Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a torque
limiter having facing members that are elastically held
between driving-side frictional transmission members and
driven-side frictional transmission members.
Conventionally, asbestos or asbestos coated with
synthetic resin of the epoxy-type has been used for facing
members in torque limiters. In such cases, however, the
torque limiters have proven to be inconvenient since the
maximum value of torque to be transmitted is not easily
determined. Thus, when asbestos facing members are used,
close contact between the facing members and transmission
members may not be obtained. Accordingly, a predetermined
coefficient of friction is not easily provided with initial
use and abrasive powder lS readily produced during such
use. After a predetermined period of time, the coefficient
of friction of the facing members will be sharply reduced
due to this abrasive powder, thereby changing considerably
the maximum value of torque to be transmitted.
on the other hand, when facing members of
asbestos coated with synthetic resin are used, such facing
members are susceptible to influencesarising from friction
heating, thus making it difficult to obtain a stable co-
efficient of friction for the facing members.
In view of the above, the present invention
provides a friction-type torque limiter in which the co-
efficient of friction of facing members may be stabilized
so as to stabilize the maximum value of torque to be
transmitted, thus enabling continuously stable transmission
operations.
In accordance with one aspect of the present
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invention, the friction-type torque limiter comprises a
driving-side frictional transmission member, a driven-side
frictional transmission member, a facing member having
copper-type sintered alloy friction surfaces disposed in-
termediate the transmission members, and means for elas-
tically holding the facing member in frictionally engaging
relation with the transmission members.
In accordance with a second aspect of the in-
vention, the friction-type torque limiter comprises a
plurality of driving-side frictional -transmission members
disposed unlformly in spaced apart relation, a plurality
of driven-side frictional transmission members, individual
ones of which being disposed intermediate adjacent pairs of
the driving-side frictional transmission members, a plurality
of facing members having copper-type sintered alloy friction
surfaces,individual ones of the facing members being disposed
intermediate adjacent pairs of the driving-side and driven-
side frictional transmission members and means for elas-
tically holding the facing members in frictionally engaging
relation with said transmission members.
The present lnvention thus provides the following
advantages which are derived from the copper-type sintered
alloy~
close contact between the facing members and the
transmission members may be obtained at an early stage of
use;
less abrasive powder is produced; and
less influence from friction heating is exerted
because of an excellent heat radiation property of the alloy.
The coefficient of friction of the facing members
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may therefore be stabilized, thus providing continuously
stable transmission operations.
It is a main object of the present invention to
provide an economically constructed friction-type torque
limiter.
Other objects and further advantages of the
present invention will be apparent from the following
description.
The invention will now be more particularly
described with reference to en~odiments thereof shown, by
way of example, in the accompanying drawings, in which:
Fig. 1 is a longitudinal section view of a first
embodiment of a friction-type torque limiter in accordance
with the present invention;
Fig. 2 is a longitudinal section view of a second
embodiment of the present invention; and
Fig. 3 is a view taken from the line III-III in
Fig. 2.
The description hereinbelow discusses in detail
the preferred embodiments of the present invention.
Fig. 1 illustrates a friction-type torque limiter
in accordance with the present invention. It will be
ob~erved that the limiter is disposed between a universal
joint 1 adapted to be interlockingly connected to a power
takeoff shaft (not shown) of an agricultural tractor (not
shown), and an input shaft 2 of an attached working machine,
such as a rotary cultivator, adapted to be connected to
and supported by the tractor.
In this friction-type torque limiter, a first
driving-side frictional transmission men~ber, hereinafter
referred to as a first plate 3, is formed in a disk shape
integrally with the universal joint 1. The plate 3 is
in contact with one side of a driven-side, disk-shaped
frictional transmission member, hereinafter referred to
as a driven plate 4, through a first facing member 5. It
will be observed that the plate 4 is connected to the
shaft 2 by means of a splined connection therebetween. A
second driving-side frictional transmission member, here-
inafter referred to as a second plate 7, is disk-shaped
and is in contact with the other side of the driven plate 4
through a second facing member 8, thc second plate 7 being
perforated and supported by a plurality of bolts 6 passing
through the perforations and through like perforations in
the first plate 3.
Springs 9 are disposed between the first plate 3
and washers 11 supported by nuts 10 which are threadedly
connected to the bolts 6.
The facing members 5 and 8 may therefore be
elastically held between the first plate 3 and the driven
plate 4, and between the driven plate 4 and the second
plate 7, respectively, by pulling or drawing the second
plate 7 toward the first plate 3 with the bolts 6 and nuts
10 .
With such an arrangement, power transmission is
provided by friction, and when an overload exceeding a
predetermined value is applied to the attached working
machine, power transmission is stopped by relative rotary
sliding of the plates 3, 4 and 7, thus preventing damage
to the attached working machine or exerting an excessive
strain upon the tractor.
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Those faces ofthe plates 3,4 and 7 which are
opposite the facing members 5 and 8, are being carburized,
and the facing members 5 and 8 are provided at both sides
of each of annular-shaped members 5a and 8a disposed at
the inner portion thereof, with linings 5b and 8b made of
a sintered alloy of which the main component is copper.
Figs. 2 and 3 illustrate a second embodiment of
the present invention in which the friction-type torque
limiter shown in Fig. l is modified to the form of a
multiple-plate type.
Three driven plates 12 are splined to the input
shaft 2. Two driving plates 13 are disposed between the
first plate 3 and the second plate 7, with the bolts 6
passing through suitable perforations in the driving plates
13. Six facing members 14 are interspersed between the
plates 3, 12, 13 and 7 as shown in Fig. 2.
Similar to the first embodiment, linings 14_
are made of a sintered alloy of which the main component
is copper and are applied to both sides of each of annular-
shaped members 14a at the inner portions of the facingmembers 14.
In this multiple-plate, friction-type torque
limiter, the bolts 6 perform a function of supporting or
mechanically linking the first plate 3, the second plate 7
and the driving plates 13 to prevent relative rotation
therebetween. The bolts 6 also function as means for
pulling or drawing the plates 7 and 13 toward the first
plate 3 in order to elastically hold the facing members 14
therebetween. Such an arrangement may therefore be con-
structed more economically and easily as compared with
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an arrangement in which means for supporting the drivingplates to prevent relative rotation therebetween, and
plate-pulling means are separately provided.
In accordance with the present invention, it
may also be possible to make all of the facing members of
a copper-type sintered alloy.
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