U.S. patent application number 12/752771 was filed with the patent office on 2011-10-06 for thermally actuated turntable for conventional/convection cooking ovens.
Invention is credited to Vince S. Warner.
Application Number | 20110240005 12/752771 |
Document ID | / |
Family ID | 44708159 |
Filed Date | 2011-10-06 |
United States Patent
Application |
20110240005 |
Kind Code |
A1 |
Warner; Vince S. |
October 6, 2011 |
Thermally Actuated Turntable for Conventional/Convection Cooking
Ovens
Abstract
The present invention is a thermally actuated turntable suitable
for conventional and convection cooking ovens, which posses uneven
temperature/cooking characteristics. By means of coupling
dissimilar materials, each having a wide variance in their
respective coefficients of thermal expansion, the relative linear
expansion of these materials caused by the ambient heat found in
the cooking chamber of an oven can be utilized in such a way as to
create a thermo-linear motor and thus produce relatively small
linear displacements of the actuator with relatively high force
capabilities. This linear displacement can then be magnified by
means of the mechanical advantage of levers to produce sufficient
linear displacement of a rack and pinion gear set which is capable
of producing multiple rotations of an attached platter during a
typical short duration cooking cycle. This slow speed rotational
motion is very advantageous for cooking short duration food
items.
Inventors: |
Warner; Vince S.; (Alpine,
UT) |
Family ID: |
44708159 |
Appl. No.: |
12/752771 |
Filed: |
April 1, 2010 |
Current U.S.
Class: |
126/338 ;
99/443R |
Current CPC
Class: |
F24C 15/16 20130101 |
Class at
Publication: |
126/338 ;
99/443.R |
International
Class: |
F24C 15/16 20060101
F24C015/16 |
Claims
1. A turntable for conventional and convection ovens, the turntable
comprising: a. at least one thermally responsive actuator; b. a
linkage system, further comprising at least one lever,
operationally connected to the thermally responsive actuator; c. a
drive mechanism operationally coupled to the linkage system and
further comprising a rack and pinion gear set; and d. a turntable
platter coupled to the drive mechanism; wherein the thermally
responsive actuator changes shape while exposed to ambient heat
within an oven chamber and moves the linkage system and the
associated drive mechanism, thereby rotating the turntable
platter.
2. The turntable of claim 1, the at least one thermally responsive
actuator comprising at least two different materials with unequal
coefficients of thermal expansion.
3. The turntable of claim 2, the at least one thermally responsive
actuator being comprised of an aluminum tube with a coaxial rod of
64FeNi coupled thereto on one end.
4. The turntable of claim 1, further comprising a covering
providing a thermally isolated interior in which the thermally
responsive actuator resides.
5. The turntable of claim 4 the covering further comprising at
least one user selectable vent.
6. The turntable of claim 1, comprising at least two thermally
responsive actuators, the actuators being linked in a manner such
that their responses to change in ambient temperature
co-operate.
7. The turntable of claim 6, the thermally responsive actuators
being comprised of at least two different materials with unequal
coefficients of thermal expansion.
8. The turntable of claim 7, at least one of the thermally
responsive actuators being comprised of an aluminum tube with a
coaxial rod of 64FeNi coupled thereto on one end.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to the field of kitchen
appliances and more particularly relates to a thermally actuated
turntable used in a conventional or convection cooking oven.
BACKGROUND OF THE INVENTION
[0002] Uniform even cooking is the goal and intention of countless
kitchen appliances and apparatuses. The recent advent of the
convection oven is an attempt to provide a more even distribution
of heat in the oven chamber by circulation of the air inside the
oven, which facilitates even cooking of the food item.
[0003] Because of the inherent uneven cooking characteristics and
short cooking times of microwave ovens, by necessity, nearly all
microwave ovens are equipped with an integrated turntable which
allows the food item to rotate through the "hot" and "cold" spots
in the oven. At present however, there are no commercially
available turntables for use in conventional cooking ovens. The
reason for this is not that conventional ovens don't have uneven
heating and cooking characteristics, but more so that a practical
and affordable solution for turntables in convection and
conventional ovens has not been invented.
[0004] Certain food items and specifically those that have short
cook time cycles such as breads, cookies and pizzas are much more
susceptible to the uneven cooking characteristics of
conventional/convection ovens. The area in the back of an oven is
typically the hottest part of the oven and the area most likely to
produce uneven cooking results. For gas ovens, the sides are
generally the hottest parts of the oven.
[0005] Because of the high temperatures that exist in conventional
ovens and the need to position food items on various rack
positions, traditional electric motor driven turntables would be
impractical and very costly to produce. Even if the electronics for
such turntables were to be located outside the cooking chamber,
providing a device that could easily be moved from one rack level
to another would be complex and cost prohibitive.
[0006] The present invention is a turntable that uses no electric
motors, cables, or other external connections and is easily moved
from one rack level to another.
SUMMARY OF THE INVENTION
[0007] In view of the foregoing challenges inherent in implanting
know types of turntables into conventional/convection ovens, this
invention provides a solution that was here-to-for not available.
As such, the present invention's general purpose is to provide a
new and improved turntable concept that utilizes the ambient heat
within the oven chamber to heat a thermo-linear motor to actuate a
mechanism which spins the turntable platter during a short duration
cooking cycle.
[0008] To accomplish these objectives a thermo-linear actuator, or
series of actuators, created by the combination of materials each
with dissimilar coefficients of thermal expansion, work together to
produce linear translation. This linear translation is then
magnified by a series of linkages and levers to ultimately actuate
a rack and pinion gear set which is attached to the shaft of the
turntable platter.
[0009] Consequently, the change in temperature of the thermo-linear
actuators from the room temperature to that of the elevated
temperatures within the oven cooking chamber will spin turntable
platter and associated food item between three and five times
during a typical cooking cycle. By means of opening and closing
certain temperature control apertures located on the side of the
device, the rate at which the platter will turn can be
adjusted.
[0010] The more important features of the invention have thus been
outlined in order that the more detailed description that follows
may be better understood and in order that the present contribution
to the art may better be appreciated. Additional features of the
invention will be described hereinafter and will form the subject
matter of the claims that follow.
[0011] Many objects of this invention will appear from the
following description and appended claims, reference being made to
the accompanying drawings forming a part of this specification
wherein like reference characters designate corresponding parts in
the several views.
[0012] Before explaining at least 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 the components set forth in the following
description or illustrated in the drawings. The invention is
capable of other embodiments and of being practiced and carried out
in various ways. Also it is to be understood that the phraseology
and terminology employed herein are for the purpose of description
and should not be regarded as limiting.
[0013] As such, those skilled in the art will appreciate that the
conception, upon which this disclosure is based, may readily be
utilized as a basis for the designing of other structures, methods
and systems for carrying out the several purposes of the present
invention. It is important, therefore, that the claims be regarded
as including such equivalent constructions insofar as they do not
depart from the spirit and scope of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] FIG. 1 is a perspective view of an outer casing for the
invention.
[0015] FIG. 2 is an exploded view of a preferred internal mechanism
for the invention.
[0016] FIG. 3 is a plan view of the internal mechanism of FIG.
2.
[0017] FIG. 4 is a plan view, in partial section, of another
preferred internal mechanism for the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0018] With reference now to the drawing, the preferred embodiment
of the ThermaSpin is herein described. It should be noted that the
articles "a", "an", and "the", as used in this specification,
include plural referents unless the content clearly dictates
otherwise.
[0019] The parts listed are given the reference numerals adjacent
their name throughout this specification: [0020] 1 Frame [0021] 2
First Lever [0022] 3 Parallel crossbar [0023] 4 Second Lever [0024]
5 Rack [0025] 6 Central Pinion Gear [0026] 7 Turntable [0027] 8
Spring [0028] 9 Turntable Support Wheel [0029] 10 Outer Push Tube
[0030] 11 Inner Push Rod [0031] 12 Cap [0032] 13 Rod joint 1 [0033]
14 Rod Support [0034] 15 Fixed Pivot Points [0035] 16 Movable Pivot
Points [0036] 17 Rocker [0037] 18 Rocker Pivot Point [0038] 19 Pass
Through Bore [0039] 20 Second Outer Push Tube [0040] 21 Second
Inner Push Rod [0041] 22 Second Cap [0042] 23 Second Rod joint
[0043] 24 Second Rod Support [0044] 25 Main Housing [0045] 26 Vent
[0046] 27 Bottom Cover
[0047] With reference to FIG. 1, the turntable's basic construction
comprises a main housing 25, surrounding a turntable platter 7,
which provides a rotating surface that is just slightly above that
of the main housing 25. The internal structure rotates the
turntable 7. One embodiment of the internal structure is shown in
FIGS. 2 and 3. A main frame 1, acts as the structural frame of the
device and is used to react the loads applied to the device by the
weight of food items loaded on the turntable platter 7 and the
reaction forces of the actuators and hinge points. In this
embodiment, a linear thermo-actuated rod provides the motivating
force to rotate the turntable 7. The rod is comprised of an outer
tube 10 and an inner rod 11 made of dissimilar materials with
different coefficients of thermal expansion (.alpha.). In this
embodiment, the inner rod 11 has a coefficient of expansion
(.alpha..sub.1) that is much smaller than the coefficient of
expansion (.alpha..sub.2) of the outer tube 10. They are joined at
one end with cap, or nut, 12 and the rod is joined to the linkage
system at rod joint 13. As the tube 10 expands with the heat, rod
11 is drawn into the tube 10 and pulls on the linkage system,
actuating it. It is of course understood that this is one
conception and embodiment of a suitable thermally responsive
actuator and others are readily conceivable. Any structure using
dissimilar materials with different coefficients of expansion such
that a change in temperature may cause a change in the overall
shape of the structure may be used. This would include bimaterial
disks, strips and springs. The preferred material structure for
this embodiment is metal as it is generally resistant to heat and
very responsive to heat changes. A highly responsive metal, such as
aluminum, cooper or brass is used for the tube 10 while a metal
with a low coefficient of expansion, like 64 FeNi (sold under the
trade name INVAR) is used for the rod 11. Any combination with
vastly dissimilar coefficients of expansion may be used. With the
preferred embodiment, INVAR has an az of 1.2 PPM/.degree. C., while
aluminum has an .alpha..sub.1 of 24 PPM/.degree. C.
[0048] The rod is supported by a fixed rod support 14. The support
14 has a bore through which the rod 11 passes while the tube 10 is
anchored on the support, which then provides the fixed point upon
which the tube 10 reacts. The thermo-actuated rod in this preferred
embodiment is connected to a first lever 2 with a fixed anchor
point 15 serving as a fulcrum. As the fulcrum is in close proximity
to the rod joint 13, it magnifies the motion of the rod 10 as it is
moved by the expanding tube. This first lever 2 is connected to a
second lever 4 by a parallel crossbar 3. Like the first lever, it
is secured to the frame with a fixed anchor point 15 that also
serves as a fulcrum. It also is positioned close to the movable
joint 16 to magnify the effect of motion. A rack 5 is then
connected to the second lever 4 and interacts with pinion gear 6 to
rotate pinion gear 6 and associated turntable 7. Turntable 7 is
also supported by a plurality of wheels 9 on the main housing 25. A
tension spring 8, keeps the rack gear 5 engaged with the pinion 6
during actuation. This spring loaded non-positive engagement method
is important to allow the rack and pinion to "skip" gears in the
event that the platter is unintentionally rotated by the user
beyond it thermally determined position and at the same time not
strip the gears and permanently damage the device.
[0049] As second embodiment, shown in FIG. 4, utilizes two
actuators of similar structure, where the second actuator comprises
a second tube 20 and rod 21, fixed together with a second cap 22.
Instead of connecting to the first lever, it connects to a rocker
17 at joint 23 and is secured by fixed anchor 24 to the frame. Both
tubes 10, 20 are further stabilized by brace 14a so as to help
maintain relative spatial relation. The first tube 10 is anchored
on the rocker 17 instead of a fixed anchor point. The rocker 17 has
a fixed anchor 18, about which it rotates and a pass-through bore
19 through which the first rod 11 passes. The combination of the
actuators and the rocker further magnifies the mechanical advantage
of the levers to move the rack gear 5. Because of the levers 3 and
5, the expansion of the tubes, measured in fractions of
millimeters, translates into several centimeters of rack movement
and serves to rotate the turntable platter 7 several times over the
course of an hour, depending upon ambient temperature and pitch of
the rack and pinion gears. The turntable is designed for cooking
food items that require less than one hour of total cooking time.
Although greater cooking times could conceivably be achieved, they
are less practical and the actual need to provide even cooking for
an item with a cooking time longer than one hour is much less
relevant to the solution provided with this invention.
[0050] The main housing may be coupled with a bottom cover 27(FIG.
2) to create an enclosed, thermally isolated system. This can
affect the transfer of heat into the system and the eventual
expansion of the actuators. Additional thermal insulation may also
be provided. A vent 26 (FIG. 1), or plurality of vents, may also be
provided to alter the rate at which heat enters the system and thus
the rate of rotation.
[0051] A number of alternative embodiments are possible. The first
alternative embodiment would be to utilize a wind-up spring as the
primary actuator. In this configuration, the center of the spring
could be attached directly to the turntable platter and potentially
produce more total rotations in a cooking cycle. The system would
need to be "throttled" to allow the platter to unwind at a
controlled rate during the entire cooking cycle.
[0052] Although the present invention has been described with
reference to preferred embodiments, numerous modifications and
variations can be made and still the result will come within the
scope of the invention. No limitation with respect to the specific
embodiments disclosed herein is intended or should be inferred.
* * * * *