Autotensioner

Details Autotensioner Autotensioner

1994-04-20

1995-03-21

Schoeppel, Roger J.

Endless belt power transmission systems or components

Resilient connection between pulley or guide-roll rim and mount

474112, 474135, F16H 712

Patent

active

053991249

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to an autotensioner used to keep constant the tension of a timing belt for driving the cam shaft of an automobile engine or the like.


BACKGROUND TECHNOLOGY

An autotensioner used to keep constant the tension of the belt for driving the camshaft of an automobile engine is proposed in Unexamined Japanese Utility Model Publication 1-171952.
In this type of autotensioner, as shown in FIG. 6, a support shaft 32 is fixed by tightening a bolt 31 into a base 30 of the engine block. A pulley support 33 is eccentrically supported on the support shaft 32. A pulley 35 is rotatably mounted on the pulley support 33 through a rolling contact bearing 34. The pulley support 33 is provided with a cylindrical portion 36 concentrical with the support shaft 32. A bracket 37 press-fitted on the cylindrical portion 36 has an arm 38 to which a tension adjusting spring 39 is coupled in order to rock the pulley support 33 in a direction in which the pulley 35 stretches the belt.
Further, between the cylindrical portion 36 and the support shaft 32 is provided a damper mechanism 40 in the form of viscous fluid so that it will impart a rocking resistance to the pulley support 33 and prevent a high-frequency fluctuation.
In this conventional autotensioner, as shown in FIG. 7, the pulley support 33 including the cylindrical portion 36 is in the form of an eccentric cylinder having two different central axes a and b. Thus, it requires a lot of manufacturing time and cost.
A technical object of the present invention is to obviate the abovesaid problems and to simplify the manufacturing process of the pulley support of the autotensioner and to reduce the cost.


DISCLOSURE OF THE INVENTION

In order to attain the above object, according to the present invention, there is provided an autotensioner comprising a support shaft, a pulley support eccentrically supported by the support shaft, a pulley rotatably supported by the pulley support, a tension imparting means for urging the pulley support in a direction in which the pulley stretches a belt, the pulley support having a cylindrical portion which is concentrical with the support shaft, and damper means disposed between the cylindrical portion and the support shaft for imparting a rocking resistance to the pulley support, characterized in that the pulley support comprises an eccentric ring and a rocking shaft, the eccentric ring has the inner periphery thereof eccentric with respect to the outer periphery thereof, and the rocking shaft is provided at one end thereof with the cylindrical portion and is integrally provided at the other end thereof with a cylindrical small-diameter portion which is inserted in the eccentric ring so as not to rotate relative to the eccentric ring.
As described above, the pulley shaft is divided into two separate parts, i.e. the eccentric ring and the rocking shaft. By assembling these two simple parts, the pulley support having two central axes can be manufactured. Thus, each part can be manufactured easily and thus the manufacturing cost can be reduced.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view showing one embodiment of the autotensioner according to the present invention;
FIG. 2 is a vertical sectional side view of the same;
FIG. 3 is a sectional side view taken along line III--III of FIG. 2;
FIG. 4 is an exploded perspective view showing the pulley support of the same;
FIG. 5 is a vertical sectional side view showing another embodiment of the autotensioner according to the present invention;
FIG. 6 is a vertical sectional side view showing a conventional autotensioner; and
FIG. 7 is a perspective view showing the pulley support of the same.


BEST MODE FOR EMBODYING THE INVENTION

Now we shall explain the embodiments with reference to FIGS. 1-5.
FIGS. 1-4 show an autotensioner used to adjust the tension of a cam shaft driving belt of an automobile engine. As shown, to one side of an engine block 1, a cylindrical support shaft 3 is fixed by tightening a bolt 2.
A support shaft 3 has a large-diameter

REFERENCES:
patent: 4832665 (1989-05-01), Kadota et al.
patent: 4904230 (1990-02-01), Kawashima et al.
patent: 4923435 (1990-05-01), Kadota et al.
patent: 5328415 (1994-07-01), Furutani et al.

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