Rotary expansible chamber devices – Methods
Reexamination Certificate
2003-08-22
2004-11-30
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Methods
C418S011000, C418S060000, C418S249000
Reexamination Certificate
active
06824367
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATION
This application claims the priority benefit of Japanese applications serial no. 2002-247201, filed on Aug. 27, 2002; serial no. 2002-247204, filed on Aug. 27, 2002; serial no. 2002-250927, filed on Aug. 29, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a multi-stage compression type rotary compressor comprising an electrical-power element arranged within a sealed vessel, a first and a second rotary compression element that is driven by the rotary shaft of the electrical-power element, wherein the refrigerant compressed by the first rotary compression element is compressed by the second rotary compression element, and the refrigerant gas compressed and discharged by the first rotary compression element is sucked to the second rotary compression element and is compressed and discharged thereby. The present invention also relates to a setting method of displacement volume ratio for the multi-stage compression type rotary compressor.
2. Description of the Related Art
A conventional rotary compressor sucks the refrigerant gas to the low-pressure chamber side of a cylinder through a suction port of the rotary compression element. The refrigerant gas compressed by the operations of a roller and a vane is temporarily discharged into the sealed vessel through the discharge port at the high-pressure chamber side of the cylinder and then is discharged to outside through the sealed vessel. The vane is installed movably in a groove formed in a radial direction of the cylinder. The vane is pressed against the roller to divide an inside of the cylinder into a low-pressure chamber side and a high-pressure chamber side. A spring is provided on a rear side of the vane to urge this vane on a roller side. A back pressure chamber that communicates with the sealed vessel is set within the groove for urging the vane on the roller side. Therefore, the high-pressure inside the sealed vessel is charged to the back pressure chamber and urges the vane on the roller side.
In this rotary compressor, the application of refrigerant with combustibility, such as propane (R290), HC refrigerant excluding Freon has been considered due to the damage of the ozone layer resulting from Freon refrigerant.
It is necessary to make the sealing amount of the combustible refrigerant such as, a propane in low amount, due to the security consideration. The security limitation for propane serving as refrigerant is 150 g. However, it is necessary to limit the sealing amount to be 100 g for sufficient security in practice (50 g for refrigerator using).
Because the refrigerant is discharged after being compressed in the sealed vessel in the rotary compressor, the sealed volume of the refrigerant must be in excess of 30 g ~50 g compared to the refrigerant in a reciprocating compressor with the same volume as the rotary compressor. Therefore, the regulatory stringent regarding to the use of the rotary compressor with combustible refrigerant.
The conventional multi-stage compression type rotary compressor, as shown in
FIG. 13
, sucks the refrigerant gas to the low-pressure chamber side of the cylinder
240
through the suction port
262
of the first rotary compression element
232
. The refrigerant gas is compressed to a medium pressure by operations of the roller
248
and the vane
252
and is discharged through the discharge port
272
at the high-pressure chamber side of the cylinder
240
. Therefore, the medium pressure refrigerant gas is sucked to the low-pressure chamber side of the cylinder
238
through the suction port
261
of the second rotary compression element
234
. The second compression of the refrigerant gas is done by the operations of the roller
246
and the vane
250
to make the refrigerant have high temperature and high pressure, and the refrigerant is then discharged through the discharge port
270
at the high-pressure chamber side. The refrigerant discharged by the compressor flows into a radiator. After the refrigerant has been radiated, it is closed in the expansion valve and then is heat-absorbed by the evaporator and sucked to the first rotary compression element
232
. This cycle is repeated. Furthermore, in
FIG. 13
, the reference numeral
216
indicates a rotary shaft of the electrical-power element. The reference numerals
227
,
228
indicate discharge valves set inside the discharge-muffler chamber
262
,
264
to open or close the discharge ports
270
,
272
.
The displacement volume of the second rotary compression element
234
is set smaller than that of the first rotary compression element
232
. Under this condition, in the conventional rotary compressor, the thickness (height) of the cylinder
240
of the first rotary compression element
232
is made smaller than that of the cylinder
238
of the second rotary compression element
234
; the internal diameter of the cylinder
238
of the second rotary compression element
234
is made smaller than that of the cylinder
240
of the first rotary compression element
232
; the eccentric amount of the roller
246
of the second rotary compression element
234
is made small (the external diameter of the roller
246
is made large). By doing so, the displacement volume of the second rotary compression element
234
is set to be smaller that of the first rotary compression element
232
.
SUMMARY OF THE INVENTION
It is to be discussed that the use of the combustible refrigerant that exerts medium pressure in the sealed vessel in the multi-stage compression type rotary compressor. The pressure inside the sealed vessel is relatively low compared to the high pressure refrigerant gas discharged into the sealed vessel. In other words, because the low pressure refrigerant has low density, the amount of the refrigerant existing in the sealed vessel can be reduced. Especially, in the case when the ratio of displacement volume of the second rotary compression element to the first rotary compression element is large, the medium pressure is difficult to rise. Therefore, the amount of the refrigerant that is sealed within the sealed vessel can be further reduced.
However, in a case when the medium pressure is lowered in the sealed vessel in the rotary compressor, during the start-up of the compressor, the pressure inside the sealed vessel that serves as a back pressure and is charged to the vane of the first rotary compression element is difficult to rise, this may break away the vanes.
Moreover, because it takes time in the internal medium-pressure compressor to reach a balanced pressure after the rotary compressor stops, the startability of re-start-up is poor.
The displacement volume ratio of the multi-stage compression type rotary compressor has suitable values according to the various usages. For each suitable value, parts must be replaced (including the changing of the material type, working equipment and measuring instrument, etc.) in the eccentric amount of the rotary shaft, the external diameter of the roller or the internal diameter·height of the cylinder. Moreover, due to the difference of the eccentric amount of the rotary shaft between the first rotary compression element and the second rotary compression element, the working of the rotary shaft is divided into more steps.
Thus, the manufacturing time that is spent on replacing parts becomes longer, and the cost (including the cost on change of the material type, working equipment and measuring instrument, etc.) due to the changing or replacements of parts becomes high.
The present invention resolves the problems caused by the conventional rotary compressor. An object of the present invention is to prevent unstable movements such as breakaway of the vane in the internal medium-pressure, multi-stage compression type rotary compressor using combustible refrigerant. It is another object of the present invention to improve the startability of the compressor.
Moreover, still another object of the present invention is to provide a multi-stage compression type rotary compressor and a setting method of displacem
Fujiwara Kazuaki
Matsumoto Kenzo
Sato Kazuya
Tsuda Noriyuki
Watabe Yoshio
J. C. Patents
Sanyo Electric Co,. Ltd.
Vrablik John J.
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