Refrigeration – With means preventing or handling atmospheric condensate... – By external heater
Reexamination Certificate
1999-10-01
2001-01-30
Tapolcai, William E. (Department: 3744)
Refrigeration
With means preventing or handling atmospheric condensate...
By external heater
C219S536000
Reexamination Certificate
active
06178763
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a refrigeration unit with a thermal breaker and to the thermal breaker itself. More particularly, the present invention relates to a refrigeration unit with a thermal breaker that is a component used in preventing condensation from forming on the outer shell of the refrigeration unit in high humidity environments.
As known, the refrigerated wall of the refrigerated compartment of a refrigeration unit is maintained at a much lower temperature than the atmosphere outside the refrigerated compartment. As shown in
FIGS. 2A
,
2
B and
2
C, the outer shell of a typical refrigeration unit includes exterior panels
13
formed of a layer of sheet metal. As shown in
FIGS. 2A
,
2
B and
2
C, a metal panel
15
defines an inside surface the refrigerated compartment. A metal panel
16
forms a border around the opening of the refrigerated compartment and is exterior to the refrigerated compartment but in close proximity to panel
15
. The panels
13
,
15
and
16
encase heat-insulating material
14
to form the heat-insulating walls of the refrigeration unit.
Since metal evenly conducts heat, a continuous metal panel extending both inside the refrigerated compartment and outside the refrigerated compartment as part of a heat-insulating wall of the refrigerated unit would tend to maintain itself at the same equilibrium temperature. As shown in
FIGS. 2A
,
2
B and
2
C, a thermal break member
17
is fitted as a part of the refrigeration unit that connects compartment panel
15
with front panel
16
. Moreover, thermal break member
17
is formed of material that is a poor conductor of heat. Rigid polyvinylchloride is a typical material for forming thermal break member
17
.
In environments where the refrigeration unit is subjected to high humidity, as shown in
FIGS. 2A
,
2
B and
2
C, a so-called anti-sweat heater wire
18
is provided and disposed to contact front panel
16
. The purpose of such wire
18
is to keep front panel
16
warm enough to prevent condensation from forming on the exterior surface of panel
16
. As shown in
FIGS. 2A and 2C
, sometimes heater wire
18
is nestled within a conduit that is formed at least in part by thermal break member
17
. In
FIG. 2A
, the conduit housing heater wire
18
is formed in part by a forward lip portion
19
of thermal break member
17
and a recessed portion of front panel
16
. As shown in
FIG. 2B
, the conduit is formed by a length of tape
26
that adheres heater wire
18
to the inside surface of front panel
16
. As shown in
FIG. 2C
, thermal break member
17
is formed by two interlocking components
20
and
21
. The conduit is formed in part by a forward lip portion
19
of an interlocking cap component
21
, a forward edge of an interlocking panel component
20
and a flange portion
22
of front panel
16
wherein flange portion
22
is disposed at a right angle with respect to front panel
16
and parallel to inner panel
15
.
Arrangements such as shown in
FIGS. 2A
,
2
B and
2
C are effective in preventing condensation from forming on the exterior surface of front panel.
16
of a refrigeration unit so long as electric current can be provided to flow through heater wire
18
. However, circumstances can cause malfunctions of heater wire
18
, and require replacement of same. For example, a power surge could burn out a portion of heater wire
18
, or heater wire
18
could merely wear out. Once heater wire
18
malfunctions, condensation forming on the exterior surface of front panel
16
would alert the repairman of the need to replace heater wire
18
.
Replacement of heater wire
18
is a major undertaking for each of the configurations shown in
FIGS. 2A
,
2
B and
2
C. In the embodiment shown in
FIG. 2A
for example, thermal break member
17
must be removed by applying force against the inside edge
23
via a block
24
of wood and using a hammer
25
to strike the block
24
. In this way, lip portion
19
of thermal break member
17
is forced to move away from the recess of front panel
16
and thereby expose heater wire
18
so that heater wire
18
can be replaced. Upon replacement of heater wire
18
, block
24
must be placed against lip portion
19
and struck with hammer
25
to reposition thermal break member
17
back into its prior orientation as part of the wall of the refrigeration compartment. In some instances, too much damage is done to the original thermal break member
17
for it to be reused, and a new piece of thermal break member
17
must be used to replace the damaged member.
In the
FIG. 2B
embodiment, rigid polyurethane foam
14
is molded in place after heater wire
18
is attached via adhesive tape
26
to the inside surface of front panel
16
. If heater wire
18
malfunctions, it cannot be replaced without destroying thermal break member
17
and removing polyurethane foam
14
from within the compartment wall. Once heater wire
18
is replaced, polyurethane foam must be reintroduced, and a replacement thermal break member
17
must be provided and re-inserted as part of the wall of the refrigerated compartment. This replacement process is very labor-intensive and time consuming and cannot be done in the field.
In the
FIG. 2C
embodiment, thermal break member
17
comprises two interlocking components
20
and
21
. Panel component
20
is configured in a manner similar to thermal break member
17
shown in FIG.
2
B. However, panel component
20
is provided with a portion that faces toward the refrigerated compartment when disposed to connect between inside panel
15
and front panel
16
. The inner portion of panel component
20
is configured to receive thermal break cap component
21
so that cap component
21
mechanically attaches in a friction fit to panel component
20
. Moreover, when cap component
21
is attached to panel component
20
, a conduit is formed to receive heater wire
18
therein. This conduit that receives heater wire
18
is formed in part by compartment panel
15
, thermal break cap
21
, and panel component
20
. Replacement of heater wire
18
requires disengagement of thermal break cap
21
from panel component
20
of thermal break member
17
. This is accomplished by inserting a wedge such as a screwdriver blade between compartment panel
15
and the edge of thermal break cap
21
and prying thermal break cap
21
away from the friction fit interlock with panel component
20
. Once thermal break cap
21
is removed, malfunctioning heater wire
18
can be removed and replaced with a new heater wire
18
. Thereafter thermal break cap
21
can be reinserted over panel component
20
and locked thereto by the application of sufficient force to deform the mating components of panel component
20
and thermal break cap
21
until they interlock with one another. Replacement of heater wire
18
in the
FIG. 2C
embodiment can be accomplished without destroying thermal break member
17
and in a much faster manner than is possible with the embodiments shown in
FIG. 2A
or FIG.
2
B. However, the two-piece thermal break member
17
shown in
FIG. 2C
is much more expensive to manufacture due to the need for precise tolerances in order to effect the proper interlock between the two components
20
and
21
. Moreover, the assembly process for the refrigeration unit requires an additional step to attach the thermal break cap
21
to panel component
20
. In addition, manufacturing of the refrigeration unit is rendered more complicated and therefore more costly due to the need to inventory two separate components
20
and
21
for thermal break member
17
in the
FIG. 2C
embodiment.
Thus, a need exists to provide a thermal break member that is less costly to install and maintain, and at the same time facilitates replacement of the heater wire in a manner that is economical. Such replacement should be capable of being done with relatively little skill by the repairing personnel, without requiring large amounts of the repair person's time, and without destruction of the thermal break membe
Brancheau Harry A.
Branz Michael A.
Hopkins Dan G.
Yingst Thomas E.
Ali Mohammad M
Dority & Manning P.A.
Specialty Equipment Companies, Inc.
Tapolcai William E.
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