Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
2000-06-07
2001-11-27
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S055400, C418S055500
Reexamination Certificate
active
06322340
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scroll compressor, and in particular to a scroll compressor suitable for a vapor compression refrigerating cycle that uses a refrigerant having the supercritical region of carbon dioxide (CO
2
), for example.
2. Description of the Related Art
Recently, a refrigeration cycle using carbon dioxide (referred to hereinbelow as a “carbon dioxide cycle”) as a working gas (refrigerant gas) has been proposed, for example, in Japanese Examined Patent Application, Second Publication, No. Hei 7-18602, as one measure for eliminating the use of Freon (dichlorofluoromethane) as a refrigerant in the vapor compression-type refrigerating cycle. This carbon dioxide cycle is identical to the conventional vapor compression-type refrigerating cycle that uses Freon. That is, as shown by A-B-C-D-A in
FIG. 5
, which shows a carbon dioxide Mollier chart, the carbon dioxide in the gaseous phase is compressed by a compressor (A-B), and this gas-phase carbon dioxide that has been compressed to a high temperature is cooled in a radiator, such as a gas cooler (B-C). Next, the carbon dioxide is decompressed using a decompressor (C-D), the carbon dioxide that has changed to a liquid phase is vaporized (D-A), and an external fluid such as air is cooled by removing its latent heat of vaporization.
However, the critical temperature of carbon dioxide is about 31°, which is low compared to the critical temperature of Freon, the conventional refrigerant. When the external temperature is high, during summer, for example, the temperature of carbon dioxide on the radiator side is higher than its critical temperature. This means that the carbon dioxide does not condense at the radiator outlet side. In
FIG. 5
, this is shown by the fact that the line BC does not cross the saturated liquid line SL. In addition, the state on the radiator output side (point C) is determined by the discharge pressure of the compressor and the temperature of the carbon dioxide at the radiator outlet side. Moreover, the temperature of the carbon dioxide at the radiator outlet side is determined by the radiating capacity of the radiator and the temperature of the uncontrollable external air. Due to this, the temperature at the radiator outlet cannot be substantially controlled. Therefore, the state of the radiator outlet side (point C) can be controlled by the discharge pressure of the compressor, that is, the pressure on the radiator outlet side. This means that in order to guarantee sufficient refrigerating capacity (difference in enthalpy) when the temperature of the external air is high, during summer, for example, as shown by E-F-G-H-E, the pressure on the radiator output side must be high. In order to attain this, the operating pressure of the compressor must be high in comparison to the refrigeration cycle used with conventional Freon. In the case of an air conditioning device for an automobile, for example, the operating pressure of the compressor when using Freon (Trademark R134) is about 3 kg/cm
2
, while in contrast, this pressure must be raised to about 40 kg/cm
2
for carbon dioxide. In addition, the operation stopping pressure when using Freon (Trademark R134) is about 15 kg/cm
2
, while in contrast it must be raised to about 100 kg/cm
2
for carbon dioxide.
Below, referring to
FIG. 6
, a typical scroll compressor as disclosed in Japanese Unexamined Patent Application, First Publication, No. Hei 5-149270, will be explained. As shown in
FIG. 6
, in a casing (not illustrated), a fixed scroll member
100
, an orbiting scroll member
101
, and an eccentric axle
102
are provided.
The fixed scroll
100
is formed by an end plate
100
a
providing a discharge port for discharging the compressor working gas (not illustrated) and an involute wrap
106
b
provided on one face of this end plate
100
a.
The orbiting scroll
101
is formed by an end plate
101
a
comprising an involute wrap side end plate
105
and an eccentric axle side end plate
106
, an involute wrap
101
b
provided on the face of the involute wrap side end plate
105
facing the end plate
100
a
of the fixed scroll, and an engagement part
103
provided on the face of the eccentric axle side end plate
106
not facing the involute wrap side end plate
105
, and accommodating therein the eccentric axle
102
, described below. The involute compression chamber
104
is formed by installing the fixed scroll
100
and the orbiting scroll
101
in the casing such that the involute wrap
100
b
of the fixed scroll
100
and the involute wrap
101
b
of the orbiting scroll
101
intermesh. Thereby, when the orbiting scroll
101
is rotated eccentrically with respect to the fixed scroll
100
by rotating the eccentric axle
102
installed in the engagement part
103
, while the working gas in the casing is compressed in compression chamber
104
, the working gas can be discharged from the discharge port provided on the end plate
100
a
of the fixed scroll
100
.
Moreover, as explained above, a scroll compressor using carbon dioxide as a working gas requires a high revolution and pressure. Thus, there is a concern of a deterioration in capacity due to leakage of the working gas. In order to prevent this, the orbiting scroll
101
presses against the fixed scroll
100
. That is, along the axial direction of the orbiting scroll
101
, the end plate
100
a
thereof is divided into an involute wrap side end plate
105
providing an involute projection
10
b
and an eccentric axle side end plate
106
providing an engagement part
103
. In addition, an sealed space
107
is formed between the involute wrap side end plate
105
and the eccentric axle side end plate
106
. Furthermore, on the involute wrap side end plate
105
, a narrow hole
108
is formed for introducing the high pressure working gas in the compression chamber
104
into the sealed space
107
. Moreover, in
FIG. 6
, reference numeral
109
denotes a seal part for sealing the sealed space
107
.
By adopting this kind of structure, one part of the high pressure working gas in the compression chamber
104
is introduced into the sealed space
107
via the narrow hole
108
, and fills the sealed space
107
. When comparing the upward force operating from the sealed space
107
on the involute wrap side end plate
105
and the downward force operating from the compression chamber
104
on the involute wrap side end plate
105
, the upward force is greater than the downward force, and thus the involute wrap side end plate
105
rises up as a whole and presses against the fixed scroll
100
side. Therefore, the end plate
100
a
of the fixed scroll
100
and the end plate
105
of the orbiting scroll
101
are on intimate contact. Thus, gas leakage from between the fixed scroll
100
and the orbiting scroll
101
is inhibited.
However, in the above-described conventional scroll compressor, the revolution of the eccentric axle side end plate
106
of the orbiting scroll
101
must be transmitted to the involute wrap side end plate
105
via the above-described seal member
109
. Thus, there is the problem of low transmission efficiency.
Thus, the friction on the seal member
109
becomes severe, and there is the problem that the operation of replacing the seal member
109
requires labor.
Furthermore, as described above, in the conventional scroll compressor, a compressed working gas is used, and the involute wrap side end plate
105
is pressed against the fixed scroll
100
side. However, in particular during operation of the scroll compressor, the compression or the working gas does not become sufficiently high, and thus the force pushing the involute wrap side end plate
105
against the fixed scroll
100
is weak and the compression efficiency is low.
In consideration of the above-described problems, it is an object of the present invention to provide a scroll compressor that transmits rotation of the eccentric axle side end plate
106
of the orbiting scroll to the involute wrap side end plate
105
with good efficiency,
Itoh Takahide
Mizuno Hisao
Mitsubishi Heavy Industries Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Vrablik John J.
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