Scroll compressor

Details Scroll compressor Scroll compressor

2002-05-31

2004-07-06

Denion, Thomas (Department: 3748)

Rotary expansible chamber devices

Working member has planetary or planetating movement

Helical working member, e.g., scroll

Reexamination Certificate

active

06758658

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a scroll compressor installed in an air conditioner, a refrigerator, or the like, and in particular, relates to the shape of a scroll member.
2. Description of Related Art
FIG. 6
shows a cross-sectional view of a scroll compressor which is conventionally used. The scroll compressor comprises housing
6
, fixed scroll member
1
which is fixed in housing
6
, and orbiting scroll member
2
which is provided in housing
6
so as to freely rotate therein. Front case
5
which supports the orbital movement of orbiting scroll member
2
is fixed at an opening end side of housing
6
, and shaft
7
which operates orbiting scroll member
2
so as to rotate is provided in front case
5
. In shaft
7
, crank pin
7
a
having axis X
2
which is offset from axis X
1
of shaft
7
is provided. This crank pin
7
a
is connected to boss
2
c
which is formed in the center of orbiting scroll member
2
.
Fixed scroll member
1
is composed of fixed end plate (end plate)
1
a
and spiral wall body
1
b.
Orbiting scroll member
2
is composed of orbiting end plate (end plate)
2
a
and spiral wall body
2
b.
Spiral wall body
2
b
of orbiting scroll member
2
is assembled to spiral wall
1
b
of fixed scroll member
1
, out of phase by 180 degrees, with spiral wall bodies
1
b
and
2
b
engaged with each other. Orbiting scroll member
2
orbitally moves with respect to fixed scroll member
1
via shaft
7
. Accordingly, a compression chamber is formed between spiral wall bodies
1
b
and
2
b.
The volume of the compression chamber is gradually reduced by this orbital movement so that fluid in the compression chamber is compressed. The compressed high pressure fluid is ultimately discharged from discharge port
1
c
which is provided in the center of fixed end plate
1
a.
In the above-described scroll compressor, the volume of the compression chamber, which is a crescent-shaped airtight space formed at the outermost portion by both scroll members
1
and
2
, is the volume of the fluid to be taken in, and the volume is gradually compressed. In order to increase the amount of the fluid to be taken in, that is, the volume to be compressed, it is required that the number of windings of each of spiral wall bodies
1
b
and
2
b
is increased or the height of each of spiral wall bodies
1
b
and
2
b
be increased. However, if the height of each of spiral wall bodies
1
b
and
2
b
be increased, there is a problem in that the rigidity of spiral wall bodies
1
b
and
2
b
against the compression reaction force of the fluid decreases.
In order to solve the above problem, the following construction is disclosed in Japanese Patent No. 1296413.
FIGS. 7A and 7B
are perspective views of fixed scroll member
1
and orbiting scroll member
2
proposed in Japanese Patent No. 1296413.
Fixed scroll member
1
is composed of fixed end plate
1
a
and spiral wall body
1
b
which is erected on a side surface of this fixed end plate
1
a.
This fixed end plate
1
a
is formed so as to correspond to the height of spiral wall body
2
b
of orbiting scroll member
2
to engage with a bottom portion by spiral wall body
1
b
which is composed of shallow bottom portion
1
d
(high site), which becomes high at the center side, and deep bottom portion
1
e
(low site), which becomes low at the outer peripheral end side.
Furthermore, orbiting scroll member
2
is composed of orbiting end plate
2
a
and spiral wall body
2
b
which is erected on a side surface of this orbiting end plate
2
a.
This orbiting end plate
2
a
is formed so as to correspond to the height of spiral wall body
1
b
of fixed scroll member
1
to engage with a bottom part of spiral wall body
2
b
which is composed of shallow bottom portion
2
d
(high site), which becomes high at the center side, and deep bottom portion
2
e
(low site), which becomes low at the outer peripheral end side.
At a side surface of each of end plates
1
a
and
2
a
of fixed scroll member
1
and orbiting scroll member
2
, bottom side step portion
3
(step portion), which is high at the center portion and low at the outer peripheral end side, is formed. Additionally, corresponding to bottom side step portion
3
of each of end plates
1
a
and
2
a,
wall body side step portion
4
(step portion), which is low at the center portion and high at the outer peripheral end side, is formed on the spiral top edge of each of spiral wall bodies
1
b
and
2
b.
As a result, bottom side step portion
3
of fixed scroll member
1
is engaged with wall body side step portion
4
of orbiting scroll member
2
, and bottom side step portion
3
of orbiting scroll member
2
is engaged with wall body side step portion
4
of fixed scroll member
1
. When orbiting scroll member
2
orbitally moves, wall body side step portion
4
provided on each of spiral wall bodies
1
b
and
2
b
slides along a circular arc of bottom side step portion
3
formed on each of end plates
1
a
and
2
a.
In scroll members
1
and
2
formed as described above, since the height of the compression chamber of the outer peripheral side is large, the outside diameter of the scroll compressor is not increased and, at the same time, the amount of the fluid to be incorporated can be increased. Furthermore, since the height of the compression chamber of the center side is small, the volume of the compression chamber is decreased and, at the same time, the rigidity of the wall bodies is improved.
In the scroll compressor having a structure such as described above, orbiting scroll member
2
undergoes various operations when compression is performed. These operations are explained with reference to FIG.
8
. In
FIG. 8
, shaft
7
(shown in
FIG. 6
) and crank pin
7
a
(shown in
FIG. 6
) are not shown.
As shown in
FIG. 8
, thrust direction gas force Fth and transverse gas force Fg due to the pressure of compression gas which is a fluid, and scroll driving force Fd due to crank pin
7
a
of shaft
7
acts on orbiting scroll member
2
.
In other words, thrust direction gas force Fth is a force drawing orbiting scroll member
2
from fixed scroll member
1
along the direction of axis X
1
(shown in
FIG. 6
) by gas pressure in the compression chamber. Additionally, transverse gas force Fg is a force drawing each of spiral wall bodies
1
b
and
2
b
along a transverse direction perpendicular to axis X
1
by has pressure in the compression chamber. Furthermore, scroll driving force Fd is a rotational driving force added to boss
2
c
by crank pin
7
a
which rotates around axis X
1
when shaft
7
rotates. Moreover, thrust force Fth is borne by an inside end surface of front case
5
on which orbiting scroll member
2
slides.
In the scroll compressor shown in
FIG. 8
, in order to obtain smooth orbital movement of orbiting scroll member
2
, a predetermined clearance
6
(hereinafter, called “tip clearance”) is provided between the end of spiral wall body
2
b
of orbiting scroll member
2
and fixed end plate
1
a
of fixed scroll member
1
.
By providing tip clearance &dgr;, smooth orbital movement of orbiting scroll member
2
is ensured and resistance to thermal expansion by heat during the process of producing high pressure fluid in scroll members
1
and
2
is also ensured. However, there are problems related to this which are explained below.
As described above, among the forces acting on orbiting scroll member
2
, as shown in
FIG. 8
, scroll driving force Fd and transverse gas force Fg act in opposite directions with respect to each other. As a result, moment M is produced which tends to overturn orbiting scroll member
2
or acts so that orbiting scroll member
2
becomes inclined. Furthermore, orbiting scroll member
2
tends to incline or overturn just by the present of tip clearance &dgr;. In this case, the upper edge of orbiting scroll member
2
exerts pressure force F against fixed end plate
1
a
of fixed scroll member
1
.
FIG. 9
is an enlarged side cross-sectional view of this state as seen f

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