U.S. patent application number 13/250076 was filed with the patent office on 2013-01-17 for method for cooling an internal combustion engine having exhaust gas recirculation and charge air cooling.
This patent application is currently assigned to CENTRUM EQUITIES ACQUISITION, LLC. The applicant listed for this patent is John A. Kolb. Invention is credited to John A. Kolb.
Application Number | 20130014733 13/250076 |
Document ID | / |
Family ID | 38470299 |
Filed Date | 2013-01-17 |
United States Patent
Application |
20130014733 |
Kind Code |
A1 |
Kolb; John A. |
January 17, 2013 |
METHOD FOR COOLING AN INTERNAL COMBUSTION ENGINE HAVING EXHAUST GAS
RECIRCULATION AND CHARGE AIR COOLING
Abstract
A system for cooling charge air from a turbo- or supercharger
and exhaust gas recirculated from an exhaust gas recirculation
valve in an internal combustion engine. The system includes a
radiator and parallel charge air and exhaust gas heat exchanger
units, the charge air heat exchanger unit having aluminum tubes and
fins for air cooling the charge air, and the exhaust gas heat
exchanger unit having stainless steel tubes and fins. The charge
air heat exchanger and the exhaust gas heat exchanger units are
each disposed adjacent the radiator, on the same or opposite sides.
Alternatively, there is provided a pair of combined charge air
cooler and exhaust gas cooler heat exchanger units, with a first
heat exchanger unit having stainless steel tubes and fins, and a
second heat exchanger unit having aluminum tubes and fins. The heat
exchanger units are disposed on opposites sides of the
radiator.
Inventors: |
Kolb; John A.; (Old Lyme,
CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Kolb; John A. |
Old Lyme |
CT |
US |
|
|
Assignee: |
CENTRUM EQUITIES ACQUISITION,
LLC
Nashville
TN
|
Family ID: |
38470299 |
Appl. No.: |
13/250076 |
Filed: |
September 30, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
12336196 |
Dec 16, 2008 |
8037685 |
|
|
13250076 |
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Current U.S.
Class: |
123/568.12 |
Current CPC
Class: |
F01P 2060/02 20130101;
F28F 2210/08 20130101; F02M 26/31 20160201; F02B 29/0456 20130101;
F02B 29/0475 20130101; Y02T 10/146 20130101; F01P 3/18 20130101;
F02M 26/30 20160201; F02B 29/0412 20130101; F02B 29/0431 20130101;
F02M 26/27 20160201; F01P 1/06 20130101; F02M 26/24 20160201; F28D
1/0435 20130101; Y02T 10/12 20130101; F28D 1/05366 20130101; F28D
1/0452 20130101; F28F 2215/04 20130101 |
Class at
Publication: |
123/568.12 |
International
Class: |
F02M 25/07 20060101
F02M025/07; F02B 47/08 20060101 F02B047/08 |
Claims
1. A method of cooling charge air from a turbo- or supercharger and
exhaust gas recirculated from an exhaust gas recirculation valve in
an internal combustion engine comprising: providing a radiator for
air cooling of liquid engine coolant from the internal combustion
engine; providing charge air and exhaust gas heat exchanger units
disposed in parallel with respect to ambient air flow, the charge
air heat exchanger unit having aluminum tubes and fins for air
cooling the charge air, and the exhaust gas heat exchanger unit
having tubes and fins made of a material resistant to higher
operating temperatures than aluminum for air cooling the exhaust
gas, the charge air heat exchanger and the exhaust gas heat
exchanger units each being disposed adjacent a face of the radiator
downstream of the radiator with respect to ambient air flow to
permit ambient air to flow in series first through the radiator and
subsequently through the charge air and exhaust gas heat exchanger
units; flowing ambient air in series first through the radiator and
subsequently through the charge air heat exchanger unit without
flowing such air through the exhaust gas heat exchanger unit and
flowing ambient air in series first through the radiator and
subsequently through the exhaust gas heat exchanger unit without
flowing such air through the charge air heat exchanger unit;
passing the charge air from the turbo- or supercharger through the
charge air heat exchanger unit to cool the charge air; passing the
exhaust gas from the exhaust gas recirculation valve through the
exhaust gas heat exchanger unit to cool the exhaust gas; and
combining the cooled charge air and cooled exhaust gas for passage
into an intake manifold on the engine.
2. The method of claim 1 wherein the exhaust gas heat exchanger
unit has tubes and fins made of stainless steel.
3. The method of claim 1 wherein the radiator comprises two units,
the charge air heat exchanger unit being disposed adjacent a face
of one radiator unit and the exhaust gas heat exchanger unit being
disposed adjacent a face of the other radiator unit.
4. The method of claim 3 wherein the charge air heat exchanger unit
and the exhaust gas heat exchanger unit have different core styles
selected from the group consisting of core depth, type of fins, fin
spacing, fin count, tube spacing and tube count.
5-9. (canceled)
10. The method of claim 3 wherein each radiator unit has a
different core style selected from the group consisting of core
depth, type of fins, fin spacing, fin count, tube spacing and tube
count.
11. The method of claim 1 wherein the charge air and exhaust gas
heat exchanger units are a first set disposed downstream of the
radiator with respect to ambient air flow to permit ambient air to
flow in series first through the radiator and subsequently through
the first set of charge air and exhaust gas heat exchanger units,
and further providing a second set of charge air and exhaust gas
heat exchanger units, both heat exchanger units in the second set
having aluminum tubes and fins for air cooling the charge air and
the exhaust gas, the second set of charge air and exhaust gas heat
exchanger units being disposed upstream of the radiator to permit
ambient air to flow in series first through the second set of
charge air and exhaust gas heat exchanger units and subsequently
through the radiator, and wherein the partially cooled charge air
from the charge air heat exchanger unit downstream of the radiator
is passed through the second charge air heat exchanger unit
upstream of the radiator to further cool the charge air and the
partially cooled exhaust gas from the exhaust gas heat exchanger
unit downstream of the radiator is passed through the second
exhaust gas heat exchanger unit upstream of the radiator to further
cool the exhaust gas before combining the cooled charge air and
cooled exhaust gas for passage to the intake manifold of the
engine.
12. (canceled)
13. The method of claim 11 wherein the radiator comprises two
units, the first set of charge air and exhaust gas heat exchanger
units downstream of the radiator being disposed adjacent one
radiator unit and the second set of charge air and exhaust gas heat
exchanger units upstream of the radiator being disposed adjacent
the other radiator unit.
14. The method of claim 13 wherein at least one of the charge air
heat exchanger units or exhaust gas heat exchanger units has a
different core style selected from the group consisting of core
depth, type of fins, fin spacing, fin count, tube spacing and tube
count.
15. The method of claim 13 wherein each radiator unit has a
different core style selected from the group consisting of core
depth, type of fins, fin spacing, fin count, tube spacing and tube
count.
16-28. (canceled)
29. A system for cooling charge air from a turbo- or supercharger
and exhaust gas recirculated from an exhaust gas recirculation
valve in an internal combustion engine comprising: a radiator for
air cooling of liquid engine coolant from the internal combustion
engine; charge air and exhaust gas heat exchanger units disposed in
parallel with respect to ambient air flow, the charge air heat
exchanger unit having aluminum tubes and fins for air cooling the
charge air, and the exhaust gas heat exchanger unit having tubes
and fins made of a material resistant to higher operating
temperatures than aluminum for air cooling the exhaust gas, the
charge air heat exchanger and the exhaust gas heat exchanger units
each being disposed adjacent a face of the radiator downstream of
the radiator with respect to ambient air flow to permit ambient air
to flow in series first through the radiator and subsequently
through the charge air heat exchanger unit without such flowing
through the exhaust gas heat exchanger unit and to permit ambient
air to flow in series first through the radiator and subsequently
through the exhaust gas heat exchanger unit without such air
flowing through the charge air heat exchanger unit; a line for
carrying charge air from the turbo- or supercharger to the charge
air heat exchanger unit to cool the charge air; a line for carrying
the exhaust gas from the exhaust gas recirculation valve to the
exhaust gas heat exchanger unit to cool the exhaust gas; and a line
for combining the cooled charge air and cooled exhaust gas for
passage into an intake manifold on the engine.
30-32. (canceled)
33. The system of claim 29 wherein the radiator comprises two
units, the charge air heat exchanger unit being disposed adjacent a
face of one radiator unit and the exhaust gas heat exchanger unit
being disposed adjacent a face of the other radiator unit.
34. The system of claim 29 wherein the charge air and exhaust gas
heat exchanger units are a first set disposed downstream of the
radiator with respect to ambient air flow to permit ambient air to
flow in series first through the radiator and subsequently through
the first set of charge air and exhaust gas heat exchanger units,
and further including a second set of charge air and exhaust gas
heat exchanger units, both heat exchanger units in the second set
having aluminum tubes and fins for air cooling the charge air and
the exhaust gas, the second set of charge air and exhaust gas heat
exchanger units being disposed upstream of the radiator to permit
ambient air to flow in series first through the second set of
charge air and exhaust gas heat exchanger units and subsequently
through the radiator, and including a line for carrying partially
cooled charge air from the charge air heat exchanger unit
downstream of the radiator to the second charge air heat exchanger
unit upstream of the radiator to further cool the charge air and a
line for carrying partially cooled exhaust gas from the exhaust gas
heat exchanger unit downstream of the radiator to the second
exhaust gas heat exchanger unit upstream of the radiator to further
cool the exhaust gas before combining the cooled charge air and
cooled exhaust gas for passage to the intake manifold of the
engine.
35. The system of claim 34 wherein the radiator comprises two
units, the first set of charge air and exhaust gas heat exchanger
units downstream of the radiator being disposed adjacent one
radiator unit and the second set of charge air and exhaust gas heat
exchanger units upstream of the radiator being disposed adjacent
the other radiator unit.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a cooling system for internal
combustion engines used in trucks and other motor vehicles and, in
particular, to a cooling system utilizing a charge air cooler and
an exhaust gas cooler in combination with a radiator.
[0003] 2. Description of Related Art
[0004] Stricter emissions requirements have forced the use of
partial exhaust gas recirculation as a means of achieving more
complete combustion, and this has necessitated the cooling of the
recirculated exhaust gas before introducing it into the engine
intake manifold. FIG. 1 shows a typical heavy duty truck cooling
system having a liquid-cooled exhaust gas recirculation (EGR)
cooler. The engine cooling system comprises an internal combustion
engine 20 utilizing conventional liquid engine coolant. The liquid
coolant heated by operation of the engine exits the engine through
line or hose 61 and passes through a thermostat 30. If the coolant
is below the thermostat set temperature it is passed through line
63 to coolant pump 32 and back through line 65 to the engine. If
the coolant is above the thermostat set temperature, it is sent
through line 62 to otherwise conventional air cooled radiator 22
where ambient air flow 60, 60a and 60b passes through the radiator
by means of a fan (not shown) as well as movement of the vehicle in
which the engine is mounted. The cooled liquid coolant then passes
through lines 57 and 59 back to the coolant pump before returning
to the engine.
[0005] For mixture with the fuel, the engine utilizes inlet air 40
that passes through a filter (not shown) and is compressed by a
turbo- or supercharger. The engine system depicted herein utilizes
engine exhaust gases exiting through lines 50 and 54 in a
turbocharger in which turbine 26 drives compressor 28. After
passing through the turbine blades, the exhaust gas exits through
line 55 to the exhaust system (not shown). After compression, the
charge air passes through line 42 to air-to-air charge air cooler
(CAC) 24 mounted upstream of radiator 22. The cooled charge air
then exits CAC 24 through line 44.
[0006] A portion of the exhaust gas exiting through line 50 passes
through line 52 and through an EGR valve 48. The exhaust gas then
passes through line 56 to EGR cooler 34, which is a liquid-to-air
heat exchanger that cools the hot exhaust gases using the cooled
liquid engine coolant entering through line 57. Because brazed
aluminum heat exchanger construction is not capable of withstanding
the high exhaust gas temperatures, typically, such an EGR cooler
must be of high-temperature heat exchanger construction; that is,
made of materials able to withstand higher temperatures than brazed
aluminum, such as brazed stainless steel, brazed cupro-nickel,
brazed copper, and the like. The cooled recirculated exhaust gas
then exits the EGR cooler through line 58, where it mixes with the
cooled charge air from line 44. The mixture of cooled recirculated
exhaust gas and charge air then proceeds through line 46 to the
intake manifold 21 of engine 20 for mixture with the fuel and then
to the engine combustion chambers.
[0007] This system has two disadvantages: 1) the high cost of
stainless steel or other high temperature EGR cooler construction
and 2) the cooling limitation resulting from the use of engine
coolant at approximately 180.degree. F.
[0008] FIG. 2 shows another prior art heavy duty truck cooling
system in which the exhaust gas which is to be recirculated is
mixed with the hot charge air coming from the turbocharger for
cooling in an air-cooled heat exchanger. Since the liquid engine
coolant does not need to cool the exhaust gas, the liquid engine
coolant passes through line 57 from radiator 22 and back to coolant
pump 32 for return to the engine. The hot exhaust gas exiting EGR
valve 48 passes through line 56 where it combines and mixes with
compressed, heated charge air in line 41 exiting compressor 28. The
combined heated exhaust gas and charge air then passes through line
43 to a brazed stainless steel combination exhaust gas
recirculation and charge air cooler 24' upstream of radiator 22.
Alternatively, the combination exhaust gas recirculation and charge
air cooler may be made of other high temperature construction such
as the aforementioned brazed cupro-nickel or brazed copper. After
the charge air and exhaust gas are cooled by ambient air 60 passing
through CAC 24', the cooled combined exhaust gas and charge air
then pass through line 45 to engine intake manifold 21. This
approach does allow the recirculated exhaust gas and charge air to
be cooled to a temperature close to that of the ambient cooling
air, which will always be much less than that of the engine
coolant. However, it does not solve the expense problem related to
high temperature-resistant construction and, in fact, increases the
expense by requiring stainless steel or other expensive high
temperature material to be used in a very large combination
EGR/CAC.
[0009] In addition to having high material costs, prior systems and
methods of cooling charge air and/or recirculated exhaust gases in
an internal combustion engine have not been able to individually
tailor thermal performance of individual heat exchanger units in a
space-saving package.
SUMMARY OF THE INVENTION
[0010] Bearing in mind the problems and deficiencies of the prior
art, it is therefore an object of the present invention to provide
an improved system and method of cooling an internal combustion
engine, including charge air cooling and exhaust gas cooling, which
achieves cooling of the charge air and the recirculated exhaust gas
to near ambient temperatures.
[0011] It is another object of the present invention to provide a
system and method of cooling an internal combustion engine,
including charge air cooling and exhaust gas cooling, which allows
the use of lower cost materials for the charge air and exhaust gas
coolers.
[0012] A further object of the present invention is to provide a
system and method of cooling charge air and recirculated exhaust
gas in an internal combustion engine which saves space in a
combined radiator, CAC and EGR cooler package.
[0013] Yet another object of the present invention is to provide a
combined heat exchanger package for an internal combustion engine
that permits tailoring of thermal performance of individual heat
exchanger units within the package.
[0014] Still other objects and advantages of the invention will in
part be obvious and will in part be apparent from the
specification.
[0015] The above and other objects, which will be apparent to those
skilled in the art, are achieved in the present invention which is
directed to a method and apparatus for cooling charge air from a
turbo- or supercharger and exhaust gas recirculated from an exhaust
gas recirculation valve in an internal combustion engine comprising
providing a radiator for air cooling of liquid engine coolant from
the internal combustion engine and providing parallel charge air
and exhaust gas heat exchanger units. The charge air heat exchanger
unit has aluminum tubes and fins for air cooling the charge air,
and the exhaust gas heat exchanger unit having tubes and fins made
of a material resistant to higher operating temperatures than
aluminum for air cooling the exhaust gas. The charge air heat
exchanger and the exhaust gas heat exchanger units are each
disposed adjacent a face of the radiator to permit ambient air to
flow in series through the radiator and the charge air and exhaust
gas heat exchanger units. The method then includes passing the
charge air from the turbo- or supercharger through the charge air
heat exchanger unit to cool the charge air, passing the exhaust gas
from the exhaust gas recirculation valve through the exhaust gas
heat exchanger unit to cool the exhaust gas, and combining the
cooled charge air and cooled exhaust gas for passage into an intake
manifold on the engine.
[0016] Preferably, the exhaust gas heat exchanger unit has tubes
and fins made of stainless steel. The radiator may comprise two
units, with the charge air heat exchanger unit being disposed
adjacent a face of one radiator unit and the exhaust gas heat
exchanger unit being disposed adjacent a face of the other radiator
unit. The charge air heat exchanger unit and the exhaust gas heat
exchanger unit may have different core styles, such as different
core depth, type of fins, fin spacing, fin count, tube spacing and
tube count.
[0017] The charge air and exhaust gas heat exchanger units may be
disposed in parallel adjacent a same face of the radiator to permit
ambient air to flow in series through the radiator and the charge
air and exhaust gas heat exchanger units.
[0018] The charge air and exhaust gas heat exchanger units may be
disposed downstream of the radiator with respect to ambient air
flow to permit ambient air to flow in series first through the
radiator and subsequently through the charge air and exhaust gas
heat exchanger units, or vice-versa.
[0019] The charge air and exhaust gas heat exchanger units may be
disposed adjacent opposite faces of the radiator, with the charge
air heat exchanger unit being disposed upstream of the radiator and
the exhaust gas heat exchanger unit being disposed downstream of
the radiator. This permits ambient air to flow in series first
through charge air heat exchanger unit having aluminum tubes and
fins and then through the radiator, and permits ambient air to flow
in series through the radiator and subsequently through the exhaust
gas heat exchanger unit having tubes and fins made of the higher
temperature resistant material. The radiator may alternately
comprise two units, with the charge air heat exchanger unit being
disposed upstream adjacent one radiator unit and the exhaust gas
heat exchanger unit being disposed downstream adjacent the other
radiator unit. The charge air heat exchanger unit and the exhaust
gas heat exchanger unit may have different core styles, and each
radiator unit may have a different core style.
[0020] Alternatively, the charge air and exhaust gas heat exchanger
units may be a first set disposed downstream of the radiator with
respect to ambient air flow to permit ambient air to flow in series
first through the radiator and subsequently through the first set
of charge air and exhaust gas heat exchanger units. There may be
further provided a second set of charge air and exhaust gas heat
exchanger units, wherein both heat exchanger units in the second
set have aluminum tubes and fins for air cooling the charge air and
the exhaust gas. The second set of charge air and exhaust gas heat
exchanger units are disposed upstream of the radiator to permit
ambient air to flow in series first through the second set of
charge air and exhaust gas heat exchanger units and subsequently
through the radiator. The partially cooled charge air from the
charge air heat exchanger unit downstream of the radiator is passed
through the second charge air heat exchanger unit upstream of the
radiator to further cool the charge air. The partially cooled
exhaust gas from the exhaust gas heat exchanger unit downstream of
the radiator is passed through the second exhaust gas heat
exchanger unit upstream of the radiator to further cool the exhaust
gas before combining the cooled charge air and cooled exhaust gas
for passage to the intake manifold of the engine. At least one of
the charge air heat exchanger units or exhaust gas heat exchanger
units may have a different core style. The radiator may comprises
two units, with the first set of charge air and exhaust gas heat
exchanger units downstream of the radiator being disposed adjacent
one radiator unit and the second set of charge air and exhaust gas
heat exchanger units upstream of the radiator being disposed
adjacent the other radiator unit. Each radiator unit may have a
different core style.
[0021] In another aspect, the present invention is directed to a
method and apparatus for cooling charge air from a turbo- or
supercharger and exhaust gas recirculated from an exhaust gas
recirculation valve in an internal combustion engine comprising
providing a radiator for air cooling of liquid engine coolant from
the internal combustion engine and providing a pair of combined
charge air cooler and exhaust gas cooler heat exchanger units. A
first one of the heat exchanger units has tubes and fins made of a
material able to withstand higher operating temperatures than
aluminum, and the second of the heat exchanger units has aluminum
tubes and fins. The heat exchanger units are disposed adjacent the
radiator to permit ambient air to flow in series through the
radiator and the heat exchanger units. The method includes
combining the charge air from the turbo- or supercharger with the
exhaust gas recirculated from the exhaust gas recirculation valve,
passing the combined charge air and exhaust gas through the first
heat exchanger unit having the tubes and fins made of the higher
temperature resistant material to partially cool the combined
charge air and exhaust gas, passing the partially cooled combined
charge air and exhaust gas through the second heat exchanger unit
having the aluminum tubes and fins to cool the combined charge air
and exhaust gas, and passing the combined cooled charge air and
exhaust gas into an intake manifold on the engine.
[0022] The heat exchanger unit having tubes and fins made of the
higher temperature resistant material, preferably stainless steel,
may be disposed downstream of the radiator with respect to ambient
cooling air flow to permit ambient air to flow in series first
through the radiator and subsequently through the heat exchanger
unit having tubes and fins made of the higher temperature resistant
material. The heat exchanger unit having aluminum tubes and fins
may be disposed upstream of the radiator with respect to ambient
cooling air flow to permit ambient air to flow in series first
through the heat exchanger unit having aluminum tubes and fins and
subsequently through the radiator.
[0023] The radiator may comprises two units, with the first heat
exchanger unit being disposed adjacent a face of one radiator unit
and the second heat exchanger unit being disposed adjacent a face
of the other radiator unit. Each of the first and second heat
exchanger units may have a different core style, and each radiator
unit may have a different core style.
[0024] In a further aspect, the present invention provides a method
and apparatus for cooling engine coolant and charge air from a
turbo- or supercharger in an internal combustion engine comprising
providing a radiator for cooling engine coolant having opposite
front and rear core faces through which ambient air flows, and
opposite upper and lower ends adjacent the faces, and providing a
charge air cooler for cooling charge air having upper and lower
units. Each charge air cooler unit has opposite front and rear core
faces through which ambient air may flow, and opposite upper and
lower ends adjacent the faces. The upper charge air cooler unit is
disposed in overlapping relationship and adjacent to the upper end
of the radiator, wherein one face at the upper end of the radiator
is disposed adjacent one face of the upper charge air cooler unit,
and the lower charge air cooler unit is disposed in overlapping
relationship and adjacent to the lower end of the radiator with the
upper and lower ends of the lower charge air cooler unit being
oriented in the same direction as the upper and lower ends of the
radiator, wherein the other face at the lower end of the radiator
is disposed adjacent one face of the lower charge air cooler unit.
Each charge air cooler unit has a different core style selected
from the group consisting of core depth, type of fins, fin spacing,
fin count, tube spacing and tube count. The charge air cooler units
are operatively connected such that the charge air may flow
therebetween. The method includes flowing the engine coolant
through the radiator to cool the engine coolant, flowing the charge
air from the turbo- or supercharger in sequence through the charge
air heat exchanger units to cool the charge air, and flowing
cooling air through the heat exchanger assembly such that the
cooling air flows in series through the upper end of the radiator
and the upper charge air cooler unit, and the cooling air flows in
series through the lower charge air cooler unit and the lower end
of the radiator. At least one of the charge air cooler units may
include cooling for recirculated exhaust gas.
[0025] In yet another aspect, the present invention provides a
method and apparatus for cooling engine coolant and charge air from
a turbo- or supercharger in an internal combustion engine
comprising providing a radiator having upper and lower units for
cooling engine coolant, with each radiator unit having opposite
front and rear core faces through which ambient cooling air flows,
a depth between the front and rear faces, and opposite upper and
lower ends adjacent the faces. The radiator units are operatively
connected such that the engine coolant may flow therebetween. There
is also provided a charge air cooler having upper and lower units
for cooling charge air, with each charge air cooler unit having
opposite front and rear core faces through which cooling air may
flow, and opposite upper and lower ends adjacent the faces. The
upper charge air cooler unit is disposed in overlapping
relationship and adjacent to the upper radiator unit with the upper
and lower ends of the upper charge air cooler unit, wherein one
face of the upper radiator unit is disposed adjacent one face of
the upper charge air cooler unit, and the lower charge air cooler
unit is disposed in overlapping relationship and adjacent to the
lower radiator unit, wherein the other face of the lower radiator
unit is disposed adjacent one face of the lower charge air cooler
unit. Each charge air cooler unit has a different core style
selected from the group consisting of core depth, type of fins, fin
spacing, fin count, tube spacing and tube count. The charge air
cooler units are operatively connected such that the charge air may
flow therebetween. The method then includes flowing the engine
coolant in sequence through the radiator units to cool the engine
coolant, flowing the charge air from the turbo- or supercharger in
sequence through the charge air heat exchanger units to cool the
charge air, and flowing cooling air through the heat exchanger
assembly such that the cooling air flows in series through the
upper radiator unit and the upper charge air cooler unit, and the
cooling air flows in series through the lower charge air cooler
unit and the lower radiator unit. At least one of the charge air
cooler units may include cooling for recirculated exhaust gas. Each
radiator unit may have a different core style.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The features of the invention believed to be novel and the
elements characteristic of the invention are set forth with
particularity in the appended claims. The figures are for
illustration purposes only and are not drawn to scale. The
invention itself, however, both as to organization and method of
operation, may best be understood by reference to the detailed
description which follows taken in conjunction with the
accompanying drawings in which:
[0027] FIG. 1 is a partially schematic view of a prior art internal
combustion engine cooling system.
[0028] FIG. 2 is a partially schematic view of another prior art
internal combustion engine cooling system showing in side
elevational view the relative placement of a combined exhaust gas
and charge air cooler with respect to the radiator.
[0029] FIG. 3 is a graphical depiction of percent of maximum heat
transfer as a function of number of rows of tubes in a single heat
exchanger core.
[0030] FIG. 4 is a partially schematic view of one embodiment of
the internal combustion engine cooling system of the present
invention showing in side elevational view the relative placement
of exhaust gas and charge air coolers with respect to the
radiator.
[0031] FIG. 5 is a perspective view of the charge air cooler and
EGR gas cooler used in some embodiments of the internal combustion
engine cooling system of the present invention. FIG. 5a is a
modification of FIG. 5, and shows different core depths, different
tube spacing and different tube count for the charge air cooler and
EGR cooler.
[0032] FIG. 6 is a partially schematic view of another embodiment
of the internal combustion engine cooling system of the present
invention showing in side elevational view the relative placement
of an exhaust gas cooler and a charge air cooler with respect to
the radiator.
[0033] FIG. 7 is a side elevational view of a modification of the
radiator/charge air cooler and exhaust gas cooler package of FIG.
6, where the radiator is split into two units, and the entire
package is two cores deep.
[0034] FIG. 8 is a partially schematic view of a further embodiment
of the internal combustion engine cooling system of the present
invention showing in side elevational view the relative placement
of combined exhaust gas and charge air coolers with respect to the
radiator.
[0035] FIG. 9 is a side elevational view of a modification of the
radiator/charge air cooler and exhaust gas cooler package of FIG.
8, where the radiator is split into two units, and the entire
package is two cores deep.
[0036] FIG. 10 is a sectional plan view of portions of the cores of
the upper and lower combined EGR/CAC radiator units of FIG. 9
showing differences in tube spacing, tube minor diameter and core
depth.
[0037] FIG. 11 is a sectional elevational view of portions of the
cores of the upper and lower combined EGR/CAC radiator units of
FIG. 9 showing differences in fin count, fin thickness and fin
louver angle.
[0038] FIG. 12 is a partially schematic view of yet another
embodiment of the internal combustion engine cooling system of the
present invention showing in side elevational view the relative
placement of exhaust gas and charge air coolers with respect to the
radiator.
[0039] FIG. 13 is a side elevational view of a modification of the
radiator/charge air cooler and exhaust gas cooler package of FIG.
12, where the radiator is split into two units, and the entire
package is two cores deep.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)
[0040] In describing the preferred embodiments of the present
invention, reference will be made herein to FIGS. 3-13 of the
drawings in which like numerals refer to like features of the
invention.
[0041] The management of airflow through an air cooled heat
exchanger or packaged group of heat exchangers is important to the
heat transfer performance of the heat exchanger unit or package.
The development of airflow paths that optimize temperature
potential is vital in the design of space-saving cooling systems
within the constraints of typical fan/shroud arrangements in
heavy-duty trucks.
[0042] Before considering airflow in the EGR/CAC/radiator heat
exchanger packages disclosed herein, it is useful to examine
airflow in a single core heat exchanger. FIG. 3 depicts the
relationship of heat transfer as a function of number of rows of
tubes in a heat exchanger core. A vehicle radiator having only one
row of core tubes is initially assumed, wherein the depth in the
direction of airflow is 0.50 in. (13 mm). If the tube spacing
across the face of the core is about 0.44 in. (11 mm) and the fin
spacing is about 14 fins per in. (5.5 fins/cm), then the airflow
through the core, caused either by the action of a fan or by ram
air as a result of vehicle motion, will be reasonably high. If
increased heat transfer performance is desired, a radiator with an
additional row of tubes may be used, making the core two rows deep.
The cooling airflow will decrease slightly because of the added
resistance of the deeper core, but the overall heat transfer will
be greatly increased. However, as illustrated in FIG. 3, as the
core is made even deeper, to three, four, five and six rows deep,
cooling air flow is greatly reduced, to the point where adding
another row will result in decreased, rather than increased, heat
transfer performance. This occurs because with the low airflow and
deep core, the cooling air reaching the last row of tubes is
already heated to the point where it is ineffective in creating
further cooling. In such a case, improved performance can be
achieved by reducing the core depth to manage, or increase, the
cooling airflow, and by other methods and means, discussed further
below.
[0043] The internal combustion engine cooling system of the present
invention achieves cooling of the charge air and the recirculated
exhaust gas to near ambient temperatures, but permits the use of
lower cost materials overall. FIG. 4 shows a first embodiment of
the cooling system in which the air-cooled stainless steel or other
high temperature-resistant exhaust gas cooler is separate from, and
in parallel with, an aluminum charge air cooler, with respect to
the cooling ambient air flow. As used herein, the term "ambient
air" includes all of the cooling air as it passes through the
radiator, exhaust gas cooler and charge air cooler heat exchanger
units, even though it is heated as it passes through the fins of
the heat exchanger units. Instead of combining the hot exhaust gas
from EGR valve 48 with the heated charge air, or separately cooling
the heated exhaust gas utilizing the liquid engine coolant, the
heated exhaust gas passes through line 56 to an air-to-air exhaust
gas heat exchanger 70 for cooling. The term "line" as used herein
is intended to include hoses, tubing, piping and the like typically
used to carry fluids in an internal combustion engine environment,
such as the exhaust gas, charge air and liquid coolant described
herein. Exhaust gas cooler 70 is disposed upstream of radiator 22
and receives inlet ambient cooling air 60. Radiator 22 is typically
a down flow type radiator, wherein engine coolant enters through an
upper manifold extending substantially the entire width of the
radiator, is then distributed in the core through vertical,
downwardly extending tubes connected by cooling fins, so that
ambient cooling air may flow from the front face 23a of the core
through and out of the rear face 23b. After being cooled by the
ambient air, the coolant then collects in an attached lower
manifold also extending across the width of the radiator.
Alternatively, the radiator may be an up-flow type radiator, with
coolant flow in the opposite direction, or a cross flow type
radiator with coolant flow through core tubes extending
horizontally between horizontally opposed manifolds.
[0044] In parallel with and above exhaust gas cooler 70, and also
in front of and in series with radiator 22 with respect to the
ambient air flow, charge air cooler heat exchanger 80 receives the
heated, compressed charge air through line 42, where it is also
cooled by ambient air 60 entering through the CAC/EGR cooler front
face 77a. As a result, ambient air 60a exiting from the CAC/EGR
cooler rear face 77b is heated by both the exhaust gas and charge
air coolers before it passes through radiator 22, where it is
further heated and exits 60b from the radiator. The cooled exhaust
gas exits exhaust gas cooler 70 through line 58, and the cooled
charge air exits charge air cooler 80 through line 44. The cooled
charge air then combines with the cooled exhaust gas and passes
through line 46 to engine intake manifold 21. Alternatively, the
EGR cooler 70 and CAC 80 may be disposed on the opposite side of
radiator 22, i.e., downstream of the radiator with respect to the
ambient air flow.
[0045] In this embodiment, the recirculated exhaust gas and the
charge air are combined after the charge air cooler, rather than
before it as in the prior art system of FIG. 2. This system and
method avoid having to make a combination exhaust gas and charge
air cooler entirely out of stainless steel or other high
temperature-resistant material. Instead, while the exhaust gas
cooler is still made of stainless steel or the like, the charge air
cooler may be made of aluminum.
[0046] The radiator, CAC and EGR cooler shown in the embodiment of
FIG. 4 (as well as in the subsequent embodiments described below)
are preferably secured to each other to create a combined heat
exchanger package. The air-to-air heat exchanger units used for the
exhaust gas cooler 70 and charge air cooler 80 are shown in more
detail in FIG. 5. Charge air cooler 80 includes upper and lower
horizontally extending manifolds 81, 82 respectively, which
distribute or collect the charge air passing through spaced,
vertically extending tubes 83 connecting the manifolds. These tubes
may be two (2) rows deep, as shown in FIG. 5, or any other
configuration, to achieve desired core depth d.sub.1. A serpentine
cooling fin array 84 (also of depth d.sub.1) between adjacent tubes
83 extending across the face of charge air cooler 80 comprises the
charge air cooler core, which transfers the heat from the charge
air within the tubes to the ambient air passing between the tubes
83 and over the fins 84. The vertical spacing between the
serpentine fins determines the desired fin count. The fins may be
of the louvered, lanced-offset, wavy (non-louvered) or other type,
or plate fins may be used instead. The manifolds have openings 85,
86 for passage of charge air into or out of the manifolds. The CAC
may be configured as an upflow unit, where heated charge air is
received in inlet 86 of manifold 82 where it passes upward through
tubes 83 and from manifold 81 through outlet 85 as cooled charge
air. Alternatively, the CAC may be configured as a downflow unit,
where the heated charge air flow is received in inlet 85 and flows
in a reverse direction out through outlet 86 as cooled charge
air.
[0047] In a construction analogous to that of the charge air
cooler, exhaust gas cooler 70 has upper and lower manifolds 71 and
72, with the former having inlet/outlet 75 and the latter having
inlet/outlet 76. Tubes 73 carry the exhaust gas between manifolds
71 and 72, and fins 74 between adjacent tubes 73 permit passage of
the cooling ambient air therebetween to cool the hot exhaust gases
passing within tube 73. The core has depth d.sub.2, and tubes 73
and fins 74 may be modified as described in connection with CAC 80.
As with the charge air cooler, EGR cooler 70 may be set up as a
downflow unit, so that the hot exhaust gases are passed through
inlet 75 downward through the tubes and cooled exhaust gas passes
outward through outlet 76, or as an upflow unit where the exhaust
gas travels in the reverse direction.
[0048] As shown in FIG. 5, both exhaust gas cooler 70 and charge
air cooler 80 have a horizontal width, measured in the direction of
the manifolds, which is greater than the vertical height of each of
the units, measured between the manifolds. Improved heat exchanger
performance as a result of reduced charge air pressure drop, may be
obtained by utilizing tubes which are as short as possible and as
numerous as possible, given the configuration of the heat exchanger
units. As shown in this embodiment, both the exhaust gas and charge
air coolers employ tubes which are oriented with the shorter
vertical height of each of the units so that there is a larger
number of shorter tubes. Alternatively, both the exhaust gas and
charge air coolers may be cross-flow units with exhaust gas flow
through horizontally oriented tubes extending between vertically
oriented manifolds on either side of the charge air cooler.
[0049] Preferably, charge air cooler 80 and exhaust gas cooler 70
are sized so that their respective widths w.sub.1 and w.sub.2 are
each the same as the width of the radiator with which they are
packaged. Preferably, CAC 80 and EGR cooler 70 are connected to
each other, as indicated by the arrows, to create a single unit
that is positioned adjacent to the radiator. The combined heights
of the charge air cooler 80 and EGR cooler 70, h.sub.1 and h.sub.2
respectively, may be up to the height of the radiator. Typically,
the height h.sub.1 of the charge air cooler is greater than the
height h.sub.2 of the exhaust gas cooler 70 when there are greater
cooling requirements for the charge air versus the recirculated
exhaust gas.
[0050] In addition to modifying the heights and widths of the CAC
and EGR coolers, the cores of each may be modified as desired to
achieve the desired thermal cooling properties for the combined
radiator/CAC/EGR cooler package. For example, the core depths, the
type of fins, the fin spacing and count, and the tube spacing and
count for each CAC and EGR cooler may be the same as or different
from other CAC and EGR coolers in the package. FIG. 5a is a
modification of FIG. 5, and shows different core depths d.sub.1',
d.sub.2', and different tube spacing and different tube count
across the widths w.sub.1 and w.sub.2 of the CAC unit 80 and EGR
cooler unit 70, respectively.
[0051] The manifolds, tubes and fins of charge air cooler 80 may be
made of aluminum, either as a conventional fully brazed CAC or with
brazed tubes and fins and grommeted tube-to-header joints. The
latter is disclosed in U.S. Pat. Nos. 5,894,649, 6,330,747 and
6,719,037, the disclosures of which are hereby incorporated by
reference. Because the exhaust gases to be cooled are considerably
hotter than the charge air to be cooled by charge air cooler 80,
exhaust gas cooler 70 is preferably not made of aluminum, and
instead the manifolds, tubes and fins are made of stainless steel
or other high temperature-resistant material for additional heat
resistance and product life. Since only the portion of the heat
exchanger package used to cool the exhaust gas is made of stainless
steel or the like, the cost of the combined exhaust gas cooler 70
and charge air cooler 80 is less, since the charge air cooler
portion is made of lower cost aluminum.
[0052] FIG. 6 depicts another embodiment of the cooling system of
the present invention. Instead of combining the exhaust gas cooler
with the charge air cooler in a common unit adjacent the same face
of the radiator, exhaust gas cooler 70 is placed adjacent the face
of the radiator opposite the charge air cooler, which is disposed
near the upper end of the radiator. As with the previous
embodiment, charge air cooler 80 is disposed upstream of radiator
22 so that ambient air 60 passes through front face 87a and out of
rear face 87b as partially heated ambient air 60a. The height of
the charge air cooler 80 is less than that of radiator 22, so that
a portion of radiator 22 (here shown as the lower portion) receives
ambient air 60 which does not pass through the charge air cooler.
The remaining portions of the radiator 22 receive ambient air 60a
which has been heated partially by passage in series through charge
air cooler 80. Disposed downstream of radiator 22 is exhaust gas
cooler 70, here shown disposed adjacent to the lower portion of the
radiator 22 which receives the unheated ambient air 60. The ambient
air 60b partially heated after passage through rear face 23b of
radiator 22 then passes in series through the front face 77a and
the fins and tubes of exhaust gas cooler 70, and exits 60c at a
higher temperature from rear face 77b. However, the difference in
temperature between the exhaust gas and the heated cooling air 60b
is still sufficient to allow good heat transfer. The cooled exhaust
gas exits the cooler 70 and passes through line 58 where it
combines with the cooled charge air in line 44. The combined
mixture then passes through line 46 into engine intake manifold
21.
[0053] The height h.sub.1 of charge air cooler 80 and the height
h.sub.2 of exhaust gas cooler 70 are preferably selected so that
the combined height h.sub.1+h.sub.2 is approximately equal to the
height of radiator 22, and the two coolers 70, 80 do not overlap
with each other. Placing the exhaust gas cooler behind the radiator
in this embodiment improves the radiator cooling performance by
avoiding heating of the radiator by the exhaust gas cooler. As with
the previous embodiment, exhaust gas cooler 70 is made of stainless
steel or other high temperature-resistant material and the charge
air cooler 80 is made of lower cost aluminum.
[0054] A modification of the embodiment of FIG. 6 is shown in FIG.
7, where charge air cooler 80 and exhaust gas cooler 70 are the
same, but the radiator is split into two different portions or
units, upper rear unit 22a and lower front unit 22b, in a manner
similar to that shown in U.S. Patent Publication No.
US2005-0109484-A1, the disclosure of which is hereby incorporated
by reference. In the front (with respect to ambient air flow 60),
charge air cooler 80 is above and has front and rear faces
substantially planar with those of lower radiator unit 22b, and in
the rear exhaust gas cooler 70 is below and has front and rear
faces substantially planar with those of upper radiator unit 22a.
Variations in core depth in the individual units may change the
planar alignment slightly. The heights and widths of upper radiator
unit 22a and charge air cooler 80 are substantially the same, as
are the heights and widths of lower radiator unit 22b and exhaust
gas cooler 70. Each radiator unit 22a, 22b has a construction
similar to the full radiator previously described above, but with
shorter height. As in the case of the CAC and EGR coolers described
in FIG. 5, the core of each unit 22a, 22b may be varied in depth,
type of fins, fin spacing and count, and tube spacing and count,
compared to the other, to achieve the desired balance of thermal
cooling properties in the package. An additional line 62a passes
partially cooled engine coolant from upper unit 22a to lower unit
22b. The modification in FIG. 7 results in a combined
radiator/CAC/EGR cooler package that is only two cores deep, as
opposed to the three core deep package of FIG. 6. This saving in
core depth has benefits in that fan 90 exhausting the heated
ambient air 60d may be spaced farther back from the rear core face,
and thereby provide for higher air flow and better air flow
distribution over the entire core face of the heat exchanger
package.
[0055] A further embodiment of the present invention is depicted in
FIG. 8. Instead of cooling the exhaust gas and heated charge air in
separate heat exchangers, the heated exhaust gas from line 56 is
combined with the heated charge air exiting the compressor in line
41, and the mixture of heated exhaust gas and charge air passes
through line 43 to first combined exhaust gas and charge air cooler
80a. Combined exhaust gas and charge air cooler 80a is disposed
downstream of radiator 22, in a location corresponding to the lower
portion of the radiator 22 that receives fresh ambient cooling air
60 through front face 23a. After ambient air 60 passes through the
radiator rear face 23b and exits as partially heated ambient air
60b, it then passes in series through the front face 87a and the
fins and tubes of the combined cooler 80a and exits as heated
ambient air 60c from the rear face 87b. The combined cooler 80a is
constructed in a manner similar to charge air cooler 80 shown in
FIG. 5, except that it is made of stainless steel or other high
temperature-resistant material instead of aluminum since it is
carrying gases at a higher temperature.
[0056] As it exits cooler 80a, the combined exhaust gas and charge
air is partially cooled. It then travels through line 69 where it
then enters a second combined exhaust gas and charge air cooler
80b, disposed upstream of radiator 22. Combined cooler 80b is shown
adjacent the front face 23a, near the upper portion of radiator 22
so that it does not overlap with the first combined cooler 80A
adjacent the rear face 23b, near the lower portion of radiator 22.
The partially cooled combined exhaust gas and charge air is then
subject to maximum cooling by ambient air 60, which passes through
the front face 87a and the tubes and fins of cooler 80b, and exits
rear face 87b as heated ambient air 60a to cool radiator 22 in
series. The arrangement of this split exhaust gas and charge air
cooler is similar to that of the split charge air cooler disclosed
in U.S. Patent Publication No. US2005-0109483-A1, the disclosure of
which is hereby incorporated by reference. The cooled combined
exhaust gas and charge air then exits cooler 80b through line 45 to
intake manifold 21. Since the combined exhaust gas and charge air
received in cooler 80b is already partially cooled, cooler 80b does
not need to be made of stainless steel or other high
temperature-resistant material, and can be made of aluminum.
Preferably, heights and locations of coolers 80a and 80b are
selected so that they do not overlap with one another, and their
combined heights are approximately equal to the height of radiator
22. Additionally, the core styles, i.e., the core depth, the type
of fins, the fin spacing and count, and the tube spacing and count,
may be varied and tailored for each unit 80a, 80b, to obtain the
desired air flow split and unit performance. For example, the front
unit 80b may have a lower fin count and/or core depth (the latter
shown by the reduced core depth of front face 87a') to limit the
heating of the ambient air that passes through the core of the
radiator, whereas the rear unit 80a may have a higher fin count
and/or core depth (the latter shown by the increased core depth of
rear face 87b') to derive maximum cooling of the combined exhaust
gas and charge air. Effects of variation in core parameters are
discussed further below. This system and method provides maximum
heat transfer performance with material cost savings over the prior
art system and method of FIG. 2 because at least half of the
combined exhaust gas and charge air cooler can be made with the
lower cost aluminum construction.
[0057] FIG. 9 shows a modification of the embodiment of FIG. 8. In
a manner similar to the modification of FIG. 7, the radiator is
split into two units 22a, 22b, with connecting line 62a, so that
the combined radiator/CAC/EGR cooler package is only two cores deep
with respect to ambient air flow 60. Again, the front and rear
faces of the vertically matched units 80b, 22b and 22a, 80a,
respectively, are in substantially the same planes (except for any
variations in core depth in the individual units) and the heights
and widths of the horizontally matched units, 22a, 80b and 80a,
22b, respectively, are substantially the same. This again saves
space and permits more optimal mounting of fan 90 for better flow
through the package of the cooling ambient air.
[0058] In a packaged group of heat exchangers, as depicted in FIGS.
4, 6, 7, 8 and 9, it is particularly important to manage the
airflow splits among the various heat exchangers in order to
achieve optimum heat transfer performance. In a package with split
radiator and split charge air cooler as shown in FIG. 9, it may be
desirable, in order to achieve optimum radiator performance, to
manage the cooling airflow through the front charge air cooler by
lowering its core resistance. This will result in the minimum
impact of the front charge air cooler upon the radiator core
behind, and will provide optimized cooling airflow to the radiator,
resulting in optimum radiator heat transfer.
[0059] The flow of cooling air through a heat exchanger core, for
example the cores of radiator units 22a, 22b and charge air cooler
units 80a, 80b, may be managed in a number of different ways, each
affecting the core airflow resistance or the airflow resistance of
the entire airflow path. For example, airflow through a given heat
exchanger may be increased by increasing the core resistance of a
heat exchanger in parallel with it or by decreasing its own core
resistance or the core resistance of a heat exchanger in series
with it. Various core parameters may be varied in any of the heat
exchangers of FIGS. 4, 6, 7, 8 and 9 to achieve a fin/tube system
with the desired cooling airflow resistance.
[0060] As described above in connection with FIG. 9, and as shown
in FIG. 10 where the cores of the upper and lower combined EGR/CAC
units are juxtaposed for comparison, a decreased depth d of the
core of upper combined exhaust gas and charge air cooler unit 80b
(in front of the upper radiator unit) decreases core resistance and
increases cooling airflow, while increased core depth D of lower
combined exhaust gas and charge air cooler unit 80a (behind the
lower radiator unit) increases core resistance and decreases
cooling airflow. Also, increased CAC tube 83 spacing S and smaller
CAC tube 83 minor diameter m on unit 80b (both measured in a
direction across the face of the core) decrease core resistance and
increase cooling airflow, whereas decreased tube spacing s and
increased tube minor diameter M on unit 80a increase core
resistance and decrease cooling airflow. Variations to the core
fins also affect cooling airflow resistance. For example, as shown
in FIG. 11 with the cores of EGR/CAC units 80a and 80b again
juxtaposed, increased fin 73a count per unit vertical distance C,
increased fin louver 73a' angles A and increased fin thickness T on
unit 80a increase core resistance and decrease cooling airflow, as
compared to the decreased fin 73b count per unit vertical distance
c, decreased fin louver 73b' angles a and decreased fin thickness t
on unit 80b. The use of louvered fins 73a', 73b' increases core
resistance and decreases cooling airflow as compared to flat,
dimpled or wavy style fins.
[0061] Each radiator unit 22a, 22b in FIG. 9 likewise may have
different core styles, such as core depth, type of fins, fin
spacing, fin count, tube spacing and tube count, in the same manner
as described in connection with the EGR/CAC units.
[0062] The core area of the EGR, CAC and radiator cores has a
direct effect on airflow management, but in a much more complex
manner than the items mentioned above. In the embodiment shown in
FIG. 9, the charge air cooler core areas may be the same as the
radiator core areas, i.e., be fully overlapping with respect to
cooling air flow. On the other hand, the charge air cooler cores
may extend beyond the radiator core areas in one or more
directions, i.e., be overhanging or non-overlapping with respect to
cooling air flow, or the radiator core areas may extend beyond
those of the charge air coolers in any direction. The airflow
resistance of a given core is inversely proportional to its area.
However, the greater the area of a heat exchanger which is
overlapped by another heat exchanger, the greater will be the
airflow resistance of the two heat exchangers. Increased
overlapping results in increased airflow resistance and increased
overhanging results in decreased airflow resistance through the
heat exchangers in the package.
[0063] It has been found that the static head loss through the heat
exchanger package along each airflow path is equivalent. Thus, face
velocities that drive convection increase or decrease to achieve
this balance. The split radiator and charge air cooler
configurations having multiple different fin/tube systems provide
the flexibility to modify air velocities for best results.
Optimized application-specific results may be obtained not only
through heat exchanger core arrangements, but also through use of
different fin/tube systems in each heat exchanger unit.
[0064] A further embodiment of the present invention which combines
some of the characteristics of previous embodiments is depicted in
FIG. 12. In a manner similar to the embodiment of FIG. 4, the
exhaust gas and heated charge air are not combined, but are instead
cooled in connected parallel heat exchangers located adjacent to
the radiator. However, in a manner similar to that of the
embodiment of FIG. 8, the heat exchangers for each of the exhaust
gas and charge air are split into units downstream and upstream of
radiator 22. Recirculated exhaust gas from line 56 is first cooled
in exhaust gas cooler 70' downstream of radiator 22, and,
separately, heated charge air from line 42 is first cooled in
charge air cooler 80', in parallel with cooler 70' and also
downstream of the radiator. The downstream exhaust gas and charge
air coolers 70' and 80', respectively, are connected to form a
single unit like that shown in FIG. 5, except that they are
inverted, so that the exhaust gas cooler portion is above the
charge air cooler portion. As with the previous description of the
embodiment of FIG. 5, the exhaust gas cooler 70' is made of
stainless steel or other high temperature-resistant material, since
it receives the hotter exhaust gas, and the charge air cooler unit
80' is made of aluminum. The exhaust gas cooler 70' and charge air
cooler unit 80' are located along the lower portion adjacent to and
downstream of rear face 23b of radiator 22, corresponding to the
region in which radiator 22 receives unheated ambient air 60. The
partially heated ambient air 60b from the lower portion of radiator
22 passes in series through front face 77a and the tubes and fins
of both exhaust gas cooler 70' and charge air cooler 80', and exits
as further heated ambient air 60c from the rear face 77b of coolers
70'/80'.
[0065] The partially cooled exhaust gas then exits exhaust gas
cooler 70' through line 69a, where it enters the inlet of second,
upstream exhaust gas cooler 70''. The partially cooled charge air
exits downstream charge air cooler 80' and travels through line 69b
to the inlet of second, upstream charge air cooler 80''. Ambient
air 60 passes through the front face 77a of both coolers 70'' and
80'', located adjacent the upper portion of the radiator, to
respectively cool the exhaust gas and charge air. The partially
heated ambient air 60a then exits the rear face 77b of coolers
70''/80'' and passes in series through the front face 23a at the
upper portion of radiator 22. The cooled exhaust gas then exits
from exhaust gas cooler 70'' through line 58, and the cooled charge
air exits from charge air cooler 80'' through line 44, and are
combined and passed through line 46 to engine intake manifold
21.
[0066] The upstream exhaust gas cooler 70'' and charge air cooler
80'' are also constructed in connected parallel units 70''/80''
similar to that shown in FIG. 5, except inverted. However, since
the exhaust gas is already partially cooled, it does not have an
excessively high temperature. Therefore, the upstream exhaust gas
cooler 70' need not be made of stainless steel or other high
temperature-resistant material, and may be constructed of aluminum,
similar to that of charge air cooler 80''. The location and
combined height of the downstream exhaust gas and charge air
coolers 70'/80' and the location and combined height of the
upstream exhaust gas and charge air coolers 70''/80'' are selected
so that the downstream and upstream connected units do not overlap
with one another, and so that the sum of the combined heights of
the units is approximately equal to the height of the radiator. As
with the other embodiments previously described, core styles such
as core depth, type of fins, fin spacing and count, and tube
spacing and count may be varied and tailored for each unit 70',
70'', 80', 80'', to obtain the desired heat transfer
performance.
[0067] In a modification similar to those of FIGS. 7 and 9, FIG. 13
shows a modification of the embodiment of FIG. 12 in which the
radiator is again split into two units 22a, 22b, connected by line
62a, so that the combined radiator/CAC/EGR cooler package is only
two cores deep to reduce package space and improve ambient air flow
by fan 90. The front and rear faces of the vertically matched units
70'', 80'', 22b and 22a, 70', 80', respectively, are in the
substantially the same planes, except for any variations in core
depth. The heights and widths of the horizontally matched units,
22a, 70''/80'' and 70'/80', 22b, respectively, are substantially
the same.
[0068] In this system and method shown in FIGS. 12 and 13, only the
first exhaust gas cooler 70' need be made of stainless steel or
other high temperature-resistant material, while the other three
coolers 70'', 80' and 80'' can all be made of lower cost aluminum
construction, thus resulting in material cost savings. The heat
transfer performance of this system and method will be
substantially the same as that of FIGS. 8 and 9 and far superior to
the prior art system and method shown in FIG. 2. As with the
embodiments shown in FIGS. 4, 6, 7, 8 and 9, the core, tube and fin
parameters of the radiator and connected EGR/CAC units in FIGS. 12
and 13 may be varied to modify the air flow as desired through the
individual heat exchanger units.
[0069] Additionally, the direction of flow of engine coolant
through the radiator unit(s), and/or the direction of flow of the
exhaust gas and charge air through the ERG/CAC units, may be
reversed as desired to achieve desired thermal performance. For
example, in the embodiments of FIGS. 9 and 12, the combined EGR/CAC
air flow may be reversed, so that all of the radiator and combined
EGR/CAC units are downflow units.
[0070] Cooling air flow through any of the heat exchanger packages
shown in FIGS. 4, 6, 7, 8, 9, 12 and 13 may be increased by the use
of a fan shroud 88 (FIG. 13) enclosing the area between fan 90 and
the heat exchangers, and by moving fan 90 away from the rear face
of the heat exchangers so that fan penetration into the enclosure
results in optimized static efficiency. Here, orifice condition on
the shroud as well as the static head loss presented to the fan
along each airflow path of the cooling system determines total
airflow. In this manner there can be presented to the fan a uniform
or non-uniform resistance to airflow to create airflow splits that
optimize cooling air approach differential and maximize temperature
potential where needed to achieve system performance requirements.
While it is difficult to achieve this in crowded vehicle engine
compartments, the heat exchanger packages of the present invention
facilitate this goal. In particular the split radiator/split charge
air cooler heat exchanger packages of FIGS. 9 and 13 provide
significant improvement since they are only two cores deep as
opposed to single radiator/split charge air cooler arrangements,
which are three cores deep. In addition, splitting the CAC and
radiator, with the use of multiple fin/tube systems, provides a
high degree of flexibility in creating airflow splits that can be
customized to meet the needs of each individual application.
[0071] Thus, the present invention provides an improved system and
method of cooling an internal combustion engine, including charge
air cooling and exhaust gas cooling, which achieves cooling of the
charge air and the recirculated exhaust gas to near ambient
temperatures, and which allows the use of lower cost materials for
the charge air and exhaust gas coolers. Improved space saving
packaging may be achieved by splitting the radiator and packaging
the combined radiator, CAC and EGR cooler only two cores deep.
Additionally, modifications to the core may be made to any
individual heat exchanger unit within the package to best tailor
thermal performance.
[0072] While the present invention has been particularly described,
in conjunction with a specific preferred embodiment, it is evident
that many alternatives, modifications and variations will be
apparent to those skilled in the art in light of the foregoing
description. It is therefore contemplated that the appended claims
will embrace any such alternatives, modifications and variations as
falling within the true scope and spirit of the present
invention.
* * * * *