CA2037093C

CA2037093C - Nested ripple circumferential flow heat exchanger

Info

Publication number: CA2037093C
Application number: CA 2037093
Authority: CA
Inventors: Paul K. Beatenbough; Kris J. Meekins; Clark E. Stohl
Original assignee: Long Manufacturing Ltd
Current assignee: Dana Canada Corp
Priority date: 1990-02-26
Filing date: 1991-02-25
Publication date: 1999-04-06
Anticipated expiration: 2011-02-25
Also published as: JPH04217792A; CA2037093A1; EP0445006A1; DE69103044T2; DE69103044D1; EP0445006B1; JPH07104114B2

Abstract

The invention relates to an improved energy exchange structure, comprising generally parallel plates, joined to define a hollow passageway for the generally circular flow of fluid between an inlet and an outlet, said plates undulating in cross-structure to define obliquely disposed crossing opposing valleys comprised in multiple sets of generally parallel valleys.

Description

20 3~ ~ 3 NESTED RIPPLE CIRCUMFERENTIAL FLOW HEAT EXCHANGER
This invention relates to an improved ripple plate heat exchanger, having particular application in automotive engine oil cooling utilities where high ratios of heat transfer to Soil pressure drop are desired.

BACKGROUND OF THE INVENTION
10With the development of lighter, high revolution, high torque and more compact internal combustion engines there has been increased need for more efficient oil cooling means.
Many auto engine manufacturers have incorporated into their basic engine design the need for oil cooling means in addition 15to that which can be attained through traditional cooling fluid passages integrally molded into the engine block. Some manufacturers have specified the use of non-integral oil coolers which act to cool a flow of oil by means exterior to the engine block. One typical mounting means comprises ~0mounting the oil cooling means at an oil filtering means. To satisfy the demands of the automotive industry, such cooling means must typically be compact, lightweight and capable of high heat transfer efficiency while not adversely reducing oil pressures. Thus, the continuing need to provide lighter and 20~7~93 , "

more efficient heat transfer devices, has occasloned the development of a multiplicity of new designs and configurations in the manufacture of heat transfer devices for use in automotive oil cooling systems.
Edrly externally mounted ~eat transfer devices generally used as oil coolers in automotlve applications typically comprised a continuous serpentine configured tube, with and without fins, mountea exterior to the engine typically in the air stream in front of the radiator or within the coollng system radiator. Oil, such as transmission or engine oil and the llke, is routed to flow through the tube to be cooled.
A cooling medium typically was passed over the tube, for example within a coolant containing radiator or an air cooling separate unit, thus allowing energy exchange from the heated oil in the tube to the cooling medium.
Wlth the need for compact efficiencies oil coolers were later introduced which were mounted on the engine, typically between the engine block and an externally mounted oii fllter assembly, that cooled the oil going to or coming from the fllter by utilizing fluid flow from the engine cooling system.
These filter mounted coolers generally use multiple hollow, generally parallel spaced plate structures between which oil and cooling fluid flows in parallel planes to maximlze heat transfer. Such spaced plate structures may contain flns ~- 2~3 ~ ~93 between the hollow plate structures or are o. ripple plate configuration. In such devices oil flows to the cooler from a port located at or about the filter mount and c'rculates between parallel plates of the cooler. Coolant from the engine cooling system circulates between and/cr about the parallel plates confining the clrculating oll and acts to transfer heat energy from the oil to the coolant. Many variations of the system exist, with oil being filtered first then flowing to the cooling device or the reverse and lG typ~cally wlth coolant flowing from the coollng system Or the engine, usually from the radiator or the water pump, to the coollng device.
one typical characteristic of f,lter mounted oil coolers is that one or both of the two fluids flow in a generally circular direction about the center of the cooler and typically the heat transfer elements, that is the fins or ripples, are typically not aligned in more than one or two directions. We have found that such configuration of the fins or ripples results in areas of decreased heat transfer efficiency to pressure drop within the heat exchanger.
A problem thus continues to exist particularly in optimizlng heat transfer ratios to oil pressure drop within the heat exchanger. With the increased average operating revolutlons of modern engines, coupled with the high torqu~

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and decreased response times, the need for oil cooling devices which are highly efficient and have minimum effect upon the oil pressure of the engine oiling system, have become desirable.

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One object of this invention is to provide energy exchange structures having improved heat transfer.
A further object of the invention is to provide energy exchange structures having reduced internal fluid pressure drop.
Another object of the inven';ion is to provide an automotive oil cooler having reduced internal oil pressure drop A

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A still another object of the lnvention is to provide a method of manufacturing an energy exchange structure havln~
efficient heat transfer and reduced internal fluid pressure drop.
These and other ob~ects of the lnvention are achieved by the invention described as follows:

SUMMARY OP T~IE INVENTION
The invention relates to an improved energy exchange structure, con,prlsing qenerally ~ar~llel opposing plates, joined to define a hollow passageway for the generally circular flow of fluid between an inlet and an outlet, sald opposing plates undulating in cross-structure to define a plurality of opposing valleys extending into the hollow passagcway and arranged ln four or more sets of generally parallel valleys, with each set being arranged oblique angularly to adjacent sets and obllque angled to a circular flow direction within the hollow passageway defined by the joined plates. Sets of valleys of a flrst plate are arranged to cross opposing sets of valleys of a second plate such that the area between opposing valleys of the opposing sets define crossing passages through which the fluid can flow.
The improved automotlve oil coolers of the invention comprise multiple opposing plates, stacked to form a plurality ~ 2~3~3 "" .~

of lnterconnected energy exchange structures for the generally circular flow of oil. Inlets of the energy exchange structures terminate at an inlet header where they are parallel interconnected with other inlets or are serially interconnected with outlets of a second structure. Outlets terminate at an outlet header and also are parallel or serially interconnected wlth outlets or inlets of a second structure.
The interconnected, st~-~ed energy exchange st~uctures pro~lda passage for the flow of oil within the energy exchange structures and passage for the flow of cooling fluid exterior to the energy exchange structures. A preferred cooling fluid flow is ~enerally at an oblique angular direction to the opposing valleys of the opposing plates of the energy exchange structures to enhance energy exchange.
The energy exchange structures may be confined within a tan~ like container wherein a liquid and/or gaseous coolant can be circulated over and between the opposing plates comprising the energy exchange structures, or may be exposed to allow the flow of air or the like thereover. Ti:e periphery of the stacked energy exchange structures may be ~oined to the tank walls to define separated coolant passages which also may be separately connected, para~lel interconnected or serially interconn~cted to coolant inlets and/or outlets.

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"_ The improved automotive oil coolers of the invention are produced by a process wherèin opposing plates, undulating in cross-section to have a plurality of valleys arranged in four or more sets of generally parallel valleys, with each set being arranged oblique angularly to adjacent sets and oblique angled to a circular flow direction within the hollow passageway defined by the joined plates. Valleys of a first plate cross apexes of opposing valleys of a second plate and the area between opposing valleys define crossing passages which are obliquely disposed preferably at from about 5 to about 75 degrees to the circumferential direction of the energy exchange structure. Said first and second plates are joined to form a hollow passageway, comprising a fluid inlet and a fluid outlet, the passageway being arranged to direct fluid entering the passageway from an inlet in a generally circular flow to an outlet. The multiple energy exchange structures can be assembled in series and/or parallel to form the cooler, with an inlet of a first energy exchange structure connected to an inlet or to an outlet from a second energy exchange structure. Typically, it is preferred to assemble two or more groups of parallel connected energy exchange structures with each group in serial arrangement with inlet and outlet headers.

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~ypically the so assembled energy exchange structures are enc3se~. in a tank like container l-avlng a cooling fluld inlet and outlet means. Generally, the external ~olned borders of the opposing pla;es are e~tended in a ~oined flattened plate to provide additional energy exchange surface at the exterior borders of the exchange structure. Such extenslon allows the circulation of coolant around the exterior boundarles of the stacked structures for additional cooling ar.d can also provide con~enlent mean_ for intcr- connecting the exchange str~ctures to stabillze them ~thin the encasing tank.

DESCRIPTION OF ~IIE DRAWINGS
Flg. 1 ic a top perspective view of an oil coole.~ made in accordance with the present invention.
lS Fig. 2 is a bottom perspective vlew of the oil cooler of Fig. 1.
Fig. 3 is a sectional view taken approximately on line 3-3 of Fig. 1.
Flg. 3a is an enlarged sectional vie~ of hollow energy exchange structure 23 of Fig. 3.
Fig. 4 is a sectional view taxen approximately on line 4-4 of Fig. 1.
Fig. S is a perspectlve view of an energy exchange structure made in accordance with the present invention.

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Fig. 6 is a plan view of tlle interior surface of the upper plate of Fig. 5.
Fig. 7 is a plan view of the interior surface of the lower plate of Fig. 5.
S Fig. 8 is a schematic view of another embodiment of the invention.

DETAILED DESCRIPTIOI~ OF T~IE INVENTION
An exemplary embodlment of an automotive oil cooler made according to the invention is illustrated in Figs. 1 and 2.
It should however be understood that the present invention can be utilized in a plurality of other applications whereln an energy exchange structure is desired.
~eferring now to Figs. 1 and 2, therein a typical automotive oil cooler 10 is illustrated which is generally installed between the automotive engine and the oil filter in a typical automotive application. Cooler 10 comprlses canister 11 havlng motor attachment end 12, oil filter attachment end 20, exterior canister side 17 and interior canister slot 14. Motor attachment end 12 comprises oll inlet 13 and motor seal slot 16 which retains oil seal 15, lllustrated in Figs 3 and 4. Exterior canister side 17 of canister 11 comprises coolant inlet 1~ and coolant outlet 19.
Oil filter attachment end 20 comprises oil outlet 21 and oil 203~9~
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filter seal surface 22. Interior canister slot 14 extends from motor attachment end 12 ~hrough oil filter attachme.nt end 20 and provides a slot through which an oil filter can be removab~.y attached to the motor in order to seal the oil cooler and the filter to the motor and provide passage bac~
to the motor of cooled and filtered oil.
Oil cooler 10 comprises a plurality of hollow energy exchanqe structures, contained within canister ll, through which oll flows between oil inlet 13 and oil outlet ~1.
Surrounding at least a portion of the energy exchange 4tructures are hollow pa.ssages through which coolant can flow ln energy exchange relationship with the hollow energy exchange structures from coolant inlet 1~ to coolant outlet 19 .
In a typical operation of the illustrated embodiment, a first, heat energized, fluid such as hot engine oil enters oil cooler 10 through oil inlet 13, flows between opposlng plates through the generally circular passages of a plurallty of hollow energy exchange structures and through cooler motor oil outlet 21 to the inlet of an oil filter~not illustrated).
The cooled oil flows through the oil filter, and i5 dlrected through a hollow, oil fllter attachment shaft (not illustrated) which extends through interlor canister ~lot 14 to the motor. The hollow, oil filter attachment shaft, 2~3~0~3 ,~, ".

enqages the motor and is typically threaded to compressingly attach the oil cooler and filter assemblies to the motor. The shaft thus provides both a means of attachment of the filter and the cooler to the motor and a passageway for cooled and filtered oil flow back to the motor from the filter.
Alternately, it should be understood that the oil can flow in reverse direction from the motor through the attachment shaft, to the filter, through the cooler and back to the motor from the cooler.
The flow of oil through the exchange structures ls directed ~y the angularly dispo ed, multiple sets of generally parallel valleys which extend inwardly to the hollow passageway of the opposing plates. The oil stream is passively separated and mixed by the crossing paths of opposing valleys increasing oil stream contact with opposinq plates of the energy exchange structure. Heat energy from the oil is dissipated to the opposing plates of the energy exchange structures and to any fin plates which may be in contact therewith.
A second fluid flow, typically a liquid coolant such as a 2~ water/antifreeze mixture, flows through coolant inlet 18 such that the coolant flows across the opposing plates and any fin plates that may be in contact therew~th, preferably counter current to the oll flow. Heat energy dlsslpates from the energy exchange structures to the coolant when the heat energy ~037~g3 ",~.
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of the c~olant is less than that of the energy exchange structures. Tlle coolant flows through the canister contalning the energy exchange structures through coolant outlet 19 for recycle through the cooling system.
Referring now to Fig. 3, thereln is illustrated a sectional vlew of the oil cooler of Fig. 1 taken approximately on line 3-3, which illustrates a stacked arranqement of hollow energy exchange structures 23, within canister 11. In Fig. 3a, an energy exchange structure 23 is enlar~ed ar.d illustrated to comprise upper opposing undulating plate 24 and lower opposing undulating plate 25, joined to form exterior joined border 26.
Apexes of inwardly extending valleys 27 of the upper opposing plate 24 cross opposing apexes of inwardly extending valleys 28 of lower opposing plate 25, with the area between apexes of valleys of a plate co~,prising crests 29 in upper plate 24 and crests 30 in lower plate 25. The inwardly extending valleys direct oil flow within the exchange structures along the crests, with crossing valleys continuously effecting a passive separation, mlxing and oblique angularly redirecting of the oil flow stream generally along a circumferential flow direction from energy exchange structure inlet to energy ex~hange structure outlet. The area between stacked energy exchange structures comprlsns passageways also resulting from the undulating plates. Coo}ant flowing through these passageways ls directed along the arrangement of valle~s 27 and 2~. As with the flow of oil, the arrangement of the valleys continuously effects a passive separation, mixing and oblique angularly redirectlng of the coolant stream from coolant inlet to coolant outlet.
In the illustrated embodiment of Fiq. 3, the interior central borders of upper plates 24 and lower plates 25 are conveniently joined through compression rings 31 to provlde structural integrity of the hollow exchange structures and fluid separation from the cooling passages therebetween.
Interior canister slot surface 34, with upper lip 32 and lower lip 33 holds motor attachment end 12 and fllter attachment end 20 ln compressing engagement to join upper plates 24 and lower plates 25, in alternating direct and interspaced relationship with compression rings 31, to eacll other.
Fig. 4 comprises a sectional view of Fig. 1, particularly illustrating oll inlet header 35 and oil outlet header 36.
The-..eat, upper plates from a first stacked energy exchange struct:lre are joined to lower plates of a second energy exchange structure, about the lnterior periphery of the headers, to provide sealed separation of the coolant flow from the oll flow of the exchange structures. It should be understood that though the embodlment illustrates common headers between all inlets and outlets of the energy exchange ~7~ ~3 structure for a parallel oil flow between exchangè structures, the invention specifically contemplates and includes separate headers between outlets and inlets of the stacked exchange structures for series oil flow.
The plates of the exchange structures are joined by any appropriate means that provide a seal of sufficient structural integrity to withstand the pressures generated within the system. Typically braze weld bonding is a preferred embodiment when the materials of construction are stainless steel, copper, brass or aluminum. Appropriate polymeric and ceramic materials may be the materials of choice and joining may comprise appropriate solvents, adhesives, or heat and ultrasonic welding of the materials.
FIG. 5 illustrates a preferred embodiment of the energy exchange structure of the invention comprising four sets of valleys. Therein, energy exchange structure 23 comprises opposing undulating upper plate 24 and undulating lower plate 25. Upper plate 24 comprises inwardly extending valleys 27 and lower plate 25 comprises opposing inwardly extending valleys 28(not shown).
The area between valleys of upper plate 24 comprising crests 29 and the area between valleys of lower plate 25 comprising crests 30(not shown) each of which comprise passages through which oil flows. The opposing plates are joined at their ,. ..
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exterior border 26. In the preferred embodiment illustrated, the exterior border 15 brazed welded to lnsure structural integrity of the seal of the energy exchange structures. The interior central border of the exchange structure comprises compresslon ring 31 to which the plates are ~oined.
The valleys of the opposing plates can be conveniently formed by stamping, embossing, molding or otherwise forming the desired arrangement of valleys into the plates. The valleys ara typically stralght or sllghtly curved and lt is preferred they comprise shortened segments.
Though valleys need not be generally equidistant spaced from adjacent valleys through~ut tlleir length, such ls preferred in many automotive applications. By equldlstant spaced ls meant that the distance between adjacent valleys should be generally the same throughout the valley's length.
It should be understood that preferred equidistant spacinq also does not mean that the d~stance between adjacent valleys need be the same, though such is preferred for many applications.
The area between adjacent valleys comprise ad~acent crests.
Neither adjacent crests nor adjacent valley~ need be of the same wldth. The crests can be in the same plane as the plate, or can be stamped, embossed or otherwise formed to extend above the plane of the plate. It should be understood that ,,,~ . .
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oth~r means well known in the art are contemplated for use in the formation of the valleys and crests, including molding and the like.
Generally the crests and valleys will be at an oblique angle to the circu~ferential direction of the plate.
Preferably, the oblique angle will be from about 5 to about 75 degrees from the circumferential direction of o~l flow between the plates and most preferably from about 15 to about 45 deqrees. ~-Opposing first and second elongated plates, having angularly disposed valleys, are assembled so that the valleys of the first plate cross opposing valleys of the second plate.
It is not essential for the valleys or crests of the first plate to be at the same oblique angle to the longltudlnal direction as those of the second plate, though such is generally preferred. Generally it is preferred that the pattern of a set of valleys of a first plate in an assembled hollow energy exchange structure, be adjacent the reverse mirror lmage of the pattern of a set of valleys of a second plate.
Fig9. 6 and 7 compri5e plan views of the ~nterior fac~ng surfaces of the upper plate 24 and lower plate 25 of Fig. 5.
Fig. 6 lllustrates valleys 27 of upper plate 24, arranged ln four sets so that generally stralght valleys are essentially ~03~0 ~3 ~

equidistant to adjacent valleys throughout their length on the plate. Crests illustrated in this preferred embodiment are of esser.tially equal width, but it should be understood that the invention contemplates and includes configurations wherein crests or valleys of a plate are not equal in width to adjacent crests or valleys.
Fig. 7, illustrates the interior surface of lower plate 25 that faces the interior surface of upper plate 24. Therein, valleys 28 are arranged in four o spaced-apart sets, with valleys in each set being essentially equidistant to adjacent valleys of the set throughout their length and comprising a reverse mirror image of upper plate 24. When upper and lower plates are assembled, facing each other, to form the energy exchange structure of the invention, the valleys of each set of the upper plate cross valleys arranged in reverse mirrored image on the lower plate Fig. 8, comprises a schematic of a configuration of valleys on internal facing surfaces of undulating plates wherein undulations are comprised in five sets of general~y parallel valleys, with each set being arranyed oblique angularly within the hollow passageway. In this embodi~ent the oblique angular direction to the circular flow through the exchanger is not consistent for all sets of valleys to manipulate oil flow through the exchanger.

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Typically, the oil coolers of the lnvention can be manufactured from any convenient materlal that will withstand the corroding effects and internal fluid pressures of the system. Typical materials include the malleable metals, such S as aluminum, copper, steel, stainless steel or alloys thereof and could even include plastics and/or ceramics.
The materials may be internally or externally coated, treated or the like. Typically, it is desirable to use as thin a material as possible to gain maxlmum efficiency in the energy exchange process. ~enerally, each of the components of a cooler are desirably formed from the same materials when they are to be joined together. For example, the plates used to manufacture the energy exchange structures would be typically formed from the same material. It should be under~tood however that it is within the contemplation of the invention to use diverse materlals in the assembly, for example the use of steel or plastics in the canisters or surfaces of the ends of the canister while using other metals, plastics or ceramics in the energy exchange structures.
It should ~ understood that though the illustrated inventlon comprises an automotive oil cooler, it is seen as being applicable to multiple heat exchanger utilities.

Claims

1. An improved energy exchange structure, comprising first and second generally parallel opposing plates joined to define a hollow passageway with a generally circular fluid flow direction between an inlet and an outlet, said opposing plates undulating in cross-section to define a plurality of opposing valleys extending into the hollow passageway and arranged in multiple spaced-apart sets of generally parallel valleys, each set being oblique angled to adjacent sets and to the generally circular fluid flow direction with valleys of the first plate arranged to cross valleys of the second plate such that the area between opposing valleys define crossing passages.

2. The structure of claim 1 wherein each said opposing plate comprises four or more sets of valleys.

3. The structure of claim 1 wherein each said opposing plate comprises five setsof valleys.

4. The structure of claim 1 comprising generally straight valleys.

5. The structure of claim 1 comprising generally curved valleys.

6. The structure of claim 1 wherein the valleys are obliquely disposed at from about 5 to 75 degrees to the direction of fluid flow within the passageway.

7. The structure of claim wherein valleys of a plate are generally equidistant spaced from adjacent valleys throughout their length.

8. The structure of claim 7 comprising valleys of generally equal width.

9. The structure of claim 1 wherein the exterior borders of the plates are joined to form a flat joined plate.

10. The structure of claim 1 wherein sets of valleys are arranged at generally the same oblique angle to the generally circular fluid flow direction of the structure.

11. An improved automotive oil cooler, comprising an energy exchange structure of claim 1.

12. An automotive oil cooler, comprising a plurality of stacked hollow energy exchange structures having inlet and outlet means, said hollow structures comprising first and second generally parallel opposing plates, connected centrally and along elongated edges to define a hollow passage extending in a generally circular direction between said plates, said opposing plates undulating in cross-section to define a plurality of opposing valleys extending into the hollow passageway and arranged in multiple spaced-apart sets of generally parallel valleys, each set being oblique angled to adjacent sets and to the generally circular fluid flow direction, with valleys of the first plate arranged to cross valleys of the second plate such that the area between opposing valleys define crossing passages.

13. The cooler of claim 12 wherein an inlet of a hollow energy exchange structure is connected to a header and an outlet of a hollow energy exchange structure is connected to a header.

14. The cooler of claim 12 wherein an inlet of one hollow energy exchange structure is connected to an outlet of another hollow energy exchange structure.

15. The cooler of claim 12 wherein the stacked arrangement of hollow energy exchange structures is assembled within a hollow structure configured to allow flow of a second fluid about surfaces of the stacked energy exchange structures.

16. A process for forming an improved oil cooler of claim 12 comprising forming plates, undulating in cross-section and having a plurality of valleys arranged in multiple spaced-apart sets of generally parallel valleys, each set being oblique angled to adjacent sets; arranging said plates such that apexes of sets of valleys of a first plate are arranged to cross adjacent apexes of sets of valleys of a second plate; joining said first and second plates centrally and along elongated edges to form an energy exchange structure having a hollow passage extending in a generally circular direction with inlet and outlet means therein and wherein said valleys of said plates are oblique angularly disposed to the circular direction of said passage; and assembling a plurality of energy exchange structures in stacked arrangement.

17. The process of claim 16 wherein said inlet means are connected to a first header and said outlet means are connected to second header.

18. The process of claim 16 wherein the stacked arrangement of hollow energy exchange structures is assembled within a hollow structure configured to allow flow of a second fluid about surfaces of the stacked energy exchange structures.