Refrigerant compressors

A refrigerant compressor comprising a balance hole communicating between a crank chamber and a suction chamber for returning the blow-by gas in the crank chamber to suction chamber, is provided with an oil separating member in a discharge chamber to separate oil in the compressed refrigerant gas. The separated oil is accumulated in an accumulating zone in the discharge chamber and returns to the crank chamber through an oil flowing passageway which communicates between the accumulating zone and the crank chamber thereby to reduce the oil leakage into the refrigerant circulating system.

BACKGROUND OF THE INVENTION 
This invention relates generally to refrigerant compressor units and, in 
particular, to a refrigerant compressor in which oil is separated from the 
compressed refrigerant gas. 
A conventional refrigerant compressor unit comprises a compressor housing, 
a cylinder block mounted therein and having a plurality of cylinders, and 
a plurality of pistons respectively, slidably and closely fitted within 
the cylinders. The pistons are driven within the cylinders to compress 
refrigerant gas. The compressor housing includes a chamber adjacent the 
cylinder block for containing piston driving elements, and a cylinder head 
having a suction chamber and a discharge chamber which operatively 
communicate with the cylinders. 
A charge of refrigerant gas and lubricating oil is introduced into the 
compressor unit. In the operation operation of the compressor, the 
refrigerant gas is compressed by the pistons reciprocating within 
corresponding cylinders. The compressed refrigerant gas circulates from 
the discharge chamber through a cooling system and returns to the 
compressor unit at the suction chamber. The lubricant oil passes into the 
crank chamber together with the refrigerant gas as a blow-by gas through a 
gap between the piston and the inner wall of the corresponding cylinder to 
lubricate therebetween. The lubricant oil is separated from the 
refrigerant gas in the crank chamber and lubricates moving parts therein. 
In order to return the blow-by gas into the suction chamber, the 
conventional compressor unit is provided with a passageway or a balance 
hole which communicates between the crank chamber and the suction chamber. 
Accordingly, the lubricant oil also returns to the suction chamber to 
lubricate the pistons and cylinders. 
However, the oil mixed with the refrigerant gas goes out from an outlet 
port and circulates in the cooling system and contaminates the inner wall 
of conduits in that system. This means not only that lubricant oil is 
wasted unreasonably, but also that the efficiency of heat exchange in the 
system is lowered. 
SUMMARY OF THE INVENTION 
It is an object of this invention is to provide a refrigerant compressor 
unit wherein the oil mixed with the compressed refrigerant gas is 
prevented from circulating through the cooling system together with the 
refrigerant gas. 
It is another object of this invention is to provide a refrigerant 
compressor in which a significant decrease in the waste of lubricant oil 
is achieved along with an increase in the efficiency of heat exchange in 
the cooling system. 
It is still another object of this invention to realize these objects in a 
simple construction. 
In one aspect of this invention, a refrigerant compressor unit includes a 
drive shaft, a cam rotor mounted on an inner end of the shaft and a, 
wobble plate mounted on an inclined surface of the cam rotor through a 
radial needle bearing. The wobble plate is connected with a plurality of 
pistons by respective piston rods, and a bearing ball for nutatably 
supporting the wobble plate is seated in a ball seat supported by the 
cylinder block. Means are provided within the discharge chamber of the 
compressor unit for separating oil from the compressed refrigerant gas. To 
this end, an oil accumulating chamber is formed within the discharge 
chamber, and an oil passageway is formed in the cylinder block which 
communicates between the oil accumulating chamber and the ball seat, 
whereby the separated oil is returned to the crank chamber where it 
lubricates the bearing ball. 
In another aspect of this invention, the oil returning passageway is so 
provided that the separated oil is introduced from the oil accumulating 
chamber to a shaft seal cavity through which the drive shaft extends 
outside of the compressor housing, whereby the oil returns to the crank 
chamber after lubricating the shaft seal assembly and the bearing 
supporting the drive shaft. 
Further objects, features and other aspects of this invention will be 
understood from the following detailed description of preferred 
embodiments of this invention referring to annexed drawings.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The embodiment of the invention illustrated in FIGS. 1-4 comprises a 
substantially cylindrical housing 10, a cylinder block 11 which is closely 
fitted into and secured to the housing 10 at an end thereof, and a front 
housing or cover plate 12 secured to the other end of the housing 10. The 
interior of the housing 10 defines a crank chamber 13 between the cylinder 
block 11 and the front housing 12. A swash plate or a cam rotor 14, which 
is disposed within the crank chamber 13, is fixedly mounted on an inner 
end of a main shaft 16. The main shaft 16 extends through a central 
portion of the front housing 12 outside of a the housing and is rotatably 
supported by means of bearing such as a needle bearing 15 in the front 
housing 12. The cam rotor 14 is also supported on the inner surface of the 
front housing 12 by means of a thrust needle bearing 17. In the crank 
chamber 13, a wobble plate 19 is also disposed in close proximity with the 
sloping surface 14a of the cam rotor 14 with a thrust needle bearing 18 
therebetween. The wobble plate 19 is nutatably but non-rotatably supported 
on a bearing ball 21 seated at an end of a supporting member 20. 
The supporting member 20 comprises a shank portion having an axial hole 20a 
at its other end and a bevel bear portion 20b at the end of the shank 
portion which has a seat for the bearing ball 21 at its center. The 
supporting member is axially slidably but non-rotatably supported on the 
cylinder block 11 by inserting the shank portion into a central axial hole 
22 formed in the cylinder block 11. The rotation of the supporting member 
20 is prevented by means of a key and a key groove (not shown). A coil 
spring 23 is disposed in the axial hole 20a of the supporting member. The 
outer end of spring 23 is in contact with a screw member 24 screwed into 
the central hole 22 of the cylinder block 11, so that the supporting 
member 20 is urged toward the wobble plate 19. The bevel gear portion 20b 
of the supporting member 20 engages with a bevel gear 25 mounted on the 
wobble plate 19 so that the rotation of the wobble plate is prevented. The 
bearing ball 21 is seated in the seat formed at a central portion of the 
bevel gear portion 20b and is also seated in a seat formed at a central 
portion of the bevel gear 25, so that the wobble plate 19 is nutatably but 
non-rotatably supported on the bearing ball 21. 
The cylinder block 11 is provided with a plurality of axial cylinders 26 
formed therein, within which pistons 27 are respectively slidably and 
closely fitted. The pistons 27 are respectively connected with the wobble 
plate 19 by a plurality of piston rods 28. The connection between the 
piston rods and the pistons and the connection between the piston rods and 
the wobble plate are made by a ball joint mechanism. 
On the outer end of the cylinder block 11, a cylinder head 31 is disposed 
and is secured to the cylinder block by means of bolts 29, interposing a 
gasket member (not shown) and a valve plate assembly 30 therebetween. 
Referring to FIG. 2, the cylinder head 31 is provided with a suction 
chamber 32 and a discharge chamber 33 separated by a partition wall 311. 
The valve plate assembly 30 comprises a valve plate 36 having suction 
ports 34 connecting between the suction chamber 32 and respective 
cylinders 26, and discharge ports 35 connecting between the discharge 
chamber 33 and respective cylinders 26. The valve plate assembly also 
includes a suction reed valve member (not shown), a discharge reed valve 
member 37, a stopper plate 39 for suppressing excessive deformation of the 
discharge reed valve member 37, and bolt-nut means 38 for securing the 
suction and discharge reed valve members and the stopper member to the 
valve plate. 
In the operation of the compressor as above described, the main shaft 16 is 
driven by any suitable driving means, such as an automobile engine. The 
cam rotor 14 rotates together with the main shaft, so that the wobble 
plate 19 nutates about the bearing ball 21 according to the rotation of 
the sloping surface 14a of the cam rotor 14. The nutation of the wobble 
plate 19 causes reciprocating movement of respective pistons 27 within 
cylinders 26. Therefore, the suction and compression of the refrigerant 
gas is repeatedly performed in each cylinder. Thus, the refrigerant gas 
circulates through a cooling circuit which is connected between an inlet 
port 40 and an outlet port 41 of the cylinder housing 31. During the 
operation of the compressor, a part of refrigerant gas in each cylinder 
passes into the crank chamber 13 as a blow-by gas through a gap between an 
inner wall of the cylinder 26 and the piston 27. 
As shown best in FIG. 3, in order to return the blow-by gas to the suction 
chamber 32, a passageway 42, which is a so-called balance hole, is formed 
in the cylinder block 11 and through the valve plate assembly 30 to 
communicate between the crank chamber 13 and the suction chamber 32. 
Lubricating oil contained in the crank chamber is agitated and splashed 
during the operation of the compressor and lubricates the internal moving 
parts in the form of an oil mist. 
Referring again to FIG. 1, the housing 10 is provided with an oil deflector 
43 formed on the inner surface thereof for directing the oil flow along 
the inner wall of the housing 10 toward the front housing 12, as disclosed 
in U.S. Pat. No. 4,005,948 to Hiraga. The front housing 12 is provided 
with an oil passageway 44 which communicates between the crank chamber 13 
at the front end of the deflector 43 and a shaft seal cavity 46 formed in 
the front housing 12, to direct the oil flow to the shaft seal cavity 46. 
A shaft seal assembly 45 is disposed in the shaft seal cavity on the main 
shaft 16 extending therein. The main shaft 16 is provided with an oil 
passageway 47 which communicates between the shaft seal cavity 46 and the 
crank chamber 13. Accordingly, oil flowing along the inner surface of the 
housing 10 is directed to the oil passageway 44 by the deflector 43, and 
flows into the shaft seal cavity 46. A part of the oil returns from the 
shaft seal cavity to the crank chamber 13 thereby lubricating the needle 
bearing 15 supporting the main shaft and the thrust needle bearing 17. The 
other part of the return oil flows through the oil passageway 47 into the 
crank chamber 13 for lubricating the needle bearing 18. 
A part of the agitated oil mist in the crank chamber flows into the suction 
chamber 32 together with the returning refrigerant gas through the balance 
hole 42, and is sucked into respective cylinders to lubricate the gap 
between the pistons and the inner walls of the cylinders. But a part of 
the oil mist is discharged to the discharge chamber together with the 
compressed refrigerant gas and, therefrom, circulates into the cooling 
circuit. The leakage of oil to the cooling circuit could cause various 
disadvantages as described hereinabove. In the refrigerant compressor unit 
of the invention, means as described more completely below is provided for 
preventing oil from flowing through the cooling circuit and for returning 
the oil flowing into the discharge chamber to the crank chamber. 
As shown in FIG. 1, the supporting member 20, screw member 24 and the bolt 
38 are provided with axial central oil passageways 51, 52, and 53, 
respectively, so that the crank chamber 13 communicates with the discharge 
chamber 33 through the passageways. An oil receiving member 54 for 
receiving oil separated by an oil separator described hereinafter is 
disposed in the discharge chamber 33 by being secured to the valve plate 
assembly 30 by the bolt 38. An oil pick-up tube 55 is fixed to the end of 
the bolt 38 and communicates with the axial passageway 53 of the bolt 38. 
The end of the tube is curved downwardly in the oil receiving member 54. 
The oil receiving member 54 is in the form of a container having a 
top-opening 57, and has a horizontal plate 56 near the top opening 57. The 
oil separator 58 is disposed in the discharge chamber above the top 
opening 57 of the oil receiving member 54. The oil separator 58 is formed 
of a material such as porous materials, screen and the like to be able to 
separate oil from the mixture of refrigerant gas and oil mist passing 
therethrough. A rear plate 59 is fixedly disposed in the rear of, and in 
contact with, the oil receiving member 54 in the discharge chamber 33 and 
is fixed to the partition wall 311 to separate the discharge chamber 33 
into two chambers 33a and 33b. The rear plate 59 may be secured to the 
cylinder head by means of bolts. The oil receiving member 54 and the oil 
separator 58 are disposed in the chamber 33a which communicates with 
discharge ports 35, and the other chamber 33b communicates with the outlet 
port 41. 
As shown in FIG. 4, the rear plate 59 is provided with a cut-away portion 
or opening 60, which is registered to the oil separator 58, so that the 
gas passing the oil separator flows into the chamber 33b. 
In operation, the mixture of oil mist and refrigerant gas, which is 
compressed in the cylinders and discharged into the discharge chamber 33, 
passes through the oil separator 58 where oil is separated from the 
oil-gas mixture. The separated oil falls down into the oil receiver 54 
under the oil separator 58, and the refrigerant gas flows into the chamber 
33b from which the refrigerant gas circulates to the cooling circuit 
through the outlet port 41. The oil accumulated in the oil receiver 54 
flows into the axial central hole 22 through the pick-up tube 55 and the 
passageway 53 of the bolt 38, and further flows through the passageways 52 
and 51 of the screw member 24 and the supporting member 20 into the crank 
chamber 13 thereby lubricating the bearing ball 21. Thus, the oil is 
prevented from circulating through the cooling circuit. The horizontal 
plate 56 serves to block the gas flow from agitating the oil accumulated 
in the oil receiving member 54. 
In the embodiment of the invention illustrated in FIGS. 1-4, the oil 
separated from the compressed gas returns to the crank chamber through the 
passageways of the bolt, screw member and supporting member, but may be 
returned through any different passageway. 
In the embodiment of the invention illustrated in FIGS. 5-7, the separated 
oil is introduced into the shaft seal cavity 46 and, thereafter, is 
returned to the crank chamber. Therefore, the deflector 43 and the oil 
passageway 44 of the front housing 12 are omitted in this embodiment. In 
other respects parts that are similar to the embodiment of FIGS. 1-4 are 
represented by the same reference numerals as in that embodiment, and the 
description of these similar parts is omitted for the purpose of 
simplification of the description. 
The cylinder head 31 in the embodiment of FIGS. 5-7 is provided with a wall 
61 projecting from the inside surface 312 of the end wall thereof in the 
discharge chamber 33 and transversely extending in the discharge chamber 
33 to connect with the partition wall 311 at opposite positions, as shown 
in FIGS. 6 and 7, so that the discharge chamber 33 is separated into an 
upper chamber portion connecting with the outlet port 41 and a lower 
chamber portion. The axial length of the projecting wall 61 is short of 
that of the partition wall 311. In the lower chamber portion, small 
projections 62 (two projections are shown) are formed to inwardly project 
from the inside surface of the partition wall 311 so that the axial side 
surface of each small projection 62 lies in the same radial plane as the 
axial end surface of the wall 61. 
An oil separator plate 63 made of a material, such as porous materials, a 
screen and the like, is disposed in the discharge chamber 33 and is 
received on the axial end surface of the projecting wall 61 and the axial 
side surfaces of the small projections 62. The oil separator plate 63 is 
formed in a shape consistent with the internal shape of the partition wall 
311, but is partially cut away as shown at 631 at a peripheral portion 
thereof corresponding to the lower chamber portion. Thus, the discharge 
chamber 33 is separated by the oil separator plate 63 into three chamber 
portions 33a, 33b, and 33c. The first chamber portion 33a is a portion 
adjacent the valve plate assembly 30, another, or second, chamber portion 
33b being the upper portion than the projecting wall 61 which portion is 
defined by the partition wall 311, the oil separator plate 63 and the 
projecting wall 61, and the other, or third, chamber portion 33c being the 
lower portion than the projecting wall 61 which portion is partially 
communicating with the first chamber portion 33a through the cut-away 
portion 631 of the oil separator plate 63. 
In order to separate the lower chamber portion 33c from the chamber portion 
33a, a partition plate 64 is also disposed in the discharge chamber 33. 
The partition plate 64 comprises a plate portion 641 covering the oil 
separator plate 63 except at at least a part of a portion thereof defining 
the upper chamber portion 33b, and an axial flange. Portion 642 axially 
extends toward the valve plate assembly 30 from the plate portion 641 at 
the lower end corresponding to the cut-away portion 631 of the oil 
separator plate 63. The axial end of the axial flange portion 642 is in 
contact with the valve plate assembly 30. Therefore, the first chamber 
portion 33a is separated from the third chamber portion 33c. The third 
chamber portion 33c is defined by the projecting wall 61, the partition 
plate 64 and the valve plate assembly 30. The partition plate 64 should be 
disposed so that all discharge ports 35 communicate with the first chamber 
portion 33a. 
The oil separator plate 63 and the partition plate 64 are secured to the 
cylinder head 31 by bolt means as shown at 65 in FIG. 7. These may be 
secured to the valve assembly 30. 
In the operation of the embodiment of FIGS. 5-7 the mixture of the 
refrigerant gas and oil mist compressed in the cylinders flows into the 
first chamber portion 33a of the discharge chamber 33 through respective 
discharge ports 35, and, passes from chamber portion 33a through the oil 
separator plate 63 into the second chamber portion 33b. At the oil 
separator plate 63, oil mist is separated from the refrigerant gas and 
flows down along the oil separator plate 63 into the lower chamber portion 
33c. The separated refrigerant gas flows into the upper chamber portion 
33b from which it circulates to the cooling circuit through the outlet 
port 41. In this manner oil is prevented from circulating to the cooling 
circuit and from accumulating in the lower chamber portion 33c. 
In this embodiment, an oil passageway 66 is formed to communicate the lower 
chamber portion 33c with the shaft seal cavity 46 in order to return the 
separated and accumulated oil into the crank chamber 13. The oil 
passageway 66 comprises a first oil hole 66a axially extending through the 
side wall of the cylindrical housing 10, a second oil hole 66b axially 
formed in the valve plate assembly 30 in registry with the first oil hole 
66a, a third oil hole 66c formed in the front housing 12 to communicate 
the first oil hole 66a with the shaft seal cavity 46, and a fourth oil 
hole 66d formed in the cylinder head 31 to connect the second oil hole 66b 
with the lower chamber portion 33c. Thus, the separated and accumulated 
oil in the lower chamber portion 33c flows into the shaft seal cavity 46 
through the oil passageway 66 and returns to the crank chamber 13 after 
lubricating needle bearings 15, 17, and 18. 
An orifice member 67 is disposed in the oil hole 66a to prevent the 
compressed refrigerant gas from leaking to the crank chamber 13 through 
the oil passageway 66. If any one of oil holes 66a-66d is sufficiently 
small to prevent the gas from flowing from the chamber portion 33c to the 
crank chamber 13 through the oil passageway 66, the orifice 67 need not be 
used. 
Furthermore, in this embodiment, the supporting member 20 is formed with an 
axial small hole 20c extending between the ball seat of the end surface 
thereof and the axial hole 20a. The screw member 24 is also formed with an 
axial hole 24a. Accordingly, the high pressure mixture gas leaks from the 
first chamber portion 33a of the discharge chamber to the axial central 
hole 22 of the cylinder block 11 through a gap along the peripheral 
surface of the bolt 38, and the leaked gas flows to the bearing ball 21 
through the holes 24a, 20a, and 20c so that the bearing ball 21 is 
lubricated. 
FIGS. 8 and 9 show a modification of the embodiment as shown in FIGS. 5-7, 
in which a back-up plate 70 is used in the second chamber portion 33b of 
the discharge chamber 33 at the rear end of the oil separator plate 63, 
and a partition plate 64' has a window 643' at the plate portion 641' 
thereof. 
The partition plate 64' comprises a plate portion 641' covering over the 
second chamber portion 33b and an axial flange portion 642' similar to the 
flange portion 642 of the partition plate 64 in the embodiment of FIG. 5, 
and the window 643' formed in the plate portion 641' at a location 
corresponding to the second chamber portion 33b. The oil separator plate 
63' is interposed between the partition plate 64' and the back-up plate 70 
to cover the window 643' of the plate portion 641', with the lower end of 
the oil separator plate 63' being exposed in the lower chamber portion 
33c. The back-up plate 70 covers over the oil separator plate 63' in the 
second chamber portion 33b except at an area corresponding to at least a 
part of the window 643'. Accordingly, the mixture of the refrigerant gas 
and oil mist discharged into the first chamber portion 33a through the 
discharge ports passes through the window 643' and the oil separator plate 
63' into the second chamber portion 33b, after oil mist is removed at the 
oil separator plate 63', and is circulated to the cooling circuit through 
the outlet port 41. The separated oil at the oil separator plate 63' flows 
down along the separator plate and is accumulated in the lower chamber 
portion 33c. 
In this embodiment, the oil captured by, and maintained in, the oil 
separator plate 63' is prevented from flowing into and being sprayed into 
the second chamber portion 33b by the back-up plate 70. 
The back-up plate 70 may be secured to the partition plate 64' by means of 
tabs 70a and 70b, as shown in FIG. 9, holding the oil separator plate 63' 
therebetween. As also shown in FIG. 9, the partition plate 64' is formed 
with small openings 644'a and 644'b for receiving tabs 70a and 70b of the 
back-up plate 70. The tabs 70a and 70b are inserted into the openings 
644'a and 644'b of the partition plate 64' interposing the oil separator 
plate 63' and the ends of tabs are bent, so that the oil separator plate 
63' and the back-up plate 70 are secured to the partition plate 64' to 
form an assembly. The assembly is disposed in the discharge chamber 33, 
and is assembled into the cylinder head by securing the partition plate 
64' by bolt means shown by 71 in FIG. 9. 
Although the invention has been described in detail in connection with 
preferred embodiments referring to compressors of a specific type, it will 
be appreciated that these are only for exemplification, and it is 
understood that other modifications and various designations may be made 
by those skilled in the art without necessarily departing from the spirit 
and scope of this invention.