Transversely engaged centrifugal clutch

A centrifugal clutch which can transmit rotation of a primary shaft on the input side to a secondary shaft on the output side joining them by utilizing a centrifugal force which increases with the increase of the rotation of the primary shaft. A shoe divided into plural segments is arranged around a rotor which is fixed to the primary shaft; arcuate dents are made on the inside of the shoe and the outside of the rotor in such a way that each of the dents on both sides is placed face-to-face in pairs and pillars can be put between their couples. The pillars are made of an elastic material and around the shoe is a spring, so that the shoe always clamped together to the rotor with the pillars being put between them. A cylinder to which the secondary shaft is fixed encloses the shoe. Thus, when the primary shaft begins to rotate accompanying the rotor, each segment of the shoe gradually comes apart from the shaft by a centrifugal force, which results in pressing them against the inside of the cylinder so strongly as to cause the secondary shaft to rotate in association with the primary shaft.

BACKGROUND OF THE INVENTION 
This invention relates to a centrifugal clutch which can transmit rotation 
of a primary shaft on the input side to a secondary shaft on the output 
side by utilizing a centrifugal force which results from the rotation of 
the primary shaft. 
So far a centrifugal clutch has also been employed to transmit rotation 
from a shaft to another. However, in the conventional, common centrifugal 
clutch, a plurality of arms are swingably fixed to a primary shaft with 
pins, shoes are rotatably attached to each end of the arms, and a ring of 
the shoes is enclosed by a cylinder in such a way that the arms can stand 
upright so as to press the shoes against the inside of the cylinder to 
transmit rotation of the primary shaft to the secondary shaft by a 
centrifugal force resulting from the rotation of the primary shaft. 
Accordingly, such a centrifugal clutch needs lubricating from time to time 
to ensure it a good operating condition because most of the joints in the 
machine are made of metal and connected with pins. This structure has also 
obliged a user to waste a lot of time in maintenance. Besides, if a user 
neglects to accurately align both axes of the primary and the secondary 
shafts on a line, the shoes cannot be brought into even contact with the 
inside of the cylinder. 
Under these circumstances, a first object of this invention is to provide a 
centrifugal clutch which can be put into operation far more easily than a 
conventional one in which pins and arms are employed. 
A second object of this invention is to provide a centrifugal clutch which 
needs no lubrication and operates silently. A third object of this 
invention is to provide a centrifugal clutch which is able to absorb a 
torsional vibration that follows the transmission of a driving force. 
A fourth object of this invention is to provide a centrifugal clutch which 
permits a driving force to be transmitted effectively even if there is a 
little offset between the respective axes of the primary and the secondary 
shafts. 
A fifth object of this invention is to provide a centrifugal clutch having 
a strong coupling force which can well withstand transmitting a large 
torque.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring FIGS. 1 and 2 showing the first embodiments, a triangular rotor 
12 is fixed to an end of a primary shaft 11. A receiving member 13 is 
provided for both sides of each apex of the triangular rotor. Near both 
ends of each side of the triangle is an arcuate groove 15. Outside the 
rotor 12 is a shoe divided into plural segments 16 whose number is made 
correspondent with the number of sides 14 of the rotor. (Thus, in this 
example, the shoe is divided into three segments each of which is faced 
with each side of the triangle.) The divided shoe has a lining 17 outside 
and arcuate grooves 18 inside, each of which is arranged vis-a-vis the 
grooves 15 which are near both ends of each side 14 of the rotor. 
The numeral 19 designates a pillar (elongate elastomeric member) which is 
made of an elastic material. A pillar 19 is put in each space formed by 
the arcuate grooves 15 of the rotor 12 and the arcuate grooves 18 of the 
shoe 16; additionally, the axis of the pillars is kept standing parallel 
to the primary shaft 11. 
There is a step 20 on upper and lower sides of the shoe 16 whose edge draws 
an arc parallel to the periphery of the shoe. On the riser of each step is 
a groove 21 in which elastic means such as a piece of coiled spring is 
put, by which the divided shoe is always pulled together inwardly toward 
the primary shaft 11. Hence, the shoe 16 is pressed against the rotor 12 
by a contracting force of the coiled spring with the pillars being put 
between them. 
A secondary shaft is designated by the numeral 23. This shaft is united to 
a cylinder 24 which encloses a ring of the divided shoe. 
The centrifugal clutch of this invention has such structure that when the 
primary shaft 11 begins rotating in the direction of the arrow, as shown 
in FIG. 1, by means of a motor for instance, the rotor 12, the pillars 19 
and a ring of the divided shoe 16 also begin rotating as one body. As the 
rotor 12 rotates faster, the segments of the shoe are increasingly pulled 
outwardly by a centrifugal force against the attraction by means of the 
coiled spring. In this way, the radius of the circular shoe grows as the 
outside lining 17 comes into contact with the inside of the cylinder 24 
which still remains unmoved at the moment. 
For some while, the shoe 16 continues to rotate inside the cylinder 24 
rubbing it with the lining. As the rotational speed becomes much faster, a 
centrifugal force increases with it, which results in pressing the lining 
on the shoe against the inside of the cylinder so strongly as to turn it 
in combination with the rotor 12 overcoming a friction force exerted on 
the output side 23. At this moment, the pillars move as the arrow A in 
FIG. 1 shows. 
Another example of this invention will now be described, which is 
illustrated in FIGS. 3 and 4. In this example, the description about the 
same part or parts having the same function as those in the above first 
example will be omitted by numbering them with correspondent reference 
numerals. 
The second example of a centrifugal clutch of this invention has two 
grooves 32 on both sides of a rectangular rotor 31 putting a primary shaft 
on its center. Between the two grooves 32 on each side of the rotor is a 
flat portion 33; the shape of the grooves 32 is arcuate at 34 at the end 
of the flat portion and then turns into a slope at 35 gradually rising 
toward the outside. A pair of shoes 36 are arranged outside the rotor 31; 
they also have arcuate grooves 37 on their inside surfaces facing the 
rotor. Any pair of opposing grooves 32, 37 exactly face each other so as 
to form an oval space. 
There is also a flat portion between the grooves 37 which is placed 
vis-a-vis the flat portion 33 of the rotor. The shoes 36 are truncated 
obliquely at 39 outside the grooves 37. 
The numeral 40 denotes pillar made of an elastic material which are 
inserted between the arcuate portions 34 of the grooves 32 of the rotor 31 
and the groove 37 of the shoes 36. Each shoe 36 has a coupling means 41 
having a hole 42 at each truncated end. The ends of coiled springs 43 are 
joined to respective holes 42 which are bored through the coupling means 
41. For this a pair of the coiled springs pull the pair of shoes 36 
together by the two ends. Outside the periphery of the shoes is a lining 
17. A primary shaft which is on the input side is designated by the 
numeral 11; the rotor 31 is fixed to the primary shaft. A secondary shaft 
which is on the output side is designated by the numeral 23. This is 
united to a cylinder 24 which encloses the pair of shoes. 
In the second example of this invention, the shoes 36 are also pulled 
outwardly as a centrifugal force grows larger and get to have an 
inclination to the rotor 31. As a consequence, the pillars 40 come between 
the grooves 32 of the rotor 31 and the grooves 37 of the shoes 36. Thus, 
the pillars are able to unite the rotor 31 and shoes 36 so firmly as to 
transmit the rotational force from the primary shaft to the secondary 
shaft. 
That is, as the rotation of the primary shaft becomes faster, a centrifugal 
force grows larger, which results in more strongly pressing the lining of 
the shoes against the inside of the cylinder 24 to such an extent that the 
rotor 31 and the cylinder can rotate as one body overcoming a load exerted 
by a friction force between the shoes and the cylinder. 
As seen from the above, in the centrifugal clutch of this invention, the 
rotor and the shoes always hold the elastic pillars tightly because they 
are clamped by coiled springs; besides, when a centrifugal force grows 
larger, the pillars start moving toward outside wedging themselves into 
the space formed by the sloped and the shoes; so that there arises a wedge 
effect (servo effect) and this increasingly consolidates the coupling of 
the clutch. 
For this mechanism, the capacity for transmitting a rotational force can be 
widely varied with a change of inclination of the slope of the surface of 
the rotor. A friction between the lining of the shoes and the cylinder 
gradually increases as the pillars more deeply interene between the sloped 
surface and the shoes. As a result, the contact of the shoes and the 
cylinder gives rise to less shock and keeps silent movement because the 
pillars are made of an elastic material. More than that, the pillars have 
an effect of absorbing a torsional vibration. Outside the above, the 
centrifugal clutch of this invention has an advantage over others since it 
can be put into operation even though there is a little offset between the 
primary and the secondary shafts.