AIR-COOLED HEAT EXCHANGER AND BLOWER ASSEMBLY AND METHOD

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from U.S. Provisional Patent Application

No. 61/023,229, filed January 24, 2008, the entire contents of which are incorporated herein by reference.

BACKGROUND

[0002] As demands for air-cooled heat exchange systems continue to increase in many vehicular applications, significant vehicle design issues arise relating to the placement and design of heat exchangers in such systems. One issue regards the limited space available within a vehicle for cooling heat exchange surfaces with air flowing thereover during forward movement of the vehicle. In many vehicular applications, the demand for cooling surfaces is greater than the available space exposed to such air flow. Accordingly, various heat exchangers and heat exchanger system configurations have been developed to meet the vehicle cooling requirements in light of the limited air flow cooling space. However, the demand for new air-cooled heat exchangers and air-cooled heat exchanger systems continues to increase.

SUMMARY

[0003] Some embodiments of the present invention provide a heat exchange system for cooling a fluid to be supplied to a component of a power-train system of a vehicle, wherein the vehicle defines a plurality of surfaces upon which air impinges by forward movement of the vehicle, and wherein the heat exchange system comprises: a housing; a fan coupled to the housing and having an axis of rotation; a heat exchanger within the housing and located outside of a flow of air generated by forward movement of the vehicle, the heat exchanger comprising: a plurality of tubes through which the fluid flows; and a plurality of fins between the tubes and through which air moved by the fan flows, the plurality of tubes and the plurality of fins lying substantially in a common plane oriented at an oblique angle with respect to the axis of rotation of the fan; and a fluid circuit along which the fluid moves from the heat exchanger to the component of the power- train system.

[0004] In some embodiments, an exhaust gas recirculation cooler for cooling exhaust gas from an engine of a vehicle is provided, and comprises: a housing having an input port and an output port; a heat exchanger located within the housing between the input port and the output port, the heat exchanger comprising a plurality of tubes through which the exhaust gas flows; and a plurality of fins between the tubes, the plurality of tubes and the plurality of fins lying substantially in a common plane; and a fan coupled to the housing and operable to supply air through the input port, through the fins between the tubes of the heat exchanger, and through the output port; wherein airflow generated by the fan passes through the heat exchanger at an oblique angle with respect to the plane of the plurality of tubes and the plurality of fins.

[0005] In some embodiments, a method of cooling exhaust gas from an engine of a vehicle is provided, and comprises: moving exhaust gas in a common first direction through multiple tubes of a heat exchanger core located in a housing; moving cooling air through an input port of the housing by a fan mounted to the housing; moving cooling air in the housing toward the heat exchanger core along a second direction oriented at an acute angle with respect to the first direction; moving cooling air through the heat exchanger tube core; transferring heat from exhaust gas moving through the tubes of the heat exchanger core to cooling air moving through the heat exchanger tube core; moving cooling air in the housing away from the heat exchanger core; and moving cooling air through an output port of the housing.

[0006] Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Fig. l is a schematic representation of a vehicle including an air cooled EGR cooler according to an embodiment of the present invention.

[0008] Fig. 2 is a schematic representation of a construction of the vehicle in Fig. 1.

[0009] Fig. 3 is a schematic representation of an alternative construction of the vehicle in Fig. 1.

[0010] Fig. 4 is a perspective view of an air cooled EGR cooler according to an embodiment of the present invention.

[0011] Fig. 5 is another perspective view of the air cooled EGR cooler shown in Fig. 4.

[0012] Fig. 6 is a sectional view of the air cooled EGR cooler shown in Figs. 4 and 5.

[0013] Fig. 7 is a perspective view of a heat exchanger of the air cooled EGR cooler shown in Figs. 4-6.

[0014] Fig. 8 is a detail view of the heat exchanger shown in Fig. 7.

DETAILED DESCRIPTION

[0015] Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings.

[0016] Figs. 1 - 8 illustrate a cooler 100 and components of vehicular cooling systems 20, 220, 320 in which the cooler 100 is used to cool a fluid using air flow. The cooler 100 illustrated in Figs. 1, 2, and 4-8 is an air cooled exhaust gas recirculation cooler (an "EGR cooler"). However, as further described below, other fluids (e.g., other gases, oil, transmission fluid) can be cooled by the heat exchange structure indicated by reference numeral 100. Fig. 1 schematically illustrates a vehicle 10 including a power-train system 15 and a cooling system 20. The power-train system 15 includes, among other elements, an engine 25 and a transmission 30. The cooling system 20 includes an air source or air supply module 35, an air outlet or air exit module 40, and the EGR cooler 100 between the air source

35 and the air outlet 40. The EGR cooler 100 includes an exhaust gas inlet 45, an exhaust gas outlet 50, an air inlet 55 fluidly connected to the air source 35, an air outlet 60 fluidly connected to the air outlet 40, and a fan 500 (see Figs. 4 - 6) mounted at the air inlet 55. The fan 500 generates a cooling air flow through the EGR cooler 100 and between the air inlet 55 and air outlet 60 to cool exhaust gas from the power-train system 15 flowing between the exhaust gas inlet 45 and outlet 50.

[0017] The coolers 100 illustrated in Figs. 1-8 each have a fan 500 enabling cooling air flow to be supplied to the cooler 100 for cooling working fluid also supplied to the cooler 100. Using such a construction, the coolers 100 can be located away from the air flow experienced by a vehicle 10, 210, 310 during movement of the vehicle (e.g., forward movement of the vehicle 10, 210, 310). Accordingly, the coolers 100 need not occupy space within the air flow of the vehicle 10, 210, 310 used by other heat exchangers to cool other components or systems of the vehicle 10, 210, 310. Such coolers 100 can be therefore be in any other location within the vehicle, such as beneath the vehicle body and/or frame, within or adjacent a trunk or bed space of the vehicle, within other enclosed or partially-enclosed cavities of the vehicle, in locations of the engine compartment not otherwise experiencing significant air flow, and the like. This flexibility can significantly increase the design possibilities for vehicle power-train cooling systems.

[0018] As shown in Fig. 1, a fluid line 65 is fluidly connected to the exhaust gas inlet 45 to supply exhaust gas from the power-train system 15 to the EGR cooler 100. Similarly, a fluid line 70 is fluidly connected to the exhaust gas outlet 50 to receive the exhaust gas exiting the EGR cooler 100 at a desirable lower temperature, and to return the exhaust gas to the power-train system 15. For purposes of illustration only, exhaust gas from the power- train system 15 flowing through the EGR cooler 100 shown in Figs. 1-8 flows between the exhaust gas inlet 45 and outlet 50 of the EGR cooler 100 in a substantially straight direction. However, it is to be understood that the flow configuration of the working fluid within the EGR 100 can vary depending at least in part upon the particular design of the heat exchanger 495 within the EGR cooler 100. In this regard, exhaust gas flow through the heat exchanger 495 can follow two or more straight and/or curved paths extending in different directions while still entering the exhaust gas inlet 45 and exiting the exhaust gas outlet 50 (which themselves can be located elsewhere on the EGR cooler 100 in other embodiments).

[0019] In some embodiments (e.g., the illustrated embodiment), air flow between the air inlet 55 and the air outlet 60 moves in a second direction that is oblique with respect to the direction of exhaust gas through the EGR cooler 100. Also, in some embodiments, an axial fan 500 is used to move the air through the EGR cooler 100, as described in greater detail below. The direction of air flow between the air inlet 55 and the air outlet 60 in such embodiments can be substantially parallel to the axis of rotation of the fan 500. In some embodiments, the oblique angle between the direction of air flow between the air inlet and outlet 55, 60 and the direction of exhaust gas through the EGR cooler 100 is less than 45 degrees. Also, in some embodiments, the oblique angle is an acute angle formed between an upstream portion of air flow from the air inlet 55 to the heat exchanger 495 and the exhaust gas flow direction through the heat exchanger 495.

[0020] Figs. 2 and 3 schematically illustrate a first construction and a second construction, respectively, of the vehicle and cooling system shown in Fig. 1. As further described below, the cooler 100 is utilized in the first and second constructions of the vehicle to cool two different working fluids. For ease of description, elements in Figs. 2 and 3 corresponding to the elements in Fig. 1 are labeled with the same numerals in the 200 and 300 series.

[0021] Fig. 2 is a schematic representation of a vehicle 210 having the EGR cooler 100, wherein the vehicle 210 includes a power-train system 215 and a cooling system 220 similar to the power-train system 15 and cooling system 20 shown in Fig. 1. The EGR cooler 100 in the illustrated embodiment of Fig. 2 is located outside of the air stream experienced by the vehicle 210 in forward movement of the vehicle 210. The vehicle 210 is a turbo-charged vehicle including a turbo 275 with a turbine 280 driving a compressor 282, a charge air cooler (CAC) 285, and a mixing valve 287. In the illustrated construction, exhaust gas from an engine 225 is utilized to propel the turbine 280, and is subsequently discharged from the vehicle 210 through an exhaust system (not shown). A portion of the exhaust gas from the engine 225 is directed via a fluid line 265 to the EGR cooler 100 in order to cool that portion of the exhaust gas. A cooling air flow between an air inlet 255 and an air outlet 260 is utilized to cool the exhaust gas flowing between an exhaust gas inlet 245 (fluidly connected to the fluid line 265) and an exhaust gas outlet 250 of the EGR cooler 100. The cooling air flow through the EGR cooler 100 defines a flow direction that is oblique with respect to the

flow direction of the exhaust gas through the EGR cooler 100. The cooled exhaust gas flows out of the EGR cooler 100 to the mixing valve 287 via a fluid line 270.

[0022] With continued reference to Fig. 2, ambient air for combustion in the engine 225 is received via an intake system (not shown). The intake air is compressed in the compressor 282 and is cooled by the CAC 285. Air cooled in the CAC 285 flows to the mixing valve 287 to be mixed with exhaust gas cooled in the EGR cooler 100. The mixture of intake air and exhaust gas flows from the mixing valve 287 to the engine 225 for combustion. It is to be understood that the flow configurations of the intake air (received at the compressor 282) and exhaust gas (through the EGR cooler 100) are shown for illustrative purposes only, and that other configurations fall within the spirit and scope of the present invention.

[0023] Fig. 3 is a schematic representation of a vehicle 310 including a cooler 100 similar to those described above, but instead used to cool transmission fluid. The cooler 100 in the illustrated embodiment of Fig. 3 is located outside of the air stream experienced by the vehicle 210 in forward movement of the vehicle 210. Also, the vehicle 310 has a power-train system 315 and a cooling system 320 similar to the power-train system 15 and cooling system 20 in Fig. 1. In this embodiment, the vehicle 310 includes a transmission fluid recirculation system with a pump 390 for circulating transmission fluid between a transmission 330 of the power-train system 315 and the cooler 100. In the illustrated construction, the pump 390 is located along a fluid line 370 fluidly connected to a transmission fluid outlet 350 of the cooler 100. However, in other embodiments, the pump 390 can be in different locations of the transmission fluid recirculation system. Transmission fluid flows from the transmission 330 to an inlet 345 of the cooler 100 via a fluid line 365. The transmission fluid flows between the transmission fluid inlet 345 and a transmission fluid outlet 350 of the cooler 100, and is cooled thereby. A cooling air flow between an air inlet 355 and an air outlet 360 is utilized to cool the transmission fluid flowing between the transmission fluid inlet 345 and the transmission fluid outlet 350 of the cooler 100. The cooling air flow through the cooler 100 defines a flow direction that is oblique with respect to the flow direction of the transmission fluid through the cooler 100.

[0024] Figs. 4 - 8 illustrate an embodiment of the coolers 100 schematically shown in Figs. 1 - 3. With specific reference to Figs. 4 - 6, the cooler 100 includes a housing 400 with an air inlet 455 and an air outlet 460, and a heat exchanger 495. The housing 400 is formed as a single molded aluminum piece. However, it is to be understood that other constructions

of the cooler can include a housing formed of two or more pieces as well as include other materials (e.g., plastic, stainless steel, and the like).

[0025] In the illustrated embodiment, a fan 500 is mounted at the air inlet 455 and is at least partially supported within the housing 400. The mounting of the fan 500 defines an axis of fan rotation 502 that is substantially parallel to the flow of cooling air (at least in part generated by the fan 500) between the air inlet 455 and the air outlet 450 of the cooler 100. In other constructions of the cooler 100, the fan 500 can be mounted at a different location of the housing 400 (e.g., at the air outlet 450).

[0026] Although the housing 400 can be constructed of multiple pieces as described above, the use of a single-piece housing 400 can provide significant advantages for the cooler 100. For example, the single-piece housing 400 can be molded or otherwise formed around the heat exchanger 495 so that the heat exchanger and housing define a single integral unit requiring no further assembly of the heat exchanger and housing. Similarly, in some embodiments, the single-piece housing 400 can be molded or otherwise formed around at least part of the fan 500 so that the fan 500 is also part of the single integral unit requiring no further assembly of the fan and housing. In both cases, the resulting cooler 100 (or substructure of the cooler 100) can be readily installed within and removed from the vehicle as a single integral unit, resulting in savings of labor, assembly, and time.

[0027] With reference to Figs. 6 - 8, the heat exchanger 495 includes a heat exchanger core 505 with a first end 507 and a second end 510. hi the illustrated construction, the heat exchanger core 505 includes a number of flat tubes 515 substantially parallel to one another, and a number of fins 520 allow cooling air flow (at least in part generated by the fan 500) through the flat tubes 515. Each fin 520 is located between two adjacent flat tubes 515 to transfer heat from the working fluid flowing through the flat tubes 515 to the cooling air flowing through the fins 520. Each flat tube 515 includes an insert 517 for dividing the flat tube 515 into a number of substantially parallel conduits (see Fig. 8). At the first end 507, the illustrated heat exchanger 495 includes a header plate 525 coupled to the heat exchanger core 505 and having a number of apertures 527. Each aperture 527 is formed to allow working fluid to flow to a corresponding flat tube 515. The header plate 525 also includes portions 530 (e.g., bosses or other extensions) having apertures 532 for receiving suitable fasteners (e.g., bolts, screws, and the like).

[0028] With reference now to Fig. 6, the header plate 525 contacts a portion 534 of the housing 400 for mounting and/or fastening the heat exchanger 495 to the housing 400. In the illustrated construction, an inlet port 535 is mounted to the header plate 525 and defines a working fluid inlet 445. More specifically, the inlet port 535 includes a mounting plate 537 adapted to couple to the header plate 525 such that the inlet port 535 and the header plate 525 are both coupled to the portion 534 of the housing 400 in an assembled state of the EGR cooler 100. This cooler configuration allows for securely fastening the heat exchanger 495 to the housing 400 and to fluidly connect the inlet 445 to the flat tubes 525 of the heat exchanger 495.

[0029] The second end 510 of the heat exchanger 495 includes a second port 540 coupled directly to the heat exchanger core 505. The second port 540 defines a working fluid outlet 450 fluidly connected to the flat tubes 515. In the illustrated construction, a portion 545 of the housing 400 opposite the portion 534 and the header plate 525 is formed to receive and support the second port 540 such that the heat exchanger 495 is securely coupled to the housing 400 between the inlet port 535 and the portion 545 of the housing 400.

[0030] In some embodiments, the heat exchanger core 505 is coupled to the housing 400 in a manner permitting either or both ends of the heat exchanger core 505 to move relative to the housing 400 in response to thermal changes experienced by the heat exchanger core 505. Such changes can cause expansion or contraction of the heat exchanger core 505, which can be accommodated by permitting such relative movement between the end(s) of the heat exchanger core 505 and the housing 400. In the illustrated embodiment, for example, the second port 540 of the heat exchanger 495 is slidable relative to the portion 545 of the housing 400 in which the second port 540 is received. If desired, one or more sliding seals can be provided between the second port 540 and the portion 545 of the housing 400. In other embodiments, the housing 400 and heat exchanger 495 can be adapted so that a similar relationship between the housing 400 and heat exchanger 495 exists on the opposite end of the heat exchanger 495 and housing 400. As an alternative to a sliding seal as just described, the second port 540 can include or define a bellows portion deforming upon thermal expansion and contraction of the heat exchanger core 505. A similar bellows structure can be provided on the opposite end of the heat exchanger core 505. Still other elements and structures used for permitting thermal expansion and contraction of a heat exchanger core

505 and an adjacent housing 400 are possible, and fall within the spirit and scope of the present invention.

[0031] As shown in Fig. 6, the heat exchanger 495 is arranged to allow the flow of a working fluid between the inlet 445 and the outlet 450. During operation of the illustrated cooler 100, the working fluid flowing through the heat exchanger 495 flows in a direction substantially parallel to an axis 550 passing through the inlet 445 and the outlet 450. In addition, a cooling air flow at least partially generated by the fan 500 flows between the air inlet 455 and the air outlet 460 in a direction substantially parallel to another axis 502. As described above, the cooling air flow along the axis 502 is oblique with respect to the direction of flow of the working fluid defined by the axis 550. As shown in Fig. 8, in some embodiments, the fins 520 of the heat exchanger 495 allowing cooling air flow therethrough are substantially perpendicular to the axis 550. Therefore, the direction of cooling air flow through the fins 520 forms an angle with the axis 502, this angle being a complementary angle of the angle between the axis 502 and the axis 550. However, in other constructions of the EGR cooler 100, the heat exchanger 495 is formed such that the fins 520 allow cooling air flow therethrough in a direction substantially parallel to the axis 502. In such constructions, the fins 520 are angled or canted to define flow paths therethrough that are parallel, substantially parallel, or substantially aligned with the axis 502.

[0032] The heat exchange structure described above and illustrated in Figs. 4-7 is an EGR cooler 100 used to cool exhaust gas supplied to the engine of a vehicle. However, it will be appreciated that the same or similar heat exchange device can also be employed to cool any fluid supplied to a power transmission component of a vehicle. For example, the same or similar heat exchange device can be used to cool air, other gases, water, oil, transmission fluid, and any other fluid used to cool an engine, transmission, or any other power transmission component of a vehicle. Accordingly, the heat exchange structure described above and illustrated in Figs. 4-7 can function as a charge air cooler, radiator, intercooler, oil cooler, and the like.

[0033] Various features and advantages of the invention are set forth in the following claims.