Information
-
Patent Grant
-
6772752
-
Patent Number
6,772,752
-
Date Filed
Thursday, April 10, 200321 years ago
-
Date Issued
Tuesday, August 10, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Diederiks & Whitelaw, PLC
-
CPC
-
US Classifications
Field of Search
US
- 126 21 A
- 126 21 R
- 126 39 G
- 126 273 R
- 126 273 A
- 219 400
- 219 401
- 219 681
- 219 757
- 219 490
-
International Classifications
-
Abstract
A cooking appliance includes an oven cavity, one or more heat sources for generating hot oven gases within the oven cavity to perform a cooking operation, a controller and a cooling system. The cooling system includes a fan having a drive shaft upon which is mounted a multi-pole magnet. A Hall effect sensor is positioned adjacent to the magnet and provides pulses to the controller. Using the pulses, the controller calculates a speed of the cooling fan. If, during a cooking operation, the controller determines the fan is not operating, the cooking operation is halted. Likewise, if the controller determines the fan is operating at too low a speed, the cooking operation is halted. In either case, a corresponding fault code is generated and stored within the controller.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the art of cooking appliances and, more particularly, to a cooking appliance including a sensor for detecting the presence of a cooling airflow.
2. Discussion of the Prior Art
In general, providing a cooling airflow system in a cooking appliance is known. It is also known to provide a sensor or monitor to detect the presence of an airflow in the cooling system. The most common method used to detect the airflow includes providing a sail switch in an airflow path contained within the cooling system. A sail switch is actually a micro-switch having a large vane secured to a switch arm. With this arrangement, the cooling airflow impinges upon the vane, causing the switch arm to change position. This change of position provides a controller with information regarding the existence of the cooling airflow.
While this method enjoys wide use in the cooking appliance industry, sail switches are rather prone to failure. As a matter of fact, sail switches are somewhat delicate and, consequently, have multiple failure modes. For example, sail switches are subject to mechanical misalignment, shipping and other mechanical abuse and, finally, poor calibration. Each of the above examples would lead to a failure in the field. As modern appliances include a wide array of electronic components, undetected cooling system failure could result in costly damage to the appliance. Moreover, as safety standards set by regulatory and other agencies require that an oven be shut down in the event of cooling system failure, it is important to provide a monitor or sensor possessing a high degree of reliability.
Another method used to monitor for the cooling airflow includes providing a pressure sensor within the airflow path. This method primarily relates to commercial ovens where temperatures are high, the oven is operated for a prolonged period and a high pressure cooling airflow is provided to maintain cooler temperatures within control compartments of the oven. While appropriate for higher pressure airflows, such systems do not lend themselves to incorporation into residential ovens where airflows are provided at much lower pressure levels.
Therefore, despite the presence of these airflow monitoring systems in the prior art, still there exists a need for an improved airflow sensor arrangement for a cooking appliance airflow system. More specifically, there exists a need for an airflow sensor that maintains alignment and is capable of withstanding vibration and other abuses associated with shipping.
SUMMARY OF THE INVENTION
The present invention is directed to a cooling system airflow sensor provided in an oven. More specifically, the oven includes an oven cavity, a controller and a heat source for generating hot gases within the oven cavity. In addition, the oven includes a cooling system for preventing the oven gases maintained within the oven cavity from effecting the controller and, in addition, neighboring structure such as kitchen cabinetry and the like.
In accordance with a preferred form of the invention, the cooling system includes an air inlet and an air outlet separated by an air passage. Preferably, the air inlet is positioned along a control panel, with the air passage extending over the oven cavity. A cooling fan is arranged within the air passage for establishing a cooling airflow that is directed through the passage to various regions of the appliance and, ultimately expelled through the air outlet, preferably arranged in a rear portion of the appliance. More specifically, the cooling fan includes a drive shaft having secured thereto a multi-pole magnet. A Hall effect sensor is positioned in association with the multi-pole magnet for detecting a rotation of the drive shaft. The Hall effect sensor provides pulses to the controller that are translated into digital outputs used to calculate the speed of the fan.
In accordance with one aspect of the invention, if the controller determines that the cooling fan is being operated below a predetermined level, e.g. approximately 1000 RPM, the controller will assume that inadequate cooling is being provided to the appliance and terminate a current cooking operation. Once the cooking operation is terminated or cancelled, a corresponding fault code is generated by the controller for display to a user or service technician. In accordance with another aspect of the present invention, if the controller determines that the cooling fan is operating above a predetermined level, e.g., approximately 3000 RPM, the controller will assume that the fan has become detached from the drive shaft and the controller will again halt the current cooking operation, while generating and displaying a corresponding fault code.
Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of a preferred embodiment when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a perspective view of a wall oven constructed in accordance with the present invention;
FIG. 2
is an enlarged view of a control panel employed in connection with the wall oven of
FIG. 1
;
FIG. 3
is a partial cross-sectional view of the wall oven of
FIG. 1
, showing aspects of the cooling system of the invention; and
FIG. 4
is a partially exploded, perspective view of a fan assembly employed in the cooling system.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With initial reference to
FIG. 1
, a cooking appliance constructed in accordance with the present invention is generally indicated at
2
. Cooking appliance
2
, as depicted, constitutes a double wall oven. However, it should be understood that the present invention not limited to this model type and can be incorporated into various other types of oven configurations, e.g., cabinet mounted ovens, as well as both slide-in and free standing ranges. In any event, in the embodiment shown, cooking appliance
2
constitutes a dual oven wall unit including an upper oven
4
having upper oven cavity
6
and a lower oven
8
having a lower oven cavity
10
. Cooking appliance
2
includes an outer frame
12
for supporting both upper and lower oven cavities
6
and
10
.
In a manner known in the art, a door assembly
14
is provided to selectively provide access to upper oven cavity
6
. As shown, door assembly
14
includes a handle
15
at an upper portion
16
thereof. Door assembly
14
is adapted to pivot at a lower portion
18
to enable selective access to within oven cavity
6
. In a manner also known in the art, door
14
is provided with a transparent zone or window
22
for viewing the contents of oven cavity
6
while door
14
is closed. A corresponding door assembly
24
including a handle
25
and a transparent zone or window
26
is provided to selectively access lower oven cavity
10
.
As best seen in
FIG. 1
, oven cavity
6
is defined by a bottom wall
27
, an upper wall
28
, opposing side walls
30
and
31
provided with a plurality of vertically spaced side rails
32
, and a rear wall
33
. In the preferred embodiment shown, bottom wall
27
is constituted by a flat, smooth surface designed to improve the cleanability of oven cavity
6
. Arranged about bottom wall
27
of oven cavity
6
is a bake element
40
. Also, a top broiler element
42
is arranged along upper wall
28
of oven cavity
6
. Top broiler element
42
is provided to enable a consumer to perform a grilling process in upper oven
4
and to aid in pyrolytic heating during a self-clean operation. More specifically, both bake element
40
and top broiler element
42
are constituted by sheathed electric resistive heating elements.
Based on the above, in the preferred embodiment depicted, cooking appliance
2
actually constitutes an electric, dual wall oven. However, it is to be understood that cooking appliance
2
could equally operate on gas, either natural or propane. In any case, both oven cavities
6
and
10
preferably employ both radiant and convection heating techniques for cooking food items therein. To this end, rear wall
33
is shown to include a convection fan or blower
44
. Although the exact position and construction of fan
44
can readily vary in accordance with the invention, in accordance with the most preferred form of the invention, fan
44
draws in air at a central intake zone (not separately labeled) and directs the air into oven cavity
6
in a radial outward direction. Also as clearly shown in this figure, another sheathed electric heating element
46
, which preferably takes the general form of a ring, extends circumferentially about fan
44
in order to heat the radially expelled air flow. At this point, it should be noted that a fan cover, which has not been shown for the sake of clarity of the drawings, extends about fan
44
and heating element
46
, preferably with the cover having an associated central inlet and a plurality of outer radial outlet openings.
As further shown in
FIGS. 1 and 2
, cooking appliance
2
includes an upper control panel
50
having a plurality of control elements. In accordance with one embodiment, the control elements are constituted by first and second sets of oven control buttons
52
and
53
, as well as a numeric pad
54
. Control panel
50
is adapted to be used to input desired cooking parameters to cooking appliance
2
. More specifically, the first and second sets of control buttons
52
and
53
, in combination with numeric pad
54
and a display
62
, enable a user to establish particular cooking operations for upper and lower ovens
4
and
8
respectively.
In the preferred embodiment particularly shown in
FIG. 2
, first set of control buttons
52
includes a cancel button
80
, a convection button
82
, a bake button
84
, a broil button
86
, and a clean button
88
. In addition, first set of control buttons
52
also preferably includes an oven light button
90
and a button
92
used to access more cooking options which are conveyed to the user through display
62
. In a corresponding manner, second set of control buttons
52
includes a cancel button
100
, a convection button
102
, a bake button
104
, a broil button
106
, and a clean button
108
. Furthermore, second set of control buttons
53
also preferably includes an oven light button
110
and a button
112
which is used to access more cooking options that are conveyed to the user through display
62
.
To this end, display
62
is preferably divided into various sections. In accordance with the most preferred embodiment of the invention, an uppermost section of display
62
is sub-divided into three time display zones
140
-
142
. More specifically, leftmost display zone
140
constitutes a first timer zone having an associated timer button
145
. Central display zone
141
constitutes a clock for cooking appliance
2
. Rightmost display zone
142
constitutes a second timer zone having an associated timer button
148
.
Spaced below time display zones
140
-
142
are a series of vertically spaced information display zones
151
-
155
. Each of information display zones
151
,
153
and
155
has associated left and right portions (not separately labeled). As shown, each of the left and right portions have associated therewith laterally positioned selection buttons
160
-
165
. As also shown, numeric pad
54
preferably enables alpha-numeric input. That is, in addition to presenting numbers 0-9, numeric pad
54
doubles as an input source for alpha information. To this end, in a manner somewhat analogous to a telephone keypad, the number 2 button functions for ABC letter entry; the number 3 button functions for DEF letter entry; the number 4 button functions for GHI letter entry; the number 5 button functions for JKL letter entry; the number 6 button functions for MNO letter entry; the number 7 button functions for PQRS letter entry; the number 8 button functions for TUV letter entry; and the number 9 button functions for WXYZ letter entry. The number 0 button can also be used to input a space. On either side of the number 0 button are Back and Enter buttons
175
and
176
which can be used in combination with the various alpha keys for information entry. Finally, provided adjacent numeric pad
54
are Help, Favorites and Setup buttons
180
-
182
.
In general, control panel
50
is linked to a controller or CPU
200
formed as part of cooking appliance
2
. Therefore, CPU
200
receives user inputs and selections through control panel
50
, as well as signals from sensors associated with cooking appliance
2
, i.e. oven temperature sensors for upper and lower ovens
4
and
8
as generally indicated at
210
and a fan speed sensor
215
. In turn, CPU
200
controls bake element
40
, top broiler element
42
, convection fan
44
and convection heating element
46
.
Since various programming and general operation characteristics of cooking appliance
2
do not form part of the present invention, these features will not be discussed further here. Instead, the present invention is particularly directed to the operation of cooking appliance
2
based on the presence of a cooling airflow provided to maintain temperature levels of various regions of the cooking appliance within appropriate levels. More specifically, the invention is concerned with controlling the operation of cooking appliance
2
in the event the cooling air flow is absent or significantly reduced.
With main reference to
FIG. 3
, cooking appliance
2
includes a cooling system indicated generally at
225
. Cooling system
225
includes an air inlet portion
230
(
FIG. 1
) and an air outlet or exhaust portion
235
separated by an air passage
240
. More specifically, a cooling fan
260
is arranged within air passage
240
to generate an air flow within cooking appliance
2
. Actually, cooling fan
260
also serves to divide air passage
240
into an inlet section
265
and an exhaust section
266
. In any event, with this arrangement, cooling fan
260
draws in an air flow through air inlet portion
230
over electronic control elements (not separately labeled) provided within control panel
50
, directs the airflow over oven cavity
6
, and thereafter directs the airflow through an outlet
270
(
FIG. 4
) to exhaust portion
235
. Actually, as the airflow is directed over oven cavity
6
, it is simultaneously directed below cabinet or wall structure arranged above cooking appliance
2
. That is, cooling system
225
of the present invention not only provides a cooling air flow for electronic components (not separately labeled) carried by control panel
50
, but prevents hot oven gases generated within oven cavity
6
from damaging neighboring structure.
Referring to
FIG. 4
, cooling fan
260
includes a drive shaft
280
that interconnects a drive motor
285
with a fan blade
290
. In the embodiment shown, fan blade
290
is constituted by a squirrel cage type fan. However, it should be understood that a wide variety of other fan blade assemblies are equally acceptable. In accordance with the most preferred form of the invention, a multi-pole magnet
320
is mounted for rotation with drive shaft
280
which, as will be detailed more fully below, interacts with sensor
215
to monitor the speed of cooling fan
260
. Although multi-pole magnet
320
could be constituted by an 8-pole magnet, in the most preferred form, multi-pole magnet
320
is actually constituted by a 16-pole magnet. Regardless, cooling fan
260
, drive shaft
280
, drive motor
285
, fan blade
290
and sensor
215
are mounted to a fan housing
310
and supported within air passage
240
.
During operation of cooking appliance
2
, sensor
215
monitors the speed of cooling fan
260
. In further accordance with the most preferred form of the invention, sensor
215
is constituted by a Hall effect sensor which, in a manner known in the art, picks up pulses generated by multi-pole magnet
320
as drive shaft
280
rotates within sensor
215
. Sensor
215
then translates the pulses to a digital output which is directed to CPU
200
. With this arrangement, CPU
200
receives the digital output, calculates a speed of cooling fan
260
and, as will become apparent more fully below, controls the operation of cooking appliance
2
in dependence on the fan speed.
As indicated above, sensor
215
monitors the speed of cooling fan
260
. As more and more electronics are employed in modem appliances, it has become imperative to ensure that the electronics are provided with an adequate cooling supply. In the event that a cooling air flow is discontinued for whatever reason to the electronics, hot oven gases generated within cooking appliance
2
could cause these components to overheat and fail. To address this concern, CPU
200
will terminate the operation of cooking appliance
2
in the event that the speed of cooling fan
260
falls below a predetermined level. In accordance with the most preferred form of the invention, controller
200
will terminate operation of cooking appliance
2
whenever the cooling fan speed falls outside a predetermined range, e.g. below approximately 1000 RPM. However, it is also important to note that a low fan speed is not the only indication of an inadequate air flow provided within cooling system
225
. In the unlikely event that fan blade
290
disconnects from drive shaft
280
, the operation of cooling system
215
will also be detrimentally affected. Therefore, CPU
200
also functions to terminate the operation of cooking appliance
2
in the event that sensor
215
detects a cooling fan speed in excess of a predetermined range, for example, above approximately 3000 RPM. As normal operation of cooling fan
260
falls within the range of 1800-2100 RPM in accordance with a preferred embodiment of the invention, therefore a speed in excess of approximately 3000 RPM would indicate that fan blade
290
has, for some reason, become detached from drive shaft
280
causing a disruption in the airflow.
In either case, i.e. sensor
215
detecting that cooling fan
260
is operating at a speed below a first predetermined level or above a second predetermined level, CPU
200
, along with terminating the operation of appliance
2
, will generate a fault code which will be presented on display
62
. The specifics of the fault code do not form part of the present invention and are actually described in detail in commonly assigned U.S. Patent Application entitled “Diagnostic System For an Appliance” filed on even date herewith and incorporated herein by reference. In any event, it is seen that the cooling system of the present invention will provide the user with some measure of confidence that, in the event cooling fan
260
ceases functional operation, electronics of control panel
50
will be protected from overheating and ultimately leading to failure and costly repairs.
Although described with reference to a preferred embodiment of the present invention, it should be readily apparent of one of ordinary skill in the art that various changes and/or modifications can be made to the invention without departing from the spirit thereof. For instance, while the cooking appliance is described as including electrically operated heating components, the present invention is equally applicable to a gas operated cooking appliance. In addition, while the electronic components are described as being housed within the control panel, a variety of other locations are equally acceptable so long as the components are exposed to the cooling airflow. Finally, the air passage arranged above the oven cavity could extend to other regions of the cooking appliance as required by various design configurations. In general, the invention is only intended to be limited to the scope of the following claims.
Claims
- 1. A cooking appliance comprising:an oven cavity; a heating system including at least one heat source positioned to develop a heated atmosphere within the oven cavity; a control panel arranged adjacent to the oven cavity, said control panel including a plurality of control elements for inputting control parameters for a cooking operation; and a cooling system provided to establish a cooling airflow being directed, at least in part, along the control panel, said cooling system including: a cooling fan having a drive shaft operatively connected to a fan blade; a multi-pole magnet mounted for rotation with the drive shaft; a Hall effect sensor positioned proximate to the multi-pole magnet, said Hall effect sensor generating a plurality of pulses as the drive shaft rotates; and a controller linked to both the control panel so as to receive the control parameters to establish the cooking operation, and the Hall effect sensor so as to receive the plurality of pulses, wherein the controller calculates a cooling fan speed based on the plurality of pulses generated by the Hall effect sensor, with said cooling fan speed being indicative of a presence of a cooling airflow in the cooling system, said controller terminating the cooking operation when the calculated cooling fan speed is outside a predetermined range.
- 2. The cooking appliance according to claim 1, wherein the controller terminates the cooking operation if the cooling fan speed falls below approximately 1000 RPM.
- 3. The cooking appliance according to claim 2, wherein the controller terminates the cooking operation if the cooling fan speed is greater than approximately 3000 RPM.
- 4. The cooking appliance according to claim 1, wherein the controller generates a fault code indicating that the cooking operation was terminated due to the cooling fan speed being outside the predetermined range.
- 5. The cooking appliance according to claim 1, wherein the multi-pole magnet is constituted by an 8 pole magnet.
- 6. The cooking appliance according to claim 1, wherein the multi-pole magnet is constituted by a 16 pole magnet.
- 7. The cooking appliance according to claim 1, further comprising:an cooling air inlet positioned adjacent to the control panel, said cooling air inlet leading to the cooling fan.
- 8. The cooking appliance according to claim 7, further comprising:an air flow passage leading from the cooling air inlet and over the oven cavity, wherein the cooling fan is provided within the air flow passage.
- 9. The cooking appliance according to claim 1, wherein the cooking appliance constitutes a dual oven wall unit.
- 10. The cooking appliance according to claim 1, wherein the fan blade constitutes a squirrel cage.
- 11. A method of monitoring an airflow generated for cooling, at least in part, a controller for a cooking appliance comprising:initiating a cooking operation in an oven cavity of the cooking appliance; operating a cooling fan, including a drive shaft having arranged thereon a multi-pole magnet, to establish a cooling airflow; rotating the multi-pole magnetic with the drive shaft in proximity to a Hall effect sensor, with said Hall effect sensor generating a plurality of pulses; directing the plurality of pulses to the controller; calculating a speed of the cooling fan based on the plurality of pulses, with said cooling fan speed being indicative of a presence of the airflow; and terminating the cooking operation if the cooling fan speed is outside a predetermined range.
- 12. The method of claim 11, further comprising:positioning the cooling fan in an air passage; and drawing the airflow to the cooling fan through a control panel inlet opening.
- 13. The method of claim 12, further comprising:directing the airflow over the oven cavity prior to the airflow reaching the cooling fan.
- 14. The method of claim 11, wherein the cooking operation is terminated if the cooling fan speed is below a predetermined level.
- 15. The method of claim 14, wherein the cooking operation is terminated if the cooling fan speed is below approximately 1000 RPM.
- 16. The method of claim 14, further comprising:generating a fault code indicating that the cooling fan speed has fallen below the predetermined level.
- 17. The method of claim 11, wherein the cooking operation is terminated if the cooling fan speed exceeds a predetermined level.
- 18. The method of claim 17, wherein the cooking operation is terminated if the cooking fan speed is greater than approximately 3000 RPM.
- 19. The method of claim 17, further comprising:generating a fault code indicating that the cooling fan speed has exceeded the predetermined level.
- 20. The method of claim 11, further comprising:displaying a fault code on a display provided on the cooking appliance when the cooling fan speed is outside the predetermined range.
US Referenced Citations (14)
Foreign Referenced Citations (1)
Number |
Date |
Country |
4222092 |
Jan 1994 |
DE |