WO2008080305A1

WO2008080305A1 - Cooling system having strategically arranged tiers of exchangers

Info

Publication number: WO2008080305A1
Application number: PCT/CN2007/003861
Authority: WO
Inventors: Wenbo Jin; Jennifer Yanfang Wu
Original assignee: Caterpillar R & D Center (China) Co., Ltd.
Priority date: 2006-12-30
Filing date: 2007-12-28
Publication date: 2008-07-10
Also published as: CN101209669A; RU2468219C2; RU2009129260A; CN101209669B

Abstract

A cooling system for a machine is disclosed. The cooling system may have a first heat exchanger (62) and a second heat exchanger (64) substantially coplanar with the first heat exchanger (62). The cooling system may also have a third heat exchanger (48) non-coplanar with the first and second heat exchanger (62,64). The third heat exchanger (48) may have an inlet temperature and a lower outlet temperature. The third heat exchanger (48) may be located such that the portion of the third heat exchanger (48) receiving fluid at the inlet temperature is disposed to also receive a flow of air in series with the second heat exchanger (64), and the portion of the third heat exchanger (48) discharging fluid at the lower outlet temperature is disposed to receive a flow of air in series with the first heat exchanger (62). The cooling system may provide unique exchanger packaging strategy that improves dissipation effectiveness within a confined space.

Description

COOLING SYSTEM HAVING STRATEGICALLY ARRANGED TIERS OF

EXCHANGERS

Technical Field

[0001] The present disclosure relates generally to a cooling system having multiple heat exchangers and, more particularly, to a cooling system having multiple heat exchangers strategically arranged in multiple tiers to efficiently dissipate heat.

Background

[0002] Machines, including track-type tractors, wheel loaders, haul trucks, and other heavy construction and mining equipment, are used for a variety of tasks. In order to accomplish these tasks, the machines typically include an internal combustion engine such as a diesel engine, gasoline engine, or gaseous fuel-powered engine that produces significant amounts of power by combusting a fuel/air mixture. This combustion process generates large amounts of heat and, in order to ensure proper and efficient operation of the engine, a cooling system is required to cool fluids directed into or out of the engine.

[0003] For example, an internal combustion engine is generally fluidly connected to several different liquid-to-air and/or air-to air heat exchangers to cool both liquids and gases circulated throughout the engine. These heat exchangers are often located close together and/or close to the engine to conserve space on the machine. An engine driven fan is disposed either in front of the engine/exchanger package to blow air across the exchangers and the engine, or between the exchangers and engine to suck air past the exchangers and blow air past the engine.

[0004] The size of engine and power output of the engine may be at least partially dependent on the amount of cooling provided to the engine. That is, the engine may have a maximum temperature and a most efficient operating temperature range, and operation of the engine may be limited by the capacity of the associated exchangers to maintain the engine's temperatures below the maximum limit and within the optimum range. In addition, given the space constraints of a particular engine's enclosure, the size of the exchangers may also be limited. Therefore, it becomes necessary to maximize cooling efficiency for a given space constraint. [0005] Maximizing cooling efficiency can be difficult, especially when multiple engine and non-engine heat exchangers are packaged together. That is, in some configurations, transmission and/or hydraulic oil coolers are co-located with engine heat exchangers to take advantage of the airflow generated by the engine driven fan. In these situations, the heat transfer from the oil coolers can affect the heat transfer from the engine's exchangers, as well as consume space within the engine's compartment.

[0006] One example of maximizing machine cooling within a given engine compartment is disclosed in U.S. Patent Publication 2004/0045749 (the '749 publication) published to Jaura et al. on March 1 1, 2004. The '749 publication describes a cooling system for a hybrid electric vehicle. The cooling system includes an electric fan disposed in a sucking arrangement to draw air in a substantially uniform manner across an electronic control module, an air conditioning condenser, a transmission oil cooler, and a radiator, all of which are disposed in a series relationship relative to the air flow created by the fan. The cooling air flow created by a 42 volt power supply driving the electric fan controllably varies based on vehicle speed and ambient air temperature such that sufficient cooling of the critical vehicle systems is accomplished.

[0007] Although the cooling system of the '749 publication may provide adequate cooling in a confined space by packaging multiple heat exchangers together in a series relationship, it may lack the efficiency required for optimal heat rejection. That is, some heat exchangers operate at a higher average temperature and/or reject greater amounts of heat to the cooling air than other heat exchangers within the same package. In this situation, if the hotter exchanger (i.e., the exchanger having a greater average temperature and heat rejection amount) is located upstream of a colder downstream exchanger, or upstream of cold portions of the downstream exchanger, effectiveness of the downstream exchanger may be significantly and negatively affected. The cooling system of the '749 publication does not address these situations.

[0008] The disclosed cooling system is directed to overcoming one or more of the problems set forth above.

Summary of the Invention

[0009] In one aspect, the present disclosure is directed to a cooling system. The cooling system may include a first heat exchanger having a first heat rejection amount, and a second heat exchanger substantially coplanar with the first heat exchanger. The second heat exchanger may have a second heat rejection amount greater then the first heat rejection amount. The cooling system may also include a third heat exchanger non-coplanar with the first and second heat exchangers and having an inlet temperature and a lower outlet temperature. The third heat exchanger may be located such that the portion of the third heat exchanger receiving fluid at the inlet temperature is disposed to also receive a flow of air in series with the second heat exchanger, and the portion of the third heat exchanger discharging fluid at the lower outlet temperature is disposed to receive a flow of air in series with the first heat exchanger.

[0010] In another aspect, the present disclosure is directed to a method of cooling. The method may include generating a first flow of pressurized fluid, a second flow of pressurized fluid, and a third flow of pressurized fluid. The second flow of -A-

pressurized fluid may have an average temperature greater than an average temperature of the first flow of pressurized fluid. The second flow of pressurized fluid may also have substantially the same flow direction as the first flow of pressurized fluid. The third flow of pressurized may be in a direction substantially orthogonal to the first and second flows of pressurized fluid. The method may also include directing a flow of air to remove heat from the first, second, and third flows of pressurized fluid. The pressurized fluid of the third flow may be first cooled by air also directed to cool the second flow of fluid, before the pressurized fluid of the third flow is cooled by air also directed to cool the first flow of pressurized fluid.

Brief Description of the Drawings

[0011] Fig. 1 is a diagrammatic illustration of an exemplary disclosed machine;

[0012] Fig. 2 is a pictorial and schematic illustration of an exemplary disclosed cooling system for use with the machine of Fig. 1 ;

[0013] Fig. 3 is a pictorial illustration of a heat exchanger for use with the cooling system of Fig. 2;

[0014] Fig. 4 is a pictorial illustration of a section of exemplary disclosed cooling fins for use with the cooling system of Fig. 3;

[0015] Figs. 5A and 5B are cross-sectional illustrations of the exemplary disclosed cooling fins of Fig. 4; and

[0016] Fig. 6 is a pictorial illustration of a section of the exemplary disclosed cooling fins of Fig. 4.

EXPLANATION OF REFERENCE SIGNS

10. Machine

12. Engine

14. Engine Block 16. Cylinder

18. Piston

20. Combustion Chamber

22. Air Induction System

24. Transmission System

26. Ground Engaging Devices

28. Hydraulic Implement System

30. Work Tool

32. Cooling Package

34. Torque converter

35. Compressor

36. Hydraulic Linear Actuator 38. First Tier

40. Second Tier

42. Cooling Fan

44. Input Device

46. Fan Blade

48. Heat Exchanger (ATAAC)

50. Heat Exchanger (HOC)

52. Upper First Side (Heat Exchanger 48)

54. First End (Heat Exchanger 48)

56. Second End (Heat Exchanger 48)

58. First End (Heat Exchanger 50)

60. Second End (Heat Exchanger 50)

62. Heat Exchanger (Radiator)

64. Heat Exchanger (TCOC)

66. Upper First End (Heat Exchanger 62) 68. Second Lower End (Heat Exchanger 62)

70. First End (Heat Exchanger 64)

72. Second End (Heat Exchanger 64)

74. First End Cap

76. Second End Cap

78. Tube

80. Fin

82. Channel

82a. Channel

82b. Channel

84. S-shape

86. Centerline

88. Bounding Surface

90. S-shape

Detailed Description

[0017] Fig. 1 illustrates a machine 10 having an engine 12. Machine 10 may perform some type of operation associated with an industry such as mining, construction, farming, power generation, or any other industry known in the art. For example, machine 10 may embody an earth moving machine such as a dozer, a loader, a backhoe, an excavator, a motor grader, a dump truck, or any other suitable earth moving machine. Machine 10 may alternatively embody a stationary machine such as a generator set, a pump, or another operation-performing machine. [0018] Engine 12 may include multiple components that cooperate to combust a fuel/air mixture and produce a power output. In particular, engine 12 may include an engine block 14 that defines a plurality of cylinders 16, a piston 18 slidably disposed within each cylinder 16, and a cylinder head (not shown) associated with each cylinder 16. It is contemplated that engine 12 may include additional or different components such as, for example, a valve arrangement associated with each cylinder head, one or more fuel injectors, and other components known in the art. For the purposes of this disclosure, engine 12 is depicted and described as a four-stroke diesel engine. One skilled in the art will recognize, however, that engine 12 may be any other type of combustion engine such as, for example, a gasoline or a gaseous fuel-powered engine.

[0019] Cylinder 16, piston 18, and the cylinder head may form a combustion chamber 20. In the illustrated embodiment, engine 12 includes four combustion chambers 20. However, it is contemplated that engine 12 may include a greater or lesser number of combustion chambers 20 and that combustion chambers 20 may be disposed in an "in-line" configuration, a "V" configuration, or any other suitable configuration.

[0020] As also shown in Fig. 1, engine 12 may include one or more systems that facilitate operation of machine 10 and the production of power by engine 12. In particular, machine 10 may include an air induction system 22 associated with engine 12, a transmission system 24 operatively connecting engine 12 to one or more ground engaging devices 26, a hydraulic implement system 28 associated with a work tool 30 mounted to machine 10, and a cooling package 32 disposed to dissipate heat from engine 12, induction system 22, transmission system 24, and hydraulic implement system 28. It is contemplated that engine 12 may include additional systems such as, for example, a fuel system, a lubrication system, a braking system, an air conditioning system, a control system, and other such known systems, which may be used to facilitate machine operation and also benefit from the heat dissipation provided by cooling package 32.

[0021] Air induction system 22 may include a means for introducing charged air into combustion chambers 20 of engine 12. For example, air induction system 22 may include one or more compressors 35 (only one illustrated in Fig. 1) in fluid communication with one or more inlet ports (not shown) of each cylinder head. It is contemplated that additional and/or different components may be included within air induction system 22 such as, for example, one or more air cleaners, a waste gate or bypass valve, a throttle valve, recirculation valve, and other means known in the art for introducing charged air into combustion chambers 20. [0022] Compressors 35 may compress the air flowing into engine 12 to a predetermined pressure level. Compressors 35 may be disposed in a parallel relationship and embody a fixed geometry compressor, a variable geometry compressor, or any other type of compressor known in the art. It is contemplated that compressors 35 may alternatively be disposed in a series relationship or that air induction system 22 may include only a single compressor 35. [0023] Transmission system 24 includes elements that interact to transmit power from engine 12 to ground engaging device 26 at a range of output speed ratios. One of these elements may include a torque converter 34. Torque converter 34 may include, for example, a pair of opposing hydraulic impellers driven by pressurized oil to selectively couple, partially couple, and/or decouple engine 12 with a mechanical step-change transmission (not shown). Torque converter 34 may allow engine 12 to rotate somewhat independently of the transmission. The amount of independent rotation between engine 12 and the transmission may be varied by modifying a pressure of the oil supplied to torque converter 34.

[0024] Hydraulic implement system 28 include a plurality of fluid components that cooperate to move work tool 30. In particular, hydraulic implement system 28 may include one or more hydraulic linear actuators 36 driven by pressurized oil to selectively extend and retract in response to an operator's command, thereby raising and lowering work tool 30 with respect to machine 10. It is contemplated that hydraulic implement system 28 may also or alternatively include rotary style actuators (not shown) utilized to spin work tool 30, and/or that hydraulic actuators 36 may be utilized to steer machine 10, brake machine 10, or accomplish other machine-related tasks, if desired.

[0025] Cooling package 32 may include components that collaborate to dissipate heat from engine 12, induction system 22, transmission system 24, and hydraulic implement system 28. For example, cooling package 32 may include a first tier 38 of coplanar heat exchangers, a second tier 40 of coplanar heat exchangers, and a cooling fan 42 located between engine 12 and both first and second tiers 38, 40. [0026] Cooling fan 42 may be indirectly driven by engine 12. In particular, as illustrated in Fig. 2, cooling fan 42 may include an input device 44 such as a belt driven pulley, a hydraulically driven motor, or an electrically powered motor that is mounted to engine 12 or machine 10, and fan blades 46 fixedly or adjustably connected thereto. Cooling fan 42 may be powered by engine 12 to cause fan blades 46 to blow air across first and second tiers 38, 40, in that order. [0027] First tier 38 may include two heat exchangers 48, 50 horizontally oriented relative to the pull of gravity. Heat exchanger 48 may be situated vertically above heat exchanger 50 and be associated with air induction system 22. For example, heat exchanger 48 may be an air-to-air after cooler (ATAAC) fluidly coupled to cool air upstream or downstream of compressor 35, before it flows into engine 12. The flow of air from compressor 35 may be vertically downward through an inlet on an upper first side 52 of heat exchanger 48 toward a first end 54. From the inlet, the flow may change direction by about 90° to flow substantially horizontally through heat exchanger 48 toward an opposing second end 56, and again change direction by about 90° to flow vertically upward through an outlet on upper first side 52, in opposition to the incoming air. Upper first side 52 of heat exchanger 48 may be located opposite heat exchanger 50. [0028] Heat exchanger 48 may have a greater average operating temperature and dissipate a greater amount of heat than heat exchanger 50. That is, heat exchanger 48 may have an inlet temperature, during rated operation of machine 10, of about 15O⁰C, and an inlet mass flow rate of about 0.188 kg/sec. As such, when the temperature of the air pushed by cooling fan 42 has a temperature of about 4O⁰C, heat exchanger 48 may have an exit temperature of about 62°C and reject about 30 k W of heat.

[0029] Heat exchanger 50 may be associated with hydraulic implement system 28 and embody, for example, a hydraulic oil cooler (HOC). The flow of oil to and/or from hydraulic actuator 36 may flow horizontally through an inlet on a first end 58 of heat exchanger 50 and exit through an outlet on an opposing second end 60. Heat exchanger 50 may have an inlet temperature, during rated operation of machine 10, of about 86°C, and an inlet flow rate of about 80L/min. As such, when the temperature of the air pushed by cooling fan 42 has a temperature of about 40⁰C, heat exchanger 50 may have an exit temperature of about 76°C and reject about 20 k W of heat.

[0030] Second tier 40 may be located downstream of first tier 38 relative to the flow of air generated by cooling fan 42, and include two vertically oriented heat exchangers 62, 64. Heat exchanger 62 may be situated to receive air flow in series with ends 56 and 60 of heat exchangers 48 and 50, respectively, while heat exchanger 64 may be situated to receive air flow in series with opposing ends 54 and 58. Similarly, the upper ends (i.e., the ends associated with hot inlet flows of fluid) of both heat exchangers 62, 64 may be situated to receive air flow in series with heat exchanger 48, while the lower ends (i.e., the ends associated with cooler outlet flows of fluid) of both heat exchangers 62, 64 may be situated to receive air flow in series with heat exchanger 50. Both heat exchangers 62, and 64 may have greater average operating temperatures and dissipate greater amounts of heat than either of heat exchangers 48 and 50.

[0031] Heat exchanger 62 may embody a radiator situated to dissipate heat from water, glycol, a water/glycol mixture, or a blended air mixture circulated throughout engine 12. The flow of coolant from engine 12 may be vertically downward through an inlet on an upper first end 66 of heat exchanger 62 toward an opposing second lower end 68 in a direction substantially aligned with the pull of gravity. [0032] Heat exchanger 62 may have a lower average operating temperate and dissipate a lower amount of heat than heat exchanger 64. That is, heat exchanger 62 have an inlet temperature, during rated operation of machine 10, of about 99°C, and an inlet flow rate of about 250L/min. As such, when the temperature of the air pushed by cooling fan 42 has a temperature of about 40⁰C, heat exchanger 62 may have an exit temperature of about 86°C and reject about 56.5 kW of heat. [0033] Heat exchanger 64 may be associated with transmission system 24 and embody, for example, a torque converter oil cooler (TCOC). The flow of oil to and/or from torque converter 34 may also flow vertically downward through an inlet on a first end 70 of heat exchanger 64 and exit through an outlet on an opposing second end 72. Heat exchanger 64 may have an inlet temperature, during rated operation of machine 10, of about 117°C, and an inlet flow rate of about 80L/min. As such, when the temperature of the air pushed by cooling fan 42 has a temperature of about 40⁰C, heat exchanger 64 may have an exit temperature of about 94°C and reject about 61 kW of heat.

[0034] Fig. 3 illustrates one exemplary heat exchanger embodiment. Although the embodiment of Fig. 3 will be described as being similar to that of heat exchanger 50 or as a hydraulic oil cooler associated with an internal combustion engine and a construction machine, heat exchangers 48, 62, and 64 could just as easily have the same or similar hardware configuration. It is further contemplated that, although the heat exchanger embodiment of Fig, 3 will be described as an air-to-liquid heat exchanger, it could alternatively be utilized in conjunction with two liquid coolants or two gaseous coolants, if desired.

[0035] Heat exchanger 50 may include a first end cap 74, a second end cap 76, a plurality of tubes 78 extending between first and second end caps 74, 76, and a plurality of fins 80 disposed transversely between layers of tubes 78. Tubes 78 may be substantially hollow straight fluid conduits fabricated from a thermally conductive metal such as aluminum, copper, or stainless steel and extend from first end 58 through first and second end caps 74, 76, to second end 60. Oil from hydraulic implement system 28 may be distributed to flow into tubes 78 at first end 58, and collected from tubes 78 at second end 60 for return to hydraulic implement system 28. In one embodiment, three tubes 78 may be situated in each coplanar row. [0036] Fins 80 may be conductively connected to and disposed between rows of tubes 78. Specifically, a plurality of fins 80, fabricated from a thermally conductive material such as aluminum, copper, or stainless steel may be arranged substantially orthogonal to the length direction of tubes 78 and located between rows of tubes 78 such that air from cooling fan 42 may blow through channels formed between fins 80. As the air flows through the channels and oil through tubes 78, the air may contact fins 80 and/or external surfaces of tubes 78 to conductively and remove heat from the oil contained within tubes 78. A temperature and flow rate of both the air and the oil may affect the magnitude of heat transfer therebetween. [0037] As illustrated in Fig. 4, a plurality of substantially trapezoidal shaped channels 82 may be formed by cooling fins 80. That is, cooling fins 80 may be considered the side wall portions separating each of channels 82. Each fin 80 may be non-parallel relative to an immediately adjacent fin, but parallel with respect to every other fin such that repeating substantially identical channels 82 may be formed. In addition, each fin 80 may be the side wall portion of two immediately adjacent channels 82a and 82b, each of the immediately adjacent channels 82a and 82b being inverted with respect to each other. In this manner, the air flowing through one channel, channel 82a for example, may be in direct contact with an external surface of an upper row of tubes 78, while the air flowing though an adjacent channel, channel 82b for example, may be in direct contact with an external surface of a lower row of tubes 78.

[0038] Each channel 82 may have curvature in a transverse direction. That is, each channel 82 may be formed to have a repeating S-shape 84 that substantially resembles a sine curve oriented in a horizontally transverse plane of each channel 82. In other words, at a first distance along the length of each channel 82, a symmetrically located centerline 86 thereof may be disposed a first distance away from first end cap 74 (referring to Fig. 3), while at a second distance along the length of each channel 82, centerline 86 may be disposed a second distance away from first end cap 74.

[0039] The width "w" of each channel 82 at a bounding surface 88 joining two immediately adjacent fins 80 may vary along the length of each channel 82. That is, each channel 82 may have a height dimension "h" about which two adjacent fins 80 are substantially symmetric. Throughout the length direction of each channel 82, the dimension "h" may remain substantially constant. However, an interior angle θ formed between bounding surface 88 and immediately adjacent fins 80 may change. For example, in the cross-sectional illustration of Fig. 5A, representing a location at a first distance along the length of channels 82 (i.e., at a point substantially midway between adjacent apexes of the sine curve), an interior angle θi formed between bounding surface 88 and immediately adjacent fins 80 may be an obtuse angle. Similarly, in the exemplary cross section of Fig. 5B, representing a location at a second distance along the length of channels 82 (i.e., at an apex portion of the sine curve), an interior angle O₂ formed between bounding surface 88 and immediately adjacent fins 80 may be an acute angle. That is, the width "wi" at an apex of the transverse sine curve in channel 82 may be greater than the width "w₂" at a point substantially midway between apexes. It should be noted that, even taking into account the transverse sine curve, the varying widths of bounding surface 88, and the alternating obtuse-acute nature of the angle θ (i.e., angular orientation of fins 80 with respect to bounding surface 88), the cross-sectional area and, thus, the restriction at any finite location of channel 82 along its length may remain substantially constant. [0040] In an alternate embodiment illustrated in Fig. 6, channels 82 may, instead of or in addition to the transversely oriented sine curve, also have curvature in another direction substantially orthogonal to the length direction of each channel 82. That is, in the direction of the height dimension "h", each channel 82 may be formed to have a repeating S-shape 90 that substantially resembles a sine curve oriented in a vertical plane symmetrically located at any finite location with respect to adjacent fins 80. In other words, at a first distance along the length of each channel 82, bounding surface 88 thereof may be disposed a first distance away from a first row of tubes 78 (referring to Fig. 3), while at a second distance along the length of each channel 82, bounding surface 88 may be disposed a second distance away from the first row of tubes 78.

[0041] The vertical curvature of each channel 82 may be interrupted. Specifically, a segment 92 of bounding surface 88 (i.e., internal and external portions of bounding surface 88) at the convex and concave apexes of each sine curve may be generally flat and substantially parallel with each other. The length of segments 92 may vary and be dependent on the application, the coolant fluids directed through heat exchanger 50, the temperatures of the coolants, and/or the flow rates of the fluids. Industrial Applicability

[0042] The disclosed cooling system may be used in any machine or power system application where multiple heat exchangers must be closely packaged and efficient heat dissipation is important. In particular, the disclosed cooling system may provide unique exchanger packaging strategy that improves dissipation effectiveness within a confined space. The disclosed system also may provide a novel fin arrangement for use with the heat exchangers that maximizes heat transfer, while minimizing flow restriction. The operation of cooling package 32 will now be described.

[0043] During operation of machine 10, the various fluids within engine 12, induction system 22, transmission system 24, and hydraulic implement system 28 may be heated. For example, engine coolant may be circulated through and absorb heat from engine block 14, the external walls of cylinders 16, and/or the cylinder heads for cooling purposes. Air pressurized by compressor 35 may rise in temperature as a result thereof of the pressurization and, when mixed with fuel and combusted, may heat up even more. Pressurized oil passing through the impellers of torque converter 34 may be continuously worked, which may raise the temperature thereof. Similarly, the pressurized oil-used to move work tool 30 may be continuously worked and heated. If unaccounted for, these elevated temperatures could reduce the effectiveness or even result in failure of their respective systems. [0044] In order to maintain proper operating temperatures of the various machine and engine systems, the fluids of each system may be directed through a dedicated heat exchanger for heat dissipation purposes. For example, the air upstream or downstream of compressor 35 may be directed through heat exchanger 48 (ATAAC). The oil from torque converter 34 may be directed through heat exchanger 64 (TCOC). The oil from hydraulic actuator 36 may be directed through heat exchanger 50 (HOC). The coolant from engine 12 may be directed through heat exchanger 62 (radiator). As these fluids flow through their respective heat exchangers, cooling fan 42 may be caused to rotate, thereby generating a flow of air directed first through heat exchangers 48 and 50, and then through heat exchangers 62 and 64. [0045] Because the heat exchanger having the hottest average temperature and greatest heat rejection of one tier of coplanar exchangers is located in series with the hottest portions of the heat exchangers of the other tier, the efficiency of cooling package 32 may be optimized. That is, warmed air may have a significant effect on cold downstream exchangers, but insignificant or at least less of an effect on hotter downstream exchangers because the hotter downstream exchangers may still have a significant thermal differential over the incoming air. In contrast, the colder downstream exchangers, when confronted with warmed air, may have less thermal differential over the air and, thus, may be able to dissipate less heat to the air. [0046] The operation of one exemplary heat exchanger will now be described. As oil is flowing through tubes 78 of heat exchanger 50, air from cooling fan 42 may be directed through channels 82 and absorb heat from fins 80, bounding surface 88, and the outer surfaces of tubes 78. Particles of the air, when directed into each of channels 82, because of the transverse sine curve (referring to Fig. 4), may be caused to collide against fins 80. This collision may result in 3-D motion of the air particles that improves the turbulence mixing effect of heat exchanger 50. And, because the total cross-sectional area at any finite location of channel 82 along its length may remain unchanged, the restriction therethrough may be insignificantly affected. [0047] With respect to the embodiment of Fig. 6, the same generally operation and benefits associated with the embodiment of Fig. 4 also may apply. However, in contrast to the embodiment of Fig. 4, the sine curve of Fig. 6, as described above, may include flat portions 92 at the apexes thereof. As the air particles in the embodiment of Fig. 4 flow toward and collide with an opposing side of the apex, there may be some tendency for the particles to reflect away from bounding surface 88 because of the extreme angle change in trajectory. The flat portions 92 may serve to reduce this extreme angle change and the likelihood of reflection away from bounding surface 88, which may function to improve the heat transfer capability and/or efficiency of heat exchanger 50.

[0048] It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed cooling system without departing from the scope of the disclosure. Other embodiments of the cooling system will be apparent to those skilled in the art from consideration of the specification and practice of the cooling system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.

Claims

ClaimsWhat is claimed is:

1. A cooling system, comprising: a first heat exchanger having a first heat rejection amount; a second heat exchanger substantially coplanar with the first heat exchanger and having a second heat rejection amount greater then the first heat rejection amount; and a third heat exchanger non-coplanar with the first and second heat exchangers and having an inlet temperature and a lower outlet temperature, the third heat exchanger being located such that the portion of the third heat exchanger receiving fluid at the inlet temperature is disposed to also receive a flow of air in series with the second heat exchanger, and the portion of the third heat exchanger discharging fluid at the lower outlet temperature is disposed to receive a flow of air in series with the first heat exchanger.

2. The cooling system of claim 1, wherein the direction that fluid flows through the first heat exchanger is substantially parallel with the direction that fluid flows through the second heat exchanger.

3. The cooling system of claim 2, wherein: the third heat exchanger has a heat rejection amount less than the heat rejections amounts of both the first and second heat exchangers; and the direction that fluid flows through the third heat exchanger is substantially orthogonal to the direction that fluid flows through first and second heat exchangers.

4. The cooling system of claim 3, wherein the fluid at an inlet of the third heat exchanger the fluid at an outlet of the third heat exchanger flows in a direction substantially parallel with the direction that fluid flows through the first and second heat exchangers.

5. The cooling system of claim 3, further including a fourth heat exchanger substantially coplanar with the third heat exchanger and having a heat rejection amount less than the heat rejection amount of the third heat exchanger.

6. The cooling system of claim 5, wherein the fourth heat exchanger has a second inlet temperature and a second lower outlet temperature, the fourth heat exchanger being located such that the portion of the fourth heat exchanger receiving fluid at the second inlet temperature is disposed to also receive a flow of air in series with the second heat exchanger, and the portion of the fourth heat exchanger discharging fluid at the second lower outlet temperature is disposed to receive a flow of air in series with the first heat exchanger.

7. The cooling system of claim 6, wherein the fluid flow through the fourth heat exchanger is in a direction substantially aligned with the direction of fluid flow through the third heat exchanger.

8. The cooling system of claim 5, wherein: the first heat exchanger has a third inlet temperature and a third lower outlet temperature; the second heat exchanger has a fourth inlet temperature and a fourth lower outlet temperature; and the third and fourth heat exchangers are located such that the portions of the first and second heat exchangers receiving fluid at the third and fourth inlet temperatures are disposed to also receive a flow of air in series the third heat exchanger, and the portions of the first and second heat exchangers discharging fluid at the third and fourth lower outlet temperatures are disposed to receive the flow of air in series with the fourth heat exchanger.

9. The cooling system of claim 5, wherein: the first heat exchanger is a radiator associated with an internal combustion engine; and the second heat exchanger is a transmission oil cooler.

10. The cooling system of claim 9, wherein: the third heat exchanger is an air cooler associated with air flow through the internal combustion engine; and the fourth heat exchanger is hydraulic implement oil cooler.

11. The cooling system of claim 5, further including a fan configured generate a flow of air across the first, second, third, and fourth heat exchangers.

12. The cooling system of claim 11, wherein the fan is situated to draw air past an engine and blow the air across the first, second, third, and fourth heat exchangers.

13. A method of cooling, comprising: generating a first flow of pressurized fluid; generating a second flow of pressurized fluid having an average temperature greater than an average temperature of the first flow of pressurized fluid, the second flow of pressurized fluid having substantially the same flow direction as the first flow of pressurized fluid; generating a third flow of pressurized fluid in a direction substantially orthogonal to the first and second flows of pressurized fluid; and directing a flow of air to remove heat from the first, second, and third flows of pressurized fluid, wherein pressurized fluid of the third flow is first cooled by air also directed to cool the second flow of fluid, before the pressurized fluid is cooled by air also directed to cool the first flow of pressurized fluid.

14. The method of claim 13, further including: generating a fourth flow of pressurized fluid; and directing the flow of air to also remove heat from the fourth flow of pressurized fluid, wherein the pressurized fluid of the fourth flow is first cooled by air also directed to cool the second flow of fluid, before being cooled by air also directed to cool the first flow of pressurized fluid.

15. The method of claim 14, wherein a greater amount of heat is removed from the second flow of pressurized fluid than from the first flow of pressurized fluid.

16. The method of claim 15, wherein a greater amount of heat is removed from the third flow of pressurized fluid than from the fourth flow of pressurized fluid.

17. The method of claim 16, wherein: an average temperature of the second flow of pressurized fluid is greater than an average temperature of the first flow of pressurized fluid; and an average temperature of the third flow of pressurized fluid is greater than an average temperature of the third flow of pressurized fluid.

18. A power system, comprising: an internal combustion engine; a fan driven' by the internal combustion engine to generate a flow of air; a radiator configured to circulate a coolant through the engine, the radiator having a first average operating temperature; a transmission oil cooler disposed in substantially the same plane as the radiator and having a second average operating temperature greater then the first average operating temperature; a hydraulic oil cooler having a first inlet temperature and a first lower outlet temperature, the hydraulic oil cooler being located such that the portion of the hydraulic oil cooler receiving fluid at the first inlet temperature is disposed to also receive the flow of air in series with the transmission oil cooler, and the portion of the hydraulic oil cooler discharging fluid at the first lower outlet temperature is disposed to receive the flow of air in series with the radiator; and an air cooler disposed in substantially the same plane as the hydraulic oil cooler and having a second inlet temperature and a second lower outlet temperature, the air cooler being located such that the portion of the air cooler receiving fluid at the second inlet temperature is disposed to also receive the flow of air in series with the transmission oil cooler, and the portion of the air cooler discharging fluid at the second lower outlet temperature is disposed to receive the flow of air in series with the radiator.

19. The power system of claim 18, wherein: the direction that fluid flows through the radiator is substantially parallel with the direction that fluid flows through the transmission oil cooler; the direction that fluid flows through the hydraulic oil cooler and the direction that fluid flows through the air cooler are substantially orthogonal to the direction that fluid flows through the radiator and the transmission oil cooler; and the fluid at an inlet and at an outlet of the air cooler flows in a direction substantially parallel with the direction that fluid flows through the radiator and the transmission oil cooler.

20. The power system of claim 18, wherein: the radiator has a third inlet temperature and a third lower outlet temperature; the transmission oil cooler has a fourth inlet temperature and a fourth lower outlet temperature; and the hydraulic oil cooler and air cooler are located such that the portions of the radiator and transmission oil cooler receiving fluid at the third and fourth inlet temperatures are disposed to also receive the flow of air in series with the air cooler, and the portions of the radiator and transmission oil cooler discharging fluid at the third and fourth outlet temperatures are disposed to receive the flow of air in series with the hydraulic oil cooler.