U.S. patent application number 11/860680 was filed with the patent office on 2009-03-26 for cooling system with isolated cooling circuits.
This patent application is currently assigned to FORD GLOBAL TECHNOLOGIES, LLC. Invention is credited to Peter Kanefsky, Robert Hornblower Meyer, Mark A. Pellerin, Roger Rose, William Charles Ruona.
Application Number | 20090078220 11/860680 |
Document ID | / |
Family ID | 39889038 |
Filed Date | 2009-03-26 |
United States Patent
Application |
20090078220 |
Kind Code |
A1 |
Meyer; Robert Hornblower ;
et al. |
March 26, 2009 |
Cooling System with Isolated Cooling Circuits
Abstract
A cooling system for an internal combustion engine, comprising a
first, high temperature, cooling circuit coupled to an engine for
cooling the engine, where a first coolant circulates in the first
circuit; and a second, low temperature, cooling circuit coupled to
a plurality of devices for cooling the plurality of devices, where
a second coolant circulates in the second circuit, the second
cooling circuit includes a plurality of radiator segments, the
coolant circulating in the second cooling circuit may exit at
different radiator segments of the plurality of radiator segments
producing coolant streams of different cooling temperatures for
cooling different devices of the plurality of devices.
Inventors: |
Meyer; Robert Hornblower;
(West Bloomfield, MI) ; Rose; Roger; (New
Baltimore, MI) ; Pellerin; Mark A.; (Saline, MI)
; Kanefsky; Peter; (West Bloomfield, MI) ; Ruona;
William Charles; (Farmington Hills, MI) |
Correspondence
Address: |
ALLEMAN HALL MCCOY RUSSELL & TUTTLE, LLP
806 S.W. BROADWAY, SUITE 600
PORTLAND
OR
97205
US
|
Assignee: |
FORD GLOBAL TECHNOLOGIES,
LLC
Dearborn
MI
|
Family ID: |
39889038 |
Appl. No.: |
11/860680 |
Filed: |
September 25, 2007 |
Current U.S.
Class: |
123/41.31 ;
165/104.19; 165/148 |
Current CPC
Class: |
F01P 3/20 20130101; F01P
7/165 20130101 |
Class at
Publication: |
123/41.31 ;
165/104.19; 165/148 |
International
Class: |
F01P 3/12 20060101
F01P003/12; F28D 1/00 20060101 F28D001/00 |
Claims
1. A cooling system for an internal combustion engine, comprising a
first, high temperature, cooling circuit coupled to an engine for
cooling the engine, where a first coolant circulates in the first
circuit; and a second, low temperature, cooling circuit coupled to
a plurality of devices for cooling the plurality of devices, where
a second coolant circulates in the second circuit, and where the
second cooling circuit includes a plurality of radiator segments,
the coolant circulating in the second cooling circuit exiting at
different radiator segments of the plurality of radiator segments
producing coolant streams of different cooling temperatures for
cooling different devices of the plurality of devices.
2. The cooling system of claim 1, wherein the plurality of radiator
segments are positioned in a path of a common stream of air
flow.
3. The cooling system for an internal combustion engine of claim 1,
wherein the coolant of the first cooling circuit does not mix with
the coolant of the second cooling circuit.
4. The cooling system according to claim 1, wherein the first
cooling circuit includes at least a radiator for cooling the
coolant circulating in the first cooling circuit.
5. The cooling system of claim 3, wherein the radiator of the first
cooling circuit is positioned in the path of an air flow downstream
from the plurality of radiator segments of the second cooling
circuit.
6. The cooling system of claim 1, wherein the plurality of radiator
segments of the second cooling circuit include at least two
radiator segments, where the coolant circulating in the second
cooling circuit exits at each of the two radiator segments to
produce coolant streams of two different temperatures.
7. The cooling system of claim 1, wherein the plurality of radiator
segments of the second cooling circuit includes at least three
radiator segments, where the coolant circulating in the second
cooling circuit exits at each of the three radiator segments to
produce coolant streams of three different temperatures.
8. The cooling system of claim 1, wherein the first cooling circuit
includes at least a coolant pump for circulating the coolant in the
first cooling circuit, and where the second cooling circuit
includes at least a coolant pump for circulating the coolant in the
second cooling circuit.
9. The cooling system of claim 8, wherein the coolant pump of the
second cooling circuit is positioned downstream of the devices and
upstream of the radiator segments, the coolant exiting the coolant
pump first traveling to the radiator segments and then to the
plurality of devices of the second cooling circuit.
10. The cooling system of claim 1, wherein the second cooling
circuit includes a bypass for allowing the coolant circulating in
the second cooling circuit to bypass the plurality of radiator
segments.
11. The cooling system of claim 1, wherein the first cooling
circuit cools a high temperature EGR cooler, and the second cooling
circuit cools a low temperature EGR cooler.
12. The cooling system of claim 1, wherein the second cooling
circuit includes a condenser positioned in a path of air flow.
13. The cooling system of claim 1, wherein the cooling system
includes a condenser positioned away from a path of air flow.
14. The cooling system of claim 1, wherein rates of coolant flow
passing through each of the plurality of devices of the second
cooling circuit are less than or equal to 15 grams per minute.
15. The cooling system of claim 1, wherein coolant flow rates of
the second cooling circuit are less than or equal to 6 grams per
minute.
16. A cooling system for an internal combustion engine, comprising
a first, high temperature, cooling circuit coupled to an engine and
an high temperature EGR cooler for cooling the engine and the high
temperature EGR cooler, where a first coolant circulates in the
first cooling circuit, the first cooling circuit includes a main
coolant pump for circulating the coolant in the first cooling
circuit and a main radiator for cooling the coolant circulating in
the first cooling circuit, the main coolant pump is positioned
downstream of the main radiator and upstream of the engine and the
high temperature EGR cooler in the path of the circulating coolant,
the engine and the high temperature EGR are arranged in parallel in
the path of the coolant circulating in the first cooling circuit
with respect to each other; a second, low temperature, cooling
circuit coupled to a plurality of devices for cooling the plurality
of devices, where a second coolant circulates in the second cooling
circuit, where the second cooling circuit includes an auxiliary
coolant pump and a condenser, where the second cooling circuit
includes three radiator segments: a warm temperature radiator, a
intermediate temperature radiator, and a low temperature radiator,
arranged successively in the path of the coolant circulating in the
second cooling circuit, where the low temperature radiator is
downstream of the intermediate temperature radiator, and the
intermediate temperature radiator is downstream of the warm
temperature radiator, where the circulating coolant of the second
cooling circuit exits the warm temperature radiator to form a first
a coolant stream with a first coolant temperature, exits the
intermediate temperature radiator to form a second coolant stream
with a second coolant temperature, exits the low temperature
radiator to form a third coolant stream with a third coolant
temperature, where the temperature of the first coolant stream is
higher than the temperature of the second coolant stream, and the
temperature of second coolant stream is higher than the temperature
of the third coolant stream, where the first coolant stream further
circulates to a transmission cooler to cool the transmission
cooler, the second coolant stream further circulates to a low
temperature EGR cooler to cool the low temperature EGR cooler, the
third coolant stream further circulates to a fuel cooler and a
charged air cooler to cool the fuel cooler and the charged air
cooler, where coolant exiting each of the plurality of devices of
the second cooling circuit circulates to the auxiliary coolant pump
before circulates further to the plurality of radiator segments,
and where the second cooling circuit includes a bypass for the
coolant circulating in the second coolant circuit to bypass the
plurality of radiator segments; where a common stream of air flow
flows pass the first condenser, the plurality of radiators of the
second cooling circuit, and the radiator of the first cooling
circuit, where the first condenser is upstream of the low
temperature radiator, the low temperature radiator is upstream of
the intermediate temperature radiator, the intermediate temperature
radiator is upstream of the warm temperature radiator, the warm
temperature radiator is upstream of the main radiator of the first
cooling circuit.
17. A method for cooling an internal combustion engine of a
vehicle, comprising: circulating coolant through a first cooling
circuit thermally coupled to combustion chambers of the engine, the
first cooling circuit including at least a radiator; circulating
coolant through a second cooling circuit thermally coupled to a
plurality of devices, the second cooling circuit including a
plurality of radiator segments, where the coolant is pumped via a
pump coupled upstream of a radiator and downstream of the devices,
where the coolant of the first cooling circuit does not mix with
coolant of the second cooling circuit; distributing coolant in the
second circuit to the plurality of devices at different
temperatures via the plurality of radiators in the second circuit;
and flowing a common stream of cooling air over at least the
radiator in the first cooling circuit and at least one of the
plurality of radiator segments in the second cooling circuit.
18. The method of claim 17 wherein the radiator of the first
cooling circuit and the plurality of radiator segments of the
second cooling circuit are positioned in a common stream of cooling
air, with the said radiator of the radiator of the first cooling
circuit downstream of the plurality of radiators; and the said
plurality of radiator segments positioned successively in the path
of the common stream of cooling air.
Description
BACKGROUND AND SUMMARY
[0001] Internal combustion engines, in particular heavy duty and
turbocharged diesel engines, may generate tremendous amounts of
heat during combustion under some conditions. To address
overheating of engine oil, cylinder walls, pistons, valves, and
other components, various cooling systems have been applied. In one
example system, WO 2005040574 provides a cooling system for an
internal combustion engine that includes a first flow circuit that
operates at a higher temperature and pressure range and serves to
cool the engine and vehicle cab, and a second circuit that operates
at a lower temperature and pressure range and primarily serves to
cool various components including the gearbox, EGR, and charge air.
The two flow circuits are interconnected via passages equipped with
various one-way valves that open in the direction of the first flow
circuit. The two cooling circuits allegedly reduce the likelihood
of cavitation caused by large pressure drops in the coolant
circuit.
[0002] However, such a system may not sufficiently address the
individual cooling temperature demands for various components in
the second, lower temperature, cooling circuit, since the radiator
of the low temperature flow circuit only cools the coolant
circulating in the low temperature flow circuit to a single
temperature.
[0003] To address the above mentioned issue, a cooling system for
an internal combustion engine may be used, the system comprising a
first, high temperature, cooling circuit coupled to an engine for
cooling the engine, where a first coolant circulates in the first
circuit; and a second, low temperature, cooling circuit coupled to
a plurality of devices for cooling the plurality of devices, where
a second coolant circulates in the second circuit, and where the
second cooling circuit includes a plurality of radiator segments,
the coolant circulating in the second cooling circuit exiting at
different radiator segments of the plurality of radiator segments
producing coolant streams of different cooling temperatures for
cooling different devices of the plurality of devices.
[0004] In this way, it may be possible to efficiently utilize two
cooling loops while also tailoring the cooling of a plurality of
devices in the low temperature circuit to the particular conditions
of each individual device. In this, operation and efficiency of the
individual devices may be improved. For example, heat exchangers
may be optimized for minimum size and fan power may be optimized to
accomplish the needed heat rejection and coolant temperatures.
[0005] In another example, a method for cooling an internal
combustion engine of a vehicle may be used. The method may comprise
circulating coolant through a first cooling circuit thermally
coupled to combustion chambers of the engine, the first cooling
circuit including at least a radiator; circulating coolant through
a second cooling circuit thermally coupled to a plurality of
devices, the second cooling circuit including a plurality of
radiator segments, where the coolant is pumped via a pump coupled
upstream of a radiator and downstream of the devices, where the
coolant of the first cooling circuit does not mix with coolant of
the second cooling circuit; distributing coolant in the second
circuit to the plurality of devices at different temperatures via
the plurality of radiators in the second circuit; and flowing a
common stream of cooling air over at least the radiator in the
first cooling circuit and at least one of the plurality of radiator
segments in the second cooling circuit
[0006] By optionally maintaining two separate cooling circuits
where the coolant streams do not mix, it may be possible to reduce
heat transfer between the two cooling circuits. Further, by
distributing coolant streams of different temperatures, as noted
above, it may be possible to individualize the coolant temperature
used for cooling a particular device, thereby improving cooling
efficiency and performance of the device. Further still, by
utilizing a common stream of cooling air over and to cool radiators
in both the first and second coolant circuits, a more compact
system design may be achieved. In addition, in the example of
including successive ordering of the plurality of radiator segments
in the second cooling circuit, it may be possible to further
increase efficiency of the second cooling circuit. Finally, by
pumping coolant in the second circuit via a pump coupled upstream
of a radiator (e.g., on the hotter side and downstream of the
various devices), it may be possible to utilize a single pump for
the lower temperature circuit that is able to provide multiple
coolant outlets with different coolant temperatures to serve the
various devices with different temperature requirements.
Alternatively, multiple pumps may also be used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 illustrates an embodiment of a cooling system for an
internal combustion engine.
DETAILED DESCRIPTION
[0008] FIG. 1 illustrates a cooling system for an internal
combustion engine, which includes two cooling circuits with their
coolant flows isolated from each other: a high temperature cooling
circuit 100 for primarily cooling the engine and a low temperature
cooling circuit 102 for cooling a multitude of devices or
components.
[0009] The high temperature cooling circuit 100 may include an
engine 104, a main pump 106 for circulating coolant in the high
temperature cooling circuit 100, a main radiator 108 for
dissipating the heat in the high temperature cooling circuit 100.
The high temperature cooling circuit 100 may further include a high
temperature exhaust gas recirculation (EGR) cooler 110 for cooling
the EGR.
[0010] Coolant lines for circulating the coolant among the various
components of the high temperature cooling circuit 100 may be
provided. In this example, the coolant is shown to circulate from
the main radiator 108 to the main pump 106 via a coolant line 112a,
further to the engine 104 via a coolant line 112b, then back to a
main radiator 108 via a coolant line 112c. In addition, the coolant
may also circulate from the main pump 106 to the high temperature
EGR cooler 110 via a coolant line 112d, and further to the main
radiator 108 via a coolant line 112e.
[0011] The low temperature cooling circuit 102 may include an
auxiliary pump 114 for circulating coolant in the low temperature
cooling circuit 102, a low temperature heat exchanger 116 for
dissipating the heat in the low temperature cooling circuit 100. It
may further include various coolers or heat exchangers for cooling
various devices, which in this example may include a transmission
cooler 118 for cooling transmission, a charged air cooler (CAC)
(e.g., an air-to-coolant CAC) 120 for cooling charged air, a fuel
cooler 122 for cooling a fuel supply, and a low temperature EGR
cooler 124 for cooling EGR. In other examples, the low temperature
cooling circuit 102 may optionally include various other heat
exchangers, such as one or more power steering coolers, condensers,
interstage coolers, engine oil coolers. The low temperature cooling
circuit 102 may also optionally include one or more additional
condensers positioned outside the low temperature heat exchanger
116.
[0012] The low temperature heat exchanger 116 may include a
condenser 116d, and a series of successively arranged two or more
radiators or radiator segments, in this example, a warm temperature
radiator 116a, an intermediate temperature radiator 116b, and a low
temperature radiator 116c. These may be arranged as
cross-counterflow segments providing maximum airflow face area to
each radiator, or, if space allows, side-by-side arranged for
u-flow or s-flow, for reduced cost and pressure drop.
[0013] The condenser 116d, the low temperature radiator 116c, the
intermediate temperature radiator 116b, and the warm temperature
radiator 116a, together with the main radiator 108 of the high
temperature cooling circuit 100 are positioned successively in a
common stream of air flow 126, with the main radiator 108 at the
most downstream end and the condenser 116d at the most upstream
end. The stream of air flow 126 may be generated by a moving
vehicle and/or a fan.
[0014] In this way, the air flow 126 cools the condenser 116d, the
low temperature radiator 116c, the intermediate temperature
radiator 116b, the warm temperature radiator 116a, and the main
radiator 108, successively in that order.
[0015] The temperature of the airflow 126 may increase as it passes
the condenser and the various radiators. For example, the
temperature of the air flow 126 may be 100.degree. F. immediately
upstream of the condenser 116d, 105.degree. F. immediately
downstream of the condenser 116d, 144.degree. F. immediately
downstream of the warm temperature radiator 116a, and 211.degree.
F. immediately downstream of the main radiator 108.
[0016] Various coolant lines may be provided to circulate the
coolant in the low temperature heat exchanger 116. In this example,
the coolant enters the low temperature heat exchanger 116 at the
warm temperature radiator 116a, and then circulates to the
intermediate temperature radiator (116b) via a coolant line 116e.
The coolant further circulates to the low temperature radiator 116c
via a coolant line 116f before exiting the low temperature heat
exchanger 116.
[0017] Various coolant lines (e.g. 128a-j, 130, 132, 134a-c) may be
provided for circulating the coolant in the low temperature cooling
circuit 102. In this example, the coolant circulates from the
auxiliary pump 114 to the low temperature heat exchanger 116 to be
cooled. The cooled coolant may then circulate to various devices
118-122 in the low temperature cooling circuit. After picking up
heat rejected from the various devices 118-122, the coolant may
then circulate back to the auxiliary pump 114 via a common coolant
line 132.
[0018] To be more specific, the coolant in this example may
circulate from the auxiliary pump 114 to the low temperature heat
exchanger 116 via a coolant line 128a. The coolant may then enter
the low temperature heat exchanger 116 at the warm temperature
radiator 116a. After being cooled by one or more radiators in the
low temperature heat exchanger 116, the coolant may exit the low
temperature heat exchanger 116 at various radiator segment
locations, and may then further circulate to cool various devices
in the low temperature cooling circuit.
[0019] In particular, the coolant may exit the low temperature heat
exchanger 116 at the low temperature radiator 116c after being
cooled by the low temperature radiator 116c. It may then circulate
to cool the charged air cooler (CAC) 120 via a coolant line 128d
before circulating back to the auxiliary pump 114 via a coolant
line 128e and then the common coolant line 132; or it may circulate
to cool the fuel cooler via a coolant line 128b before circulating
back to the auxiliary pump 114 via a coolant line 128c and then the
common coolant line 132.
[0020] The coolant may additionally exit at the intermediate
temperature radiator 116b, after being cooled by the intermediate
temperature radiator 116b. It may then circulate to cool the low
temperature EGR 124 via a coolant line 128h before circulating back
to the auxiliary pump 114 via a coolant line 128i.
[0021] The coolant may further exit the low temperature heat
exchanger 116 at the warm temperature radiator 116a after being
last cooled by the warm temperature radiator 116a. It may then
circulate to cool the transmission 118 via a coolant line 128f
before circulating back to the auxiliary pump 114 via a coolant
line 128g and then the common coolant line 132.
[0022] A bypass coolant line 128j with various branches (e.g.,
134a, 134b, 134c) may also be provided for bypassing the low
temperature heat exchanger 116 under certain operating conditions,
for example when the coolant temperature exiting the auxiliary pump
is lower than 59.degree. F. For example, as provided in this
example, the coolant may circulate directly from the auxiliary pump
114 to cool the various devices 118, 120, 122, 124 of the low
temperature cooling circuit without passing through the low
temperature heat exchanger 116. In particular, the coolant may
circulate from the auxiliary pump 114 via coolant line 128j, and
then via a coolant line 134a, to a coolant line 128h which leads to
the low temperature EGR cooler 124. The coolant may circulate from
the auxiliary pump 114 via the coolant line 128j, and then via a
coolant line 134c, to the coolant line 128f which leads to the
transmission 118. The coolant may circulate from the auxiliary pump
114 via coolant line 128j, and then coolant line 134b, to the
coolant line 130 which leads to the fuel cooler 122 and the charged
air cooler 120.
[0023] Various modifications or adjustments may be made to the
above example systems. For example, the cooling system may include
no fan, one fan or multitude of fans (not shown) for generating air
flow for cooling the various radiators of the cooling system. In
case there is no fan, the cooling system may rely solely on ram air
generated when the vehicle is moving for cooling the various
radiators of the cooling system.
[0024] The cooling system may include various sensors (not shown)
for sensing various operating parameters of the engine, vehicle,
and/or cooling system, such as one or more temperature sensors,
pressure sensors, and coolant flow rate sensors. Theses sensors may
be located in various locations in the cooling system.
[0025] The cooling system may also include various additional
pumps, filters, bypasses, valves, meters, controls and actuators,
etc. For example, additional pumps may be provided for the high
temperature cooling circuit and the low temperature cooling
circuit. The cooling system may also include valves for adjusting
and/or directing the flow rates of coolant down various coolant
lines or pipes.
[0026] The cooling system may further include a control unit (not
shown). The control unit (not shown) may be an engine control unit
or may be a unit separate from the engine control unit. It may be
configured to send and receive information from various sensors,
such as temperature sensors and pressure sensors. It may also be
coupled to and control operation of various pumps, such as coolant
pumps (e.g., 106 & 114), and various fans, such as an engine
cooling fan. It may be used to receive information from various
other sensors, pumps, actuators and valves etc.
[0027] Although the cooling system includes a main radiator 108 for
the high temperature cooling circuit 100, the radiators (e.g., the
various radiators 116a-c of the low temperature heat exchanger116),
and coolers (e.g. fuel cooler, charge air cooler, EGR cooler) may
be any suitable types of heat exchangers for heat transfer, such as
air-to-coolant heat exchangers, which serve to exchange heat
between air and coolant, and coolant-to-coolant exchangers, which
serve to exchange heat between one coolant to another.
[0028] The coolant flow rates in the various coolant lines of the
cooling system may be adjusted according to engine and/or vehicle
specifications. For example, the rate of coolant flow and the
dimension of the coolant line may be increased to accommodate an
increased cooling need, or decreased to accommodate a decreased
cooling need. For example, the rate of coolant flow for cooling the
engine, which has the largest cooling need among all engine and
vehicle components, (e.g. 100) may be relatively large (e.g., 150
gpm). The EGR cooler has a comparatively smaller cooling need
compared to the engine. Therefore, the coolant flow rate for
cooling the high temperature EGR (e.g. 106) may be comparatively
smaller (e.g., 20 gpm).
[0029] The dimensions of the various coolant lines of the cooling
system may be set according to coolant flow rates. For example, the
CAC 120 which may have a smaller flow rate compared to that of CAC,
has a comparatively smaller coolant line dimension than that of the
low temperature EGR cooler 124. Various additional dimensions
and/or flow rates are indicated in the Figures.
[0030] Although one condenser is provided in this example, no
condenser or a multitude of condensers may be provided in other
examples. For example, an additional condenser may be added to the
low temperature cooling circuit to further cool the coolant
temperature in the low temperature cooling circuit.
[0031] Although the high temperature cooling circuit 100 serves to
cool only the engine 104 and the high temperature EGR 110 in this
example, the high temperature cooling circuit 100 may serve to cool
other components or devices in other examples.
[0032] Although the engine and other components and/or devices in
the high temperature cooling circuit 100, such as the engine 104
and the high temperature EGR cooler 110 are arranged parallel to
each other in this example. In other examples, they may be arranged
in series, or in a combination of in parallel and in series.
[0033] Similarly, although the low temperature cooling circuit 102
serves to cool only the transmission 118, the charged air cooler
120, fuel cooler 122, and the low temperature EGR cooler 124 in
this example, in other examples, other components or devices, such
as Interstage Cooler, Engine Oil Cooler, Turbocharger, Electronic
Controls, or a power supply cooler, may be cooled by the low
temperature cooling circuit.
[0034] As shown in FIG. 1, the various components and/or devices to
be cooled in the low temperature cooling circuit 102 are arranged
in parallel with each other. To be more specific, in this example,
the transmission cooler 118, the charged air cooler (CAC) 120, the
fuel cooler 122, and the EGR cooler 124 are arranged in parallel
with each other. In other examples, the various components and/or
devices to be cooled by the low temperature cooling circuit may be
arranged in series or in a combination of series or parallel.
[0035] The coolant lines serving the various components and/or
devices to be cooled by the low temperature cooling circuit 102 may
exit from one or more of the radiators in the low temperature heat
exchanger, depending on the cooling need of the particular
component and/or devices to be cooled. For example, and as
described in part previously, the charged air cooler 120 and the
fuel cooler 122 need to be cooled to relatively lower temperatures,
the coolant line serving the fuel cooler and may exit the low
temperature radiator 116c, which provides the coolest coolant among
all the radiators of the low temperature heat exchanger.
[0036] In other examples, it may also be possible for a coolant
serving to cool a particular device to be a mixture of coolants
exiting one or more radiators. The coolant mixing ratio and flow
rates may be adjusted depending on the cooling need of the
particular device. The flow rates of the coolant may be determined
depending on the temperature of the coolant exiting the various
radiators and the cooling temperature requirement of the particular
device. For example, although not provided in this example, the
coolant serving to cool the CAC 120 may be a mixture of coolants
exiting the low temperature radiator 116c and the intermediate
temperature radiator 116b.
[0037] By maintaining two separate cooling circuits where the
coolant streams do not mix, it may be possible to reduce heat
transfer between the two cooling circuits. To be more specific, it
may better insulate the engine heat of the high temperature cooling
circuit from the low temperature cooling circuit, achieving lower
coolant temperatures in the low temperature cooling circuit to
achieve more optimal cooling of the various devices in the second
cooling circuit.
[0038] By providing at least a condenser in the second cooling
circuit, it may be possible, in some situations, to further cool
the coolant streams of the second cooling circuit to a lower
temperature when it is needed for an increased cooling
capacity.
[0039] By successively ordering the plurality of radiator segments
in the second cooling circuit so that increased cooling of the
circulating coolant may be achieved at a radiator positioned
downstream in the path of the circulating coolant.
[0040] By allowing coolant to exit at the various successively
arranged radiator segments, it may be possible to provide coolant
streams of different temperatures for cooling the various devices
in the second cooling circuit. In one example, the coolant stream
exiting the low temperature radiator, which is the most downstream
radiator segment, has the lowest temperature (e.g., 127.degree.
F.); the coolant stream exiting the intermediate temperature
radiator, which is positioned upstream of the low temperature
radiator, has the next lowest temperature (e.g., 150.degree. F.);
and the coolant stream exiting the warm temperature radiator, which
is positioned upstream of the intermediate temperature radiator,
has the highest temperature (e.g. 180.degree. F.).
[0041] By distributing coolant streams of different temperatures,
it may be possible to individualize the temperature of the coolant
for cooling a particular device, thereby improving cooling
efficiency and performance of the device. In a particular example,
the temperature of the coolant used for cooling a transmission is
180.degree. F., achieved by allowing the coolant used to cool the
transmission to exit a temperature heat exchanger after it is
cooled by only one radiator; the temperature of the coolant used to
cool a low temperature EGR cooler is 150.degree. F., achieved by
allowing the coolant used for cooling the low temperature EGR
cooler to exit a low temperature heat exchanger after it is cooled
by two radiators; and the temperature of the coolant used to cool a
fuel cooler and a charged air cooler is 127.degree. F., achieved by
allowing the coolant used to cool the fuel cooler and the charger
air cooler to exit a low temperature heat exchanger after it is
cooled by three radiators.
[0042] An improved cooling efficiency may allow smaller coolant
flows and smaller coolant line dimensions, which may lead to a more
compact cooling system design.
[0043] By utilizing a common stream of cooling air over to cool
radiators in both the first and the second coolant circuits, it may
further help to achieve a more compact system design.
[0044] By pumping coolant in the second cooling circuit via a pump
coupled upstream of a radiator (e.g., on the hotter side and
downstream of the various devices), it may be possible to utilize a
single pump for the lower temperature circuit that is able to
provide multiple coolant outlets with different coolant
temperatures to serve the various devices with different
temperature requirements.
[0045] Further, the dimension of the cooling lines or pipes of the
two cooling circuits and the coolant flow rates may be
individualized to suit the cooling needs of each component, and
thereby minimize the cooling system package size. For example,
utilizing a larger coolant line or pipe dimension in the high
temperature cooling circuit may help to meet the increased cooling
need of the engine, which generates a tremendous amount of heat
during combustion. On the other hand, utilizing a smaller coolant
line dimension in the low temperature cooling circuit, which serves
engine and vehicle components with lower cooling needs, may help to
minimize the overall package size of the cooling system.
[0046] By providing a high temperature EGR cooler and a low
temperature EGR cooler with different operating temperatures, it
may be possible for a finer tuning of the EGR temperature.
[0047] Further, by utilizing two thermally separate cooling loops,
it may be possible to reduce cavitation, even when using a pump on
the hotter side of a radiator of the low temperature loop.
[0048] The following claims particularly point out certain
combinations and subcombinations regarded as novel and nonobvious.
These claims may refer to "an" element or "a first" element or the
equivalent thereof. Such claims should be understood to include
incorporation of one or more such elements, neither requiring nor
excluding two or more such elements. Other combinations and
subcombinations of the disclosed features, functions, elements,
and/or properties may be claimed through amendment of the present
claims or through presentation of new claims in this or a related
application. Such claims, whether broader, narrower, equal, or
different in scope to the original claims, also are regarded as
included within the subject matter of the present disclosure.
* * * * *