U.S. patent application number 09/742700 was filed with the patent office on 2002-06-20 for twin turbine exhaust gas re-circulation system having a second stage variable nozzle turbine.
Invention is credited to Coleman, Gerald N., Faletti, James J., Feucht, Dennis D., Pierpont, David A..
Application Number | 20020073981 09/742700 |
Document ID | / |
Family ID | 24985868 |
Filed Date | 2002-06-20 |
United States Patent
Application |
20020073981 |
Kind Code |
A1 |
Coleman, Gerald N. ; et
al. |
June 20, 2002 |
TWIN TURBINE EXHAUST GAS RE-CIRCULATION SYSTEM HAVING A SECOND
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. 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 includes a
controllable, variable intake nozzle. The first compressor outlet
is fluidly coupled with the second compressor inlet. The engine has
good fuel consumption characteristics and EGR flow rate
control.
Inventors: |
Coleman, Gerald N.; (Peoria,
IL) ; Faletti, James J.; (Spring Valley, IL) ;
Feucht, Dennis D.; (Morton, IL) ; Pierpont, David
A.; (Peoria, IL) |
Correspondence
Address: |
Raymond W. Campbell
Taylor & Aust, P.C.
142 South Main Street
Avilla
IN
46710
US
|
Family ID: |
24985868 |
Appl. No.: |
09/742700 |
Filed: |
December 20, 2000 |
Current U.S.
Class: |
123/605 ;
123/607; 123/611; 123/612 |
Current CPC
Class: |
F02B 37/24 20130101;
F02B 37/001 20130101; Y02T 10/144 20130101; F02M 26/08 20160201;
F02B 29/0406 20130101; F02B 37/025 20130101; F02D 41/0007 20130101;
F02M 26/23 20160201; Y02T 10/12 20130101; F02D 41/0065 20130101;
F02B 37/013 20130101; F02M 26/43 20160201 |
Class at
Publication: |
123/605 ;
123/607; 123/611; 123/612 |
International
Class: |
F02P 003/06; F02P
001/00; F02P 009/00 |
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 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 fixed geometry and being fluidly
coupled with said first exhaust manifold; and a second turbocharger
including a second turbine having an inlet with a controllable,
variable intake nozzle and having an outlet, and including 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.
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 with
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.
4. The internal combustion engine of claim 3, said at least one
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 at least one
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 said second exhaust
manifold and said intake manifold, and a valve and a cooler
associated with said exhaust gas re-circulation duct.
7. The internal combustion engine of claim 6, including an
aftercooler fluidly interconnecting said second compressor outlet
and said at least one 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. The internal combustion engine of claim 1, said first turbine
being a fixed housing turbine having a first turbine fixed geometry
first inlet fluidly connected to said second turbine outlet and a
first turbine fixed geometry second inlet fluidly connected to said
first exhaust manifold.
10. 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 fixed geometry and being fluidly coupled with the
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
fluidly coupled with said second exhaust manifold and having a
controllable, variable intake nozzle, and said second compressor
inlet being fluidly coupled with said first compressor outlet.
11. The turbocharger system of claim 10, 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.
12. The turbocharger system of claim 11 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 and an outlet
in fluid communication with said intake manifold.
13. The turbocharger system of claim 12, 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 10, said first turbine at
least one inlet being fluidly coupled with said first exhaust
manifold, and with said second turbine outlet.
15. The turbocharger system of claim 14, including an exhaust gas
re-circulation duct fluidly interconnecting said second exhaust
manifold and said intake manifold, and a valve and a cooler
associated with said exhaust gas re-circulation duct.
16. The turbocharger system of claim 15, including an aftercooler
fluidly interconnecting said second compressor outlet and said
intake manifold.
17. The turbocharger system of claim 16, including an intercooler
fluidly interconnecting said first compressor outlet and said
second compressor inlet.
18. A method of operating an internal combustion engine, comprising
the steps of: providing a plurality of combustion cylinders, an
intake manifold supplying combustion gas to said plurality of
combustion cylinders, and first and second exhaust manifolds;
transporting exhaust gas from said plurality of combustion
cylinders to said first exhaust manifold and said second exhaust
manifold; providing 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; providing a second turbocharger
including a second turbine having a controllable, variable intake
nozzle at an inlet and having an outlet, and including a second
compressor having an inlet and an outlet; rotatably driving said
first turbine with exhaust gas introduced at said first turbine at
least one inlet from each said second turbine outlet and 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 compressed combustion gas from said
first compressor outlet to said second compressor inlet;
transporting compressed combustion gas from said second compressor
outlet to said at least one 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.
19. The method of claim 18, further including the steps of
providing said first turbine at least one inlet with at least two
first turbine inlets, transporting fluid from said second turbine
outlet to one of said first turbine inlets, and transporting fluid
from said first exhaust manifold to a second of said inlets.
20. The method of claim 18, including the step of re-circulating
exhaust gas in an exhaust gas re-circulation duct interconnecting
at least one of said first and second exhaust manifolds and said
intake manifold.
21. A turbocharger and engine emissions control 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 and engine emissions control 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
fixed geometry and being fluidly coupled with the first exhaust
manifold; 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 controllable variable
inlet nozzle fluidly coupled with said second exhaust manifold, and
said second compressor inlet being fluidly coupled with said first
compressor outlet; and an exhaust gas recirculation duct fluidly
coupled to said second exhaust manifold and said intake manifold.
Description
TECHNICAL FIELD
[0001] The present invention relates to internal combustion engine
turbochargers and exhaust gas recirculation systems, and, more
particularly, to an internal combustion engine having multiple
exhaust gas manifolds, a twin turbine 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 provided 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, a
first exhaust manifold and a second exhaust manifold each coupled
with a plurality of the combustion cylinders, and at least one
intake manifold 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. A second
turbocharger includes a second turbine having an inlet and an
outlet, and a second compressor having an inlet and an outlet. The
inlet of the second turbine has a controllable, variable intake
nozzle and 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 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 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 has a
controllable, variable intake nozzle. 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 with the steps
of: providing a plurality of combustion cylinders, an intake
manifold supplying combustion gas to said plurality of combustion
cylinders and first and second exhaust manifolds; transporting
exhaust gas from the plurality of combustion cylinders to the first
exhaust manifold and the second exhaust manifold; providing 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; providing a second turbocharger including a second turbine
having a
[0011] In another aspect of the 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 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 has a
controllable, variable intake nozzle. The second compressor inlet
is fluidly coupled with the first compressor outlet.
[0012] In yet another aspect of the invention, a method of
operating an internal combustion engine is provided with the steps
of: providing a plurality of combustion cylinders, an intake
manifold supplying combustion gas to said plurality of combustion
cylinders and first and second exhaust manifolds; transporting
exhaust gas from the plurality of combustion cylinders to the first
exhaust manifold and the second exhaust manifold; providing 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; providing a second turbocharger including a second turbine
having a controllable, variable 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 first turbine at
least one inlet from each the second turbine outlet and 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 compressed combustion gas from the first compressor
outlet to the second compressor inlet; transporting compressed
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.
[0013] In still another aspect of the 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 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. 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 has a
controllable, variable intake nozzle and is fluidly coupled with
the second exhaust manifold. The second compressor inlet is fluidly
coupled with the first compressor outlet. An EGR duct is fluidly
coupled to the second exhaust manifold and to the intake
manifold.
BRIEF DESCRIPTION OF THE DRAWING
[0014] The sole drawing FIGURE is a schematic representation of an
internal combustion engine, including turbocharger and exhaust gas
re-circulation systems of the present invention
BEST MODE FOR CARRYING OUT THE INVENTION
[0015] Referring now to the drawing, there is shown an embodiment
of an internal combustion engine 10 including an embodiment of a
turbocharger system 12 of the present invention.
[0016] Internal combustion engine 10 includes a plurality of
combustion cylinders 14, such as the six combustion cylinders 14
shown in FIG. 1, 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 FIG. 1 includes a single intake manifold 16
which is fluidly coupled with each combustion cylinder 14, and
provides an air 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.
[0017] Turbocharger system 12 includes a first turbocharger 22 and
a second turbocharger 24. First turbocharger 22 includes a
wastegated, fixed housing first turbine 26 having a first inlet 27,
a second inlet 28 and an outlet 30. First turbocharger 22 further
includes a first compressor 32 having an inlet 34 and an outlet
36.
[0018] First turbine 26 is mechanically coupled with first
compressor 32, such as by a shaft 37, and thereby rotatably drives
first compressor 32. Second inlet 28 of first turbine 26 is fluidly
coupled with exhaust manifold 18 via a fluid conduit 38, and
receives exhaust gas therefrom for rotatably driving first turbine
26. First turbine outlet 30 discharges spent exhaust gas to an
exhaust system, including any needed muffler, (not shown) and then
to an ambient environment. First compressor inlet 34 receives
combustion air from the ambient environment, for compressing within
first compressor 32.
[0019] 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. Inlet 42 of second turbine 40 includes a
controllably actuatable variable intake nozzle 52 at inlet 42, with
a constriction area which may be controllably adjusted to thereby
provide an inlet orifice to second turbine 40 with a varying area.
By varying the area of intake nozzle 52, the flow rate through
second turbine 40 is controlled, which in turn controls the
rotational output speed of second turbine 40.
[0020] Second turbine outlet 44 is fluidly coupled with first inlet
27 of first turbine 26 via a fluid conduit 53. It should be
understood that first turbine 26 also may be provided with only a
single inlet, such as inlet 28 coupled to first exhaust manifold 18
by conduit 38, in which case fluid conduit 53 will fluidly
communicate with inlet 28, perhaps through conduit 38. Inlet 42 of
second turbine 40 is fluidly coupled with second exhaust manifold
20 via a fluid conduit 54.
[0021] Second compressor 46 is mechanically coupled with and
rotatably driven by second turbine 40 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.
[0022] An engine emissions control system in the form of 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.
[0023] Valve 66 includes an inlet 72 and an outlet 74, and is
fluidly coupled with EGR duct 70 to control the flow to intake
manifold 16.
[0024] 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.
[0025] 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 52, for controlling and adjusting the area
thereof.
[0026] Industrial Applicability
[0027] During use of engine 10 and turbocharger and EGR system 12,
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 38, for rotatably driving first turbine 26. First turbine
26 in turn rotatably drives first compressor 32 via shaft 37.
[0028] 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 53 to first inlet 27 of first turbine 26, for
rotatably driving first turbine 26, allowing for the further
utilization of the exhaust gas energy remaining. The spent exhaust
gas is discharged from first turbine 26 outlet 30 to the ambient
environment.
[0029] In response to data obtained on engine operating conditions,
or data on performance of the turbochargers, the controllable
variable intake nozzle 52 at inlet 42 of second turbine 40 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 52
at inlet 42, the flow rate through second turbine 40 is controlled,
which in turn controls the rotational output speed of second
turbine 40, and therefore the rotational speed and performance of
second compressor 46, which is driven by second turbine 40.
[0030] 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 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.
[0031] 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.
[0032] 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 controllably actuated via suitable electrical
circuitry (not shown) to control the amount of exhaust gas which is
re-circulated to intake manifold 16. Cooler 68 is used to cool the
exhaust gas which is recirculated to intake manifold 16.
[0033] Valve 66 is selectively actuated to control the flow of
exhaust gas from valve 66 outlet 74. Exhaust gas flowing through
valve 66 outlet 74 is cooled within EGR cooler 68 and then
transported to mixer 80 for mixing with the combustion air
compressed by first compressor 32 and second compressor 46, and
cooled by 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.
[0034] System 12 has good fuel consumption characteristics, and
excellent EGR flow rate control with controllable variable intake
nozzle 52 at inlet 42 of second turbine 40.
[0035] 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 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.
[0036] Other aspects, objects and advantages of this invention can
be obtained from a study of the drawings, the disclosure and the
appended claims.
* * * * *