Rotary expansible chamber devices – Working member has planetary or planetating movement – Helical working member – e.g. – scroll
Reexamination Certificate
1999-02-05
2001-03-27
Denion, Thomas (Department: 3748)
Rotary expansible chamber devices
Working member has planetary or planetating movement
Helical working member, e.g., scroll
C418S055100, C464S103000, C464S102000, C384S609000, C384S608000, C384S615000, C384S617000
Reexamination Certificate
active
06206665
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a scroll type fluid machine such as a compressor, a vacuum pump or an expander and more particularly, to a mechanism for inhibiting rotation of a movable scroll of the fluid machine revolving at the time of operation of the fluid machine.
A rotation inhibiting mechanism for the movable scroll of a prior art scroll type compressor described in Japanese Patent Unexamined Publication (JP-A) No. 310685/1997 will be described.
At the outset, a first technology of the prior art scroll type compressor will be described by referring to
FIGS. 1 through 3
. In
FIG. 1
, a housing
10
of the scroll type compressor is provided with a rear housing
10
a
in the shape of a large-diameter bottomed cylinder and a front housing
10
b
formed of a large-diameter cylindrical portion
10
b
1
and a small-diameter cylindrical portion
10
b
2
and fixed to an open end of the rear housing
10
a.
Further, the rear housing
10
a
and the front housing
10
b
are arranged concentric with each other.
Further, a shaft
11
extends into the housing
10
along the central axis X of the latter through the small-diameter cylindrical portion
10
b
2
of the front housing
10
b.
The shaft
11
is provided with a small-diameter portion
11
a
surrounded by the small-diameter cylindrical portion
10
b
2
of the front housing
10
b
and a large-diameter portion
11
b
surrounded by the large-diameter cylindrical portion
10
b
1
. To one end surface of the large-diameter portion
11
b
there is fixed a driving pin
12
extending parallel to, and eccentric with, the axis X. The shaft
11
is rotatably supported by the large-diameter cylindrical portion
10
b
1
of the front housing
10
b
through a ball bearing
13
while the small-diameter portion
11
a
is rotatably supported by the small-diameter cylindrical portion
10
b
2
of the front housing
10
b
through a ball bearing
14
.
At a position radially and outwardly of the small-diameter cylindrical portion
10
b
2
of the front housing
10
b
there is arranged an electromagnetic clutch
15
. The electromagnetic clutch
15
rotatably fits about the small-diameter cylindrical portion
10
b
2
of the front housing
10
b
and is provided with a pulley
15
a
connected to an external driving source (not shown) by means of a V-belt (not shown), an exciting coil
15
b
fixed to the small-diameter cylindrical portion
10
b
2
and a rotation transmitting plate
15
c
fixed to one end of the small-diameter portion
11
a
of the shaft
11
. Thus, the shaft
11
is rotated by the external driving source (not shown) through the electromagnetic clutch
15
.
Within the rear housing
10
a
there is arranged a fixed scroll
16
.
The fixed scroll
16
is provided with a disk-shaped end plate
16
a
which fits in the rear housing
10
a
arranged coaxially with the axis X, a spiral body
16
b
formed on one of the surfaces of the end plate
16
a
and legs
16
c
formed on the other surface of the end plate
16
a.
At the center of the end plate
16
a
there is formed a discharge hole
16
a
1
. The fixed scroll
16
is fixed to the rear housing
10
a
by means of bolts
17
while the legs
16
c
are held in contact with the bottom
10
a
1
of the rear housing
10
a.
The space within the rear housing
10
a
is divided into an intake chamber
18
and a discharge chamber
19
by means of the end plate
16
a
of the fixed scroll
16
.
Within the rear housing
10
a
there is disposed a movable scroll
20
as a revolving member lying adjacent to the fixed scroll
16
. The movable scroll
20
is provided with a disk-shaped end plate
20
a,
a spiral body
20
b
formed on one of the surfaces of the end plate
20
a
and an annular boss
20
c
formed on the other surface of the end plate
20
a.
The central axis of the end plate
20
a
is eccentric with the axis X. The spiral body
20
b
of the movable scroll
20
engages with the spiral body
16
b
of the fixed scroll
16
.
Within the boss
20
c
there is rotatably fitted, through a needle bearing
22
, a thick disk-shaped bush
21
disposed concentric with the end plate
20
a.
Further, the bush
21
is provided with an eccentric through hole
21
a
extending parallel to the axis X and a balance weight
23
extending in the radial direction is fixed to the bush
21
. The through hole
21
a
houses the driving pin
12
fixed to the large-diameter portion
11
b
of the shaft
11
so as to allow the pin
12
to slide therein.
A fixed race
24
is fixed to one end of the large-diameter cylindrical portion
10
b
1
of the front housing
10
b
and a movable race
25
is fixed to the end plate
20
a
of the movable scroll
20
. Further, a plurality of balls
26
are interposed between the fixed race
24
and the movable race
25
in spaced apart relationships with one another in the circumferential direction and a ball coupling for preventing the rotation of the movable scroll
20
, that is, a rotation inhibiting mechanism is constructed by these races
24
and
25
and the plurality of balls
26
.
The above-described ball coupling will be described with reference to
FIGS. 2A and 2B
. Each of the fixed race
24
and the movable race
25
is formed by a press using a ferrous material and is in the shape of an annular ring. The fixed race
24
is provided on one of the surfaces thereof with a plurality of annularly extending ball rolling grooves
24
c
which are spaced apart from one another in the circumferential direction and likewise, the movable race
25
is provided on one of the surfaces thereof with a plurality of annularly extending ball rolling grooves
25
c
which are spaced apart from one another in the circumferential direction. The balls
26
are made of a bearing steel material and are interposed between the fixed race
24
and the movable race
25
in a state in which they are held sandwiched by the rolling grooves
24
c
of the fixed race
24
and the opposing ball rolling grooves
25
c
of the movable race
25
.
To continue to describe further the present invention by referring to
FIG. 3
, the inner surface of the ball rolling groove
24
c
includes an inner peripheral portion
24
c
1
having a curved surface of a radius of curvature R
1
, an outer peripheral portion
24
c
2
having a curved surface of a radius of curvature of R
2
and a bottom portion
24
c
3
connecting the portions
24
c
1
and
24
c
2
while the inner surface of the ball rolling groove
25
c
includes an inner peripheral portion
25
c
1
having a curved surface of a radius of curvature of R
1
, an outer peripheral portion
25
c
2
having a curved surface of a radius of curvature of R
2
and a bottom portion
25
c
3
connecting the portions
25
c
1
and
25
c
2
. The radius of curvature R
1
and the radius of curvature R
2
may be the same or somewhat different from each other. Anyway, the radii of curvature R
1
and R
2
bear close resemblance to the radius of each of the balls
26
and are set to a value slightly larger than the value of the radius of each of the balls
26
.
The bottom portions
24
c
3
and
25
c
3
are each in the form of a flat surface so as to become tangential to the inner peripheral portions
24
c
1
and
25
c
1
and the outer peripheral portions
24
c
2
and
25
c
2
, respectively. In other words, the bottom portions
24
c
3
and
25
c
3
form themselves geometrical curved surfaces of large radii of curvature gently connecting the inner peripheral portions
24
c
1
and
25
c
1
to the outer peripheral portions
24
c
2
and
25
c
2
, respectively. The central diameter of each of the curved bottom portions
24
c
3
and
25
c
3
is set to a value substantially identical with the radius of revolutionary motion of the movable scroll
20
. Further, the size of the width of each of the bottom portions
24
c
3
and
25
c
3
is set to one-third of the width of the effective ball rolling locus and it is desirable to set this size to a value which is determined in anticipation of an error of the shape of each of the scrolls of the scroll type compressor, an error of the attachmen
Baker & Botts L.L.P.
Denion Thomas
Sanden Corporation
Trieu Thai-Ba
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