U.S. patent application number 10/556318 was filed with the patent office on 2007-08-09 for system for controlling compressor of cooling system and method for controlling the same.
This patent application is currently assigned to LG ELECTRONICS INC.. Invention is credited to Ji Young Bae, Chang Yong Jang, Kyoung Jun Park.
Application Number | 20070180841 10/556318 |
Document ID | / |
Family ID | 36923827 |
Filed Date | 2007-08-09 |
United States Patent
Application |
20070180841 |
Kind Code |
A1 |
Bae; Ji Young ; et
al. |
August 9, 2007 |
System for controlling compressor of cooling system and method for
controlling the same
Abstract
Disclosed is a system for controlling a compressor of a cooling
system. The system includes: the compressor having a driving shaft
that is rotatable clockwise and counterclockwise and operated by a
power of a motor outputting different torque characteristics
depending on the rotational directions of the driving shaft; a
selector for selecting an output torque characteristic of the
motor; a switching part for turning on or off the motor; and a
control unit for controlling the selector to drive the compressor
in a torque characteristic suitable for an object to be cooled. In
an aspect of the invention, there is provided a method for
controlling an operation of a compressor in a cooling system. The
method includes the steps of: (a) an initial starting step of
starting the compressor equipped with a motor different torque
characteristics depending on rotary directions of a driving shaft
at a first torque characteristic; (b) determining the operation
torque characteristic of the motor; (c) when it is determined that
the motor operates at the first torque characteristic in
consequence of performing the step (b), if a first condition is met
during an operation of the compressor, stopping the compressor, (d)
determining whether it is suitable to continuously operate the
motor at the first torque characteristic in a state that the
compressor is stopped, and if it is determined that it is suitable,
maintaining the operation torque characteristic of the motor, while
if it is determined that it is not suitable, converting the
operation torque characteristic of the motor from the first torque
characteristic to a second torque characteristic, and if a second
condition is met, operating the compressor.
Inventors: |
Bae; Ji Young; (Busan,
KR) ; Park; Kyoung Jun; (Changwon-si, KR) ;
Jang; Chang Yong; (Gwangju, KR) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
LG ELECTRONICS INC.
20, Yoido-Dong, Youngdungpo-Gu
SEOUL
KR
|
Family ID: |
36923827 |
Appl. No.: |
10/556318 |
Filed: |
April 27, 2004 |
PCT Filed: |
April 27, 2004 |
PCT NO: |
PCT/KR04/00965 |
371 Date: |
December 27, 2006 |
Current U.S.
Class: |
62/228.1 |
Current CPC
Class: |
F25B 2600/23 20130101;
F25B 2600/0251 20130101; F04C 2270/03 20130101; F04C 28/04
20130101; F25D 2500/04 20130101; F04C 18/3564 20130101; F04B 49/06
20130101; F25B 49/025 20130101; F04C 28/06 20130101; F04C 28/14
20130101; F25B 2700/2104 20130101; F25B 1/04 20130101 |
Class at
Publication: |
062/228.1 |
International
Class: |
F25B 49/00 20060101
F25B049/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 13, 2003 |
KR |
10-2003-0030348 |
Claims
1. A system for controlling a compressor of a cooling system, the
controlling system comprising: the compressor having a driving
shaft that is rotatable clockwise and counterclockwise and operated
by a power of a motor outputting different torque characteristics
depending on the rotational directions of the driving shaft; a
selector for selecting an output torque characteristic of the
motor; a switching part for turning on or off the motor; and a
control unit for controlling the selector to drive the compressor
in a torque characteristic suitable for an object to be cooled.
2. The system of claim 1, further comprising means for sensing
information on the object to be cooled, wherein the control unit
controls the selector and the switching part on the basis of
information transmitted from the sensing means.
3. The system of claim 2, wherein the sensing means comprises a
temperature sensor for measuring the temperature of the object to
be cooled.
4. The system of claim 1, further comprising an overload protector
provided between the motor and the switching part.
5. The system of claim 1, wherein the motor comprises: a first
winding connecting a first terminal and a common terminal and
rotating the driving shaft in a first torque characteristic; and a
second winding a second terminal and the common terminal and
rotating the driving shaft in a second torque characteristic.
6. The system of claim 5, wherein the selector comprises: a first
contact point connected with the first terminal; a second contact
point connected with the second terminal; and a common contact
point connected with a power and selected connected to the first
contact point or the second contact point.
7. The system of claim 1, wherein the switching part comprises a
thermostat of which contact point is turned on or off depending on
the temperature of the object to be cooled.
8. The system of claim 7, further comprising means for determining
whether the motor is turned on or off.
9. The system of claim 8, wherein the determining means comprises a
current sensor for sensing a current through the switching
part.
10. The system of claim 8, wherein the control unit controls the
selector on the basis of whether the motor is turned on or off and
an elapse of time.
11. The system of claim 7, further comprising a second switching
part connected in series with the switching part, wherein the
control unit controls the selector and the second switching part on
the basis of the elapse degree of time.
12. The system of claim 1, wherein the compressor comprises: the
driving shaft having a predetermined sized eccentric part and being
rotatable clockwise and counterclockwise; a cylinder forming a
predetermined inner volume; a roller rotating in contact with an
inner circumference of the cylinder, installed rotatably on an
outer circumference of the eccentric part, performing a rolling
motion along the inner circumference and forming a fluid chamber to
suck and compress fluid along with the inner circumference; a vane
installed elastically in the cylinder so as to be in contact with
the roller continuously, and partitioning the fluid chamber into
two independent spaces; upper and lower bearings installed
respective at upper and lower sides of the cylinder, for rotatably
supporting the driving shaft and sealing the inner volume;
discharge ports communicating with the fluid chamber; discharge
valves for opening the respective discharge ports at a
predetermined pressure or more; and at least one suction port
communicating with the fluid chamber.
13. The system of claim 12, wherein the suction and discharge ports
are formed in the cylinder.
14. The system of claim 13, wherein the discharge ports are spaced
apart by a predetermined distance to face with each other with
respect to the vane.
15. The system of claim 14, wherein the suction port is one that is
located to face with the vane on an imaginary line passing on the
vane.
16. The system of claim 14, wherein the suction port is located at
a side on an imaginary line passing on the vane.
17. The system of claim 12, wherein the suction and discharge ports
are formed in the bearing, further comprising a valve assembly for
selectively opening one of the suction ports depending on the
rotary direction of the driving shaft.
18. The system of claim 17, wherein the discharge ports comprise
first and second discharge ports that are located to face with each
about the vane.
19. The system of claim 17, wherein the suction port comprises: a
first suction port located adjacent to the vane; and a second
suction port spaced apart by a predetermined angle from the first
suction port with respect to a center of the cylinder.
20. The system of claim 17, wherein the roller compresses the fluid
by using the overall fluid chamber when the driving shaft rotates
only in either the clockwise direction or counterclockwise
direction.
21. The system of claim 17, wherein the roller compresses the fluid
by using a part of the fluid chamber when the driving shaft rotates
only in either the clockwise direction or counterclockwise
direction.
22. The system of claim 19, wherein the valve assembly comprises: a
first valve installed rotatably between the cylinder and the
bearing and having a penetration hole through which the driving
shaft is inserted; and a second valve fixed between the cylinder
and the bearing, having a site portion accommodating the first
valve, and for guiding a rotary motion of the first valve.
23. The system of claim 22, wherein the first valve is comprised of
a circular plate member that is in contact with the eccentric part
of the driving shaft to rotate in the rotary direction of the
driving shaft.
24. The system of claim 22, wherein the first valve comprises: a
first opening communicating with the first suction port when the
driving shaft rotates in one of the clockwise direction or the
counterclockwise direction; and a second opening communicating with
the second suction port when the driving shaft rotates in the other
the clockwise direction or the counterclockwise direction.
25. The system of claim 24, wherein the suction port further
comprises a third suction port located on the second suction port
and the vane, and the first opening no sooner opens the third
suction port than the second suction port is opened.
26. The system of claim 22, wherein the valve assembly further
comprises means for controlling a rotary angle of the first valve
so as to precisely open the corresponding suction port with respect
to each rotary direction.
27. The system of claim 26, wherein the control means comprises: a
protruded portion protruded in a radius direction of the first
valve; and a groove formed in the second valve and accommodating
the protruded portion movably.
28. A cooling system comprising: a compressor having a driving
shaft that can be rotatable clockwise and counterclockwise and
operated by a power of a motor outputting different torque
characteristics depending on the rotational directions of the
driving shaft; a compressor control part including a selector for
selecting an output torque characteristic of the motor; a switching
part for turning on or off the motor; and a micom for controlling
the selector to operate the compressor at a torque characteristic
suitable for an object to be cooled; first and second heat
exchangers which heat-exchange coolant forcibly delivered from the
compressor with an indoor or an outdoor respectively; and an
expansion unit provided in a coolant tube connecting the first and
second heat exchangers.
29. A method for controlling an operation of a compressor in a
cooling system, the method comprising the steps of: (a) an initial
starting step of starting the compressor equipped with a motor
different torque characteristics depending on rotary directions of
a driving shaft at a first torque characteristic; (b) determining
the operation torque characteristic of the motor, (c) when it is
determined that the motor operates at the first torque
characteristic in consequence of performing the step (b), if a
first condition is met during an operation of the compressor,
stopping the compressor; (d) determining whether it is suitable to
continuously operate the motor at the first torque characteristic
in a state that the compressor is stopped, and if it is determined
that it is suitable, maintaining the operation torque
characteristic of the motor, while if it is determined that it is
not suitable, converting the operation torque characteristic of the
motor from the first torque characteristic to a second torque
characteristic, and if a second condition is met, operating the
compressor.
30. The method of claim 29, wherein the first torque characteristic
has a torque greater than the second torque characteristic.
31. The method of claim 30, wherein the first condition is a
question `Is the temperature of an object to be cooled below a
lower limit of a set temperature?`.
32. The method of claim 31, wherein the step (c) comprises the step
of (c0) computing an absolute value (P) of an average temperature
variation rate of the object to be cooled during a predetermined
time period while the compressor operates.
33. The method of claim 32, wherein the step (d) comprises the
steps of: (d1) determining a conversion condition of the torque
characteristic in the state that the compressor is stopped, and if
the conversion condition is met, converting the torque
characteristic of the motor to the second torque characteristic;
(d2) determining the conversion condition of the torque
characteristic in the state that the compressor is stopped, and if
the conversion condition is not met, maintaining the torque
characteristic of the motor at the first torque characteristic; and
(d3) after the step (d1) or (d2), if the second condition is met,
operating the compressor while if the second condition is not met,
continuing to determining whether the second condition is met or
not.
34. The method of claim 33, wherein the conversion condition of the
torque characteristic is a question "Does an absolute value (P) of
average temperature variation rate of the object to be cooled
exceed a critical value (P+) of an absolute value of temperature
variation rate for torque characteristic conversion of the
motor?".
35. The method of claim 33, wherein the second condition is a
question "Does the temperature of the object to be cooled exceed an
upper limit of a set temperature?.
36. The method of claim 29, wherein the step (b) is performed after
the step (d).
37. The method of claim 36, further comprising, when it is
determined that the motor operates at the second torque
characteristic as a result of performing the step (b), the step (e)
determining whether or not it is proper to operate the motor at the
second torque characteristic based on the state of the object to be
cooled and stopping the compressor.
38. The method of claim 37, wherein the step (e) comprises the
steps of: (e1) measuring an absolute value (P) of an average
temperature variation rate of the object to be cooled for a
selected time interval while the compressor operates; (e2)
determining whether the absolute value (P) of the average
temperature variation rate of the object to be cooled is less than
an absolute value (P-) of a preset minimum temperature variation
rate for a selected time interval; and (e3) if the step (e2) is
met, determining that it is not proper to operate the motor at the
second torque characteristic and stopping the compressor.
39. The method of claim 38, further comprising the step (e4) of,
determining whether the temperature of the object to be cooled is
less than the lower limit of the set temperature, if so,
determining that it is proper to operate the motor at the second
torque characteristic and stopping the compressor.
40. The method of claim 39, when in the step (e4), it is determined
that the temperature of the object to be cooled is equal to or
greater than the lower limit of the set temperature, further
comprising the step of returning to the step (e1).
41. The method of claim 38, further comprising the steps of: (f) if
a compression key is stopped by the step (e3), after a time delay,
converting the torque characteristic of the motor to the first
torque characteristic; and (g) after the step (f), driving the
motor to operate the compressor, and going to the step (b).
42. The method of claim 39, further comprising the step of, if the
compressor is stopped by the step (e4), driving the motor and
operating the compressor when the temperature of the object to be
cooled meets an upper limit of the set temperature, and going to
the step (b).
43. The method of claim 30, wherein the first condition is a
question "Is the compressor turned off?".
44. The method of claim 43, wherein whether or not the compressor
is stopped is determined by On or Off of a motor switching part
which is automatically turned on or off by a condition of the
object to be cooled.
45. The method of claim 44, wherein whether or not the compressor
is stopped is determined by whether or not current is sensed by a
current sensor connected in series to the motor switching part.
46. The method of claim 43, wherein the step (c) comprises the step
(c5) of counting an elapse time.
47. The method of claim 46, wherein the step (d) comprises the
steps of: (d5) determining the conversion condition of the torque
characteristic in a stop state of the compressor, and if the
conversion condition is met, converting the torque characteristic
to the second torque characteristic; (d6) determining the
conversion condition of the torque characteristic in the stop state
of the compressor, and if the conversion condition is not met,
maintaining the first torque characteristic; (d7) resetting the
elapse time after the step (d5) or (d6); and (d8) after the step
(d7), if the second condition is met, operating the compressor, and
if the second condition is not met, continuing to determining
whether or not the second condition is met.
48. The method of claim 47, wherein the conversion condition of the
torque characteristic is a question "doesn't the elapse time reach
a minimum limit time?
49. The method of claim 47, wherein the second condition is a
question "Is the compressor turned on?".
50. The method of claim 47, wherein the step (b) is performed after
the step (c).
51. The method of claim 50, after the step (b), when it is
determined that the motor operates at the second torque
characteristic, determining whether or not it is proper to operate
the motor at the second torque characteristic based on whether or
not a predetermined time elapses, and stopping the compressor the
compressor.
52. The method of claim 51, wherein the step (k) comprises the
steps of: (k1) counting an elapse time (T) while the compressor
operates; (k2) determining whether the elapse time (T) exceeds a
preset maximum limit time (T+) or the elapse time (T) is under a
preset start success determining time (Tt) of the compressor; and
(k3) if the step (k2) is met, determining that it is not proper to
operate the motor at the second torque characteristic and stopping
the compressor.
53. The method of claim 52, further comprising the step of (k4), if
the step (k2) is not met, determining whether or not the compressor
is in Off-state, and if the compressor is in Off-state, determining
that it is proper to operate the motor at the second torque
characteristic.
54. The method of claim 53, further comprising the step of (1)
after the step (k4), resetting the elapse time (T).
55. The method of claim 53, further comprising the step of, in the
step (k4), if it is determined that the compressor is not in
Off-state, returning to the step (k1).
56. The method of claim 54, after the step (1), determining whether
the compressor is turned on, if it is determined that the
compressor is turned on, returning to the step (b), and if it is
determined that the compressor is not turned on, returning to the
step (1).
57. The method of claim 52, further comprising the steps of: (n) if
the compressor is stopped by the step (k3), after a predetermined
time delay, converting the torque characteristic of the motor to
the first torque characteristic; and (o) after the step (n),
resetting the elapse time (T), operating the compressor and then
returning to the step (b).
Description
TECHNICAL FIELD
[0001] The present invention relates to a cooling system and a
method for controlling a compressor thereof and more particularly,
to a cooling system using a compressor in which a motor is
rotatable in forward/reverse directions, and a method for
controlling the compressor.
BACKGROUND ART
[0002] In general, compressors are machines that are supplied power
from a power generator such as electric motor, turbine or the like
and apply compressive work to a working fluid, such as air or
refrigerant to elevate the pressure of the working fluid. Such
compressors are widely used in a variety of applications, from
electric home appliances such as air conditioners, refrigerators
and the like to industrial plants.
[0003] The compressors are classified into two types according to
their compressing methods: a positive displacement compressor, and
a dynamic compressor (a turbo compressor). The positive
displacement compressor is widely used in industry fields and
configured to increase pressure by reducing its volume. The
positive displacement compressors can be further classified into a
reciprocating compressor and a rotary compressor.
[0004] The reciprocating compressor is configured to compress the
working fluid using a piston that linearly reciprocates in a
cylinder. The reciprocating compressor is configured to compress
the working fluid using a piston that linearly reciprocates in a
cylinder. The reciprocating compressor has an advantage of
providing high compression efficiency with a simple structure. The
rotary compressor is configured to compress working fluid using a
roller eccentrically revolving along an inner circumference of the
cylinder, and has an advantage of obtaining high compression
[0005] efficiency at a low speed compared with the reciprocating
compressor, thereby reducing noise and vibration.
[0006] Meanwhile, the reciprocating or rotary compressor used in
the cooling system requires different torques according to various
environmental conditions.
[0007] In other words, since an inner pressure of a refrigeration
pipe is very high at an initial start operation having high
temperature of a refrigerant and high temperature of an object to
be cooled (for example, a food containing chamber in case of a
refrigerator, or an indoor space in case of an air conditioner), a
large torque is required for driving the compressor.
[0008] In addition, when a temperature of the object to be cooled
is increased after the cooling system stops its operation for a
long time and thus the cooling system again operates, the inner
pressure of the refrigeration pipe is high, so that a large torque
is required for driving the cooling system.
[0009] Meanwhile, if the cooling system operates for a long time,
frost is formed on a surface of a heat exchanger absorbing adjacent
heat, resulting in a degradation of heat exchange efficiency.
Therefore, a defrost operation should be carried out periodically.
In this case, temperatures of the heat exchanger and the
refrigerant increase so that a large torque is necessary for
driving the compressor.
[0010] On the contrary, there is also a case of requiring a small
torque when driving the compressor. In other words, in case an
inner pressure of the refrigeration pipe is in a low state when the
compressor is driven, for example, in case a temperature of the
refrigerant is maintained in a low state by maintaining the object
at a low temperature, a small torque is required. In addition, a
small torque is required when the compressor is operated
intermittently with a short period while driving the cooling
system.
[0011] As described above, when driving the compressor, the cooling
system requires different driving torques according to different
conditions. However, although different torques are required
according to different conditions, the torque of the compressor of
the cooling system is unchangeable. Accordingly, the compressor
must have the largest of the torques meeting the above conditions.
In this case, if using a large-capacity compressor, it causes
problems of unnecessary power consumption and increase in a size of
the compressor. Meanwhile, two or more compressors may be used in
order to obtain desired driving torques according to conditions.
However, in this case, the structure of the cooling system is very
inefficient and installation costs are expended excessively.
DISCLOSURE OF INVENTION
[0012] Accordingly, the present invention is directed to a cooling
system and a system for controlling a compressor that substantially
obviate one or more problems due to limitations and disadvantages
of the related art.
[0013] An object of the present invention is to provide a cooling
system using one compressor to generate two different torques
according to operation conditions of the cooling system, and a
system for controlling the compressor.
[0014] Another object of the present invention is to provide a
method for controlling a compressor, which can generate two
different torques, with suitable driving torques and efficiency
according to operation conditions of a cooling system.
[0015] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objectives and other
advantages of the invention may be realized and attained by the
structure particularly pointed out in the written description and
claims hereof as well as the appended drawings.
[0016] To achieve these objects and other advantages and in
accordance with the purpose of the invention, as embodied and
broadly described herein, a system for controlling a compressor of
a cooling system includes: the compressor having a driving shaft
that is rotatable clockwise and counterclockwise and operated by a
power of a motor outputting different torque characteristics
depending on the rotational directions of the driving shaft; a
selector for selecting an output torque characteristic of the
motor, a switching part for turning on or off the motor; and a
control unit for controlling the selector to drive the compressor
in a torque characteristic suitable for an object to be cooled.
[0017] To achieve another object of the present invention, a method
for controlling an operation of a compressor in a cooling system
includes the steps of: (a) an initial starting step of starting the
compressor equipped with a motor different torque characteristics
depending on rotary directions of a driving shaft at a first torque
characteristic; (b) determining the operation torque characteristic
of the motor; (c) when it is determined that the motor operates at
the first torque characteristic in consequence of performing the
step (b), if a first condition is met during an operation of the
compressor, stopping the compressor; (d) determining whether it is
suitable to continuously operate the motor at the first torque
characteristic in a state that the compressor is stopped, and if it
is determined that it is suitable, maintaining the operation torque
characteristic of the motor, while if it is determined that it is
not suitable, converting the operation torque characteristic of the
motor from the first torque characteristic to a second torque
characteristic, and if a second condition is met, operating the
compressor.
[0018] It is to be understood that both the foregoing general
description and the following detailed description of the present
invention are exemplary and explanatory and are intended to provide
further explanation of the invention as claimed.
BRIEF DESCRIPTION OF DRAWINGS
[0019] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this application, illustrate embodiment(s) of
the invention and together with the description serve to explain
the principle of the invention. In the drawings:
[0020] FIG. 1 is a schematic view illustrating a structure of a
cooling system;
[0021] FIG. 2 is a schematic view of a system for controlling a
compressor according to an embodiment of the present invention;
[0022] FIG. 3 is a schematic view of a system for controlling a
compressor according to another embodiment of the present
invention;
[0023] FIG. 4 is a schematic view illustrating an embodiment of the
compressor of FIGS. 2 and 3;
[0024] FIG. 5 is an exploded perspective view illustrating a
compressing unit of the compressor of FIG. 4;
[0025] FIGS. 6A to 6C are cross-sectional views illustrating an
inside of the cylinder when the roller of the compressor shown in
FIG. 4 revolves counterclockwise;
[0026] FIGS. 7A to 7C are cross-sectional views illustrating an
inside of the cylinder when the roller of the compressor shown in
FIG. 4 revolves clockwise;
[0027] FIG. 8 is a schematic view illustrating another embodiment
of the compressor of FIGS. 2 and 3;
[0028] FIG. 9 is an exploded perspective view illustrating a
compressing unit of the compressor of FIG. 8;
[0029] FIG. 10 is a sectional view of the compressing unit shown in
FIG. 9;
[0030] FIG. 11 is a sectional view illustrating an inside of the
cylinder of the compressor shown in FIG. 8;
[0031] FIGS. 12A and 12B are plan views illustrating an embodiment
of a control means of the valve assembly in the compressing unit of
FIG. 9;
[0032] FIGS. 13A to 13C are sectional views illustrating an inside
of the cylinder when the roller of the compressor shown in FIG. 8
revolves counterclockwise;
[0033] FIGS. 14A to 14C are sectional views illustrating an inside
of the cylinder when the roller of the compressor shown in FIG. 8
revolves clockwise;
[0034] FIG. 15 is a flowchart illustrating a method for controlling
a compressor of a cooling system according to an embodiment of the
present invention; and
[0035] FIG. 16 is a flowchart illustrating a method for controlling
a compressor of a cooling system according to another embodiment of
the present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0036] Reference will now be made in detail to the preferred
embodiments of the present invention to achieve the objects, with
examples of which are illustrated in the accompanying drawings.
Wherever possible, the same reference numbers will be used
throughout the drawings to refer to the same or like parts.
[0037] FIG. 1 is a schematic view illustrating a structure of a
cooling system according to the present invention. Referring to
FIG. 1, the cooling system of the present invention includes a
compressor 510, a first heat exchanger 520, a second heat exchanger
530, and an expansion unit 540. Of course, there is provided a
compressor control unit (not shown) for controlling the compressor
510.
[0038] The compressor 510 has a driving shaft which is rotatable in
clockwise or counterclockwise directions. The compressor 510 is
supplied with a power generated by a motor which outputs torque
characteristics variably according to rotation directions of the
driving shaft, which will be described later. The compressor
control unit includes a selector for selecting the output torque
characteristics of the motor, a switching unit for switching on/off
the motor, and a micom for controlling the selector to drive the
compressor according to the torque characteristic suitable for
states of an object to be cooled. The compressor control unit
constructed as above will be described later.
[0039] The compressor 510 compresses sucked refrigerant at high
pressure and discharges it. Therefore, the refrigerant is supplied
with a flowing force to pass through respective elements through a
pipe 550 of the cooling system. The compressed refrigerant is
transferred to the first heat exchanger 520. The first heat
exchanger 520 changes heat between an object to be cooled and an
adiabatic air, thereby condensing the compressed refrigerant. At
this time, a first fan 525 blows an outdoor air to the first heat
exchanger 520. The refrigerant compressed at the first heat
exchanger 520 moves to the expansion unit 540 through the pipe 550.
The expansion unit 540 expands the condensed high-pressure and
low-temperature refrigerant to generate low-pressure and
low-temperature refrigerant. The expanded refrigerant is introduced
into the second heat exchanger 530. The second heat exchanger 530
absorbs and evaporates heat of the object through heat exchange
with an indoor heat exchanger. At this time, a second fan 535
discharges the air, which is cooled due to the heat exchange with
the second heat exchanger 530, toward the object to be cooled so
that the object is cooled. The low-temperature and low-pressure
gaseous refrigerant evaporated at the second heat exchanger 530 is
introduced into the compressor 510. The object continues to be
cooled through a repetition of the above procedures.
[0040] Meanwhile, although not shown, the cooling system according
to the present invention can further include several bypasses to
make the object warm. A brief description on that will be made.
Although not shown, the bypass directly guide the refrigerant
discharged from the compressor 510 to the second heat exchanger
530. At this time, the refrigerant guided by the bypass is directly
introduced into the second heat exchanger 530 through a side which
is not connected to the expansion unit 540. The refrigerant
introduced into the second heat exchanger 530 by the bypass is
condensed through heat exchange with the object to be cooled. At
this time, high-temperature and high-pressure refrigerant emits
heat toward the object to be cooled and is changed into
low-temperature and low-pressure refrigerant. The heat emitted from
the second heat exchanger 530 is discharged to the object through
the second fan 535, thus making the object warm. The refrigerant
heat-exchanged at the second heat exchanger 530 is introduced into
the expansion unit 540 to be changed into low-temperature and
low-pressure refrigerant, and then introduced into the first heat
exchanger 520. At the first heat exchanger 520, the refrigerant
absorbs heat of an outdoor air and is evaporated. Then, the
refrigerant is introduced into the compressor 510. Through
repetition of the above procedures, the cooling system of the
present invention can make the object warm.
[0041] The cooling system of the present invention is applicable to
an air conditioning system for cooling or heating an indoor space,
a refrigerator for cooling a predetermined chamber so as to keeping
foods in a fresh state, and the like. Meanwhile, the cooling system
requires different operation characteristics in various
environmental conditions, more particularly torque characteristics
of the motor. The compressor of the present invention provides an
optimum torque characteristic in various environmental conditions
requiring different torque characteristics. Further, the present
invention provides a system and a method for controlling the
compressor.
[0042] Hereinafter, the system and the method for controlling the
compressor will be described in detail with reference to the
accompanying drawings.
[0043] FIG. 2 is a schematic view of a system for controlling the
compressor according to an embodiment of the present invention, and
FIG. 3 is a schematic view of a system for controlling the
compressor according to another embodiment of the present
invention. Each embodiment of the present invention will be
described with reference to FIGS. 2 and 3.
[0044] Referring to FIG. 2, the system for controlling the
compressor according to an embodiment of the present invention
includes a compressor, a selector 620, a switching unit 650, and a
control unit 610. The compressor is provided with a power generator
(i.e., a motor) for generating power, and a compressing unit being
supplied with the power to compress a refrigerant and discharge the
compressed refrigerant. A structure of the compressing unit will be
described later in detail with reference to FIGS. 4 to 14C, and a
brief description on the motor will be described herein.
[0045] The motor used in the compressor of the present invention
has a driving shaft 13 which is rotatable counterclockwise and
clockwise and outputs different torque characteristics depending on
rotation directions of the driving shaft 13. To achieve this, the
motor includes: a first winding 634 connecting a first terminal 632
and a common terminal 631 and rotating the drive shaft 13 in a
first torque characteristic; and a second winding 635 connecting a
second terminal 632 and the common terminal 631 and rotating the
drive shaft 13 in a second torque characteristic. Here, for the
convenience of explanation, it is assumed that the first torque is
greater than the second torque, and the driving shaft 13 rotates
counterclockwise when the first torque can be obtained, i.e., when
the power is supplied to the first winding side. According to the
compressor of the present invention, in order to obtain a large
torque when the driving shaft 13 rotates counterclockwise, the
first winding 634 should have a thick coil whose diameter is large
and also have a large number of turns. On the contrary, when the
driving shaft 13 rotates clockwise, an efficiency in operation
should be high although the torque is small. Therefore, the second
winding 635 should have a diameter smaller than the first winding
634 and also have a small number of turns. By doing so, the first
winding 634 is used to rotate the driving shaft 13 counterclockwise
in an initial start operation requiring a large torque, or when a
pressure of a refrigerant circulation line is in a high state due
to a high temperature of the object to be cooled or the
refrigerant. When a relatively small torque is required, in other
words, when a pressure of the refrigerant circulation line is in a
low state due to a low temperature of the object to be cooled or
the refrigerant, the second winding 635 is used to rotate the
driving shaft 13 clockwise. Compared with the case of using the
first winding 634 to rotate the driving shaft 13, the case of using
the second winding 635 to rotate the driving shaft 13 has a smaller
output torque and reduces power consumption, so that the cooling
system can be operated very economically.
[0046] The selector 620 selects the output torque characteristics
of the motor under a control of the control unit 610. To achieve
this, the selector includes a first contact point 623 connected
with the first terminal 633, a second contact point 622 connected
with the second terminal 632, and a common contact point 621
connected to the first contact point 623 or the second contact
point 622. If the selector 620 is constructed as above, the control
unit 620 can control the selector 620 to output the torque
characteristics suitable for the adjacent environment of the motor.
In other words, if the adjacent environment requires for the
compressor to output a large torque, the control unit 610 transmits
a control signal to the selector 620 to thereby connect the common
contact point 621 with the second contact point 622.
[0047] The switching unit 650 turns on/off the motor of the
compressor. In the system for controlling the compressor of the
cooling system according to the present invention, the switching
unit 650 is controlled by the control unit 610. In other words,
based on external information, the control unit 610 determines
whether the cooling system operates or not. If the control unit 620
intends to operate the cooling system, the control unit 610
transmits the control signal to the switching unit 650 to thereby
turn on the switching unit 650. Then, a circuit for supplying a
power to the motor is turned on and thus the power is supplied to
the motor from a winding side selected by the selector 620. As a
result, the driving shaft 13 is driven by either of the first and
second torques. On the other hand, if the control unit 620 intends
to stop the cooling system, the control unit 620 transmits the
control signal to the switching unit 650 to thereby turn off the
switching unit 650. Then, the circuit for supplying the power to
the motor is turned off and thus the power is supplied to the
motor. As a result, the motor stops its operation.
[0048] In the system for controlling the compressor according to
the present invention, the control unit 610 controls the selector
620 and the switching unit 650 on the basis of information on the
object to be cooled. Here, the information on the object to be
cooled can be obtained through a sensing means, e.g., a temperature
sensor for measuring a temperature of the object to be cooled. In
FIG. 2, the temperature sensor senses temperatures of the food
containing chamber or the indoor space and transits the temperature
information to the control unit 610. Then, the control unit 620
controls the selector 620 and the switching unit 650 on the basis
of the temperature information transmitted from the sensing means,
e.g., the temperature sensor.
[0049] Meanwhile, an overload protector is connected in series
between the switching unit 650 and the motor in order to prevent
the motor from being damaged due to an overload phenomenon. A
plurality of capacitors 645 are connected in parallel between the
motor and the selector 620. An undescribed reference numeral "646"
is a positive temperature coefficient (P.T.C), which serves to
effectively protect the circuit by limiting an excess current in an
initial stage, or to effectively support the start of the
compressor by improving an initial start torque at a start circuit
of the compressor.
[0050] Hereinafter, an operation of the system for controlling the
compressor according to the present invention will be described in
brief.
[0051] When the control unit 610 performs an operation of starting
the compressor on the basis of the temperature measured by the
temperature sensor 60, the control unit 610 transmits the control
signal to the switching unit 650 to thereby turn on the switching
unit 650. Then, the circuit for supplying the power to the motor is
turned on and thus the power is supplied to the motor. As a result,
the driving shaft 13 rotates so that the cooling system is driven.
Here, the common contact point 621 of the selector 620 is connected
to either of the first and second contact points 623 and 622 before
the switching unit 650 is turned on. To achieve this, the control
unit 610 may control the selector 620 before the switching unit 650
is turned on, or may continuously maintain the previous state when
the cooling system is stopped. Meanwhile, in a state that the
common contact point 621 is connected to the first contact point
623, if the switching unit 650 is turned on, the motor start to
operate with the first torque. In a state that the common contact
point 621 is connected to the second contact point 622, if the
switching is turned on, the motor starts to operate with the second
torque.
[0052] If the motor is driven, the cooling system starts to
operate. If the cooling system operates for a predetermined time,
the temperature of the room is also changed. The temperature of the
room is detected by the temperature sensor 660, and the detected
information is transmitted to the control unit 610. Then, the
control unit 610 determines an operation method of the cooling
system, i.e., whether to continue to operate the cooling system
with a current torque, whether to stop the cooling system, or
whether to operate the cooling system with a changed torque. At
this time, in case the control unit 610 determines to operate the
cooling system with the changed torque, the control unit 610
transmits the control signal to the switching unit 650 to thereby
turn off the switching unit 650. Then, the control unit 610
transmits the control signal to the selector 620 to thereby change
the connection state between the common contact point 621 and other
contact points 622 and 623. After the connection state is changed,
the switching unit 650 is turned on. Then, the compressor operates
according to the changed torque characteristic. Accordingly, in an
embodiment of the present invention, the cooling system can be
operated suitably according to the state of the object to be
cooled. A method for controlling the compressor of the cooling
system according to an embodiment of the present invention will be
described later.
[0053] Meanwhile, referring to FIG. 3, a system for controlling the
compressor according to another embodiment of the present invention
includes a control unit 610, a selector 620, a power generator 10,
and a switching unit 670. Here, since the structures of the control
unit 610, the selector 620 and the power generator 10 are identical
to those of FIG. 2, their detailed description will be omitted.
[0054] In the system for controlling the compressor according to
another embodiment of the present invention, as shown in FIG. 3,
the switching unit 670 includes a thermostat, of which contact
points are on/off according to temperatures of the object to be
cooled. Here, the thermostat is provided with, e.g., a bimetal. For
example, the switching unit 670 is configured to switch on the
contact point when the temperature of the indoor space or the food
containing chamber is above a predetermined level, and to switch
off when the temperature is below the predetermined level. The
switching unit 670 constructed as above drives or stops the motor
according to conditions of the room without any control of the
control unit 610. In this case, the control unit 610 controls the
selector 620 by checking an elapse of time, so that the cooling
system is effectively operated.
[0055] Meanwhile, the system for controlling the compressor
according to another embodiment of the present invention further
includes means for determining whether the motor is turned on or
off. Here, the determining means is provided with a current sensor
690 for sensing a current through the switching unit 670. In this
case, when the temperature of the room increases or decreases to
thereby turn on or off the switching unit 670, the current sensor
690 senses whether or not the motor operates and transmits
corresponding information to the control unit 610. With the
information on the operation of the motor, the control unit 610
checks an elapse of time and controls the selector 620, so that the
cooling system is controlled more effectively.
[0056] Meanwhile, the system according to another embodiment of the
present invention further includes a second switching unit 680
connected in series to the switching unit 370. Unlike the switching
unit 670, the second switching unit 680 is turned on/off by the
control unit 610. In this case, the control unit 610 can control
the selector 620 on the basis of the elapse of time, and can
control the second switching unit 680 to forcibly stop the motor.
Here, during the driving of the motor, the control unit 610 can
forcibly stop the motor by opening the contact point of the second
switching unit 680. However, during the stopping of the motor, the
control unit 610 cannot forcibly operate the motor. Here, the case
of not driving the motor is the case that either of the switching
unit 670 and the second switching unit 680 is opened. If the
switching unit 670 is opened, the motor is not driven even when the
control unit 610 closes the contact point of the second switching
unit 680. Thus, in the system according to another embodiment of
the present invention, the control unit 610 checks the elapse of
time and controls the compressor on the basis of information on the
elapse of time during the driving of the motor.
[0057] Hereinafter, an operation of the system according to another
embodiment of the present invention will be described in brief.
[0058] For example, if the temperature of the room increases, the
switching unit 670 is automatically turned on to drive the motor.
Of course, like the embodiment described above with reference to
FIG. 2, the common contact point 621 is connected to any one of
other contact points before the motor is driven. If it is assumed
that the common contact point 621 is connected to the first contact
point 623, the motor is driven with the first torque as soon as the
switching unit 670 is turned on. If the motor is driven, the
current sensor 690 informs the control unit 610 that the motor is
driven. The control unit 610 checks an elapse of time while
recognizing the driving of the motor. The control unit 610 can
change the torque characteristic by transmitting the control signal
to the second switching unit 680 after a predetermined time, or by
transmitting the control signal to the selector 620 after stopping
the motor. After the torque characteristic of the motor is changed
by the selector 620, the control unit 610 can control the second
switching unit 680 to drive the motor again. Of course, after a
predetermined time, the contact point of the switching unit 670 may
be automatically opened due to an operation of the thermostat, so
that the motor is stopped. According to the present invention, the
system for controlling the compressor operates suitably according
to the conditions since the cooling system immediately responds to
the temperature of the room. Of course, the system for controlling
the compressor according to another embodiment of the present
invention requires an elaborate control algorithm based on the
driving of the motor and the elapse of time. An operation of the
system for controlling the compressor according to another
embodiment of the present invention will be described below in more
detail.
[0059] Hereinafter, a structure of a compressor in the cooling
system according to the present invention will be described in
detail with reference to the accompanying drawings.
[0060] FIG. 4 is a schematic view of the compressor of FIG. 2 or 3
according to an embodiment of the present invention. FIG. 5 is an
exploded perspective view illustrating a compressing unit of the
compressor of FIG. 4.
[0061] As shown in FIG. 4, the rotary compressor of the present
invention includes a case 1, a power generator 10 positioned in the
case 1, i.e., a motor, and a compressing unit 20. Referring to FIG.
4, the power generator 10 is positioned on the upper portion of the
compressor and the compressing unit 20 is positioned on the lower
portion of the compressor. However, their positions may be changed
if necessary. An upper cap 3 and a lower cap 5 are installed on the
upper portion and the lower portion of the case 1 respectively to
define a sealed inner space. A suction pipe 7 for sucking working
fluid is installed on a side of the case 1 and connected to an
accumulator 8 for separating lubricant from refrigerant. A
discharge tube 9 for discharging the compressed fluid is installed
on the center of the upper cap 3. A predetermined amount of the
lubricant "0" is filled in the lower cap 5 so as to lubricate and
cool members that are moving frictionally. Here, an end of a
driving shaft 13 is dipped in the lubricant.
[0062] The power generator 10 includes a stator 11 fixed in the
case 1, a rotor 12 rotatable supported in the stator 11 and the
driving shaft 13 inserted forcibly into the rotor 12. The rotor 12
is rotated due to electromagnetic force, and the driving shaft 13
delivers the rotation force of the rotor to the compressing unit
20. To supply external power to the stator 20, a terminal 4 is
installed in the upper cap 3.
[0063] The compressing unit 20 includes a cylinder 21 fixed to the
case 1, a roller 22 positioned in the cylinder 21 and upper and
lower bearings 24 and 25 respectively installed on upper and lower
portions of the cylinder 21. The compressing unit 20 will be
described in more detail with reference to FIGS. 2, 3 and 4.
[0064] The cylinder 21 has a predetermined inner volume and a
strength enough to endure the pressure of the fluid. The cylinder
21 accommodates an eccentric portion 13a formed on the driving
shaft 13 in the inner volume. The eccentric portion 13a is a kind
of an eccentric cam and has a center spaced by a predetermined
distance from its rotation center. The cylinder 21 has a groove 21b
extending by a predetermined depth from its inner circumference. A
vane 23 to be described below is installed on the groove 21b. The
groove 21b is long enough to accommodate the vane 23 completely. As
shown in FIGS. 4 and 5, the suction ports 27 communicating with the
fluid chamber 29 are formed at the cylinder 21. The suction ports
27 guide the compressed fluid to the fluid chamber 29. The suction
ports 27 are connected to the suction pipe 7 so that the fluid
outside of the compressor can flow into the chamber 29. More
particularly, the suction pipe 7 is connected to the suction ports
27 through a connection pipe 7 so that prior-to-compressed fluid
can be supplied to the fluid chamber 29.
[0065] The roller 22 is a ring member that has an outer diameter
less than the inner diameter of the cylinder 21. As shown in FIG.
4, the roller 22 contacts the inner circumference of the cylinder
21 and rotatably coupled with the eccentric portion 13a
Accordingly, the roller 22 performs rolling motion on the inner
circumference of the cylinder 21 while spinning on the outer
circumference of the eccentric portion 13a when the driving shaft
13 rotates. The roller 22 revolves spaced apart by a predetermined
distance from the rotation center `0` due to the eccentric portion
13a while performing the rolling motion. Since the outer
circumference of the roller 22 always contacts the inner
circumference due to the eccentric portion 13a, the outer
circumference of the roller 22 and the inner circumference of the
cylinder form a separate fluid chamber 29 in the inner volume. The
fluid chamber 29 is used to suck and compress the fluid in the
rotary compressor.
[0066] The vane 23 is installed in the groove 21b of the cylinder
21 as described above. An elastic member 23a is installed in the
groove 21b to elastically support the vane 23. The vane 23
continuously contacts the roller 22. In other words, the elastic
member 23a has one end fixed to the cylinder 21 and the other end
coupled with the vane 23, and pushes the vane 23 to the side of the
roller 22. Accordingly, the vane 23 divides the fluid chamber 29
into two separate spaces 29a and 29b as shown in FIG. 4. While the
driving shaft 13 rotate or the roller 22 revolves, the volumes of
the spaces 29a and 29b change complementarily. In other words, if
the roller 22 rotates clockwise, the space 29a gets smaller but the
other space 29b gets larger. However, the total volume of the
spaces 29a and 29b is constant and approximately same as that of
the predetermined fluid chamber 29. One of the spaces 29a and 29b
works as a suction chamber for sucking the fluid and the other one
works as a compression chamber for compressing the fluid relatively
when the driving shaft 13 rotates in one direction (clockwise or
counterclockwise). Accordingly, as described above, the compression
chamber of the spaces 29a and 29b gets smaller to compress the
previously sucked fluid and the suction chamber expands to suck the
new fluid relatively according to the rotation of the roller 22. If
the rotation direction of the roller 22 is reversed, the functions
of the spaces 29a and 29b are exchanged. In the other words, if the
roller 22 revolves counterclockwise, the right space 29b of the
roller 22 becomes a compression chamber, but if the roller 22
revolves clockwise, the left space 29a of the roller 22 becomes a
discharge unit.
[0067] The upper bearing 24 and the lower bearing 25 are, as shown
in FIG. 4, installed on the upper and lower portions of the
cylinder 21 respectively, and rotatably support the driving shaft
12 using a sleeve and the penetrating holes 24b and 25b formed
inside the sleeve. More particularly, the upper bearing 24, the
second bearing 25 and the cylinder 21 include a plurality of
coupling holes 24a, 25a and 21a formed to correspond to each other
respectively. The cylinder 21, the upper bearing 24 and the lower
bearing 25 are coupled with one another to seal the cylinder inner
volume, especially the fluid chamber 29 using coupling members such
as bolts and nuts.
[0068] The discharge ports 26a and 26b are formed on the upper
bearing 24. The discharge ports 26a and 26b communicate with the
fluid chamber 29 so that the compressed fluid can be discharged.
The discharge ports 26a and 26b can communicate directly with the
fluid chamber 29 or can communicate with the fluid chamber 29
through a predetermined fluid passage 21d formed in the cylinder 21
and the first bearing 24. Discharge valves 26c and 26d are
installed on the upper bearing 24 so as to open and close the
discharge ports 26a and 26b. The discharge valves 26c and 26d
selectively open the discharge ports 26a and 26b only when the
pressure of the chamber 29 is greater than or equal to a
predetermined pressure. To achieve this, it is desirable that the
discharge valves 26c and 26d are leaf springs of which one end is
fixed in the vicinity of the discharge ports 26 and 26b and the
other end can be deformed freely. As shown, retainers 26e and 26f
for limiting the deformation of the valves in order for the values
to operate stably can be installed on upper portions of the
discharge valves 26c and 26d. The retainer 26e and 26f are provided
so as to secure the stable operations of the discharge valves 26c
and 26d and disposed contacting the discharge valves 26c and 26d to
control the opening extents of the discharge valves 26c and 26d. If
there are no retainers 26e and 26f, the discharge valves 26c and
26d may be deformed due to the high pressure, whereby the
reliability of the discharge valves 26c and 26d may be
deteriorated.
[0069] A muffler 140 is disposed above the upper bearing 24. The
muffler 140 reduces noise generated when the compressed fluid is
discharged. For this, the muffler 140 encloses an upper space of
the discharge ports 26a and 26b, and an additional discharge 141 is
formed at one side of the muffler 140.
[0070] Meanwhile, the revolution direction of the roller 22 and the
location of the suction port 27 are very important factors for
determining the compression capacity in a preferred embodiment of
the present invention. Their relationship will be described in more
detail hereinafter.
[0071] FIG. 6A is a sectional view illustrating an inside of the
cylinder when the roller of the compressor of FIG. 4 revolves
counterclockwise. As shown in the drawing, the fluid chamber 29 is
divided into the two spaces 29a and 29b by the vane 23 and the
roller 22. The discharge ports 26a and 26b are respectively located
on each side of the vane 23 to continuously compress fluid
regardless of the revolution direction of the roller 22. In other
words, regardless of the revolution direction of the roller, at
least one of the discharge ports 26a and 26b is opened between the
suction port 27 and the vane 23. At this point, it is preferable
that a distance between the vane 23 and the discharge port 26a is
identical to that between the vane 23 and the discharge port
27b.
[0072] Here, the compression chamber 200 is divided into a suction
portion for sucking gas through the suction port 27 by the vane 23
and the roller 22, and a discharge portion for discharging the
fluid gas through one of the discharge ports 26a and 26b. At this
point, the suction portion and the discharge portion are determined
according to the revolution direction of the roller 22. In other
words, when the roller 22 revolves counterclockwise, a right space
210 with respect to the roller 22 becomes the discharge portion,
and when the roller 22 revolves clockwise, a left space 220 becomes
the discharge portion.
[0073] Meanwhile, the compression capacity of the compressor is
determined by volumes of the discharge portions 29a and 29b. The
volumes of the discharge portions 29a and 29b are determined by
spaces enclosed by the cylinder 50 and the roller 22 from the
suction port 27 to the vane 23. Accordingly, the compression
capacity is determined by the location of the suction port 27.
[0074] For example, when the suction port 27 is located on a
phantom line extending from a longitudinal axis of the vane 23, in
other words, when the suction port 27 is located spaced away from
the vane 23 by an angular distance of about 180.degree., the volume
of the discharge portion 29a becomes identical to that of the
discharge portion 29b. Therefore, an identical capacity can be
obtained from the compressor regardless of the revolution direction
of the roller 22.
[0075] However, when the suction port 27 is located on one side of
the phantom line extending from the longitudinal axis of the vane
23, the discharge portions 29a and 29b of the compression chamber
29 become different in their volumes. That is, as shown in FIG. 6A,
the compression chamber 29 is divided in the left and right spaces
29a and 29b. The left space 29a is defined by a counterclockwise
angular distance between the vane 23 and the suction port 26, and
the right space 29b is defined by a clockwise angular distance
between the vane 23 and the suction port 26, the counterclockwise
angular distance being less than the clockwise angular distance. At
this point, the spaces 29a and 29b become low and high capacity
discharge portions 29b and 29a in accordance with the revolving
direction of the roller 22. This shows that the rotary compressor
of the present invention has a dual-capacity.
[0076] The location of the suction port 27 is then determined by a
compression ratio between the high and low capacity discharge
portions 29b and 29a. For example, the present invention proposes a
clockwise angular distance of about 180-300.degree. between the
vane 23 and the suction port 27. When the clockwise angular
distance between the vane 23 and the suction port 26 is
180.degree., the compression ratio between the spaces 29b and 29a
becomes 50:50. When the clockwise angular distance between the vane
23 and the suction port 27 is about 270.degree., the compression
ratio between the spaces 29b and 29a is about 75:25.
[0077] The operation of the rotary compressor of the present
invention will now be described in more detail.
[0078] FIGS. 6A to 6C show consecutive operating steps of the
rotary compressor when the roller revolves counterclockwise. FIG.
6A shows an initial fluid intake step, FIG. 6B shows a fluid
compression/discharge step, and FIG. 6C shows a discharge
completion step.
[0079] As the driving shaft 13 rotates, the roller 22 rotates and
revolves counterclockwise along the inner circumference of the
cylinder 50. During this process, the suction port 27 is opened so
that fluid is sucked into the fluid chamber through the suction
port 27. The fluid is then directed to the high capacity discharge
portion 29b by the roller 22 as shown in FIG. 6A.
[0080] As the roller 22 further revolves, the volume of the high
capacity discharge portion 29b is reduced to compress the fluid.
During this process, the vane 23 maintains the seal of the high
capacity discharge portion 29b while elastically reciprocating by
the spring 23a and the roller 22, at the same time of which fluid
is continuously fed into the high capacity discharge portion 29b
through the suction port 27.
[0081] After the above, when pressure of the high capacity
discharge portion 29b is increased above a predetermined level, the
discharge valve 26d of the high capacity discharge portion 29b is
opened. Accordingly, the fluid in the high capacity discharge
portion 29b starts being discharged to the muffler through the
discharge port 26b, as shown in FIG. 6B.
[0082] Then, when the roller further revolves, the fluid in the
high capacity discharge portion 29b is completely discharged to the
muffler through the discharge port 26b, after which the discharge
valve 26d closes the discharge port 26b using its self-elastic
force, as shown in FIG. 6C.
[0083] FIGS. 7A and 7B show consecutive operating steps of the
rotary compressor when the roller revolves clockwise. FIG. 7A shows
an initial fluid intake step, and FIG. 7B shows a fluid
compression/discharge step.
[0084] As the driving shaft 13 rotates, the roller 22 rotates and
revolves clockwise along the inner circumference of the cylinder
21. During this process, the suction port 27 is opened so that
fluid is sucked into the compression chamber through the suction
port 27. At this point, the fluid is directed to the low capacity
discharge portion 29a by the roller 22.
[0085] As the roller 22 further revolves, the volume of the low
capacity discharge portion 29a is reduced to compress the fluid, at
the same time of which fluid is continuously fed through the
suction port 27.
[0086] After the above, when pressure of the low capacity discharge
portion 29a is increased above a predetermined level, the discharge
valve 26c of the low capacity discharge portion 29a is opened.
Accordingly, the fluid in the low capacity discharge portion 29a
starts being discharged to the muffler through the discharge port
26a, as shown in FIG. 7B.
[0087] Then, when the roller 22 further revolves, the fluid in the
low capacity discharge portion 29a is completely discharged to the
muffler through the discharge port 26a, after which the discharge
valve 26c closes the discharge port 26a using its self-elastic
force.
[0088] After the above, as the roller 22 further revolves
clockwise, the fluid is further discharged to the muffler through
the above-described intake, compression, and discharge steps.
[0089] As shown in FIG. 4, the compressed gas in the muffler 140 is
discharged into the case 1 through the discharge port 141, and is
then further directed to a desired destination through a space
between the rotor 12 and the stator 11 or a space between the
stator 11 and the case 1.
[0090] Meanwhile, in FIG. 8, there is shown a compressor of the
compressor control system according to another embodiment of the
present invention. The compressor according to another embodiment
of the present invention will be described in detail hereinafter.
FIG. 8 is a longitudinal sectional view illustrating a construction
of the compressor, FIG. 9 is an exploded perspective view
illustrating a compressing unit of the compressor, and FIG. 10 is a
sectional view of the compressing unit.
[0091] Referring to FIG. 8, the compressor according to another
embodiment of the present invention includes a power generator 10
and a compressing unit 20, and the compressing unit 20 includes a
cylinder 21, upper and lower bearings 24 and 25, and a valve
assembly 100. In this embodiment, the same structure as the
embodiment of FIGS. 4 to 7c will be omitted.
[0092] The upper bearing 24 is provided with discharge ports 26a
and 26b, communicating with the fluid chamber 29 to discharge the
compressed fluid out of the fluid chamber 29. The discharge ports
26a and 26b may be directly communicated with the fluid chamber 29,
or be communicated with the same through a fluid passage 21d formed
on the cylinder 21 and the upper bearing 24. An opening/closing
operation of the discharge ports 26a and 26b is controlled by
discharge valves 26c and 26d, installed on the upper bearing 24.
The discharge valves 26c and 26d selectively open the discharge
ports 26a and 26b only when the pressure of the fluid chamber 29 is
increased to above a predetermined level. To achieve this, it is
desirable that the discharge valves 26c and 26d are leaf springs of
which one end is fixed in the vicinity of the discharge ports 26a
and 26b and the other end can be deformed freely. Although not
shown, retainers for limiting the deformation of the valves in
order for the values to operate stably can be installed on upper
portions of the discharge valves 26c and 26d. In addition, a
muffler (not shown) can be installed on the upper portion of the
upper bearing 24 to reduce a noise generated when the compressed
fluid is discharged.
[0093] The suction ports 27a, 27b and 27c communicating with the
fluid chamber 29 are formed on the lower bearing 25. The suction
ports 27a, 27b and 27c guide the compressed fluid to the fluid
chamber 29. The suction ports 27a, 27b and 27c are connected to the
suction pipe 7 so that the fluid outside of the compressor can flow
into the chamber 29. More particularly, the suction pipe 7 is
branched into a plurality of auxiliary tubes 7a and is connected to
suction ports 27 respectively. If necessary, the discharge ports
26a, and 26b may be formed on the lower bearing 25 and the suction
ports 27a, 27b and 27c may be formed on the upper bearing 24.
[0094] Meanwhile, it is preferable to provide a plenum 200
communicating with the suction ports 27a, 27b and 27c and
preliminarily storing fluid so that the fluid can be supplied to
the fluid chamber 29 of the cylinder 21.
[0095] The suction plenum 200 directly communicates with all of the
suction ports 27a, 27b and 27c so as to supply the fluid.
Accordingly, the suction plenum 200 is installed in a lower portion
of the lower bearing 25 in the vicinity of the suction ports 27a,
27b and 27c. Although there is shown in the drawing that the
suction ports 27a, 27b and 27c are formed at the lower bearing 25,
they can be formed at the upper bearing 24 if necessary. In this
case, the suction plenum 200 is installed in the upper bearing 24.
The suction plenum 200 can be directly fixed to the lower bearing
25 by a welding. In addition, a coupling member can be used to
couple the suction plenum 200 with the cylinder 21, the upper and
lower bearings 24 and 25 and the valve assembly 100. In order to
lubricate the driving shaft 13, a sleeve 25d of the lower bearing
25 should be soaked into a lubricant which is stored in a lower
portion of the case 1. Accordingly, the suction plenum 200 includes
a penetration hole 200a for the sleeve. Preferably, the suction
plenum 200 has one to four times a volume as large as the fluid
chamber 29 so as to supply the fluid stably. The suction plenum 200
is also connected with the suction pipe 7 so as to store the fluid.
In more detail, the suction plenum 200 can be connected with the
suction pipe 7 through a predetermined fluid passage. In this case,
as shown in FIG. 10, the fluid passage penetrates the cylinder 21,
the valve assembly 100 and the lower bearing 25. In other words,
the fluid passage includes a suction hole 21c of the cylinder 21, a
suction hole 122 of the second valve, and a suction hole 25c of the
lower bearing 25.
[0096] Such a suction plenum 200 forms a space in which a
predetermined amount of fluid is always stored, so that a
compression variation of the sucked fluid is buffered to stably
supply the fluid to the suction ports 27a, 27b and 27c. In
addition, the suction plenum 200 can accommodate oil extracted from
the stored fluid and thus assist or substitute for the accumulator
8.
[0097] The suction and discharge ports 26 and 27 become the
important factors in determining compression capacity of the rotary
compressor and will be described referring to FIG. 11. FIG. 11
illustrates a cylinder coupled with the lower bearing 25 without a
valve assembly 100 to clearly show the suction ports 27.
[0098] First, the compressor of the present invention includes at
least two discharge ports 26a and 26b. As shown in the drawing,
even if the roller 22 revolves in any direction, one discharge port
should exist between the suction port and vane 23 positioned in the
revolution path to discharge the compressed fluid. Accordingly, one
discharge port is necessary for each rotation direction. It causes
the compressor of the present invention to discharge the fluid
independent of the revolution direction of the roller 22 (that is,
the rotation direction of the driving shaft 13). Meanwhile, as
described above, the compression chamber of the spaces 29a and 29b
gets smaller to compress the fluid as the roller 22 approaches the
vane 23. Accordingly, the discharge ports 26a and 26b are
preferably formed facing each other in the vicinity of the vane 23
to discharge the maximum compressed fluid. In other word, as shown
in the drawings, the discharge ports 26a and 26b are positioned on
both sides of the vane 23 respectively. The discharge ports 26a and
26b are preferably positioned in the vicinity of the vane 23 if
possible.
[0099] The suction port 27 is positioned properly so that the fluid
can be compressed between the discharge ports 26a and 26b and the
roller 22. Actually, the fluid is compressed from a suction port to
a discharge port positioned in the revolution path of the roller
22. In other words, the relative position of the suction port for
the corresponding discharge port determines the compression
capacity and accordingly two compression capacities can be obtained
using different suction ports 27 according to the rotation
direction. Accordingly, the compression of the present invention
has first and second suction ports 27a and 27b corresponding to two
discharge ports 26a and 26b respectively and the suction ports are
separated by a predetermined angle from each other with respect to
the center 0 for two different compression capacities.
[0100] Preferably, the first suction port 27a is positioned in the
vicinity of the vane 23. Accordingly, the roller 22 compresses the
fluid from the first suction port 27a to the second discharge port
26b positioned across the vane 23 in its rotation in one direction
(counterclockwise in the drawing). The roller 22 compress the fluid
due to the first suction port 27a by using the overall chamber 29
and accordingly the compressor has a maximum compression capacity
in the counterclockwise rotation. In other words, the fluid as much
as overall volume of the chamber 29 is compressed. The first
suction port 27a is actually separated by an angle 1 of 10.degree.
clockwise or counterclockwise from the vane 23. The drawings of the
present invention illustrates the first suction port 27a separated
by the angle .theta.1 counterclockwise. At this separating angle
.theta.1, the overall fluid chamber 29 can be used to compress the
fluid without interference of the vane 23.
[0101] The second suction port 27b is separated by a predetermined
angle from the first suction port 27a with respect to the center.
The roller 20 compresses the fluid from the second suction port 27b
to the first discharge port 26a in its rotation in counterclockwise
direction. Since the second suction port 27b is separated by a
considerable angle clockwise from the vane 23, the roller 22
compresses the fluid by using a portion of the chamber 29 and
accordingly the compressor has the less compression capacity than
that of counterclockwise rotary motion. In other words, the fluid
as much as a portion volume of the chamber 29 is compressed. The
second suction port 27b is preferably separated by an angle
.theta.2 of a range of 90-180.degree. clockwise or counterclockwise
from the vane 23. The second suction port 27b is preferably
positioned facing the first suction port 27a so that the difference
between compression capacities can be made properly and the
interference can be avoid for each rotation direction.
[0102] As shown in FIG. 11, the suction ports 27a and 27b are
generally in circular shapes. In order to increase a suction amount
of fluid, the suction ports 27a and 27b can also be provided in
several shapes, including a rectangle. Further, as shown in FIGS.
12A and 12B, the suction ports 27a and 27b can be in rectangular
shapes having predetermined curvature. In this case, an
interference with adjacent other parts, especially the roller 22,
can be minimized in operation.
[0103] Meanwhile, in order to obtain desired compression capacity
in each rotation direction, suction ports that are available in any
one of rotation directions should be single. If there are two
suction ports in rotation path of the roller 22, the compression
does not occur between the suction ports. In other words, if the
first suction port 27a is opened, the second suction port 27b
should be closed, and vice versa Accordingly, for the purpose of
electively opening only one of the suction ports 27a and 27b
according to the revolution direction of the roller 22, the valve
assembly 100 is installed in the compressor of the present
invention.
[0104] The valve assembly 100 includes first and second valves 110
and 120, which are installed between the cylinder 21 and the lower
bearing 25 so as to allow it to be adjacent to the suction ports.
If the suction ports 27a, 27b and 27c are formed on the upper
bearing 24, the first and second valves 110 and 120 are installed
between the cylinder 21 and the upper bearing 24.
[0105] The first valve 110 is a disk member installed so as to
contact the eccentric portion 13a more accurately than the driving
shaft 13. Accordingly, if the driving shaft 13 rotates (that is,
the roller 22 revolves), the first valve 110 rotates in the same
direction. Preferably, the first valve 110 has a diameter larger
than an inner diameter of the cylinder 21. The cylinder 21 supports
a portion (i.e., an outer circumference) of the first valve 110 so
that the first valve 110 can rotate stably.
[0106] The first valve 110 includes first and second openings 111
and 112 respectively communicating with the first and second
suction ports 27a and 27b in specific rotation direction, and a
penetration hole 110a into which the driving shaft 13 is inserted.
In more detail, when the roller 22 rotates in any one of the
clockwise and counterclockwise directions, the first opening 111
communicates with the first suction port 27a by the rotation of the
first valve 110, and the second suction port 27b is closed by the
body of the first valve 110. When the roller 22 rotates in the
other of the clockwise and counterclockwise directions, the second
opening 112 communicates with the second suction port 27b. At this
time, the first suction port 27a is closed by the body of the first
valve 110. These first and second openings 111 and 112 can be in
circular or polygonal shapes. Additionally, as shown in FIGS. 12A
and 12B, the openings 111 and 112 can be rectangular shapes having
predetermined curvature. As a result, the openings are enlarged,
such that fluid is sucked smoothly. If these openings 111 and 112
are formed adjacent to a center of the first valve 110, a
probability of interference between the roller 22 and the eccentric
portion 13a becomes increasing. In addition, there is the fluid's
probability of leaking out along the driving shaft 13, since the
openings 111 and 112 communicate with a space between the roller 22
and the eccentric portion 13a. For these reasons, it is preferable
that the openings 111 and 112 are positioned in the vicinity of the
outer circumference of the first valve. Meanwhile, the first
opening 111 may open each of the first and second suction ports 27a
and 27b at each rotation direction by adjusting the rotation angle
of the first valve 110. In other words, when the driving shaft 13
rotates in any one of the clockwise and counterclockwise
directions, the first opening 111 communicates with the first
suction port 27a while closing the second suction port 27b. When
the driving shaft 13 rotates in the other of the clockwise and
counterclockwise directions, the first opening 111 communicates
with the second suction port 27b while closing the first suction
port 27a. It is desirable to control the suction ports using such a
single opening 111, since the structure of the first valve 110 is
simplified much more.
[0107] The second valve 120 is fixed between the cylinder 21 and
the lower bearing 25 so as to guide a rotary motion of the first
valve 110. The second valve 120 is a ring-shaped member having a
site portion 121 which receives rotatably the first valve 110. The
second valve 120 further includes a coupling hole 120a through
which it is coupled with the cylinder 21 and the first and second
bearings 24 and 25 by a coupling member. Preferably, the second
valve 120 has the same thickness as the first valve 110 in order
for a prevention of fluid leakage and a stable support. In
addition, since the first valve 110 is partially supported by the
cylinder 21, the first valve 110 may have a thickness slightly
smaller than the second valve 120 in order to form a gap for the
smooth rotation of the second valve 120.
[0108] Meanwhile, referring to FIG. 11, in the case of the
clockwise rotation, the fluid's suction or discharge between the
vane 23 and the roller 22 does not occur while the roller 22
revolves from the vane 23 to the second suction port 27b.
Accordingly, a region V becomes a vacuum state. The vacuum region V
causes a power loss of the driving shaft 13 and a loud noise.
Accordingly, in order to overcome the problem in the vacuum region
V, a third suction port 27c is provided at the lower bearing 25.
The third suction port 27c is formed between the second suction
port 27b and the vane 23, supplying fluid to the space between the
roller 22 and the vane 23 so as not to form the vacuum state before
the roller 22 passes through the second suction port 27b.
Preferably, the third suction port 27c is formed in the vicinity of
the vane 23 so as to remove quickly the vacuum state. However, the
third suction port 27c is positioned to face the first suction port
27a since the third suction port 27c operates at a different
rotation direction from the first suction port 27a. In reality, the
third suction port 27c is positioned spaced by an angle (.theta.3)
of approximately 10.degree. from the vane 23 clockwise or
counterclockwise. In addition, as shown in FIGS. 5A and 5B, the
third suction port 27c can be circular shapes or curved rectangular
shapes.
[0109] Since such a third suction port 27c operates along with the
second suction port 27b, the suction ports 27b and 27c should be
simultaneously opened while the roller 22 revolves in any one of
the clockwise and counterclockwise directions. Accordingly, the
first valve 110 further includes a third opening configured to
communicate with the third suction port 27c at the same time when
the second suction port 27b is opened. According to the present
invention, the third opening 113 can be formed independently.
However, since the first and third suction ports 27a and 27c are
adjacent to each other, it is desirable to open both the first and
third suction ports 27a and 27c according to the rotation direction
of the first opening 111 by increasing the rotation angle of the
first valve 110.
[0110] The first valve 110 may open the suction ports 27a, 27b and
27c according to the rotation direction of the roller 22, but the
corresponding suction ports should be opened accurately in order to
obtain desired compression capacity. The accurate opening of the
suction ports can be achieved by controlling the rotation angle of
the first valve. Thus, it is preferable that the valve assembly 100
further includes means for controlling the rotation angle of the
first valve 110, which will be described in detail with reference
to FIGS. 12A and 12B. FIGS. 12A and 12B illustrate the valve
assembly connected with the second bearing 25 in order to clearly
explain the control means.
[0111] The control means can be provided with a projection 115
formed on the first valve 110 and projecting in a radial direction
of the first valve, and a groove 123 formed on the second valve 220
and receiving the projection movably. Here, the groove 123 is
formed on the second valve 220 so as not to be exposed to the inner
volume of the cylinder 21. Therefore, a dead volume is not formed
inside the cylinder. In addition, although not shown, the control
means can be provided with a projection formed on the second valve
120 and projecting in a radial direction of the second valve 120,
and a groove formed on the first valve 110 and receiving the
projection 124 movably.
[0112] In the case of using such a control means, as shown in FIG.
12A, the projections 115 and 124 are latched to one end of each
groove 123 and 116 if the driving shaft 13 rotates
counterclockwise. Accordingly, the first opening 111 communicates
with the first suction port 27a so as to allow the suction of
fluid, and the second and third suction ports 27b and 27c are
closed. On the contrary, as shown in FIG. 12, if the driving shaft
13 rotates clockwise, the projections 115 and 124 are latched to
the other end of each groove 123 and 116, and the first and second
openings 111 and 112 simultaneously open the third and second
suction ports 27c and 27b so as to allow the suction of fluid. The
first suction port 27a is closed by the first valve 110.
[0113] Hereinafter, an operation of a rotary compressor according
to the present invention will be described in more detail.
[0114] FIGS. 13A to 13C are cross-sectional views illustrating an
operation of the rotary compressor when the roller revolves in the
counterclockwise direction.
[0115] First, in FIG. 13A, there are shown states of respective
elements inside the cylinder when the driving shaft 13 rotates in
the counterclockwise direction. First, the first suction port 27a
communicates with the first opening 111, and the remainder second
suction port 27b and third suction port 27c are closed. Detailed
description on the state of the suction ports in the
counterclockwise direction will be omitted since it has been
described above.
[0116] In a state that the first suction port 27a is opened, the
roller 22 revolves counterclockwise with performing a rolling
motion along the inner circumference of the cylinder due to the
rotation of the driving shaft 13. As the roller 22 continues to
revolve, the size of the space 29b is reduced and the fluid that
has been sucked is compressed. In this stroke, the vane 23 moves up
and down elastically by the elastic member 23a to thereby partition
the fluid chamber 29 into the two sealed spaces 29a and 29b. At the
same time, new fluid is continuously sucked into the space 29a
through the first suction port 27 so as to be compressed in a next
cycle.
[0117] When the fluid pressure in the space 29b is above a
predetermined value, the second discharge valve 26d is opened.
Accordingly, the fluid in the space 29b is discharged through the
second discharge port 26b. As the roller 22 continues to revolve,
all the fluid in the space 29b is discharged through the second
discharge port 26b. After the fluid is completely discharged, the
second discharge valve 26d closes the second discharge port 26c by
its self-elasticity.
[0118] Thus, after a single cycle is ended, the roller 22 continues
to revolve counterclockwise and discharges the fluid by repeating
the same cycle. In the counterclockwise cycle, the roller 22
compresses the fluid with revolving from the first suction port 27a
to the second discharge port 26b. As aforementioned, since the
first suction port 27a and the second discharge port 27b are
positioned in the vicinity of the vane 23 to face each other, the
fluid is compressed using the overall volume of the fluid chamber
29 in the counterclockwise cycle, so that a maximal compression
capacity is obtained.
[0119] FIGS. 14A to 14C are cross-sectional views an operation
sequence of a rotary compressor according to the present invention
when the roller revolves clockwise.
[0120] First, in FIG. 14A, there are shown states of respective
elements inside the cylinder when the driving shaft 13 rotates in
the clockwise direction. The first suction port 27a is closed, and
the second suction port 27b and third suction port 27c communicate
with the second opening 112 and the first opening 111 respectively.
If the first valve 110 has the third opening 113 additionally, the
third suction port 27c communicates with the third opening 113.
Detailed description on the state of the suction ports in the
clockwise direction will be omitted since it has been described
above.
[0121] In a state that the second and third suction ports 27b and
27c are opened, the roller 22 begins to revolve clockwise with
performing a rolling motion along the inner circumference of the
cylinder due to the clockwise rotation of the driving shaft 13. In
such an initial stage revolution, the fluid sucked until the roller
22 reaches the second suction port 27b is not compressed but is
forcibly exhausted outside the cylinder 21 by the roller 22 through
the second suction port 27b as shown in FIG. 14A. Accordingly, the
fluid begins to be compressed after the roller 22 passes the second
suction port 27b as shown in FIG. 14B. At the same time, a space
between the second suction port 27b and the vane 23, i.e., the
space 29b is made in a vacuum state. However, as aforementioned, as
the revolution of the roller 22 starts, the third suction port 27c
communicates with the first opening 111 and thus is opened so as to
suck the fluid. Accordingly, the vacuum state of the space 29b is
removed by the sucked fluid, so that generation of a noise and
power loss are constrained.
[0122] As the roller 22 continues to revolve, the size of the space
29a is reduced and the fluid that has been sucked is compressed. In
this compression stroke, the vane 23 moves up and down elastically
by the elastic member 23a to thereby partition the fluid chamber 29
into the two sealed spaces 29a and 29b. Also, new fluid is
continuously sucked into the space 29b through the second and third
suction ports 27b and 27c so as to be compressed in a next
stroke.
[0123] When the fluid pressure in the space 29a is above a
predetermined value, the first discharge valve 26c shown in FIG. 15
is opened and accordingly the fluid is discharged through the first
discharge port 26a. After the fluid is completely discharged, the
first discharge valve 26c closes the first discharge port 26a by
its self-elasticity.
[0124] Thus, after a single stroke is ended, the roller 22
continues to revolve clockwise and discharges the fluid by
repeating the same stroke. In the counterclockwise stroke, the
roller 22 compresses the fluid with revolving from the second
suction port 27b to the first discharge port 26a. Accordingly, the
fluid is compressed using a part of the overall fluid chamber 29 in
the counterclockwise stroke, so that a compression capacity smaller
than the compression capacity in the clockwise direction.
[0125] In the aforementioned strokes (i.e., the clockwise stroke
and the counterclockwise stroke), the discharged compressed fluid
moves upward through the space between the rotator 12 and the
stator 11 inside the case 1 and the space between the stator 11 and
the case 1. As a result, the compressed fluid is discharged through
the discharge tube 9 out of the compressor.
[0126] Hereinafter, a method for controlling the compressor of the
cooling system constructed as above will be described in detail
with reference to the accompanying drawings. FIG. 15 is a flowchart
illustrating a method for controlling the compressor of the cooling
system according to an embodiment of the present invention. In this
embodiment, the control unit receives information on the
temperature change of the room from the temperature sensor
installed in the room and controls the compressor. Of course, the
motor installed in the compressor has different torque
characteristics depending on rotation directions of the driving
shaft. In the following description, a phrase "to operate with the
first torque" means that the compressor is driven with a large
torque and also generates a large output (or a large cooling
force), and a phrase "to operate with the second torque" means that
the compressor is driven a small torque and generates a small
output (or, a small cooling force).
[0127] Referring to FIG. 15, the compressor starts to operate with
the first torque characteristic at an initial start step. In the
embodiment of FIG. 2, at the initial start stage, if the control
unit 610 receives the information on the temperature of the room
from the temperature sensor 660 installed in the room and
determines to operate the cooling system, the control unit 610
transmits the control signal to the switching part 650 to thereby
close the contact point of the switching part 650. The power is
supplied to the motor, and the driving shaft 13 operates with the
first torque. Of course, the switching part 650 is closed in a
state that the common contact point 621 of the selector 620 is
connected to the first contact point 623. Like the above, there are
two methods for connecting the common contact point 621 of the
selector 620 to the first contact point 623 before the motor is
driven. One method is that the control unit 610 receiving the
information from the temperature sensor 660 controls the selector
620 before the contact point of the switching part 650 is closed.
The other method is that the common contact point 621 of the
selector 620 is designed to always maintain the connection state
with the first contact point 623 at the initial start stage. Of
course, in the latter case, if the motor is opened in a state that
the connection states of the contact points of the selector 620 are
changed, it can be configured to maintain the connection states as
they are. The reason why the compressor operates with the first
driving torque at the initial start stage is that the compressor is
in a relatively high load because a compressor of a refrigerant
line becomes high due to a high temperature of the object to be
cooled, i.e., the food containing chamber of the refrigerator or
the indoor space, and a high temperature of the refrigerant of the
cooling system at the initial start stage. It is desirable that the
compressor is driven with a very high torque characteristic, i.e.,
the first torque, at the initial start stage when the compressor is
in the high load state. At this time, if the compressor is driven
with the second torque smaller than the first torque, the start
operation fails, or a cooling force of the refrigerant becomes
insufficient even if it operates for a long time, so that the
object is not cooled well.
[0128] After the initial start with the first torque, as shown in
FIG. 15, the driving mode of the motor is checked. Of course, it is
checked that the compressor is operated with the first torque mode
at the initial start stage. The driving mode determining step,
which will be described later, is carried out in order to determine
if the driving mode of the compressor is changed in operation, at
which mode the compressor operates when the compressor starts to
operate after it stops, and by which operation method the
compressor operates according to the state of the room.
[0129] As the determination result of the driving mode, if the
compressor is driven with the first torque characteristic, it is
checked whether a first condition is met while the compressor
operates. If the first condition is met, the compressor is stopped.
Here, when checking whether the first condition is met or not, as
shown in FIG. 15, it is desirable to compute an absolute value (P)
of an average temperature variation rate of the room for a
predetermined time. The reason is that the absolute value (P) is
used as the basis of determining whether or not the driving mode of
the compressor is changed. Of course, if using other factors, for
example, elapse of time, to determine the driving mode of the
compressor, it is unnecessary to compute the absolute value (P).
Meanwhile, in this embodiment, the first condition is whether the
temperature of the object, i.e., the temperature (t) of the room is
below a lower limit (t-) of the set temperature. Here, if the
temperature (t) is greater than the lower limit (t-) of the set
temperature, as shown in FIG. 15, the absolute value (P) is
continuously computed. If the temperature (t) is less than the
lower limit (t-) of the set temperature, the compressor is stopped.
In the embodiment of FIG. 2, if the temperature of the room
provided from the temperature sensor 660 is less than the lower
limit (t-) of the set temperature while the control unit 610
continues to compute the absolute value (P), the control unit 610
transmits the control signal to the switching part 650 to stop the
motor.
[0130] It is determined whether it is adaptable to continue to
operate the compressor with the first torque characteristic in a
state that the compressor is stopped. As the determination result,
if adaptable, the driving torque characteristic of the motor is
maintained, and if not adaptable, the driving torque characteristic
is changed into the second torque characteristic. If satisfying the
second condition, the compressor is again driven. Detailed
description on that will be made with reference to FIG. 2.
[0131] First, the control unit 610 determines the torque
characteristic change condition of the motor in a state that the
compressor is stopped. In this embodiment, the torque
characteristic change condition of the motor, as shown in FIG. 15,
is whether the absolute value (P) is greater than a critical value
(P+) of the temperature variation rate absolute value for the
torque characteristic change. In other words, if the computed
absolute value (P) is greater than the critical value (P+), the
control unit 610 transmits the control signal to the selector 620
to connect the common contact point 621 with the second contact
point 623, so that the driving torque characteristic of the motor
changes from the first torque characteristic to the second torque
characteristic. Here, that the absolute value (P) is greater than
the critical value (P+) means that it is unnecessary to drive the
motor with stronger cooling force since the temperature variation
rate of the room is high, that is, the temperature is dropped much
more while the compressor operates. Accordingly, in this case, it
is necessary to stop the first driving torque mode operation having
much energy consumption and operate the compressor at the second
driving torque mode. For this reason, the control unit 610 controls
the selector 620 to change the driving torque characteristic.
Meanwhile, if the torque characteristic change condition is not
met, the temperature variation rate of the room is small. In other
words, it means that a drop in the temperature of the room is
small. Therefore, in this case, the room should continue to be
cooled with a strong cooling force. Accordingly, the first torque
characteristic is maintained as it is without changing the driving
torque characteristic.
[0132] The driving mode is changed after determining the driving
torque change characteristic, and then it is determined whether or
not the second condition is met. Here, the second condition is
whether the temperature of the object to be cooled, i.e., the
temperature (t) of the room is greater than the upper limit (t+) of
the set temperature of the room. In other words, the cooling system
does not operate for a predetermined time since the compressor is
in the stopped state. Accordingly, with the passage of time, the
temperature of the room is gradually increasing. If the temperature
(t) of the room exceeds the upper limit (t+) of the set
temperature, the control unit 610 transmits the control signal to
the switching part 650 to close the contact point, thereby driving
the motor. In this case, although the torque is small, the motor is
driven at the second driving torque having a high energy
efficiency. At this time, the motor can be driven at the second
driving torque since the temperature of the room is dropped much
more and the compressor is burdened with a load having allowable
range within which the compressor can be driven at the second
driving torque. When the motor is driven at the second driving
torque, an energy efficiency of the cooling system is improved.
Meanwhile, even if the toque characteristic is maintained since the
driving torque change condition is not met, the temperature of the
room is checked to drive the compressor in the same manner. If the
temperature (t) of the room is less than the upper limit (t+) of
the set temperature, it continues to check the temperature.
[0133] If the compressor operates after the above procedures are
completed, as shown in FIG. 15, the driving mode of the compressor
is again determined. In this case, the driving mode of the
compressor can be determined with two cases. One case is to change
the driving mode when the temperature of the room is dropped much
while the above procedures are executed, and the other case is to
maintain the driving mode since the temperature of the room is
dropped less. After the driving mode is maintained, the compressor
is driven, the driving mode of the compressor is determined, and
then the above procedures are repeated. Another method for
controlling the compressor after determining the driving mode of
the compressor will be described below.
[0134] Referring to FIG. 15, if it is determined that the motor is
driven at the second torque characteristic, the control unit 610
determines whether it is adaptable to operate the motor at the
second torque characteristic on the basis of the state of the
object to be cooled, i.e., the temperature of the room and the
absolute value of the variation rate. Then, the compressor is
stopped. A description on that will be described with reference to
FIG. 2.
[0135] First, the control unit 610 receives the temperature of the
room from the temperature sensor 660 in real time, and computes the
absolute value (P) of the average temperature variation rate for a
predetermined time while the compressor is operating. It is
determined whether the absolute value (P) is less than an absolute
value (P-) of the minimum temperature variation rate.
[0136] Here, if the absolute value (P) is less than the absolute
value (P+), the control unit 610 transmits the control signal to
the switching part 650 to open the contact points of the switching
part 650, thereby stopping the motor. That the absolute value (P)
is less than the absolute value (P+) means that the temperature of
the room is not dropped as much as the minimum necessary level due
to the lack of the cooling force although the cooling system
operates at the second torque for a predetermined time. In this
case, if the cooling system operates at the second torque,
necessary cooling force is not supplied to the room, so that the
room is not cooled effectively. Accordingly, if it is determined
that the absolute value (P) is the absolute value (P+), it is not
suitable to operate the motor at the second torque characteristic.
Therefore, the driving torque characteristic is changed into the
first torque characteristic in order to cool the room at larger
cooling force. In this case, as shown in FIG. 15, the control unit
610 controls the switching part 650 to stop the compressor.
[0137] If the compressor is stopped, the control unit 610 transmits
the control signal to the selector 620 after a delay of
predetermined time, so that the common contact point 621 and the
first contact point 623 are connected to each other. As a result,
the driving torque characteristic of the motor is changed into the
first torque characteristic. If the torque characteristic change of
the motor is completed, the control unit 610 transmits the control
signal to the switching part 650 to close the contact points of the
switching part 650, thereby driving the motor. The compressor is
driven at the first driving torque, so that the room is cooled at a
large cooling force. If the compressor is driven at the first
driving torque, as shown in FIG. 15, it is again determined at
which driving mode the compressor is operating.
[0138] Meanwhile, if the absolute value (P) is greater than the
absolute value (P+), the control unit 610 determines whether it is
suitable to operate the motor at the second torque characteristic
on the basis of the temperature information provided from the
temperature sensor 660. The determination condition, as shown in
FIG. 15, is that it is whether the temperature of the object to be
cooled, i.e., the temperature (t) of the room, is less than the
lower limit (t-) of the set temperature. If the temperature (t) of
the room is less than the lower limit (t-) of the set temperature,
the control unit 610 determines whether it is suitable to operate
the motor at the second torque characteristic, and then transmits
the control signal to the switching part 650 to stop the motor.
Here, that the temperature (t) of the room is less than the lower
limit (t-) of the set temperature means that a large cooling force
is not necessary since the temperature (t) is sufficiently low
although the temperature variation rate of the room is very small,
and that the cooling system can continue to operate at a small
cooling force. Accordingly, in this case, the motor is stopped in a
state that the driving characteristic of the motor is maintained.
Meanwhile, if the temperature (t) of the room is greater than the
lower limit (t-) of the set temperature, the control unit 610
continues to compute the absolute value (P), compares the two
absolute values (P)(P+), and repeats the above procedures according
to the comparison result.
[0139] After stopping the compressor since the temperature (t) of
the room is less than the lower limit (t-) of the set temperature,
as shown in FIG. 15, it is determined whether the temperature of
the object to be cooled, i.e., the temperature (t) of the room
satisfies the upper limit (t+) of the set temperature. If the
temperature (t) satisfies the upper limit (t+) of the set
temperature, the motor is driven, and the process proceeds to the
step of determining the driving mode.
[0140] In the method for controlling the compressor according to
the present invention, the control unit controls the compressor to
check the temperature variation of the room in real time and output
the torques necessary for the cooling force of the room and the
driving of the compressor on the basis of the checked temperature
variation, thereby always obtaining the optimum operation of the
compressor.
[0141] FIG. 16 is a flowchart illustrating a method for controlling
the compressor in the cooling system according to another
embodiment of the present invention. In this embodiment, the
control unit controls the compressor on the basis of the driving of
the motor and the elapse degree of time. This embodiment of the
present invention will be described in detail with reference to
FIG. 3. The same contents as the embodiment of FIG. 15 will be
omitted.
[0142] Referring to FIG. 16, the compressor starts to operate at
the first torque at the initial start stage. Referring again to
FIG. 3, the motor is automatically driven by the switching part 670
for tuning on/off the contact points according to the temperature
of the room. In other words, the switching part 670 including the
thermostat operated by the bimetal is configured to close the
contact points above the first temperature and open them below the
second temperature. If the temperature of the room increases above
the first temperature, the contact points of the switching part 670
are closed so that the compressor operates. After the compress is
initially operated, the process proceeds to the step of determining
the driving mode.
[0143] As the determination result of the driving mode, if the
compressor operates at the first torque characteristic, it is
determined whether the compressor satisfies the first condition
while it is operating. At this time, if the first condition is met,
the compressor is stopped. In this embodiment, the first condition
is whether the compressor is stopped or not. Referring to FIG. 3,
the compressor is automatically turned on or off by the switching
part 670 which is turned on/off according to the temperature of the
room. Accordingly, if the compressor operates for a long time so
that the temperature of the room is dropped below the second
temperature, the contact points of the switching part 670 are
opened to stop the compressor. The current sensor 690 connected in
series to the switching part 670 checks the stopping of the
compressor and informs the control unit 610 of it. In other words,
if the current is not sensed by the current sensor 690, the control
unit 610 determines that the motor is stopped.
[0144] Meanwhile, in order to determine the driving mode change
condition, which will be described later, the elapse time (T) is
counted while the compressor is operating. If the compressor is not
stopped, the elapse time (T) continues to be counted. Of course, if
the compressor is stopped, the counting of the elapse time (T) is
stopped.
[0145] If it is determined that the compressor is stopped, it is
determined whether it is suitable to continue to operate the
compressor at the first torque characteristic in a state that the
compressor is stopped. If suitable, the driving torque
characteristic is maintained, and if not suitable, the driving
characteristic is changed into the second torque characteristic.
After maintaining or changing the driving torque characteristic of
the motor, it is determined whether the second condition is met. If
met, the compressor is operated. Detailed description on that will
be made in detail with reference to FIG. 2.
[0146] First, the control unit 610 determines the condition for
changing the torque characteristic of the motor in a stat that the
compressor is stopped. Here, the torque characteristic change
condition is whether or not the elapse time (T) is less than the
preset minimum time (T-). In other words, if the elapse time (T) is
less than the minimum time (T-), the control unit 610 determines
that it is not suitable to drive the compressor at the first
driving mode. That the elapse time (T) is less than the minimum
time (T-) means that the temperature of the room is dropped to
desired temperature within a very short time due to the sufficiency
of the cooling force or the low temperature of the room. Therefore,
it is unnecessary to drive the compressor at large cooling force.
At this time, it is necessary to efficiently drive the system by
reducing the energy consumption through the change of the torque
characteristic. On the contrary, if the elapse time (T) exceeds the
minimum time (T-), the control unit 610 determines that it is
suitable to drive the compressor at the first driving mode, and
thus maintains the driving torque characteristic. In this
embodiment, the minimum time (T-) can be set to about 10
minutes.
[0147] If the elapse time (T) is less than the minimum time (T-),
the control unit 610 transmits the control signal to the selector
620 to connect the common contact point 621 with the second contact
point 622, thereby changing the driving torque characteristic of
the motor into the second torque characteristic. After changing the
driving torque characteristic of the motor, the control unit 610
resets the elapse time (T). On the contrary, if the elapse time is
less than the minimum time (T-), the control unit 610 resets the
elapse time (I) in a state that the driving torque characteristic
is maintained as it is, as shown in FIG. 16.
[0148] After resetting the elapse time (T), the control unit 610
determines the second condition, i.e., whether the compressor is
driven or not. Of course, the current sensor 690 is used to
determine the second condition. If it is determined that the
compressor is driven, as shown in FIG. 15, the process proceeds to
the step of determining the driving mode of the motor. On the other
hand, if it is determined that the compressor is not driven, the
control unit 610 continues to determine the second condition.
[0149] Meanwhile, like the embodiment of FIG. 15, two results are
provided at the step of determining the driving mode of the
compressor after the above procedures. If it is determined that the
compressor is driven at the first torque, the above procedures are
repeatedly carried out, and if it is determined that the motor is
driven at the second torque, the compressor operates in a different
method. The case that the motor is driven at the second torque will
be described below.
[0150] First, if it is determined that the motor is driven at the
second torque characteristic, it is determined whether it is
suitable to operate the motor at the second torque characteristic
on the basis of the elapse time. Here, the determination is carried
out by comparing the elapse time while the compressor operates and
the preset time. After completing the determination, the compressor
is stopped, which will be described in detail with reference to
FIG. 3.
[0151] The control unit 610 counts the elapse time (T) while the
compressor is driven as shown in FIG. 16. Then, the control unit
610 determines the driving torque change condition of the
compressor. Here, the driving torque change condition is provided
with two cases. One case is whether the elapse time (T) exceeds the
maximum limit time (T+), and the other case is whether the elapse
time (T) is less than a start success determining time (Tt) of the
compressor. In this embodiment, the maximum limit time (T+) can be
set to about 30 minutes, and the start success determining time
(Ty) can be set to about 10 minutes. If one of two conditions is
met, the control unit 610 determines that it is not suitable to
operate the compressor at the second torque characteristic. The
reasons are as follows.
[0152] First, that the elapse time (T) exceeds the maximum limit
time (T+) means that the compressor operates at the second torque
characteristic unnecessarily for a long time. Due to an
insufficiency of the cooling force of the cooling system or the
high temperature of the surroundings or the room, the compressor
operates at the second torque characteristic for a long time.
Therefore, the temperature is dropped enough to open the switching
part 670 installed in the room. In this case, since it is more
effective to drive the cooling system at large cooling force, it is
determined that it is not suitable to operate the compressor at the
second torque characteristic
[0153] If the elapse time (T) is less than the start success
determining time (Tt), the compressor does not operate normally. In
addition, it means that the compressor is stopped just after the
compressor is driven at the second torque characteristic. In other
words, when the compressor operates at the second torque
characteristic, if the torque outputted at the second torque start
is smaller than the torque necessary for the driving, the motor is
overloaded. Therefore, the motor is automatically stopped by, for
example, the overload protector 640. In this case, since it means
that the torque of the driving shaft 13 is weak when driving the
motor at the second torque characteristic, the motor should be
driven at larger torque.
[0154] As described above, if it is determined that it is not
suitable to drive the motor at the second torque characteristic,
the control unit 610 transmits the control signal to the second
switching part 680 to open the contact points, thereby forcibly
stopping the motor. After the compressor is stopped, as shown in
FIG. 16, the control unit 610 delays a predetermined time and
controls the selector 620 to change the driving torque
characteristic of the compressor into the first torque
characteristic. After changing the torque characteristic, the
elapse time (T) is reset. The control unit 610 controls the second
switching part 680 to drive the compressor, and then the process
proceeds to the step of determining the mode.
[0155] Meanwhile, if the compressor operating at the second torque
does not satisfies the torque change condition, in other words, if
the elapse time exceeds the start success determining time (Tt) and
is less than the maximum limit time (T+), the control unit 610
determines that it is suitable to drive the compressor at the
second torque. This means that the start at the second torque is
succeeded and the temperature of the room is dropped below the
second temperature. After such a determination, the current sensor
690 senses whether or not the compressor is turned on. At this
time, if the compressor is operating, the torque change condition
is again determined while checking the elapse time (T), and then a
corresponding process is carried out.
[0156] If it is determined that the compressor is stopped, it means
that the driving at the second torque is succeeded and the
temperature of the room is dropped to a desired target temperature,
i.e., the second temperature, while the compressor operates at the
second torque. After the compressor is stopped, the control unit
610 resets the elapse time (T). In addition, since the cooling
system does not operate after the compressor is stopped, the
temperature of the room increases gradually. If the temperature of
the room is above the first temperature, the switching part 670 is
automatically closed and the motor rotates, thereby driving the
compressor. If the temperature is less than the first temperature,
the switching part 670 maintains the opened state and thus the
compressor maintains the stopped state. Meanwhile, as shown in FIG.
16, after the compressor is driven, the process proceeds to the
step of determining the driving mode of the compressor.
[0157] According to the system for controlling the cooling system,
the compressor is controlled by automatically turning on/off the
motor according to the temperature of the room on the basis of the
time elapse. Therefore, it is possible to provide the torque and
the cooling force which is sensitive to the temperature condition
of the room and suitable for the condition of the room.
[0158] It will be apparent to those skilled in the art that various
modifications and variations can be made in the present invention.
Thus, it is intended that the present invention covers the
modifications and variations of this invention provided they come
within the scope of the appended claims and their equivalents.
[0159] For example, the method for controlling the compressor of
the cooling system according to the present invention is not
limited to only the above-described compressors. In other words,
the present invention can be applied to any compressor used in the
cooling system and having the motor that outputs two different
torques. However, unlike the compressors of the present invention,
these compressors has a disadvantage that they cannot provide the
two different torques and two different capacities or cooling
forces at the same time. In this case, if the method of the present
invention is applied to the compressors, the compressors can output
torque suitable for the state of the object to be cooled, thereby
obtaining an improved energy efficiency. Meanwhile, the present
invention provides a method for controlling the compressors that
can output two different torques and dual capacity.
INDUSTRIAL APPLICABILITY
[0160] The rotary compressor constructed as above has following
effects.
[0161] First, according to the related art, several devices are
combined in order to achieve the dual-capacity compression. For
example, an inverter and two compressors having different
compression capacities are combined in order to obtain the dual
compression capacities. In this case, the structure becomes
complicated and the cost increases. However, according to the
present invention, the dual-capacity compression can be achieved
using only one compressor. Particularly, the present invention can
achieve the dual-capacity compression by changing parts of the
conventional rotary compressor to the minimum.
[0162] Second, the conventional compressor having a single
compression capacity cannot provide the compression capacity that
is adaptable for various operation conditions of air conditioner or
refrigerator. In this case, a power consumption may be wasted
unnecessarily. However, the present invention can provide a
compression capacity that is adaptable for the operation conditions
of equipments.
[0163] Third, according to the rotary compressor of the present
invention, the conventional designed fluid chamber can be used to
provide the dual-compression capacity. It means that the compressor
of the present invention has at least the same compression capacity
as the conventional rotary compressor having the same cylinder and
fluid chamber in size. In other words, the rotary compressor of the
present invention can substitute for the conventional rotary
compressor without modifying designs of basic parts, such as a size
of the cylinder. Accordingly, the rotary compressor of the present
invention can be freely applied to required systems without any
consideration of the compression capacity and any increase in unit
cost of production.
[0164] Fourth, according to the method for controlling the
compressor of the present invention, all the compressors which can
output different torques as well as the double-capacity compressors
can operate at the optimum torque according to the conditions of
the objects to be cooled. Therefore, the cooling system can be
operated more economically and efficiently compared with the
related art.
* * * * *