U.S. patent application number 10/720277 was filed with the patent office on 2004-06-03 for hot-air heater.
This patent application is currently assigned to Rinnai Corporation. Invention is credited to Fujisawa, Yoshinori, Ito, Keichi, Shimonoma, Yokihiko, Yamada, Yoshimune.
Application Number | 20040105666 10/720277 |
Document ID | / |
Family ID | 32375917 |
Filed Date | 2004-06-03 |
United States Patent
Application |
20040105666 |
Kind Code |
A1 |
Shimonoma, Yokihiko ; et
al. |
June 3, 2004 |
Hot-air heater
Abstract
Because the air trunk area of the air blowing passage on the
downstream side of the air-blowing fan was kept almost constant in
a conventional hot-air heater, an electric heater provided in this
air blowing passage provided air trunk resistance by itself making
it necessary to increase the rotation speed of the air blowing fan
thereby resulting in the operating noise growing louder which, in
turn, posed a problem. Therefore, an expansion 35 was formed along
the air blowing passage 32 that passes from the intake opening 11b
through the exhaust opening 12b. This expansion functions as a
storage portion that contains the electric heater 3.
Inventors: |
Shimonoma, Yokihiko;
(Aichi-ken, JP) ; Ito, Keichi; (Aichi-ken, JP)
; Fujisawa, Yoshinori; (Aichi-ken, JP) ; Yamada,
Yoshimune; (Aichi-ken, JP) |
Correspondence
Address: |
ARENT FOX KINTNER PLOTKIN & KAHN
1050 CONNECTICUT AVENUE, N.W.
SUITE 400
WASHINGTON
DC
20036
US
|
Assignee: |
Rinnai Corporation
|
Family ID: |
32375917 |
Appl. No.: |
10/720277 |
Filed: |
November 25, 2003 |
Current U.S.
Class: |
392/360 |
Current CPC
Class: |
Y02B 30/00 20130101;
Y02B 30/28 20130101; F24H 3/0417 20130101; F24H 3/04 20130101; F24H
3/0488 20130101 |
Class at
Publication: |
392/360 |
International
Class: |
F24H 003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 27, 2002 |
JP |
343427/2002 |
Claims
What is claimed is:
1. A hot-air heater comprising: (a) an air-blowing passage leading
from an inlet to an outlet; (b) an air-blowing fan and an electric
heater, which are provided along said air-blowing passage, so that
when said air-blowing fan is operated to suck air into said
air-blowing passage through said inlet, said air is heated by said
electric heater to provide hot air, which is blasted out of said
outlet into a room, wherein an expansion is formed on said
air-blowing passage as a storage portion to contain said electric
heater.
2. The hot-air heater according to claim 1, wherein the air trunk
area decreases smoothly on the downstream side of said
expansion.
3. The hot-air heater according to claim 1, wherein a
cross-sectional area of the exit and that of the outlet of said
expansion are each increased compared to that of the entrance of
said expansion.
4. The hot-air heater according to claim 1, wherein said
air-blowing passage has a bent portion obtained by bending itself
somewhere along it and said air-blowing fan is provided with a
moving vane positioned on said bent portion, so that said expansion
positioned on the downstream side of said bent portion is provided
with said electric heater in such a manner that it intersects with
said air-blowing passage, the distance between the inner wall of
said expansion positioned on the inner side of said bent portion
and said electric heater is increased compared to that between the
inner wall of said expansion positioned on the outer side of said
bent portion and said electric heater.
5. The hot-air heater according to claim 1, wherein heat insulation
means are provided around said expansion of said electric
heater.
6. The hot-air heater according to claim 1, wherein said expansion
is adapted to have a double structure, which contains airspace.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a hot-air heater in which
an electric heater is incorporated along an air-blowing
passage.
[0003] 2. Description of the Related Art
[0004] A conventional hot-air heater, as described in Jpn. Pat.
Appln. KOKAI Publication No. 1998-132385, comprises a frame having
an outlet and an inlet formed therein. An air-blowing passage is
formed in the frame that leads from the inlet to the outlet. This
air-blowing passage is provided with an air-blowing fan on the
upstream side and an electric heater, constituting an elongated
sheathed heater etc. on the downstream side. In this case, the
electric heater is positioned in such a manner that it intersects
with the air flowing along the air-blowing passage. In this
configuration, if the air-blowing fan is operated, air is sucked
into the air-blowing passage through the inlet and heated by the
electric heater to provide hot air having a predetermined
temperature, which is blasted out of the outlet into a room.
[0005] However, in the heater described in the above publication,
the air trunk area of the air-blowing passage is kept constant all
along this passage leading from the downstream side of the
air-blowing fan to the outlet, and the electric heater is provided
somewhere along this passage to provide air trunk resistance in
this air-blowing passage (i.e., resistance against air flow in the
air-blowing passage). Therefore, to provide sufficient airflow to
the hot air to be blasted out of the outlet, it is necessary to
increase the rotation speed of the air-blowing fan; however, this
increases the operating sound, which, in turn, poses a problem. In
this case, to decrease the air trunk resistance, increasing the
cross-sectional area of the air-blowing passage may be considered
(hereinafter referred to as air trunk area); however, this
increases the size of the relevant appliance and decreases the wind
speed, which, in turn, poses a problem.
[0006] In view of the above, the object of the present invention is
to provide a hot-air heater in which the air trunk resistance, when
an electric heater is provided along an air-blowing passage, does
not increase, which thereby ensures that the wind speed at the
outlet may not decrease.
SUMMARY OF THE INVENTION
[0007] To solve the above problems, according to the present
invention, a hot-air heater comprises:
[0008] (a) an air-blowing passage leading from an inlet to an
outlet;
[0009] (b) an air-blowing fan and an electric heater that are
provided along the air-blowing passage, so that when the
air-blowing fan is operated to suck air into the air-blowing
passage through the inlet, the air is heated by the electric heater
to provide hot air, which is blasted out of the outlet into a
room,
[0010] wherein an expansion is formed along the air-blowing passage
as a storage portion to contain the electric heater.
[0011] According to the present invention, when the air-blowing fan
is operated, air is sucked into an air passage and thus reaches the
electric heater. In this case, the air trunk area of the storage
portion, in which the electric heater is contained, has been
increased so that the air-blowing resistance in this portion does
not increase and can, therefore, be made nearly equal to the
air-blowing resistance of the air-blowing passage in front of and
behind this storage portion. Therefore, the air flows through the
air-blowing passage smoothly and the rotation speed of the
air-blowing fan does not need to be increased.
[0012] In this case, if the air trunk area on the downstream side
of said expansion is decreased smoothly, the occurrence of
turbulent flow can be prevented and thus the resistance of air
flowing along an inner surface of the expansion can be decreased,
which will, thereby, further decrease the air trunk resistance.
[0013] Further, if the cross-sectional area of the exit and inlet
of said expansion are increased compared to that of the entrance of
this expansion, then the air trunk can be decreased further.
[0014] In case said air-blowing passage has a bent portion formed
halfway through it, said air-blowing fan is equipped with a moving
vane positioned at the bent portion. Furthermore, the electric
heater is positioned at the expansion, that is, on the downstream
side of this bent portion, in such a manner that it intersects with
the air-blowing passage. Thus, the volume of air flowing through
the inner side of the bent portion decreases compared to that
flowing through its outer side; therefore, the air-blowing passage
positioned on the inner side of the bent portion is overheated by
radiation heat etc. from the electric heater, increasing the risk
of the appliance itself getting overheated by the excess radiation
heat etc. Therefore, preferably, the space between the inner wall
of the expansion positioned on the inner side of the expansion and
the electric heater is increased compared to the space between the
inner wall of the expansion positioned on the outer side of the
bent portion and the electric heater. This not only ensures smooth
air flow but also prevents the overheating of the appliance.
[0015] Further, it is possible to prevent the overheating of the
appliance, which is influenced by the expansion of the electric
heater, even if this expansion is overheated by providing heat
insulation means around the expansion of said electric heater.
[0016] Furthermore, if said expansion has a double structure,
comprising the inner and outer walls of the air-blowing passage and
the airspace between them, then this structure can decrease thermal
conductivity, thereby improving the heat insulation effects.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] FIG. 1 is an explanatory plan view of the configuration of a
hot-air heater according to the present invention;
[0018] FIG. 2 is an explanatory enlarged cross-sectional view of a
part of the air-blowing passage of a conventional embodiment;
[0019] FIG. 3 is an explanatory enlarged cross-sectional view of a
part of the air-blowing passage of the present invention;
[0020] FIG. 4 is an explanatory enlarged cross-sectional view of a
part of the air-blowing passage of a variant;
[0021] FIG. 5 is an explanatory enlarged cross-sectional view of a
part of an air-blowing passage of a variant;
[0022] FIG. 6 is an explanatory enlarged cross-sectional view of a
part of an air-blowing passage of a variant;
[0023] FIG. 7 is an explanatory enlarged cross-sectional view of a
part of an air-blowing passage of a variant;
[0024] FIG. 8 is an explanatory enlarged cross-sectional view of a
part of an air-blowing passage of a variant; and
[0025] FIG. 9 is an explanatory enlarged cross-sectional view of
part of an air-blowing passage of a variant.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0026] In FIG. 1, the reference numeral 1 indicates a hybrid-type
hot-air heater according to the present invention. This hot-air
heater 1 has a box-shaped frame 11, which incorporates a gas heater
portion 2 on the top and an electric heater portion 3 at the
bottom. A first outlet 12a and a second outlet 12b are formed at
the front face of frame 11 and a first inlet 13a and a second inlet
13b are formed at the rear face of frame 11 to face the gas heater
portion 2 and the electric heater 3, respectively. This arrangement
ensures that the two air-blowing fans used to make the air-blowing
system of the gas heater portion 2 and that of the electric heater
portion 3 are independent of each other.
[0027] The gas heater portion 2 constitutes a gas burner 20 and a
first air-blowing fan 21, which is arranged below the gas burner
20. The gas heater portion 2 not only supplies the gas burner 20
with combustion air, but also mixes the combustion gas with air
sucked through the first inlet 13a in the frame 11 to blast them
out into a room. The gas burner 20 has a burner body 20a, which has
a fuel/air inlet 201 with a gas spray nozzle (not shown) mounted to
the a tip of a gas tube that is connected to a proportional valve
(not shown) arranged in the frame 11 and a mixer tube portion 202
that communicates with this inlet 201. A ceramic flame-port plate
203 having a plurality of flame ports provided thereon in a row is
mounted on the upper open face of the burner body 20a via a
distribution plate (not shown), so that the gas burner 20 is
contained in the combustion chamber 204.
[0028] The frame 11 contains a diversion plate 41 in such a manner
that it surrounds the upper portion of the combustion chamber 204.
This ensures that when the first air-blowing fan 21 is operated,
air sucked through the first inlet 13a in the frame 11 and
combustion gas discharged from the combustion chamber 204 can be
partitioned from each other until they flow at a predetermined
distance. Further, the frame 11 also contains a partition 43 in
such a manner that it covers combustion chamber 204 including the
diversion plate 41 and forms an air passage 42 to lead to the first
air-blowing fan 21 between itself and the diversion plate 41. The
air-blowing fan 21 positioned below the burner body 20a has a
housing 211 in which an air-blowing duct 211a leading to the first
outlet 12a is formed.
[0029] In the housing 211 a cross-flow type first moving vane 212
is arranged, which is connected to a first motor (not shown) whose
rotation speed can be controlled. In this case, the air passage 42
and the internal space of the housing 211 communicate with each
other through an upper-face opening 213 in the housing 211. In such
a manner, an air-blowing system of the gas heater portion 2 leading
from the first inlet 13a to the first outlet 12a is formed. In this
configuration, when the first motor is driven to rotate the first
moving vane 212, air in the room is sucked through the inlet 13a in
the frame 11 so that it can be supplied to the inlet 201 in the
burner body 20a and then flow through the air passage 42.
[0030] In this case, if fuel gas is sprayed through a gas spray
nozzle (not shown) to the inlet 201, an air-fuel mixture is
supplied to the flame port plate 203 and then burns. It should be
noted that the air/fuel ratio is adjusted by controlling the first
motor, to control the rotation speed of the first moving vane 212.
Combustion gas generated from the gas burner 20 as a result of the
burning of the air-fuel mixture passes through a combustion gas
passage 44 on an inner side of the diversion plate 41 and is sucked
toward the first air-blowing fan 21. On arriving at the downstream
end of the diversion plate 41, the combustion gas and the air are
mixed to be cooled and flow through the opening 213 in the housing
211. Then, the air-fuel mixture having a predetermined temperature
is released through the first outlet 12a into the room.
[0031] On the other hand, the electric heater portion 3 is
contained in a case 31 made of resin and has an air-blowing passage
32 leading from the second inlet 13b to the second outlet 12b. In
this case, to miniaturize the electric heater portion 3, the
air-blowing passage 32 is bent in a direction from the upper side
of the appliance 1 to the horizontal side. The bent portion 32a
obtained by thus bending this air-blowing passage 32 is provided
with a second air-blowing fan 33. The second air-blowing fan 33
constitutes a second motor (not shown), whose rotation speed can be
controlled, and a roughly cylindrical cross-flow type second moving
vane 331, which is connected to this second motor and arranged on
the bent portion 32a. The downstream side of this bent portion 32a
is provided with an electric heater 34. It should be noted that the
control of the rotation speed of the second motor does not
influence the functioning of said electric heater 34.
[0032] The electric heater 34 has a configuration in which a
combination of elongated sheathed heaters 341, which are arranged
in three vertical stages with a predetermined space in between in
such a manner that they intersect with the air-blowing passage 32,
are aligned in as many as three rows in the airflow direction so
that the sheathed heaters 341 may alternate with each other. Each
sheathed heater 341 is supported by the frame 11 via a holder (not
shown). In such a manner, an air-blowing system of the electric
heater portion 3 is formed so as to lead from the second inlet 13b
to the second outlet 12b. Then, if the second air-blowing fan 33 is
operated, air is sucked through the second inlet 13b in the
air-blowing passage 32 and heated by the electric heater 34 to
provide hot air, which is blasted out of the second outlet 12b into
the room. The hot air, when blasted out of this second outlet 12b,
may possibly overheat the floor of the room. Therefore, a lower
face 321 of the air-blowing passage 32 leading from the second
air-blowing fan 33 to the second outlet 12b is formed to incline
upward.
[0033] In this configuration, if, as shown in FIG. 2, the air trunk
area of the air-blowing passage 32 is kept constant all along this
passage leading from the downstream side of the air-blowing fan 33
to the second outlet 12b and the electric heater 34 is mounted
somewhere along this passage, the electric heater 34 itself
provides air trunk resistance in this air-blowing passage 32.
Therefore, to provide sufficient airflow to the hot air to be
blasted out of the second outlet 12b, it is necessary to increase
the rotation speed of the second air-blowing fan 33, which, in
turn, increases the operating sound and poses a problem. In this
case, increasing the cross-sectional area of the air-blowing
passage 32 may be considered to decrease the air trunk resistance.
However, in this case, the size of the electric heater portion 3
will increase and the wind velocity of the air blasted out of the
second outlet 12b will also increase, which poses a problem. To
avoid this problem, the air trunk area of the storage portion
containing the electric heater 34 has been increased so that the
expansion to decrease the influence of the electric heater 34 on
the air trunk resistance may be mitigated.
[0034] As shown in FIGS. 1 and 3, according to the present
embodiment, a metal expansion 35 leading to the second outlet 12b
is linked to the downstream end of the air-blowing passage 32 to
provide the storage portion that contains the electric heater 34.
In this case, the air trunk area is increased vertically as against
the airflow direction so that the air trunk resistance in the
expansion 35 may be roughly the same as that of the air-blowing
passage 32 on both sides of the expansion 35. Further, a
cross-sectional area of the exit of the expansion 35 is increased
compared to that of its entrance. Accordingly, the air trunk
resistance of the expansion 35 is decreased and thus air flows
smoothly all along the air-blowing passage 32, so that it is
unnecessary to increase the rotation speed of the second
air-blowing fan 33. This prevents the operating sound from
increasing.
[0035] Further, it is possible to prevent the overheating of the
gas heater portion 2, the case 3, etc., because the distance
between the inner wall face 351 of the storage portion 35 and the
electric heater 34 can be preserved and the air flowing through a
gap between the inner wall face 351 and the vertically positioned
sheathed heaters 341 of the electric heater 34 has a cooling
effect. Furthermore, only the expansion 35 of the electric heater
34 is increased in air trunk area, so that it is possible to
suppress an increase in the size of the electric heater portion
3.
[0036] Although in the present embodiment, as shown in FIGS. 1 and
3, the air trunk area of expansion 35 has been increased in such a
manner that its cross section may be rectangular, an inclined face
352 may be formed in the vicinity of the exit of the expansion 35
so that the air trunk area on the downstream side of the expansion
35 is decreased smoothly as shown in FIG. 4. In this case,
turbulent flow is prevented from occurring at the expansion 35, so
that the air-blowing resistance of air flowing along the inner face
of the expansion 35 is decreased, thus further decreasing the air
trunk resistance.
[0037] If the bent portion 32a is formed on the air-blowing passage
32 and the moving vane 331 is positioned on this bent portion 32a,
the cooling effect on the upper side of the expansion 35
deteriorates because the heated air rises and also because the
volume of air on the inner side is less than that on the outer side
of the bent portion 32a. Thus, the volume of air flowing through
the upper side is less than that flowing through the lower side of
the electric heater 34. Therefore, the upper side of the expansion
35 is overheated by radiation heat etc. from the electric heater
34, the excess heat of which is stored in the case 31, thereby
possibly overheating the gas heater portion 2 and the case 31.
[0038] Therefore, as shown in FIG. 5, the electric heater 34 may be
displaced downward or, as shown in FIG. 6, the expansion 35 may be
formed in such a manner that the distance between the upper inner
wall face 351a of the expansion 35 and the electric heater 34 is
greater than that between the lower inner wall face 351b of the
expansion 35 and the electric heater 34. Accordingly, the distance
between the upper side of the expansion portion 35 and the electric
heater 34, which is the heat source and with respect to which this
expansion portion is positioned to be easily heated by it, is
increased to facilitate air flow on the upper side of the expansion
35 and enhance heat insulation for the wall faces and the
surrounding area of the expansion 35, thereby preserving the
cooling effects and preventing overheating.
[0039] It should be noted that, as shown in FIG. 7, a separate heat
insulating material 5 may be provided around the expansion 35 to
prevent the transfer of heat from the electric heater 34 to the
case 31. In this case, an airspace is formed between the heat
insulating material 5 and the expansion 35 to provide a double
structure, which thereby prevents the heat from being radiated
externally.
[0040] Further, as shown in FIG. 8, an incurved plate material 6a
may be provided on the inner side of the expansion 35 shown in
FIGS. 1 and 3 to ensure that the air trunk area at the expansion
portion 35 changes smoothly. In this case, the air trunk area of
the expansion 35 increases smoothly from its entrance and decreases
from a position somewhere along it toward its exit. Accordingly, it
is possible to prevent turbulent flow from occurring at a turning
point of the expansion 35, thus further smoothing the air flow.
[0041] Further, the incurved plate material 6a, which is provided
as described above, causes the expansion 35 to have a double
structure and, therefore, itself has a heat blocking effect. An
airspace is formed between this plate material 6a and the inner
wall face 351 of the expansion 35, which further improves the heat
insulating effects. In this case, the incurved plate material 6a
may be made of a material having adiathermancy. Thus, it is
possible to further suppress the excess heat from spreading to the
surrounding area of the expansion 35, which, thereby, prevents the
overheating of the gas heater portion 2.
[0042] Further, as shown in FIG. 9, a plate material 6b having
adiathermancy may be incurved in a V-shape and arranged on the
inner side of the expansion 35. In this case, the sheathed heaters
341 are arranged alternately in the air-flow direction to ensure
that the air flows smoothly between the sheathed heaters 341.
* * * * *