U.S. patent application number 13/057335 was filed with the patent office on 2011-06-09 for linear compressor.
Invention is credited to Yang-Hoon Jung, Hee-Dong Kang, Kye-Lyong Kang, Hyun Kim, Jong-Kwon Kim, Jeong-Uk Lee, Shin-Hyun Park.
Application Number | 20110135518 13/057335 |
Document ID | / |
Family ID | 41663861 |
Filed Date | 2011-06-09 |
United States Patent
Application |
20110135518 |
Kind Code |
A1 |
Kang; Kye-Lyong ; et
al. |
June 9, 2011 |
LINEAR COMPRESSOR
Abstract
The present invention relates to a linear compressor, and more
particularly to, a linear compressor which employs a conductor
member in a linear motor instead of a magnet to produce a driving
force by electromagnetic induction. The linear compressor of the
present invention includes a fixed member provided with a
compression space, a movable member which linearly reciprocates
inside the fixed member to compress refrigerant, one or more
springs installed to elastically support the movable member in a
motion direction, a stator composed of a first stator supplied with
a current, and a second stator spaced apart from the first stator
at a certain interval, a conductor member electromagnetically
induced by a magnetic field produced by the stator to make the
movable member linearly reciprocate, and a control unit which
controls supply of the current with respect to the first
stator.
Inventors: |
Kang; Kye-Lyong;
(Gyeongsangnam-do, KR) ; Kim; Jong-Kwon;
(Changwon-shi, KR) ; Park; Shin-Hyun; (Pusan,
KR) ; Kim; Hyun; (Changwon-shi, KR) ; Kang;
Hee-Dong; (Changwon-shi, KR) ; Lee; Jeong-Uk;
(Jeonju-shi, KR) ; Jung; Yang-Hoon; (Changwon-shi,
KR) |
Family ID: |
41663861 |
Appl. No.: |
13/057335 |
Filed: |
August 5, 2009 |
PCT Filed: |
August 5, 2009 |
PCT NO: |
PCT/KR09/04366 |
371 Date: |
February 3, 2011 |
Current U.S.
Class: |
417/417 |
Current CPC
Class: |
H02K 33/16 20130101;
F04B 35/045 20130101 |
Class at
Publication: |
417/417 |
International
Class: |
F04B 17/04 20060101
F04B017/04 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 7, 2008 |
KR |
10-2008-0077607 |
Claims
1. A linear compressor, comprising: a fixed member provided with a
compression space; a movable member which linearly reciprocates
inside the fixed member to compress refrigerant; one or more
springs installed to elastically support the movable member in a
motion direction; a stator composed of a first stator supplied with
a current, and a second stator spaced apart from the first stator
at a certain interval; a conductor member electromagnetically
induced by a magnetic field produced by the stator to make the
movable member linearly reciprocate; and a control unit which
controls supply of the current with respect to the first
stator.
2. The linear compressor of claim 1, further comprising a
connection member which connects the movable member to the
conductor member, wherein the conductor member is a conductor
mounted on one end of the connection member.
3. The linear compressor of claim 1, further comprising a
connection member which connects the movable member to the
conductor member, wherein the conductor member is formed by
alternately stacking an annular iron piece and conductor, and
mounted on one end of the connection member.
4. The linear compressor of claim 1, further comprising a
connection member which connects the movable member to the
conductor member, wherein the conductor member is a conductor line
wound around one end of the connection member.
5. The linear compressor of claim 1, wherein the first stator
comprises a coil winding body wound with a coil, and a core mounted
on the coil winding body, and the control unit controls On and Off
of current supply with respect to the coil winding body so as to
produce a one-way magnetic field in the conductor member.
6. The linear compressor of claim 5, wherein the springs comprise
one or more of a first spring installed to elastically support the
movable member in a refrigerant compression direction, and a second
spring installed to elastically support the movable member in the
opposite direction to the refrigerant compression direction.
7. The linear compressor of claim 1, wherein at least some portion
of the conductor member is positioned between the first stator and
the second stator.
8. The linear compressor of claim 7, wherein the first stator
comprises first and second coil winding bodies spaced apart at an
interval in an axial direction and wound with a coil, respectively,
and a core mounted on the first and second coil winding bodies, and
the control unit performs a control to supply currents having a
phase difference to the first and second coil winding bodies to
produce a two-way magnetic field in the conductor member.
9. The linear compressor of claim 8, wherein the coil is wound
around the first and second coil winding bodies in the same
direction, and a capacitor is connected in series to one of the
first and second coil winding bodies.
10. The linear compressor of claim 8, wherein the control unit
performs a control to supply currents having a phase difference of
90.degree. to the first and second coil winding bodies.
11. The linear compressor of claim 8, wherein the springs comprise
a first spring installed to elastically support the movable member
in a refrigerant compression direction, and a second spring
installed to elastically support the movable member in the opposite
direction to the refrigerant compression direction.
12. The linear compressor of claim 1, wherein, when the movable
member operates over a certain speed, a speed of the movable member
and a force moving the movable member are inversely proportional at
different ratios according to an amplitude of a load.
13. The linear compressor of claim 12, wherein the control unit
varies an amplitude of a voltage applied to the first stator
according to the amplitude of the load.
14. The linear compressor of claim 13, wherein the control unit
varies the amplitude of the voltage so that the speed reduction of
the movable member can be relatively small or the force moving the
movable member can be substantially maintained or increase with the
increase of the load.
15. The linear compressor of claim 12, wherein the control unit
varies a frequency according to the amplitude of the load.
16. The linear compressor of claim 15, wherein the control unit
varies the frequency so that the speed of the movable member can
increase or the force moving the movable member can be
substantially maintained or increase with the increase of the
load.
17. A linear compressor, comprising: a fixed member provided with a
compression space; a movable member which is provided with a
conductor member, and linearly reciprocates inside the fixed member
to compress refrigerant; a plurality of springs installed to
elastically support the movable member in a motion direction; a
first stator applied with a current to magnetically induce the
conductor member; a second stator positioned corresponding to the
first stator so that at least some portion of the conductor member
can be positioned in a space between the first stator and the
second stator; and a control unit which varies one or more of an
amplitude and frequency of power applied to the first stator
according to an amplitude of a load to control a cooling capacity
according to the load.
18. The linear compressor of claim 17, wherein, when the movable
member operates over a certain speed, a speed of the movable member
and a force moving the movable member are inversely proportional at
different ratios.
19. The linear compressor of claim 18, wherein the control unit
varies the amplitude of the voltage so that the speed reduction of
the movable member can be relatively small or the force moving the
movable member can be substantially maintained or increase with the
increase of the load.
20. The linear compressor of claim 18, wherein the control unit
varies the frequency so that the speed of the movable member can
increase or the force moving the movable member can be
substantially maintained or increase with the increase of the load.
Description
TECHNICAL FIELD
[0001] The present invention relates to a linear compressor, and
more particularly to, a linear compressor which employs a conductor
member in a linear motor instead of a magnet to produce a driving
force by electromagnetic induction.
BACKGROUND ART
[0002] In general, a compressor is a mechanical apparatus receiving
power from a power generation apparatus such as an electric motor,
a turbine or the like, and compressing the air, refrigerant or
various operation gases to raise a pressure. The compressor has
been widely used for electric home appliances such as refrigerators
and air conditioners, and application thereof has been expanded to
the whole industry.
[0003] The compressors are roughly classified into a reciprocating
compressor, wherein a compression space to/from which an operation
gas is sucked and discharged is defined between a piston and a
cylinder, and the piston linearly reciprocates in the cylinder to
compress refrigerant, a rotary compressor, wherein a compression
space to/from which an operation gas is sucked and discharged is
defined between an eccentrically-rotating roller and a cylinder,
and the roller eccentrically rotates along an inside wall of the
cylinder to compress refrigerant, and a scroll compressor, wherein
a compression space to/from which an operation gas is sucked and
discharged is defined between an orbiting scroll and a fixed
scroll, and the orbiting scroll rotates along the fixed scroll to
compress refrigerant.
[0004] Recently, among the reciprocating compressors, a linear
compressor has been actively developed because it improves
compression efficiency and provides simple construction by removing
a mechanical loss caused by motion conversion by directly
connecting a piston to a linearly-reciprocating driving motor.
[0005] FIG. 1 is a side view illustrating a conventional linear
compressor. The conventional linear compressor is installed such
that a structure composed of a frame 2, a cylinder 3, a piston 4, a
suction valve 6, a discharge valve 7, a linear motor 10, a motor
cover 18, a supporter 19, a rear cover 20, main springs S1 and S2
and a suction muffler assembly 21 is elastically supported inside a
shell 1.
[0006] The cylinder 3 is fixedly fitted into the frame 2, the
discharge valve 7 is installed to block one end of the cylinder 3,
the piston 4 is inserted into the cylinder 3, and the thin suction
valve 6 is installed to open and close a suction hole 5 of the
piston 4.
[0007] The linear motor 10 is installed such that a gap is
maintained between an inner stator 12 and an outer stator 14 and a
magnet frame 16 can linearly reciprocate therein. The magnet frame
16 is connected to the piston 4 by a piston fixing portion 16c, and
linearly reciprocates due to a mutual electromagnetic force between
the inner stator 12 and the outer stator 14 and the magnet frame 16
to operate the piston 4.
[0008] The motor cover 18 supports the outer stator 14 in an axial
direction and is bolt-fixed to the frame 2 so as to fix the outer
stator 14, and the rear cover 20 is coupled to the motor cover 18.
The supporter 19 connected to the other end of the piston 4 is
installed between the motor cover 18 and the rear cover 20 to be
elastically supported by the main springs S1 and S2 in an axial
direction, and the suction muffler assembly 21 which allows suction
of refrigerant is also fastened with the supporter 19.
[0009] Here, the main springs S1 and S2 include four front springs
S1 and four rear springs S2 in up-down and left-right symmetric
positions around the supporter 19. When the linear motor 10
operates, the front springs S1 and the rear springs S2 move in
opposite directions to buffer the shock of the piston 4 and the
supporter 19. Moreover, refrigerant existing on the side of a
compression space P serves as a kind of gas spring to buffer the
shock of the piston 4 and the supporter 19.
[0010] Accordingly, when the linear motor 10 operates, the piston 4
and the suction muffler assembly 21 connected thereto linearly
reciprocate, and the operations of the suction valve 6 and the
discharge valve 7 are automatically controlled with variations of a
pressure of the compression space P, so that the refrigerant is
sucked into the compression space P via a suction tube (not shown),
the suction muffler assembly 21 and the suction hole 5 of the
piston 4, compressed therein, and discharged to the outside through
a discharge cap 8, a loop pipe 9 and a discharge tube (not shown)
on the shell side.
[0011] The linear motor 10 of the linear compressor includes the
inner stator 12, the outer stator 14, and the magnet frame 16
around the frame 2 as shown in FIG. 1. The inner stator 12 is
constructed such that laminations are stacked in a circumferential
direction, and the outer stator 14 is constructed such that core
blocks 14b are installed on a coil winding body 14a at certain
intervals in a circumferential direction.
[0012] FIG. 2 is a perspective view illustrating a conventional
magnet frame. The magnet frame 16 includes a cylindrical frame main
body 16a positioned between the inner stator 12 and the outer
stator 14 of the linear motor 10, magnets 16b fixed to some outer
portions of the frame main body 16a, and a piston fixing portion
16c extended to the inside so that the piston 4 can be fixed to one
end of the frame main body 16a. Holes 16d are formed on one side of
the magnets 16b.
[0013] Here, the magnets 16b are formed on the frame main body 16a
at certain intervals in a circumferential direction. Preferably,
eight magnets 16b are coupled to the outside of the frame main body
16a at regular intervals.
[0014] In the conventional linear compressor, the magnet linearly
reciprocates between the inner stator and the outer stator due to a
mutual electromagnetic force. However, it is difficult to employ a
cylindrical magnet because of a high price of the magnet. Even if
several bar-shaped magnets are fixed to form a magnet frame, the
unit costs and overall costs of production still increase.
[0015] Moreover, in the conventional linear compressor, the linear
motor varies a stroke to modulate a cooling capacity according to a
load. To this end, a complicated control unit is provided, which is
accompanied with design limitations on sizes of peripheral
components. Further, a complicated control method is required,
which increases the costs of production and complicates a
manufacturing process. Furthermore, much power is consumed for
controlling, which degrades efficiency of the whole compressor.
DISCLOSURE
Technical Problem
[0016] An object of the present invention is to provide a linear
compressor which employs a conductor member instead of a magnet to
simplify the shape and controlling of a linear motor.
[0017] Another object of the present invention is to provide a
linear compressor which can supply a necessary cooling capacity,
using a characteristic between a speed of a movable member and a
force moving the movable member according to an amplitude or
variation of a load.
[0018] A further object of the present invention is to provide a
linear compressor which adjusts a frequency or voltage amplitude of
applied power to generate a cooling capacity according to a
load.
Technical Solution
[0019] According to an aspect of the present invention, there is
provided a linear compressor, including: a fixed member provided
with a compression space; a movable member which linearly
reciprocates inside the fixed member to compress refrigerant; one
or more springs installed to elastically support the movable member
in a motion direction; a stator composed of a first stator supplied
with a current, and a second stator spaced apart from the first
stator at a certain interval; a conductor member
electromagnetically induced by a magnetic field produced by the
stator to make the movable member linearly reciprocate; and a
control unit which controls supply of the current with respect to
the first stator.
[0020] In addition, preferably, the linear compressor further
includes a connection member which connects the movable member to
the conductor member, wherein the conductor member is a conductor
mounted on one end of the connection member.
[0021] Moreover, preferably, the linear compressor further includes
a connection member which connects the movable member to the
conductor member, wherein the conductor member is formed by
alternately stacking an annular iron piece and conductor, and
mounted on one end of the connection member.
[0022] Further, preferably, the linear compressor further includes
a connection member which connects the movable member to the
conductor member, wherein the conductor member is a conductor line
wound around one end of the connection member.
[0023] Furthermore, preferably, the first stator includes a coil
winding body wound with a coil, and a core mounted on the coil
winding body, and the control unit controls On and Off of current
supply with respect to the coil winding body so as to produce a
one-way magnetic field in the conductor member.
[0024] Still furthermore, preferably, the springs include one or
more of a first spring installed to elastically support the movable
member in a refrigerant compression direction, and a second spring
installed to elastically support the movable member in the opposite
direction to the refrigerant compression direction.
[0025] Still furthermore, preferably, at least some portion of the
conductor member is positioned between the first stator and the
second stator.
[0026] Still furthermore, preferably, the first stator includes
first and second coil winding bodies spaced apart at an interval in
an axial direction and wound with a coil, respectively, and a core
mounted on the first and second coil winding bodies, and the
control unit performs a control to supply currents having a phase
difference to the first and second coil winding bodies to produce a
two-way magnetic field in the conductor member.
[0027] Still furthermore, preferably, the coil is wound around the
first and second coil winding bodies in the same direction, and a
capacitor is connected in series to one of the first and second
coil winding bodies.
[0028] Still furthermore, preferably, the control unit performs a
control to supply currents having a phase difference of 90.degree.
to the first and second coil winding bodies.
[0029] Still furthermore, preferably, the springs include a first
spring installed to elastically support the movable member in a
refrigerant compression direction, and a second spring installed to
elastically support the movable member in the opposite direction to
the refrigerant compression direction.
[0030] Still furthermore, preferably, when the movable member
operates over a certain speed, a speed of the movable member and a
force moving the movable member are inversely proportional at
different ratios according to an amplitude of a load.
[0031] Still furthermore, preferably, the control unit varies an
amplitude of a voltage applied to the first stator according to the
amplitude of the load.
[0032] Still furthermore, preferably, the control unit varies the
amplitude of the voltage so that the speed reduction of the movable
member can be relatively small or the force moving the movable
member can be substantially maintained or increase with the
increase of the load.
[0033] Still furthermore, preferably, the control unit varies a
frequency according to the amplitude of the load.
[0034] Still furthermore, preferably, the control unit varies the
frequency so that the speed of the movable member can increase or
the force moving the movable member can be substantially maintained
or increase with the increase of the load.
[0035] According to another aspect of the present invention, there
is provided a linear compressor, including: a fixed member provided
with a compression space; a movable member which is provided with a
conductor member, and linearly reciprocates inside the fixed member
to compress refrigerant; a plurality of springs installed to
elastically support the movable member in a motion direction; a
first stator applied with a current to magnetically induce the
conductor member; a second stator positioned corresponding to the
first stator so that at least some portion of the conductor member
can be positioned in a space between the first stator and the
second stator; and a control unit which varies one or more of an
amplitude and frequency of power applied to the first stator
according to an amplitude of a load to control a cooling capacity
according to the load.
Advantageous Effects
[0036] According to the present invention, since the linear motor
employs the conductor member instead of the magnet to supply a
driving force by magnetic induction, the mechanism and controlling
thereof are simplified, so that the costs of production are cut
down. Moreover, since the linear motor can be driven by minimum
elements without a special driving unit for controlling, it is
possible to improve entire efficiency.
[0037] In addition, according to the present invention, the linear
compressor varies one or more of the voltage and the frequency,
using the characteristic between the speed of the movable member
and the force moving the movable member according to variations of
the load, to thereby supply a necessary cooling capacity.
[0038] Moreover, according to the present invention, the linear
compressor adjusts the frequency or the voltage amplitude of
applied power to generate a cooling capacity according to the
load.
DESCRIPTION OF DRAWINGS
[0039] FIG. 1 is a side view illustrating a conventional linear
compressor;
[0040] FIG. 2 is a perspective view illustrating a conventional
magnet frame;
[0041] FIG. 3 is a side-sectional view illustrating a first
embodiment of a linear compressor according to the present
invention;
[0042] FIG. 4 is a side-sectional view illustrating a second
embodiment of the linear compressor according to the present
invention;
[0043] FIG. 5 is a side-sectional view illustrating a third
embodiment of the linear compressor according to the present
invention;
[0044] FIG. 6 is a perspective view illustrating a first embodiment
of a conductor member applied to the linear compressor according to
the present invention;
[0045] FIG. 7 is a perspective view illustrating a second
embodiment of the conductor member applied to the linear compressor
according to the present invention;
[0046] FIG. 8 is a perspective view illustrating a third embodiment
of the conductor member applied to the linear compressor according
to the present invention;
[0047] FIG. 9 is a graph showing magnetic flux waveforms of a
linear motor shown in FIG. 5 by an applied current;
[0048] FIG. 10 is a schematic circuit view for applying a current
to the linear motor shown in FIG. 5;
[0049] FIG. 11 is a graph showing linear reciprocation magnetic
flux operations of the linear motor shown in FIG. 5;
[0050] FIG. 12 is a graph showing the relation between a slip and a
torque of the linear motor shown in FIG. 5 in variations of a
voltage; and
[0051] FIG. 13 is a graph showing the relation between the slip and
the torque of the linear motor shown in FIG. 5 in variations of a
frequency.
MODE FOR INVENTION
[0052] Hereinafter, the present invention will be described in
detail with reference to embodiments and drawings.
[0053] FIGS. 3 to 5 are side-sectional views illustrating various
embodiments of a linear compressor according to the present
invention.
[0054] As illustrated in FIGS. 3 to 5, the linear compressor
according to the present invention is constructed such that a fixed
member 120 provided with a compression space P of refrigerant, a
movable member 130 compressing refrigerant in the fixed member 120,
and a linear motor 200 driving the movable member 130 are installed
in a hermetic container 100. The linear motor 200 includes first
and second stators 220 and 240, and a conductor member 260
positioned in a space between the first and second stators 220 and
240.
[0055] The second stator 240 is fixed to an outer circumference of
the fixed member 120, and the first stator 220 is fixed in an axial
direction by a frame 110 and a motor cover 300. Since the frame 110
and the motor cover 300 are fastened and coupled to each other by a
fastening member such as a bolt, the first stator 220 is fixed
between the frame 110 and the motor cover 300. The frame 110 may be
formed integrally with the fixed member 120, or manufactured
individually from the fixed member 120 and coupled to the fixed
member 120.
[0056] A supporter 310 is connected to the rear of the movable
member 130, and a rear cover 320 is coupled to the rear of the
motor cover 300. The supporter 310 is positioned between the motor
cover 300 and the rear cover 320. Springs S1 and S2 are installed
in an axial direction to buffer the shock of the linear
reciprocation of the movable member 130 with both ends supported by
the supporter 310 and the motor cover 300 or the supporter 310 and
the rear cover 320. Here, detailed installation positions and
elastic moduli of the springs S1 and S2 may be changed according to
the construction and operation of the linear motor 200, which will
be described below in detail.
[0057] In addition, a suction muffler 330 is provided at the rear
of the movable member 130. The refrigerant is introduced into the
movable member 130 through the suction muffler 330, thereby
reducing refrigerant suction noise.
[0058] Some portion of a front end of the movable member 130 has a
hollow so that the refrigerant introduced through the suction
muffler 330 can be introduced into and compressed in the
compression space P defined between the fixed member 120 and the
movable member 130. A suction valve (not shown) is installed at the
front end of the movable member 130. The suction valve (not shown)
opens the front end of the movable member 130 so that the
refrigerant can flow from the movable member 130 to the compression
space P, and closes the front end of the movable member 130 so that
the refrigerant cannot flow back from the compression space P to
the movable member 130.
[0059] When the refrigerant is compressed over a defined pressure
in the compression space P by the movable member 130, a discharge
valve 160 positioned at a front end of the fixed member 120 is
open. The high-pressure compressed refrigerant is discharged to a
discharge cap 170, discharged again to the outside of the linear
compressor through a loop pipe 180, and circulated in a freezing
cycle.
[0060] The linear motor 200 includes the first stator 220 through
which a current flows, the second stator 240 maintaining a gap from
the first stator 220, and the conductor member 260 installed
maintaining a gap between the first and second stators 220 and 240,
and magnetically induced by the first stator 220 to make the
movable member 130 linearly reciprocate. The linear motor 200
includes a control unit (not shown) which controls supply of a
current with respect to the first stator 220. Here, the first
stator 220 is an outer stator relatively distant from the fixed
member 120, and the second stator 240 is an inner stator mounted on
the fixed member 120.
[0061] The linear motor 200 of the linear compressor so constructed
is a linear motor 200 provided with two stators 220 and 240, but a
general linear motor 200 provided with only one current-flowing
stator 220 also belongs to the scope of the present invention. In
addition, the linear compressor may include a power unit (not
shown) which can receive power from the outside. As the power unit
is an element obvious to a person of ordinary skill in the art,
explanations thereof are omitted.
[0062] As illustrated in FIG. 3, an embodiment of the first stator
220 is constructed such that core blocks 222 are mounted on one
coil winding body 221 wound with a coil in a circumferential
direction. The control unit controls On/Off of current supply with
respect to the coil winding body 221 so as to produce a one-way
magnetic field in the conductor member 260, and produces a force so
that the conductor member 260 can move in a refrigerant compression
direction, i.e., a top dead center direction. Here, preferably,
only the front main springs S1 are installed between the motor
cover 300 and the supporter 310 to grant a restoration force
against a force applied to the movable member 130 by the linear
motor 200. In addition, preferably, the elastic modulus and number
of the front main springs S1 are determined to be proportional to
the coil winding number of the coil winding body 221.
[0063] Accordingly, when the current is input to the coil winding
body 221, a magnet flux forms a closed circuit along the first and
second stators 220 and 240 due to the current flowing through the
coil winding body 221. Since an induction field is produced in the
conductor member 260 due to the magnetic flux, the force is applied
in a top dead center direction, so that the conductor member 260
and the movable member 130 move in the top dead center direction to
compress the refrigerant. Next, when the current is not input to
the coil winding body 221, the magnet flux and the induction field
are vanished, and the conductor member 260 and the movable member
130 move in a bottom dead center direction due to the restoration
force of the front main springs S1. Such a process is repeated to
suck, compress and discharge the refrigerant.
[0064] As illustrated in FIG. 4, another embodiment of the first
stator 220 is constructed such that core blocks 222 are mounted on
one coil winding body 221 wound with a coil in a circumferential
direction like the above embodiment. The control unit controls
On/Off of current supply with respect to the coil winding body 221
so as to produce a one-way magnetic field in the conductor member
260, and produces a force so that the conductor member 260 can move
in a refrigerant suction direction, i.e., a bottom dead center
direction unlike the above embodiment. Here, preferably, only the
rear main springs S2 are installed between the supporter 310 and
the rear cover 320 to grant a restoration force against a force
applied to the movable member 130 by the linear motor 200.
Moreover, preferably, the elastic modulus and number of the rear
main springs S2 are determined to be proportional to the coil
winding number of the coil winding body 221 as in the above
embodiment.
[0065] Therefore, when the current is input to the coil winding
body 221, a magnet flux forms a closed circuit along the first and
second stators 220 and 240 due to the current flowing through the
coil winding body 221. Since an induction field is produced in the
conductor member 260 due to the magnetic flux, the force is applied
in a bottom dead center direction, so that the conductor member 260
and the movable member 130 move in the bottom dead center direction
to suck the refrigerant. Next, when the current is not input to the
coil winding body 221, the magnet flux and the induction field are
vanished, and the conductor member 260 and the movable member 130
move in a top dead center direction due to the restoration force of
the rear main springs S2. Such a process is repeated to suck,
compress and discharge the refrigerant.
[0066] As illustrated in FIG. 5, a further embodiment of the first
stator 220 is constructed such that first and second coil winding
bodies 221A and 221B wound with a coil in a circumferential
direction are positioned at a certain interval in an axial
direction, and core blocks 222 are mounted on the first and second
coil winding bodies 221A and 221B. The coil is wound around the
first and second coil winding bodies 221A and 221B in the same
direction. The control unit performs a control to supply currents
having a phase difference of 90.degree. to the first and second
coil winding bodies 221A and 221B, respectively, to produce a
two-way magnetic field in the conductor member 260, and repeats a
process of producing a force so that the conductor member 260 can
move in a refrigerant compression direction, i.e., a top dead
center direction, and producing a force so that the conductor
member 260 can move in a refrigerant suction direction, i.e., a
bottom dead center direction.
[0067] Here, preferably, the front main springs S1 are installed
between the motor cover 300 and the supporter 310 and the rear main
springs S2 are installed between the supporter 310 and the rear
cover 320 to grant a restoration force against a force applied to
the movable member 130 by the linear motor 200. In addition,
preferably, the elastic modulus and number of the front main
springs S1 and the rear main springs S2 are determined to be
proportional to the coil winding number of the first and second
coil winding bodies 221A and 221B.
[0068] Accordingly, when the current is input to the first coil
winding body 221A, as the currents having AC waveforms with a phase
difference of 90.degree. are input to the first and second coil
winding bodies 221A and 221B, the magnetic flux also has AC
waveforms. Since an induction field is produced in the conductor
member 260 due to the magnetic flux, the force is applied
alternately in top and bottom dead center directions, so that the
conductor member 260 and the movable member 130 repeat a process of
moving in the top dead center direction to compress the refrigerant
and moving in the bottom dead center direction to suck the
refrigerant.
[0069] The construction and operation of the conductor member 260
applied to the linear compressor so constructed will be described
below in more detail.
[0070] FIGS. 6 to 8 are perspective views illustrating various
embodiments of the conductor member applied to the linear
compressor according to the present invention.
[0071] As illustrated in FIG. 6, an embodiment of the conductor
member 260 is formed of a conductor material such as Cu and Al in a
shape corresponding to a connection member 290, e.g., a cylindrical
shape. Here, the conductor member 260 is mounted on one end of the
connection member 290 by an adhesive or an adhesion member, and the
connection member 290 is installed to connect the conductor member
260 to the movable member 130. Surely, the connection member 290
has the same construction as the conventional one, and has various
holes 291 in portions other than the mounting portion of the
conductor member 260 to reduce a passage resistance or radiate
heat.
[0072] As illustrated in FIG. 7, another embodiment of the
conductor member 270 is formed in a cylindrical shape by
alternately stacking an annular iron piece 270a and a ring
conductor 270b. Like the above embodiment, the conductor member 270
is mounted on one end of a connection member 290 by an adhesive or
an adhesion member, and the connection member 290 is installed to
connect the conductor member 270 to the movable member 130. The
ring conductor 270b may be formed of a conductor material such as
Cu and Al.
[0073] As illustrated in FIG. 8. a further embodiment of the
conductor member 280 is formed by winding a conductor line. The
conductor member 280 is mounted to be wound around the outside of
one end of a connection member 290 or the outside of the connection
member 290, and the connection member 290 is installed to connect
the conductor member 280 to the movable member 130.
[0074] The conductor members 260, 270 and 280 shown in FIGS. 6 to 8
are preferably formed of Al or Cu, and have the feature of being
magnetically induced by an electromagnetic force. Since the
conductor members 260, 270 and 280 are applied to the linear motor
200, the present invention can more reduce manufacturing expenses
than the prior art using the magnet.
[0075] FIG. 9 is a graph showing magnetic flux waveforms of the
linear motor shown in FIG. 5 by an applied current. When the
control unit applies power to the linear motor 200 including the
first and second coil winding bodies 221A and 221B, with respect to
currents flowing through the first stator 220, a current I.sub.M of
the first coil winding body 221A and a current I.sub.A of the
second coil winding body 221B have AC waveforms with a phase
difference of 90.degree.. Therefore, a synthetic magnetic field
B.sub.S of the first stator 220 by the current shows AC waveforms.
The produced magnetic field linearly reciprocates, alternated in
positive and negative directions like the waveforms of the currents
I.sub.M and I.sub.A.
[0076] FIG. 10 is a schematic circuit view for applying a current
to the linear motor shown in FIG. 5. For example, when an AC
current is applied to a terminal I-I', the current I.sub.A applied
to the second coil winding body 221A is the AC current applied
through a capacitor C, and has a phase difference of 90.degree.
from the current I.sub.M applied to the first coil winding body
221A.
[0077] FIG. 11 is a graph showing linear reciprocation magnetic
flux operations of the linear motor shown in FIG. 5. FIG. 11
provides a graph showing the current I.sub.M of the first coil
winding body 221A, the current I.sub.A of the second coil winding
body 221B, and the synthetic magnetic field B.sub.S of the first
stator 220 in the application of the current, and a table showing
the linear reciprocation magnetic flux operations of the linear
motor 200 in points a to f existing in one period. That is, the
table of FIG. 11 shows that the first and second coil winding
bodies 221A and 221B are repeatedly magnetized into N-S and S-N
poles in the points a to f according to the applied voltage.
[0078] More specifically, in the points a, b and c, B.sub.S which
is the sum of I.sub.M and I.sub.A appears in a positive direction,
i.e., an N pole, and an amplitude thereof increases and then
decreases, and in the points d, e and f, B.sub.S which is the
magnetic field sum of I.sub.M and I.sub.A appears in a negative
direction, i.e., an S pole, and an amplitude thereof increases and
then decreases. As noted above, the magnetic flux is alternated in
the positive/negative directions by the first coil winding body
221A and the second coil winding body 221B, and the electromagnetic
force of the first and second stators 220 and 240 and the induction
field of the conductor member 260 interwork with each other.
[0079] FIG. 12 is a graph showing the relation between a slip and a
torque of the linear motor shown in FIG. 5 in variations of a
voltage, and FIG. 13 is a graph showing the relation between the
slip and the torque of the linear motor shown in FIG. 5 in
variations of a frequency. In the linear compressor, when a load
increases, a refrigerant gas is expanded, so that a speed of the
movable member 130 decreases. The linear compressor varies the
voltage or the frequency according to the load to control the speed
of the movable member 130, thereby compensating for decrease of a
cooling capacity caused by the speed reduction of the movable
member 130. The right-side graph of FIG. 12 is an enlarged view of
a portion of the left-side graph.
[0080] Therefore, when the linear compressor designed to vary the
voltage or the frequency according to the load is applied to e.g.,
a refrigerator, the linear motor 200 automatically regulates a
freezing capacity, and the refrigerator naturally modulates the
cooling capacity according to the load.
[0081] When the linear motor 200 adopting the conductor member 260
operates, the relation between the slip which is the speed of the
movable member 130 and the torque which is the force moving the
movable member 130 will be examined in more detail. As illustrated
in FIGS. 12 and 13, when the linear motor 200 is initially driven,
the slip and the torque rise to be proportional. When the linear
motor 200 stably operates in a slip of over a certain value or a
set value, the slip and the torque are inversely proportional
regardless of the load.
[0082] As illustrated in FIG. 12, A represents an S-T curve in a
first voltage, B represents an S-T curve in a second voltage higher
than the first voltage, and C represents an S-T curve using a
variable voltage. Here, the refrigerant inside the linear
compressor is expanded in a high temperature state, so that an
elastic modulus of the refrigerant gas increases. As a result,
driving the linear motor 200 in a slip identical to that of a low
temperature state requires more force in the high temperature
state. The high temperature state slip is smaller than the low
temperature state slip in the same torque.
[0083] Accordingly, when the load increases, e.g., when an ambient
temperature rises from a low to high temperature, the control unit
varies the voltage input to the linear motor 200, so that the S-T
characteristic moves following curve C as shown in FIG. 12. Here,
if the control unit does not adjust the voltage, the S-T
characteristic moves from a low temperature region II of curve A to
a high temperature region I of curve A. However, when the control
unit adjusts the voltage, e.g., when the control unit varies power
applied to the linear motor 200 from the first voltage to the
second voltage, the stroke of the movable member 130 is identically
maintained, and the speed of the movable member 130 increases, so
that the high temperature region I of curve A is changed into a
high temperature region II' of curve B. Therefore, the S-T
characteristic moves from the low temperature region II of curve A
to the high temperature region II' of curve B, i.e., moves
following curve C.
[0084] As described above, when the S-T characteristic moves from
the low temperature region II to the high temperature region II'
following curve C, the slip relatively less decreases or decreases,
and the torque is maintained to be substantially identical or
increases, so that the stroke of the movable member 130 increases.
Accordingly, the reduction of the cooling capacity caused by the
decrease of the slip is compensated for by the increase of the
stroke of the movable member 130, thereby modulating the cooling
capacity. The voltage of the linear motor 200 may vary from the
second voltage to the first voltage to modulate the cooling
capacity.
[0085] The control unit is constructed to control an AC chopper
unit and a triac unit so as to vary the voltage applied to the
linear motor 200 as noted. A mechanism insensitive to voltage
variations is designed to control the voltage to be appropriate for
the cooling capacity required in the linear compressor, to thereby
ensure modulation of the cooling capacity. That is, when judging
the load as an overload, the control unit applies a voltage to
delay the time to turn on the AC chopper unit and the triac unit in
a refrigerant suction stroke or to advance the time to turn on the
AC chopper unit and the triac unit in a refrigerant compression
stroke. On the contrary, when judging the load as a low load, the
control unit applies a voltage to advance the time to turn on the
AC chopper unit and the triac unit in the refrigerant suction
stroke or to delay the time to turn on the AC chopper unit and the
triac unit in the refrigerant compression stroke.
[0086] As illustrated in FIG. 13, A represents an S-T curve in a
first frequency, B represents an S-T curve in a second frequency
higher than the first frequency, and C represents an S-T curve
using a variable frequency. Here, the refrigerant inside the linear
compressor is expanded in a high temperature state, so that an
elastic modulus of the refrigerant gas increases. Consequently,
driving the linear motor 200 in a slip identical to that of a low
temperature state requires more force in the high temperature
state. The high temperature state slip is smaller than the low
temperature state slip in the same torque.
[0087] Accordingly, when a load increases, e.g., when an ambient
temperature rises from a low to high temperature, the control unit
varies the frequency input to the linear motor 200, so that the S-T
characteristic moves following curve C as shown in FIG. 13. Here,
if the control unit does not adjust the frequency, the S-T
characteristic moves from a low temperature region II of curve A to
a high temperature region I of curve A. However, when the control
unit adjusts the frequency, i.e., when the control unit supplies
power varying from the first frequency to the second frequency to
the linear motor 200 to prevent variations of the force moving the
movable member 130, the stroke of the movable member 130 is
identically maintained, and the speed of the movable member 130
increases, so that the high temperature region I of curve A is
changed into a high temperature region I' of curve B. As a result,
the S-T characteristic moves from the low temperature region II of
curve A to the high temperature region I' of curve B, i.e., moves
following curve C.
[0088] As described above, when the S-T characteristic moves from
the low temperature region II to the high temperature region I'
following curve C, the slip increases, or the torque is maintained
to be substantially identical or increases, so that the stroke of
the movable member 130 increases to thereby modulate the cooling
capacity. In addition, power varying from the second frequency to
the first frequency may be applied to the linear motor 200 to
reduce the cooling capacity.
[0089] The control of the voltage amplitude and the control of the
frequency amplitude may be simultaneously, selectively or
alternately performed.
[0090] The control unit is constructed to control an inverter unit
so as to vary the frequency applied to the linear motor 200 as
noted. The inverter unit includes a rectification unit which
rectifies AC power, and an inverter element which converts a
rectified voltage from the rectification unit into an AC voltage
according to a control signal. The inverter unit applies power to
the linear motor 200 according to a control frequency by the
control signal. Surely, the inverter unit may apply power according
to a control voltage.
[0091] The AC chopper method and the triac phase control method
which are the methods using applied voltage variations, and the
inverter method which is the method using applied frequency
variations are nothing but examples of the control methods for
modulating the cooling capacity according to the load. Besides,
methods for naturally modulating a cooling capacity can also be
used, such as a direct application method which is a mechanical
design method optimizing the relation between a slip and a torque
regardless of a load, and a current direct application method which
is a mechanical design method using a mechanical resonance
frequency varied according to a load.
[0092] While the present invention has been described in connection
with the preferred embodiments, the present invention is not
limited thereto and is defined by the appended claims. Therefore,
it will be understood by those skilled in the art that various
modifications and changes can be made thereto without departing
from the spirit and scope of the invention defined by the appended
claims.
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