U.S. patent application number 09/891809 was filed with the patent office on 2001-12-27 for heat exchanger having plural tubes connected to header tanks by brazing.
Invention is credited to Fujiyoshi, Hironobu, Kajikawa, Yoshiharu, Teshima, Shoei.
Application Number | 20010054496 09/891809 |
Document ID | / |
Family ID | 18692194 |
Filed Date | 2001-12-27 |
United States Patent
Application |
20010054496 |
Kind Code |
A1 |
Kajikawa, Yoshiharu ; et
al. |
December 27, 2001 |
Heat exchanger having plural tubes connected to header tanks by
brazing
Abstract
A heat exchanger such as a condenser for use in an automobile
air-conditioning system is composed of a pair of header tanks,
plural tubes connecting both header tanks, and fins made of a thin
aluminum plate disposed between the tubes. Those components are all
connected to one another by brazing to form a unitary body of the
heat exchanger. A solder material for bonding the tubes and the
header tanks is attached onto the inner surface of both header
tanks to prevent the solder material from dispersing into the thin
fins in the brazing process. Thus, the thin aluminum fins are
protected against erosion due to the solder dispersed therein.
Inventors: |
Kajikawa, Yoshiharu;
(Hekinan-city, JP) ; Teshima, Shoei; (Handa-city,
JP) ; Fujiyoshi, Hironobu; (Nishio-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, PLC
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Family ID: |
18692194 |
Appl. No.: |
09/891809 |
Filed: |
June 26, 2001 |
Current U.S.
Class: |
165/133 ;
165/134.1 |
Current CPC
Class: |
F28F 21/084 20130101;
F28D 2021/0084 20130101; F28F 9/0224 20130101 |
Class at
Publication: |
165/133 ;
165/134.1 |
International
Class: |
F28F 013/18; F28F
019/02; F28F 019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2000 |
JP |
2000-193155 |
Claims
What is claimed is:
1. A heat exchanger comprising: a pair of cylindrical header tanks,
each having a fluid passage therein; a plurality of tubes, each
connected between the pair of header tanks to establish fluid
communication between the fluid passages in the pair of header
tanks; and a plurality of fins connected between the tubes in
heat-conductive relation, wherein: a solder material is attached
onto the inner surface of each header tanks; and the tubes are
connected to header tanks by the solder material in a brazing
process.
2. The heat exchanger as in claim 1, wherein: the header tanks, the
tubes and the fins are made of aluminum.
3. The heat exchanger as in claim 1, wherein: a sacrificial
corrosion layer is further attached onto the outer surface of the
header tanks.
4. A method of manufacturing a heat exchanger having a pair of
cylindrical header tanks, a plurality of tubes connected between
the pair of header tanks and a plurality of fins connected between
the tubes, the method comprising: attaching a solder material for
connecting the tubes to the header tanks onto the inner surface of
the header tanks; assembling the header tanks, the tubes and the
fins together to form an assembled unit; and brazing the assembled
unit in a furnace to form a unitary body of the heat exchanger.
5. The method of manufacturing a heat exchanger as in claim 4,
wherein: the method further includes a step of coating a flux
material necessary for brazing on the outer surface of the tubes,
the coating step being performed before the assembling step.
6. A heat exchanger for use in a refrigerating cycle in an
automotive air-conditioner system as a condenser for condensing
over-heated refrigerant supplied thereto, the heat exchanger
comprising: a first header tank made of aluminum having an elongate
inner space; a second header tank made of aluminum having an
elongate inner space; a plurality of tubes made of aluminum, each
connected between the pair of header tanks, so that the refrigerant
introduced into the inner space of the first header tank is
distributed to the plurality of tubes and flows into the inner
space of the second header tank; and a plurality of corrugated
fins, each connected between the tubes in heat-conductive relation,
wherein: a solder layer for connecting the tubes to the header
tanks by brazing is clad on the inner surface of the header tanks.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is based upon and claims benefit of
priority of Japanese Patent Application No. 2000-193155 filed on
Jun. 27, 2000, the content of which is incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a heat exchanger having
plural tubes connected to header tanks by brazing. This invention
is adequately applicable to an automotive heat exchanger such as a
condenser for use in an air-conditioner.
[0004] 2. Description of Related Art
[0005] A condenser having plural tubes connected to header tanks
disposed at both sides of the tubes is known hitherto. A
cross-sectional view of a header tank to which a tube is connected
in a conventional heat exchanger is shown in FIG. 3. Plural
aluminum tubes 14 having refrigerant passages therein are connected
to header tanks disposed at both ends of the tubes. In FIG. 3, only
one tube 11 is shown and another tube is not shown. Aluminum fins
(such fines 15 as shown in FIG. 1) are interposed between
neighboring tubes, and the tubes and fines are laminated forming a
condenser core.
[0006] In the conventional condenser, the header tank 11 is
composed of a first U-shaped plate 111 and a second u-shaped plate
112, both connected to each other. The first U-shaped plate 111 is
a clad plate having a core plate 111a and a solder layer 111b clad
on the outer surface of the core plate 111a. The second U-shaped
plate 112 is also a clad plate having a core plate 112a and solder
layers 112b and 112c which are clad on both inner and outer
surfaces of the core plate 112a. The fins 15 disposed between the
tubes 14 and connected thereto are also made of solder-clad
aluminum, while tubes 14 are made of bare aluminum. Each tube 14
having plural refrigerant passages therein are made by a drawing
process.
[0007] In the assembling process of the condenser, the tubes 14 and
the fins 15 are alternately laminated, and the tubes 14 are
inserted into both header tanks to form a unitary condenser unit.
Flux "f" is coated on the solder layers 111b and 112c which are
clad on the outer surface of the tube 11. Then, the condenser unit
is brazed in a furnace to melt the solder layers and to connect all
the components to one another. In this brazing process, the solder
layer 111b on the outer surface of the first plate 111 connects the
tubes 14 to the first plate 111, and the solder clad on the fins 15
connects the tubes 14 and fins 15 together.
[0008] In the brazing process of the conventional condenser, the
molten solder material is not only used for connecting the first
plate 111 to the tubes 14 but also supplied to the fins 15
connected to the tubes 14, because the solder layer 111b is located
on the outer surface of the header tank 11. Therefore, the solder
from the first plate 111 is added to the clad solder on the fins
15, and solder becomes too rich at the end portions of the fins 15
located close to the first plate 111. In other words, much solder
is dispersed into the end portions of the fins 15, causing erosion
in the fins 15. Though the solder is also dispersed into the tubes
14, the erosion problem is more harmful to the fins 15 because the
fins 15 are much thinner than the tubes 14.
SUMMARY OF THE INVENTION
[0009] The present invention has been made in view of the
above-mentioned problem, and an object of the present invention is
to eliminate or at least suppress the solder dispersion into the
tubes and especially into the fins in the brazing process, thereby
avoiding the erosion due to the dispersed solder.
[0010] A heat exchanger is composed of a pair of cylindrical header
tanks (a first header tank and a second header tank), plural tubes
connecting the pair of header tanks and plural corrugated fins
disposed between the tubes in heat conductive relation. The heat
exchanger may be used as a condenser for condensing over-heated
refrigerant in an automotive air-conditioning cycle. The
refrigerant supplied to the first header tank is distributed to the
plural tubes and flows into the second header tank. The over-heated
refrigerant is cooled down while flowing through the tubes, and the
condensed refrigerant flows out from the second header tank.
[0011] The tanks are formed by rounding a solder-clad aluminum
plate, so that the solder layer is positioned in the inner surface
of the cylindrical tanks. The solder layer serves as a material for
connecting the tubes and the tanks in brazing. The tubes are drawn
from a bare aluminum material, and the corrugated fins are made of
a thin solder-clad aluminum plate. Flux to promote brazing is
coated on the outer surface of the tubes. Then, all the components
thus made are assembled to form a heat exchanger unit. The
assembled heat exchanger unit is brazed in a furnace filled with
nitrogen gas or inert gas. In the brazing process, the tubes and
tanks are connected to each other by the molten solder layer clad
on the inner surface of the tanks, while the corrugated fins are
connected to the tubes by the molten solder on the surface of the
corrugated fins.
[0012] Since the solder layer is positioned on the inner surface of
the cylindrical header tank, i.e., the aluminum plate forming the
header tank is between the solder layer and the corrugated fin, the
solder molten in the brazing process is prevented from dispersing
into the fin even if the end portion of the fin is positioned close
to the header tank. In addition, unnecessary dispersion of the
molten solder into the tubes is also prevented. Thus, the fin made
of a thin aluminum plate is protected against erosion due to
excessive solder dispersed into the fin.
[0013] Other objects and features of the present invention will
become more readily apparent from a better understanding of the
preferred embodiment described below with reference to the
following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view showing an entire structure of
a condenser;
[0015] FIG. 2 is a partial cross-sectional view showing a portion
connecting a tube to a header tank in the condenser shown in FIG.
1, as an embodiment of the present invention; and
[0016] FIG. 3 is a partial cross-sectional view showing a portion
similar to that of FIG. 3 in a conventional condenser.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] An embodiment of the present invention will be described
with reference to FIGS. 1 and 2. First, referring to FIG. 1, the
entire structure of a condenser 10 which is generally referred to
as a multi-flow-type condenser will be described. The condenser 10
cools down and condenses overheated gaseous refrigerant supplied
from a compressor (not shown) in an automotive air-conditioning
system. The condenser 10 is composed of a condenser core 13
disposed between and connected to a pair of header tanks, a first
header tank 11 and a second header tank 12. The header tanks 11, 12
are made of aluminum and substantially cylinder-shaped.
[0018] The condenser core 13 is composed of tubes 14, corrugated
fins 15, both being alternately laminated, and side plates 19, 20
respectively disposed at the top and the bottom of the condenser
core 13. The condenser core 13 is connected between both header
tanks 11, 12, so that the tubes extend horizontally. The tube 14 is
made by drawing aluminum into a flat shape having plural
refrigerant passages therein. The fin 15 is made by bending a
solder-clad aluminum plate into a corrugated shape. One end of each
tube 14 is inserted into the first header tank 11 and the other end
into the second header tank 12, so that the inner spaces of both
header tanks 11, 12 communicate with each other through the tubes
14. The U-shaped side plate 19 is disposed at the top of the
condenser core 13 and connected to the upper most fin 15, while the
other U-shaped side plate 20 is disposed at the bottom of the
condenser core 13 and connected to the lower most fin 15. Both side
plates 19, 20 serve as condenser frames with which the condenser 10
is mounted on a vehicle body.
[0019] A refrigerant inlet port 16 is provided at an upper portion
of the first header tank 11, while a refrigerant outlet port 17 is
provided at a lower portion of the second header tank 12. The
refrigerant entering the first tank 11 through the inlet port 16,
is distributed to each tube 14, enters the second header tank 12
through the tubes 14 and flows out from the outlet port 17. Both
ends of the first header tank 11 are closed with caps 113, 114,
respectively, and similarly both ends of the second header tanks 12
are closed with caps 123, 124, respectively.
[0020] The structure connecting the tubes 14 to the header tanks
11, 12 will be described in detail with reference to FIG. 2 that
shows a cross-section II-II marked in FIG. 1. Since both header
tanks 11, 12 have the same structure, the structure of the first
header tank 11 will be described below as a representative of both
header tanks 11, 12. Reference numbers shown in parentheses in FIG.
2 denote components or portions of the second header tank 12 that
correspond to those of the first header tank 11.
[0021] The first header tank 11 is composed of a first U-shaped
plate 111 and a second U-shaped plate 112, both being connected to
each other to form a cylindrical inner space that serves as a
refrigerant passage. A pair of caps 113, 114 close both ends of the
inner passage. Plural openings (not shown), the number of which
corresponds to the number of tubes 14, are formed in the first
header tank 11, so that each tube 14 is inserted into the opening
and connected thereto. The first plate 111 which is connected to
the tubes 14 is a solder-clad aluminum plate having a core aluminum
plate 111a and a solder layer 111b clad on the inner surface of the
first plate 111. The second plate 112 is a solder-clad aluminum
plate having a core aluminum plate 112a and solder layers 112b,
112c clad on both surfaces of the second plate 112. Both aluminum
core plates 111a, 112a are made of an aluminum material such as
A-3003, and the solder layers 111b, 112b, 112c are made of a solder
material such as A-4045.
[0022] The tubes 14 made of a bare aluminum material such as A-1050
are manufactured in a drawing process. The fins 15 are made of a
solder-clad aluminum plate having a core plate made of aluminum
such as A-3003 and a solder layer such as A-4045 clad on the core
plate. The caps 113, 114 and side plates 19, 20 are made of bare
aluminum such as A-3003. The refrigerant inlet port 16 and the
refrigerant outlet port 17 are also made of bare aluminum.
[0023] A process of manufacturing the condenser 10 will be
explained below. All the components of the condenser 10 are
manufactured using the solder-clad aluminum material or the bare
aluminum, respectively. Then, flux is coated on the second plate
112 (122), the caps 113, 114 (123, 124), the tubes 14, and the side
plates 19, 20, in a coating process such as immersion coating or
roll coating. Then, the coated flux is dried. As the flux, a
mixture of non-corrosive flux (e.g., fluorides such as a mixture of
KALF.sub.4 and K.sub.2Al.sub.6) and a binder for improving flux
adhesion (e.g., acrylic resin substantially composed of
2-ethylhexyl methacrylate) may be used. Alternatively, silicon (Si)
may be further mixed with the mixture of the flux and the binder to
improve brazing ability.
[0024] Then, the components, including the first header tank 11,
the second header tank 12, tubes 14, fins 15, side plates 19, 20,
and inlet and outlet ports 16, 17, are all assembled to form a
condenser unit 10 shown in FIG. 1. The assembled unit is kept in a
jig to keep its unitary form. The unit kept in the jig is heated in
a brazing furnace filled with nitrogen gas or inert gas up to a
melting point of the solder material. Thus, all the components of
the condenser 10 are connected to one another by brazing, forming a
unitary body of the condenser 10.
[0025] In the brazing process, the first plates 111, 121 and the
tubes 14 are connected to each other by the solder layers 111b,
121b clad on the inside surfaces of the first plates 111, 121 under
the flux coated on the tubes 14. Since the solder layers 111b, 121b
are positioned inside the header tanks 11, 12, i,e., fins 15 are
separated by the core plates 111a, 121a from the solder layers
111b, 121b the solder is prevented from flowing to the fins 15.
Therefore, excessive solder supply to the fins 15 are avoided, and
the end portions of the fins 15 may be positioned closer to the
header tanks 11, 12.
[0026] In a conventional manufacturing process, flux "f" (shown in
FIG. 3) necessary for brazing is coated after its assembling
process by spraying or other methods. Accordingly, the flux is
coated not only on necessary portions but also on other portions,
and thereby a large amount of flux is consumed. On the contrary to
the conventional process, in the process of the present invention,
the flux required for brazing (connections between the first plates
111, 121 and tubes 14, and between the tubes 14 and fins 15) is
supplied from the tubes 14. The flux required is coated on the
tubes 14 before the assembling process. Therefore, the flux is
coated only on the necessary portions and the unnecessary
consumption of the flux is avoided.
[0027] Application of the present invention is not limited to the
condenser described above, but it can be applied to other heat
exchangers such as automotive radiators. Though the solder-clad
aluminum is used for the components requiring brazing in the
foregoing embodiment, a solder material in a paste state may be
coated on aluminum components, or silicon (Si) that promotes
brazing may be coated on the aluminum components. The material of
the components is not limited to aluminum, but the components may
be made of an aluminum alloy. Though the flux required for brazing
the first plates 111, 121 and the tubes 14 is coated on the tubes
14 in the foregoing embodiment, it is possible to additionally coat
the flux on the solder layers 111b, 121b, if necessary.
Alternatively, the flux may be coated only on the solder layers
111b, 121b without coating it on the tubes 14.
[0028] Though the first plates 111, 121 having the solder layers
clad on the inside surfaces thereof are used in the foregoing
embodiment, it is also possible to additionally clad a sacrificial
corrosion layer (e.g., A-7072 or A-3003 including 1 weight-percent
Zn) on the outer surfaces of the first plates 111, 121. Though the
tubes 14 having plural passages therein formed by drawing are used
in the foregoing embodiment, they may be replaced with tubes formed
by presswork.
[0029] While the present invention has been shown and described
with reference to the foregoing preferred embodiment, it will be
apparent to those skilled in the art that changes in form and
detail may be made therein without departing from the scope of the
invention as defined in the appended claims.
* * * * *