Asymmetric scroll compressor

Details Asymmetric scroll compressor Asymmetric scroll compressor

2000-12-18

2002-11-12

Denion, Thomas (Department: 3748)

Rotary expansible chamber devices

Working member has planetary or planetating movement

Helical working member, e.g., scroll

C418S055300, C418S055100

Reexamination Certificate

active

06478556

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an asymmetric scroll compressor, and more particularly, the present invention relates to an asymmetric scroll compressor which can minimize a reverse rotation torque of an orbiting scroll, keep constant a direction of force acting on an Oldham ring to prevent reversal of rotation toque of the orbiting scroll, and reduce to the minimum unbalanced force of discharging gas generated upon a discharging stroke.
2. Description of the Related Art
Generally, a compressor serves as a machine for compressing fluid such as air, refrigerant gas or the like. The compressor is composed of a power generating section for generating driving force and a compressing mechanism section for compressing gas using the driving force which is transferred from the power generating section. Compressors are generally divided into rotary compressors, reciprocating compressors and scroll compressors, depending upon structures of compressing mechanism sections.
FIG. 1
illustrates a compressing mechanism section of a scroll compressor. As shown in
FIG. 1
, a compressing mechanism section of a scroll compressor includes a frame
1
. n orbiting scroll
4
which has a wrap
4
a
of an involute curve-shaped configuration, is seated on an upper surface of the framer. A fixed scroll
3
is coupled to the orbiting scroll
4
in such a way as to cover the orbiting scroll
4
. The fixed scroll
3
is formed, on a lower surface thereof, with a wrap
3
a
which has an involute curve-shaped configuration, and is defined, at a center portion thereof, with a discharging hole
3
b
. The fixed scroll
3
and the orbiting scroll
4
cooperate with each other to define compression chambers P therebetween. A boss part
4
b
which is projectedly formed on a lower surface of the orbiting scroll
4
, is connected with an eccentric part
2
a
of a rotation shaft
2
which in turn is connected with a power generating section (not shown).
An Oldham ring
30
for preventing rotation of the orbiting scroll
4
is disposed between the frame
1
and the orbiting scroll
4
.
FIG. 2
illustrates in further detail a coupling relationship of the Oldham ring
30
As shown in
FIG. 2
, the Oldham ring
30
has a ring-shaped configuration. First and second keys
32
and
33
each having a square column-shaped configuration are projectedly formed on an upper surface of the Oldham ring
30
and located along a first straight line. Third and fourth keys
34
and
35
each having a square column shaped configuration are projectedly formed on a lower surface of the Oldham ring
30
and located along a second straight line which is orthogonal to the first straight line along which the first and second keys
32
and
33
are located.
The lower surface of the orbiting scroll
4
is defined, along the first straight line, with first and second key grooves
4
c
and
4
d
, in a manner such that the first and second keys
32
and
33
of the Oldham ring
30
are respectively fitted into the first and second key grooves
4
c
and
4
d
. Also, the upper surface of the frame
1
is defined, along the second straight line, with third and fourth key grooves
1
a
and
1
b
, in a manner such that the third and fourth keys
34
and
35
of the Oldham ring
30
are respectively fitted into the third and fourth key grooves
1
a
and
1
b.
The Oldham ring
30
is disposed between the frame
1
and the orbiting scroll
4
, so that the first and second keys
32
and
33
are respectively fitted into the first and second key grooves
4
c
and
4
d
of the orbiting scroll
4
and the third and fourth keys
34
and
35
are respectively fitted into the third and fourth key grooves
1
a
and
1
b
of the frame
1
.
In the compressing mechanism section, if driving force is transferred from the power generating section to the rotation shaft
2
, the orbiting scroll
4
which is secured to the rotation shaft
2
, is orbited in a state wherein the orbiting scroll
4
is engaged with the fixed scroll
3
and prevented by the Oldham ring
30
from being rotated. By orbiting motion of the orbiting scroll
4
, relative movement of the wraps
3
a
and
4
a
which are respectively formed on the fixed scroll
3
and the orbiting scroll
4
and each of which has the involute curve-shaped configuration, is induced, whereby it is possible to continuously intake, compress and discharge gas.
Hereinbelow, a compression principle of the scroll compressor will be described with reference to FIG.
3
. By the fact that the fixed scroll
3
which has the wrap
3
a
of the involute curve-shaped configuration and the orbiting scroll
4
which has the wrap
4
a
of the involute curve-shaped configuration, are engaged with each other in a state wherein the wraps
3
a
and
4
a
have a phase difference of 180° therebetween, crescent-shaped compression chambers P are respectively created at opposite positions. In this situation, when the orbiting scroll
4
is orbited with respect to the fixed scroll
3
which is secured to the frame
1
in a state wherein the orbiting scroll
4
is prevented by the Oldham ring
30
from being rotated, as the compression chambers P are moved toward a center of the scroll compressor, volumes of the respective compression chambers P are reduced and thereby a compressing function of the scroll compressor is performed.
More concretely speaking this compressing procedure, refrigerant gas which is introduced into the scroll compressor, flows into the fixed scroll
3
through an intake port (not shown) which is defined through a side wall of the fixed scroll
3
.
At this time, one part of the intaken gas flows into a first compression chamber P
1
which is defined adjoining the intake port of the fixed scroll
3
, and then, a compressing process is undertaken. At the same time, the other part of the intaken gas flows, along a guide passage which is defined through the fixed scroll
3
, into a second compression chamber P
2
which is defined directly opposite to the first compression chamber P
1
to be placed at a 180° separation from the first compression chamber P
1
, and then, a compressing process is undertaken. As the orbiting scroll
4
is orbited, the refrigerant gas existing in the compression chambers P, which refrigerant gas is undertaken to be symmetrically and simultaneously compressed, is further compressed while being moved toward the center of the scroll compressor, and then, is discharged through the discharging hole
3
b
which is defined at the center portion of the fixed scroll
3
.
On the other hand, in the case of an asymmetric scroll compressor, as can be readily seen from
FIG. 4
, by the fact that a wrap
5
a
of a fixed scroll
5
is formed in such a way as to be longer than a wrap
6
a
of an orbiting scroll
6
by 180° or less, it is possible to intake an increased amount of refrigerant gas into the same volume when compared to a conventional symmetric scroll compressor, whereby a stroke volume is raised. Also, because it is possible to prevent the refrigerant gas which is intaken into the compression chambers P, from being heated, an intake amount of the refrigerant gas can be further increased.
In the meanwhile, referring to
FIG. 5
, in the scroll compressor, a rotation torque of the orbiting scroll is calculated by an equation given below:
Mt=Ft×{&bgr;−r
cos (&dgr;
e
−&thgr;)}
where Ft is gas force acting in a tangential direction, &bgr; is a distance from a center of the orbiting scroll to an application point of the gas force Ft, r is an eccentricity between a center of an end plate of the orbiting scroll and a center of a base circle of an involute curve of the orbiting scroll wrap, &thgr; is a crank angle, and &dgr;be is an eccentric angle which is measured at an outer end of the wrap toward a direction where the wrap is wound up.
In the case of a conventional symmetric scroll compressor, due to the fact that pressures in two compression chambers are the same with each other, since &bgr; is constant as ½&eg

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