Swash plate type compressor

Details Swash plate type compressor Swash plate type compressor

2001-06-12

2003-03-18

Walberg, Teresa (Department: 3742)

Pumps

Condition responsive control of drive transmission or pump...

Adjustable cam or linkage

Reexamination Certificate

active

06533555

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a swash plate type compressor that has single headed pistons and is used in an air conditioner of a vehicle, and more particularly, to improvement of a radial bearing that supports a drive shaft for reciprocating the pistons and to improvement of a lubricating structure of a shaft sealing assembly.
As shown in
FIG. 6
, the housing of a typical swash plate type compressor includes a front housing member
71
, a cylinder block
72
and a rear housing member
73
, which are secured to one another. A drive shaft
74
has a first end and a second end. The drive shaft
74
is supported by the housing through a first and second radial bearings
75
,
76
such that the first end protrudes from the front housing member
71
. A shaft sealing assembly
78
is located about the drive shaft
74
at a position between the first end and the first radial bearing
75
. The sealing assembly
78
prevents refrigerant gas from leaking from a crank chamber
77
to the atmosphere.
Moving parts of a compressor such as bearings are lubricated by misted lubricant contained in refrigerant gas. Therefore, parts where refrigerant gas is stagnant are not effectively lubricated. A compressor that uses carbon dioxide (CO
2
) for a cooling circuit instead of chlorofluorocarbon has been introduced. When using CO
2
as refrigerant, the refrigerant pressure is more than ten times that of a case where chlorofluorocarbon is used as refrigerant, which increases the load acting on bearings and shaft sealing assemblies. Accordingly, lubrication must be improved.
In the compressor of Japanese Unexamined Patent Publication No. 11-241681, the shaft sealing assembly
78
is located in an isolated chamber
80
, which is forward of the first radial bearing
75
. A decompression passage
79
is formed in the drive shaft
74
. An outlet
79
b
of the decompression passage
79
opens to the end face of the second end of the drive shaft
74
. A fan
81
is attached to the second end of the drive shaft
74
. When the fan
81
rotates integrally with the drive shaft
74
, refrigerant in the decompression passage
79
is drawn to the outlet
79
b
. The refrigerant then flows to the crank chamber
77
through the radial bearing
76
.
The isolated chamber
80
is connected to the crank chamber
77
through the space in the radial bearing
75
and the space in a thrust bearing
82
. The spaces in the radial bearing
75
and the thrust bearing
82
function as oil supplying passages.
Japanese Unexamined Patent Publication No. 8-165987 discloses a compressor shown in FIG.
7
. In this compressor, a second end of the drive shaft
74
faces a chamber
84
that communicates with a suction chamber
83
. An axial passage
85
is formed in the drive shaft
74
. The inlet
85
a
of the passage
85
opens to an isolated chamber
80
. The outlet
85
b
of the passage
85
opens to the chamber
84
.
In the compressor of
FIG. 6
, the fan
81
attached to the drive shaft
74
draws some of refrigerant gas into the decompression passage
79
through the first radial bearing
75
or through the thrust bearing
82
. The drawn refrigerant gas then returns to the crank chamber
77
through the second radial bearing
76
. Accordingly, the radial bearings
75
,
76
and the shaft sealing assembly
78
are reliably lubricated. However, to flow lubricant through the decompression passage
79
, the fan
81
is required, which complicates the structure.
Instead of a fan, the chamber
84
is located adjacent to the second end of the drive shaft
74
of the compressor shown in
FIG. 7
, and the passage
85
is formed in the drive shaft
74
to connect the isolated chamber
80
with the chamber
84
. Thus, refrigerant flows through the radial bearings
75
,
76
or through the thrust bearing
82
in accordance with the pressure difference between the crank chamber
77
and the chamber
84
. However, since the inlet
85
a
is located between the shaft sealing assembly
78
and the thrust bearing, flow of refrigerant is weakened either in the shaft sealing assembly
78
or in the thrust bearing, which results in insufficient lubrication.
BRIEF SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a swash plate type compressor that includes a simple structure for effectively lubricating radial bearings, which support a drive shaft, and a shaft sealing assembly.
To achieve the foregoing and other objectives and in accordance with the purpose of the present invention, a swash plate type compressor is provided. The compressor includes a housing, a drive shaft, first and second radial bearings, a piston, a cam plate, a shaft sealing assembly. A suction chamber, a discharge chamber and a crank chamber are defined in the housing. The housing has at least one cylinder bore. The drive shaft is rotatably supported by the housing and has a first end portion and a second end portion. The first end portion protrudes from the housing. The first and second radial bearings support the first and second end portions of the drive shaft, respectively. The piston is reciprocally accommodated in the cylinder bore. The cam plate is accommodated in the crank chamber and is operably coupled to the piston to convert rotation of the drive shaft into reciprocation of the piston. The shaft sealing assembly seals the space between the drive shaft and the housing and is accommodated in the suction chamber. The suction chamber is closer to the first end portion of the drive shaft than the first radial bearing is. A passage is formed in the drive shaft to connect the suction chamber to the crank chamber. The passage has an inlet and an outlet. The inlet is closer to the second end portion than the second radial bearing is. The outlet is closer to the second end portion than the first radial bearing is.
Other aspects and advantages of the invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.


REFERENCES:
patent: 4174191 (1979-11-01), Roberts
patent: 5603610 (1997-02-01), Kawaguchi et al.
patent: 5842834 (1998-12-01), Kawaguchi et al.
patent: 6398515 (2002-06-01), Yokomachi et al.
patent: 6402480 (2002-06-01), Sud et al.
patent: 6412171 (2002-07-01), Kato et al.
patent: 6416297 (2002-07-01), Kawaguchi et al.
patent: 6422129 (2002-07-01), Yokomachi et al.
patent: 0 926 342 (1999-06-01), None
patent: 8-165987 (1996-06-01), None
patent: 11-241681 (1999-09-01), None

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