U.S. patent application number 11/645283 was filed with the patent office on 2007-06-28 for heat exchanger.
This patent application is currently assigned to DENSO Corporation. Invention is credited to Masaki Harada, Sumio Susa, Haruhiko Watanabe.
Application Number | 20070144720 11/645283 |
Document ID | / |
Family ID | 38192261 |
Filed Date | 2007-06-28 |
United States Patent
Application |
20070144720 |
Kind Code |
A1 |
Harada; Masaki ; et
al. |
June 28, 2007 |
Heat exchanger
Abstract
A heat exchanger (20) includes a plurality of tubes (23) with a
fluid flowing therein and header tanks (21) arranged at the
longitudinal ends of the tubes (23) and comunicating with the
plurality of the tubes (23). The header tanks (21) each include a
core plate (27) coupled with the tubes (23) and a tank body (31)
coupled to straight portions (29) holding the joints of the core
plate (27) with the tubes (23) and forming an internal space of the
tank together with the core plate (27). The cross section of the
each header tank (21) configured of the core plate (27) and the
tank body (31) is in the shape of an ellipse or a polygon similar
to an ellipse, and the aspect ratio of the ellipse inscribed in the
cross section of the header tank (21) is between 0.95 and 1.05
inclusive. Thus, the header tanks of the heat exchanger have a
strength capable of sufficiently resisting an increased supercharge
pressure.
Inventors: |
Harada; Masaki;
(Kariya-city, JP) ; Susa; Sumio; (Anjo-city,
JP) ; Watanabe; Haruhiko; (Yokkaichi-city,
JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO Corporation
Kariya-city
JP
|
Family ID: |
38192261 |
Appl. No.: |
11/645283 |
Filed: |
December 22, 2006 |
Current U.S.
Class: |
165/173 |
Current CPC
Class: |
F28F 9/0224 20130101;
F28F 2220/00 20130101; F28F 2275/06 20130101; F28F 2225/08
20130101; F28F 2275/04 20130101 |
Class at
Publication: |
165/173 |
International
Class: |
F28F 9/02 20060101
F28F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2005 |
JP |
2005-372709 |
Nov 9, 2006 |
JP |
2006-303840 |
Claims
1. A heat exchanger comprising: a plurality of tubes, a fluid flows
therein; and a pair of header tanks arranged at the longitudinal
ends of the tubes and communicating with the plurality of the
tubes, the header tanks each including: a core plate having both
ends portion between which the plurality of tubes are connected
with the core plate, and a tank body coupled to the end portions of
the core plate, thereby forming an internal space of the tank
together with the core plate; and wherein an outside portion of a
cross section of the header tank substantially perpendicular to a
longitudinal direction of each header tank which extends from one
to the other of joints where the tube is connected with the core
plate including the cross section of the tank body is in the shape
of an ellipse, or a polygon similar to an ellipse, and wherein the
aspect ratio of the ellipse inscribed in the outside portion is
between 0.95 and 1.05 inclusive.
2. A heat exchanger according to claim 1, wherein joints between
the core plate and the tank body are formed with a straight
portion, constituting a joint margin.
3. A heat exchanger according to claim 1, wherein the header tank
has end openings coupled with a cap.
4. A heat exchanger comprising: a plurality of tubes a fluid flows
therein; and a pair of header tanks arranged at the longitudinal
ends of the tubes and communicating with the plurality of the
tubes, the header tanks each including: a core plate having both
ends portion between which the plurality of tubes are connected
with the core plate, and a tank body coupled to the end portions of
the core plate, thereby forming an internal space of the tank
together with the core plate; and wherein a cross section of the
header tank substantiality perpendicular to a longitudinal
direction of the header tank is in the shape of an ellipse or a
polygon similar to an ellipse, and wherein the aspect ratio of the
ellipse inscribed in the header tank is between 0.95 and 1.05
inclusive.
5. A heat exchanger according to claim 4, wherein joints between
the core plate and the tank body are formed with a straight portion
constituting a joint margin.
6. A heat exchanger according to claim 4, wherein the header tank
has an openings coupled with a cap.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to a heat exchanger having a pair of
header tanks capable of having a sufficient strength so as to
withstand even a high-pressure medium.
[0003] 2. Description of the Related Art
[0004] The restriction of the exhaust gas emitted from large trucks
is increasing more and more every year. At the same time, the
supercharge pressure and temperature of the intercooler of large
trucks have increased remarkably as shown in FIG. 9. As a heat
exchanger of this intercooler, a vertically long header tank 11
having a rectangular cross section shown in FIG. 10 is
conventionally known. With the increase in supercharge pressure,
however, this header tank 11 is deformed in an increased amount and
may break under an excessively large load imposed on the root of
the tubes. An example of this header tank is described in Japanese
Unexamined Patent Publication No. 9-196594.
SUMMARY OF THE INVENTION
[0005] The object of this invention is to solve the problem
described above and provide a heat exchanger having a header tank
capable of sufficiently resisting an increased supercharge
pressure.
[0006] In order to solve the aforementioned problem, according to a
first aspect of the invention, there is provided a heat exchanger
employing a means wherein an outside portion of a cross section of
the header tank substantially perpendicular to a longitudinal
direction thereof which extends from one joint to the other where
the tube is connected with the core plate including the cross
section of a tank body is in the shape an ellipse or a polygon
similar to an ellipse, and wherein the aspect ratio of an ellipse
inscribed in the outside portion is between 0.95 and 1.05
inclusive. With this heat exchanger, the stress concentration at
the joints between the core plate and the tube can be prevented on
the one hand, and the sectional shape of the portion reinforced in
strength by the tubes is not required to be limited on the other
hand, thereby improving the design freedom.
[0007] Also, in order to solve the aforementioned problem,
according to another aspect of the invention, there is provided a
heat exchanger wherein the cross section of the header tank
substantially perpendicular to a longitudinal direction of the
header tank is in the shape of an ellipse or a polygon similar to
an ellipse, and the aspect ratio of an ellipse inscribed in the
header tank is between 0.93 and 1.05 inclusive.
[0008] In this heat exchanger, a header tank is provided in which
stress concentration at the joint between the core plate and the
tubes can be prevented, and therefore which has sufficient strength
to resist an increased supercharge pressure.
[0009] In order to solve the aforementioned problem, according to
still another aspect of the invention, there is provided a heat
exchanger wherein straight portions each making up a joint margin
are formed at the joint between the core plate and the tank body.
Therefore, a more reliable header tank is provided in which the
joint area between the core plate and the tank body can be
positively secured.
[0010] In order to solve the aforementioned problem, according to
yet another aspect of the invention, there is provided a heat
exchanger wherein a cap is coupled to the openings at the ends of
the cylindrical header tank. When the core plate and the tank body
are coupled to each other, therefore, a jig can be inserted from
the openings and pressure can be applied from both inside and
outside the header tank, thereby making possible a positive
coupling.
[0011] The reference numeral inserted in parentheses following the
name of each means described above indicates an example of
correspondence with a specific means described in the embodiments
below.
[0012] The present invention may be more fully understood from the
description of preferred embodiments of the invention, as set forth
below, together with the accompanying drawings.
[0013] BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a front view schematically showing a heat
exchanger according to an embodiment of the invention.
[0015] FIG. 2 is a sectional view taken along line A-A in FIG.
1.
[0016] FIG. 3 is a diagram showing the relation between the aspect
ratio of the inscribed ellipse of the header tank and the stress
exerted on the tube root.
[0017] FIG. 4A is a sectional view showing a header tank including
a tank body having a semicircular cross section and a core plate
having a cross section equivalent to one half of an octagon,
wherein the straight portions of the tank body are located outside
the straight portions, respectively, of the core plate.
[0018] FIG. 4B is a sectional view showing a header tank including
a tank body having a semicircular cross section and a core plate
having a cross section equivalent to one half of an octagon,
wherein the straight portions of the tank body are located inside
the straight portions, respectively, of the core plate.
[0019] FIG. 4C is a sectional view showing a header tank including
a tank body having a semicircular cross section and a core plate
having a cross section equivalent to one half of an octagon,
wherein the straight portions of both the tank body and the core
plate are extended radially outward.
[0020] FIG. 5 is a sectional view of a header tank having an
octagonal cross section.
[0021] FIG. 6 is a sectional view showing the shape or a header
tank on the side nearer to the tube than the tube root.
[0022] FIG. 7 is a perspective view showing a header tank having,
at each end thereof, an opening covered with a cap.
[0023] FIG. 8A is a perspective view showing a header tank having a
pseudo-circular outer peripheral portion and an outer peripheral
portion larger in aspect ratio.
[0024] FIG. 8B is a sectional view showing a pseudo-circular outer
peripheral portion of a header tank also having an peripheral
portion larger in aspect ratio.
[0025] FIG. 8C is a sectional view showing an outer peripheral
portion larger in aspect ratio or a header tank also having a
pseudo-circular peripheral portion.
[0026] FIG. 9 is a diagram showing recent increases in supercharge
pressure and temperature of the intercooler for large trucks.
[0027] FIG. 10 is a sectional view showing a vertically long
rectangular conventional header tank.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0028] Embodiments of the invention are explained below with
reference to FIGS. 1 to 8C.
[0029] FIGS. 1 to 6 are diagrams showing a first embodiment of the
invention. In FIG. 1, reference numeral 20 designates a heat
exchanger. Heat exchanger 20 includes a plurality of tubes 23 with
a pair of header tanks 21 juxtaposed at the ends thereof.
[0030] The header tanks 21, made of copper, iron or stainless steel
high in strength at high temperatures and capable of being
processed as a thin metal sheet, each have a core plate 27 coupled
with each tube 23 at tube root 25 as shown in FIG. 2. Each core
plate 27 has a substantially semicircular cross section, and is
formed with a straight portion 29 at each end thereof as a brazing
or welding margin. The core plate 27 is also provided with a Tank
body 31 having a substantially semicircular cross section. Tank
body 31 also has straight portions 33 as joints with the core plate
27. The core plate 27 and the tank body are assembled with the
straight portions 29, 33 coupled by brazing and welding,
respectively. The header tanks 21 thus assembled are formed in such
a manner that the cross section thereof is in contact with an
ellipse.
[0031] The ellipse 35 inscribed in the cross section of each header
tank 21 is explained in more detail. The inscribed ellipse 35 is
assumed to be in contact with an ordinary cross section of the
header tank not connected with a pipe or a bracket.
[0032] Assume that the intersection between the center line E along
the center line of the tube 23 of the header tanks 21 and the inner
wall surface of the tank body 31 is designated as A, the
intersection between the center line E and the core plate 27 as B
and the middle point of the line segment AB as 0. Also, assume that
the intersections between the center line F passing through the
point 0 in the direction perpendicular to the center line E and the
inner wall surface of the header tank 21 as C, D, respectively.
Then, the ellipse having the center at point 0 and one of the line
segment AB=a and the line segment CD=b as a long axis and the other
as a short axis constitutes an inscribed ellipse 35.
[0033] The ratio a/b between the long, and short axes of the
inscribed ellipse 35 is preferably between 0.95 and 1.05 inclusive.
The reason for this is shown by way of the graph of FIG. 3. The
abscissa represents the aspect ratio a/b of the inscribed ellipse,
and the ordinate represents the maximum stress exerted on the tube
root, assuming that the aspect ratio is 100 when the aspect ratio
a/b=1. As can be understood from this graph, the maximum stress
exerted on the tube root is increased for an aspect ratio a/b of
not more than 0.95 or not less than 1.05. As a result, the plate
thickness is required to be increased and the machining becomes
difficult, leading to higher costs. Thus, the aspect ratio a/b is
desirably between 0.95 and 1.05 inclusive.
[0034] As stated above, the header tanks 21 or the heat exchanger
described above have a substantially circular cross section with an
aspect ratio a/b of between 0.95 and 1.05 inclusive, and therefore
concentration of stress on the tube root can be prevented. Also, in
view of the fact that the core plate 27 and the tank body 31 are
formed with the straight portions 29, 33, respectively, which are
brazed and welded, sufficient coupling strength is obtained. Even
in a high-pressure medium, therefore, sufficient strength can be
secured without increasing the thickness, thereby suppressing an
increase in weight and cost.
[0035] In the case where the inscribed ellipse 35, with a
substantially circular cross section having the ratio a/b between
the long and short axes thereof, of not less than 0.95 and not more
than 1.05 the thickness of the heat exchanger is increased, which
somewhat disadvantageously requires consideration of the
interference with the radiator when mounted on the vehicle. A
vertically long cross section, however, would require a
considerable increase in thickness in order to maintain the
strength, resulting in an increased weight. Therefore, a
substantially circular cross section can advantageously reduce both
the thickness and the weight, for a lower cost.
[0036] FIGS. 4A to 4C and 5 are diagrams showing other examples of
the first embodiment.
[0037] FIGS. 4A to 4C showing cross sections of a header tank
including a semicircular cross section of the tank body and a half
octagonal cross section of the core plate. The octagonal cross
section has the corners thereof connected at a smooth angle. In the
header tank 41 shown in FIG. 4A, the straight portions 45 of the
tank body 43 are coupled with the outside of the straight portions
49 of the half octagonal core plate 47. In the header tank 51 shown
in FIG. 4E, on the other hand, the straight portions 55 of the tank
body 53 are coupled with the inside of the straight portions 59 of
the half octagonal core plate 37. In the header tank 61 shown in
FIG. 4C, the straight portions 65, 69 of the tank body 63 having a
semicircular cross section and the core plate 67 having a half
octagonal cross section, respectively, extend radially outward, and
the extensions thereof are coupled to each other.
[0038] The header tank 71 shown in FIG. 5 is in the shape of an
octagon including a tank body and a core plate, in which the
straight portions 75 of the tank body 73 are coupled to the inside
of the straight portions 79 of the core plate 77.
[0039] The header tanks shown In FIGS. 4A, 4B, 4C, 5 have a cross
section in the shape of a polygon similar to the ellipse or a
combination of an ellipse and a polygon similar to the ellipse. The
polygon, however, is desirably at least a pentagon. The reason for
this is that in the case where the polygon has less than five
corners, the angle between the tube and the core plate at the tube
root may assume a substantially right angle as shown in FIG. 10,
for increased root stress, depending on the peripheral position of
the polygon with respect to the tube. Also, a number of corners
less than 5 would reduce the inside angle of the corners and
concentrate stress.
[0040] The portion of the header tank having a cross section In the
shape of a polygon similar to an ellipse, therefore, is not
necessarily limited to an octagon as in the embodiments described
above, but may be a pentagon, a hexagon, a nonagon or a
decagon.
[0041] Also, the cross section of the header tank portion nearer to
the tube than the tube root is not necessarily in contact with the
inscribed circle. Specifically, as shown in FIG. 6, the portion of
the header tank 91 nearer to the tube than the tube roots A, B does
not necessarily project into contact with the inscribed ellipse 35
like the core plate 57 of the header tank 51 shown in FIG. 4B, but
the tube roots A and B mats be connected to each other in a region
inside the inscribed circle 35 like the core plate 93 shown in FIG.
6. This is by reason of the fact that the portion between the tube
roots A and B is reinforced by the tube 23 and has sufficient
strength without being in contact with the inscribed circle 35.
[0042] FIG. 7 is a diagram showing a second embodiment of the
invention having a structure in which an opening 81 is formed at
the end of the header tank 51 and covered by a cap 83. By so doing,
the tank body 53 and the core plate 57 can be coupled to each other
by inserting a jig from the opening 81 and closely attaching by
pressing the straight portions 55, 59 against each other from both
inside and outside.
[0043] Generally, aluminum materials can be welded to each other in
spite of a small clearance which may exist between them. On the
other hand, in the case of a clearance at the weld zone of brass or
stainless steel, welding is known to be difficult due to zinc being
present in the structure of the former and due to the oxide film
formed on the surface of the latter.
[0044] In the header tank 51 having the cap 83 according to this
embodiment, the welding zone can be closely attached by inserting a
jig even when welding brass or stainless steel, thereby resulting
in highly reliable welding work.
[0045] FIG. 8A shows a header tank 101 according to a third
embodiment of the invention. Header tank 101 includes a similar
core plate 57 to the one shown in FIG. 4B, and the tank body 103 is
fixedly welded on the core tank 57. The tank body 103 has first
tank outer peripheral portions 153 having a pseudo-circular cross
section (aspect ratio of 1.95 to 1.05) as shown in FIG. 8B, and
second tank outer peripheral portions 105 having a larger aspect
ratio (1.2, for example) than the first tank outer peripheral
portion 153 as shown in FIG. 8C. The first tank outer peripheral
portions 152 and the second tank outer peripheral portions 105
alternate with each other to thereby form the tank body 103.
[0046] In view of the fact that the tank body 103 of the header
tank 101 has the first tank outer peripheral portions 153 having a
pseudo-circular cross section (aspect ratio of 1.95 to 1.05) and
the second tank outer peripheral portions 105 having a larger
aspect ratio (1.2, for example) than the first tank outer
peripheral portions 153, as described above, the rigidity of the
tank as a whole is improved and deformation thereof suppressed,
thereby reducing root stress.
[0047] The shapes of the first tank outer peripheral portions 153
and the second tank outer peripheral portions 105 are applicable to
the common portion other than where a pipe, a mounting bracket,
etc. are arranged. Also, the aspect ratio of the shape of the
second tank outer peripheral portions 10 is not limited to and can
assume any value other than 1.2.
[0048] While the invention has been described by reference to
specific embodiments chosen for 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.
* * * * *