Heat exchanger capable of preventing heat stress

Abstract

The object of the present invention is to provide a heat exchanger which can prevent the tubes from being damaged by the heat stress caused by the temperature difference between the reinforcement members and the tubes of the core portion. A heat exchanger comprises a core portion having a plurality of tubes 12a and fins 12b which are arrange so as to be alternately laid in layers. In the core portion 12, the tubes 12a are arranged at the outermost ends in the piling direction V of the tubes 12a and the fins 12b and the inserts (14) which reinforce the core portion 12 are fixed to the tubes (12a) and tanks (11, 13).

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a heat exchanger and is effective when applied to a heat exchanger, such as a radiator, for cooling engine cooling water.

2. Description of the Related Art

A conventional radiator, as shown in FIG. 13 of the patent document 1, through which a cooling water flows, comprises: a core portion 12 comprising a plurality of tubes 12a disposed in layers in the V direction in FIG. 13, and fins 12b arranged between the tubes 12a; and tanks 11 connected to the ends of the tubes 12a in a longitudinal direction L thereof which tanks distribute and collect the cooling water flowing through the tubes 12a. In this configuration, the heat of the cooling water, having absorbed heat from an engine, etc. and flowing through the tubes 12a in a high temperature state, is transmitted to the fins 12b and air flowing through the fins 12b absorbs the heat transmitted to the fins 12b. Due to this, the radiator can cool the cooling water.

Further, the radiator 50 disclosed in the patent document 1 comprises: tanks 11 at the both ends in the direction perpendicular to the longitudinal direction L of the tubes 12a, that is, in the direction V in which the tubes 12a and the fins 12b are alternately laid in layers; and inserts 14 fixed to the core portion 12 and for reinforcing the core portion 12.

As a result, the core portion 12 is not damaged by a deformation thereof, such as torsion, caused by an external force. In addition, the radiator can attain its inherent role in which it cools the cooling water flowing through the tubes 12a.

[Patent Document 1]

Japanese Utility Model Publication No. 2-92491

On the other hand, the heat exchanger of the patent document 1 has a structure in which the inserts 14 are integrally fixed to the fins 12b of the core portion 12, for reasons of manufacturing, in which, for example, when the tubes 12a and the fins 12b are joined by brazing, the tubes 12a and the fins 12b can be easily pressed by the inserts 14.

Due to this, there may be produced a temperature difference between the insert 14 fixed to the fin 12b cooled by a cooling air flow (wind) and the tube 12a through which a high temperature cooling water flows. In the worst case, the thermal stress produced by the temperature difference may destroy the thin tubes 12a having thicknesses less than that of the insert 14.

In the radiator, a state in which there is no temperature difference between the insert 14 and the tubes 12a when the engine is not in operation and another state in which there is the temperature difference therebetween are alternately repeated and, as a result, the tubes 12a may be destroyed by the repeated stress.

SUMMARY OF THE INVENTION

The present invention has been developed with the above-mentioned problems being taken into consideration, and the object thereof is to provide a heat exchanger having a core portion, in which the tubes and the fins are alternately laid in layers, and reinforcement members for reinforcing the core portion, wherein the tubes are prevented from being damaged due to the heat stress caused by the temperature difference between the reinforcement members and the tubes of the core portion.

In order to realize the above-mentioned object, in a first aspect of the present invention, there is provided with a heat exchanger having a core portion in which tubes and fins are alternately arranged in layers and reinforcement members for reinforcing the core portion and characterized in that in the core portion (12), the tubes (12a) disposed in the outermost sides in the piled direction (V) and the reinforcement members (14) are arranged so as to come into contact with each other.

In this configuration, the reinforcement members (14) are arranged so as to be in contact with the tubes (12a) and, therefore the heat of the tubes (12a) can be transmitted to the reinforcement members (14). Due to this, compared to the case of the patent document 1 shown in FIG. 13, where the reinforcement member (14) and the fin (12b) are arranged to be in contact with each other, the temperature difference between the reinforcement members (14) and the tubes (12a) can be made smaller. Therefore, a heat stress caused by the temperature difference is unlikely to be produced. As a result, it is possible to prevent the tubes (12a) from being damaged due to the heat stress.

According to a second aspect, in the heat exchanger disclosed in the first aspect, the reinforcement members (14) may be integrally fixed to the tubes (12a) of the core portion (12), so that the heat of the tubes (12a) can be transmitted to the reinforcement members (14) therefrom without fail and, as a result, the temperature difference can be made smaller.

According to a third aspect, in the heat exchanger disclosed in the first or second aspect, a heat exchanger is characterized in that the reinforcement members (14) and the tubes (12a) are independently and respectively fixed to independent tanks (11, 13).

If the tube (12a) and the reinforcement member (14) are fixed to the tank (11, 13) in a state they are integrally fixed to each other, the first fluid inside the tanks (11, 13) may leak out from the tanks (11, 13) at the contacting surface between the surface of the reinforcement member (14) and the surface of the tube (12a), etc. Thus, it is difficult to fix the tubes (12a) and the reinforcement members (14) to the tank (11, 13).

In the third aspect, however, as the tubes (12a) and the reinforcement members (14) are fixed to the tanks (11, 13) independently and respectively, it is possible to fix particularly the reinforcement members (14) to the tanks (11, 13) easily. Further, the contacting portions (surfaces) between the surfaces of the reinforcement members (14) and the surfaces of the tubes (12a) can be eliminated in the tanks (11, 13) and, as a result, it is possible to prevent the first fluid inside the tanks (11, 13) from leaking out therefrom.

According to a fourth aspect, in the heat exchanger disclosed in any one of the first to the third aspects, the heat exchanger is characterized in that the reinforcement members (14) are formed in a recess shape the sectional area of which in the direction perpendicular to the longitudinal direction of the reinforcement members (14) has a bottom portion (14a) and an opening. In the heat exchanger, on the bottom portion (14a) of the recess shape a protrusion (14b) protruding toward an outside of the reinforcement member (14) are formed, and wherein the protrusion (14b) and the tube (12a) are formed so as to come into contact with each other.

In this configuration, as the reinforcement members (14) having a sectional shape which is stronger against bending force and torsional force reinforce the core portion (12) together with the tanks (11, 13), the reinforcement ability (the strength of the reinforcement) for the core portion can be improved.

According to a fifth aspect, in the heat exchanger disclosed in any one of the first to the fourth aspects, the heat exchanger is characterized in that in a state in which the protrusion (14b) and the tube (12a) are integrally fixed to each other, when viewing from the direction (W) in which the second fluid flows into spaces between the tubes (12a); and in that the reinforcement member (14) comprises fixing portions (ON) at which the reinforcement member (14) is in contact with the tube (12a) and separated portions (OFF) at which the reinforcement member (14) is separated from the tube (12a).

In this configuration, when the reinforcement members (14) and the tubes (12a) are fixed to each other, for example, by brazing or the like, the brazing material concentrates on the fixing portions (ON) at which the reinforcement member (14) and the tube (12a) are in contact with each other and, therefore, the reinforcement member (14) and the tube (12a) can be more securely fixed to each other.

In addition, as the second fluid can pass through the separated portions (OFF), the heat radiation from the first fluid flowing through the tubes (12a) integrally fixed to the reinforcement members (14) can be enhanced. Therefore, it is possible to improve the heat exchanging ability of the heat exchanger.

According to a sixth aspect, in the heat exchanger disclosed in any one of the first to the fifth aspects, at least a part of the reinforcement member (14) may be made of a material larger in an iodization tendency than that of the tube (12a). Due to this, portions of the reinforcement members (14) formed with a material larger in an iodization tendency than that of the tubes (12a) can be corroded earlier than the tubes (12a). As a result, it is possible to prevent from forming pitting holes in the tubes (12a) due to corrosion and to prevent the first fluid flowing through the tubes (12a) from leaking out from the tubes (12a).

According to a seventh aspect, in the heat exchanger disclosed in any one of the first to the sixth aspects, the reinforcement member (14) may be attached with a sacrifice (more corrosive) member made of a material larger in an iodization tendency than that of the tubes (12a). As a result, it is possible to prevent the tubes (12a) from being corroded due to the same reason as in the fifth aspect.

According to an eighth aspect, in the heat exchanger disclosed in any one of the first to the seventh aspects, the heat exchanger is characterized in that the tubes (12a) have a thickness of 0.3 mm or less.

From reasons such as the weight reduction of the heat exchanger main body and the improvement of the heat transmitting coefficient from the tubes (12a) to the fins (12b), the plate thickness of tubes (12a) is reduced so as to provide a thin plate not more than 0.3 mm. If the construction of the patent document 1 shown in FIG. 13 is formed by using the tubes (12a) with less thickness, the tubes (12a) are remarkably likely to be damaged due to the heat stress caused by the temperature difference between the reinforcement members (14) and the tubes (12a).

In the eighth aspect however, due to the effects of the construction described in the first to the sixth aspects, the temperature difference between the reinforcement members (14) and the tubes (12a) can be made smaller and, therefore, it is possible to prevent the tubes (12a) from being damaged even if the plate thickness of the tubes (12a) is reduced into a thickness not more than 0.3 mm.

In a ninth aspect of the present invention, according to the heat exchanger in any one of the first to third aspects, the tube (12a) and the reinforcement member (14) are in contact with each other in a range of more than a half of the length (Lt) along the flowing direction of the second fluid in the tube (12a).

According to this aspect, the contacting area of the reinforcement member and the tube is increased in comparison with those of the radiator according to the third or the fourth aspect and therefore, the heat of the tubes is transmitted to the reinforcement member without fail and it is possible to surely reduce the temperature difference between the reinforcement member and the tube. In addition, it is possible to prevent the tube from being inflated or deformed due to the internal pressure of the tube, by the reinforcement member.

Moreover, in a case of the heat exchanger of the third or the fourth aspect according to the present invention, the wide area on the surface of the tube near the reinforcement member is exposed to the outside.

On the other hand, in the ninth aspect according to the present invention the area of the exposed surface of the tube near the reinforcement member is reduced and therefore, the corrosion resistance quality of the tube is advantageously improved.

In a tenth aspect of the present invention, according to the heat exchanger of the ninth aspect, the reinforcement member (14) is formed so that a section of the reinforcement member perpendicular to a longitudinal direction of the reinforcement member (14) becomes a U shape having a bottom portion (14a) and an opening portion, and the bottom portion (14a) is formed to come into contact with the tube (12a).

Due to this, it is possible to effectively transmit heat of the tube to the wall portion (14c) of the reinforcement member. In addition, as the reinforcement member having a sectional shape with higher strength with respect to the bending force and the torsional force reinforces the core portion together with the tanks it is possible to improve the reinforcement ability for the core portion.

In an eleventh aspect of the present invention, according to the heat exchanger of the tenth aspect, on a bottom portion (14a) of the reinforcement member (14), holes (14c) penetrating through the bottom portion (14a) are formed.

In this configuration, when the reinforcement member and the tube are joined with each other by brazing, for example, as the holes are provided on the reinforcement member the brazing material gathers into the portions in which the reinforcement member and the tube are in contact with each other so that it is possible to fix the reinforcement member to the tube more securely. In addition, it is possible to check the brazing condition through the holes.

The symbols in the parenthesis attached to each means described above indicate a correspondence with the specific means in the embodiments to be described later.

The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a plan view showing a first embodiment of the present invention in which the present invention is applied to a radiator.

FIG. 2 is a plan view of the radiator according to the first embodiment of the present invention.

FIG. 3 is an enlarged partial view of C portion in FIG. 1.

FIG. 4A is a partial sectional view taken along the line A-A in FIGS. 1 and 3.

FIG. 4B is a partial sectional view taken along the line B-B in FIGS. 1 and 3.

FIG. 5 is a front view of a portion of a radiator according to a second embodiment of the present invention which corresponds to C portion in FIG. 1.

FIG. 6 is a plan view of the portion shown in FIG. 5.

FIG. 7 is a partial sectional view taken along the line E-E in FIG. 5.

FIG. 8 is a perspective view of a radiator according to a third embodiment of the present invention.

FIG. 9 is an enlarged perspective view of the F portion in FIG. 8.

FIG. 10 is a drawing when viewed from the G arrow direction in FIG. 9.

FIG. 11 is a perspective view of main components of a radiator according to a fourth embodiment of the present invention.

FIG. 12 is a perspective view of main components of a radiator according to a fifth embodiment of the present invention.

FIG. 13 is a perspective view of a radiator according to patent document 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(First Embodiment)

FIGS. 1 and 2 show a radiator 10 according to a first embodiment of the present invention. The radiator 10 which cools a cooling water absorbing heat from a heat source such as an engine, as is generally known, is mounted on a vehicle, so that the radiator is supplied with and is collided by a cooling air flow blown from a blower (not shown) installed on the upstream side in the air flow. The arrows of the upward and the downward in the figure indicate the upward direction and the downward direction in a state in which it is mounted on the vehicle.

A substantially rectangular prism shaped flow-in side tank is denoted by the number 11 in the figure and is arranged so that the longitudinal direction thereof becomes the vertical direction in the arrangement. Naturally, the top surface and the bottom surface of the flow-in side tank 11 are closed. The flow-in side tank 11 is provided with a cylindrical cooling water inlet port 11a. The cooling water inlet port 11a is connected with a rubber hose (not shown in the figure) through which cooling water flows which has absorbed heat from a heat source such as an engine and has become high in a temperature.

The flow-in side tank 11 is provided with a plurality of holes (not shown) the number of which corresponds to that of the tubes 12a. An end of each tube 12a is inserted into a hole. The other end of the tube 12a is inserted into a hole provided in a flow-out side tank 13 as is the flow-in side tank 11. The flow-out side tank 13 has a substantially rectangular prism shape and is arranged so that the longitudinal direction thereof becomes the vertical direction V in the arrangement.

The tube 12a has a flat shape which is reduced in a vertical direction thereof and fins 12b which are formed in a corrugated shape are arranged so as to come into contact with the flat surfaces of the tube 12a. In this configuration, the tubes 12a and the fins 12b are in a state of being piled up in layers in a vertical direction V in the figure. An assembly comprising the tubes 12a and the fins 12b are referred hereinafter as a core portion.

The flow-out side tank 13 is provided with a cylindrical cooling water outlet port 13a. The cooling water outlet port 13a is connected with a rubber hose (not shown in the figure) through which a cooling water cooled as described below re-circulates toward the heat source (an engine).

These components, such as the cooling water inlet port 11a, the tanks 11 and 13, the cooling water outlet port 13a, the tubes 12a and the fins 12b, are made of an aluminum alloy, and are integrally assembled in a unit by brazing, welding or the like.

In the present embodiment, the tubes 12a are arranged at the ends of the core portion 12 in the vertical direction V thereof and, therefore, the tubes 12a can be fixed on the inserts 14 which are the reinforcement members of the core portion 12. Insertion holes (not shown) in which the parts for securing, such as bolts, are inserted when they are used for attaching the radiator 10 to a vehicle are formed on the inserts 14. Thus the inserts 14 often act as members on which some components are installed, in addition to having roles as reinforcement members.

At first, the shape of the insert 14 is explained with reference to FIG. 4A. The insert 14 is formed from a plate of thickness about 1.5 to 2 mm by a pressing process so that the sectional area of the insert 14 perpendicular to the longitudinal direction of the inserts 14 (the same direction as the longitudinal direction L of the tubes 12a) is made in a recess shape having a bottom portion 14a and an opening. Further, on the bottom portion 14a of the insert 14, the insert 14 is provided with a protrusion 14b protruding toward the outside direction of the insert 14 (the downward direction in FIG. 4A). Due to the protrusion 14b, the sectional area of the insert 14 perpendicular to the longitudinal direction of the inserts 14 is made in a shape which has steps and the width is narrowed to form two steps.

The surface of a plate of the insert 14 which is the side from which the protrusion 14b protrudes (the surface on the side contacting the tube 12a) is clad with a material, such as titanium, copper, or the alloy thereof, that has an ionization tendency larger than that of an aluminum alloy which makes up the tubes 12a, etc.

Next, the fixing structure of the insert 14 and the tube 12a is explained. The insert 14 and the tube 12a are integrally fixed by the brazing, welding or the like as described above, at an area thereof nearer the center of the core portion 12 from voluntary point D (refer to FIG. 3 and FIG. 4A) in the longitudinal direction L of the tubes 12a. On the other hand, the insert 14 and the tube 12a are not integrally fixed and are separated with each other at an area outside of the core portion 12 from the point D (refer to FIG. 4B) and are fixed to the tank 13 independently with each other in a separated state.

FIG. 3 shows a fixing structure in which the insert 14 is fixed to the flow-out side tank 13 and the tubes 12a are fixed to the flow-out side tank 13. The fixing structure in which the inserts 14 are fixed to the flow-in side tank 11 and the tubes 12a are fixed to the flow-in side tank 11 are the same.

Next, the operation of the present embodiment in the above configuration is explained. The cooling water of high temperature absorbing heat from the heat source such as an engine flows into the flow-in side tank 11 from the cooling water inlet port 11a. The cooling water then is divided to flow into a plurality of the tubes 12a from the flow-in side tank 11 and flows toward the flow-out side tank 13. At this time, the heat of the cooling water flowing through the tubes 12a is transmitted to the fins 12b and the air (indicated by the arrow W) flowing through the fins 12b absorbs the transmitted heat. Thus, the cooling water which is cooled and is brought into a low temperature state flows into the flow-out side tank 13.

The cooling water which flows from the respective tubes 12a and is gathered into the flow-out side tank 13 returns from the outlet port 13a to the engine (the heat source).

The functions and effects of the first embodiment are listed below.

(1) As the tubes 12a are arranged on the ends of the core portion 12 in the vertical direction V thereof and are fixed on the inserts 14 which are the reinforcement members of the core portion 12, the tubes 12a can be prevented from being damaged by thermal stress caused by a temperature difference between the tubes 12a and the inserts 14.

Due to this construction, compared to the prior art shown in FIG. 8 and having a construction in which the inserts 14 and fins 12b are fixed to each other, the temperature difference between the tubes 12a and the inserts 14 can be made smaller. Therefore, heat stress caused by the temperature difference is unlikely to be produced so that the tubes 12a are prevented from being damaged by the heat stress.

In addition, the heat of the tubes 12a integrally fixed to the inserts 14 is transmitted to the inserts 14 and therefore, the heat radiation ability of the tubes 12a can be enhanced.

Moreover, compared to the prior art, the number of the tubes 12a are increased (to a total two, upper and lower) by fixing the tubes 12a to the inserts 14 because the tubes 12a occupy only a small space. Therefore, the passage area (the total sectional area of the tubes) through which the cooling water flows is increased so that the flow resistance of the cooling water can be reduced.

The conventional fins 12b integrally fixed with the conventional inserts 14, that is, the fins 12b provided on the both ends (the upper end and the lower end) in the piling direction V, has a low heat radiation efficiency because only one side of the fin 12b is in contact with the tube 12a which is the heat source. On the other hand, in the present embodiment, as the tubes 12a are provided on the both ends in the piling direction V, the both sides of all fins 12b are in contact with the tubes 12a which are the heat source. Therefore, the heat radiation efficiency of the fins 12b on the both ends (an upper end and a lower end) in the piling direction V can be improved.

These effects can be realized with substantially no change of the dimension of the layers of the tubes 12a and fins 12b in the piling direction V thereof. Exactly speaking, the dimension of the layers is increased in the piling direction V by the size of two tubes 12a but the size of the tube 12a in the piling direction V is around a few millimeters. In addition, these effects are particularly remarkable in the case where the thickness of the tube 12a is reduced to 0.3 mm or less because of a recent tendency in which the weight of the main body of a heat exchanger has been reduced, the heat transmitting coefficient from the tube 12a to the fin 21b has been improved, and the like.

(2) As the respective inserts 14 and the respective tubes 12a are independently fixed to the tanks 11 and 13, the inserts 14 and tanks 11, 13, and the tubes 12a and tanks 11, 13 can be fixed without leakage of the cooling water.

On the other hand, when the ends of the insert 14 and the tube 12 integrally connected to each other are inserted into the holes on the tanks 11 and 13 and the inserted ends are fixed by brazing, welding or the like, the cooling water in the tanks 11, 13 may leak out therefrom at the contacting surface between the surface of the insert 14 and the surface of the tube 12a, or the like.

To the contrary, in the present embodiment, the insert 14 and the tube 12a are independently and respectively fixed to the tanks 11 and 13 so that there is no contacting surface between the surface of the insert 14 and the surface of the tube 12a from which contacting surface the cooling water may leak out. Therefore, the inserts 14 can be easily fixed to the tanks 11, 13 without a leakage of the cooling water.

(3) The insert 14 is formed in a sectional shape the width of which is narrowed to form two steps (refer to FIG. 4A), that is stronger against a bending force and a torsional force, and the protrusion 14b is fixed to the flat surface of the tube 12a and, therefore, the reinforcement ability of the core portion 12 can be further improved. The expression “stronger against a bending force and a torsional force” has the same meaning as the expression “the geometric moment of inertia is larger”.

(4) As the protrusion 14b of the insert 14 contacted with and fixed by the tube 12a is clad with a material larger in an ionization tendency than that of the material making up the tube 12a, the corrosion resistance of the tube 12a can be improved.

If the tube 12a is corroded and forms pitting holes, the cooling water naturally leaks out therefrom. Because of this, in the present embodiment, the side surfaces of the protrusion 14b of the insert 14 are clad with a material such as titanium, copper or alloy thereof larger in an ionization tendency than that of an aluminum alloy making up the tube 12a, etc. By this configuration, the clad material larger in an ionization tendency than that of the tubes 12a is corroded earlier than the tubes 12a and therefore, the tubes 12a are prevented from being corroded, in other words, the anti-corrosive ability of the tubes 12a can be improved.

(Second Embodiment)

A radiator according to a second embodiment has substantially the same configuration as that of the first embodiment but the shape of the inserts 14 is different from that of the first embodiment. The inserts 14 of the first embodiment have a constant sectional shape (refer to FIG. 4A) at the positions nearer to the center side of the core portion than D point in FIG. 3.

On the other hand, the inserts 14 of the present invention when viewing them from the direction from which the cooling air flows into the core portion (that is, the vertical direction on the paper of FIG. 5), are formed to have fixing portions (corresponding to ON portions in FIGS. 5 and 6) in which the insert 14 and a tube 12a are in contact with and fixed to each other and separated portions (corresponding to OFF portion in FIGS. 5 and 6) in which the insert 14 and the tube 12a are separated from each other.

At the fixing portions ON, the insert 14 has a sectional shape the width of which is narrowed to form two steps, as shown in FIG. 4A and, on the other hand, at the separated portions OFF the insert 14 has a sectional shape like a recess as shown in FIG. 7. The fixing portions ON and the separated portions OFF are alternately provided in the longitudinal direction L of the tubes 12a.

According to this construction, in a case where the insert 14 and the tube 12a are fixed to each other, for example, by brazing, as a brazing material is collected in the fixing portions ON where the insert 14 and the tube 12a are in contact with each other, the insert 14 and the tube 12a can be more securely fixed to each other.

Moreover, as the cooling air can pass through the separated portions OFF the heat can be promoted to be radiated from the cooling water flowing through the tube 12a integrally fixed with the insert 14. Therefore, the radiation ability of the radiator can be enhanced.

This embodiment can perform the same functions and effects (1) to (4) as described in the first embodiment.

(Third Embodiment)

A third embodiment of the present invention will be explained below. FIG. 8 shows a perspective view of a radiator according to the third embodiment of the present invention, FIG. 9 shows an enlarged perspective view of F portion in FIG. 8, and FIG. 10 shows a drawing when viewed in the G arrow direction in FIG. 9. In those figures, parts of this embodiment, the same as or equivalent to those of the first embodiment, are denoted with the same symbols attached thereto and these parts are not explained here.

In each embodiment described above, the cooling water inlet port 11a, the tanks 11 and 13, the cooling water outlet port 13a, the tubes 12a and the fins 12b are made of an aluminum alloy, however in the present embodiment, parts of the tanks 11, 13, the cooling water inlet port 11a, and the cooling water outlet port 13a are made of a resin, such as a nylon or the like.

As shown in FIGS. 8 and 9, a flow-in side tank 11 for cooling water comprises a tank body 111 having a substantially rectangular columnar shape with an open portion at one of the faces thereof, and a plate-shaped core plate 112 closing the open portion of the tank body 111. The tank body 111 is made of a resin and is integrally formed with the cooling water inlet port 11a. The core plate 112 is made of an aluminum alloy.

The tank body 111 and the core plate 112 are integrated with each other by calking the outer peripheries of the core plate 112. An O-ring (not shown in the figures) for sealing is installed between the tank body 111 and the core plate 112.

The holes (not shown in the figures) into which the tubes 12a are inserted are formed on the core plate 112 and one end of the tube 12a is inserted into the hole. A protruding piece 112a which fixes the insert 14 by calking is formed on the core plate 112.

The flow-out side tank 13 for cooling water has a similar configuration as that of the flow-in side tank 11 and comprises a tank body 131, a core plate 132 and an O-ring (not shown in the figures), and protruding pieces 132a are formed on the core plate 132.

The inserts 14 which are made by pressing a plate material made of an aluminum alloy and a section perpendicular to the longitudinal direction of the insert 14 (the same direction as the longitudinal direction L of the tubes 12a) as shown in FIG. 10 is formed so that it becomes a U shape having a flat bottom portion 14a and an opening portion.

The length Li of the insert 14 along the air flowing direction is made substantially equal to the length Lt of the tube 12a along the air flowing direction and thereby, the contacting area of the insert 14 and the tube 12a is maintained sufficiently by joining the bottom portion 14a of the insert 14 to the flat surface of the tube 12a by brazing, welding or the like.

The bottom portion 14a of the insert 14 and the flat surface of the tube 12a are in contact with each other in a range more than a half of the length Lt of the tube 12a, in the air flowing direction, and desirably in a range more than two third of the length Lt.

As shown in FIG. 8 and FIG. 9, on the bottom portion 14a holes 14c are formed which penetrate through the bottom portion 14a. A number of the holes 14c having an oval shape the long side of which is parallel to the longitudinal direction of the insert 14 are arranged along the longitudinal direction of the insert 14.

Installation pieces 14d which extend from the bottom portion 14a and are bent in a L shape are formed on the both ends in the longitudinal direction of the insert 14. In detail, the installation piece 14d extend toward the tank 11 or 13 and in a state parallel to the longitudinal direction L of the tube 12a after extending toward the opposite side of the tube 12a (the outside of the lamination direction of the tubes) from the bottom portion 14a.

The installation pieces 14d are held in a sandwiched state between the main body of the core plate 112, 132 and the protruding piece 112a, 132a by calking the protruding piece 112a, 132a of the core plate 112, 132.

According to the present embodiment, the parts of the tanks 11, 13, the cooling water inlet port 11a and the cooling water outlet port 13a are made of a resin and therefore, the weight of the radiator can be reduced and the cost thereof can be reduced.

As the bottom portion 14a of the insert 14 and the flat surface of the tube 12a are made to come into contact with each other in a range of more than a half of the length Lt of the tube 12a along the air flowing direction, the contact area of the insert 14 and the tube 12a in this embodiment is increased in comparison with those of the radiators according to the first and the second embodiments and therefore the heat of the tubes 12a is transmitted to the insert 14 without fail and it is possible to surely reduce the temperature difference between the insert 14 and the tube 12a.

In addition, it is possible to prevent the tubes 12a from being inflated or deformed due to the internal pressure of the tubes, by using the insert 14.

The area of the exposed surface of the tube 12a at the insert 14 side is reduced in comparison with those of the radiators according to the first and the second embodiments and therefore, the corrosion resistance of the tubes 12a is advantageously improved.

As the insert 14 which has a sectional shape with higher strength with respect to the bending force and the torsional force reinforces the core portion 12 together with the tanks 11, 13, it is possible to improve the reinforcement performance of the core portion 12.

When the insert 14 and the tube 12a are joined with each other by brazing as the holes 14a are provided on the insert 14 the brazing material gathers into the portions in which the insert 14 and the tube 12a are in contact with each other (in which there is no hole 14a) it is possible to fix the insert 14 to the tube 12a more surely. In addition, it is possible to check the brazing condition through the holes 14c.

As the insert 14 and the tube 12a are independently fixed to the tanks 11, 13 respectively, it is possible to join the insert 14 and the tubes 12a with the tanks 11, 13 without leakage of the cooling water.

(Fourth Embodiment)

A fourth embodiment of the present invention will be explained below. FIG. 11 shows a perspective view of main components (corresponding to the F portion in FIG. 8) of a radiator according to the fourth embodiment of the present invention. In the figures, the parts of the embodiment same as or equivalent to those of the third embodiment are denoted with the same symbols attached thereto and these parts are not explained here.

As shown in FIG. 11, installation pieces 14d extending from the bottom portion 14a are provided on the both ends in the longitudinal direction of the insert 14. More specifically, the installation piece 14d extends in an oblique direction from the bottom portion 14a toward the tank 11 or 13 and at the opposite side of the tube 12a (to the outside in the lamination direction V of the tubes).

On the core plate 112 holes (not shown in the figure) into which the installation pieces 14d are inserted are formed and the ends of the installation pieces 14d are inserted into the holes.

The holes into which the installation pieces 14d are inserted are independently provided and separated from the holes into which the tubes 12a are inserted. Though not shown in the figure, the holes (not shown in the figure) into which the installation pieces 14d are inserted are formed on the core plate 132 of the flow-out side tank 13 and the ends of the installation pieces 14d are inserted into the holes.

According to this embodiment, the insert 14 and the tube 12a are independently fixed to the tanks 11, 13 respectively, so that it is possible to join the insert 14 and the tube 12a with the tanks 11, 13 without the leakage of cooling water.

(Fifth Embodiment)

A fifth embodiment of the present invention will be explained below. FIG. 12 shows a perspective view of main components (portions corresponding to the F portion in FIG. 8) of a radiator according to the fourth embodiment of the present invention. In the figures, the parts of the embodiment same as or equivalent to those of the third and fourth embodiments are denoted with the same symbols attached thereto and these parts are not explained here.

Though in the fourth embodiment, the insert 14 and the tube 12a are independently fixed to the holes formed on the core plate 112, 132 respectively, as shown in FIG. 12, the end of the insert 14 and the end of the tube 12a both may be inserted into one hole formed on the core plate 112, 132 so as to be fixed to the hole by brazing, welding or the like.

(Other Embodiments)

In the embodiments described above, the radiator 10 in which the cooling water absorbing heat from a heat source is made to radiate heat are used as an example of the heat exchanger, but the heat exchanger may be a condenser in which a gas-phase refrigerant is condensed into a liquid-phase refrigerant by heat exchanging in the heat exchanger. Further, the effects of the present invention can be naturally realized in a heat exchanger in which a liquid-phase refrigerant is evaporated into a gas-phase refrigerant by the heat exchanging in the heat exchanger, that is, an evaporator.

In the above-mentioned embodiments, the examples in which the inserts 14 and the tubes 12a are fixed to each other by brazing, welding, or the like are shown but the effects of the present invention can be performed even in a case where the inserts 14 and the tubes 12a come into contact with each other.

In the above-mentioned embodiments, the examples in which the tanks 11 and 13 are arranged at the both ends of the tubes 12a are shown but a configuration in which the tubes are formed in a U shape and the fluid flows out from and into one tank may be applied. In this case, the inside space of the tank is necessarily separated into a flow-out space and a flow-in space.

In the above-mentioned embodiments, an example in which the fixing surfaces (the protrusions 14b) at which the insert 14 and the tube 12a are fixed to each other are clad with a material larger in an ionization tendency than that of the tubes 12a are shown but on the reverse side of the tube 12a, that is, on the bottom surface 14a side of the insert 14a material may be clad. Alternatively, an independent part (for example, a plate material) which is made of a material larger in an ionization tendency may be integrally fixed to the insert 14.

Further alternatively, the insert 14 itself may be made of a material larger in an ionization tendency. The basic material making up the insert 14 may be added with a material larger in an ionization tendency by a specific ratio with respect to the basic material, thereby making a part including the material having larger ionization tendency by a higher ratio (more rich) corrode first.

Though in the third to the fifth embodiment, the holes 14c are formed on the bottom portion 14a of the insert 14, the holes 14c may not be formed on the bottom portion 14a of the insert 14. In this case, the contacting area of the insert 14 and the tube 12a is further increased.

While the invention has been described by reference to specific embodiments chosen for the purposes of illustration, it should be apparent that numerous modifications could be made thereto, by those skilled in the art, without departing from the basic concept and scope of the invention.

Claims

1. A heat exchanger comprising:

a core portion having a plurality of tubes through which a first fluid flows and which are arrange so as to be laid in layers, and fins arranged between a plurality of the tubes and for promoting heat exchanging between the first fluid and a second fluid flowing through a space between the tubes; and

tanks arranged at ends of the tubes and communicating with a plurality of the tubes; and

reinforcement members fixed to the tanks and for reinforcing peripheries of the core portion as well as the tanks; wherein

the reinforcement members and the tubes of a plurality of the tubes arranged at the outermost ends in a piling direction of the tubes are arrange so that the tube and the reinforcement member come into contact with each other.

2. The heat exchanger as set forth in claim 1, wherein the reinforcement members are integrally fixed to the tubes of the core portion.

3. The heat exchanger as set forth in claim 1, wherein the reinforcement members and the tubes are independently and respectively fixed to the tanks.

4. The heat exchanger as set forth in claim 1; wherein

the reinforcement members are formed in a recess shape a sectional area of which in a direction perpendicular to a longitudinal direction of the reinforcement members has a bottom portion and an opening; wherein

on the bottom portion of the recess shape a protrusion protruding toward an outside of the reinforcement member is formed; and wherein

the protrusion and the tube are formed so as to come into contact with each other.

5. The heat exchanger as set forth in claim 1; wherein

in a state in which the reinforcement member and the tube are integrally fixed to each other, when viewing from a direction in which the second fluid flows into spaces between the tubes, the reinforcement member is formed to have fixing portions at which the reinforcement member is in contact with the tube and separated portions at which the reinforcement member is separated from the tube.

6. The heat exchanger as set forth in claim 1, wherein at least a part of the reinforcement member is made of a material larger in an iodization tendency than that of the tubes.

7. The heat exchanger as set forth in claim 1, wherein the reinforcement member is attached with a sacrificial member made of a material larger in an iodization tendency than that of the tubes.

8. The heat exchanger as set forth in claim 1, wherein the tubes have a thickness of 0.3 mm or less.

9. The heat exchanger as set forth in claim 1, wherein the tube and the reinforcement member are in contact with each other in a range of more than half the length in a flowing direction of the second fluid in the tube.

10. The heat exchanger as set forth in claim 9, wherein the reinforcement member is formed so that a section of the reinforcement member perpendicular to a longitudinal direction of the reinforcement member becomes a U shape having a bottom portion and an opening portion and the bottom portion is formed to come into contact with the tube.

11. The heat exchanger as set forth in claim 10 wherein, on a bottom portion of the reinforcement member, holes penetrating through the bottom portion are formed.