Method and device for diagnosis of a particle filter arranged in the exhuast gas system of a petro-operated internal combustion engine

Abstract

Determining the presence of a particle filter in the exhaust gas tract of an engine, with the steps of determining a first exhaust gas temperature curve which occurs in the exhaust gas tract upstream of the particle filter; measuring a second exhaust gas temperature curve by a first temperature sensor arranged downstream of the particle filter; determining a first heat quantity by integration over a specific time of a first heat flow curve determined by a first exhaust gas mass flow, a first specific heat capacity and the first exhaust gas temperature curve; determining a second heat quantity by integration over the specific time of a second heat flow curve determined by a second exhaust gas mass flow, a second specific heat capacity and the second exhaust gas temperature curve, evaluating the first heat quantity and the second heat quantity to determine the presence of the correct particle filter.

Claims

1. A method for determining a presence of a correct particle filter in an exhaust gas tract of a petrol-operated internal combustion engine, the method comprising: determining a first exhaust gas temperature curve which occurs in the exhaust gas tract upstream of an installation position of a particle filter; measuring a second exhaust gas temperature curve by a first temperature sensor arranged downstream of the installation position of the particle filter; determining a first heat quantity by integration over a specific time of a first heat flow curve which is determined by a first exhaust gas mass flow, a first specific heat capacity and the first exhaust gas temperature curve, the determining of the first heat quantity comprises taking into account a change in the first specific heat capacity based on a change in air ratio, the air ratio being a ratio of air quantity supplied for combustion of a quantity unit of supplied fuel to a minimum air quantity necessary for complete combustion; determining a second heat quantity by integration over the specific time of a second heat flow curve which is determined by a second exhaust gas mass flow, a second specific heat capacity and the second exhaust gas temperature curve; and evaluating the first heat quantity and the second heat quantity in order to determine the presence of the correct particle filter.

2. The method of claim wherein 1, the first exhaust gas temperature curve is determined by a second temperature sensor which is arranged upstream of the installation position of the particle filter.

3. The method of claim 1, wherein the first exhaust gas temperature curve is determined by a predefined temperature model.

4. The method of claim 1, wherein integrating the first heat flow curve and the second heat flow curve occurs as soon as the first exhaust gas temperature curve has reached a specific first threshold value.

5. The method of claim 1, wherein the determining of the second heat quantity further comprises taking into account a change in the second specific heat capacity based on a change in the second exhaust gas temperature curve.

6. The method of claim 1, further comprising determining a ratio of the first heat quantity and the second heat quantity for ratio evaluation.

7. The method of claim 6, further comprising: providing a dividend of the ratio to be the difference between the first heat quantity and the second heat quantity; and providing a divisor of the ratio to be the first heat quantity.

8. The method of claim 7, further comprising: providing the ratio to be comparatively large if the particle filter is correctly installed in the installation position; and providing the ratio to be comparatively small if the particle filter is incorrectly installed in the installation position.

9. The method of claim 6, further comprising: providing a comparison value stored in a memory of an engine control unit (ECU) of the internal combustion engine; and using the comparison value in the ratio evaluation.

10. The method of claim 1, further comprising: providing a fault memory; and providing an entry into the fault memory if the evaluation of the first heat quantity and of the second heat quantity indicates that the particle filter is not correctly installed in the installation position.

11. The method of claim 1 further comprising: providing a fault display; providing a signal emitted to a driver from the fault display if the evaluation of the first heat quantity and of the second heat quantity indicates that the particle filter is not correctly installed in the installation position.

12. The method of claim 1, further comprising: providing a device for determining a presence of the particle filter in the exhaust gas tract of a petrol-operated internal combustion engine.

13. A device for determining a presence of a correct particle filter in an exhaust gas tract of a petrol-operated internal combustion engine, the device comprising a control unit configured for: determining a first exhaust gas temperature curve which occurs in the exhaust gas tract upstream of an installation position of the particle filter; measuring a second exhaust gas temperature curve by a first temperature sensor arranged downstream of the installation position of the particle filter; determining a first heat quantity by integration over a specific time of a first heat flow curve which is determined by a first exhaust gas mass flow, a first specific heat capacity and the first exhaust gas temperature curve, the determining of the first heat quantity comprises taking into account a change in the first specific heat capacity based a change in air ratio, the air ratio being a ratio of air quantity supplied for combustion of a quantity unit of supplied fuel to a minimum air quantity necessary for complete combustion; determining a second heat quantity by integration over the specific time of a second heat flow curve which is determined by a second exhaust gas mass flow, a second specific heat capacity and the second exhaust gas temperature curve; and evaluating the first heat quantity and the second heat quantity in order to determine the presence of the correct particle filter.

14. The device of claim 13, wherein the first exhaust gas temperature curve is determined by a second temperature sensor which is arranged upstream of the installation position of the particle filter.

15. The device of claim 13, wherein the first exhaust gas temperature curve is determined by a predefined temperature model.

16. The device of claim 13, wherein the control unit is further configured for integrating the first heat flow curve and of the second heat flow curve as soon as the first exhaust gas temperature curve has reached a specific first threshold value.

17. The device of claim 13, wherein the control unit is further configured for taking into account a change in the second specific heat capacity based on at least one of a change in the second exhaust gas temperature curve when determining the second heat quantity.

18. The device of claim 13, wherein if the evaluation of the first heat quantity and of the second heat quantity indicates that the particle filter is not correctly installed in the installation position the control unit is further configured to perform at least one of providing an entry into a fault memory or providing a signal emitted from a fault display.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment of the present disclosure is illustrated in the figures and will be explained in more detail with reference to the following description. The drawings show:

(2) FIG. 1 diagrammatically, an internal combustion engine with associated exhaust gas aftertreatment system according to a first embodiment;

(3) FIG. 2 diagrams of the temporal development of various parameters of an exhaust gas aftertreatment system according to a second embodiment, when a monolith is correctly installed in the particle filter;

(4) FIG. 3 diagrams of the temporal development of various parameters of an exhaust gas aftertreatment system according to a third embodiment, when there is no monolith in the particle filter.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

(6) FIG. 1 shows a block diagram of an internal combustion engine 10 with an exhaust gas tract 20. The exhaust gas tract 20 serves to discharge an exhaust gas 36 from at least one combustion chamber of the internal combustion engine 10 and after-treat the exhaust gas 36. Accordingly, the exhaust gas 36 flows through the exhaust gas tract 20. The exhaust gas tract 20 has an exhaust gas catalytic converter 21 and a particle filter 22 arranged downstream of the exhaust gas catalytic converter 21. Accordingly, the exhaust gas tract 20 includes a first exhaust gas sensor 23 and a second exhaust gas sensor 24. The first exhaust gas sensor 23 is arranged upstream of the exhaust gas catalytic converter 21, and the second exhaust gas sensor 24 is arranged downstream of the exhaust gas catalytic converter 21.

(7) Also, the exhaust gas tract 20 includes a first exhaust gas temperature sensor 25 and a second exhaust gas temperature sensor 26. The first exhaust gas temperature sensor 25 is arranged downstream of an installation position 35 of the particle filter 22, and the second exhaust gas temperature sensor 26 is arranged upstream of the installation position 35 of the particle filter 22.

(8) The first exhaust gas temperature sensor 25 is configured to measure the temperature of the exhaust gas 36 downstream of the particle filter 22. The first exhaust gas temperature sensor 25 is accordingly configured to measure over a specific time a second exhaust gas temperature curve T_dw of the temperature of the exhaust gas downstream of the particle filter 22.

(9) The second exhaust gas temperature sensor 26 is configured to measure the temperature of the exhaust gas 36 upstream of the particle filter 22. The second exhaust gas temperature sensor 26 is accordingly configured to measure over a specific time a first exhaust gas temperature curve T_up which prevails upstream of the particle filter 22.

(10) FIG. 1 also shows an engine control unit ECU which has a control unit 30. The control unit 30 has a block 31 for checking the presence of the particle filter 22, a block 32 containing a temperature model, and a fault memory 33. FIG. 1 also shows a fault display device 34 which is actuated by the control unit 30.

(11) Measurement results from the first exhaust gas sensor 23 and second exhaust gas sensor 24 are transmitted to the control unit 30. In addition, the first exhaust gas temperature curve T_up and the second exhaust gas temperature curve T_dw are transmitted to the control unit 30.

(12) A first standard temperature curve T_01 and a second standard temperature curve T_02 are also stored in the control unit 30. In addition, the control unit 30 is configured to determine, from an air ratio λ and the first exhaust gas temperature curve T_up, a first specific heat capacity cp_1 of the exhaust gas 36 upstream of the installation position 35 of the particle filter 22. Also, the control unit 30 is configured to determine, from the air ratio λ and the second exhaust gas temperature curve T_dw, a second specific heat capacity cp_2 of the exhaust gas 36 downstream of the installation position 35 of the particle filter 22.

(13) The control unit 30 is also configured to determine a first mass flow m′_1 of the exhaust gas 36 upstream of the installation position 35 of the particle filter 22 of the basis of data from the internal combustion engine 10. The control unit 30 is also configured to determine a second mass flow m′_2 of the exhaust gas 36 downstream of the installation position 35 of the particle filter 22. According to an embodiment, the first mass flow m′_1 corresponds to the second mass flow m′_2.

(14) The control unit 30 is configured to determine a first heat flow curve Q′_up from the first mass flow m′_1, the first specific heat capacity cp_1, the first exhaust gas temperature curve T_up and the first standard temperature curve T_01. Furthermore, the control unit 30 is configured to determine a second heat flow curve Q′_dw from the second mass flow m′_2, the second specific heat capacity cp_2, the second exhaust gas temperature curve T_dw and the second standard temperature curve T_02.

(15) The control unit 30 is furthermore configured to determine a first heat quantity Q_up transmitted during a specific time upstream of the installation position 35 of the particle filter 22. In addition, the control unit 30 is configured to determine a second heat quantity Q_dw transmitted during a specific time downstream of the installation position 35 of the particle filter 22. The control unit 30 is configured to first begin determination of the first heat quantity Q_up and the second heat quantity Q_dw as soon as the first exhaust gas temperature curve T_up has exceeded a first threshold value 40. Furthermore, the control unit 30 is configured to end the determination of the first heat quantity Q_up and the second heat quantity Q_dw as soon as the first exhaust gas temperature curve T_up has exceeded a second threshold value 41. According to another embodiment, the control unit 30 may also be configured to end the determination of the first quantity Q_up and the second heat quantity Q_dw as soon as a predefined time period has elapsed, wherein the time period begins as soon as the first exhaust gas temperature curve T_up has exceeded the first threshold value 40.

(16) According to another embodiment, the control unit 30 may also be configured to determine the first exhaust gas temperature curve T_up by means of a function for modelling the temperature FKT_TEMP_MOD.

(17) The control unit 30 is also configured to form a ratio i from the first heat quantity Q_up and the second heat quantity Q_dw, and compare this ratio i with a comparison value 43 (see FIGS. 2, 3). The control unit 30 is configured to conclude from this comparison whether the particle filter 22 is installed in the installation position 35, or to conclude whether a monolith is present in the particle filter 22.

(18) FIGS. 2 and 3 each show a first diagram 50 in which the temperature prevailing in the exhaust gas 36 upstream of the installation position 35 of the particle filter 22, and the temperature T prevailing in the exhaust gas 36 downstream of the installation position 35 of the particle filter 22, are shown over the time t. Accordingly, the first exhaust gas temperature curve T_up and the second exhaust gas temperature curve T_dw are shown. In addition, the first diagrams 50 each show the first threshold value 40 and the second threshold value 41. It is clear that integration of the first heat flow curve Q′_up first begins as soon as the first exhaust gas temperature curve T_up has exceeded the first threshold value 40.

(19) The first diagram 50 in FIG. 2, and the first diagram 50 in FIG. 3, differ in particular in the second exhaust gas temperature curve T_dw. In the first diagram 50 of FIG. 2, the second exhaust gas temperature curve T_dw follows the rise of the first exhaust gas temperature curve T_up comparatively slowly. In the first diagram 50 of FIG. 3, the second exhaust gas temperature curve T_dw follows the rise of the first exhaust gas temperature curve T_up comparatively quickly.

(20) The first diagram 50 of FIGS. 2 and 3 furthermore shows a first area 52 which extends below the first exhaust gas temperature curve T_up between a first time t1 and a temporally successive second time t2. In addition, a second area 54 is shown which extends below the second exhaust gas temperature curve T_dw between the first time t1 and the second time t2. Also, a difference area 56 is shown which is determined from the difference between the first area 52 and the second area 54. It is clear that the difference area 56 of the first diagram 50 in FIG. 2 is much larger than the difference area 56 of the first diagram 50 in FIG. 3.

(21) In addition, FIGS. 2 and 3 each show a second diagram 60, which in each case represents the first heat quantity Q_up determined during the time t. For this, the first heat flow curve Q′_up is shown over the time t. It is clear from the diagrams that determination of the transmitted first heat quantity begins as soon as time t1 has been passed, and ends as soon as the third threshold value 42 is reached at time t2. The area below the curve shown in the second diagrams 60, which represents the first heat flow curve Q′_up, represents the first heat quantity Q_up transmitted in the period from time t1 to time t2.

(22) FIGS. 2 and 3 each also show a third diagram 70, which in each case shows a ratio i of the first heat quantity Q_up and the second heat quantity Q_dw over the time, in particular from time t1 to time t2. Also, a comparison value 43 is shown. The third diagram 70 of FIG. 2 differs from third diagram 70 of FIG. 3 in that the ratio i n the third diagram 70 of FIG. 2 permanently lies above the comparison value 43, whereas the ratio i in the third diagram 70 of FIG. 3 permanently lies below the comparison value 43. In the present case, accordingly it may be concluded from the first diagram 70 of FIG. 2 that the particle filter 22 is correctly installed, and it may be concluded from the third diagram 70 of FIG. 3 that the particle filter 22 is not correctly installed.

(23) The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.

LIST OF DESIGNATIONS

(24) 10 Internal combustion engine

(25) 20 Exhaust gas tract

(26) 21 Exhaust gas catalytic converter

(27) 22 Particle filter

(28) 23 First exhaust gas sensor

(29) 24 Second exhaust gas sensor

(30) 25 First exhaust gas temperature sensor

(31) 26 Second exhaust gas temperature sensor

(32) 30 Control unit

(33) 31 Block function for checking particle filter

(34) 32 Block temperature model

(35) 33 Fault memory

(36) 34 Fault display device

(37) 35 Installation position

(38) 36 Exhaust gas

(39) 40 First threshold value

(40) 41 Second threshold value

(41) 42 Third threshold value

(42) 43 Comparison value

(43) 50 First diagram

(44) 52 First area

(45) 54 Second area

(46) 56 Difference area

(47) 60 Second diagram

(48) 70 Third diagram

(49) T Temperature

(50) t Time

(51) t1 First time

(52) t2 Second time

(53) T_up First exhaust gas temperature curve

(54) T_dw Second exhaust gas temperature curve

(55) T_01 First standard temperature curve

(56) T_02 Second standard temperature curve

(57) ECU Engine control unit

(58) FKT_DIAG_OPF Function for checking particle filter

(59) FKT_TEMP_MOD Function for modelling temperature

(60) m′_1 First mass flow

(61) m′_2 Second mass flow

(62) cp_1 First specific heat capacity

(63) cp_2 Second specific heat capacity

(64) λ Air ratio

(65) Q′_up First heat flow curve

(66) Q′_dw Second heat flow curve

(67) Q_up First heat quantity

(68) Q_dw Second heat quantity

(69) i Ratio