System and method for determining a parameter indicative of an amount of a reducing agent

Patent metadata

Field	Value
Publication number	US-10060320-B2
Application number	US-201315106193-A
Country	US
Kind code	B2
Filing date	Dec 19, 2013
Priority date	Dec 19, 2013
Publication date	Aug 28, 2018
Grant date	Aug 28, 2018

Abstract

A system is provided for determining a parameter indicative of an amount of a reducing agent in a selective catalytic reduction (SCR) module of a vehicle, the system including: the SCR module having at least one passage for transporting a stream of gas and an SCR catalyst for converting NOx emissions, and having an extension in an axial direction, at least one first antenna unit configured to transmit and receive a microwave signal. Moreover, the first antenna unit is arranged outside the SCR module and configured to transmit microwave signals towards the SCR catalyst and to receive a microwave signal reflected within the SCR module. The system further includes processing circuitry connected to the first antenna unit and configured to determine a difference between the transmitted microwave signal and the received reflected microwave signal and to determine a parameter indicative of the amount of a reducing agent in the SCR catalyst based on the determined difference between the transmitted microwave signal and the received reflected microwave signal. Moreover, the invention relates to a method for determining a parameter indicative of an amount of a reducing agent in a system of a vehicle.

First claim

The invention claimed is:

1. A system for determining a parameter indicative of an amount of a reducing agent in a selective catalytic reduction (SCR) module of a vehicle, the system comprising:
the SCR module having at least one passage for transporting a stream of gas and an SCR catalyst for converting NOx emissions, and having an extension in an axial direction,
a first antenna unit configured to transmit microwave signal and receive a microwave signal (SR),
wherein the first antenna unit is arranged outside the SCR module and configured to transmit microwave signals towards the SCR catalyst and to receive a microwave signal reflected within the SCR module,
wherein the system further comprises:
processing circuitry connected to the first antenna unit and configured to determine a first difference between the transmitted microwave signal and the received reflected microwave signal, and to determine a parameter indicative of the amount of a reducing agent in the SCR catalyst based on the determined first difference between the transmitted microwave signal and the received reflected microwave signal (SRef R),
wherein the first antenna unit is configured to transmit microwave signals across a cross-sectional area of the SCR module, and the SCR module is configured to transport the stream of gas parallel to the axial direction, the first antenna unit being positioned within a distance in the axial direction limited by end portions of the SCR module, and the processing circuitry being configured to determine an amount of NH 3 in the SCR catalyst at a plurality of axial positions along an axial length of the SCR module.

2. The system according to claim 1 , wherein the reducing agent is at least one of anhydrous ammonia, aqueous ammonia or urea.

3. The system according to claim 1 , wherein the reducing agent comprises at least one of anhydrous ammonia, aqueous ammonia or urea, or a mixture thereof.

4. The system according to claim 1 , wherein the amount of the reducing agent correlates to an amount of NH3.

5. The system according to claim 1 , wherein the first antenna unit is configured to transmit microwave signals across a cross sectional area (TA) of the SCR module.

6. The system according to claim 1 , wherein the system further comprises:
a second antenna unit configured to receive the transmitted microwave signal from the first antenna unit, and connected to the processing circuitry,
wherein the second antenna unit is arranged outside the SCR module and spaced apart from the first antenna unit,
the processing circuitry is configured to determine at least one of the first difference between the transmitted microwave signal from the first antenna unit and the received reflected microwave signal received by the first antenna unit and a second difference between the transmitted microwave signal from the first antenna unit and a received microwave signal received by the second antenna unit to determine a parameter indicative of the amount of a reducing agent in the SCR catalyst based on the at least one of the determined first difference and the determined second difference.

7. The system according to claim 1 , wherein the system further comprises:
a second antenna unit configured to transmit a microwave signal to the first antenna unit, and connected to the processing circuitry,
wherein the second antenna unit is arranged outside the SCR module and spaced apart from the first antenna unit,
the processing circuitry is configured to determine at least one of the first difference between the transmitted microwave signal from the first antenna unit and the received reflected microwave signal received by the first antenna unit and a third difference between the transmitted microwave signal from the second antenna unit and the received microwave signal (SR 3 ) received by the first antenna unit to determine a parameter indicative of the amount of a reducing agent in the SCR catalyst based on the at least one of the determined first difference and the determined third difference.

8. The system according to claim 6 , wherein the first antenna unit and the second antenna unit are arranged on the same axial distance, as seen in the axial direction.

9. The system according to claim 6 , wherein the first antenna unit is arranged spaced apart from the second antenna unit, as seen in the axial direction.

10. The system according to claim 1 , wherein at least one of the position of the first antenna unit and the position of the second antenna unit is movable along the axial direction.

11. The system according to claim 6 , wherein the system further comprises a third antenna unit configured to transmit and receive a microwave signal, the third antenna unit is connected to the processing circuitry and arranged outside the SCR module, and spaced apart from the first antenna unit and second antenna unit,
wherein the first antenna unit, the second antenna unit and the third antenna unit are configured to transmit and receive signals intermittently between each other.

12. The system according to claim 11 , wherein the processing circuitry is configured to:
determine at least any one of the first difference, the second difference, the third difference, a fourth difference between the transmitted microwave signal from the first antenna unit and the received microwave signal (SR 5 ) received by the third antenna unit, and a fifth difference between the transmitted microwave signal (ST 4 ) from the third antenna unit and the received microwave signal (SR 4 ) received by the first antenna unit, and determine a parameter indicative of the amount of the reducing agent in the SCR catalyst based on the at least any one of the determined first difference, second difference, third difference, fourth difference and fifth difference.

13. The system according to any one of claim 11 , wherein the first antenna unit, the second antenna unit and the third antenna unit are arranged on the same axial distance, as seen in the axial direction.

14. The system according to any one of claim 11 , wherein the first antenna unit, the second antenna unit and the third antenna unit are spaced apart from each other, as seen in the axial direction.

15. The system according to claim 1 , wherein the system further comprises a casing surrounding the SCR module and that any one of the antenna units is positioned outside the casing.

16. The system according to claim 1 , wherein at least one of the microwave signal transmitted from any one of the first antenna unit, the second antenna unit and the third antenna unit is within a bandwidth having a pre-determined radio frequency.

17. The system according to claim 1 , wherein the SCR module is a honeycomb structure.

18. The system according to claim 17 , wherein the SCR catalyst is coated onto a wall surface of the honeycomb structure.

19. The system according to claim 17 , wherein the SCR catalyst is a part of the honeycomb structure.

20. The system according to claim 1 , wherein the SCR catalyst is a zeolite-based catalyst or vanadia-based catalyst.

21. An exhaust aftertreatment system for receiving an exhaust gas, the exhaust aftertreatment system comprising the system according to claim 1 and further comprising an injector for supplying a reducing agent to the exhaust gas at a position upstream of the SCR module.

22. The exhaust aftertreatment system according to claim 21 , further comprising a diesel particulate filter arranged upstream of the injector, and a diesel oxygen cat

Assignees

• Volvo Truck Corp

Inventors

• Blomgren Fredrik
• Dahl Johan

Classifications

• F01N11/00

  Monitoring or diagnostic devices for exhaust-gas treatment apparatus · CPC title

• F01N2900/1818

  Concentration of the reducing agent · CPC title

• F01N2560/12

  Other sensor principles, e.g. using electro conductivity of substrate or radio frequency · CPC title

• F01N2590/08

  for heavy duty applications, e.g. trucks, buses, tractors, locomotives · CPC title

• F01N2560/021

  for measuring or detecting ammonia NH3 · CPC title