High-pressure dome type compressor capable of preventing oil discharge due to gas and of cooling oil by discharge gas

A high-pressure dome type compressor is capable of successfully cooling oil fed to sliding portions during a passage of oil in a drive shaft by discharge gas without causing the oil to be discharged along with the gas. In the drive shaft of a motor disposed in a casing and a moveable scroll of a compression section driven by the drive shaft, there are defined discharge gas passages for discharging, into the casing, compressed fluid compressed in a compression chamber of the compression element. An oil feed passage for oil pumped up from an oil reservoir at a bottom of the casing is defined in the drive shaft so as to be partitioned from the discharge gas passage.

TECHNICAL FIELD 
The present invention relates to a high-pressure dome type compressor in 
which a motor and a compression section to be driven by a drive shaft are 
disposed within a high-pressure dome type closed casing. 
BACKGROUND ART 
Conventionally, there has been known a high-pressure dome type compressor 
as disclosed in, for example, Japanese Patent Laid-Open Publication No. 
SHO 60-224988. In this high-pressure dome type compressor, a suction pipe 
is connected to a compression section, compressed gas compressed by the 
compression section is once discharged into the casing and then discharged 
out of the casing via an outside discharge pipe. 
More specifically, in the conventional high-pressure dome type compressor, 
as shown in FIG. 2, a compression section E comprising a fixed scroll B 
fixed to a housing A disposed in a casing F and a movable scroll D to be 
driven by a drive shaft C of a motor M is internally provided airtight 
within the closed casing F. A suction pipe G is connected to the fixed 
scroll B, and a discharge port H opened into the casing F is defined in 
the fixed scroll B. 
In the movable scroll D, there is defined a boss D1 to which is fitted an 
eccentric shaft portion C1 of the drive shaft C that is connected to the 
motor M, so that the movable scroll D will be eccentrically rotated as the 
drive shaft C rotates. The drive shaft C is supported with a bearing by 
the housing A, while oil in an oil reservoir J at the bottom of the casing 
F is pumped up through an oil feed passage C2 defined in the drive shaft C 
so as to be fed to the bearing portion and boss D1's sliding portion of 
the housing A. 
Then, gas sucked from the suction pipe G into the compression section E is 
compressed in a compression chamber K defined between the scrolls B, D, 
then discharged into the casing F through the discharge port H defined at 
the center of the fixed scroll B, and thereafter discharged out of the 
casing F via an outside discharge pipe L. 
For the conventional high-pressure dome type compressor, there is a need of 
cooling oil because the oil fed to the bearing portion through the oil 
feed passage C2 of the drive shaft C, which has become high in temperature 
due to frictional heat, is returned to the oil reservoir J of the casing 
F. However, the cooling of oil in the oil reservoir J is usually 
implemented merely by naturally cooling only the surface of the oil 
reservoir J by heat exchange with the discharge gas which has been 
discharged into the casing F, not by aggressively cooling the oil enough. 
Thus, there has been a problem in that seizure may occur to the sliding 
portions. 
In operating ranges in which the amount of refrigerant circulation 
decreases, there has been another problem that oil cannot be cooled up by 
discharge gas so that the oil becomes an abnormally high temperature, 
causing a deterioration of the oil. 
As a solution for this, it might be conceived to implement the cooling of 
oil by aggressively putting the discharge gas into contact with the 
surface of the oil reservoir. With this solution applied, however, the oil 
would be disturbed by the discharge gas being blown against the oil 
reservoir, resulting in a problem of so-called oil rise that the oil is 
discharged along with gas. 
The present invention has been developed in view of the above described 
problems and has for its essential object to provide a high-pressure dome 
type compressor capable of successfully cooling the oil fed to sliding 
portions by implementing heat exchange between the discharge gas and the 
oil fed to the sliding portions, without causing any oil rise. 
DISCLOSURE OF THE INVENTION 
The present invention provides a high-pressure dome type compressor in 
which a compression section having a fixed scroll and a movable scroll as 
well as a motor having a drive shaft for driving the movable scroll of the 
compression section are disposed in a closed casing, the high-pressure 
dome type compressor being characterized in that: discharge gas passages 
for discharging, into the closed casing, compressed gas compressed in a 
compression chamber of the compression section are defined in the movable 
scroll and the drive shaft, respectively, and an oil feed passage for oil 
pumped up from an oil reservoir located at a bottom of the closed casing 
is defined in the drive shaft so as to be partitioned from the discharge 
gas passage. 
According to the present invention, heat exchange between discharge gas 
flowing through the discharge gas passage and oil flowing through the oil 
feed passage is carried out so that the oil within the oil feed passage to 
be supplied to the bearing and other sliding portions can be successfully 
cooled by the discharge gas within the discharge gas passage. Still, since 
the discharge gas passage and the oil feed passage are defined so as to be 
partitioned from each other, any disturbance of oil due to discharge gas 
can be prevented so that the cooling of oil can be accomplished 
successfully without causing any oil rise. 
Furthermore, since heat exchange between discharge gas and oil is 
successfully carried out, the temperature difference between discharge gas 
temperature and oil temperature can be minimized so that the state of oil 
can be determined based on the discharge gas temperature. Thus, the 
control of oil temperature is facilitated. 
When a large quantity of refrigerant is mixed in low-temperature oil, for 
example, at a start of the compressor, the oil within the oil feed passage 
can be heated by the discharge gas flowing through the discharge gas 
passage. Therefore, gas can be separated from the oil by a heating process 
before the oil is fed to the lubricating portions, so that the viscosity 
of oil can be increased and thus the lubrication performance can be 
improved. 
In an embodiment, the discharge gas passage of the drive shaft is provided 
so as to be eccentric with respect to an axis of the drive shaft, in an 
eccentric direction of the movable scroll driven by the drive shaft. 
According to this embodiment, the discharge gas passage is provided in such 
a direction that any imbalance of the movable scroll is canceled. 
Therefore, the balance weight provided to the drive shaft may be smaller 
than the conventional, so that the compressor can be designed to be 
lighter in weight. 
In an embodiment, a discharge pipe is opened to a first space defined 
between the compression section and the motor while the discharge gas 
passage of the drive shaft is opened to a second space defined on a side 
of the motor opposite to a side of the motor on which the compression 
section is provided. 
According to this embodiment, discharge gas discharged from the discharge 
gas passage is discharged out of the casing through the discharge pipe, 
after it has cooled the motor. Therefore, the cooling of the motor can be 
aggressively fulfilled by the discharge gas discharged from the discharge 
gas passage. Still, during the cooling of the motor, oil in the discharge 
gas is separated so that the oil rise can be prevented more successfully. 
Further scope of applicability of the present invention will become 
apparent from the detailed description given hereinafter. However, it 
should be understood that the detailed description and specific examples, 
while indicating preferred embodiments of the invention, are given by way 
of illustration only, since various changes and modifications within the 
spirit and scope of the invention will become apparent to those skilled in 
the art from this detailed description. 
The present invention will become more fully understood from the detailed 
description given hereinbelow and the accompanying drawings which are 
given by way of illustration only, and thus are not limitative of the 
present invention, and wherein:

BEST MODE FOR CARRYING OUT THE INVENTION 
FIG. 1 is a high-pressure dome type scroll compressor showing an embodiment 
of the present invention. In the scroll compressor, a housing 2 is fixed 
to a closed casing 1, a compression section CF is disposed above the 
housing 2, and a fixed scroll 3 of the compression section CF is fixed to 
the housing 2. On the other hand, a motor M for driving the compression 
section CF is disposed below the housing 2, and a drive shaft 4 of the 
motor M is held to a bearing portion 21 of the housing 2. 
Further, the housing 2 serves for the partition into a low-pressure side 
chamber 5 where the compression section CF is disposed and a high-pressure 
side chamber 6 where the motor M is disposed and a discharge pipe 11 is 
opened so that compressed gas compressed by the compression section CF is 
discharged. A suction pipe 12 connects directly with the fixed scroll 3. 
The high-pressure side chamber 6 is divided into a first space 61 defined 
by the motor M between the motor M and the compression section CF, a 
second space 62 defined by the motor M and a cup-like pump housing 13 on a 
side of the motor M opposite to a side of the motor M on which the 
compression section is provided, and a third space 63 having an oil 
reservoir 14 and defined below the pump housing 13. 
The compression section CF comprises a movable scroll 7 which has a spiral 
member 72 protrudingly provided to an end plate 71 and which is connected 
to the drive shaft 4 of the motor M, and the fixed scroll 3 which has a 
spiral member 32 protrudingly provided to an end plate 31. These scrolls 
7, 3 are oppositely provided so that their spiral members 72, 32 engage 
each other, where a compression chamber 15 is defined between the spiral 
members 72, 32. 
In the movable scroll 7, a discharge port 73 for discharging compressed gas 
compressed in the compression chamber 15 is defined at a central portion 
of the end plate 71 of the movable scroll 7, while a cylindrical portion 
75 having a discharge gas passage 74 to which the discharge port 73 opens 
is provided to a rear-side central portion of the end plate 71. 
In the drive shaft 4, an eccentric boss 41 for receiving the cylindrical 
portion 75 of the movable scroll 7 is defined, while further provided are 
a discharge gas passage 42 one end of which is communicated with the 
discharge gas passage 74 of the cylindrical portion 75 via a communicating 
member 8 and the other end of which is opened to the second space 62 
defined on the underside of the motor M in the closed casing 1, and an oil 
feed passage 43 one end of which is opened into the eccentric boss 41 and 
the other end of which is communicated with the oil reservoir 14 provided 
at the bottom of the casing 1 via an oil pump 16. The discharge gas 
passage 42 and the oil feed passage 43 are partitioned and defined in 
parallel to each other. This discharge gas passage 42 is communicated with 
the second space 62 through an unshown hole. 
The communicating member 8 comprises a seal member 82 which is 
insertionally fitted into the cylindrical portion 75 of the movable scroll 
7 so as to be unrotatable and axially movable relative to the cylindrical 
portion 75 via a ring seal 81, and a sliding bushing 83 which will slide 
in contact with the seal member 82 and which is pressed and secured into 
the eccentric boss 41 of the drive shaft 4. Between the seal member 82 and 
the cylindrical portion 75, there is interposed a coil spring 84 for 
urging the seal member 82 against the sliding bushing 83, by which the 
seal member 82 and the sliding bushing 83 are sealed from each other so 
that the gas within the discharge gas passages 74, 42 will not leak into 
the eccentric boss 41. 
The drive shaft 4 is supported at its lower side by the pump housing 13. 
The oil pump 16 is a positive displacement type oil pump. 
The discharge gas passage 42 formed in the drive shaft 4 is made larger in 
diameter than the oil feed passage 43, and provided so as to be eccentric 
with the axis of the drive shaft 4 in the eccentric direction of the 
movable scroll 7. 
Between the movable scroll 7 and the housing 2, an Oldham's ring 17 is 
provided so that the movable scroll 7 is enabled to orbit without rotating 
itself. 
Further, the rear side of the end plate 71 of the movable scroll 7 is 
supported by an annular thrust receiving portion 22 defined in the housing 
2. The thrust receiving portion 22 is located inner than the Oldham's ring 
17. At the inner radius of the thrust receiving portion 22, a cylindrical 
seal ring 18 is further provided to contact with the end plate 71 of the 
movable scroll 7. By the seal ring 18, a spatial portion defined on the 
inner radius side of the seal ring 18 is partitioned from the low-pressure 
side chamber 5. 
Oil pumped up through the oil feed passage 43 is once pumped up into the 
eccentric boss 41, lubricating a bearing 91 provided between the outer 
circumferential surface of the cylindrical portion 75 of the movable 
scroll 7 and the inner circumferential surface of the eccentric boss 41, 
as well as the bearing portion 21 supporting the outer circumferential 
surface of the eccentric boss 41, while the oil is fed also to the place 
where the seal ring 18 is provided. The oil after effecting the 
lubrication is returned to the bottom oil reservoir 14 through an oil 
passage 19 defined on the periphery of the motor M, via an oil return 
passage 23 formed in the housing 2. 
By the movable scroll 7 being driven to orbitally revolve relative to the 
fixed scroll 3, the volume of the compression chamber 15 defined between 
the spiral members 32, 72 is varied, by which low-pressure gas sucked in 
through the suction pipe 12 connected to the fixed scroll 3 through the 
casing 1 is introduced between the spiral members 32, 72, and compressed 
in the compression chamber 15. Then, high-pressure gas discharged through 
the discharge port 73 of the movable scroll 7 into the discharge gas 
passage 74 of the cylindrical portion 75 is fed to the discharge gas 
passage 42 of the drive shaft 4, and thereafter discharged to the second 
space 62 through an unshown hole. The gas is further passed through an air 
gap 10 of the motor M so as to be fed to the first space 61, and 
thereafter discharged out of the casing 1 via the discharge pipe 11. 
With the construction described above, in this embodiment, the drive shaft 
4 of the motor M disposed within the closed casing 1 of a high-pressure 
dome, and the movable scroll 7 of the compression section CF to be driven 
by the drive shaft 4 are provided with the discharge gas passages 74, 42 
for discharging, into the casing 1, compressed fluid compressed in the 
compression chamber 15 of the compression section CF, while the oil feed 
passage 43 for oil pumped up from the oil reservoir 14 at the bottom of 
the casing 1 is defined in the drive shaft 4 so as to be partitioned from 
the discharge gas passage 42. Therefore, heat exchange between discharge 
gas flowing through the discharge gas passage 42 and oil flowing through 
the oil feed passage 43 is carried out so that the oil within the oil feed 
passage 43 to be fed to the sliding portions such as the bearings 21, 91 
can be successfully cooled by the discharge gas within the discharge gas 
passage 42. Still, since the discharge gas passage 42 and the oil feed 
passage 43 are defined so as to be partitioned from each other, any 
disturbance of oil due to discharge gas can be prevented so that the 
cooling of oil can be accomplished successfully without causing any oil 
rise. 
Further, since heat exchange between discharge gas and oil is successfully 
carried out, the temperature difference between discharge gas temperature 
and oil temperature can be minimized so that the state of oil can be 
determined based on the discharge gas temperature. Thus, the control of 
oil temperature is facilitated. 
When a large quantity of refrigerant is mixed in low-temperature oil, for 
example, at a start of the compressor, the oil within the oil feed passage 
43 is heated by the discharge gas flowing through the discharge gas 
passage 42. Therefore, gas can be separated from the oil by a heating 
process before the oil is fed to the lubricating portions, so that the 
viscosity of oil can be increased and thus the lubrication performance can 
be increased. 
Further, the discharge gas passage 42 is provided so as to be eccentric 
with respect to the axis of the drive shaft 4, in the eccentric direction 
of the movable scroll 7. Accordingly, in this case, the discharge gas 
passage 42 is provided in such a direction that any imbalance of the 
movable scroll 7 is canceled. Therefore, the balance weight provided to 
the drive shaft 4 may be smaller than the conventional, so that the 
compressor can be designed to be lighter in weight. 
Further, the discharge pipe 11 is opened to the first space 61 defined 
between the compression section CF and the motor M, while the discharge 
gas passage 42 is opened to the second space 62 defined on a side of the 
motor M opposite to the side on which the compression section is provided. 
Therefore, before discharge gas discharged from the discharge gas passage 
42 is discharged out of the casing 1 through the discharge pipe 11, the 
discharge gas is passed through the air gap 10 of the motor M so that the 
motor M can be cooled aggressively. Still, the oil in the discharge gas 
can be separated by the cooling of the motor M, so that the oil rise can 
be prevented further successfully. 
Also since the compression section CF is disposed in the low-pressure side 
chamber 5, the whole compression section CF is thermally insulated by the 
low-pressure gas so that suctional overheating is prevented. Thus, a high 
volumetric efficiency is attained. 
INDUSTRIAL FIELD OF APPLICATION 
The high-pressure dome type compressor of the present invention is used for 
refrigerators, air conditioners, and the like. 
The invention being thus described, it will be obvious that the same may be 
varied in many ways. Such variations are not to be regarded as a departure 
from the spirit and scope of the invention, and all such modifications as 
would be obvious to one skilled in the art are intended to be included 
within the scope of the following claims.