Method for operating a component part disposed in an exhaust gas region of an internal combustion engine and device for implementing the method

Abstract

A method for operating a component part situated in an exhaust gas region of an internal combustion engine, and a device for carrying out the method are proposed, in which, in a first operating phase, an exhaust gas component is embedded, and which, in a second operating phase, is regenerated from the exhaust gas component. The second operating phase may be started both as a function of the operating state of the component part and/or as a function of the operating state of the internal combustion engine, and also by an external start signal. If there is an external start signal present, the second operating phase is preferably only started if, at the same time, at least one additional conditions is satisfied. The external start signal is made available, for instance, by a diagnostic unit which is connected via a diagnosis interface.

Description

FIELD OF THE INVENTION

The present invention relates to a method for operating a component part disposed in an exhaust gas region of an internal combustion engine and a device for implementing the method.

BACKGROUND INFORMATION

German Published Patent Application No. 199 06 287 describes a method for regenerating a particulate filter disposed in the exhaust gas region of an internal combustion engine, in which changes are made between various operating states as a function of the most recently present operating state, and as a function of the state of the particulate filter. In one operating state, a regeneration of the particulate filter from the embedded particles takes place.

The regeneration takes place at an increased temperature, at which the particles, chiefly soot particles and ash particles, are burned by an oxidation reaction. In the average operation of an internal combustion engine, the temperature of the particulate filter lies in a temperature range of 150 to 300 degrees Centigrade, in general, therefore, below the temperature required for the regeneration. Therefore, in general, special heating measures are required in order to initiate regeneration. The required temperature may be reached, for instance, via an increase of the temperature of the exhaust gas of the internal combustion engine. Since the exhaust gas has to heat up, besides the particulate filter, additional component parts that may be present, that is, the exhaust gas region as a whole, some minutes may pass until the regeneration starts. An estimate of the duration of the regeneration, that is a function of the loading state of the particulate filter and of its size, would currently be up to 25 minutes.

If the internal combustion engine is situated in a motor vehicle, situations are conceivable in which a complete regeneration of the particulate filter is not possible or is not even able to be begun. Such situations, on the one hand, are fault states such as an engine oil dilution by a previous regeneration. On the other hand there may be operating states present in which the internal combustion engine does not even reach its own nominal operating temperature. Such an operating state occurs, for example, in short-range operation of the motor vehicle. In this case, a regeneration procedure may perhaps be broken off or may not start in the first place.

German Published Patent Application No. 198 43 879 describes a method for operating an internal combustion engine, in whose exhaust gas region an NOx adsorption catalyst is situated. In a first operating phase in which the internal combustion engine is driven using a lean mixture within the scope of a stratified cylinder charge, the NOx created is stored in the NOx adsorption catalyst. In a second operating phase, in which the internal combustion engine is operated with a stoichiometric or rich mixture within the scope of a homogeneous cylinder charge, the NOx adsorption catalyst is regenerated. As in the particulate filter, the regeneration of the NOx adsorption catalyst takes place at increased catalyst temperatures, compared to normal operating conditions, which are able to be reached using special catalyst heating measures. The duration of the regeneration of the NOx adsorption catalyst lies within the range of seconds, and is therefore considerably shorter compared to the duration of the regeneration of a particulate filter. Still, based on the required heating measures, in principle, the same problems occur as in the regeneration of the particulate filter. Here, too, situations are conceivable in which the regeneration is broken off or is not started in the first place.

SUMMARY OF THE INVENTION

The object of the present invention is to specify a method for operating a component part disposed in an exhaust gas region of an internal combustion engine and a device for implementing the method which ensure the operating readiness of the component part. The method according to the present invention and the device according to the present invention for carrying out the method provide that, in a first operating phase, an exhaust gas component of the internal combustion engine is embedded in a component part situated in the exhaust gas region of the internal combustion engine, and, in a second operating phase, the component part is regenerated from the embedded exhaust gas component. The second operating phase is started as a function of the operating state of the component part and/or as a function of the operating state of the internal combustion engine. According to the present invention, it is provided that the second operating phase is furthermore started by an external start signal.

The measure according to the present invention makes it possible to ensure the operating readiness of the component part in that the operating phase, in which the component part is regenerated from the embedded exhaust gas component, is able to be started at will, using the external start signal. The regenerated state of the component part may be produced, for example, by an operator, as desired. The desire to do this may occur during service performed on the internal combustion engine and the components assigned to it. If the internal combustion engine is situated in a motor vehicle, the demand may occur within the scope of stays in a repair shop. The measure according to the present invention makes it possible to put the component part into a specified state that is equivalent to the regenerated state. In this application, the measure according to the present invention makes possible the diagnosis of the internal combustion engine and the components assigned to it, starting from the regenerated state of the component part. The vehicle operation of the motor vehicle, that was possibly restricted before, may be restored again.

A first further refinement provides that the external start signal is guided via a diagnosis interface. These days, diagnosis interfaces are usually present, provided the internal combustion engine is situated in a motor vehicle. In this application, normalized interfaces will in future be prescribed by law, so that one may assume their increasing availability. The external start signal is preferably made available by a diagnostic unit which may be contacted in a simple manner if a diagnosis interface is present.

Another refinement provides that, when the external start signal is present, the second operating phase is started only if at least one additional condition has been satisfied at the same time.

Such a condition is, for instance, that the temperature and/or the rotary speed of the internal combustion engine lie within a prespecified range. A further condition is, for example, that the speed of a motor vehicle is equal to zero. Still another condition is, for example, that a performance specification signal of the internal combustion engine corresponds to an idling value, at which the internal combustion engine is at least within the range of its idling speed. Yet another condition is, for instance, that an idling controller, that is included in the control system of the internal combustion engine, is in a steady state, at which the idling speed regulation of the internal combustion engine is held at least approximately constant.

One embodiment of the method according to the present invention, and of the device according to the present invention for carrying out the method, provides that, in the second operating phase of the internal combustion engine, an increase in the temperature of the exhaust gas of the internal combustion engine is provided.

The method according to the present invention and the device according to the present invention for carrying out the method are particularly suitable for producing the operating readiness of a catalytic converter designed as catalytic converter with hydrogen trap, especially as an NOx adsorption catalyst and/or a particulate filter, preferably a Diesel particulate filter.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE shows a technical environment in which a method according to the present invention proceeds.

DETAILED DESCRIPTION

The FIGURE shows an internal combustion engine 10 in whose intake area an air mass flow sensor 11 is situated, and in whose exhaust gas region 12 a temperature sensor 13 and a component part 14 are situated. Air mass flow sensor 11 emits an air mass flow signal msl to a control system 15. Temperature sensor 13 makes available to control system 15 a temperature tabg of the exhaust gas of internal combustion engine 10. Control system 15 also has supplied to it a performance setpoint signal ps, a rotary speed signal n of internal combustion engine 10, as well as a regeneration signal r made available by a regeneration control system 16 Control system 15 emits a fuel metering signal msk to internal combustion engine 10, emits an exhaust gas recirculation signal agr to an exhaust gas recirculation valve 17 which sets a recirculated exhaust gas quantity 18, and emits an idling controller signal lr to a condition tester 19.

Rotary speed signal n and performance setpoint signal ps are also made available to condition tester 19. Condition tester 19 also receives a speed signal v, an engine temperature signal tmot and an external start signal s that are supplied to it. External start signal s is made available by a diagnostic unit 20, and is passed on to condition tester 19 via a diagnosis interface 21.

Condition tester 19 emits a regeneration release signal rf to regeneration control system 16. Furthermore, a pressure difference signal dp is supplied to regeneration control system 16, which makes available a pressure difference 22, which records the pressure difference of the exhaust gas in front of and behind component part 14.

The method according to the present invention and the device according to the present invention for carrying out the method operate as follows:

As a function of performance setpoint signal ps, control system 15 set the fuel quantity, that is to be supplied to internal combustion engine 10, using fuel quantity signal msk, which is supplied to a system that meters in fuel and is not shown in detail. In this instance, air mass flow signal msl is taken into consideration, which is made available by air mass flow sensor 11, which is situated in the intake region of internal combustion engine 10. If internal combustion engine 10 is a Diesel internal combustion engine, in principle, no additional input variables are needed for setting fuel quantity signal msk. If necessary, an exhaust gas sensor is provided, that is not shown, which emits a lambda signal to control system 15, as a measure for the air-fuel ratio in the exhaust gas of the internal combustion engine. Also not shown is a possibly present throttle valve in the intake region of internal combustion engine 10, which either emits a throttle valve signal to control system 15, or which is activated by control system 15.

The concentration of nitrogen oxides in the exhaust gas of internal combustion engine 10, as well as temperature tabg of the exhaust gas may be influenced using recirculated exhaust gas quantity 18, which controls control system 15 via exhaust gas recirculating valve 17 using exhaust gas recirculating signal agr.

Component part 14 may be, for example, an adsorption catalyst which embeds a prespecified exhaust gas component in a first operating phase. In the related art named at the outset, the adsorption catalyst is embodied as an NOx adsorption catalyst which stores the nitrogen oxides contained in the exhaust gas in the first operating phase of internal combustion engine 10. Since the storage capacity of such an adsorption catalyst is limited, the adsorption catalyst occasionally has to be regenerated in a second operating phase. The necessity for this generation may be determined in regeneration control system 16, for instance, in the light of NOx mass stored in the adsorption catalyst, the NOx mass appearing behind the adsorption catalyst, the NOx mass flow appearing in front of and behind the adsorption catalyst, or in the light of other criteria. The appearance of regeneration signal r shows the regeneration required for component part 14. A change from the first to the second operating phase may then be directly brought about. Control system 15 may, however, prevent the change required per se, in the light of determined operating conditions of internal combustion engine 10.

In the exemplary embodiment shown, component part 14 is a particulate filter, especially a Diesel particulate filter, which embeds the soot particles contained in the exhaust gas of internal combustion engine 10, in the first operating phase. Regeneration control system 16 may ascertain the loading state of the particulate filter, for instance, in the light of the pressure difference occurring in the exhaust gas in front of and behind the particulate filter. The pressure difference is measured by pressure difference sensor 22, and is made available as pressure difference signal dp. If the loading limit of the particulate filter exceeds a predefined measure, then regeneration control system 16 emits regeneration signal r to control system 15. In this exemplary embodiment too, a change from the first to the second operating phase may then be directly brought about. Here, too, control system 15 may, however, prevent the change required per se, in the light of determined operating conditions of internal combustion engine 10.

Such operating conditions are, for example, an operation of internal combustion engine 10 during the warm-up phase, temperature tmot of internal combustion engine 10 being able to be measured, for instance, by a temperature sensor, that is not shown, that is situated, for example, in the cooling water, on the cylinder block or in the oil circulation. A change to the second operating phase is further prevented, for example, if internal combustion engine 10 is in idling operation. In this operating state, temperature tabg of the exhaust gas is so low that the fuel requirement for heating up component part 14 would be too large. A change to the second operating phase is further prevented, for instance, if the distance in time to a prior second operating phase is too short. In this context, it should be taken into consideration that an oil dilution during the second operating phase may occur by a heating method in which a postinjection of fuel is provided, which partially condenses on the cylinder walls of internal combustion engine 10, and gets into the engine oil. If these operating situations are present, the second operating phase is just not started in the first place. Furthermore, one has to take into account that the second operating phase cannot be shut down. This case arises if internal combustion engine 10 is switched off during the presence of the second operating phase.

According to the present invention, it is provided that the second operating phase is able to be started, independently of the operating states of internal combustion engine 10 and/or the state of component part 14, using external start signal s. External start signal s may, for example, caused by a service technician within the scope of maintenance. External start signal s makes it possible to be able to shift component part 14 into the regenerated state at any time. The further diagnosis may then proceed from a specified initial state.

External start signal s could, for instance, take place by a simple short-circuiting of a contact which, for example, is connected to control system 15. A simple handling occurs if start signal s is conveyed via disgnosis interface 21. Such a diagnosis interface 21 is mostly already available these days. In the future, the availability of diagnosis interface 21 will be increased because of legal regulations. Start signal s is preferably made available by diagnostic unit 20, which is contacted to diagnosis interface 21. Diagnosis interface 21 may be implemented both as a mechanical plug connection and as a radio communication.

In one simple embodiment, external start signal s may directly cause the start of the second operating phase, in which component part 14 is regenerated. Preferably, however, condition tester 19 is provided, which additionally tests, when an external start signal is present, whether prespecified conditions are present, and which, using regeneration release signal fr, releases the second operating phase only when at least one condition is satisfied.

A first condition determines that temperature tmot of internal combustion engine 10 has to exceed a threshold value. Another condition provides that the driving speed of a motor vehicle, in which internal combustion engine 10 is situated, is equal to zero. Using this measure, it is checked whether external start signal s was actually caused during a service stay. Furthermore, it may be tested whether rotary speed n of internal combustion engine 10 is in the range of the idling speed. Particularly advantageous is checking whether performance setpoint signal ps corresponds to a value at which internal combustion engine 10 is operated when idling. Performance setpoint signal ps is made available, for example, by an accelerator situated in the motor vehicle. Using this measure, it is additionally ensured, if necessary, that internal combustion engine 10 is being operated at a rotary speed n in the idling speed range. Using idling control signal lr, one may then additionally ensure that internal combustion engine 10 is being operated at a rotary speed n in the idling speed range, and that no request for changing the rotary speed is present or that no increased idling speed is present, as, for example, might be specified during warmup of the internal combustion engine. Consequently, condition tester 19 forms an AND link of external control signal s with the presence of at least one of conditions tmot, v, n, ps, lr. Only if the at least one condition tmot, v, n, ps, Ir is satisfied, condition tester 19 releases regeneration release signal Fr to regeneration control system 16. Regeneration release signal Fr has preference compared to pressure difference signal dp, which indicates the loading state of component part 14. Making available regeneration signal r induces control system 15 to make the immediate change in the operating phase. Additional checking of conditions is no longer required, since the conditions in condition tester 19 had already been determined to have been satisfied.

Using the change to the second operating phase, control unit 15 is able to initiate at least one possibly required heating measure. For example, temperature tabg of the exhaust gas may be increased, which is measured by temperature sensor 13. The increase in temperature tabg of the exhaust gas may take place, for example, by throttling of the air flow being supplied to internal combustion engine 10, using the throttle valve that is not shown. The temperature increase may also take place by an increase in recirculated exhaust gas quantity 18. As a further measure, one may undertake an increase in the idling speed of internal combustion engine 10. One other measure provides a postinjection of fuel, which is combusted only incompletely in the cylinders. The uncombusted fuel reacts exothermically in exhaust gas region 12 with any residual oxygen present. This measure may effectively be supported using a secondary air injection that is not shown. Direct electrical heating of component part 14, that is not shown, may also be provided.

The end of the second operating phase is detected using the measures described. The second operating phase is then terminated along with the change into the first operating phase. The readiness for use of component part 14 is restored using the end of the second operating phase, that is, the termination of regeneration.

Claims

1-11. (canceled)

12. A method for operating a component part situated in an exhaust gas region of an internal combustion engine, comprising:

in a first operating phase, embedding an exhaust gas component in the component part;

in a second operating phase, regenerating the component part from the exhaust gas component;

starting the second operating phase as a function of at least one of an operating state of the internal combustion engine and a loading state of the component part; and

starting the second operating phase by an external start signal.

13. The method as recited in claim 12, further comprising:

conveying the external start signal via a diagnosis interface.

14. The method as recited in claim 12, wherein the external start signal is made available by a diagnostic unit.

15. The method as recited in claim 12, further comprising:

if an external start signal is present, starting the second operating phase only if, at the same time, at least one other condition is satisfied.

16. The method as recited in claim 15, wherein at least one of:

a temperature of the internal combustion engine exceeds a prespecified threshold value, and

a driving speed of a motor vehicle, in which the internal combustion engine is situated, is equal to zero.

17. The method as recited in claim 15, wherein a rotary speed of the internal combustion engine corresponds to an idling speed.

18. The method as recited in claim 15, wherein a performance specification signal for a performance of the internal combustion engine corresponds to a value that is sufficient only for a keeping up of an idling speed of the internal combustion engine.

19. The method as recited in claim 15, wherein an idling controller signal made available by an idling controller is in a steady-state condition.

20. The method as recited in claim 12, wherein the component part includes an adsorption catalyst.

21. The method as recited in claim 12, wherein the component part includes a particulate filter.

22. The method as recited in claim 21, wherein the particulate filter includes a Diesel particulate filter.

23. A device for operating a component part situated in an exhaust gas region of an internal combustion engine, comprising:

an arrangement for, in a first operating phase, embedding an exhaust gas component in the component part;

an arrangement for, in a second operating phase, regenerating the component part from the exhaust gas component;

an arrangement for starting the second operating phase as a function of at least one of an operating state of the internal combustion engine and a loading state of the component part; and

an arrangement for starting the second operating phase by an external start signal.