U.S. patent application number 12/317275 was filed with the patent office on 2009-06-25 for household laundry appliance fitted with a lifting magnet.
This patent application is currently assigned to BSH Bosch und Siemens Hausgeraete GmbH. Invention is credited to Piotr Gorny, Guido Sattler, Gunter Steffens.
Application Number | 20090158609 12/317275 |
Document ID | / |
Family ID | 40589633 |
Filed Date | 2009-06-25 |
United States Patent
Application |
20090158609 |
Kind Code |
A1 |
Gorny; Piotr ; et
al. |
June 25, 2009 |
Household laundry appliance fitted with a lifting magnet
Abstract
The tumble drying device has a heat pump with a lifting magnet,
with a rinsing valve of the heat pump being connectable by means of
the lifting magnet, with the lifting magnet and a PTC resistor with
a non-linear resistance curve being connected in series, with it
being possible to heat up the PTC resistor by means of a current
flow and said PTC resistor being highly resistive when a
predetermined limit temperature is exceeded and with the limit
temperature being adjusted such that it is reached before a
permissible on-time of the lifting magnet is exceeded.
Inventors: |
Gorny; Piotr; (Sycow,
PL) ; Sattler; Guido; (Falkensee, DE) ;
Steffens; Gunter; (Dallgow-Doberitz, 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
Munchen
DE
|
Family ID: |
40589633 |
Appl. No.: |
12/317275 |
Filed: |
December 19, 2008 |
Current U.S.
Class: |
34/108 |
Current CPC
Class: |
D06F 58/22 20130101;
D06F 58/30 20200201; D06F 2103/00 20200201 |
Class at
Publication: |
34/108 |
International
Class: |
D06F 58/02 20060101
D06F058/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 21, 2007 |
DE |
10 2007 061 984.9 |
Claims
1. A tumble drying device with a heat pump, comprising: a lifting
magnet; a rinsing valve connectable by the lifting magnet; and a
PTC resister with a non-linear resistance curve connected in series
with the lifting magnet, the PTC resistor being heatable by a
current flow and being highly resistive if a pre-determined limit
temperature is exceeded, the pre-determined limit temperature being
reached before exceeding a permissible on-time duration of the
lifting magnet.
2. The tumble drying device of claim 1, further comprising an
electronic controller connected to and for actuating the lifting
magnet.
3. The tumble drying device of claim 1, wherein a correct
activation of the lifting magnet heats up the PTC resistor to a
temperature below the limit temperature.
4. The tumble drying device of claim 1, wherein a correct
activation of the lifting magnet takes place within a period of
approximately 5-10 seconds.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates to a domestic appliance embodied as a
tumble drying device with a lifting magnet, in particular a heat
pump dryer.
[0002] Tumble drying devices, which are currently of interest, are
described in the documents WO 2008/119611 A1, WO 2007/093461 A1, WO
2007/093467 A1, as well as in WO 2007/093468 A1. Each of these
tumble drying devices has a heat pump, which has a component loaded
with dirt in the form of lint, which accumulates during a tumble
drying process. This component is the heat sink, at which the heat
pump absorbs heat from its passing process air stream. Fine lint
deposits there, which has to be regularly removed. To this end, a
cleaning device is present in each instance, which regularly cleans
the loaded components and/or the region of the heat pump, in which
this component is arranged, with the aid of rinsing fluid. The
rinsing fluid is supplied by means of a correspondingly provided
channel with the aid of a rinsing valve to be opened at a given
time as well as further components which are described in detail in
each instance.
SUMMARY OF THE INVENTION
[0003] Lifting magnets are frequently used as the drive to activate
switching processes. To optimize cost and installation space,
lifting magnets can be used, which only have a restricted on-time
duration (e.g. of 10%). Exceeding the permissible on-time duration,
e.g. in the event of a faulty actuation, can result in the lifting
magnet being damaged, as a result of which safety requirements can
in some instances not be fulfilled. To observe safety regulations,
a complicated "functional safety" or a temperature protector could
previously be used in the lifting magnet coil. However, these
solutions are comparatively complicated and expensive. Introducing
a protector into the coil may possibly represent significant
additional expenses, since this is generally not provided in a
production facility.
[0004] It is thus an object of the present invention to provide a
cost-effective and reliable possibility of protecting a lifting
magnet against an excessive power supply.
[0005] The domestic appliance embodied as a tumble drying device
includes a heat pump with a lifting magnet, with a rinsing valve of
the heat pump being connectable by means of the lifting magnet. The
lifting magnet and a PTC resistor with a nonlinear resistance curve
are connected in series, with it being possible to heat up the PTC
resistor by means of a current flow and said PTC resistor being
highly resistive in the case of a predetermined limit temperature
being exceeded and with the limit temperature being adjusted such
that it is reached before a permissible on-time duration of the
lifting magnet is exceeded. As a result of the PTC resistor being
able to be heated up by means of the current flow and being highly
resistive if the limit temperature is exceeded, the current is
limited to a degree which is noncritical to the lifting magnet.
[0006] The scope of the invention does not necessarily depend on
the embodiment of the heat pump. The heat pump currently has a heat
source, which is used to heat up a process air stream for the
drying process and a heat sink, which is used to cool down the
process air stream. In this way, heat, which the heat pump absorbs
in the heat sink, is pumped to the heat source and is output there
again in the event of an increase in temperature. Details relating
to the embodiment of a heat pump result from the documents cited in
the introduction, to which reference is made here in its
entirety.
[0007] The invention is not necessarily restricted to a special
function of the rinsing valve. The application of the invention to
a rinsing valve is however currently of particular interest, said
rinsing valve being used to this end to supply a rinsing fluid to a
region of the heat pump loaded with dirt for the purpose of rinsing
and removal. The dirt may be lint, such as accumulates in the
region of the heat sink, at which moisture from an air stream
loaded with steam and lint is condensed out, said air stream
flowing around the heat sink, and correctly adheres to the heat
sink as a result of the presence of moisture.
[0008] The following advantages are achieved by introducing the PTC
resistor: a cost-effective lifting magnet with a reduced on-time
duration can be used and a complicated safety circuit is dispensed
with on the electronics system. A temperature protector in the
lifting magnet coil can also be omitted.
[0009] The PTC resistor can be embodied for instance as a PTC
resistor based on ceramics, e.g. with barium titanium or based on
polymers, e.g. with a sooty particle-filled plastic.
[0010] It is advantageous for the simple and precise switching of
the lifting magnet for the lifting magnet to be connected to an
electronic controller for its actuation.
[0011] It is also advantageous if the limit temperature is adjusted
such that a correct activation of the lifting magnet heats up the
PTC resistor to a temperature below the limit temperature. In other
words, the dimensioning of the PTC resistor is then effected such
that the inrush current and the working current of the lifting
magnet do not allow the PTC resistor to be highly resistive within
the necessary time interval.
[0012] A domestic appliance is also preferable, in which a correct
activation takes place within a period of approximately 5-10
seconds.
[0013] The domestic appliance may be present as a washer dryer or
as a separate dryer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] The invention is illustrated schematically below with
reference to an exemplary embodiment.
[0015] FIG. 1 shows a circuit diagram for operating a lifting
magnet in a heat pump dryer.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT
INVENTION
[0016] FIG. 1 shows a tumble drying device 7 with a heat pump 8,
with the heat pump 8 being equipped with a rinsing valve 9. The
rinsing valve 9 is used to clear a channel through which rinsing
fluid is supplied to a region of the heat pump 8 which is loaded
with lint, in particular the region in which the heat sink of the
heat pump 8 is arranged, for lint rinsing and removal purposes. The
heat pump 8 is currently only shown schematically, since it does
not essentially depend on its inner design for the present
description. In any case, the heat pump 8 has a heat source, which
is currently used to heat up a process air stream for the drying
process and a heat sink, which is used to cool down the process air
stream. In this way, heat, which the heat pump 8 absorbs in the
heat sink, is pumped to the heat source and output there again in
the case of an increase in temperature.
[0017] A lifting magnet 4 is used to connect the rinsing valve 9.
Two alternating current power supply terminals 1, 2 are connected
in series in order to actuate the lifting magnet 4:
(i) a switching relay 3 for the optional opening and closing of an
associated current circuit which can be supplied by means of the
alternating current power supply terminals 1, 2, (ii) the
current-controlled lifting magnet 4 and (iii) a PTC; ("Positive
Temperature Coefficient"-) resistor 5.
[0018] The switching relay 3 is activated by means of an electronic
circuit 6, which has a microcontroller. The lifting magnet 4 is
mechanically connected to the rinsing valve 9 for the opening and
closing thereof.
[0019] The activation of the lifting magnet 4 only needs to take
place for a period of approximately 5-10 s. Pause times of several
minutes are then provided. To optimize cost and installation space,
a lifting magnet 4 is used, which only has a limited permissible
on-time duration (ED) of e.g. 10%. If the permissible on-time
duration is exceeded, this may lead to the lifting magnet 4 being
damaged or safety regulations not being observed.
[0020] The PTC resistor 5 has a non-linear resistance curve,
whereby below a predefined limit temperature, an ohmic resistance
is typically comparatively low and only changes marginally, while
above the limit temperature, the PTC resistor is rapidly highly
resistive. The PTC resistor 5 can be heated up by means of a
current flow passing therethrough. The limit temperature is
adjusted such that it is reached before a permissible on-time
duration of the lifting magnet is exceeded, while, in the case of a
correct activation (inrush current and working current) of the
lifting magnet of approximately 5-10 seconds here, the PTC resistor
is only heated up to a temperature below the limit temperature.
[0021] When the switching relay 3 is closed, current flows through
the current circuit and firstly allows the lifting magnet 4 to
connect and secondly heats up the PTC resistor 5. With a correct
and/or proper actuation of the switching relay 3, the PTC resistor
5 remains low resistive, and the limit temperature is not reached
by means of the currents. In the case of a fault, it may however
occur that the switching relay 3 closes for longer. If the
temperature in the PTC resistor 5 then reaches the limit
temperature, which occurs before a permissible on-time duration of
the lifting magnet 4 is exceeded, the PTC resistor 5 is highly
resistive and limits the current flow through the current circuit,
as a result of which the lifting magnet 4 is protected against
damage.
* * * * *