Endless belt power transmission systems or components – Resilient connection between pulley or guide-roll rim and mount
Reexamination Certificate
2000-11-21
2002-12-17
Hannon, Thomas R. (Department: 3682)
Endless belt power transmission systems or components
Resilient connection between pulley or guide-roll rim and mount
C474S199000, C464S073000, C464S089000
Reexamination Certificate
active
06494799
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a power transmission device provided with the function of a torque limiter. The present invention can be widely used in compressors, industrial machinery, etc.
Many kinds of this type of power transmission devices have been proposed. One is disclosed in Japanese Patent Laid-Open Publication No.311399/1998, which will be explained referring to
FIGS. 3
to
5
.
The power transmission device taught by Japanese Patent Laid-Open publication No.311399/1998 comprises a cylindrical rotor
22
made of ferro-alloy inserted in a pulley
21
. The rotor
22
is welded to the pulley
21
. A ball bearing
23
is disposed inside of the rotor
22
. The rotor
22
is supported to be rotatable by a cylindrical protrusion
25
a
of a front housing
25
of a compressor (driven device)
24
through the ball bearing
23
. A hub
27
operating as a driven rotary member is inserted in a rotary shaft
26
of the compressor
24
. The hub
27
has a substantially cylindrical shape as shown in FIG.
5
.
The hub
27
is splined to the rotary shaft
26
. A ring-shaped stopper plate
28
is welded to the hub
27
. A bolt
29
is inserted in the central hole of the stopper plate
28
to be threaded into a screw hole of the rotary shaft
26
, thereby fixing the hub
27
to the rotary shaft
26
. The stopper plate
28
locates the hub
27
relative to the rotary shaft
26
. Thus, the hub
27
can rotate integrally with the shaft
26
.
The hub
27
is provided with a cylindrical portion
27
c
at its one end distant from the compressor
24
. The cylindrical portion
27
c
is provided with an externally threaded portion
27
b
.The hub
27
is provided with a cylindrical portion
27
d
adjacent the cylindrical portion
27
c
. The outer diameter of the cylindrical portion
27
d
is larger than that of the cylindrical portion
27
c
. The periphery of the cylindrical portion
27
d
is partially cut away to form a pair of parallel flat chord portions
27
e
. The hub
27
is provided with a flange portion
27
a
adjacent the cylindrical portion
27
d
. The outer diameter of the flange portion
27
a
is larger than those of the cylindrical portions
27
c
and
27
d.
Three fragmentary-annular-ring-shaped convex segments
27
f
are formed on the periphery of the end face of the flange portion
27
a
close to the cylindrical portion
27
d
. The end face of the flange portion
27
a
close to the cylindrical portion
27
d
forms a concave segment
27
g
except at the fragmentary-annular-ring-shaped convex segments
27
f
. A cylindrical portion
27
h
is formed on the end face of the flange portion
27
a
close to the compressor
24
. The outer diameter of the cylindrical portion
27
h
is small enough to leave a relatively large space between its outer surface and the inner surface of the cylindrical protrusion
25
a
of the front housing
25
.
The power transmission device comprises a cylindrical outer holder
30
made of ferro-alloy. The outer holder
30
is provided with three radially outwardly protruding lugs
30
a
. The outer holder
30
is fixed to the pulley
21
by three bolts
37
penetrating the lugs
30
a
. The power transmission device comprises a cylindrical inner holder
31
made of a ferro-alloy such as stainless steel. The inner holder
31
is provided with a radially inwardly protruding flange
31
a.
A rubber ring
32
is disposed between the outer holder
30
and the inner holder
31
to be seized by them. Therefore, torque is transmitted from the pulley
21
through outer holder
30
and the rubber ring
32
to the inner holder
31
. The pulley
21
, the rotor
22
, the outer holder
30
, the rubber ring
32
and the inner holder
31
constitute a driving rotary member rotating integrally.
The flange
31
a
of the inner holder
31
fits snugly on the cylindrical portion
27
d
of the hub
27
to constitute a driving friction member. A washer
33
is disposed between the flange
31
a
of the inner holder
31
and the fragmentary-annular-ring-shaped convex segments
27
f
of the hub
27
to constitute an intermediate friction member.
The flange portion
27
a
of the hub
27
constitutes a first driven friction member. The end faces of the fragmentary-annular-ring-shaped con vexes
27
f
are coated with fluororesin coating material to reduce and stabilize the friction coefficient &mgr;
1
of the abutting surfaces between the fragmentary-annular-ring-shaped con vexes
27
f
and the washer
33
. The fluororesin coating material is an electrical insulating material that protects the fragmentary-annular-ring-shaped con vexes
27
f
from electric corrosion.
The washer
33
has annular-ring-shape as shown in FIG.
5
and is made of stainless steel or phosphor bronze. The washer
33
is provided with a central hole
33
a
and three fragmentary-annular-ring-shaped lugs
33
b
radially outwardly protruding from its outer periphery. The washer
33
snugly fits on the cylindrical portion
27
d
of the hub
27
. The shape and size of the fragmentary-annular-ring-shaped lugs
33
b
coincide with those of the fragmentary-annular-ring-shaped con vexes
27
f
of the hub
27
.
The washer
33
and the hub
27
are assembled so that the fragmentary-annular-ring-shaped lugs
33
b
abut the fragmentary-annular-ring-shaped convex segments
27
f
.
FIG. 3
shows the assembled condition in normal operation of the compressor
24
, wherein the fragmentary-annular-ring-shaped lugs
33
b
abut the fragmentary-annular-ring-shaped convex segments
27
f.
A washer
34
is disposed to sandwich the flange portion
31
a
of the inner holder
31
in collaboration with the washer
33
. The washer
34
constitutes a second driven friction member. The washer
34
is made of stainless steel and coated with fluororesin coating material to reduce and stabilize the friction coefficient of the abutting surfaces between the flange
31
a
of the inner holder
31
and the washer
34
. The fluororesin coating material is an electrical insulating material that protects the washer
34
from electric corrosion.
As shown in
FIG. 5
, the washer
34
is annular-ring-shaped and provided with a substantially hexagonal hole
34
a
having a pair of parallel straight edges
34
b
. The washer
34
fits on the pair of parallel flat chord portions
27
e
of the hub
27
to rotate integrally with the hub
27
.
A disk spring
35
is disposed adjacent the washer
34
. As shown in
FIG. 5
, the disk spring
35
is provided with a central circular hole
35
a
. The disk spring
35
fits on the cylindrical portion
27
c
of the hub
27
with its internal edge fitted snugly on the external side surface of the cylindrical portion
27
c.
A nut
36
is disposed adjacent the disk spring
35
to be threaded onto the externally threaded portion
27
b
of the hub
27
.
Fastening force acting on the nut
36
is transmitted to the disk spring
35
to axially compress it. Therefore, fastening force acting on the nut
36
determines the spring force (resilient reaction force) of the disk spring
35
. The spring force of the disk spring
35
presses the outer periphery of the disk spring
35
against the outer periphery of the washer
34
.
The friction coefficient &mgr;
1
of the abutting surfaces between the fragmentary-annular-ring-shaped convex segments
27
f
of the hub
27
and the fragmentary-annular-ring-shaped lugs
33
b
of the washer
33
is set at a small value of about 0.1.
Micro-irregularities are formed on the surface of the flange
31
a
of the inner holder
31
opposite the washer
33
by shot blasting or the like to set the friction coefficient &mgr;
2
of the abutting surfaces between the flange
31
a
of the inner holder
31
and the fragmentary-annular-ring-shaped lugs
33
b
of the washer
33
at a large value of about 0.25.
The friction coefficient &mgr;
3
of the abutting surfaces between the flange
31
a
of the inner holder
31
and the washer
34
is set at a small value substantially equal to the friction coefficient &mgr;
1
.
The procedure for assembling the power transmission device is as follow
Baker & Botts L.L.P.
Charles Marcus
Hannon Thomas R.
Sanden Corporation
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