Stoves and furnaces – Hot-air furnaces – Compressed air
Reexamination Certificate
2002-10-30
2003-07-29
Basichas, Alfred (Department: 3743)
Stoves and furnaces
Hot-air furnaces
Compressed air
C126S11000R, C237S055000
Reexamination Certificate
active
06598599
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a hot air space heater that is adapted to blow hot air out of a whole hot air outlet provided at a front plate of a frame of the heater, and more particularly to a hot air space heater of which the frame can be reduced in depth.
A construction of a conventional hot air space heater is shown in FIG. 1 of Japanese Patent Application Laid-open Publication NO. 316052/1999. In this construction, a combustion chamber and a fuel tank are arranged side by side in a frame of the heater, and a hot air outlet extends from a region in front of the combustion chamber toward a front of a region in which the fuel tank is located so that hot or heated air can be blown out of the whole hot air outlet. This conventional hot air space heater employs a special duct structure in order to guide air fed by a fan provided on a rear side of the frame to the hot air outlet. The duct structure has a combustion chamber space including the combustion chamber becoming narrower toward the front, and an extended air feed space spreading laterally from a front region of the combustion chamber space toward a front region of the fuel tank. In addition, a front portion of an upper wall of the duct is inclined toward the hot air outlet. In this conventional duct structure, it is impossible to permit hot air to flow through the extended air feed space without constructing the combustion chamber space narrower toward the front and inclining the front portion of the upper wall of the duct toward the hot air outlet. However, employing these constructions requires a distance between the combustion chamber and the hot air outlet to be relatively long, resulting in an increased depth of the frame of the heater.
In a conventional hot air space heater shown in FIG. 2 of Japanese Patent Application Laid-open Publication No. 316051/1999, the aforementioned extended air feed space is provided and a guide plate is mounted on at least one of louvers arranged in the hot air outlet. This guide plate has a V-shaped cross-section and is fixed onto the louver so as to direct an opening of the guide plate toward the combustion chamber. This duct structure of the heater also requires the front portion of the upper wall of the duct to be inclined toward the hot air outlet. In this hot air space heater, strong air flow without turbulence is blown against the guide plate mounted on the louver in order to guide or turn part of hot air to the extended air feed space. This heater also requires a distance between the combustion chamber and the hot air outlet (or a depth of the frame) to be relatively long because the front portion of the upper wall of the duct must be inclined. Therefore, the depth of the frame can only be reduced to a limited dimension.
Like Japanese Patent Application Laid-open Publication No. 316052/1999, Japanese Patent Application Laid-open Publication No. 4224/2001 (EP 1,217,314 A1) shows a hot air space heater that employs a specially shaped duct structure in order to permit hot air to flow into an extended air feed space.
FIG. 1 of U.S. Pat. No. 6,295,937 shows an example of a conventional hot air space heater in which a heat exchanger is arranged above a combustion chamber. In this example, the heater heats air taken into a duct structure from an indoor air intake port provided on a rear side of a frame of the heater by making the air contact with an outer wall of the combustion chamber and the heat exchanger, and then blows the heated air out of a hot air outlet. In this heater, the hot air outlet is arranged lower than the indoor air intake port.
U.S. Pat. No. 6,325,060 discloses a hot air space heater which is so constructed that a plurality of heat-exchange pipes are arranged on a combustion chamber and that a heat-exchange chamber is arranged on these heat-exchange pipes.
SUMMARY OF THE INVENTION
A hot air space heater of the present invention comprises a frame having a front plate, a rear plate, a pair of side plates connecting said front and rear plates, and a top plate. An indoor air intake port is provided at the rear plate. A hot air outlet is provided at the front plate. The hot air outlet is formed so as to extend from a position in proximity to one of the side plates to a position in proximity to the other side plate in a lateral direction, and is positioned lower than the indoor air intake port. The heater also comprises a burner arranged in the frame in a manner to be close to one of the side plates rather than at a central portion of the frame, a combustion chamber arranged on and communicating with the burner, a heat exchanger arranged on an upper plate of the combustion chamber and communicating with the combustion chamber, and a duct structure having an air feed passage therein. The heater further comprises an indoor air convection fan arranged in the vicinity of the indoor air intake port to take in indoor air into the air feed passage.
The heat exchanger, for example, includes a plurality of heat-exchange pipes extending upward from the upper plate of the combustion chamber and an exhaust gas chamber arranged on and communicating with these heat-exchange pipes.
The hot air outlet has a first hot air outlet portion positioned in front of the upper portion of the combustion chamber and the heat exchanger, and a second hot air outlet portion laterally contiguous to the first hot air outlet portion and positioned in front of a region including an accessory-receiving space.
The duct structure includes a first side wall arranged adjacent to the one side plate; a second side wall facing the first side wall in the lateral direction so as to have the upper portion of the combustion chamber, a plurality of the heat-exchange pipes, and the exhaust gas chamber positioned therebetween and also facing the other side plate of the frame in the lateral direction so as to form the accessory-receiving space therebetween; a bottom wall positioned lower than the upper portion of the combustion chamber; a top wall having a main portion thereof positioned upper than the heat exchanger; and a front wall positioned between a front end of the top wall and the hot air outlet and longitudinally extending along the front plate. The second side wall includes a first side wall portion positioned on a side of the rear plate and extending along or juxtaposedly with the first side wall and a second side wall portion connecting to the first side wall portion and extending in the lateral direction so as to form an extended air feed space laterally spreading between the second side wall portion and the second hot air outlet portion.
In the present invention, an air guide is arranged in the duct structure. The air guide is arranged along the first outlet portion of the hot air outlet facing the upper portion of the combustion chamber so as to guide or turn part of air to be blown forward out of the first hot air outlet portion to the extended air feed space. Providing such air guide in the duct structure can guide or turn part of the air directed forward through the second hot air outlet portion to the extended air feed space, even when a distance from the upper portion of the combustion chamber and the heat exchanger to the hot air outlet is reduced. In other words, hot air blown against the air guide is reflected backward and then tends to flow toward the extended air feed space having a smaller air resistance. The air guide positively guides or turns the air flow to the extended air feed space. Thus, in accordance with the present invention, a sufficient amount of hot air can also be blown forward out of the second outlet portion of the hot air outlet corresponding to the extended air feed space.
A vertical dimension or height of the hot air outlet is preferably defined so as to be able to face both the upper portion of the combustion chamber and lower portions of a plurality of the heat-exchange pipes communicating with the combustion chamber. This enables sufficient heat exchange at the heat exchanger.
The air guide is preferably formed so as to have a plate-like member ex
Basichas Alfred
Pearne & Gordon LLP
Toyotomi Co. Ltd.
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