U.S. patent number RE32,933 [Application Number 07/158,879] was granted by the patent office on 1989-05-30 for environmental test chamber.
This patent grant is currently assigned to Venturedyne, Ltd.. Invention is credited to Donald Vander Schaaf.
United States Patent |
RE32,933 |
Vander Schaaf |
May 30, 1989 |
Environmental test chamber
Abstract
A test chamber device comprising a generally enclosed chamber a
first duct communicating with the chamber and including therein
selectively operable heating coils, a second duct communicating
with the chamber and including therein selectively operable
refrigerating coils, and a damper for closing the second duct when
the heating coils are operating so that the refrigerating coils are
isolated from air flow in the chamber.
Inventors: |
Vander Schaaf; Donald (Holland,
MI) |
Assignee: |
Venturedyne, Ltd. (Milwaukee,
WI)
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Family
ID: |
26855470 |
Appl.
No.: |
07/158,879 |
Filed: |
February 22, 1988 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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Reissue of: |
646699 |
Aug 31, 1984 |
04572283 |
Feb 25, 1986 |
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Current U.S.
Class: |
165/61;
62/159 |
Current CPC
Class: |
F25D
17/06 (20130101); F25D 31/005 (20130101) |
Current International
Class: |
F25D
17/06 (20060101); F25D 31/00 (20060101); F25B
029/00 () |
Field of
Search: |
;165/61,65,21,30,101,103,60 ;62/325,159 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1823550 |
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Oct 1960 |
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DE |
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2420644 |
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Dec 1974 |
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DE |
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2650686 |
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Jun 1979 |
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DE |
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7932377 |
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Nov 1980 |
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DE |
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Primary Examiner: King; Lloyd L.
Attorney, Agent or Firm: Michael, Best & Friedrich
Claims
I claim:
1. A test chamber device comprising
a generally enclosed chamber, and
means for circulating and alternatively heating and cooling the air
in said chamber, said means including
alternatively operable heating means and refrigerating means,
a first duct having said heating means therein and including a
first end communicating with said chamber, and a second end,
a second duct having said refrigerating means therein and including
a first end, and a second end communicating with said chamber,
and
means for selectively connecting said second end of said first duct
to said first end of said second duct when said refrigerating means
is operating, and for selectively isolating said refrigerating
means when said heating means is operating by opening said second
end of said first duct to said chamber and closing said first end
of said second duct.
2. A test chamber device as set forth in claim 1 wherein said
second end of said first duct has a first opening communicating
with said first end of said second duct and a second opening
communicating with said chamber, and wherein said means for
connecting said second end of said first duct to said first end of
said second duct includes a damper selectively and alternatively
operable between a first position wherein said damper opens said
first opening and closes said second opening, and a second position
wherein said damper opens said second opening and closes said first
opening, with said second end of said second duct remaining in
communication with said chamber.
3. A test chamber device as set forth in claim 1 wherein said
second duct is generally vertically oriented with said second end
being the lower end, and wherein said device further includes means
in said second end for draining water condensed on said
refrigerating means.
4. A test chamber device as set forth in claim 1 wherein said first
end of said first duct communicates with said chamber through a
third opening having said fan therein, and wherein said device
further comprises a boot registering with said third opening and
extending into said chamber for directing the air from said first
duct onto an object within said chamber.
5. A test chamber device as set forth in claim 4 wherein said third
opening is downwardly facing, wherein said boot extends downwardly
into said chamber, and wherein said chamber is adapted to have the
object positioned beneath said boot.
6. A test chamber device comprising
a generally enclosed chamber,
a first duct having therein selectively operable heating means and
including a first end communicating with said chamber, and a second
end,
a second duct having therein selectively operable refrigerating
means and including a first end, and a second end communicating
with said chamber,
said second end of said first duct having a first opening
communicating with said first end of said second duct and a second
opening communicating with said chamber, and
means for connecting said second end of said first duct to said
first end of said second duct when said refrigerating means is
operating, and for opening said second end of said first duct to
said chamber and closing said first end of said second duct when
said heating means is operating, said means including a damper
selectively and alternatively operable between a first position
wherein said damper opens said first opening and closes said second
opening, and a second position wherein said damper opens said first
opening and closes said second opening.
7. A test chamber device as set forth in claim 4 wherein said means
for circulating the air further includes a fan positioned in said
third opening in said first end of said first duct for blowing air
from said first end of said first duct into said chamber.
8. A test chamber device as set forth in claim 1 wherein said means
for circulating the air further includes a fan positioned in said
first end of said first duct for blowing air from said first end of
said first duct into said chamber.
9. A test chamber device comprising
a generally enclosed chamber,
a first duct having a first end communicating with said chamber and
a second end including a first opening, and a second opening
communicating with said chamber,
a second duct extending generally vertically and having an upper
end communicating with said first opening and a lower end
communicating with said chamber,
alternatively operable heating means and refrigerating means, said
heating means being located in said first duct and said
refrigerating means being located in said second duct,
means in said lower end of second duct for draining water condensed
on said refrigerating means.
a fan in said first end of said first duct for blowing air into
said chamber,
a flexible boot registering with said first end of said first duct
and extending generally downwardly into said chamber for directing
the air from said first duct onto an object positioned beneath said
boot within said chamber, and
a damper selectively and alternatively operable between a first
position wherein said damper opens said first opening and closes
said second opening so that said second end of said first duct
communicates with said first end of said second duct, and a second
position wherein said damper opens said second opening and closes
said first opening so that said first end of said second duct is
closed to said chamber and said second end of said first duct
communicates with said chamber, with said second end of said second
duct remaining in communication with said chamber. .Iadd.
10. A test chamber device comprising a generally enclosed chamber,
air heating means, air refrigeration means said heating and
refrigerating means being alternatively operable, means for
.[.preventing.]. .Iadd.controlling air flow over both said heating
and refrigerating means and further operative to prevent air flow
over said refrigerating means when said heating means is operating,
and single means for circulating air over said heating means and
into said chamber when said heating means is operating and for
circulating air over said refrigerating means and into said chamber
when said refrigerating means is operating. .Iaddend. .Iadd.
11. A test chamber device as set forth in claim 10 and further
comprising a first duct having therein said heating means and
communicating with said chamber, and a second duct having therein
said refrigerating means and communicating with said chamber, and
wherein said single means circulates air through said first duct
when said heating means is operating and circulates air through
said second duct when said refrigerating means is operating.
.Iaddend. .Iadd.12. A test chamber device as set forth in claim 11
wherein said second duct is generally vertically oriented and has a
lower end, and wherein said device further includes means in said
lower end for draining water condensed on said refrigerating means.
.Iaddend.
.Iadd.13. A test chamber device as set forth in claim 11 wherein
said first duct includes a first end communicating with said
chamber and a second end, wherein said second duct includes a first
end and a second end communicating with said chamber, and wherein
said device further comprises means for selectively connecting said
second end of said first duct to said first end of said second duct
when said refrigerating means is operating, and for opening said
second end of said first duct to said chamber and closing said
first end of said second duct when said heating means is operating.
.Iaddend. .Iadd.14. A test chamber device as set forth in claim 13
wherein said second end of said first duct has a first opening
communicating with said first end of said second duct and a second
opening communicating with said chamber, and wherein said means for
connecting said second end of said first duct to said first end of
said second duct includes a damper selectively and alternatively
operable between a first position wherein said damper opens said
first opening and closes said second opening, and a second position
wherein said damper opens said second opening and closes said first
opening, with said second end of said second duct remaining in
communication with said chamber. .Iaddend.
.Iadd. 5. A test chamber device as set forth in claim 13 wherein
said first end of said first duct communicates with said chamber
through a third opening, and wherein said device further comprises
a boot registering with said third opening and extending into said
chamber for directing the air from said first duct onto an object
within said chamber. .Iaddend. .Iadd.16. A test chamber device as
set forth in claim 11 wherein said single means includes a fan
which circulates air through said first duct when said heating
means is operating and which circulates air through said second
duct when said refrigerating means is operating. .Iaddend.
.Iadd.17. A test chamber device as set forth in claim 10 wherein
said single means includes a fan which circulates air over said
heating means when said heating means is operating and which
circulates air over said refrigerating means when said
refrigerating means is operating. .Iaddend.
.Iadd.18. A test chamber device comprising a generally enclosed
chamber, first duct means having therein heating means and
communicating with said chamber, second duct means having therein
refrigerating means and communicating with said chamber, said
heating and refrigerating means being alternatively operable, and
means for preventing air flow over said refrigerating means when
said heating means is operating, said means for preventing air flow
comprising damper means for controlling air flow through both of
said first and second duct means, said damper means being
selectively operable in a first mode for directing air flow through
said second duct means and over said refrigerating means, and said
damper means being selectively operable in a second mode for
directing air flow through said first duct means and over said
heating means. .Iaddend. .Iadd.19. A test chamber device as set
forth in claim 18 wherein said first duct means includes a first
end communicating with said chamber, and a second end, wherein said
second duct means includes a first end, and a second end
communicating with said chamber, wherein said damper means is
operable in said first mode for connecting said second end of said
first duct to said first end of said second duct, and wherein said
damper means is operable in said second mode for opening said
second end of said first duct to said chamber and closing said
first end of said second duct. .Iaddend.
.Iadd. A test chamber device as set forth in claim 19 wherein said
second end of said first duct means has a first opening
communicating with said first end of said second duct means and a
second opening communicating with said chamber, and wherein said
damper means is operable between first and second positions
corresponding to said first and second modes, respectively, said
damper means operating in said first position to open said first
opening and close said second opening, and said damper means
operating in said second position to open said second opening and
close said first opening, with said second end of said second duct
means remaining communication with said chamber. .Iaddend.
.Iadd.21. A test chamber device as set forth in claim 19 wherein
said first end of said first duct communicates with said chamber
through a third opening, and wherein said device further comprise a
boot registering with said third opening and extending into said
chamber for directing the air from said first duct onto an object
within said chamber. .Iaddend. .Iadd.22. A test chamber device as
set forth in claim 18 wherein said second duct means is generally
vertically oriented and has a lower end, and wherein said device
further includes means in said lower end for draining water
condensed on
said refrigerating means. .Iaddend. .Iadd.23. A test chamber device
as set forth in claim 18 and further comprising single means for
circulating air through said second duct means when said damper
means is in said first mode and for circulating air through said
first duct means when said damper means is in said second mode.
.Iaddend. .Iadd.24. A test chamber device as set forth in claim 23
wherein said single means includes a fan which circulates air
through said second cut means when said damper means is in said
first mode and which circulates air through said first duct means
when said damper means is in said second mode. .Iaddend. .Iadd.25.
A test chamber device as set forth in claim 18 and further
comprising a housing enclosing said chamber, said first and second
duct means and said
damper means. .Iaddend. .Iadd.26. A test chamber comprising, in
combination,
means defining an enclosed chamber,
heating means,
refrigerating means,
said heating means and refrigerating means being alternatively
operable,
duct means associated with each of said heating and refrigeration
means and with said chamber so that air can be circulated through
said duct means, over said heating and refrigerating means and
through said chamber,
means for circulating air through said duct means, over said
heating and refrigerating means and to and from said chamber,
and
damper means associated with said duct means for controlling air
flow over both said heating and refrigerating means, said damper
means being operative to provide air flow over said refrigerating
means and to and from said chamber, and said same damper means
being further operative to provide air flow over said heating means
while simultaneously interrupting
said air flow over said refrigerating means. .Iaddend. .Iadd.27.
The test chamber of claim 26 wherein said circulating means
comprises a single fan. .Iaddend. .Iadd.28. The test chamber of
claim 26 and further comprising a housing enclosing said chamber,
said heating and refrigerating means, said duct means and said
damper means. .Iaddend.
Description
BACKGROUND OF THE INVENTION
The invention relates to test chambers for subjecting an object to
varying environmental conditions, such as varying temperature and
humidity. More particularly, the invention relates to the
circulation of conditioned air in such test chambers.
In prior test chambers, a heater in the circulation system is used
to heat the air and a refrigeration coil in the system is used to
cool the air. If the refrigeration coil remains in the path of air
circulation when hot air is being circulated, the heated air picks
up moisture from frost and ice on the refrigeration coil. Since the
object being tested is at a lower temperature than the moisture
containing heated air, undesirable condensation on the object will
result as the heated air passes over it.
Another problem with prior test chambers is the time lag between
shifting from a hot condition to a cold condition, and vice versa.
This occurs because it is often necessary to heat or cool the
entire test chamber before the temperature of the object being
tested is sufficiently changed. Accordingly, a great deal of time
is wasted.
SUMMARY OF THE INVENTION
The invention provides a test chamber device comprising a generally
enclosed chamber, and a system for alternatively circulating hot
and cold air in the chamber. The circulating system includes
alternatively operable heating means and refrigerating means, and
means for isolating the refrigerating means from the circulation
system when the heating means is operating. Preferably, the heating
means includes heating coils and the refrigerating means includes
refrigeration coils, with both sets of coils exposed to air
circulating in the system.
In the preferred embodiment, the circulating means further includes
conduit means having opposite first and second ends adapted to
communicate with the chamber. A fan associated with the conduit
means causes the flow of air into the chamber. The heating and
refrigeration coils are within the conduit means. Preferably, the
conduit means includes a first duct associated with the heating
coils and a second duct associated with the refrigeration coils.
The conduit means further includes means for selectively connecting
the first duct to the second duct when the refrigerating coils are
operating, so that cool air is directed into the chamber, and for
selectively isolating the refrigerating means from the chamber when
the heating coils are operating, so that the refrigeration coils
are out of the air circulating system when heated air is being
delivered to the chamber.
In the preferred embodiment, a damper is provided in the
circulating system to alternatively expose the refrigeration coils
to the circulating air during the cooling cycle and isolate the
refrigeration coils from the circulating air during the heating
cycle. Also, in the preferred embodiment, the conduit means in
which the refrigeration coils are exposed to the air is generally
vertically oriented and includes means for draining water dripping
from the refrigeration coils.
Preferably, the first duct communicates with the chamber through an
opening in which the fan is positioned, and the device further
includes a flexible boot registering with the fan and extending
into the chamber for directing the air from the first duct onto an
object in the chamber. The chamber is adapted to have the object
positioned beneath the boot.
A principal feature of the invention is the provision of means for
isolating the refrigerating means from the air flow when the
heating means is operating. This prevents condensation on the
object being tested, since the heated air does not pass over the
refrigerating means and cannot pick up moisture from the
refrigeration coils.
Another principal feature of the invention is the provision of a
boot for directing the air from the first duct onto the object.
This reduces the time lag when shifting temperature conditions
since the conditioned air is directed onto the object and it is not
necessary to heat or cool the entire test chamber in order to heat
or cool the object.
Other features and advantages of the invention will become apparent
to those skilled in the art upon review of the following detailed
description, claims, and drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a test chamber embodying the
invention.
FIG. 2 is a cross-sectional view taken along line 2--2 in FIG.
1.
Before explaining one embodiment of the invention in detail, it is
to be understood that the invention is not limited in its
application to the details of construction and the arrangements of
components set forth in the following description or illustrated in
the drawings. The invention is capable of other embodiments and of
being practiced or being carried out in various ways. Also, it is
to be understood that the phraseology and terminology used herein
is for the purpose of description and should not be regarded as
limiting.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a the chamber device 10 for subjecting an
object 12 to varying temperature conditions is illustrated. The
device 10 includes a front wall 14 having a door 16, a rear wall 18
opposite the front wall 14, a top wall 20, and a bottom wall 22
defining a test chamber 23. The device 10 is adapted to have the
object 12 placed in the bottom of the test chamber 23. In the
illustrated construction, the object 12 is supported by a shaker 24
extending through the bottom wall 22 of the device 10 for shaking
the object 12. While such shaking means is not part of the
invention, it should be understood that such a shaking means can be
included in a device embodying the invention.
The device 10 also includes means for alternatively circulating hot
and cold air in the chamber 23. In the preferred embodiment, such
means includes alternatively operable heating means 26 and
refrigerating means 28, and means for isolating the refrigerating
means 28 when the heating means 26 is operating. Isolating the
refrigerating means 28 prevents condensation collected on the
refrigeration means from being transferred to the object 12, since
the heated air does not pass over the refrigerating means 28.
While various suitable means can be employed for isolating the
refrigerating means, in the preferred embodiment, the means
includes a generally horizontal first duct 30 having the heating
means 26 therein, and a generally vertical second duct 32 having
the refrigerating means 28 therein. The first duct 30 runs along
the top wall 20 of the device 10 and has a first or left end
communicating with the chamber 23, and a second or right end
opposite the first end. The first or left end of the first duct 30
includes an opening 34 communicating with the chamber 23. A fan 36
draws air through the first duct 30 and directs it through the
opening 34 into the chamber 23. The fan 36 is powered by a motor
38. The second duct 32 runs along the rear wall 18 of the device 10
and has a first or upper end positioned adjacent the second or
right end of the first duct 30, and a second or lower end near the
bottom of the chamber 23 and communicating with the chamber 23
through an opening 39.
The device 10 also includes means for selectively connecting the
second or right end of the first duct 30 to the first or upper end
of the second duct 32 when the refrigerating means 28 is operating
and for selectively isolating the refrigerating means 28 from the
first duct when it is not. This includes means for opening the
second or right end of the first duct 30 to the chamber 23 while
closing the first or upper end of the second duct 32 when the
heating means 26 is operating and the refrigeration means 28 is
not.
In the preferred embodiment, the heating means 26 is of
conventional construction and includes heating coils in duct 30,
Similarly, the refrigerating means 28 is of conventional
construction and includes refrigeration coils in duct 32.
In the illustrated construction, the second or right end of the
first duct 30 has a first opening 40 communicating with the first
or upper end of the second duct 32, and a second opening 42
communicating with the chamber 23. The means for connecting the
second end of the first duct 30 to the first end of the second duct
32 includes a damper 44. The damper 44 is mounted on a generally
horizontal shaft 46 which is rotatably mounted within the second
duct 32. The damper 44 is selectively and alternatively movable
between a first or generally horizontal position (shown in solid
lines in FIG. 1) wherein the damper 44 opens the first opening 40
and closes the second opening 42, so that the second duct 32
communicates with the first duct 30, and a second or generally
vertical position(shown in phantom in FIG. 1) wherein the damper 44
opens the second opening 42 and closes the first opening 40, so
that air will circulate only through the first duct 30 and not
through the second duct 32.
As best shown in FIG. 2, the device 10 includes a motor 48 operably
connected to the damper shaft 46 for moving the damper 44 between
the first and second positions. The motor 48 can be controlled by
any suitable control means, and such control means would preferably
be part of the means (not shown) for controlling overall operation
of the device 10.
If the preferred embodiment, the device 10 further includes a drain
50 in the second or bottom end of the second duct 32 for draining
water condensed on the refrigeration coils.
The device 10 further comprises, in the preferred embodiment, a
flexible boot 52 registering with the opening 34 in the first or
left end of the first duct 30 and extending downwardly into the
chamber 23 for directing the air from the first duct 30 onto the
object 12. The boot 52 reduces the time lag in shifting temperature
conditions, since the air from the first duct 30 is directed onto
the object 12, and it is not necessary to heat or cool the entire
chamber 23 in order the heat or cool the object 12.
In operation and assuming the test device 10 is in a test mode
where cold, refrigerated air is being circulated over the object
12, the damper 44 will be in the solid line position illustrated in
FIG. 1. A continuous airflow conduit is then defined through ducts
30 and 32. Air is drawn into that continuous conduit by fan 36 with
the air circulating through the conduit over the object 12 and
returning to the conduit through the lower opening 39 in the duct
32. Both the refrigeration coils 28 and the heating coils 26, which
are not energized, are in that airflow circuit.
When it is desired to subject the object 12 to hot air, the
refrigeration coils 28 are turned off and the heating coils 26 are
turned on. Also, the damper 44 is rotated to assume the dotted line
position in FIG. 1. With the damper 44 in that position, the duct
32 is removed from the air circulation system, i.e., isolated from
the airflow circuit. The air circulated in the test chamber 23 by
fan 36 now follows a path through the boot 52 over the object 12
and returns to the air circulation conduit through opening 42 and
passes only over the heating coils 26.
By isolating the refrigeration coils 28 from the air circulation
flow, several advantages are obtained. During the cold air or
refrigeration cycle, moisture will condense and freeze on the coils
28 in a well known manner. If the refrigeration coils 28 are left
in the airflow circulation system when the heating coils 26 are
energized, the hot air flowing over the coils will melt any frozen
condensation and the hot air will then absorb moisture from the
coils. That moisture laden air will flow through the conduit and
onto the object 12. In the heating cycle, the object 12 will be at
a temperature blow the heating air until it is brought up to
temperature. Since it is cooler than the moisture laden air, the
moisture in that air will tend to condense out on the object 12.
This is an extremely undesirable result in a test procedure. By
isolating the refrigeration coils 28 from the air circulation
system, the hot air does not make circulation contact with the
refrigeration coils 28 and cannot pick up the moisture from the
coils 28, and in that respect the device 10 keeps the test sample
relatively moisture free.
Another advantage from the disclosed preferred embodiment resides
in the fact that the duct 32, although isolated from the airflow
circuit, still has open communication with the interior of the test
chamber 23 through the lower opening 39. The significance of this
arrangement is that the refrigeration coils 28 will be the coldest
spot in the overall test chamber 23. Any moisture which may be
contained in the test chamber air tends to migrate to the coldest
spot available. That coldest spot available being the refrigeration
coils 28, the moisture will migrate from the circulating air
through opening 39 to the coils 28 and condense out on the coils
28. This further contributes to keeping the object 12 generally
moisture-free during the hot cycle portion of the test
procedure.
As a result of the isolation of the refrigeration coils 28 and the
face that on the hot cycle the refrigeration coils 28 will act in
the nature of a dehumidifier, it is not necessary to include costly
mechanisms such as air purge systems to change the air in the test
chamber 23 each time the device 10 changes from a hot to cold cycle
or vice versa. Such purge systems are expensive and also require
time between test cycles thereby lengthening the overall test
procedure. These problems and disadvantages are obviated by the
preferred embodiment.
The drain 50 provides a ready and convenient means for conveying
any condensation collected on the coils 28 and/or melted during the
heating cycle out of the test chamber 23.
Various other features of the invention are set forth in the
following claims.
* * * * *