Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
1999-10-15
2001-04-17
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
Reexamination Certificate
active
06217301
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a scroll fluid machine such as a scroll compressor and a scroll expansion device.
BACKGROUND ART
FIG. 2
illustrates first and second spiral bodies
1
and
2
in a scroll fluid machine disclosed in Japanese Patent Laying-Open No. 60-252102. In
FIG. 2
, the first spiral body
1
corresponds to a fixed scroll and the second spiral body
2
corresponds to a movable scroll.
As shown in
FIG. 2
, a discharge port
3
is provided in the vicinity of winding starting ends of the first and second spiral bodies
1
and
2
in order to discharge compressed refrigerant. A thickness t4 of the first spiral body
1
located in the vicinity of discharge port
3
is defined to be larger than a thickness t5 of a winding finishing end of the first spiral body
1
. The second spiral body
2
is similarly shaped.
The increased thickness t4 of the winding starting ends of the first and second spiral bodies
1
and
2
in the vicinity of discharge port
3
can enhance the strength of the portion near the winding starting ends of the first and second spiral bodies
1
and
2
, and prevent leakage of refrigerant occurring at the central portion.
However, the increased thickness at the central portion of the spiral bodies causes a problem described below. Using
FIG. 3
, the problem is described.
FIG. 3
shows a relation between pressure and volume in a compression chamber formed by the first and second spiral bodies
1
and
2
, where P1 and P1′ represent the pressure in the compression chamber when refrigerant is discharged, P2 represents the pressure in the compression chamber when the refrigerant is taken in, V1 represents the volume of the compression chamber when the refrigerant is taken in, and V2 represents the volume of the compression chamber when the refrigerant is discharged.
Since the thickness t4 of the winding starting ends of the first and second spiral bodies
1
and
2
is increased as described above, an opening area of discharge port
3
is small unless the first and second spiral bodies
1
and
2
are enlarged. Discharge resistance of the refrigerant from discharge port
3
accordingly increases to excessively raise the pressure in the compression chamber from P1 to P1′, for example, as shown in
FIG. 3
when the refrigerant is discharged, which is referred to as phenomenon of excessive compression. As a result, an extra work W becomes necessary, leading to increase in loss.
DISCLOSURE OF THE INVENTION
The present invention is made to solve such a problem as described above. An object of the invention is to prevent occurrence of the phenomenon of excessive compression in a scroll fluid machine having a pair of spiral bodies where the thickness thereof increases in a direction from winding finishing ends toward winding starting ends.
According to the invention, a scroll fluid machine includes first and second spiral bodies having the thickness increasing in a direction from winding finishing ends toward winding starting ends, first and second compression chambers formed between the first and second spiral bodies and located on the innermost side, and a discharge port discharging compressed refrigerant successively from the first and second compression chambers. The scroll fluid machine is provided with a refrigerant discharge timing advancing means for advancing the timing at which refrigerant is discharged from the first compression chamber relative to the refrigerant discharge timing of the second compression chamber.
The refrigerant discharge timing advancing means thus provided allows the timing at which refrigerant is discharged from the first compression chamber to precede the refrigerant discharge timing of the second compression chamber. Discharge resistance of the refrigerant is accordingly reduced compared with the conventional machine to prevent the excessive compression from happening.
In the scroll fluid machine according to the invention, the first spiral body has an extension which prolongs the winding finishing end of the first spiral body to a region near the winding finishing end of the second spiral body, and the discharge port has an opening advancing portion for opening the first compression chamber earlier. The refrigerant discharge timing advancing means includes the extension and the opening advancing portion.
The extension thus provided to the first spiral body enables the pressure in the first compression chamber to rise to a desired pressure earlier than the second compression chamber, for example. The first compression chamber where the pressure attains the desired pressure can be opened relatively earlier to discharge the refrigerant, since the discharge port has the opening advancing portion. Accordingly, the timing at which the refrigerant is discharged from the first compression chamber can be made earlier than the refrigerant discharge timing of the second compression chamber, so that the discharge resistance of the refrigerant can be decreased.
The opening advancing portion is preferably formed by expanding the discharge port toward the first compression chamber.
The thickness of the winding finishing end of the first spiral body is preferably smaller than that of the winding finishing end of the second spiral body.
Preferably, the thickness of the extension gradually decreases toward the winding finishing end of the first spiral body.
The scroll fluid machine according to the invention is preferably provided with one intake port for taking in the refrigerant.
Further, the scroll fluid machine according to the invention includes a movable scroll and a fixed scroll, the first spiral body is provided at the fixed scroll, and the second spiral body is provided at the movable scroll.
The thickness of the second spiral body in the vicinity of its winding starting end is preferably larger than that of the first spiral body in the vicinity of its winding starting end, and the opening advancing portion preferably has a shape which allows the opening advancing portion to be closed temporarily by a part near the winding starting end of the second spiral body. Referring to
FIG. 1
, for example, an opening advancing portion (
3
a
) is temporarily closed by a part near a winding starting end (
2
a
) of a second spiral body (
2
) immediately before the refrigerant is discharged from a first compression chamber (
4
).
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Kajiwara Mikio
Kuroiwa Hiroyuki
Ueda Shusaku
Yoshii Toshiaki
Yoshimura Keiji
Burns Doane , Swecker, Mathis LLP
Daikin Industries Ltd.
Denion Thomas
Trieu Theresa
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