Information
-
Patent Grant
-
6343594
-
Patent Number
6,343,594
-
Date Filed
Thursday, June 1, 200024 years ago
-
Date Issued
Tuesday, February 5, 200222 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 56811
- 123 56812
- 123 56817
- 123 56818
- 123 56819
- 123 5682
- 123 56826
- 123 56827
- 123 56829
- 060 6052
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International Classifications
-
Abstract
A variable flow venturi assembly for use in an exhaust gas recirculation system of an internal combustion engine having a housing with an inner chamber, a combustion air inlet in communication with the inner chamber, and an exhaust gas inlet in communication with the inner chamber. A venturi valve is slidably disposed within the chamber. A venturi valve has a longitudinally extending throughhole with an inlet opening in communication with the combustion air inlet, an outlet opening and a venturi section interposed and in communication with each of the inlet opening and the outlet opening. The venturi valve further has at least one bypass port and at least one induction port. Each bypass port is in communication with a combustion air inlet and a throughhole. Each induction port is in communication with the exhaust gas inlet and the throughhole. An actuator slidably moves the venturi valve within the inner chamber of the housing.
Description
TECHNICAL FIELD
The present invention relates to internal combustion engines, and, more particularly, to a variable flow venturi assembly for use in an exhaust gas recirculation system of an internal combustion engine.
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 Apump@ 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 the EGR flow path. The butterfly valve is controllably actuated using an electronic controller which senses various parameters associated with operation of the engine. The controllable actuator associated with the butterfly valve for controlling the EGR flow rate typically is connected with the butterfly valve through appropriate mechanical linkages, etc. Although such systems may provide effective EGR, they may be relatively complicated, difficult and expensive to manufacture, and may require replacement more often.
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, a variable flow venturi assembly for use in an exhaust gas recirculation system of an internal combustion engine having a housing with an inner chamber, a combustion air inlet in communication with the inner chamber, and an exhaust gas inlet in communication with the inner chamber. A venturi valve is slidably disposed within the chamber. A venturi valve has a longitudinally extending throughhole with an inlet opening in communication with the combustion air inlet, an outlet opening and a venturi section interposed and in communication with each of the inlet opening and the outlet opening. The venturi valve further has at least one bypass port and at least one induction port. Each bypass port is in communication with a combustion air inlet and a throughhole. Each induction port is in communication with the exhaust gas inlet and the throughhole. An actuator slidably moves the venturi valve within the inner chamber of the housing.
In another aspect of the invention, an internal combustion engine having an intake manifold and a variable flow venturi assembly. The variable flow venturi assembly has a housing, a venturi valve and an actuator. The housing is attached to the intake manifold, and has an inner chamber, a combustion air inlet in communication with the inner chamber, and an exhaust gas inlet in communication with the inner chamber. The venturi valve is slidably disposed within the inner chamber. The venturi valve has a longitudinally extending throughhole with an inlet opening in communication with the combustion air inlet, an outlet opening and a venturi section interposed and in communication with each of the inlet opening an the outlet opening. The venturi valve further has at least one bypass port and at least one induction port. Each bypass port is in communication with the combustion air inlet and the throughhole. Each induction port is in communication with the exhaust gas inlet and the throughhole. An actuator slidably moves the venturi valve within the chamber of the housing.
In yet another aspect of the invention, a method of operating a variable flow venturi assembly in an exhaust gas recirculation system of an internal combustion engine has the steps of: providing a housing having an inner chamber, a combustion air inlet in communication with the inner chamber, and an exhaust gas inlet in communication with the inner chamber; providing a venturi valve slidably disposed within the inner chamber, the venturi valve has a longitudinally extending throughhole with an inlet opening in communication with the combustion air inlet, an outlet opening and a venturi section interposed and in communication with each of the inlet opening and the outlet opening, the venturi valve further has at least one bypass port and at least one induction port, each bypass port in communication with the combustion air inlet and the throughhole, each induction port in communication with the exhaust gas inlet and the throughhole; moving the venturi valve in a slidable manner within the inner chamber of the housing using an actuator; and covering each bypass port a selected amount dependent upon the moving step.
BRIEF DESCRIPTION OF THE DRAWINGS
The FIGURE is a side, sectional view of an embodiment of a variable flow venturi assembly of the present invention for use in an exhaust gas recirculation system of an internal combustion engine.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the drawing, there is shown an embodiment of a variable flow venturi assembly
10
of the present invention which is attached to an intake manifold
12
of an internal combustion engine. Variable flow venturi assembly
10
forms part of an EGR system which is used to recirculate the exhaust gas from an exhaust manifold (not shown) of the internal combustion engine to intake manifold
12
. Intake manifold
12
is connected in known manner to a plurality of combustion cylinders, with each combustion cylinder having a corresponding piston which is movable in a reciprocal manner therein. The relative motion between the different pistons may be dependent upon each other in the case of a crank shaft engine, or may be independent of each other in the case of a free piston engine.
Variable flow venturi assembly
10
generally has a housing
14
, a venturi valve
16
and an actuator
18
. Housing
14
has an inner chamber
20
extending in a longitudinal manner from a combustion air inlet
22
to a mounting flange
24
. Inner chamber
20
includes multiple adjacent surfaces, with a larger diameter portion
26
, a smaller diameter portion
28
, a first annular recess
30
and a second annular recess
32
. Combustion air inlet
22
receives combustion air which is used within the combustion cylinders attached to intake manifold
22
. More particularly, in the embodiment shown, combustion air inlet
22
receives compressed and cooled combustion air from an after cooler which is attached to a compressor of a turbocharger. Such a turbocharger and after cooler are well known in the art, and will not be described in further detail hereinafter.
Mounting flange
24
allows housing
14
of variable flow venturi assembly
10
to be connected with intake manifold
12
in a suitable manner. In the embodiment shown, mounting flange
24
has a plurality of holes
34
which receive corresponding fasteners such as a stud
36
for attaching housing
14
to intake manifold
12
. Of course, variable flow venturi assembly
10
may be connected to intake manifold
12
in any suitable manner.
Housing
14
also has an exhaust gas inlet
38
which is in communication with inner chamber
20
and which receives exhaust gas from an exhaust manifold (not shown) of the internal combustion engine. Exhaust gas inlet
38
is appropriately configured to allow interconnection with the exhaust manifold of the internal combustion engine. In the embodiment shown, exhaust gas inlet
38
has an annular flange
40
allowing housing
14
to be bolted together in a suitable manner with other appropriate pipes, conduits, etc. using bolts or studs which pass through bolt holes
42
. Exhaust gas inlet
38
is in communication with first annular recess
30
forming a part of inner chamber
20
.
Venturi valve
16
is slidably disposed within inner chamber
20
. Venturi valve
16
has a longitudinally extending throughhole
44
with an inlet opening
46
in communication with combustion air inlet
22
, an outlet opening
48
in communication with intake manifold
12
, and a venturi section
50
interposed and in communication with each of inlet opening
46
and outlet opening
48
. Venturi section
50
tapers in a constricting manner from inlet opening
46
to constrict the flow of combustion air therethrough, and thereby cause the velocity of the combustion air to increase and the pressure of the combustion air to decrease. Venturi section
50
terminates at a venturi throat
52
, relative to a direction of flow indicated by arrow
54
. Throughhole
44
also has an expansion section
56
which is disposed downstream from venturi section
50
, between venturi section
50
and outlet opening
48
. Expansion section
56
allows the combustion air which flows through venturi section
50
to expand on the downstream side of venturi throat
52
.
Venturi valve
16
also has an annular flange
58
with a diameter which is larger than smaller diameter portion
28
of inner chamber
20
. Annular flange
58
has an annular shoulder
60
which faces in an axial direction relative to a longitudinal axis
62
of venturi valve
16
. Annular flange
58
also has a circumferential groove
64
which carries an
0
-ring
66
or any other type of seal for sealing between annular flange
58
and housing
14
.
Venturi valve
16
is movable within housing
14
a distance corresponding to the stroke length of annular flange
58
within second annular recess
32
. More particularly, venturi valve
16
is movable between extreme positions a distance corresponding to the stroke length S
1
between annular flange
58
and a cover
68
carried within second annular recess
32
adjacent mounting flange
24
. A compression spring
70
which abuts cover
68
and an annular shoulder
72
disposed on a side of annular flange
58
opposite from annular shoulder
60
biases venturi valve
16
to the position shown in the figure.
Actuator
18
is in the form of a pneumatic actuator which applies pressure in the form of air pressure to annular shoulder
60
of annular flange
58
to move venturi valve
16
to a selected position within housing
14
. More particularly, actuator
18
has a threaded port
74
which is connected to one or more branch channels
76
leading to annular shoulder
60
. A small annular recess (not numbered) adjacent annular shoulder
60
allows the fluid pressure transported through branch channel
76
to be evenly applied to annular shoulder
60
. Threaded port
74
is internally threaded and allows actuator
18
to be easily connected with a source of pressurized air
78
through appropriate fluid conduits, hoses, etc., schematically represented by lines
80
and
82
in the figure. A controllable valve
84
is interposed between lines
80
and
82
and allows the pressure and duration of the air which is supplied to threaded port
74
to be controlled using a controller
86
connected therewith. Controller
86
may receive appropriate input signals from various sensors associated with the internal combustion engine to controllably actuate valve
84
. For example, controller
86
may actuate valve
84
dependent upon load characteristics, engine temperature, etc.
Venturi valve
16
also has a plurality of bypass ports
88
extending therethrough. Each bypass port
88
has an inlet
90
associated with larger diameter portion
26
of inner chamber
20
, and an outlet end
92
disposed in communication with and terminating within expansion section
56
of throughhole
44
. Each inlet end
90
terminates at a radially outward periphery of venturi valve
16
, and thus has a substantially oblong shape as illustrated. Likewise, outlet end
92
of each bypass port
88
contacts expansion section
56
of throughhole
44
at an oblique angle and thus also has oblong shape as illustrated.
Bypass ports
88
allow a predetermined amount of combustion air to bypass venturi section
50
, dependent upon the longitudinal displacement position of venturi valve
16
within housing
14
. More particularly, each inlet end
90
has a length L in the longitudinal direction which is approximately the same as the stroke length S
1
of venturi valve
16
within housing
14
. Venturi valve
16
may be slidably displaced within housing
14
using actuator
18
to a desired longitudinal position, as described above. Dependent upon the selected longitudinal position of venturi valve
16
within housing
14
, a corresponding amount of each inlet end
90
is covered by smaller diameter portion
28
of inner chamber
20
. When venturi valve
16
is in the position shown in the drawing, each inlet end
90
is fully open so that a maximum amount of combustion air can bypass venturi section
50
. Conversely, when pneumatic pressure is exerted by actuator
18
to move venturi valve
16
to the right the maximum distance S
1
shown in the drawing, each inlet end
90
is substantially entirely covered by smaller diameter portion
28
of inner chamber
20
. By varying the amount of combustion air which flows through bypass ports
88
, the amount of combustion air which flows through venturi throat
52
is likewise variably controlled.
Venturi valve
16
also has a plurality of induction ports
94
. Each induction port
94
has an inlet (not numbered) disposed in communication with exhaust gas inlet
38
and an opposite end (not numbered) which extends to and terminates at throughhole
44
of venturi valve
16
. Each induction port
94
transports exhaust gas from first annular recess
30
into throughhole
44
of venturi valve
16
for mixing with the combustion air transported through venturi throat
52
. Each induction port
94
may have an end which is sized, shaped and configured to provide proper fluid exhaust gas into throughhole
44
, and which promotes pressure recovery through diffusion within throughhole
44
.
In the embodiment shown, each induction port
94
is always substantially open, regardless of the position of venturi valve
16
within housing
14
. That is, each induction port
94
may be moved to the right a maximum distance corresponding to stroke length S
1
, dependent upon the position of venturi valve
16
within housing
14
. It is thus appreciated that induction ports
94
are always open, regardless of the position of venturi valve
16
within housing
14
. It is also possible to position induction ports
94
such that the inlet ends are substantially covered by smaller diameter portion
28
of inner chamber
20
. For example, the inlet end of each induction port
94
may be positioned at or near location
96
of smaller diameter portion
28
. Conversely, it is also possible to position the inlet end of each induction port
94
such that it is open when each bypass port
88
is in the full bypass position as shown, and substantially closed when venturi valve
16
is moved to the rightmost position corresponding to stroke length S
1
. For example, the inlet end to each induction port
94
may be positioned at or near location
98
when venturi valve
16
is in the full bypass position shown in the figure. The exact configuration of induction ports
94
and the exact positioning of the inlet ends and outlet ends of each induction port
94
may vary dependent upon the specific application.
Industrial Applicability
During use, combustion occurs within the combustion cylinders of the internal combustion engine associated with intake manifold
12
in known manner. The exhaust gas from the combustion cylinder drives a turbine side of a turbocharger, which in turn drives a compressor side of a turbocharger providing compressed combustion air to intake manifold
12
. The compressed combustion air is cooled with an after cooler (not shown) and is then transported to combustion air inlet
2
of variable flow venturi assembly
10
. Additionally, a portion of the exhaust gas from the exhaust manifold of the internal combustion engine is directed through appropriate fluid conduits, etc. to exhaust gas inlet
38
of variable flow venturi assembly
10
. Dependent upon load, temperature or other parameters associated with operation of the internal combustion engine, controller
86
controls a flow of pressurized air from air source
78
to actuator
18
. The amount and/or pressure of the air which is supplied to actuator
18
is controlled with controller
86
using valve
84
. The pressurized air exerts an axial force against shoulder
60
which moves venturi valve
16
to a selected position within housing
14
. Compression spring
70
opposes the force applied by the air pressure against shoulder
60
such that venturi valve
16
is held at a selected location in a stationary manner within housing
14
. The selected location of venturi valve
16
in turn covers each inlet end
90
of bypass ports
88
a predetermined amount. The amount of area of each inlet end
90
which is uncovered determines the amount of combustion air which bypasses venturi section
50
through bypass ports
88
. By controlling the amount of air which bypasses through bypass ports
88
, the amount of combustion air which flows through venturi section
50
is likewise controlled. The magnitude of the vacuum pressure within venturi throat
52
and adjacent the outlet of each induction port
94
is a function of the amount of air which flows through venturi throat
52
. This vacuum pressure determines the amount of exhaust gas which is induced through induction ports
94
to mix with the combustion air which flows through venturi throat
52
. Thus, by controlling the amount of air which bypasses through bypass ports
88
, the amount of exhaust gas which mixes with the combustion air is likewise controlled. Combustion air with a predetermined amount of exhaust gas mixed therewith flows from outlet opening
48
of venturi valve
16
and into intake manifold
12
for use within the combustion cylinders of the internal combustion engine.
The present invention provides a variable flow venturi assembly
10
which is used to control and allows easy adjustment of the exhaust gas which is mixed with the combustion air. The venturi valve may be displaced to a selected location using a pneumatic actuator, thereby covering the bypass ports a predetermined amount and controlling the flow of combustion air to the venturi section to in turn control the amount of exhaust gas which is mixed therewith. The induction ports for inducing the exhaust gas into the flow of combustion air have inlets which may be selectively placed such that the inlets are always opened or sometimes open, dependent upon the position of venturi valve
16
within housing
14
. The length of the inlet end of each bypass port
88
is preferably selected to correspond to the stroke length S
1
of venturi valve
16
within housing
14
, thereby moving bypass ports
88
from a full bypass position to a full closed position, dependent upon the position of venturi valve
16
within housing
14
. The amount of force which is required to move venturi valve
16
may be varied by changing the effective area of annular shoulder
60
, relative to the spring constant of compression spring
70
.
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. A variable flow venturi assembly for use in an exhaust gas recirculation system of an internal combustion engine, comprising:a housing having an inner chamber, a combustion air inlet in communication with said inner chamber, and an exhaust gas inlet in communication with said inner chamber; a venturi valve slidably disposed within said inner chamber, said venturi valve including a longitudinally extending throughhole with an inlet opening in communication with said combustion air inlet, an outlet opening and a venturi section interposed between and in communication with each of said inlet opening and said outlet opening, said venturi valve further including at least one bypass port and at least one induction port, each said bypass port in communication with said combustion air inlet and said throughhole, each said induction port in communication with said exhaust gas inlet and said throughhole; and an actuator for slidably moving said venturi valve within said inner chamber of said housing.
- 2. The variable flow venturi assembly of claim 1, wherein said actuator includes a pneumatic actuator.
- 3. The variable flow venturi assembly of claim 2, wherein said venturi valve includes an annular flange with an annular shoulder, said pneumatic actuator exerting a selective axial force against said annular shoulder to move said venturi valve within said inner chamber.
- 4. The variable flow venturi assembly of claim 3, wherein said annular flange includes an opposing annular shoulder and a spring biased against said opposing annular shoulder, said spring exerting a force against said annular flange which opposes said pneumatic actuator.
- 5. The variable flow venturi assembly of claim 1, wherein said at least one bypass port includes a plurality of bypass ports, said inner chamber including a smaller diameter portion in which said venturi valve is slidably disposed, each said bypass port being covered by said smaller diameter portion an amount which is dependent upon a selected position of said venturi valve within said inner chamber.
- 6. The variable flow venturi assembly of claim 5, wherein each said bypass opening is entirely open when said venturi valve is at a full bypass position within said inner chamber.
- 7. The variable flow venturi assembly of claim 5, wherein each said induction port terminates at a location downstream from said venturi section.
- 8. The variable flow venturi assembly of claim 1, wherein said inner chamber includes an annular recess and said at least one induction port comprises a plurality of induction ports, each said induction port in communication with said annular recess and said throughhole.
- 9. The variable flow venturi assembly of claim 8, wherein each said induction port terminates at a location adjacent to and downstream from said venturi section.
- 10. An internal combustion engine, comprising:an intake manifold; and a variable flow venturi assembly, including: a housing attached to said intake manifold, said housing having an inner chamber, a combustion air inlet in communication with said inner chamber, and an exhaust gas inlet in communication with said inner chamber; a venturi valve slidably disposed within said inner chamber, said venturi valve including a longitudinally extending throughhole with an inlet opening in communication with said combustion air inlet, an outlet opening and a venturi section interposed between and in communication with each of said inlet opening and said outlet opening, said venturi valve further including at least one bypass port and at least one induction port, each said bypass port in communication with said combustion air inlet and said throughhole, each said induction port in communication with said exhaust gas inlet and said throughhole; and an actuator for slidably moving said venturi valve within said chamber of said housing.
- 11. The internal combustion engine of claim 10, wherein said actuator includes a pneumatic actuator.
- 12. The internal combustion engine of claim 11, wherein said venturi valve includes an annular flange with an annular shoulder, said pneumatic actuator exerting a selective axial force against said annular shoulder to move said venturi valve within said inner chamber.
- 13. The internal combustion engine of claim 12, wherein said annular flange includes an opposing annular shoulder and a spring biased against said opposing annular shoulder, said spring exerting a force against said annular flange which opposes said pneumatic actuator.
- 14. The internal combustion engine of claim 10, wherein said at least one bypass port includes a plurality of bypass ports, said inner chamber including a smaller diameter portion in which said venturi valve is slidably disposed, each said bypass port being covered by said smaller diameter portion an amount which is dependent upon a selected position of said venturi valve within said inner chamber.
- 15. The internal combustion engine of claim 14, wherein each said bypass opening is entirely open when said venturi valve is at a full bypass position within said inner chamber.
- 16. The internal combustion engine of claim 14, wherein each said induction port terminates at a location downstream from said venturi section.
- 17. The internal combustion engine of claim 10, wherein said inner chamber includes an annular recess and said at least one induction port comprises a plurality of induction ports, each said induction port in communication with said annular recess and said throughhole.
- 18. The internal combustion engine of claim 17, wherein each said induction port terminates at a location adjacent to and downstream from said venturi section.
- 19. A method of operating a variable flow venturi assembly in an exhaust gas recirculation system of an internal combustion engine, comprising the steps of:providing a housing having an inner chamber, a combustion air inlet in communication with said inner chamber, and an exhaust gas inlet in communication with said inner chamber; providing a venturi valve slidably disposed within said inner chamber, said venturi valve including a longitudinally extending throughhole with an inlet opening in communication with said combustion air inlet, an outlet opening and a venturi section interposed between and in communication with each of said inlet opening and said outlet opening, said venturi valve further including at least one bypass port and at least one induction port, each said bypass port in communication with said combustion air inlet and said throughhole, each said induction port in communication with said exhaust gas inlet and said throughhole; moving said venturi valve in a slidable manner within said inner chamber of said housing using an actuator; and covering each said bypass port a selected amount dependent upon said moving step.
- 20. The method of claim 19, wherein said venturi valve includes an annular flange with an annular shoulder, and wherein said moving step comprises the substep of exerting a selective axial force against said annular shoulder with said actuator to move said venturi valve within said inner chamber.
- 21. The method of claim 20, wherein said annular flange includes an opposing annular shoulder, and comprising the further step of exerting a force using a spring against said annular flange which opposes said actuator.
- 22. The method of claim 19, wherein each said induction port is always uncovered, independent of said moving step.
- 23. The method of claim 19, wherein said actuator includes a pneumatic actuator.
US Referenced Citations (14)