Information
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Patent Grant
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6324853
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Patent Number
6,324,853
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Date Filed
Thursday, September 28, 200023 years ago
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Date Issued
Tuesday, December 4, 200122 years ago
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Inventors
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Original Assignees
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Examiners
- Bennett; Henry
- Jones; Melvin
Agents
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CPC
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US Classifications
Field of Search
US
- 062 275
- 062 148
- 062 155
- 062 349
- 062 351
- 062 444
- 062 452
- 062 80
- 062 298
- 062 151
- 062 440
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International Classifications
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Abstract
A de-icing system operable to facilitate the removal of ice from the door (18) and closure surface (22) of a low temperature refrigeration or ultra-low freezer device (10) and to thereby ensure proper operation of the device (10) and protect its contents. The de-icing system employs manually activated heaters (32) and a timing circuit (38) to thaw the ice. Because the de-icing system focuses heat only on specific, ice-sensitive areas, the temperature of the freezer's interior compartment (14) remains constant so that the contents need not be removed during the de-icing process. In use, an operator activates the de-icing system a few minutes prior to opening the freezer door (18). When the door (18) is opened, the melted or loosened ice can be removed with a soft cloth. If the operator forgets that the heaters have been activated, the timing circuit (38) automatically terminates the de-icing process and stops the heaters (32) before the freezer's interior storage temperature has been affected. Optional thermal fuses (42) provides a safety cut-off should the timing circuit (38) fail or the heaters (32) exceed a pre-established temperature.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to devices for preventing the accumulation of ice in low temperature refrigeration devices. More particularly, the invention relates to heating devices for facilitating the removal of accumulated ice from the doors and corresponding closure surfaces of low temperature refrigeration devices, including ultra-low temperature freezers.
2. Description of the Prior Art
Low temperature refrigeration devices, especially ultra-low freezers, are commonly used in laboratory settings for storing biological samples. These freezers typically operate between approximately −40° C. and −95° C., and can develop substantial ice build-up around the door seal and closure surfaces depending on frequency of entry, ambient temperature, and humidity conditions. The accumulated ice can have seriously debilitating affects on freezer performance, including interfering with proper door sealing and interior accessibility, and overloading the door latching and mounting mechanisms. Even moderate amounts of ice build-up can so interfere with proper sealing that the required interior temperature cannot be maintained or can only be maintained by overworking the cooling mechanism. When this happens, valuable, perhaps irreplaceable, freezer's contents may be damaged by thawing.
A well-known method of de-icing involves allowing the built-up ice to thaw naturally. This inconveniently entails removing the entire contents of the iced freezer to a second freezer, and waiting for the ice to thaw. Any attempt to artificially hasten thawing, including prying the ice loose, pouring hot water on the ice, or placing space heaters nearby, can damage the door seals or other components of the freezer unit.
SUMMARY OF THE INVENTION
The de-icing system of the present invention presents novel enabling technology operable to facilitate the removal of ice from the door seals and closure surfaces of a low temperature refrigeration or ultra-low freezer device and thereby ensuring proper performance and preventing damage to the device and its contents. The de-icing system employs built-in manually activated heaters and a timing circuit to efficiently and conveniently thaw the accumulated ice. Because the de-icing system focuses heat only on specific, ice-sensitive areas of the freezer, the interior temperature remains relatively constant so that the freezer's contents need not be removed during the de-icing process. The reliable, mechanical timing circuit automatically terminates the process after a predetermined period of time. Optional thermal fuses provide a safety cut-off in the event the heaters exceed a pre-established maximum temperature.
In use, an operator activates the de-icing system a few minutes prior to opening the freezer's door. When the door is opened, the melted or loosened ice can be removed from the door and closure surfaces with a soft cloth. Either the timing circuit or the the thermal fuses will automatically terminate the de-icing process before the freezer's interior storage temperature is detrimentally affected.
These and other important aspects of the present invention are more fully described in the section entitled DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT, below.
BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figures, wherein:
FIG. 1
is a perspective view of an ultra-low freezer unit showing the placement of the heating elements of a preferred embodiment of the present invention.
FIG. 2
is a schematic of the heating and timing circuit of a preferred embodiment of the present invention.
FIG. 3
is a sectional view of an ultra-low freezer further illustrating placement of the heating elements.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
Referring to
FIG. 1
, an ultra-low freezer unit
10
is shown which incorporates the de-icing system of the present invention to prevent ice accumulation on the door seal and closure surfaces of the freezer
10
. The freezer
10
, which is itself entirely conventional, broadly comprises an insulated housing
12
; an interior storage compartment
14
; an opening
16
; a door
18
; and a cooling mechanism
20
. The de-icing system of the present invention may be used with any conventional freezer such as those manufactured and sold by Revco, Harris, Ontario Ovens Inc., and Sanyo.
The housing
12
is preferably insulated and of a material and design suitable for both maintaining the interior temperature of the freezer
10
and protecting the contents from damage. The housing
12
encloses the interior compartment
14
wherein the freezer's contents are stored at low temperatures. Although the interior compartment
14
is shown as a single large cavity, the interior space may be divided into a plurality of interior compartments.
An opening
16
in both the housing
12
and the interior compartment
14
provides access to the low temperature interior environment and the contents located therein. A door
18
is hingedly mounted to the housing
10
and positionable to cover the opening
16
when closed. The door
18
is preferably insulated to the same degree as the housing
12
, and preferably includes a gasket or seal which corresponds to the closure surface
22
surrounding the opening
14
and operable to ensure a tight seal and little, if any, air transfer when the door
18
is closed. Alternatively or additionally, the closure surface
22
may include a gasket or seal for the same purpose.
The cooling mechanism is operable to transfer ambient heat from the interior compartment
14
to the environment exterior of the insulated housing
12
. Various suitable cooling mechanisms are well-known and readily available, and the present invention is independent of any particular cooling mechanism.
For various reasons, ice is likely to accumulate on the closure surface
22
and corresponding portions of the door
18
. The rate of ice build-up depends on such factors as frequency of entry, ambient temperature, and humidity conditions. This ice may interfere with proper mating and sealing of the door
18
and closure surface
22
, thereby allowing air transfer and creating conditions under which maintaining the desired temperature of the interior compartment
14
is difficult or impossible.
The de-icing system of the present invention is operable to periodically thaw the ice, thereby facilitating its removal and ensuring proper operation of the device
10
. The de-icing system is shown in
FIG. 2
as an electrical circuit
30
comprising at least one heating element
32
; an activation switch
34
; an indicator light
36
; and a timing circuit
38
.
The heating elements
32
are operable to warm the closure surface in order to melt or loosen accumulated ice and thereby facilitate the ice's removal. A plurality of strategically placed heating elements
32
are preferred, though a single element could be used. The preferred positioning of the heating elements with regard to the refrigeration device as a whole is illustrated in
FIGS. 1 and 3
. The heaters
32
are preferably built into or mounted behind the closure surface
22
. Thermally conductive foils (not shown) may be used to concentrate heat on the closure surface
22
and corresponding door portions.
The activation switch
34
is operable to initiate the de-icing process by energizing the heating elements
32
and starting the timing circuit
38
. The indicator light
36
visually communicates that the de-icing process is in progress. The light
36
activates when the switch
34
is closed and remains lit while the heating elements
32
are producing heat. The de-icing process terminates and the heaters
32
de-energized when a pre-established time or temperature condition is satisfied.
The timing circuit
40
is operable to close an internal switch
40
when the activation switch
34
is activated, thereby allowing the heaters
32
to produce heat. The circuit
38
is further operable to measure a predetermined period of time, preferably fifteen minutes, following activation, and to terminate the de-icing process at the expiration of that time by opening the internal switch
40
to cause the heaters
32
to de-energize. Thus, the timing circuit
38
is included as a safety feature to prevent continuous heat input. Absent the timing circuit
38
, the heaters
32
might run indefinitely, possibly damaging nearby gaskets or seals, or undesirably raising the temperature of the interior compartment
14
. The timing circuit
38
is preferably mechanical in nature rather than electronic.
Thermal switches
42
operable to power-down the heaters
32
after reaching a predetermined temperature may be included as an alternative or in addition to the timing circuit
38
. The thermal switches
42
are preferably resettable fuses.
To use the de-icing system, an operator depresses the activation switch
34
, thereby energizing the heating elements
32
and starting the timing circuit
38
. The indicator light
36
activates to indicate that the de-icing process has begun. After a few minutes, the operator opens the door
18
to the refrigeration device
10
and removes with a soft cloth any water or loose ice resulting from de-icing. The timing circuit
38
causes the heaters
32
to de-energize and the light
36
to extinguish fifteen minutes after the switch
34
was activated. If the heaters
32
reach a predetermined temperature at any time, the optional thermal switches
42
terminate the de-icing process without regard to the timing circuit
38
.
From the preceding description, it can be seen that the de-icing system of the present invention efficiently and conveniently facilitates the removal of accumulated ice from freezer doors and closure surfaces. It is noted that the present invention is a de-icing system independent of any particular freezer or refrigeration device.
Applications are contemplated for the de-icing system herein described that require only minor modifications to the system as disclosed. Thus, although the invention has been described with reference to the preferred embodiment illustrated in the attached drawings, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims.
For example, the circuit
30
may be integrally incorporated into new freezers during manufacture, or may be produced in stand-alone form for use with existing refrigeration devices. Furthermore, the heating elements
32
, timing circuit
38
, and other components may be any suitable off-the-shelf or custom equipment, as practical and desirable.
Claims
- 1. A de-icing system for use with a refrigeration device having a door and corresponding closure surface susceptible to the accumulation of ice, the de-icing system being operable to facilitate the removal of the ice from the door and closure surface, the de-icing system comprising:at least one heater positioned near the closure surface and operable to apply heat to the door and closure surface in order to facilitate the removal of accumulated ice; an activation switch operable to cause the heater to produce heat; and a timing circuit operable to automatically cause the heater to stop producing heat after a predetermined period of time.
- 2. The de-icing system of claim 1, further comprising at least one thermally conductive foil operable to concentrate the heat produced by the heater.
- 3. The de-icing system of claim 1, further comprising at least one thermal switch associated with each heater and operable to cause the heater to stop producing heat when the heat reaches a predetermined temperature.
- 4. The de-icing system of claim 3, the thermal switch being a resettable thermal fuse.
- 5. A refrigeration device comprising:a housing enclosing at least one storage compartment, with the housing having at least one opening for providing access to the storage compartment; at least one door positionable and operable to cover and seal the opening along a closure surface, the door and closure surface being susceptible to ice accumulation; and a de-icing system comprising at least one heater positioned near the closure surface and operable to apply heat to the door and closure surface in order to facilitate the removal of accumulated ice; an activation switch operable to cause the heater to produce heat; and a timing circuit operable to automatically cause the heater to stop producing heat after a predetermined period of time.
- 6. The refrigeration device of claim 5, further comprising at least one thermally conductive foil operable to concentrate the heat produced by the heater.
- 7. The refrigeration device of claim 5, further comprising at least one thermal switch associated with each heater and operable to cause the heater to stop producing heat when the heat reaches a predetermined temperature.
- 8. The refrigeration device of claim 7, the thermal switch being a resettable thermal fuse.
US Referenced Citations (9)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0911591 A1 |
Apr 1999 |
EP |