U.S. patent application number 13/182503 was filed with the patent office on 2012-01-19 for laundry treatment appliance.
This patent application is currently assigned to DIEHL AKO STIFTUNG & CO. KG. Invention is credited to HARTMUT WAUER.
Application Number | 20120011661 13/182503 |
Document ID | / |
Family ID | 44583904 |
Filed Date | 2012-01-19 |
United States Patent
Application |
20120011661 |
Kind Code |
A1 |
WAUER; HARTMUT |
January 19, 2012 |
LAUNDRY TREATMENT APPLIANCE
Abstract
A laundry treatment appliance has a laundry treatment apparatus
with a rotatably mounted laundry drum held in a housing such that
it can move. The laundry treatment apparatus has an electric motor
for driving the laundry drum, a control system for actuating the
electric motor, a vibration sensor for detecting a vibratory
movement of the laundry treatment apparatus, and a
vibration-damping apparatus for damping a vibratory movement. The
vibration-damping apparatus has at least one controllable vibration
damper which can be actuated in dependence on the vibratory
movement of the laundry treatment apparatus for changing the
vibration-damping properties of the vibration damper. The control
system, in the event of a malfunction in a power supply system,
actuates the electric motor such that the electric motor generates
electrical energy from a rotary movement of the laundry drum and
makes it available to the control system.
Inventors: |
WAUER; HARTMUT; (KISSLEGG,
DE) |
Assignee: |
DIEHL AKO STIFTUNG & CO.
KG
WANGEN
DE
|
Family ID: |
44583904 |
Appl. No.: |
13/182503 |
Filed: |
July 14, 2011 |
Current U.S.
Class: |
8/137 ;
68/12.06 |
Current CPC
Class: |
D06F 37/203 20130101;
D06F 37/22 20130101 |
Class at
Publication: |
8/137 ;
68/12.06 |
International
Class: |
D06F 33/00 20060101
D06F033/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 14, 2010 |
DE |
10 2010 027 158.6 |
Claims
1. A laundry treatment appliance, comprising: a housing; a laundry
treatment apparatus having a rotatably mounted laundry drum, said
laundry treatment apparatus held in said housing such that said
laundry treatment apparatus can move; an electric motor for driving
said rotatably mounted laundry drum in rotation; a control system
for actuating said electric motor, it being possible to connect
said control system to a power supply system; at least one
vibration sensor for detecting a vibratory movement of said laundry
treatment apparatus; at least one vibration-damping apparatus for
damping the vibratory movement of said laundry treatment apparatus,
said vibration-damping apparatus having at least one controllable
vibration damper which can be actuated by said control system in
dependence on the vibratory movement of said laundry treatment
apparatus, the vibratory movement being detected by said at least
one vibration sensor, for changing vibration-damping properties of
said vibration damper; said control system formed such that, in an
event of a malfunction in the power supply system associated with
the said control system, said control system: actuates said
electric motor such that said electric motor obtains electrical
energy from a rotary movement of said rotatably mounted laundry
drum and makes the electrical energy available to said control
system; and actuates said at least one vibration damper in
dependence on the vibratory movement of said laundry treatment
apparatus, which is detected by said vibration sensor, in order to
damp the vibratory movement of said laundry treatment apparatus;
and/or actuates said electric motor to brake the rotary movement of
said rotatably mounted laundry drum.
2. The laundry treatment appliance according to claim 1, further
comprising at least one further sensor detecting at least one of a
rotation speed, a fluctuation in the rotation speed, a torque or a
fluctuation in the torque of said electric motor; and wherein said
control system actuates at least one of said electric motor or said
at least one vibration damper in dependence on a measurement
variable which is detected by said at least one further sensor in
an event of a malfunction in the power supply system associated
with the said control system.
3. The laundry treatment appliance according to claim 1, further
comprising at least one device for detecting a phase position of an
unbalance of said rotatably mounted laundry drum; and wherein said
control system actuates at least one of said electric motor or said
at least one vibration damper in dependence on a detected phase
position of the unbalance in an event of a malfunction in the power
supply system associated with said control system.
4. The laundry treatment appliance according to claim 2, wherein:
said laundry treatment appliance has a door-locking apparatus; and
said control system actuates said door-locking apparatus in
dependence on the measurement variable detected by said at least
one further sensor in an event of the malfunction in the power
supply system associated with said control system.
5. The laundry treatment appliance according to claim 1, wherein
said control system is configured in order to identify a
malfunction in the power supply system associated with said control
system.
6. The laundry treatment appliance according to claim 1, wherein
said at least one vibration damper of said vibration-damping
apparatus is an electrically controllable frictional damper.
7. A method for operating a laundry treatment appliance having a
laundry treatment apparatus with a rotatably mounted laundry drum,
the laundry treatment apparatus being held in a housing of the
laundry treatment appliance such that the laundry treatment
apparatus can move, the laundry treatment appliance further having
an electric motor for driving the rotatably mounted laundry drum in
rotation, a control system for actuating the electric motor and the
control system being connectable to a power supply system, and at
least one vibration-damping apparatus for damping a vibratory
movement of the laundry treatment apparatus, which comprises the
steps of: in an event of a malfunction in the power supply system
associated with the power supply system, performing, via the
control system, the steps of: actuating the electric motor such
that the electric motor obtains electrical energy from a rotary
movement of the rotatably mounted laundry drum and makes the
electrical energy available to the control system; and actuating at
least one vibration damper in dependence on the vibratory movement
of the laundry treatment apparatus to damp the vibratory movement
of the laundry treatment apparatus; and/or actuating the electric
motor to brake the rotary movement of the rotatably mounted laundry
drum.
8. The method according to claim 7, which further comprises
actuating, via the control system, at least one of the electric
motor or the at least one vibration damper in dependence on at
least one of a rotation speed, a fluctuation in rotation speed, a
torque or a fluctuation in torque of the electric motor in an event
of a malfunction in the power supply system associated with the
control system.
9. The method according to claim 7, which further comprises
actuating, via the control system, at least one of the electric
motor or the at least one vibration damper in dependence on a phase
position of an unbalance of the rotatably mounted laundry drum in
an event of a malfunction in the power supply system associated
with the control system.
10. The method according to claim 7, which further comprises
actuating, via the control system, a door-locking apparatus of the
laundry treatment appliance in dependence on one of a rotation
speed or a torque of the electric motor in an event of a
malfunction in the power supply system associated with the control
system.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims the priority, under 35 U.S.C.
.sctn.119, of German application DE 10 2010 027 158.6, filed Jul.
14, 2010; the prior application is herewith incorporated by
reference in its entirety.
BACKGROUND OF THE INVENTION
Field of the Invention
[0002] The present invention relates to a laundry treatment
appliance, in particular a laundry treatment appliance having an
active vibration-damping system.
[0003] A laundry treatment appliance, for example a washing
machine, a tumble dryer or a washer dryer, typically has a washing
tub (also called a wash tub), a laundry drum which is rotatably
mounted in the washing tub, and an electric motor for driving the
laundry drum. The washing tub is held in the housing of the laundry
treatment appliance such that it moves, for example by a plurality
of vibration dampers.
[0004] In a spin-drying cycle of the laundry treatment appliance, a
load which bears against the circumference of the laundry drum and
is non-uniformly distributed can cause undesirable movements of the
washing tub which, when the washing tub is rigidly coupled to the
outer wall of the laundry treatment appliance, can lead to movement
of the laundry treatment appliance, and at least to undesirable
development of noise. The same is also true in a washing cycle due
to a free-falling and rolling load in the laundry drum.
[0005] Various measures for determining an unbalance of this kind
are known in order to be able to react to an unbalance in
spin-drying or washing cycles. The method described in German
patent DE 102 34 053 C1 (corresponding to U.S. Pat. No. 6,973,392)
is based on a measurement of the periodic fluctuation in the
electrical power consumption by the drive motor of the laundry
drum. German patent DE 44 31 846 C2 proposes comparing the torques
of the electric motor which are to be applied in the event of
acceleration of the laundry drum with the torques which are to be
applied in order to maintain a constant rotation speed.
Furthermore, German patent DE 103 45 591 B1 (corresponding to U.S.
patent publication No. 2005/0066450), German patent DE 10 2004 053
216 B3 (corresponding to U.S. patent publication No. 2006/0010936)
and German patent DE 10 2005 037 144 B4 (corresponding to U.S. Pat.
No. 7,921,494) disclose various types of vibration sensors for
detecting vibratory movements of an internal unit, which is
suspended such that it can vibrate, of a laundry treatment
appliance about a center of mass in at least one spatial axis.
[0006] German patent DE 10 2005 037 144 B4 also describes a laundry
treatment appliance in which the internal unit is suspended such
that it can vibrate by at least one spring, which is mounted
between the housing and preferably the upper region of the washing
tub, and at least one frictional damper, which is mounted between
the washing tub and the lower region of a side wall or the base of
the housing. The springs and frictional dampers, together with the
mass of the washing tub and the contents of the washing tub, form
the vibration and damping system of the laundry treatment
appliance.
[0007] Frictional dampers contain, in their simplest form, an outer
body (for example tube) and a tappet, preferably composed of
plastic, which can move in the outer body or coaxially to the outer
body. A rubber-like, porous pad which can be saturated with grease
or a grease-like liquid is, for example, inserted between the
tappet and the outer body. The task of this pad is to increase the
friction between the tappet and the outer body and to convert the
kinetic energy, for example of a washing tub, into frictional
heat.
[0008] The damping behaviour of a frictional damper of this kind is
largely constant. It changes only on account of the pad and the
frictional surfaces heating up, this leading to wearing of the pad
over the course of time. This so-called "settling" can lead to a
reduction in the frictional forces over the service life of the
laundry treatment appliance, as a result of which the damping
effect of the frictional dampers is reduced. The washing tub can
also execute so-called yawing movements which cannot be effectively
suppressed by such frictional dampers given an unfavourable
arrangement.
[0009] In order to avoid the above-described rigid damping
behaviour, frictional dampers have been developed which have
frictional surfaces of different configuration which lead to a
variable vibration damping, with the damping property changing as
the stroke of the tappet increases. The degree of damping is
typically virtually zero in the case of a small stroke and
increases as the deflection of the tappet increases.
[0010] This type of frictional damper is also called a "free-stroke
frictional damper". The properties of these frictional dampers can
be influenced by selecting the contours of the frictional surfaces
and are substantially constant over the service life of the laundry
treatment appliance, apart from natural aging processes. A
free-stroke frictional damper of this kind is described, for
example, in published, non-prosecuted German patent application DE
40 14 166 A1.
[0011] European patent EP 0 878 574 B1 (corresponding to U.S. Pat.
No. 5,907,880) discloses a method for actively damping vibrations
in a laundry treatment appliance. The frictional dampers contain a
magnetorheological medium in this case, it being possible to change
the rheological properties (for example viscosity) of the medium by
applying a magnetic field in order to thus influence the damping
properties of the frictional damper. In the method proposed in this
document, a deviation in the rotation speed of the electric motor
is detected and an actuating signal is generated if the deviation
in rotation speed exceeds a threshold value for this deviation in
rotation speed. This actuating signal generates a magnetic field in
the interior of the frictional damper, the flux density of the
magnetic field being proportional to the actuating signal and
therefore to the magnitude of the deviation in rotation speed.
[0012] However, controllable frictional dampers of this kind have
not been used as standard in laundry treatment appliances to date
since their functionality is lost or greatly restricted in the
event of a power cut because the magnetorheological liquid is
typically of low viscosity if not excited and accordingly cannot
have any or have only poor damping properties. Particularly in the
case of large unbalances, the continued rotation of the laundry
drum in the event of a power cut can further lead to very severe
deflections of the washing tub, and this can lead to damage to the
laundry treatment appliance and cause disturbing noise.
SUMMARY OF THE INVENTION
[0013] It is accordingly an object of the invention to provide a
laundry treatment appliance which overcome the above-mentioned
disadvantages of the prior art methods and devices of this general
type, which has an actively controllable vibration-damping system,
and which laundry treatment appliance also ensures the laundry drum
reliably slows to a stop in the event of a malfunction in the power
supply system.
[0014] The laundry treatment appliance contains a laundry treatment
apparatus having a rotatably mounted laundry drum, with the laundry
treatment apparatus being held in a housing of the laundry
treatment appliance such that it can move. The laundry treatment
appliance further has an electric motor for driving the laundry
drum in rotation, a control system for actuating the electric motor
with it being possible to connect the control system to a power
supply system, at least one vibration sensor for detecting a
vibratory movement of the laundry treatment apparatus, and at least
one vibration-damping apparatus for damping a vibratory movement of
the laundry treatment apparatus. In this case, the
vibration-damping apparatus has at least one controllable vibration
damper which can be actuated by the control system in dependence on
the vibratory movement of the laundry treatment apparatus, which is
detected by the at least one vibration sensor, for the purpose of
changing the vibration-damping properties of the vibration damper.
In addition, the control system is formed in such a way that, in
the event of a malfunction in the power supply system which is
associated with the control system, the control system actuates the
electric motor in such a way that the electric motor obtains
electrical energy from a rotary movement of the laundry drum and
makes this available to the control system, and actuates the at
least one vibration damper in dependence on the vibratory movement
of the laundry treatment apparatus, which is detected by the
vibration sensor, in order to damp a vibratory movement of the
laundry treatment apparatus, and/or actuates the electric motor in
order to brake the rotary movement of the laundry drum.
[0015] The laundry treatment appliance of the invention contains an
actively controllable vibration-damping system. The actively
controllable vibration-damping system is operational only when the
(motor) control system and the vibration-damping system are
supplied with electrical energy. In order to prevent unbalances in
the laundry treatment apparatus damaging the laundry treatment
appliance in the event of a malfunction in the power supply system
(for example a power cut), the vibration-damping system is also
kept operational in the event of a malfunction in the power supply
system of this kind.
[0016] To this end, the (motor) control system is formed in such a
way that, in the event of a malfunction in the power supply system
which is associated with the (motor) control system, the (motor)
control system actuates the electric motor in such a way that the
electric motor obtains electrical energy from a rotary movement of
the laundry drum and makes this available to the control system.
Electric motors can act like a current generator and induce a
voltage in the stator winding on account of the continued rotation
of the laundry drum in the event of a power cut, the voltage being
made available to the control system via the motor connection
lines. Electrical energy can be supplied to the intermediate
circuit of the motor control system given suitable actuation of the
power electronics. Therefore, the motor control system can also
maintain its functionality in the event of a power cut, as long as
kinetic energy is made available by the laundry drum slowing to a
stop.
[0017] Since the main control system of the laundry treatment
appliance stops functioning, typically after a few moments, due to
a lack of energy supply in the event of a power cut, the motor
control system no longer has a communication partner. Therefore,
the motor control system has to be able to make independent
decisions about the continued implementation of suitable safety
measures in the event of a malfunction in the power supply system.
The (motor) control system is therefore configured in such a way
that, in the event of a malfunction in the power supply system, the
(motor) control system actuates the at least one vibration damper
as a function of the vibratory movement of the laundry treatment
apparatus, which is detected by the vibration sensor, in order to
damp a vibratory movement of the laundry treatment apparatus,
and/or actuates the electric motor in order to brake the rotary
movement of the laundry drum.
[0018] In this case, the electrical energy which is induced in the
electric motor is preferably temporarily stored in an
energy-storage device in the electric motor or the motor control
system.
[0019] The "laundry treatment apparatus", sometimes also called the
internal unit in the prior art disclosed in the introductory part,
contains, in particular, the rotatably mounted laundry drum for
accommodating the laundry to be washed and/or dried and also
usually the washing tub or wash tub for accommodating the laundry
drum.
[0020] The "vibration sensor" used may be a sensor for directly
detecting a vibration or a device for determining a vibratory
movement from other measurement variables, such as rotation speed,
torque or power consumption by the electric motor. In one
embodiment, the vibration sensor is a sensor which detects the
movement of the laundry treatment apparatus or the washing tub of
said laundry treatment apparatus.
[0021] The "vibration-damping apparatus" has at least one
(actively) controllable vibration damper. That is to say, the
vibration-damping apparatus can have one, two, three, four or more
controllable vibration dampers and, in addition, further vibration
dampers with invariable damping properties.
[0022] The motor control system is configured according to the
invention in such a way that, in the event of a malfunction in the
power supply system which is associated with the motor control
system, the motor control system actuates the electric motor in
such a way that the electric motor obtains electrical energy from a
rotary movement of the laundry drum and makes this available to the
control system, and actuates the at least one vibration damper in
dependence on the vibratory movement of the laundry treatment
apparatus, which is detected by the vibration sensor, in order to
damp a vibratory movement of the laundry treatment apparatus,
and/or actuates the electric motor in order to brake the rotary
movement of the laundry drum. This means that the electrical energy
obtained by the electric motor is sufficient to further operate the
motor control system and to further detect and evaluate the
measurement values using the vibration sensor in the event of a
malfunction in the power supply system.
[0023] In one refinement of the invention, at least one
rotation-speed and/or torque sensor for detecting a rotation speed,
a fluctuation in rotation speed, a torque and/or a fluctuation in
torque of the electric motor is also provided. The control system
is then additionally formed in such a way that it also actuates the
electric motor and/or the at least one vibration damper as a
function of the measurement variable which is detected by the at
least one rotation-speed and/or torque sensor in the event of a
malfunction in the power supply system which is associated with the
control system.
[0024] In a further refinement of the invention, at least one
device for detecting a phase position of an unbalance of the
laundry drum is also provided. The control system is then
additionally formed in such a way that it also actuates the
electric motor and/or the at least one vibration damper in
dependence on the detected phase position of the unbalance, that is
to say in a phase-dependent manner relative to the position of the
unbalance, in the event of a malfunction in the power supply system
which is associated with the control system. In this case, the
damping properties of the at least one controllable vibration
damper are preferably regulated in advance of the position of the
unbalance of the laundry treatment apparatus.
[0025] Since the respective vibratory movement is known from the at
least one vibration sensor, the respective rotation speed,
fluctuation in rotation speed, torque and/or fluctuation in torque
of the electric motor are known from the rotation-speed and/or
torque sensor and the respective phase position of the unbalance of
the laundry drum is known, the motor control system can also take
the optimum safety measures in the event of a malfunction in the
power supply system in order to prevent damage to the laundry
treatment appliance.
[0026] In a still further refinement of the invention, the laundry
treatment appliance also has a door-locking apparatus. The control
system is then preferably formed in such a way that it actuates the
door-locking apparatus in dependence on the measurement variable
which is detected by the rotation-speed and/or torque sensor, in
the event of a malfunction in the power supply system which is
associated with the control system. In this way, the door-locking
system can be prevented from being released, even in the event of a
power cut, as long as the laundry drum is still rotating or still
rotating too fast.
[0027] Furthermore, the control system is preferably configured in
order to identify a malfunction in the power supply system which is
associated with the control system. In this advantageous
embodiment, the control system can immediately react to a
malfunction in the power supply system and initiate the required
safety measures. A malfunction in the power supply system can
preferably be achieved by monitoring the input voltage and
frequency. Similarly, by virtue of this functionality of the motor
control system, the motor control system itself can identify when
the malfunction in the power supply system is rectified again. In
this case, the motor control system can then optionally
automatically return to normal actuation of the electric motor.
[0028] The at least one controllable vibration damper of the
vibration-damping apparatus is preferably an electrically
controllable frictional damper. The frictional damper is preferably
a frictional damper with a magnetorheological or electroviscous
medium (in particular liquid). However, frictional dampers in which
the frictional forces of two touching frictional surfaces which are
opposite one another can be varied by electromechanically changing
the contact pressure can also be used. Similarly, frictional
dampers in which a passage opening between two adjacent chambers
which are filled with a fluid (for example air or liquid) can be
narrowed or widened in order to change the damping properties can
be used. Instead of the passage opening with a variable opening
cross section, it is also feasible to use a switchable capillary
pore membrane or the like.
[0029] A method for operating a laundry treatment appliance, in
particular the above-described laundry treatment appliance of the
invention, is characterized in that the control system, in the
event of a malfunction in the power supply system which is
associated with the control system, actuates the electric motor in
such a way that the electric motor obtains electrical energy from a
rotary movement of the laundry drum and makes this available to the
control system, and actuates at least one vibration damper in
dependence on a vibratory movement of the laundry treatment
apparatus in order to damp the vibratory movement of the laundry
treatment apparatus, and/or actuates the electric motor in order to
brake the rotary movement of the laundry drum.
[0030] The above embodiments regarding the advantages of the
laundry treatment appliance according to the invention
correspondingly apply to this operating method.
[0031] In one refinement of the invention, the control system also
actuates the electric motor and/or the at least one vibration
damper in dependence on a rotation speed, a fluctuation in rotation
speed, a torque and/or a fluctuation in torque of the electric
motor in the event of a malfunction in the power supply system
which is associated with the control system.
[0032] In a further refinement of the invention, the control system
also actuates the electric motor and/or the at least one vibration
damper in dependence on a phase position of the unbalance of the
laundry drum in the event of a malfunction in the power supply
system which is associated with the control system.
[0033] In a yet further refinement of the invention, the motor
control system also actuates a door-locking apparatus of the
laundry treatment appliance, specifically preferably in dependence
on a rotation speed or a torque of the electric motor, in the event
of a malfunction in the power supply system which is associated
with the control system.
[0034] According to the invention, one or more of the following
safety measures can be taken in a laundry treatment appliance
having an actively controllable vibration-damping system in the
case of a malfunction in the power supply system.
[0035] In the case of small, non-critical unbalance values, the
kinetic energy of the laundry drum can be used to supply energy to
the motor control system for as long as possible. In this case,
only a minimum quantity of energy is drawn from the system and the
laundry drum has a long slow-down time. Secondly, the quantity of
energy drawn can also be maximized and excess energy can be
converted into heat in the windings of the electric motor, so that
rapid braking and accordingly a short slow-down time of the laundry
drum result following a power cut.
[0036] In the case of small, non-critical unbalance values, only a
little energy or no energy at all is required for the controlled
vibration dampers. The system can run largely undamped.
[0037] In the case of relatively large to critical unbalance
values, the energy which is returned to the motor control system is
required to supply energy to the controlled vibration dampers. In
this case, the slow-down time of the laundry drum depends on the
quantity of energy which is required to supply energy first to the
motor control system and sensors and second to the controlled
vibration dampers. This can ensure that the laundry drum slows to a
stop as far as possible in a vibration- and impact-free manner.
[0038] Provided that the quantity of energy required for the motor
control system and the controllable vibration damper does not
correspond to the maximum quantity of energy which can be drawn,
the differential quantity of energy can, as already described
above, be converted into heat in the stator windings of the
electric motor. In this case, the slow-down time of the laundry
drum after a power cut is reduced further.
[0039] No more electrical energy can be obtained when the drum
reaches a standstill. It is not necessary to supply power to the
controllable vibration dampers in this case either. The further run
time of the motor control system now depends only on the remaining
capacity of the intermediate circuit capacitors and can be reduced
by active discharging.
[0040] Provided that the power cut ends again before the drum
reaches a standstill, the motor control system independently makes
a decision about the further rotation-speed profile of the electric
motor. If the current rotation speed is still above a spreading
rotation speed, that is to say the rotation speed at which the
entire load is pressed against the edge of the laundry drum by
centrifugal forces, the rotation speed could be returned to the
original rotation speed, but at least the current rotation speed is
maintained.
[0041] The present invention can be used for any desired laundry
treatment appliances, for example washing machines, tumble dryers
and washer dryers.
[0042] Other features which are considered as characteristic for
the invention are set forth in the appended claims.
[0043] Although the invention is illustrated and described herein
as embodied in a laundry treatment appliance, it is nevertheless
not intended to be limited to the details shown, since various
modifications and structural changes may be made therein without
departing from the spirit of the invention and within the scope and
range of equivalents of the claims.
[0044] The construction and method of operation of the invention,
however, together with additional objects and advantages thereof
will be best understood from the following description of specific
embodiments when read in connection with the accompanying
drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0045] FIG. 1 is a highly simplified block diagram of a laundry
treatment appliance according to one preferred exemplary embodiment
of the invention; and
[0046] FIG. 2 is a highly simplified block diagram of the laundry
treatment appliance according to a further preferred exemplary
embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0047] Referring now to the figures of the drawing in detail and
first, particularly, to FIG. 1 thereof, there is shown a laundry
treatment appliance 5 (for example a washing machine). The laundry
treatment appliance 5 has a washing tub 10 and a laundry drum 12,
which is rotatably mounted in the washing tub 10, for accommodating
the laundry (load) to be treated. The washing tub 10 and the
laundry drum 12 together form a laundry treatment apparatus of the
invention. The laundry drum 12 is preferably equipped with an
apparatus for passive unbalance compensation (for example a
ball-type balancing device).
[0048] The rotation axis of the laundry drum 12 runs, for example,
substantially horizontally (front-loader) or vertically
(top-loader). The laundry drum 12 is driven by an electric motor
14, the drive axle of the electric motor either directly or
indirectly providing driving, for example, by a V-belt.
[0049] The electric motor 14 is driven by a (motor) control system
18 which is connected to a power supply system or a power supply
network 19 for the purpose of supplying energy. In addition, the
washing machine 5 also has a main control system 20 which is
connected to the motor control system 18 and likewise to the power
supply network 19. As an alternative to this, the (motor) control
system 18 can, as illustrated in FIG. 2, be connected to the power
supply network 19 by the main control system 20.
[0050] The laundry treatment apparatus 10-12 is held in the housing
of the washing machine 5 such that it can vibrate. To this end, at
least one spring 22 is provided, the spring preferably being
mounted in the upper region between the washing tub 10 and the
housing. A vibration-damping apparatus is also provided, the
vibration-damping apparatus having at least one vibration damper 24
which is preferably mounted in the lower region between the washing
tub 10 and the housing of the washing machine 5.
[0051] According to the invention, the vibration dampers 24 are
controllable vibration dampers, it being possible for the damping
properties of the vibration dampers to be actively actuated by the
motor control system 18. Whereas these vibration dampers 24 can
also be optionally actuated by the main control system 20 during
normal operation of the washing machine 5, it has to be possible to
actuate the vibration dampers using the motor control system 18 in
the event of a power cut (that is to say a malfunction in the power
supply system 19).
[0052] Frictional dampers with a magnetorheological or
electroviscous medium are preferably used for these controllable
vibration dampers 24. The main control system 20 and the motor
control system 18 can influence a magnetic field or a control
voltage of these frictional dampers 24, this causing a change in
the at least one rheological or electroviscous property of the
medium and therefore the damping properties of the vibration
dampers 24.
[0053] Various measures are provided for monitoring the laundry
treatment apparatus 10-12. The electric motor 14 (or selectively
the motor control system 18 too) is equipped with a rotation-speed
and/or torque sensor 26. The rotation-speed and/or torque sensor 26
detects a rotation speed, a fluctuation in rotation speed, a
torque, a fluctuation in torque or the like of the electric motor
14. The power consumption by the electric motor 14 can be
optionally detected too.
[0054] At least one vibration sensor 28 is also provided in order
to detect a vibratory movement of the laundry treatment apparatus
10-12 in at least one spatial direction. In principle, any desired
sensors and devices which are known or will become known to a
person skilled in the art and which measure at least one of the
physical units travel/distance, speed or acceleration can be used
for this purpose. An acceleration sensor can preferably be used as
the vibration sensor 28.
[0055] The measurement results from the rotation-speed and/or
torque sensor 26 and from the vibration sensor 28 are made
available to the motor control system 18 which then actuates
firstly the electric motor 14 and secondly the at least one
controllable vibration damper 24 in accordance with these
measurement results and possibly other conditions (for example
current washing program etc.). Furthermore, the motor control
system 18 can also actuate a door-locking apparatus 32, so that the
washing machine door can be opened only when the laundry drum 12 is
no longer rotating or no longer rotating too quickly.
[0056] During normal operation, that is to say with a functioning
power supply system, the main control system 20 and the motor
control system 18 are supplied with electrical energy by the power
supply network 19 directly (FIG. 1) or in series (FIG. 2), and the
electric motor 14, the vibration dampers 24 and the sensors 26, 28
are supplied with electrical energy by the power supply network 19
via the motor control system 18. In the event of a malfunction in
the power supply system 19 (for example power cut), the main
control system 20 stops operating after a few moments and the
electric motor 14 is no longer supplied with power either. In other
words, there is no longer any flow 30 of energy to the electric
motor 14.
[0057] The motor control system 18 is formed in such a way that it
identifies a power cut of this kind, for example on the basis of
the input voltage and frequency of the power supply network, and
accordingly can initiate suitable safety measures. Firstly, the
motor control system 18 actuates the electric motor 14 such that
the electric motor functions as a generator and the kinetic
rotation energy of the slowing-down laundry drum is converted into
electrical energy in order to make this electrical energy available
to the motor control system 18, the controllable vibration dampers
24, the sensors 26, 28 and the door-locking apparatus 32 (flow 30
of energy in the direction of the motor control system 18). In this
case, the electrical energy induced in the electric motor 14 is
preferably temporarily stored in an energy-storage device of the
electric motor 14 or the motor control system 18.
[0058] In this way, "emergency operation" of the motor control
system 18 is also ensured in the event of a power cut. The motor
control system 18 can therefore ensure, in the case of a
slowing-down laundry drum 12, that the laundry drum does not cause
any damage to the washing machine even when there is an unbalance.
In particular, the motor control system 18 can also actuate the
controllable vibration dampers 24 for damping a vibratory movement
of the laundry treatment apparatus 10-12 and/or brake the electric
motor 14. The motor control system 18 can preferably derive
actuating variables for at least one vibration damper 24 and the
electric motor 14 from the measurement variables of a fluctuation
in rotation speed and/or power, a phase position of an unbalance
and a movement of the washing tub.
* * * * *