U.S. patent application number 14/365845 was filed with the patent office on 2014-10-16 for sealed compressor and refrigerator including sealed compressor.
This patent application is currently assigned to Panasonic Corporation. The applicant listed for this patent is Panasonic Corporation. Invention is credited to Yu Haraki, Terumasa Ide, Ko Inagaki, Kiwamu Watanabe.
Application Number | 20140308141 14/365845 |
Document ID | / |
Family ID | 48696772 |
Filed Date | 2014-10-16 |
United States Patent
Application |
20140308141 |
Kind Code |
A1 |
Haraki; Yu ; et al. |
October 16, 2014 |
SEALED COMPRESSOR AND REFRIGERATOR INCLUDING SEALED COMPRESSOR
Abstract
A sealed compressor (100) of the present invention comprises an
electric component (111), a compression component (117), and a
sealed container (101), the compression component includes a shaft
(119), a cylinder block (129), a piston (133), and a crank weight
(126), a rotor (115) of the electric component has a cylindrical
shape, contains a cylindrical space therein, and includes an upper
section (116) in which a lower portion of a bearing (131) of a
cylinder block is fitted into the cylindrical space, a lower
section (115e) to which a lower portion of the main shaft inserted
into the through-hole of the bearing and inserted into the
cylindrical space is fixedly fitted, and a balance weight (170,
270) placed on an opposite side of the crank weight with respect to
the piston.
Inventors: |
Haraki; Yu; (Osaka, JP)
; Inagaki; Ko; (Shiga, JP) ; Ide; Terumasa;
(Kyoto, JP) ; Watanabe; Kiwamu; (Shiga,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Corporation |
Kadoma-shi, Osaka |
|
JP |
|
|
Assignee: |
Panasonic Corporation
Kadoma-shi Osaka
JP
|
Family ID: |
48696772 |
Appl. No.: |
14/365845 |
Filed: |
December 26, 2012 |
PCT Filed: |
December 26, 2012 |
PCT NO: |
PCT/JP2012/008309 |
371 Date: |
June 16, 2014 |
Current U.S.
Class: |
417/415 |
Current CPC
Class: |
F04B 39/0094 20130101;
F04B 39/0246 20130101; F04B 39/02 20130101; F04B 39/0027
20130101 |
Class at
Publication: |
417/415 |
International
Class: |
F04B 39/00 20060101
F04B039/00; F04B 39/02 20060101 F04B039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 26, 2011 |
JP |
2011-283183 |
Claims
1. A sealed compressor comprising: an electric component including
a stator and a rotor which is rotatable with respect to the stator;
a compression component activated by the electric component placed
below the compression component; and a sealed container
accommodating the electric component and the compression component;
wherein the compression component includes: a shaft including a
main shaft, and an eccentric shaft which is eccentric with respect
to the main shaft; a cylinder block including a bearing having
inside thereof a through-hole extending vertically and supporting
the main shaft inserted into the through-hole such that the main
shaft is rotatable, and a cylinder having a compression chamber
inside thereof; a piston which is coupled to the eccentric shaft
and is reciprocatable within the compression chamber; and a crank
weight mounted to an upper portion of the eccentric shaft; wherein
the rotor has a cylindrical shape and contains a cylindrical space
therein; and wherein the rotor includes: an upper section in which
a lower portion of the bearing is fitted into the cylindrical
space; a lower section which is smaller in inner diameter than the
upper section, a lower portion of the main shaft inserted into the
through-hole of the bearing and inserted into the cylindrical space
being fixedly fitted to the lower section; and a balance weight
placed on an opposite side of the crank weight with respect to the
piston.
2. The sealed compressor according to claim 1, wherein a height of
the upper section is equal to or greater than 70% of a height of
the rotor.
3. The sealed compressor according to claim 1, wherein the
compression component further includes a thrust ball bearing placed
on a thrust surface of the bearing.
4. The sealed compressor according to claim 1, wherein a mass of
the balance weight is equal to or less than 1/5 of a mass of the
crank weight.
5. The sealed compressor according to claim 1, wherein the balance
weight is placed on a lower surface of the rotor.
6. The sealed compressor according to claim 1, wherein the balance
weight is placed on an upper surface of the rotor.
7. The sealed compressor according to claim 1, wherein the balance
weight is mounted to the rotor by a caulking pin.
8. A refrigerator comprising the sealed compressor as recited in
claim 1.
Description
TECHNICAL FIELD
[0001] The present invention relates to a sealed compressor and a
refrigerator including the sealed compressor. Particularly, the
present invention relates to a sealed compressor used in a heat
pump cycle such as a refrigeration cycle, and a refrigerator
including the sealed compressor.
BACKGROUND ART
[0002] Conventionally, there is known a sealed compressor which is
thinned and intended to mitigate the vibration caused by a piston,
which is one of sealed compressors in which a working fluid is
compressed by the piston into high-temperature and high-pressure
states and the resulting working fluid is discharged to a heat pump
cycle. For example, in the sealed compressor disclosed in Patent
Literature 1, the upper surface of a rotor is provided with a
recess, and the lower portion of a support frame is fitted into the
recess. This allows the support frame and the recess to overlap
with each other, and their lengths to be reduced. In this way, the
sealed compressor is thinned.
[0003] A crankshaft is composed of a body shaft, an eccentric plate
section formed at the upper end of the body shaft, and an eccentric
shaft provided at the eccentric plate section. The body shaft of
the crankshaft is rotatably inserted into a hole of the support
frame. The lower portion of the body shaft protrudes downward from
the hole of the support frame and is fixedly fitted to a rotor. The
eccentric shaft of the crankshaft protrudes upward from the support
frame, and a balance weight is mounted to the upper end portion of
the eccentric shaft. The piston is coupled to the eccentric shaft
and inserted into a cylinder bore of the support frame. In such a
sealed compressor, when the rotor rotates, the eccentric shaft of
the crankshaft eccentrically rotates, and the piston reciprocates
within the cylinder bore. At this time, the inertia force due to
the reciprocation motion of the piston and the eccentric rotation
motion of the eccentric shaft cause an unbalanced component of a
centrifugal force, which is a cause of the vibration of the sealed
compressor. To avoid this, the vibration of the sealed compressor
is mitigated by cancelling the unbalanced component by the
centrifugal force of a crank weight mounted to the eccentric
shaft.
CITATION LIST
Patent Literature
[0004] Patent Literature 1: Japanese Laid-Open Patent Application
Publication No. 2002-70740
SUMMARY OF INVENTION
Technical Problem
[0005] However, in the above described conventional sealed
compressor, in a case where the amount of the working fluid to be
discharged is increased, the volume of the cylinder bore and the
outer diameter of the piston are increased, or the stroke amplitude
of the piston is increased. In such a case, the unbalanced
component increases. Therefore, it is necessary to increase the
weight of the crank weight for cancelling the unbalanced component
to increase the centrifugal force.
[0006] However, if the centrifugal force of the crank weight is
increased so that the centrifugal force and the unbalanced
component are balanced, a rotational moment generated by the fact
that the piston and the crank weight are distant from each other
would increase. This increases the vibration of the runout of the
crankshaft in an inclined state, and as a result, increases a
vibration and a noise in the sealed compressor.
[0007] Especially, in the above stated sealed compressor, a
cantilever bearing configuration is employed, in which only one end
of the crankshaft is supported by the support frame. Since the
lower portion of the support frame is fitted into the recess, the
rotor and the crankshaft are fixedly fitted to each other in a
small range, which reduces a stiffness of the fitted portions. In
this case, the vibration of the runout of the crankshaft is
transmitted to the rotor, and thereby the vibration of the rotor
tends to be amplified. This significantly increases the vibration
and the noise in the sealed compressor, which is due to the
vibration of the crankshaft.
[0008] The present invention is directed to solving the above
described problem, and an object of the present invention is to
provide a thinned sealed compressor which can reduce a vibration
and a noise, and a refrigerator including the sealed
compressor.
Solution to Problem
[0009] According to an aspect of of the present invention, there is
provided a sealed compressor comprising: an electric component
including a stator and a rotor which is rotatable with respect to
the stator; a compression component activated by the electric
component placed below the compression component; and a sealed
container accommodating the electric component and the compression
component; wherein the compression component includes: a shaft
including a main shaft, and an eccentric shaft which is eccentric
with respect to the main shaft; a cylinder block including a
bearing having inside thereof a through-hole extending vertically
and supporting the main shaft inserted into the through-hole such
that the main shaft is rotatable, and a cylinder having a
compression chamber inside thereof; a piston which is coupled to
the eccentric shaft and is reciprocatable within the compression
chamber; and a crank weight mounted to an upper portion of the
eccentric shaft; wherein the rotor has a cylindrical shape and
contains a cylindrical space therein; and wherein the rotor
includes: an upper section in which a lower portion of the bearing
is fitted into the cylindrical space; a lower section which is
smaller in inner diameter than the upper section, a lower portion
of the main shaft inserted into the through-hole of the bearing and
inserted into the cylindrical space being fixedly fitted to the
lower section; and a balance weight placed on an opposite side of
the crank weight with respect to the piston.
Advantageous Effects of Invention
[0010] The present invention has the above described configuration,
and has advantages that it is possible to provide a sealed
compressor which can reduce a vibration and the noise, and a
refrigerator including the sealed compressor.
[0011] The above and further objects, features and advantages of
the invention will more fully be apparent from the following
detailed description of a preferred embodiment, with reference to
accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a cross-sectional view showing a sealed compressor
according to Embodiment 1 of the present invention.
[0013] FIG. 2 is an enlarged view showing a region A of FIG. 1.
[0014] FIG. 3A is a cross-sectional view of a rotor for use in the
sealed compressor of FIG. 1, which is taken along a plane
perpendicular to the axis of the rotor.
[0015] FIG. 3B is a cross-sectional view of the rotor which is
taken along broken lines B-B of FIG. 3A.
[0016] FIG. 4 is a view showing an external appearance of the rotor
of FIG. 3A, when viewed from a lower side.
[0017] FIG. 5 is a view schematically showing forces applied to a
shaft of the sealed compressor of FIG. 1.
[0018] FIG. 6 is a cross-sectional view showing a sealed compressor
according to Embodiment 2 of the present invention.
[0019] FIG. 7 is a view schematically showing forces applied to a
shaft of the sealed compressor of FIG. 6.
[0020] FIG. 8 is a cross-sectional view schematically showing a
refrigerator according to Embodiment 3 of the present
invention.
DESCRIPTION OF EMBODIMENTS
[0021] According to a first aspect of the present invention, there
is provided there is provided a sealed compressor comprising: an
electric component including a stator and a rotor which is
rotatable with respect to the stator; a compression component
activated by the electric component placed below the compression
component; and a sealed container accommodating the electric
component and the compression component; wherein the compression
component includes: a shaft including a main shaft, and an
eccentric shaft which is eccentric with respect to the main shaft;
a cylinder block including a bearing having inside thereof a
through-hole extending vertically and supporting the main shaft
inserted into the through-hole such that the main shaft is
rotatable, and a cylinder having a compression chamber inside
thereof, a piston which is coupled to the eccentric shaft and is
reciprocatable within the compression chamber; and a crank weight
mounted to an upper portion of the eccentric shaft; wherein the
rotor has a cylindrical shape and contains a cylindrical space
therein; and wherein the rotor includes: an upper section in which
a lower portion of the bearing is fitted into the cylindrical
space; a lower section which is smaller in inner diameter than the
upper section, a lower portion of the main shaft inserted into the
through-hole of the bearing and inserted into the cylindrical space
being fixedly fitted to the lower section; and a balance weight
placed on an opposite side of the crank weight with respect to the
piston.
[0022] In accordance with this configuration, since the lower
portion of the bearing is fitted into the cylindrical space in the
upper end portion of the rotor, the sealed compressor can be
thinned while lessening the height which is a sum of the height of
the rotor and the height of the bearing without a need to reduce
the length of the bearing. This reduces a range in which the lower
section of the rotor and the lower portion of the main shaft are
fixedly fitted to each other is small, and the stiffness of the
fitted portions is reduced. To avoid this, the forces and moments
applied by the eccentric shaft and the piston to the shaft can be
cancelled by the balance weight in addition to the crank weight.
This makes it possible to prevent the vibration of the runout of
the shaft in an inclined state. Therefore, it becomes possible to
prevent a situation in which the vibration of the shaft is
transmitted from the fitted portions with a low stiffness to the
rotor and thereby the vibration of the rotor is amplified. As a
result, the vibration and the noise in the sealed compressor can be
reduced.
[0023] According to a second aspect of the present invention, in
the sealed compressor according to the first aspect, a height of
the upper section may be equal to or greater than 70% of a height
of the rotor. In accordance with this configuration, the rotor and
the bearing fitted thereinto overlap with each other in a great
area, and as a result, the sealed compressor can be further
thinned
[0024] According to a third aspect of the present invention, in the
sealed compressor according to the first or second aspect, the
compression component may further include a thrust ball bearing
placed on a thrust surface of the bearing. In accordance with this
configuration, a friction or the like between the thrust surface of
the bearing and the eccentric shaft of the shaft can be mitigated
by the thrust ball bearing, and hence the vibration and the noise
which would be caused by them can be reduced.
[0025] According to a fourth aspect of the present invention, in
the sealed compressor according to any one of the first to third
aspects, a mass of the balance weight may be equal to or less than
1/5 of a mass of the crank weight. In accordance with this
configuration, since the mass of the balance weight is reduced, the
centrifugal force of the balance weight is reduced. This makes it
possible to prevent the deformation of the rotor due to the
centrifugal force of the balance weight and reduce the vibration
and the noise, which would be caused by the deformation.
[0026] According to a fifth aspect of the present invention, in the
sealed compressor according to any one of the first to fourth
aspects, the balance weight may be placed on a lower surface of the
rotor. In accordance with this configuration, since the balance
weight placed on the lower surface is distant from the piston and
the crank weight, unbalanced moment component can be cancelled by
the balance weight with a small mass. Therefore, generation of the
noise and the vibration due to the unbalanced moment component can
be prevented. In addition, the lower section fixedly fitted to the
main shaft and the balance weight are provided in the lower portion
of the rotor such that they are close to each other. This makes it
possible to prevent the deformation of the rotor, and hence
generation of the vibration and the noise which would be caused by
the deformation.
[0027] According to a sixth aspect of the present invention, in the
sealed compressor according to any one of the first to fourth
aspects, the balance weight may be placed on an upper surface of
the rotor. In accordance with this configuration, the balance
weight placed on the upper surface is distant from the liquid level
of the lubricating oil reserved in the bottom portion of the sealed
container. This makes it possible to prevent a situation in which
the balance weight is immersed in the lubricating oil and stirs the
lubricating oil, and formation of bubbles of the working fluid
dissolved into the lubricating oil is facilitated. As a result, it
becomes possible to prevent generation of the noise due to the
lubricating oil contained in the bubbles of the working fluid.
[0028] According to a seventh aspect of the present invention, in
the sealed compressor according to any one of the first to sixth
aspects, the balance weight may be mounted to the rotor by a
caulking pin. In accordance with this configuration, the stack
structure composed of a plurality of steel plates constituting the
rotor can be fastened together by the caulking pin, and the balance
weight can be mounted to the rotor. This provides a high
productivity.
[0029] According to an eighth aspect of the present invention,
there is provided a refrigerator comprising the sealed compressor
as recited in any one of the first to seventh aspects. In
accordance with this configuration, the thinned sealed compressor
allows the internal space of the refrigerator to be expanded, and
the heat-insulating wall of the refrigerator to be increased. Thus,
the refrigerator can be used more easily and the heat-insulating
capability can be improved. Moreover, by the sealed compressor with
the vibration mitigated, the noise and the vibration in the
refrigerator can be reduced.
[0030] Hereinafter, embodiments of the present invention will be
described with reference to the drawings.
[0031] Throughout the drawings, the same or corresponding
components are identified by the same reference symbols and will
not be described in repetition.
Embodiment 1
[0032] FIG. 1 is a cross-sectional view showing a sealed compressor
100. For easier understanding of the description, a direction
parallel to the axis of a main shaft 123 of a shaft 119 will be
referred to as a longitudinal (vertical) direction, while a
direction which is perpendicular to the longitudinal direction will
be referred to as a lateral direction.
[0033] As shown in FIG. 1, the sealed compressor 100 includes a
compressor body 105 and a sealed container 101 accommodating the
compressor body 105. The sealed compressor 100 is a device
configured such that the compressor body 105 causes a working fluid
to be in high-temperature and high-pressure states and the working
fluid is discharged from the sealed container 101. The compressor
body 105 is elastically supported by, for example, a suspension
spring 107. The compressor body 105 includes an electric component
111 and a compression component 117 activated by the electric
component 111.
[0034] The sealed container 101 is filled with lubricating oil 103
and the working fluid. The lubricating oil 103 is used for
lubricating the compression component 117 for actuation and
reserved in the bottom portion of the sealed container 101. As the
working fluid, for example, hydrocarbon-based R600a (isobutane)
which is low in global warming potential, or the like is used. A
suction pipe (not shown) for suctioning the working fluid and a
discharge pipe 104 for discharging the working fluid are connected
to the sealed container 101. The sealed container 101 is provided
with a power supply terminal 109 connected to the electric
component 111.
[0035] The electric component 111 includes a stator 113 and a rotor
115 which rotates with respect to the stator 113, and, for example,
a salient pole concentration winding DC brushless motor is used as
the electric component 111. The stator 113 is configured such that
a plurality of constituents are arranged in a substantially
cylindrical shape. The constituents are configured such that copper
windings are wound around a plurality of teeth of a core
constructed of thin steel plates stacked together, via the
insulating materials. The windings are continuous in all of the
constituents and both ends thereof are connected to the power
supply terminal 109. The rotor 115 has a cylindrical shape and
contains a cylindrical space therein. The rotor 115 is placed
inward relative to the stator 113. As will be described later, the
rotor 115 is divided into two stages in the longitudinal direction
in terms of a difference in inner diameter. The inner diameter of a
boring section 116 formed by boring a hole in the rotor 115, which
is located in the upper stage, is set greater than the inner
diameter of a mounting section 115e in the lower stage. The lower
surface of the rotor 115 is attached with a balance weight 170. The
balance weight 170 is placed on an opposite side of a crank weight
126 with respect to a piston 133.
[0036] The compression component 117 is placed above the electric
component 111 and includes a shaft 119 activated by the electric
component 111. The shaft 119 includes a cylindrical main shaft 123.
The lower portion of the main shaft 123 is inserted into a
cylindrical space of the rotor 115 and shrink-fit to the mounting
section 115e of the rotor 115. The lower end portion of main shaft
123 protrudes downward from the rotor 115 fitted with the lower
portion of the main shaft 123, and is immersed in the lubricating
oil 103 in the bottom portion of the sealed container 101. The main
shaft 123 is provided with an oil feeding mechanism 128. The oil
feeding mechanism 128 includes, for example, a communicating hole
130b formed inside the main shaft 123, a centrifugal pump 130
mounted in the communicating hole 130b, and a spiral groove 127
formed in the outer peripheral surface of the main shaft 123. The
centrifugal pump 130 suctions up the lubricating oil 103 from a
lower end opening 130a of the communicating hole 130b to the upper
end opening of the communicating hole 130b according to the
rotation of the main shaft 123. The communicating hole 130b is
mainly provided inside the lower end portion of the main shaft 123
which protrudes downward from the lower end of the bearing 131. The
lower end opening 130a of the communicating hole 130b opens in the
lower end surface of the main shaft 123, while the upper end
opening of the communicating hole 130b opens in the outer
peripheral surface of the main shaft 123. The upper end opening of
the communicating hole 130b is connected to the lower end of the
spiral groove 127. The spiral groove 127 extends upward in a spiral
form on the outer peripheral surface of the main shaft 123, between
the outer peripheral surface of the main shaft 123 and the inner
peripheral surface of the bearing 131. The upper end of the spiral
groove 127 is connected to a region in the vicinity of sliding
portions of the compression component 117.
[0037] The shaft 119 further includes an eccentric shaft 125
provided above the main shaft 123. The eccentric shaft 125 has a
cylindrical shape and extends in parallel with the main shaft 123
such that the axis of the eccentric shaft 125 does not conform to
the axis of the main shaft 123. The crank weight 126 is mounted to
the upper end of the eccentric shaft 125. The crank weight 126 has,
for example, a substantially sector shape along a plane
perpendicular to the axis of the eccentric shaft 125, and has a
hole in a center portion thereof The upper end portion of the
eccentric shaft 125 is pressed into this hole, and thus the
crankshaft 126 is fixedly fitted to the upper end of the eccentric
shaft 125.
[0038] The shaft 119 further includes a flange 121 between the main
shaft 123 and the eccentric shaft 125. The lower surface of the
flange 121 is connected to the upper end of the main shaft 123. The
upper surface of the flange 121 is connected to the lower end of
the eccentric shaft 125. The flange 121 joins the main shaft 123
and the eccentric shaft 125 to each other. The flange 121 has, for
example, a substantially sector form around the eccentric shaft 125
on a plane perpendicular to the axis of the eccentric shaft 125.
The main shaft 123 is connected to the center portion of the flange
121. A portion of the flange 121, which has an arc-shaped portion
of a substantially sector form, protrudes in a direction opposite
to the eccentric shaft 125 from the main shaft 123. A bearing 131
of a cylinder block 129 is placed below the flange 121.
[0039] The cylinder block 129 includes the bearing 131 extending in
the longitudinal direction and a cylinder 137 extending in the
lateral direction. The bearing 131 has a substantially cylindrical
shape. The lower portion of the bearing 131 is inserted into the
cylindrical space of the boring section 116 of the rotor 115. The
lower end of the bearing 131 is fixedly fitted to the mounting
section 115e in contact state. In this way, the lower portion of
the bearing 131 is accommodated within the boring section 116, and
the boring section 116 and the bearing 131 overlap with each other.
This can reduce the height of the boring section 116 and of the
bearing 131 without reducing the length of the bearing 131. As a
result, the height of the sealed container 101 can be lessened.
[0040] The bearing 131 has therein a cylindrical through-hole
extending in the longitudinal direction. The main shaft 123 is
rotatably inserted into the through-hole. The bearing 131 radially
supports the main shaft 123 on its inner peripheral surface. This
provides a configuration of a cantilever bearing in which the shaft
119 is supported only by the bearing 131. The lower end portion of
the main shaft 123 which is inserted into the through-hole
protrudes downward from the lower end of the bearing 131 and is
fixedly fitted to the mounting section 115e of the rotor 115.
[0041] The bearing 131 bears on a thrust surface 196 as will be
described later, a longitudinal load applied to the flange 121 via
a thrust ball bearing 180. The longitudinal load applied to the
flange 121 corresponds to a load which is a sum of the load of the
shaft 119, the load of the crank weight 126 and the rotor 115
mounted to the shaft 119, and the load of the balance weight 170
mounted to the rotor 115.
[0042] The cylinder 137 has therein a cylindrical space extending
in the lateral direction. A valve plate 139 is attached to the end
surface of the cylinder 137. The valve plate 139 closes one end of
the lateral cylindrical space. Thereby, a compression chamber 141
is formed inside the cylinder 137. A cylinder head 153 is fastened
to the end surface of the cylinder 137 so as to cover the valve
plate 139, and a suction muffler 155 is mounted between the valve
plate 139 and the cylinder head 153. The suction muffler 155 is
molded using a resin such as PBT (polybutylene terephthalate), and
its internal muffling space can reduce the noise generated by the
working fluid flowing from the suction pipe.
[0043] One end portion of the piston 133 is reciprocatingly
inserted into the compression chamber 141 inside the cylinder 137,
while the other end portion of the piston 133 is connected to a
coupling section 143. The eccentric shaft 125 is coupled to the
piston 133 in such a manner that a piston pin 135 mounted to the
piston 133 is fitted into the hole provided in one end portion of
the coupling section 143 and the eccentric shaft 125 is fitted into
a hole provided in the other end portion of the coupling section
143.
[0044] FIG. 2 is an enlarged view showing a region A of FIG. 1. As
shown in FIG. 2, the bearing 131 of the cylinder block 129 has the
annular thrust surface 196 on the upper surface thereof The thrust
surface 196 extends in a direction perpendicular to the center axis
of the bearing 131. The center of the thrust surface 196 conforms
to the center axis of the bearing 131. The inner diameter of the
thrust surface 196 is greater than the inner diameter of the
bearing 131. An annular extending section 194 is provided between
the inner circle of the thrust surface 196 and the inner peripheral
surface of the bearing 131. The annular extending section 194 has a
cylindrical shape extending in the longitudinal direction. The axis
of the annular extending section 194 conforms to the center axis of
the bearing 131. The inner peripheral surface of the annular
extending section 194 is continuous with the inner peripheral
surface of the body of the bearing 131 and faces the outer
peripheral surface of the main shaft 123.
[0045] The thrust ball bearing 180 is placed on the outer side of
the annular extending section 194 of the bearing 131, between the
flange 121 of the shaft 119 and the thrust surface 196 of the
bearing 131. The thrust ball bearing 180 has a plurality of balls
186. The balls 186 are rolling elements. The plurality of balls 186
are equal in size to each other. The balls 186 are held in a cage
188. Instead of the thrust ball bearing 180, other ball bearings
such as a roller bearing may be used.
[0046] The cage 188 is an annular flat plate member and is made of
a resin material such as polyamide. The cage 188 has an inner
peripheral surface which is in contact with the outer peripheral
surface of the annular extending section 194 and includes a
plurality holes inside thereof The plurality of holes are arranged
in a circumferential direction thereof The balls 166 are rollably
stored in the holes, respectively. The height of the cage 188 is
smaller than the diameter of the balls 186. The balls 186 protrude
in opposite directions of the longitudinal direction, from the cage
188. The balls 186 are sandwiched between an upper race 182 and a
lower race 190 in the longitudinal direction, and held therein.
[0047] The upper race 182 and the lower race 190 are annular flat
plate members, and are made of a metal, preferably, a spring steel
or the like which has been subjected to a thermal treatment. The
upper and lower surfaces of each of the races 182, 190 are parallel
to each other and are formed to be flat. The upper race 182 is
placed above the balls 186 and the cage 188. The upper surface of
the upper race 182 is in contact with the lower surface of the
flange 121, while the lower surface of the upper race 182 is in
contact with the balls 186. The lower race 190 is placed below the
balls 186 and the cage 188. The upper surface of the lower race 190
is in contact with the balls 186, while the lower surface of the
lower race 190 is in contact with the upper surface of a support
member 192. The support member 192 is an annular member having an
elasticity. The upper surface of the support member 192 is in
contact with the lower surface of the lower race 190, while the
lower surface of the support member 192 is in contact with the
thrust surface 196 of the bearing 131.
[0048] FIG. 3A is a cross-sectional view of the rotor 115, which is
taken along a plane perpendicular to the axis of the rotor 115.
FIG. 3B is a cross-sectional view of the rotor 115 which is taken
along broken lines B-B of FIG. 3A. As shown in FIGS. 3A and 3B, the
rotor 115 includes an upper end plate 115c, a lower end plate 115d,
and a substantially cylindrical core 115a sandwiched between the
upper end plate 115c and the lower end plate 115d. The core 115a
includes a plurality of thin annular electromagnetic steel plates
which are stacked together. Each of the electromagnetic steel
plates has a plurality of (three in the present embodiment)
circular holes for caulking pins 172 and a plurality of (six in the
present embodiment) arc-shaped holes for permanent magnets 115b.
The permanent magnets 115b are arc-shaped column members, and their
height is set substantially equal to the height of the core 115a.
The end plates 115c, 115d are thin annular plates and have circular
holes for the caulking pins 172, respectively.
[0049] The caulking pins 172 are inserted into the circular holes
of the lower end plate 115d, respectively. The core 115a is placed
on the lower end plate 115d so that the caulking pins 172 are
inserted into the circular-holes, respectively. Then, the permanent
magnets 115b are inserted into the arc-shaped holes of the core
115a, respectively. The upper end plate 115c is placed on the core
115a. The upper end plate 115c, the lower end plate 115d, and the
core 115a are fastened together by the caulking pins 172 such that
the upper end plate 115c, the lower end plate 115d, and the core
115a adhere to each other. Finally, the permanent magnets 115b (to
be precise, magnet elements before being magnetized) accommodated
in the core 115a are magnetized, thereby constructing the rotor
115.
[0050] As described above, the rotor 115 is divided in the
longitudinal direction according to a difference in the inner
diameter, into the boring section 116 in the upper stage and the
mounting section 115e in the lower stage. The boring section 116
and the mounting section 115e are identical to each other except
for the inner diameter between the steel plates constituting the
boring section 116 and the steel plates constituting the mounting
section 115e. The steel plates constituting the boring section 116
and the steel plates constituting the mounting section 115e are
fastened together by using the caulking pins 172, and thus the
boring section 116 and the mounting section 115e are unitarily
constructed.
[0051] As shown in FIG. 3B, the inner diameter R1 of the boring
section 116 is set greater than the inner diameter R2 of the
mounting section 115e. As shown in FIG. 1, the inner diameter R1 of
the boring section 116 is set slightly greater than the outer
diameter of the lower portion of the bearing 131. This allows the
lower portion of the bearing 131 to be inserted into the
cylindrical space of the boring section 116. Since the boring
section 116 and the bearing 131 overlap with each other when viewed
from a side, the height of the boring section 116 and of the
bearing 131 can be lessened without reducing the length of the
bearing 131. As a result, the height of the sealed container 101
can be lessened.
[0052] The inner diameter R2 of the mounting section 115e is set
smaller than the outer diameter of the lower portion of the bearing
131 and substantially equal to the outer diameter of the lower
portion of the main shaft 123 of the shaft 119. The lower portion
of the main shaft 123 penetrating the bearing 131 and protruding
downward is inserted into the cylindrical space of the mounting
section 115e and fixedly fitted to the inner peripheral surface
defining the cylindrical space.
[0053] As shown in FIG. 3B, the ratio of the height M of the boring
section 116 with respect to the height L of the core 115a of the
rotor 115 is equal to or greater than 70%, while the ratio of the
height N of the mounting section 115e with respect to the height L
of the core 115a of the rotor 115 is equal to or less than 30%. For
example, the boring section 116 with the height M of 30 mm and the
mounting section 115e with the height N of 6 mm are provided to
correspond to the core 115a with the height L of 36 mm In this
case, the ratio of the height M of the boring section 116 with
respect to the height L of the core 115a is 83%. As should be
understood, the ratio of the longitudinal dimension the boring
section 116 with respect to the longitudinal dimension of the core
115a is very large. This allows the sealed container 101 to be
thinned On the other hand, the ratio of the longitudinal dimension
of the mounting section 115e with respect to the longitudinal
dimension of the core 115a is very small, and the mounting section
115e and the main shaft 123 are fixedly fitted to each other in a
small range. In addition, the core 115a has a stacked structure in
which the plurality of steel plates are stacked together in the
longitudinal direction. Therefore, the lateral stiffness of the
core 115a to which the main shaft 123 is fixedly fitted is
relatively low. An undesirable effect on the fitted portions by the
inclination of the main shaft 123 is mitigated by the balance
weight 170.
[0054] FIG. 4 is a view showing an external appearance of the rotor
115, when viewed from a lower side. As shown in FIGS. 3B and 4, the
balance weight 170 is formed of a thin metal flat plate and is
placed on the lower end plate 115d of the rotor 115. The mass of
the balance weight 170 is, as will be described later, determined
by the forces and moments applied to the shaft 119. The mass of the
balance weight 170 is smaller than the mass of the crank weight
126, and is set to, for example, 1/8 of the mass of the crank
weight 126.
[0055] The balance weight 170 has a substantially arc-shape on a
plane parallel to the lower surface of the rotor 115. The inner
curve of the arc-shape of the balance weight 170 conforms to the
inner periphery of the lower end plate 115d, while the outer curve
of the arc-shape of the balance weight 170 conforms to the outer
periphery of the lower end plate 115d and the outer periphery of
the core 115a. The balance weight 170 is provided to be symmetric
with respect to a line parallel to the trajectory of the
reciprocation motion of the piston 133 (FIG. 1), as indicated by
one-dotted line C of FIG. 4. The balance weight 170 has two
circular holes into which the caulking pins 172 are inserted,
respectively. The two circular holes are placed to be symmetric
with respect to one-dotted line C. The caulking pins 172 inserted
into the circular holes allow the rotor 115 to be assembled and the
balance weight 170 to be fastened to the lower surface of the rotor
115.
[0056] As described above, since the location at which the balance
weight 170 is mounted to the rotor 115 and the location at which
the rotor 115 and the shaft 119 are fixedly fitted to each other
are close, the deformation such as a deflection of the rotor 115
can be prevented.
[0057] Next, the operation of the sealed compressor 100 as
described above will be described. As shown in FIG. 1, a power
supply (not shown) such as the power supply utility provided
outside the sealed container 101 is connected to the power supply
terminal 109 of the sealed container 101. Thus, AC power is
supplied from the outside power supply to the electric component
111. In the electric component 111, the rotor 115 rotates by a
magnetic field generated in the stator 113. Concurrently, the main
shaft 123 of the shaft 119 fixedly fitted to the rotor 115 rotates
and the eccentric shaft 125 coupled to the main shaft 123 via the
flange 121 rotates eccentrically.
[0058] The coupling section 143 converts the eccentric rotation
motion of the eccentric shaft 125 into a linear reciprocation
motion. The piston 133 reciprocates inside the compression chamber
141 of the cylinder 137. According to the motion of the piston 133,
the volume of the compression chamber 141 closed by the piston 133
changes. When the piston 133 moves in the direction for increasing
the volume of the interior of the compression chamber 141, the
working fluid flows from the suction pipe into the sealed container
101 and is suctioned into the compression chamber 141 via the
suction muffler 155. On the other hand, when the piston 133 moves
in the direction for reducing the volume of the interior of the
compression chamber 141, the working fluid is compressed in the
compression chamber 141 and then the working fluid in
high-temperature and high-pressure states is sent from the sealed
container 101 to a refrigeration cycle (not shown) via the
discharge pipe 104 or the like.
[0059] According to the rotation of the main shaft 123, the
lubricating oil 103 is suctioned up by the centrifugal pump 130
through the communicating hole 130b. The lubricating oil 103 flows
through the centrifugal pump 130 and moves upward along and on the
inner wall of the communicating hole 130b. The lubricating oil 103
reaches the upper end of the communicating hole 130 and then flows
to the lower end of the spiral groove 127 on the surface of the
main shaft 123. When the main shaft 123 rotates within the bearing
131, the lubricating oil 103 in the spiral groove 127 moves upward
because of its viscosity between the outer peripheral surface of
the main shaft 123 and the inner peripheral surface of the bearing
131, and lubricates sliding sections between them. Furthermore, the
lubricating oil 103 is fed to the sliding sections of the
compression component 117 through the eccentric shaft 125, the
coupling section 143, or the like, to lubricate the sliding
sections.
[0060] Since the lower portion of the bearing 131 is inserted into
the boring section 116 of the rotor 115, the lower end portion of
the main shaft 123 protruding downward from the lower end of the
bearing 131 is short in length. The communicating hole 130b
provided inside the lower end portion of the main shaft 123 is also
short in length, and the lifting range of the centrifugal pump 130
to feed the lubricating oil 103 through the communicating hole 130b
is reduced. Because of this, even when the rotational frequency of
the main shaft 123 is low or the liquid level of the lubricating
oil 103 is lowered temporarily, the centrifugal pump 130 can raise
the lubricating oil 103 to the spiral groove 127 via the
communicating hole 130b. This makes it possible to sufficiently
feed the lubricating oil 103 to the sliding sections. As a result,
a reliability of the sealed compressor 100 can be improved.
[0061] When the flange section 121 rotates, the balls 186 of the
thrust ball bearing 180 roll while point-contacting the upper race
182 and the lower race 190. This makes it possible to reduce a
friction between the thrust surface 196 of the bearing 131 and the
lower surface of the flange 121 of the shaft 119. Because of this,
a driving power loss due to the friction can be reduced, and the
mechanical efficiency of the sealed compressor 100 can be
improved.
[0062] On the other hand, in the thrust ball bearing 180, the balls
186 are in point-contact with the races 182, 190. This causes a
surface pressure to increase in a localized region. Therefore, it
is necessary to feed the lubricating oil 103 to the thrust ball
bearing 180. Regarding this, due to a reduction of the length of
the communicating hole 130b as described above, the lubricating oil
103 is sufficiently fed to the thrust ball bearing 180. Therefore,
the thrust ball bearing 180 can be lubricated smoothly, and hence
the durability of the thrust ball bearing 180 can be improved.
[0063] Next, the forces and moments applied to the shaft 119, in
association with the balance weight 170, during the operation of
the sealed compressor 100 will be described. FIG. 5 is a view
schematically showing the forces applied to the shaft 119. As shown
in FIG. 5, when the piston 133 reciprocates, an inertia force is
generated in the piston 133. When the eccentric shaft 125
eccentrically rotates, a centrifugal force is generated in the
eccentric shaft 125. Since the reciprocation motion of the piston
133 and the eccentric rotation motion of the eccentric shaft 125
are associated with each other, the inertia force of the piston 133
and the centrifugal force of the eccentric shaft 125 are applied to
the shaft 119 in the same direction. For example, when the piston
133 moves in the direction for increasing the internal volume of
the compression chamber 141 (FIG. 1), the inertia force of the
piston 133 and the centrifugal force of the eccentric shaft 125 are
applied to the shaft 119 in a direction of an arrow FA of FIG. 5.
On the other hand, when the piston 133 moves in the direction for
reducing the internal volume of the compression chamber 141 (FIG.
1), the inertia force of the piston 133 and the centrifugal force
of the eccentric shaft 125 are applied to the shaft 119 in a
direction which is opposite to the arrow FA of FIG. 5. This causes
an unbalanced component FA which is a sum of the inertia force of
the piston 133 and the centrifugal force of the eccentric shaft 125
to be applied to the shaft 119 in the direction in which the piston
133 reciprocates.
[0064] The crank weight 126 is mounted to the upper end of the
eccentric shaft 125, and is positioned in a direction opposite to
the eccentric shaft 125 with respect to the main shaft 123. The
crank weight 126 rotates around the same rotational axis as that of
the eccentric shaft 125 in association with the rotation of the
eccentric shaft 125. For this reason, in the direction in which the
piston 133 reciprocates, the centrifugal force FB of the crank
weight 126 is applied to the shaft 119 in a direction opposite to
the unbalanced component FA.
[0065] The balance weight 170 is mounted to the lower surface of
the rotor 115 and is positioned in a direction opposite to the
eccentric shaft 125 with respect to the main shaft 123. The balance
weight 170 rotates around the same rotational axis as that of the
main shaft 123 in association with the rotation of the main shaft
123. For this reason, in the direction in which the piston 133
reciprocates, the centrifugal force FC of the balance weight 170 is
applied to the shaft 119 via the rotor 115 in a direction opposite
to the direction of the unbalanced component FA and the same
direction as that of the centrifugal force FB of the crank weight
126.
[0066] The mass of the crank weight 126 and the mass of the balance
weight 170 are set so that a difference between the unbalanced
component FA and the sum of the centrifugal force FB of the crank
weight 126 and the centrifugal force FC of the balance weight 170
is smaller, and preferably zero. To this end, the loads FA, FB, FC
are well balanced.
[0067] When the vertical distance (height) from the balance weight
170 to the center of the piston 133 is LAC, and the height from the
center of the piston 133 to the crank weight 126 is LAB, a
rotational moment M at the center of the piston 133 is expressed as
M=FB.times.LAB-FC.times.LAC. The centrifugal force FB of the crank
weight 126 and the centrifugal force FC of the balance weight 170
are set so that the moment FB.times.LAB and the moment FC.times.LAC
cancel each other, and the rotational moment M is smaller and
preferably zero. This allows the moments to be balanced as well as
the forces applied to the shaft 119. This can suppress the
vibration of the runout of the shaft 119 in an inclined state.
Therefore, it becomes possible to prevent a situation in which the
vibration of the rotor 115 is amplified by the vibration of the
shaft 119, and to further reduce the noise and the vibration in the
sealed compressor 100.
[0068] In a state in which the moment components are well balanced
as described above, since the balance weight 170 is more distant
from the piston 133 than the crank weight 126, the centrifugal
force FC of the balance weight 170 is smaller than the centrifugal
force FB of the crank weight 126. For example, in a case where a
point of support is present in the center height of the piston 133,
the mass of the balance weight 170 is 1/8 of the mass of the crank
weight 126, if the height LAC is eight times as large as the height
LAB. This significantly reduces the mass of the balance weight 170
mounted to the rotor 115, and also reduces the centrifugal force FC
of the balance weight 170 which is applied to the rotor 115 even
during a high-speed rotation. Therefore, even when the ratio of the
height of the mounting section 115e with respect to the height of
the rotor 115 is small, the rotor 115 and the main shaft 123 are
fixedly fitted to each other in a smaller range, and the stiffness
of the fitted portion is relatively low, the force applied to the
fitted portions is small. The lateral deflection of the core 115a
which is the stack of the steel plates, due to this force, can be
prevented. As a result, it becomes possible to prevent a situation
in which the shaft 119 vibrates by the runout due to the deformed
rotor 115, and the noise is generated due to a change in a gap
between the stator 113 and the rotor 115.
[0069] Especially, the balance weight 170 is mounted to the lower
surface of the rotor 115 and is positioned to be most distant from
the piston 133 among the constituents of the rotor 115. This
reduces the mass of the balance weight 170 mounted to the lower
surface as compared to a case where the balance weight 170 is
mounted to another location, such as the upper surface of the rotor
115. Therefore, a bending moment applied to the mounting section
115e of the rotor 115 can be reduced, and a deflection of the rotor
115 can be prevented. As a result, the vibration and the noise
which would be caused by the deformation of the rotor 115 can be
further reduced.
[0070] As shown in FIG. 1, the height of the boring section 116 of
the rotor 115 is set greater and the height which is a sum of the
height of the rotor 115 and the height of the bearing 131 is set
smaller. This reduces a distance between the piston 133 located
above the bearing 131 and a portion 101a in which the suspension
spring 107 supporting the compressor body 105 such as the piston
133 is fitted to the sealed container 101.
[0071] The vibration of the piston 133 which is a vibration source
is more likely to be transmitted to outside the sealed compressor
100 via the suspension spring 107 and the fitted portions 101a of
the sealed container 101. In contrast, in the sealed compressor 100
of the present embodiment, by using the balance weight 170 in
addition to the crank weight 126, the noise and the vibration in
the sealed compressor 100 can be mitigated. As a result, the noise
and the vibration which would be transmitted to outside the sealed
compressor 100 can be lessened.
[0072] Moreover, since the vibration of the runout of the shaft
119, and the vibration generated in the sealed compressor 100 can
be mitigated, it becomes possible to prevent a situation in which a
biased load is applied to the balls 186 of the thrust ball bearing
180. As a result, a durability of the thrust ball bearing 180 can
be improved.
Embodiment 2
[0073] The configuration of a sealed compressor 100 according to
Embodiment 2 is substantially the same as that of the sealed
compressor 100 according to Embodiment 1 except that the location
of a balance weight 270 of Embodiment 2 is different from the
location of the balance weight 170 of Embodiment 1. FIG. 6 is a
cross-sectional view showing the sealed compressor 100 according to
Embodiment 2.
[0074] As shown in FIG. 6, the balance weight 270 is mounted to the
upper surface of the rotor 115 and placed on an opposite side of
the crank weight 126 with respect to the piston 133. The mass of
the balance weight 270 is, as will be described later, determined
by the forces and moments applied to the shaft 119. The mass of the
balance weight 270 is smaller than the mass of the crank weight
126, and is set to, for example, 1/5 of the mass of the crank
weight 126.
[0075] Next, the forces and moments applied to the shaft 119, in
association with the balance weight 270, during the operation of
the sealed compressor 100, will be described. FIG. 7 is a view
schematically showing the forces applied to the shaft 119. As shown
in FIG. 7 in the direction in which the piston 133 reciprocates,
the shaft 119 is applied with the unbalanced component FA which is
a sum of the inertia force generated in the piston 133 by the
reciprocation motion of the piston 133 and the centrifugal force
generated in the eccentric shaft 125 by the eccentric rotation
motion of the eccentric shaft 125. The centrifugal force FB of the
crank weight 126 is applied to the shaft 119 in the direction
opposite to the direction of the unbalanced component FA.
[0076] Further, the balance weight 270 is mounted to the upper
surface of the rotor 115, and is positioned at an opposite side of
the eccentric shaft 125 with respect to the main shaft 123. The
balance weight 270 rotates around the same rotational axis as that
of the main shaft 123 in association with the rotation of the main
shaft 123. For this reason, in the direction in which the piston
133 reciprocates, the centrifugal force FD of the balance weight
270 is applied to the shaft 119 via the rotor 115 in a direction
opposite to the direction of the unbalanced component FA and in the
same direction as the direction of the centrifugal force FB of the
crank weight 126.
[0077] The mass of the crank weight 126 and the mass of the balance
weight 170 are set so that there is a balance between the
unbalanced component FA and the sum of the centrifugal force FB of
the crank weight 126 and the centrifugal force FC of the balance
weight 170. When the vertical distance (height) from the balance
weight 270 to the center of the piston 133 is LAD, the rotational
moment M at the center of the piston 133 is expressed as
M=FB.times.LAB-FD.times.LAD. The centrifugal force FB of the crank
weight 126 and the centrifugal force FD of the balance weight 270
are set so that the moment FB.times.LAB and the moment FD.times.LAD
cancel each other, and the rotational moment M is zero. Thereby,
the forces applied to the shaft 119 are balanced, and the moments
applied to the shaft 119 are balanced. This can prevent the
vibration of the runout of shaft 119. Therefore, it becomes
possible to further reduce the noise and the vibration in the
sealed compressor 100.
[0078] In a state in which the moments are well balanced as
described above, since the balance weight 270 is more distant from
the piston 133 than the crank weight 126, the centrifugal force FD
of the balance weight 270 becomes smaller than the centrifugal
force FB of the crank weight 126. This can prevent the deformation
of the rotor 115 and the vibration of the runout of the shaft 119,
and hence prevent the vibration and the noise in the sealed
compressor 100. In addition, as shown in FIG. 7, it becomes
possible to reduce the vibration and the noise transmitted from the
sealed container 101 to outside the sealed compressor 100 via the
suspension spring 107.
[0079] Moreover, the balance weight 270 is placed above the rotor
115 and is distant from the liquid level of the lubricating oil 103
reserved in the bottom portion of the sealed container 101 as shown
in FIG. 6. In this structure, when the rotor 115 rotates, it
becomes possible to prevent a situation in which the balance weight
270 is immersed in the lubricating oil 103 and stirs the
lubricating oil 103. Even if the working fluid is dissolved into
the lubricating oil 103, it becomes possible to prevent a situation
in which the working fluid generates bubbles in the lubricating oil
103 due to the stirring by the balance weight 270. As a result, it
becomes possible to prevent a situation in which the bubbles of the
working fluid, containing the lubricating oil 103, are suctioned
into the compression chamber 141, are compressed by the piston 133
in the interior of the compression chamber 141, and generate the
noise.
Embodiment 3
[0080] FIG. 8 is a cross-sectional view schematically showing a
refrigerator 200 according to Embodiment 3. As shown in FIG. 8, the
refrigerator 200 includes a heat-insulating casing 202 having a
heat-insulating space inside thereof and doors attached to the
heat-insulating casing 202 to open and close the heat-insulating
space. The surface of the heat-insulating casing 202 attached with
the doors is a front surface and the opposite surface is a back
surface.
[0081] The heat-insulating casing 202 has a substantially
rectangular parallelepiped shape which is elongated in the
longitudinal direction. The heat-insulating casing 202 includes a
heating insulating wall defining the heat-insulating space inside
thereof, and partition plates for partitioning the heat-insulating
space into a plurality of (five in the present embodiment)
heat-insulating space sections 210, 212, 214, 216, 218. The five
heat-insulating space sections 210, 212, 214, 216, 218 are
vertically separated as four stages. The heat-insulating space
section in the second stage from the upper is separated into two
parts in a rightward or leftward direction. For example, the
heat-insulating space section in the first stage from the upper is
used as a chill room 210, the two heat-insulating space sections in
the second stage from the upper are used as a switch room 212 and
an ice making room 214, the heat-insulating space section in the
third stage from the upper is used as a vegetable room 216, and the
heat-insulating space section in the fourth stage from the upper is
used as a freezing room (compartment) 218. The heat-insulating
space sections 210, 212, 214, 216, 218 are connected to each other
via ducts (not shown), and dampers are provided inside the ducts.
The ducts allow air communication among the respective
heat-insulating space sections. The flow rate of the air is
adjusted by the dampers. The heat-insulating space sections 210,
212, 214, 216, 218 are partially or entirely provided with
temperature sensors (not shown).
[0082] The heat-insulating casing 202 includes an inner casing 204
and an outer casing 206 provided outside the inner casing 204. The
inner casing 204 is manufactured by vacuum-molding using a resin
such as ABS. The inner casing 204 constitutes the inner surface of
the heat-insulating wall defining the heat-insulating space and the
partition plates for partitioning the heat-insulating space. The
outer casing 206 is made of metal such as a pre-coat steel plate,
and constitutes the outer surface of the heat-insulating wall. A
heat-insulating material 208 is unitarily foamed and filled in a
space formed between the inner casing 204 and the outer casing 206,
thus constructing the heat-insulating casing 202. In this way, the
heat-insulating wall and the partition plates are formed together
and unitarily. As the heat-insulating material 208, for example,
foamed plastic such as a hard urethane foam, a phenol foam, or a
styrene foam is used. As this foamed material, for example, a
hydrocarbon-based cyclopentane is used to prevent global
warning.
[0083] The heat-insulating casing 202 is provided with a recess 230
formed by denting a part of its back surface and its upper surface.
The sealed compressor 100 is elastically supported in the recess
230. A condenser (not shown) and a drier (not shown) for removing a
moisture are placed on the side surface or the like of the
heat-insulating casing 202. In addition, a capillary 234 which is a
pressure-reducing unit and an evaporator 238 are placed on the back
surface of the heat-insulating casing 202. A cooling fan 236 and
the evaporator 238 are placed on the back surface of the vegetable
room 216 and the back surface of the freezing room 218 in the
interior of the heat-insulating casing 202. The sealed compressor
100, the condenser, the capillary 234 and the evaporator 238 are
connected together in an annular shape by a pipe 240, thus
constituting a refrigeration cycle. Furthermore, the
heat-insulating casing 202 is provided with a controller (not
shown). The temperature sensors placed in the heat-insulating space
sections are connected to the controller. In addition, the sealed
compressor 100, the condenser, the drier, the capillary 234, the
evaporator 238, the cooling fan 236 and the evaporator 238 are
connected to the controller. The controller controls these
components based on the detection values of the temperature
sensors.
[0084] In the present embodiment, five doors 220, 222, 224, 226,
228 are attached to the heat-insulating casing 202 such that the
doors 220, 222, 224, 226, 228 can open and close the front surfaces
of the heat-insulating space sections 210, 212, 214, 216, 218 in
the interior of the heat-insulating casing 202. The chill room 210
is provided with a rotatable door 220, while the switch room 212,
the ice making room 214, the vegetable room 216, and the freezing
room 218 are provided with drawing doors 222, 224, 226, 228,
respectively. The rotatable door 220 and the drawing doors 222,
224, 226, 228 are each constructed by bonding a decorative sheet to
the heat-insulating material such as foamed polystyrene. Between
the doors 220, 222, 224, 226, 228 and the heat-insulating casing
202, gaskets are placed, which can keep the heat-insulating space
sections 210, 212, 214, 216, 218 in a sealed state.
[0085] Next, the operation of the refrigeration cycle of the above
described refrigerator 200 will be described. The controller starts
and stops the cooling operation based on the detection signals from
the temperature sensors. Upon the start of the cooling operation,
the working fluid is compressed by the reciprocation motion of the
piston 133 (FIG. 1) in the sealed compressor 100, and the working
fluid in the high-temperature and high-pressure states is sent from
the discharge pipe 104 (FIG. 1) to the refrigeration cycle through
the pipe 240. The gaseous working fluid in the high-temperature and
high-pressure states radiates heat in the condenser, and is
condensed into a liquid. The liquid working fluid is
pressure-reduced in the capillary 234 to be turned into
low-temperature and low-pressure states, and reaches the evaporator
238. The cooling fan 236 operates to cause the air in the vegetable
room 216 and the freezing room 218 to migrate, and this air
exchanges heat with the working fluid in the low-temperature state
in the evaporator 238. The working fluid raises its temperature and
is evaporated. The evaporated working fluid is returned to the
sealed compressor 100 through the pipe 240. In contrast, the cooled
air is delivered to the heat-insulating space sections 210, 212,
214 via the ducts. At this time, the flow rates of the cooled air
delivered to the heat-insulating space sections 210, 212, 214 are
adjusted via the dampers, so that the heat-insulating space
sections 210, 212, 214, 216, 218 are adjusted at proper
temperatures, respectively.
[0086] For example, the temperature of the chill room 210 is a
temperature at which stuff are not frozen and preserved in a
chilled state, for example, 1 to 5 degrees C. The switch room 212
is set to a temperature which can be changed by the user, and is
placed at the set temperature. This set temperature may be set to,
for example, a specified temperature in a range from a temperature
zone of the freezing room 218 to a temperature zone of the
vegetable room 216. The ice making room 214 includes an automatic
ice making device (not shown), and is configured to automatically
make ice and reserve the ice. To preserve the ice, the ice making
room 214 is adjusted at a temperature which is relatively higher
than the freezing temperature zone, for example, minus 18 to minus
10 degrees C. The vegetable room 216 is adjusted at a temperature
which is equal to or slightly higher than that of the chill room
210, for example, 2 to 7 degrees C. As this temperature is lower
and is not a freezing temperature, the freshness of the vegetables
can be kept for a long time. The freezing room 218 is normally
adjusted at minus 22 to minus 18 degrees C. to preserve stuff in a
frozen state. However, to preserve the stuff in a more frozen
state, for example, the freezing room 218 may be adjusted at minus
30 to minus 25 degrees C.
[0087] The refrigerator 200 incorporates the sealed compressor 100
provided with the crank weight 126 and the balance weight 170, 270
of FIGS. 1 and 6. In this case, the forces and rotational moments
which cannot be cancelled merely by the crank weight 126 are
cancelled by the balance weight 170, 270. Since the vibration of
the sealed compressor 100 can be mitigated during the operation,
the vibration and noise in the refrigerator 200 can be reduced.
[0088] Since the rotor 115 and the bearing 131 overlap with each
other because of the boring section 116 of FIGS. 1 and 6, the
height of the sealed compressor 100 can be lessened. Because of
this, the depth of the recess 230 on the heat-insulating casing 202
is allowed to be small, which can increase the size of the
heat-insulating space in the interior of the refrigerator 200, and
the thickness of the heat-insulating material 208. Therefore, the
refrigerator 200 can be used more easily and its heat-insulating
capability can be improved.
[0089] Since the partition plates and the heat insulating wall in
the heat-insulating casing 202 are constructed by unitarily filling
the foamed material, a cost reduction and improvement of a heat
insulating capability can be achieved. Since the partition plates
manufactured in this way have a heat-insulating capability which is
about twice as high as that of the heat-insulating member of the
foamed polystyrene, the partition plates can be thinned, and
correspondingly the heat-insulating space can be expanded.
Other Embodiments
[0090] Although in Embodiment 3, the sealed compressor 100 is
incorporated into the refrigerator 200, it may be used in devices
using refrigeration cycles (heat pump cycles) such as air
conditioners, automatic dispensers, other freezing devices, and
further, industrial compressors such as air compressors.
[0091] Although in Embodiment 3, the partition plates and the
heat-insulating wall are formed unitarily in the heat-insulating
casing 202, they may be formed separately.
[0092] The above embodiments may be combined so long as they do not
exclude each other.
[0093] Numeral modifications and alternative embodiments of the
present invention will be apparent to those skilled in the art in
view of the foregoing description. Accordingly, the description is
to be construed as illustrative only, and is provided for the
purpose of teaching those skilled in the art the best mode of
carrying out the invention. The details of the structure and/or
function may be varied substantially without departing from the
spirit of the invention.
INDUSTRIAL APPLICABILITY
[0094] As described above, a sealed compressor and a refrigerator
including the sealed compressor of the present invention are useful
as a thinned sealed compressor which is capable of reducing a
vibration and a noise, and a refrigerator including the thinned
sealed compressor.
REFERENCE SIGNS LIST
[0095] 100 sealed compressor
[0096] 101 sealed container
[0097] 111 electric component
[0098] 113 stator
[0099] 115 rotor
[0100] 115e mounting section (lower section)
[0101] 116 boring section (upper section)
[0102] 117 compression component
[0103] 119 shaft
[0104] 123 main shaft
[0105] 125 eccentric shaft
[0106] 126 crank weight
[0107] 129 cylinder block
[0108] 131 bearing
[0109] 133 piston
[0110] 137 cylinder
[0111] 141 compression chamber
[0112] 170 balance weight
[0113] 172 caulking pin
[0114] 180 thrust ball bearing
[0115] 200 refrigerator
[0116] 270 balance weight
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