Note: Descriptions are shown in the official language in which they were submitted.
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A refrigerator unit and/or a freezer unit as well as a method for the control
thereof
The present invention relates to a refrigerator unit and/or freezer unit
comprising a
refrigerant circuit, which has a compressor, a condenser, at least one
capillary tube
as well as at least one evaporator, and a control device for the control of
the
refrigerant flow through the refrigerant circuit.
The invention further relates to a method for the control of such a
refrigerator unit
and/or freezer unit, wherein at least one operating parameter and/or ambient
parameter of the refrigerator unit and/or freezer unit is detected and the
refrigerant
flow is controlled by the refrigerant circuit in dependence on the detected
operating
parameter and/or ambient parameter.
As a rule, valves such as monostable or bistable solenoid valves or also motor-
driven valves are used for the control of the refrigerant flow through the
refrigerant
circuit of refrigerator and/or freezer units. DE 36 01 817 A1, for example,
shows a
regulator apparatus for the refrigerant inflow to the evaporator of such a
refrigerant
circuit, said regulator apparatus comprising an expansion valve actuable by an
electrical actuating motor. DE 33 24 590 C2, in contrast, shows an
electromagnetic
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on/off valve with whose aid the refrigerant flow can be selectively guided to
a
freezer compartment evaporator or to a refrigerator compartment evaporator of
a
refrigerator and/or freezer unit. The moving valve body is problematic, on the
one
hand, with such valves for the control of the refrigerant flow. This can
result in
functional disturbances or unwanted noises. The additional connection points,
which are caused by the installation of the valves into the refrigerant
circuit, are
furthermore problematic with such valves. They are expensive, on the one hand,
and moreover bring along the risk of a potential leak. In addition, relatively
high
component costs result due to the valves.
The present invention wants to provide a remedy here. It is its underlying
object to
provide an improved refrigerator and/or freezer unit as well as an improved
method
for the control of such a refrigerator and/or freezer unit which avoid the
disadvantages of the prior art and further develop the latter in an
advantageous
manner. An improved control of the refrigerant flow with a reduced risk of
leaking,
which works without noise, should preferably be achieved with simple means.
This object is solved in accordance with the invention by a refrigerator unit
and/or
freezer unit in accordance with claim 1. The object is solved in a technical
method
aspect by a method in accordance with claim 16. Preferred aspects of the
invention
are the subject of the dependent claims.
It is therefore proposed in accordance with the invention to control the
refrigerant
flow in that the capillary tube is heated by means of a heating device and
thereby
causing the refrigerant flowing through the capillary tube to evaporate. The
invention is based on the recognition that vapor produced in the capillary
tube can
considerably reduce and optionally completely prevent the flow of the
refrigerant
through the capillary tube. The greater the evaporation produced in the
capillary
tube, the lower the remaining refrigerant flow through the capillary tube.
In a further development of the invention, the control of the refrigerant flow
can
completely dispense with flow regulation valves and on/off valves. The control
of
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the refrigerant flow can be effected solely by the heating of the capillary
tube or of a
plurality of capillary tubes and by the evaporation of the refrigerant
therein.
Additional connection points in the refrigerant circuit such as would be
required for
the installation of valves are thereby omitted. The risk of leaking can be
reduced
accordingly. In addition, the switching noises usually arising with valves are
eliminated. The control of the refrigerant flow can be carried out completely
free of
noise. In addition, lower costs can be achieved in comparison with a valve
solution
since the heating device is much cheaper in comparison with the relatively
expensive valves.
In an alternative further development of the invention, the control of the
refrigerant
flow can also take place by a combination of flow regulator valves and on/off
valves,
on the one hand, and of the heating of the capillary tube or of a plurality of
capillary
tubes, on the other hand. A greater variability of the control possibilities
can thereby
optionally be achieved. The previously described performance possibility with
a
complete omission of control valves, however, has clear advantages with
respect to
the costs, the risk of leaking and the forming of noise.
In accordance with an advantageous embodiment of the invention, the heating
device is arranged at the end section of the respective capillary tube at the
downstream side. If the capillary tube is heated directly in front of the
injection
position at its end, a particularly efficient control of the refrigerant flow
can be
achieved.
In an alternative embodiment of the invention, the heating device is arranged
at the
upstream end section of the respective capillary tube. Surprisingly, the
refrigerant
flow can already be controlled extremely precisely by heating the inlet
section of the
capillary tube.
The heating device itself can generally have different designs. In accordance
with
an advantageous embodiment of the invention, a resistance heating with
relatively
low power can be used which is seated in the respective capillary tube.
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The heating output introduced into the capillary tube and/or the temperature
of the
capillary tube can preferably be changed in at least a plurality of steps, in
particular
in a stepless manner. A stepless control of the refrigerant flow through the
refrigerant circuit can thereby optionally be achieved. If the capillary tube
is only
heated slightly above the point at which vapor formation occurs, a remaining
refrigerant flow can still pass through the capillary tube. If, in contrast,
the capillary
tube is heated more and more strongly and if the vapor formation is
accordingly
increased more and more, less and less refrigerant can pass through the
capillary
tube.
In a further development of the invention, the heating device is made with
stepless
temperature control for this purpose and can be controlled accordingly by the
control device which can have a temperature regulator or a temperature control
module for this purpose. Alternatively or additionally, provision can also be
made to
change the length of the heated capillary tube section, for example by
switching in
further heating elements, and to thereby influence the vapor formation.
The heating output of the heating device can be controlled in dependence on
different operating parameters of the refrigerator unit and/or freezer unit.
An
evaporator temperature, a refrigerator compartment temperature, a freezer
compartment temperature and/or the ambient temperature of the refrigerator
unit
and/or freezer unit is preferably detected by means of at least one
temperature
sensor. The control device controls the heating device in dependence on the
temperature detected in order to control the refrigerant flow accordingly.
Alternatively or additionally, the duty cycle of the compressor of the
refrigerant
circuit can also detected as an operating parameter and the heating device can
be
controlled in dependence on the detected duty cycle.
The control of the refrigerant flow can be used particularly advantageously by
heating the capillary tube and producing vapor in the capillary tube in
refrigerator
units and/or freezer units with different temperature zones, in particular if
different
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evaporators are provided for the corresponding temperature zones. The unit
can,
for example, have a freezer compartment evaporator and a refrigerator
compartment evaporator which are advantageously connected in succession such
that the refrigerant first circulates through the freezer compartment
evaporator and
then through the refrigerator compartment evaporator.
In particular only one single capillary tube with a heating device associated
with it is
provided in the named arrangement in which the refrigerant first flows through
the
freezer compartment evaporator and then through the refrigerator compartment
evaporator. By the heating of the capillary tube provided upstream of the
freezer
compartment evaporator, the refrigerant amount entering into the freezer
compartment evaporator can be reduced as required, whereby the refrigerant
amount is optionally consumed, so-to-say, completely in the freezer
compartment
evaporator and the downstream refrigerator section evaporator does not undergo
any further cooling. With such a minimal solution, which is extremely cost-
favorable
in manufacture, the problem regularly occurs in the prior art that either the
freezer
compartment is not operated coldly enough or the refrigerator section is
operated
too coldly depending on the ambient temperature. This problem can be
eliminated
in a simple manner by the heating of the capillary tube disposed in front of
the
freezer section evaporator.
By a direct bringing about of a deficiency in refrigerant and by corresponding
running times, a desired temperature difference can be established between the
refrigerator compartment and the freezer compartment. This solution has the
advantage with respect to the current winter circuit with a lamp circuit or
heating in
the interior of the unit that no heating of the interior space is necessary,
whereby
energetic advantages result and disadvantages for the stored foodstuffs are
avoided.
In accordance with a further advantageous embodiment of the invention, the
refrigerator circuit can also be configured such that the refrigerant first
flows through
the refrigerator section evaporator and then through the freezer section
evaporator.
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In this case, two separate capillary tubes and respective associated heating
devices
are advantageously provided. In this process, the two capillary tubes are
preferably
connected in parallel with one another. The refrigerant amount flowing into
the
refrigerator section evaporator can be controlled in a suitable manner via the
one
capillary tube, which is connected directly in front of the refrigerator
section
evaporator, or before the heating of this capillary tube, in order to achieve
the
desired temperature of the refrigerator section. The refrigerant flowing out
of the
refrigerator section evaporator is then guided directly into the freezer
section
evaporator. Since the cold output which can thereby be achieved will, however,
not
be sufficient for the freezer section evaporator, additional refrigerant can
be guided
into the freezer section evaporator via the capillary tube connected in
parallel. The
said capillary tube connected in parallel picks up the refrigerant upstream of
the
other capillary tube. The refrigerant amount flowing through the freezer
section
evaporator can be finely adjusted in this process by heating the capillary
tube
connected in parallel.
The invention will be explained in more detail in the following with respect
to a
preferred embodiment and to associated drawings. There are shown in the
drawings:
Fig. 1: a schematic sectional view of a refrigerator unit and/or freezer unit
whose freezer compartment is cooled using a freezer compartment
evaporator and whose refrigerator compartment is cooled using a
refrigerator compartment evaporator.
Fig. 2: a schematic representation of the refrigerant circuit of the
refrigerator unit
and/or freezer circuit of Fig. 1; and
Fig. 3: a schematic representation of a refrigerant circuit of the
refrigerator unit
and/or freezer unit of Fig. 1 in accordance with a further preferred
embodiment of the invention.
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A refrigerator unit and/or freezer unit 1 is drawn in Fig. 1 whose unit body 2
can be
closed by a throughgoing unit door 3. The interior space of the unit body 2 is
divided into a freezer compartment 4 and a refrigerator compartment 5, with
the
freezer compartment 4 being closable by an inner door 6 in the embodiment
shown.
Storage trays 7 and a drawer-like vegetable pull-out 8 are arranged in a known
manner in the refrigerator compartment 5.
The freezer compartment 4 is cooled by a freezer compartment evaporator 9
which
can surround the freezer compartment 4 on five sides. The refrigerator
compartment 5, in contrast, is cooled by a refrigerator compartment evaporator
10
which extends at the rear wall of the refrigerator compartment 5.
As Fig. 2 shows, the freezer compartment evaporator 9 and the refrigerator
compartment evaporator 10 are part of a refrigerant circuit 11 which moreover
comprises a compressor 12, a condenser 13 as well as a capillary tube 14
upstream of the two evaporators 9 and 10. In the embodiment shown, the freezer
compartment evaporator 9 is arranged upstream of the refrigerator compartment
evaporator 10. As Fig. 2 shows, the two evaporators 9 ad 10 are connected
sequentially in series so that the refrigerant flowing out of the freezer
section
evaporator 9 is guided into the refrigerator section evaporator 10. A
capillary tube
14 is only provided upstream of the freezer section evaporator 9 arranged
upstream.
The capillary tube 14 is provided with a heating device 16 whose heating
elements
can each heat the end section of the respective capillary tubes 14 and 15 at
the
downstream side. In accordance with the embodiment shown in accordance with
Fig. 2, the heating device 16 can advantageously also be arranged at the end
of the
capillary tube at the upstream side, whereby a very precise control of the
refrigerant
passage can be achieved. The heating device 16 can be a simple resistance
heating element and can advantageously be temperature regulated in a stepless
manner. For this purpose, the heating device 16 is controllable by a
temperature
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control module of an electronic control device 18 which, in another respect,
also
controls the operation of the compressor 12.
In the embodiment shown, the refrigerant flowing out of the condenser first
flows
into the capillary tube 14 arranged in front of the freezer compartment
evaporator 9.
If this capillary tube 14 is not heated, the refrigerant flows in a
conventional manner
into the freezer compartment evaporator 9. The refrigerant leaving the freezer
compartment evaporator 9 then flows to the refrigerator compartment evaporator
10. If, in contrast, the capillary tube 14 connected before the freezer
compartment
evaporator 9 is heated by the heating device 16 and vapor is produced in the
capillary tube 14, the refrigerant passage through the capillary tube 14
optionally
reduces toward zero. An undercooling of the refrigerator section can thereby
be
prevented. If the refrigerant amount is correspondingly reduced by heating the
capillary tube 14, the remaining refrigerant amount entering into the freezer
section
evaporator 9 is evaporated there and consumed, so-to-say, such that a further
cooling of the freezer section evaporator 10 is prevented or correspondingly
reduced.
As Fig. 2 shows, the control device 18 can be connected to a plurality of
temperature sensors 21 and 22 which measure the refrigerator compartment
evaporator temperature or the refrigerator compartment temperature and/or the
ambient temperature. The control device 18 controls the heating device 16 and
the
compressor 12 in dependence on the temperatures detected. The control device
18
advantageously only has to take account of one further operating parameter or
ambient parameter, in addition to the refrigerator section evaporator
temperature or
the refrigerator compartment temperature, which is detected by the temperature
sensor 21, for the control of the heating device 16 and thus the control of
the
refrigerant inflow into the freezer section evaporator 9. This can be the
ambient
temperature which, as shown in Fig. 2, can be detected with an ambient
temperature sensor 22. Alternatively or additionally, the freezer section
evaporator
temperature or the freezer compartment temperature can, however, also be used
as the second operating parameter. In this case, the control device 18 would
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include a corresponding freezer section temperature sensor. Alternatively or
additionally, however, it would also be possible to control the heating device
16 in
dependence on the relative duty cycle of the compressor 12.
Fig. 3 shows an alternative embodiment of the invention. The refrigerant
circuit 11
here likewise includes the refrigerator compartment evaporator 10 and freezer
compartment evaporator 9 connected to one another in series, with, however the
refrigerator compartment evaporator 10 being arranged upstream of the freezer
compartment evaporator 9 in this embodiment. The refrigerant circuit 11
naturally
also includes a compressor 12 and a condenser 13 here.
As Fig. 3 shows, two capillary tubes 14 and 15 a well as heating devices 16
and 17
associated with them are used in this embodiment for the control of the
refrigerant
flow through the two evaporators 9 and 10. The first capillary tube 14 is
connected
directly in front of the refrigerator compartment evaporator 10. The
refrigerant line
branches upstream of the said capillary tube 14. At the distributor point 18,
a
bypass line leading around the refrigerator compartment evaporator 10 branches
off
and leads to the capillary tube 15 which is connected in parallel and with
which the
second heating device 17 is associated. As Fig. 3 shows, the capillary tube 15
opens into the freezer compartment evaporator 9.
In this configuration of the refrigerant circuit 11, a precise control of the
desired
temperature difference of the two evaporators can be achieved: The refrigerant
flow
which should enter into the refrigerator compartment evaporator 10 can be
controlled precisely via the heating of the capillary tube 14 using the
heating device
16. The refrigerant flow leaving the refrigerator compartment evaporator 10
then
flows through the freezer compartment evaporator 9. If this refrigerant flow
is not
sufficient for the cooling of the freezer compartment evaporator 9 to the
desired
temperature, which will be the case as a rule, additional refrigerant is
guided into
the freezer compartment evaporator 9 via the capillary tube 15 connected in
parallel. The refrigerant amount supplied in this process can be controlled
precisely
by the heating of the capillary tube 15 via the second heating device 17.
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The two heating devices 16 and 17 are also controlled by the control device 18
here. The latter is connected to temperature sensors 20 and 21 by means of
which
the temperatures in the refrigerator compartment and in the freezer
compartment or
in the refrigerator compartment evaporator and freezer compartment evaporator
are
detected.
