U.S. patent application number 13/990962 was filed with the patent office on 2013-10-10 for latent heat exchanger and water heater.
This patent application is currently assigned to RINNAI CORPORATION. The applicant listed for this patent is Yoichi Kojima, Hidekatsu Naruse, Shinya Otsubo. Invention is credited to Yoichi Kojima, Hidekatsu Naruse, Shinya Otsubo.
Application Number | 20130264037 13/990962 |
Document ID | / |
Family ID | 46382739 |
Filed Date | 2013-10-10 |
United States Patent
Application |
20130264037 |
Kind Code |
A1 |
Otsubo; Shinya ; et
al. |
October 10, 2013 |
LATENT HEAT EXCHANGER AND WATER HEATER
Abstract
A latent heat exchanger (1) has a casing (2), a heat-absorbing
tube (50) accommodated in the casing (2), an inlet header (60), and
an outlet header (70). The casing (2) has a casing main body (10)
and a top plate (40) closing an upper opening (16) of the casing
main body (10). The back wall (11), the front wall (12), the bottom
wall (13), one side wall (14), and the other side wall (15) of the
casing main body (10) are formed integrally by draw-processing a
single metal plate.
Inventors: |
Otsubo; Shinya; (Nagoya-shi,
JP) ; Naruse; Hidekatsu; (Nagoya-shi, JP) ;
Kojima; Yoichi; (Nagoya-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Otsubo; Shinya
Naruse; Hidekatsu
Kojima; Yoichi |
Nagoya-shi
Nagoya-shi
Nagoya-shi |
|
JP
JP
JP |
|
|
Assignee: |
RINNAI CORPORATION
Nagoya-shi, Aichi
JP
|
Family ID: |
46382739 |
Appl. No.: |
13/990962 |
Filed: |
November 18, 2011 |
PCT Filed: |
November 18, 2011 |
PCT NO: |
PCT/JP2011/076689 |
371 Date: |
May 31, 2013 |
Current U.S.
Class: |
165/157 |
Current CPC
Class: |
Y02B 30/00 20130101;
F28F 9/013 20130101; F28D 21/0007 20130101; F28F 2009/0297
20130101; Y02B 30/102 20130101; F28D 7/085 20130101; F28F 9/0224
20130101; F24H 8/006 20130101; F28D 7/0041 20130101; F24H 1/46
20130101; F28F 2275/08 20130101; F28F 9/00 20130101; F28D 7/087
20130101; F24H 1/523 20130101; F24H 8/00 20130101; F24D 19/0092
20130101; F28F 2265/30 20130101; F28F 1/025 20130101; F28F 1/08
20130101; Y02B 30/106 20130101; F28F 2265/26 20130101 |
Class at
Publication: |
165/157 |
International
Class: |
F28F 9/00 20060101
F28F009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2010 |
JP |
2010-290153 |
Dec 27, 2010 |
JP |
2010-290154 |
Dec 27, 2010 |
JP |
2010-290155 |
Claims
1. A latent heat exchanger comprising: a casing having a flow path
of combustion gas therein; a heat absorbing pipe accommodated in
the casing; an inlet header for introducing fluid to be heated into
the heat absorbing pipe; and an outlet header for discharging the
fluid to be heated from the heat absorbing pipe, wherein the casing
has a box-shaped casing body having an upper opening and a top
board closing the upper opening of the casing body, the casing body
has a back wall, a front wall, a bottom wall having a drain
discharging opening, one side wall having an upstream end-inserting
hole through which an upstream end of the heat absorbing pipe is
inserted and a downstream end-inserting hole through which a
downstream end of the heat absorbing pipe is inserted, and the
other side wall, the back wall, the front wall, the bottom wall,
the one side wall, and the other side wall are integrally formed by
drawing one single metal plate, and the inlet header and the outlet
header are respectively disposed outside the one side wall and
connected to the upstream and downstream ends of the heat absorbing
pipe led outside the one side wall through the upstream
end-inserting hole and the downstream end-inserting hole.
2. The latent heat exchanger according to claim 1, wherein the
casing body and the top board are connected by a fastening
process.
3. The latent heat exchanger according to claim 1, wherein the heat
absorbing pipe in the casing has a piping structure in which a
straight portion extending between the one side wall and the other
side wall and circularly arcuate turn-around portions located at
both ends on one side wall side and the other side wall side are
repeated consecutively.
4. The latent heat exchanger according to claim 3, further
comprising a side baffle plate in a plate shape between the
circularly arcuate turn-around portion located on the other side
wall side and an inner surface of the other side wall.
5. The latent heat exchanger according to claim 4, wherein the back
wall has a combustion gas inlet port for introducing the combustion
gas into the casing, the front wall has a combustion gas outlet
port for discharging the combustion gas out of the casing, and the
side baffle plate has inclined faces inclined from ends on an inlet
port side and an outlet port side toward a heat absorbing pipe
side.
6. The latent heat exchanger according to claim 4, wherein an upper
end of the side baffle plate is connected to a lower surface of the
top board, and a lower end of the side baffle plate does not abut
an inner surface of the bottom wall.
7. A water heater having the latent heat exchanger according to
claim 1.
8. The latent heat exchanger according to claim 1, wherein the top
board and the bottom wall respectively have an upper protrusion and
an lower protrusion, protruding inwardly into the casing, and the
upper protrusion abuts the uppermost circularly arcuate turn-around
portion on a top board side and the lower protrusion abuts the
bottommost circularly arcuate turn-around portion on a bottom wall
side.
9. The latent heat exchanger according to claim 5, further
comprising an upper baffle plate inclined downward from a lower
surface of the top board on a front wall side toward an upper edge
of an opening of the gas outlet port.
10. The latent heat exchanger according to claim 3, wherein a
plurality of the heat absorbing pipes are accommodated in the
casing, wherein the circularly arcuate turn-around portions of the
heat absorbing pipes each have a cross section flattened in a
direction that the heat absorbing pipes are stacked one another,
and the heat absorbing pipes are stacked at the flattened
circularly arcuate turn-around portions between the top board and
the bottom wall.
11. A method of manufacturing the latent heat exchanger according
to claim 1, comprising the steps of: inserting the upstream and
downstream ends of the heat absorbing pipe through the upstream
end-inserting hole and the downstream end-inserting hole of the one
side wall respectively; leading the upstream and downstream ends of
the heat absorbing pipe outside the one side wall; applying a
brazing material to boundaries between outer surfaces of the
led-out heat absorbing pipe and the upstream ends-inserting hole
and the downstream ends-inserting hole; inserting the upstream and
the downstream ends of the led-out heat absorbing pipe through
connection holes of header main bodies of the inlet and outlet
headers respectively: applying a brazing material to boundaries
between outer surfaces of the upstream and downstream ends of the
heat absorbing pipe and the connection holes; closing openings of
the header main bodies with header covers respectively; applying a
brazing material to boundaries between inner surfaces of main body
peripheral walls of the header main bodies and outer surfaces of
cover peripheral walls of the header covers; closing the upper
opening of the casing body with the top board to form a subassembly
in which the casing body, the top board, the heat absorbing pipe,
the inlet header, and the outlet header are integrally formed; and
heating the subassembly in a heating furnace.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a latent heat exchanger for
recovering latent heat by condensing water vapor in combustion gas
and a water heater comprising the latent heat exchanger.
BACKGROUND ART
[0002] Conventionally, there has been known a so-called condensing
type water heater having a sensible heat exchanger and a latent
heat exchanger in an apparatus body. In this kind of the water
heater, after sensible heat in combustion gas is absorbed by the
sensible heat exchanger, latent heat in the combustion gas is
absorbed by the latent heat exchanger. As the latent heat
exchanger, there has been proposed one disclosed in, e.g., Patent
Document 1 or Patent Document 2, for miniaturization and higher
heat efficiency. As shown in FIGS. 13 and 15, in such a latent heat
exchanger, a plurality of heat absorbing pipes 820 or a plurality
of heat absorbing pipes 920 each having a pipe structure in which a
straight portion and a circularly arcuate turn-around portion are
repeated consecutively, are arranged in a meandering or spiral
manner, in a casing where combustion gas flows, and in order to
circulate fluid to be heated in the heat absorbing pipes 820 or the
heat absorbing pipes 920, upstream ends and downstream ends of the
heat absorbing pipes 820 or 920 are connected respectively to an
inlet header 830 or 930 and an outlet header 840 or 940 in one side
wall 814 or 914 of the casing.
[0003] When the latent heat in the combustion gas is absorbed by
the latent heat exchanger as described above, strong acidic drain
(condensed water) is generated in the casing by cooling water vapor
in the combustion gas below the dew point temperature and
condensing the water vapor. Thus, in order to prevent corrosion due
to the drain, a member made of anti-corrosive metal such as
stainless steel or titanium has been used as the casing and the
heat absorbing pipe. Further, in order to quickly discharge the
drain from the casing inside, a drain discharge opening is formed
in a lower area of the casing.
[0004] As shown in FIG. 14, in assembling the latent heat exchanger
of the Patent Document 1 described above, an upper casing 812
having upper projecting portions 812a projecting downward
respectively from four corners thereof and a lower casing 813
having lower projecting portions 813a projecting upward
respectively from four corners thereof are welded such that the
upper and lower projecting portions 812a, 813a abut each other,
whereby a tubular casing body 811 having both-side openings is
produced. Subsequently, as shown in FIG. 13, peripheries of the
both-side openings of the casing body 811 are welded respectively
to an one side wall 814 to which the upstream and downstream ends
of the heat absorbing pipes 820 are brazed and the other side wall
815. Similarly, as shown in FIG. 16, a casing of the latent heat
exchanger of the Patent Document 2 is produced by brazing a top
member 915, a pair of side walls 913, 914, and a main body member
911 having a concave cross-section and serving as a front wall
911a, a back wall 911b, and a bottom wall 911c.
[0005] In the latent heat exchanger having the above casing, when
strong acid drain dripped from the heat absorbing pipes during an
operation proceeds to the lower corners of the casing, the drain
easily enters a gap existing in a welded or brazed connection area
between the peripheries of the both-side openings of the casing
body or the main body member and the side walls, which may result
in long-term retention of the strong acid drain in the gap.
Further, when metal plates are connected to each other by welding,
the metal plates are potentially transformed at the welded area. As
such, even if the metal plates inherently excellent in
anti-corrosion are used, the anti-corrosion ability partially is
deteriorated at the welded area. Thus, there is a problem that the
metal plates become easily corroded at both lower sides of the
casing where the drain is likely to be retained. Further, in the
latent heat exchanger manufactured by connecting many metal plates
by welding or brazing, there are problems that a number of members
increase and an assembling work becomes complicated due to increase
of members to be connected.
[Prior Arts]
[0006] [Patent Document 1] JP2009-180398 A [0007] [Patent Document
2] JP2008-292032 A
SUMMARY OF THE INVENTION
[0008] The present invention has been made to solve the problems
described above, and an object of the present invention is to
provide a latent heat exchanger, for which miniaturization and
higher heat efficiency are required, capable of reducing corrosion
due to the drain so as to enhance durability and being produced in
a simple process, and a water heater using the latent heat
exchanger.
[0009] According to one aspect of the present invention, there is
provided a latent heat exchanger comprising:
[0010] a casing having a flow path of combustion gas therein;
[0011] a heat absorbing pipe accommodated in the casing;
[0012] an inlet header for introducing fluid to be heated into the
heat absorbing pipe; and
[0013] an outlet header for discharging the fluid to be heated from
the heat absorbing pipe, wherein
[0014] the casing has a box-shaped casing body having an upper
opening and a top board closing the upper opening of the casing
body,
[0015] the casing body has a back wall, a front wall, a bottom wall
having a drain discharging opening, one side wall having an
upstream end-inserting hole through which an upstream end of the
heat absorbing pipe is inserted and a downstream end-inserting hole
through which a downstream end of the heat absorbing pipe is
inserted, and the other side wall,
[0016] the back wall, the front wall, the bottom wall, the one side
wall, and the other side wall are integrally formed by drawing one
single metal plate, and
[0017] the inlet header and the outlet header are respectively
disposed outside the one side wall and connected to the upstream
and downstream ends of the heat absorbing pipe led outside the one
side wall through the upstream end-inserting hole and the
downstream end-inserting hole.
[0018] According to the present invention, since no connection area
by welding or brazing is formed in a lower area of the casing of
the latent heat exchanger, drain is not likely to be retained in
the lower area of the casing. Therefore, it makes possible to
smoothly discharge the drain from the drain discharge opening
provided at the lower area of the casing. As a result, corrosion of
the metal plates due to the drain can be reduced, whereby it makes
possible to provide the latent heat exchanger and the water heater
excellent in durability. Further, since the casing is formed by
closing the upper opening of the casing body, whose walls are
integrally formed by the drawing, with the top board, it makes
possible to manufacture the latent heat exchanger easily with fewer
members.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic perspective view showing one example
of a latent heat exchanger according to an embodiment 1 of the
present invention;
[0020] FIG. 2 is a schematic exploded perspective view of FIG.
1;
[0021] FIG. 3 is a partial schematic cross-sectional view showing
an internal structure on the other side wall side of the latent
heat exchanger according to the embodiment 1 of the present
invention;
[0022] FIG. 4 is a schematic perspective view showing a side baffle
plate according to the embodiment 1 of the present invention;
[0023] FIG. 5 is a schematic perspective view showing a heat
absorbing pipe according to the embodiment 1 of the present
invention;
[0024] FIG. 6 is a schematic cross-sectional view showing a
circularly arcuate turn-around portion of the heat absorbing pipe
according to the embodiment 1 of the present invention;
[0025] FIG. 7 is a schematic cross-sectional view showing a
straight portion of the heat absorbing pipe according to the
embodiment 1 of the present invention;
[0026] FIG. 8 is a schematic cross-sectional view as taken along
A-A of FIG. 1;
[0027] FIG. 9 is a partial schematic cross-sectional view showing a
connection step for connecting a casing body and a top board by a
fastening process according to the embodiment 1 of the present
invention, wherein FIG. 9A shows a state before connection and FIG.
9B shows a state after connection;
[0028] FIG. 10 is a schematic block diagram showing one example of
a water heater according to the embodiment 1 of the present
invention;
[0029] FIG. 11 is a schematic perspective view showing one example
of a latent heat exchanger according to an embodiment 2 of the
present invention;
[0030] FIG. 12 is a schematic block diagram showing one example of
a water heater according to the embodiment 2 of the present
invention;
[0031] FIG. 13 is a schematic perspective view showing one example
of a conventional latent heat exchanger;
[0032] FIG. 14 is a schematic perspective view showing a casing
body of FIG. 13;
[0033] FIG. 15 is a schematic perspective view showing another
example of a conventional latent heat exchanger; and
[0034] FIG. 16 is a schematic perspective view showing a casing of
FIG. 15.
PREFERRED MODE FOR CARRYING OUT THE INVENTION
Embodiment 1
[0035] Hereinafter, a latent heat exchanger and a water heater
having the latent heat exchanger according to an embodiment of the
present invention will be described in detail.
[0036] FIG. 1 is a schematic perspective view showing one example
of the latent heat exchanger according to the embodiment 1 of the
present invention, and FIG. 2 is a schematic exploded perspective
view of FIG. 1.
[0037] As shown in FIGS. 1 and 2, a casing 2 of the latent heat
exchanger of the embodiment has a box-shaped casing body 10 having
an upper opening 16 and a top board 40 closing the upper opening 16
of the casing body 10. Those casing body 10 and top board 40 are
respectively formed from one thin plate made of a metal having
anti-corrosion such as stainless steel.
[0038] A casing body 10 has a back wall 11, a front wall 12, a
bottom wall 13, one side wall 14, and the other side wall 15. The
casing body 10 is integrally formed in a box shape and has the
upper opening 16, by drawing one single metal plate. More in
detail, the back and front walls 11, 12 rise from front and back
edges of the plate shaped bottom wall 13 extending in a
predetermined direction, and those walls 11 and 12 are integrally
connected to the bottom wall 13 via corners. Also, the one and
other side walls 14, 15 rise from right and left edges of the
bottom wall 13, and those side walls 14, 15 are integrally
connected to the bottom wall 13 via corners. Further, right and
left edges of each of the back and front walls 11, 12 are connected
integrally to the one and other side walls 14, 15, respectively,
via corners. With this configuration, an internal space having the
upper opening 16, that is surrounded by the back wall 11, the front
wall 12, the bottom wall 13, and the both side walls 14, 15, is
formed in the casing body 10. In the present embodiment, a mounting
portion 101 for mounting thereon a top board 40 when the casing
body 10 and the top board 40 are connected to each other by a
fastening process, that is bent the respective walls 11, 12, 14, 15
in the horizontal direction, and an upper flange portion 102 for
fastening the top board 40 therein by the fastening process (to be
described later), that is bent upwardly from the mounting portion
101, are consecutively formed at opening ends of the back wall 11,
the front wall 12, and the both side walls 14, 15.
[0039] Accordingly, when the casing body 10 according to the
embodiment is manufactured, there is no need of welding or brazing.
Further, since no connection area by welding or brazing is formed
at a lower area of the casing 2 having the casing body 10, the
drain is not likely to be retained in the lower area when the drain
is generated. Furthermore, since the back wall 11, the front wall
12, the bottom wall 13, and the one and other side walls 14, 15 are
integrally formed by the drawing, the casing 2 can be easily formed
with fewer members.
[0040] A combustion gas inlet port 111 for introducing the
combustion gas into the casing and a combustion gas outlet port 121
for discharging the combustion gas out of the casing, that are
opened in a laterally long rectangular shape, are respectively
formed at substantially center areas in both up-down and left-right
directions of the back wall 11 and the front wall 12, when a latent
heat exchanger 1 is assembled in an apparatus body of a water
heater. With this configuration, a flow path of the combustion gas
communicating from the combustion gas inlet port 111 to the
combustion gas outlet port 121 is formed inside the casing 2. A
shape and an opened position of the combustion gas inlet port 111
or the combustion gas outlet port 121 can be appropriately set
according to the form of use. For example, according to the form of
the water heater, the combustion gas inlet port 111 may be formed
at the bottom wall 13 or the combustion gas outlet port 121 may be
formed at the top board 40.
[0041] The bottom wall 13 is inclined downward from a back wall 11
side to a front wall 12 side in order to smoothly discharge the
drain out of the casing 2 upon a generation of the drain, and a
drain discharge opening 17 for discharging the drain is opened in
the lowest area of the inclined plane. The drain discharge opening
17 is connected to a neutralizer via a discharge pipe (not shown).
Lower protrusions 131, 131 are formed in the bottom wall 13 by the
drawing so as to protrude inwardly into the casing 2 from both ends
(one side wall 14 side end and the other side wall 15 side end) in
the left-right direction, in a state where the casing body 10 and
the top board 40 are connected to each other. The lower protrusions
131, 131 are respectively formed at a location abutting circularly
arcuate turn-around portions 52 of a bottommost heat absorbing pipe
50.
[0042] A plurality of upstream end-inserting holes 141 through
which upstream ends 53 of the heat absorbing pipes 50 are inserted
and a plurality of downstream end-inserting holes 142 through which
downstream ends 54 of the heat absorbing pipes 50 are inserted are
formed, by burring, in both ends (the back wall 11 side end and the
front wall 12 side end) of the one side wall 14 in the front-back
direction, as many as the heat absorbing pipes 50. In the present
embodiment, the upstream end-inserting holes 141 and the downstream
end-inserting holes 142 are respectively arranged in two rows,
which are staggered with respect to each other. The number and
arrangement of the inserting holes 141, 142 can appropriately be
selected in accordance with the number of the heat absorbing pipes
50. The other side wall 15 is same as the one side wall 14 except
that the upstream end-inserting holes 141 and the downstream
end-inserting holes 142 are not formed.
[0043] The top board 40 has a top board body 41 in a flat plate
shape, a standing strip 42 formed by bending upward an entire
periphery of the top board body 41, and a lower flange portion 43
formed by bending back an entire periphery of the standing strip 42
in a horizontal direction. The top board 40 is formed by drawing
one single metal plate, same as the casing body 10. The standing
strip 42 is sized so as to fit within an inner periphery of the
upper opening 16, which is surrounded by the back wall 11, the
front wall 12, the one and other side walls 14, 15 of the casing
body 10. Further, the lower flange 43 is sized so as to be mounted
on the mounting portion 101. Furthermore, upper protrusions 144,
144 are formed in the top board body 41 by the drawing so as to
protrude inwardly into the casing 2 from both ends (the one side
wall 14 side end and the other side wall 15 side end) in the
left-right direction, in a state where the casing body 10 and the
top board 40 are connected to each other. The upper protrusions
144, 144 are respectively formed at a location abutting circularly
arcuate turn-around portions 52 of an uppermost heat absorbing pipe
50 as described later.
[0044] As shown in FIGS. 3 and 4, an upper end of a side baffle
plate 45 in a flat plate shape is welded to a lower surface of the
top board 40 on the other side wall 15 side. The side baffle plate
45 is arranged in the casing 2 such that a plate portion 451
extends along a flow path direction of the combustion gas in a
state where the casing body 10 and the top board 40 is connected to
each other. That is, the casing body 10 integrally formed by the
drawing is used in the latent heat exchanger 1 according to the
present embodiment, so that it is necessary to lead out the
upstream and downstream ends 53, 54 of the heat absorbing pipes 50
through the one side wall 14 in connecting the upstream and
downstream ends 53, 54 of the heat absorbing pipes 50 respectively
to an inlet header 60 and an outlet header 70 disposed outside the
one side wall 14. Thus, when the upstream and downstream ends 53,
54 of the heat absorbing pipes 50 are inserted through the upstream
end-inserting holes 141 and the downstream end-inserting holes 142,
respectively, there occurs a space having a certain volume between
ends of the circularly arcuate turn-around portions 52 on the other
side wall 15 side and an inner surface of the other side wall 15.
This causes the combustion gas introduced through the combustion
gas inlet port 111 to flow in the space with less gas glow
resistance, which may result in preventing the combustion gas from
efficiently contacting the heat absorbing pipes 50 and reducing in
heat efficiency. However, providing the side baffle plate 45 in the
space between the ends of the circularly arcuate turn-around
portions 52 on the other side wall 15 side and the inner surface of
the other side wall 15 causes the combustion gas to flow toward the
heat absorbing pipes 50 side, making it easy for the combustion gas
to contact the heat absorbing pipes 50, thereby allowing
enhancement of the heat efficiency. In addition, since the upper
end of the side baffle plate 45 is connected to the lower surface
of the top board 40, the casing 2 can be fabricated simply by
closing the upper opening 16 of the casing body 10 with the top
board 40 to which the side baffle plate 45 has been connected.
[0045] Further, as shown in FIG. 4, the side baffle plate 45
according to the present embodiment is formed of a flat plate
portion 451 having, at an upper end thereof, a connection portion
450 for connecting to the lower surface of the top board 40 and
inclined faces 452, 452 respectively inclined in a manner curved,
from ends on a combustion gas inlet port 111 side and a combustion
gas outlet port 121 side toward the heat absorbing pipes 50. With
this configuration, since the combustion gas introduced into the
casing 2 from the combustion gas inlet port 111 flows along the
inclined faces 452, 452 on the combustion gas inlet port 111 side
and the combustion gas outlet port 121 side, it makes easier for
the combustion gas to contact the heat absorbing pipes 50, thereby
allowing further enhancement of the heat efficiency. Alternatively,
the inclined faces 452, 452 may be linearly inclined.
[0046] Further, as shown in FIG. 3, the side baffle plate 45 is
formed such that a lower end thereof does not abut an inner surface
of the bottom wall 13. If the side baffle plate 45 extends to such
an extent that the lower end thereof abuts the bottom wall 13,
vibration of the side baffle plate 45 is transmitted both to the
top board 40 and the bottom wall 13 when the combustion gas passes
inside the casing 2, resulting in easy generation of noise.
However, the side baffle plate 45 only abuts the lower surface of
the top board 40 but not the bottom wall 13, so that such noise can
be prevented. Further, flow of drain is not disturbed, so that it
makes possible to discharge the drain smoothly. Moreover, since no
connection area is formed between the bottom wall 13 and the side
baffle plate 45, there is no need to take care of crevice corrosion
due to the drain.
[0047] Referring back to FIG. 2, an upper baffle plate 46 is
connected to the top board 40, that is inclined downward from the
lower surface of the top board 40 on the front wall 12 side toward
an entire upper edge of the opening of the combustion gas outlet
port 121. With this configuration, the combustion gas introduced
from the combustion gas inlet port 111 is further suppressed from
an upper side to the heat absorbing pipe 50 side, it makes easy for
the combustion gas to contact the heat absorbing pipes 50 and to
smoothly discharge out of the casing 2 from the combustion gas
outlet port 121 along the upper baffle plate 46 on the combustion
gas outlet port 121 side.
[0048] Inside the casing 2, a plurality of (five, in the present
embodiment) heat absorbing pipes 50 through which tap water serving
as fluid to be heated flows are accommodated in a meandering manner
with a gap allowing passage of the combustion gas provided between
one another. The upstream and downstream ends of the heat absorbing
pipes 50 are respectively led outside the one side wall 14 through
the upstream end-inserting hole 141 and the downstream
end-inserting hole 142 formed in the one side wall 14, as described
above.
[0049] FIG. 5 is a schematic perspective view showing one of the
heat absorbing pipes 50. The heat absorbing pipe 50 according to
the present embodiment is formed by bending a plurality of portions
of a corrugate pipe (pipe having an outer shape in which ridge
portions and valley portions continuously alternate in an axial
direction thereof) made of an anti-corrosion metal such as
stainless steel. Further, the heat absorbing pipe 50 has a pipe
structure in which a straight portion 51 and the circularly arcuate
turn-around portion 52 are repeated consecutively and has a wave
shape in which the straight portions 51 and the circularly arcuate
turn-around portions 52 are made to meander in one plane. (In FIGS.
1, 2 and so on, a part of the straight portion 51 is only described
as the corrugate pipe for avoiding complication.) Each of the heat
absorbing pipes 50 is accommodated in the casing 2 such that the
straight portion 51 extends in the left-right direction between the
one and other side walls 14, 15 and the circularly arcuate
turn-around portions 52 are disposed at both ends (the one side
wall 14 side end and the other side wall 15 side end) in the
left-right direction. A plurality of the heat absorbing pipes 50
formed by connecting the straight portion 51 to the circularly
arcuate turn-around portions 52 bent at one direction may be used
and such heat absorbing pipes 50 may be accommodated in a spiral
manner in the casing 2.
[0050] As shown in FIGS. 5 and 6, the circularly arcuate
turn-around portions 52 of the heat absorbing pipes 50 each have a
cross section flattened in a direction that the heat absorbing
pipes 50 are stacked one another. FIG. 6 shows a cut shape of the
valley portion of the heat absorbing pipe 50. On the other hand, as
shown in FIG. 7, the valley portion of the straight portion 51 of
the heat absorbing pipe 50 has a circular cross section.
[0051] As shown in FIGS. 2 and 3, the heat absorbing pipes 50 each
are stacked at the flattened circularly arcuate turn-around
portions 52. With this configuration, a gap between the heat
absorbing pipes 50 adjacent to each other is narrowed in the
stacking direction of the heat absorbing pipes 50, whereby the heat
absorbing pipes 50 are arranged densely. As a result, it makes
possible to downsize the latent heat exchanger 1 and to bring into
contact the combustion gas with the heat absorbing pipes 50
efficiently.
[0052] The heat absorbing pipes 50 stacked one another are
displaced by half-pitch in a wavelength direction of the wave
shape. That is, in FIG. 2, with respect to a second heat absorbing
pipe 50 from the top and a second heat absorbing pipe 50 from the
bottom, their adjacent heat absorbing pipes 50 are provided at
positions displaced by half-pitch in an upstream side of the flow
path of the combustion gas (to the combustion gas inlet port 111
side).
[0053] The flattened circularly arcuate turn-around portions 52 of
the uppermost heat absorbing pipe 50 and the bottommost heat
absorbing pipe 50, which are positioned at the both ends (both ends
on the one side wall 14 side and the other wall 15 side) in the
left-right direction, abut the above-described upper protrusions
144 formed in the top board 40 and the lower protrusions 131 formed
in the bottom wall 13, respectively. With this configuration,
without using other member for fixing the heat absorbing pipes 50,
the heat absorbing pipes 50 can be fixed stably in the casing 2.
Also, vibration of the heat absorbing pipes 50 due to water hammer
phenomenon or the like can be reduced. Further, since other member
for fixing the heat absorbing pipes 50 is not arranged in the flow
path of the combustion gas except for the heat absorbing pipes 50,
it makes possible to bring into contact the combustion gas with the
heat absorbing pipes 50 efficiently.
[0054] As described above, the upstream and downstream ends 53, 54
of the heat absorbing pipes 50 are respectively led outside the
casing 2 through the upstream end-inserting holes 141 and the
downstream end-inserting holes 142 formed in the one side wall 14.
Further, as shown in FIG. 1, the upstream and downstream ends 53,
54 are respectively connected to the inlet header 60 and the outlet
header 70 disposed outside the one side wall 14. As such, the
upstream and downstream ends 53, 54 of the heat absorbing pipes 50
are connected to the inlet and outlet headers 60, 70, respectively
and thus, as a whole, the plurality of heat absorbing pipes 50 are
connected in parallel. This reduces a water-passing resistance as
compared to a case where the heat absorbing pipes 50 are connected
in series.
[0055] The inlet and outlet headers 60, 70 which are respectively
connected to the upstream and downstream ends 53, 54 of the heat
absorbing pipes 50 are arranged outside the one side wall 14 of the
casing body 10. As shown FIGS. 1 to 2 and further FIG. 8 showing a
cross-sectional view as taken along A-A of FIG. 1, the both headers
60, 70 respectively have header main bodies 61, 71 in a dish shape
and header covers 64, 74 in a dish shape to be internally fitted
respectively to the header main bodies 61, 71. The both headers 60,
70 are formed respectively by connecting their members by brazing
such that openings of the header main bodies 61, 71 and those of
the header covers 64, 74 face each other. The outlet header 70
according to the present embodiment has the same configuration as
that of the inlet header 60 except for using the header cover 74
obtained by turning upside down the header cover 64 of the inlet
header 60. Thus, a description will be given mainly of the inlet
header 60 below.
[0056] As seen well in FIG. 8, the header main body 61 has a main
body bottom plate 62 having connection holes 160 to be connected to
the upstream ends 53 of the heat absorbing pipes 50 and a main body
peripheral wall 63 raised from a peripheral end of the main body
bottom plate 62 toward a header cover 64 side and opened toward the
header cover 64 side, in a state where the header main body 61 and
the header cover 64 are fitted to each other. In the embodiment,
the both headers 60, 70 are provided adjacent to the one side wall
14. However, the upstream ends 53 or the downstream ends 54 of the
heat absorbing pipes 50 may be further extended apart from the
casing 2 and the upstream ends 53 or the downstream ends 54 of the
extended heat absorbing pipes 50 may be connected to the inlet
header 60 or the outlet header 70.
[0057] The main body peripheral wall 63 of the header main body 61
is made to extend such that at least a part of a main body open end
630 is positioned higher than an outer peripheral surface of a
cover bottom plate 65 in a cross-sectional direction, in a state
where the header cover 64 is fitted to the header main body 61.
Also, as shown in FIG. 2, the main body peripheral wall 63 of the
header main body 61 is formed into substantially a rectangular
shape having a pair of long sides 63a and a pair of short sides
63b. Further, as shown in FIG. 8, the main body open end 630 of the
long and short sides 63a, 63b is formed so as to wide outwardly.
With this configuration, when the header main body 61 and the
header cover 64 are brazed to each other, a brazing reservoir M is
formed between an inner surface of the main body peripheral wall 63
and an outer surface of a cover peripheral wall 66. As a result, it
makes possible to enlarge a connection area to be brazed between
the inner surface of the main body peripheral wall 63 and the outer
surface of a cover peripheral wall 66. Further, since a brazing
material spreads in the brazing reservoir M, it makes possible to
prevent the brazing material from depositing on unnecessary area
during the brazing process, as compared to a case where the brazing
material is applied only on edge face of the main body open end
630.
[0058] Further, according to the present embodiment, claws 67, 67,
which are bent toward the header cover 64 side after the header
main body 61 and the header cover 64 are fitted to each other, are
respectively formed in the main body open end 630 of the opposing
long sides 63a of the header main body 61. Those claws 67, 67 are
arranged such that they are not overlapped in a short side 63b
direction. Specifically, in the embodiment, since the header main
body 61 and the header cover 64 fitting into the header main body
61 are brazed, it is necessary to press the header cover 64 into
the header main body 61 before the brazing. However, since the
peripheral walls 63, 66 of the header main body 61 and the header
cover 64 have fabrication errors respectively, there is a
possibility that the header cover 64 cants with respect to the
header main body 61 or the header cover 64 removes from the header
main body 61 after pressing-in. From this point of view, the claws
67 to be bent toward the header cover 64 side are formed in the
main body open end 630 of the main body peripheral wall 63. Thus,
after the header cover 64 and the header main body 61 are fitted to
each other, the claws 67 abutting an outer peripheral surface of
the header cover 64 suppress backlash of the header cover 64,
thereby reliably preventing shift of the header cover 64. Further,
forming the claws 67 in the main body open end 630 of the long
sides 63a allows the header cover 64 to be fixed to the header main
body 61 avoiding an inflow port 164 to which a water supply pipe is
connected. The number of the claws 67 may be one, or three or more
in accordance with a size of the header main body 61. In a case
where the main body open end 630 of the main body peripheral wall
63 has the claw 67, the main body open end 630 preferably is
extended such that a part of the main body open end 630 other than
a part in which the claw 67 is formed, is equal to or higher than
the outer peripheral surface of the cover bottom plate 65 in a
cross sectional direction upon fitting the header cover 64 to the
header main body 61.
[0059] The header cover 64 connected to the header main body 61 has
the cover bottom plate 65 and the cover peripheral wall 66 raised
from a peripheral end of the cover bottom plate 65 toward a header
main body 61 side and opened toward the header main body 61 side,
in a state where the header main body 61 and the header cover 64
are fitted to each other. The cover peripheral wall 66 is formed
into a substantially rectangular shape having a pair of long sides
and a pair of short sides, same as the main body peripheral wall 63
of the header main body 61, such that the outer surface of the
cover peripheral wall 66 fits into the inner surface of the main
body peripheral wall 63.
[0060] As shown in FIG. 2, the inflow port 164 and an outflow port
(not shown) are respectively formed near an upper end of the cover
bottom plate 65 and a lower end of the cover bottom plate 75 by
burring. Joint cylinders 68, 78 for connecting respectively to the
water supply pipe and a connection pipe connecting to an upstream
end of a pipe body of a sensible heat exchanger are attached
respectively to the inflow port 164 and the outflow port. With this
configuration, the fluid to be heated flows from the inlet header
60 to the outlet header 70 via the plurality of the heat absorbing
pipes 50 and water vapor in the combustion gas is condensed on
outer surfaces of the heat absorbing pipes 50, resulting in
recovery of the latent heat.
[0061] Next, one example of a manufacturing method of the latent
heat exchanger according to the embodiment will be described in
detail.
[0062] In manufacturing the latent heat exchanger 1, firstly, the
upstream and downstream ends 53, 54 of the heat absorbing pipes 50
are respectively inserted through the upstream end-inserting holes
141 and the downstream end-inserting holes 142 of the one side wall
14 of the casing body 10 formed by the drawing and the upstream and
downstream ends 53, 54 of the heat absorbing pipes 50 are led
outside the one side wall 14 by a predetermined length. Then, the
brazing material (for example, nickel-based brazing paste) is
applied to boundaries between outer surfaces of the led-out heat
absorbing pipes 50 and the upstream ends-inserting holes 141 and
the downstream ends-inserting holes 142. Subsequently, the upstream
and the downstream ends 53, 54 of the led-out heat absorbing pipe
50 are respectively inserted through the connection holes 160, 170
of the header main bodies 61, 71 and the brazing material is
applied to boundaries between the outer surfaces of the upstream
and the downstream ends 53, 54 and the connection holes 160, 170.
The brazing material can be pre-applied at inner surfaces of the
upstream end-inserting holes 141 and the downstream end-inserting
holes 142 of the one side wall 14 and inner surfaces of the
connection holes 160, 170 of the header main bodies 61, 71.
[0063] Alternatively, the joint cylinders 68, 78 are respectively
inserted into the inflow port 164 and the outflow port (not shown)
of the header covers 64, 74 in advance and those are prefixed by
applying brazing material to their boundaries. Then, the header
covers 64, 74 are placed between jig holding portions P, P formed
in the main body peripheral walls 63, 73 of the header main bodies
61, 71 and a pushing jig (not shown) such that the openings of the
header covers 64, 74 and those of the header main bodies 61, 71
face each other, and the header covers 64, 74 are pressed into the
header main bodies 61, 71 by the pushing jig. After pressing-in,
the claws 67, 77 formed in the main body open ends 630, 730 of the
main body peripheral walls 63, 73 are respectively bent toward the
header covers 64, 74 sides and further the brazing material is
applied into the brazing reservoirs M formed between the inner
surfaces of the main body peripheral walls 63, 73 and the outer
surfaces of the cover peripheral walls 66, 76. At this time,
although the claws 67, 77 are respectively bent toward the header
covers 64, 74 sides, the brazing material penetrates into base
portions of the claws 67, 77 by penetrating ability of the brazing
material.
[0064] Next, as shown in FIG. 9A, the top board 40 is disposed on
the casing body 10 such that the lower flange portion 43 of the top
board 40 is mounted on the mounting portion 101 formed at an
peripheral edge of the upper opening 16 of the casing body 10. At
this time, the upper protrusions 144 formed in the top board 40 and
the lower protrusions 131 formed in the bottom wall 13 respectively
abut the circularly arcuate turn-around portions 52 of the
uppermost and bottommost heat absorbing pipes 50. Further, the side
baffle plate 45 formed in the lower surface of the top board 40 on
the other side wall 15 side is inserted into the space formed
between the ends of the circularly arcuate turn-around portions 52
on the other side wall 15 side and the inner surface of the other
side wall 15. Furthermore, the upper baffle plate 46 formed in the
lower surface of the top board 40 on the front wall 12 side is
disposed so as to downward incline from the lower surface of the
top board 40 toward the entire upper edge of the opening of the
combustion gas outlet port 121.
[0065] Then, as shown in FIG. 9B, the fastening process is
performed for bending the upper flange portion 102 of the casing
body 10 against the lower flange portion 43 of the top board 40,
whereby the upper opening 16 of the casing body 10 is closed by the
top board 40. With this, a subassembly in which the heat absorbing
pipes 50, the inlet header 60, and the like are prefixed is
assembled. As described above, in the present embodiment, the walls
11, 12, 13, 14, 15 of the casing body 10 are integrally formed by
drawing the single metal plate, and only the upper opening 16 of
the casing body 10 with less affected by the drain is closed by the
top board 40. Thus, it is possible to produce the casing 2 having
an excellent corrosion resistance without performing welding or
brazing but simply by connecting the casing body 10 and the top
board 40 by the fastening process.
[0066] Finally, the subassembly is placed in a heating furnace and
a brazing process is performed. With this, members are fixed at
portions to which the brazing materials are applied and the latent
heat exchanger 1 is produced. Since the casing body 10 and the
heating absorbing pipes 50 are subject to the heating
(solution-annealed) during the brazing process, residual stresses
in the casing body 10 generated by the drawing process and the
circularly arcuate turn-around portions 52 are removed, so that
even upon contacting with the strong acidic drain, stress-corrosion
cracking can be prevented.
[0067] Next, one example of a water heater according to the present
embodiment will be described in detail.
[0068] FIG. 10 is a schematic block diagram showing the water
heater according to the embodiment 1. A sensible heat exchanger 3
and the latent heat exchanger 1 are located in an apparatus body
(not shown).
[0069] As shown in FIG. 10, the sensible heat exchanger 3 is
arranged below the latent heat exchanger 1. Also, a gas burner 4
for burning gas supplied from a gas supply pipe is arranged below
the sensible heat exchanger 3 and further an air supply fan 5 for
supplying combustion air is arranged below the gas burner 4.
[0070] The sensible heat exchanger 3 comprises a number of fins 332
arranged in parallel and a meandering pipes 331 passing through the
fins 332. The sensible heat exchanger 3 and the latent heat
exchanger 1 are partitioned into upper and lower regions by the
bottom wall 13 of the casing body 10.
[0071] The sensible heat exchanger 3 communicates with the latent
heat exchanger 1 via the combustion gas inlet port 111 described
above. The combustion gas supplied into the latent heat exchanger 1
from the sensible heat exchanger 3 via the combustion gas inlet
port 111 passes through the latent heat exchanger 1 and thereafter
it is discharged out of the apparatus body from the combustion gas
outlet port 121.
[0072] In the water heater of the present embodiment, the
combustion gas is produced by combustion of the gas burner 4 and
the sensible heat exchanger 3 and the latent heat exchanger 1 are
heated by the combustion gas. Then, sensible heat in the combustion
gas is absorbed by the sensible heat exchanger 3 and latent heat in
the combustion gas absorbed the sensible heat is absorbed by the
latent heat exchanger. At this time, water vapor in the combustion
gas is cooled below the dew point temperature, so that the strong
acidic drain is generated and the drain generated in the latent
heat exchanger 1 drips on the bottom wall 13 of the casing body 10.
As described above, however, the latent heat exchanger 1 of the
present embodiment has the casing body 10 whose walls 11, 12, 13,
14, 15 are integrally formed by the drawing, so that no connection
area by welding or brazing is formed in the lower area of the
casing 2. Therefore, the drain is not likely to be retained in the
lower area of the casing 2, whereby it makes possible to discharge
the drain smoothly from the discharge opening 17 to the
neutralizer. As a result, corrosion of the casing 2 due to the
drain can be reduced, whereby the water heater having high
durability can be obtained.
[0073] The joint cylinder 68 of the inlet header 60 is connected to
the water supply pipe for introducing cold water from a water
supply source such as a water pipe and the joint cylinder 78 of the
outlet header 70 is connected to a connection pipe communicating to
an upstream end of pipes 331 of the sensible heat exchanger 3.
Therefore, the cold water supplied from the water supply pipe is
heated to be hot water during passing through the latent heat
exchanger 1 and the sensible heat exchanger 3 and thereafter the
hot water is supplied to a hot-water supplying terminal such as a
bathroom or a kitchen, from a hot-water supply pipe connected to a
downstream end of pipes 331 of the sensible heat exchanger 3.
Embodiment 2
[0074] Although in the above embodiment 1, a latent heat exchanger
used for a water heater having a single heating circuit has been
described, in this embodiment 2, a latent heat exchanger used for a
water heater having two heating circuits will be described. The
same elements as those of the latent heat exchanger and the water
heater in the embodiment 1 are denoted by the same reference
numerals, and a description thereof will be are omitted.
[0075] FIG. 11 is a schematic perspective view from the back
showing a latent heat exchanger according to the present embodiment
2.
[0076] As shown in FIG. 11, a casing of a latent heat exchanger 1a
has a casing body 10 and a top board 40 closing an upper opening of
the casing body 10, same as those of the latent heat exchanger 1 of
the embodiment 1. However, an inside of the casing is partitioned
by a partition wall W into a first region on the one side wall 14
side and a second region on the other side wall 15 side, and first
absorbing pipes 50a and second absorbing pipes 50b are accommodated
respectively in the regions arranged in parallel along the
left-right direction. The structures of the first and second heat
absorbing pipes 50a, 50b are same as those of embodiment 1.
[0077] As for the casing body 10, a back wall 11, a front wall 12,
a bottom wall 13, one side wall 14, and the other side wall 15 are
integrally formed by drawing one single metal plate, same as that
of the embodiment 1. Two combustion gas inlet ports 111a, 111b are
formed in the back wall 11 so as to introduce combustion gas into
the first and second regions respectively. On the other hand, as
shown in FIG. 12, one single combustion gas outlet port 121
communicating with the first and second regions is formed in the
front wall 12. However, two combustion gas outlet ports may be
formed in the front wall 12, same as the back wall 11. Furthermore,
although not shown, first upstream end-inserting holes and first
downstream end-inserting holes through which upstream ends and
downstream ends of the first heat absorbing pipes 50a respectively
inserted are formed in the one side wall 14 and second upstream
end-inserting holes and second downstream end-inserting holes
through which upstream ends and downstream ends of the second heat
absorbing pipes 50b respectively inserted are formed in the other
side wall 15. Lower protrusions 131 abutting circularly arcuate
turn-around portions of the first and second heat absorbing pipes
50a, 50b and a drain discharge opening 17 for discharging the drain
are formed in the bottom wall 13.
[0078] Thus, in the latent heat exchanger 1a of the present
embodiment, the casing body 10 does not have any connection areas
by welding or brazing, so that there is no need of welding or
brazing to assemble the casing body 10. Also, since no connection
area by welding or brazing is formed in the lower area of the
casing, the drain is not likely to be retained in the lower area
when the drain is generated. Further, since the back wall 11, the
front wall 12, the bottom wall 13, the one side wall 14, and the
other side wall 15 are integrally formed by the drawing, the casing
can be easily formed with fewer members. Furthermore, since only
the upper opening of the casing body 10 with less affected by the
drain is closed by the top board 40, it is possible to produce the
casing having an excellent corrosion resistance without performing
welding or brazing but simply by connecting the casing body 10 and
the top board 40 by the fastening process.
[0079] The top board 40 has the same configuration as that of the
top board 40 according to the embodiment 1, and the side baffle
plate 45 is provided only in the first region on the one side wall
14 side. Other side baffle plate may be provided also in the second
region. However, in a case where the partition wall W is provided
after accommodation of the second heat absorbing pipes 50b in the
casing body 10, it is possible to dispose the partition wall W near
ends of the circularly arcuate turn-around portions of the second
heat absorbing pipes 50b. Thus, in the present embodiment, the side
baffle plate 45 can be provided in either the first or the second
region.
[0080] A first inlet header 60a and a first outlet header 70a which
are respectively connected to the upstream and downstream ends of
the first heat absorbing pipes 50a are arranged outside the one
side wall 14 and a second inlet header 60b and a second outlet
header 70b which are respectively connected to the upstream and
downstream ends of the second heat absorbing pipes 50b are arranged
outside the other side wall 15. Those headers respectively have a
header main body and a header cover same as those of the embodiment
1.
[0081] FIG. 12 is a schematic block diagram showing one example of
a water heater having the latent heat exchanger 1a described
above.
[0082] In the water heater, combustion gas produced by a first gas
burner 4a is supplied, by an air supply fan 5a, to a first sensible
heat exchanger 3a where sensible heat is recovered and further
supplied to the first region of the latent heat exchanger 1a where
latent heat is recovered. Similarly, combustion gas produced by a
second gas burner 4b is supplied, by an air supply fan 5a, to a
second sensible heat exchanger 3b where sensible heat is recovered
and further supplied to the second region of the latent heat
exchanger 1a where latent heat is recovered. According to the water
heater, for example, one heating circuit can be used for a hot
water supply circuit and the other heating circuit can be used for
a heating circuit.
Other Embodiments
[0083] (1) In the embodiments above, the top board is fastened to
the casing body by forming the upper flange in the casing body.
Alternatively, a casing body may be fastened to a top board by
forming an upper flange in the top board.
[0084] (2) In the embodiments above, the side baffle plate is
connected to the lower surface of the top board. Alternatively, a
top board and a side baffle plate which are not connected to each
other may be used, and the side baffle plate may be connected to a
bottom wall before a casing body is connected to the top board
after the accommodation of the heat absorbing pipes. In this case,
considering the noise described above, it is preferable that an
upper end of the baffle plate are not extended to abut a lower
surface of the top board.
[0085] As described in detail, the present invention is summarized
as follows.
[0086] According to one aspect of the present invention, there is
provided a latent heat exchanger comprising:
[0087] a casing having a flow path of combustion gas therein;
[0088] a heat absorbing pipe accommodated in the casing;
[0089] an inlet header for introducing fluid to be heated into the
heat absorbing pipe; and
[0090] an outlet header for discharging the fluid to be heated from
the heat absorbing pipe, wherein
[0091] the casing has a box-shaped casing body having an upper
opening and a top board closing the upper opening of the casing
body,
[0092] the casing body has a back wall, a front wall, a bottom wall
having a drain discharging opening, one side wall having an
upstream end-inserting hole through which an upstream end of the
heat absorbing pipe is inserted and a downstream end-inserting hole
through which a downstream end of the heat absorbing pipe is
inserted, and the other side wall,
[0093] the back wall, the front wall, the bottom wall, the one side
wall, and the other side wall are integrally formed by drawing one
single metal plate, and
[0094] the inlet header and the outlet header are respectively
disposed outside the one side wall and connected to the upstream
and downstream ends of the heat absorbing pipe led outside the one
side wall through the upstream end-inserting hole and the
downstream end-inserting hole.
[0095] According to the latent heat exchanger described above,
since the back wall, the front wall, the bottom wall, the one side
wall, and the other side wall of the casing body are integrally
formed by drawing the single metal plate, there is no need of
welding or brazing to assemble the casing body. Also, since no
connection area by welding or brazing is formed in the lower area
of the casing, generated drain is not likely to be retained in the
lower area of the casing. Therefore, it makes possible to smoothly
discharge the drain from the drain discharge opening formed in the
lower area of the casing. Further, since the casing body has the
back wall, the front wall, the bottom wall, the one side wall, and
the other side wall, integrally formed by the drawing, it makes
possible to manufacture the latent heat exchanger easily with fewer
members.
[0096] In the latent heat exchanger described above, the casing
body and the top board may be connected by the fastening
process.
[0097] According to the latent heat exchanger described above,
since the walls of the casing body are integrally formed by drawing
the single metal plate, in the assemble of the casing, only the
upper opening of the casing body with less affected by the drain is
closed by the top board. Thus, it is possible to produce the casing
having an excellent corrosion resistance simply by connecting the
casing body and the top board by the fastening process.
[0098] Preferably, the latent heat exchanger described above has a
heat absorbing pipe in the casing having a piping structure in
which a straight portion extending between the one side wall and
the other side wall and circularly arcuate turn-around portions
located at the both ends on the one side wall side and the other
side wall side are repeated consecutively. More preferably, the
latent heat exchanger having the structure described above further
comprises a side baffle plate in a plate shape between the
circularly arcuate turn-around portion on the other side wall side
and an inner surface of the other side wall.
[0099] Since the heat absorbing pipe is arranged densely in the
casing by use of the heat absorbing pipe having the above
structure, the latent heat exchanger having a small size and higher
heat efficiency can be obtained. Further, the casing body having
the walls integrally formed by the drawing is used in the latent
heat exchanger, so that it is necessary to lead out the upstream
and downstream ends of the heat absorbing pipe from the one side
wall in connecting the heat absorbing pipe to the inlet header and
the outlet header disposed outside the one side wall. Thus, when
the upstream and downstream ends of the heat absorbing pipe are
inserted through the upstream end-inserting hole and the downstream
end-inserting hole, respectively, there occurs a space having a
certain volume between the circularly arcuate turn-around portion
on the other side wall side and an inner surface of the other side
wall. This causes the combustion gas introduced through the
combustion gas inlet port to flow in the space with less gas glow
resistance, which may result in preventing the combustion gas from
efficiently contacting the heat absorbing pipe and reducing in heat
efficiency. On the other hand, providing the side baffle plate in
the space between the circularly arcuate turn-around portion on the
other side wall side and the inner surface of the other side wall
causes the combustion gas to flow toward the heat absorbing pipe
side, making it easy for the combustion gas to contact the heat
absorbing pipe, whereby higher heat efficiency can be obtained.
[0100] In the latent heat exchanger described above, when the back
wall has a combustion gas inlet port for introducing the combustion
gas into the casing and the front wall has a gas combustion outlet
port for discharging the combustion gas out of the casing,
respectively, the side baffle plate may have inclined faces
inclined from ends on an inlet port side and an outlet port side
toward a heat absorbing pipe side.
[0101] According to the latent heat exchanger described above, the
flow path of the combustion gas is formed between the combustion
gas inlet port in the back wall and the combustion gas outlet port
in the front wall. The side baffle plate has the inclined faces
inclined from the ends on the inlet port side and the outlet port
side toward the heat absorbing pipe side, so that the combustion
gas flows along the inclined faces. Therefore, according to the
latent heat exchanger described above, it makes easier for the
combustion gas to contact the heat absorbing pipe, thereby allowing
further enhancement of the heat efficiency.
[0102] Preferably, in the latent heat exchanger described above,
the side baffle plate is formed such that an upper end is connected
to a lower surface of the top board and a lower end does not abut
an inner surface of the bottom wall.
[0103] According to the latent heat exchanger described above, the
casing in which the side baffle plate is positioned at a
predetermined place can be fabricated simply by closing the upper
opening of the casing body with the top board to which the side
baffle plate is connected. Further, if the side baffle plate
extends to such an extent that the lower end thereof abuts the
bottom wall, vibration of the side baffle plate is transmitted both
to the top board and the bottom wall when the combustion gas passes
inside the casing, resulting in easy generation of noise. On the
other hand, the side baffle plate is only connected to the lower
surface of the top board but not the bottom wall, it makes possible
to prevent such noise. Further, flow of drain is not disturbed,
whereby it makes possible to discharge the drain smoothly.
Moreover, since any connection portions are not formed between the
bottom wall and the side baffle plate, there is no need to take
care of crevice corrosion due to the drain.
[0104] According to a preferable aspect of the present invention
whose object is to fix a plurality of the heat absorbing pipes in
the casing stably, the latent heat exchanger described above
comprises,
[0105] a plurality of the heat absorbing pipes accommodated in the
casing, wherein
[0106] the heat absorbing pipes each in the casing have a piping
structure in which a straight portion extending between the one
side wall and the other side wall and circularly arcuate
turn-around portions are repeated consecutively,
[0107] the heat absorbing pipes are stacked at the flattened
circularly arcuate turn-around portions between the top board and
the bottom wall,
[0108] the circularly arcuate turn-around portions of the heat
absorbing pipes each have a cross section flattened in a direction
that the heat absorbing pipes are stacked one another, and
[0109] the top board and the bottom wall respectively have an upper
protrusion and an lower protrusion, protruding inwardly into the
casing, wherein
[0110] the upper protrusion abuts the uppermost circularly arcuate
turn-around portions on a top board side and the lower protrusion
abuts the bottommost circularly arcuate turn-around portions on a
bottom wall side.
[0111] According to the latent heat exchanger described above,
since the circularly arcuate turn-around portions each of the heat
absorbing pipes stacked between the top board and the bottom wall
have a flattened cross section, the heat absorbing pipes can be
arranged more densely than the heat absorbing pipes having a
circular cross section, whereby it makes possible to reduce a
height in a direction that the heat absorbing pipes are stacked one
another. Further, since the density of the arranged heat absorbing
pipes becomes higher, an amount of ineffective combustion gas which
is discharged out of the casing without contact relative to the
heat absorbing pipes becomes less, whereby higher thermal
efficiency can be obtained. On the other hand, in a case where the
heat absorbing pipes are stacked between the top board and the
bottom wall, vibration and deformation of the heat absorbing pipes
are likely to be occurred. However, according to the latent heat
exchanger above, the top board and the bottom wall respectively
have the upper and lower protrusions which protrude inwardly into
the casing and those upper and lower protrusions abut the flattened
circularly arcuate turn-around portions of the heat absorbing
pipes, so that the heat absorbing pipes can be fixed stably without
using other fixing member. Moreover, since the casing can be
produced by closing the upper opening of the casing body integrally
formed by the back wall, the front wall, the one side wall, and the
other side wall, with the top board, the heat absorbing pipes can
be fixed upon closing the upper opening with the top board, without
using other fixing member. Therefore, high productivity can be
obtained.
[0112] Preferably, in the latent heat exchanger having the
plurality of the heat absorbing pipes,
[0113] the heat absorbing pipes each in the casing have a piping
structure in which a straight portion extending between the one
side wall and the other side wall and the circularly arcuate
turn-around portions located at both ends on the one side wall side
and the other side wall side are repeated consecutively,
[0114] the top board has upper protrusions located at the both ends
on the one side wall side and the other side wall side,
[0115] the upper protrusions at the both ends respectively abut the
uppermost circularly arcuate turn-around portions located at the
both ends,
[0116] the bottom wall has lower protrusions located at the both
ends on the one side wall side and the other side wall side,
and
[0117] the lower protrusions at the both ends respectively abut the
bottommost circularly arcuate turn-around portions located at the
both ends.
[0118] According to the latent heat exchanger described above, the
flattened circularly arcuate turn-around portions of the heat
absorbing pipes are formed at the both ends on the one and other
side wall sides and the upper and lower protrusions formed in the
top board and the bottom wall respectively abut the uppermost and
bottommost circularly arcuate turn-around portions at the both
ends, so that the heat absorbing pipes can be fixed more stably in
the casing.
[0119] According to another preferable aspect of the present
invention whose object is to prevent water leak from the header, in
the latent heat exchanger described above,
[0120] at least one of the inlet header and the outlet header has a
header main body in a dish shape and a header cover in a dish shape
to be internally fitted to the header main body,
[0121] the header main body and the header cover are connected by
brazing such that openings face each other,
[0122] the header main body has a main body bottom plate having
connection holes to be connected to the upstream ends or the
downstream ends of the heat absorbing pipes and a main body
peripheral wall extended from a peripheral end of the main body
bottom plate toward a header cover side and opened toward the
header cover side,
[0123] the header cover has a cover bottom plate having an inflow
port or an outflow port and a cover peripheral wall extended from a
peripheral end of the cover bottom plate toward a header main body
side and opened toward the header main body side, and
[0124] the header main body and the header cover are formed such
that an outer surface of the cover peripheral wall fits into an
inner surface of the main body peripheral wall and a brazing
reservoir is formed between the inner surface of the main body
peripheral wall and the outer surface of the cover peripheral wall,
in a state where the header main body and the header cover are
fitted to each other.
[0125] In a conventional way of connecting a header main body and a
header cover, the brazing material has been applied only on edge
face of the main body open end of the main body peripheral wall, so
that scattering and dripping of the brazing material easily occur,
whereby the header main body and the header cover are difficult to
connect to each other reliably. On the other hand, according to the
latent heat exchanger described above, the brazing reservoir is
formed between the inner surface of the main body peripheral wall
and the outer surface of the cover peripheral wall, in a state
where the header main body and the header cover are fitted to each
other in order to connect the header main boy in a dish shape to
the header cover in a dish shape by brazing. Accordingly, not only
scattering and dripping of the brazing material can be prevented in
a brazing process, but also a connection area between the inner
surface of the main body peripheral wall and the outer surface of a
cover peripheral wall can be enlarge, as compared to a case where
the brazing material is applied only on the edge face of the main
body open end as the conventional method.
[0126] In the latent heat exchanger having the header including the
structure described above,
[0127] the main body peripheral wall may be formed such that the
main body open end is widen outwardly.
[0128] According to the latent heat exchanger described above, it
makes possible to enlarge the connection area between the inner
surface of the main body peripheral wall and the outer surface of
the cover peripheral wall easily.
[0129] In the latent heat exchanger having the header including the
structure described above,
[0130] at least a part of the main body open end of the main body
peripheral wall may be extended higher than an outer peripheral
surface of the cover bottom plate in a cross-sectional direction,
in a state where the header main body and the header cover are
fitted to each other.
[0131] According to the latent heat exchanger described above, it
makes possible to further enlarge the connection area between the
inner surface of the main body peripheral wall and the outer
surface of the cover peripheral wall.
[0132] In the latent heat exchanger having the header including the
structure described above,
[0133] a claw, which is bent toward the header cover side after the
header main body and the header cover are fitted to each other, may
be formed in the main body open end of the main body peripheral
wall.
[0134] When the header main body and the header cover are brazed to
each other, the header cover is pressed into the header main body
firstly. However, due to fabrication errors of both peripheral
walls of those members, the header cover may be shifted with
respect to the header main body after pressing-in. As a result, the
header main body is not connected to the header cover precisely. On
the other hand, the claw to be bent toward the header cover side is
provided on the main body open end of the main body peripheral
wall, such a shift of the header cover can be prevented by bending
the claw after the header cover is pressed into the header main
body.
[0135] Preferably, in the latent heat exchanger having the header
including the structure described above,
[0136] the main body peripheral wall is formed into substantially a
rectangular shape having a pair of long sides and a pair of short
sides, and
[0137] the claw is formed in at least one of the main body open end
of the pair of the long sides.
[0138] More preferably, claws are respectively formed in the main
body open end of the pair of the opposing long sides of the main
body peripheral wall, and
[0139] the claws of the main body peripheral wall formed in the
long sides are respectively arranged such that they are not
overlapped in a short side direction.
[0140] According to the latent heat exchanger described above, the
shift of the header cover upon fitting the header cover to the
header main body can be reliably prevented.
[0141] According to yet another preferable aspect of the present
invention whose object is to manufacture a water heater having a
plurality of heating circuits,
[0142] the latent heat exchanger described above further
comprising:
[0143] a second heat absorbing pipe accommodated in the casing and
arranged in parallel with the heat absorbing pipe;
[0144] a second inlet header for introducing second fluid to be
heated into the second heat absorbing pipe;
[0145] a second outlet header for discharging the second fluid to
be heated from the second heat absorbing pipe, wherein
[0146] the other side wall has a second upstream end-inserting hole
through which an upstream end of the second heat absorbing pipe is
inserted and a second downstream end-inserting hole through which a
downstream end of the second heat absorbing pipe is inserted,
and
[0147] the second inlet header and the second outlet header are
respectively disposed outside the other side wall and connected to
the upstream and downstream ends of the second heat absorbing pipe
led outside the other side wall through the second upstream
end-inserting hole and the second downstream end-inserting
hole.
[0148] According to the latent heat exchanger described above, in
the latent heat exchanger used for a water heater having the
plurality of the heating circuits, not only corrosion due to the
drain can be prevented, but also the latent heat exchanger can be
manufactured easily.
[0149] Further, according to the present invention, a water heater
having the latent heat exchanger described above can be
provided.
[0150] The present application claims priorities under the Paris
Convention on Japanese patent applications No. 2010-290153, No.
2010-290154, and No. 2010-290155, all of which are filed on Dec.
27, 2010, and entire contents of which are incorporated herein by
reference.
INDUSTRIAL APPLICABILITY
[0151] According to the present invention, there can be provided a
latent heat exchanger and water heater using thereof which are
excellent in durability and easy manufactured.
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