U.S. patent application number 11/714523 was filed with the patent office on 2007-08-23 for heat exchanger device.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Tatsuo Ozaki.
Application Number | 20070193730 11/714523 |
Document ID | / |
Family ID | 36036532 |
Filed Date | 2007-08-23 |
United States Patent
Application |
20070193730 |
Kind Code |
A1 |
Ozaki; Tatsuo |
August 23, 2007 |
Heat exchanger device
Abstract
The heat transfer performance of a heat exchanger situated on
the downstream side of airflow is improved by utilizing a turbulent
flow in a heat exchanger situated on the upstream side of airflow.
At least on fins 12 of a heat exchanger 10 on the upstream side of
airflow among a plurality of heat exchanger devices 10, 20 arranged
in series in the airflow direction, collision walls 12c cut and
raised in an upright position as a turbulent flow forming means for
stirring airflow are provided.
Inventors: |
Ozaki; Tatsuo;
(Okazaki-City, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO CORPORATION
1-1, Showa-cho
Kariya-city
JP
448-8661
|
Family ID: |
36036532 |
Appl. No.: |
11/714523 |
Filed: |
March 6, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/JP05/16864 |
Sep 7, 2005 |
|
|
|
11714523 |
Mar 6, 2007 |
|
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Current U.S.
Class: |
165/140 ;
165/152 |
Current CPC
Class: |
B60K 11/08 20130101;
F28F 1/128 20130101; F28D 1/0435 20130101; B60H 1/00321
20130101 |
Class at
Publication: |
165/140 ;
165/152 |
International
Class: |
F28D 1/02 20060101
F28D001/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 8, 2004 |
JP |
2004-260740 |
Claims
1. A heat exchanger device in which a plurality of heat exchangers
are arranged in series in an airflow direction, wherein: the
plurality of heat exchangers comprise tubes through which fluids
flow, respectively, and fins provided on an outer surface of the
tubes for increasing heat exchanging area with air flowing around
the tubes; and the fins of the heat exchanger on an upstream side
of airflow among the plurality of heat exchangers are provided with
turbulent flow forming means for stirring the airflow.
2. The heat exchanger device as set forth in claim 1, wherein the
fins of the heat exchanger on a downstream side of the airflow
among the plurality of heat exchangers are also provided with
turbulent flow forming means for stirring the airflow.
3. The heat exchanger device as set forth in claim 1, wherein a
distance between the plurality of heat exchangers is equal to or
less than 20 mm.
4. The heat exchanger device as set forth in claim 1, wherein: the
fins have right-angled collision walls formed by cutting and
raising in an upright position a portion of flat-shaped plate
parts; the right-angled collision walls are provided in a plural
number symmetrically in the airflow direction; and the right-angled
collision walls constitute the turbulent flow forming means.
5. The heat exchanger device as set forth in claim 1, wherein: the
fins have V-shaped collision walls formed by cutting and raising
into a V-shaped section a portion of the flat-shaped plate parts;
the V-shaped collision walls are provided such that a direction of
formation of the V-shaped section is reversed by turns in the
airflow direction; and the V-shaped collision walls constitute the
turbulent flow forming means.
6. The heat exchanger device as set forth in claim 1, wherein the
heat exchanger on the upstream side of the airflow among the
plurality of the heat exchangers is a refrigerant heat dissipater
for vehicle air conditioning and the heat exchanger on a downstream
side of the airflow is a radiator for cooling vehicle engine.
Description
CROSS REFERENCE TO ANY RELATED APPLICATIONS
[0001] This is continuation of PCT Application No.
PCT/JP2005/016864, filed on Sep. 7, 2005. This application takes
priority from Japanese patent Application No. 2004-260740 filed on
Sep. 8, 2004.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a heat exchanger device in
which a plurality of heat exchangers are arranged in series in the
airflow direction, suitable as a heat exchanger device in which a
refrigerant heat dissipater for vehicle air conditioning and a
radiator for cooling vehicle engine are arranged in series.
[0004] 2. Description of the Related Art
[0005] An attempt is made to improve the heat transfer rate of fins
of a conventional heat exchanger by providing slit pieces
constituting segments arranged in a staggered form with respect to
an airflow and by providing a bent part by bending the upstream
side of an airflow of the slit piece through about 90 degrees to
stir the airflow and restrict the growth of a temperature boundary
layer (for example, refer to patent document 1).
[0006] [Patent document 1] Japanese Unexamined Patent Publication
(Kokai) No. 63-83591
[0007] By the way, in the invention described in patent document 1,
the slit piece is formed by cutting and raising a portion of the
thin plate-shaped fin and the bent part is formed by bending the
front end (front edge) side of the cut and raised slit piece
through about 90 degrees, and therefore, there are problems with
manufacture as described below.
[0008] In other words, in the invention described in patent
document 1, all of the bent parts are formed by bending the front
end side of the slit piece and Continuation of PCT/JP2005/016864
English Translation of Int. Application therefore the bending
forces in the same direction act on the thin plate-shaped fin
material successively and when the bent part is formed, the fin
material deforms in one direction in an unbalanced manner.
[0009] In addition, it is necessary to provide the slit pieces
regularly at fixed pitch dimensions, however, as described above,
in the invention described in patent document 1, the fin material
tends to collect in one direction, and therefore, it is difficult
to reduce the variation in the pitch dimension between the slit
pieces. Then, if the variation in the pitch dimension between the
slit pieces becomes greater, the possibility is high that the heat
transfer rate is reduced and a desired heat exchange performance
cannot be obtained.
[0010] In order to solve the above-mentioned problem, the inventors
of the present invention have proposed a heat exchanger with an
improved heat exchange performance, and with a simple fin shape, in
the patent application of Japanese Patent Application No.
2004-62236.
[0011] In this earlier application, a fin for increasing the heat
exchange area with air flowing around a tube is provided on the
outer surface of the tube through which fluid flows and the fin is
provided with a flat-shaped plate part and a collision wall formed
by cutting and raising in an upright position a portion of the
plate part and the collision walls are provided in a plural number
symmetrically in the airflow direction.
[0012] Accordingly, when the collision walls are formed the bending
forces in the directions in which the force on the upstream side
and that on the downstream side of airflow cancel out each other
act upon a thin plate-shaped fin material. Consequently, when the
collision walls are formed, it is possible to prevent in advance
the fin material from deforming in one direction in an unbalanced
manner and therefore it is possible to keep the variation in the
dimension of the collision walls small.
[0013] As a result, it is possible to improve productivity (to
increase the production speed) of the fins with a simple shape
while improving the heat exchange efficiency by increasing the heat
transfer rate between the fin and air by utilizing the turbulent
flow effect by the collision walls.
[0014] By the way, the above-mentioned earlier application relates
to the improvement of the heat transfer performance in a single
heat exchanger.
SUMMARY OF THE INVENTION
[0015] Accordingly, an object of the present invention is to
improve, in a heat exchanger device in which a plurality of heat
exchangers are arranged in series in the airflow direction, the
heat transfer performance of a heat exchanger situated on the
downstream side of airflow by utilizing a turbulent flow forming
structure of a heat exchanger situated on the upstream side of
airflow.
[0016] In order to attain the above-mentioned object, a first
aspect of the present invention is a heat exchanger device in which
a plurality of heat exchangers (10, 20) are arranged in series in
the airflow direction, characterized in that the plurality of heat
exchangers (10, 20) comprise tubes (11, 12) through which fluids
flow, respectively, and fins (12, 22) provided on an outer surface
of the tubes (11, 21) for increasing heat exchanging area with air
flowing around the tubes (11, 21), and the fins (12) of the heat
exchanger (10) on an upstream side of airflow among the plurality
of heat exchangers (10, 20) are provided with turbulent flow
forming means (12c, 12g) for stirring the airflow.
[0017] According to this, a turbulent flow is formed by stirring
airflow at the fins (12) of the heat exchanger (10) on the upstream
side of airflow, and therefore, it is possible to improve the heat
exchange performance of the heat exchanger (10) on the upstream
side of airflow by improving the heat transfer rate thereof. In
addition, by making the influence of the turbulent flow formation
on the upstream side of airflow exert also on the heat exchanger
(20) on the downstream side of airflow, it is possible to realize
the improvement of the heat exchange performance of the heat
exchanger (20) on the downstream side of airflow by the turbulent
flow formation also therein.
[0018] In a second aspect of the present invention according to the
heat exchanger device of the first aspect, the fins (22) of the
heat exchanger (20) on a downstream side of the airflow among the
plurality of the heat exchangers (10, 20) are also provided with
turbulent flow forming means (22c, 22g) for stirring the
airflow.
[0019] According to this, in addition to the effect of the first
aspect, the turbulent flow forming action of the heat exchanger
(20) on the downstream side of airflow itself is added in the fins
(22) thereof and, therefore, it is possible to further improve the
heat exchange performance of the heat exchanger (20) on the
downstream side of airflow.
[0020] In a third aspect of the present invention according to the
heat exchanger device of the first or second aspect, a distance (L)
between the plurality of the heat exchangers (10, 20) is equal to
or less than 20 mm.
[0021] According to an experiment by the inventors of the present
invention, it has been found that by setting the distance (L) to 20
mm or less as illustrated in FIG. 7 to be described later, it is
possible to effectively improve the heat exchange performance of
the heat exchanger (20) on the downstream side of airflow by
effectively making the influence of the turbulent flow formation on
the upstream side of airflow exert on the heat exchanger (20) on
the downstream side of airflow.
[0022] In a fourth embodiment of the present invention according to
any one of the heat exchanger devices of the first to third
aspects, the fins (12, 22) have right-angled collision walls (12c,
22c) formed by cutting and raising in an upright position a portion
of flat-shaped plate parts (12a, 22a), the right-angled collision
walls (12c, 22c) are provided in a plural number symmetrically in
the airflow direction, and the right-angled collision walls (12c,
22c) constitute the turbulent flow forming means.
[0023] In this manner, the turbulent flow forming means is
specifically constructed by the collision walls formed by cutting
and raising in an upright position the fin plate part.
[0024] Here, by providing the right-angled collision walls (12c,
22c) in a plural number symmetrically in the airflow direction, the
bending forces in the directions in which the force on the upstream
side and that on the downstream side of airflow cancel out each
other act upon the thin plate-shaped fin material when the
right-angled collision walls are formed. Consequently, when the
collision walls are formed, it is possible to prevent in advance
the fin material from deforming in one direction in an unbalanced
manner and, therefore, it is possible to keep small the variation
in the dimension of the collision walls.
[0025] In a fifth aspect of the present invention according to any
one of the heat exchanger devices of the first to third aspects,
the fins (12, 22) have V-shaped collision walls (12g, 22g) formed
by cutting and raising into a V-shaped section a portion of the
flat-shaped plate parts (12a, 22a), the V-shaped collision walls
(12g, 22g) are provided such that the direction of the formation of
the V-shaped section is reversed by turns in the airflow direction,
and the V-shaped collision walls (12g, 22g) constitute the
turbulent flow forming means.
[0026] In this manner, it may also be possible to construct the
turbulent flow forming means specifically by the V-shaped collision
walls formed by cutting and raising into the V-shaped section the
fin flat part.
[0027] Then, by providing the V-shaped collision walls such that
the direction of the formation of the V-shaped section is reversed
by turns in the airflow direction, the bending stresses at the time
of the cutting and raising formation of the fin material are
cancelled out and it is possible to avoid a residual stress from
occurring in one particular direction in the fin.
[0028] Consequently, when the V-shaped collision walls (12g, 22g)
are formed, it is possible to prevent in advance the fin material
from deforming in one direction in an unbalanced manner and,
therefore, it is possible to keep the variation in the dimension of
the V-shaped collision walls (12g, 22g) small.
[0029] In a sixth aspect of the present invention according to any
one of the heat exchanger devices of the first to fifth aspects,
the heat exchanger on the upstream side of the airflow among the
plurality of the heat exchangers (10, 20) is a refrigerant heat
dissipater for vehicle air conditioning (10) and the heat exchanger
on a downstream side of the airflow is a radiator for cooling
vehicle engine (20).
[0030] According to this, it is possible to effectively improve the
heat exchange performance (heat dissipation performance) of the
radiator (20) on the downstream side of airflow by the turbulent
flow formation of airflow in the refrigerant heat dissipater (10)
on the upstream side of airflow.
[0031] By the way, the symbols in the parentheses attached to each
means described above indicate a correspondence with a specific
means in the embodiments to be described later.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1A is a schematic sectional view showing a state in
which a heat exchanger device according to a first embodiment of
the present invention is mounted on a vehicle.
[0033] FIG. 1B is a partial section of a core part of the heat
exchanger device in FIG. 1A.
[0034] FIG. 2 is a front view of a heat exchanger according to the
first embodiment.
[0035] FIG. 3A is a partial perspective view of a core part of the
heat exchanger according to the first embodiment of the present
invention.
[0036] FIG. 3B is a sectional view taken along A-A line in FIG.
3A.
[0037] FIG. 4 is a sectional view showing another embodiment of
collision walls of fins according to the first embodiment.
[0038] FIG. 5 is an enlarged sectional view of the fin part for
explaining the definition of a cutting and raising height H and a
pitch dimension P of an L-shaped section part.
[0039] FIG. 6 is an explanatory diagram of airflow in various heat
exchanger devices in which a refrigerant heat dissipater and a
radiator are arranged in series.
[0040] FIG. 7 is a graph of the heat dissipation performance ratio
of a radiator.
[0041] FIG. 8 is a graph of a total airflow resistance ratio of the
refrigerant heat dissipater and the radiator.
[0042] FIG. 9A is a partial perspective view of a core part of a
heat exchanger according to a third embodiment of the present
invention.
[0043] FIG. 9B is a sectional view taken along B-B line in FIG.
9A.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
First Embodiment
[0044] FIG. 1A to FIG. 5 and FIG. 6(a) show a first embodiment of
the present invention and the present embodiment relates to a heat
exchanger device for a vehicle in which a refrigerant heat
dissipater for vehicle air conditioning and a radiator for cooling
vehicle engine are arranged in series.
[0045] FIG. 1A is a diagram showing the heat exchanger device for a
vehicle according to the present embodiment which is mounted on a
vehicle, and FIG. 1B is a partial sectional view of a core part of
the heat exchanger device for a vehicle. A refrigerant heat
dissipater for vehicle air conditioning 10 and a radiator for
cooling vehicle engine 20 are arranged in series with respect to a
direction "a" of airflow (cooling air).
[0046] The mounting structure of the heat exchanger is explained
specifically. There is formed an engine compartment 31 below a
vehicle hood (bonnet) 30 and grill openings 32a and 32b are open in
the most front part in the engine compartment 31. The refrigerant
heat dissipater 10 and the radiator 20 are arranged in series at
the portion immediately after the grill openings 32a and 32b. Here,
the refrigerant heat dissipater 10 is arranged on the upstream side
of airflow and the radiator 20 is arranged on the downstream side
(on the rear side of the vehicle) of the refrigerant heat
dissipater 10.
[0047] On the downstream side of the radiator 20, a cooling fan 22
composed of axial fans is arranged via a shroud 21. This cooling
fan 22 is an electrically driven fan that rotates and drives an
axial fan by an electric motor 22a.
[0048] On the downstream side (on the rear side of the vehicle) of
the cooling fan 22, an engine (internal combustion engine) 33 for
vehicle traveling is mounted. This vehicle engine 33 is of a
water-cooled type and the cooling water of the vehicle engine 33 is
cooled by being circulated through the radiator 20 by a water pump,
not shown.
[0049] In addition, the refrigerant heat dissipater 10 is connected
to the compressor discharge side of a vehicle air conditioning
refrigeration cycle, not shown, and cools the refrigerant by
dissipating the heat of the compressor discharge refrigerant (high
pressure side refrigerant) to airflow. In a refrigeration cycle
using a normal CFC (freon).TM. refrigerant, the refrigerant
discharge pressure of the compressor is less than the critical
pressure of the refrigerant and therefore the refrigerant
dissipates heat while condensing in the refrigerant heat dissipater
10. In contrast to this, in a refrigeration cycle using a
refrigerant such as carbon dioxide (CO2) etc., the refrigerant
discharge pressure of the compressor becomes equal to or greater
than the critical pressure of the refrigerant and therefore the
refrigerant dissipates heat in a supercritical state without
condensing in the refrigerant heat dissipater 10.
[0050] The reason that the radiator 20 is arranged on the
downstream side of the refrigerant heat dissipater 10 is to
preserve temperature differences from air both in the refrigerant
heat dissipater 10 and in the radiator 20. In other words, in the
constant operation state of the vehicle engine 33, the temperature
of the engine cooling water in the radiator 20 becomes higher than
the refrigerant temperature in the refrigerant heat dissipater 10
and, therefore, it is advantageous to arrange the radiator 20 on
the downstream side of the refrigerant heat dissipater 10 in order
to preserve the temperature differences from air both in the
refrigerant heat dissipater 10 and in the radiator 20.
[0051] FIG. 2 illustrates a specific configuration of the
refrigerant heat dissipater 10, wherein a plurality of tubes 11
through which refrigerant flows are arranged in parallel with
predetermined spacing and fins 12 are provided between the
plurality of the tubes 11. This fin 12 is joined to the outer
surface of the tube 11 to promote heat exchange between refrigerant
and air by increasing the heat transfer area with air.
[0052] On both the ends in the lengthwise direction of the tube 11,
header tanks 13 and 14 are provided. The header tanks 13 and 14
extend in the direction perpendicular to the lengthwise direction
of the tube 11 and are communicated with the refrigerant path in
each tube 11. Then, on both the ends in the lamination direction of
tubes and fins (in the vertical direction in FIG. 2) of a core part
composed of the tubes 11, the fins 12, etc., side plates 15 and 16
constituting a reinforced member are arranged.
[0053] By the way, in the present embodiment, all of the tube 11,
the fin 12, the header tanks 13 and 14 and the side plates 15 and
16 are formed from aluminum alloy, which is excellent in thermal
conductivity, and these metal members 11 to 16 are joined together
into one unit by brazing.
[0054] As shown in FIG. 1B and FIG. 3A or FIG. 3B, the tube 11 of
the refrigerant heat dissipater 10 is a flat-shaped porous tube
formed by extrusion work or drawing work, in which a plurality of
refrigerant path holes 11a are formed in parallel. The flat shape
of the tube 11 is in parallel to the airflow direction "a".
[0055] In addition, as shown in FIG. 3A or FIG. 3B, the fin 12 is a
corrugated fin formed by being bent into a wavy shape so as to have
a bent part 12b that is curved so as to connect a flat-shaped plate
part 12a and its neighboring plate part 12a. In the present
embodiment, the wavy corrugated fin 12 is formed by applying a
roller forming method to a thin plate metal material. The bent part
12b of the fin 12 comes into contact with and is brazed to the
flat-shaped part (plane part) of the tube 11 as shown in FIG. 3A or
FIG. 3B.
[0056] Then, on the plate part 12a of the fin 12, a plurality of
collision walls 12c having a shape into which a portion of the
plate part 12a is cut and raised in an upright position are
provided. Here, cutting and raising in an upright position
specifically means to cut and raise a portion of the plate part 12a
so as to be right angles with respect to the surface of the plate
part 12a, however, the cut and raised angle of the collision wall
12c may be near 90 degrees, which are increased or decreased by a
minute angle from 90 degrees.
[0057] Air flowing along the fin 12, that is, the surface of the
plate part 12a is caused to collide with the collision walls 12 to
stir the airflow along the surface of the plate part 12a,
increasing the heat transfer rate between the fin 12 and the
air.
[0058] Here, the plate part connected to the root part of the
collision wall 12c among the plate part 12a of the fin 12 is
referred to as a slit piece 12d. The slit piece 12d and the
collision wall 12c form an L-shaped section. Then, the L-shaped
sections are arranged so as to be in a symmetrical relationship
with respect to a virtual plane M perpendicular to the plate part
12a between the upstream side of airflow and the downstream side of
airflow.
[0059] Specifically, when the plate part 12a is bisected into the
upstream side and the downstream side in the airflow direction by
the virtual plane M, the number of collision walls 12c on the
upstream side is equal to the number of collision walls 12c on the
downstream side, and on the upstream side of airflow, the
downstream side of airflow of the slit piece 12s is cut and raised
in an upright position, while on the downstream side of airflow,
the upstream side of airflow of the slit piece 12d is cut and
raised in an upright position.
[0060] By the way, the basic configuration of the refrigerant heat
dissipater for vehicle air conditioning 10 may be the same as that
of the radiator for cooling vehicle engine 20 and, therefore,
symbols of the constituent members of the radiator for cooling
vehicle engine 20 are written in the parentheses attached to the
symbols of the corresponding members of the refrigerant heat
dissipater 10 in FIG. 2, FIG. 3A, and FIG. 3B, and the specific
explanation of the radiator for cooling vehicle engine 20 is
omitted.
[0061] However, the pressure of the engine cooling water
circulating through the radiator for cooling vehicle engine 20 is
much lower than the refrigerant pressure in the refrigerant heat
dissipater for vehicle air conditioning 10 and, therefore, it is
not necessary to increase the pressure resistant strength of the
tube 21 of the radiator 20 as is required for the tube 11 of the
refrigerant heat dissipater 10. Because of this, the tube 21 of the
radiator 20 has a simple flat-shaped section forming only one
cooling water path as shown in FIG. 1B.
[0062] In the present embodiment, also on the fins 22 of the
radiator 20 situated on the downstream side of airflow, collision
walls 22c and slit pieces 22d are formed that constitute L-shaped
sections similarly to the fin 12 of the refrigerant heat dissipater
10 as shown in FIG. 3A or FIG. 3B.
[0063] By the way, the L-shaped sections formed by the slit pieces
12d and the collision walls 12c are not limited to the shape shown
in FIG. 3A and FIG. 3B and in contrast to this, as shown in FIG. 4,
it may also be possible to form the collision walls 12c and 22c on
the upstream side of airflow of the slit pieces 12d and 22d in the
upstream side region of airflow of the fins 12 and 22 and on the
other hand, to form the collision walls 12c and 22c on the
downstream side of airflow of the slit pieces 12d and 22d in the
downstream side region of airflow.
[0064] What is required is to symmetrically arrange the collision
walls 12c and 22d in the upstream side region of airflow of the
fins 12 and 22 and the collision walls 12c and 22c in the
downstream side region of airflow.
[0065] Next, specific examples of the dimensions of the fins 12 and
12 are explained. The fins 12 and 22 are, as described above,
corrugated fins formed by connecting the neighboring plate parts
12a and 22a by the bent parts 12b and 22b and by being bent into a
wavy shape, and the fin pitch Pf of the corrugated fins 12 and 22
is twice the distance between the neighboring plate parts 12a and
22a, as shown in FIG. 3B, and the fin pitch Pf is, for example, 2.5
mm.
[0066] A plate thickness t (refer to FIG. 5) of the corrugated fins
12 and 22 is, for example, 0.05 mm, a height H (refer to FIG. 5) of
the collision walls 12c and 22c is, for example, 0.3 mm, and a
pitch P of the L-shaped section part is, for example, 0.5 mm.
[0067] In addition, a distance L (refer to FIG. 1B and FIG. 6)
between the two heat exchangers 10 and 20 before and after in the
airflow direction is preferably set to a short distance equal to or
less than 20 mm and more specifically, it is preferable that the
distance L=about 5 mm.
[0068] Next, the function and effect of the present embodiment are
explained. FIG. 6(a) shows the airflow in the refrigerant heat
dissipater 10 situated on the upstream side of airflow and the
airflow in the radiator 20 situated on the downstream side of
airflow in the present embodiment. By the way, the arranging
configuration of the collision walls 12c and 22c and the slit
pieces 12d and 22d on the fins 12 and 22 in FIG. 6(a) is the same
as that in FIG. 4.
[0069] In the upstream side region of airflow in the refrigerant
heat dissipater 10, as the collision wall 12c has minute
dimensions, the air that has entered passes through while
maintaining an approximately laminar flow state, however, as the
airflow approaches the downstream side, the stirring effect of the
airflow by the collision wall 12c increases in magnitude gradually.
Because of this, in the downstream side region of airflow of the
refrigerant heat dissipater 10, the airflow enters a turbulent flow
state as shown in FIG. 6(a) and the heat transfer rate on the air
side can be improved.
[0070] Here, since the distance L between the two heat exchangers
10 and 20 before and after in the airflow direction is set to a
short distance equal to or less than 20 mm, it is possible to form
a turbulent flow state of airflow also in the upstream side region
of the radiator 20 by exerting the influence of the turbulent flow
state in the downstream side region of airflow of the refrigerant
heat dissipater 10 on the upstream side region of airflow of the
radiator 20. An a part in FIG. 6(a) shows an influenced range of
the turbulent flow state in the refrigerant heat dissipater 10.
[0071] From the above, it is possible to form the turbulent flow
state both in the upstream side region and in the downstream side
region of airflow in the fin 22 on the radiator 20 side, and
therefore, it is possible to effectively improve the heat
dissipation performance on the radiator 20 side.
[0072] In the present embodiment, the collision walls 12c and 22c
on the upstream side and the collision walls 12c and 22c on the
downstream side are provided so as to be symmetric with each other
in the airflow direction, and therefore, the bending forces, the
directions of which are set to cancel each other, act on the thin
plate-shaped fin material at the time of the fin formation
process.
[0073] Consequently, it is possible to prevent in advance the fin
material from deforming in one direction in an unbalanced manner
when the collision walls 12c and 22c are formed and to keep small
the variation in the dimensions of the slit pieces 12d and 22d and
the collision walls 12c and 22c.
[0074] As a result, it is possible to improve the productivity of
the fins 12 and 22 with a simple shape while improving the heat
exchange efficiency by increasing the heat transfer rate between
air and the fins 12 and 22 using the turbulent flow effect by the
collision walls 12c and 22c.
Second Embodiment
[0075] FIG. 6(b) shows a second embodiment, wherein the
configuration of the fin 12 of the refrigerant heat dissipater 10
situated on the upstream side of airflow is the same as that of the
first embodiment and the configuration of the fin 22, in opposition
thereto, of the radiator 20 situated on the downstream side of
airflow is the same as that of the prior art shown in FIG.
6(c).
[0076] In other words, on the fin 22 of the radiator 20 in the
second embodiment, the collision wall 22c as in the first
embodiment is not formed but a slant louver 22f is formed, which is
formed by cutting and raising in a slant position through
predetermined angles as in the prior art shown in FIG. 6(c). The
cutting and raising direction of the slant louvers 22f on the
upstream side of the airflow is opposite to that on the downstream
side of the airflow.
[0077] According to the second embodiment, the fin 22 itself of the
radiator 20 does not comprise a forming means, however, it is
possible to exert the influence of the turbulent flow state in the
downstream side region of airflow of the refrigerant heat
dissipater 10 also on the upstream side region of airflow of the
radiator 20. As a result, it is possible to form a turbulent flow
state of airflow also in the upstream side region of the radiator
20 as shown in the .alpha. part of FIG. 6(b).
[0078] Due to this, it is possible to improve the heat transfer
rate by the formation of turbulent airflow also on the radiator
side 20, and therefore, it is possible to improve the heat
dissipation performance on the radiator side 20.
[0079] By the way, the prior art shown in FIG. 6(c) is a typical
one, that has been commercialized, in which the slant louvers 12f
and 22f formed by cutting and raising in a slant position through
predetermined angles are formed both on the fin 12 of the
refrigerant heat dissipater 10 and on the fin 22 of the radiator
20. In this prior art, air passes through between the louvers 12f
(22f) in a laminar flow state, and therefore, it is not possible to
improve the heat dissipation performance by the formation of
turbulent flow by the collision walls 12c and 22c as in the first
and second embodiments.
[0080] In addition, FIG. 6(d) shows a comparative example of the
present invention, in which the collision wall 22c is cut and
raised in an upright position only on the fin 22 of the radiator 20
on the leeward side (downstream side in an airflow direction). In
this comparative example, it is not possible to form the turbulent
flow state of airflow in the fin 12 of the refrigerant heat
dissipater 10 on the windward side (upstream side in an airflow
direction), and therefore, it is not possible to improve the heat
dissipation performance of the radiator 20 on the leeward side by
utilizing the turbulent flow state of airflow in the refrigerant
heat dissipater 10 on the windward side.
[0081] Next, the effect of the first embodiment is specifically
explained based on the experiment result shown in FIG. 7 and FIG.
8. As the condition of the experiment shown in FIG. 7 and FIG. 8,
the dimension example of each part of the fins 12 and 22 in the
first embodiment is the same as the above-described dimensions. In
other words, the fin plate thickness t=0.05 mm, the fin pitch
Pf=2.5 mm, the height of the collision walls 12c and 22c H=0.3 mm,
and the pitch P of the L-shaped section part=0.5 mm.
[0082] Then, it is assumed that the air temperature at the inlet is
25.degree. C. (room temperature), the cooling water temperature at
the inlet of the radiator 20 is 80.degree. C., the flow velocity of
the cooling air is 4 m/s, and the flow rate of cooling water for
circulating to the radiator 20 is 40 L/min, and a state is set in
which there is no heat dissipation by the refrigerant heat
dissipater 10 on the windward side, and then, the heat dissipation
performance (KW) of the radiator 20 according to the first
embodiment and the heat dissipation performance (KW) of the
radiator 20 according to the prior art shown in FIG. 6(c) are
measured and the ratio (%) of the heat dissipation performance of
the radiator 20 according to the first embodiment with respect to
the heat dissipation performance of the radiator 20 according to
the prior art, which is assumed to be 100%, is shown in FIG. 7.
[0083] By the way, it is needless to say that the body of the core
part of the radiator 20 according to the first embodiment and that
of the radiator 20 according to the prior art are set to the same
dimensions.
[0084] With the radiator 20 according to the first embodiment, if
the distance L is reduced to about 20 mm, it is possible to improve
the heat dissipation performance to about 102% compared to the
prior art.
[0085] Then, it has been confirmed that if the distance L is
reduced to about 5 mm, it is possible to improve the heat
dissipation performance of the radiator 20 to about 104% compared
to the prior art.
[0086] Next, FIG. 8 shows the influence of the airflow resistance
according to the first embodiment. The total airflow resistance
(Pa) of the refrigerant heat dissipater 10 and the radiator 20
according to the first embodiment and the total airflow resistance
(Pa) of the refrigerant heat dissipater 10 and the radiator 20
according to the prior art are measured and the ratio (%) of the
total airflow resistance according to the first embodiment with
respect to the total airflow resistance according to the prior art,
which is assumed to be 100%, is shown in FIG. 8.
[0087] According to the first embodiment, if the distance L is
reduced to 20 mm or less, the airflow resistance increases because
a turbulent flow is formed in the airflow in the radiator 20 on the
leeward side by the formation of a turbulent flow in the airflow in
the refrigerant heat dissipater 10 on the windward side, however,
the degree of the increase is very small compared to the prior art
and therefore there is almost no practical problem.
[0088] By the way, although the heat dissipation performance ratio
in the case of the second embodiment is not shown schematically in
FIG. 7, the fin 22 of the radiator 20 does not comprise the
turbulent flow forming means in the second embodiment, and
therefore, the rate of improvement in the heat dissipation
performance of the radiator 20 becomes smaller than the first
embodiment, however, according to the experiment by the inventors
of the present invention, it has been confirmed that it is possible
to improve the heat dissipation performance of the radiator 20 to
about 102% compared to that of the prior art also in the second
embodiment if the distance L is reduced to about 5 mm.
[0089] By the way, according to an experiment by the inventors of
the present invention, as the dimension range of the fins 12 and 22
having the right-angled collision walls 12c and 22c are preferably
that the fin plate thickness t=0.01 to 0.1 mm, the height H of the
collision walls 12c and 22c=0.1 to 0.5 mm, the pitch P of the
L-shaped section part is in the range between about 1.5 times to
five times of the height H from the standpoint of the improvement
in heat exchanger performance, the fin formability, the fin
strength, etc.
Third Embodiment
[0090] In the first embodiment, as the turbulent flow forming means
in the refrigerant heat dissipater 10 and the radiator 20, the
collision walls 12c and 22c are formed in an upright position from
the plate parts 12a and 22a of the fins 12 and 22 and in the second
embodiment, as the turbulent flow forming means in the refrigerant
heat dissipater 10, the collision wall (collision part) 12c is
formed in an upright position from the plate part 12a of the fin
12, however, in a third embodiment, as the turbulent flow forming
means, collision walls having a V-shaped section are formed on the
fins 12 and 22.
[0091] In other words, FIG. 9A and FIG. 9B show a configuration of
fins 12, 22 according to the third embodiment, in which V-shaped
collision walls 12g (22g) the V-shaped sectional part of which
extends in the direction perpendicular to the airflow direction a
are formed on the plate parts 12a and 22a of the fins 12 and 22.
The V-shaped collision wall 12g (22g), which forms a turbulent flow
by the collision and stirring of airflow, can be formed by the
cutting and raising formation by a roller forming machine etc.
[0092] The geometry of the V-shaped collision wall 12g (22g) is
stated specifically below. The V-shaped collision walls 12g (22g)
are formed so that the direction of the formation of the V-shaped
section is reversed vertically by turns in the airflow direction
Here, the top part of the V-shaped section is situated near the
plate parts 12a and 22a and the fork end parts of the V-shaped
section are situated on the side departing from the plate parts 12a
and 22a.
[0093] Such V-shaped collision walls 12g (22g) are arranged in a
staggered manner with respect to the plate parts 12a, 22a (in other
words, the fin material surface S before the cutting and raising
formation) so as to sandwich the plate parts 12a, 22a.
[0094] According to the third embodiment, the airflow collides with
the V-shaped collision walls 12g (22g) and is stirred, and then a
turbulent flow of airflow is formed and, therefore, it is possible
to improve the heat transfer rate of the fins 12 and 22 by the
formation of the turbulent flow.
[0095] Then, by forming the V-shaped collision walls 12g on the fin
12 of the refrigerant heat dissipater 10 on the windward side and
by forming a turbulent flow of airflow in the downstream region of
the fin 12, it is possible to form a turbulent flow of airflow in
the upstream region of the fin 22 of the radiator 20 on the leeward
side. Due to this, it is possible to effectively improve the heat
dissipation performance of the radiator 20 on the leeward side also
in the third embodiment as in the first and second embodiments.
[0096] In addition, also in the third embodiment, as shown in FIG.
9B, the V-shaped collision walls 12g and 22g on the upstream part
and those on the downstream part are formed symmetrically with each
other with respect to the virtual plane M in the airflow direction
"a". Then, the direction of the formation of the V-shaped section
is reversed vertically by turns in the airflow direction "a" and,
therefore, the bending forces produced at the time of the
cutting-and raising formation of the fin material are cancelled out
and the residual stress in the specific one direction can be
prevented from remaining in the fin.
[0097] Consequently, when the V-shaped collision walls 12g and 22g
are formed, it is possible to prevent in advance the fin material
from deforming to one side and, therefore, it is possible to keep
small the variation in the dimension of the V-shaped collision
walls 12g and 22g.
[0098] In addition, the individual sections themselves of the
V-shaped collision walls 12g and 22g are symmetric in the V-shape,
and therefore, the number of V-shaped collision walls 12g and 22g
may be odd or even.
Other Embodiments
[0099] In the embodiments described above, the heat exchanger
device for vehicle in which the refrigerant heat dissipater 10 and
the radiator 10 are arranged in series is explained, however, the
present invention can be applied widely to various purposes, not
limited to those for vehicle, provided the heat exchanger device is
one in which a plurality of heat exchangers are arranged in series
in the airflow direction.
* * * * *