 12 via an inlet valve 14 and an intake manifold 16 . A throttle valve 18 is arranged in this. The amount of air flowing through the intake manifold 16 is detected by an HFM sensor (hot film sensor) 20 .

The combustion exhaust gases pass from the combustion chamber 12 into an exhaust pipe 24 via an exhaust valve 22 . A catalyst 26 is arranged between two sections of the exhaust pipe 24 . The lambda values of the gas flowing through the catalytic converter 26 are recorded by lambda probes 28 and 30 . The lambda probe 28 is arranged at the entrance of the catalytic converter 26 , the lambda probe 30 at the exit of the catalytic converter 26 .

The fuel is supplied to the combustion chamber 12 via an injector 32 arranged directly on the combustion chamber 12 . The internal combustion engine 10 shown in FIG. 1 is therefore one with gasoline direct injection. This is supplied with fuel by a fuel system 34 . The fuel-air mixture present in the combustion chamber 12 is ignited by a spark plug 36 . The energy required for the ignition is provided by an ignition system 38 . The speed of a crankshaft 40 is tapped by a speed sensor 42 .

The functions and the operation of the internal combustion engine 10 are controlled or regulated by a control and regulating device 44 . For this purpose, the control and regulating device 44 is connected on the output side to the throttle valve 18 , to the injector 32 , and to the ignition system 38 . On the input side, the control and regulating device 44 receives signals from the HFM sensor 20 , from the lambda probes 28 and 30 and from the speed sensor 42 .

The catalyst 26 in particular reduces the gases emitted in the exhaust gas expelled from the combustion chamber 12, carbon monoxide, hydrocarbon and nitrogen oxides. The conversion of these harmful exhaust gases into harmless exhaust gases depends essentially on the operating temperature of the catalytic converter 26 . Noteworthy conversion of the pollutants begins only when the operating temperature of the catalyst 26 is approximately 250 ° C. Ideal operating conditions for high conversion rates and a long service life of the catalyst 26 prevail at approximately 400 to 800 ° C.

The internal combustion engine 10 shown in FIG. 1 is used in a motor vehicle. However, internal combustion engines used in motor vehicles must meet certain standards with regard to their exhaust gases. Since the conversion capacity of a catalytic converter deteriorates over the course of its life, measures must be taken to ensure that the internal combustion engine 20 fulfills these standards with regard to its exhaust gases over the longest possible running time of the internal combustion engine 10 . If it is no longer possible to meet said standards due to damage or aging of the catalytic converter 26 , it must be ensured that this can be recognized or ascertained immediately. The method shown in FIG. 2, which is stored as a computer program in the control and regulating device 44, serves these purposes:
After a start block 46 , the oxygen storage capacity SO2 of the catalytic converter 26 is determined in a block 48 . The signals from the two lambda probes 28 and 30 are used for this purpose. In block 50 , the determined current oxygen storage capacity SO2 is compared with a reference oxygen storage capacity SO2REF stored in a memory 52 . The reference oxygen storage capacity SO2REF is the same as that of a reference catalytic converter. It is determined, for example, by tests for each type of catalyst. Such a catalytic converter, for example, is meant as a reference catalytic converter that has aged to such an extent that it just barely meets the exhaust gas standard.

A difference dSO2 (block 54 ) formed in block 50 between the current oxygen storage capacity SO2 and the reference oxygen storage capacity SO2REF is compared in block 56 with a limit value G. This comparison serves to determine whether the decrease in the current oxygen storage capacity SO2 compared to the reference oxygen storage capacity SO2REF has reached a level which makes it necessary to replace the catalyst 26 . If the difference dSO2 is above the limit value G, an entry is made in an error memory in block 58 . A message is output in block 60 . This may consist, for example, of a warning light lighting up in the dashboard of the motor vehicle in which the internal combustion engine 10 is installed.

If the deviation dSO2 is below the limit value G, the difference dSO2 is fed into a characteristic curve in block 62 . A change dZW (block 64 ) of the ignition angle of the internal combustion engine 10 is determined late by this characteristic curve 62 . This shift dZW of the ignition angle is fed to an engine control 66 , which controls the ignition system 38 accordingly. By shifting the ignition angle increases the temperature day (block 68 ) and the mass flow (not shown) of the exhaust gas in the exhaust pipe 24th The method ends in block 70 .

The working temperature of the catalytic converter 26 is raised by increasing the exhaust gas temperature and the exhaust gas mass flow. This in turn can compensate for an age-related deterioration in the performance or the conversion rate of the catalytic converter 26 . The method shown in FIG. 2 thus makes it possible to set the exhaust gas temperature and the exhaust gas mass flow depending on the current performance or oxygen storage capacity SO2 of the catalytic converter 26 . The catalytic converter 26 can thus always be operated at the temperature at which it achieves the desired conversion rate during its entire service life. A rigid increase in the exhaust gas temperature, which unnecessarily increases fuel consumption, is therefore no longer necessary.

The relationship between the oxygen storage capacity SO2 and the exhaust gas temperature tag can also be seen from FIGS . 3 and 4: In FIG. 3, a region of the oxygen storage capacity SO2 of the catalytic converter 26 at the beginning of its life is designated by the reference symbol 72 . If the internal combustion engine 10 is operated with a low load, the temperature of the catalytic converter 26 drops, since on the one hand the exhaust gas temperature and on the other hand the amount of exhaust gas flowing through the catalytic converter 26 is small. Accordingly, without countermeasures, the oxygen storage capacity SO2 of the catalytic converter 26 would decrease in the section denoted by 74 in FIG. 3 (shown in dashed lines).

However, this is countered ( FIG. 4) by increasing the exhaust gas temperature so that the actual oxygen storage capacity SO2 and the current conversion rate of the catalytic converter 26 dependent on this can be kept at the desired level. Similarly, the performance or the oxygen storage capacity SO2 of the catalytic converter 26 would also decrease due to aging. This area is designated by 76 in FIG. 3 and is also shown in dashed lines. However, this is compensated for by continuously increasing the exhaust gas temperature in section 76 .

Claims (14)

1. A method for operating an internal combustion engine ( 10 ), in which the exhaust gases are fed to a catalyst ( 26 ), characterized in that the exhaust gas energy (tag) of the internal combustion engine ( 10 ) depends on the current performance (SO2) of the catalyst ( 26 ) , 2. The method according to claim 1, characterized in that the current performance (SO2) of the catalyst ( 26 ) is compared with a reference performance (SO2REF) and the exhaust gas energy (tag) of the internal combustion engine ( 10 ) depending on the extent of the deviation (dSO2 ) the current performance (SO2) is changed from the reference performance (SO2REF). 3. The method according to claim 2, characterized in that the current performance of the catalyst ( 26 ) by its current oxygen storage capacity (SO2) and the reference performance by a reference oxygen storage capacity (SO2REF) are expressed. 4. The method according to claim 3, characterized in that the current oxygen storage capacity (SO2) of the catalyst ( 26 ) is determined from the lambda values ( 28 , 30 ) at the input and output of the catalyst ( 26 ). 5. The method according to any one of the preceding claims, characterized in that the exhaust gas energy (day) during cold start and / or at low load ( 74 ) of the internal combustion engine ( 10 ) is increased depending on the current performance (SO2) of the catalyst ( 26 ). 6. The method according to any one of the preceding claims, characterized in that the exhaust gas energy (tag) by a change in the efficiency of the internal combustion engine ( 10 ), in particular by a change (dZW) the ignition angle and / or the speed and / or the mixture composition and / or at least one other filling-changing parameter is changed. 7. The method according to claim 6, characterized in that the extent of the change (dZW) in the efficiency of the internal combustion engine ( 10 ) is determined via a characteristic curve ( 62 ) into which the deviation (dSO2) of the current performance (SO2) of the catalyst ( 26 ) is fed by the reference performance (SO2REF). 8. The method according to any one of claims 2 to 7, characterized in that when the deviation (dSO2) of the current performance (SO2) of the catalyst ( 26 ) from the reference performance (SO2REF) reaches a certain value (G) and / or exceeds, an entry is made in an error memory ( 58 ) and / or a message is generated ( 60 ). 9. Computer program, characterized in that it is used for Carrying out the method according to one of the preceding Claims is appropriate when it is on a computer is performed. 10. Computer program according to claim 9, characterized characterized it on a store, in particular on a flash memory. 11. Control and / or regulating device ( 44 ) for operating an internal combustion engine ( 10 ), characterized in that it comprises a memory on which a computer program according to one of claims 9 or 10 is stored. 12. Internal combustion engine ( 10 ) with a catalyst ( 26 ), characterized in that the exhaust gas energy (tag) of the internal combustion engine ( 10 ) depends on the current performance (SO2) of the catalyst ( 26 ). 13. Internal combustion engine ( 10 ) according to claim 12, characterized in that the catalytic converter ( 26 ) has at least one lambda probe ( 28 , 30 ) at the inlet and at the outlet and a current oxygen storage capacity corresponding to the current performance of the catalytic converter ( 26 ) ( SO2) of the catalyst is determined from the signals of the lambda probes ( 28 , 30 ) at the input and at the output of the catalyst ( 26 ). 14. Internal combustion engine ( 10 ) according to one of claims 12 or 13, characterized in that it comprises a control and / or regulating device ( 44 ) according to claim 11.