U.S. patent application number 15/113272 was filed with the patent office on 2017-01-12 for sealed compressor and refrigeration device.
The applicant listed for this patent is PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD.. Invention is credited to KO INAGAKI, MASANORI KOBAYASHI.
Application Number | 20170009758 15/113272 |
Document ID | / |
Family ID | 54008522 |
Filed Date | 2017-01-12 |
United States Patent
Application |
20170009758 |
Kind Code |
A1 |
KOBAYASHI; MASANORI ; et
al. |
January 12, 2017 |
SEALED COMPRESSOR AND REFRIGERATION DEVICE
Abstract
A sealed compressor includes sealed container that contains
electric element, and compression element driven by electric
element. Compression element includes shaft that includes main
shaft portion, and eccentric shaft portion integrally movable with
main shaft portion, and bearing portion that supports main shaft
portion of shaft to constitute a cantilever bearing. Compression
element further includes cylinder that compresses gas, piston
reciprocatively inserted into cylinder, and connecting rod that
connects eccentric shaft portion with piston.
Inventors: |
KOBAYASHI; MASANORI; (Shiga,
JP) ; INAGAKI; KO; (Shiga, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO., LTD. |
Osaka-shi |
|
JP |
|
|
Family ID: |
54008522 |
Appl. No.: |
15/113272 |
Filed: |
February 13, 2015 |
PCT Filed: |
February 13, 2015 |
PCT NO: |
PCT/JP2015/000651 |
371 Date: |
July 21, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F04B 35/04 20130101;
F04B 15/00 20130101; F04B 17/03 20130101; F04B 39/0022 20130101;
F04B 39/0094 20130101; F04B 39/12 20130101; F04B 39/0005 20130101;
F25B 31/023 20130101 |
International
Class: |
F04B 39/00 20060101
F04B039/00; F25B 31/02 20060101 F25B031/02; F04B 35/04 20060101
F04B035/04; F04B 39/12 20060101 F04B039/12; F04B 15/00 20060101
F04B015/00; F04B 17/03 20060101 F04B017/03 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 25, 2014 |
JP |
2014-033746 |
Claims
1. A sealed compressor comprising a sealed container that contains
an electric element, and a compression element driven by the
electric element, wherein the compression element includes: a shaft
that includes a main shaft portion, and an eccentric shaft portion
integrally movable with the main shaft portion, a bearing portion
that supports the main shaft portion of the shaft to constitute a
cantilever bearing, a cylinder that compresses gas, a piston
reciprocatively inserted into the cylinder, and a connecting rod
that connects the eccentric shaft portion with the piston, an angle
a1 formed by a first center line indicating a shaft center of the
bearing portion, and a second center line indicating a shaft center
of the cylinder, and an absolute value c1 of an angle of a tilt of
the shaft with respect to the bearing portion satisfy equation (1):
a1=.pi./2+c1 (1), and an outer circumferential surface of the
piston includes: a seal portion producing a clearance from an inner
circumferential surface of the cylinder, and forming a sliding
surface, an extension portion disposed in a rear of the seal
portion, and forming a sliding surface, and a non-sliding portion
disposed in the rear of the seal portion, and not forming a sliding
surface.
2. The sealed compressor according to claim 1, wherein the
extension portion has a radius same as a radius of the seal
portion, and forms the sliding surface that supports side
pressure.
3. The sealed compressor according to claim 1, wherein the electric
element is driven at a plurality of rotation speeds by an inverter
circuit.
4. A refrigeration device comprising the sealed compressor
according to claim 1 in a freezing cycle.
Description
TECHNICAL FIELD
[0001] The present invention relates to a sealed compressor capable
of reducing sliding loss of a piston, and a refrigeration device
including this sealed compressor.
BACKGROUND ART
[0002] There has been a recent demand for higher efficiency of a
sealed compressor included in a refrigerator or other refrigeration
devices with an aim to reduce power consumption.
[0003] A type of sealed compressors developed under these
circumstances decreases distortion of a reciprocating piston
produced within a compression chamber during a compression stroke
to reduce sliding loss and improve efficiency (for example, see PTL
1).
[0004] A conventional sealed compressor is hereinafter described
with reference to the drawings. FIG. 8 is a longitudinal
cross-sectional view of a conventional sealed compressor. FIG. 9 is
a cross-sectional view illustrating a main part around a piston of
the conventional sealed compressor during a compression stroke.
FIG. 10 is a cross-sectional view illustrating the main part around
the piston of the conventional sealed compressor during a suction
stroke.
[0005] As illustrated in FIGS. 8 through 10, sealed container 301
of the conventional sealed compressor contains electric element 304
including stator 302 and rotor 303, and compression element 305
driven by electric element 304. Shaft 310 includes main shaft
portion 311, and eccentric shaft portion 312 eccentrically disposed
at one end of main shaft portion 311. Rotor 303 is fixed to main
shaft portion 311.
[0006] Cylinder block 314 includes substantially cylindrical
cylinder 315, and bearing portion 320. Piston 323 is
reciprocatively inserted into cylinder 315. Valve plate 350 is
attached to an end surface of cylinder 315. Cylinder 315 and piston
323 constitute compression chamber 316.
[0007] As illustrated in FIG. 9, piston pin 325 attached to piston
323 is positioned in parallel with eccentric shaft portion 312.
Bearing portion 320 supporting main shaft portion 311 of shaft 310
constitutes a cantilever bearing.
[0008] Connecting rod 326 is composed of large-hole end portion
328, small-hole end portion 329, and rod portion 330. Large-hole
end portion 328 engages with eccentric shaft portion 312.
Small-hole end portion 329 connects with piston 323 via piston pin
325. Eccentric shaft portion 312 and piston 323 connect with each
other via connecting rod 326 and piston pin 325.
[0009] In the drawing, shaft center C indicates a shaft center of
piston 323, while shaft center D indicates a shaft center of
cylinder 315.
[0010] Operation of the conventional sealed compressor thus
constructed is hereinafter described. When electric element 304 is
turned on, rotor 303 causes rotation of shaft 310. Rotational
movement of eccentric shaft portion 312 produced in accordance with
rotation of shaft 310 is transmitted to piston 323 via connecting
rod 326. As a result, piston 323 starts reciprocating movement
within cylinder 315. This reciprocating movement of piston 323
sucks refrigerant gas from a cooling system (not shown) having a
freezing cycle, and supplies the refrigerant gas into compression
chamber 316. The refrigerant gas is compressed in compression
chamber 316, and again discharged to the cooling system.
[0011] During a compression stroke of the reciprocating movement of
piston 323, piston 323 is pressed toward eccentric shaft portion
312 by a compression load applied to compress the refrigerant gas.
As a result, shaft 310 is tilted within bearing portion 320. In
this case, shaft center C of piston 323 is also tilted in
accordance with the tilt of shaft 310. Accordingly, for alignment
between shaft center C of piston 323 and shaft center D of cylinder
315 during the compression stroke, shaft center D of cylinder 315
is disposed in a tilted position in correspondence with the tilt of
shaft center C of piston 323. This structure decreases distortion
of piston 323 within cylinder 315 during the compression stroke,
thereby reducing sliding loss to achieve higher efficiency.
[0012] In the conventional sealed compressor, however, piston 323
is pulled toward cylinder 315 by a suction load applied to suck
refrigerant gas during a suction stroke of the reciprocating
movement of piston 323 as illustrated in FIG. 10. In this case,
shaft 310 is tilted toward cylinder 315. As a result, shaft center
C of piston 323 deviates from shaft center D of cylinder 315
disposed in a tilted position beforehand. Particularly when the
suction load increases under severe driving conditions including a
high compression ratio, shaft center C of piston 323 is further
tilted in such a manner as to press a tip end of piston 323 against
a bottom of compression chamber 316. This condition produces
distortion of piston 323, and increases input accordingly.
CITATION LIST
Patent Literature
[0013] PTL 1: Japanese Translation of PCT Publication No.
2011-508840
SUMMARY OF THE INVENTION
[0014] The present invention solves the aforementioned conventional
problems by providing a highly efficient sealed compressor capable
of preventing input increase by reducing distortion produced by a
tilt of a piston during a suction stroke.
[0015] A sealed compressor according to the present invention
includes a sealed container that contains an electric element, and
a compression element driven by the electric element. The
compression element includes a shaft that includes a main shaft
portion, and an eccentric shaft portion integrally movable with the
main shaft portion, and further includes a bearing portion that
supports the main shaft portion of the shaft to constitute a
cantilever bearing. The compression element further includes a
cylinder that compresses gas, a piston reciprocatively inserted
into the cylinder, and a connecting rod that connects the eccentric
shaft portion with the piston. An angle a1 formed by a first center
line indicating a shaft center of the bearing portion, and a second
center line indicating a shaft center of the cylinder, and an
absolute value c1 of an angle of a tilt of the shaft with respect
to the bearing portion satisfy equation (1). An outer
circumferential surface of the piston includes a seal portion
producing a clearance from an inner circumferential surface of the
cylinder, and forming a sliding surface, an extension portion
disposed in a rear of the seal portion, and forming a sliding
surface, and a non-sliding portion disposed in the rear of the seal
portion, and not forming a sliding surface.
a1=.pi./2+c2 (1)
[0016] In this structure, a side extension portion constituting a
sliding surface is disposed in the rear of the seal portion forming
a sliding surface of the piston even in a state of large deviation
between the shaft center of the cylinder and the shaft center of
the piston during a suction stroke. This structure eliminates a
sliding surface in the vertical up-down direction. Accordingly,
local distortion of the piston in the vertical up-down direction
decreases at the time of a tilt of the piston.
[0017] The sealed compressor according to the present invention
reduces local distortion produced during a suction stroke of a
piston for prevention of input increase, thereby improving
efficiency.
BRIEF DESCRIPTION OF DRAWINGS
[0018] FIG. 1 is a longitudinal cross-sectional view of a sealed
compressor according to a first exemplary embodiment of the present
invention.
[0019] FIG. 2 is an enlarged cross-sectional view of a main part of
the sealed compressor according to the first exemplary embodiment
of the present invention when a compression load is applied during
a compression stroke.
[0020] FIG. 3 is an enlarged cross-sectional view of the main part
of the sealed compressor according to the first exemplary
embodiment of the present invention when a suction load is applied
during a suction stroke.
[0021] FIG. 4 is a cross-sectional view of a cylinder and a piston,
as viewed from above, of the sealed compressor according to the
first exemplary embodiment of the present invention.
[0022] FIG. 5 is a longitudinal cross-sectional view of the
cylinder and the piston of the sealed compressor according to the
first exemplary embodiment of the present invention.
[0023] FIG. 6 is a cross-sectional view of a main part illustrating
a positional relationship between a bearing portion and the
cylinder of the sealed compressor according to the first exemplary
embodiment of the present invention.
[0024] FIG. 7 is a schematic cross-sectional view of a refrigerator
according to a second exemplary embodiment of the present
invention.
[0025] FIG. 8 is a longitudinal cross-sectional view of a
conventional sealed compressor.
[0026] FIG. 9 is a cross-sectional view of a main part around a
piston during a compression stroke of the conventional sealed
compressor.
[0027] FIG. 10 is a cross-sectional view of the main part around
the piston during a suction stroke of the conventional sealed
compressor.
DESCRIPTION OF EMBODIMENTS
[0028] Exemplary embodiments according to the present invention are
hereinafter described with reference to the drawings. The present
invention is not limited to the exemplary embodiments presented
herein.
First Exemplary Embodiment
[0029] FIG. 1 is a longitudinal cross-sectional view of a sealed
compressor according to a first exemplary embodiment of the present
invention. FIG. 2 is an enlarged cross-sectional view of a main
part of the sealed compressor when a compression load is applied
during a compression stroke. FIG. 3 is an enlarged cross-sectional
view of the main part of the sealed compressor when a suction load
is applied during a suction stroke. FIG. 4 is a cross-sectional
view of a cylinder and a piston, as viewed from above, of the
sealed compressor. FIG. 5 is a longitudinal cross-sectional view of
the cylinder and the piston of the sealed compressor. FIG. 6 is a
cross-sectional view of a main part illustrating a positional
relationship between a bearing portion and the cylinder of the
sealed compressor.
[0030] As illustrated in FIGS. 1 through 6, sealed container 101
contains electric element 104 including stator 102 and rotor 103,
and compression element 105 driven by electric element 104.
Lubricant 106 is stored in an inner bottom of sealed container
101.
[0031] An interior of sealed container 101 is filled with
hydrocarbon type R600a refrigerant 106. Lubricant 102 that is
low-viscosity oil in a range from VG3 to VG10 is sealed into the
bottom of sealed container 101.
[0032] Electric element 104 includes rotor 103 and stator 102, and
is driven by an inverter (not shown) at a plurality of driving
frequencies including at least a driving frequency equal to or
higher than a power supply frequency. A maximum driving frequency
for driving electric element 104 is set to 80 Hz. Electric element
104 is driven at a driving frequency equal to or higher than a
minimum driving frequency of 17 Hz.
[0033] Shaft 110 includes main shaft portion 111, and eccentric
shaft portion 112 eccentrically disposed at one end of main shaft
portion 111 and integrally movable with main shaft portion 111.
Rotor 103 is fixed to main shaft portion 111. Lubrication path 113
is provided within shaft 110 and in a surface of shaft 110. A lower
portion of lubrication path 113 is extended to reach a
predetermined depth of lubricant 106 for immersion in lubricant
106.
[0034] Cylinder block 114 includes cylinder 115 having a
cylindrical shape (including a substantially cylindrical shape),
and bearing portion 120. Bearing portion 120 supporting main shaft
portion 111 of shaft 110 constitutes a cantilever bearing.
[0035] Piston 123 is reciprocatively inserted into cylinder 115.
Valve plate 150 is attached to an end of cylinder 115. Cylinder 115
and piston 123 form compression chamber 116.
[0036] Piston pin 125 attached to piston 123 is positioned in
parallel with eccentric shaft portion 112. As illustrated in FIGS.
4 and 5, seal portion 123a and extension portion 123b are formed on
an outer circumferential surface of piston 123. Seal portion 123a
has a cylindrical sliding surface configured to produce a small
clearance from an inner circumferential surface of cylinder 115.
Extension portion 123b has sliding surfaces disposed on both side
surfaces of piston 123 in the rear of seal portion 123a. Each
sliding surface of extension portion 123b has a radius same as a
radius of seal portion 123a, and is extended in an axial direction
of piston 123 while maintaining a fixed width. Non-sliding portion
123c is formed in each of vertically upper and lower surfaces of
piston 123 in the rear of seal portion 123a. Each of non-sliding
portions 123c has a larger clearance from the inner circumferential
surface of cylinder 115, thereby constituting a portion not
slidable.
[0037] As illustrated in FIG. 2, connecting rod 126 is composed of
large-hole end portion 128, small-hole end portion 129, and rod
portion 130. Large-hole end portion 128 engages with eccentric
shaft portion 112. Small-hole end portion 129 connects with piston
123 via piston pin 125. Eccentric shaft portion 112 and piston 123
connect with each other via connecting rod 126 and piston pin
125.
[0038] In general, shaft 110, connecting rod 126, piston pin 125,
and piston 123 constituting a part of compression element 105 are
assembled such that shaft center 144 of main shaft portion 111 of
shaft 110, and shaft center C of reciprocating piston 123 form an
angle of .pi./2 (rad). A structure assembled in this manner
achieves smoothest operation and reduces driving loss. Accordingly,
this exemplary embodiment is constructed in a similar manner.
[0039] According to this exemplary embodiment, piston 123 is sized
to have a diameter of 26 mm, a full length of 23 mm, and axial
lengths of 8 mm and 15 mm for seal portion 123a and extension
portion 123b, respectively. Each radius clearance between the inner
circumferential surface of cylinder 115 and the sliding surface of
seal portion 123a, and between the inner circumferential surface of
cylinder 115 and the sliding surface of extension portion 123b is
set to 0.005 mm. A radius clearance between the inner
circumferential surface of cylinder 115 and non-sliding portion
123c is set to 0.5 mm.
[0040] Considered herein is a projection surface extending in
parallel with first center line 141 indicating a shaft center of
bearing portion 120, and in parallel with second center line 142
indicating a shaft center of cylinder 115 as illustrated in FIG. 6.
An angle formed by first center line 141 and second center line 142
is defined as angle a1. An absolute value of an angle of a tilt of
shaft 110 with respect to bearing portion 120 produced by a
diameter clearance between bearing portion 120 and main shaft
portion 111 is defined as value c1 (rad). Cylinder block 114
(cylinder 115) is constructed such that angle a1 and value c1
satisfy the following equation (1).
a1=.pi./2+c1 (1)
[0041] Operation of the sealed compressor thus constructed is
hereinafter described. When electric element 104 is turned on,
rotor 103 causes rotation of shaft 110. Rotational movement of
eccentric shaft portion 112 produced in accordance with rotation of
shaft 110 is transmitted to piston 123 via connecting rod 126.
[0042] As a result, piston 123 starts reciprocating movement within
cylinder 115. This reciprocating movement of piston 123 sucks
refrigerant gas from a cooling system (not shown) having a freezing
cycle, and supplies the refrigerant gas into compression chamber
116. The refrigerant gas is compressed in compression chamber 116,
and again discharged to the cooling system.
[0043] Pumping operation produced by rotation of shaft 110 starts
at a lower end of lubrication path 113. Lubricant 106 stored in the
bottom of sealed container 101 passes through lubrication path 113,
flows upward by the pumping operation, and horizontally scatters
toward the entire circumference within sealed container 101.
Scattered lubricant 106 reaches piston pin 125, piston 123 and the
like to lubricate piston pin 125, piston 123 and the like.
[0044] Distortion of the piston is hereinafter described.
[0045] In a sealed compressor including a cantilever bearing
structure, a compression load during compression of refrigerant gas
is generally supported only on one side of main shaft portion 111
of shaft 110. In this case, shaft 110 is tilted within the diameter
clearance between main shaft portion 111 and bearing portion 120
when a compression load is applied during a compression stroke as
illustrated in FIG. 2. Accordingly, in the assembly setting .pi./2
(rad) for the angle of shaft center C of piston 123 with respect to
shaft center 144 of main shaft portion 111, the valve plate 150
side of piston 123 is tilted upward from a horizontal line.
[0046] According to this exemplary embodiment, the valve plate 150
side of shaft center D of cylinder 115 is tilted beforehand in the
upward direction from the horizontal line in consideration of the
tilt of piston 123.
[0047] Accordingly, when a compression load is applied to piston
123 during the compression stroke, shaft center D of cylinder 115
is aligned with shaft center C of piston 123 as illustrated in FIG.
2. As a result, distortion of reciprocating piston 123
decreases.
[0048] As illustrated in FIG. 6, an intersection O is defined at an
intersection of first center line 141 indicating the shaft center
of bearing portion 120 and second center line 142 indicating the
shaft center of cylinder 115. Absolute value c1 is defined as an
absolute value of an angle of a tilt of shaft 110 with respect to
bearing portion 120 produced by the diameter clearance between
bearing portion 120 and main shaft portion 111. In this case,
cylinder 115 is disposed such that angle a1 formed by first center
line 141 indicating the shaft center of bearing portion 120 and
second center line 142 indicating the shaft center of cylinder 115
satisfy equation (1).
[0049] More specifically, angle a1 expressed by equation (1) is
determined as a design value of the angle of the shaft center of
cylinder 115 according to this exemplary embodiment. Angle a1 is so
designed as to approximate an actual value based on absolute value
c1 of the angle of the tilt of shaft 110 with respect to bearing
portion 120. Accordingly, distortion between piston 123 and
cylinder 115 more securely decreases.
[0050] On the other hand, shaft 110 is tilted within the diameter
clearance between main shaft portion 111 and bearing portion 120
when suction force is applied to piston 123 during the suction
stroke as illustrated in FIG. 3. According to this exemplary
embodiment, assembly is determined such that the angle of shaft
center C of piston 123 with respect to shaft center 144 of main
shaft portion 111 of shaft 110 becomes .pi./2 (rad) at the time of
a tilt of shaft 110 within the diameter clearance of bearing
portion 120. Accordingly, the valve plate 150 side of piston 123 is
tilted downward from the horizontal line in this state. As a
result, deviation is produced from shaft center D of cylinder 115
designed in consideration of the tilt of piston 123 during the
compression stroke.
[0051] As apparent, shaft center C of piston 123 tilts and deviates
downward from shaft center D of cylinder 115 when a suction load is
applied to piston 123 during the suction stroke. In this case, a
maximum tilt amount of seal portion 123a in the radial direction
produced at shaft center deviation angle .alpha. of piston 123 is
expressed as (axial length L of seal portion 123a).times.sin
(.alpha.) as illustrated in FIG. 5.
[0052] In a typical sealed compressor for use in applications
similar to a use application of this exemplary embodiment, an axial
full length of piston 123 is set to a length of seal portion 123a
to secure sealing and sliding reliability. The radius clearance of
seal portion 123a, i.e., 0.005 mm in this exemplary embodiment, is
the minimum clearance in clearances produced by components of
compression element 105. In this case, the maximum tilt amount of
seal portion 123a in the radial direction during the suction stroke
becomes larger than 0.005 mm, the radius clearance of seal portion
123a. Accordingly, distortion is produced between E part of piston
123 on the compression chamber 116 side, and F part of piston 123
on the eccentric shaft portion 112 side.
[0053] According to this exemplary embodiment, however, the sliding
portion of piston 123 is composed of seal portion 123a, and
extension portion 123b provided on both sides of piston 123 for
supporting side pressure. In this case, F part corresponds to
non-sliding portion 123c having a radius clearance of 0.5 mm, which
is sufficiently larger than 0.005 mm of the radius clearance of the
seal portion. Accordingly, no contact is produced between F part of
piston 123 and the inner circumferential surface of cylinder
115.
[0054] Moreover, the maximum tilt amount L.times.sin (.alpha.) of
seal portion 123a in the radial direction produced at shaft center
deviation angle a becomes smaller than 0.005 mm of the radius
clearance in the vicinity of E part as a result of small length L
of seal portion 123a.
[0055] In this case, distortion at E part of piston 123 decreases
even when a suction load is applied during the suction stroke.
[0056] Accordingly, distortion between piston 123 and cylinder 115
decreases during the suction stroke, as well as during the
compression stroke.
[0057] Furthermore, the suction force generated during the suction
stroke is considerably smaller than the compression load, wherefore
the tilt angle of piston 123 becomes smaller during the suction
stroke than the compression stroke. Distortion between piston 123
and cylinder 115 also becomes smaller during the suction stroke
than the compression stroke. Accordingly, distortion between piston
123 and cylinder 115 during the suction stroke effectively
decreases.
[0058] According to this exemplary embodiment, therefore,
efficiency improves by reduction of sliding loss produced between
piston 123 and cylinder 115 during both the compression and suction
strokes.
[0059] As described above, the sealed compressor according to this
exemplary embodiment includes sealed container 101 that contains
electric element 104, and compression element 105 driven by
electric element 104. Compression element 105 includes shaft 110
that includes main shaft portion 111, and eccentric shaft portion
112 integrally movable with main shaft portion 111, and further
includes bearing portion 120 that supports main shaft portion 111
of shaft 110 to constitute a cantilever bearing. Compression
element 105 further includes cylinder 115 that compresses gas,
piston 123 reciprocatively inserted into cylinder 115, and
connecting rod 126 that connects eccentric shaft portion 112 with
piston 123. Angle a1 formed by first center line 141 indicating a
shaft center of bearing portion 120, and second center line 142
indicating a shaft center of cylinder 115, and absolute value c1 of
an angle of a tilt of shaft 110 with respect to bearing portion 120
satisfy equation (1). An outer circumferential surface of piston
123 includes seal portion 123a producing a clearance from an inner
circumferential surface of cylinder 115, and forming a sliding
surface, extension portion 123b disposed in a rear of seal portion
123a, and forming a sliding surface, and non-sliding portion 123c
disposed in the rear of seal portion 123a, and not forming a
sliding surface.
[0060] This structure reduces sliding loss of piston 123 and
cylinder 115 during both the compression and suction strokes,
thereby improving efficiency.
[0061] Extension portion 123b has a radius same as a radius of seal
portion 123a, and forms the sliding surface that supports side
pressure. This structure reduces local distortion of the piston,
thereby preventing input increase and improving efficiency.
[0062] Electric element 104 is driven at a plurality of rotation
speeds by an inverter circuit.
[0063] This structure prevents distortion of the piston within the
cylinder even under a driving condition of low-speed rotation where
a lubricant film thickness decreases on the sliding surface of the
piston as a result of a small lubricant supply amount to the
piston. This structure also prevents distortion of the piston
within the cylinder during the suction stroke under a driving
condition of high-speed rotation where the tilt of the piston
increases due to a high compression ratio. Accordingly, efficiency
improves.
Second Exemplary Embodiment
[0064] FIG. 7 is a schematic cross-sectional view of a refrigerator
according to a second exemplary embodiment of the present
invention. Described herein is a refrigerator presented as an
example of a refrigeration device. The refrigerator illustrated in
FIG. 7 includes the sealed compressor described in the first
exemplary embodiment.
[0065] As illustrated in FIG. 7, heat insulating box 180 includes
inner box 182, outer box 184, and heat insulating walls. Inner box
182 is produced by vacuum forming of a resin material such as ABS
(Acrylonitrile Butadiene Styrene). Outer box 184 is made of a metal
material such as pre-coated steel sheet. The heat insulating walls
are produced by filling foamed heat insulating material 186 into a
space defined by inner box 182 and outer box 184. Heat insulating
material 186 is made of rigid urethane foam, phenol foam, styrene
foam or the like. It is more preferable to use hydrocarbon
cyclopentane for a foamed material in view of prevention of global
warming.
[0066] Heat insulating box 180 is divided into a plurality of heat
insulating sections. A revolving-type door is provided in an upper
part, while drawer-type compartments are provided in lower part of
heat insulating box 180. The plurality of heat insulating sections
include refrigerating compartment 188, a pair of drawer-type
switching compartment 190 and ice compartment 192 disposed side by
side, drawer-type vegetable compartment 194, and drawer-type
freezing compartment 196 in this order from above. A heat
insulating door is attached to each of the respective heat
insulating sections via a gasket. These doors are composed of
refrigerating compartment revolving door 198, switching compartment
drawer door 200, ice compartment drawer door 202, vegetable
compartment drawer door 204, and freezing compartment drawer door
206 in this order from above.
[0067] Outer box 184 of heat insulating box 180 includes recessed
portion 208 corresponding to a recessed rear part of a top surface
of outer box 184.
[0068] In a freezing cycle, sealed compressor 210, a condenser (not
shown) provided on a side or other portions of heat insulating box
180, capillary 212 corresponding to a decompressor, a drier (not
shown) for removing moisture, evaporator 216, and suction piping
218 are connected in an annular shape. Sealed compressor 210
corresponds to the sealed compressor described in the first
exemplary embodiment, and is elastically supported on recessed
portion 208. Evaporator 216 is disposed in a rear of vegetable
compartment 194 and freezing compartment 196. Cooling fan 214 is
provided in the vicinity of evaporator 216.
[0069] Operation and effect of the refrigerator thus constructed
are hereinafter described.
[0070] Initially, temperature setting and cooling system for the
respective heat insulating sections are described.
[0071] A temperature of refrigerating compartment 188 is generally
determined in a range from 1.degree. C. to 5.degree. C., with a
lower limit set above a freezing temperature for refrigerating
storage.
[0072] Temperature setting of switching compartment 190 is
changeable by a user within a predetermined temperature zone,
ranging from a freezing compartment temperature zone to a
refrigerating compartment or vegetable compartment temperature
zone.
[0073] Ice compartment 192 is an independent ice storage
compartment. Ice compartment 192 includes a not-shown automatic ice
making device to automatically produce ice and store the produced
ice. A temperature of ice compartment 192 is set in the freezing
temperature zone for storage of ice. However, the temperature of
ice compartment 192 may be set at a freezing temperature in a range
from -18.degree. C. to -10.degree. C. for storage of ice, which
temperature is relatively higher than the freezing temperature
zone.
[0074] A temperature of vegetable compartment 194 is often set at a
temperature equivalent to the temperature range of refrigerating
compartment 188, or at a temperature ranging from 2.degree. C. to
7.degree. C., which is slightly higher than the temperature range
of refrigerating compartment 188. Freshness of leafy vegetables
continues longer as the temperature of vegetable compartment 194
decreases toward a lower limit above a freezing temperature.
[0075] A temperature of freezing compartment 196 is generally set
in a range from -22.degree. C. to -18.degree. C. for freezing
storage. However, the temperature of freezing compartment 196 may
be set in a low temperature range from -30.degree. C. to
-25.degree. C. for improvement of a freezing storage state.
[0076] The respective compartments are sectioned by the heat
insulating walls to efficiently maintain different temperature
settings. However, heat insulating box 180 may be integrally formed
by filling foamed heat insulating material 186 to reduce costs and
improve heat insulation performance. Heat insulating box 180 formed
by filling foamed heat insulating material 186 exhibits
approximately twice the heat insulation performance of a structure
formed of a heat insulating material such as styrene foam.
Accordingly, heat insulating box 180 thus constructed is allowed to
increase a storage volume by reduction of thicknesses of
partitioning parts.
[0077] Operation of the freezing cycle is hereinafter
described.
[0078] Cooling operation starts and stops in response to signals
generated from a temperature sensor (not shown) and a control board
based on the set temperatures within the refrigerator. Sealed
compressor 210 performs predetermined compression operation in
accordance with instructions of cooling operation. Discharged
high-temperature and high-pressure refrigerant gas is condensed and
liquefied at the condenser (not shown) while releasing heat, and
decompressed by capillary 212 to become low-temperature and
low-pressure liquid refrigerant. The generated liquid refrigerant
reaches evaporator 216.
[0079] The refrigerant gas within evaporator 216 is evaporated and
gasified by heat exchange with air inside the refrigerator in
accordance with operation of cooling fan 214. Low-temperature
cooling air after heat exchange is distributed by a damper (not
shown) or the like to cool the respective compartments.
[0080] In sealed compressor 210 of the refrigerator performing the
foregoing operation, cylinder block 114 includes bearing portion
120 and cylinder 115 disposed such that first center line 141
indicating the shaft center of bearing portion 120 and second
center line 142 indicating the shaft center of cylinder 115 cross
each other as described in the first exemplary embodiment. Angle a1
(rad) formed by first center line 141 and second center line 142,
and absolute value c1 (rad) of the angle of the tilt of shaft 110
with respect to bearing portion 120 produced by the diameter
clearance between bearing portion 120 and main shaft portion 111
satisfy equation (1). Piston 123 includes cylindrical seal portion
123a constituting a sliding surface and producing a uniform
clearance between an outer circumferential surface of piston 123
and an inner circumferential surface of cylinder 115. Piston 123
further includes extension portion 123b disposed in the rear of
seal portion 123a, having a radius same as a radius of seal portion
123a, and constituting a sliding surface for supporting side
pressure.
[0081] In this structure, a sliding area in a tilted state of
piston 123 decreases even when deviation between the shaft center
of cylinder 115 and the shaft center of piston 123 increases during
the suction stroke. This effect is produced by the configuration of
piston 123 which includes extension portion 123b constituting a
sliding surface for supporting side pressure in the rear of
cylindrical seal portion 123a providing a sliding surface of piston
123, and eliminates a sliding surface in the vertical up-down
direction.
[0082] This structure decreases local distortion of piston 123,
thereby reducing sliding loss for improvement of efficiency of
sealed compressor 210. As a result, reduction of power consumption
of the refrigerator is achievable.
[0083] As described above, the refrigerator in this exemplary
embodiment is a refrigeration device including the sealed
compressor according to the first exemplary embodiment.
Accordingly, the refrigeration device provided herein realizes
reduction of power consumption.
INDUSTRIAL APPLICABILITY
[0084] As described above, the sealed compressor according to the
present invention improves efficiency by reduction of sliding loss
of a piston, and therefore is applicable not only to a household
electric refrigerator, but also to a refrigeration device for an
air conditioner, a vending machine, or various other
apparatuses.
REFERENCE MARKS IN THE DRAWINGS
[0085] 101 Sealed container
[0086] 102 Stator
[0087] 103 Rotor
[0088] 104 Electric element
[0089] 105 Compression element
[0090] 106 Lubricant
[0091] 110 Shaft
[0092] 111 Main shaft portion
[0093] 112 Eccentric shaft portion
[0094] 113 Lubrication path
[0095] 114 Cylinder block
[0096] 115 Cylinder
[0097] 116 Compression chamber
[0098] 120 Bearing portion
[0099] 123 Piston
[0100] 123a Seal portion
[0101] 123b Extension portion
[0102] 123c Non-sliding portion
[0103] 125 Piston pin
[0104] 126 Connecting rod
[0105] 128 Large-hole end portion
[0106] 129 Small-hole end portion
[0107] 130 Rod portion
[0108] 141 First center line
[0109] 142 Second center line
[0110] 144 Shaft center
[0111] 150 Valve plate
[0112] 180 Heat insulating box
[0113] 182 Inner box
[0114] 184 Outer box
[0115] 186 Heat insulating material
[0116] 188 Refrigerating compartment
[0117] 190 Switching compartment
[0118] 192 Ice compartment
[0119] 194 Vegetable compartment
[0120] 196 Freezing compartment
[0121] 198 Refrigerating compartment revolving door
[0122] 200 Switching compartment drawer door
[0123] 202 Ice compartment drawer door
[0124] 204 Vegetable compartment drawer door
[0125] 206 Freezing compartment drawer door
[0126] 208 Recessed portion
[0127] 210 Sealed compressor
[0128] 212 Capillary
[0129] 214 Cooling fan
[0130] 216 Evaporator
[0131] 218 Suction piping
* * * * *