Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
2001-04-12
2002-12-31
Vrablik, John J. (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
Reexamination Certificate
active
06499978
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to scroll compressors and, more particularly, to a scroll compressor provided with a scroll wrap designed at a predetermined section to be different from the other sections in thickness, thus being improved in its gas refrigerant compression efficiency.
2. Description of the Prior Art
FIG. 1
is a sectional view of a conventional scroll compressor.
FIG. 2
is a plan sectional view, showing the profile of the wraps of the fixed and orbiting scrolls of a conventional symmetric scroll compressor.
As shown in the drawings, the conventional symmetric scroll compressor has a main frame
20
and a sub-frame
25
, which are set within a hermetic casing
1
at upper and lower positions. In such a conventional symmetric scroll compressor, a compression part
10
, used for compressing gas refrigerant prior to discharging the compressed gas refrigerant, is set on the main frame
20
within the casing
1
. A motor
30
is set within the space defined between the main frame
20
and the sub-frame
25
, and is used for driving the compression part
10
.
The above motor
30
comprises a stator
31
and a rotor
33
, while the compression part
10
comprises a fixed scroll
11
and a orbiting scroll
15
. The fixed and orbiting scrolls
11
and
15
have involute wraps
11
a
and
15
a
, with a phase difference of 180° formed between the two wraps
11
a
and
15
a
, The two wraps
11
a
and
15
a
of the scrolls
11
and
15
engage with each other to form variable compression chambers C and C′ between them.
When the stator
31
of the motor
30
is turned on, the rotor
33
is rotated along with the motor shaft
35
, and so the orbiting scroll
15
is orbited relative to the fixed scroll
11
.
When the orbiting scroll
15
is orbited relative to the fixed scroll
11
as described above, the variable compression chambers C and C′ formed between the two wraps
11
a
and
15
a
of the scrolls
11
and
15
are gradually reduced in their volumes and are increased in their pressures in a direction toward the center of the compression part
10
. Therefore, it is possible to compress the gas refrigerant introduced into the compression part
10
through an inlet port
16
and to discharge the compressed gas refrigerant from the compression part
10
into a refrigerant discharging pipe through an outlet port
19
. Such a gas refrigerant compressing process of the conventional symmetric scroll compressor is shown in
FIG. 4
in detail.
In order to minimize a loss during the gas refrigerant compressing process, it is necessary to prevent a leakage of compressed gas refrigerant. In the conventional symmetric scroll compressor, the compressed gas refrigerant may leak in a radial direction through axial gaps and leak in a tangential direction through radial gaps.
Such a tangential leakage of compressed gas refrigerant through radial gaps is caused by the gaps formed between the two wraps
11
a
and
15
a
at a plurality of tangential contact points P of the two scrolls
11
and
15
.
FIG. 3
is a view, showing the design factors of a conventionally designed scroll of the conventional symmetric scroll compressor.
As shown in the drawing, the wrap
11
a
or
15
a
of each of the fixed and orbiting scrolls
11
and
15
of the conventional symmetric scroll compressor is shaped as an involute curve, comprising an inside involute and an outside involute designed to have a phase difference of ±&agr; between them. Each of the wraps
11
a
and
15
a
also has a constant thickness T.
That is, the thickness T of each wrap
11
a
or
15
a
is expressed as follows: T=L
0
−L
i
=a (&thgr;+&agr;)−a (&thgr;−&agr;)=2a&agr;. This means that each wrap
11
a
or
15
a
has a constant thickness T from the first to the last.
However, such a conventional symmetric scroll compressor is problematic due to the constant thickness of the wraps
11
a
and
15
a
, That is, since the wraps
11
a
and
15
a
of the fixed and orbiting scrolls
11
and
15
of the conventional symmetric scroll compressor have such a constant thickness T as described above, a plurality of gaps are undesirably formed between the two wraps
11
a
and
15
a
at the tangential contact points P of the two scrolls
11
and
15
as shown in
FIG. 2
due to a requirement of machining allowance and/or assembling allowance of the two wraps
11
a
and
15
a
. In addition, the size of such gaps is not uniform, and so the amounts of leaking gas refrigerant from the compression chambers C and C′ of the compression part
10
are different from each other. This finally causes a reduction in the gas refrigerant compression efficiency and an increase in operational noises of such a conventional symmetric scroll compressor.
If the profile of each wrap
11
a
or
15
a
of the two scrolls
11
and
15
is shaped as an ideal involute curve, it is possible to allow the tangential contact points P of the two scroll wraps
11
a
and
15
a
to be completely free from such undesired gaps or to have only negligible gaps. In such a case, the symmetric scroll compressor accomplishes desired gas refrigerant compression efficiency. However, it is practically impossible to form such an ideal involute curve in the scroll wraps
11
a
and
15
a
due to a requirement of machining allowance and/or assembling allowance of the two wraps
11
a
and
15
a
, Therefore, a plurality of gaps having different sizes are formed at the tangential contact points P of the two scroll wraps
11
a
and
15
a
, thereby undesirably allowing a leakage of compressed gas refrigerant. This results in a reduction in the gas refrigerant compression efficiency and an increase in operational noises of the conventional symmetric scroll compressors.
FIG. 5
is a plan sectional view, showing the profile of the wraps of the fixed and orbiting scrolls of a conventional asymmetric scroll compressor.
As shown in the drawings, the conventional asymmetric scroll compressor is designed such that the involute terminal angle &phgr;e′ of the fixed scroll wrap
15
′ is larger than the involute terminal angle &phgr;e of the orbiting scroll wrap
11
′ at an angle of 180°, with a plurality of variable compression chambers formed between the two scroll wraps
11
′ and
15
′. This asymmetric scroll compressor is preferably increased in the volume of its sucked gas refrigerant by at least 10% in comparison with the conventional symmetric scroll compressor without changing the inner diameters of the main and sub-frames.
In such scroll compressors, the term “involute terminal angle of a scroll wrap” means an angle formed between the initial end and the terminal end of the scroll wrap.
Different from the conventional symmetric scroll compressor, the conventional asymmetric scroll compressor has only one gas refrigerant suction part, and so the asymmetric scroll compressor does not have any gas refrigerant suction passage formed around the outer edge of the orbiting scroll. Therefore, this asymmetric scroll compressor is less likely to overheat the sucked gas refrigerant, and is improved in its volume efficiency in comparison with the symmetric scroll compressor. The asymmetric scroll compressor is thus allowed to gradually and smoothly suck gas refrigerant into its compression part, and is remarkably reduced in its pulse vibration in comparison with the symmetric scroll compressor when the compressed air refrigerant is discharged from the compressor.
However, the conventional asymmetric scroll compressor is problematic as follows. That is, the asymmetric scroll compressor uses the extended inside involute section &phgr;e~&phgr;e′ of the fixed scroll wrap
11
′ as a compression chamber different from the conventional symmetric scroll compressor which does not use such an inside involute section &phgr;e~&phgr;e′ as the compression chamber. In addition, the fixed and orbiting scrolls of the asymmetric scroll compressor are designed such that the
Chang Young Il
Cho Yang Hee
Lee Byeong Chul
LG Electronics Inc.
Vrablik John J.
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