Heat exchanger

An outer peripheral sealing surface of an inner surface of a core plate of a header tank is configured into a loop and extends along an outer peripheral edge portion of the core plate and clamps a packing in cooperation with an outer peripheral end portion of a tank main body of the header tank. A transition section of the outer peripheral sealing surface connects between a primary section and a secondary section, which are located in two different planes, respectively, and the plane of the secondary section is the same as a plane of a boundary portion sealing surface held between two tube connecting surfaces in the core plate.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and incorporates herein by reference Japanese Patent Application No. 2011-82087 filed on Apr. 1, 2011.

TECHNICAL FIELD

The present disclosure relates to a heat exchanger.

BACKGROUND

For instance, WO 2010/133491A1 teaches a header tank (collector box) of a heat exchanger that has two inside spaces, which are partitioned by a partition wall for two heat exchange systems.

The header tank of the heat exchanger of WO 2010/133491A1 includes a core plate (collector plate), a cover and a seal. The core plate has a bottom, which has tube receiving holes and is surrounded by a peripheral groove. The cover has a peripheral lug. The seal is held between the peripheral groove of the core plate and the peripheral lug of the cover and is also held between the core plate and the partition wall of the cover. Furthermore, a portion of the bottom of the core plate, which is opposed to the partition wall, is locally recessed in a view taken from an inside of the header tank, so that the sealing surface of the seal extends in a plane.

In the header tank of WO 2010/133491A1, the sealing surface of the seal extends in the plate, so that a uniform compression force may be achieved along the entire sealing surface of the seal. However, since the portion of the core plate is locally recessed in the view taken from the inside of the header tank, a projecting length of an end portion of the tube, which projects from the recessed portion of the core plate into the inside of the header tank, becomes longer than that of the other tube, which projects from another portion of the core plate that is other than the recessed portion. This construction poses the following disadvantage with respect to the production of the header tank.

Normally, the tubes are fixed to the core plate as follows. That is, each of the tubes is inserted into the corresponding tube receiving hole of the core plate. Then, a dedicated tool is inserted into an opening of an end portion of the tube to widen the opening of the end portion of the tube from the inside of the tube and thereby to plastically deform a connecting portion of the tube, which is connected to the peripheral edge of the receiving hole. In this way, the tube is temporarily fixed to the tube receiving hole. Thereafter, the tube is brazed to the core plate. Therefore, in the case of WO 2010/133491A1, the amount of deformation of the end portion of the tube, which has the long projecting length discussed above, needs to be increased to plastically deform the connecting portion of the tube, which is connected to the receiving hole of the core plate, by a predetermined amount. This might possibly cause cracking of the end portion of the tube. Alternatively, the amount of plastic deformation of the tube at the connecting portion received in the receiving hole might possibly become insufficient. In such a case, a clearance at a brazing part between the tube and the receiving hole might become excessively large to cause a brazing defect. Furthermore, when the tubes are excessively deformed to have an increased width at the end portion of the tube, a size of a space between the end portions of the adjacent two tubes may be reduced. Thereby, a partition plate may be snagged, i.e., caught between the tubes without being held in place at the time of assembling of a tank main body of the header tank, thereby resulting in deterioration of the assembling efficiency. Furthermore, in the header tank of WO 2010/133491A1, the core plate is locally recessed in the view taken from the inside of the header tank, so that a heat exchanging surface area between the tube, which is connected to the locally recessed portion of the core plate, and the air may be reduced at the outside of the header tank in comparison to the other tubes, which are placed at the outside of the locally recessed portion at the core plate.

SUMMARY

The present disclosure is made in view of the above disadvantages. Thus, it is an objective of the present disclosure to provide a head exchanger that addresses at least one of the above disadvantages. According to the present disclosure, there is provided a heat exchanger, which includes a core and two header tanks. The core includes a plurality of tubes, which are configured to conduct fluid. The two header tanks are placed at two opposed longitudinal ends, respectively, of the plurality of tubes and are communicated with the plurality of tubes. Each of the two header tanks includes a core plate, a tank main body, at least one partition wall, at least two tank chambers and a seal member. The plurality of tubes is joined to the core plate. The at least one partition wall is joined to the tank main body. The at least two tank chambers are formed by the core plate, the tank main body and the at least one partition wall. An inner surface of the core plate includes an outer peripheral sealing surface, at least two tube connecting surfaces and at least one boundary portion sealing surface. The outer peripheral sealing surface is configured into a loop and extends along an outer peripheral edge portion of the core plate and clamps the seal member in cooperation with an outer peripheral end portion of the tank main body. The at least two tube connecting surfaces extend in a corresponding plane and are located on an inner side of the outer peripheral sealing surface where the plurality of tubes is located. Each of the at least two tube connecting surfaces has at least one tube receiving hole, through each of which a corresponding one of the plurality of tubes is received. The at least one boundary portion sealing surface extends in a corresponding plane. Each of the at least one boundary portion sealing surface is located between corresponding adjacent two of the at least two tube connecting surfaces to clamp the seal member in corporation with an end of each corresponding one of the at least one partition wall. The outer peripheral sealing surface includes at least one primary section, at least one secondary section and at least one transition section. The at least one primary section extends in a corresponding plane. The at least one secondary section extends in a corresponding plane. The corresponding plane of the at least one secondary section is generally parallel to the corresponding plane of the at least one primary section and is spaced from the corresponding plane of the at least one primary section in a direction perpendicular to the corresponding plane of the at least one primary section. Each of the at least one transition section connects between a corresponding one of the at least one primary section and a corresponding one of the at least one secondary section and is tilted relative to the corresponding plane of the at least one primary section and the corresponding plane of the at least one secondary section. The corresponding plane of the at least one primary section is generally parallel to the corresponding plane of the at least two tube connecting surfaces and is placed on a side of the corresponding plane of the at least two tube connecting surfaces where an outside of the header tank is located. The corresponding plane of the at least one boundary portion sealing surface is displaced from the corresponding plane of the at least one primary section in a direction perpendicular to the corresponding plane of the at least one primary section within a range that does not exceed the corresponding plane of the at least two tube connecting surfaces on a side where an inside of the header tank is located. The corresponding plane of the at least one secondary section is the same as the corresponding plane of the at least one boundary portion sealing surface.

DETAILED DESCRIPTION

Various embodiments of the present disclosure will be described with reference to the accompanying drawings. In each of the following embodiments, similar components are indicated by the same reference numerals.

First Embodiment

A first embodiment of the present disclosure will be described with reference toFIGS. 1 to 7. In the present embodiment, a heat exchanger of the present disclosure is implemented as a heat exchanger of a hybrid vehicle, in which a drive force of the vehicle is obtained from an internal combustion engine and a drive electric motor.

FIG. 1is a front view of the heat exchanger according to the first embodiment. As shown inFIG. 1, the heat exchanger of the present embodiment includes a core4and two header tanks5. The core4has a plurality of tubes2and a plurality of fins3. The tubes2are arranged one after another, i.e., are stacked one after another at generally equal intervals in a stacking direction thereof (a left-to-right direction inFIG. 1). The header tanks5are installed to an upper end portion and a lower end portion, respectively, of the core4.

Each tube2is formed as a flat tube, which is configured to conduct fluid therethrough and has an elongated cross-section, in which an elongating direction of the cross-section of the tube coincides with a flow direction (also referred to as an air flow direction) of air that flows around the flat tube through the core4. A longitudinal direction of the tube2coincides with a top-to-bottom direction ofFIG. 1. Each fin3is configured into a wavy form and is joined to planar outer surfaces of adjacent two of the tubes2. The fin3increases a heat conducting surface area of the core4to promote heat exchange between the fluid, which flows through the tubes2, and the air.

The header tanks5are respectively arranged at the upper and lower ends (two opposed longitudinal ends) of the tubes2. Each header tank5is elongated in a horizontal direction (left-to-right direction) ofFIG. 1and has first and second tank chambers501,502that are communicated with the tubes2. The header tank5includes a core plate51, a tank main body52and partition walls524. The tubes2are received by and are joined to the core plate51. The partition walls524include a first partition wall524aand a second partition wall524b, which are joined to the tank main body52, more specifically are formed integrally with the tank main body52. Furthermore, the header tank5includes a packing53(not shown inFIG. 1), which is a seal member that is made of rubber and seals between the core plate51and the tank main body52having the partition walls524. Furthermore, as shown inFIG. 7, which is an enlarged perspective view showing a main feature of the tank main body52, the tank main body52includes a first recess5211and a second recess5212, which are arranged one after another in the stacking direction of the tubes2, and an intermediate recess5213is held between the first recess5211and the second recess5212in the stacking direction of the tubes2in the tank main body52. The first recess5211, the second recess5212and the intermediate recess5213are closed with the core plate51to form the first tank chamber501, the second tank chamber502and an intermediate chamber503, respectively. In other words, the first and second chambers501,502and the intermediate chamber503are formed by the core plate51, the outer wall of tank main body52and the first and second partition walls524.

One of the header tanks5, which is placed at the upper side, is referred to as an upper header tank (also referred to as a first header tank)5A, and the other one of the header tanks5, which is placed at the lower side, is referred to as a lower header tank (also referred to as a second header tank)5B. An engine coolant inlet81and an electric system coolant inlet82are formed in the upper header tank5A. The engine coolant inlet81is communicated with the first tank chamber501of the upper header tank5A to supply engine coolant into the first tank chamber501. The electric system coolant inlet82is communicated with the second tank chamber502of the upper header tank5A to supply electric system coolant into the second tank chamber502. An engine coolant outlet83and an electric system coolant outlet84are formed in the lower header tank5B. The engine coolant outlet83is communicated with the first tank chamber501of the lower header tank5B to output the engine coolant from the first tank chamber501. The electric system coolant outlet84is communicated with the second tank chamber502of the lower header tank5B to output the electric system coolant from the second tank chamber502. A fluid inlet or outlet for fluid, such as the coolant, is not provided to any of the intermediate chambers503of the upper and lower header tanks5A,5B, and an inside of each intermediate chamber503is filled with air.

Although the upper header tank5A and the lower header tank5B differ with respect to the inflow and the outflow of the coolants as discussed above, a basic structure of the upper header tank5A and a basic structure of the lower header tank5B are the same. Therefore, in the present specification, the upper header tank5A will be described as the header tank5at the time of describing the structure of the header tank5in the following description.

Two side plates6are provided at the two lateral sides, respectively, of the core4, which are opposed to each other in the stacking direction of the tubes2, to reinforce the core4. Each side plate6is elongated in the longitudinal direction (tube longitudinal direction) of the tubes2, and two opposed end portions of the side plate6are connected to, i.e., joined to the header tanks5.

The core4includes a first radiator arrangement41, a second radiator arrangement42and a thermally insulating arrangement43. The first radiator arrangement41includes the corresponding tubes2, which are connected to the first tank chambers501of the upper and lower header tanks5A,5B. The second radiator arrangement42includes the corresponding tubes2, which are connected to the second tank chambers502of the upper and lower header tanks5A,5B. The thermally insulating arrangement43includes two of the tubes2, which are connected to the intermediate chambers503of the upper and lower header tanks5. The two tubes2of the thermally insulating arrangement43are connected to the intermediate chamber503of the upper and lower header tanks5A,5B and do not conduct fluid such as the coolant. That is, the fluid does not flow through these two tubes2. In the present embodiment, the thermally insulating arrangement43includes the two tubes2. However, the number of tubes2of the thermally insulating arrangement43is not limited to this number and may be changed to one or three or more.

In the present embodiment, the first radiator arrangement41exchanges heat between the engine coolant, which is circulated through the engine (not shown), and the air to cool the engine coolant. Furthermore, the second radiator arrangement42exchanges heat between the electric system coolant, which is circulated through the electric motor (not shown) and an electric control circuit (e.g., an inverter circuit) that controls the electric motor, and the air to cool the electric system coolant that cools the electric motor and the electric control circuit. The first radiator arrangement41and the second radiator arrangement42correspond to a plurality of heat exchanging arrangements (first and second heat exchanging arrangements) of the present disclosure.

Next, the structure of the header tank5will be described in detail.FIG. 2is an enlarged cross-sectional view taken along line II-II inFIG. 1, showing a cross-section of the first tank chamber501of the header tank5.FIG. 3is an enlarged cross-sectional view taken along line III-III inFIG. 1, showing a cross-section of the intermediate chamber503of the header tank5.FIG. 4is a partial enlarged perspective view showing a main feature of the core plate51of the header tank5.FIG. 5is a perspective view of the packing53of the header tank5.FIG. 6is a partial enlarged perspective view showing the main feature of the core plate51, to which the packing53and the tubes2are installed.FIG. 7is a partial enlarged perspective view showing a main feature of the tank main body52of the header tank5.

In the present embodiment, the core plate51of the header tank5is made of an aluminum alloy, and the tank main body52of the header tank5is made of glass fiber reinforced polyamide resin. As shown inFIGS. 2 and 3, in a state where the packing53made of the rubber is held between the core plate51and the tank main body52as well as between the core plate51and the partition walls524, projections516of the core plate51, which will be described later, are bent against the tank main body52by swaging to fix the tank main body52to the core plate51.

The core plate51is configured into a generally rectangular planar form and includes a groove512, two tube connecting portions511and a boundary portion518. The groove512is configured into a loop and extends along an outer peripheral edge portion of the core plate51. The two tube connecting portions511are placed at two locations, which correspond to the first tank chamber501and the second tank chamber502, respectively, and tube receiving holes517are formed in each of the tube connecting portions511. The boundary portion518is held between the tube connecting portions511and is placed at a location, which corresponds to the intermediate chamber503. A flange portion521, which is formed at an end portion of the tank main body52, as well as the packing53are inserted into the groove512. The flange portion521of the tank main body52forms an outer peripheral end portion of the present disclosure.

The groove512of the core plate51includes three portions. Specifically, the groove512includes an inner wall portion (also referred to as an inner vertical wall portion)513, an outer peripheral portion514and an outer wall portion (also referred to as an outer vertical wall portion)515. The inner wall portion513is bent generally at a right angle from outer peripheral edges of the tube connecting portions511and extends downward inFIG. 2. The outer peripheral portion514extends from a lower end of the inner wall portion513in a horizontal direction inFIG. 2. The outer wall portion515is bent generally at a right angle from an outer peripheral edge of the outer peripheral portion514and extends upward inFIG. 2. The projections516, each of which is configured into a generally rectangular form, are arranged at generally equal intervals along an upper end of the outer wall portion515. The projections516initially extend in the same direction as that of the outer wall portion515and are inwardly bent generally in the horizontal direction to urge the flange portion521against the packing53upon placement of the flange portion521of the tank main body52in the groove512.

With reference toFIGS. 2 and 4, a majority of an outer peripheral sealing surface514a, which is an inner surface (upper surface inFIGS. 2 and 4) of the outer peripheral portion514of the groove512, is located in an corresponding plane that is placed on a side (lower side inFIGS. 2 and 4) of tube connecting surfaces511a, which are inner surfaces of the tube connecting portions511, where an outside of the header tank5is located. The outer peripheral sealing surface514ais configured into a loop and extends along the outer peripheral edge portion of the core plate51and clamps the packing53in cooperation with the flange portion521of the tank main body52. In this specification, this majority of the outer peripheral sealing surface514aincludes two primary sections514a1. With reference toFIGS. 3 and 4, two portions of the outer peripheral sealing surface514a, which are adjacent to a boundary portion sealing surface518athat is an inner surface of the boundary portion518, extend in a corresponding plane, in which the boundary portion sealing surface518ais located. In the present specification, these two portions of the outer peripheral sealing surface514a, which are adjacent to the boundary portion sealing surface518a, are referred to as secondary sections514a2. A boundary between each secondary section514a2and the boundary portion sealing surface518ais indicated by a dot-dot-dash line inFIG. 4for ease of understanding.

The inner wall portion513is absent in the groove512at the locations where the secondary sections514a2are respectively formed. Furthermore, the outer peripheral sealing surface514afurther includes four transaction sections514a3, each of which connects between the corresponding adjacent primary section514aand the corresponding adjacent secondary section514a2. Therefore, when the core plate51is viewed inFIG. 1, the core plate51has a trapezoidal recess.

With reference toFIG. 4, the two tube connecting surfaces511a, which are placed on the one side and the other side, respectively, of the boundary portion sealing surface518ain the stacking direction of the tubes2, extend in the corresponding common plane (the same plane) on the inner side of the outer peripheral sealing surface514awhere the tubes2are located. In this embodiment, the plane of the boundary portion sealing surface518ais the same as the plane of the tube connecting surfaces511a, that is, the boundary portion sealing surface518aand the tube connecting surfaces511aextend in the common plane. Furthermore, the tube receiving holes517, in each of which the corresponding tube2is received, fixed by swaging and brazed, are arranged one after another in the stacking direction of the tubes2in each tube connecting surface511a. A peripheral protrusion517ais formed to protrude upwardly inFIG. 4around each tube receiving hole517through a burring process to reliably perform the fixation of the tube2by the swaging and the brazing of the tube2relative to the tube receiving hole517. Furthermore, two side plate receiving holes (not shown), into which the side plates6are respectively received and brazed, are formed at two outer end portions of the tube connecting surfaces511a, which are opposed to each other in the stacking direction of the tubes2. Furthermore, the two tube receiving holes517, into which the two tubes2(the tubes2not conducting the fluid) of the thermally insulating arrangement43are received, fixed by swaging and brazed, are arranged one after another in the stacking direction of the tubes2in the boundary portion sealing surface518a.

In the present embodiment, as shown inFIG. 4, the boundary portion sealing surface518aof the boundary portion518of the core plate51extends in the corresponding common plane, in which the tube connecting surfaces511aof the tube connecting portions511and the secondary sections514a2of the outer peripheral sealing surface514aextend. The corresponding common plane, in which the boundary portion sealing surface518a, the tube connecting surfaces511aand the secondary sections514a2extend, is generally parallel to a plane of the primary sections514a1and is spaced from the plane of the primary sections514a1in a direction, which is perpendicular to the stacking direction of the tubes2and is perpendicular to the plane of the primary sections514a1, away from the center of the core4(the longitudinal center of the tubes2), i.e., away from the outside of the header tank5. Furthermore, as shown inFIG. 6, partition sealing portions532of the packing53, which will be described later, are installed on the boundary portion sealing surface518a. The boundary portion sealing surface518acan clamp and compress the partition sealing portions532of the packing53in cooperation with an end of the first partition wall524aand an end of the second partition wall524bprovided in the tank main body52.

Next, the packing53will be described in detail with reference toFIG. 5. The packing53includes a loop portion531and the partition sealing portions532, which are formed integrally. The loop portion531is configured into a loop to correspond with the outer peripheral sealing surface514aof the core plate51. Each of the partition sealing portions532seals between the boundary portion sealing surface518aof the core plate51and the corresponding partition wall524a,524b. Furthermore, the loop portion531of the packing53includes two packing primary sections531a, two packing secondary sections531band four packing transition sections531c, which are formed to correspond with the two primary sections514a1, the two secondary sections514a2and the four transition sections514a3, respectively, in terms of the location and the height. The partition sealing portions532include a first partition sealing portion532aand a second partition sealing portion532b, which contact the first partition wall524aand the second partition wall524b, respectively, of the tank main body52. The first and second partition sealing portions532a,532bare connected to the packing secondary sections531bat the same level, i.e., the same height (in the same plane). The packing53, which is configured in the above described manner, is placed on the outer peripheral sealing surface514aand the boundary portion sealing surface518aof the core plate51, as shown inFIG. 6.

Next, the tank main body52will be described with reference toFIG. 7. In the present embodiment, an upper portion of the tank main body52is curved into an arcuate form, and the tank main body52is elongated in the stacking direction of the tubes2. The flange portion521is formed to extend all around an opening end of the tank main body52. A shape of the flange portion521of the tank main body52corresponds to a shape of the outer peripheral sealing surface514aof the core plate51. Therefore, when the tank main body52is viewed inFIG. 1(i.e., viewed from a front side of the heat exchanger), the trapezoidal recess is formed about a third main body portion5203of the tank main body52, which will be described later.

The tank main body52includes a first main body portion5201, a second main body portion5202and the third main body portion5203, which form the first recess5211, the second recess5212and the intermediate recess5213, respectively, therein. The first recess5211, the second recess5212and the intermediate recess5213are closed with the core plate51to form the first tank chamber501, the second tank chamber502and the intermediate chamber503, respectively, of the header tank5.

The first partition wall524ais formed between the first recess5211and the intermediate recess5213to separate, i.e., partition therebetween, and the second partition wall524bis formed between the second recess5212and the intermediate recess5213to separate, i.e., partition therebetween. In the present embodiment, the height of the third main body portion5023is lower than the first main body portion5201and the second main body portion5202. Therefore, each of the first partition wall524aand the second partition wall524bhas an outwardly exposed portion besides a facing portion, which faces the intermediate recess5213. Furthermore, the third main body portion5203includes two reinforcing ribs525, which connect between the first main body portion5201and the second main body portion5202.

A flange sealing surface522is formed in the flange portion521of the tank main body52. The flange sealing surface522contacts the loop portion531of the packing53to clamp and compress the packing53by a predetermined compression amount in cooperation with the outer peripheral sealing surface514aof the core plate51. Therefore, the flange sealing surface522includes two flange primary sections522a, two flange secondary sections522band four flange transition sections522cto correspond with the two primary sections514a1, the two secondary sections514a2and the four transition sections514a3, respectively.

A protruding portion523, which protrudes in an arcuate form (a semicylindrical form) toward the loop portion531of the packing53, is formed in the flange sealing surface522. The protruding portion523is provided to reduce the force, which is required to compress and deform the packing53by a predetermined amount, and to implement the appropriate compression ratio of the packing53.

The protruding portion523, which protrudes in the arcuate form (the semicylindrical form) toward the partition sealing portion532a,532b, is also formed in the end of the first partition wall524aand the end of the second partition wall524b.

As discussed above, in the header tank5of the heat exchanger of the present embodiment, the flange primary sections522a, the flange secondary sections522band the flange transition sections522cof the tank main body52compress the packing primary sections531a, the packing secondary sections531band the packing transition sections531cof the packing53in corporation with the primary sections514e1, the secondary sections514a2and the transition sections514a3of the outer peripheral sealing surface514aof the core plate51. Furthermore, the end surface of the first partition wall524aand the end surface of the second partition wall524bof the tank main body52compress the first partition sealing portion532aand the second partition sealing portion532bof the packing53in corporation with the boundary portion sealing surface518aof the core plate51. Thereby, the gap between the tank main body52and the core plate51is sealed by the packing53.

At this time, the primary sections514a1and the secondary sections514a2of the outer peripheral sealing surface514aof the core plate51and the boundary portion sealing surface518aextend in the horizontal direction inFIG. 1. Furthermore, although each transition section514a3is tilted relative to the plane of the adjacent primary section514a1and the plane of the adjacent secondary section514a2, a tilt angle of the transition section514a3is moderate, i.e., shallow. Therefore, the forces, which act on the packing53, are mostly forces, each of which has a generally vertical component. Thus, the compression of the packing53can be reliably implemented.

Furthermore, in the present embodiment, the tube connecting surfaces511aand the boundary portion sealing surface518aof the core plate51are located in the corresponding common plane. Therefore, irregular tubes, which have the long projecting length toward the inside of the header tank5, do not exist. As a result, the fixation process of each tube2in the corresponding tube receiving hole517by the swaging can be reliably performed. Also, the irregular tubes, which have the short expositing length into the air at the core4, do not exist.

Second Embodiment

Next, a second embodiment of the present disclosure will be described with reference toFIGS. 8 and 9. Here,FIG. 8is a partial enlarged perspective view showing a main feature of the core plate51of the header tank5of the heat exchanger of the second embodiment.FIG. 9is a partial enlarged perspective view showing the main feature of the core plate51, to which the packing53and the tubes2are installed according to the second embodiment.

As shown inFIGS. 8 and 9, the heat exchanger of the second embodiment is similar to that of the first embodiment except that the boundary portion sealing surface518aof the core plate51is displaced from the tube connecting surfaces511aon the side where the outside of the header tank5is located, i.e., on the lower side of the header tank5(the side where the other header tank5is located, i.e., where the center of the core4is located) inFIG. 8. Even in this embodiment, similar to the first embodiment, the plane of the boundary portion sealing surface518ais displaced from the plane of the primary sections514a1in the direction perpendicular to the plane of the primary sections514a1within a range that does not exceed the plane of the tube connecting surfaces511aon the side where an inside of the header tank5is located, i.e., on the side opposite from the outside of the header tank5, i.e., opposite from the center of the core4. More specifically, in this embodiment, the plane of the boundary portion sealing surface518ais located between the plane of the primary sections514a1and the plane of the tube connecting surfaces511ain the direction perpendicular to the plane of the primary sections514a1. Furthermore, similar to the first embodiment, in the second embodiment, the secondary sections514a2of the outer peripheral sealing surface514aand the boundary portion sealing surface518aof the core plate51are connected with each other at the same level, i.e., in the corresponding common plane, and the outer peripheral sealing surface514aincludes the primary sections514a1, the secondary sections514a2and the transition sections514a3. Furthermore, a boundary between each secondary section514a2of the outer peripheral sealing surface514aand the boundary portion sealing surface518ais indicated by a dot-dot-dash line inFIG. 8for ease of understanding.

The header tank5of the second embodiment is formed in the above described manner, so that the tilt angle of each transition section514a3relative to the primary and secondary sections514a1,514a2can be made further moderate, i.e., shallower in comparison to the first embodiment. Therefore, the projecting length of each corresponding tube2, which projects from the boundary portion sealing surface518ainto the inside of the intermediate chamber503, becomes longer than that of the other tubes2. However, the projecting length of the above tubes2, which project from the boundary portion sealing surface518a, is still shorter than that of the previously proposed technique, in which the outer peripheral sealing surface extends in the corresponding plane, and the boundary portion sealing surface and the outer peripheral sealing surface are located in the same level, i.e., in the same single corresponding plane. Therefore, the appropriate sealing performance can be maintained, and the fixing process of each tube2in the corresponding tube receiving hole517by the swaging can be more reliably performed in comparison to the previously proposed technique.

Now, modifications of the above embodiments will be described.

As discussed above, it is desirable to use at least one tube2, which does not conduct the fluid, in the thermally insulating arrangement43of the core4. However, the thermally insulating arrangement43may be eliminated from the core4in a case where a temperature difference between the first radiator arrangement41and the second radiator arrangement42is small. In such a case, the header tank5does not include the intermediate chamber503, and a single partition wall524, which divides between the first tank chamber501and the second tank chamber502, the boundary portion sealing surface518aand the partition sealing portion532of the packing53are arranged between two adjacent tubes of the first radiator arrangement41and of the second radiator arrangement42, which are arranged adjacent to each other.

Furthermore, in the first and second embodiments, the header tank5includes the two tank chambers501,502, the single intermediate chamber503and the single boundary portion518of the core plate51. However, the number of the partition walls may be increased to increase the numbers of the tank chambers, the intermediate chamber(s) and the boundary portion(s). Also, the number of the first radiator arrangement41and the second radiator arrangement42(i.e., the heat exchanging arrangements) may be increased to three or more, and the number of the thermally insulating arrangement43may be increased to two or more depending on the number of the heat exchanging arrangements.

Additional advantages and modifications will readily occur to those skilled in the art. The present disclosure in its broader terms is therefore not limited to the specific details, representative apparatus, and illustrative examples shown and described.