Combustion chamber

Abstract

A system for treating particulates of an engine's exhaust is provided. The system comprises a filter configured to collect particulate matter and a device for regenerating the filter. The device comprises a housing, a fuel injector configured to inject fuel, an igniter configured to ignite the injected fuel, and a combustion chamber. The device is characterized in that the cross section of the combustion chamber converges from an inlet to an outlet.

Description

TECHNICAL FIELD

The present disclosure is directed to a burner that comprises a combustion chamber with a converging shape. In one embodiment, the combustion chamber comprises a conical shape that converges in diameter from its inlet to outlet. The disclosed burner may be used for various purposes, including the regeneration of a particulate trap within an internal combustion engine's exhaust system.

BACKGROUND

Internal combustion engines, including diesel engines, gasoline engines, and natural gas engines, for example, generally emit air pollutants. These air pollutants are generally composed of both gaseous matters and particulate matters. Particulate matter from a diesel engine typically includes ash and soot. Soot is composed of carbon particles that were not combusted during the combustion process.

Over the past several years, engine emission regulations have become increasingly stringent, driving engine manufacturers toward improving and developing new emissions-reducing technologies. Many of these technologies are aimed at minimizing particulate matters emitted from the engine.

In doing so, some engine manufacturers have developed systems to treat engine exhaust before it enters the environment. Some of these systems employ exhaust treatment devices such as particulate traps to filter particulate matter from the exhaust flow. A particulate trap generally includes a filter material designed to capture particulate matter. After an extended period of use, unfortunately, the filter material may become saturated with particulate matter, thereby hindering the exhaust gas that flows through the particulate trap.

The collected particulate matter may be removed from the filter material through a process called regeneration—burning. Because soot is composed of unburned hydrocarbons, soot has a propensity for combusting when exposed to oxygen and heat.

A particulate trap may be regenerated by increasing the temperature of the filter material and the trapped particulate matter above the combustion temperature of the particulate matter, thereby burning away the collected particulate matter. This increase in temperature may be effectuated by various means. For example, some systems may employ a heating element to directly heat one or more portions of the particulate trap (e.g., the filter material or the external housing). Other systems have been configured to heat exhaust gases upstream of the particulate trap.

Some of these systems that heat the upstream exhaust gases may work by altering one or more engine operating parameters, such as the ratio of air-to-fuel in the combustion chambers. Other systems may heat the exhaust gases upstream of the particulate trap with, for example, a burner disposed within an exhaust conduit leading to the particulate trap.

In systems that heat exhaust gases upstream of the particulate trap, the heated gases then flow through the particulate trap and transfer heat to the filter material and captured particulate matter. The transferred heat promotes regeneration of the filter by burning the accumulated soot.

U.S. Pat. No. 5,771,683 to Webb (“Webb”) discloses an auxiliary heat source including a cylindrical flame containment chamber. In particular, FIG. 3 of Webb discloses a relatively cylindrical chamber 42a. The efficiency—or completeness—of the combustion within the combustion chamber is effected by how the flame from the combustor mixes with the exhaust gas entering into the combustor housing. Further, the location of the combustion chamber in the cylindrical combustor housing may cause high flow resistance. This high flow resistance causes high backpressure on the turbine exit of the turbocharger. This high back pressure results in reduced fuel efficiency, lessened transient response, increased thermal loading, reduced high-altitude capability, and loss of engine rating capability, to name a few.

The disclosed regeneration assembly is directed toward overcoming one or more of the problems set forth above.

SUMMARY

In at least one embodiment, a device configured to at least partially regenerate a particulate filter is provided. The device comprises a housing, a fuel injector configured to inject fuel, and a combustion chamber. The device is characterized in that a cross section of the combustion chamber converges from an inlet to an outlet.

In at least another embodiment, a system for treating particulates of an engine's exhaust is provided. The system comprises a filter configured to collect particulate matter and a device configured to at least partially regenerate a particulate filter. The device comprises a housing, a fuel injector configured to inject fuel, and a combustion chamber. The device is characterized in that a cross section of the combustion chamber converges from an inlet to an outlet.

In yet another embodiment, an aftertreatment system for an engine is provided. The system comprises a filter configured to collect particulates from the engine's exhaust and a burner configured to regenerate the filter. In this embodiment, the burner comprising a conical combustion chamber.

In even yet another embodiment, an internal combustion engine is provided. The engine comprises an exhaust system configured to receive engine exhaust, a filter configured to collect particulate matter within the exhaust, a burner configured to regenerate at least some of the particulate matter within the filter, and an engine control module configured to control when the burner regenerates the filter. The engine is characterized in that the burner comprises a conical combustion chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a portion of an embodiment of an internal combustion engine with exhaust system comprising an auxiliary regeneration device;

FIG. 2 is a cross sectional view of an auxiliary regeneration device comprising a cylindrical combustion chamber in accordance with one particular embodiment;

FIG. 3 is a cross sectional view of an auxiliary regeneration device comprising a partially conical combustion chamber in accordance with another particular embodiment; and

FIG. 4 is a cross sectional view of an auxiliary regeneration device comprising a fully conical combustion chamber in accordance with yet another embodiment.

DETAILED DESCRIPTION

Referring to FIG. 1, an engine 10 connected to an auxiliary regeneration device (“ARD”) 20 and particulate filter 30 is shown.

Regeneration of filter 30 is controlled, at least in part, by engine control module (“ECM”) 40. ECM 40 may sense engine speed 41, engine load 42, exhaust gas temperature 43, and possibly other engine 10 parameters not shown. In this particular embodiment, ECM 40 also measures filter 30 temperature with temperature sensor 46 and detects whether a flame exists in ARD 20 with flame detection sensor 48. ECM 40 may then use these measured parameters to generate signals for controlling regeneration, such as ARD 20 fuel control signal 44, ARD 20 combustion air control signal 45, and ignition control signal 47 to igniter 49. The reader should appreciate that igniter 49 may be any device known in the art that may be used to ignite a combustible fuel 53, such as a glow plug, plasma plug, multi-torch plug, or J-gap spark plug, for example.

ECM 40 generates ARD 20 fuel control signal 44, ARD 20 combustion air control signal 45, and ignition control signal 47 to control regeneration of filter 30. Signal 44 controls the quantity of fuel 53 injected into ARD 20 provided by fuel supply 50 with fuel supply valve 51. Signal 45 controls ARD 20 combustion air valve 52, which controls the amount of pressurized air 101 sent to ARD 20.

In this particular embodiment, ARD 20 receives pressurized air 101 in addition to exhaust gas 102. By providing pressurized air 101 directly to ARD 20, ARD 20 can regenerate filter 30 at most any engine 10 speed or load, including engine 10 idle. This particular design ensures that ARD 20 receives enough oxygen to ensure combustion at most all engine 10 loads.

Now referring to FIG. 2, an ARD 20 with a cylindrical combustion chamber 240 is depicted.

ARD 20 comprises a combustor housing 210, an inlet 211 where exhaust gas 102 enters, a fuel injector 230 for injecting fuel 53, an igniter 49 for igniting the injected fuel 53, a pressurized air inlet 271 for receiving pressurized air 101, a combustor chamber 240, and a flame stabilizer 250. As can be seen, combustion chamber 240 is cylindrical and situated within and substantially coaxially with combustor housing 210. The reader should appreciation, however, that combustion chamber 240 does not necessarily have to be positioned coaxially with combustor housing 210.

In this particular embodiment, a flame stabilizer 250 is provided. Flame stabilizer 250 is well known in the art of combustors and provides the function of stabilizing the flame before exiting combustion chamber 240. The reader should appreciate that any type of flame stabilizer 250 that is known in the art may be used and, in some cases, it may be desirable to not use any flame stabilizer 250.

Another function of flame stabilizer 250 is as the flame passes through flame stabilizer 250, the flow of gases accelerates and forms a high velocity flame jet in zone two 243. The high jet momentum improves the turbulent mixing between the flame jet and the oxygen in the exhaust gas, thus enabling zone two 243 combustion to proceed more rapidly and more completely.

In this particular embodiment, an air swirler 244 is also depicted. Air swirler 244 aids in mixing of combustion air 101 with fuel 53 before the mixture is ignited. The reader should appreciate that air swirler 244 is generally known to one skilled in the art and that various air swirlers 244 may be used to achieve mixing of air 101 with fuel 53. Furthermore, although FIGS. 2-4 depict an ARD 20 with flame swirler 244, the reader should also appreciate that ARD 20 may also work without air swirler 244.

During rich-burn combustion within chamber 240, only a fraction of combustion air from pressurized air 101 required for complete combustion is supplied to combustion chamber 240. Accordingly, in zone one 242, there is excess fuel 53 during rich-burn combustion. This rich-burn combustion in zone one 242 within primary combustion chamber 240 results in the oxidation of fuel 53 into carbon monoxide, H₂, and some other unburned hydrocarbon products. Combustion continues in zone two 243 when the incomplete combustion product from zone one 242 is discharged into combustor housing 210, where it is mixed with O₂ from exhaust gas 102. The efficiency—completeness—of the combustion in zone two 243 is significantly effected by how the flame jet from zone one 242 is mixed with exhaust gas 102 entering into combustion housing 210.

Due to the constrain of the ARD 20 packaging, as well as the mixing requirements of the flame jet and the exhaust gas 102 jet, primary combustion chamber 240 within combustor housing 210 is often positioned directly in the path of exhaust gas 102 and inlet 211. Locating combustor chamber 240 so that it intersects with inlet 211 and flow 102 generally increases the flow resistance of exhaust gas 102. This increased flow resistance results in increased backpressure on the exit of turbine 100, thus resulting in unacceptable performance penalties to engine 10. Some of these performance penalties include a fuel consumption penalty, deteriorated transient response, increased thermal loading, reduced altitude capability, and loss of rating capability.

The conical combustion chambers 340 and 440 described in FIGS. 3 and 4 reduce the flow resistance of exhaust gas 102 within ARD 20.

Referring now to FIG. 3, an ARD 20 comprising a partially conical combustion chamber 340 is depicted. As can be seen, combustion chamber 340 comprises two sections, first section 341 and second section 342. Second section 342 comprises a substantially cylindrical chamber with a constant diameter along its length. First section 341, on the other hand, comprises a chamber with a converging diameter, which gives second section 342 a conical shape. Together, sections 341 and 342 give combustion chamber 340 a partially conical construction, which minimizes exhaust 102 flow resistance.

Referring now to FIG. 4, an ARD 20 comprising a fully conical combustion chamber 440 is depicted. As can be seen, ARD 20 comprises a combustion chamber 440 with a shape that converges from its inlet to its outlet. In this embodiment, the diameter of chamber 440 converges along its entire length, thus giving chamber 440 a conical shape.

Although FIGS. 3 and 4 depict either a partially conical-shaped combustion chamber 340 or a fully conical-shaped combustion chamber 440, the reader should appreciate that any combustion chamber 240 with a decreasing cross-sectional area may alternatively be used to achieve substantially similar results. For example, the combustion chamber 240 does not necessarily require a circular shape, thus giving it a cylindrical or conical shape. Instead, for example, the combustion chamber may have a square, rectangular, triangular, etc., cross sectional shape.

The partially conical combustion chamber 340 and fully conical combustion chamber 440 are depicted as being attached with flame stabilizers 250. Although the depicted embodiments show the presence of flame stabilizers 250, the reader should also appreciate that ARD 20 may be used without stabilizers 250. Omitting flame stabilizers 250 from the design may reduce the cost of manufacture while providing for reduced exhaust gas 102 backpressure—for a combustion chamber 240, 340, and 440 of identical design, that is.

INDUSTRIAL APPLICABILITY

Referring again to FIG. 1, a brief description of the operation of engine 10 with ARD 20 will be made.

In operation, fresh air 60 enters compressor 70, where it is pressurized. From compressor 70, pressurized air 101 is then either sent to combustion air valve 52 or to intake manifold 80 of engine 10.

If sent to valve 52, pressurized air 101 will be utilized—in part—to aid in combustion of fuel 53 in ARD 20. If pressurized air 101 is sent to intake manifold 80, pressurized air 101 will aid in providing combustion air within internal combustion engine 10.

If the pressurized air was sent to intake manifold 80, once air 101 takes part in the combustion process of engine 10, exhaust gas 102 will enter exhaust manifold 90. Exhaust 102 will be pressurized as a result of the combustion process and will be used to drive turbine 100. In this embodiment, pressurized exhaust 102 drives turbine 100, which is connected to compressor 70 for providing the energy required to pressurize fresh air 60.

Once exhaust 102 exits turbine 100, exhaust 102 enters ARD 20, where, in combination with pressurized air 101, it is used to provide the oxygen necessary for aiding in the combustion of fuel 53 in ARD 20.

In this particular embodiment, ECM 40 receives engine speed signal 41, engine load signal 42, and exhaust gas temperature signal 43 from engine 10. ECM 40 also determines whether a flame exists in ARD 20 via flame detection sensor 48 and the temperature of filter 30 via temperature sensor 48. ECM 40 uses these parameters to generate control signal 44 for fuel supply valve 51, control signal 45 to combustion air valve 52, and control signal 47 for igniter 49. Once ARD 20 generates combustion of fuel 53, the heated regeneration air 290 is expelled towards filter 30. The heated regeneration air 290 then facilitates burning of the soot and unburned carbon particles in filter 30, thereby regenerating filter 30. By controlling the amount of combustion air 101 and fuel 53 that is sent to ARD 20, as well as ignition of igniter 49, ECM 40 can precisely control regeneration of filter 30.

It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the disclosed regeneration assembly without departing from the scope of the invention. Other embodiments of the invention will be apparent to those having ordinary skill in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the invention being indicated by the following claims and their equivalents.

Claims

1. A device for regenerating a particulate filter, comprising:

a housing;

a fuel injector configured to inject fuel;

an igniter configured to ignite the injected fuel;

a combustion chamber; and

an intake air line configured to provide combustion air from an intake system of an engine,

characterized in that a cross section of the combustion chamber converges from an inlet to an outlet.

2. The device of claim 1, further characterized in that the combustion chamber comprises a first section of decreasing diameter.

3. The device of claim 2, further characterized in that the combustion chamber comprises a second section of substantially constant diameter.

4. The device of claim 1, further comprising a flame stabilizer connected to an end of the combustion chamber.

5. The device of claim 1, further characterized in that the combustor housing is coaxial with the combustion chamber.

6. The device of claim 1, further comprising a combustion air inlet configured to provide combustion air to the combustion chamber.

7. The device of claim 1, further comprising a flame detector configured to detect a flame within the combustor housing.

8. A system for treating particulates of an engine's exhaust, comprising:

a filter configured to collect particulate matter; and

the device of claim 1.

9. The system of claim 8, further characterized in that the device receives exhaust gas downstream of a turbine exhaust.

10. The system of claim 8, further characterized in that the intake air line receives combustion air downstream of a compressor discharge.

11. The system of claim 8, further characterized in that the device uses the same fuel as the engine.

12. An aftertreatment system for an engine, comprising:

a filter configured to collect particulates from the engine's exhaust; and

a burner configured to regenerate the filter, said burner receives combustion air from an intake system of the engine,

characterized in that the burner comprises a conical combustion chamber.

13. The aftertreatment system of claim 12, further comprising a fuel supply valve configured to control injection of fuel into the burner.

14. The aftertreatment system of claim 12, further comprising a combustion air control valve configured to regulate an amount of combustion air sent to the burner.

15. The aftertreatment system of claim 12, characterized in that the burner further comprises a flame detector configured to detect the presence of a flame in the combustor chamber.

16. The aftertreatment system of claim 12, characterized in that the burner further comprises a flame stabilizer.

17. An internal combustion engine, comprising:

an exhaust system configured to receive engine exhaust;

a filter configured to collect particulate matter within the exhaust;

a burner configured to regenerate at least some of the particulate matter within the filter, characterized in that the burner comprises a conical combustion chamber;

an intake air line configured to carry combustion air from an intake system of the engine to the burner; and

an engine control module configured to control when the burner regenerates the filter.

18. The engine of claim 17, further comprising a turbocharger configured to compress engine intake air, wherein at least some compressed intake air is provided to the burner.

19. The engine of claim 17, further characterized in that the filter comprises a temperature sensor.

20. The engine of claim 17, further characterized in that the engine control module controls a timing of injection of fuel into the burner.

21. The engine of claim 17, further comprising a combustion air valve configured to regulate a flow of combustion air to the burner.

22. The engine of claim 17, further characterized in that the combustion chamber comprises a flame stabilizer.