U.S. patent application number 09/755632 was filed with the patent office on 2002-07-11 for two turbocharger exhaust gas re-circulation system having a frist stage variable nozzle turbine.
Invention is credited to Coleman, Gerald N., Faletti, James J., Feucht, Dennis D., Pierpont, David A..
Application Number | 20020088230 09/755632 |
Document ID | / |
Family ID | 25039933 |
Filed Date | 2002-07-11 |
United States Patent
Application |
20020088230 |
Kind Code |
A1 |
Coleman, Gerald N. ; et
al. |
July 11, 2002 |
TWO TURBOCHARGER EXHAUST GAS RE-CIRCULATION SYSTEM HAVING A FRIST
STAGE VARIABLE NOZZLE TURBINE
Abstract
An internal combustion engine, particularly suitable for a motor
vehicle, is provided with a plurality of combustion cylinders, at
least a first exhaust manifold and a second exhaust manifold and at
least one intake manifold. Each exhaust manifold is coupled with a
plurality of the combustion cylinders. Each intake manifold is
coupled with a plurality of the combustion cylinders. A first
turbocharger includes a first turbine having at least one inlet and
an outlet, and a first compressor having an inlet and an outlet.
The at least one first turbine inlet is fluidly coupled with the
first exhaust manifold and includes a controllable, variable intake
nozzle. A second turbocharger includes a second turbine having an
inlet and an outlet, and a second compressor having an inlet and an
outlet. The second turbine inlet is fluidly coupled with the second
exhaust manifold. The first compressor outlet is fluidly coupled
with the second compressor inlet. The engine has improved
performance and efficiency, with an efficient and compact
turbocharger arrangement.
Inventors: |
Coleman, Gerald N.; (Peoria,
IL) ; Faletti, James J.; (Spring Valley, IL) ;
Feucht, Dennis D.; (Morton, IL) ; Pierpont, David
A.; (Peoria, IL) |
Correspondence
Address: |
Todd T. Taylor
Taylor & Aust, P.C.
142 south Main Street
Avilla
IN
46710
US
|
Family ID: |
25039933 |
Appl. No.: |
09/755632 |
Filed: |
January 5, 2001 |
Current U.S.
Class: |
60/605.1 ;
60/605.2; 60/612 |
Current CPC
Class: |
F02B 37/22 20130101;
F02M 26/42 20160201; F02M 26/71 20160201; F01N 13/107 20130101;
Y02T 10/144 20130101; F02B 37/24 20130101; F02B 37/001 20130101;
Y02T 10/12 20130101; F02B 37/18 20130101; F02B 37/013 20130101;
F02B 37/004 20130101; F02M 26/23 20160201; F02M 26/08 20160201;
F02M 26/05 20160201 |
Class at
Publication: |
60/605.1 ;
60/605.2; 60/612 |
International
Class: |
F02B 033/44 |
Claims
1. An internal combustion engine, comprising: a plurality of
combustion cylinders; a first exhaust manifold and a second exhaust
manifold, each said first exhaust manifold and said second exhaust
manifold coupled with a plurality of said combustion cylinders; at
least one intake manifold, each said intake manifold coupled with a
plurality of said combustion cylinders; a first turbocharger
including a first turbine having an inlet and an outlet, and a
first compressor having an inlet and an outlet, said first turbine
inlet having a controllable, variable intake nozzle and being
fluidly coupled with said first exhaust manifold; and a second
turbocharger including a second turbine having an inlet and an
outlet, and a second compressor having an inlet and an outlet, said
second turbine inlet having a fixed geometry and being fluidly
coupled with said second exhaust manifold, said second compressor
inlet being fluidly coupled with said first compressor outlet.
2. The internal combustion engine of claim 1, including an exhaust
gas re-circulation duct fluidly interconnecting at least one of
said first exhaust manifold and said second exhaust manifold to
said intake manifold.
3. The internal combustion engine of claim 2, including an exhaust
gas re-circulation valve disposed in said exhaust gas
re-circulation duct, said exhaust gas re-circulation valve having
an inlet in fluid communication with said second exhaust manifold,
a first outlet in fluid communication with said first turbine
inlet, and a second outlet in fluid communication with said at
least one intake manifold.
4. The internal combustion engine of claim 3, said first turbine
inlet being fluidly coupled with said first exhaust manifold, and
with said second turbine outlet.
5. The internal combustion engine of claim 1, said first turbine
inlet being fluidly coupled with said first exhaust manifold, and
with said second turbine outlet.
6. The internal combustion engine of claim 5, including an exhaust
gas re-circulation duct fluidly interconnecting at least one of
said first and said second exhaust manifold s with said intake
manifold, and a valve and a cooler associated with said exhaust gas
re-circulation duct.
7. The internal combustion engine of claim 5, including an
aftercooler fluidly interconnecting said second compressor outlet
and at least one said intake manifold.
8. The internal combustion engine of claim 7, including an
intercooler fluidly interconnecting said first compressor outlet
and said second compressor inlet.
9. A turbocharger system for use with an internal combustion engine
having a plurality of combustion cylinders, an intake manifold and
first and second exhaust manifolds, said turbocharger system
comprising: a first turbocharger including a first turbine having
at least one inlet and an outlet, and a first compressor having an
inlet and an outlet, said at least one first turbine inlet having a
controllable, variable intake nozzle and being fluidly coupled with
the first exhaust manifold; and second turbocharger including a
second turbine having an inlet and an outlet, and a second
compressor having an inlet and an outlet, said second turbine inlet
being fluidly coupled with said second exhaust manifold, and said
second compressor inlet being fluidly coupled with said first
compressor outlet.
10. The turbocharger system of claim 9, including an exhaust gas
re-circulation duct interconnecting at least one of said first
exhaust manifold and said second exhaust manifold to said intake
manifold.
11. The turbocharger system of claim 10 including an exhaust gas
re-circulation valve disposed in said exhaust gas re-circulation
duct, said exhaust gas re-circulation valve having an inlet in
fluid communication with said second exhaust manifold, a first
outlet in fluid communication with said first turbine at least one
inlet, and a second outlet in fluid communication with said intake
manifold.
12. The turbocharger system of claim 11, said first turbine at
least one inlet being fluidly coupled with said first exhaust
manifold, and with said second turbine outlet.
13. The turbocharger system of claim 9, said first turbine at least
one inlet being fluidly coupled with said first exhaust manifold,
and with said second turbine outlet.
14. The turbocharger system of claim 13, including an exhaust gas
re-circulation duct fluidly interconnecting at least one of said
first and said second exhaust manifolds with said intake manifold,
and a valve and a cooler associated with said exhaust gas
re-circulation duct.
15. The turbocharger system of claim 14, including an aftercooler
fluidly interconnecting said second compressor outlet and said
intake manifold.
16. The turbocharger system of claim 15, including an intercooler
fluidly interconnecting said first compressor outlet and said
second compressor inlet.
17. A method of operating an internal combustion engine, comprising
the steps of: providing a plurality of combustion cylinders and an
intake manifold supplying combustion gas to said plurality of
combustion cylinders; transporting exhaust gas from said plurality
of combustion cylinders to at least a first exhaust manifold and a
second exhaust manifold; providing a first turbocharger including a
first turbine having at least one first turbine inlet with a
controllable variable intake nozzle and having an outlet, and a
first compressor having an inlet and an outlet; providing a second
turbocharger including a second turbine having an inlet and an
outlet, and a second compressor having an inlet and an outlet;
rotatably driving said first turbine with exhaust gas introduced at
said at least one first turbine inlet from said first exhaust
manifold; rotatably driving said second turbine with exhaust gas
introduced at said second turbine inlet from said second exhaust
manifold; introducing combustion gas at said first compressor
inlet; transporting combustion gas from said first compressor
outlet to said second compressor inlet; transporting combustion gas
from said second compressor outlet to said intake manifold; sensing
at least one of operating conditions of said engine and performance
of said turbochargers; and controlling said controllable variable
intake nozzle in response to at least one of said engine operating
conditions and said performance of said turbochargers.
18. The method of claim 17, including providing a fluid conduit
fluidly interconnecting said at least one first turbine inlet with
said second turbine outlet, and transporting exhaust gas from said
second turbine outlet to said at least one first turbine inlet.
19. The method of claim 17, including providing a re-circulation
duct fluidly interconnecting at least one of said first and said
second exhaust manifolds with said intake manifold, and
recirculating exhaust gas from said at least one exhaust manifold
to said intake manifold.
20. A turbocharger and engine emission control system for an
internal combustion engine having a plurality of combustion
cylinders, an intake manifold and first and second exhaust
manifolds; comprising: a first turbocharger including a first
turbine having an inlet and an outlet, and a first compressor
having an inlet and an outlet, said first turbine inlet having a
controllable variable intake nozzle and being fluidly coupled with
the first exhaust manifold; a second turbocharger including a
second turbine having a fixed inlet and an outlet, and a second
compressor having an inlet and an outlet, said second turbine inlet
fluidly coupled with said second exhaust manifold, said second
compressor inlet fluidly coupled with said first compressor outlet,
and said second compressor outlet fluidly coupled with the intake
manifold; and an exhaust gas re-circulation duct fluidly coupled to
said second exhaust manifold and said intake manifold.
21. The system of claim 20, including a valve in said exhaust gas
re-circulation duct, said valve having an inlet fluidly coupled to
said second exhaust manifold, a first outlet fluidly coupled to
said first turbine inlet, and a second outlet fluidly coupled to
said intake manifold.
22. The system of claim 20, including a fluid conduit
interconnecting said second turbine outlet and said first turbine
inlet.
Description
TECHNICAL FIELD
[0001] The present invention relates to internal combustion engine
turbochargers and exhaust gas re-circulation systems, and, more
particularly, to an internal combustion engine having multiple
exhaust gas manifolds, a two turbocharger and an exhaust gas
re-circulation system.
BACKGROUND ART
[0002] An internal combustion engine may include one or more
turbochargers for compressing a fluid to be supplied to one or more
combustion chambers within corresponding combustion cylinders. Each
turbocharger typically includes a turbine driven by exhaust gases
of the engine, and a compressor driven by the turbine. The
compressor receives the fluid to be compressed and supplies the
compressed fluid to the combustion chambers. The fluid compressed
by the compressor may be in the form of combustion air only, or may
be a mixture of fuel and combustion air.
[0003] It is known to provide multiple turbochargers within a
turbocharger system in an internal combustion engine. For example,
U.S. Pat. No. 3,250,068 (Vulliamy) discloses an internal combustion
engine having two turbochargers. A first turbocharger includes a
turbine which is driven by a single exhaust manifold on the
internal combustion engine. The spent exhaust gas from the turbine
of the first turbocharger is transported in a series manner to the
inlet of a turbine of the second turbocharger. The spent exhaust
gas is then discharged to the ambient environment from the turbine
of the second turbocharger. The compressor of the second
turbocharger compresses ambient combustion air and provides the
compressed combustion air in a series manner to the compressor of
the first turbocharger, which in turn transports the compressed
combustion air to the intake manifold of the engine.
[0004] A problem with a turbocharger system as described above is
that the spent exhaust gas from the turbine of the first
turbocharger may not have enough energy to provide a desired
compression ratio within the second turbocharger. The overall
compression ratio from the turbocharger system is thus limited
according to the amount of energy available at the turbine of the
second turbocharger.
[0005] An exhaust gas re-circulation (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
re-circulate 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, further reducing the amount of exhaust gas by-products
emitted as undesirable pollutants from the internal combustion
engine.
[0006] Dependent upon certain operating conditions associated with
a diesel engine, it may be desirable to provide a richer or leaner
mixture of the exhaust gas within the combustion air which is
transported to the intake manifold. One known technique for
controlling the amount of exhaust gas which is mixed with the
combustion air utilizes controllably actuatable valves which
interconnect the exhaust manifold with the compressor which
receives the exhaust gas. The flow of exhaust gas to the second
compressor can be completely shut off, or can be controlled on a
timed basis to provide a desired average flow of exhaust gas which
mixes with the combustion air. Another known technique is to
provide a bypass fluid conduit associated with the combustion air
or exhaust gas. A controllably actuatable butterfly valve or the
like is positioned within the bypass fluid conduit and controlled
to in turn control the amount of exhaust gas which mixes with the
combustion air. Although such systems are effective to control
exhaust gas re-circulation within the diesel engine, they usually
require that additional structure in the form of sensors, conduits,
valves and associated controllers be added to the internal
combustion engine.
[0007] The present invention is directed to overcoming one or more
of the problems as set forth above.
DISCLOSURE OF THE INVENTION
[0008] In one aspect of the invention, an internal combustion
engine is provided with a plurality of combustion cylinders, and a
first exhaust manifold and a second exhaust manifold each coupled
with a plurality of combustion cylinders. At least one intake
manifold is provided, coupled with a plurality of the combustion
cylinders. A first turbocharger includes a first turbine having an
inlet and an outlet, and a first compressor having an inlet and an
outlet. The first turbine inlet has a controllable variable intake
nozzle, and is fluidly coupled with the first exhaust manifold. A
second turbocharger includes a second turbine having an inlet and
an outlet, and a second compressor having an inlet and an outlet.
The second turbine inlet is fluidly coupled with the second exhaust
manifold. The second compressor inlet is fluidly coupled with the
first compressor outlet.
[0009] In another aspect of the present invention, a turbocharger
system is provided, for use with an internal combustion engine
having a plurality of combustion cylinders, an intake manifold and
first and second exhaust manifolds. The turbocharger system has a
first turbocharger including a first turbine having at least one
inlet and an outlet, and a first compressor having an inlet and an
outlet. The at least one first turbine inlet has a controllable,
variable intake nozzle, and is fluidly coupled with the first
exhaust manifold. A second turbocharger includes a second turbine
having an inlet and an outlet, and a second compressor having an
inlet and an outlet. The second turbine inlet is fluidly coupled
with the second exhaust manifold, and the second compressor inlet
is fluidly coupled with the first compressor outlet.
[0010] In yet another aspect of the invention, a method of
operating an internal combustion engine is provided having steps of
providing a plurality of combustion cylinders and an intake
manifold supplying combustion gas to the plurality of combustion
cylinders; transporting exhaust gas from the plurality of
combustion cylinders to at least a first exhaust manifold and a
second exhaust manifold; providing a first turbocharger including a
first turbine having at least one first turbine inlet with a
controllable variable intake nozzle and having an outlet, and a
first compressor having an inlet and an outlet; providing a second
turbocharger including a second turbine having an inlet and an
outlet, and a second compressor having an inlet and an outlet;
rotatably driving the first turbine with exhaust gas introduced at
the at least one first turbine inlet from the first exhaust
manifold; rotatably driving the second turbine with exhaust gas
introduced at the second turbine inlet from the second exhaust
manifold; introducing combustion gas at the first compressor inlet;
transporting combustion gas from the first compressor outlet to the
second compressor inlet; transporting combustion gas from the
second compressor outlet to the intake manifold; sensing at least
one of operating conditions of the engine and performance of the
turbochargers; and controlling the controllable, variable intake
nozzle in response to at least one of the engine operating
conditions and the performance of the turbochargers.
[0011] In still another aspect of the present invention, a
turbocharger and engine emission control system is provided for use
with an internal combustion engine having a plurality of combustion
cylinders, an intake manifold and first and second exhaust
manifolds. A first turbocharger includes a first turbine having an
inlet and an outlet, and a first compressor having an inlet and an
outlet. The first turbine inlet has a controllable variable intake
nozzle, and is fluidly coupled with the first exhaust manifold. A
second turbocharger includes a second turbine having a fixed inlet
and an outlet, and a second compressor having an inlet and an
outlet. The second turbine inlet is fluidly coupled with the second
exhaust manifold. The second compressor inlet is fluidly coupled
with the first compressor outlet, and the second compressor outlet
is fluidly coupled with the intake manifold. An exhaust gas
re-circulation duct is fluidly coupled to the second exhaust
manifold and the intake manifold.
BRIEF DESCRIPTION OF THE DRAWING
[0012] The sole drawing, FIG. 1, is a schematic representation of
an internal combustion engine, including a turbocharger and exhaust
gas re-circulation system of the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0013] Referring now to the drawing, there is shown an embodiment
of an internal combustion engine 10 including a turbocharger system
12 of the present invention.
[0014] Internal combustion engine 10 includes a plurality of
combustion cylinders 14, such as the six combustion cylinders 14
shown in the drawing, each of which is coupled with a corresponding
intake manifold 16 and exhaust manifold 18, 20. Internal combustion
engine 10 includes one or more intake manifolds 16, and in the
embodiment shown in the drawing includes a single intake manifold
16 which is fluidly coupled with each combustion cylinder 14, and
provides a combustion gas mixture to each combustion cylinder 14,
as will be described hereinafter. Internal combustion engine 10
also includes one or more exhaust manifolds 18, 20, and in the
embodiment shown includes a first exhaust manifold 18 and a second
exhaust manifold 20. First exhaust manifold 18 is fluidly coupled
with three combustion cylinders 14, and second exhaust manifold 20
is fluidly coupled with the remaining three combustion cylinders
14. A fuel, such as diesel fuel, is injected into each combustion
cylinder 14 and combusted therein, in known manner.
[0015] Turbocharger system 12 includes a first turbocharger 22 and
a second turbocharger 24. First turbocharger 22 includes a first
turbine 26 having at least one first turbine inlet 28 and an outlet
30, and a first compressor 32 having an inlet 34 and an outlet 36.
First turbine 26 may be provided as a divided housing turbine
having multiple inlets. Inlet 28 includes a controllably actuatable
variable intake nozzle 38 at inlet 28, with a constriction nozzle
which may be controllably adjusted to thereby provide an inlet
orifice to first turbine 26 with a varying area. By varying the
area of intake nozzle 38, the flow rate through first turbine 26 is
controlled, which in turn controls the rotational output speed of
first turbine 26.
[0016] First turbine 26 is mechanically coupled with first
compressor 32, such as by a shaft 37, and thereby rotatably drives
first compressor 32. First turbine inlet 28 is fluidly coupled with
exhaust manifold 18 via a fluid conduit 39, and receives exhaust
gas therefrom for rotatably driving first turbine 26. The exhaust
gas which passes through and exits from first turbine 26 flows to
the engine exhaust gas system, including any muffler (not shown),
and is eventually discharged to the ambient environment. First
compressor inlet 34 receives combustion air from the ambient
environment, for compressing within first compressor 32.
[0017] Second turbocharger 24 includes a second turbine 40 having
an inlet 42 and an outlet 44, and a second compressor 46 having an
inlet 48 and an outlet 50. Unlike first turbine inlet 28, which
includes variable intake nozzle 38, second turbine 40 is a fixed
housing turbine, including inlet 42 having a fixed inlet geometry.
Second turbine outlet 44 is fluidly coupled with first turbine
inlet 28 via a fluid conduit 52 fluidly interconnecting outlet 44
with fluid conduit 39. It should be understood that, if first
turbine 26 is provided as a divided housing turbine, with a second
first turbine inlet (not shown), fluid conduit 52 may be connected
to the second first turbine inlet. Inlet 42 of second turbine 40 is
fluidly coupled with second exhaust manifold 20 via a fluid conduit
54.
[0018] Second compressor 46 is mechanically coupled with and
rotatably driven by second turbine 40, such as through a shaft 55.
Second compressor inlet 48 is fluidly coupled with first compressor
outlet 36 via a fluid conduit 56. An optional intercooler 58 is
disposed in fluid communication with fluid conduit 56, for cooling
compressed combustion gas transported from first compressor 32 to
second compressor 46. An aftercooler 60 is disposed in fluid
communication with a fluid conduit 62, which fluidly couples second
compressor 46 outlet 50 with intake manifold 16.
[0019] An EGR system 64 fluidly interconnects second exhaust
manifold 20 with intake manifold 16. A valve 66 and cooler 68 are
positioned in fluid communication with an EGR duct 70. Valve 66
controls a flow of exhaust gas re-circulated from exhaust manifold
20 to intake manifold 16. Cooler 68 acts as a heat exchanger, to
cool the exhaust gas re-circulated to intake manifold 16.
[0020] Valve 66 includes an inlet 72, a first outlet 74 and a
second outlet 76. Inlet 72 is fluidly coupled with second exhaust
manifold 20 via EGR duct 70. Valve first outlet 74 is fluidly
coupled with first turbine inlet 28 and fluid conduit 39 via a
fluid conduit 78. Valve second outlet 76 is fluidly coupled with
intake manifold 16 via EGR duct 70. Again, in the case of a divided
housing first turbine 26, fluid conduit 78 may be fluidly coupled
directly or indirectly with a second first turbine inlet (not
shown).
[0021] A mixer 80 receives exhaust gas flow from EGR duct 70 and
compressed combustion fluid flow from fluid conduit 62, and
supplies a mixture thereof to intake manifold 16 via a fluid
conduit 82.
[0022] A controller 84 is coupled to and receives input data from
engine and turbocharger operating and performance sensors (not
shown), and transmits control signals via a signal line 86 to
variable intake nozzle 38, for controlling and adjusting the area
thereof. The controller 84 is also coupled to and receives input
data from the engine to control the position of the valve 66.
Industrial Applicability
[0023] During use of engine 10,turbocharger system 12 and EGR
system 64, fuel, such as diesel fuel is injected into combustion
cylinders 14 and combusted when a piston (not shown) disposed
within each combustion cylinder 14 is at or near a top dead center
(TDC) position. Exhaust gas is transported from each combustion
cylinder 14 to the exhaust manifold associated with it, either
first exhaust manifold 18 or second exhaust manifold 20. Exhaust
gas within first exhaust manifold 18 is transported to first
turbine 26 via fluid conduit 39, for rotatably driving first
turbine 26. First turbine 26 in turn rotatably drives first
compressor 32 via shaft 37.
[0024] In response to data on engine operating conditions, or data
on performance of the turbochargers received by controller 84, the
controllable variable intake nozzle 38 at inlet 28 is adjusted. For
example, a sensor or sensors, not shown, may sense engine load
condition, engine coolant temperature, combustion air inlet
temperature or an engine start-up condition, as well as various
performance data obtained from first turbocharger 22 and second
turbocharger 24, which is transmitted to and processed by
controller 84. By varying the area of the variable intake nozzle
38, the flow rate through first turbine 26 is controlled, which in
turn controls the rotational output speed of first turbine 26 and
shaft 37, and therefore the rotational speed and performance of
first compressor 32.
[0025] Concurrently, exhaust gas from exhaust manifold 20 is
transported to second turbine inlet 42 via fluid conduit 54 for
driving second turbine 40. Second turbine 40 in turn rotatably
drives second compressor 46 via shaft 55. The spent exhaust gas
from second turbine 40 flows from second turbine outlet 44 through
fluid conduit 52 to fluid conduit 39 for rotatably driving first
turbine 26. The spent exhaust gas is discharged from first turbine
26 outlet 30 to the engine 10 exhaust system and then to the
ambient environment.
[0026] First compressor 32 draws combustion air into first
compressor inlet 34. The combustion air is compressed within first
compressor 32, and is discharged from first compressor 32 outlet 36
through fluid conduit 56. The compressed combustion air is
optionally cooled within intercooler 58, and is transported to
second compressor inlet 48 for further compressing within second
compressor 46. First compressor 32 and second compressor 46 thus
form a multi-stage compressor for compressing combustion air which
is provided to intake manifold 16.
[0027] The compressed combustion air is transported from second
compressor 46 outlet 50 through fluid conduit 62 to aftercooler 60.
The compressed combustion air is again cooled within aftercooler
60, and is transported to intake manifold 16 via mixer 80 and fluid
conduit 82, for use in combustion occurring within combustion
cylinders 14.
[0028] Exhaust gas is re-circulated from second exhaust manifold 20
to intake manifold 16 via EGR duct 70, mixer 80 and fluid conduit
82. Valve 66 is controlled and selectively actuated via suitable
electrical circuitry (not shown) to control the amount of exhaust
gas which is re-circulated to intake manifold 16. Exhaust gas
flowing from first outlet 74 of valve 66 flows through fluid
conduit 78, and mixes with exhaust gas from first exhaust manifold
18, flowing to first turbine 26 inlet 28 via fluid conduit 39 and
variable intake nozzle 38. Exhaust gas from valve 66 second outlet
76 is cooled within EGR cooler 68 and is then transported to mixer
80, for mixing with the combustion air compressed by first
compressor 32 and second compressor 46, and cooled by the optional
interstage cooler 58 and aftercooler 60. The mixture of combustion
air and exhaust gas is then transported to intake manifold 16 via
fluid conduit 82.
[0029] Valve 66 functions both to regulate the flow of exhaust gas
that is mixed with the combustion air transported to intake
manifold 16, and to provide exhaust gas to first turbocharger 22.
Controlling or regulating the amount of exhaust gas transported to
intake manifold 16 provides an effective exhaust gas re-circulation
system within internal combustion engine 10. Moreover, controlling
a flow of exhaust gas to first turbine 26 utilizes energy from the
exhaust gas not transported to intake manifold 16 to drive first
turbine 26.
[0030] EGR valve 66 controls the flow rate of exhaust gases to
intake manifold 16. Second stage fixed turbine 46 establishes a
differential pressure between each of the first exhaust manifold 18
and second exhaust manifold 20 and the intake manifold 16
sufficiently high to force exhaust flow into intake manifold 16.
Variable nozzle 38 at inlet 28 of first turbine 26 can be
controlled to improve engine load acceptance and engine braking by
controlling the performance of first turbine 26, and thus the
performance of first compressor 32.
[0031] The turbocharger system of the present invention provides
multiple turbochargers with turbines and compressors fluidly
coupled together in a series arrangement to provide improved
performance and efficiency. The first turbocharger has a turbine
that receives exhaust gas from both an exhaust manifold and from
the turbine of the second turbocharger. By utilizing the spent
exhaust gas from the second turbocharger, the energy associated
therewith may be recaptured, along with the energy from the first
exhaust manifold, and utilized to drive the turbine of the first
turbocharger. The turbocharger system is compact, efficient and
provides compressed air with a relatively high compression ratio to
the intake manifold.
[0032] Other aspects, objects and advantages of this invention can
be obtained from a study of the drawing, the disclosure and the
appended claims.
* * * * *