US20100095654A1

US20100095654A1 - Procedure for operating an internal combustion engine and device for the execution of the procedure

Info

Publication number: US20100095654A1
Application number: US12/603,022
Authority: US
Inventors: Bernd Rapp; Andreas Beiter; Sascha Joos
Original assignee: Individual
Current assignee: Robert Bosch GmbH
Priority date: 2008-10-21
Filing date: 2009-10-21
Publication date: 2010-04-22
Also published as: DE102008043025A1; EP2180179A2; EP2180179A3

Abstract

Suggested is a procedure for operating a combustion engine (10), which comprises at least one pencil-type glow plug (12) that is assigned to at least one cylinder (11), and in whose exhaust gas area (13) at least one catalytic converter (14) is arranged, as well as a device for implementing the procedure. The pencil-type glow plug (12) is operated at least temporarily independent of the combustion engine operating status until reaching a preset measure for the conversion capability of the catalytic converter (14). The procedure according to the invention enables a low-emission operation of the combustion engine (10) simultaneously with minimal energy consumption and an extended lifetime of the pencil-type glow plug (12).

Description

This application is claims benefit of Serial No. 102008 043 025.0, filed 21 Oct. 2008 in Germany and which application is incorporated herein by reference. To the extent appropriate, a claim of priority is made to the above disclosed applications.

TECHNICAL FIELD

The invention is based on a procedure for operating a combustion engine as well as on a device for implementing the procedure according to the category of the independent claims.
Subject matter of the present invention is also a control unit program as well as a control unit program product.

BACKGROUND

DE 10 2005 061 878 A1 describes a glow current control device for controlling the glow current of a pencil-type glow plug that is arranged in a cylinder of a combustion engine. The familiar glow current control device comprises an environment detection device as well as a driver and/or vehicle detection device, which detect a momentary environment of the environmental information concerning the vehicle as well as internal information concerning the driver or the vehicle and send those to a performance requirement pre-determination device. The performance requirement pre-determination device determines an expected performance requirement of the combustion engine, so that a previous heating of the pencil-type glow plug is possible if the combustion engine is cooled down. Thereby the combustion in the cylinders of the combustion engine can be improved and in particular the emission of undesired exhaust gases can be reduced.
The invention is based on the task provided a simple procedure for operating a combustion engine, which comprises at least one pencil-type glow plug that is assigned to at least one cylinder, and in whose exhaust gas area at least one catalytic converter is arranged as well as a device for implementing the procedure.

SUMMARY

The invention is based on a procedure for operating a combustion engine, which comprises at least one pencil-type glow plug, which is assigned to at least one cylinder, and in whose exhaust gas area at least one catalytic converter is arranged. The procedure according to the invention distinguishes itself thereby that the pencil-type glow plug is operated at least temporarily independent of the combustion engine operating status until reaching a preset measure for the conversion capability of the catalytic converter.
The operation of the at least one pencil-type glow plug at least temporarily until reaching the measure for the conversion capability of the catalytic converter influences in particular the combustion of the fuel in the cylinders of the combustion engine positively, meaning that a minimum of undesired exhaust gases such as carbon monoxide and hydrocarbon are created. Thereby an optimization of the combustion engine operation can be provided focusing on low NOx emissions.
The stabilizing effect by operating the pencil-type glow plug is based on a reduction of the ignition delay and on an improvement of the combustion robustness by a defined pre-conditioning of the combustion chamber in the cylinders of the combustion engine.
The particularly low carbon monoxide and hydrocarbon emissions are kept on a low level over the entire lifetime of the combustion engine and the catalytic converter.
The procedure according to the invention has in particular an effect during the cold start of the combustion engine. Furthermore the procedure is provided during the subsequent operation of the combustion engine preferably always when the preset measure for the conversion capability of the catalytic converter is fallen below, for example in the range of a boost switch off of the combustion engine.
With the procedure according to the invention the special advantages of an efficient operation of the at least one pencil-type glow plug is thereby achieved, in that the energy supply of the pencil-type glow plug can be turned off after reaching the preset measure for the conversion capability of the catalytic converter, so that the pencil-type glow plug does not have to be operated unnecessarily and the resulting fuel consumption is unnecessarily increased. The glow plug 12 on the one hand is loaded minimally and on the other hand the energy consumption is minimized.
The determination of the measure for the conversion capability of the catalytic converter or the determination of the reaching of the conversion capability of the catalytic converter can take place in different ways, whereby individual embodiments are subject matter of the dependent claims, which furthermore relate to further advantageous configurations and improvements of the procedure according to the invention.
A simple configuration provides that the preset measure for the conversion capability of the catalytic converter shall be reached when the catalytic converter has reached its start up temperature. The startup temperature, which is also called “light-off” temperature, is the temperature, from which on the catalytically supported reactions can take place in the catalytic converter in order to achieve a conversion capability above 50%.
A particularly simple configuration provides that the preset measure for the conversion capability of the catalytic converter shall be reached when a preset operating time of the pencil-type glow plug has elapsed.
Another simple configuration provides that the preset measure for the conversion capability of the catalytic converter shall be reached when the catalytic converter has reached a certain conversion rate. The conversion rate can for example be determined with the aid of an exhaust gas sensor, which is arranged downstream after the catalytic converter and which detects one or several exhaust gas components that are converted by the catalytic converter, whereby the upstream occurring corresponding exhaust gas components can either be calculated or also measured.
One embodiment provides that the reaching of the preset measure for the conversion capability of the catalytic converter is determined with the aid of a comparison of the exhaust gas temperature that is measured or calculated upstream of the catalytic converter with an upstream exhaust gas temperature threshold value.
An alternative or additional embodiment provides that the reaching of the preset measure for the conversion capability of the catalytic converter is determined with the aid of a comparison of the exhaust gas temperature that is measured downstream of the catalytic converter with an downstream exhaust gas temperature threshold value.
An advantageous embodiment provides that the reaching of the preset measure for the conversion capability of the catalytic converter is determined with the aid of a comparison of the difference that occurs at the catalytic converter between the downstream exhaust gas temperature and the upstream exhaust gas temperature and a comparison with a temperature difference threshold, whereby the downstream exhaust gas temperature can be measured and the upstream exhaust gas temperature can be measured or calculated.
With those measure in particular the ageing process of the catalytic converter can be considered, during which the conversion capability of the catalytic converter usually diminishes.
Alternatively or additionally the reaching of the preset measure for the conversion capability of the catalytic converter can also be determined by measuring the exhaust gas lambda downstream after the catalytic converter and a comparison with a downstream exhaust gas lambda threshold value.
Alternatively or additionally the reaching of the preset measure for the conversion capability of the catalytic converter can also be determined by an occurring difference between the downstream exhaust gas lambda and the upstream exhaust gas lambda and a comparison of the deviation with an exhaust gas lambda deviation threshold value. The exhaust gas lambda is thereby measured downstream and measured or calculated upstream before the catalytic converter.
The previously described embodiments, at which at least one exhaust gas temperature and/or at least one exhaust gas lambda are evaluated, qualify not only for determining the reaching of the preset measure for the conversion capability of the catalytic converter but are simultaneously suitable for determining whether the catalytic converter has reached its start up temperature.
According to one improvement it is provided that the electric power that is delivered to the pencil-type glow plug varies. At the beginning of the heating process for example an increased power can be preset, which is lowered with an increasing operating time of the pencil-type glow plug.
The device according to the invention for implementing the procedure relates initially to a customized control unit, which contains measures for implementing the procedure. A conversion capability determination as well as a pencil-type glow plug heat control is provided as such measures.
The control unit contains preferably at least one electric storage, in which the steps of the procedure are stored as control unit program.
The control unit program provides according to the invention that all steps of the procedure are carried out if it runs in a control unit.
The control unit program product with a program code that is stored on a machine-readable medium carries out the procedure according to the invention if the program runs in a control unit.
Embodiments of the inventions are illustrated in the drawing and further explained in the subsequent description.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE shows a technical surrounding, in which a procedure according to the invention is carried out.

DETAILED DESCRIPTION

The FIGURE shows a combustion engine 10, which comprises at least one cylinder 11 assigned to a pencil-type glow plug 12. At least one catalytic converter 14 is arranged in the exhaust gas area 13 of the combustion engine 10.
In the exhaust gas area 13 upstream before the catalytic converter 14 an upstream exhaust gas temperature te_vK occurs as well as an upstream exhaust gas lambda la_vK. Downstream after the catalytic converter 14 a downstream exhaust gas temperature te_nK as well as a downstream exhaust gas lambda lam_nK occur.
The upstream exhaust gas lambda lam_vK are measured by an upstream lambda sensor 15 and the upstream exhaust gas temperature te_vK by an upstream temperature sensor 16. The downstream exhaust gas temperature te_nK is measured by a downstream temperature sensor 17 and the downstream exhaust gas lambda lam_nK by a downstream lambda sensor 18.
A control unit 20 provides the pencil-type glow plug 12 and a heat output HZ. The upstream lambda sensor 15 sends a measured upstream exhaust gas lambda lam_Mes_vK, the upstream temperature sensor 16 a measured upstream exhaust gas temperature te_Mes_vK, the downstream temperature sensor 17 a downstream exhaust gas temperature te_Mes_nK and the downstream lambda sensor 17 a measured downstream exhaust gas lambda lam_Mes_nK to the control unit 20.
The control unit 20 contains a conversion rate determination 21 as well as a pencil-type glow plug heat control 22.
The conversion rate determination 21 is provided with a maximum period of time ti_Max, a start up temperature te_An, the measured downstream exhaust gas temperature te_Mes_nK, a downstream exhaust gas temperature threshold value te_ScW_nK, the measured upstream exhaust gas temperature te_Mes_vK, a calculated upstream exhaust gas temperature te_Sim_vK, an upstream exhaust gas temperature threshold value te_ScW_vK, a temperature difference threshold value te_Dif_ScW, the measured downstream exhaust gas lambda lam_Mes_nK, a downstream exhaust gas lambda threshold value lam_ScW_nK, the measured upstream exhaust gas lambda lam_Mes_vK, a calculated upstream exhaust gas lambda lam_Sim_vK, an exhaust gas lambda deviation threshold value lam_Dif_ScW as well as a percentage conversion rate %. The conversion rate determination 21 provides a glow demand signal Anf_Gl, which is provided to the pencil-type glow plug heat control 22, which is furthermore provided with a combustion engine demand signal Anf_Bkm as well as a heat power default var_HZ and which provides the heat output HZ for the pencil-type glow plug 12.
The procedure according to the invention works as follows:
The catalytic converter 14 that is arranged in the exhaust gas area 13 of the combustion engine 10 is provided for the conversion of undesired exhaust gas components of the combustion engine 10 as for example carbon monoxide, hydrocarbons and nitrous gases.
According to the invention the operation of the pencil-type glow plug 12 is provided at least temporarily until the reaching of a preset measure for the conversion capability of the catalytic converter 14, whereby at least one pencil-type glow plug 12 is assigned to at least one cylinder 11 of the combustion engine 10. An insufficient conversion capability occurs in particular at a cold start of the combustion engine 10. But the conversion capability can also fall below the preset measure in the subsequent operation of the combustion engine 10, for example during a boost switch off.
The pencil-type glow plug 12 is usually provided for heating the air-fuel mixture that is supplied to a diesel combustion engine 10. The pencil-type glow plug 12 is therefore usually operated depending on the operating status of the combustion engine 10, for example depending on a cold start process. For this purpose the pencil-type glow plug heat control 22 is provided with the combustion engine demand signal Anf_Bkm, which causes the pencil-type glow plug heat control 22 to provide the heat output HZ. The combustion engine demand signal Anf_Bkm can for example depend on the operating temperature of the combustion engine 10.
In practice the pencil-type glow plug 12 is connected to a not further shown, if necessary periodical voltage source, whereby the current depends on the pencil-type glow plug temperature.
The controlling of the pencil-type glow plug 12 independent of the combustion engine operating status at least temporarily until reaching the preset measure for the conversion capability of the catalytic converter 14 takes place depending on the glow demand signal Anf_Gl, which is provided by the conversion rate determination 21. The pencil-type glow plug 12 can thereby be impinged with the heat output HZ at least temporarily until reaching the preset measure for the conversion capability of the catalytic converter 14 independent of the combustion engine demand signal Anf_Bkm.
By operating the pencil-type glow plug 12 the exhaust gas raw emission of the combustion engine, in particular the carbon monoxide emission and the hydrocarbon emissions are positively influenced, so that even in the case of an insufficient conversion capability of the catalytic converter 14 minimal emissions occur. By heating the pencil-type glow plug 12 electric energy is inserted into the cylinder 11 of the combustion engine 10, which contributes to a temperature increase in the cylinder 11 and therefore also in the exhaust gas area 13, whereby the heating of the catalytic converter 14 can be supported. A heating requirement of the catalytic converter 14 can thereby exist based on a cold start of the combustion engine 10 as well as on a combustion engine operation status with a low upstream exhaust gas temperature te_vK, as for example in idle status or in the range of a boost switch off of the combustion engine 10.
According to a simple embodiment the preset measure for the conversion capability of the catalytic converter 14 is reached, when the preset maximum period of time ti_Max has elapsed. The beginning of the time period can for example be determined by a not further shown demand for heating the catalytic converter 14. The beginning of the time period can furthermore be determined depending on measures that are described further below.
According to another very simple embodiment the reaching of the preset measure for the conversion capability of the catalytic converter 14 is assumed when the catalytic converter 14 has achieved a start up temperature te_An. The reaching of the startup temperature te_An can also be determined by measures that are described further below.
According to an alternative simple embodiment it can be provided that the preset measure for the conversion capability of the catalytic converter 14 should be reached, when the catalytic converter has reached a certain conversion rate %. In this embodiment a specific percentage, for example 80% can be preset, whereby the reaching of the specific conversion rate % can be determined by a not further shown exhaust gas sensor that is arranged downstream after the catalytic converter 14 and a comparison with the converted exhaust gas component that has been measured or calculated upstream before the catalytic converter.
A further embodiment provides that the reaching of the preset measure for the conversion capability of the catalytic converter 14 is determined with the of a comparison of the measured downstream exhaust gas temperature te_Mes_nK with the downstream exhaust gas temperature threshold value te_ScW_nK. The downstream exhaust gas temperature te_nK can be used as an approximate measure for the temperature of the catalytic converter.
Alternatively or additionally it can be provided that the reaching of the preset measure for the conversion capability of the catalytic converter 14 is determined with the aid of a comparison of the measured upstream exhaust gas temperature te_Mes_vK with the upstream exhaust gas temperature threshold value te_ScW_vK. In that case the upstream exhaust gas temperature te_vK is used as an approximate measure for the temperature of the catalytic converter.
According to another approach that can be provided additionally or alternatively the reaching of the preset measure for the conversion capability of the catalytic converter 14 is determined with the aid of a comparison of the difference that occurs at the catalytic converter 14 between the downstream exhaust gas temperature te_nK and the upstream exhaust gas temperature te_vK and a comparison with the temperature difference threshold value te_Dif_ScW, whereby the downstream exhaust gas temperature te_nK can be measured and the upstream exhaust gas temperature te_vK can be measured or calculated.
The upstream exhaust gas temperature te_vK can be provided to the conversion capability determination 21 as a measured upstream exhaust gas temperature te_Mes_vK as well as a calculated upstream exhaust gas temperature te_Sim_vK. The calculated upstream exhaust gas temperature te_Sim_vK can for example be calculated depending on variables of the combustion engine 10 such as the load or the fuel amount that has been introduced into the combustion engine 10.
The embodiments that are based on the detection of at least one exhaust gas temperature cannot only be used for determining the preset measure for the conversion capability of the catalytic converter 14 but also for determining the reaching of its start up temperature.
Alternatively or additionally the preset measure for the conversion capability of the catalytic converter 14 can be determined by a comparison between the measured downstream exhaust gas lambda lam_nK and the downstream exhaust gas lambda threshold value lam_ScW_nK.
It is especially advantageously that the reaching of the preset measure for the conversion capability of the catalytic converter 14 can additionally or alternatively be determined by a comparison of the downstream exhaust gas lambda lam_nK with the upstream exhaust gas lambda lam_vK. The upstream exhaust gas lambda lam_vK can thereby be provided by the measured upstream exhaust gas lambda lam_Mes_vK or by the calculated upstream exhaust gas lambda lam_Sim_vK. The reaching of the preset measure for the conversion capability of the catalytic converter 14 is subsequently determined by comparing the measured downstream exhaust gas lambda lam_Mes_nK with the measured upstream exhaust gas lambda lam_Mes_vK or the calculated upstream exhaust gas lambda lam_Sim_vK. The difference is compared to the exhaust gas lambda deviation threshold value lam_Dif_ScW, whereby the values of the deviations of the exhaust gas lambdas lam_vK, lam_nK can preferably be taken as a basis for the comparison. It is thereby assumed that in the case of reaching the preset measure for the conversion capability of the catalytic converter 14 the exhaust gas lambda deviation threshold value lam_Dif_ScW is exceeded. Because the upstream exhaust gas lambda lam_vK can vary above as well as below the stoichiometric exhaust gas lambda the value creation of the exhaust gas lambda deviation is preferably provided.
According to one embodiment a power control of the pencil-type glow plug 12 can be provided with the aid of a heat output default var_HZ. The influencing of the power takes preferably place in such a way that at the beginning of the heating of the pencil-type glow plug 12 the maximum power is preset while it is reduced with an increasing operating time of the pencil-type glow plug 12. The described approaches according to the invention enables a targeted switching off of the heating of the pencil-type glow plug 12 at a point of time, at which the catalytic converter 14 is able to ensure a sufficient conversion of undesired exhaust gas components, so that an optimization of the emissions of the combustion engine 10 by operating the pencil-type glow plug 12 within the scope of the invention's measures can fade into the background. Thereby the pencil-type glow plug 12 is minimally burdened on the one hand and the energy consumption minimized on the other hand.

Claims

1. A procedure for operating a combustion engine, which comprises at least one pencil-type glow plug that is assigned to at least one cylinder, and in whose exhaust gas area at least one catalytic converter is arranged, wherein the pencil-type glow plug is operated at least temporarily independent of the combustion engine operating status until reaching a preset measure for the conversion capability of the catalytic converter.

2. The procedure according to claim 1, wherein the preset measure for the conversion capability of the catalytic converter, if the catalytic converter has reached its start up temperature.

3. The procedure according to claim 1, wherein the preset measure for the conversion capability of the catalytic converter is reached, when a preset operating time of the pencil-type glow plug has elapsed.

4. The procedure according to claim 1, wherein the preset measure for the conversion capability of the catalytic converter is reached when the catalytic converter has reached a certain conversion rate.

5. The procedure according to claim 1, wherein the reaching of the preset conversion capability of the catalytic converter is determined with the aid of a comparison of the upstream exhaust gas temperature that has been measured or calculated upstream of the catalytic converter with an upstream exhaust gas temperature threshold value.

6. The procedure according to claim 1, wherein the reaching of the preset measure for the conversion capability of the catalytic converter is determined with the aid of a comparison of the downstream exhaust gas temperature that has been measured or calculated downstream of the catalytic converter with an downstream exhaust gas temperature threshold value.

7. The procedure according to claim 1, wherein the reaching of the preset measure for the conversion capability of the catalytic converter is determined with the aid of a comparison of the difference that occurs at the catalytic converter between the downstream exhaust gas temperature and the upstream exhaust gas temperature and a comparison of the temperature difference threshold value, wherein the downstream exhaust gas temperature is measured and the upstream exhaust gas temperature is measured or calculated.

8. The procedure according to claim 1, wherein the reaching of the preset measure for the conversion capability of the catalytic converter is determined with the aid of a comparison of the downstream after the catalytic converter measured downstream exhaust gas lambda and a comparison with a downstream exhaust gas lambda threshold value.

9. The procedure according to claim 1, wherein the reaching of the preset measure for the conversion capability of the catalytic converter is determined with the aid of an occurring difference between the downstream exhaust gas lambda and the upstream exhaust gas lambda and a comparison with an exhaust gas lambda threshold value, wherein the downstream exhaust gas lambda is measured and the upstream exhaust gas lambda is measured or calculated.

10. The procedure according to claim 1, wherein the temperature of the pencil-type glow plug varies.

11. A device for operating a combustion engine, which comprises at least one pencil-type glow plug that is assigned to at least one cylinder, and in whose exhaust gas area at least one catalytic converter is arranged, wherein at least one customized control unit is provided for implementing the procedure according to one of the previous claims, which contains measures for implementing the procedure.

12. A control unit program, which carries out all steps of a procedure according to claim 1 if the program runs in a control unit.

13. A control unit program product with a program code that is stored on a machine-readable medium for implementing the procedure according to claim 1 if the program is carried out in a control unit.