U.S. patent number 3,634,651 [Application Number 05/095,203] was granted by the patent office on 1972-01-11 for serological incubator.
This patent grant is currently assigned to Becton, Dickinson and Company. Invention is credited to Roger A. Chevalaz, Edward J. Rapoza, Maxwell E. Siegel.
United States Patent |
3,634,651 |
Siegel , et al. |
January 11, 1972 |
SEROLOGICAL INCUBATOR
Abstract
A hollow heat resistant plastic body has openings in a top
surface thereof for receiving carriers containing objects to be
heated, each opening has a hinged hood formed to enclose parts of
the carrier that extend above the top surface of the body. Each
opening has associated therewith a spring-loaded elevator platform
for sealing the opening to prevent air leakage when the platform is
not being used and for lowering into the body when a carrier is
placed thereon. A blower is positioned within the body and adjacent
to a thermostatically controlled heater for circulating air over
the entire heater. A calibrated adjustable air inlet and baffles
are provided to optimize the air circulation within the body and to
maintain a uniform temperature.
Inventors: |
Siegel; Maxwell E. (Sussex,
NJ), Rapoza; Edward J. (Butler, NJ), Chevalaz; Roger
A. (Rockaway, NJ) |
Assignee: |
Becton, Dickinson and Company
(East Rutherford, NJ)
|
Family
ID: |
22250630 |
Appl.
No.: |
05/095,203 |
Filed: |
December 4, 1970 |
Current U.S.
Class: |
219/400; 219/413;
219/521; 236/3; 392/382; 600/22; 219/386; 219/433; 219/530; 237/3;
422/109 |
Current CPC
Class: |
B01L
9/06 (20130101); B01L 7/00 (20130101); B01L
7/02 (20130101) |
Current International
Class: |
C12M
1/00 (20060101); B01L 9/00 (20060101); B01L
7/02 (20060101); B01L 9/06 (20060101); B01L
7/00 (20060101); F27d 011/02 () |
Field of
Search: |
;219/400,413,521,523,530,540,378,380-381,386-399,433 ;237/3
;236/2,3,5 ;23/253 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Mayewsky; Volodymyr Y.
Claims
What is claimed is:
1. An incubator for heating reactants contained in open ended test
tubes to a selected temperature, comprising:
a body member having an inner chamber and openings in a top surface
thereof for inserting the test tubes into the chamber;
a spring-loaded platform associated with each opening for sealing
the associated openings when the platform has no test tubes placed
thereon and for lowering into said chamber when test tubes are
placed thereon;
hood means for enclosing the openings and the portions of the test
tubes that extend above the top surface;
electrical heating means for heating a gas within the chamber;
thermostat means in thermal contact with the gas for controlling
said heating means in response to gas temperature; and
circulating means for circulating the gas throughout the chamber
and over the heating means, whereby the open ends of the test tubes
are not subjected to circulating gas and evaporation of the
reactants is minimized.
2. An incubator as described in claim 1, wherein the support means
additionally comprises a carrier for holding the test tubes upright
and for retaining the spring-loaded platform in the chamber.
3. An incubator as described in claim 1, wherein each spring-loaded
platform comprises:
a pair of posts mounted vertically beneath the top surface of the
body member;
a level platform slidably mounted to said posts for vertical
motion; and
leaf springs positioned beneath the platform for urging the
platform in an upward direction to seal the associated opening.
4. An incubator for heating materials contained in containers to
selected temperatures, comprising:
a body member having an inner chamber and openings in a surface
thereof for inserting the containers into the chamber;
spring-loaded platform means associated with each opening for
supporting the inserted containers and for sealing the associated
opening when the platform has no containers placed thereon;
hood means for sealing the openings and enclosing any portion of
the containers that extend above the surface of the body
member;
electrical heating means for heating a gas within the chamber;
thermostat means in thermal contact with the gas for controlling
said heating means in response to gas temperature; and
circulating means for circulating the gas throughout the chamber
and over the heating means, whereby the openings are sealed by the
spring-loaded platform when no containers are placed on the
platform.
5. An incubator as described in claim 4, wherein the hood means is
constructed of a transparent material.
6. An incubator as described in claim 4, additionally comprising
carrier means for supporting containers to be heated.
7. An incubator as described in claim 4, wherein the heating means
comprises a heating rod contained within the chamber and extending
substantially across the chamber, and the circulating means
comprises a tangential blower positioned adjacent said heating rod
and having a length substantially equal to that of the heating
rod.
8. An incubator as described in claim 4, additionally comprising
baffle means for establishing a circulation path throughout the
entire chamber, and a screen baffle extending across the
circulation path, whereby uniform heat distribution is provided
within the chamber when the containers are unevenly inserted in the
chamber.
9. An incubator as described in claim 4, additionally comprising a
variable gas inlet positioned so that the circulating means draws
unheated gas into the chamber and mixes it with heated gas and
calibrated to provide uniform heat distribution within the chamber
at selected temperatures.
10. An incubator for heating objects such as reactants contained in
open ended test tubes to predetermined temperatures,
comprising:
a body member having an inner chamber and openings in a top surface
thereof for inserting test tubes into the chamber;
spring-loaded platform means associated with each opening for
sealing the associated opening when there are no test tubes placed
thereon and for supporting said test tubes within the chamber so
that the open end of the test tubes extend above the top surface of
the incubator and out of the openings;
hood means for closing the openings and enclosing the portions of
the test tubes that extend above the top surface;
an electric heating rod contained within the chamber and extending
substantially across the chamber;
a tangential blower positioned adjacent said heating rod and having
a length substantially equal to that of the heating rod so that the
fan circulates air over the entire length of the heating rod;
a baffle for establishing a path to circulate the air throughout
the chamber;
a screen baffle extending across the circulation path, to provide
uniform heat distribution within the chamber when loaded with
odd-shaped or unsymmetrically loaded test tube rocks;
a variable air inlet positioned relative to said fan so that air is
aspirated into the chamber, said air inlet being calibrated at
selected temperatures to provide uniform heat distribution within
the chamber; and
thermostat means in thermal contact with the air within the chamber
for controlling the electrical heating rod in response to the air
temperature, whereby the air within the chamber is maintained at a
selected temperature.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to serological incubators and more
particularly to an incubator that utilizes warm air circulation to
maintain a prescribed temperature.
2. Description of the Prior Art
Incubators are widely used in chemical procedures to aid reactions
by maintaining the reactants at a specified temperature. In the
Blood Bank of the clinical laboratory, for instance, many tests
require a temperature of 37.degree. C., or body temperature, while
in Serology, 56.degree. C. is a commonly used temperature.
In the prior art there were two types of incubators in general use,
the water bath and the dry bath or heat block type of incubator.
The water bath type of incubator maintained a tank of water at a
prescribed temperature. There were several advantages to this type
of incubator, one being that it held a relatively stable
temperature with little variation throughout the tank if a
circulating pump was used. The water bath warmed objects quickly
and accepted entire test tube racks or other odd-shaped containers.
However, the water bath incubator had disadvantages such as loss of
water due to evaporation, mold growth, rusting and messiness all of
which required maintenance time. The water bath incubator also
required extremely long warmup time prior to being brought to the
prescribed temperature; therefore, they were usually left in the
heated condition continuously to be immediately available when
needed. This consumed excessive power and also created a dangerous
condition in the laboratory.
The dry-bath-type incubator usually consisted of a block of
aluminum, drilled to receive test tubes or other objects of various
sizes. Its advantages included convenience, relatively rapid warmup
time and elimination of the disadvantages of the water bath type of
incubator. However, its major disadvantage was its lack of
flexibility in that it could not receive odd-shaped objects or
entire racks of test tubes. The aluminum block had to be predrilled
to the size test tubes that were to be used. Test tubes had to be
individually inserted and removed thus increasing the likelihood of
identification errors while consuming excessive time.
Heating ovens have been used in the prior art and in these devices
air or other gaseous fluids were heated by a heating element and
then circulated by a fan. Generally, these devices did not achieve
a uniform heat distribution and did not provide optimum heat
transfer from the heating element to the fluid. Undesirable
temperature variations existed in different areas of the oven in
the form of hot and cold pockets of uncirculated air.
SUMMARY OF THE INVENTION
The present invention contemplates a warm air incubator which
combines the advantages of both the dry bath and water bath
incubators while eliminating the difficulties encountered with
heating ovens. Such an incubator has the flexibility of the water
bath in that it accepts various shaped containers such as test tube
carriers while having the cleanliness and rapid warmup of the
dry-bath-type incubator. The present invention provides continuous
temperature control over a range from room temperature to
60.degree. C. for general purpose use and it is factory calibrated
at the two most common clinical temperatures, namely 37.degree. C.
and 56.degree. C.
A hollow body has a tangential blower which circulates air over the
entire length of a heating rod to provide maximum heat transfer to
the air from the rod and to uniformally distribute the heated air
throughout the hollow body. The heating rod is controlled by a
variable thermostat utilized to select a desired temperature.
Openings are provided in a top surface of the hollow body for
receiving carriers, each opening having a hinged hood formed to
enclose portions of the carriers that extend above the top surface.
Associated with each opening is a spring-loaded elevator platform
upon which a carrier is placed. The platform is lowered into the
body and retained therein against the forces of the spring loading
by retaining stops formed on the carrier. When the carrier is
removed the platform rises up and seals the associated opening
thereby minimizing air leakage from within the body.
When a carrier containing test tubes is placed on the platform and
the platform is lowered into the hollow body and open ends of the
test tubes extend above the top surface and are not subjected to
the air circulation within the body, thus minimizing evaporative
losses of reactants contained within the test tubes. The hoods
enclose the portion of the test tubes extending above the top
surface and prevent loss of heated air.
Uniform temperature is maintained throughout the space within the
body by the use of baffles and a calibrated variable air inlet. The
baffles establish a circulation path throughout the body and the
variable air inlet is calibrated at 37.degree. C. and 56.degree. C.
to provide optimum circulation and to compensate for air leakages
and extraneous heat inputs.
A 1-hour mechanical timer having an audible alarm is provided for
setting various incubation times and for providing a warning when
the selected times have expired.
The present invention provides a serological incubator that has
rapid warmup time so that it may be turned off when not in use. The
device is flexible in that it receives carriers of test tubes or
other odd-shaped containers while requiring less maintenance
because it is not subject to rusting, water evaporation or mold
growth as were the water-bath-type incubators of the prior art.
One object of the invention is to provide a serological incubator
having fast warmup time in comparison with those of the prior
art.
Another object of the present invention is to provide an incubator
that can receive carriers of test tubes or odd-shaped
containers.
Another object of the invention is to provide an incubator that can
receive a larger quantity of test tubes than most incubators of the
prior art.
Another object of the present invention is to provide an incubator
that has a selectable temperature over a range from room
temperature to 60.degree. C.
Another object of the invention is to provide an incubator
utilizing warm air for heating and having a minimum of air loss
during operation.
Another object of the invention is to provide a warm air incubator
having a uniform temperature distribution.
Another object of the invention is to provide a warm air incubator
that reduces reactant evaporation from open test tubes.
Another object of the invention is to provide a warm air incubator
that has increased heating efficiency and uniform heat
distribution.
The foregoing other objects and advantages of the invention will
appear more fully hereinafter from a consideration of the detailed
description which follows, taken together with the accompanying
drawings wherein one embodiment of the invention is illustrated by
way of example.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of an incubator built in accordance with the
present invention.
FIG. 2 is a sectional view of the incubator shown in FIG. 1 taken
along line 2--2 of FIG. 1 with a portion of the screen baffle cut
away.
FIG. 3 is a sectional view similar to that shown in FIG. 2 but with
a test tube carrier shown inserted in one of the openings of the
incubator.
FIG. 4 is a elevation view of the incubator of FIG. 1 with a
portion of the body cut away.
FIG. 5 is a cross-sectional view taken along line 5--5 of FIG.
1.
FIG. 6 is a schematic diagram showing the electrical connections
within the incubator of FIG. 1.
FIG. 7 is a isometric view of a carrier used with the present
invention.
DESCRIPTION OF THE INVENTION
Referring to FIGS. 1 and 2 there is shown a base member 1 formed of
a heat resistant plastic and having feet 3 formed therein and a
flange 5 formed around the periphery thereof. A body member 7 also
formed of heat resistant plastic has an inwardly extending flange 9
positioned adjacent flange 5 and secured thereto by mounting screws
11 so that body member 7 and base 1 define a chamber 6. Body member
7 has openings 13 formed in a top surface thereof for receiving
carriers. Member 7 has formed therein a control panel 15 for
mounting control and indicator devices thereon.
A rocker-type on-off switch 17 is mounted on the control panel and
adjacent thereto are mounted pilot lights 19 and 21 for indicating
when power is being applied to the incubator and heater
respectively. A mechanical 1-hour timer 23 is mounted below control
panel 15 and has a shaft extending upward therethrough with a knob
25 mounted above the control panel on said shaft for setting a
selected time. Timer 23 has a bell for sounding an alarm when a
selected time period has elapsed. Inscribed on the control panel
about knob 25 are numerals 27 indicating the minutes remaining
before the timer provides the alarm. A preheat indication is
inscribed on control panel 15 at approximately the 5-minute
position of timer 23, said position indicates the time required to
preheat the air within the incubator to a selected temperature.
Within chamber 6 there is positioned a baffle member 31 formed of a
sheet metal material and having front and rear downturned portions
33 and 35 respectively and flanged portions 37 and 39. Flanged
portions 37 and 39 have self-clinching standoffs 41 attached
thereto and extending downward therefrom. Standoffs 41 are tapped
to receive mounting screws 45 for mounting baffle member 31 to base
member 1 and within chamber 6. A thermostat 47 is mounted below
baffle 31 by a mounting bracket 49 and mounting screws 51.
Thermostat 47 has a shaft 53 extending through side portion 33 and
through member 7. A knob 55 is mounted to shaft 53 for setting
thermostat 47. Referring to FIG. 4 there is shown knob 55 and
surrounding said knob is a rotatable indicating plate 57 for
indicating thermostat temperature settings. A set screw 59 is
adapted to fix plate 57 at a particular position after calibration
of thermostat 47 is accomplished at the factory.
Associated with each opening 13 are a pair of posts 61 shown most
clearly in FIG. 2. Posts 61 are upstanding from baffle 31 and are
tapped for receiving mounting screws 63 for attaching posts 61 to
baffle 31. The upper ends of posts 61 are received in cylindrical
receptacles 65 formed in member 7. An elevator platform 67 is
associated with each of the openings 13 and is slidably mounted
between posts 61 for vertical motion. Leaf springs 69 located
between baffle 31 and platforms 67 are provided for urging platform
67 to its maximum upward position in which position platforms 67
seal openings 13.
Referring to FIG. 7 there is shown a carrier 71 used in the
incubator of the invention. The carrier is designed to hold objects
for insertion into the incubator, the embodiment shown is designed
to hold test tubes and microscope slides. One skilled in the art
can easily design other embodiments for holding other objects to be
heated. The carrier shown is made of plastic material and has two
end members 123 having upward extensions forming handles 125. The
end members are slit along lines extending from each side of
handles 125 so that the handles may flex. Retaining stops 122 are
formed about midway down each handle. Crossmembers 127 and 129 are
cemented parallel to each other and between the end members at the
top and midpositions respectively of the end members. A lower
crossmember 131 is cemented between the end members substantially
near the bottom and parallel to the crossmembers 127 and 129.
Crossmembers 127 and 129 have notches 133 formed therein adjacent
handles 125 to allow the handles to flex inwardly. Also formed in
members 127 and 129 are circular openings 135 for receiving test
tubes and slots 137 for receiving microscope slides. Each circular
opening and slot in member 127 has an associated opening or slot in
member 129 so that the test tubes and slides stand straight up.
Referring to FIG. 3 there is shown the incubator of FIG. 2 with a
carrier 71 containing test tubes 73 inserted in one of the openings
13 and resting on one of platforms 67. The weight of carrier 71 and
test tubes 73 may force platform 67 in a downward direction against
the force of springs 69 so that platform 67 is at its lowest
vertical position and the lower portions of test tubes 73 are
within chamber 6. However, if the weight is not sufficient then the
carrier is pressed downward until retaining stops 122 on carrier 71
engage a lip formed around openings 13 of body member 7 to retain
the platform in its lowest position. The upper portions of test
tubes 73 extend above the top surface of member 7; therefore, hoods
75, made of clear plastic, are provided to enclose the upper
portions of test tubes 73 and prevent air leakage when a platform
is not sealing an opening. Each hood 75 has a tab 76 formed thereon
for engagement with an opening 77 formed in member 7. Said
engagement forming a hinge whereby hood 75 may be opened as shown
in FIG. 3. If desired one hood may be used to cover all of the
openings. To remove carrier 71 each handle 125 is flexed inwardly
until stops 122 disengage the lip and the carrier is lifted
out.
Referring to FIGS. 4 and 5 a blower assembly 79 has end brackets 81
and 83 mounted to flanged portions 85 and 87 respectively of baffle
member 31. Mounting screws 89 secure end brackets 81 and 83 to the
associated flanges of baffle 31. A heating rod is mounted between
end brackets 81 and 83 by nuts 85 threaded on a threaded rod 91
passing through heater 93. Heating rod 93 is of sufficient length
to extend substantially across chamber 6. Heater 93 is of open wire
construction and has an electrical rating of about 200 watts. A
tangential blower member 97 is rotatably mounted adjacent and
parallel to heating rod 93 and between end brackets 81 and 83. Fan
97 has a shaft 99 drivably connected to a motor 101 which is
mounted to end bracket 81. Mounted between end brackets 81 and 83
is a semicircular baffle member 103 that partially encloses fan 97
as shown most clearly in FIG. 4. Fan 97 rotates in a
counterclockwise direction as indicated by arrow 104 in FIG. 4 for
circulating air in a direction as indicated by arrows 105 around
baffle 31. The blades of fan 97 are substantially equal in length
to heating rod 93 so that the air circulates over the entire length
of rod 93 for maximum heat exchange while fan 97 is a tangential
blower it functions like a paddle wheel.
An adjustable air inlet is shown generally at 107 and comprises a
raised segmental area 111 formed on the top surface of member 7. A
segmental opening 112 is provided in area 111 for allowing air to
enter chamber 6. A screen member 109 is mounted on the inner
surface of member 7 below opening 112. A shutter member 113 is
slidably mounted between screen 109 and raised area 111 for varying
the effective opening formed in raised area 111. Indices 115 are
inscribed on raised area 111 to indicate the proper shutter
position for optimum air circulation within the incubator for the
two most commonly used temperatures. These indices are inscribed at
the factory during calibration of the incubator. The adjustable air
inlet functions to provide uniform heat distribution at various
temperatures by providing the optimum air circulation within the
incubator and for compensating for air leaks out of the incubator.
Opening 112 is located above fan 97 so that the fan draws air into
the chamber to compensate for air leakages out of the chamber and
to prevent overheating from extraneous heat sources such as the
blower motor.
Referring to FIG. 4 baffle screens 139 made of perforated sheet
metal are mounted to baffle 31 to provide a constant resistance to
air circulation. Screens 139 extend across chamber 6 to assure a
uniform circulation of air in the chamber when test tubes are
loaded only in one end of carrier 71. Without the screens the air
tends to follow the path of least resistance and bypasses the test
tubes when they are unevenly loaded. Screens 139 equalize the
airflow to maintain a uniform heat distribution.
A power cord and plug assembly 116 is provided for connecting to
any convenient power source. Cord 116 enters member 7 through a
rubber grommet 117 which prevents air leaks and protects the power
cord.
Referring to FIG. 6 there is shown plug 116 electrically connected
to switch 17 which is a double-pole throw-type switch having two
outputs each connected to fan motor 101. Pilot light 19 is
connected across the outputs of switch 17 to indicate when switch
17 is in the on position and providing power to the incubator.
Series connected between the outputs of switch 17 are a safety
control 119, thermostat 47 and heater 93. Safety control 119 is of
a type that opens a circuit when the temperature is increased above
a specified limit. A device such as the Dual Mite Model No. 206
available from Thermo Engineering Company, Akron, Ohio, may be used
for the present invention. Such a device is calibrated to open a
circuit at a temperature of about 170.degree. F. Pilot light 21 is
connected in parallel with heater 93 to indicate when power is
being provided to the heater.
In operation, prior to inserting a carrier knob 25 is turned to the
preheat position so that the air within the incubator is heated to
a desired temperature which is selected with knob 55. After the
preheat period the temperature of the air within the incubator
should be as indicated by knob 55 and then a carrier is placed on
one of the platforms 67 and pressed down until the stops 122 engage
the lip of the opening to retain the platform in space 6 within the
incubator. The associated hood 75 is placed over the carrier to
seal the opening and prevent warmed air from escaping. If the other
openings 13 are not being utilized the associated platforms 67 are
in their uppermost position and seal openings 13 to prevent air
leakage therethrough. Knob 25 is then turned to the desired
incubation time after which period the timer 23 sounds an audible
alarm notifying the operator that the incubation period has
elapsed.
Referring to FIG. 4 it may be noted that baffle 31 extends
horizontally to a position adjacent fan 97. Baffle 31 functions to
establish an oval flow pattern within the incubator. The
counterclockwise rotation of fan 97 establishes a counterclockwise
flow of air about baffle 31. Baffle 103 functions to direct the air
returning from under baffle 31 back into the blades of fan 97 where
it is again forced under baffle 31 and around the counterclockwise
oval path. Fan 97 tends to draw a limited amount of air through
opening 112 as shown by arrows 121. Air entering opening 112
compensates for air leakage out of chamber 6 and mixes with air
that has passed over heating rod 95 to prevent overheating. Opening
112 is located near the motor end of blower 79 to compensate for
excess heat radiated by the motor.
It may be noted from viewing FIG. 3 that the upper portions of test
tubes 73 extend into hoods 75 and are thus protected from the flow
of warm air around baffle 31 thus minimizing evaporative loss of
the reactants within test tubes 73. The incubator is not limited to
receiving test tubes or microscope slides, the carriers may be
designed to hold any odd-shaped objects.
Thus, the present invention provides a serological incubator having
a fast warmup time so that the device may be shut off when not in
use. The incubator has a continuous temperature range from room
temperature to 60.degree. C. and can receive entire test tube
carriers or odd-shaped containers thus reducing the possibility of
mislabeling and identifying the test tubes. A long maintenance-free
life is expected since the incubator is not subject to rust or mold
formation as were those of the prior art. Maximum heating
efficiency and uniform heat distribution are achieved by the use of
a tangential blower, baffles and a calibrated variable air
inlet.
* * * * *