Patent Publication Number: US-2013228307-A1

Title: Heat exchanger

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a vehicle heat exchanger that performs heat exchange between a first heat carrier and a second heat carrier that flow between stacked plates. 
     2. Description of Related Art 
     Published Japanese Translation of PCT application No. 2007-518958 (JP-A-2007-518958), Japanese Patent Application Publication No. 2000-310497 (JP-A-2000-310497), and Japanese Patent Application Publication No. 2000-283661 (JP-A-2000-283661), for example, all describe heat exchangers in which plates are stacked together. In JP-A-2007-518958, JP-A-2000-310497, and JP-A-2000-283661, various heat exchangers that improve heat exchanger safety, the ease of assembling a plurality of plates that form the heat exchanger, and the ability to ensure the rigidity of a plurality of plates and the like are proposed. 
     A stacked vehicle heat exchanger (such as a transmission fluid cooler) has also been proposed that has dish-shaped plates (i.e., a cup plates), of which the peripheral edge portions are fixed in a liquid-tight manner when stacked, formed such that a first layered space into which a first heat carrier (such as transmission fluid) is introduced and a second layered space into which a second heat carrier (such as coolant) is introduced, are formed alternately between them. This stacked vehicle heat exchanger performs heat exchange between the first heat carrier and the second heat carrier. This kind of vehicle heat exchanger is provided with a base plate that serves as a base when the cup plates are stacked together in order, for example. That is, in this kind of vehicle heat exchanger, cup plates are formed (i.e., assembled) stacked together in order on the base plate. At this time, in order to uniquely determine the relative position of the base plate and the cup plate that abuts against (i.e., is stacked directly on) this base plate, shapes for positioning, for example, must be provided on each. However, such shapes for positioning may affect the mountability to the vehicle. While it is possible to perform positioning by providing a recessed portion on one and a protruding portion on the other, these shapes may protrude outside of the vehicle heat exchanger, or if this is avoided, may conversely become protruding portions that protrude toward the layer side of the heat carrier and thus impede the flow of the heat carrier. In this way, there is room for innovation with respect to the positioning of the base plate and the cup plate. These issues are not well-known. 
     SUMMARY OF THE INVENTION 
     The invention provides a vehicle heat exchanger capable of improving mountability in a vehicle. 
     A first aspect of the invention relates to a vehicle heat exchanger. This vehicle heat exchanger includes a plurality of cup plates that are formed such that a first layered space into which a first heat carrier is introduced and a second layered space into which a second heat carrier is introduced are formed alternately between the plurality of cup plates when the plurality of plates are stacked, and in which peripheral end portions of the plurality of cup plates are fixed together in a liquid-tight manner; and a base plate that is thicker than the cup plates and on which the cup plates are stacked in order. The vehicle heat exchanger performs heat exchange between the first heat carrier and the second heat carrier. A positioning protruding portion that protrudes toward a side where there is an end cup plate that contacts the base plate and is to be fitted into a positioning hole for positioning the end cup plate with respect to the base plate, formed through the end cup plate, from among the stacked cup plates, is formed in the base plate in a position facing, in a stacking direction of the cup plates, a heat carrier flow hole portion provided in the plurality of cup plates for introducing the heat carrier into a layered space that contacts the base plate, from among the first layered space and the second layered space. 
     Accordingly, a positioning protruding portion that protrudes toward an end cup plate that contacts the base plate and is to be fitted into a positioning hole for positioning the end cup plate with respect to the base plate, formed through the end cup plate, from among the stacked cup plates, is formed in the base plate in a position opposite, in the stacking direction, a heat carrier flow hole portion provided in the plurality of cup plates for introducing the heat carrier into a layered space that contacts the base plate, from among the first layered space and the second layered space. As a result, the positioning hole formed in the end cup plate and the positioning protruding portion formed on the base plate make it possible to appropriately position the end cup plate and the base plate relative to one another, while avoiding a protruding shape that protrudes out to the outside, opposite the end cup plate side, of the base plate. Accordingly, the mountability (or the degree of freedom with regards to mounting) of the heat exchanger to the vehicle can be improved. In particular, the heat carrier flow hole portions formed on the cup plates other than the end cup plate are provided in positions opposite, in the stacking direction, the positioning hole formed in the end cup plate, i.e., the holes of the cup plates are provided in the same positions, so when the thicknesses of the cup plates that form the same layered spaces as that of the end cup plate are the same, these cup plates can be treated as common parts, which enables productivity to be improved. 
     The positioning protruding portion formed on the base plate may be formed in a shape that protrudes no more than a thickness of the end cup plate, toward a side where there is a layered space that contacts the base plate. Accordingly, the flow of a heat carrier introduced into the flow layer that contacts the base plate is impeded as little as possible, so cooling performance improves, compared to a case in which the positioning protruding portion is a shape that protrudes toward the side with the flow layer that contacts the base plate, or a case in which the positioning protruding portion is a shape that cuts through the layered space and abuts against the cup plate that is stacked on the base plate after the end cup plate in order to support that cup plate. 
     The end cup plate may be made thicker than the cup plates other than the end cup plate. Accordingly, positioning strength can be adequately ensured even if the shape for determining the relative position with respect to the base plate is a simple hole that has not been burred (i.e., formed with a cylindrical surface), for example. 
     A thickness of the end cup plate may be a predetermined thickness set in advance as a thickness that does not require an annular protrusion to be formed by burring at the positioning hole in order to ensure strength. Accordingly, positioning strength is able to be adequately ensured without forming an annular protrusion for positioning by burring on the end cup plate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features, advantages, and technical and industrial significance of exemplary embodiments of the invention will be described below with reference to the accompanying drawings, in which like numerals denote like elements, and wherein: 
         FIG. 1  is an example of a block diagram schematically showing the structure of a cooling system provided in a vehicle; 
         FIG. 2  is a sectional view of a heat exchanger shown in  FIG. 1 ; 
         FIG. 3  is a sectional view of another heat exchanger to which the invention may be applied; 
         FIG. 4  is a sectional view of a reference example (related art) of a heat exchanger when another fluid side cup plate structure is employed as it is as an end fluid side cup plate; and 
         FIG. 5  is a sectional view of another reference example (other related art) of a heat exchanger. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     In the invention, the first heat carrier is preferably transmission fluid, the second heat carrier is preferably coolant, and the vehicle heat exchanger is preferably a transmission fluid cooler capable of cooling at least the transmission fluid. 
     Also, the transmission fluid is preferably hydraulic fluid (transmission fluid) that can be used in a vehicular automatic transmission, for example. More specifically, this hydraulic fluid may be, for example, well-known hydraulic fluid (ATF: Automatic Transmission Fluid) used in a planetary gear type automatic transmission or a synchronous mesh twin shaft parallel axis-type automatic transmission or the like, well-known hydraulic fluid (CVTF) used in a belt-type continuously variable transmission (belt-type CVT) or a traction-type continuously variable transmission or the like, well-known hydraulic fluid used in an automatic transmission for a hybrid vehicle that functions as a so-called electric continuously variable transmission that includes a differential mechanism and an electric motor, or well-known hydraulic fluid used in an automatic transmission mounted in a so-called parallel hybrid vehicle that includes an electric motor capable to transmitting power to an engine shaft and an output shaft or the like. 
     Also, the coolant is preferably coolant that can be used to cool an internal combustion engine such as a gasoline engine or a diesel engine, for example, and that is cooled by heat exchange being performed with the outside air by a well-known radiator. 
     Hereinafter, example embodiments of the invention will be described in detail with reference to the accompanying drawings. 
       FIG. 1  is a block diagram schematically showing the structure of a cooling system  20  provided in a vehicle  10 . In  FIG. 1 , the cooling system  20  includes, for example, a radiator  30 , a thermostat  40 , a water pump  50 , a heater core  60 , and a vehicle heat exchanger (hereinafter, referred to as “heat exchanger”)  70  to which the invention may be applied. The solid arrows in  FIG. 1  indicate the flow of coolant Clt, and the broken arrows indicate the flow of transmission fluid Fld (hereinafter, referred to as “fluid Fld”). 
     The radiator  30  receives coolant Clt for an engine  100  that flows out from an outlet  102  of a water jacket of the engine  100  mounted in the vehicle  10 , cools the coolant Clt through heat exchange with outside air, and discharges the cooled coolant Clt out from an outlet  34  into an inlet  42  of the thermostat  40 . 
     Until the coolant Clt becomes equal to or greater than a predetermined temperature, for example, the thermostat  40  closes a value on the inlet  42  side to prevent the coolant Clt from flowing from the inlet  42  to an outlet  44 . On the other hand, when the coolant Clt becomes equal to or greater than the predetermined temperature, for example, the thermostat  40  opens the valve on the inlet  42  side to allow the coolant Clt to flow from the inlet  42  to the outlet  44 , from which the coolant Clt then flows out to the water pump  50 . Also, the thermostat  40  receives, from an inlet  46 , coolant Clt that flows through a bypass flow path  104  in the water jacket of the engine  100 , and channels this coolant Clt from the outlet  44  to the water pump  50 . Also, the thermostat  40  receives, from an inlet  48 , coolant Clt that flows through the heater core  60 , and channels this coolant Clt from the outlet  44  to the water pump  50 . 
     The water pump  50  is provided in the engine  100 , for example, and draws in coolant Clt via the thermostat  40  and supplies it to the water jacket of the engine  100  that channels the coolant Clt to various parts. 
     The heater core  60  receives coolant Clt that flows out from an outlet  106  of the water jacket of the engine  100 , and performs heat exchange between this coolant Clt and air, thereby generating warm air. 
     The heat exchanger  70  includes a coolant inlet  72  that receives coolant Clt that flows out from an outlet  108  of the water jacket of the engine  100 , a coolant outlet  74  that channels the coolant Clt to the heater core  60  after it flows through the inside of the heat exchanger  70  itself, a fluid inlet  76  that receives fluid Fld that flows out from a vehicular automatic transmission (hereinafter, referred to as “automatic transmission”)  110 , and a fluid outlet  78  that channels this fluid Fld to the automatic transmission  110  after it flows though the inside of the heat exchanger  70  itself. The heat exchanger  70  structured in this way performs heat exchange between the fluid Fld that serves as a first heat carrier that is received from the fluid inlet  76 , and the coolant Clt that serves as a second heat carrier that is received from the coolant inlet  72 . 
     With the cooling system  20  structured in this way, the coolant Clt that flows out from the water jacket of the engine  100 , for example, is returned to the water jacket by the water pump  50  through the heater core  60  and the heat exchanger  70 . Also, for example, when the valve of the thermostat  40  is closed, the coolant Clt that flows out from the water jacket of the engine  100  flows through the bypass flow path  104  and is returned to the water jacket by the water pump  50 . In addition, for example, when the valve of the thermostat  40  is open, the coolant Clt that flows out from the water jacket of the engine  100  flows through the radiator  30  and is returned to the water jacket by the water pump  50 . 
     Also, in the heat exchanger  70 , for example, when it is cold (during warm-up), heat is transferred from coolant Clt that has been warmed by the engine  100  to the fluid Fld, so that the fluid Fld is warmed quickly, which in turn promotes warm-up of the automatic transmission  110 , thereby improving fuel efficiency. On the other hand, after warm-up, heat is transferred to the coolant Clt from the fluid Fld that has been warmed by the automatic transmission  110 , so the fluid Fld is cooled, and thus, the automatic transmission  110  is cooled. 
       FIG. 2  is a sectional view of the heat exchanger  70 . In  FIG. 2 , the heat exchanger  70  includes, in addition to the coolant inlet  72 , the coolant outlet  74 , the fluid inlet  76 , and the fluid outlet  78  described above, fluid side cup plates  80  that serve as first cup plates, coolant side cup plates  82  that serve as second cup plates, a base plate  86  that serves as an end plate that abuts against a cup plate (for example, a fluid side cup plate  80 ) on one side in the stacking direction of a core main body  84  formed by a stack of fluid side cup plates  80  and coolant side cup plates  82 , and a top plate  88  that serves as an end plate that abuts against a cup plate (for example, a coolant side cup plate  82 ) on the other side in the stacking direction of the core main body  84 . The fluid side cup plates  80 , the coolant side cup plates  82 , and the top plate  88  are each formed by a thin metal plate. Also, the base plate  86  is a thick metal plate (for example, an aluminum plate that is sufficiently thicker than the fluid side cup plates  80 ) that serves as the base when the fluid side cup plates  80  and the coolant side cup plates  82  are stacked in order. This base plate  86  functions as a strengthening member for mounting the heat exchanger  70  to the vehicle  10  (for example, to the automatic transmission  110 ). In  FIG. 2 , for the sake of convenience, the cross-section passing through the center of the coolant inlet  72  and the cross-section passing through the center of the fluid inlet  76  are shown on the same plane. Also, the coolant outlet  74  and the fluid outlet  78  are of course provided on the surface of the top plate  88 , just like the coolant inlet  72  and the fluid inlet  76 . 
     In the fluid side cup plates  80 , coolant flow hole portions  80   a  that allow the coolant Clt to flow and correspond to the coolant inlet  72  and the coolant outlet  74 , and fluid flow hole portions  80   b  that allow the fluid Fld to flow and correspond to the fluid inlet  76  and the fluid outlet  78 , are formed in an aluminum plate that is approximately 0.2 mm to 0.5 mm thick, for example, by press-forming. Also, in the coolant side cup plates  82 , coolant flow hole portions  82   a  that allow the coolant Clt to flow and correspond to the coolant inlet  72  and the coolant outlet  74 , and fluid flow hole portions  82   b  that allow the fluid Fld to flow and correspond to the fluid inlet  76  and the fluid outlet  78 , are formed in an aluminum plate that is approximately 0.2 mm to 0.5 mm thick, for example, by press-forming. 
     Also, the plurality of fluid side cup plates  80  and coolant side cup plates  82  are formed (i.e., assembled) in a stacked manner such that fluid flow layered spaces (hereinafter, referred to as “fluid flow layers”)  90  that serve as first layered spaces into which the fluid Fld is introduced, and coolant flow layered spaces (hereinafter, referred to as “coolant flow layers”)  92  that serve as second layered spaces into which the coolant Clt is introduced, are formed alternately between them. The plurality of fluid side cup plates  80  and coolant side cup plates  82  are fixed together in a liquid-tight manner at their peripheral edge portions by brazing. That is, the fluid side cup plates  80  form the fluid flow layers  90  and the coolant side cup plates  82  form the coolant flow layers  92 , by the fluid side cup plates  80  and the fluid flow layers  90  being alternately stacked together. The fluid flow layers  90  are also flow paths (i.e., passages) for the fluid Fld, and the coolant flow layers  92  are also flow paths for the coolant Clt, so the heat exchanger  70  is a stacked vehicle heat exchanger that performs heat exchange between the fluid Fld in the fluid flow layers  90  and the coolant Clt in the coolant flow layers  92 . 
     Inner fins  94  that serve as fins that abut against the fluid side cup plates  80  and the coolant side cup plates  82  are provided across the entire fluid flow layers  90 , inside the fluid flow layers  90 . Also, a plurality of individual convex protrusions  96  that protrude out toward the coolant flow layers  92  and abut against the fluid side cup plates  80  are formed at approximately equal density, for example, on the coolant side cup plates  82 . The inner fins  94  and the convex protrusions  96  are both provided to improve heat-transfer performance during heat exchange performed between the fluid FM and the coolant Clt. In this way, the inner fins  94  and the convex protrusions  96  are both structures that perform heat exchange between the fluid Fld and the coolant Clt, but their structures for performing heat exchange are different with the fluid side cup plates  80  and the coolant side cup plates  82 . In addition, the fluid side cup plates  80  and the coolant side cup plates  82  are both formed with thin metal plates, so the inner fins  94  and the convex protrusions  96  are both provided to ensure strength with respect to a load in the stacking direction in particular. The convex protrusions  96  are formed by press-forming the coolant side cup plates  82 , for example. In other words, the convex protrusions  96  are depressions (i.e., dimples) formed by press-forming the coolant side cup plates  82 . 
     Therefore, in the heat exchanger  70  of this example embodiment, the structure of the convex protrusions  96  is used and the structure of the inner fins  94  is not used, on the coolant side cup plates  82  (in the coolant flow layers  92 ). Therefore, the height of the convex protrusions  96  (i.e., the dimension of the amount that the convex protrusions  96  protrude out in the stacking direction from the surface of the flat portion on the coolant flow layer  92  side of the coolant side cup plates  82 ) that corresponds to the thickness dimension in the stacking direction of the coolant flow layers  92  is set to a smaller value than the height in the stacking direction of the inner fins  94  that corresponds to the thickness dimension in the stacking direction of the fluid flow layers  90 . For example, the height of the convex protrusions  96  (i.e., the thickness of the coolant flow layers  92 ) is obtained through testing (or by design) in advance and set taking into account the number and formation positions of the convex protrusions  96 , and the heat balance between the fluid side heat release amount Qf and the coolant side heat release amount Qc. 
     As described above, the fluid flow layers  90  and the coolant flow layers  92  are set to thicknesses with different thickness dimensions in the stacking direction. Also, the shape of the fluid side cup plates  80  and the shape of the coolant side cup plates  82  are formed different from each other, such that fluid flow layers  90  and coolant flow layers  92  of different thicknesses are formed (matching each of the different thicknesses, for example). For example, flange portions formed on the coolant flow hole portions  80   a  of the fluid side cup plates  80  and on the fluid flow hole portions  82   b  of the coolant side cup plates  82 , respectively, protrude in the stacking direction corresponding to the fluid flow layers  90  and the coolant flow layers  92 , respectively, that have different thicknesses. Also, outer wall portions  80   c  of the fluid side cup plates  80  and outer wall portions  82   c  of the coolant side cup plates  82  protrude out in the stacking direction corresponding to the fluid flow layers  90  and the coolant flow layers  92 , respectively, that have different thicknesses, while also protruding out the same amount in the stacking direction corresponding to the liquid-tight brazing between the plates when stacked. 
     In the heat exchanger  70 , with the base plate  86  as the lowest level, the core main body  84  is formed by stacking the fluid side cup plate  80 , the inner fins  94 , the coolant side cup plate  82 , the fluid side cup plate  80 , and the inner fins  94 , . . . in this order from the base plate  86  upward, and the top plate  88  is stacked on top as the highest level. Also, the heat exchanger  70  is manufactured by brazing these together in a liquid-tight manner in a brazing furnace, for example, and then a complete inspection is performed after manufacturing (for example, an inspection is performed for fluid Fld and coolant Clt leaks). 
     Here, the coolant flow hole portions  80   a , the fluid flow hole portions  80   b , the coolant flow hole portions  82   a , and the fluid flow hole portions  82   b  are formed in predetermined shapes that enable the stacked plates to be brazed together in a liquid-tight manner, while serving as positioning holes when alternately stacking the fluid side cup plates  80  and the coolant side cup plates  82  together. For example, annular protrusions that are the inner peripheral edges of the fluid flow hole portions  80   b  and are burred (i.e., formed with a cylindrical surface) so as to protrude out toward the coolant side cup plate  82  side are brazed in a liquid-tight manner while fit into the fluid flow hole portions  82   b  on which flange portions that protrude out toward the fluid side cup plate  80  side are formed. Also, annular protrusions that are the inner peripheral edges of the coolant flow hole portions  82   a  and are burred so as to protrude out toward the fluid side cup plate  80  side are brazed in a liquid-tight manner while fit into the coolant flow hole portions  80   a  on which flange portions that protrude out toward the coolant side cup plate  82  side are formed. 
     In order to uniquely determine the relative positions of the base plate  86  and the end fluid side cup plate  80  that is contacting the base plate  86 , from among the stacked cup plates, (hereinafter, the end fluid side cup plate  80  that contacts the base plate  86  will be referred to as “fluid side cup plate  81 ”) when the fluid side cup plates  80  and the coolant side cup plates  82  are stacked in order on the base plate  86 , a shape for positioning must be provided on each of the plates.  FIG. 4  is a sectional view of a reference example (related art) of a heat exchanger  170  when a fluid side cup plate  80  is employed as it is as an end fluid side cup plate. In  FIG. 4 , the fluid flow hole portions  80   b  also serve as positioning holes when stacking the fluid side cup plates  80  onto the base plate  86 . Therefore, a positioning recessed portion  86   a  corresponding to annular protrusions  80   b   1  that are burred on the fluid flow hole portions  80   b  and protrude toward the base plate  86  side is formed by press-forming, for example, on the base plate  86 , such that the annular protrusion  80   b   1  will fit into the base plate  86 . As a result, a protrusion toward the outside, opposite the fluid side cup plate  80  side, is produced on the positioning recessed portion  86   a , which may affect the mountability of the heat exchanger  170  to the vehicle  10  (e.g., the automatic transmission  110 ). In other words, the degree of freedom when mounting the heat exchanger  170  to the vehicle  10  may decrease. It should be noted that the annular protrusions  80   b   1  must be formed to ensure positioning strength with the fluid side cup plates  80  that are formed with thin metal plates. From another perspective, forming the annular protrusions  80   b   1  by burring on the fluid flow hole portions  80   b  enables the fluid side cup plates  80  to be made as thin as possible. It is also possible to have the annular protrusions  80   b   1  protrude toward the fluid flow layer  90  side, but in this case, they may impede the flow of fluid Fld inside the fluid flow layers  90 . 
     Therefore, with the heat exchanger  70  according to this example embodiment, as shown in  FIG. 2 , the fluid side cup plate  81  is made thicker than the fluid side cup plates  80  other than the fluid side cup plate  81 , and a positioning hole  81   a  for determining the relative position with respect to the base plate  86  is formed through this fluid side cup plate  81 . The thickness of the fluid side cup plate  81  is a predetermined thickness of approximately 1 mm, for example, set in advance as a thickness at which it is not necessary to form an annular protrusion (such as the annular protrusions  80   b   1 ) by burring at a positioning hole  81   a  that extends through to ensure positioning strength, for example. That is, the thickness of the fluid side cup plate  81  is a predetermined thickness set in advance to adequately ensure positioning strength, even if the positioning hole  81   a  for determining the relative position with the base plate  86  is a simple hole (i.e., a drainage hole) that has not been burred. 
     Also, a positioning protruding portion  86   b  that protrudes toward the fluid side cup plate  81  side and is to be fitted into the positioning hole  81   a  formed through the fluid side cup plate  81  is formed by press-forming, for example, so as to be able to fit into the positioning hole  81   a  when the fluid side cup plate  81  is stacked onto the base plate  86 . That is, the positioning protruding portion  86   b  that protrudes toward the fluid side cup plate  81  side and is to be fitted into the positioning hole  81   a  formed through the fluid side cup plate  81 , is formed in the base plate  86  in a position opposite, in the stacking direction, the fluid flow hole portions  80   b  and  82   b  formed in the cup plates  80  and  82 , respectively, for introducing fluid Fld into the fluid flow layer  90  that contacts the base plate  86 . In this way, the fluid flow hole portions  80   b  and the positioning hole  81   a  are provided in the same positions in the fluid side cup plates  80  and  81 , so if the thicknesses of the fluid side cup plates  80  and  81  are the same, the fluid side cup plates  80  and  81  can be common parts. Also, this positioning recessed portion  86   a  has a flat shape that protrudes corresponding to the positioning hole  81   a , for example, and the height of the protruding portion, is set to a predetermined height (for example, a height of approximately the same as or less than the thickness of the fluid side cup plate  81 ) that is set in advance and that enables the fluid side cup plate  81  and the base plate  86  to be appropriately positioned, for example. Therefore, in the fluid flow layer  90  formed by the fluid side cup plate  81 , the protruding portion  86   b  will not protrude toward the fluid flow layer  90  side more than the thickness of the positioning hole  81   a  at the positioning hole  81   a  portion, so the flow of fluid Fld will be impeded as little as possible. In this way, with the heat exchanger  70  of this example embodiment, making the fluid side cup plate  81  thicker than the other fluid side cup plates  80  obviates the need for the annular protrusion formed by burring at the positioning hole  81   a  for positioning the fluid side cup plates on the base plate  86 . Also, on the base plate  86 , the shape for positioning may be changed from an inner recessed shape (see the positioning recessed portion  86   a ) to an inner protruding shape (see the positioning protruding portion  86   b ). This makes it possible to prevent (i.e., avoid) protrusions protruding toward the outside from the base plate  86 . 
     As described above, according to this example embodiment, the positioning protruding portion  86   b  that protrudes toward the fluid side cup plate  81  side and is to be fitted into the positioning hole  81   a  formed through the fluid side cup plate  81  is formed in the base plate  86  in a position opposite, in the stacking direction, the fluid flow hole portions  80   b  and  82   b  formed in the cup plates  80  and  82 , respectively for introducing fluid Fld into the fluid flow layer  90  that contacts the base plate  86 . As a result, the positioning hole  81   a  formed in the fluid side cup plate  81  and the positioning protruding portion  86   b  formed on the base plate  86  make it possible to appropriately position the fluid side cup plate  81  and the base plate  86  relative to one another, while avoiding a protruding shape that protrudes out to the outside, opposite the fluid side cup plate  81  side, of the base plate  86 . Accordingly, a protrusion toward the outside from the base plate  86  can be prevented, i.e., there is no longer an outer protruding shape on the base plate  86 , so the mountability of the heat exchanger  70  to the vehicle  10  (i.e., the automatic transmission  110 ) (or the degree of freedom when mounting the heat exchanger  70  to the vehicle  10 ) can be improved. In particular, the fluid flow hole portions  80   b  and  82   b  formed on the fluid side cup plates  80  and  82  are provided in positions opposite, in the stacking direction, the positioning hole  81   a  formed in the fluid side cup plate  81 , i.e., the fluid flow hole portions  80   b  and the positioning hole  81   a  are provided in the same positions on the fluid side cup plates  80  and  81 , respectively, so when the thicknesses of the fluid side cup plates  80  and  81  are the same, the fluid side cup plates  80  and  81  can be treated as common parts, which enables productivity to be improved. 
     Also, according to this example embodiment, the positioning protruding portion  86   b  formed on the base plate  86  is formed in a shape that does not protrude toward the side with the fluid flow layer  90  that contacts the base plate  86  more than the thickness of the fluid side cup plate  81  (i.e., the thickness of the positioning hole  81   a  formed in the fluid side cup plate  81 ). Therefore, the flow of fluid Fld introduced into the fluid flow layer  90  that contacts the base plate  86  is impeded as little as possible, so cooling performance improves, compared to, for example, a case in which the positioning protruding portion  86   b  is a shape that protrudes toward the side with the fluid flow layer  90  that contacts the base plate  86 , or a case in which the positioning protruding portion  86   b  is not formed in a position opposite the fluid flow hole portions  80   b  and  82   b  in the stacking direction and is shaped so as to cut through the fluid flow layer  90  that contacts the base plate  86  and abut against the coolant side cup plate  82  in order to support this coolant side cup plate  82 . 
     Also in this example embodiment, the fluid side cup plate  81  is formed thicker than the fluid side cup plates  80  other than from the fluid side cup plate  81 . Therefore, positioning strength can be adequately ensured even if the shape for determining the relative position with respect to the base plate  86  is a simple hole that has not been burred, for example. 
     Also in this example embodiment, the thickness of the fluid side cup plate  81  is a predetermined thickness set in advance as a thickness that does not require the annular protrusion  80   b   1  to be formed by burring at the positioning hole  81   a  in order ensure positioning strength. As a result, positioning strength can be adequately ensured without forming the annular protrusion  80   b   1  for positioning by burring on the fluid side cup plate  81 . 
     Next, another example embodiment of the invention will be described. Portions in the description below that are common to the example embodiment described above will be denoted by like reference characters and descriptions of those portions will be omitted. 
       FIG. 3  is a sectional view of a heat exchanger  200  to which the invention may be applied, according to another example embodiment that is different from the example embodiment with the heat exchanger  70  described above. In  FIG. 3 , the heat exchanger  200  includes fluid side cup plates  206  and coolant side cup plates  208  that are stacked together, with their peripheral edge portions fixed in a liquid-tight manner by brazing, between a base plate  202  and a top plate  204 , such that fluid flow layers  210  and coolant flow layers  212  are alternately formed between them. That is, the fluid side cup plates  206  form the fluid flow layers  210  and the coolant side cup plates  208  form the coolant flow layers  212 , by the fluid side cup plates  206  and the coolant side cup plates  208  being alternately stacked together. Also, just like the heat exchanger  70  described above, the heat exchanger  200  is a stacked vehicle heat exchanger that performs heat exchange between the fluid Fld in the fluid flow layers  210  and the coolant Clt in the coolant flow layers  212 . In the heat exchanger  200 , inner fins  214  that abut against the fluid side cup plates  206  and the coolant side cup plates  208  are provided both inside the fluid flow layers  210  and inside the coolant flow layers  212 . 
     Coolant flow hole portions  206   a  that allow the coolant Clt to flow and correspond to a coolant inlet  216  and a coolant outlet, not shown, and fluid flow hole portions  206   b  that allow the fluid Fld to flow and correspond to a fluid inlet  218  and a fluid outlet, also not shown, are formed in the fluid side cup plates  206 . Also, coolant flow hole portions  208   a  that allow the coolant Clt to flow and correspond to the coolant inlet  216  and the coolant outlet, not shown, and fluid flow hole portions  208   b  that allow the fluid Fld to flow and correspond to the fluid inlet  218  and the fluid outlet, not shown, are formed in the coolant side cup plates  208 . 
     In the heat exchanger  200 , with the base plate  202  as the lowest level, the core main body  220  is formed by stacking the inner fins  214 , the fluid side cup plate  206 , the inner fins  214 , the coolant side cup plate  208 , the inner fins  94 , the fluid side cup plate  206 , . . . in this order from the base plate  202  upward, and stacking the top plate  204  on top as the highest level. Also, the heat exchanger  200  is manufactured by brazing these together in a liquid-tight manner in a brazing furnace, for example, and then a complete inspection is performed after manufacturing (for example, an inspection is performed for fluid Fld and coolant Clt leaks). 
     Here, the coolant flow hole portions  206   a , the fluid flow hole portions  206   b , the coolant flow hole portions  208   a , and the fluid flow hole portions  208   b  are formed in a predetermined shapes that enable the stacked plates to be brazed together in a liquid-tight manner, while serving as positioning holes when alternately stacking the fluid side cup plates  206  and the coolant side cup plates  208  together. 
     Just as with the example embodiment described above, it is necessary to provide shapes for positioning on each of the plates in order to uniquely determine the relative positions of the base plate  202  and the end fluid side cup plate  206  that abuts against the base plate  202  (hereinafter this end fluid side cup plate will be referred to as “fluid side cup plate  207 ”).  FIG. 5  is a sectional view of another reference example (other related art) of a heat exchanger  300  in which a fluid side cup plate  206  is employed as it is as an end fluid side cup plate, just like the heat exchanger  170  shown in  FIG. 4 . 
     In  FIG. 5 , the coolant flow hole portions  206   a  are made to function as positioning holes when stacking the fluid side cup plates  206  onto the base plate  202 . Therefore, a positioning recessed portion  202   a  corresponding to annular protrusions  206   a   1  that are burred on the coolant flow hole portions  206   a  and protrude toward the base plate  202  side is formed by press-forming, for example, on the base plate  202 , such that the annular protrusion  206   a   1  will fit into the base plate  202 . As a result, a protrusion toward the outside, opposite the fluid side cup plate  206  side, is produced on the positioning recessed portion  202   a  of the base plate  202 , which may affect the mountability of the heat exchanger  300  to the vehicle  10  (e.g., the automatic transmission  110 ). 
     Therefore, with the heat exchanger  200  of this example embodiment, just as with the heat exchanger  70  of the example embodiment described above, the fluid side cup plate  207  is made to be thicker than the fluid side cup plates  206  other than the fluid side cup plate  207 , and a positioning hole  207   a  for determining the relative position with respect to the base plate  202  is formed, as shown in  FIG. 3 . Also, a positioning protruding portion  202   b  that protrudes toward the fluid side cup plate  207  side and is to be fitted into the positioning hole  207   a  formed in the fluid side cup plate  207 , is formed by press-forming, for example, on the base plate  202  so as to be able to fit into the positioning hole  207   a  when the fluid side cup plate  207  is stacked onto the base plate  202 . That is, the positioning protruding portion  202   b  that protrudes toward the fluid side cup plate  207  side and is to be fitted into the positioning hole  207   a  formed through the fluid side cup plate  207 , is formed in the base plate  202  in a position opposite, in the stacking direction, the coolant flow hole portions  206   a  and  208   a  formed in the cup plates  206  and  208 , respectively, for introducing coolant Clt into the coolant flow layer  212  that contacts the base plate  202 . In this way, with the heat exchanger  200  of this example embodiment, the coolant flow hole portions  206   a  and the positioning hole  207   a  are provided in the same positions in the fluid side cup plates  206  and  207 , so if the thicknesses of the fluid side cup plates  206  and  207  are the same, the fluid side cup plates  206  and  207  can be common parts. Also, making the fluid side cup plate  207  thicker than the other fluid side cup plates  206  obviates the need for the annular protrusion formed by burring at the positioning hole  207   a  for positioning the fluid side cup plates on the base plate  202 . Also, on the base plate  202 , the shape for positioning may be changed from an inner recessed shape (see the positioning recessed portion  202   a ) to an inner protruding shape (see the positioning protruding portion  202   b ). This makes it possible to prevent (i.e., avoid) protrusions protruding toward the outside from the flat portion of the base plate  202 . 
     As described above, according to this example embodiment, with the heat exchanger  200 , the positioning protruding portion  202   b  that protrudes toward the fluid side cup plate  207  side and is to be fitted into the positioning hole  207   a  formed through the fluid side cup plate  207  is formed in the base plate  202  in a position opposite, in the stacking direction, the coolant flow hole portions  206   a  and  208   a  formed in the cup plates  206  and  208 , respectively for introducing coolant Clt into the coolant flow layer  212  that contacts the base plate  202 . As a result, similar effects as those obtained with the example embodiment described above are obtained. 
     Heretofore, example embodiments of the invention have been described in detail with reference to the drawings, but the invention may also be applied in other modes. 
     For example, in the example embodiment described, above, the heat exchangers  70  and  200  are transmission fluid heat exchangers that perform heat exchange between the fluid Fld and the coolant Clt, but the invention is not limited to this. That is, the invention may be applied to any stacked vehicle heat exchanger capable of performing heat exchange between a first heat carrier and a second heat carrier. For example, the invention may also be applied to a stacked vehicle heat exchanger in which the first heat carrier is the coolant Clt and the second heat carrier is the fluid Fld, or a stacked vehicle heat exchanger in which the first heat carrier is coolant (or engine oil) and the second heat carrier is engine oil (or coolant), or the like. 
     Also, in the example embodiment described above, the fluid side cup plates  81  and  207  are made thicker than the fluid side cup plates  80  and  206 , but the invention is not limited to this. For example, the fluid side cup plates  81  and  207  may also be the same thickness as the fluid side cup plates  80  and  206 . That is, the thickness of the fluid side cup plates  81  and  207  need only be a predetermined thickness that at least adequately ensures positioning strength, even if the positioning holes  81   a  and  207   a  are simple holes. 
     While the invention has been described with reference to example embodiments thereof, it is to be understood that the invention is not limited to the described embodiments or constructions. To the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the example embodiments are shown in various combinations and configurations, other combinations and configurations, including more, less or only a single element, are also within the scope of the invention.