U.S. patent application number 11/990410 was filed with the patent office on 2009-05-14 for cooking appliance.
This patent application is currently assigned to BSH Bosch und Siemens Hausgeraete GmgH. Invention is credited to Ingo Bally, Kerstin Feldmann, Wolfgang Fuchs, Martin Keller, Edmund Kuttalek, Maximilian Neuhauser, Klemens Roch, Wolfgang Schnell, Guenter Zschau.
Application Number | 20090120424 11/990410 |
Document ID | / |
Family ID | 37101634 |
Filed Date | 2009-05-14 |
United States Patent
Application |
20090120424 |
Kind Code |
A1 |
Bally; Ingo ; et
al. |
May 14, 2009 |
Cooking Appliance
Abstract
A cooking appliance, particularly an elevated-mounted cooking
appliance, comprising: at least one muffle, which delimits a
cooking compartment and whose muffle opening is surrounded by a
muffle frame; a door for closing the muffle opening; a drive
device, which is controlled by a control circuit and which serves
to displace the door, and; a pinching protection device for
identifying a pinching instance. Once a pinching instance has been
identified by the pinching protection device, the drive device can
be controlled by the control circuit so that a force applied to the
door does not exceed a specified force time profile.
Inventors: |
Bally; Ingo; (Traunstein,
DE) ; Feldmann; Kerstin; (Bretten, DE) ;
Fuchs; Wolfgang; (Altenmarkt a.d. Alz, DE) ; Keller;
Martin; (Traunreut, DE) ; Kuttalek; Edmund;
(Grassau, 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
GmgH
Muenchen
DE
|
Family ID: |
37101634 |
Appl. No.: |
11/990410 |
Filed: |
July 26, 2006 |
PCT Filed: |
July 26, 2006 |
PCT NO: |
PCT/EP2006/064704 |
371 Date: |
February 13, 2008 |
Current U.S.
Class: |
126/19R ;
126/273R; 99/337 |
Current CPC
Class: |
F24C 15/027 20130101;
F24C 7/08 20130101 |
Class at
Publication: |
126/19.R ;
126/273.R; 99/337 |
International
Class: |
F24C 15/00 20060101
F24C015/00; F24C 15/02 20060101 F24C015/02 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 17, 2005 |
DE |
102005038897.3 |
Claims
1-18. (canceled)
19. A cooking appliance comprising: a muffle having a muffle body
defining a cooking compartment with a cooking compartment access
opening formed in the muffle body; a door configured for traveling
movement in and out of a covering relation with the muffle access
opening; a drive device in mechanical communication with the door
for applying motive force thereto; a control circuit in operational
communication with the drive device for controlling door motion;
and a pinch protection device in operational communication with the
control circuit for detecting a pinch event, wherein upon detection
of a pinch event by the pinch protection device, the control
circuit controls the drive device to apply a force to the door that
does not exceed a predetermined force/time profile, with the
force/time profile representing a predetermined force applied for a
predetermined time period.
20. The cooking appliance according to claim 18 wherein the pinch
protection device is functionally integrated in the control
circuit.
21. The cooking appliance according to claim 19 wherein a first
force/time profile is applied for a pinch event occurring when the
door is being driven toward the muffle access opening and a second
force/time profile is applied for a pinch event occurring when the
door is being driven away from the muffle access opening.
22. The cooking appliance according to claim 21 wherein the first
force/time profile includes a first portion having a maximum force
of 100 N for 5 s, and a second portion having a maximum force of 25
N for an indeterminate time.
23. The cooking appliance according to claim 21 wherein the second
force/time profile includes a first portion having a maximum value
of 400 N for 0.5 s; a second portion having a maximum force of 150
N for 4.5 s; and a third portion having a maximum force of 25 N for
an indeterminate time.
24. The cooking appliance according to claim 19 and further
comprising means for monitoring door speed including means for
detecting a pinch event.
25. The cooking appliance according to claim 24 wherein the means
for detecting a pinch event includes means for determining a
reference speed and means for a comparing the door speed with the
reference speed to determine a deviation of the door speed from the
reference speed, with a predetermined deviation being indicative of
a pinch event.
26. The cooking appliance according to claim 5 wherein the means
for monitoring the door speed includes means for detecting a change
of door speed within a predetermined time period with a
predetermined change in door speed within a predetermined time
period being indicative of a pinch event.
27. The cooking appliance according to claim 19 the control circuit
includes means for regulating door movement as a function of door
speed.
28. The cooking appliance according to claim 19 wherein the control
circuit includes means for causing the drive device to reverse door
movement upon detection of a pinch event by the pinch protection
device.
29. The cooking appliance according to claim 25 wherein the pinch
protection device becomes operational when the means for monitoring
door speed detects that door speed has reached the reference
speed.
30. The cooking appliance according to claim 25 wherein the control
circuit controls the drive device according to a predetermined
force/time profile when the means for monitoring door speed detects
that door speed has reached the reference speed.
31. The cooking appliance according to claim 19 and further
comprising at least one stop switch operationally disposed between
the muffle body and the door wherein an actuation of the at least
one stop switch deactivates the pinch protection device.
32. The cooking appliance according to claim 30 wherein the at
least one stop switch becomes operational a distance of about 4 mm
between the muffle body and the door.
33. The cooking appliance according to claim 31 wherein the door
can be moved into a closed relation with the access opening with a
predetermined force when the at least one stop switch is
actuated.
34. The cooking appliance according to claim 19 wherein said
cooking appliance is configured for mounting above countertop level
with a plurality of sides and a downwardly directed muffle opening
and the door is configured for covering the downwardly directed
muffle opening.
35. A method for operating a cooking appliance comprising the steps
of: providing a muffle having a muffle body defining a cooking
compartment with a muffle access opening formed in the muffle body;
a door configured for traveling movement in and out of a covering
relation with the muffle access opening; a drive device in
mechanical communication with the door for applying motive force
thereto; a control circuit in operational communication with the
drive device for controlling door motion; and a pinch protection
device in operational communication with the control circuit;
detecting a pinch event using the pinch protection device; and
controlling the drive device using the control circuit to apply a
force to the door that does not exceed a predetermined force/time
profile, with the force/time profile representing a predetermined
force applied for a predetermined time period.
Description
[0001] The present invention relates to a cooking appliance, in
particular a high-level cooking appliance, comprising at least a
muffle which delimits a cooking compartment and has a muffle
opening, a door for closing the muffle opening, a drive device
which is controlled by a control circuit and is for causing the
door to travel, and a pinching protection device for detecting a
pinching instance.
[0002] DE 102 28 140 A1 discloses a high-level cooking appliance in
which any pinching of objects at the base door can be detected by a
plurality of pinching protection switches between the base door and
the muffle compartment, wherein said pinching protection switches
can be actuated independently of one another. In this case it is
additionally possible to analyze a pressure increase in a door seal
having a hollow profile.
[0003] DE 101 64 239 A1 describes a pinching protection which is
triggered by different tensile forces at the traction cables which
drive the base door. A torque sensor is also described which
measures a load torque exerted on the drive shaft of the electric
motor. Tensile force sensors, piezoelectric sensors and deformation
or stress/strain sensors are also listed as sensors.
[0004] In addition, DE 102 28 141 A1 describes an optoelectronic
sensor for detecting a pinching instance, wherein said sensor
switches according to the quantity of reflected light.
[0005] Countermeasures such as stopping or reversing the door are
introduced upon detection of the pinching instance. There is
typically a perceptible time period which elapses between the
detection of the pinching instance and the coming into effect of
the countermeasures due to the inertia of the system; thus, for
example, the motor must be stopped and restarted for the purpose of
reversing.
[0006] It is disadvantageous that the above-described pinching
detection systems do not provide measures for the time between the
detection of the pinching instance and the subsequent
countermeasure. Likewise, no measures are provided for identifying
malfunctions of the pinching protection.
[0007] The present invention therefore addresses the problem of
providing improved operational safety for the pinching instance on
a cooking appliance of the type described above.
[0008] The present problem is solved by the cooking appliance
having the features recited in claim 1 and a method in accordance
with claim 17.
[0009] For this, the cooking appliance, which is in particular a
high-level cooking appliance but can also be a cooking appliance
having a baking carriage, is configured in such a way that, after a
pinching instance has been detected by the pinching protection
device, the control circuit regulates the drive device such that a
force which is applied to the door does not exceed a specific
force/time profile.
[0010] The pinching protection is preferably not embodied as a
discrete assembly, but is functionally integrated in the control
circuit or its module(s), which typically already includes a
microcontroller.
[0011] For improved safety coordination it is advantageous if a
first force/time profile is provided for a pinching instance in the
closing direction of the door, i.e. as a result of upward travel in
the case of a high-level cooking appliance. An object is typically
pinched between base door and muffle frame or housing in this case.
Alternatively or additionally, a second force/time profile can be
provided for a pinching instance in the opening direction of the
door, if an object is then typically pinched between base door and
work surface in the case of a high-level cooking appliance.
[0012] The first force/time profile, i.e. in a closing direction,
advantageously has a first section having a maximum force F=100 N
for 5 s, followed by a second section having a maximum force F=25
N. The third section can also be reduced further to 0 N after a
certain time.
[0013] The second force/time profile advantageously has a first
section having a maximum force F=400 N for 0.5 s, followed by a
second section having a maximum force F=150 N for 4.5 s, followed
by a third section having a maximum force F=25 N. The third section
can also be reduced further to 0 N after a certain time.
[0014] In order to react quickly and with minimal errors to a
pinching instance it is advantageous if the pinching instance can
be detected by monitoring a travel speed of the door, e.g. on the
basis of percental or absolute deviation from a reference speed
value or on the basis of a high positive or negative
acceleration.
[0015] Furthermore, it is advantageous if the travel movement of
the door generally can be regulated depending on speed, and thus
independently of a load or frictional conditions. In addition,
provision is advantageously made for reaching a reference speed via
speed ramps.
[0016] For greater safety, it is advantageous if the travel
direction of the door is reversed in the pinching instance, in
particular if a pinching protection can only be activated when a
reference speed of the door has been reached. It is also
advantageous if the force/time profile can only be activated if a
reference speed of the door has been reached.
[0017] In addition, provision is advantageously made for at least
one stop switch which is arranged in the region between muffle
opening and door, wherein an actuation of the at least one stop
switch deactivates the pinching protection device. It is then
advantageous if the at least one stop switch can be actuated within
an opening distance of 4 mm between muffle frame and base door. In
the event that the at least one stop switch is actuated, it is then
advantageous if the door can be pushed onto the muffle opening
using a defined force.
[0018] In particular, the invention is suitable for high-level
cooking appliances in which the muffle opening is a base-side
muffle opening and the door is a base door which preferably moves
in a linear manner.
[0019] The invention is described in greater detail below with
reference to the appended schematic figures, in which:
[0020] FIG. 1 shows a perspective view of a high-level cooking
appliance which is mounted on a wall and has a lowered base
door;
[0021] FIG. 2 shows a perspective view of the high-level cooking
appliance with closed base door;
[0022] FIG. 3 shows a perspective view of a housing of the
high-level cooking appliance without the base door;
[0023] FIG. 4 shows a schematic side view, in cross section along
the line I-I from FIG. 1, of the high-level cooking appliance which
is mounted on a wall and has a lowered base door;
[0024] FIG. 5 shows a front view of a further embodiment of a
high-level cooking appliance;
[0025] FIG. 6 to 11 show diagrams of travel movements of a base
door in the context of various limiting conditions;
[0026] FIGS. 12 and 13 show force/time profile curves for a base
door.
[0027] FIG. 1 shows a high-level cooking appliance with a housing
1. The rear side of the housing 1 is mounted on a wall 2 in the
manner of a suspended cabinet. A cooking compartment 3, which can
be monitored via a viewing window 4 installed in the front side of
the housing 1, is defined in the housing 1. It can be seen from
FIG. 4 that the cooking compartment 3 is delimited by a muffle 5
which is equipped with a heat-insulating jacket (not shown) and
that the muffle 5 has a base-side muffle opening 6. The muffle
opening 6 can be closed by means of a base door 7. The base door 7
is shown lowered in FIG. 1, wherein its underside is in contact
with a work surface 8 of a kitchen entity. In order to close the
cooking compartment 3, the base door 7 must be repositioned to the
position shown in FIG. 2, the so-called "zero position". For the
purpose of repositioning the base door 7, the high-level cooking
appliance has a drive device 9, 10. The drive device 9, 10 has a
drive motor 9 which is illustrated by means of broken lines in
FIGS. 1, 2 and 4 and is arranged between the muffle 5 and an
external wall of the housing 1. The drive motor 9 is arranged in
the region of the rear side of the housing 1 and, as shown in FIG.
1 or 4, has an active connection to a pair of lifting elements 10
which are connected to the base door 7. In this case, as shown in
the schematic side view in FIG. 4, each lifting element 10 is
designed in the form of an L-shaped carrier whose vertical limb
extends from the drive motor 9 in the housing. For the purpose of
repositioning the base door 7, the drive motor 9 can be actuated
with the aid of an operating panel 12, which is arranged on the
front of the base door 7 in accordance with FIGS. 1 and 2, and a
control circuit 13. As shown in FIG. 4, the control circuit 13 is
located behind the operating panel 12 within the base door 7. The
control circuit 13, which is composed of a plurality of spatially
and functionally separate printed circuit boards that communicate
via a communication bus, represents a central control unit for the
appliance operation and controls and/or adjusts e.g. heating,
travel of the base door 3, conversion of user inputs, lighting,
pinching protection, timing of heating elements 16, 17, 18, 22 and
much more.
[0028] It can be seen from FIG. 1 that a top side of the base door
7 has a cooking matrix 15. Almost the entire surface of the cooking
matrix 15 is occupied by heating elements 16, 17, 18, these being
indicated in FIG. 1 by dash-dotted lines. In FIG. 1, the heating
elements 16, 17 are two separate cooking position heating elements
of different sizes, while the heating element 18 is a surface
heating element which is provided between the two cooking position
heating elements 16, 17 and almost surrounds the cooking position
heating elements 16, 17. The cooking position heating elements 16,
17 define associated cooking zones or cooking rings for the user;
the cooking position heating elements 16, 17 and the surface
heating element 18 together define an underside-heating zone. The
zones can be indicated by means of a suitable motif on the surface.
The heating elements 16, 17, 18 can be controlled in each case via
the control circuit 13.
[0029] In the exemplary embodiment shown, the heating elements 16,
17, 18 are embodied as radiant heating elements which are covered
by a glass ceramic plate 19. The glass ceramic plate 19 has
approximately the dimensions of the top of the base door 7. The
glass ceramic plate 19 is also equipped with mounting openings (not
shown), through which sockets project for the purpose of holding
support parts 20 for cooking item carriers 21, as is also shown in
FIG. 4. Instead of a glass ceramic plate 19, it is also possible to
use other--preferably quick-reacting--covers, e.g. thin sheet
metal.
[0030] With the aid of an operating knob which is provided in the
operating panel 12, the high-level cooking appliance can be
switched to a cooking position operating mode or an
underside-heating operating mode, wherein these are explained
below.
[0031] In the cooking position operating mode, the cooking position
heating elements 16, 17 can be controlled individually via the
control circuit 13 by means of operating elements 11 which are
provided in the operating panel 12, while the surface heating
element 18 remains unused. The cooking position operating mode can
be implemented when the base door 7 is lowered as shown in FIG. 1.
However, it can also be operated in an energy-saving function when
the cooking compartment 3 is closed and the base door 7 is
raised.
[0032] In the underside-heating operating mode, the control device
13 controls not only the cooking position heating elements 16, 17
but also the surface heating element 18.
[0033] In order to achieve a maximally even browning impression of
the cooking item during the underside-heating operation, it is
critical that the cooking matrix 15 which provides the underside
heating exhibits an even distribution of the heat power output over
the surface of the cooking matrix 15, even though the heating
elements 16, 17, 18 have different nominal powers. Therefore the
heating elements 16, 17, 18 are preferably not switched to a
continuous operation by the control circuit 13, but the current
supply to the heating elements 16, 17, 18 is timed. In this case,
the different nominal heating powers of the heating elements 16,
17, 18 are reduced individually in such a way that the heating
elements 16, 17, 18 provide an equal distribution of the heating
power output over the surface of the cooking matrix 15.
[0034] FIG. 4 schematically shows the position of a fan 23, e.g.
for the generation of recirculating air in the case of hot air
operation or for supplying fresh air. Furthermore, provision is
made for a topside-heating element 22 which is attached at a top
side of the muffle 5 and can be embodied as a single circuit or
multiple circuit, e.g. having an inner circuit and an outer
circuit. It is also possible--not shown here for the sake of
greater clarity--to provide for further heating elements such as a
ring heating element between a rear wall of the housing 1 and the
muffle. The different operating modes including e.g.
topside-heating operation, hot-air operation or rapid-heating
operation can be set by the control circuit 13 by switching on and
setting the heating power of the heating elements 16, 17, 18, 22
correspondingly, optionally with activation of the fan 23. The
setting of the heating power can be done by means of suitable
timing. In addition, the cooking matrix 15 can be embodied
differently, e.g. with or without a grilling zone, as a simple
heat-retention zone (featuring a single circuit or multiple
circuits) without cooking rings, etc. The housing 1 has a seal 24
which faces the base door 7.
[0035] The operating panel 12 is normally arranged on the front
side of the base door 7. Alternatively, other arrangements are also
conceivable, e.g. on the front side of the housing 1, divided over
various partial panels and/or partly on side surfaces of the
cooking appliance. Further configurations are possible. The
operating elements 11 are not restricted in terms of their
construction, and can comprise e.g. operating knobs, tumbler
switches, pushbuttons and plastic membrane buttons. The display
elements 14 comprise e.g. LED, LCD and/or touchscreen displays.
[0036] FIG. 5 schematically shows a high-level cooking appliance
from the front (not to scale), wherein the base door 7 is open and
is in contact with the work surface 8. The closed state is drawn by
means of a broken line.
[0037] In this embodiment there are two travel switch panels 25 on
the front side of the permanently attached housing 1. Each travel
switch panel 25 comprises two pushbuttons, specifically an upper
CLOSE pushbutton 25a which causes a base door 7 to travel upward in
a closing direction, and a lower OPEN pushbutton 25b which causes a
base door 7 to travel downward in an opening direction. Without
automatic operation (see below) the base door 7 only travels upward
as a result of continuous simultaneous depression of the CLOSE
buttons 25a of both travel switch panels 25, if possible; the base
door 7 also only travels downward as a result of continuous
simultaneous depression of the OPEN buttons 25b of both travel
switch panels 25, if possible (manual operation). Since increased
operating alertness on the part of the user is assumed in the case
of manual operation, and both hands are also used here, pinching
protection is only optional. In the case of an alternative
embodiment, travel switch panels 26 are attached on opposite
external sides of the housing 1 and have corresponding CLOSE
buttons 26a and OPEN buttons 26b, as drawn using dotted lines.
[0038] The control circuit 13, which is drawn using dash-dotted
lines and is located in the interior of the base door 7 behind the
operating panel 12, switches the drive motor 9 in such a way that
the base door 7 begins to move gently, i.e. not abruptly by simply
starting the drive motor 9, but via a defined ramp.
[0039] In this exemplary embodiment, the control circuit 13
comprises a memory unit 27 for storing at least a destination or
travel position P0, P1, P2, PZ of the base door 7, preferably using
volatile memory modules, e.g. DRAMs. If a destination position P0,
P1, P2, PZ is stored, following actuation of one of the buttons
25a, 25b or 26a, 26b of the travel switch panels 25 or 26, the base
door can travel independently in the selected direction until the
next destination position has been reached or until one of the
buttons 25a, 25b or 26a, 26b is actuated again (automatic
operation). In this exemplary embodiment, the lowermost destination
position PZ corresponds to the maximum opening, the (zero) position
P0 corresponds to the closed state, and P1 and P2 are freely
selectable intermediate positions. If the last destination position
for a direction has been reached, manual operation is additionally
necessary for further travel, if possible (i.e. if the last final
positions do not correspond to a maximally open final state or to
the closed final state). Similarly, if no destination position is
stored for a direction (which would be the case e.g. for an upward
movement into the closed position if only PZ is stored but not P0,
P1, P2), movement in this direction requires manual operation. If
no destination position is stored, e.g. in the case of a new
installation or following a power disconnection, no automatic
operation is possible. If the base door 7 is to travel using the
automatic operation, pinching protection is preferably
activated.
[0040] Automatic operation and manual operation are not mutually
exclusive: as a result of continuous actuation of the travel switch
panel(s) 25, 26, the base door 7 also moves in manual operation if
a destination position is nonetheless available in this direction.
In this case, it is possible to define e.g. a maximum actuation
time of the travel panels 25 or 26, or of the associated buttons
25a, 25b and 26a, 26b respectively, for the purpose of activating
the automatic operation, e.g. 0.4 seconds.
[0041] A destination position P0, P1, P2, PZ can be any desired
position of the base door 7 between and including the zero position
P0 and the maximum opening position PZ. However, the maximum stored
opening position PZ does not have to be the position which is in
contact with the work surface 8. Storage of the destination
position P0, P1, P2, PZ can be carried out with the base door 7 at
the desired destination position P0, P1, P2, PZ by means of e.g.
actuating a confirmation button 28 in the operating panel 12 for
several seconds (e.g. two seconds). For the sake of greater
clarity, available optical and/or acoustic signal emitters which
output corresponding signals following storage of a destination
position are not drawn. Arriving at the desired destination
position P0, P1, P2, PZ to be set is achieved e.g. by means of--in
this exemplary embodiment--two-handed operation of the travel
switch panels 25 or 26 and manual travel to this position:
[0042] It is possible to store just one or, as shown in this
exemplary embodiment, also a plurality of destination positions P0,
P1, P2, PZ in the memory unit 27. In the case of a plurality of
destination positions P0, P1, P2, PZ, these can be reached
successively by actuating the corresponding travel buttons 25a, 25b
or 26a, 26b.
[0043] By virtue of a plurality of destination positions P0, P1,
P2, PZ, the high-level cooking appliance can easily be adjusted to
the desired operating height of a plurality of users. The
destination position(s) can advantageously be deleted and/or
overwritten. In one embodiment, for example, only one destination
position in the open state can be stored, while the zero position
P0 is detected automatically and can be reached automatically.
Alternatively, the zero position P0 must also be stored in order
that it can be reached automatically.
[0044] For ergonomic use, it is particularly advantageous if the or
a destination position P1, P2, PZ opens the base door 7 at least
approximately 400 mm to approximately 540 mm (i.e. P1-P0, P2-P0,
PZ-P0>=40 cm to 54 cm). At this opening distance, the cooking
item carriers 21 can easily be inserted into the support parts 20.
In this case, it is advantageous if the viewing window 4 is mounted
at approximately eye level of the user or somewhat lower, e.g. by
means of a template which indicates the dimensions of the cooking
appliance.
[0045] A power failure protection for bridging power failures of
approximately 1 to 3 s, preferably up to 1.5 s, is present but not
illustrated.
[0046] The drive motor 9 from FIG. 1 has at least one sensor unit
31, 32 on a motor shaft 30, these being arranged before or after a
transmission if applicable, in order to measure a travel
displacement or a position and/or a speed of the base door 7. The
sensor unit can comprise e.g. one or more induction sensors,
Hall-effect sensors, optoelectronic sensors, SAW sensors, etc. In
this case, in order to measure displacement and speed in a simple
manner, two Hall-effect (partial) elements 31 are attached to the
motor shaft 30 such that they are offset by 180.degree.--i.e.
opposite each other--and a Hall-effect measurement pick-up 32 is
separately attached in a fixed manner in this region of the motor
shaft. When a Hall-effect element 31 then travels past the
measurement pick-up 32 as the motor shaft 30 rotates, a measurement
signal or sensor signal is generated which is closely approximate
to digital. Using (not necessarily) two Hall-effect elements 31,
therefore, two signals are output with one rotation of the motor
shaft 30. By analyzing these signals relative to time, e.g. their
time difference, it is possible to determine the speed vL of the
base door 7, e.g. using comparison tables or a real-time conversion
in the control circuit 13. By means of adding or subtracting the
measurement signals, it is possible to determine a travel
displacement or a position of the base door 7.
[0047] A speed regulator can realize the speed e.g. via a
PWM-controlled power semiconductor.
[0048] In order to determine the zero point, the displacement
measurement is automatically reset by initializing in the zero
position P0 of the base door 7 at each start-up, in order that e.g.
an erroneous sensor signal output or sensor signal pick-up is not
perpetuated.
[0049] The drive motor 9 can be operated by actuating both travel
switch panels 25 or 26 even if the main switch 29 is switched
off.
[0050] Instead of two separate switches per travel panel 25, 26, a
single switch per travel panel is also possible, e.g. a tumbler
switch which has a neutral position and only switches under
pressure. Other forms are also possible. The type and arrangement
of the operating elements 28, 29 of the operating panel 12 are
likewise not restricted.
[0051] The arrangement and distribution of the control circuit 13
is flexible and not restricted in this case, and can therefore
comprise a plurality of boards, e.g. a display board, a control
board and a lift board, which are physically separate.
[0052] A 4-mm opening can be detected by stop switches 33 which,
when actuated, deactivate a pinching protection.
[0053] The high-level cooking appliance can also be embodied
without a memory unit 27, in which case no automatic operation is
then possible. This can be suitable for increased operating safety,
e.g. as protection against pinching.
[0054] FIG. 6 shows a diagram (not to scale) which plots the travel
speed vL of the base door 7 in mm/s relative to the position of the
base door in mm from the zero position P0 for a travel of the base
door 7 from the closed state where P0=0 mm to PZ=maximum opening at
530 mm here using the manual travel operation (i.e. without
automatic travel) and, as indicated by the dotted arrow, a halt of
the travel movement between P0 and PZ. The curve runs in the
direction of the arrow, i.e. from right to left. The arrows that
are present above the curve and point downward indicate actuations
of the operating panel 12.
[0055] The travel movement of the base door 7 downward begins with
two-handed actuation of the travel switch panels 25, 26 or the OPEN
switches 25b or 26b as indicated by the upper left-hand vertical
arrow. The control circuit 13 regulates the drive motor 9 in such a
way that the base door 7 gently, i.e. via a defined ramp R1,
reaches its reference speed of vL=50 mm/s in this case. The ramp R1
is linear here. The drive motor 9 is not simply switched on,
therefore.
[0056] As a result, the travel movement is also load-independent,
in particular it is independent of the load of the base door 7 or
changed frictional conditions of the mechanism. An input variable
for this can be the rotational speed of the drive motor 9, which
speed can be measured e.g. by Hall-effect sensors.
[0057] After reaching the reference speed of vL=50 mm/s, the base
door 7 travels downward in a constant manner until it nears the
maximum opening PZ, which is derived from the structurally
predetermined maximum travel of the base door 7 or as a result of
reaching the work surface 8. In this figure, it is assumed that the
structural maximum opening PZ is reached. In this case, the control
circuit 13 detects this approach and automatically brakes the base
door 7 gently, i.e. using a defined ramp R2, to arrive at PZ. Both
ramps R1 and R2 can have different gradients or shapes. The arrival
at the base plate can be detected by stop switches 33 and/or by
monitoring the travel displacement.
[0058] If one or both of the travel switches 25b, 26b is triggered,
as indicated by the upper left-hand vertical arrow, the base door 7
stops abruptly without a ramp, as indicated by the dotted arrow. In
this mode, starting takes place in a gentle manner, but--unless the
final position is reached--stopping takes place abruptly.
[0059] The cooking compartment 3 is not opened, i.e. the base door
7 is not moved from the zero position P0, if an opening safety
device is active, e.g. if a specific temperature is exceeded in the
cooking compartment, e.g. 425.degree. C. or 600.degree. F., or if a
child safety device is activated.
[0060] FIG. 7 shows a diagram (not to scale) which is similar to
FIG. 6 for travel of the base door 7 from the closed state to a
stored position P1=476 mm using the automatic travel operation.
[0061] In this case, the base door 7 automatically begins to travel
to the position P1 as a result of briefly actuating one of the OPEN
switches 25b or 26b, as indicated by the upper right-hand vertical
arrow. Here again, the base door 7 is gently started (right-hand
ramp) and automatically braked (left-hand ramp). In this
embodiment, using automatic operation it is possible to choose
between two fixed reference speeds, specifically 75 mm/s (broken
line) and 50 mm/s (continuous line), wherein the slower speed is
advantageous for older users in particular. The slower speed level
is preset, e.g. upon delivery. Provision can also be made for more
than two speed levels or reference speeds; unrestricted setting of
the reference speed(s) by the user is also conceivable. Also
advantageous is provision for switching between at least two speed
levels of 50 mm/s and 65 mm/s, e.g. upon device initialization.
[0062] FIG. 8 shows a diagram (not to scale) for travel of the base
door 7 from the maximum opening position PZ to the zero position
P0, i.e. to the closed state, using the manual operation.
[0063] The travel movement of the base door 7 upward begins with
two-handed actuation of the CLOSE switches 25a or 26a, as indicated
by the upper left-hand vertical arrow. The control circuit 13
regulates the drive motor 9 in such a way that the base door 7
starts gently from PZ to its reference speed of vL=50 mm/s, and
then travels constantly at this reference speed (rightward).
[0064] The control circuit 13 detects an approach at the zero
position P0 and gently brakes the base door 7 at the correct time
in advance. Instead of now coming to a halt via the linear ramp
directly at the zero position P0, however, 4 mm before the zero
position P0 provision is made for switching from speed-dependent
voltage to defined voltage, i.e. by supplying a corresponding
voltage to the motor 9. It is thus possible to set a maximum force
development as a result of inhibiting the drive motor 9. This
voltage varies depending on the previous history of the procedure
(load, frictional conditions, etc.). The detection of the 4-mm
opening distance is done via the displacement measurement or
additionally or alternatively via the stop switches 33. In the
region from P0 to P0+4 mm, it is possible to dispense with pinching
protection.
[0065] As in FIG. 6, if one or both of the travel switches 25b, 26b
is triggered, as indicated by the upper right-hand vertical arrow,
the base door 7 stops abruptly without a ramp as indicated by the
dotted arrow.
[0066] FIG. 9 shows a diagram (not to scale) for travel of the base
door 7 from a stored position P1=476 mm to the closed state P0
using the automatic travel operation. Unlike the manual travel
operation shown in FIG. 8, only one of the CLOSE switches 25a, 26a
need be briefly actuated, as indicated by the upper vertical arrow.
The base door 7 then travels in a manner similar to FIG. 7, but in
the other direction. When the zero position P0 is approached, in a
similar manner to the situation in FIG. 8, the braking ramp for the
last 4 mm opening changes from a state which is dependent on speed
to a state which is dependent on load or closing force.
[0067] FIG. 10 shows a diagram which is similar to FIG. 8, in which
pinching now occurs at a reference speed of vL=50 mm/s, as
indicated by the upper vertical arrow. As a result of pinching e.g.
a hand or a saucepan etc. between the base door 7 and the housing
1, the speed of the base door 7 decreases because the object
obstructs further travel. The monitoring of the lifting speed takes
place here e.g. by means of analyzing the sensor signals of the
motor shaft, wherein e.g. the time between the measurement signals
or impulses is analyzed. Only in a second instance is the motor
current monitored, this being a somewhat slower method. In
particular, the force which can be generated by the motor 9 for the
purpose of travel is limited, in order to prevent accidents being
caused by too severe pinching (see also FIGS. 12 and 13). The
deviation from the reference speed is detected by the control
circuit 13, e.g. as a result of a speed variation or a
time-relative change of the speed. In addition, the base door
reverses in order that the object can be removed; an e.g. acoustic
warning signal is also output if applicable. The base door 7 only
starts again subsequently if a travel button panel 25, 26 is
actuated again accordingly.
[0068] In order to ensure that the pinching instance is not
triggered erroneously, e.g. as a result of a changed load or a
change in the running characteristics of the mechanism, firstly the
pinching protection might only be activated if the base door 7 has
reached its reference speed (if a travel button 25a, 25b, 26a, 26b
is triggered prior to this the base door 7 halts immediately), and
secondly a plurality of sensor signals might be analyzed, e.g.
averaged.
[0069] FIG. 11 shows the pinching instance (upper vertical arrow)
during the opening travel of the base door 7 using the automatic
operation to a destination position P1, wherein an object is
pinched between the underside of the base door 7 and the work
surface 8. In this case, the pinching detection can take place via
two redundant stop switches which detect a reduction--in particular
an uneven reduction--in the loading of the base door 7, whereupon
the drive motor 9 reverses. The maximum permitted force/time
profile (see FIGS. 12 and 13) is not exceeded in this case.
[0070] FIG. 12 shows a force F in N, this being the maximum force
which can be applied to the base door 7 in the pinching instance
when traveling in a closing direction (i.e. upward), relative to
the elapsed time t in s as a first force/time profile FT1.
[0071] In the pinching instance, the possible closing force is
limited to 100 N, corresponding to approximately 10 kg, for 5 s
when t=0 s. This is useful e.g. if the motor 9 power is increased
by the control device 13 in order to maintain the reference speed.
In particular, this ensures that body parts are not injured. If the
base door is advanced for 5 s using (maximally) 100 N, the maximum
force that can be applied decreases further to 25 N, e.g. for 5
seconds. Subsequently, this force level can be maintained or e.g.
reduced further to 0 N. It must be emphasized that this force/time
profile FT1 only specifies the maximum applicable force, and the
actual applicable force is normally lower than this, e.g. if the
pinching instance is detected by the control device 13 and the base
door 7 is correspondingly reversed after t=0.5 s, whereupon the
applied force drops from 100 N to e.g. 0 N.
[0072] The maximum force threshold of 100 N can also apply for
other travel situations.
[0073] FIG. 13 shows a force F in N, this being the maximum force
which can be applied to the base door 7 in the pinching instance
when traveling in an opening direction (i.e. downward), relative to
the elapsed time t in s as a second force/time profile FT2. In this
case, the drive motor 9 can apply up to 400 N to the base door 7 in
a first block of t=[0 s; 0.5 s], then 150 N when t=[0.5 s; 5 s],
and then 25 N. Obviously, the time intervals and force thresholds
of the force/time profiles FT1, FT2 can be adapted to the
implementation and to further limiting conditions.
LIST OF REFERENCE SIGNS
[0074] 1 Housing [0075] 2 Wall [0076] 3 Cooking compartment [0077]
4 Viewing window [0078] 5 Muffle [0079] 6 Muffle opening [0080] 7
Base door [0081] 8 Work surface [0082] 9 Drive motor [0083] 10
Lifting element [0084] 11 Operating element [0085] 12 Operating
panel [0086] 13 Control circuit [0087] 14 Display elements [0088]
15 Cooking matrix [0089] 16 Cooking position heating element [0090]
17 Cooking position heating element [0091] 18 Surface heating
element [0092] 19 Glass ceramic plate [0093] 20 Support part [0094]
21 Cooking item carrier [0095] 22 Top heating element [0096] 23 Fan
[0097] 24 Seal [0098] 25 Travel switch panel [0099] 25a Travel
switch upward [0100] 25b Travel switch downward [0101] 26 Travel
switch panel [0102] 26a Travel switch upward [0103] 26b Travel
switch downward [0104] 27 Memory unit [0105] 28 Confirmation button
[0106] 29 Main switch [0107] 30 Motor shaft [0108] 31 Hall-effect
element [0109] 32 Measurement pick-up [0110] 33 Stop switch [0111]
FT1 First force/time profile [0112] FT2 Second force/time profile
[0113] P0 Zero position [0114] P1 Intermediate position [0115] P2
Intermediate position [0116] PZ Final position [0117] R1 Speed ramp
[0118] R2 Speed ramp [0119] vL Travel speed of the base door
* * * * *