Method and Device for Inspecting and Safeguarding a Functionality of an Exhaust Gas Aftertreatment System of a Combustion Engine

Abstract

The disclosure relates to a method for checking and ensuring the functionality of an exhaust gas aftertreatment system of an internal combustion engine. The exhaust gas aftertreatment system has a catalytic converter and a voltage source. The catalytic converter has a catalytic converter area and an electrical heating device which is selectively supplied with electrical energy from the voltage source. The method includes determining an actual value which is characteristic of an ohmic resistance of the heating device. The actual value being determined by using an electrical current strength supplied to the heating device and an electrical voltage supplied to the heating device from the voltage source. The method also includes providing a setpoint value which is characteristic of an expected ohmic resistance of the heating device. The setpoint value takes into account a specific heating-up behavior of the heating device and an expected long-term behavior of the catalytic converter.

Claims

1. A method for checking and ensuring functionality of an exhaust gas aftertreatment system of an internal combustion engine, the exhaust gas aftertreatment system includes a catalytic converter and a voltage source, the catalytic converter having a catalytic converter area and an electrical heating device which is selectively supplied with electrical energy from the voltage source, wherein the method comprising: determining an actual value which is characteristic of an ohmic resistance of the heating device, the actual value being determined by using an electrical current strength supplied to the heating device and an electrical voltage supplied to the heating device from the voltage source; providing a setpoint value which is characteristic of an expected ohmic resistance of the heating device, the setpoint value taking into account a specific heating-up behavior of the heating device and an expected long-term behavior of the catalytic converter; and comparing the actual value with the setpoint value in order to check and ensure whether the heating device is functioning in accordance with the specific heating-up behavior and the expected long-term behavior.

2. The method of claim 1, wherein, to compare the actual value with the setpoint value, a first difference is formed from the actual value and the setpoint value and the first difference is compared with a first threshold value, it being detected that the heating device is not functioning in accordance with the specific heating-up behavior and the expected long-term behavior if the first difference deviates from the first threshold value by at least a first specific amount.

3. The method of claim 1, wherein the exhaust gas aftertreatment system has a voltage measuring device arranged at an end of a transmission cable assigned to the heating device that transmits electrical energy from the voltage source to the heating device during operation of the heating device, the voltage measuring device being set up to determine a measurement signal which is characteristic of the electrical voltage arriving at the heating device during operation, and the actual value being determined by using the measurement signal of the voltage measuring device.

4. The method of claim 3, wherein the method further comprises: comparing the measurement signal of the voltage measuring device with a setpoint voltage value which is characteristic of an expected electrical voltage arriving at the heating device during the operation of the heating device from the voltage source, wherein, to compare the measurement signal with the setpoint voltage value, a second difference is formed from the measurement signal and the setpoint voltage value and the second difference is compared with a second threshold value, it being detected that the transmission cable is not functioning in accordance with its expected functionality if the second difference deviates from the second threshold value by at least a second specific amount.

5. The method of claim 4, wherein the setpoint value and/or the setpoint voltage value take(s) into account current ambient conditions.

6. The method of claim 4, wherein the setpoint value and/or the setpoint voltage value is/are provided as a characteristics map.

7. The method of claim 3, wherein the determination of the actual value and/or the determination of the measurement signal is/are determined by using an electrical test current strength supplied to the heating device and an electrical test voltage supplied to the heating device from the voltage source.

8. The method of claim 7, wherein the electrical test voltage is 0.5 volts to 5 volts.

9. The method of claim 1, wherein the voltage source is designed to output a maximum electrical voltage that is greater than or equal to 36 volts.

10. The method of claim 4, wherein the selective energy supply of the electrical heating device from the voltage source is controlled by the comparison of the actual value with the setpoint value and/or by the comparison of the measurement signal with the setpoint voltage value.

11. A device for checking and ensuring functionality of an exhaust gas aftertreatment system of an internal combustion engine, the exhaust gas aftertreatment system includes a catalytic converter and a voltage source, the catalytic converter having a catalytic converter area and an electrical heating device which is selectively supplied with electrical energy from the voltage source, the device includes a control unit designed for controlling a method, the method comprising: determining an actual value which is characteristic of an ohmic resistance of the heating device, the actual value being determined by using an electrical current strength supplied to the heating device and an electrical voltage supplied to the heating device from the voltage source; providing a setpoint value which is characteristic of an expected ohmic resistance of the heating device, the setpoint value taking into account a specific heating-up behavior of the heating device and an expected long-term behavior of the catalytic converter; and comparing the actual value with the setpoint value in order to check and ensure whether the heating device is functioning in accordance with the specific heating-up behavior and the expected long-term behavior.

12. The device of claim 11, wherein, to compare the actual value with the setpoint value, a first difference is formed from the actual value and the setpoint value and the first difference is compared with a first threshold value, it being detected that the heating device is not functioning in accordance with the specific heating-up behavior and the expected long-term behavior if the first difference deviates from the first threshold value by at least a first specific amount.

13. The device of claim 11, wherein the exhaust gas aftertreatment system has a voltage measuring device arranged at an end of a transmission cable assigned to the heating device that transmits electrical energy from the voltage source to the heating device during operation of the heating device, the voltage measuring device being set up to determine a measurement signal which is characteristic of the electrical voltage arriving at the heating device during operation, and the actual value being determined by using the measurement signal of the voltage measuring device.

14. The device of claim 13, wherein the method further comprises: comparing the measurement signal of the voltage measuring device with a setpoint voltage value which is characteristic of an expected electrical voltage arriving at the heating device during the operation of the heating device from the voltage source, wherein, to compare the measurement signal with the setpoint voltage value, a second difference is formed from the measurement signal and the setpoint voltage value and the second difference is compared with a second threshold value, it being detected that the transmission cable is not functioning in accordance with its expected functionality if the second difference deviates from the second threshold value by at least a second specific amount.

15. The device of claim 14, wherein the setpoint value and/or the setpoint voltage value take(s) into account current ambient conditions.

16. The device of claim 14, wherein the setpoint value and/or the setpoint voltage value is/are provided as a characteristics map.

17. The device of claim 11, wherein the determination of the actual value and/or the determination of the measurement signal is/are determined by using an electrical test current strength supplied to the heating device and an electrical test voltage supplied to the heating device from the voltage source.

18. The device of claim 17, wherein the electrical test voltage is 0.5 volts to 5 volts.

19. The device of claim 11, wherein the voltage source is designed to output a maximum electrical voltage that is greater than or equal to 36 volts.

20. The device of claim 14, wherein the selective energy supply of the electrical heating device from the voltage source is controlled by the comparison of the actual value with the setpoint value and/or by the comparison of the measurement signal with the setpoint voltage value.

Description

DESCRIPTION OF DRAWINGS

[0031] FIG. 1 shows a schematic representation of an exhaust gas aftertreatment system with a control unit.

[0032] FIG. 2 shows a block diagram of a method for checking and ensuring the functionality of an exhaust gas aftertreatment system.

[0033] Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

[0034] FIG. 1 shows a schematic representation of an exhaust gas aftertreatment system 100 of an internal combustion engine. The exhaust gas aftertreatment system 100 has a catalytic converter 110, a voltage source 140 and a control unit 200. The catalytic converter 110 has a catalytic converter area 112 and an electrical heating device 114. The catalytic converter area 112 is set up to reduce pollutants from an exhaust gas 102. The heating device 114 is set up to heat the catalytic converter area 112. The heating device 114 is arranged upstream of the catalytic converter area 112 in the direction of exhaust gas flow. The catalytic converter 110 additionally has an exhaust gas inlet area 120 and an exhaust gas outlet area 130. The exhaust gas inlet area 120 is designed to allow exhaust gas 102 to flow into the catalytic converter 110. The exhaust gas outlet area 130 is designed to allow exhaust gas 102 to flow out of the catalytic converter 110.

[0035] The voltage source 140, for example a rechargeable battery or a battery, is designed to supply the heating device 114 with electrical energy. In this respect, the exhaust gas aftertreatment system 100 has a transmission cable 142 and the heating device 114 has a power connection 116. The electrical energy flows to the heating device 114 by way of the transmission cable 142 and the power connection 116.

[0036] As shown, the exhaust gas aftertreatment system 100 has a voltage measuring device 170. The voltage measuring device 170 is arranged at one end of the transmission cable 142 that is assigned to the heating device 114. The voltage measuring device 170 is accordingly arranged in the immediate vicinity of the heating device 114. The voltage measuring device 170 is designed to detect a value which is characteristic of an incoming voltage transmitted from the voltage source 140 to the heating device 114. Accordingly, the voltage measuring device 170 detects a value that takes transmission losses of the transmission cable 142 into account.

[0037] The control unit 200 has a computing unit 210, a program/data memory 220 and an error memory 230. In some examples, the recorded measurement data of the voltage measuring device 170 are transmitted to the control unit 200. In addition, measurement data of the voltage source 140 are transmitted to the control unit 200. The control unit 200 is designed to control the exhaust gas aftertreatment system 100 and also to check the exhaust gas aftertreatment system 100 for its functionality.

[0038] In some implementations, the control unit 200 is designed to carry out a method shown in FIG. 2 for checking and ensuring the functionality of the exhaust gas aftertreatment system 100. Accordingly, the control unit 200 is designed to determine an actual value 302 which is characteristic of an ohmic resistance of the heating device 114. At least one first actual value condition 310 and a second actual value condition 312 are taken into account for the actual value determination. The first actual value condition 310 is an electrical current strength supplied to the heating device 114. The second actual value condition 312 is an electrical voltage supplied to the heating device 114. In some examples, the control unit 200 is additionally designed to provide a setpoint value 304. It may be provided, for example, from the program/data memory 220. The setpoint value 304 here is characteristic of an expected ohmic resistance of the heating device 114. A first setpoint condition 314, a second setpoint condition 316, and a third setpoint condition 318 may be included in the process of providing the setpoint value 304. The first setpoint condition 314 takes into account a specific heating-up behavior of the heating device 114. The second setpoint condition 316 takes into account an expected long-term behavior of the catalytic converter 110. The third setpoint condition 318 takes into account ambient conditions such as an ambient temperature.

[0039] The control unit 200 is also designed to carry out a comparison of the actual value 302 with the setpoint value 304. In this respect, the computing unit 210 of the control unit 200 may be used. For the comparison of the actual value 302 with the setpoint value 304, in some examples, a first difference is formed from the actual value 302 and the setpoint value 304 by a first difference formation 380. The first difference is then compared with a first threshold value 360. The threshold value 360 may, for example, be stored in the program/data memory 220. The first difference may be formed continuously during the operation of the exhaust gas aftertreatment system 100. In some examples, the control unit 200 is designed to detect that the heating device 114 is not functioning as desired if the first difference deviates from the first threshold value 360 by at least a first specific amount 400. The first specific amount 400 may also be stored in the program/data memory 220 and provided from it. This first result formation 420 is also carried out with the computing unit 210. If it is detected that the heating device 114 is not functioning properly, an error entry may be made in the error memory 230. In addition, it is conceivable that an operator of the internal combustion engine or a driver of a vehicle in which the internal combustion engine with the exhaust gas aftertreatment system 100 is installed is shown an error by an error display device.

[0040] The control unit 200 is additionally designed to determine a measurement signal 306. When determining the measurement signal 306, a first measurement signal condition 320 is included. The first measurement signal condition 320 is in this case characteristic of a signal that is measured with the voltage measurement device 170 at the end of the transmission cable 142 facing the heating device 114. The control unit 200 may be additionally designed to provide a setpoint voltage value 308 by the program/data memory 220. The setpoint voltage value 308 may depend on a first voltage setpoint condition 322 and a second voltage setpoint condition 324. The first voltage setpoint condition 322 takes into account the expected electrical voltage that is intended to arrive at the heating device 114. The second voltage setpoint condition 324 takes into account at least one ambient parameter.

[0041] The control unit 200 is additionally designed to perform a second difference formation 390 with the measurement signal 306 and the setpoint voltage value 308 by the computing unit 210. According to this example with the computing unit 210, the control unit 200 is additionally designed to compare the result of the second difference formation 390 with a second threshold value 370. The second threshold value 370 may be stored in the program/data memory 220 of the control unit 200. With the second difference formation 340 and the comparison of the second difference formation 390 with the second threshold value 370, it can be determined whether the transmission of the electrical energy from the voltage source 140 to the heating device 114 is functioning properly. A second result formation 430 is carried out for this check. It is detected here that the transmission cable 142 is not functioning in accordance with its expected functionality if the second difference deviates from the second threshold value 370 by at least a second specific amount 410. The second specific amount 410 may be stored in the program/data memory 220 of the control unit 200.

[0042] As such, the method makes it possible, on the one hand, to check whether the exhaust gas aftertreatment system 100 is functioning properly and otherwise, if necessary, determine which components of the exhaust gas aftertreatment system 100 are not functioning properly. In addition, if problems are found, the control of the exhaust gas aftertreatment system 100 may be adapted in order to ensure that the functionality continues to be ensured. Overall, despite the possibility of checking, the exhaust gas aftertreatment system 100 has a simple construction, does not require any additional components and nevertheless allows the functionality of the exhaust gas aftertreatment system 100 to be checked. Overall, this makes the method and the device correspondingly reliable and robust.

[0043] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.