Guide passage between the piston and housing of a compressor

Details Guide passage between the piston and housing of a compressor Guide passage between the piston and housing of a compressor

1999-12-07

2001-09-25

Tyler, Cheryl J. (Department: 3745)

Pumps

Three or more cylinders arranged in parallel, radial, or...

C417S569000, C092S169100, C092S172000

Reexamination Certificate

active

06293763

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a piston type compressor. More particularly, the present invention pertains to a compressor that decreases pressure loss at the last stage of piston discharge strokes.
Japanese Unexamined Patent Publications Nos. 8-261150 and 10-68382 disclose piston type compressors.
FIG. 11
illustrates part of the piston type compressor of the publications. A piston
81
is reciprocally housed in a cylinder bore
82
. A valve plate
95
separates the cylinder bore
82
from a suction chamber
83
and from a discharge chamber
84
. The valve plate
95
includes a main plate
85
, a first sub plate
89
and a second sub plate
91
. The first and second sub plates
89
,
91
sandwich the main plate
85
. A suction port
86
and a discharge port
87
are formed in the valve plate
95
. The first sub plate
89
includes a suction valve flap
88
. The suction valve flap
88
corresponds to the suction port
86
. The second sub plate
91
has a discharge valve flap
90
. The discharge valve flap
90
corresponds to the discharge port
87
.
A compression chamber
92
is defined by the end face of the piston
81
and the first sub plate
89
in the cylinder bore
82
. When the piston
81
is moved from the top dead center position to the bottom dead center position, that is, when the piston
81
is in the suction stroke, refrigerant gas in the suction chamber
83
is drawn into the compression chamber
92
through the suction port
86
and the suction valve flap
88
. When the piston
81
moves from the bottom dead center position toward the top dead center position, that is, when the piston
81
is in the discharge stroke, the gas in the compression chamber
92
is compressed to a predetermined pressure. The gas is then discharged to the discharge chamber
84
through the discharge port
87
and the valve flap
90
.
As shown in
FIG. 12
, the ports
86
and
87
are located radially inside of the wall of the cylinder bore
82
.
When the piston
81
is at the last stage of the discharge stroke, that is, when the piston
81
is in the vicinity of the top dead center position, gas in the compression chamber
92
flows to the discharge port
87
through a narrow space between the end of the piston
81
and the first sub plate
89
. This causes a pressure loss. The pressure loss decreases the compression efficiency of the compressor.
Compressors that are used in vehicle air conditioners typically use fluorocarbon as refrigerant. However, the recent trend is to replace fluorocarbon by carbon dioxide to decrease the influence of the refrigerant on the environment.
Carbon dioxide refrigerant requires a higher compression rate (for example, ten times higher) than fluorocarbon refrigerant. Thus, the pressure loss mentioned above is much more significant in compressors using carbon dioxide as a refrigerant.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a compressor that decreases pressure loss at the last stage of the piston discharge stroke.
To achieve the above objective, the present invention provides a compressor. The compressor comprises a housing, a cylinder bore formed in the housing, a suction chamber formed in the housing, a discharge chamber formed in the housing. A discharge port connects the discharge port to the cylinder bore. A piston is located in the cylinder bore. The piston moves from a top dead center position to a bottom dead center position to draw refrigerant gas into the cylinder bore from the suction chamber. The piston moves from the bottom dead center position to the top dead center position to discharge refrigerant gas to the discharge chamber. A compression chamber is defined by an enclosure. The enclosure is formed by the piston and the housing. A guide passage facilitates the flow of compressed gas from the compression chamber to the discharge port. The guide passage is defined in the enclosure when the piston is located substantially at the top dead center position.
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: 1109154 (1914-09-01), Thomas
patent: 3957140 (1976-05-01), Overkott
patent: 4189984 (1980-02-01), Tankred et al.
patent: 4311127 (1982-01-01), Mayer
patent: 4350083 (1982-09-01), Gannaway
patent: 4610606 (1986-09-01), Hazzard et al.
patent: 5149254 (1992-09-01), Riffe
patent: 5346373 (1994-09-01), Riffe
patent: 5380163 (1995-01-01), Fujii et al.
patent: 5411055 (1995-05-01), Kane
patent: 5492459 (1996-02-01), Burkett et al.
patent: 5562425 (1996-10-01), Kimura et al.
patent: 0881386A2 (1998-12-01), None
patent: 58-2481 A (1983-01-01), None
patent: 08-261150 (1986-10-01), None
patent: 10-068382 (1998-03-01), None
patent: WO96/34200 (1996-10-01), None

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