Note: Descriptions are shown in the official language in which they were submitted.
CA 02787319 2012-07-17
1
DESCRIPTION
Title of the Invention: FLUID MACHINE
Technical Field
[0001] The present invention relates to fluid machines,
and more particularly, to a fluid machine suitable for use
as a hermetic type reciprocating compressor for compressing
a carbon dioxide refrigerant.
Background Art
[0002] As a fluid machine of this type, a hermetic type
compressor has been known which is provided with a hermetic
container storing lubricating oil in an inside bottom
thereof, an electric motor arranged inside the hermetic
container, a compression mechanism arranged inside the
hermetic container and including a piston driven by the
electric motor through a rotary shaft and a cylinder block
having a cylinder bore formed therein, the piston being
reciprocated within the cylinder bore to draw in and
discharge a working fluid, and a lubrication mechanism
configured to utilize centrifugal force produced by
rotation of the rotary shaft, to supply the lubricating oil
stored in the inside bottom of the hermetic container to an
upper region in the hermetic container.
[0003] Patent Document 1 discloses a hermetic type
compressor in which an oil feed hole is formed in the
cylinder block to connect the cylinder bore to the outside
of the cylinder bore, and an annular groove is formed in
the outer peripheral surface of the piston. When the
piston is at its bottom dead center, the oil feed hole
communicates with the annular groove, and when the piston
is at it top dead center, the oil feed hole communicates
with the cylinder bore.
Prior Art Literature
CA 02787319 2012-07-17
2
Patent Document
[0004] Patent Document 1: Japanese Laid-open Patent
Publication No. 2009-197684
Summary of the Invention
Problems to be Solved by the Invention
[0005] The above conventional technique permits the
lubricating oil to be effectively supplied to the piston or
cylinder bore and also enables lubrication of the gap
between the piston and the cylinder block. No special
consideration is, however, given to localized lubrication
of a connecting rod coupling the rotary shaft to the piston
and of a piston pin coupling the connecting rod to the
piston. Thus, there still is a demand for improvement in
the lubrication performance and reliability of fluid
machines.
[0006] The present invention was created in view of the
above circumstances, and an object thereof is to provide a
fluid machine improved in lubrication performance and
reliability.
Means for Solving the Problems
[0007] To achieve the object, the present invention
provides a fluid machine comprising: a hermetic container
storing lubricating oil in an inside bottom thereof; a
driving unit arranged inside the hermetic container; a
driven unit arranged inside the hermetic container and
including a piston driven by the driving unit through a
rotary shaft and a cylinder block having a cylinder bore
formed therein, the piston being reciprocated within the
cylinder bore to draw in and discharge a working fluid; a
lubrication mechanism configured to utilize the rotary
shaft to supply the lubricating oil stored in the inside
bottom to an upper region in the hermetic container; a
frame secured to the hermetic container and disposed in
CA 02787319 2012-07-17
3
contact with an upper surface of the cylinder block to
support the driven unit, the frame having an upper surface
onto which the lubricating oil supplied to the upper region
in the hermetic container flows down; a connecting rod
arranged under the frame and coupling the rotary shaft to
the piston; a piston pin coupling the connecting rod to the
piston; a first oil feed hole formed through the frame and
the cylinder block; and a second oil feed hole formed
through the frame (claim 1).
[0008] When the piston is at a bottom dead center
thereof, the first oil feed hole is located immediately
above the piston pin and the second oil feed hole is
located immediately above the connecting rod (claim 2).
When the piston is at a top dead center thereof, the
first and second oil feed holes are located immediately
above the connecting rod (claim 3).
The frame has oil reservoir sections formed by spot-
facing respective openings of the first and second oil feed
holes (claim 4).
[0009] The connecting rod has an oil groove formed in an
upper surface thereof and extending from a location near
the rotary shaft to a vicinity of the piston pin (claim 5).
Pressure of the working fluid drawn into and
discharged from the driven unit prevails in an interior of
the hermetic container, and the working fluid is a carbon
dioxide refrigerant (claim 6).
Advantageous Effects of the Invention
[0010] The fluid machine according to claim 1 is
provided with the first and second oil feed holes, and the
first and second oil feed holes allow the lubricating oil
to reliably drop onto the piston, the piston pin and the
connecting rod, which are arranged under the frame. This
is because the frame is secured to the hermetic container
CA 02787319 2012-07-17
4
and the lubricating oil that flows from the upper region in
the hermetic container down to the upper surface of the
frame is not acted upon by the centrifugal force produced
by the rotation of the rotary shaft. Accordingly, the
lubricating oil can effectively lubricate the driven unit
without being influenced by the centrifugal force, whereby
the lubrication performance and reliability of the fluid
machine can be improved.
[0011] According to the invention of claim 2, when the
piston is at the bottom dead center, the first oil feed
hole is located immediately above the piston pin, and the
second oil feed hole is located immediately above the
connecting rod. Accordingly, when the piston is at the
bottom dead center and thus the pressure of the working
fluid in the cylinder bore is low, the lubricating oil can
be made to drop from the first and second oil feed holes
directly onto the piston pin and the connecting rod,
respectively, without being influenced by the pressure of
the working fluid slightly leaking from the cylinder bore.
The driven unit can therefore be lubricated more
effectively, making it possible to further improve the
lubrication performance of the fluid machine.
[0012] According to the invention of claim 3, when the
piston is at the top dead center, the first and second oil
feed holes are located right above the connecting rod.
Thus, also when the piston is at the top dead center and
thus the working fluid pressure in the cylinder bore is
high, the lubricating oil can be made to drop from the
first and second oil feed holes directly at least onto the
connecting rod. The driven unit can therefore be
lubricated more effectively, making it possible to further
improve the lubrication performance of the fluid machine.
[0013] According to the invention of claim 4, the frame
CA 02787319 2012-07-17
has the oil reservoir sections for temporarily storing the
lubricating oil that flows from the upper region in the
hermetic container down to the upper surface of the frame.
It is therefore possible to cause the lubricating oil to
5 intermittently drip little by little, and since the driven
unit can be lubricated more effectively, the lubrication
performance of the fluid machine can be further improved.
[0014] According to the invention of claim 5, the
connecting rod has the oil groove formed in the upper
surface thereof, and the oil groove permits the lubricating
oil dropped from the first and second oil feed holes onto
the connecting rod to be guided to those portions at which
the connecting rod is coupled to the rotary shaft and the
piston pin. Thus, since the driven unit can be lubricated
more effectively, the lubrication performance of the fluid
machine can be further improved.
[0015] According to the invention of claim 6, the
working fluid is a carbon dioxide refrigerant. Where a
carbon dioxide refrigerant is used as the working fluid,
the pressure of the working fluid discharged from the
cylinder bore is high, so that the pressure of the working
fluid leaking from the cylinder bore and prevailing in the
interior of the hermetic container may possibly become
high. Consequently, the lubricating oil dropping, in
particular, from the first oil feed hole directly onto the
piston pin is greatly influenced by the pressure of the
working fluid. With the aforementioned configuration,
however, the driven unit can be effectively lubricated
without the influence of the pressure of the working fluid,
whereby the lubrication performance of the fluid machine
can advantageously be enhanced.
Brief Description of the Drawings
[0016] FIG. 1 is a longitudinal sectional view of a
CA 02787319 2012-07-17
6
compressor according to a first embodiment.
FIG. 2 is an enlarged view of a principal part of a
compression mechanism shown in FIG. 1.
FIG. 3 illustrates lubrication channels in the
compressor of FIG. 1.
FIG. 4 is an enlarged view of the principal part of
the compression mechanism, illustrating lubrication
channels formed when a piston shown in FIG. 1 is at its
bottom dead center.
FIG. 5 is an enlarged view of the principal part of
the compression mechanism, illustrating lubrication
channels formed when the piston in FIG. 1 is at its top
dead center.
Mode of Carrying out the Invention
[0017] FIGS. 1 through 5 illustrate a compressor 1 as a
fluid machine according to a first embodiment.
The compressor 1 is a hermetic type reciprocating
compressor, which is more particularly classified as
displacement type compressor referred to as reciprocating
compressor or piston compressor, and is used as a device
constituting a refrigeration cycle, not shown, incorporated
in an automatic vending machine, for example.
The refrigeration cycle has a path through which a
refrigerant as a working fluid for the compressor 1 is
circulated. For the refrigerant, carbon dioxide, which is
a non-flammable natural refrigerant, is used, for example.
[0018] As illustrated in FIG. 1, the compressor 1 is
provided with a hermetic container 2. The hermetic
container 2 contains an electric motor (driving unit) 4 and
a compression mechanism (driven unit) 6 to which driving
force of the electric motor 4 is transmitted.
The hermetic container 2 has a shell structure
constituted by a top shell 2A covering the electric motor 4
CA 02787319 2012-07-17
7
and a bottom shell 2B joined to the top shell 2A by welding
and surrounding the compression mechanism 6. The electric
motor 4 is housed with its longitudinal axis directed in a
depth direction of the top shell 2A. The top shell 2A has
a depth greater than that of the bottom shell 2B. The
compression mechanism 6, on the other hand, is housed with
its longitudinal axis directed in a radial direction of the
bottom shell 2B. The bottom shell 2B has a smaller depth
than the top shell 2A.
[0019] The electric motor 4 includes a stator 8
configured to generate a magnetic field when supplied with
electric power, and a rotor 10 configured to rotate by the
magnetic field generated by the stator 8. The rotor 10 is
arranged inside the stator 8 coaxially therewith and is
secured by shrink fitting to a main shaft section 24 of a
crankshaft (rotary shaft) 14, described later. The stator
8 is supplied with electric power from outside of the
compressor 1 through electric equipment 12 fixed to the
hermetic container 2, and leads, not shown.
[0020] The compression mechanism 6 includes the
crankshaft 14, a cylinder block 16, a piston 18, and a
connecting rod 20. The crankshaft 14 has an eccentric
shaft section 22 and the main shaft section 24 and is
positioned perpendicularly to the connecting rod 20.
As illustrated in FIG. 2, a cylinder bore 26 is formed
through the cylinder block 16. A cylinder gasket 28, a
suction valve 50, described later, a valve plate 30, a head
gasket 32 and a cylinder head 34 are urgingly fixed, in the
mentioned order from the cylinder block side, to the
cylinder block 16 by bolts, so as to close an outer open
end of the cylinder bore 26.
[0021] The stator 8 shown in FIG. 1 is fixed by bolts to
the cylinder block 16 with a frame 36 therebetween, and the
CA 02787319 2012-07-17
8
frame 36 is secured to the hermetic container 2. The frame
36 is disposed in contact with an upper surface 16a of the
cylinder block 16.
Specifically, the electric motor 4 and the compression
mechanism 6 are supported by a seating section 38 forming a
lower part of the frame 36, and the frame 36 is secured at
the seating section 38 to the hermetic container 2. At a
cylindrical section 40 forming an upper part of the frame
36, on the other hand, a bearing 42 for the main shaft
section 24 is arranged on an inner peripheral surface 40a
of the cylindrical section 40, and a bearing 44 for
receiving thrust load of the rotor 10, such as a thrust
race (bearing) or thrust washer, is arranged on an upper
end face 40b of the cylindrical section 40.
[0022] As illustrated in FIG. 2, the valve plate 30 has
a suction hole 46 and a discharge hole 48 for letting the
refrigerant in and out, respectively. The suction and
discharge holes 46 and 48 are respectively opened and
closed by the suction and discharge valves 50 and 52, each
constituted by a reed valve.
The cylinder head 34 has a suction chamber 54 and a
discharge chamber 56, both for the refrigerant. When the
discharge valve 52 is open during compression stroke of the
piston 18, the discharge chamber 56 communicates with the
cylinder bore 26 through the discharge hole 48. On the
other hand, when the suction valve 50 is open during
suction stroke of the piston 18, the suction chamber 54
communicates with the cylinder bore 26 through the suction
hole 46.
[0023] A suction pipe 58 and a discharge pipe 60 are
fixed to the hermetic container 2 and have one ends
connected to the suction and discharge chambers 54 and 56,
respectively, of the cylinder head 34. The suction and
CA 02787319 2012-07-17
9
discharge pipes 58 and 60 have respective other ends
connected to the refrigeration cycle via a suction muffler
and a discharge muffler, respectively, neither of which is
shown. The mufflers serve to reduce pulsation and noise of
the refrigerant flowing between the compressor 1 and the
refrigeration cycle.
[0024] The connecting rod 20 has one end formed as a
large end portion 62 to which the eccentric shaft section
22 of the crankshaft 14 is rotatably coupled, and has the
other end formed as a small end portion 64 to which the
piston 18 is coupled so as to be capable of reciprocating
motion. The small end portion 64 is coupled to the piston
18 by a piston pin 66, and a fixing pin 68 prevents the
piston pin 66 from coming off the piston 18.
[0025] With the individual parts configured in this
manner, as the crankshaft 14 rotates, the connecting rod 20
makes a rocking motion on the piston pin 66 as a fulcrum,
in conjunction with eccentric rotation of the eccentric
shaft section 22, and the piston 18 makes a reciprocating
motion within the cylinder bore 26 in conjunction with the
rocking motion of the connecting rod 20.
Discharge pressure of the refrigerant mainly prevails
in the interior of the hermetic container 2. A small
amount of lubricating oil for lubricating individual
sliding parts of the electric motor 4 and compression
mechanism 6, such as the bearings 42 and 44, is stored in
an inside bottom 2a of the hermetic container 2.
[0026] An oil passage (lubrication mechanism) 70 is
formed in the crankshaft 14 so as to extend from a nearly
axial center of a lower end face 22a of the eccentric shaft
section 22 up to an intermediate portion of the main shaft
section 24. The oil passage 70 opens, at an upper section
thereof, in an outer peripheral surface 24a of the main
CA 02787319 2012-07-17
shaft section 24, and is connected, at a lower section
thereof, with an oil pipe (lubrication mechanism) 72. The
oil pipe 72 has an inclined portion 74 at a distal end
portion thereof, and the inclined portion 74 is so inclined
5 as to extend from nearly the axial center of the eccentric
shaft section 22 toward the axis of the main shaft section
24. A distal end of the inclined portion 74 of the oil
pipe 72 extends to an oil reservoir 76 formed in the inside
bottom 2a of the hermetic container 2 and having a concave
10 shape as viewed in section.
[0027] The oil reservoir 76 has a size and a depth such
that a small amount, for example, about 200 cc, of
lubricating oil can be stored with its oil level located
above the distal end of the oil pipe 74. As the oil pipe
72 eccentrically rotates together with the eccentric shaft
section 22 due to rotation of the crankshaft 14,
centrifugal force acts upon the lubricating oil in the
inclined portion 74 of the oil pipe 72 in an obliquely
upward and outward direction, so that the lubricating oil
is drawn from the oil reservoir 76 upward into the oil
passage 74 by the centrifugal force.
[0028] Operation and function of the compressor 1 will
be now described.
In the compressor 1, when electric power is supplied
to the stator 8, the rotor 10, which is fixed to the main
shaft section 24, and thus the crankshaft 14 rotate, with
the result that the piston 18 is actuated by the connecting
rod 20 to make a reciprocating motion inside the cylinder
bore 26. As the piston 18 reciprocates, the refrigerant is
drawn from the refrigeration cycle into the cylinder bore
26, then compressed in the cylinder bore 26, and discharged
to the refrigeration cycle.
[0029] Specifically, as the piston 18 moves in a
CA 02787319 2012-07-17
11
direction of decreasing the volumetric capacity of the
cylinder bore 26, the refrigerant in the cylinder bore 26
is compressed, and when the pressure in the cylinder bore
26 exceeds a refrigerant discharge pressure, the discharge
valve 52 opens because of the difference between the
pressure in the cylinder bore 26 and the pressure in the
discharge chamber 56. The compressed refrigerant is guided
through the discharge hole 48 into the discharge chamber 56
and then is discharged to the refrigeration cycle through
the discharge pipe 60.
[0030] Subsequently, as the piston 18 moves from its top
dead center in a direction of increasing the volumetric
capacity of the cylinder bore 26, the pressure in the
cylinder bore 26 lowers. Since the pressure in the
cylinder bore 26 lowers, the discharge valve 52 closes due
to the difference between the pressure in the cylinder bore
26 and the pressure in the discharge chamber 56.
When the pressure in the cylinder bore 26 drops below
a refrigerant suction pressure, the suction valve 50 opens
because of the difference between the pressure in the
cylinder bore 26 and the pressure in the suction chamber
54. The refrigerant in the refrigeration cycle is guided
through the suction pipe 58 into the suction chamber 54 and
then drawn into the cylinder bore 26 via the suction hole
46.
[0031] Then, as the piston 18 moves from its bottom dead
center in a direction of decreasing the volumetric capacity
of the cylinder bore 26, the refrigerant in the cylinder
bore 26 is compressed. In this manner, a series of
processes, namely, suction of the refrigerant from the
refrigeration cycle into the cylinder bore 26, compression
of the refrigerant in the cylinder bore 26 and discharge of
the refrigerant to the refrigeration cycle, repeatedly
CA 02787319 2012-07-17
12
takes place.
[0032] As indicated by the arrows with symbols in FIG.
3, as the compressor 1 operates in the aforementioned
manner, the lubricating oil drawn upward from the oil
reservoir 76 into the oil passage 70 (arrow (a)) flows out
of the oil passage (arrow (b)) and then downward toward the
eccentric shaft section 22 (arrow (c)), and after
lubricating the large end portion 62 and its vicinities,
the lubricating oil flows down by gravity to the oil
reservoir 76 (arrow (d)).
[0033] On the other hand, part of the lubricating oil
flowing out of the oil passage 70 moves upward due to
centrifugal force along outer peripheral grooves, not
shown, formed in the crankshaft 14 (arrow (e)), thus
forming an oil film in the gap between the crankshaft 14
and the frame 36 to lubricate the bearing 42, and is guided
toward the upper end of the crankshaft 14. On reaching the
upper end face 40b of the cylindrical section 40 (arrow
(f)), the lubricating oil lubricates the bearing 44, then
passes through the gap between the rotor 8 and the frame 36
(arrow (g)), and flows down onto the upper surface 38a of
the seating section 38 of the frame 36.
[0034] The lubricating oil on the upper surface 38a
passes through a first oil feed hole 78 formed through the
seating section 38 of the frame 36 and the cylinder block
16 (arrow (h)) and a second oil feed hole 80 formed through
the seating section 38 of the frame 36 (arrow (i)), then
lubricates the compression mechanism 6, and flows down to
the oil reservoir 76 (arrow (d)).
Part of the lubricating oil that failed to pass
through the bearing 44 moves further upward along an inner
peripheral surface 10a of the rotor 10 up to the upper end
of the rotor 10 (arrow (j)), is scattered outward due to
CA 02787319 2012-07-17
13
the centrifugal force produced by the rotation of the rotor
to cool the stator 8 (arrow (k)), and passes through the
gap between the stator 8 and the rotor 10 (arrow (1)) and
then through the first oil feed hole 78 (arrow (h)) and the
5 second oil feed hole 80 (arrow (i)). After lubricating the
compression mechanism 6, the lubricating oil flows down to
the oil reservoir 76 (arrow (d)).
[0035] The compression mechanism 6 is lubricated in the
manner described below. Oil mist drawn into the cylinder
10 bore 26 enters, together with the refrigerant gas leaking
from the cylinder bore 26, the gap between the piston 18
and the cylinder block 16 for sealing and lubrication of
the piston 18 (arrow (m) ) . Also, part of the lubricating
oil drawn into the cylinder bore 26 is discharged to the
discharge chamber 56 and then to the refrigeration cycle
through the discharge pipe 60 (arrow (n)).
[0036] The lubricating oil is thereafter drawn from the
refrigeration cycle, together with the refrigerant, into
the suction chamber 54 through the suction pipe 58 (arrow
(o)), then adheres to a wall surface 54a of the suction
chamber 54, and flows down by gravity to the oil reservoir
76 (arrow (p)). The lubricating oil thus reaching the oil
reservoir 76 is again drawn up through the oil pipe 72 and
circulates in the hermetic container 2 or through the
refrigeration cycle, as stated above, while contributing to
sealing and lubrication of the individual sliding parts of
the electric motor 4 and compression mechanism 6.
[0037] As illustrated in FIG. 4, the first oil feed hole
78 is formed in a position such that when the piston 18 is
at the bottom dead center, the first oil feed hole 78 is
located immediately above the piston pin 66. The
lubricating oil that drips from the first oil feed hole 78
when the piston 18 is at the bottom dead center flows
CA 02787319 2012-07-17
14
toward the sliding portion where the piston pin 66 is
brought into sliding contact with the piston 18, as
indicated by arrows, and thus can directly lubricate the
piston pin 66.
[0038] The second oil feed hole 80 is formed in a
position such that when the piston 18 is at the bottom dead
center, the second oil feed hole 80 is located right above
the connecting rod 20. The lubricating oil that drips from
the second oil feed hole 80 when the piston 18 is at the
bottom dead center is able to directly lubricate the
connecting rod 20.
The oil feed holes 78 and 80 are respectively
constituted by oil reservoir sections 82 and 84 and small-
diameter holes 86 and 88 located beneath the respective oil
reservoir sections 82 and 84. The lubricating oil that has
reached the upper surface 38a is temporarily stored in the
oil reservoir sections 82 and 84.
[0039] The oil reservoir sections 82 and 84 are formed
by spot-facing the openings of the respective oil feed
holes 78 and 80 in the seating section 38 of the frame 36.
The oil reservoir section 82 is formed so as to extend from
the seating section 38 up to an intermediate portion of the
cylinder block 16.
Compared with the oil reservoir sections 82 and 84,
the small-diameter holes 86 and 88 have reduced diameters
set in accordance with the kinematic viscosity of the
lubricating oil used. The lubricating oil stored in the
oil reservoir sections 82 and 84 passes through the
respective small-diameter holes 86 and 88, so that the
lubricating oil intermittently drips drop by drop, or in a
few drops, to the compression mechanism 6.
[0040] Also, the connecting rod 20 has an oil groove 90
formed in an upper surface 20a thereof and extending from a
CA 02787319 2012-07-17
location near the crankshaft 14 to the vicinity of the
piston pin 66. The lubricating oil that dropped from the
second oil feed hole 80 to the oil groove 90 when the
piston 18 is at the bottom dead center flows toward both
5 the large and small end portions 62 and 64 due to the
rocking motion of the connecting rod 20, as indicated by
arrows. Thus, the large and small end portions 62 and 64
at which the connecting rod 20 is coupled to the crankshaft
14 and the piston 18, respectively, and their vicinities
10 can be lubricated by the lubricating oil.
[0041] On the other hand, when the piston 18 is at the
top dead center as illustrated in FIG. 5, the first and
second oil feed holes 78 and 80 are located immediately
above the connecting rod 20. The lubricating oil that
15 dropped from the oil feed holes 78 and 80 to the oil groove
90 when the piston 18 is at the top dead center flows
toward both the large and small end portions 62 and 64 due
to the rocking motion of the connecting rod 20, as
indicated by arrows. Thus, the large and small end
portions 62 and 64 at which the connecting rod 20 is
coupled to the crankshaft 14 and the piston 18,
respectively, and their vicinities can be lubricated by the
lubricating oil.
[0042] Further, the second oil feed hole 80 opens in a
position such that the open end thereof is partly closed by
an end wall 16b of the cylinder block 16 located opposite
the end wall to which the cylinder head 34 is fixed. After
passing through the second oil feed hole 80, the
lubricating oil flows down along the end wall l6b and falls
to the connecting rod 20 and the vicinities of a skirt 18a
of the piston 18.
[0043] The compressor 1 of the first embodiment is
provided with the first and second oil feed holes 78 and
CA 02787319 2012-07-17
16
80, and the first and second oil feed holes 78 and 80 allow
the lubricating oil to reliably drop onto the piston 18,
the piston pin 66 and the connecting rod 20, which are
arranged below the frame 36. This is because the frame 36
is secured to the hermetic container 2 and the lubricating
oil that flows from an upper region in the hermetic
container 2 down to the upper surface 38a of the frame 36
is not acted upon by the centrifugal force produced by the
rotation of the crankshaft 14. Accordingly, the
lubricating oil can effectively lubricate the compression
mechanism 6 without being influenced by the centrifugal
force, whereby the lubrication performance and reliability
of the compressor 1 can be improved.
[0044] When the piston 18 is at the bottom dead center,
the first oil feed hole 78 is located immediately above the
piston pin 66, and the second oil feed hole 80 is located
immediately above the connecting rod 20. Accordingly, when
the piston 18 is at the bottom dead center and thus the
refrigerant pressure in the cylinder bore 26 is low, the
lubricating oil can be made to drop from the first and
second oil feed holes 78 and 80 directly onto the piston
pin 66 and the connecting rod 20, respectively, without
being influenced by the pressure of the refrigerant gas
slightly leaking from the cylinder bore 26. The
compression mechanism 6 can therefore be lubricated more
effectively, making it possible to further improve the
lubrication performance of the compressor 1.
[0045] When the piston 18 is at the top dead center, the
first and second oil feed holes 78 and 80 are located right
above the connecting rod 20. Thus, also when the piston 18
is at the top dead center and thus the refrigerant pressure
in the cylinder bore 26 is high, the lubricating oil can be
made to drop from the first and second oil feed holes 78
CA 02787319 2012-07-17
17
and 80 directly at least onto the connecting rod 20. The
compression mechanism 6 can therefore be lubricated more
effectively, making it possible to further improve the
lubrication performance of the compressor 1.
[0046] Further, the frame 36 has the oil reservoir
sections 82 and 84 for temporarily storing the lubricating
oil that flows from the upper region in the hermetic
container 2 down to the upper surface 38a of the frame 36.
It is therefore possible to cause the lubricating oil to
intermittently drip little by little, and since the
compression mechanism 6 can be lubricated more effectively,
the lubrication performance of the compressor 1 can be
further improved.
[0047] Also, the connecting rod 20 has the oil groove 90
formed in the upper surface 20a thereof, and the oil groove
90 permits the lubricating oil dropped from the first and
second oil feed holes 78 and 80 onto the connecting rod 20
to be guided to the large and small end portions 62 and 64
at which the connecting rod 20 is coupled to the crankshaft
14 and the piston pin 66. Thus, since the compression
mechanism 6 can be lubricated more effectively, the
lubrication performance of the compressor 1 can be further
improved.
[0048] The present invention is not limited to the
foregoing embodiment and may be modified in various ways.
Specifically, in the above embodiment, a carbon
dioxide refrigerant is exemplified as the working fluid for
the compressor 1, but the working fluid to be used is not
limited to the carbon dioxide refrigerant. Where a carbon
dioxide refrigerant is used as the working fluid, the
working fluid discharged from the compression mechanism 6
is in a supercritical state and thus the pressure thereof
is very high, so that high pressure may possibly prevail in
CA 02787319 2012-07-17
18
the interior of the hermetic container 2. Consequently,
the lubricating oil dropping, in particular, from the first
oil feed hole 78 directly onto the piston pin 66 is greatly
influenced by the pressure of the working fluid. With the
aforementioned configuration, however, the compression
mechanism 6 can be effectively lubricated without the
influence of the pressure of the working fluid, whereby the
lubrication performance of the compressor 1 can
advantageously be enhanced.
[0049] Also, in the foregoing embodiment, the
displacement type compressor 1 is explained by way of
example. The present invention is applicable to hermetic
type fluid machines in general, such as scroll compressor
and expander, and fluid machines to which the invention is
applied can of course be used as devices constituting
refrigeration cycles incorporated in apparatuses other than
automatic vending machines.
Explanation of Reference Signs
[0050] 1 compressor (fluid machine)
2 hermetic container
2a inside bottom
4 electric motor (driving unit)
6 compression mechanism (driven unit)
14 crankshaft (rotary shaft)
16 cylinder block
16a upper surface
18 piston
20 connecting rod
20a upper surface
26 cylinder bore
36 frame
38a upper surface
66 piston pin
CA 02787319 2012-07-17
19
70 oil passage (lubrication mechanism)
72 oil pipe (lubrication mechanism)
78 first oil feed hole
80 second oil feed hole
82 oil reservoir section
84 oil reservoir section
90 oil groove
