Note: Descriptions are shown in the official language in which they were submitted.
1 324602
~is applica~on is a divisional applicati~n of c~ ng application
ial no. 543,185, filed July 28, 1987.
The present invention relates to a condenser for use as
a cooler in automobiles, and more particularly to a condenser
for such use, which i8 made of aluminum. Herein "aluminum"
includes aluminum alloys.
In general heat exchangers, as car coolers use a high
pressure gaseous coolant, and they must have an anti-pressure
construction.
To thi~ end the known heat exchangers are provided with
a core which includes flat tubes arranged in zigzag forms,
each tube having pores, and fins interposed between one tube
and the next. Hereinafter this type of heat exchanges will
be referred to as a serpentine type heat exchanger.
The serpentine type heat exchangers are disadvantageous
in that the coolant undergoes a relatively large resistance
while flowing throughout the tubes. To reduce the resistance
the common practice is to use wider tubes so as to increase
the cross-sectional area thereof. However this leads to a
large core, ar.d on the other hand an accommodation space in
the
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automobile is very much limited. As a result this practice is
not always effective.
Another practice is to placing more fins by reducing the
distances between the tubes. This requires that the helght of
each fin is reduced. However, when the fins are too small the
bending work becomes difficult, and takes more time and labor.
In general the condenser has a coolant path which consists of two
sections, that is, an inlet section, hereinafter referred to as
~condensing section~ in which the coolant is still gaseous, and
an outlet section, hereinafter referred to as "supercooling
sectionH in which it be~omes liquid. In order to increase the
heat exchange efficiency it is essential to increase the area for
effecting heat transfer in the condensing section, whereas it is
no problem for the supercooling section to have a reduced area
lS for heat transfer.
The conventional serpentine type heat exchangers have a coolant
passageway which consists of a single tube. It is impossible for
a single tube to be large in some part, and small in others. If
the tube is to have a wider cross-sectlonal section the tube per
se ~ust be large throughout the entire length; in other words a
large tube must be used. This of course leads to a larger
condenser.
As ls evident from the foregoing description it is difficult to
improve the conventional serpentine type heat exchangers merely
by changlng the dimensional factors thereof.
Basically the serpentlne type heat exchangers involve the
compllcate process which consists of bendlng tubes, and then
assembling them lnto a core in comblnation with fins. Thls is
why it ls difflcult to produce the heat exchangers on automatic
mass production line. Non-automatic production is costly.
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The present invention solves the difficulties pointed out wlth
respect to the conventional serpentine type heat exchangers, and
provides a condenser having a relatively small core whlch
nevertheless includes a lar~e effective cross-sectional area for
coolant passageways, thereby reducing a possible resistance to
the flow of coolant.
The present invention also provides a condenser having coolant
passageways which are divided into a condensing section and a
supercooling section which are different in the numbers of tubes
from each other.
The present invention again provides a condenser having a core
whose construction is adapted for enhancing the heat exchange
efficiency.
p~ t flppl~c~
According to the p~cse*t in40~LLY~ there is provided a condenser
adapted for use in the car cooling system, the condenser
comprising: a pair of headers provided in parallel with each
other; a plurallty of tubular elements whose opposite ends are
connected to the headers, fins provided in air paths present
between one tube and the next; wherein each header is made of an
alumlnum pipe having a circular cross-section; wherein each of
the tubular elements is made of a flat hollow alumin~m tube made
by extrusion; and wherein the opposite ends of the tubular
elements are inserted in sllts produced in the headers, and
llquid-tightly soldered therein; wherein the soldering substance
~5 ls previously coated in the headers or the tubular elements or
both; wherein at least one of the headers is internally divided
by a partition into at least two groups of coolant passageways,
wherein one group is located toward the inlet whereas the other
is located toward the outlet, thereby enabling the flow of
coolant to make at least one U-turn in the header; wherein the
opposite ends of the partition are inserted in a semi-circular
slit produced in the header and soldered therein; and wherein the
partition is disc-shaped, having a larger circular portion and a
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smaller circular portion, the partition i8 inserted in the
header through the slit with the larger circular portion
being secured in the slit and with the smaller circular
portion being kept in contact with the inside wall surface of
the header.
According to the present application there is provided a
condensing apparatus comprising:
a pair of headers provided in parallel with each other;
a plurality of tubular elements whose opposite ends are
connected to the headers; fins provided in air paths present
between one tube and the next; wherein each header is made of
an aluminum pipe having a circular cross-section; wherein
each of the tubular elements is made of a flat hollow
aluminum tube; and wherein the opposite ends of the tubular
elements are inserted in slits produced in the headers, and
liquid-tightly secured therein; wherein at least one of the
headers is internally divided by a partition into at least
two groups of coolant passageways, thereby enabling the flow
of coolant to make at least one Uturn in the header; and
wherein the p~rtition is inserted in the header through a
slit produced in the header and secured therein.
Thus, the present invention adopts a multi-flow pattern
system, whereby the coolant flows through a plurality of
tubular elements at one time. The effective cross-sectional
area for coolant passageways can be increased merely by
increasing the number of tubular elements, thereby reducing
resistance acting on the coolant. This leads to the
reduction in the pressure loss of coolant.
In general, the multi-flow pattern system is difficult to
withstand a high pressure provided by a pressurized gaseous
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coolant because of the relatively fragile joints between the
headers and tubular elements, and the headers per se which
are constructed without presupposing the high pressure which
would act thereon by the coolant. In order to solve this
problem encountered b~ the multi-flow pattern system the
condenser of the present invention uses a cylindrical pipe
for the header, and flat tubes for the tubular elements,
whose opposite ends are inserted in the slits produced in the
headers and soldered therein, thereby ensuring that the
condenser withstands a high pressure provided by the coolant.
Each of the headers is internally divided by a partition into
at least two sections; that is a condensing section and a
supercooling section, wherein the condensing section has a
coolant in its gaseous state whereas the supercooling section
has a coolant in its liquid state. When the coolant is in a
gaseous state its volume i5 large, which requires a
relatively large effective cross-sectional area for the
coolant passageways. When it is in a liquid state the volume
reduces, thereby allowing the coolant passageway to have a
relatively small cross-sectional area.
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According to a preferred embodiment of the present inventlon
there are provided dimensional relationships among the width,
height and pitch of the tubular elements and fins as follows:
Width of the tubular element: 6 to 12 mm; Height of the tubular
element: smm or less; Height of each fin: 8 to 1~ mm; Fln pitch:
1.6 to 3.2 mm.
The tubular elements are ~ointed to the headers; more
specifically, the opposite ends of each tubular element are
inserted into slits produced in the headers so that they fit
therein in a liquid-tight manner and then they are soldered
therein. Prior to the insertion the tubular elements or the
headers or both are provided with a layer of a soldering
substance. All the soldering is effected at one time by placing
the assembled unit in a furnace, thereby saving time and labor in
the assembling work. Suitably the headers are made of an
electrically seamed clad metal pipe having its inner surface
coated with a soldering substance. Desirably the coolant
passageways have effective cross-sectional areas which are
progressively reduced from the inlet side to the outlet side.
Suitably each tubular element is provided with stop means whereby
the tubular element is prevented from being inserted through the
semi-circular slit of the header. Preferably each tubular
element has a body and a head with a shoulder interposed
therebetween, and wherein the stop means is provided by the5 shoulder. Desirably the stop means
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are provided by bulged portions left after the corners of each
tubular element are out. Suitably tubular elements have dlffer-
ent lengths, and are grouped with respect to thelr lengths, and
wherein at least one of the headers is dlvlded lnto two small
headers so as to enable one of the small headers to accept the
shorter tubular elements, thereby forming a space vold of tubular
element.
The present lnvention wlll be further illustrated by
way of the accompanying drawings, in which:-
Fig. 1 is a front view showing a condenser embodyingthe present invention;
Fig. 2 ls a plan view showing the condenser of Fig. l;
Flg. 3 is a perspectiv~ view showing the ~oint between
the header and the lndlvldual tubes;
Fig. 4 is a cross-sectlonal vlew through the line 4-4
in Fig. l;
Fig. 5 is a cross-sectionl view showing the ~oint
between the header and the tube;
Fig. 6 is a cross-sectlonal view of the tube exemplify-
ing a dimensional relationship about it;
Flg. 7 is a cross-sectional view of the fin exemplify-
ing a dimensional relatlonshlp about it;
Fig. 8 is an explanatory view showing a flow pattern of
coolant;
Fig. 9 ls a perspective view showing a modified version
of the ~oint between the tubes and the header;
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Fig. 10 is a cross-sectional view showing the relation-
ship between the tube and the header after they are ~ointed to
each other;
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Fig. 11 is a cross-sectional view showing a modified
version of the stopper produced in the tube;
Fig. 12 is a cross-sectional view showing another
modified veræion of the stopper;
Fig. 13 is a cross-sectional view showing a further
modified version of the stopper;
Fig. 14 is front view showing a modified version of the
condenser;
Fig. 15 is a graph showing the relationship between the
width of the tubes and the rate of air passage therethrough;
Fig. 16 is a graph showing the relationship between the
height of the tubes and the pressure loss of air; and
Fig. 17 is a graph showing variations in the heat
exchange efficiency with respect to the height of the fins
and the pressure loss of air.
As shown in Fig. 1 the condenser 10 of the present
invention includes a plurality of planar tubes 11, and
corrugated fins 12 alternately arranged. The tubes 11 are
connected to headers 13 and 14 at their opposite ends.
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The tube 11 is planar, made o~ aluminum;
preferably, o~ a multi-hollow type.
The-header 13, 14 is made of a cylindrical pipe
of aluminum. It is provided ~ith slits 15 produced at
equal intervals along its length, where the ends of
the tubes 11 are so~dered to the respective headers
13, 14. The le~t-hand header 13 is provided with a
coolant inlet pipe 16 at its upper end and a plug 17
at the lower end. The right-hand header 14 i~
provided with a coolant outlet pipe 18 at its lower
end and a plug 19 at its upper end. The coolant inlet
and outlet are diametrically located. The reference
numerals 23 and 24 denote side plates fixed to the
fins 12 located at the outermost positions..
Each header 13, 14 is provided with a partition
20, 21, respectively, thereby dividing the internal
chamber into upper and lower ~ections, wherein the
partition 20 in the header 13 is located slightly
toward the inlet 16, whereas the partition 21 in the
header 14 i8 located about lf3 the length toward the
outlet 18.
Because of the provision of the partitions 20
and 21 in the headers 13 and 14 the flow pattern o~
the coolant is formed as shown in Fig. 8; that is, the
coolant passageway is grouped into an inlet section
(A), a middle section (B) and an outlet section (C).
As seen from Fig. 8 the coolant flows in three
di~erent directions. In addition, the tubes are
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different in number from group to group; that is, the
group ~B) has more tubes than the group (C) (outlet
section), and the group (A) (inlet section) has more
tubes than the group (B). This means that the group
(A) has a larger effective cross~sectional area for
coolant passageway than the group (B), which in turn
has a greater area for it than the group (C).
Referring to Fig. 8 the coolant introduced into
the core through the inlet pipe 16 flows to the right-
hand header 14 in the inlet section (A), and then in a
reversed direction in the middle section (B). In the
outlet section (C) the flow of coolant is again-
reversed, and led to the right-hand header 14, where
it is discharged through the outlet pipe 18. While
the coolant i.s flowing through the sections (A), (B)
and (C) heat exchange takes place between the coolant
and the air passing through the fins 12. In the inlet
section (A) the coolant is in its gaseous ~tate, but
because of the large effective cross-sectional area in
the section (A) heat e~change proceeds efficiently
between the coolant and the air. In the section (C)
the coolant is in its liquid state, and reduced in its
volume, which allows the section tC) to have a
relatively small cross-sectional area for coolant
passageway as compared with the section (B). In this
way the coolant passes through the fir~t condensing
section (A), the second section (B) and the third
supercooling section (C), in the course of which heat
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~ 3246~
exchange smoothly and efficiently takes place.
In the illustrated embodiment the numbers of tubes are
progressively decreased from the section (A) to the section
(B) and to the section (C). However, it is possible to give
the same number of tubes to the sections (A) and (B), and a
smaller number of tubes to the section (C). Alternatively,
it is possible to arrange so that each section (A) to (C) has
the same number o~ tubes but their cross-sectional areas are
progressively reduced from the section (A) to the section (B)
and to the section (C). As a further modification the
intermediate section (B) can be omitted; in this case the
flow pattern is called a two-path system. In contrast, the
above-mentioned embodiment is called a three-path system. As
a still further modification one or more intermediate
sections can be added.
The illustrated embodiment has the headers located at
the left-hand side and the right-hand side but they can be
located at the upper side and the lower side wherein the
tubes and fins are vertically arranged.
To joint the tubes 11 to the headers 13, 14 the tubes or
the headers or both are previously provided with a layer of a
soldering substance on their ajoining surfaces. More
specifically, as shown in Fig. 3 there is an aluminum pipe
13a, such as a clad metal pipe, which is used as the headers
13 and 14. The clad pipe 13a has a layer of a soldering
B
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substance 13b. The pipe 13a is electrically seamed but can
be made by extrusion or any other known method. For the
soldering substance an Al Si alloy preferably containing 6 to
13% by weight of Si is used. The tubes 11 are inserted in
the slits 15 for their end portions to be held therein. Then
they are heated together to melt the soldering substance. In
this case, as clearly shown in Fig. 5 the ajoining parts of
the tube 11 and the clad pipe 13a have fillets 29, whereby
the header 13, 14 and the tubes 11 are jointed to each other
without gaps interposed therebetween. Likewise, the
corrugated fins 12 can be provided with a layer of a
soldering substance, thereby effecting the soldering joint
between the fins 12 and the tubes 11 simultaneously when the
tubes 11 are jointed to the headers 13, 14. This facilitates
the soldering joint among the headers 13, 14, the tubes 11
and the fins 12, thereby saving labor and time in the
assembling work. The layer of a soldering substance can be
provided in the inner surface of the clad pipe 13a but the
place is not limited to it.
The partitions 20, 21 are jointed to the respective
headers 13, 14 in the following manner:
The clad pipe 13a is previously provided with a semi-
circular slit 28 in its wall, wherein the slit 28 covers half
the circumference of the pipe 13a. The partition 20, 21 is
; 25 made of a disc-shaped plate having a smaller circular portion
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20a and a larger circular portion 20b, wherein the smaller
circular portion 20a has a diameter equal to the inside
diameter of the pipe 13a, and wherein the larger circular
portion 20b has a diameter equal to the outside diameter of
the pipe 13a. The larger diameter portion 20b is inserted
and soldered in the slit 28. The headers 13, 14 and the
partitions 20, 21 are preferably provided with layers of
soldering substances as described above, so that the
soldering joint between them can be performed simultaneously
when the tubes 11 are soldered to the headers 13, 14. This
finishes the soldering joint among the headers, the tubes,
the fins and the partitions at one time. The larger diameter
portion 20b fits in the slit 28 so that no leakage of coolant
is likely to occur, and that the appearance of an outer
surface of the pipe 13a is maintained. In addition, the
larger diameter portion 20b is embedded in the slit 28,
thereby preventing the partition 20, 21 from being displaced
by an unexpected force acting thereon.
; As is generally known in the art, a possible pressure
loss of air largely depends on the relative positional
relationship between the tubes 11 and the fins 12. A reduced
pressure loss leads to the increased heat exchange
efficiency. Accordingly, the heat exchange efficiency
depends on this positional relationship between them. Now,
referring to Figs. 6 and 7 this po6itional relationship will
be described:
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It is prescribed so that the tube 11 has a width (W) of
6 to 12mm, and a height (Ht) of not larger than 5mm, and that
the fin 12 has a height ~Hf) of 8 to 16mm, and a fin pitch
(Fp) of 1.6 to 3.2mm. Referring to Figs. 15, 16 and 17 the
` 5 reasons for the prescriptions are as follows:
As shown in Fig. 15, if the tube 11 has a width of
smaller than 6mm the fin 12 will be accordingly narrower,
thereby reducing the number of louvers 12a. The reduced
number of louvers 12a leads to less efficient heat exchange.
If the tube is wide enough to allow an adequate number of
louvers 12a to be provided on the fins 12, the heat exchange
efficiency will be enhancedO However, if the width (W) of
the tube is more than 12mm, the fins 12 will be accordingly
widened, thereby increasing its weight. In addition too wide
fins and too many louvers are likely to increase resistance
to the air passing therethrough, thereby causing a greater
pressure loss of air.
If the tubes 11 have a height (Ht) of more than 5mm the
pressure loss of air will increase. The inside height (Hp)
of the tube 11 is preferably not smaller than 1.8mm. The
inside height (Hp) is important in that it defines the size
of an effective coolant passageway. If it is smaller than
1.8mm the pressure loss of coolant will increase, thereby
reducing the heat exchange efficiency. In order to maintain
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1 324602
a height (Hp~ of at least 1.8mm for coolant passageway, the
height (Ht) of the tube 11 will have to be at least 2.5mm,
inclusive of the thickness of the tube wall.
As shown in Fig. 17, if the height (Hf) of the fin 12 is
smaller than 8mm the pressure loss of air will increase, but
if it is larger than 16mm the number of fins will have to be
reduced, thereby reducing the heat exchange efficiency.
If the pitch (Fp) of fins 12 is smaller than 1.6mm there
will occur an interference between the adjacent louvers 12a,
thereby amplifying the pressure loss of air. However, if it
exceeds 3.2mm the heat exchange efficiency will decrease.
Referring to Figs. 9 and 10 a modified version will be
described:
This embodiment is characteristic in that it is provided
with shoulders 25 which work as stop means to prevent the
tube from being inserted too deeply into the header 13, 14.
More specifically, the tube 11 includes a body 111 and a head
llla which has shoulders 25 therebetween. The shoulders 25
are adapted to come into abutment with the heater 13, 14 when
the tube 11 is inserted into the slit 15.
As modified versions of the stop means various
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examples are shown in Figs. 11 to 13:
Fig. 11 shows the process o~ ~or~ing stop means
125. In (a) the tube 211 has sharp or aoute corners.
The corners are cut away in such a manner as to form
bulged portions 125, which provide stop means. Pig.
12 shows a tube 311 having round corners, which are
split lengthwise in such a manner as to form shoulders
225. Fig. 13 shows a tube 411 having a relatively
thin wall. In this case the cutting and splitting are
jointly used in such a manner as to for~ shoulders
325.
Fig. 14 shows an example of the condenser
embodying the present invention, characterized in that
the condenser is provided with a space 27 void of any
tube or fin so that an obstacle 26 is avoided when it
is installed in an engine room or somewhere. This
embodiment has a pair of headers 113 and 14, and the
left-hand header 113 is divided into two parts 113a
and 113b. The tubes 11 consist o~ longer tubes lla
and shorter tubes llb, which are connected to the
header 113b at their left-hand ends. The other ends
thereof are connected to the header 14. The outlet
pipe 18 is provided on the header 113b. The coolant
introduced through the inlet pipe 16 ~lows in the
direction of arrows up to the right-hand header 14,
and makes a U-turn to flow through the shorter tubes
llb up to the header 113b, where 1t is let out through
the outlet pipe 18. The number of the space 27 is
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determined in accordance with that o~ an obstacle 26;
when three ~paces are to be given, three kinds o~
lengths of tubes are used.
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