CONSTANT MASS FLOW INJECTION SYSTEM

• US 20160108789A1
• Filed: 10/21/2014
• Published: 04/21/2016
• Est. Priority Date: 10/21/2014
• Status: Active Grant

• Current Assignee: Cummins Emission Solutions Inc.
• Original Assignee: Cummins Emission Solutions Inc.
• Inventors: Mitchell, Douglas A.
• Granted Patent: US 9,453,446 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F01N 2610/02 the substance being ammonia or urea
• CPC Class Codes: F01N 2610/06 the substance being in the gaseous form
• CPC Class Codes: F01N 2610/08 with prior mixing of the substances with a gas, e.g. air
• CPC Class Codes: F01N 2610/085 Controlling the air supply
• CPC Class Codes: F01N 2610/1453 Sprayers or atomisers; Arrangement thereof in the exhaust apparatus
• CPC Class Codes: F01N 2900/0414 using a state observer
• CPC Class Codes: F01N 2900/1812 Flow rate
• CPC Class Codes: F01N 2900/1824 Properties of the air to be mixed with added substances, e.g. air pressure or air temperature
• CPC Class Codes: F01N 3/206 Adding periodically or continuously substances to exhaust gases for promoting purification, e.g. catalytic material in liquid form, NOx reducing agents F01N3/2066 takes precedence
• CPC Class Codes: F01N 3/2066 Selective catalytic reduction [SCR]
• CPC Class Codes: F01N 3/208 Control of selective catalytic reduction [SCR], e.g. dosing of reducing agent
• CPC Class Codes: F01N 3/225 Electric control of additional air supply
• CPC Class Codes: F01N 3/32 using air pump using jet air pumps F01N3/34; pumps in general F04
• CPC Class Codes: F01N 9/00 Electrical control of exhaust gas treating apparatus monitoring or diagnostic devices for exhaust-gas treatment apparatus F01N11/00; conjoint electrical control of two or more combustion engine functions F02D43/00
• CPC Class Codes: F02B 37/164 the bypassed air being used in an auxiliary apparatus, e.g. in an air turbine
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

Exhaust aftertreatment assemblies and methods of manufacturing and operating exhaust aftertreatment assemblies. The exhaust aftertreatment assembly includes a reductant delivery device, a reductant source fluidly coupled to the reductant delivery device, a mixing chamber positioned between the reductant delivery device and the reductant source and thereby fluidly coupling the reductant source to the reductant delivery device, and a compressed air source fluidly coupled to the mixing chamber upstream of the mixing chamber with respect to the reductant delivery device. The compressed air source provides compressed air to mix with reductant in the mixing chamber.

Claims

1. An exhaust aftertreatment assembly, comprising:

a reductant delivery device;

a reductant source fluidly coupled to the reductant delivery device;

a mixing chamber fluidly coupled to the reductant delivery device, the mixing chamber positioned between the reductant delivery device and the reductant source and thereby fluidly coupling the reductant source to the reductant delivery device; and

a compressed air source fluidly coupled to the mixing chamber upstream of the mixing chamber with respect to the reductant delivery device, the compressed air source providing compressed air so as to mix with reductant in the mixing chamber.

2. The exhaust aftertreatment assembly of claim 1, further comprising at least one sensor configured to sense a value correlated to the quantity of reductant released from the reductant source.

3. The exhaust aftertreatment assembly of claim 2, further comprising a controller configured to cause a quantity of compressed air from the compressed air source to mix with the reductant released from the reductant source in the mixing chamber based on the sensed value.

4. The exhaust aftertreatment assembly of claim 3, wherein the causing of a quantity of compressed air from the compressed air source to mix with the reductant includes venting recirculated exhaust gas compressed by a turbine to the compressed air source.

5. The exhaust aftertreatment assembly of claim 3, further comprising a regulator coupled in a fluid flow path between the mixing chamber and the compressed air source, the regulator configured to cause a quantity of compressed air from the compressed air source to mix with a quantity of reductant released from the reductant source, the regulator electrically coupled to the controller.

6. The exhaust aftertreatment assembly of claim 5, wherein the regulator includes a valve operable to control the flow rate of compressed air from the compressed air source to the mixing chamber.

7. The exhaust aftertreatment assembly of claim 1, wherein the reductant source includes a tank of gaseous NH₃.

8. The exhaust aftertreatment assembly of claim 1, wherein the reductant delivery device includes a lattice of tubes including a plurality of openings therein.

9. The exhaust aftertreatment assembly of claim 1, further comprising a pressure sensor positioned in the mixing chamber, the pressure sensor configured to provide a pressure reading of fluid in the mixing chamber, the pressure reading configured to control injection of compressed air from the compressed air source into the mixing chamber.

10. The exhaust aftertreatment assembly of claim 1, wherein the reductant delivery device comprises a reductant injector.

11. An engine assembly, comprising:

an internal combustion engine;

an exhaust aftertreatment system fluidly coupled to the internal combustion engine;

a reductant delivery device fluidly coupled to the exhaust aftertreatment system;

a reductant source fluidly coupled to the reductant delivery device;

a mixing chamber positioned between the reductant delivery device and the reductant source, the mixing chamber fluidly coupling the reductant source to the reductant delivery device; and

a compressed air source fluidly coupled to the mixing chamber upstream of the mixing chamber with respect to the reductant delivery device, the compressed air source providing compressed air to mix with reductant in the mixing chamber.

12. The engine assembly of claim 11, further comprising a controller configured to cause a quantity of compressed air from the compressed air source to mix with the reductant released from the reductant source in the mixing chamber.

13. A method of treating engine exhaust comprising:

determining a difference between a predetermined optimized mass flow rate for a reductant delivery device fluidly coupled to an exhaust aftertreatment system and a commanded reductant mass flow rate of reductant from a reductant source fluidly coupled to the exhaust aftertreatment system, the commanded reductant mass flow rate determined to treat an exhaust stream of exhaust in the exhaust aftertreatment system by injection of the reductant via the reductant delivery device into the exhaust aftertreatment system, the predetermined optimized mass flow rate determined to produce equalized fluid flow from a plurality of injection apertures in the reductant delivery device; and

causing, based on the determined difference and in response to a release of the reductant, mixing, in a mixing chamber upstream of the reductant delivery device, of a quantity of compressed air from a compressed air source with the reductant released from the reductant source pursuant to the commanded reductant mass flow rate of reductant.

14. The method of claim 13, further comprising:

determining the commanded reductant mass flow rate of reductant determined to treat the exhaust stream of exhaust in the exhaust aftertreatment system.

15. The method of claim 13, wherein causing mixing includes opening a regulator coupled in a fluid flow path between the mixing chamber and the compressed air source, the regulator controlling the flow of compressed air from the compressed air source to the mixing chamber.

16. The method of claim 13, further comprising:

receiving a value corresponding to a pressure in the mixing chamber; and

controlling the quantity of compressed air from the compressed air source mixed with the reductant based upon the received value.

17. The method of claim 13, wherein the reductant delivery device comprises a reductant injector.

18. A control system for treating an engine exhaust stream comprising:

a sensing module electrically coupled to at least one regulator configured to cause release of reductant from a reductant source fluidly coupled to the exhaust aftertreatment system at a commanded reductant mass flow rate, the sensing module configured to determine a difference between a predetermined optimized mass flow rate for a reductant delivery device fluidly coupled to the exhaust aftertreatment system and the commanded reductant mass flow rate of reductant from the reductant source, the predetermined optimized mass flow rate determined to produce equalized fluid flow from a plurality of injection apertures in the reductant delivery device; and

an actuation module configured to cause a quantity of compressed air from a compressed air source to mix with the reductant released from the reductant source.

19. The control system of claim 18, wherein the sensing module includes a timer configured to measure the duration of release of reductant from the reductant source for determining the commanded reductant mass flow rate.

20. The control system of claim 18, wherein the actuation module is electrically coupled to a regulator positioned in a fluid flow path between a mixing chamber and the compressed air source, the mixing chamber fluidly coupled to the reductant delivery device, the mixing chamber positioned between the reductant delivery device and the reductant source and thereby fluidly coupling the reductant source to the reductant delivery device.

21. The control system of claim 18, wherein the reductant source includes a tank of gaseous NH₃.

22. A method of treating engine exhaust comprising:

mixing a reductant with compressed air in a mixing chamber fluidly coupled to a reductant delivery device upstream of the reductant delivery device;

transferring the reductant and compressed air mixture from the mixing chamber to the reductant delivery device; and

injecting the reductant and compressed air mixture into an exhaust aftertreatment system coupled to an internal combustion engine.

23. The method of claim 22, wherein the mixing of the reductant with compressed air in the mixing chamber comprises determining a quantity of compressed air required to increase the reductant and compressed air mixture to a predetermined quantity.

24. The method of claim 22, wherein the reductant delivery device comprises a reductant injector.