U.S. patent application number 10/518643 was filed with the patent office on 2005-12-01 for hermetic compressor.
This patent application is currently assigned to Matsushita Refrigeration Company. Invention is credited to Akashi, Hironari, Kakiuchi, Takashi, Katayama, Makoto, Kawabata, Hirotake, Kojima, Takeshi, Kubota, Akihiko, Nagao, Takahide, Tsuboi, Kosuke.
Application Number | 20050265863 10/518643 |
Document ID | / |
Family ID | 29996750 |
Filed Date | 2005-12-01 |
United States Patent
Application |
20050265863 |
Kind Code |
A1 |
Akashi, Hironari ; et
al. |
December 1, 2005 |
Hermetic compressor
Abstract
Relating to oil feed to a piston portion in a dual support
bearing of a hermetic compressor, and a structure for improving
efficiency and reliability and accomplishing reduction of noise is
disclosed. In this structure, since an auxiliary bearing 119 is
provided with an oil feed passage 129 for conducting lubricating
oil 108 discharged from an upper end of an oil feed mechanism 114,
to a sliding surface of a piston 120, the lubricating oil 108 is
fed to the piston 120 and a piston pin 122 from the oil feed
passage 129 to make the sealing performance excellent, so that the
amount of leakage of refrigerant gas from a compression chamber 117
is reduced to improve the freezing capability or efficiency.
Further, lubrication of sliding portions of the piston 120 and the
piston pin 122 becomes excellent so that noise caused by sliding is
reduced and the reliability is improved.
Inventors: |
Akashi, Hironari;
(Chigasaki-shi, JP) ; Kawabata, Hirotake;
(Fujisawa-shi, JP) ; Kubota, Akihiko;
(Chigasaki-shi, JP) ; Nagao, Takahide;
(Fujisawa-shi, JP) ; Katayama, Makoto;
(Chigasaki-shi, JP) ; Tsuboi, Kosuke;
(Chigasaki-shi, JP) ; Kakiuchi, Takashi;
(Yamato-shi, JP) ; Kojima, Takeshi; (Yokohama-shi,
JP) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ LLP
SUITE 800
1990 M STREET NW
WASHINGTON
DC
20036-3425
US
|
Assignee: |
Matsushita Refrigeration
Company
Kusatsu-shi
JP
|
Family ID: |
29996750 |
Appl. No.: |
10/518643 |
Filed: |
July 15, 2005 |
PCT Filed: |
June 26, 2003 |
PCT NO: |
PCT/JP03/08143 |
Current U.S.
Class: |
417/415 ;
417/372; 417/902 |
Current CPC
Class: |
F04B 39/0246 20130101;
F04B 39/0292 20130101 |
Class at
Publication: |
417/415 ;
417/372; 417/902 |
International
Class: |
F04B 017/00; F04B
035/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 26, 2002 |
JP |
2002-185774 |
Claims
1. A hermetic compressor having a sealed housing storing therein
lubricating oil and receiving therein a motor element and a
compression element driven by said motor element, said compression
element comprising a shaft having an eccentric shaft portion, and
an auxiliary shaft portion and a main shaft portion coaxially
provided on upper and lower sides of said eccentric shaft portion
so as to sandwich it therebetween, a cylinder block provided with a
compression chamber of a substantially cylindrical shape, a main
bearing fixed to or formed integral with said cylinder block so as
to be substantially perpendicular to an axis of said compression
chamber and supporting an upper half portion of said main shaft
portion of said shaft, an auxiliary bearing fixed to or formed
integral with said cylinder block and supporting said auxiliary
shaft portion, a piston that performs reciprocating motion in said
compression chamber, and connecting means for coupling said piston
and said eccentric shaft together, wherein said shaft is provided
with an oil feed mechanism having a lower end communicating with
said lubricating oil and an upper end penetratingly open to an
upper end portion of said auxiliary shaft portion, and said
auxiliary bearing is provided with an oil fence for receiving the
lubricating oil spouting out from the upper end portion of said oil
feed mechanism and an oil feed passage for conducting the
lubricating oil to a sliding surface of said piston.
2. A hermetic compressor according to claim 1, wherein an oil pool
for storing said lubricating oil is concavely formed in said oil
feed passage on an upper surface of said auxiliary bearing.
3. A hermetic compressor according to claim 1, wherein an oil
dispersion hole communicating with said oil feed mechanism is
formed in a substantially horizontal direction at a portion of said
auxiliary shaft portion above an upper surface of said auxiliary
bearing.
4. A hermetic compressor according to claim 1, wherein said oil
fence is made to project upward and is provided on an upper surface
of said auxiliary bearing in the vicinity of said oil feed
passage.
5. A hermetic compressor according to claim 1, wherein an opening
portion is provided, said opening portion communicating with said
oil feed passage provided on an upper surface of said auxiliary
bearing and being open above an oil feed passage provided at a
portion of said cylinder block above said compression chamber.
6. A hermetic compressor according to claim 5, wherein an oil guide
projecting downward is provided in the vicinity of the opening
portion on the side of a lower end surface of said auxiliary
bearing.
7. A hermetic compressor according to claim 5, wherein a
cylindrical piston pin fixed to said piston and coupling a
connecting rod being connecting means and said piston together is
provided, and the opening portion is located right above said
piston pin in the vicinity of a bottom dead center of said piston
and is larger than a horizontal section of said piston pin.
8. A hermetic compressor according to claim 1, wherein a cylinder
communicating hole having one end communicating with and open to an
upper portion in the compression chamber of said cylinder block is
provided in said oil feed passage.
9. A hermetic compressor according to claim 1, wherein a
substantially annular oil feed groove communicating with said oil
feed passage in the vicinity of a bottom dead center of said piston
is concavely formed on an outer periphery of said piston.
10. A hermetic compressor according to claim 1, wherein an oil bath
communicating with sliding surfaces between said auxiliary shaft
portion and said auxiliary bearing is formed around said auxiliary
shaft portion.
11. A hermetic compressor according to claim 10, wherein an oil
feed hole is formed on said auxiliary shaft portion, said oil feed
hole establishing communication between said oil bath and said oil
feed mechanism and having a bottom surface located above a bottom
surface of said oil bath.
12. (canceled)
13. A hermetic compressor according to claim 1, wherein an oil
fence projecting upward is provided on a surface of said cylinder
block above the compression chamber, and said oil feed passage is
formed in the surface of said cylinder block above said compression
chamber.
14. A hermetic compressor according to claim 1, which is
inverter-driven at a plurality of operating frequencies including
at least an operating frequency lower than a power supply
frequency.
15. A hermetic compressor according to claim 14, wherein said
operating frequency lower than said power supply frequency includes
at least an operating frequency lower than 30 Hz.
16. A hermetic compressor having a sealed housing storing therein
lubricating oil and receiving therein a motor element and a
compression element driven by said motor element, said compression
element comprising a shaft having an eccentric shaft portion, and
an auxiliary shaft portion and a main shaft portion coaxially
provided on upper and lower sides of said eccentric shaft portion
so as to sandwich it therebetween, a cylinder block provided with a
compression chamber of a substantially cylindrical shape, a main
bearing fixed to or formed integral with said cylinder block so as
to be substantially perpendicular to an axis of said compression
chamber and supporting an upper half portion of said main shaft
portion of said shaft, an auxiliary bearing fixed to or formed
integral with said cylinder block and supporting said auxiliary
shaft portion, a piston that performs reciprocating motion in said
compression chamber, and connecting means for coupling said piston
and said eccentric shaft together, wherein said shaft is provided
with an oil feed mechanism having a lower end communicating with
said lubricating oil and an upper end penetratingly open to an
upper end portion of said auxiliary shaft portion, and said
cylinder block is provided with an oil fence for receiving the
lubricating oil spouting out from the upper end portion of said oil
feed mechanism and an oil feed passage for conducting the
lubricating oil to a sliding surface of said piston.
17. A hermetic compressor according to claim 16, wherein an oil
dispersion hole communicating with said oil feed mechanism is
formed in a substantially horizontal direction at a portion of said
auxiliary shaft portion above an upper surface of said auxiliary
bearing.
Description
TECHNICAL FIELD
[0001] The present invention relates to a hermetic compressor for
use in a refrigerator, an air conditioner, a freezing refrigerating
system or the like.
BACKGROUND ART
[0002] In recent years, reduction in consumption power and noise
reduction have been strongly demanded with respect to hermetic
compressors that are used in freezing systems such as household
freezers, refrigerators and so on. Under the circumstances, there
have been advanced reduction in viscosity of lubricating oil and
reduction in rotation of compressors (e.g. about 1200 r/min in case
of household refrigerators) by inverter driving. On the other hand,
it has been becoming a premise to deal with hydrocarbon
refrigerants etc. that are natural refrigerants with low warming
coefficients represented by R134a and R600a whose ozone destruction
coefficients are zero. Further, a method of a dual support bearing
that supports a shaft at two or more portions, which has been
adopted from the past, is effective as an element technology for
reducing a sliding loss and reducing vibration and noise upon
operation.
[0003] As a conventional hermetic compressor, there is one as
described in a Laid-open Unexamined Patent Publication No.
S61-118571. Hereinbelow, referring to the drawings, description
will be given about the foregoing conventional hermetic
compressor.
[0004] FIG. 8 is a longitudinal sectional view of the conventional
hermetic compressor, and FIG. 9 is a plan view of the main part of
the conventional hermetic compressor. FIGS. 10 and 11 are sectional
views of the main parts of the conventional hermetic compressor. In
FIGS. 8 and 9, 1 denotes a sealed housing, and 2 denotes a space
within the sealed housing. The sealed housing 1 receives therein a
motor element 5 comprising a stator 3 having a coil portion 3a and
a rotor 4, and a compression element 6 driven by the motor element
5. 8 denotes lubricating oil stored within the sealed housing
1.
[0005] 10 denotes a shaft having a main shaft portion 11 where the
rotor 5 is press-fitted and fixed, and an eccentric portion 12
formed eccentrically to the main shaft portion 11, and further
having an auxiliary shaft portion 13 provided coaxially with the
main shaft portion. Inside the main shaft portion 11, a concentric
pump 14 is provided having one end open into the lubricating oil 8
and the other end communicating with a vertical hole portion 15
that communicates with an upper end portion of the shaft 10. 16
denotes a cylinder block having a compression chamber 17 of a
substantially cylindrical shape and a main bearing 18 supporting
the main shaft portion 11, and having at an upper portion thereof
an auxiliary bearing 19 fixed thereto for supporting the auxiliary
shaft portion 13. The auxiliary bearing 19 is provided with a
recess portion 19a provided around an outer peripheral portion of
the shaft 10. 20 denotes a piston inserted into the compression
chamber 17 of the cylinder block 16 so as to be reciprocatingly
slidable therein, and coupled to the eccentric portion 12 by a
connecting means 21 and a piston pin 22.
[0006] With respect to the hermetic compressor thus structured, an
operation thereof will be described hereinbelow. The rotor 4 of the
motor element 5 rotates the shaft 10 to transmit rotational motion
of the eccentric portion 12 to the piston 20 via the connecting
means 21, so that the piston 20 performs reciprocating motion in
the compression chamber 17. Following it, refrigerant gas is sucked
from a cooling system (not shown) into the compression chamber 17
and compressed therein, then discharged into the cooling system
again.
[0007] Here, description will be given about a sliding loss
reducing mechanism of the dual support bearing. During the
operation of the compressor, a compressive load of the piston 20 is
transmitted to the eccentric portion 12 via the connecting means
21. Here, inasmuch as the dual support bearing type receives the
load at both the upper and lower bearings centering around the
eccentric portion 12 (point of application) where the compressive
load from the piston 20 is applied, the load is distributed
substantially uniformly to the upper and lower bearings, and a face
contact is ensured as opposed to the single support bearing type in
which a mounting error occurs at the inner periphery, so that load
distribution at sliding portions of the shaft 10 becomes uniform to
lower the surface pressure, and thus the sliding length can be
shortened as compared with the single support type. As a result
thereof, there is provided with a merit that the sliding loss is
reduced to achieve improvement in efficiency of the compressor.
[0008] Next, description will be given about an oil feed mechanism
of the conventional dual support bearing type. In FIG. 10, by
rotation of the shaft 10, the lubricating oil 8 in the concentric
pump 14 is drawn upward by a centrifugal force forming free
surfaces like parabolas A1, A2, flown into the vertical hole
portion 15 by a conveying force of the tributary A1, and introduced
into the respective sliding portions of the main shaft 11, the
eccentric portion 12 and the auxiliary shaft portion 13 in the
order named, thereby lubricating them. Further, in FIG. 11, of the
lubricating oil 8 drawn up into the vertical hole portion 15, one
portion is thrown (direction B) to the sealed housing 1 using as a
guide a communication hole 13a provided in the auxiliary shaft
portion 13 and the recess portion 19a, and one portion is thrown
(direction C) to the sealed housing 1 from an upper end of the
vertical hole portion 15. This provides the mechanism in which the
lubricating oil 8 having received the heat from the respective
sliding portions can perform the heat radiation to the sealed
housing 1 so as to be cooled.
[0009] However, in the foregoing conventional structure, inasmuch
as the lubricating oil 8 drawn up by the rotation of the shaft 10
is fed to the piston 20 indirectly in the form of air dispersion,
the feed amount thereof is unstable. Accordingly, there has been
possibility of lowering of reliability such that when the
lubricating oil 8 between the piston 20 and the cylinder block 16
becomes insufficient, the amount of leakage of the refrigerant gas
from the compression chamber 17 increases to lower the freezing
capability or efficiency, or sliding portions between the piston 20
and the cylinder block 16 are subjected to lubrication failure to
cause abrasion.
[0010] Further, in the foregoing conventional structure, inasmuch
as the tip end of the auxiliary shaft portion 13 is located in a
position higher than the auxiliary bearing 19 and the cylinder
block 16, a portion of the lubricating oil 8 dispersed from the
upper end of the vertical hole portion 15 and the communication
hole 13a of the auxiliary shaft portion 13 flies over the cylinder
block 16 and is splashed on a suction muffler (not shown) normally
located under the compression chamber and, as a result, there has
been such an instance where the temperature of the suction muffler
increases to raise the temperature of suction gas so that the
freezing capability or efficiency is lowered.
[0011] Further, in the foregoing conventional structure, upon
assembling the compression element 6, it is not possible to
assemble the piston 20, the piston pin 22 and the connecting means
21 after fixing the auxiliary bearing 19 to the cylinder block 16,
so that the assembling method and order are limited resulting in
poor assembling efficiency.
[0012] Further, in the foregoing conventional structure, during the
operation of the hermetic compressor being stopped, the lubricating
oil 8 within the recess portion 19a flows out downward via the
communication hole 13a and the vertical hole portion 15 being the
oil feed path. Therefore, there has been possibility of lowering of
reliability such that, upon starting next, sliding is carried out
in a non-oil-feed state until the lubricating oil 8 reaches the
auxiliary bearing 19 having a large head difference, and thus
sliding portions between the auxiliary shaft portion 13 and the
auxiliary bearing 19 are subjected to lubrication failure to cause
abrasion.
[0013] Further, in a hermetic motor that is inverter-driven at a
plurality of operating frequencies including an operating frequency
below a power supply frequency, the foregoing problems are further
increased.
DISCLOSURE OF THE INVENTION
[0014] The present invention solves the foregoing conventional
problems and has an object to provide a hermetic compressor wherein
the energy efficiency is high, the noise or vibration during
operation is low, the assembling performance is excellent, and
further, the reliability is high.
[0015] The present invention is configured that a sealed housing
stores therein lubricating oil and receives therein a motor element
and a compression element driven by said motor element, said
compression element comprising a shaft having an eccentric shaft
portion, and an auxiliary shaft portion and a main shaft portion
coaxially provided on upper and lower sides of said eccentric shaft
portion so as to sandwich it therebetween, a cylinder block
provided with a compression chamber of a substantially cylindrical
shape, a main bearing fixed to or formed integral with said
cylinder block so as to be substantially perpendicular to an axis
of said compression chamber and supporting an upper half portion of
said main shaft portion of said shaft, an auxiliary bearing fixed
to or formed integral with said cylinder block and supporting said
auxiliary shaft portion, a piston that performs reciprocating
motion in said compression chamber, and connecting means for
coupling said piston and said eccentric shaft together, wherein
said shaft is provided with an oil feed mechanism having a lower
end communicating with said lubricating oil and an upper end
penetratingly open to an upper end portion of said auxiliary shaft
portion, and at least one of said auxiliary bearing and said
cylinder block is provided with an oil feed passage for conducting
the lubricating oil discharged from the upper end of said oil feed
mechanism, to a sliding surface of said piston. Therefore, the
lubricating oil having ascended to the auxiliary shaft portion by
means of the oil feed mechanism is dispersed from an upper end
portion of the auxiliary bearing by a centrifugal force due to
rotation of the shaft, and a portion thereof is splashed on the
auxiliary bearing and stored on an upper surface of the auxiliary
bearing. The lubricating oil stored on the upper surface of the
auxiliary bearing is stably and continuously fed to the piston and
the piston pin from the oil feed passage due to gravity, and thus
an action is exhibited that sealing between the piston and the
cylinder block is improved, and metal contacts are reduced to lower
noise and abrasion caused thereby.
[0016] In another mode of the present invention, an oil pool for
storing the lubricating oil is further formed concavely in the oil
feed passage on the upper surface of the auxiliary bearing.
Therefore, an action is exhibited that the lubricating oil once
collected in the oil pool can be stably fed to sliding portions of
the piston etc.
[0017] In another mode of the present invention, an oil dispersion
hole communicating with the oil feed mechanism is further formed in
a substantially horizontal direction at a portion of the auxiliary
shaft portion above the upper surface of the auxiliary bearing.
Therefore, an action is exhibited that even when the revolution
speed of the shaft or the viscosity of the lubricating oil changes,
a direction of the lubricating oil spouting out from the oil
dispersion hole is constant, and thus the dispersed lubricating oil
can be easily recovered so that the lubricating oil can be stably
fed to the sliding portions of the piston etc.
[0018] In another mode of the present invention, an oil fence
projecting upward is provided on the upper surface of the auxiliary
bearing in the vicinity of the oil feed passage. Therefore, the
lubricating oil dispersed from the upper end portion of the
auxiliary shaft portion can be hit upon the oil fence so as to be
collected on the upper surface of the auxiliary bearing, and thus
an action is exhibited that a sufficient amount of the lubricating
oil can be stably fed to the sliding portions of the piston etc.
Further, an action is exhibited that the oil fence serves as an
obstacle to prevent the lubricating oil from being splashed on a
suction muffler located below the compression chamber so that the
temperature rise of the suction muffler can be prevented.
[0019] In another mode of the present invention, an opening portion
is further provided, wherein the opening portion communicates with
the oil feed passage provided on the upper surface of the auxiliary
bearing and is open above an oil feed passage provided at a portion
of the cylinder block above the compression chamber. Therefore, an
action is exhibited that the lubricating oil having flown to the
lower surface of the auxiliary bearing from the opening portion of
the oil feed passage passes through the oil feed passage on the
cylinder block, or directly drops to the piston and the piston pin
so that the lubricating oil can be stably fed to the sliding
portions of the piston etc.
[0020] In another mode of the present invention, an oil guide
projecting downward is provided in the vicinity of the opening
portion on the side of a lower end surface of the auxiliary
bearing. Therefore, an action is exhibited that the lubricating oil
having flown to the opening portion of the oil feed passage at the
lower surface of the auxiliary bearing does not flow in unspecified
directions, but drops to the piston and the piston pin along the
oil guide, so that the oil feed to the position of the piston pin
can be securely and stably carried out.
[0021] In another mode of the present invention, a cylindrical
piston pin fixed to the piston and coupling a connecting rod being
connecting means and the piston together is further provided, and
the opening portion is located right above the piston pin in the
vicinity of a bottom dead center of the piston and is larger than a
horizontal section of the piston pin. Therefore, when the auxiliary
bearing is fixed to the cylinder block in advance, or is formed
integral therewith, it is possible to pass the connecting rod
through the eccentric portion after inserting the auxiliary shaft
into the auxiliary bearing, then insert the piston into the
cylinder block, finally insert the piston pin into the piston from
an upper portion of the opening portion of the oil feed passage and
couple the connecting rod and the piston together, and thus an
action is exhibited that the assembling can be carried out in good
order so that the working efficiency is improved.
[0022] In another mode of the present invention, a cylinder
communicating hole having one end communicating with and open to an
upper portion in the compression chamber of the cylinder block is
provided in the oil feed passage. Therefore, inasmuch as the
cylinder communicating hole is almost sealed by the piston, the
lubricating oil is retained in the oil feed passage even during
being stopped, and thus an action is exhibited that the feed of the
lubricating oil to the piston and the piston pin is started
simultaneously with the start-up so that sealing between the piston
and the cylinder block is improved, and metal contacts are reduced
to lower noise and abrasion caused thereby.
[0023] Another mode of the present invention is characterized in
that a substantially annular oil feed groove communicating with the
oil feed passage in the vicinity of a bottom dead center of the
piston is further formed concavely on an outer periphery of the
piston. Therefore, the lubricating oil is fed to the oil feed
groove when the piston is near the bottom dead center, and the
lubricating oil is fed between the piston and the cylinder block
during a compression stroke, and thus an action is exhibited that
sealing between the piston and the cylinder block is improved, and
metal contacts are reduced to lower noise and abrasion caused
thereby.
[0024] In another mode of the present invention, an oil bath
communicating with sliding surfaces between the auxiliary shaft
portion and the auxiliary bearing is further formed around the
auxiliary shaft portion. Therefore, since a lower portion of the
oil bath is almost sealed by the auxiliary shaft portion, the
lubricating oil dispersed from the upper end portion of the
auxiliary shaft portion and stored in the oil bath remains in the
oil bath even during being stopped so that an action is exhibited
that the feed of the lubricating oil to the auxiliary shaft portion
is started simultaneously with the start-up, and thus lubricity of
the auxiliary shaft portion and the auxiliary bearing immediately
after the start-up is improved.
[0025] In another mode of the present invention, an oil feed hole
is formed on the auxiliary shaft portion, wherein the oil feed hole
establishes communication between the oil bath and the oil feed
mechanism and has a bottom surface located above a bottom surface
of the oil bath. Therefore, an action is exhibited that the
lubricating oil can be stably fed to the oil bath from the oil feed
hole, and a portion of the lubricating oil remains in the oil bath
even during being stopped so that the lubricating oil can be fed to
the auxiliary shaft portion constantly stably from the start-up to
the stopping.
[0026] In another mode of the present invention, a portion of the
oil feed passage is formed in the auxiliary bearing, and an oil
feed hole establishing communication between the oil feed passage
and the oil feed mechanism at least once during one rotation of the
shaft is formed in the auxiliary shaft portion. Therefore, since
the lubricating oil having ascended to the auxiliary shaft portion
by means of the oil feed mechanism flows directly into the oil feed
passage from the oil feed hole, an action is exhibited that even
when the revolution speed of the shaft or the viscosity of the
lubricating oil changes, the lubricating oil can be stably fed to
the piston and the piston pin.
[0027] In another mode of the present invention, an oil fence
projecting upward is provided on a surface of the cylinder block
above the compression chamber, and the oil feed passage is formed
in the surface of the cylinder block above the compression chamber.
Therefore, an action is exhibited that since the lubricating oil
dispersed from the upper end portion of the auxiliary shaft portion
can be hit upon the oil fence so as to be collected on the upper
surface of the cylinder block, a sufficient amount of the
lubricating oil can be stably fed to the sliding portions of the
piston etc. and, since the cylinder block is cooled to lower a
temperature thereof, the temperature rise of gaseous refrigerant
sucked into the compression chamber is suppressed to reduce a heat
receiving loss.
[0028] Further, an action is exhibited that the oil fence serves as
an obstacle to prevent the lubricating oil from being splashed on a
suction muffler located below the compression chamber so that the
temperature rise of the suction muffler can be prevented.
[0029] In another mode of the present invention, further, it is
inverter-driven at a plurality of operating frequencies including
at least an operating frequency lower than a power supply
frequency. Therefore, an action is exhibited that the consumption
power amount is reduced by reduction in compression load due to the
low operating frequency.
[0030] In another mode of the present invention, further, the
operating frequency lower than the power supply frequency includes
at least an operating frequency lower than 30 Hz. Therefore, an
action is exhibited that the consumption power amount can be
further reduced by reduction in compression load due to the low
operating frequency lower than 30 Hz.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] FIG. 1 is a longitudinal sectional view of a hermetic
compressor according to an embodiment 1 of the present
invention;
[0032] FIG. 2 is a plan sectional view of the same embodiment;
[0033] FIG. 3 is a sectional view of the main part of the same
embodiment;
[0034] FIG. 4 is a sectional view of the main part of a hermetic
compressor according to an embodiment 2 of the present
invention;
[0035] FIG. 5 is a sectional view of the main part of a hermetic
compressor according to an embodiment 3 of the present
invention;
[0036] FIG. 6 is a sectional view of the main part of a hermetic
compressor according to an embodiment 4 of the present
invention;
[0037] FIG. 7 is a sectional view of the main part of a hermetic
compressor according to an embodiment 5 of the present
invention;
[0038] FIG. 8 is a longitudinal sectional view of a conventional
hermetic compressor;
[0039] FIG. 9 is a plan view of the conventional hermetic
compressor;
[0040] FIG. 10 is a sectional view of a lower portion of a
conventional shaft; and
[0041] FIG. 11 is a sectional view of the main part of a
conventional auxiliary shaft.
BEST MODE FOR CARRYING OUT THE INVENTION
[0042] Hereinbelow, description will be given about embodiments of
compressors according to the present invention. The same symbols
are assigned to those structures that are the same as the
conventional ones, thereby to omit detailed description
thereof.
EMBODIMENT 1
[0043] FIG. 1 is a longitudinal sectional view of a hermetic
compressor according to the embodiment 1 of the present invention,
and FIG. 2 is a plan sectional view of the same embodiment. FIG. 3
is a sectional view of the main part of the same embodiment.
[0044] In FIGS. 1, 2 and 3, 101 denotes a sealed housing, and 102
denotes a space within the sealed housing. The sealed housing 101
receives therein a motor element 105 comprising a stator 103 having
a coil portion 103a and a rotor 104, and a compression element 106
driven by the motor element 105. The motor element 105 is
inverter-driven and can freely change a revolution speed. 108
denotes lubricating oil stored within the sealed housing 101.
[0045] 110 denotes a shaft having a main shaft portion 111 where
the rotor 105 is press-fitted and fixed, an eccentric portion 112
formed eccentrically to the main shaft portion 111, and an
auxiliary shaft portion 113 provided coaxially with the main shaft
portion 111.
[0046] Inside the shaft 110, an oil feed mechanism 114 is provided
having one end communicating into the lubricating oil 108 and the
other end communicating with an upper end portion of the shaft 110
as a vertical hole portion 115. 116 denotes a cylinder block having
a compression chamber 117 of a substantially cylindrical shape and
a main bearing 118 supporting the main shaft portion 111, and
having at an upper portion thereof an auxiliary bearing 119 fixed
thereto for supporting the auxiliary shaft portion 113. 120 denotes
a piston inserted into the compression chamber 117 so as to be
reciprocatingly slidable therein, and coupled to the eccentric
portion 112 by a connecting means 121 and a piston pin 122. 123
denotes a suction muffler having one end communicating with the
inside of the compression chamber 117, and the other end
communicating with the space 102 within the sealed housing. 124
denotes an opening portion communicating with an upper surface of
the auxiliary bearing 119 and being open above the piston 120.
[0047] 125 denotes an oil pool formed concavely on the upper
surface of the auxiliary bearing 119 for storing the lubricating
oil 125. 126 denotes an oil fence formed integral with the
auxiliary bearing 119 so as to project upward in the vicinity of
the oil pool 125. 127 denotes an oil dispersion hole formed in a
substantially horizontal direction at a portion of the auxiliary
shaft portion 113 above the upper surface of the auxiliary bearing
119, and communicating with the oil feed mechanism 114.
[0048] 128 denotes an oil guide projecting downward in the vicinity
of the opening portion, on the side of a lower end surface of the
auxiliary bearing 119. 129 denotes an oil feed passage for
conducting the lubricating oil 108 discharged from the upper end of
the oil feed mechanism 114, to a sliding surface of the piston 120,
and including the oil dispersion hole 127, the oil pool 125, the
oil fence 126, the opening portion 124 and the oil guide 128 in its
structure. Further, a portion of the oil feed passage 129 is also
formed in the cylinder block 116 over the compression chamber
117.
[0049] Refrigerants for use in the present compressor are
hydrocarbon refrigerants etc. that are natural refrigerants with
low warming coefficients represented by R134a and R600a whose ozone
destruction coefficients are zero, and are used in combination with
compatible lubricating oils, respectively.
[0050] With respect to the hermetic compressor thus structured, an
operation thereof will be described hereinbelow.
[0051] Through rotation of the shaft 110, the oil feed mechanism
114 has a pump capability generated by a centrifugal force etc., so
that the lubricating oil 108 at the bottom portion of the sealed
housing 101 is drawn upward passing through the oil feed mechanism
114. As shown in FIG. 3, the lubricating oil 108 drawn up into an
upper portion of the vertical hole portion 115 forming an upper
portion of the oil feed mechanism 114 is dispersed due to the
centrifugal force caused by the rotation of the shaft 110 so as to
be splashed on the inner surface of the sealed housing 101 like in
the conventional one, while a portion thereof is splashed on the
auxiliary bearing 119 and stored in the oil pool 125 formed on the
upper surface thereof. The lubricating oil 108 stored in the oil
pool 125 is fed to the piston 120 and the piston pin 122 by
directly dropping from the opening portion 124 due to gravity or
moving along a wall surface of the cylinder block 116, and further
enters between the piston 120 and the cylinder block 116 due to
reciprocating motion of the piston 120. Therefore, the sealing
performance by the lubricating oil 108 is enhanced so that the
amount of leakage of refrigerant gas from the compression chamber
117 into the space 102 within the sealed housing is reduced,
thereby improving the freezing capability or efficiency. Further,
metal contacts of sliding portions between the piston 120 and the
cylinder block 116 and sliding portions of the piston pin 122 are
prevented to achieve excellent lubrication, so that the noise
caused by the sliding is lowered and the reliability is
improved.
[0052] Further, by providing the oil fence 126, the lubricating oil
108 dispersed from the upper portion of the auxiliary shaft portion
113 hits the oil fence 126 so as to be collected into the oil pool
125 formed on the upper surface of the auxiliary bearing 119.
Therefore, a further sufficient amount of the lubricating oil 108
can be stably fed to the piston 120 and the piston pin 122.
Further, by the provision of the oil fence 126, the lubricating oil
108 is not splashed on the suction muffler 123 located under the
compression chamber 117, so that the temperature rise of the
suction gas following the temperature rise of the suction muffler
123 can be prevented, and thus the freezing capability or
efficiency can be enhanced.
[0053] Further, by providing the oil dispersion hole 127, even when
the revolution speed of the shaft 110 or the viscosity of the
lubricating oil 108 is changed, a direction of the lubricating oil
108 spouting out from the oil dispersion hole 127 is stably fixed
to a substantially horizontal direction. Therefore, the lubricating
oil 108 can be securely hit upon the oil fence 126 so that the
lubricating oil 108 can be stably fed to the piston 120 and the
piston pin 122.
[0054] Further, the lubricating oil 108 having flown to a lower end
portion of the opening 124, at the lower surface of the auxiliary
bearing 119, of the oil feed passage 129 drops to the piston 120
and the piston pin 122 along the oil guide 128. Therefore, the
lubricating oil 108 does not flow in unspecified directions along
the lower surface of the auxiliary bearing 119, so that the oil
feed to the sliding surface of the piston or the piston pin can be
securely and stably carried out.
[0055] When the opening portion 124 of the oil feed passage 129 at
the lower surface of the auxiliary bearing 119 and the cylinder
block 116 are adjacent to each other, the lubricating oil 108
having flown to the opening portion 124 of the oil feed passage 129
at the lower surface of the auxiliary bearing 119 continuously
flows as it is to the cylinder block 116 therealong. Accordingly,
as compared with the case of discontinuously dropping in the form
of drops, the oil feed to the piston 120 and the piston pin 122 can
be continuously and securely carried out, and further, the oil also
flows over the surface of the cylinder block 116 to achieve a
cooling effect.
[0056] In this embodiment, a control is performed such that a
relatively high operating frequency such as 60 Hz is used initially
upon starting to enhance the oil feed capability so as to store the
lubricating oil 108 in the oil pool 125, then a low operating
frequency such as 25 Hz is used for carrying out an energy saving
operation depending on a load of the refrigerating cycle.
[0057] The action achieved by the foregoing structure is universal
irrespective of a kind of refrigerant and lubricating oil combined
therewith.
EMBODIMENT 2
[0058] FIG. 4 is a sectional view of the main part according to the
embodiment 2 of the present invention. A basic structure of a
hermetic compressor in this embodiment is the same as the contents
shown in FIGS. 1 and 2.
[0059] In FIG. 4, 130 denotes an opening portion that is provided
in an auxiliary bearing 132 as a portion of an oil feed passage 131
leading lubricating oil 108 discharged from an upper end of an oil
feed mechanism 114, to a sliding surface of a piston 120, and that
is located right above a piston pin 122 in the vicinity of a bottom
dead center of the piston 120, and has a section larger than a
horizontal section of the piston pin 122.
[0060] With respect to the compressor thus structured, an operation
thereof will be described hereinbelow.
[0061] When the auxiliary bearing is fixed to a cylinder block 116
in advance, or when the auxiliary bearing 132 is formed integral
with the cylinder block 116, the order of assembling is such that
an auxiliary shaft 113 of a shaft 110 is first passed through a
connecting rod 121, and subsequently through the auxiliary bearing
132. Thereupon, when the piston 120 and the connecting rod 121 are
joined together by the piston pin 122, and further, the piston 120
is inserted into the cylinder block 116, the degree of freedom of
the connecting rod 121 is small so that insertion of the auxiliary
shaft 113 into the auxiliary bearing 132 and insertion of an
eccentric portion 112 into the connecting rod 121 should be
performed simultaneously, and thus the assembling becomes
difficult. However, in the present invention, it is possible to
pass the connecting rod 121 through the eccentric portion 112 after
inserting the auxiliary shaft 113 into the auxiliary bearing 132,
then insert the piston 120 into the cylinder block 116, finally
insert the piston pin 122 into the piston 120 from an upper portion
of the opening portion of the oil feed passage 131 and couple the
connecting rod 121 and the piston 120 together. Therefore, the
assembling can be carried out in good order so that the working
efficiency is improved.
EMBODIMENT 3
[0062] FIG. 5 is a sectional view of the main part according to the
embodiment 3 of the present invention. A basic structure of a
hermetic compressor in this embodiment is the same as the contents
shown in FIGS. 1 and 2.
[0063] In FIG. 5, 133 denotes a cylinder communicating hole having
one end communicating with an oil pool 125, and a lower end
communicating with and open to an upper portion in a compression
chamber 117 of a cylinder block 116. 134 denotes a substantially
annular oil feed groove communicating with the cylinder
communicating hole 133 in the vicinity of a bottom dead center of a
piston 120 and formed concavely on the outer periphery of the
piston 120.
[0064] 135 denotes an auxiliary bearing fixed to the cylinder block
116 and supporting an auxiliary shaft portion 113. 136 denotes an
oil bath communicating with sliding surfaces between the auxiliary
shaft portion 113 and the auxiliary bearing 135 and formed around
the auxiliary shaft portion 113. 137 denotes an oil feed hole
formed on the auxiliary shaft portion 113 for establishing
communication between the oil bath 136 and an oil feed mechanism
114, and having a bottom surface located above a bottom surface of
the oil bath 136.
[0065] 138 denotes an oil feed passage for conducing lubricating
oil 108 discharged from an upper end of the oil feed mechanism 114,
to a sliding surface of the piston 120, and formed by an oil
dispersion hole 127, the oil pool 125, an oil fence 126 and the
cylinder communicating hole 133.
[0066] With respect to the compressor thus structured, an operation
thereof will be described hereinbelow.
[0067] Lubricating oil 108 in the oil feed passage 138 flows into
the cylinder communicating hole 133, but a lower end portion of the
cylinder communicating hole 133 is almost sealed by the piston 120.
Accordingly, the lubricating oil 108 remains within the cylinder
communicating hole 133 even during being stopped. Therefore, the
lubricating oil 108 remaining in the cylinder communicating hole
133 is fed between the piston 120 and the cylinder block 116
simultaneously with the starting so that the sealing between the
piston 120 and the cylinder block 116 becomes good immediately
after the starting. Thus, the amount of leakage of refrigerant gas
from the compression chamber 117 into the space 102 within the
sealed housing is lowered so that the freezing capability or
efficiency is improved. Further, metal contacts of sliding portions
between the piston 120 and the cylinder block 116 and sliding
portions of the piston pin 122, which are liable to occur
immediately after the starting, are reduced so that the noise
caused by the sliding is lowered and the reliability is
improved.
[0068] Further, the lubricating oil 108 is fed to the oil feed
groove 134 when the piston 120 is near the bottom dead center, and
the lubricating oil 108 is fed between the piston 120 and the
cylinder block 116 during a compression stroke. By this action, the
sealing between the piston 120 and the cylinder block 116 by the
lubricating oil 108 is further improved, and the amount of leakage
of refrigerant gas from the compression chamber 117 into the space
102 within the sealed housing is further lowered so that the
freezing capability or efficiency is improved. Further, metal
contacts of the sliding portions between the piston 120 and the
cylinder block 116 are further reduced so that the noise caused by
the sliding is further lowered and the reliability is further
improved.
[0069] On the other hand, a portion of the lubricating oil 108
having ascended to the auxiliary shaft portion 113 by means of the
oil feed mechanism 114 passes through the oil feed hole 137 to be
stored in the oil bath 136, so that the lubricating oil 108 is fed
to sliding surfaces of the auxiliary shaft portion 113 and the
auxiliary bearing 135. A lower portion of the oil bath 136 is in
the state of being almost sealed by the auxiliary shaft portion
113, and further, the bottom surface of the oil feed hole 137 is
located above the bottom surface of the oil bath 136, so that the
lubricating oil 108 only slightly flows out from the oil bath 136
during being stopped, and thus remains in the oil bath 136.
Therefore, the lubricating oil 108 can be fed to the auxiliary
shaft portion 113 simultaneously with the starting, and thus metal
contacts of the sliding portions between the auxiliary shaft
portion 113 and the auxiliary bearing 135 immediately after the
starting are reduced so that the noise caused by the sliding is
lowered and the reliability is improved.
[0070] Being inverter-driven using low operating frequencies lower
than the power supply frequency, it takes the lubricating oil 108 a
long time to reach the auxiliary shaft portion 113 upon starting so
that a non-oil-feed state is liable to occur during that time.
However, in the foregoing structure, inasmuch as the lubricating
oil 108 can be fed to the auxiliary shaft portion 113
simultaneously with the starting, the effect is further
increased.
[0071] Further, like in the case of performing an operation using
an extremely low frequency lower than 30 Hz after the lubricating
oil 108 has been stored in the oil pool 125 and the oil bath 136,
even when the pump capability by means of the oil feed mechanism
114 is low so that a long time is required for the lubricating oil
108 to reach the upper end portion of the auxiliary shaft portion
113, the lubricating oil 108 is fed to the auxiliary bearing 135
and the piston 120 from the oil bath 136 and the oil pool 125
during that time, respectively. Therefore, inasmuch as an operation
with a lower operating frequency is made possible, the pressure
load condition in the freezing system is lightened so that it
becomes possible to further reduce the consumption power amount of
the compressor.
[0072] The action achieved by the foregoing structure is universal
irrespective of a kind of refrigerant and lubricating oil combined
therewith.
EMBODIMENT 4
[0073] FIG. 6 is a sectional view of the main part according to the
embodiment 4 of the present invention. A basic structure of a
hermetic compressor in this embodiment is the same as the contents
shown in FIGS. 1 and 2.
[0074] In FIG. 6, 139 denotes an oil feed passage for conducting
lubricating oil 108 discharged from an upper end of an oil feed
mechanism 114, to a sliding surface of a piston 120. A portion of
the oil feed passage 139 is formed inside an auxiliary bearing 140,
while the oil feed passage 139 further communicates with the inside
of a cylinder block 116 and has an open end over the piston 120.
141 denotes an oil feed hole that establishes communication between
the oil feed passage 139 and the oil feed mechanism 114 at least
once during one rotation of a shaft 110, and is formed in an
auxiliary shaft portion 113.
[0075] With respect to the compressor thus structured, an operation
thereof will be described hereinbelow.
[0076] The lubricating oil 108 having ascended to the auxiliary
shaft portion 113 by means of the oil feed mechanism 114 flows
directly into the oil feed passage 139 from the oil feed hole 141,
and thus, even when the revolution speed of the shaft 110 or the
viscosity of the lubricating oil 108 is changed, the lubricating
oil 108 can be stably and securely fed to the piston 120 and the
piston pin 122.
[0077] Therefore, the sealing between the piston 120 and the
cylinder block 116 is improved, and thus the amount of leakage of
refrigerant gas from the compression chamber 117 into the space 102
within the sealed housing is lowered so that the freezing
capability or efficiency is improved. Further, metal contacts of
sliding portions between the piston 120 and the cylinder block 116
and sliding portions of the piston pin 122, which are liable to
occur immediately after the starting, are reduced so that the noise
caused by the sliding is lowered and the reliability is
improved.
EMBODIMENT 5
[0078] FIG. 7 is a sectional view of the main part according to the
embodiment 5 of the present invention. A basic structure of a
hermetic compressor in this embodiment is the same as the contents
shown in FIGS. 1 and 2.
[0079] In FIG. 7, 142 denotes an oil fence formed so as to project
upward on a surface of a cylinder block 116 above a compression
chamber 117, and 143 denotes an oil feed passage for conducting
lubricating oil 108 discharged from an upper end of an oil feed
mechanism 114, to a sliding surface of a piston 120, wherein a
portion thereof is formed in the surface of the cylinder block 116
above the compression chamber 117. 144 denotes an auxiliary bearing
fixed to the cylinder block 116 and supporting an auxiliary shaft
portion 113.
[0080] With respect to the compressor thus structured, an operation
thereof will be described hereinbelow.
[0081] A portion of the lubricating oil 108 having ascended to the
auxiliary shaft portion 113 by means of the oil feed mechanism 114
is dispersed from an upper end portion of the auxiliary shaft
portion 113 to hit the oil fence 142 and flows over an upper
surface of the cylinder block 116 along the oil feed passage 143 so
as to be fed to the piston 120 and a piston pin 122. In this event,
since the cylinder block 116 is cooled by the lubricating oil 108
to lower a temperature thereof, the temperature rise of gaseous
refrigerant sucked into the compression chamber 117 is suppressed
to reduce a heat receiving loss, so that the freezing capability or
efficiency is increased. Further, it is possible to prevent seizure
etc. of sliding portions between the piston 120 and the cylinder
block 116 owing to the lowering of temperature of the cylinder
block 116, so that the reliability is improved.
[0082] Further, by the provision of the oil fence 142, there is
almost no lubricating oil 108 that is splashed on the suction
muffler 123 located below the compression chamber 117, so that the
temperature rise of suction gas following the temperature rise of
the suction muffler 123 can be prevented, and thus the freezing
capability or efficiency can be enhanced.
INDUSTRIAL APPLICABILITY
[0083] As described above, the present invention is configured that
the shaft is provided with an oil feed mechanism having a lower end
communicating with the lubricating oil and an upper end
penetratingly open to an upper end portion of the auxiliary shaft
portion, and at least one of the auxiliary bearing and the cylinder
block is provided with an oil feed passage for conducting the
lubricating oil discharged from the upper end of the oil feed
mechanism, to a sliding surface of the piston. Therefore, the
lubricating oil is stably fed to the piston and the piston pin from
the oil feed passage, so that the freezing capability or efficiency
is improved, the noise caused by the sliding of the piston and the
piston pin is lowered, and the reliability is further improved.
[0084] In another mode of the present invention, an oil pool for
storing the lubricating oil is further formed concavely in the oil
feed passage on the upper surface of the auxiliary bearing.
Therefore, a sufficient amount of the lubricating oil can be stably
fed to the piston, so that the freezing capability or efficiency is
improved, the noise caused by the sliding of the piston and the
piston pin is lowered, and the reliability is further improved.
[0085] In another mode of the present invention, an oil dispersion
hole communicating with the oil feed mechanism is further formed in
a substantially horizontal direction at a portion of the auxiliary
shaft portion above the upper surface of the auxiliary bearing.
Therefore, even when the revolution speed of the shaft or the
viscosity of the lubricating oil changes, a direction of the
lubricating oil spouting out from the oil dispersion hole is
constant, and thus the dispersed lubricating oil can be easily
recovered. Thus, the lubricating oil can be stably fed to the
piston and the piston pin, so that the freezing capability or
efficiency is improved, the noise caused by the sliding of the
piston and the piston pin is lowered, and the reliability is
further improved.
[0086] In another mode of the present invention, an oil fence
projecting upward is provided on the upper surface of the auxiliary
bearing in the vicinity of the oil feed passage. Therefore, the
lubricating oil can be collected on the upper surface of the
auxiliary bearing, so that a sufficient amount of the lubricating
oil can be stably fed to the piston, and further, the temperature
rise of suction gas following the temperature rise of a suction
muffler due to the lubricating oil can be prevented. Accordingly,
the freezing capability or efficiency is improved, the noise caused
by the sliding of the piston and the piston pin is lowered, and the
reliability is further improved.
[0087] In another mode of the present invention, an opening portion
is provided, wherein the opening portion communicates with the oil
feed passage provided on the upper surface of the auxiliary bearing
and is open above an oil feed passage provided at a portion of the
cylinder block above the compression chamber. Therefore, the
lubricating oil drops to the piston and the piston pin via the oil
feed passage on the cylinder block or directly to enable the oil
feed, so that the oil feed to the piston and the piston pin can be
securely carried out, and a cooling effect is obtained by the
lubricating oil flowing on the surface of the cylinder block.
Accordingly, the freezing capability or efficiency is improved, the
noise caused by the sliding of the piston and the piston pin is
lowered, and the reliability is further improved.
[0088] In another mode of the present invention, an oil guide
projecting downward is provided in the vicinity of the opening
portion on the side of a lower end surface of the auxiliary
bearing. Therefore, the oil feed can be securely and stably
implemented relative to the sliding portions of the piston as
aimed, so that the freezing capability or efficiency is improved,
the noise caused by the sliding of the piston and the piston pin is
lowered, and the reliability is further improved.
[0089] In another mode of the present invention, a cylindrical
piston pin fixed to the piston and coupling a connecting rod being
connecting means and the piston together is further provided, and
the opening portion is located right above the piston pin in the
vicinity of a bottom dead center of the piston and is larger than a
horizontal section of the piston pin. Therefore, when the auxiliary
bearing is fixed to the cylinder block in advance, or is formed
integral therewith, the assembling is easy because it is not
necessary to simultaneously perform the insertion of the auxiliary
shaft into the auxiliary bearing and the insertion of the eccentric
portion into the connecting rod, so that the assembling can be
carried out in good order, and thus the working efficiency is
improved.
[0090] In another mode of the present invention, a cylinder
communicating hole having one end communicating with and open to an
upper portion in the compression chamber of the cylinder block is
provided in the oil feed passage. Therefore, the amount of leakage
of refrigerant gas from the compression chamber is reduced
immediately after the start-up to improve the freezing capability
or efficiency. Further, metal contacts of the sliding portions of
the piston and the piston pin are prevented immediately after the
start-up to provide excellent lubrication, so that the noise caused
by the sliding is lowered and the reliability is improved.
[0091] Another mode of the present invention is characterized in
that a substantially annular oil feed groove communicating with the
oil feed passage in the vicinity of a bottom dead center of the
piston is further formed concavely on an outer periphery of the
piston. Therefore, following the improvement in sealing
performance, there are obtained effects in improvement of the
freezing capability or efficiency and improvement of the
reliability of the sliding portions.
[0092] In another mode of the present invention, an oil bath
communicating with sliding surfaces between the auxiliary shaft
portion and the auxiliary bearing is further formed around the
auxiliary shaft portion. Therefore, the lubricating oil can be fed
to the auxiliary shaft portion simultaneously with the start-up,
and thus the lubrication of the sliding portions between the
auxiliary shaft portion and the auxiliary bearing is made
excellent, so that the noise caused by the sliding is lowered and
the reliability is improved.
[0093] In another mode of the present invention, an oil feed hole
is formed on the auxiliary shaft portion, wherein the oil feed hole
establishes communication between the oil bath and the oil feed
mechanism and has a bottom surface located above a bottom surface
of the oil bath. Therefore, the lubricating oil can be fed to the
auxiliary shaft portion constantly stably from the start-up to the
stopping.
[0094] In another mode of the present invention, a portion of the
oil feed passage is formed in the auxiliary bearing, and an oil
feed hole establishing communication between the oil feed passage
and the oil feed mechanism at least once during one rotation of the
shaft is formed in the auxiliary shaft portion. Therefore, even
when the revolution speed of the shaft or the viscosity of the
lubricating oil changes, the lubricating oil can be stably fed to
the sliding surfaces between the auxiliary shaft portion and the
auxiliary bearing, the piston and the piston pin.
[0095] In another mode of the present invention, an oil fence
projecting upward is provided on a surface of the cylinder block
above the compression chamber, and the oil feed passage is formed
in the surface of the cylinder block above the compression chamber.
Therefore, a heat receiving loss is reduced so that the freezing
capability or efficiency is increased and the reliability is
improved. Further, the temperature rise of suction gas following
the temperature rise of the suction muffler can be prevented so
that the freezing capability or efficiency is enhanced.
[0096] In another mode of the present invention, further, it is
inverter-driven at a plurality of operating frequencies including
at least an operating frequency lower than a power supply
frequency. Therefore, the consumption power amount of the
compressor is reduced.
[0097] In another mode of the present invention, further, the
operating frequency lower than the power supply frequency includes
at least an operating frequency lower than 30 Hz. Therefore,
inasmuch as the operation at a lower operating frequency is made
possible, the consumption power amount is further reduced.
* * * * *