U.S. patent application number 10/859488 was filed with the patent office on 2004-12-09 for heat exchanger.
Invention is credited to Goto, Tetsuya, Hayasaka, Atsushi, Okochi, Takaki, Sonoda, Yoshihiko.
Application Number | 20040244954 10/859488 |
Document ID | / |
Family ID | 33487502 |
Filed Date | 2004-12-09 |
United States Patent
Application |
20040244954 |
Kind Code |
A1 |
Goto, Tetsuya ; et
al. |
December 9, 2004 |
Heat exchanger
Abstract
A heat exchanger includes plural laminated tubes through which a
coolant from a fuel cell flows, fins arranged between the tubes and
at outermost sides in a lamination direction of the tubes, core
plates connected to longitudinal end portions of the tubes, and
tank members attached to the core plates to form tank spaces. The
tubes are made of a first insulating material, and the fins and the
core plates are bonded to the tubes by using metal parts provided
separately from each other on surfaces of the tubes. In addition, a
coating portion is coated with a second insulating material on
surfaces of the core plates at least at an exposed position of the
core plates and at positions around brazing portions of the core
plate bonded to the tubes. Accordingly, the heat exchanger can be
insulated from the fuel cell without using an electrical insulating
liquid.
Inventors: |
Goto, Tetsuya; (Anjo-city,
JP) ; Okochi, Takaki; (Chiryu-city, JP) ;
Sonoda, Yoshihiko; (Tokoname-city, JP) ; Hayasaka,
Atsushi; (Kariya-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
33487502 |
Appl. No.: |
10/859488 |
Filed: |
June 2, 2004 |
Current U.S.
Class: |
165/153 ;
165/133 |
Current CPC
Class: |
H01M 8/04067 20130101;
F28F 2265/24 20130101; Y02E 60/50 20130101; F28F 21/067 20130101;
F28F 21/04 20130101; F28D 1/05366 20130101; F28F 19/04 20130101;
H01M 8/04029 20130101; F28F 9/0226 20130101 |
Class at
Publication: |
165/153 ;
165/133 |
International
Class: |
F28D 015/00; F28F
013/18; F28F 019/02; F28D 001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 5, 2003 |
JP |
2003-161045 |
Claims
What is claimed is:
1. A heat exchanger comprising: a plurality of tubes through which
a coolant from a fuel cell flows to perform heat exchange, the
tubes being laminated in a lamination direction and made of a first
insulating material; a plurality of fins arranged between adjacent
the tubes and outermost sides of the tubes in the lamination
direction to be bonded to the tubes; a core plate connected to one
longitudinal end portion of each tube; and a tank member made of
resin, the tank member being attached to the core plate at a side
opposite to the tubes with respect to the core plate, wherein the
tank member and the core plate are attached to form a tank space
communicating with the tubes, wherein: the tubes have a plurality
of metal parts separated from each other on outer surfaces of the
tubes; and the fins and the core plate are bonded by brazing to the
outer surfaces of the tubes at the metal parts.
2. The heat exchanger according to claim 1, further comprising a
coating portion coated by a second insulating material on one
surface of the core plate opposite to the tank space wherein: the
core plate has an exposed portion exposed to outside from the
tubes, and brazing portions brazed to the tubes; and the coating
portion is provided at least on the exposed portion and at
positions around the brazing portions of the core plate.
3. The heat exchanger according to claim 2, further comprising
first and second side plates arranged at the outermost fins in the
lamination direction for reinforcing to extend in a longitudinal
direction of the tubes, wherein: at least one longitudinal end
portion of each side plate is made of the first insulating
material; the one longitudinal end portion of each side plate has a
brazing portion brazed to the core plate through a metal part
provided on a surface of the longitudinal end portion of each side
plate; and the coating portion is provided on the core plate at a
position around the brazing portion of each side plate.
4. The heat exchanger according to claim 1, further comprising
first and second side plates arranged at the outermost fins in the
lamination direction for reinforcing to extend in a longitudinal
direction of the tubes, wherein: at least one longitudinal end
portion of each side plate is made of the first insulating
material; the one longitudinal end portion of each side plate has a
brazing portion brazed to the core plate through a metal part
provided on a surface of the longitudinal end portion of each side
plate; and the brazing portion of the longitudinal end portion of
each side plate is separated from positions where the tubes are
brazed to the core plate.
5. The heat exchanger according to claim 1, further comprising
first and second side plates arranged at the outermost fins in the
lamination direction for reinforcing to extend in a longitudinal
direction of the tubes, wherein: all the side plates are made of
the first insulating material; and each of the side plates further
has a first metal part provided on its surface to be bonded to the
outermost fin, and a second metal part provided separately from the
first metal part on its surface to be bonded to the core plate.
6. A heat exchanger comprising: a plurality of tubes through which
a coolant from a fuel cell flows to perform heat exchange, the
tubes being laminated in a lamination direction and made of a first
insulating material; a plurality of fins arranged between adjacent
the tubes and outermost sides of the tubes in the lamination
direction to be bonded to the tubes; a core plate connected to one
longitudinal end portion of each tube; a tank member made of resin,
the tank member being attached to the core plate at a side opposite
to the tubes with respect to the core plate, wherein the tank
member and the core plate are attached to form a tank space
communicating with the tubes; a plurality of first metal parts
provided on outer surfaces of the tubes to be bonded to the fins;
and a plurality of second metal parts provided on the outer
surfaces of the tubes to be bonded to the core plate, wherein the
second metal parts are provided on the outer surfaces of the tubes
to be separated from the first metal parts.
7. The heat exchanger according to claim 6, wherein: the first
metal parts are provided on the outer surfaces of the tubes to be
separated from each other; and the second metal parts are provided
on the outer surfaces of the tubes to be separated from each
other.
8. The heat exchanger according to claim 6, wherein the first metal
part and the second metal part are provided on the surface of each
tube to cover a part of the outer surface of each tube and to have
an uncovered part between the second metal part and the first metal
part.
9. A heat exchanger comprising: a plurality of tubes through which
a coolant from a fuel cell flows to perform heat exchange, the
tubes being laminated in a lamination direction and made of a first
insulating material; a plurality of fins arranged between adjacent
the tubes and outermost sides of the tubes in the lamination
direction to be bonded to the tubes; a core plate connected to one
longitudinal end portion of each tube; a tank member made of resin,
the tank member being attached to the core plate at a side opposite
to the tubes with respect to the core plate, wherein the tank
member and the core plate are attached to form a tank space
communicating with the tubes; a first metal part provided on an
outer surface of each tube to be bonded to the fins; and a second
metal part provided on the outer surface of each tube to be bonded
to the core plate to have an uncovered part on the surface of each
tube between the second metal part and the first metal part.
10. The heat exchanger according to claim 1, wherein the first
insulating material is a ceramic material.
11. The heat exchanger according to claim 1, wherein the core plate
and the fins are made of a metal material.
12. The heat exchanger according to claim 1, wherein the tank
member and the core plate are arranged at both the longitudinal end
portions of each tube to form the tank space at two longitudinal
sides of the tubes.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2003-161045 filed on Jun. 5, 2003, the disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a heat exchanger for
cooling a fuel cell of a fuel-cell powered vehicle. In the heat
exchanger, cooling water can be used as a coolant.
BACKGROUND OF THE INVENTION
[0003] In a cooling system of a fuel cell described in
JP-A-2002-33108 (corresponding to US Patent Application Publication
2002/31693), a radiator (heat exchanger) is provided in a coolant
circulation passage through which a coolant is circulated in the
fuel cell. Further, as the coolant, an electric insulation liquid
material is used. For example, the electric insulation liquid
material is fluorinert (Sumitomo 3M make) of a fluoride inet liquid
or an insulating oil. Furthermore, an insulating material is
interposed between the fuel cell and the coolant circulation
passage, or the coolant circulation passage is formed from an
insulating material, so that the radiator is electrically insulated
from the fuel cell.
[0004] However, the electrical insulating liquid such as the
fluorinert has a low electrical conductivity as compared with a
general coolant such as water and ethylene glycol. Therefore, it is
difficult to sufficiently improve cooling performance in the
radiator. Further, manufacturing cost of the cooling system of the
fuel cell is increased because the electrical insulating liquid
such as the fluorinert is expensive as compared with the general
coolant.
[0005] Each component of the radiator may be formed by an
insulation material in order to provide the insulating performance
in the radiator while the general coolant is used. However, in this
case, heat conductivity of the radiator is greatly deteriorated,
and it is difficult to obtain a necessary cooling capacity in the
radiator.
SUMMARY OF THE INVENTION
[0006] In view of the above-described problems, it is an object of
the present invention to provide a heat exchanger which can be
insulated from a fuel cell without using an electrical insulating
liquid as the coolant while cooling performance of the heat
exchanger is not largely deteriorated.
[0007] According to the present invention, a heat exchanger
includes a plurality of tubes through which a coolant from a fuel
cell flows to perform heat exchange, a plurality of fins arranged
between adjacent the tubes and outermost sides of the tubes in a
lamination direction of the tubes to be bonded to the tubes, a core
plate connected to one longitudinal end portion of each tube, and a
tank member made of resin. The tubes are made of a first insulating
material, the tank member is attached to the core plate at a side
opposite to the tubes with respect to the core plate, and the tank
member and the core plate are attached to form a tank space
communicating with the tubes. In the heat exchanger, the tubes have
a plurality of metal parts separated from each other on outer
surfaces of the tubes, and the fins and the core plate are bonded
by brazing to the outer surfaces of the tubes at the metal parts.
Because the metal parts are separated from each other on the outer
surfaces of the tubes, it is possible to electrically insulate the
fins and tube parts connected to the fins in the heat exchanger,
even when a water-included liquid is used as the coolant. In
addition, heat exchanging performance can be improved by the fins
made of a metal material.
[0008] Preferably, a coating portion is coated by a second
insulating material on one surface of the core plate opposite to
the tank space. Generally, the core plate has an exposed portion
exposed to outside from the tubes (side plates), and brazing
portions brazed to the tubes. In this case, the coating portion is
provided at least on the exposed portion and at positions around
the brazing portions of the core plate. Accordingly, the insulating
performance on the outer side of the heat exchanger can be
effectively improved even when cooling water is used as the
coolant.
[0009] In the heat exchanger, first and second side plates are
generally arranged at the outermost fins in the lamination
direction for reinforcing to extend in a longitudinal direction of
the tubes. In this case, at least one longitudinal end portion of
each side plate is made of the first insulating material.
Furthermore, the one longitudinal end portion of each side plate
has a brazing portion brazed to the core plate through a metal part
provided on a surface of the longitudinal end portion of each side
plate, and the coating portion is provided at a position around the
brazing portion of each side plate. Therefore, the outside of the
heat exchanger can be accurately insulated from the fuel cell.
[0010] More preferably, the brazing portion of the longitudinal end
portion of each side plate is separated from positions where the
tubes are brazed to the core plate. In this case, the insulating
performance of the side plate can be improved.
[0011] According to the present invention, a first metal part
bonded to the fins and a second metal part bonded to the core plate
are provided on the outer surface of each tube to be separated from
each other on the outer surface of each tube. Therefore, an
uncovered part made of the first insulating material is formed on
the surface of each tube between the second metal part and the
first metal part. Accordingly, the insulating performance of the
heat exchanger can be readily improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] Other objects, features and advantages of the present
invention will become more apparent from the following detailed
description made with reference to the accompanying drawings, in
which:
[0013] FIG. 1 is a schematic diagram showing a fuel cell system
including a fuel cell and a radiator (heat exchanger) according to
a preferred embodiment of the present invention;
[0014] FIG. 2 is a front view showing the radiator in FIG. 1;
and
[0015] FIG. 3 is a cross-sectional view showing a main portion of
the radiator according to the embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] A preferred embodiment of the present invention will be now
described with reference to FIGS. 1-3. A fuel cell system shown in
FIG. 1 includes a fuel cell 10 mounted on a fuel-cell powered
vehicle, and a radiator 100 for cooling the fuel cell 10. A driving
motor for running the vehicle is driven by using the fuel cell 10
as an electrical source. The radiator 100 cools coolant (cooling
water) circulating in the fuel cell 10, so that temperature of the
fuel cell is controlled.
[0017] The fuel cell 10 is constructed with fuel cell stacks
composed of plural cells, and outer casings for accommodating the
fuel cell stacks. Each of the cells of the fuel cell stack is
formed by inserting an electrolyte film between a plus electrode
and a minus electrode so as to generate electrical power by
chemical reaction between hydrogen and oxygen.
[0018] As shown in FIG. 1, a radiator circulation passage 20 made
of an insulating material is connected to the outer casing of the
fuel cell 10 at two positions. For example, the radiator
circulation passage 20 is defined by a rubber hose made of an
insulating rubber material. The radiator 100 and a water pump 21
are arranged in the radiator circulation passage 20 in this order
in a coolant flow direction. By the operation of the water pump 21,
the coolant in the outer casing of the fuel cell 10 circulates in
the radiator circulation passage 20 and the radiator 100 as in the
arrows in FIG. 1. The coolant is an antifreeze liquid obtained by
mixing ethylene glycal into water, for example. This antifreeze
liquid is generally used as the coolant in a general
gasoline-engine vehicle.
[0019] A bypass passage 22 through which the coolant bypasses the
radiator 100 is provided in the radiator circulation passage 20 to
be parallel to the radiator 100. The bypass passage 22 is defined
by a rubber hose made of an insulating rubber material, for
example. A valve 23 is provided at a join portion where the
radiator circulation passage 20 at a downstream side of the
radiator 100 and a downstream side of the bypass passage 22 are
joined. The operation of the valve 23 is controlled by a control
unit (not shown), so that a flow ratio between a coolant amount
passing through the radiator 100 and a coolant amount passing
through the bypass passage 22 can be adjusted. The valve 23 may be
provided in a joint portion where the radiator circulation passage
20 at an upstream side of the radiator 100 and an upstream side of
the bypass passage 22 are joined.
[0020] A reserve tank 24 is provided in the radiator 100 to absorb
a volume expansion part of the coolant when the temperature of the
coolant increases, and to supply a volume contraction part of the
coolant to the radiator 100 when the temperature of the coolant
decreases.
[0021] The radiator 100 includes a core portion 130, an upper tank
member 110 and a lower tank member 120. The radiator 100 is
vertical flow type in which coolant flows in tubes 131 of the core
portion 130 vertically. For example, in FIGS. 2 and 3, the coolant
flows through the tubes 131 downwardly from the upper tank member
110 toward the lower tank member 120. The core portion 130 is
constructed with the plural flat tubes 131, plural fins 132, two
side plates 133 and two upper and lower core plates 134.
[0022] Each of the fins 132 is a corrugated fin formed into a wave
shape by bending a thin plate. The tubes 131 and the fins 132 are
alternately stacked (laminated) in a lamination direction. The side
plates 133 are attached to outermost fins 132 (right and left
outermost sides in FIG. 2) of the stacked member to reinforce the
core portion 130. The side plates 133 are attached to extend in a
longitudinal direction of the tubes 131.
[0023] Each of the core plates 134 is provided with tube holes 134a
in which one end portions of the tubes 133 are inserted, and side
plate holes 134b in which one end portions of the side plates 133
are inserted. In addition, the core plates 134 have tank insertion
portions 134c at its outer peripheral portion, in which outer
peripheral portions of the upper and lower tank member 110, 120 are
inserted so that tank spaces communicating with the tubes 131 are
formed. Furthermore, plural claw portions 134d for fastening the
upper and lower tank members 110, 120 are provided in the core
plate 134 at outer sides of the tank insertion portions 134c.
[0024] The upper tank member 110 and the lower tank member 120 are
made of a resin material such as a nylon material including glass
fiber, to have a heat resistance and a sufficient strength. Each of
the upper tank member 110 and the lower tank member 120 is formed
into an approximate U shape in cross section. An open end of the
tank member 110, 120 faces the core plate 134, and is connected to
the core plate 134 to form the tank space.
[0025] As shown in FIG. 3, a seal member 140 (seal packing) is
inserted between the outer peripheral portion of each tank member
110, 120 around the opening side of each tank member 110, 120 and
the tank insertion portion 134c of the core plate 134, and each
tank member 110, 120 is mechanically connected to each core plate
130 by using claws 134d.
[0026] An inlet pipe 111, a coolant filling port 112 and attachment
portions 113 are provided in the upper tank member 110 integrally
with the upper tank member 110. In contrast, an outlet pipe 121 and
attachment portions 122 are provided in the lower tank member 120
integrally with the lower tank member 120. The inlet pipe 111
through which the coolant in the radiator circulation passage 20
flows into the upper tank member 110 of the radiator 100 is
connected to the radiator circulation passage 20, and the outlet
pipe 121 through which the coolant in the lower tank member 120 is
discharged to the radiator circulation passage 20 is connected to
the radiator circulation passage 20. Accordingly, coolant in the
radiator circulation passage 20 flows into the upper tank member
110 from the inlet pipe 111, flows through the tubes 131 of the
core portions 130, and is collected into the lower tank member 120.
Then, the coolant collected into the lower tank member 120 flows
out of the radiator 100 through the outlet pipe 120.
[0027] Next, the main portion of the present invention will be now
described. In this embodiment, the fins 132 and the core plate 134
are made of a general heat conductive material (metal material)
such as an aluminum or an aluminum alloy. The tubes 131 and the
side plates 133 are made of a ceramic material (first insulating
material) having electrical insulating performance. For example,
the tubes 131 and the side plates 133 are made of a ceramic
material having a high purity alumina as main material. Each of the
tubes 131 and each of the side plates 133 are formed by burning
after being molded by extrusion. When the dimensions of the tubes
131 and the side plates 133 cannot be accurately set only by the
burning, polishing can be performed after the burning, if
necessary.
[0028] The surface of each tube 131 can be provided with a first
metal part 131a around the tube holes 134a of the core plate 134,
and a second metal part 131b contacting fins 132. The metal parts
131a, 131b are formed by providing a metal layer on the ceramic
surface of the tubes 131. The metal parts 131a, 131b can be formed
on the ceramic surface by a direct or an indirect metalization
method or a melting connection method. Further, an Al--Si type
brazing material can be formed on the top surfaces of the metal
parts 131a, 131b in order to readily bond the tubes 131 with the
fins 132 and the core plates 134. The metal parts 131a, 131b are
provided on the outer surface of the tubes 131 made of the ceramic
material to be separated from each other. Therefore, the outer
surface of each tube 131 has uncovered portions (exposed portions)
without the metal parts 131a, 131b between the metal parts 131a and
131b. In addition, the metal parts 131b are provided on the outer
surface of each tube 131 to be separated from each other to have
the uncovered portion between the metal parts 131b, and the metal
parts 131a are provided on the outer surfaces of the tubes 131 to
be separated from each other.
[0029] The surface of each side plate 133 can be provided with
first metal parts 133b contacting the outermost fin 132, and second
metal parts 133a around the side plate holes 134b of the core
plates 134. Similarly to the tubes 131, the first metal part 133b
is provided on the outer surface of the side plate 133 to be
separated from the second metal parts 133a. In addition, the second
metal part 133a provided on the outer surface of the side plate 133
is separated from the metal part 131a provided on the outer surface
of each tube 131.
[0030] By the metal parts 131a, 131b, 133a and 133b, the tubes 131
can be brazed to the core plates 134 and the fins 132,
respectively, and the side plates 133 can be brazed to the core
plates 134 and the fins 132, respectively, in the core portion
130.
[0031] Furthermore, a coating portion 150 is coated by a resin
material (second insulating material) onto the outer surface of the
core plate 134 at least at the exposed portion and positions around
the brazing portions the core plate 134, where the tubes 131 and
the side plates 133 are inserted to be brazed to the core plate
134. Hear, the exposed portion is the part of the core plate 134
exposed to outside from the side plates 133 and the tubes 131. For
example, the coating portion 150 is resin-coated by using a silicon
material (second insulating material). As shown in FIG. 3, the
coating portion 150 is coated at the outside surface opposite to
the tank space of the tank member 120, 130.
[0032] In the fuel cell 10, electrical power is generated by the
chemical reaction between hydrogen and oxygen supplied to both the
electrodes. Heat generated during the electrical power generation
is transmitted to the coolant (cooling water), and flows into the
radiator 100 by the operation of the water pump 21 through the
radiator circulation passage 20. The coolant flowing through the
radiator 100 is cooled, and the cooled coolant is circulated to the
fuel cell 10, so as to control the temperature of the fuel cell 10.
When a generated electrical power amount of the fuel cell 10 is
small, the coolant from the fuel cell 10 flows through the bypass
passage 22 while bypassing the radiator 100, by the operation of
the switching valve 23. Hear, the flow amount of the coolant
flowing through the radiator 100 is adjusted, so that the
temperature of the fuel cell 10 during the operation of the fuel
cell 10 can be controlled in a suitable temperature range.
Generally, the radiator 100 cools the coolant to be equal to or
lower than a predetermined temperature (e.g., 80.degree. C.).
[0033] When the power generation operation of the fuel cell 10 is
performed, a high voltage is applied to the coolant (cooling
water). In this embodiment, the tubes 131 and the side plates 133
are made of an insulating material such as the ceramic material.
Furthermore, the metal parts 131b on the surfaces of the tubes 131,
to be bonded to the fins 132, are separated from the metal parts
131a bonded to the core plate 134, and the metal parts 133b on the
surfaces of the side plates 133, to be bonded to the fins 132., are
separated from the metal parts 133a bonded to the core plate 134.
In addition, the coating portion 150 made of an insulating material
is provided on the outer surface of the core plate 134 at the
exposed portions of the core plates 134, exposed to an outside, and
the portions around the brazing portions (bonding portions) of the
core plates 134, where the tubes 131 and the side plates 133 are
brazed to the core plates 134. Thus, even when the high-voltage
coolant flows in the radiator 100, the high-voltage coolant can be
insulated from the outside of the radiator 100. Thus, it is
unnecessary to use the electrical insulation liquid as the coolant.
Accordingly, cooling water can be used as the coolant in the
radiator 100.
[0034] In this embodiment, the tubes 131 and the side plates 133
can be bonded to the fins 132 made of a metal material such as
aluminum or an aluminum alloy by brazing, using the metal parts
131b, 133b provided separately from each other on the outer
surfaces of the tubes 131 and the side plates 133. Accordingly,
even when the coating portion 150 is not provided at the positions
around the brazing portions of the core plate 134, and even when
the coolant such as the cooling water is used, the insulation of
the fins 132 and the tubes 131 can be obtained.
[0035] Because the fins 132 contained in a large area in the
radiator 100 do not need to be made of an insulating material while
being insulated, heat transmitting performance in the radiator 100
can be improved, and cooling performance for cooling the coolant in
the radiator 100 can be effectively improved.
[0036] Further, the side plates 133 are made of a ceramic material,
and are bonded to the outermost fins 132 in the lamination
direction, similarly to the tubes 131. Therefore, the radiator 100
can be reinforced while the coolant (cooling water) in the radiator
100 can be insulated from the outside of the radiator 100.
[0037] In this embodiment, even when any the tube 131 or the side
plate 133 is not brazed to the core plate 134 to cause a
non-bonding portion, the non-bonding portion is closed by the
coating portion 150. Therefore, the coating portion 150 can be also
used as a seal means between the tubes 131, the side plates 133 and
the core plates 134.
[0038] (Other Embodiments)
[0039] Although the present invention has been fully described in
connection with the preferred embodiment thereof with reference to
the accompanying drawings, it is to be noted that various changes
and modifications will become apparent to those skilled in the
art.
[0040] For example, in the above-described embodiment, the side
plate 133 can be formed to have a first portion made of a ceramic
material and a second portion made of an aluminum material. Hear,
the first portion is a portion around a brazing portion brazed with
the core plate 134, and the second portion is the other portion of
the side plate 133 except for the first portion. In this case, the
metal part 133b provided on the side plate 133 described in the
above embodiment can be omitted.
[0041] Further, for example, when the heat exchanger is assembled
to a vehicle while an outer portion of the core plate 134 is
covered by an insulation member, the outer surface of the heat
exchanger can be insulated with respect to the coolant even when
the coating portion 150 is not provided.
[0042] In the above-described embodiment of the present invention,
the coating portion 150 (coating layer) is coated on the core plate
134 at positions around the bonding portions of the core plate 134
where the longitudinal end portions of the tubes 131 are bonded to
the core plate 134. However, in the present invention, because the
metal parts 131a on the tubes 131 are provided to be separated from
the metal parts 131b on the tubes 131, the coating portion 150
provided at positions around the tube bonding portions of the core
plate 134 can be omitted. Further, the metal parts 131b on the
tubes 131, to be bonded to the fins 132, are separated from metal
part 131a on the tubes 131, to be bonded to the core plate 134.
Therefore, the ceramic surfaces of the tubes 131 are exposed
outside between the metal parts 131b and the metal parts 131a.
Accordingly, the fins 132 and the main parts of the tubes 131
connected to the fins 132 can be electrically insulated.
[0043] In the above-described embodiment, the present invention is
typically applied to the heat exchanger having the upper and lower
tank members 110, 120 and the upper and lower core plates 134.
However, the present invention can be applied to a heat exchanger
only having one side tank and one side core plate. Further, in the
above-described embodiment, the upper and lower tank members 110,
120 and the core plates 134 extend approximately horizontally.
However, the present invention can be applied to a heat exchanger
where the tank members 110, 120 and the core plates 134 extend
approximately vertically or extend in a direction crossing with the
horizontal direction.
[0044] Such changes and modifications are to be understood as being
within the scope of the present invention as defined by the
appended claims.
* * * * *