Scroll type compressor with oil-separating plate in discharge chamber

In a scroll type compressor, a movable scroll is engaged with an immovable scroll so that spaces are formed for taking in a fluid including a lubricating oil mist to be compressed. The movable scroll is revolved around a central axis of the immovable scroll so that, as the spaces are displaced toward a center of the immovable scroll, a volume thereof is reduced to compress the fluid therein. The immovable scroll has a passage through which each of the spaces is communicated with a discharge chamber upon reaching the center, whereby the compressed fluid is successively discharged through the passage into the chamber. An oil-separating plate is disposed in the chamber at a given level lower than the passage, and a reed valve is provided at the passage. A retainer for the reed valve is shaped such that the compressed fluid discharged from the passage through the reed valve is directed to and impinged on an upper surface of the plate, to thereby separate a lubricating oil from fluid, whereby the separated oil is reserved in a lower portion of the chamber defined by the plate, and thus a level of the reserved oil is maintained at the upper surface thereof.

BACKGROUND OF THE INVENTION 
1) Field of the Invention 
The present invention relates to a scroll type compressor which can be 
used, for example, in an air-conditioning system of a vehicle such as an 
automobile, and more particularly, to a scroll type compressor provided 
with an improved lubricating arrangement for movable parts thereof. 
2) Description of the Related Art 
For example, Japanese Unexamined Patent Publication No. 57-62988 discloses 
a scroll type compressor for an air-conditioning system of an automobile, 
which comprises immovable and movable scroll members housed in a housing 
and having spiral guide walls engaged with each other in such a manner 
that spaces are formed as a compression chamber therebetween. The movable 
scroll member is revolved around a center axis of the immovable scroll 
member in such a manner that an engagement is maintained between the 
spiral guide walls of the immovable and movable scroll member, and that 
the spaces or compression chambers therebetween are displaced toward 
centers of the spiral guide walls. 
During the revolution of the movable scroll member around the center axis 
of the immovable scroll member, a compression chamber appears successively 
at the outsidemost portions of the spiral guide walls thereof, and opens 
to take in a refrigerant, including a lubricating oil mist, fed from an 
evaporator of the air-conditioning system, and then the compression 
chamber concerned is fully closed by the spiral guide walls, due to the 
revolution of the movable scroll member. Thereafter, as the compression 
chamber concerned is displaced toward the centers of the spiral guide 
walls, a volume thereof becomes gradually smaller, whereby the refrigerant 
confined therein is compressed, and when the compression chamber concerned 
reaches the centers of the spiral guide walls, the compressed refrigerant 
is discharged through a reed valve into a discharge chamber formed in the 
housing of the compressor. After the discharge of the compressed 
refrigerant into the discharge chamber is completed, the compression 
chamber concerned disappears at the centers of the spiral guide walls, and 
thus a compression of the refrigerant is successively carried out. 
To cause the revolution of the movable scroll member around the central 
axis of the immovable scroll member, the compressor comprises a drive 
shaft projected from the housing and operatively connected to and rotated 
by a prime mover of the vehicle, and an eccentric mechanism provided 
between the drive shaft and the movable scroll member for converting the 
rotation of the drive shaft into the revolution of the movable scroll 
member. The drive shaft is provided with a seal assembly to prevent a 
leakage of the refrigerant from the housing, and is rotatably supported by 
a radial bearing. The eccentric mechanism includes an eccentric pin 
element projected from an enlarged portion of the drive shaft, and a bush 
element rotatably engaged with the eccentric pin element and rotatably 
received in a sleeve portion projected from the movable scroll member 
through the intermediary of a radial bearing. The drive shaft, the bush 
element and the sleeve portion are axially aligned with each other, and 
thus the movable scroll member can be revolved around the central axis of 
the immovable scroll member by the rotation of the drive shaft. 
Also, to constrain the movement of the movable scroll member, to thereby 
ensure the revolution thereof around the central axis of the immovable 
scroll member, the compressor comprises a first annular plate fixedly 
disposed at a rear side of the movable scroll member and having a 
plurality of circular recesses formed therein, and a second annular plate 
attached to a rear side wall surface of the movable scroll member and 
facing the first annular plate, and having the same number of circular 
recesses formed therein. The circular recesses of the first and second 
annular plates are radially disposed so that each of the circular recesses 
of the first annular plate partially overlaps the corresponding circular 
recess of the second annular plate, and two shoe elements are slidably 
received in each pair of the partially overlapped circular recesses of the 
first and second annular plates in such a manner that a ball element is 
slidably disposed between and held by the two shoe elements. With this 
arrangement, the movement of the movable scroll member is constrained, and 
thus the revolution thereof around the central axis of the immovable 
scroll member is ensured. 
The various movable parts of the compressor as mentioned above are exposed 
to the refrigerant fed from an evaporator of the air-conditioning system, 
and thus are lubricated with lubricating oil separated from refrigerant. 
When an excessive amount of the oil mist is included in the refrigerant, 
although the movable parts are sufficiently lubricated, the larger the 
amount of oil mist, the lower the cooling efficiency of the 
air-conditioning system, and accordingly, in the conventional compressor, 
the compressed refrigerant discharged from the compression chamber into 
the discharge chamber through the reed valve is directed to and impinged 
on an inner wall surface of the discharge chamber, so that a part of the 
oil mist is separated from the refrigerant, and the separated oil is 
stored in the discharge chamber. Nevertheless, an amount of the separated 
oil obtained depends upon the running conditions of the compressor, such 
as a rotational speed of the drive shaft and a rate of flow of the 
compressed and discharged refrigerant, etc., and thus an amount of the oil 
mist included in the refrigerant cannot be maintained at a constant value 
during the running of the compressor. Accordingly, when an amount of the 
oil mist is too small, the movable parts are not sufficiently lubricated 
and may seize up. Conversely, when the amount of the oil mist is too 
large, the cooling efficiency of the air-conditioning system is lowered, 
as mentioned above. 
SUMMARY OF THE INVENTION 
Therefore, an object of the present invention is to provide a scroll type 
compressor having an improved lubricating arrangement wherein an amount of 
the oil mist included in the refrigerant can be maintained at a constant 
value even when the running conditions of the compressor vary. 
In a scroll type compressor according to the present invention, immovable 
and movable scroll members are housed in a housing and have spiral guide 
walls engaged with each other such that spaces or compression chambers for 
taking in a fluid including a lubricating oil mist to be compressed are 
formed therebetween. The movable scroll member is revolved around a center 
axis of the immovable scroll member in such a manner that, as the 
compression chambers are displaced toward a center of the immovable scroll 
member, a volume thereof is reduced to thereby cause a compression of the 
fluid in the compression chambers. The immovable scroll member has a 
passage through which each of the compression chambers is communicated 
with a discharge chamber upon reaching the center of the immovable scroll 
member, whereby the compressed fluid is successively discharged through 
the passage into the discharge chamber. An oil-separating plate member is 
provided in the discharge chamber at a given level lower than the passage, 
and a reed valve element is provided at the passage. A retainer element 
for retaining the reed valve element is shaped such that the compressed 
fluid discharged from the passage through the reed valve element is 
directed to and impinged on an upper surface of the oil-separating plate 
member, to thereby separate a lubricating oil from the fluid, whereby the 
separated oil is reserved in a lower portion of the discharge chamber 
defined by the oil separating plate member and thus a level of the 
reserved oil is maintained at the upper surface of the oil-separating 
plate member.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
FIGS. 1 and 2 show a first embodiment of a scroll type compressor according 
to the present invention. This compressor comprises front and rear 
housings 10 and 12, and an intermediate housing 14 disposed therebetween, 
and the front and rear housings 10 and 12 are joined to the front and rear 
ends of the intermediate housing 14 by screws (not shown) extending 
through the housings 10, 14 and 12. The front housing 10 defines a suction 
chamber 16 together with an annular disk plate 18 fixedly disposed at a 
boundary between the front and intermediate housings 10 and 14, and the 
suction chamber 16 is in communication with, for example, an evaporator of 
an air-conditioning system (not shown), through an inlet port 20 formed in 
a side wall of the front housing 10, whereby a refrigerant including a 
lubricating oil mist is fed to the suction chamber from the evaporator. 
The compressor also comprises an immovable scroll member 22 housed in the 
intermediate housing 14 and including a base portion 22a integrally formed 
therewith, and a spiral guide wall 22b projected from a front wall surface 
of the base portion 22a. As apparent from FIG. 1, the base portion 22a of 
the scroll member 22 defines a discharge chamber 24 together with the rear 
housing 12, and the discharge chamber 24 is communicated with a condenser 
of the air-conditioning system through an outlet port 26 formed in a side 
wall of the rear housing 12. The base portion 22a of the immovable scroll 
member 22 has a central through passage 22c formed therein, and thus an 
inner chamber defined by the intermediate housing 14 is in communication 
with the discharge chamber 24. The through passage 22c is usually closed 
by a reed valve 23a attached to the rear side wall surface of the base 
portion 22a, and when the reed valve 23a is open as shown in FIG. 1, it is 
held open by a retainer 23b. 
The compressor further comprises a movable scroll member 28 movably 
disposed in the intermediate housing 14 and including a base portion 28a 
integrally formed therewith, and a spiral guide wall 28b projected from a 
rear wall surface of the base portion 28a. The spiral guide wall 28b of 
the movable scroll member 28 is engaged with the spiral guide wall 22b of 
the immovable scroll member 22 so that spaces or compression chambers 30 
are formed therebetween. Each of the spiral guide walls 22b and 28b may 
have a profile defined by an involute line. 
The movable scroll 28 is revolved around an central axis of the immovable 
scroll member 22 in such a manner that an engagement is maintained between 
the spiral guide walls 22b and 28b, whereby the compression chambers 30 
are successively displaced toward the center of the immovable scroll 
member 22. To this end, the compressor comprises a drive shaft 32 
operatively connected to and rotated by a prime mover of the vehicle (not 
shown), and an eccentric mechanism 34 provided between the drive shaft 32 
and the movable scroll member 28 for converting the rotation of the drive 
shaft 32 into the revolution of the movable scroll member 28. 
In particular, the drive shaft 32 includes a shaft portion 32a and an 
enlarged portion 32b integrated with an inner end thereof, and is disposed 
within the front housing 10 so that a longitudinal axis thereof is aligned 
with the central axis of the immovable scroll member 22. The shaft portion 
32a of the drive shaft 32 is received in an outer sleeve portion 10a 
projected from the front housing 10 and is rotatably supported by a 
seal-assembly 36 disposed in the outer sleeve portion 10a, and the 
enlarged portion 32b thereof is received in and rotatably supported by a 
radial bearing 38 fixedly housed in the front housing 10. Note, the shaft 
portion 32a is operatively connected to, for example, a prime mover of the 
vehicle, through a suitable clutch such as an electromagnetic clutch. The 
eccentric mechanism 34 includes an eccentric pin element 34a integrally 
projected from an inner end face of the enlarged portion 32b of the drive 
shaft 32, and a bush element 34b rotatably engaged with the eccentric pin 
element 34a and rotatably received in a sleeve portion 28c projected from 
the movable scroll member 28 into a central opening of the annular disk 
plate 18 and provided with a radial bearing 40 for rotatably receiving the 
bush element 34b. With this arrangement, the movable scroll member 28 can 
be revolved around the central axis of the immovable scroll member 22 by 
the rotation of the drive shaft 32. Note, the eccentric pin element 34b is 
provided with a counterweight 34c, to ensure that the eccentric mechanism 
46 is stably driven. 
To constrain the movement of the movable scroll member 28 so as to ensure 
the revolution thereof around the central axis of the immovable scroll 
member 22, the compressor comprises a first annular plate 42 fixedly 
attached to the annular disk plate 18 at a rear side thereof and having a 
plurality of circular recesses 42a formed therein, and a second annular 
plate 44 attached to a rear side wall surface of the movable scroll member 
28 so as to face the first annular plate 42 and having the same number of 
circular recesses 44a formed therein. The circular recesses 42a and 44a of 
the first and second annular plates 42 and 44 are radially disposed at 
regular intervals so that each of the circular recesses 42a of the first 
annular plate 42 partially overlaps the corresponding circular recess 44a 
of the second annular plate 44, and two shoe elements 42b and 44b are 
slidably received in each pair of the partially overlapped circular 
recesses 42a and 44a of the first and second annular plates, respectively, 
so that a ball element 46 is slidably disposed between and held by the two 
shoe elements 42b and 44b. With this arrangement, the movement of the 
movable scroll member is constrained so that the revolution thereof around 
the central axis of the immovable scroll member can be ensured. Namely, a 
rotation of the movable scroll member 28 around its own central axis is 
prevented during the revolution thereof around the central axis of the 
immovable scroll member. 
Although the inner chamber of the intermediate housing 14 is in 
communication with the suction chamber 16 defined by the front housing 10 
through the central openings of the annular disk plate 18 and the first 
annular plate 42, a further communication therebetween is provided with a 
through passage 48 formed and disposed at a location beside a rotational 
zone of the counterweight 34c, and thus a sufficient amount of the 
refrigerant is fed from the suction chamber 16 to the inner chamber of the 
intermediate housing 14. 
In operation, each of the compression chambers 30 initially appears at the 
outermost portions of the spiral guide walls 28b and 22b of the movable 
and immovable scroll members 28 and 22 and opens to the inner chamber of 
the intermediate housing 14, so that the refrigerant is introduced 
thereinto, and then the compression chamber 30 concerned is completely 
closed by the spiral guide walls 28b and 22b due to the revolution of the 
movable scroll member 28. As the compression chamber 30 concerned is 
displaced toward the center of the immovable scroll member 22, the volume 
thereof becomes gradually smaller so that the refrigerant confined therein 
is compressed, and when the compression chamber 30 concerned reaches the 
center of the immovable scroll member 22, it is brought into communication 
with the central through passage 22c of the immovable scroll member 22, so 
that the reed valve 23a is opened by the compressed refrigerant and the 
compressed refrigerant is discharged into the discharge chamber 24. 
Thereafter, the compression chamber 30 concerned disappears at the center 
of the immovable scroll member 22, and a new compression chamber 
successively appears at the outermost portions thereof during the 
revolution of the movable scroll member 28, whereby compression of the 
refrigerant can be consecutively carried out. The compressed refrigerant 
is fed to the condenser of the air-conditioning system through the outlet 
port 26. 
During the running of the compressor, all of the movable parts are exposed 
to the refrigerant, and thus lubricated with a lubricating oil separated 
from the refrigerant. In an assembly of the immovable and movable scroll 
members 22 and 28, the lubricating oil separated from the refrigerant also 
serves as a sealing material. Particularly, the compression chambers 30 
defined by the spiral guide walls 22b and 28b are sealed by the 
lubricating oil existing at contacting locations between the spiral guide 
walls 22b and 28b. Further, the tops of the spiral guide walls 22b and 
28b, in contact with inner wall surfaces of the base portions 28 and 22, 
are provided with spiral grooves 22d and 28d formed at the tops thereof, 
respectively, and are filled with the lubricating oil separated from the 
refrigerant, whereby the filled oil serves as a top seal. 
The compressor according to the present invention is characterized in that 
a horizontal plate member 50 is provided in the discharge chamber 24 at a 
given level, and that the retainer 23b is shaped such that, when the reed 
valve 23a is opened and held thereby, the compressed refrigerant 
discharged from the through passage 22c is directed to the horizontal 
plate member 50. The horizontal plate member 50 includes a first ledge 
portion 50a projected from the base portion 22a of the immovable scroll 
member 22 and a second ledge portion 50b projected from the rear housing 
12. Namely, the first and second ledge portions 50a and 50b are not 
provided with the horizontal plate member 50 until the rear housing 12 is 
mounted on the intermediate housing 14. The first ledge portion 50a is not 
extended to a peripheral inner wall surface of the intermediate housing 
14, as shown in FIG. 2, and the second ledge portion 50b is laterally 
coextended with respect to the first ledge portion 50a. Namely, an upper 
portion of the discharge chamber 24 defined by the plate member 50 is in 
communication with a lower portion thereof at the lateral end sides of the 
plate member 50. 
The horizontal plate member 50 serves as an oil-separating plate. In 
particular, when the compressed refrigerant discharged from the through 
passage 22c is directed to and impinged on the plate member 50, the 
lubricating oil is separated therefrom. The separated oil is reserved in 
the lower portion of the discharge chamber 24 defined by the plate member 
50. The separation of the oil from the refrigerant is continued until the 
level of the reserved oil reaches an upper surface of the horizontal plate 
member 50. When the level of the reserved oil becomes higher than the 
upper surface of the plate member 50, no further separation of the oil 
from the refrigerant occurs, but instead an oil surface of the reserved 
oil is made turbulent by the compressed refrigerant discharged from the 
through passage 22c, so that a part of the reserved oil is entrained with 
the refrigerant as an oil mist. The entrainment of the oil with the 
refrigerant is continued until the level of the reserved oil is lowered to 
the upper surface of the plate member 50, and thus the level of the 
reserved oil can be maintained at the upper surface of the plate member 50 
during the running of the compressor, as shown in FIG. 2. Namely, a total 
amount of the oil mist included in the refrigerant can be substantially 
maintained at a constant value, and thus a fluctuation of an cooling 
efficiency of the air-conditioning system can be substantially prevented. 
Of course, the level of the upper surface of the horizontal plate member 
50 is selected so that the refrigerant includes an amount of the oil mist 
sufficient to lubricate the movable parts of the compressor. 
FIGS. 3 and 4 show a modification of the embodiment of FIGS. 1 and 2. Note, 
in FIGS. 3 and 4, features similar to those of FIGS. 1 and 2 are indicated 
by the same reference numerals. In this modification, the horizontal plate 
member 50 has an additional sloped plate member 52 including a first 
portion 52a integrally formed with the first ledge portion 50a and 
projected from the base portion 22a of the immovable scroll member 22, and 
a second portion 52b integrally formed with the second ledge portion 50b 
and projected from the rear housing 12. The first portion 52a has an oil 
passage 54 formed at an upper end thereof and extended to the spiral 
groove 22d through the base portion 22a and spiral guide wall 22b of the 
immovable scroll member 22. The first portion 52a also has a lateral 
through slot 56 formed at a lower end thereof, and an elongated groove 58 
formed in an end face thereof and communicating the oil passage 54 and the 
lateral through slot 56. When the rear housing 12 is mounted on the 
intermediate housing 14, the end face of the first portion 52a is mated 
with an end face of the second portion 52b, so that the lateral through 
slot and the elongated groove 58 are closed, to thereby provide an oil 
passage and an oil intake port, respectively. As a pressure of the 
discharge chamber is maintained at a high level during the running of the 
compressor, a part of the reserved oil is fed to the spiral groove 22d 
through the intake port 56 and the oil passages 58 and 54, to thereby 
ensure a formation of the oil seal at the top of the spiral guide wall 22b 
of the immovable scroll member 22. 
Finally, it will be understood by those skilled in the art that the 
foregoing description is of preferred embodiments of the present 
invention, and that various changes and modifications thereof can be made 
without departing from the spirit and scope thereof.