Refrigeration – With means preventing or handling atmospheric condensate... – By external heater
Reexamination Certificate
2001-11-15
2004-02-03
Doerrler, William C. (Department: 3744)
Refrigeration
With means preventing or handling atmospheric condensate...
By external heater
C062S278000, C062S196100, C219S553000, C219S542000, C219S523000
Reexamination Certificate
active
06684659
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a refrigerator having a defrosting device for defrosting an evaporator with a heater.
BACKGROUND ART
In recent years, art associated with a freezing refrigerator having a defrosting device for an evaporator is disclosed in Japanese Unexamined Patent Publication No. HEI 8-54172. A schematic side sectional view showing a structure thereof is shown in FIG.
31
. Hereinafter, a conventional freezing refrigerator will be explained by referring to the drawings.
In
FIG. 31
, reference numeral
1
denotes a refrigerator housing. Reference numeral
2
denotes a freezing chamber located inside the refrigerator housing
1
. Reference numeral
3
denotes a refrigerator chamber located inside the refrigerator housing
1
. Reference numeral
4
denotes a door of the freezing chamber. Reference numeral
5
denotes a door of the refrigerator chamber. Reference numeral
6
denotes a partition wall for partitioning the freezing chamber
2
and the refrigerator chamber
3
from each other. Reference numeral
7
denotes an inlet port of the freezing chamber
2
for sucking air into the freezing chamber. Reference numeral
8
denotes an inlet port of the refrigerator chamber
3
for sucking air into the refrigerator chamber. Reference numeral
9
denotes a discharge port for discharging cool air. Reference numeral
10
denotes an evaporator. Reference numeral
11
denotes a fan for circulating cool air.
Reference numeral
12
denotes a partition wall of the evaporator
10
for partitioning the evaporator and the freezing chamber
2
. Reference numeral
13
denotes a basin. Reference numeral
14
denotes a drain outlet. Reference numeral
15
denotes a defrosting tube heater in which a Nichrome wire held in a coil-like configuration is covered with a glass tube. Reference numeral
16
denotes a roof for preventing an evaporation sound, generated when a defrost water is directly dripped on the defrosting tube heater
15
. Reference numeral
17
denotes a metal-made bottom surface plate mounted between the basin
13
and the defrosting tube heater
15
to be insulated and held.
In this conventional refrigerator, when the freezing chamber
2
and the refrigerator chamber
3
are cooled, coolant is allowed to flow through the evaporator
10
so that the evaporator
10
is cooled. In the same manner, with operation of the fan
11
, air having an increased temperature in the freezing chamber
2
and the refrigerator chamber
3
is sent to a cooling chamber, and this air is cooled via heat exchange in the evaporator
10
. Then, the cooled air is sent to an interior of the freezing chamber
2
from the discharge port
9
so that cold air is sent to the refrigerator chamber
3
through a communication port (not shown) from the freezing chamber
2
.
Generally, air which has undergone heat exchange within the evaporator
10
is highly humidified with an inflow of high temperature outside air as a result of frequent opening and closing of door
4
and door
5
, and evaporation of moisture content of conserved food in the freezing chamber
2
and the refrigerator chamber
3
, or the like, so that moisture in the air becomes frosted and adheres to the evaporator
10
, which has a temperature lower than the air. With an increase in frost quantity, heat transmission with air undergoing heat exchange with a surface of the evaporator
10
is hindered, while a heat passage ratio is lowered because of lowering of conveyed air quantity resulting from ventilation resistance, with a result that a cooling shortage is generated.
Therefore, before a frost quantity becomes superfluous, the Nichrome wire of the defrosting tube heater
15
is electrified. When electrification of the Nichrome wire is started, heat is radiated to the evaporator
10
and peripheral parts from the Nichrome wire. At this time, heat radiated to the bottom plate
17
is partially reflected according to a form of the bottom plate
17
, while remaining heat is reflected toward the evaporator
10
and the peripheral parts. As a consequence, frost which adheres to and near the evaporator
10
, the basin
13
and the exhaust port
14
is melted into water. Additionally, in this manner, a portion of defrosted water which is melted in this manner is directly dripped on the basin
13
while a remaining portion makes a detour of the defrosting tube heater
15
to fall to the basin
13
by way of the roof
16
, to be exhausted to an exterior from the drain outlet
14
.
However, with the above structure, when the defrosting tube heater
15
is generally electrified, not only a surface temperature of the Nichrome wire, but also a surface temperature of the glass surrounding the wire, come to have a high temperature. At the same time, since the bottom plate
17
is located in the vicinity of the tube heater
15
, part of heat radiated from the tube heater
15
is reflected again to the tube heater
15
with a result that a heated temperature of the tube heater
15
unusually rises and attains a value not lower than an ignition temperature of a flammable coolant to be used. Accordingly, there is a problem in that in a case where the flammable coolant is used as a coolant, leakage of the flammable coolant from piping mounted on a portion communicating with the evaporator
10
and inside of the refrigerator leads to danger of ignition of the flammable coolant with electrification of the defrosting heater
15
, so as to result in an explosion.
SUMMARY OF THE INVENTION
In view of the above problem, an object of the present invention is to provide a freezing refrigerator which can suppress danger of ignition of a flammable coolant even in a case where defrosting is conducted in an environment in which the flammable coolant is leaked to an atmosphere of a defrosting device.
In order to attain the above object, the refrigerator according to the present invention comprises a freezing cycle for connecting a compressor, a condenser, a depression mechanism and a vaporizer to seal flammable coolant, and a defrosting heater or device for defrosting the vaporizer, wherein a heated temperature of the defrosting heater during operation becomes only lower than an ignition temperature of the flammable coolant. Consequently, when the flammable coolant is leaked to an inside of the refrigerator because of breakage of piping or the like, danger of ignition is extremely lowered even when heating of the defrosting heater or device is started.
As the defrosting device, it is desirable to mount a glass tube and a heater wire formed of metal resistor inside of the glass tube. In such a case, it is desirable to heat the heater wire up to a temperature lower than the ignition temperature of the flammable coolant. Since a majority of heat resulting from the heater wire, which is a heating body, is radiated to frost which has adhered to the evaporator and peripheral parts, defrosting is conducted during a defrosting time which is the same as, or less than conventional defrosting time, while corrosion and deterioration or the like resulting from direct contact with exterior air can be prevented. Consequently, while a defrosting capability and life of the defrosting device that is the same as, or more than, conventional defrosting capability and life can be secured, a surface temperature of the heater wire which is likely to come into contact with exterior air can be set to a level that is the same as, or lower than, the ignition temperature of the flammable coolant.
It is desirable that a surface at a central portion of a length of a spiral portion of the heater wire has a heated temperature lower than the ignition temperature of the flammable coolant. By doing so, it is possible to set a surface temperature of the heater wire at the central portion, which has a high temperature, to a temperature that is the same as or lower than the ignition temperature of the flammable coolant in a length direction of the spiral portion, while securing a defrosting capability and life to be the same as, or more than, conventional defrosting capability and lif
Nishimura Koichi
Shimizu Takeshi
Tanaka Masaaki
Doerrler William C.
Matsushita Refrigeration Company
Shulman Mark S.
Wenderoth , Lind & Ponack, L.L.P.
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