Information
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Patent Grant
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6267106
-
Patent Number
6,267,106
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Date Filed
Tuesday, November 9, 199924 years ago
-
Date Issued
Tuesday, July 31, 200123 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
-
International Classifications
-
Abstract
An internal combustion engine includes a combustion air supply; an exhaust manifold; and an induction venturi. The induction venturi includes a combustion air inlet connected and in communication with the combustion air supply, an exhaust gas inlet connected and in communication with the exhaust manifold, and an outlet. A venturi section terminates at a venturi throat and is in communication with the combustion air inlet. An expansion section is positioned between and in communication with the venturi section and the outlet. At least one induction port terminates adjacent the venturi throat and within the expansion section.
Description
TECHNICAL FIELD
The present invention relates to exhaust gas recirculation systems in an internal combustion engine, and, more particularly, to induction venturi in exhaust gas recirculation systems.
BACKGROUND ART
An exhaust gas recirculation (EGR) system is used for controlling the generation of undesirable pollutant gases and particulate matter in the operation of internal combustion engines. Such systems have proven particularly useful in internal combustion engines used in motor vehicles such as passenger cars, light duty trucks, and other on-road motor equipment. EGR systems primarily recirculate the exhaust gas by-products into the intake air supply of the internal combustion engine. The exhaust gas which is reintroduced to the engine cylinder reduces the concentration of oxygen therein, which in turn lowers the maximum combustion temperature within the cylinder and slows the chemical reaction of the combustion process, decreasing the formation of nitrous oxides (NoX). Furthermore, the exhaust gases typically contain unburned hydrocarbons which are burned on reintroduction into the engine cylinder, which further reduces the emission of exhaust gas by-products which would be emitted as undesirable pollutants from the internal combustion engine.
When utilizing EGR in a turbocharged diesel engine, the exhaust gas to be recirculated is preferably removed upstream of the exhaust gas driven turbine associated with the turbocharger. In many EGR applications, the exhaust gas is diverted directly from the exhaust manifold. Likewise, the recirculated exhaust gas is preferably reintroduced to the intake air stream downstream of the compressor and air-to-air after cooler (ATAAC). Reintroducing the exhaust gas downstream of the compressor and ATAAC is preferred due to the reliability and maintainability concerns that arise if the exhaust gas passes through the compressor and ATAAC. An example of such an EGR system is disclosed in U.S. Pat. No. 5,802,846 (Bailey), which is assigned to the assignee of the present invention.
With conventional EGR systems as described above, the charged and cooled combustion air which is transported from the ATAAC is at a relatively high pressure as a result of the charging from the turbocharger. Since the exhaust gas is also typically inducted into the combustion air flow downstream of the ATAAC, conventional EGR systems are configured to allow the lower pressure exhaust gas to mix with the higher pressure combustion air. Such EGR systems may include a venturi section which induces the flow of exhaust gas into the flow of combustion air passing therethrough. An efficient venturi section is designed to “pump” exhaust gas from a lower pressure exhaust manifold to a higher pressure intake manifold. However, because varying EGR rates are required throughout the engine speed and load range, a variable orifice venturi may be preferred. Such a variable orifice venturi is physically difficult and complex to design and manufacture. Accordingly, venturi systems including a fixed orifice venturi and a combustion air bypass circuit are conventionally favored. The bypass circuit consists of piping and a butterfly valve in a combustion air flow path which is parallel with the venturi flow path. The butterfly valve is controllably actuated using an electronic controller which senses various parameters associated with operation of the engine.
With a venturi section as described above, the maximum flow velocity and minimum pressure of the combustion air flowing through the venturi section occurs within the venturi throat disposed upstream from the expansion section. The butterfly valve is used to control the flow of combustion air to the venturi throat, which in turn affects the flow velocity and vacuum pressure created therein. By varying the vacuum pressure, the amount of exhaust gas which is induced into the venturi throat of the venturi section can be varied. However, inducing the exhaust gas into the flow of combustion air in the venturi throat may affect the diffusion and pressure recovery of the mixture within the expansion section of the venturi.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the invention, an internal combustion engine comprises a combustion air supply; an exhaust manifold; and an induction venturi. The induction venturi includes a combustion air inlet connected and in communication with the combustion air supply, an exhaust gas inlet connected and in communication with the exhaust manifold, and an outlet. A venturi section terminates at a venturi throat and is in communication with the combustion air inlet. An expansion section is positioned between and in communication with the venturi section and the outlet. At least one induction port terminates adjacent the venturi throat and within the expansion section.
In another aspect of the invention, an induction venturi induces an exhaust gas into a flow of combustion air in an exhaust gas recirculation system of an internal combustion engine. The internal combustion engine includes a combustion air supply and an exhaust manifold. The induction venturi comprises a housing having a combustion air inlet for receiving combustion air from the combustion air supply, an exhaust gas inlet for receiving exhaust gas from the exhaust manifold, an outlet, and an inner chamber in communication with each of the combustion air inlet, the exhaust gas inlet and the outlet. A venturi section terminates at a venturi throat and is in communication with the combustion air inlet. The venturi section is positioned within the inner chamber of the housing. An expansion section is positioned between and in communication with the venturi section and the outlet. At least one induction port is defined by the housing and/or venturi section. At least one induction port terminates adjacent the venturi throat and within the expansion section.
In yet another aspect of the invention, a method of operating an internal combustion engine having an exhaust gas recirculation system comprises the steps of: providing a combustion air supply; providing an exhaust manifold; providing an induction venturi including a combustion air inlet connected and in communication with the combustion air supply, an exhaust gas inlet connected and in communication with the exhaust manifold, an outlet, a venturi section terminating at a venturi throat and in communication with the combustion air inlet, an expansion section positioned between and in communication with the venturi section and the outlet, and at least one induction port terminating adjacent the venturi throat and within the expansion section; transporting combustion air from the combustion air supply, through the combustion air inlet and through the venturi section; and transporting exhaust gas from the exhaust gas manifold, through at least one induction port and into the expansion chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a schematic, sectional view illustrating an embodiment of an induction venturi of the present invention for use in an exhaust gas recirculation system of an internal combustion engine;
FIG. 2
is a side, sectional view of an embodiment of an induction venturi of the present invention; and
FIG. 3
is an end, sectional view taken along line
3
—
3
in FIG.
2
.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the drawings, and more particularly to
FIG. 1
, there is shown a schematic representation of an induction venturi
10
of the present invention which may be utilized with an EGR system in an internal combustion engine. Induction venturi
10
includes a housing
12
defining a venturi section
14
, expansion section
16
and inner chamber
18
. Venturi section
14
receives combustion air from a combustion air supply such as a turbocharger and aftercooler associated with the internal combustion engine. Venturi section
14
has a generally nozzle shape and terminates at a venturi throat
20
at which point the combustion air travels at maximum velocity and minimum pressure adjacent exit end
22
. Expansion section
16
is disposed immediately adjacent to and downstream from venturi section
14
, relative to the direction of flow through venturi section
14
. Inner chamber
18
receives exhaust gas from an exhaust manifold of the internal combustion engine. Inner chamber
18
is positioned generally radially outward from and annularly around venturi throat
20
and exit end
22
. The exhaust gas flows in the annular space defined by inner chamber
18
and flows through an annular-shaped induction port defined between expansion section
16
and exit end
22
. The exhaust gas thus mixes with the combustion air adjacent to exit end
22
and within expansion section
16
.
Conventionally, an induction venturi includes a venturi section through which the combustion air flows at maximum velocity and minimum pressure. Since the minimum pressure of the combustion air occurs within the venturi throat of the venturi section, conventional wisdom is for the induction port which induces exhaust gas into the flow of combustion air to also terminate within the venturi throat so that the exhaust gas can be effectively drawn into the flow of combustion air as a result of the vacuum pressure created therein. However, the inventor of the present invention has surprisingly found that an induction port which terminates immediately downstream and adjacent to exit end
22
of venturi section
14
and within expansion section
16
still results in adequate exhaust gas being drawn into the flow of combustion air flowing through induction venturi
10
. Additionally, diffusion of the exhaust gas into the combustion air has been found to be improved, and pressure recovery within expansion section
16
has also been found to be improved.
FIGS. 2 and 3
illustrate an embodiment of an induction venturi
30
of the present invention. Induction venturi
30
includes a two part housing
32
A,
32
B. Housing part
32
A defines inner chamber
34
which is connected with an exhaust gas inlet
36
, which in turn receives exhaust gas from an exhaust manifold
38
of an internal combustion engine. Housing part
32
A also includes a combustion air inlet
40
which receives combustion air from a combustion air supply such as a turbocharger (not shown) and an aftercooler
42
.
Housing part
32
B is connected with housing part
32
A and includes an outlet
44
which is fluidly connected with an intake manifold
46
of the internal combustion engine. Housing part
32
B is disposed downstream from housing part
32
A, relative to a direction of flow through induction venturi
30
from combustion air inlet
40
to outlet
44
, indicated by arrows
48
and
50
.
Venturi section
52
is a generally cone-shaped piece which is positioned within inner chamber
34
and carried by housing part
32
A. Venturi section
52
has a venturi nozzle
54
which terminates at a venturi throat
56
. The combustion air flowing through venturi nozzle
54
from aftercooler
42
is at a maximum velocity and minimum pressure when flowing through venturi throat
56
adjacent exit end
58
. Venturi section
52
has an outer surface
60
which extends from exit end
58
and is disposed at an acute angle of approximately
30
° relative to longitudinal axis
60
of venturi section
52
.
Housing part
32
B is attached with and carries a liner
62
. Liner
62
defines an expansion section
64
disposed downstream from venturi section
52
. Combustion air which flows through exit end
58
into expansion section
64
diffuses or expands therein and thus increases in pressure within expansion section
64
. Expansion section
64
within liner
62
has a generally circular cross-sectional shape when viewed from the right side of FIG.
2
. Additionally, venturi throat
56
and exit end
58
also have a generally circular cross-sectional shape, as shown in FIG.
3
. Thus, an induction port
66
is defined in the annular space between exit end
58
and liner
62
. Induction port
66
and inner chamber
34
have a substantially annular shape when viewed in cross-section as shown in FIG.
3
. The particular shape of inner chamber
34
can vary dependent upon the specific application of induction venturi
30
.
To assemble induction venturi
30
, venturi section
52
is installed within housing part
32
A and liner
62
is installed within housing part
32
B. Housing parts
32
A and
32
B are then attached together as shown. By providing a venturi section
52
and liner
62
that are removably installed within housing parts
32
A and
32
B, respectively, it is possible to change the configuration of induction venturi
30
, depending upon the specific engine operating characteristics with which induction venturi
30
is utilized. For example, the configuration of venturi nozzle
54
and venturi throat
56
within venturi section
52
may be changed, or the approach angle of outer surface
60
may be changed. Moreover, the diameter, curvature, expansion rate, etc. within expansion section
64
may be changed by using a differently configured liner
62
. It naturally follows that in high volume production of a given configuration, the inner venturi nozzle
54
will be cast integral with the housing
32
A and the expansion section
64
will be cast integral with the housing
32
B.
INDUSTRIAL APPLICABILITY
During use, cooled and compressed combustion air flows into induction venturi
30
at combustion air inlet
40
. Additionally, exhaust gas flows from exhaust manifold
38
to exhaust gas inlet
36
and into inner chamber
34
surrounding venturi section
52
. The combustion air flows through venturi section
52
and is at a maximum velocity and minimum pressure adjacent exit end
58
of venturi throat
56
. The exhaust gas flowing within inner chamber
34
is at a higher pressure than the combustion air exiting from exit end
58
and thus is drawn through the annular shaped induction port
66
surrounding exit end
58
. The exhaust gas impinges with the combustion air at an angle of approximately 30°. The combustion air and exhaust gas mix, diffuse and expand within expansion section
64
and flow from the expanding outlet
44
to intake manifold
46
.
Induction venturi
30
of the present invention provides effective induction of the exhaust gas into the flow of combustion air, while at the same time improving diffusion and pressure recovery within expansion section
64
and
44
. By configuring venturi section
52
and expansion section
64
as parts which are separate from housing
32
A,
32
B and removably installed within housing
32
A,
32
B, the geometric configuration of induction venturi
30
and flow characteristics of combustion air and exhaust gas flowing therethrough may be changed dependent upon the specific operating characteristics of the internal combustion engine.
Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.
Claims
- 1. An internal combustion engine, comprising:a combustion air supply; an exhaust manifold; and an induction venturi including a combustion air inlet connected and in communication with said combustion air supply, an exhaust gas inlet connected and in communication with said exhaust manifold, an outlet, a venturi section terminating at a venturi throat exit end and in communication with said combustion air inlet, an expansion section positioned between and in communication with said venturi section exit end and said outlet, and at least one induction port terminating separate from and adjacent said venturi throat exit end within said expansion section.
- 2. The internal combustion engine of claim 1, further comprising a housing with an inner chamber, said venturi section positioned within said inner chamber.
- 3. The internal combustion engine of claim 2, wherein said venturi section has a generally cone shape, said inner chamber surrounding said venturi section and being in communication with said expansion section.
- 4. The internal combustion engine of claim 3, wherein said venturi section terminates at an exit end adjacent said venturi throat, each of said exit end and said expansion section having a generally circular cross section, said at least one induction port comprising an annular space between said exit end and said expansion section.
- 5. The internal combustion engine of claim 4, wherein said at least one induction port comprises an annular space which is positioned radially around said exit end.
- 6. The internal combustion engine of claim 4, wherein said venturi section has an outer surface extending from said exit end which is disposed at an angle of approximately 30° relative to a longitudinal axis of said venturi section.
- 7. The internal combustion engine of claim 4, further comprising a liner disposed within said housing and defining said expansion section.
- 8. The internal combustion engine of claim 2, wherein said venturi section is separate from and carried by said housing.
- 9. The internal combustion engine of claim 1, wherein said combustion air supply includes an air-to-air aftercooler.
- 10. An induction venturi for inducing exhaust gas into a flow of combustion air in an exhaust gas recirculation system of an internal combustion engine, the internal combustion engine including a combustion air supply and an exhaust manifold, said induction venturi comprising:a housing having a combustion air inlet for receiving combustion air from the combustion air supply, an exhaust gas inlet for receiving exhaust gas from the exhaust manifold, an outlet, and an inner chamber in communication with each of said combustion air inlet, said exhaust gas inlet and said outlet; a venturi section terminating at a venturi throat exit end and in communication with said combustion air inlet, said venturi section positioned within said inner chamber; an expansion section positioned between and in communication with said venturi section exit end and said outlet; and at least one induction port defined by at least one of said housing and said venturi section, said at least one induction port terminating separate from and adjacent said venturi throat exit end within said expansion section radially outwardly of said venturi throat.
- 11. The induction venturi of claim 10, wherein said at least one induction port comprises a single induction port which is defined by each of said housing and said venturi throat.
- 12. The induction venturi of claim 10, wherein said venturi section has a generally cone shape, said inner chamber surrounding said venturi section and being in communication with said expansion section.
- 13. The induction venturi of claim 12, wherein said venturi section terminates at an exit end adjacent said venturi throat, each of said exit end and said expansion section having a generally circular cross section, said at least one induction port comprising an annular space between said exit end and said expansion section.
- 14. The induction venturi of claim 13, wherein said at least one induction port comprises an annular space which is positioned radially around said exit end.
- 15. The induction venturi of claim 13, wherein said venturi section has an outer surface extending from said exit end which is disposed at an angle of approximately 30° relative to a longitudinal axis of said venturi section.
- 16. The induction venturi of claim 13, further comprising a liner disposed within said housing and defining said expansion section.
- 17. The induction venturi of claim 12, wherein said venturi section is separate from and carried by said housing.
- 18. The induction venturi of claim 10, wherein said combustion air supply includes an air-to-air aftercooler.
- 19. A method of operating an internal combustion engine having an exhaust gas recirculation system, comprising the steps of:providing a combustion air supply; providing an exhaust manifold; providing an induction venturi including a combustion air inlet connected and in communication with said combustion air supply, an exhaust gas inlet connected and in communication with said exhaust manifold, an outlet, a venturi section terminating at a venturi throat and in communication with said combustion air inlet, an expansion section positioned between and in communication with said venturi section and said outlet, and at least one induction port terminating adjacent said venturi throat and within said expansion section; transporting combustion air from said combustion air supply, through said combustion air inlet and through said venturi section into said expansion section; and transporting exhaust gas from said exhaust gas manifold, through said at least one induction port and into said expansion section separately from the combustion air.
- 20. The method of claim 19, wherein said induction venturi includes a housing with an inner chamber, and said venturi section is positioned within said housing and has a generally cone shape, said inner chamber surrounding said venturi section and being in communication with said expansion section.
- 21. The method of claim 20, wherein said venturi section terminates at an exit end adjacent said venturi throat, each of said exit end and said expansion section having a generally circular cross section, said at least one induction port comprising an annular space between said exit end and said expansion section.
- 22. The method of claim 21, wherein said at least one induction port comprises an annular space which is positioned radially around said exit end.
- 23. The induction venturi of claim 21, wherein said venturi section has an outer surface extending from said exit end which is disposed at an angle of approximately 30° relative to a longitudinal axis of said venturi section.
US Referenced Citations (9)
Foreign Referenced Citations (4)
Number |
Date |
Country |
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Aug 1998 |
EP |
713331 |
Aug 1954 |
GB |
2 284 016 |
May 1995 |
GB |
8326609 |
Dec 1996 |
JP |