U.S. patent application number 12/087971 was filed with the patent office on 2008-12-25 for cooking appliance, especially top-mounted cooking appliance, and method for controlling a cooking appliance.
This patent application is currently assigned to BSH BOSCH UND SIEMENS HAUSGERAETE GMBH. Invention is credited to Ingo Bally, Alexander Dinkel, Kerstin Feldmann, Wolfgang Fuchs, Martin Keller, Angelika Namberger, Maximilian Neuhauser, Klemens Roch, Wolfgang Schnell, Guenter Zschau.
Application Number | 20080314374 12/087971 |
Document ID | / |
Family ID | 38059105 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080314374 |
Kind Code |
A1 |
Bally; Ingo ; et
al. |
December 25, 2008 |
Cooking Appliance, Especially Top-Mounted Cooking Appliance, and
Method for Controlling a Cooking Appliance
Abstract
A cooking appliance, especially a top-mounted cooking appliance
including a muffle that defines a cooking space and is provided
with a muffle access opening; a door pivotably mounted to the
muffle for movement into and our of a covering relation with the
access opening; a driving device in operative engagement with the
door; a control device operatively associate with the driving
device for controlling door movement; and an arrangement for
determining a door displacement parameter during door movement,
wherein a determined door displacement parameter is used as a
reference parameter for a function of the appliance.
Inventors: |
Bally; Ingo; (Traunstein,
DE) ; Dinkel; Alexander; (Unterwoessen, DE) ;
Feldmann; Kerstin; (Bretten, DE) ; Fuchs;
Wolfgang; (Altenmarkt a.d. Alz, DE) ; Keller;
Martin; (Traunreut, DE) ; Namberger; Angelika;
(Altenmarkt a.d. Alz, DE) ; Neuhauser; Maximilian;
(Chieming/Egerer, DE) ; Roch; Klemens; (Trostberg,
DE) ; Schnell; Wolfgang; (Trostberg, DE) ;
Zschau; Guenter; (Traunwalchen, DE) |
Correspondence
Address: |
BSH HOME APPLIANCES CORPORATION;INTELLECTUAL PROPERTY DEPARTMENT
100 BOSCH BOULEVARD
NEW BERN
NC
28562
US
|
Assignee: |
BSH BOSCH UND SIEMENS HAUSGERAETE
GMBH
MUNICH
DE
|
Family ID: |
38059105 |
Appl. No.: |
12/087971 |
Filed: |
December 22, 2006 |
PCT Filed: |
December 22, 2006 |
PCT NO: |
PCT/EP2006/070167 |
371 Date: |
July 18, 2008 |
Current U.S.
Class: |
126/1R |
Current CPC
Class: |
F24C 15/027 20130101;
F24C 7/08 20130101 |
Class at
Publication: |
126/1.R |
International
Class: |
F24C 15/02 20060101
F24C015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 31, 2006 |
DE |
102006004381.2 |
Claims
1-12. (canceled)
13. A cooking appliance, especially a top-mounted cooking
appliance, comprising: a muffle that defines a cooking space and is
formed with a muffle access opening; a door pivotably mounted to
the muffle for movement into and out of a covering relation with
the access opening; a driving device in operative engagement with
the door; a control device operatively associated with the driving
device for controlling door movement; and means for determining a
door displacement parameter during door movement wherein a
determined door displacement parameter is used as a reference
parameter for a function of the appliance.
14. The cooking appliance according to claim 13 and further
comprising means for using the reference parameter to generate a
trigger signal in the control device to initiate action by the
driving device with respect to door movement.
15. The method according to claim 13 and further comprising means
for using the reference parameter as a criterion in subsequent
displacement movements of the door.
16. The cooking appliance according to claim 13 and further
comprising means for determining a reference speed of door movement
from a displacement speed, wherein the reference speed is defined
as the reference parameter.
17. The cooking appliance according to claim 16 wherein the
reference parameter is determined after a substantially constant
displacement speed has been reached by the door.
18. The cooking appliance according to claim 16 wherein the
reference parameter is determined after a substantially constant
door acceleration has been reached.
19. The cooking appliance according to claim 13 wherein the
determination of the reference parameter is defined over an entire
door displacement path.
20. The cooking appliance according to claim 13 wherein a jammed
state is defined dependent upon the determined reference
parameter.
21. A method for operating a cooking appliance, especially a
top-mounted cooking appliance, comprising the steps of: providing a
cooking appliance having a muffle that defines a cooking space and
is provided with a muffle access opening; a door pivotably mounted
to the muffle for movement into and out of a covering relation with
the access opening; a driving device in operative engagement with
the door; providing a control device operatively associated with
the driving device for controlling door movement; providing means
for determining a door displacement parameter during door movement
operatively associated with the control device; determining a
parameter dependant on door displacement the determination
occurring during door displacement; and using the determined
parameter as a reference parameter for a function of the appliance,
in particular an anti-jamming function.
22. The method according to claim 21 wherein the step of
determining the reference parameter includes holding at least one
switch closed, the switch being operatively associated with the
door.
23. The method according to claim 22 and further comprising the
step of aborting the determination step upon early release of the
at least one switch.
24. The method according to claim 22 wherein in the determination
step, the at least one switch is opened prior to determining the
reference value and automatic operation on the basis of the
reference parameter is not permitted, in particular no displacement
operation of the door is possible.
Description
[0001] The invention relates to a cooking appliance, particularly a
top-mounted cooking appliance, comprising at least a muffle that
delimits a cooking space, and is provided with a muffle hole, a
door for closing the muffle hole and a driving device which is
controlled by a control device and is used for displacing the
door.
[0002] A top-mounted cooking appliance is known from DE 102 28 140
A1 in which the jamming of objects by the bottom door may be
detected by a plurality of anti-jamming switches that may be
actuated independently of one another and are located between the
bottom door and the muffle frame. In addition, any pressure
increase may be evaluated in a door seal with a hollow
cross-section.
[0003] In DE 101 64 239 A1, an anti-jamming mechanism is described
which is triggered by varying tensile forces on the traction cables
driving the bottom door. A torque sensor is also described, which
registers a load moment on the drive shaft of an electric motor.
Tensile force sensors, piezoelectric sensors and deformation or
tension/expansion sensors are listed as sensors for this
purpose.
[0004] DE 102 88 141 A1 also describes an optoelectronic sensor for
detecting a jam, which is activated by the quantity of reflected
light.
[0005] The disadvantage of the described jam detectors is that they
are either relatively slow (tensile force sensors), or imprecise
and prone to error (optical force sensors) and, furthermore,
require increased installation costs.
[0006] The main disadvantage is that the function for detecting a
jammed object does not work reliably, if at all, if there is a
variation in the internal parameters of the cooking appliance
itself or in external factors. For example, a heavy load on the
door may mean that a preset displacement speed cannot be achieved,
or can only be achieved after a delay. Furthermore, using the
cooking appliance in an area where the voltage fluctuates between
too high and too low may result in short-term deviations. Finally,
the effects of aging on the drive for the door or on guide rails
may mean that an originally preset displacement speed can no longer
be reached.
[0007] Another disadvantage is a triggering of a closing process
for the door, in which--shortly before the closed state is
reached--there is a changeover from an anti-jamming mechanism in
which a switch or a function is used for detecting a jammed state,
to a closing mechanism for registering a closed state.
[0008] The object of the invention is, therefore, to provide rapid,
simple and precise adjustment of the cooking appliance to variable
operating conditions, and--preferably--a displacement speed
detector for a cooking appliance of the type described above.
[0009] This object is achieved by the cooking appliance having the
features described in claim 1 and by a method according to claim
9.
[0010] Thus a cooking appliance is preferred, particularly a
top-mounted cooking appliance, comprising at least a muffle that
delimits a cooking space, and is provided with a muffle hole, a
door for closing the muffle hole and a driving device which is
controlled by a control device and is used for displacing the door,
wherein--during a displacement of the door--a parameter that is
dependent upon said displacement of the door is detected and
wherein the detected parameter is used as the reference parameter
for a function of the appliance.
[0011] In this way the cooking appliance and its functionalities
may be advantageously adjusted to local or current operating
conditions. This would enable environmental influences, as well as
a non-standard operating voltage or a varying load on the door, to
be taken into account as external operating conditions. Internal
operating conditions that may be taken into account include, for
example, effects of aging of the cooking appliance itself, for
example an aging drive motor or wear on guide rails for
displacement of the door, so that even gradual changes such as the
effects of friction may be taken into account.
[0012] The reference parameter is thus advantageously always
approximated as closely as possible to an actual target value. As
well as a speed-dependent reference parameter being taken into
account, the latter may also be determined on the basis of other
variable factors such as a motor current.
[0013] The reference parameter may subsequently be used as a
criterion for the triggering of a function in the same displacement
movement of the door. This advantageously enables a respective
adjustment in particular of the displacement speed and--for
example--of an anti-jamming mechanism, so that, for example, a
varying load on the door may be taken into account individually for
the respective displacement cycle.
[0014] The reference parameter may also subsequently be used as a
criterion in subsequent displacement movements of the door. The
settings for basic parameters or for basic parameter ranges can
thereby advantageously be defined when the cooking appliance is
commissioned for the first time, or at periodic intervals during
maintenance activities. In addition to the initial memorization of
functions, this also enables the parameters thus defined to be
adjusted from time to time so that even gradual changes, for
example elevation speed, can be taken into account on the basis of
changing frictional conditions.
[0015] A reference speed determined from a displacement speed may
be defined as the reference parameter. The reference parameter is
preferably determined for this purpose after a constant
displacement speed has been reached. This enables the parameter to
be determined reliably during an initial acceleration phase without
load-dependent acceleration effects. The reference parameter may
also be determined, however, after a constant acceleration has been
achieved. This enables the parameter to be set at particularly
early stage, so that it may be used particularly advantageously for
the current displacement movement.
[0016] The determination of the reference parameter is
alternatively defined over the entire displacement path or part
thereof, e.g. it is initially determined and then subsequently
adjusted to favorable effect. Such an approach offers the advantage
of, for example, enabling frictional effects from lifting rails and
similar to be detected especially accurately and to be taken into
account.
[0017] A jammed state may therefore advantageously be determined
dependent upon the defined reference parameter. This ensures the
correct functioning of safety-related functions, such as the
detection of a jammed state even in variable environmental
conditions, for example where the operating voltage is too high or
too low, resulting in fluctuations in displacement speed.
[0018] The reference parameter is determined preferably by keeping
a button pressed down, or--in particular--two buttons (e.g.
displacement buttons) to be operated with both hands. If the
buttons are released early, the process to determine the reference
parameter is preferably aborted. Such a procedure is useful since,
if the process is aborted early due to the release of the
displacement buttons or other buttons, this prevents a reference
parameter value being determined on the basis of an erroneous
displacement process. Automatic operation on the basis of the
parameter or reference parameter to be determined, e.g. an
automatic displacement operation, is then conveniently not
possible.
[0019] For this purpose, the cooking appliance--which is, in
particular, a top-mounted cooking appliance but may also be a
cooking appliance with an oven carriage--is equipped with a speed
measurement device for determining a displacement speed of the
door. The speed measurement device enables an object jammed by the
door to be detected by monitoring of the displacement speed,
wherein the displacement movement does not need to be
speed-controlled, but may--for example--also be governed on a
load-dependent basis via the motor voltage or motor current. The
displacement movement of the door is, however, advantageously also
controlled on a speed-dependent--and therefore also
load-dependent--basis, e.g. via a central control unit.
[0020] It is particularly advantageous, for the closure case, if at
least one end switch is available in addition, said end switch
being disposed between muffle hole and/or frame, and door, wherein
any activation of at least one end switch deactivates the
anti-jamming device or a first type of anti-jamming mechanism, and
thus terminates protective measures. This end switch preferably
activates with an degree of opening of less than one centimeter, in
particular in a range of 4-9 mm, which is so small that no normal
household objects could become jammed. If at least one end switch
is activated the door is pushed with defined force--and no longer
with controlled speed--onto the muffle hole. Nevertheless, it is
advantageously guaranteed that the door is not unintentionally
reversed on closing, but can still be reversed if an object should
become jammed in the final phase of closing.
[0021] In particular, the non-abrupt, premature stopping of the
closure movement would indicate that a child's finger has become
jammed, in which case the door is immediately opened again,
particularly to a degree sufficient to allow the finger to be
withdrawn. Such non-abrupt, premature stopping of the closure
movement may be detected with particular reliability by the
monitoring of a speed differential value.
[0022] However, in order to prevent even smaller objects, or--in
particular--a child's finger, from becoming jammed, it is
preferable for a switchover to a modified safety feature to be
provided instead of complete deactivation.
[0023] The advantage of this speed-supported anti-jamming device is
that is responds relatively quickly, can hold accurate input date,
and may be implemented relatively easily without major design
measures.
[0024] The monitoring of the displacement speed can be focused on a
reduction in the displacement speed, which is uncontrolled and
therefore cannot be deliberately regulated. This may occur in that
a value measured by the speed measurement device deviates from a
target value by a fixed or percentage value. If the deviation is
above or below a defined threshold value, a jam is assumed to have
occurred. For example, if the door can no longer be displaced with
the set target speed because an object is preventing it from doing
so, then its speed is reduced accordingly. This evaluation and
monitoring may be carried out--for example--in a central control
device, e.g. via suitable microcontrollers.
[0025] Alternatively, or additionally, a timing-related change in
the displacement speed--especially too rapid a change--may trigger
a jam situation, if--for example--the door slows down more quickly
than provided for, in the event of a jam.
[0026] The values are, of course, selected such that jam situations
are not triggered by speed fluctuations caused by the normal
process for the displacement of the door. In addition, the
anti-jamming methods described in the prior art, such as motor
current measurement, may also be used.
[0027] It is advantageous for the speed measurement device to
comprise at least one sensor on a motor shaft of the drive
mechanism, in particular a drive motor, by which corresponding
sensor signals can be generated upon rotation of said motor shaft.
This facilitates a relatively rapid response. The sensor signals
are directly or indirectly a measure of the displacement speed of
the door. It is then particularly beneficial if at least one sensor
is a Hall sensor which emits two sensor signals per motor shaft
rotation. The Hall sensor system is easy to install, fast and
non-sensitive. Two (partial) Hall elements are advantageously
attached to the motor shaft, so that two signals are emitted for
each rotation of the motor shaft. Evaluation of the timing of these
signals enables a speed to be determined for the bottom door, for
example via comparison tables or by conversion to real time. The
displacement speed is preferably detected by a time differential
between the sensor signals.
[0028] In order to determine a stable speed it is advantageous for
several, i.e. more than two, sensor signals to be evaluated. To
this end it is also advantageous if several, i.e. more than two,
sensor signals, are emitted.
[0029] It is particularly advantageous if the displacement
direction of the door is reversed once the jam has been
detected.
[0030] For this purpose an anti-jamming device may be provided
which monitors for jam situations and/or implements any measures to
be carried out in the event of a jam. The anti-jamming device may
be a separate device or functionally integrated into existing
control circuits, e.g. into the central control circuit or into a
control board or lift board.
[0031] It is preferable for the anti-jamming system or the
anti-jamming device to be activatable only if a target displacement
value, in particular a target speed, is reached by the door. This
minimizes the risk of the anti-jamming mechanism being triggered
incorrectly.
[0032] In order to protect the object jammed by the door, it is
advantageous if a maximum force-time curve is not exceeded by the
door. Jammed "by" the door may mean jammed between the door and an
outer limit, e.g. the work surface, or jammed between door and
muffle frame or housing. Different force-time curves may be
provided for each case.
[0033] It is particularly advantageous, for the closure case, if at
least one end switch is available in addition, which is disposed in
the area between muffle hole or frame and door, wherein any
activation of at least one end switch deactivates the anti-jamming
device or anti-jamming mechanism, i.e. interrupts protective
measures. This end switch typically activates with a degree of
opening of 4-9 mm, which is so small that no objects could still be
jammed. On the other hand, this guarantees that the door is not
unintentionally reversed on closing. If the at least one end switch
is activated, the door is pushed with defined force--and no longer
with controlled speed--onto the muffle hole.
[0034] The speed measurement device may, however, also be used for
other purposes, such as setting the displacement speed of the door.
This alone is not yet known and also is not obvious.
[0035] The invention is particularly suitable for top-mounted
cooking appliances in which the muffle hole is at the bottom and
the door is a bottom door, which preferably moves in linear
fashion.
[0036] The invention is described in greater detail below on the
basis of the attached schematic diagrams, in which:
[0037] FIG. 1 shows a perspective view of a wall-mounted,
top-mounted cooking appliance with bottom door lowered;
[0038] FIG. 2 shows a perspective view of the top-mounted cooking
appliance with bottom door closed;
[0039] FIG. 3 shows a perspective view of a housing of the
top-mounted cooking appliance without the bottom door;
[0040] FIG. 4 shows a schematic side view in cross-section along
the line I-I from FIG. 1 of the wall-mounted, top-mounted cooking
appliance with bottom door lowered;
[0041] FIG. 5 shows the front view of a further embodiment of a
top-mounted cooking appliance;
[0042] FIGS. 6 to 11 are diagrams of displacement movements of a
bottom door under various basic conditions;
[0043] FIGS. 12 and 13 are force-time profile curves for a bottom
door; and
[0044] FIG. 14 is a diagram of a preferred displacement movement
when a thin object is jammed between a bottom door and a
muffle.
[0045] FIG. 1 shows a top-mounted cooking appliance with a housing
1. The rear side of the housing 1 is attached to a wall 2 in the
manner of a hanging cupboard. A cooking space 3 is delimited in the
housing 1, which may be monitored through a viewing window 4 set
into the front face of the housing 1. FIG. 4 shows that the cooking
space 3 is delimited by a muffle 5, which is provided with a
heat-insulating sheathing (not illustrated), and that the muffle 5
has a muffle hole 6 in the bottom surface. The muffle hole 6 can be
closed with a bottom door 7. In FIG. 1 the bottom door 7 is shown
in a lowered state, wherein it lies with its underside on a work
surface 8 of a kitchen appliance. In order to close the cooking
space 3, the bottom door 7 must be adjusted to the position shown
in FIG. 2, known as the "zero position". For the purpose of
adjusting the bottom door 7 the top-mounted cooking appliance has a
drive mechanism 9, 10. The drive mechanism 9, 10 has a drive motor
9, shown by dashed lines in FIGS. 1, 2 and 4, which is disposed
between the muffle 5 and an outer wall of the housing 1. The drive
motor 9 is disposed in the area of the rear face of the housing 1,
and--as shown in FIG. 1 or 4--is effectively connected to a pair of
lifting elements 10, which are connected to the bottom door 7.
According to the schematic lateral view from FIG. 4 each lifting
element 10 is designed as an L-shaped carrier, whereof the
horizontal legs extend out from the drive motor 9 on the housing
side. In order to adjust the bottom door 7 the drive motor 9 may be
activated with the help of an operating panel 12 und and a control
circuit 13, which are disposed on the front surface of the bottom
door 7 in accordance with FIGS. 1 and 2. As shown in FIG. 4, the
control circuit 13 is located behind the operating panel 12 inside
the bottom door 7. The control circuit 13, which is assembled in
this case from several spatially and functionally separate PCBs
that communicate via a communication bus, is a central control unit
for operating the appliance and controls and/or regulates functions
such as heating up, displacement of the bottom door 3,
implementation of user inputs, illumination, an anti-jamming
mechanism, timing of the heating elements 16, 17, 18, 22, and much
more.
[0046] FIG. 1 indicates that an upper surface of the bottom door 7
has a cooking hob 15. Almost the entire surface of the cooking hob
15 is occupied by heating elements 16, 17, 18, which are shown in
FIG. 1 by dashed lines. In FIG. 1 the heating elements 16, 17 are
two separate cooking zone heating elements of different sizes,
whilst the heating element 18 is a flat heating element provided
between the two cooking zone heating elements 16, 17 that virtually
surrounds the cooking zone heating elements 16, 17. The cooking
zone heating elements 16, 17 define relevant cooking zones or hobs
for the user; the cooking zone heating elements 16, 17 together
with the flat heating element 18, define an under-surface heating
zone. The zones may be indicated by an appropriate decor on the
upper surface. The heating elements 16, 17, 18 can each be
controlled via the control circuit 13.
[0047] In the exemplary embodiment shown, the heating elements 16,
17, 18 are designed as radiant heating elements which are covered
by a vitroceramic plate 19. The vitroceramic plate 19 has roughly
the same dimensions as the upper surface of the bottom door 7. The
vitroceramic plate 19 is, furthermore, equipped with mounting holes
(not illustrated), through which extend bases for supporting the
retaining parts 20 for cooking product carriers 21, as also shown
in FIG. 4. Other--preferably readily appealing--covers may also be
used instead of a vitroceramic plate 19, e.g. a thin metal
sheet.
[0048] With the help of an operating handle provided in the
operating panel 12, the top-mounted cooking appliance may be
switched to hob or under-surface heating mode, as explained
below.
[0049] In hob mode the cooking zone heating elements 16, 17 are
triggered individually via the control circuit 13 by means of
operating elements 11, which are provided in the operating panel
12, whilst the flat heating elements 18 remain out of operation.
The hob operating mode may be executed with the bottom door 7
lowered as shown in FIG. 1. It may, however, also be operated with
the cooking space 3 closed, with the bottom door 7 raised up in an
energy-saving function.
[0050] In under-surface heating mode, not only the cooking zone
heating elements 16, 17 but also the flat heating elements 18 are
triggered by the control device 13.
[0051] To ensure that the cooking product is browned as evenly as
possible during under-surface heating mode, it is crucial that the
cooking hob 15 providing the heat from below has equal distribution
of the heat output over the surface of the cooking hob 15, even
though the heating elements 16, 17, 18 have different nominal
outputs. Thus the heating elements 16, 17, 18 are advantageously
not switched to continuous operation by the control circuit 13, but
the power supply to the heating elements 16, 17, 18 is delivered at
timed intervals. This means that the different nominal heat outputs
of the heating elements 16, 17, 18 are reduced individually so that
the heating elements 16, 17, 18 achieve an even distribution of
heat output across the surface of the cooking hob 15.
[0052] FIG. 4 is a schematic diagram showing the position of a fan
23, e.g. for generating circulating area in a hot-air mode or for
supplying cool air. In addition, an upper heating element 22, which
is attached to an upper side of the muffle 5, is provided, which
may be designed with one or more rings, e.g. with an inner and an
outer ring. Further heating elements, such as a ring element, may
also be provided between the rear wall of the housing 1 and the
muffle, though such heating elements are not illustrated here for
the sake of clarity. The control circuit 13 may be used for setting
the various operating modes, such as--for example--top heating,
hot-air or rapid heating mode, by appropriate actuation and setting
of the heating output of the heating elements 16, 17, 18, 22, with
activation of the fan 23 if necessary. The heating output may be
adjusted by means of a suitable timed delivery system. In addition
the cooking hob 15 may have a different design, e.g. with or
without grilling zone, as a single or multi-ring warming area
without hob, and so on. The housing 1 has a seal 24 to the bottom
door 7.
[0053] The operating panel 12 is arranged mainly on the front face
of the bottom door 7. Alternatively, other arrangements are also
possible, e.g. on the front face of the housing 1, distributed
across different subpanels and/or partially on the lateral surfaces
of the cooking appliance. Other designs are possible. The operating
elements 11 are unrestricted in terms of their construction and may
take the form of, for example, operating handles, toggle switches,
push-buttons or membrane keys, which incorporate display elements
14 such as--for example--LED, LCD and/or touchscreen displays.
[0054] FIG. 5 is a schematic, not-to-scale diagram of a top-mounted
cooking appliance drawn from the front, in which the bottom door 7
is opened and resting on the work surface 8. The closed state is
drawn in dashed lines.
[0055] In this embodiment, two displacement switch panels 25 are
located on the front face of the permanently mounted housing 1.
Each displacement switch panel 25 comprises two push-buttons,
namely an upper CLOSE button 25a for displacing the bottom door 7
upward in the closing direction, and a lower OPEN button 25b for
displacing the bottom door 7 downward in the opening direction.
Without automatic operation (see below) the bottom door 7 is
displaced upward only by continuous, simultaneous pressure on the
CLOSE buttons 25a of both displacement switch panels 25, if
possible; the bottom door 7 is likewise also displaced downward
only by continuous, simultaneous pressure on the OPEN buttons 25b
of both displacement switch panels 25, is possible (manual
operation). Since manual operation requires increased attention by
the user during operation and, in this case, also requires the use
of both hands, an anti-jamming mechanism is merely optional. In an
alternative embodiment, displacement switch panels 26 are located
on opposite outer surfaces of the housing 1 with corresponding
CLOSE buttons 26a and OPEN buttons 26b, as indicated by the dotted
lines.
[0056] The control circuit 13, which is shown by a hatched line on
the interior of the bottom door 7 behind the operating panel 12,
actuates the drive motor 9 so that the bottom door 7 begins to move
gently, i.e. not abruptly by the drive motor 9 simply being started
up, but by means of a defined ramp.
[0057] In this exemplary embodiment the control circuit 13
comprises a memory unit 27 for storing at least one destination or
displacement position P0, PE, P1, P2, PZ of the bottom door 7,
preferably with volatile memory components, e.g. DRAMs. If a
destination position P0, P1, P2, PZ is stored, then the bottom
door--after actuation of one of the buttons 25a, 25b or 26a, 26b on
the displacement switch panels 25 or 26--automatically moves in the
set direction until the next destination position is reached or one
of the buttons 25a, 25b or 26a, 26b is actuated again (automatic
operation). In this exemplary embodiment the lowest destination
position PZ corresponds to the maximum open state, the (zero)
position P0 corresponds to the closed state, and P1 and P2 are
freely adjustable positions in between. Once the last destination
position is reached for a direction, manual operation must be used
for further displacement if this is possible (i.e. the final end
positions do not correspond to the maximum open or closed end
state). In the same way, if no destination position is stored for a
direction--as would be the case, for example, for an upward
movement to the closed position if only PZ is stored, but not P0,
P1, P2, then manual operation must be used. If no destination
position is stored, e.g. for a new installation or after a power
outage, automatic operation is not possible. If the bottom door 7
is displaced, particularly in automatic mode, then an anti-jamming
mechanism is preferably activated.
[0058] Automatic operation and manual operation are not mutually
exclusive: continuous activation of the displacement switch
panel(s) 25, 26 also causes the bottom door 7 to move in manual
mode, if a destination position could be reached in this direction.
In this case, for example, a maximum actuation time of e.g. 0.4
seconds for the displacement panels 25 or 26, or--more
precisely--for the corresponding buttons 25a, 25b or 26a, 26b, may
be set for activation of the automatic mode.
[0059] A destination position P0, P1, P2, PZ may be any position of
the bottom door 7 between and including the zero position P0 and
the maximum open position PZ. The maximum stored open position PZ
need not, however, be the position resting on the work surface 8.
The destination positions P0, P1, P2, PZ may be stored with the
bottom door 7 at the required destination position P0, P1, P2, PZ,
by pressing an actuation button 28 in the operating panel 12--for
example--for several seconds (e.g. two seconds continuously).
Existing optical and/or acoustic signal emitters, which emit
appropriate signals when a destination position is stored, are not
drawn for the sake of clarity. The required destination position
P0, P1, P2, PZ to be set is reached--in this exemplary embodiment,
for example--by operating the displacement switch panels 25 or 26
with both hands and manual displacement to this position.
[0060] Just one destination position, or--as shown in this
exemplary embodiment--a plurality of destination positions P0, P1,
P2, PZ, may be stored in the memory unit 27. If there is a
plurality of destination positions P0, P1, P2, PZ these may be
reached in succession by actuation of the corresponding
displacement buttons 25a, 25b or 26a, 26b. Using a plurality of
destination positions P0, P1, P2, PZ the top-mounted cooking
appliance can easily be adjusted to the required operating height
of several users. The destination position(s) may advantageously be
canceled and/or overwritten. In one embodiment, for example, only
one destination position may be stored in the open state, whilst
the zero position P0 is automatically detected and can be
automatically reached. Alternatively, the zero position P0 must
also be stored in order to be automatically accessible.
[0061] It is particularly beneficial, in the interests of ergonomic
use, for one or more of the destination positions P1, P2, PZ to
open the bottom door 7 by at least approx. 400 mm to approx. 540 mm
(i.e. P1-P0, P2-P0, PZ-P0>40 cm to 54 cm). With this degree of
opening the cooking product carriers 21 can easily be placed in the
retaining parts 20. In this instance it is beneficial if the
viewing window 4 is set approximately at the user's eye level or
slightly below, e.g. by means of a template indicating the size of
the cooking appliance.
[0062] The diagrams do not show an existing mains power buffering
for bridging power outages of approx. 1 to 3 seconds, and
preferably up to 1.5 seconds of power outage.
[0063] The drive motor 9 from FIG. 1 has at least one sensor unit
31, 32 on a motor shaft 30, arranged either in front or behind a
gear unit, in order to measure a displacement path or a position
and/or a speed for the bottom door 7. The sensor unit may, for
example, comprise one or more induction, Hall, optical or SAW
sensors, etc. In this case, for simple measurement of path and
speed, two Hall (partial) elements 31 are mounted on the motor
shaft 30, offset by 180.degree.--i.e. opposite one another--and a
Hall meter 32 is installed at a fixed location in this area, at a
distance from the motor shaft. If a Hall element 31 then travels
past the meter 32 when the motor shaft 30 rotates, a measurement
and/or sensor signal is generated that is, in good approximation,
digital. Therefore, with (for example) two Hall elements 31, a
rotation of the motor shaft 30 causes two signals to be emitted. If
the timing of these signals is analyzed, e.g. the difference in
time between them, then the speed vL of the bottom door 7 can be
determined, for example via comparison tables or by conversion into
real time in the control circuit 13. By addition or subtraction of
the measurement signals, a displacement path or position for the
bottom door 7 may be determined.
[0064] A speed regulator may implement the speed, for example by
means of a PWM-controlled power semiconductor.
[0065] In order to determine the zero point, the path measurement
is automatically readjusted at each actuation by initialization of
the bottom door 7 in the zero position P0, so that--for example--an
erroneous sensor output or recording is not implemented.
[0066] The drive motor 9 can be operated by actuation of both
displacement switch panels 25 or 26 even if the main switch 29 is
deactivated.
[0067] Instead of two separate switches for each displacement panel
25, 26, a single switch for each displacement panel is also
possible, e.g. a toggle switch with neutral position, which
actuates only under pressure. Other forms are also possible. Nor
are the operating elements 28, 29 on the operating panel 12
restricted as to their type and arrangement.
[0068] The arrangement and distribution of the control circuit 13
is thus flexible and not restricted, and may therefore also
comprise a plurality of PCBs, e.g. a display board, a control board
and a lift board, which are spatially separate.
[0069] A 4-mm opening, for example, may be detected by end switches
33, which deactivate an anti-jamming mechanism upon actuation.
Deactivation of the anti-jamming mechanism may, however, also be
possible for example by counting pulses from the sensor signals,
when a count value is reached which corresponds to a final
measurement of--for example--8.6 mm.
[0070] The anti-jamming mechanism is thus deactivated independently
of such mechanical end switches 33.
[0071] The top-mounted cooking appliance may also be designed
without a memory unit 27, in which case automatic operation is not
possible. This may be useful for increasing user safety, e.g.
protection against jamming.
[0072] FIG. 6 is a not-to-scale diagram showing application of the
displacement speed vL of the bottom door 7 in mm/s compared to the
position of the bottom door in mm from the zero position P0 for a
displacement of the bottom door 7 from the closed state where P0=0
mm to PZ=maximum opening, in this case 530 mm in manual
displacement mode (i.e. without automatic displacement), and, as
indicated by the dotted arrow, a stopping of the displacement
movements between P0 and PZ. The curve will run in the direction of
the arrow, i.e. from right to left. The downward-pointing arrows
situated above the curve indicate actuations of the operating panel
12.
[0073] The displacement of the bottom door 7 downward starts with
the two-handed actuation of the displacement switch panels 25, 26
or of the OPEN switches 25b or 26b, as indicated by the
perpendicular arrow on the top left. The control circuit 13
controls the drive motor 9 so that the bottom door 7 starts up
gently, i.e. with a defined ramp R1, to its target speed vL of (in
this case) 50 mm/s. The ramp R1 is linear in this case. The drive
motor 9 is therefore not simply activated.
[0074] The displacement movement is therefore also
load-independent, in particular it is independent of the loading of
the bottom door 7 or changes in the frictional conditions of the
mechanism. An input variable for this purpose may be the number of
rotations of the drive motor 9. These may be measured by Hall
sensors, for example.
[0075] Once the target speed vL=50 mm/s is reached the bottom door
7 travels constantly downward until it is close to the maximum
opening PZ, which results from the constructively preset maximum
displacement of the bottom door 7 or from the reaching of the work
surface 8. In this diagram it is assumed that the constructive
maximum opening PZ is reached. In this case the control circuit 13
detects this approach and, gently and automatically, slows down the
bottom door 7, i.e. with a defined ramp R2, at PZ. The two ramps R1
and R2 may have other gradients or forms. The approach to the base
plate may be detected by end switches 33 and/or by monitoring of
the displacement path.
[0076] If one or both of the displacement switches 25b, 26b is
released, as indicated by the perpendicular arrow on the top left,
the bottom door 7 stops abruptly without ramp, as indicated by the
dotted arrow. In this mode, therefore, the movement is started
gently but halted abruptly, unless the end position is reached.
[0077] The cooking space 3 is not opened, and the bottom door 7 is
therefore not displaced from the zero position P0, if an
anti-opening safeguard is active, i.e. if, for example, a defined
temperature e.g. 425.degree. C. or 600.degree. F. is exceeded in
the cooking space, or if a child safety feature is activated.
[0078] FIG. 7 is a not-to-scale diagram similar to FIG. 6, showing
a displacement of the bottom door 7 from the closed state to a
stored position P1=476 mm in automatic displacement mode.
[0079] In this case, as a result of brief activation of one of the
OPEN switches 25b or 26b, as indicated by the perpendicular arrow
on the top right, the bottom door 7 starts to move automatically to
the position P1. Here, too, the bottom door 7 is started up gently
(right-hand ramp) and slowed down automatically (left-hand ramp).
In this embodiment it is possible, in automatic mode, to select
between two fixed target speeds, i.e. 75 mm/s (dashed line) and 50
mm/s (solid line), wherein the lower speed is particularly ideal
for elderly users. The slower speed level is preset, e.g. upon
delivery. More than two speed levels or target speeds may also be
provided; the free adjustment of target speed(s) by the user is
also a possibility. Ideally it is also possible to switch between
at least two speed levels of 50 mm/s and 65 mm/s, e.g. when an
appliance is initialized.
[0080] FIG. 8 is a not-to-scale diagram showing a displacement of
the bottom door 7 from the maximum open position PZ to the zero
position P0, i.e. to the closed state, in manual operating
mode.
[0081] The displacement of the bottom door 7 upward starts with the
two-handed actuation of the CLOSED switches 25a and 26a, as
indicated by the perpendicular arrow on the top left. The control
circuit 13 controls the drive motor 9 so that the bottom door 7
starts up gently from PZ to its target speed of vL=50 mm/s, and
then travels constantly at this target speed (toward the
right).
[0082] The control circuit 13 detects an approach to the zero
position P0 and gently slows down the bottom door 7 in good time
beforehand. Now, however, instead of moving downward directly to
the zero position P0 by means of the linear ramp, the
speed-dependent control is switched to control with defined voltage
4 mm before the zero position P0, i.e. by supplying the motor 9
with a corresponding voltage. This enables maximum power
development to be set if the drive motor 9 is blocked. This voltage
varies according to the history of the displacement (loading,
frictional conditions, etc.). The 4 mm opening is detected by the
path measurement or additionally or alternatively via the end
switches 33. An anti-jamming mechanism can also be dispensed with
in the range from P0 to P0+4 mm.
[0083] If, as in FIG. 6, one or both of the displacement switches
25b, 26b is released, as indicated by the perpendicular arrow on
the top right, the bottom door 7 stops abruptly without ramp, as
indicated by the dotted arrow.
[0084] FIG. 9 shows a not-to-scale diagram for a displacement of
the bottom door 7 from a stored position P1=476 mm to the closed
state P0 in automatic displacement mode. In contrast to the manual
displacement mode shown in FIG. 8, only one of the CLOSED switches
25a, 26a now needs to be briefly activated, as indicated by the
upper perpendicular arrow. The bottom door 7 then moves similarly
to the manner shown in FIG. 7, only in the other direction. When
the zero position P0 is approached, then--similarly to the
situation from FIG. 8--the braking ramp switches from a
speed-controlled state to a load or closing force-controlled state
for the last 4 mm opening.
[0085] FIG. 10 is a diagram similar to that shown by FIG. 8, in
which a jam now occurs at a target speed of vL=50 mm/s, as
indicated by the upper perpendicular arrow. If, for example, a hand
or a pan etc. becomes jammed between the bottom door 7 and the
housing 1, the speed of the bottom door 7 drops away since the
object prevents any further displacement. The lift speed is
monitored here, for example, by analysis of the sensor signals from
the motor shaft, wherein--for example--the time between the
measurement signals or pulses is analyzed. The motor current is
only monitored in the second instance, this being a somewhat slower
method. In particular the power that may be generated by the motor
9 for displacement is limited, to prevent accidents caused by
excessively severe jamming (see also FIGS. 12 and 13). The
deviation from the target speed is detected by the control circuit
13, e.g. by a speed deviation or a temporary change in speed. The
bottom door is thereupon reversed so that the object may be
removed; a warning signal, e.g. acoustic, may also be emitted. The
bottom door 7 thereafter only starts up again upon renewed
actuation of a displacement keypad 25, 26.
[0086] To prevent incorrect triggering of a jammed state, e.g. by a
change in loading or a change in the running properties of the
mechanism, the anti-jamming mechanism, firstly, may be activated
only when the bottom door 7 has reached its target speed (if a
displacement button 25a, 25b, 26a, 26b is first released before
this, the bottom door 7 stops immediately), and, secondly, a
plurality of sensor signals are analyzed, for example to obtain an
average figure.
[0087] FIG. 11 shows the jammed state (upper perpendicular arrow)
during the opening displacement of the bottom door 7 in automatic
mode to a destination position P1, in which an object is jammed
between the lower surface of the bottom door 7 and the work surface
8. In this case the jam may be detected via two redundant end
switches, which detect a particularly uneven easing of the load on
the bottom door 7, whereupon the drive motor 9 reverses. The
maximum permitted force-time profile (see FIGS. 12 and 13) is
thereby not exceeded.
[0088] FIG. 12 shows a maximum force F in N that may be applied to
the bottom door 7 in the event of a jam during the displacement in
a closing direction (i.e. upward), against the elapsed time t in s
as a first force-time profile FT1.
[0089] If a jam occurs at t=0 s the potential closing force is
limited to 100 N, corresponding to approx. 10 kg, for 5 s. This
makes sense, for example, if the motor 9 is adjusted upward by the
control device 13 in order to maintain the target speed. This
ensures, in particular, that body parts are not injured. If the
bottom door is drawn up for 5 s with (maximum) 100 N, the maximum
applicable force is reduced further to 25 N, e.g. for 5 seconds.
This level of force can be maintained subsequently or, for example,
reduced further to 0 N. It must be stressed that this force-time
profile FT1 shows only the maximum applicable force, and the force
actually applied is usually lower, e.g. if the jam is detected by
the control device 13 and the bottom door 7 is reversed accordingly
after t=0.5 s, whereupon the applied force is reduced from 100 N to
e.g. 0 N.
[0090] The maximum force threshold value of 100 N may also apply
for other displacement situations.
[0091] FIG. 13 shows a maximum force F in N that may be applied to
the bottom door 7 in the event of a jam during displacement in an
opening direction (i.e. downward), against elapsed time t in s as a
second force-time profile FT2. In this case the drive motor 9 may
apply up to 400 N to the bottom door 7 in a first block of t=[0 s;
0.5 s], and thereafter 150 N at t=[0.5; 5 s] and thereafter 25
N.
[0092] Of course, the time intervals and force threshold values of
the force-time profiles FT1, FT2 may be adjusted to the structure
and other basic conditions.
[0093] FIG. 14 shows an exemplary displacement profile for the
memorization of functions, wherein--during the displacement of the
door 7--a parameter vr dependent upon the displacement of the door
7 is determined as a reference parameter. A reference speed is
particularly preferred as the reference parameter vr.
[0094] The parameter is determined, in particular, after the
cooking appliance is installed and when it is first commissioned,
in order to take into account environmental influences at the place
of installation. It is particularly advantageous, however, for the
definition of the parameter to be repeated so that environmental
influences that change over time or even internal features of the
cooking appliance can also be taken into account. It is
particularly advantageous for such a parameter to be memorized with
each displacement of the door, particularly each time the door is
raised, in order--for example--to enable a constantly variable load
to be taken into account.
[0095] FIG. 14 shows, by way of example, a speed profile of a
displacement speed vL, wherein a speed v in mm/s is shown over a
current position P of the door 7 in mm.
[0096] Where numerical details are provided these must be regarded
as purely exemplary.
[0097] Starting from an end position PZ, which corresponds to a
fully opened door 7, the door 7 is raised in the direction of the
muffle 5 whilst being accelerated. Once a lower interim position pa
is reached, the door 7 is moved upward with a constant displacement
speed vL.
[0098] A further function of the cooking appliance may be triggered
depending on the displacement speed vL as an exemplary parameter.
Thus, for example, a jammed state may be detected if the
displacement speed is below a target displacement speed vR before
an upper interim position pb is reached, after which point the door
7 is moved toward the muffle 5 with decreasing speed.
[0099] The deviation below a permitted minimum speed vS is
preferably defined as a criterion for the emission of a jammed
signal or the registering of a jammed state. In principal, however,
a fault may also generally be detected when the speed falls outside
a tolerance range vT, wherein the speed tolerance range vT is
likewise preferably preset dependent upon the current operating
conditions.
[0100] In the illustrated exemplary displacement profile the jammed
state situation is drawn, in which the displacement speed vL falls
off before the upper interim position pb is reached and is lower
than the permitted target or minimum speed vS, as illustrated on
the basis of the outlined jam-speed profile. In such a case the
door 7 is preferably accelerated in the opposite direction
(reversed) and moved downward by an opening path s to enable a
jammed object to be removed, as outlined by means of the exemplary
reset-speed profile v2.
[0101] Since the constant speed that may be achieved for the
cooking appliance for raising the door 7 may vary depending on the
current load on the door 7 and/or depending on current external and
internal operating conditions, the cooking appliance may not be
able to reach a normally permissible minimum speed vS, then--for
functions such as, for example, the monitoring of a jammed
state--it is preferable for a memorized parameter, such as the
reference speed vr, to be used as the basis as the reference
parameter for a target speed vR that is to be used.
[0102] Depending on such a reference parameter, which is determined
once, after installation of the cooking appliance or subsequently,
as being the parameter to be determined and, in particular, to be
measured, a permissible minimum speed vS and/or a speed tolerance
range vT are then defined individually in each case.
[0103] The reference parameter, in particular the target speed vR,
is preferably determined after the lower interim position pa is
reached, after which point the door 7 moves upward at a constant
speed. The reference speed vr can preferably be determined on an
initial path section as a reference path sr, so that a parameter
determined over such a reference path may already be used for the
continued upward displacement of the door 7.
[0104] In principal, however, it is also possible for the parameter
to be determined over a reference path sr* which is already within
the acceleration range of the door 7 between the end position PZ
and the lower interim position pa. In particular, such a definition
can therefore be carried out advantageously if--apart from an
initial acceleration on start-up and a transition phase to the
constant speed--there is a constant acceleration phase.
[0105] In principal, however, it is possible for the reference
parameter to be determined over a greater range, possibly even over
the entire displacement path. The inclusion of the entire
displacement path, inclusive or exclusive of acceleration or
deceleration ranges, may be used in normal operation, particularly
for the detection of faults or changes in the displacement
conditions (friction, leverage, etc.). In the event of a fault a
service signal may, for example, be emitted, which alerts the user
to the need for lubrication or maintenance of guide rails or of a
drive module.
[0106] When parameters are memorized, such as the reference speed
vr as a parameter, a procedure is preferred in which an operator
must keep one, or preferably two, buttons 25a, 26a, pressed down
for the duration of the parameter setting process over a specific
predefined, particularly initial, lifting path of the door 7. For
example a user must hold down the button(s) for at least two
seconds when the door is started up, enabling the appliance to
reach the ramp or the lower position pa and to travel through the
reference definition section sr. If the button(s) is/are released
early, the result is that the reference value vr cannot be
correctly determined, which may--for example--lead to an
anti-jamming mechanism not being activated on the basis of the
displacement speed vL, which is why--in turn--automatic
displacement mode is not permitted. Releasing of the button
therefore causes the displacement to stop and the parameter
definition process to be aborted. Even in subsequent displacement
movements, it is preferable for the definition of a parameter to be
aborted in the event of a fault, such as--for example--a jammed
state, to ensure that no parameters determined on the basis of an
incorrect displacement movement are stored.
[0107] In addition to the definition of the reference parameter vr,
the latter--as already described above--may also be readjusted by
monitoring and adjusting it for small, systematic changes, e.g. due
to variable frictional or leverage conditions, over one or more
additional ranges. This readjustment is preferably carried out
within the range of a constant target value, e.g. in the range of a
constant displacement speed.
[0108] A parameter may be permanently stored in the cooking
appliance upon being memorized for the first time. It is useful,
however, for such a parameter to be updated from time to time or
even with each displacement movement, so that changing operating
conditions are taken into account.
TABLE-US-00001 List of reference characters 1 Housing 2 Wall 3
Cooking space 4 Viewing window 5 Muffle 6 Muffle hole 7 Bottom door
8 Work surface 9 Drive motor 10 Lifting element 11 Operating
element 12 Operating panel 13 Control circuit 14 Display elements
15 Cooking hob 16 Heating element 17 Heating element 18 Flat
heating element 19 Vitroceramic hob 20 Retaining part 21 Cooking
product carrier 22 Upper heating element 23 Fan 24 Seal 25
Displacement switch panel 25a Upward displacement switch 25b
Downward displacement switch 26 Displacement switch panel 26a
Upward displacement switch 26b Downward displacement switch 27
Memory unit 28 Confirmation button 29 Main switch 30 Motor shaft 31
Hall element 32 Meter 33 End switch FT1 First force-time profile
FT2 Second force-time profile P Position pa Lower interim position
pb Upper interim position P0 Zero position PZ End position PS
Reversing position R1 Speed ramp R2 Speed ramp ds Jammed signal sr,
sr* Reference paths v2 Reset speed profile vr Reference parameter
(reference speed) vR Target speed vS Minimum speed vT Speed
tolerance range vL Displacement speed of bottom door
* * * * *