Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a hot water
supply system and, more particularly, to a storage-type
hot water supply sys-tem with a pulse combus-tor.
A pulse combustor has long been known as a com-
bustor of high combustion ef~Eiciency. A pulse combus-tor
comprises a pulse burner hav:Lng a combustion chamber,
and an elongate pipe, a so-called tail pipe, which
communicates with the exhaust side of the combustion
chamber. A pulse combus,or is a combustor which
operates similarly to a two cycle engine and performs
intermittent combustion at predetermined cycles.
~xhaust gas is exhausted while it is pulsed within
the tail pipe.
A pulse combustor as described above has the
following advantages. Air and ~uel gas are automatically
fed to the combustion chamber due to a negative pressure
generated within the combustion chamber of the pulse
burner. Therefore, a blower or fan for supplying air is
not required (except at the start of the operation of
the combustor), and the blower can be of compact size.
High load combustion can be performed, and a combustion
chamber of small size can be used. Since the fuel gas
is pulsed within the tail pipe as described above, a
thermal transfer coefficient of about 3 to 5 times that
of a conventional combustor may be obtained if such a
tail pipe is used as a heat exchanger. The pulse
combustor has other advantages. However, since the
pulse combustor has high combus-tion efficiency as
described above, i-t has a problem of creating excessive
noise.
In a conventional hot water supply system which
uses a pulse combustor as a heating source, a pulse
burner of the pulse combustor is mounted at the upper
por-tion of a storage tank. ~he tail pipe extends
from the upper portion of the storage tank toward the
lo~er portion -thereof and then extends outside the tank
from the lower portion thereof. This tail pipe is
used as a heat exchanger. The exhaust gas which is
passed through the tail pipe is cooled by a liquid
within the storage tank and is condensed. Condensed
water is thus produced within the tail pipe. In order
to facilitate smooth discharge of the condensed water
iIl the conventional hot water supply system of the type
described above, the pulse burner of the pulse combustor
is mounted on the upper portion of the storaye tank and
the tail pipe extends from the upper portion of the
storage tank to the lower portion thereofO The
conventional hot water supply system further has, for
the purpose of reducing noise, a suction muffler which
is arranged at the upper portion of the stora~e tank
and which is connected to the combustion chamber, and an
exhaust muEfler which is arranged beneath the storage
tank and which is connected to -the exhaust side of the
tail pipe. The storage tank, the suction and exhaust
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mufflers, and the pulse combustor are covered with a
soundproofing material such as concreteO
~ n a hot water supply system of the type described
above, the pulse burner and the suction muffler of the
pulse combustor are arranged at the upper portion of
the storage tank, while the exhaus-t muffler is arxanged
beneath the tank, providing a bulky overall system.
Furthermore, since the pulse burner and the tail pipe
of the pulse combustor (~.~hich are sources of noise) are
present almost throughout the entire body of the system,
soundproofing is difficult. Since the overall system
is covered with a soundproofing material, the system
becomes even more bulky and does not allow easy access
for maintenance.
The present invention has been made in consideration
of these problems and has for its object to provide
a hot water supply system, which is compact in size,
and which is capable of easily eliminating noise.
According to one aspect of the present invention,
there is provided a hot water supply system comprising:
a base of substantially cylindrical shape; a storage
tank supported on -the base, the storage tank having an
upper end plate with a hot water outlet portl and a
lower end plate supported by the base and defining,
together with an inner face of the base, a soundproofing
chamber; a pulse combustor having a pulse burner which
is attached to the lower end plate and which has a
combustion chamber, and a tail pipe which communica-tes
with the combustion chamber, is arranged inside the
storage tank next to the lower end plate, and functlons
as a heat exchanger, the tail pipe having an ascending
portion which extends from the pulse burner toward the
upper end plate, and a descending portion which extends
from a top end of the ascending portion toward the lower
end plate and into the soundproofing chamber through
the lower end plate to guide condensed water condensed
inside the tail pipe to outside the storage tank; a
blower which is arranged inside the soundproofing
chamber and which supplies air to the combustion
chamber of the pulse burner when the pulse burner is
started; a suction muffler which communicates with the
blower and which is arranged inside the soundproofing
chamber; and an exhaust muffler which communicates with
the descending portion of the tail pipe and which
is arranged inside the soundproofing chamber. The
base has a soundproofiny layer and shields noise
generated inside the soundproofing chamber.
In the hot water supply system of the present
invention as described above, the pulse combustor, the
suction muffler, the blower and the exhaust muffler are
concentrated at the lower portion of the storage tank.
For this reason, the hot water supply system of the
present invention can be made compact in size as
compared with conventional systems. In particular, the
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pulse combustor and the mufflers which are the sources
of noise are concentrated a-t the lower portion of the
storage tank as described above. Accordingly, the
noise may be easily reduced by the base which is
arranged below the storage tan~. The hot water supply
system of the present invention need not be en-tirely
covered wlth a soundproofing material as in a
conventional system and can therefore be made compact
in size. Although the pulse combustor is mounted at
the lower portion of the s-torage tank in the system of
the present invention, the condensed water produced
inside the tail pipe may be smoothly dischar~ed since
the tail pipe has a descending portion.
This invention can be more fully understood from
the following detailed description when taken in
conjunction with the accompanying drawings, in which:
Fig. 1 is a vertical sectional view of a hot water
supply system according to the first embodiment of the
present invention;
Fig. 2 is a vertical sectional view of a pulse
burner o~ the system shown in Fig. l; and
Fig. 3 is a vertical sectional view of a hot water
supply system according to tAe second embodiment of the
present invention.
The first embodiment of the present invention will
first be described in detail with reference to the
accompanying drawings.
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Referring to Fig. 1, a ho-t water supply system 10
has a cy]indrical base 12 wi-th two open ends. The base
12 is made of a soundproofing material such as
concre-te. The base 12 is placed on floor A and its
lower end is closed therehy. The hot water supply
system 10 further has a storage tank 14 supported on
the base 12. The storage ta:nk 14 has a cylindrical
circumferential wall 16, an upper end plate 18 closing
the upper end opening of the wall 16, and a lower end
plate 20 closing the lower end openlng of the wall 16.
A hot water outlet port 22 is Eormed in the upper end
plate 18, and a hot water discharge pipe 24 is
connected to the port 22. A water inlet port 26 is
formed in the wall 16 near the lower end plate 20, and
a water supply pipe 28 is connected to the port 26. A
thermostat 30 for detecting the temperature of a liquid
held inside the storage tank 14 is mounted in the wall
16 near the upper end plate 18. The lower end plate 20
has an annular engaging groove 32 which engages with
the lower edge of the wall 16. Thus, the lower end
plate 20 is detachably attached to the wall 16. The
lower end plate 20 further has a boss 34 which projects
downward from the substantially central portion
thereof. The lower end plate 20 is mounted on the
upper peri..pheral edge of the base 12 to thereby suppvrt
the storage tank 14 on the base 12. The lower end
plate 20 further seals the upper end of the base 12
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and, toge-ther wi-th the inner face of -the base 12,
defines a soundproofing chamber 36.
The hot water supply system 10 further has a pulse
combustor 38. As shown in Figs. 1 and 2, the pulse
combustor 38 has a pulse burner 40 which is attached to
the ].ower end plate 20. The pulse burner 40 has an
outwardly extendlng Elanye 41, which is securely fixed
to the boss 34 of the lower end plate 20 wlth screws.
The upper half of the pulse burner 40 projects into the
storage tank 14 through the lower end plate ~0, while
the lower half thereof is positioned inside the
soundproofing chamber 36. The pulse burner 40 has a
base plate 42 which separates the interior of the pulse
burner 40 into a combustion chamber 44 (upper half) and
an air chamber 45 (lower half). The base plate ~2 has
a gas hole 48 and a plurality of air holes 46 e~tending
through the base plate 42. The ends of the gas hole 48
and the air gas holes 46 opening to the combustion
chamber 44 are opened/closed by a flap valve 50. An
ignition plug 52 is mounted on the base plate 42 -to
extend into the combustion chamber 44. A gas pipe 54 is
connected to the end of the gas hole 48 opening to the
air chamber 45 and extends downward to be connected to
a fuel gas supply device (not shown).
The pulse combustor 38 has a tail pipe 56 which
communicates with the combustion chamber 44 of the pulse
burner 40 and which is arranged inside the storage tank
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40 adjacent to the lower end plate 20, and serves as a
heat exchanger~ The tai.l pipe 56 has an ascending
portion 58, which communicates with the combustion
chamber 44 of the pulse burner 40 and which extends
substantially vertically upward from the pulse burner ~0
toward the upper end plate 18. The tail pipe 56 further
has a descending portion 60, which extends from the
extended end of the ascending portiorl 58 toward the lower
end plate 20. The descending portion 60 extends spirally
outward and downward around the ascending portion 58.
The terminal end of the descending portion 60 ~xtends
into the soundproofing chamber 36 through the lower end
plate 20.
The hot water supply s~stem 10 has a fan 62 which
is arranged as a blower inside the soundproofing
chamber 36. A nozzle 64 of the fan 62 communicates
with the air chamber 45 of the pulse burner 40. A pair
of suction mufflers 66 are arranged inside the
soundproofin~ chambex 36 and are series-connected to
the suction side of the fan 62. A suction pipe 68 is
connected to the lower suction muffler 66, and extends
outside the base 12 therethrough. ~ pair of exhaust
mufflers 70 and a drain tank 72 are further arranged
inside the soundproofing chamber 36 and are series-
connected to the terminal end of the descending portion60 of the tail pipe 56. An exhaust pipe 74 is connected
to the drain tank 72 and extends through the base 12 and
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then upward alongside the storage tank 14. A drain
pipe 76 is connected to the drain tank 72 and extends
outside the base 12 therethrough. Reference numeral 78
denotes a solenoid valve for opening/closing the drain
pipe 76.
The mode c?f operation of the hot water supply
system lO of the construction as described above will
now be described.
When the fan 62 is driven, combustion air is
supplied -to the air chamber 45 of the pulse burner 40
through the suc-tion pipe 68 and the suction mufflers 66
and then to the combustion chamber 44 throu~h the air
holes 46. Simultaneously, fuel gas is supplied to the
combustion chamber 44 through the gas pipe 54 and the
gas hole 48 from the fuel gas supply device (not shown).
The combustion air and the fuel gas are mixed inside
the combustion chamber 44 and are combusted upon being
ignited by the ignition plug 52~ Then, the ~ressure
inside the combustion chamber 44 is rendered positive;
the flap valve 50 is urged to close the gas hole 48 and
the aix holes 46, and the exhaust gas is supplied to
the tail pipe 56. When the exhaust gas is supplied
to the tail pipe 56~ the pressure inside the combustion
chamber 44 is rendered negative. Then, the flap valve
50 receives suction to open the gas hole 48 and the
air holes 46 so that the combustion air and the fuel
gas are suc:ked into the combustion chamber 44. At this
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time, the exhaust gas suppli.ed -to the tail pipe 56 is
also sucked toward the combustion chamber 44 by -the
negative pressure inside the combustion chamber 44, and
part of the exhaust gas flows into the combustion
chamber 44~ Since the exhaust gas which has flown into
the combustion chamber 44 in this manner is at a high
temperature, the gas mixture inside the combustion
chamber 44 is automatically ignited and combusted.
Thereafter, intermittent co~lbustion .is performecl
automatically without requiring opera-tion of the fan 62
and the ignition plug 52.
The exhaust gas suppLied to the tail pipe 56 flows
therein as a pulsed fluid and is supplied to the exhaust
mufllers 70. The exhaust gas noise is reduced by the
exhaust muf~lers 70 and is exhausted to the outside from
the exhaust pipe 74 -through the drain tank 72. The
tail pipe 56 is heated by the exhaust gas to exchange
heat with the liquid inside the storage tank 14, thereby
heating this liquidO While the exhaust gas flows lnside
the tail pipe 56, it is gradually cooled by the liquid
inside the storage tank 14 and i5 condensed. Condensed
water is thus produced inside the descending portion 60
of the tail pipe 56. The length of the ascending
portion 58 of the tail pipe 56 is so set that the
2~ exhaust gas may condense within the descending portion
60. The condensed water is guided through the descending
portion 60 to the outside of the storage tank 14, and is
supplied through -the exha-lst mufflers 70 to the drain
tank 72. In order to improve -the effects of the exhaust
mufflers 70r the solenoid valve 78 arranged in the
drain pipe 76 is closed during the operation of the
S pulse combustor 38. When the pulse combustor 3~ is
inoperative, the solenoid valve 78 is opened. Then,
the condensed water in the drain tank 72 is drained
outside the base 12 -through the drain pipe 76~
The hot water supply system 10 according to the
first embodimen-t as described above has the following
advantages.
The pulse combustor 38, the fan 62, the suction
mufflers 66 and the exhaust mufflers 70 are concentrated
at the lower portion of the storage tank 14. Therefore,
the system 10 can be made compact in size as compared
with conventional systems. The lower half of the pulse
burner 40, the suction mufflers 66 and the exhaust
mufflers 70 are arranged within the soundproofing
chamber 36 defined by the lower end plate 20 and the
base 12. The base 12 is made of a soundproofing material
such as concrete~ Accordingly, noise generated by
various parts inside the soundproofing chamber 36 is
shielded. In this manner, since the pulse burner 40,
the suction mufflers 66, the exhaust mufflers 70, and
so on, are concentrated at the lower portion of the
storage tank 14, the noise may be easily eliminated by
the base 12~ The upper half of the pulse burner ~0 and
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the tail pipe 56 are arranged inside the storage tank
14, and the noise generated thereby is attenuated by the
liquid held inside the storage tank 14. For this
reason, the noise generated by the pulse burner 40 and
the tail pipe 56 hardly penetrates to outside the
storage tank l~o Since the system :L0 is compact in size
and is capable of eliminatirlg the noise, it may be easily
used for household and indus,trial applications.
The tail pipe 56 serving as a heat exchanger is
arranged at the lower portion of the storage tank 14.
Therefore, convection tends to be caused in the storage
-tank 14 so that the liquid held therein may be
efficiently heated. The tail pipe 56 has the ascending
portion 58 and the descending portion 60, and the
descending portion 60 extends spirally downward from the
top end of the ascending portion 58 toward the lower end
plate 20. The area of heat exchange is sufficient.
The descending portion 60 extends spirally downward from
the top end of the ascending portion 58 toward the lower
end plate 20, that is, inclined downward. The condensed
water produced inside the descending portion 60 can flow
to the outside o~ the storage tank 14 along the descending
portion by its own weight. Addi-tionally, the exhaust gas
pressure inside the tail pipe 56 is as high as about
800 mm Aq, and the condensed water inside the descending
portion 60 is smoothly exhausted under the pressure of
the exhaust gas. Although the pulse combustor 38 is
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arranged at the lower portion of the storage -tank 14,
the condensed water produced in the tail pipe 56 is
smoothly exhaus-ted. The lower end plate 20 is detachabl~
attached to the wall 16. Therefore, when the pulse
burner 40 or the like goes out of order, the lower end
plate 20, together with the pulse burner, may be
removed Erom the wall 16, thus facilitating easy
replacement of the par-ts or the like.
A hot water supply system according to the second
embodiment of the present invention will now be described
in detail with reference to Fig. 3. The same reference
numerals aS in Fig. 1 denote the same parts in Fig. 3,
and a detailed description thereof will be omitted.
In this embodiment, a storage tank 14 is divided
into a first section 80 with a tail pipe 56 housed
therein, and a second section 82 communicating with a
hot water outlet port 22. The storage tank 14 has a
subtank 84 defining the first section 80, and a main
tank 86 defining the second section 82. The main tank
86 has a cylindrical circumferential wall 88, an upper
end plate 18 closing the upper end opening of -the wall
88, and a lower end plate 90 closing the lower end
opening o~ the wall 88~ The hot water outlet port 22
is formed in the upper end plate 18, and a hot water
discharge pipe 24 is connected to the port 22. A water
inlet port 26 is formed in the wall 88 near the lower
end plate 90, and a water supply pipe 28 is connected
-to the port 26. The lower end pla-te 90 is supported by
the upper perlpheral edge of a base 12, and closes the
upper end thereof. ThP base 12 has a heigh-t about
twice that of the first embodiment. The subtank 84 has
a cylindrical circumfe.rential w~11 92, an upper end
plate 94 closlng the upper end opening of the wall 92,
and a lower end plate 20 closing the lower end opening
of the wall 92. The lower end plate 20 is supported b~
an annular flange 96 mounted at about the vertically
central portion of the inner face of the base 12. The
lower end plate 20, together with the inner face of the
base 12, defines a soundproofing chamber 36 below the
lower end plate 20. The lower end plate 20 also
defines, together with the inner face of the base 12
and the lower end plate 90, another soundproofing
chamber 98 above the lower end plate 20. Therefore, the
subtank 84 is arranged inside the soundproofing chamber
98. A pulse burner 40 is attached to the lower end
plate 20, and the tall pipe 56 is arranged inside the
subtank 8~ and hence, inside the first section 80. The
storage tank 14 has first and second con~unicating pipes
100 and 102 which con~unicate between the first and
second sec-ti.ons 80 and 82. One end of the first
communicating pipe 100 opens to the lower end plate 90
in the vicinity of the water inlet port 26, and the
other end thereof opens to the upper end plate 94. One
end of the second con~unicating pipe 102 opens to the
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upper end plate 94, and the pipe 102 extends into -the
second section 82 through the lower end plate 90, while
the other end of the second communicating pipe 102 opens
to the vici~ity of the hot water outlet port 22.
The hot water supply system 10 according to the
second embodiment of the present invention and having
the construction described above has the following
advantages in addition to those of the first
embodiment. The liquid lnside the second section 82 is
supplied to the fixst section 80 through the first
communicating pipe 100 and is heated by the tail pipe
56. The liquid heated therein is supplied to the
vicinity of the hot water outlet port 22 through the
second communicating hole 102 and is discharged through
the hot water outlet port 22. In this manner, the
liquid heated inside the first section 80 hardly mix
with the liquid inside the second section 82 and is
discharged through the hot water outlet port 22 while
remaining at a high tempera-ture. For this reason, the
system of this embodiment is capable of supp~ying hot
water of high tempera-ture within a relatively short
period of time. Since the subtank 84 with the tail
pipe 56 housed therein is arranged inside the sound-
proofing chamber 98, noise may be eliminated r~ore
reliably than with the first embodiment.
The embodimen-ts described above are only for
explanatory purposes, and the present invention is not
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limited -to -these embodiments. For example, the
descending portion 60 of the tail pipe 56 is spiral
or circular in -the above embodiments~ However, -the
descending portion may be wound in a rectangular shape.
If a large heat exchange area is not required, the
descendiny portion 60 may be a linear portion without
being wound. In the above embodiments, the base 12 is
made of a soundproofing material. However, the base
may he made of any other suitable material and the
inner or outer face thereof may be covered with a
soundproofing material. In the second embodiment, the
first and second sections 80 and 82 are defined by the
main tank 86 and the subtank 84 which are separated from
each other. However, the first and second sections may
be defined by a partition wall in a single tank, and
a communicating hole or a communicating pipe may be
arranged in this partition wall.
