U.S. patent application number 16/649405 was filed with the patent office on 2020-09-24 for electric pressure canner with digital control.
This patent application is currently assigned to National Presto Industries, Inc.. The applicant listed for this patent is National Presto Industries, Inc.. Invention is credited to James A. Hedrington, Julian Warwick.
Application Number | 20200297003 16/649405 |
Document ID | / |
Family ID | 1000004900298 |
Filed Date | 2020-09-24 |
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United States Patent
Application |
20200297003 |
Kind Code |
A1 |
Hedrington; James A. ; et
al. |
September 24, 2020 |
ELECTRIC PRESSURE CANNER WITH DIGITAL CONTROL
Abstract
A digital pressure canner and related methods of operation that
provide for improved safety and consistency during a food canning
process by reducing temperature over and undershoot. The digital
pressure canner includes a digital control operating with inputs
from digital sensors to accurately control the canning temperature
during the canning process. By reducing over and undershoot of
canning temperatures, foods within the pressure canner are
maintained at temperatures sufficient to kill any bacteria or
microorganisms for the entire canning cycle. In order to verify
operation of the digital canner at sufficient canning temperatures,
mechanical safety devices, for example, a pressure relief valve can
be utilized in conjunction with digital controllers and sensors to
provide audible and visual feedback to a user during the canning
process.
Inventors: |
Hedrington; James A.;
(Chippewa Falls, WI) ; Warwick; Julian; (Jim
Falls, WI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
National Presto Industries, Inc. |
Eau Claire |
WI |
US |
|
|
Assignee: |
National Presto Industries,
Inc.
Eau Claire
WI
|
Family ID: |
1000004900298 |
Appl. No.: |
16/649405 |
Filed: |
October 15, 2018 |
PCT Filed: |
October 15, 2018 |
PCT NO: |
PCT/US2018/055851 |
371 Date: |
March 20, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62572080 |
Oct 13, 2017 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
A23L 3/015 20130101;
B65B 25/001 20130101; A23L 3/003 20130101; A23L 3/10 20130101 |
International
Class: |
A23L 3/00 20060101
A23L003/00; A23L 3/015 20060101 A23L003/015; A23L 3/10 20060101
A23L003/10; B65B 25/00 20060101 B65B025/00 |
Claims
1. A digital pressure canner, comprising: a vessel body; a lid
assembly mechanically coupled to the vessel body so as to define a
pressurized canning area; and a control circuit including a digital
sensor probe and a digital controller operably connected to a
heater assembly, wherein the digital sensor probe is exposed to the
pressurized canning area to measure a real-time internal canning
temperature, the digital sensor probe communicating the real-time
internal canning temperature to the digital controller, which
subsequently varies a power output to the heater assembly.
2. The digital pressure canner of claim 1, wherein the digital
sensor probe is mounted through the lid assembly to access the
pressurized canning area.
3. The digital pressure canner of claim 2, wherein the digital
sensor probe is mounted in a rotatable sensor mount that is
rotatably connected to the lid assembly.
4. The digital pressure of claim 3, wherein the lid assembly
further comprises a sensor channel defining a sensor bore and
wherein the rotatable sensor mount is rotatably mounted such that
rotation of the rotatable sensor mount directs the digital sensor
probe through the sensor bore.
5. The digital pressure canner of claim 4, wherein the rotatable
sensor mount further comprises a sealing member for sealably
engaging the sensor bore when the digital sensor probe is directed
through the sensor bore.
6. The digital pressure canner of claim 5, wherein the rotatable
sensor mount further comprises a latch member, said latch member
physically engaging a pair of projections on the sensor channel to
secure the rotatable sensor mount relative to the sensor channel
when the digital sensor probe is directed through the sensor
bore.
7. The digital pressure canner of claim 6, wherein the sensor
channel includes a locking pin that is elevated above the sensor
channel when the pressurized canning area is pressurized such that
the latch member cannot be disengaged from the pair of projection
when the pressurized canning area is pressurized.
8. The digital pressure canner of claim 1, wherein the lid assembly
further comprises a relief bore, said relief bore in communication
with the pressurized canning area and wherein a pressure relief
valve is mounted within the relief bore.
9. A method of canning food with a digital pressure canner,
comprising: monitoring a real-time canning temperature within a
pressurized canning area of a pressurized canning vessel using a
digital sensor probe exposed to the pressurized canning area;
communicating the real-time canning temperature to a digital
controller operably connected to the digital sensor probe; and
varying an output power supplied by the digital controller to a
heater assembly on the pressurized canning vessel such that the
real-time canning temperature is maintained at a desired canning
temperature.
10. The method of claim 9, further comprising: directing the
digital sensor probe through a lid assembly of the pressurized
canning vessel.
11. The method of claim 10, wherein the step of directing the
digital sensor probe further comprises: mounting the digital sensor
probe in a rotatable sensor mount that is rotatably connected to
the lid assembly; rotating the rotatable sensor mount relative to
the lid assembly such that the digital sensor probe is directed
through a sensor bore defined in the lid assembly.
12. The method of claim 11, wherein the rotatable sensor mount
further comprises a sensor sealing member and wherein rotating the
rotatable sensor mount further comprises: sealing the digital
sensor probe in the pressurized canning area by sealably engaging
the sensor sealing member and the sensor bore.
13. The method of claim 12, wherein the rotatable sensor mount
further comprises a latching member and wherein sealing the digital
sensor probe in the pressurized canning area further comprises:
engaging the latching member with a pair of engagement tabs on the
lid assembly.
14. The method of claim 13, wherein a locking pin is exposed to the
pressurized canning area and further comprising: lifting the
locking pin when the pressurized canning area is under pressure,
whereby the elevated locking pin prevents disengagement of the
latching member from the pair of engagement tabs.
15. The method of claim 9, wherein varying the output power
supplied by the digital controller to the heater assembly further
comprises: controlling the output power such overshoot of the
desired canning temperature by the real-time canning temperature is
reduced.
16. The method of claim 9, wherein varying the output power
supplied by the digital controller to the heater assembly further
comprises: controlling the output power such that undershoot of the
desired canning temperature by the real-time canning temperature is
reduced.
17. The method of claim 9, wherein varying the output power
supplied by the digital controller to the heater assembly further
comprises: controlling the output power such overshoot of the
desired canning temperature by the real-time canning temperature is
reduced; and controlling the output power such that undershoot of
the desired canning temperature by the real-time canning
temperature is reduced.
18. The method of claim 9, further comprising: mounting a pressure
relief valve in a relief bore in the pressurized canning vessel
such that the pressure relief valve is in communication with the
pressurized canning area of the pressurized canning vessel; and
relieving excess pressure in the pressurized canning vessel with
the pressure relief valve, said excess pressure being pressure
higher than a pressure setting of the pressure relief valve.
19. The method of claim 18, wherein controlling the output power
supplied by the digital controller reduces the excess pressure in
the pressurized canning vessel such that the real-time canning
temperature remains at or above the desired canning temperature.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of U.S.
Provisional Application No. 62/572,080, filed Oct. 13, 2017, which
is hereby incorporated herein in its entirety by reference.
TECHNICAL FIELD
[0002] The present invention is directed to pressure canner
appliances. More specifically, the present invention is directed to
a digital pressure canner appliance that uses a non-contact thermal
sensor to digitally measure internal steam temperature and control
the application of heat to the pressure canner appliance so as to
avoid large variation in internal temperature during the canning
process.
BACKGROUND
[0003] Residential canner appliances are well known and are
frequently used to prepare food recipes in jars. Canner appliances
are used to preserve food products in a jar for up to 1 year by
sterilizing the contents, removing oxygen from the food product and
jar, and sealing the jar. Traditionally, two types of canning
methods exist, water bath canning and pressure canning. Water bath
canning is the relatively lower-temperature canning process
typically used for high-acid foods including fruits and fruit
juices, jams, jellies, salsas, tomato sauces, pickled foods,
vinegars, and condiments. The high acidity of the foods kills the
bacteria and microorganisms. Pressure canning is performed at a
relatively higher temperature (240.degree. F.) and pressure, and is
used for low-acid foods including vegetables, meats, poultry, and
seafood. The high internal temperature kills the bacteria and
microorganisms. As such, the achievement and maintenance of
temperature high enough to ensure that the bacteria and
microorganisms are killed is of paramount importance.
[0004] In operation, traditional pressure canners are filled with
the jar-food to be sterilized and a small amount of water. Once the
lid has been fixedly attached to the vessel, the vessel is placed
on a heat source such as, for example, a stove top, wherein the
heat source is set at a maximum output level. As the vessel is
heated, the water begins to boil, which turns to steam and the
pressure within the vessel begins to rise. The lid can include a
mechanical pressure relief, for example, a weighted rocker or
spring-based relief valve that begins to release pressure/steam
above a desired setpoint. It is this relief of pressure, and the
corresponding rocking motion and whistling noise that indicates to
a user that the appropriate temperature and pressure has been
achieved for sterilization and timing of the canning process can
commence.
[0005] While the mechanical pressure relief performs its basic
function, it can result in a very inefficient canning process. For
instance, once satisfactory pressure is reached, there is no longer
the necessity for the heat source to be set at the maximum level.
However, the user has no reliable control feedback regarding the
heat source other than the motion, noise and steam associated with
the rocker and spring-based relief valves. In some instances, the
noise may be so significant that the user reduces the heat source
so much that the relief valves are no longer venting, which is an
indication that pressure is no longer satisfactory and a
potentially dangerous canning situation is occurring.
[0006] While prior digital canner appliances exist that are capable
of water bath canning, the National Center for Home Food
Preservation (funded by the USDA) has warned against using digital
canner appliances for pressure canning. The main concern with
digital pressure canner appliances regards the temperature for the
preservation and sterilization of the food product. The temperature
in prior digital pressure canner appliances tends to fluctuate due
to the mounting location of the heat sensor. Typically, the heat
sensor is located on a canner floor or bottom and measures the
temperature of the canner material as opposed to an internal steam
temperature within the pressure canner. As the canner material
functions as a large heat sink, the heat sensor is not exposed to
real-time temperature conditions within the pressure canner and to
which the food is actually exposed. As such, the temperature sensed
by the heat sensor will always be lagging or leading with respect
to the internal temperature conditions resulting in a heating
element not being operated in the most efficient and desirable
fashion. As such, large under and overshoots can be experienced
with respect to internal canner temperature, which can potentially
allow bacteria and microorganisms to survive the canning process
and lead to food spoilage.
[0007] As such, it would be advantageous to have a digital pressure
canner appliance that is able to sense steam temperature in a
real-time environment so as to ensure effective and safe pressure
canning of food products.
SUMMARY
[0008] A digital pressure canner of the present invention can
provide for improved safety and consistency by reducing over and
undershoot with respect to temperature control for a canning
process. By reducing over and undershoot of internal canning
temperatures, foods within the pressure canner are consistently
maintained at the temperatures necessary to kill any bacteria or
microorganisms throughout the entire canning cycle. Embodiments of
the digital pressure canner include a temperature sensor adapted to
measure an internal steam temperature within the pressure canner
itself and to communicate the internal steam temperature in
real-time to a temperature control. By measuring internal steam
temperature in real-time, the temperature control is able to
control a heating element in conjunction with actual conditions
inside the pressure canner and avoid temperature over and
undershoot within the pressure canner. In some embodiments,
mechanical safety device, for example, a pressure relief valve can
be utilized in conjunction with digital controllers and sensors to
provide audible or physical indications that sufficient canning
temperatures have been achieved.
[0009] In one aspect, the present invention is directed to a
pressure canner that utilizes a digital controller and a digital
sensor to reduce temperature over and undershoot during a canning
cycle. The digital sensor is configured such that a sensing element
is exposed to an interior canning environment within the pressure
canner such that real-time steam temperature is communicated to the
digital controller.
[0010] In another aspect, the present invention is directed to a
method of canning food wherein a canning temperature is controlled
with a digital controller and related digital sensors so as to
reduce any temperature over or undershoot during a canning cycle.
The method can comprise positioning a sensing element within an
interior canning volume of a pressure canner such that real-time
steam temperatures are communicated to the digital controller for
selectively operating a heating element.
[0011] The above summary is not intended to describe each
illustrated embodiment or every implementation of the subject
matter hereof. The figures and the detailed description that follow
more particularly exemplify various embodiments.
[0012] The above summary is not intended to describe each
illustrated embodiment or every implementation of the subject
matter hereof. The figures and the detailed description that follow
more particularly exemplify various embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Subject matter hereof may be more completely understood in
consideration of the following detailed description of various
embodiments in connection with the accompanying figures, in
which:
[0014] FIG. 1 is a front view of a pressure canner according to a
representative embodiment of the present invention.
[0015] FIG. 2 is a top view of the pressure canner of FIG. 1.
[0016] FIG. 3 is a top view of the pressure canner of FIG. 1.
[0017] FIG. 4 is a side view of the pressure canner of FIG. 1.
[0018] FIG. 5 is a section view of the pressure canner of FIG. 1
taken at line B-B of FIG. 4.
[0019] FIG. 6 is a detailed top, perspective view of the pressure
canner of FIG. 1.
[0020] FIG. 7 is an exploded, top perspective view of the pressure
canner of FIG. 1.
[0021] FIG. 8 is a schematic illustration of an operations circuit
of the pressure canner of FIG. 1.
[0022] While various embodiments are amenable to various
modifications and alternative forms, specifics thereof have been
shown by way of example in the drawings and will be described in
detail. It should be understood, however, that the intention is not
to limit the claimed inventions to the particular embodiments
described. On the contrary, the intention is to cover all
modifications, equivalents, and alternatives falling within the
spirit and scope of the subject matter as defined by the
claims.
DETAILED DESCRIPTION OF THE DRAWINGS
[0023] A representative embodiment of a pressure canner 100 of the
present invention is illustrated within FIGS. 1-4 and 7. Generally,
pressure canner 100 comprises a lid assembly 102 and a vessel body
104. Though not illustrated in FIG. 1, it will be understood by one
of ordinary skill in the art that lid assembly 102 and vessel body
104 can be operably locked together with conventional interlock
features to form a vessel capable of safely operating at internal
pressures exceeding at least 10 psig. For example, lid assembly 102
and vessel body 104 can make use of a plurality of recesses 103 and
tabs 105 that cooperate to allow the lid assembly 102 to be placed
onto the vessel body 104 and rotated into a captured or locked
position as commonly found in conventional pressure canner designs.
Pressure canner 100 is generally fabricated of materials suitable
for repeated exposure to elevated temperatures and pressure and
that can be cleaned and sanitized with conventional cleaning
materials.
[0024] As illustrated in FIGS. 1-7, vessel body 104 is generally
defined by an internal pressure vessel 106 and an external shell
108. Internal pressure vessel 106 defines an upper opening 110, an
inner sidewall 112 and a vessel floor 114. External shell 108
includes a pair of opposed handles 116a, 116b. Opposed handle 116b
can include a rotating sensor mount 118. Rotating sensor mount 118
can comprise a mount body 120 defined by an upper mounting surface
122 and a lower mounting surface 124. The lower mounting surface
124 can define a sensor mounting bore 126 that is surrounded by a
lower sealing member 128. A digital pressure sensor 130 can be
mounted within the sensor mounting bore 126 such that a sensor
probe 132 extends outward and away from the lower mounting surface
124. The digital pressure sensor 130 can comprise a sensor wire
(not shown) that extends outward of the mount body 120. Upper
mounting surface 122 can comprise a latch member 136 rotatably
coupled to the upper mounting surface 122. Latch member 136 can
comprise an elongated latch body 138 having a pair of latch ends
140a, 140b.
[0025] Referring again to FIGS. 1-7, lid assembly 102, generally
comprises an upper cover surface 150 including an upper mount
member 152. Upper surface 150 generally defines a lid perimeter 154
such that the lid assembly 102 can sealably coupled to the internal
pressure vessel 106, and thereby allow for the operation of
pressure canner 100 above atmospheric pressure through the
interaction of recesses 103 and tabs 105. Upper surface 150 can
include a relief bore 156 and a sensor bore 158. Upper mount member
152 generally extends across the upper surface 150 and can comprise
a lid handle member 160. Upper surface 150 can further include a
relief aperture 162 in communication with the relief bore 156 and
wherein the relief aperture 162 further define a relief mounting
surface 164. In addition, upper mount member 152 can define a
sensor channel 166 such that the sensor bore 158 is exposed and
accessible. Proximate the sensor channel 166 is a pair of
projections 167a, 167b on either side of the sensor channel 166
with each projection 167a, 167b configured to receive the
corresponding latch end 140a, 140b. Sensor channel 166 can further
comprise a locking pin 169 located proximate the projections 167a,
167b. Locking pin 169 generally comprises an elongated member 171
that sealably extends through a pin aperture 175 through the upper
cover surface 150 and terminates at a bottom pin surface 173. Lid
assembly 102 can further include a pressure relief valve 168 which
is operably coupled to the relief mounting surface 164 such that
the pressure relief valve 168 is in communication with the internal
pressure vessel 106 through the relief bore 156 and relief aperture
162 when the lid assembly 102 is operatively coupled to the vessel
body 104.
[0026] Pressure canner 100 further comprises an operations circuit
shown schematically in FIG. 8. The operations circuit generally
comprises a power source 182, a digital controller 184 and a
heating element 186. Power source 182 generally comprises a
standard cord and plug assembly for electrically connecting the
pressure canner 100 to a standard electrical outlet. With power
source 182 connected to an electrical outlet, digital controller
184 can be turned on and begin providing control of the heating
element 186. Generally, digital controller 184 will include a
number of stored programs or "recipes" that correspond to certain
foods to be pressure canned. These programs or recipes can include
desired temperatures and times necessary to safely and successfully
can various food types. In some instances, pressure canner 100 can
further comprise a display element and/or buttons, whereby a user
can interface with the digital controller 184 to select food types
to be canned or to alternatively, operate the pressure canner 100
manually.
[0027] In operation, a jar, for example, a mason jar 188 filled
with food to be canned is placed on the vessel floor 114 within the
vessel body 104 as shown in FIG. 7. The lid assembly 102 is
securely coupled to the vessel body 104 to define an interior
pressurized canning area 190 as shown in FIGS. 5 and 7. With the
lid assembly 102 secured over the upper opening 110 with recesses
103 and tabs 105, the mount body 120 of the rotating sensor mount
118 can be rotated such that the mount body 120 is positioned
within the sensor channel 166 as shown in FIGS. 3-6. With the lower
mounting surface 124 positioned proximate the upper cover surface
150, the sensor probe 132 is directed into and through the sensor
bore 158 such that the sensor probe 132 is exposed to the inner
pressure vessel 106 and the interior pressurized canning area 190
specifically. Latch member 136 can be rotated such that the latch
ends 140a, 140b securely engage the projections 167a, 167b and
lower sealing member 128 can engage and seal the sensor bore 158 as
shown in FIGS. 3 and 6. Preferably, the sensor probe 132 is exposed
to the interior pressurized canning area 190 defined within the
inner pressure vessel 106 in a non-contact manner, wherein the
sensor probe 132 is not in physical contact with the material that
comprises the inner pressure vessel 106 or lid assembly 102 such
that any heat sink impact of these materials is avoided and to
eliminate leading or lagging temperature readings as found in
conventional canners.
[0028] With the pressure canner 100 assembled and the mason jar 188
positioned within the interior pressurized canning area 190,
digital controller 184 will receive manual or "recipe" instructions
requesting operation at a desired temperature and pressure.
Generally, the digital controller 184 will allow power to the
heating element 186, whereby the internal temperature will begin to
rise in the internal pressure vessel 106 and the interior
pressurized canning area 190. The steam temperature and pressure
within the internal pressure vessel 106 and the interior
pressurized canning area 190 will be sensed by the sensor probe 132
that is in communication with the interior of the interior pressure
vessel 106 through its positioning through the sensor bore 158. As
the sensor probe 132 is sensing and communicating the
real-temperature conditions within the interior pressurized canning
area 190 to the digital controller 184, the typical temperature
over and undershoot that is experienced with measuring temperature
on a canner floor or surface and the corresponding lag with respect
to real time conditions is avoided. By avoiding the initial
temperature overshoot during initial heating, the digital
controller 184 also avoids the subsequent temperature "undershoot"
that occurs when a conventionally located temperature senor finally
transmits a temperature to the controller that the temperature
setpoint has been achieved. Through the exposure of the sensor
probe 132 to the actual steam temperature within the interior
pressure vessel 106 and the interior pressurized canning area 190
specifically and the corresponding real-time measurements provided
to the digital controller 184, the desired and targeted temperature
setpoint is maintained without the cyclic overshoot/undershoot of
conventional pressure canners utilizing conventional temperature
measurement of canner surfaces. As such, the food being canned
within the pressure canner 100 is maintained at the necessary
temperature for sufficient periods to kill any bacteria and
microorganisms. Furthermore, the digital controller 184 can
maintain sufficient temperature such that the pressure relief valve
168 is either not venting or only minimally venting so as to
indicate more efficient operation of the pressure canner 100
throughout the canning process.
[0029] During canning, the pressure experienced within the internal
pressure vessel 106 biases the bottom pin surface 173 such that the
elongated member 171 is lifted and the locking pin 169 is exposed
in the sensor channel 166 as shown in FIG. 6. With the locking pin
169 lifted and physically elevated above the surface of the sensor
channel 166, rotation of the latch member 136 is prevented as the
latch ends 140a, 140b physically contact the locking pin 169. As
such, the locking pin 169 ensures that the latch ends 140a, 140b
remain securely engaged with the projections 167a, 167b and
rotating sensor mount 118 is retained such that the sensor probe
132 remains within and exposed to the interior pressurized canning
area 190 during canning. Only when pressure has been removed, for
example, by venting the interior pressurized canning area 190, does
the elongated member 171 drop down such that the locking pin 169 is
below the sensor channel 166 and the latch member 136 can be
rotated to unlock the rotating sensor mount 118.
[0030] Various embodiments of systems, devices, and methods have
been described herein. These embodiments are given only by way of
example and are not intended to limit the scope of the claimed
inventions. It should be appreciated, moreover, that the various
features of the embodiments that have been described may be
combined in various ways to produce numerous additional
embodiments. Moreover, while various materials, dimensions, shapes,
configurations and locations, etc. have been described for use with
disclosed embodiments, others besides those disclosed may be
utilized without exceeding the scope of the claimed inventions.
[0031] Persons of ordinary skill in the relevant arts will
recognize that the subject matter hereof may comprise fewer
features than illustrated in any individual embodiment described
above. The embodiments described herein are not meant to be an
exhaustive presentation of the ways in which the various features
of the subject matter hereof may be combined. Accordingly, the
embodiments are not mutually exclusive combinations of features;
rather, the various embodiments can comprise a combination of
different individual features selected from different individual
embodiments, as understood by persons of ordinary skill in the art.
Moreover, elements described with respect to one embodiment can be
implemented in other embodiments even when not described in such
embodiments unless otherwise noted.
[0032] Although a dependent claim may refer in the claims to a
specific combination with one or more other claims, other
embodiments can also include a combination of the dependent claim
with the subject matter of each other dependent claim or a
combination of one or more features with other dependent or
independent claims. Such combinations are proposed herein unless it
is stated that a specific combination is not intended.
[0033] Any incorporation by reference of documents above is limited
such that no subject matter is incorporated that is contrary to the
explicit disclosure herein. Any incorporation by reference of
documents above is further limited such that no claims included in
the documents are incorporated by reference herein. Any
incorporation by reference of documents above is yet further
limited such that any definitions provided in the documents are not
incorporated by reference herein unless expressly included
herein.
* * * * *