EP0889299A2 - Heat exchanger having a double pipe construction - Google Patents

Abstract

An outer cylindrical pipe (11) forming a double pipe typeoil cooler (1) is disposed within lines extending from both outersurfaces of each tube (2), which defines the width dimension ofthe tube (2). That is, the double pipe type oil cooler (1) islocated at a position where the flow speed of cooling water ismaximum. Thereby, as the cooling water flows from the tube (2)is used efficiently for cooling, the cooling performance of theoil cooler (1) is further improved. Further, the double pipetype oil cooler (1) is formed into flat shaped double pipe inwhich the longitudinal axis thereof is more than twice as long asthe latitudinal axis thereof, and the latitudinal axis of the oilcooler (1) is smaller than the width dimension of the tube (2).

Description

BACKGROUND OF THEINVENTION1. Field of the Invention:

The present invention relates to a heat exchanger appliedto an oil cooler installed in a vehicle radiator and having adouble pipe construction, in which a circle-like fluid passagethrough which a second fluid flows to be heat exchanged withfirst fluid is formed thereinside.

2. Description of Related Art:

Conventionally, as shown in FIGS. 10 and 11, a double pipetype oil cooler 100 is well known. Thisoil cooler 100 isinstalled in alower tank 102 of a vehicle radiator for coolingvehicle engine cooling water. This oil cooler 100 coolslubrication oil by carrying out heat exchange between the coolingwater introduced from atube 103 of the radiator and thelubrication oil flowing in theoil cooler 100.

Theoil cooler 100 includes an outercylindrical pipe 104,an innercylindrical pipe 105, anoil passage 106, aninner fin107 provided in theoil passage 106, and a connectingmember 109for connecting the outercylindrical pipe 104 to anexternalconnecting pipe 108. The outside wall surface of the outercylindrical pipe 104 contacts the cooling water flowing from thetube 103. The innercylindrical pipe 105 is disposed inside theoutercylindrical pipe 104, and the center axis of the innercylindrical pipe 105 is concentric to that of the outercylindrical pipe 104. Theoil passage 106 is formed between the outercylindrical pipe 104 and the innercylindrical pipe 105.The lubrication-oil flows into theoil cooler 100 through theconnectingpipe 108 and circulates therein.

In theconventional oil cooler 100, as shown in FIGS. 10and 11, the diameter of theoil cooler 100 is set larger than thewidth (WT) of thetube 103, for attaining a sufficient radiationarea. Therefore, the cooling water stagnates around the lowerportion of theoil cooler 100. Thus, the cooling water flowspeed decreases around the lower portion of theoil cooler 100,and the cooling water side heat transmitting efficiency islessened. Further, in the conventional oil cooler, the coolingwater flow flowing from thetube 103 into thelower tank 102 isnot used efficiently for improving the cooling performance of theoil cooler 100.

Here, JP-U-58-46969 discloses a double pipe type oilcooler installed in a radiator tank, which includes crosssectional 8-shaped outer and inner cylindrical pipes. However,in this reference, no relation between the radiator tube and theoil cooler is disclosed.

JP-U-58-524623 discloses a double pipe type oil coolerthat is installed into a radiator tank, and that includes crosssectional flat or rectangular shaped outer and inner cylindricalpipes. In this double pipe type oil cooler, the longitudinalaxis of the oil cooler is arranged perpendicularly relative tothe cooling water flow direction flowing from the tube, and thelatitudinal axis thereof is arranged along the cooling water flowdirection. Therefore, the cooling water stagnates around the bottom portion of the oil cooler. Thus, the cooling water flowspeed decreases around the bottom portion of the oil cooler andthe cooling water side heat transmitting efficiency is lessened.That is, the cooling water flowing from the tube into theradiator tank is not used efficiently. Further, when theradiating area thereof is set the same as the conventionalcylindrical double pipe type oil cooler, the width dimension ofthe tank needs to be large, and the width dimension of theradiator is made large.

JP-U-59-71071 discloses a double pipe type oil coolerinstalled in a radiator tank, which includes cross sectionalelliptic shaped outer and inner cylindrical pipes. Further, JP-A-3-233129discloses a double pipe type oil cooler which includescross sectional substantially U-shaped outer and innercylindrical pipes. In these oil coolers, as the diameter of theoil cooler is larger than the width of the radiator tube, theposition of maximum cooling water flow speed is not usedefficiently for cooling.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a doublepipe type heat exchanger in which an entire heat exchangingperformance is further improved without reducing a heattransmitting area. Another object of the present invention is tominimize the size of an upstream side fluid passage, like a tube,and a downstream side fluid passage, like a downstream side tank.

According to a first aspect of the present invention, a double pipe type heat exchanger is disposed within linesextending from both sides of an upstream side fluid passage,which defines the width dimension thereof. That is, the doublepipe type heat exchanger is located at a position where the flowspeed of a first fluid is a maximum. Thereby, as the first fluidflows from the upstream side fluid passage and is usedefficiently for heat exchanging, the heat exchanging performanceof the entire double pipe type heat exchanger is further improved.

According to a second aspect of the present invention, adouble pipe type heat exchanger is formed into s flat shapeddouble pipe in which the longitudinal axis thereof is more twiceas long as the latitudinal axis thereof, and the latitudinal axisof the heat exchanger is smaller than the width dimension of anupstream side fluid passage. Thus, the outside wall surface areaof the double pipe type heat exchanger contacting the coolingwater can be made large. Thereby, though the latitudinal axis ofthe heat exchanger is set to be smaller than the width dimensionof the upstream side fluid passage, the heat exchangingperformance of the entire heat exchanger is maintained.

BRIEF DESCRIPTION OF THE DRAWINGS

Additional objects and advantages of the present inventionwill be more readily apparent from the following detaileddescription of preferred embodiments thereof when taken togetherwith the accompanying drawings in which:

FIG. 1 is a cross sectional view showing a double pipetype oil cooler in a first embodiment, installed in a lower tank of a vehicle radiator;

FIG. 2 is a cross sectional view showing a cooling waterflow with respect to the oil cooler in the first embodiment;

FIG. 3 is a plan view showing the double pipe type oilcooler according to the first embodiment;

FIG. 4 is a front view showing the double pipe type oilcooler according to the first embodiment;

FIG. 5 is a partial cross sectional view showing thedouble pipe type oil cooler according to the first embodiment;

FIG. 6 is a cross sectional view showing a double pipetype oil cooler in a second embodiment, installed in a lower tankof a vehicle radiator;

FIGS. 7A, 7B are cross sectional views showing double pipetype oil coolers in modifications;

FIGS. 8A, 8B are cross sectional views showing double pipetype oil coolers in modifications;

FIG. 9A is a cross sectional view showing the double pipetype oil cooler in the first embodiment;

FIGS. 9B, 9C are cross section views showing double pipetype oil coolers in modifications;

FIG. 10 is a cross sectional view showing a prior artdouble type oil cooler installed in a lower tank of a vehicleradiator; and

FIG. 11 is a cross sectional view showing a cooling waterflow with respect to the prior art oil cooler.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS(First Embodiment)

Referring to FIGS. 1 and 2, a double pipetype oil cooler1 according to a first embodiment cools lubrication oil for avehicle engine by carrying out heat exchange between thelubrication oil and cooling water for the vehicle engine. Thedouble pipetype oil cooler 1 is installed in a lower tank 3 of avehicle radiator. The lower tank 3 is connected to the lowerends of a plurality oftubes 2 of the radiator disposed at theposition, where the radiator is likely to receive an airgenerated by running dynamic pressure of the vehicle.

Eachtube 2 is made of a metal, such as an aluminum alloy,that has superior heat transmitting performance, and that isformed into a flat oval shape. Thetube 2 forms an upstream sidecooling water passage 4 through which the cooling water flowsdownwardly. When the cooling water flows through the upstreamsidecooling water passage 4, the cooling water is heat exchangedwith the air passing by the outside surface of thetube 2 and iscooled. A corrugated fin (not illustrated) is provided betweeneach pair ofadjacent tubes 2 for improving the heat transmittingperformance.

A lower tank 3 includes a core plate 5 made of aluminumalloy, acapsule 7 made of resin, and a downstream sidecoolingwater passage 8 into which the cooling water flows from theplural tubes 2. Thecapsule 7 is fixed to the core plate 5 bycrimping, through a sealing member 6 such as rubber packing.

The core plate 5 includes a plurality ofinsertion holes5a into which the downstream side ends of theplural tubes 2 are inserted. The downstream side ends of thetubes 2 are brazedwith the core plate 5. Thecapsule 7 is made of resin such asnylon and formed into vessel-shape, that is, the cross sectionalshape thereof is formed into a substantially U-shapedconfiguration. Thecapsule 7 includes two circle-shapedinsertion holes 7a into which anipple 10 of theoil cooler 1 isinserted. The insertion holes 7 are formed on the side wall ofthecapsule 7. Here, thecapsule 7 may be made of metal.

The structure of the double-pipetype oil cooler 1 will bedescribed in more detail with reference to FIGS. 1-5. Thedouble-pipetype oil cooler 1 includes twonipples 10 asconnecting members, an outercylindrical pipe 11, an innercylindrical pipe 12, anoil passage 13 through which thelubrication oil circulates, a coolingwater passage 14 throughwhich the cooling water circulates, and aninner fin 15. Theoutercylindrical pipe 11 is formed to separate intodoublemembers 11a, 11b, and is connected to thenipple 10. The innercylindrical pipe 12 is provided inside the outercylindrical pipe11. Theoil passage 13 is formed between the outercylindricalpipe 11 and the innercylindrical pipe 12. The coolingwaterpassage 14 is formed inside the innercylindrical pipe 12. Theinner fin 15 is disposed inside theoil passage 13.

Eachnipple 10 is inserted into theinsertion hole 7a ofthecapsule 7, and aseal member 16 such as an O-ring is disposedbetween thenipple 10 and the inside wall of thecapsule 7. Anouterperipheral screw portion 19 is formed at the outerperiphery of a cylindrical pipe portion protruding from the outside wall of thecapsule 7. Anut 17 and an externalconnectingpipe 18 are screwed on the outerperipheral screwportion 19. Here, there are two external connectingpipes 18.One is an inlet side external connectingpipe 18, and the otheris an outlet side external connectingpipe 18.

The inlet side external connectingpipe 18 connects to theoil cooler 1 and a torque converter (not illustrated) of avehicle automatic transmission. The outlet side externalconnectingpipe 18 connects to an oil-pump or an oil pan (notillustrated). Here, the oil flows from the torque converter,through theoil cooler 1, and into the oil pump or the oil pan,or flows from the oil pump or the oil pan, through theoil cooler1, and into the torque converter.

The outercylindrical pipe 11 is made of metal, such as analuminum alloy or brass, and formed into a flat shape. The outercylindrical pipe 11 is formed by crimp-connecting a pair ofsaucer-like metal plates 11a, 11b facing each other at the outerperipheries thereof. Themetal plates 11a, 11b include concaveportions, and these concave portions face each other. The outercylindrical pipe 11 is formed into a configuration that is ovalin cross-section, the longitudinal axis direction of which isalong the cooling water flow direction from thetube 2 to thelower tank 3. That is, the latitudinal axis of the oval shape isperpendicular to the cooling water flow direction.

The longitudinal axis length (HO) is more twice as long asthe latitudinal axis length (WO). For example, in the presentembodiment, HO is 3.4 times as long as WO. Referring to FIGS. 2 and 4, the upper and lower ends of the outercylindrical pipe 11are formed into an arc-like portion 20, and the center portion ofthe outercylindrical pipe 11 is formed into a generallyportion21 having a length LS. The outerperipheral pipe 11 is disposedinside the downstream side coolingwater passage 8 in the lowertank 3 in such a manner that acrimp portion 22 is located on thecenter axis of thetube 2. The outercylindrical pipe 11 isfixed to thenipple 10 such that the outercylindrical pipe 11 islocated within lines (dotted chain lines in FIG. 1) extendingfrom the outer surfaces of thetube 2. The width dimension WTbetween these lines is the width dimension of the tube 2 (forexample, the outer diameter of the tube 2).

The innercylindrical pipe 12 is made of a metal, such asan aluminum alloy or brass, and formed into an oval shape that isconcentric to the outercylindrical pipe 11. Theoil passage 13is formed into an oval ring shape, and between the outer andinnercylindrical pipes 11, 12. The coolingwater passage 14opens at both ends of the innercylindrical pipe 11 in the rowingdirection of theplural tubes 2. The cooling water flowing inthe downstream side coolingwater passage 8 flows through thecoolingwater passage 14. Theinner fin 15 is disposed in theoil passage 13 for improving the oil side heat transmittingefficiency.

Operation of the first embodiment will be described withreference to FIGS. 1-5.

When the oil pump is driven by the vehicle engine, thelubrication oil flows through the inlet side external connectingpipe 18, and into theoil passage 13. The lubrication oilcirculates in theoil passage 13, heat exchanges with the coolingwater, and flows out of theoil cooler 1 through the outlet sideexternal connectingpipe 18. Here, as theinner fin 15 isprovided inside theoil passage 13, the oil side heattransmitting efficiency is high.

When the water pump is driven by the vehicle engine, thecooling water flowing from the water jacket of the vehicle engineflows into the upper tank of the radiator. The cooling water isdistributed into eachtube 2, and flows through thetube 2 whilebeing cooled by heat exchanging with cooling air. After that,the cooling water flows from the lower end of thetube 2 and intothe lower tank 3.

The cooling water is evenly divided by thecrimp portion22 of theoil cooler 1 into both sides of the outercylindricalpipe 11. Theoil cooler 1 is disposed at the position where theflow speed of the cooling water is maximum, and has thestraightportion 21. Thus, the cooling water contacting the outside wallsurface of the outercylindrical pipe 11 flows smoothly withoutstagnating. Thereby, water side heat transmitting efficiency isfurther improved, and the lubrication-oil circulating in theoilpassage 13 is cooled efficiently.

As described above, in the present embodiment, theoilcooler 1 is located at the position where the flow speed of thecooling water is maximum. That is, theoil cooler 1 is disposedwithin lines extending from the outer surfaces of thetube 2.The width dimension WT between these lines is the width dimension of the tube 2 (for example, the outer diameter of the tube 2).As the cooling water flowing from eachtube 2 is used efficientlyfor cooling, the radiating performance of theentire oil cooler 1is further improved.

Theoil cooler 1 is formed into an oval flat shaped doublepipe in which the longitudinal axis (HO) is more than twice aslong as the latitudinal axis (WO), and the latitudinal axis oftheoil cooler 1 is smaller than the outer diameter of thetube 2.Thus, the outside wall surface area contacting the cooling watercan be made large. Thereby, though the latitudinal axis (WO) oftheoil cooler 1 is set to be smaller than the outer diameter(WT) of thetube 2, the radiating performance of theoil cooler 1is maintained.

When the radiating area of theoil cooler 1 is the same asthe conventional cylindrical shaped double pipe oil cooler,because the longitudinal axis length (HO) along the longitudinaldirection of thetube 2 is more than twice as long as thelatitudinal axis length (WO) perpendicular to the longitudinaldirection of thetube 2, the width dimensions of thetube 2 andthe lower tank 3 are maintained, thereby maintaining the widthdimension of the radiator. Here, when the width dimension of thelower tank 3 is set substantially the same as that of thetube 2,theoil cooler 1 can be disposed inside the downstream side tank.As a result, the width dimension of the downstream side tank,such as a lower tank 3, can be downsized, thereby downsizing thewidth dimension of the radiator.

In the present embodiment, theoil cooler 1 is disposed inside the lower tank 3 of the down-flow tyke radiator. However,theoil cooler 1 may be provided inside the downstream side tankof a cross-flow type radiator instead. The flow speed of thecooling water flowing from each tube in the cross-flow typeradiator is higher than that in the down-flow type radiator,because the number of tubes in the cross-flow type radiator issmaller than that of the down-flow type radiator. Further, whenan engine load is high, the flow speed of the cooling waterflowing from each tube is high, because the flow amount of thecooling water circulating in the radiator increases. Therefore,when theoil cooler 1 of the present embodiment is used underthese conditions, the cooling water side heat transmittingefficiency is improved more than under the condition in thepresent embodiment, and the radiating performance of theentireoil cooler 1 is further improved.

(Second Embodiment)

According to a second embodiment, as shown in FIG. 6, thedouble pipetype oil cooler 1 is installed in the lower tank 3 ofthe radiator.

In the second embodiment, theoil cooler 1 is disposedinside the lower tank 3 of the down flow type radiator in whichthetubes 2 are arranged in two rows in a front and reardirection of the vehicle. Here, the inner fin provided in theoil passage 13 is not illustrated in FIG. 6. The latitudinalaxis length (WO) of theoil cooler 1 is set shorter than thewidth length (WT) of thetubes 2 arranged in two rows. Theoilcooler 1 is disposed inside the lower tank 3 in such a manner that the outercylindrical pipe 11 is located within lines (onedotted chain lines in FIG. 6) extending from the outside surfacesof thetubes 2. The width dimension WT between these lines isthe width dimension between the outside surfaces of thetubes 2arranged in two rows. The upper end lower ends of theoil cooler1 are formed into a shape that is half elliptic in cross section.

(Modifications)

In the above embodiment, the heat exchanger of thepresent invention is applied to an oil cooler for cooling thetorque converter oil of the vehicle automatic transmission. Inaddition, the heat exchanger may be applied for coolinglubrication-oil for an engine installed into a vehicle, ship,air-plane, or railroad vehicle.

Further, the heat exchanger of the present invention maybe applied to a refrigerant condenser to carry out a heatexchange between the refrigerant and cooling medium forcondensing the refrigerant, or a refrigerant evaporator to carryout a heat exchange between the refrigerant and heating mediumfor evaporating the refrigerant. The heat exchanger may beapplied for carrying out a heat exchange between a first gasflowing outside the outer cylindrical pipe and a second gasflowing inside the outer cylindrical pipe, and may be applied forheat exchanging between a liquid flowing outside the outercylindrical pipe and a gas flowing inside the outer cylindricalpipe.

In the above-described embodiments, theoil cooler 1 isformed into an oval shape in cross section. However, as shown in FIGS. 7A, 7B, theoil cooler 1 may instead be formed into a semi-ellipticalshape having astraight portion 21, or into a simpleelliptical cross-sectional shape.

Further, as shown in FIGS. 8A, 8B, theoil cooler 1 may beformed into a pentagonal shape having astraight portion 21, or atrianglular shape having astraight portion 21 in cross section.Further, theoil cooler 1 may be formed into other polygon shapessuch as a rectangular-shape.

In the above-described embodiments, theoil cooler 1 is,as shown in FIG. 9A, located within the outer diameter (WT) ofthetube 2. However, as shown in FIG. 9B, theoil cooler 1 maybe located within the inner diameter (WT) of thetube 2 instead.That is, the width dimension of thetube 2 may be based on eitherthe outer diameter or the inner diameter of thetube 2.

Further, as shown in FIG. 9C, the width dimension (WT) maybe based on the width of lines elongating from the center of thewall forming thetube 2 in the thickness direction thereof. Here,when the downstream side end of thetube 2 is expanded as shownin FIG. 9C, it is preferable that the width dimension of thetube2 is based on the outer diameter of thetube 2, because thecooling water flows from the downstream side end of thetube 2into the lower tank 3 while expanding.

The above-described embodiments disclose, as an example, adouble pipetype oil cooler 1 installed in a vehicle radiator inwhich atube 2 is used as an upstream side cooling water passagepipe, and a lower tank 3 is used as a downstream side coolingwater passage pipe. In addition, this heat exchanger may be applied to a triple pipe type heat exchanger (triple pipe typeoil cooler) having an inlet side passage as the upstream sidepassage and an outermost cylindrical pipe as the downstream sidepassage.

Further, a metal pipe, resin pipe or rubber hose may beused as the upstream side passage. A metal tank, tube, oil-panshaped vessel, metal pipe or resin pipe may be used as thedownstream side passage. Here, the upstream side passage may beformed into a circlular, polygonal, or flat shape such as anellipse, an oval, a rectangle or the like.

Claims (7)

1. A double pipe type heat exchanger (1) disposed in adownstream side fluid passage (8) into which a first fluid flowsfrom an upstream side fluid passage (4), which includes a ringlike-passage (13) through which a second fluid to be heatexchanged with the first fluid flows, wherein

   said double pipe type heat exchanger (1) is disposedwithin lines extending from both sides of said upstream sidefluid passage (4), which defines a width of said upstream sidefluid passage (4),

   said double pipe type heat exchanger (1) is formed into ashape that is flat in cross section, and has a longitudinaldirection length that is perpendicular to a width direction ofsaid upstream side fluid passage is longer than a latitudinaldirection length thereof, and

   the latitudinal direction length of said double pipe typeheat exchanger (1) is shorter than a width dimension of saidupstream side fluid passage (4).
2. A double pipe type heat exchanger (1) according toclaim 1, wherein said double pipe type heat exchanger (1) isformed into a polygonal cross-sectional shape, which has alongitudinal axis along a flow-direction of the first fluidflowing from said upstream side fluid passage (4) into saiddownstream side fluid passage (8) and a latitudinal axisperpendicular to the flow-direction of the first fluid.
3. A double pipe type heat exchanger (1) according toclaim 1, wherein said double pipe type heat exchanger (1) isformed into an elliptical cross-sectional shape, which has alongitudinal axis along a flow-direction of the first fluidflowing from said upstream side fluid passage (4) into saiddownstream side fluid passage (8), and a latitudinal axisperpendicular to the flow-direction of the first fluid.
4. A heat double pipe type heat exchanger (1)according to claim 1, wherein said double pipe type heatexchanger (1) is formed into an oval cross-sectional shape, whichhas a longitudinal axis along a flow-direction of the first fluidflowing from said upstream side fluid passage (4) into saiddownstream side fluid passage (8), and a latitudinal axisperpendicular to the flow-direction of the first fluid.
5. A double pipe type heat exchanger (1) according toclaim 2, wherein said longitudinal axis is more than twice aslong as said latitudinal axis.
6. A double pipe type heat exchanger (1) according toclaim 1, wherein

   said upstream side fluid passage (4) includes a pluralityof tubes (2) forming an upstream side cooling water passage (4)therein,

   said downstream side fluid passage (8) includes adownstream side tank (3) into which a cooling water flows as the first fluid, and which forms a downstream side cooling waterpassage (8) a volume thereof is larger than that of said upstreamside cooling water passage (4),

   said double pipe type heat exchanger (1) is used as adouble pipe type oil cooler (1) disposed in a rowing direction ofsaid plurality of tubes (2),

   said double pipe type oil cooler (1) includes anelliptically shaped outer cylindrical pipe (11) as an outsidewall surface thereof that contacts the cooling water, anelliptically shaped inner cylindrical pipe (12) disposed insidesaid outer cylindrical pipe (11), a center axis of which isconcentric to a center axis of said outer cylindrical pipe (11),an oil passage (13) formed between said outer cylindrical pipe(11) and said inner cylindrical pipe (12) and performing as saidring like-passage (13), and a connecting portion for connectingsaid outer cylindrical pipe (11) to an external connecting pipe(18).
7. A double pipe type heat exchanger (1) according toclaim 6, wherein

   said outer cylindrical pipe (11) is formed by crimp-connectinga pair of saucer-like plates (11a, 11b) facing eachother at outer peripheries thereof, and said plates (11a, 11b)include concave portions facing each other, and

   said outer cylindrical pipe (11) is disposed in saiddownstream side tank (3) in such a manner that a crimp portion(22) thereof is located on a center axis of said tube (2).

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