U.S. patent application number 13/259382 was filed with the patent office on 2012-02-09 for linear compressor.
Invention is credited to Hyo Jae Lee.
Application Number | 20120034114 13/259382 |
Document ID | / |
Family ID | 44146030 |
Filed Date | 2012-02-09 |
United States Patent
Application |
20120034114 |
Kind Code |
A1 |
Lee; Hyo Jae |
February 9, 2012 |
LINEAR COMPRESSOR
Abstract
The present invention discloses a linear compressor including: a
hermetic container which defines a sealed space where a refrigerant
flows in and out and which has an inlet pipe and an outlet pipe; a
cylinder provided in the hermetic container and having a
compression space therein; a piston linearly reciprocated in the
cylinder and compressing the refrigerant of the compression space;
a linear motor supplying a driving force to the piston and
operating the piston at a set operating frequency; a plurality of
support springs elastically supporting an assembly composed of the
cylinder, the piston and the linear motor on the bottom surface of
the hermetic container; and a loop pipe provided to guide the
refrigerant compressed in the compression space to the outlet pipe.
As the exciting force exerted on the hermetic container by the loop
pipe has an opposite phase to the exciting force exerted on the
hermetic container by the support springs, vibration of the
assembly can be offset by vibration of the loop pipe through the
phase shift, and thus the overall vibration can be reduced.
Inventors: |
Lee; Hyo Jae;
(Gyeongsangnam-do, KR) |
Family ID: |
44146030 |
Appl. No.: |
13/259382 |
Filed: |
December 6, 2010 |
PCT Filed: |
December 6, 2010 |
PCT NO: |
PCT/KR2010/008672 |
371 Date: |
October 19, 2011 |
Current U.S.
Class: |
417/417 |
Current CPC
Class: |
F04B 35/045 20130101;
F04B 39/0072 20130101; F04B 39/0044 20130101 |
Class at
Publication: |
417/417 |
International
Class: |
F04B 17/03 20060101
F04B017/03 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 8, 2009 |
KR |
10-2009-0121292 |
Claims
1. A linear compressor, comprising: a hermetic container which
defines a sealed space where a refrigerant flows in and out and
which has an inlet pipe and an outlet pipe; a cylinder provided in
the hermetic container and having a compression space therein; a
piston linearly reciprocated in the cylinder and compressing the
refrigerant of the compression space; a linear motor supplying a
driving force to the piston and operating the piston at a set
operating frequency; a plurality of support springs elastically
supporting an assembly composed of the cylinder, the piston and the
linear motor on the bottom surface of the hermetic container; and a
loop pipe provided to guide the refrigerant compressed in the
compression space to the outlet pipe, wherein the exciting force
exerted on the hermetic container by the loop pipe has an opposite
phase to the exciting force exerted on the hermetic container by
the support springs.
2. The linear compressor of claim 1, wherein the natural frequency
of the loop pipe is set equal to or lower than the rated operating
frequency of the linear motor.
3. The linear compressor of claim 2, wherein the rated operating
frequency of the linear motor is set to 60 Hz, and the natural
frequency of the loop pipe is set to 50 Hz or less.
4. A linear compressor, comprising: a hermetic container which
defines a sealed space where a refrigerant flows in and out; a
cylinder provided in the hermetic container and having a
compression space therein; a piston linearly reciprocated in the
cylinder and compressing the refrigerant of the compression space;
a linear motor supplying a driving force to the piston and
operating the piston at a set operating frequency; a support spring
elastically supporting an assembly composed of the cylinder, the
piston and the linear motor on the bottom surface of the hermetic
container; and a loop pipe provided to guide the refrigerant
compressed in the compression space to the outlet pipe, wherein the
rated operating frequency of the linear motor is greater than the
natural frequency of the loop pipe.
5. The linear compressor of claim 4, wherein the rated operating
frequency of the linear motor is determined in proportion to the
natural frequency of the loop pipe.
Description
TECHNICAL FIELD
[0001] The present invention relates to a linear compressor which
can reduce vibration through the phase shift between vibration
factors.
BACKGROUND ART
[0002] In general, a compressor is a mechanical apparatus for
receiving power from a power generation apparatus, such as an
electric motor, a turbine, etc. and compressing the air,
refrigerant or other various operating gases to raise the pressure.
The compressor has been widely used in electric home appliances
such as refrigerators, air conditioners, etc., and its application
has been expanded to the whole industry.
[0003] The compressors are roughly classified into a reciprocating
compressor in which a compression space for sucking and discharging
an operating gas is defined between a piston and a cylinder so that
the piston can be linearly reciprocated in the cylinder to compress
a refrigerant, a rotary compressor in which a compression space for
sucking and discharging an operating gas is defined between an
eccentrically-rotated roller and a cylinder so that the roller can
be eccentrically rotated along the inner wall of the cylinder to
compress a refrigerant, and a scroll compressor in which a
compression space for sucking and discharging an operating gas is
defined between an orbiting scroll and a fixed scroll so that the
orbiting scroll can be rotated along the fixed scroll to compress a
refrigerant.
[0004] Recently, a linear compressor which not only improves
compression efficiency but also has a simple structure has been
actively developed among the reciprocating compressors. In
particular, the linear compressor does not have a mechanical loss
caused by motion conversion since a piston is directly connected to
a driving motor which performs a linear reciprocating motion.
[0005] FIG. 1 is a structural diagram of vibration factors of a
conventional linear compressor.
[0006] As illustrated in FIG. 1, the conventional linear compressor
includes a hermetic container 10 defining a sealed space and a main
body 20 composed of a cylinder, a piston and a linear motor and
compressing a refrigerant in the hermetic container 10. Here, the
main body 20 is elastically supported in the hermetic container 10
by a plurality of support springs S and a loop pipe L defining a
discharge passage of the refrigerant, and the hermetic container 10
is fixed to and elastically supported on the installation surface
via a mount 11 provided on its bottom surface.
[0007] Normally, in the linear compressor, a permanent magnet of
the linear motor driving the piston is driven together with the
piston, which increases the vibration as well as the mass of a
mechanism unit performing a linear reciprocating motion. However,
since the linear compressor operates in a resonance state to
improve compression efficiency, reducing the mass of the mechanism
unit to reduce vibration may unsuitably degrade the overall
efficiency of the compressor. Therefore, in the linear compressor,
it is necessary to optimize the vibration transferring
characteristic between the hermetic container 10 and the main body
20 so as to reduce vibration. Here, the factors having an influence
on the vibration transferring characteristic include the mount 11,
the support springs S, and the loop pipe L. While the rigidity of
the mount 11 and the rigidity and height of the support springs S
do not have an influence on the overall efficiency, a given
rigidity and mass of the loop pipe L have a large influence on the
overall efficiency in terms of the design of the linear compressor
using the resonance.
[0008] FIG. 2 is a graph showing vibration displacements of the
loop pipe employed in the conventional linear compressor.
[0009] As illustrated in FIG. 2, the design is made such that the
conventional linear compressor has a rated operating frequency of
60 Hz and that the loop pipe has a natural frequency of 70 Hz to 90
Hz which is higher than the rated operating frequency. Here, as in
the conventional reciprocating compressor, the linear motor raises
the operating frequency from 0 Hz to 60 Hz upon starting.
Specifically, if the natural frequency of the loop pipe is lower
than the operating frequency of the linear compressor, while the
operating frequency of the linear compressor is raised to the rated
operating frequency upon starting, resonance occurs when the
operating frequency of the linear compressor becomes equal to the
natural frequency of the loop pipe, which may lead to damage of the
loop pipe. It is thus preferable that the natural frequency of the
loop pipe should be set higher than the rated operating frequency
of the linear compressor.
[0010] However, in the conventional linear compressor, the main
body is elastically supported in the hermetic container by the
support springs and the loop pipe, and the natural frequency of the
loop pipe is set higher than the rated operating frequency. While
the operating frequency is raised to the rated operating frequency
upon starting, the exciting force of the loop pipe increases in the
same direction as the exciting force of the support springs. As a
result, the exciting force of the loop pipe and the exciting force
of the support springs are superimposed, which amplifies vibration
transferred to the entire compressor upon starting.
DISCLOSURE
Technical Problem
[0011] The present invention has been made to solve the
aforementioned problems in the prior art. An object of the present
invention is to provide a linear compressor which can reduce
vibration through the phase shift.
Technical Solution
[0012] According to an aspect of the present invention for
achieving the above object, there is provided a linear compressor
including: a hermetic container which defines a sealed space where
a refrigerant flows in and out and which has an inlet pipe and an
outlet pipe; a cylinder provided in the hermetic container and
having a compression space therein; a piston linearly reciprocated
in the cylinder and compressing the refrigerant of the compression
space; a linear motor supplying a driving force to the piston and
operating the piston at a set operating frequency; a plurality of
support springs elastically supporting an assembly composed of the
cylinder, the piston and the linear motor on the bottom surface of
the hermetic container; and a loop pipe provided to guide the
refrigerant compressed in the compression space to the outlet pipe,
wherein the exciting force exerted on the hermetic container by the
loop pipe has an opposite phase to the exciting force exerted on
the hermetic container by the support springs.
[0013] In addition, the natural frequency of the loop pipe may be
set equal to or lower than the rated operating frequency of the
linear motor.
[0014] Moreover, the rated operating frequency of the linear motor
may be set to 60 Hz, and the natural frequency of the loop pipe may
be set to 50 Hz or less.
[0015] According to another aspect of the present invention, there
is provided a linear compressor including: a hermetic container
which defines a sealed space where a refrigerant flows in and out;
a cylinder provided in the hermetic container and having a
compression space therein; a piston linearly reciprocated in the
cylinder and compressing the refrigerant of the compression space;
a linear motor supplying a driving force to the piston and
operating the piston at a set operating frequency; a support spring
elastically supporting an assembly composed of the cylinder, the
piston and the linear motor on the bottom surface of the hermetic
container; and a loop pipe provided to guide the refrigerant
compressed in the compression space to the outlet pipe, wherein the
rated operating frequency of the linear motor is greater than the
natural frequency of the loop pipe.
[0016] Additionally, the rated operating frequency of the linear
motor may be determined in proportion to the natural frequency of
the loop pipe.
Advantageous Effects
[0017] As described above, in the linear compressor according to
the present invention, the main body is elastically supported in
the hermetic container by the support springs and the loop pipe,
and the natural frequency of the loop pipe is set lower than the
rated operating frequency. Since the linear compressor operates at
the rated operating frequency directly upon starting by using the
inverter motor, the exciting force of the loop pipe moves in the
opposite direction to the exciting force of the support springs at
the rated operating frequency, thereby reducing vibration
transferred to the entire compressor.
DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a structural diagram of vibration factors of a
conventional linear compressor.
[0019] FIG. 2 is a graph showing vibration displacements of a loop
pipe employed in the conventional linear compressor.
[0020] FIG. 3 is a side-sectional view of an embodiment of a linear
compressor according to the present invention.
[0021] FIG. 4 is a graph showing vibration displacements of a loop
pipe employed in the linear compressor according to the present
invention.
[0022] FIG. 5 is a graph showing vibration amplitudes of a hermetic
container by variations of the natural frequency of the loop pipe
in the linear compressor according to the present invention.
MODE FOR INVENTION
[0023] Hereinafter, exemplary embodiments of the present invention
will be described in detail with reference to the attached
drawings.
[0024] FIG. 3 is a side-sectional view of an embodiment of a linear
compressor according to the present invention.
[0025] Referring to FIG. 3, in the embodiment of the linear
compressor according to the present invention, a cylinder 200, a
piston 300, and a linear motor 400 composed of an inner stator 420,
an outer stator 440 and a permanent magnet 460 are provided in a
hermetic container 110 defining a sealed space. When the permanent
magnet 460 is linearly reciprocated between the inner stator 420
and the outer stator 440 due to a mutual electromagnetic force, the
piston 300 connected to the permanent magnet 460 is linearly
reciprocated together with the permanent magnet 460.
[0026] While the inner stator 420 is secured to the outer
circumference of the cylinder 200, the outer stator 440 is secured
in the axial direction by a frame 520 and a motor cover 540. The
frame 520 and the motor cover 540 are coupled to each other by
means of a fastening member such as a bolt, so that the outer
stator 440 is secured between the frame 520 and the motor cover
540. The frame 520 may be integrated with the cylinder 200 or may
be separately manufactured and coupled to the cylinder 200. In the
embodiment shown in FIG. 3, the frame 520 and the cylinder 200 are
provided as an integral unit.
[0027] A supporter 320 is connected to the rear of the piston 300.
Both ends of four front main springs 800 are supported by the
supporter 320 and the motor cover 540. In addition, both ends of
four rear main springs 800 are supported by the supporter 320 and a
back cover 560 that is coupled to the rear of the motor cover 540.
Moreover, a suction muffler 700 is provided at the rear of the
piston 300 and reduces noise when a refrigerant flows into the
piston 300.
[0028] The piston 300 is provided as a hollow type so that the
refrigerant flowing through the suction muffler 700 can be
introduced into and compressed in a compression space P defined
between the cylinder 200 and the piston 300. A suction valve 610,
which is provided at a front end of the piston 300, opens the front
end of the piston 300 to allow the refrigerant to flow from the
piston 300 to the compression space P and closes it to prevent the
refrigerant from flowing backward from the compression space P to
the piston 300.
[0029] If the refrigerant is compressed in the compression space P
over a given pressure by the piston 300, it opens a discharge valve
620 positioned at a front end of the cylinder 200. The discharge
valve 620 is provided in a support cap 640 secured to one end of
the cylinder 200 and is elastically supported by a spiral discharge
valve spring 630. The compressed high-pressure refrigerant is
discharged to a discharge cap 660 through a hole formed in the
support cap 640, discharged to the outside of the linear compressor
100 through a loop pipe L, and circulated in a refrigeration
cycle.
[0030] The respective components of the linear compressor 100
described above are supported by a front support spring 120 and a
rear support spring 140 in the assembled state and spaced apart
from the bottom of the hermetic container 110. Since the components
are not in direct contact with the bottom of the hermetic container
110, vibration generated in the respective components of the linear
compressor 100 while they are compressing the refrigerant is not
directly transferred to the hermetic container 110. As a result, it
is possible to reduce vibration transferred to the outside of the
hermetic container 110 and noise caused by the vibration of the
hermetic container 110.
[0031] As described in connection with the prior art, it is
necessary for the linear compressor to optimize the vibration
transferring characteristic so as to reduce vibration and also
necessary to place a limitation on the design of the loop pipe L
which is a factor having an influence on compression efficiency. Of
course, as the main body composed of the cylinder 200, the piston
300 and the linear motor 400 is elastically supported in the
hermetic container 110 by the support springs 120 and 140 and the
loop pipe L, vibration transferred to the hermetic container 110
can be considered as the sum of the exciting force of the support
springs 120 and 140 and the exciting force of the loop pipe L.
However, according to the present invention, the design is made
such that the exciting force of the loop pipe L has the opposite
phase to the exciting force of the support springs 120 and 140,
thus reducing vibration transferred to the entire compressor.
[0032] FIG. 4 is a graph showing vibration displacements of the
loop pipe employed in the linear compressor according to the
present invention.
[0033] Referring to FIG. 4, in the linear compressor according to
the present invention, the natural frequency f.sub.lp of the loop
pipe is set lower than the rated operating frequency f so as to
reduce vibration through the phase shift. Here, as shown in the
graph, while the loop pipe vibrates in a positive (+) direction at
a frequency lower than its natural frequency f.sub.lp, it vibrates
in a negative (-) direction at a frequency higher than its natural
frequency f.sub.lp. Therefore, if the rated operating frequency f
is higher than the natural frequency f.sub.lp of the loop pipe,
vibration of the loop pipe is phase-shifted, and the exciting force
of the loop pipe operates in the opposite direction to the exciting
force of the support springs, which reduces vibration transferred
to the entire hermetic container.
[0034] Further, the linear motor operates at the rated operating
frequency f directly upon starting in order to prevent damage of
the loop pipe. At this time, if the linear motor sweeps from 0 to
the rated operating frequency f upon starting, the operating
frequency becomes equal to the natural frequency f.sub.lp of the
loop pipe before reaching to the rated operating frequency f, which
leads to resonance damaging the loop pipe. It is thus preferable to
employ an inverter motor, which operates at the rated operating
frequency f directly upon starting, as the linear motor.
[0035] For example, the rated operating frequency f may be set to
60 Hz so that the linear motor operates at the rated operating
frequency f directly upon starting, and the natural frequency
f.sub.lp of the loop pipe may be set to 50 Hz or less which is
lower than the rated operating frequency f.
[0036] FIG. 5 is a graph showing vibration amplitudes of the
hermetic container by variations of the natural frequency of the
loop pipe in the linear compressor according to the present
invention.
[0037] FIG. 5 shows an experiment result of the linear compressor
according to the present invention, in which experiment the
vibration transferred to the entire hermetic container was
measured, setting the rated operating frequency to 60 Hz and
varying the natural frequency of the loop pipe.
[0038] As shown in FIG. 5, the closer the natural frequency
f.sub.lp of the loop pipe to 60 Hz which is the rated operating
frequency, the greater the vibration transferred to the entire
hermetic container. When the natural frequency f.sub.lp of the loop
pipe is set in a frequency domain lower than 60 Hz which is the
rated operating frequency f, it reduces vibration transferred to
the entire hermetic container.
[0039] In more detail, if the natural frequency f.sub.lp of the
loop pipe varies from 35 Hz to 50 Hz, vibration of the hermetic
container increases from 13 Gal to 75 Gal. However, since a
vibration variation .DELTA.f of the hermetic container caused by a
natural frequency variation .DELTA.f.sub.lp of the loop pipe is
small, it can be deemed that vibration transferred to the
compressor is stable in this section. Meanwhile, if the natural
frequency f.sub.lp of the loop pipe varies from 50 Hz to 60 Hz,
vibration of the hermetic container increases from 57 Gal to 1120
Gal. As the vibration variation .DELTA.f of the hermetic container
caused by the natural frequency variation .DELTA.f.sub.lp of the
loop pipe is large, it can be deemed that vibration transferred to
the compressor is amplified in this section. Additionally, if the
natural frequency f.sub.lp of the loop pipe varies from 60 Hz to 70
Hz, vibration of the hermetic container decreases from 1120 Gal to
452 Gal. But, since the vibration variation .DELTA.f of the
hermetic container caused by the natural frequency variation
.DELTA.f.sub.lp of the loop pipe is smaller than that in the above
variation amplification section, even if the actual vibration value
transferred to the hermetic container decreases, it is much larger
than in the above vibration stable section. Furthermore, if the
natural frequency f.sub.lp of the loop pipe varies to 70 Hz or
more, vibration of the hermetic container decreases to 452 Gal or
less. However, since the vibration variation .DELTA.f of the
hermetic container caused by the natural frequency variation
.DELTA.f.sub.lp of the loop pipe is smaller than that in the above
variation amplification section, likewise, even if the actual
vibration value transferred to the hermetic container decreases, it
is much larger than in the above vibration stable section.
[0040] As a result, taking vibration of the entire compressor into
consideration, it is preferable that the natural frequency f.sub.lp
of the loop pipe should be set in a frequency domain of 50 Hz or
less in the compressor having a rated operating frequency f of 60
Hz. Moreover, considering that the natural frequency f.sub.lp of
the loop pipe is determined in proportion to the rated operating
frequency f, it is preferable that the natural frequency f.sub.lp
of the loop pipe should be set in a frequency domain of 41.6 Hz or
less in the compressor having a rated operating frequency f of 50
Hz.
[0041] The present invention has been described in detail with
reference to the exemplary embodiments and the attached drawings.
However, the scope of the present invention is not limited to such
embodiments and drawings, but is defined by the appended
claims.
* * * * *