Power transmission

Endless belt power transmission systems or components – Control for variable input to output speed-ratio – Condition responsive

Reexamination Certificate

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Details

C192S056500, C464S036000

Reexamination Certificate

active

06425837

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a torque limiting power transmission, and more specifically, to a mechanism for a power transmission suitable for use in compressors and other industrial equipment.
2. Description of Related Art
FIGS. 19 and 20
depict a known power transmission as described in JP-A-8-135752. Referring to
FIG. 20
, an inner lace of ball bearing
24
is fixed to inner cylindrical projecting portion
22
A of front housing
22
of compressor
21
. Rotor
25
is fixed to an outer race of ball bearing
24
. Pulley
26
is fixed to rotor
25
, and a first holding member
28
is fixed to pulley
26
by rivets
27
. Hub
29
is fixed to shaft
23
of compressor
21
via nut
30
. A second holding member
32
is fixed to hub
29
by rivets
31
. An elastic ring
33
made from a synthetic resin, or rubber is press-fitted between first holding member
28
and second holding member
32
.
Referring to
FIG. 19
, elastic ring
33
is formed in the shape of a petal, and a plurality of convex portions
33
A and concave portions
33
B are formed on inner and outer peripheries of elastic ring
33
, respectively. A plurality of concave portions
28
A and convex portions
28
B are formed on a periphery of first holding member
28
corresponding to the plurality of convex portions
33
A and concave portions
33
B of elastic ring
33
. A plurality of concave portions
32
A and convex portions
32
B are formed on an inner periphery of second holding member
32
corresponding to the plurality of convex portions
33
A and concave portions
33
B of elastic ring
33
.
When a torque is transmitted from pulley
26
to shaft
23
of compressor
21
, the respective convex portions
33
A and concave portions
33
B of elastic ring
33
deform due to compression of the respective concave portions
28
A and convex portions
28
H of first holding member
28
, and the respective concave portions
32
A and convex portions
32
B of second holding member
32
. Thus, the torque is transmitted by a reactive force. When an excessive torque relative to a preset value is generated by, for example, a seizure of compressor
21
, elastic ring
33
deforms, decreasing its thickness in the radial direction. As a result, elastic ring
33
slips against concave portions
32
A and convex portions
32
B of second holding member
32
, interrupting the transmission of the torque.
In such a known power transmission, because a plurality of concave portions and convex portions are provided along a radial axis of the first and second holding members respectively, even if the elastic ring slips, causing its convex portions and concave portions to escape from the concave portions and convex portions of the second holding member with which they were originally fitted, they may be re-fitted to the adjacent concave portions and convex portions of the second holding member, and the torque may be transmitted again.
Further, in such a known power transmission, because the elastic modulus of the elastic ring varies depending on the temperature of an area along a radial axis of the first and second holding members, respectively, the torque limiter may become unstable.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a stable power transmission, which may be unaffected by variation of the temperature of an area along a radial axis of the first and second holding members. It is another object of the present invention to provide a stable power transmission. It is yet another object of the present invention to prevent foreign material from entering the transmission. It is still another object of the present invention to prevent abrasion and rust. It is a further object of the present invention to maintain a torque interrupted condition once a torque is interrupted.
According to one embodiment of the invention, a power transmission has a drive side rotatable member having a plurality of tapered radial concave portions with each having a pair of tapered surfaces. The plurality of tapered radial concave portions are disposed in a radial direction along a radial axis of the drive side rotatable member. A driven side rotatable member is connected to a rotary shaft and has a plurality of radial and axial concave portions disposed in a radial direction along a radial axis of the driven side rotatable member. A plurality of balls are each moveable between each of the plurality of tapered radial concave portions and each of the plurality of radial and axial concave portions. A spring is provided on the driven side rotatable member. Further, a ring having an inclined surface is urged by the spring, whereby the ring presses each of the plurality of balls at a point at which the inclined surface is formed. The ring presses each of the plurality of balls to each of the plurality of tapered radial concave portions and to the driven side rotatable member when torque is transmitted. Further, the ring presses each of the plurality of balls to each of the pairs of tapered surfaces of each of the plurality of tapered radial concave portions and to the inclined surface of the ball pressing ring in order to move each of the balls into each of the plurality of radial and axial concave portions when a torque is interrupted. Accordingly, the present invention has a structure which may maintain torque in an interrupted condition once torque is interrupted.
Further, the driven side rotatable member may have an axial interior concave portion connected to each of the plurality of radial and axial concave portions, such that when torque is interrupted, each of the plurality of balls moves into the axial interior concave portion each of the plurality of radial and axial concave portions, thereby preventing each of the plurality of balls from moving radially.
In yet another embodiment, the drive side rotatable member may include a pulley, an outer ring fixed to the pulley, an inner ring pressing against each of the plurality of balls, and an elastic rubber member connecting the outer ring and the inner ring.
In a still another embodiment, the spring may be a belleville spring. An urging force of such a belleville spring presses against the ball pressing ring. The urging force may be adjusted by means of an adjusting screw.
In a further embodiment, a first seal member may provide a seal between an inner peripheral surface of the drive side rotatable member and a peripheral surface of the driven side rotatable member. A second seal member may provide a seal between the inner peripheral surface of the drive side rotatable member and a peripheral surface of the ball pressing ring, thereby forming an enclosed space.
In still a further embodiment, an enclosed area may be formed between a rubber member and the driven side rotatable member by creating a seal between an inner peripheral surface of the rubber member and a peripheral surface of the driven side rotatable member. An enclosed area also may be formed between a rubber member and the ball pressing ring by creating a seal between the inner peripheral surface of the rubber member and a peripheral surface of the ball pressing ring.
Further, an enclosed area may be formed between a ring-like seal member-fixed to the inner ring and the driven side rotatable member by creating a seal between the ring-like seal member-fixed to the inner ring and a peripheral surface of the driven side rotatable member and an enclosed area may be formed between between the rubber member and the ball pressing ring by creating a seal between an inner peripheral surface of the rubber member and a peripheral surface of the ball pressing ring.
In yet a further embodiment, an enclosed area may be formed between the rubber member and the driven side rotatable member by creating a seal between an inner peripheral surface of the rubber member and an enclosed area may be formed between the driven side rotatable member and a ring-like seal member-fixed to the inner ring by providing a seal between a peripheral surface of the driven side rotatable member and the ring-

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