U.S. patent application number 14/354193 was filed with the patent office on 2014-10-02 for laundry dryer with a heat pump system.
This patent application is currently assigned to ELECTROLUX HOME PRODUCTS CORPORATION N.V.. The applicant listed for this patent is Electrolux Home Products Corporation N.V.. Invention is credited to Alberto Bison, Francesco Cavarretta.
Application Number | 20140290091 14/354193 |
Document ID | / |
Family ID | 47191688 |
Filed Date | 2014-10-02 |
United States Patent
Application |
20140290091 |
Kind Code |
A1 |
Bison; Alberto ; et
al. |
October 2, 2014 |
Laundry Dryer with a Heat Pump System
Abstract
Laundry dryer, with a heat pump system, said heat pump system
comprises a refrigerant circuit (10) for a refrigerant and an
drying air stream circuit (12) for the drying air stream, wherein
the refrigerant circuit (10) includes a compressor (14) with
variable output, a first heat exchanger (16), variable expansion
means (18) and a second heat exchanger (20) connected in series and
forming a closed loop, the drying air stream circuit (12) includes
the first heat exchanger (16), the second heat exchanger (20), a
laundry treatment chamber (22) and at least one air stream fan
(24), the refrigerant circuit (10) and the air stream circuit (12)
are thermally coupled by the first heat exchanger (16) and the
second heat exchanger (20), the first heat exchanger (16) is
provided for heating up the air stream and cooling down the
refrigerant, and the second heat exchanger (20) is provided for
cooling down the air stream and heating up the refrigerant, wherein
a control unit (38) is provided to adjust the variable expansion
means (18), wherein the control unit (38) is adapted to adjust the
variable expansion means (18) in response to at least a compressor
quantity representative of the operation of the compressor (14)
and/or in response to the drying cycle selected by the user,
wherein said quantity is at least one of the following rotational
speed of the compressor (14), supply current/voltage frequency of
the compressor motor, absorbed power or current of the compressor
(14).
Inventors: |
Bison; Alberto; (Pordenone,
IT) ; Cavarretta; Francesco; (Pordenone, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Electrolux Home Products Corporation N.V. |
Brussel |
|
BE |
|
|
Assignee: |
ELECTROLUX HOME PRODUCTS
CORPORATION N.V.
Brussel
BE
|
Family ID: |
47191688 |
Appl. No.: |
14/354193 |
Filed: |
October 24, 2012 |
PCT Filed: |
October 24, 2012 |
PCT NO: |
PCT/EP2012/004447 |
371 Date: |
April 25, 2014 |
Current U.S.
Class: |
34/524 |
Current CPC
Class: |
D06F 2103/00 20200201;
D06F 2103/50 20200201; D06F 58/206 20130101; D06F 2105/26 20200201;
D06F 58/30 20200201 |
Class at
Publication: |
34/524 |
International
Class: |
D06F 58/28 20060101
D06F058/28; D06F 58/20 20060101 D06F058/20 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 25, 2011 |
EP |
11186571.3 |
Claims
1. A laundry dryer with a heat pump system, said heat pump system
comprises a refrigerant circuit (10) for a refrigerant and an
drying air stream circuit (12) for the drying air stream, wherein
the refrigerant circuit (10) includes a compressor (14) with
variable output, a first heat exchanger (16), variable expansion
means (18) and a second heat exchanger (20) connected in series and
forming a closed loop, the drying air stream circuit (12) includes
the first heat exchanger (16), the second heat exchanger (20), a
laundry treatment chamber (22) and at least one air stream fan
(24), the refrigerant circuit (10) and the air stream circuit (12)
are thermally coupled by the first heat exchanger (16) and the
second heat exchanger (20), the first heat exchanger (16) is
provided for heating up the air stream and cooling down the
refrigerant, and the second heat exchanger (20) is provided for
cooling down the air stream and heating up the refrigerant, wherein
a control unit (38) is provided to adjust the variable expansion
means (18), characterized in, that the control unit (38) is adapted
to adjust the variable expansion means (18) in response to at least
a compressor quantity representative of the operation of the
compressor (14) and/or in response to the drying cycle selected by
the user, wherein said quantity is at least one of the following:
rotational speed of the compressor (14), supply current/voltage
frequency of the compressor motor absorbed power or current of the
compressor (14).
2. Laundry dryer according to claim 1, wherein the control unit
(38) is adapted to monitor or determine at least one of the
compressor quantity and to operate the variable expansion means
(18) accordingly.
3. Laundry dryer according to claim 2, wherein the control unit
(38) is adapted to receive signals representative of at least one
of the compressor quantity or the control unit (38) is adapted to
receive signal representative of predetermined parameters, which
are the basis for the determination of at least one of the
compressor quantity.
4. Laundry dryer according to any of the preceding claims, wherein
the control unit (38) is adapted to set the variable expansion
means (18) to a reduced lamination work, when the at least one of
the compressor quantity is high or starts to increase or increases,
the control unit (38) is adapted to set the variable expansion
means (18) to an increased lamination work, when the at least one
of the compressor quantity is low or starts to decrease or
decreases.
5. Laundry dryer according to claim 1, comprising at least one
drying cycle, in which the compressor (14) operates at different
outputs, and/or comprising different drying cycles, wherein the at
least one of the compressor quantity is constant or substantially
constant in each drying cycle, but different from drying cycle to
drying cycle, wherein the control unit (38) adjusts the variable
expansion means (18) according to the drying cycle selected by the
user.
6. Laundry dryer according to claim 5, wherein the control unit
(38) is adapted to set the variable expansion means (18) to a
reduced lamination work according to an increasing of the at least
one of the compressor quantity for the selected drying cycle and to
set the variable expansion means (18) to an increased lamination
work according to a decreasing of at least one of the compressor
quantity for the selected drying cycle.
7. Laundry dryer according to claim 5 or 6, wherein the control
unit (38) actuates the compressor (14) to increase the at least one
of the compressor quantity according to the selected drying cycle,
and automatically actuates the variable expansion means (18) to a
reduced lamination work, further wherein the control unit (38)
actuates the compressor to decrease the at least one of the
compressor quantity according to selected drying cycle, and
automatically actuates the variable expansion means (18) to an
increased lamination work.
8. Laundry dryer according to any of the preceding claims, wherein
the variable expansion means (18) comprise at least two capillary
tubes (28, 30), wherein at least one of said capillary tubes (28,
30) is switched or switchable by at least one valve (26; 32, 34;
36).
9. Laundry dryer according to claim 8, wherein the expansion means
(18) comprises at least two parallel series of a capillary tube
(28, 30) and a corresponding on-off valve (32, 34) in each case,
wherein the capillary tubes (28, 30) have different lengths and/or
different cross-sections.
10. Laundry dryer according to claim 8, wherein the expansion means
(18) comprises at least two serial capillary tubes (28, 30),
wherein at least one of the capillary tubes (28, 30) is bypassed by
an on-off valve (36).
11. Laundry dryer according to any of the preceding claims 8-10,
wherein the capillary tubes (28, 30) have different lengths and/or
different cross-sections.
12. Laundry dryer according any of the preceding claims 8-10,
wherein the capillary tubes (28, 30) have the same lengths and
cross-sections.
13. Laundry dryer according to any of the preceding claims 8-12,
wherein the expansion means (18) comprises two capillary tubes (28,
30) and a three-way valve (26), wherein the capillary tubes (28,
30) are alternatingly switchable by the three-way valve (26) and
the capillary tubes (28, 30) have different lengths and/or
different cross-sections.
14. Laundry dryer according any of the preceding claims 1-7,
wherein the expansion means (18) comprises at least one lamination
valve including a variable opening degree, so the pressure drop at
said expansion means (18) is adjustable.
15. The laundry dryer according to any one of the claims, wherein
the control unit (38) is provided for adapting the lamination work
at the expansion means (18) to a warm-up phase and a steady state
phase of the process of the heat pump system, wherein the warm-up
phase corresponds with a higher lamination work and the steady
state phase corresponds with lower lamination work.
Description
[0001] The present invention relates to a laundry dryer with a heat
pump system for a according to the-preamble of claims 1 and 7.
[0002] A laundry dryer with a heat pump system is an efficient way
to dry laundry by low energy consumption. In a conventional heat
pump laundry dryer an air stream flows in a close air stream
circuit. The air stream is moved by a fan, passes through a laundry
drum, removes water from wet laundry, is then cooled down and
dehumidified in an evaporator, heated up in a condenser and at last
re-inserted into the laundry drum again. The refrigerant instead is
compressed by a compressor, condensed in the condenser, laminated
in expansion means and then vaporized in the evaporator.
[0003] In the most laundry dryers the heat pump system works in an
on-off mode, wherein the compressor has one rotational speed. The
operation of the heat pump system can be optimized by a variable
rotational speed compressor. However, in this case, the Applicant
has found that in order to obtain better performances, variable
expansion means can be provided to adapt the lamination work to the
variation of the rotational speed of the compressor.
[0004] In fact, it has been found that higher rotational speed of
the compressor and lower rotational speed of the compressor
requires different lamination work for the compressor to operates
in an effective way.
[0005] EP 1 612 976 A1 discloses a drying apparatus comprising a
heat pump system, wherein variable expansion means and the
compressing performance of the compressor are controlled in
response to the pressure of the refrigerant detected at the outlet
of the compressor. However, this control method is complex and
requires pressure and temperature sensors and an appropriate
feedback line.
[0006] It is an object of the present invention to provide a
laundry dryer with a heat pump system, in which the lamination work
of the expansion means can be adapted by low complexity.
[0007] The object of the present invention is achieved by the
laundry dryer with a heat pump system according to claim 1
[0008] According to the present invention, the laundry dryer
comprises a control unit the control unit is adapted to adjust the
variable expansion means in response to at least a compressor
quantity representative of the operation of the compressor and/or
to the drying cycle selected by the user, wherein said compressor
quantity is at least one of the following:
[0009] rotational speed of the compressor (14),
[0010] supply current/voltage frequency of the compressor
motor,
[0011] absorbed power or current of the compressor (14).
[0012] Preferably, the control unit is adapted to monitor or
determine the rotational speed of the compressor and/or the supply
current/voltage frequency of the compressor motor and/or the
absorbed power or current of the compressor and to operate the
variable expansion means accordingly.
[0013] Preferably, the control unit is adapted to receive signals
representative of the rotational speed of the compressor and/or the
supply current/voltage frequency of the compressor motor and/or the
absorbed power or current of the compressor or the control unit is
adapted to receive signal representative of predetermined
parameters, which are the basis for the determination of rotational
speed of the compressor and/or the supply current/voltage frequency
of the compressor motor and/or the absorbed power or current of the
compressor.
[0014] Preferably, the control unit is adapted to set the variable
expansion means to a reduced lamination work, when the output of
the compressor is high or starts to increase or increases, the
control unit is adapted to set the variable expansion means to an
increased lamination work, when the output of the compressor is low
or starts to decrease or decreases, output of the compressor being
the rotational speed of the compressor and/or the supply
current/voltage frequency of the compressor motor and/or the
absorbed power or current of the compressor.
[0015] Preferably, the laundry dryer comprises at least one drying
cycle, in which the compressor operates at different outputs,
and/or comprising different drying cycles, wherein the output of
the compressor is constant or substantially constant in each drying
cycle, but different from drying cycle to drying cycle, wherein the
control unit adjusts the variable expansion means according to the
drying cycle selected by the user.
[0016] Preferably, the control unit is adapted to set the variable
expansion means to a reduced lamination work according to an
increasing output profile of the compressor for the selected drying
cycle and to set the variable expansion means to an increased
lamination work according to a decreasing output profile of the
compressor for the selected drying cycle.
[0017] Preferably, the control unit actuates the compressor to
increase the output established by the selected drying cycle, and
automatically actuates the variable expansion means to a reduced
lamination work, further wherein the control unit actuates the
compressor to decrease the output established by the selected
drying cycle, and automatically actuates the variable expansion
means to an increased lamination work.
[0018] Preferably, the variable expansion means comprise at least
two capillary tubes wherein at least one of said capillary tubes is
switched or switchable by at least one valve.
[0019] Preferably, the expansion means comprises at least two
parallel series of a capillary tube and a corresponding on-off
valve in each case, wherein the capillary tubes have different
lengths and/or different cross-sections.
[0020] Preferably, the expansion means comprises at least two
serial capillary tubes, wherein at least one of the capillary tubes
is bypassed by an on-off valve.
[0021] Preferably, the capillary tubes have different lengths
and/or different cross-sections.
[0022] Preferably, the capillary tubes have the same lengths and
cross-sections.
[0023] Preferably, the expansion means comprises two capillary
tubes and a three-way valve, wherein the capillary tubes are
alternatingly switchable by the three-way valve and the capillary
tubes have different lengths and/or different cross-sections.
[0024] Preferably, the expansion means comprises at least one
lamination valve including a variable opening degree, so the
lamination work at said expansion means is adjustable.
[0025] Preferably, the control unit is provided for adapting the
lamination work at the expansion means to a warm-up phase and a
steady state phase of the process of the heat pump system, wherein
the warm-up phase corresponds with a higher lamination work and the
steady state phase corresponds with lower lamination work.
[0026] The novel and inventive features believed to be the
characteristic of the present invention are set forth in the
appended claims.
[0027] The invention will be described in further detail with
reference to the drawings, in which
[0028] FIG. 1 shows a schematic diagram of a heat pump system for a
laundry dryer according to the present invention,
[0029] FIG. 2 shows a detailed schematic diagram of expansion means
of the heat pump system for the laundry dryer according to a first
embodiment of the present invention,
[0030] FIG. 3 shows a detailed schematic diagram of expansion means
of the heat pump system for the laundry dryer according to a second
embodiment of the present invention,
[0031] FIG. 4 shows a detailed schematic diagram of expansion means
of the heat pump system for the laundry dryer according to a fourth
embodiment of the present invention,
[0032] FIG. 5 shows a detailed schematic diagram of expansion means
of the heat pump system for the laundry dryer according to a fifth
embodiment of the present invention,
[0033] FIG. 6 shows a schematic diagram of the power and motor
frequency as function of time for a compressor of the heat pump
system for the laundry dryer according to the present
invention,
[0034] FIG. 7 shows a schematic diagram of the motor frequencies as
function of time for the compressor of the heat pump system for the
laundry dryer according to the present invention,
[0035] FIG. 8 shows a schematic diagram of the motor speeds as
function of time for the compressor of the heat pump system for the
laundry dryer according to the present invention,
[0036] FIG. 9 shows a schematic diagram of the motor frequency as
function of time for the compressor of the heat pump system for the
laundry dryer according to the present invention, and
[0037] FIG. 10 shows a schematic diagram of the motor speeds as
function of time for the compressor of the heat pump system for the
laundry dryer according to the present invention.
[0038] FIG. 11 shows a schematic diagram of a refrigerant circuit
of the heat pump system with a control unit for the laundry dryer
according to the present invention.
[0039] FIG. 1 illustrates a schematic diagram of a heat pump system
for a laundry dryer according to a first embodiment of the present
invention. The heat pump system includes a closed refrigerant
circuit 10 and a drying air stream circuit 12.
[0040] The drying air stream circuit 12 is preferably a closed loop
in which the process air is continuously circulated through the
laundry storing chamber. However it may also be provided that a
(preferably smaller) portion of the process air is exhausted from
the process air loop and fresh air (e.g. ambient air) is taken into
the process air loop to replace the exhausted process air. And/or
the process air loop is temporally opened (preferably only a short
section of the total processing time) to have an open loop
discharge.
[0041] The refrigerant circuit 10 includes a compressor with
variable output 14, a first heat exchanger 16, variable expansion
means 18 and a second heat exchanger 20. The compressor 14, the
first heat exchanger 16, the variable expansion means 18 and the
second heat exchanger 20 are switched in series and form a closed
loop.
[0042] The drying air stream circuit 12 includes the first heat
exchanger 16, the second heat exchanger 20, a laundry treatment
chamber 22, preferably a rotatable drum 22 and a drying air stream
fan 24. The first heat exchanger 16 and the second heat exchanger
20 form the thermal coupling between the refrigerant circuit 10 and
the drying air stream circuit 12.
[0043] The refrigerant circuit 10 is subdivided into a high
pressure portion and a low pressure portion. The high pressure
portion extends from the outlet of the compressor 14 via the first
heat exchanger 16 to the inlet of the variable expansion means 18.
The low pressure portion extends from the outlet of the variable
expansion means 18 via the second heat exchanger 20 to the inlet of
the compressor 14.
[0044] In this example, the first heat exchanger 16 acts as a
condenser, and the second heat exchanger 20 acts as an evaporator.
However, when the refrigerant operates at least at the critical
pressure in the high pressure portion of the refrigerant circuit
10, then the first heat exchanger 16 acts as a gas cooler since the
refrigerant is in the gaseous state during the cycle. Similar, when
the refrigerant operates at least at the critical pressure in the
low pressure portion of the refrigerant circuit 10, then the second
heat exchanger 16 acts as a gas heater since the refrigerant is in
the gaseous state during the cycle.
[0045] The compressor 14 with variable output compresses and heats
up the refrigerant. The first heat exchanger 16 cools down the
refrigerant in the refrigerant circuit 10 and heats up the air
stream in the drying air stream circuit 12, before the air stream
is re-inserted into the laundry drum 26. The variable expansion
means 18 laminates the refrigerant from a higher pressure to a
lower pressure. The second heat exchanger 20 cools down and
dehumidifies the air stream, after said air stream has passed the
laundry drum 22 in the drying air stream circuit 12. The drying air
stream is driven by the air stream fan 24. The output of the
compressor 14 is adjustable.
[0046] The compressor 14 with variable output is adapted to treat
different refrigerant mass flow rate depending on the rotation
speed thereof. An electronic controller is provided to change the
rotational speed of the electric motor of the compressor in
response to a predetermined feedback.
[0047] As an example, the electronic controller can vary the
operating frequency of the current/voltage absorbed by the
compressor electric motor in order to adjust the rotational speed
and the power of the compressor. The electronic controller can be
an inverter, which drives the electric motor of the compressor
14.
[0048] The laundry dryer comprises a control unit 38 connected to
the compressor 14 via a compressor control line 44. The control
unit 38 is adapted to control the compressor 14 so as to vary the
rotational speed and/or the supply current/voltage frequency and/or
power/current absorbed by the compressor.
[0049] The control unit 38 operates the electronic controller (e.g.
inverter) so as to drive the electric motor of the compressor
14.
[0050] Rotational speed of the compressor is the speed of the shaft
connected to the device that compresses the refrigerant during the
compressor running, the rotational speed is substantially equals to
the rotational speed of the motor. Supply current/voltage frequency
is the frequency of the current/voltage supplied to the compressor
motor by the electronic controller to vary the rotational speed of
the compressor.
[0051] Additionally, the laundry dryer can comprise a drying cycle
(operation mode) in which the rotational speed and/or the supply
current/voltage frequency and/or power/current absorbed by the
compressor varies over the drying time. In addition or
alternatively, the laundry dryer can comprise at least two
operational modes in which the compressor output is substantially
constant or at least substantially constant over most of the drying
time but the output is different from one cycle to another.
[0052] Preferably, the laundry dryer comprises a control panel 40
for the user to select the available operation modes of the drying
cycle/s. The control unit 38 is adapted to receive from the control
panel 40 information regarding the drying cycle selected by the
user.
[0053] It has to be noted that the control unit 38 may be a
stand-alone electronic unit, or it may be included in a system
which performs overall control of the laundry dryer, including
interfacing with a user to display operational information, select
drying programs (i.e. control panel) and set operational parameters
for such programs.
[0054] Additionally the electronic controller (e.g. inverter) can
be integrated in the control unit 38.
[0055] The user can select different operation modes of the drying
cycle/s on said control panel 40 via, for example, a suitable
changeover switch 46. For example, a fast operation mode
corresponds with a relative high rotational speed of the compressor
14. Further, an eco (or night) mode corresponds with a lower
rotational speed of the compressor 14. In dependence of the
selection of the user, the control unit activates the corresponding
rotational speed of the compressor 14.
[0056] Clearly other operation modes can be envisaged having
specific output of the compressor for drying different type of
textile, different weight of the laundry, for achieving different
drying degree of the laundry.
[0057] FIG. 6 shows an exemplary schematic diagram of the power P
and supply current/voltage frequency f as function of time t for
the compressor 14. FIG. 7 clarifies further the relation between
the power P and the supply current/voltage frequency f.
[0058] FIG. 6 shows a first supply current/voltage frequency f1 and
a corresponding first power P1 as well as a second supply
current/voltage frequency f2 and a corresponding second power P2.
The frequencies f1 and f2 decrease during the drying cycle, while
the corresponding powers P1 and P2 remain constant.
[0059] The rotational speed of the compressor is linked to the
supply current/voltage frequency f.
[0060] FIG. 7 shows a schematic diagram of the supply
current/voltage frequencies f3 and f4 as function of time t for the
compressor 14. The supply current/voltage frequency f3 is higher
than the supply current/voltage frequency f4. The supply
current/voltage frequency f3 relates, for example, to the fast mode
of the drying cycle as previously mentioned. The supply
current/voltage frequency f4 relates, for example, to the eco (or
night) mode of the drying cycle. The drying cycle of the eco mode
requires more time than the drying cycle of the fast mode but less
energy.
[0061] FIG. 8 shows a schematic diagram of the motor speeds v3 and
v4 as function of time t for the compressor 14 of the heat pump
system for the laundry dryer according to the present invention.
The motor speed v3 is higher than the motor speed v4. The motor
speed v3 can relate, for example, to the fast mode of the drying
cycle. The motor speed v4 can relate, for example, to the eco (or
night) mode of the drying cycle. The drying cycle of the eco mode
requires more time than the drying cycle of the fast mode but less
energy.
[0062] FIG. 9 shows a schematic diagram of the supply
current/voltage frequency f as function of time for the compressor
14 that represent another possible operation mode. In FIG. 10 the
supply current/voltage frequency f has been reduced after about the
half time of the drying cycle.
[0063] FIG. 10 shows a schematic diagram of the motor speeds v3 and
v4 as function of time for the compressor 14. The motor speed v3
relates, for example, to another possible fast mode of the drying
cycle. The motor speed v4 relates, for example, to another possible
eco mode of the drying cycle. In both cases the motor speeds v3 and
v4 are reduced during the drying cycle. In the fast mode, the motor
speed v3 is reduced after the half time of the drying cycle. In the
eco mode, the motor speed v4 is reduced after about one third of
the time of the drying cycle. The drying cycle of the eco mode
requires more time than the drying cycle of the fast mode but less
energy.
[0064] The variable expansion means 18 provide different lamination
work according to the operational conditions of the heat pump
system. The control unit 38 is connected to the variable expansion
means 18 via a control line 42. The variable expansion means 18 are
controlled in response to signal issued by the control unit 38 so
as to adjust the pressure drop.
[0065] The variable expansion means can include at least two
capillary tubes switchable by the control unit 38 to provide
different lamination work. FIGS. 2 to 6 show some exemplary
arrangements of above mentioned type that will be described in
details in the following.
[0066] Alternatively the variable expansion means can include a
variable expansion valve controllable by the control unit 38, for
example the valve can be an electronic valve.
[0067] FIG. 2 shows a detailed schematic diagram of expansion means
18 of the heat pump system for the laundry dryer according to an
embodiment of the present invention. The expansion means 18 of the
first embodiment include a three-way valve 26, a first capillary
tube 28 and a second capillary tube 30.
[0068] The three-way valve 26 comprises three ports. A first port
is connected to the outlet of the first heat exchanger 16. A second
port is connected to the inlet of the first capillary tube 28. A
third port is connected to the inlet of the second capillary tube
30.
[0069] The three-way valve 26 is provided to change over between
the first capillary tube 28 and the second capillary tube 30, so
that the refrigerant flows either through the first capillary tube
28 or through the second capillary tube 30. The first capillary
tube 28 and the second capillary tube 30 have different geometric
properties, so that the first capillary tube 28 and the second
capillary tube 30 provide different lamination works.
[0070] In the example proposed, the lamination work increases with
the length of the capillary tubes 28 and 30, assuming that the
cross-section of the tubes is the same and the refrigerant flow
rate is the same as well. The first capillary tube 28 is shorter
than the second capillary tube 30. Thus, the second capillary tube
30 provides higher lamination work than the first capillary tube
28.
[0071] However, in a similar manner the lamination work increases
with the increasing of the cross-section of the capillary tubes 28
and 30, assuming that the length of the tubes is the same and the
refrigerant flow rate is the same as well.
[0072] In an alternative embodiments The three-way valve 26 can be
arranged downstream of first capillary tube 28 and the second
capillary tube 30.
[0073] FIG. 3 shows a detailed schematic diagram of expansion means
18 of the heat pump system for the laundry dryer according to
another embodiment of the present invention. The expansion means 18
of the embodiment shown include the first capillary tube 28, the
second capillary tube 30, a first on-off valve 32 and a second
on-off valve 34.
[0074] The inlets of the first capillary tube 28 and the second
capillary tube 30 are connected to the outlet of the first heat
exchanger 16. The outlet of the first capillary tube 28 is
connected to the inlet of the first on-off valve 32. In a similar
way, the outlet of the second capillary tube 30 is connected to the
inlet of the second on-off valve 34. Thus, the on-off valves 32 and
34 are arranged downstream the corresponding capillary tubes 28 and
30, respectively. The outlets of the first on-off valve 32 and the
second on-off valve 34 are connected to the inlet of the second
heat exchanger 20.
[0075] The first on-off valve 32 and the second on-off valve 34 are
provided to select one of the capillary tubes 28 or 30. The first
capillary tube 28 and the second capillary tube 30 have different
geometric properties, so that the first capillary tube 28 and the
second capillary tube 30 provides different lamination work. Since
the first capillary tube 28 is shorter than the second capillary
tube 30, the second capillary tube 30 provides higher lamination
work than the first capillary tube 28 (assuming that the respective
cross sections are the same).
[0076] Additionally, when both the on-off valve 32, 34 are in open
position, the first and second capillary tube 28, 30 provide a
cumulative lamination work different from the one generated by the
first capillary tune 28 when only the first on-off valve 32 is open
and by the second capillary tube 30 when only the second on-off
valve 32 is open.
[0077] FIG. 4 shows a detailed schematic diagram of expansion means
18 of the heat pump system for the laundry dryer according to
another embodiment of the present invention. The expansion means 18
of the embodiment shown include the first capillary tube 28, the
second capillary tube 30 and the by-pass on-off valve 36.
[0078] The inlet of the first capillary tube 28 is connected to the
outlet of the first heat exchanger 16. The inlet of the second
capillary tube 30 is connected to the outlet of the first capillary
tube 28. The outlet of the second capillary tube 30 is connected to
the inlet of the second heat exchanger 20. Thus, the first
capillary tube 28 and the second capillary tube 30 are connected in
series. The bypass on-off valve 36 is connected in parallel to the
first capillary tube 28.
[0079] Preferably, the bypass on-off valve 36 is provided along a
bypass line comprising a bypass line inlet arranged between the
inlet of the first capillary tube 28 and the outlet of the first
heat exchanger 16 and a bypass line outlet arranged between the
outlet of the first capillary tube 28 and inlet of the second
capillary tube 30.
[0080] When the bypass on-off valve 36 is closed, then the
refrigerant flows in the first capillary tube 28 and the second
capillary tube 30. When the bypass on-off valve 36 is open, then
the first capillary tube 28 is bypassed, and the refrigerant flows
only in the second capillary tube 30. When the bypass on-off valve
36 is open, then the lamination work of the expansion means 18
decreases.
[0081] FIG. 5 shows a detailed schematic diagram of expansion means
18 of the heat pump system for the laundry dryer according to
another embodiment of the present invention. The expansion means 18
of the embodiment shown include the first capillary tube 28, the
second capillary tube 30 and the by-pass on-off valve 36.
[0082] The inlet of the first capillary tube 28 is connected to the
outlet of the first heat exchanger 16. The inlet of the second
capillary tube 30 is connected to the outlet of the first capillary
tube 28. The outlet of the second capillary tube 28 is connected to
the inlet of the second heat exchanger 20. Thus, the first
capillary tube 28 and the second capillary tube 30 are connected in
series. The bypass on-off valve 36 is connected in parallel to the
second capillary tube 30.
[0083] Preferably, the bypass on-off valve 36 is provided along a
bypass line 38 comprising a bypass line inlet arranged between the
outlet of the first capillary tube 28 and the inlet of second
capillary tube 30 and a bypass line outlet arranged between the
outlet of the second capillary tube 30 and inlet of the second heat
exchanger 20.
[0084] When the bypass on-off valve 36 is closed, then the
refrigerant flows in the first capillary tube 28 and the second
capillary tube 30. When the bypass on-off valve 36 is open, then
the second capillary tube 30 is bypassed, and the refrigerant flows
only in the first capillary tube 28. When the bypass on-off valve
36 is open, then the lamination work of the expansion means 18
decreases.
[0085] In the above embodiments the expansion means 18 include two
capillary tubes 28 and 30 in each case, wherein two different
lamination work can be selected. In general, the expansion means 18
may include more capillary tubes 28 and 30 and/or more valves 26,
32, 34 and/or 36, so that more than two different lamination work
can be selected.
[0086] The control unit 38 controls the valves 26, 32, 34 and/or 36
of the variable expansion means 18, so that the lamination work at
said variable expansion means 18 is adapted to operational
condition of the heat pump system.
[0087] According to the present invention, the control unit 38
adjusts the variable expansion means 18 in response to the
rotational speed of the compressor, the supply current/voltage
frequency f of the compressor motor and/or the absorbed power or
current of the compressor 14.
[0088] In practise, the control unit 38 is adapted to monitor or
determine the rotational speed of the compressor and/or the supply
current/voltage frequency f of the compressor motor and/or the
absorbed power or current of the compressor 14 and to operate the
variable expansion means accordingly.
[0089] Preferably via the compressor control line 44 provided
between the control unit 38 and the compressor 14, the control unit
38 is adapted to receive signals representative of the rotational
speed of the compressor and/or the supply current/voltage frequency
f of the compressor motor and/or the absorbed power or current of
the compressor 14 or is adapted to receive signal representative of
predetermined parameters, which are the basis for the determination
of rotational speed of the compressor and/or the supply
current/voltage frequency f of the compressor motor and/or the
absorbed power or current of the compressor 14.
[0090] The control unit 38 sets the variable expansion means 18 to
a reduced lamination work, when the output of the compressor 14 is
high or is getting higher or start to increase, i.e. high speed,
high supply current/voltage frequency and high absorbed power or
current.
[0091] Conversely, the control unit 38 sets the variable expansion
means 18 to an increased lamination work, when the output of the
compressor 14 is low or is getting lower o start to decrease.
[0092] The adjusting of the variable expansion means 18 is
performed by a change of the opening degree of the controllable
valve or by selecting the most suitable capillary tube from a
plurality of capillary tubes 28 and 30 so that the lamination work
generated by the variable expansion means 18 is fitted, in an
effective way, to the compressor variable output. The opening
degree of the controllable valve can be adjusted continuously.
[0093] According to another aspect of the present invention, when
the laundry dryer includes at least one drying cycle, in which the
compressor operates at different outputs, then the control unit 38
adjusts the variable expansion means 18 according to the drying
cycle selected by the user. When the laundry dryer includes
different drying cycles, wherein the output is constant (or
substantially constant) in each drying cycle, but different from
drying cycle to drying cycle, then controller adjusts also the
variable expansion means 18 according to the drying cycle selected
by the user.
[0094] The control unit 38 is adapted to set the variable expansion
means 18 to a reduced lamination work according to an increasing
output profile of the compressor 14 for the selected drying cycle
and to set the variable expansion means 18 to an increased
lamination work according to a decreasing output profile of the
compressor 14 for the selected drying cycle.
[0095] Increasing/decreasing output profile means and
increasing/decreasing of the compressor rotational speed and/or the
supply current/voltage frequency f of the compressor motor and/or
the absorbed power or current of the compressor.
[0096] In practise, when the control unit 38 has to actuate the
compressor 14 to increase the output established by the selected
drying cycle, then the control unit 38 automatically actuates the
variable expansion means 18 to a reduced lamination work and when
the control unit 38 has to actuate the compressor to decrease the
output established by the selected drying cycle, then the control
unit 38 automatically actuates the variable expansion means 18 to
an increased lamination work.
[0097] A further application of the variable expansion means 18 may
be an adaption of the pressure drop between a warm-up phase and a
steady state phase of the laundry dryer. During the warm-up phase
of the laundry dryer, a certain lamination work is advantageous in
order to shorten said warm-up phase. When the warm-up phase is
over, then the lamination work is adjusted to fit the steady state
phase.
[0098] Although illustrative embodiments of the present invention
have been described herein with reference to the accompanying
drawings, it is to be understood that the present invention is not
limited to those precise embodiments, and that various other
changes and modifications may be affected therein by one skilled in
the art without departing from the scope or spirit of the
invention. All such changes and modifications are intended to be
included within the scope of the invention as defined by the
appended claims.
LIST OF REFERENCE NUMERALS
[0099] 10 refrigerant circuit
[0100] 12 air stream circuit
[0101] 14 compressor
[0102] 16 first heat exchanger, condenser
[0103] 18 expansion means
[0104] 20 second heat exchanger, evaporator
[0105] 22 laundry drum
[0106] 24 air stream fan
[0107] 26 three-way valve
[0108] 28 first capillary tube
[0109] 30 second capillary tube
[0110] 32 first on-off valve
[0111] 34 second on-off valve
[0112] 36 bypass on-off valve
[0113] 38 control unit
[0114] 40 control panel
[0115] 42 control line
[0116] 44 compressor control line
[0117] 46 changeover switch
[0118] f supply current/voltage frequency
[0119] f1 first supply current/voltage frequency
[0120] f2 second supply current/voltage frequency
[0121] f3 supply current frequency/voltage for the fast mode
[0122] f4 supply current frequency/voltage for the eco mode
[0123] P power
[0124] P1 first power
[0125] P2 second power
[0126] v motor speed
[0127] v3 motor speed for the fast mode
[0128] v4 motor speed for the eco mode
[0129] t time
* * * * *