Endless belt power transmission systems or components – Means for adjusting belt tension or for shifting belt,... – Guide roll mounted for movement of its axis along arcuate...
Reexamination Certificate
1998-09-11
2001-03-06
Bucci, David A. (Department: 3682)
Endless belt power transmission systems or components
Means for adjusting belt tension or for shifting belt,...
Guide roll mounted for movement of its axis along arcuate...
C474S109000
Reexamination Certificate
active
06196941
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an auto tensioner for automatically holding a belt tension at an appropriate strength in a belt driving mechanism, and more particularly to an auto tensioner for suppressing a change of the position of a tension pulley due to a vibration or impact received from a belt as well as allowing a pressing work of the tension pulley so as to keep the belt tension constant.
2. Description of the Related Art
Some type of the auto tensioner comprises a tension pulley on which a belt is to be wound, an arm for supporting the tension pulley such that it is capable of rotating, a fixing shaft for supporting this arm swingably, a friction plate for supplying a swing resistance to this arm, and a twisting coil spring for urging the arm in the direction of a rotation thereof as well as pressing the arm against the friction plate. The twisting coil spring and the friction plate exert different functions between when the belt tension changes mildly and when a violent vibration or impact is applied thereto.
First, if the belt tension changes mildly, the arm is inclined by the twisting restoration force of the twisting coil spring, so as to keep the belt tension constant. If a violent vibration or impact is applied from the belt to the tension pulley, that vibration or impact is transmitted to the arm, however because the arm is pressed against a friction plate by the expansive restoration force of the twisting coil spring, a large friction resistance is generated between the arm and the friction plate. As a result, the vibration or impact is absorbed and damped quickly, thereby preventing the swing of the arm supporting the tension pulley so as to keep the belt tension constant.
In the above auto tensioner, the friction plate is worn with a passage of time. Then, wearing particles are generated by this wearing. Some part of the wearing particles remain in a gap between the friction plate and a mating member which the friction plate contacts. If the remainder of the wearing particles increases, the friction resistance between the friction plate and the arm changes. Consequently, the damping function for the vibration or impact may drop. As a result, there is a possibility that a function of the auto tensioner for protecting the arm supporting the tension pulley from the aforementioned vibration or impact so as to keep the belt tension constant may be lost.
SUMMARY OF THE INVENTION
Accordingly, a primary object of the present invention is to provide an auto tensioner capable of suppressing changes of friction resistance of a friction plate accompanied by a generation of wearing particles.
Another object of the present invention is to provide an auto tensioner capable of suppressing changes of friction resistance of a friction plate accompanied by a generation of wearing particles and protecting an arm supporting a tension pulley from a vibration or impact so as to keep the belt tension constant.
The other objects, features and advantage of the present invention will be evident from a following description.
To achieve the above object, the present invention provides an auto tensioner comprising a fixing shaft having an arm supporting portion, an arm supported around the arm supporting portion of the fixing shaft so as to be swingable, a tension pulley supported rotatably at a free end of the arm, an opposing member disposed so as to oppose the arm and blocked from rotating relative to the arm supporting portion, a friction plate disposed between the arm and the opposing member so as to supply the arm with a swing resistance due to a friction resistance generated by a contact thereof with the opposing member, and a pressing member for pressing the arm against the friction plate so as to make the friction plate in contact with the opposing member, wherein at least one of said arm and said opposing member has a wearing particles collecting portion for collecting wearing particles generated in a portion contacting the friction plate because of a friction with the friction plate.
Preferably, the wearing particles collecting portion is composed of a concave portion formed in a plane in which at least one of the arm supporting portion and the opposing member is in contact with the friction plate.
Preferably, the opposing member is a friction pressing plate for pressing the friction plate against the arm.
Preferably, the pressing member is a twisting coil spring for pressing the arm against the friction plate and urging the arm in a direction of a rotation thereof.
Preferably, a plurality of the wearing particles collecting portions are spaced along the circumference.
Preferably, a wearing particles discharging portion for discharging wearing particles collected in the wearing particles collecting portion to outside is further contained.
Preferably, a wearing particles discharging portion for discharging wearing particles collected in the wearing particles collecting portion to outside is further contained, and the wearing particles discharging portion is an opening formed by extending an inner end in the diameter direction of the concave portion inward in the diameter direction beyond an inner end in the diameter direction of the friction plate.
Preferably, a wearing particles discharging portion for discharging wearing particles collected in the wearing particles collecting portion to outside is further contained, and the wearing particles discharging portion is an opening formed by extending an outer end in the diameter direction of the concave portion outward in the diameter direction beyond an outer end in the diameter direction of the friction plate.
Preferably, the wearing particles collecting portion is composed of a belt-like groove formed in the diameter direction.
Preferably, the wearing particles collecting portion is composed of a belt-like groove inclined relative to the diameter direction.
Preferably, the wearing particles collecting portion is composed of a V-shaped groove.
Preferably, a bushing interposed between an outer surface of the arm supporting portion of the fixing shaft and an inner surface of the arm mounted on the arm supporting portion is further contained, and with respect to a center in the axial direction of the arm supporting portion of the fixing shaft, a center in the axial direction of a pulley supporting portion which is a free end of the arm is offset and the tension pulley is rotatably supported by the pulley supporting portion of the arm, the bushing has a thickness which increases gradually from a proximal end of the arm supporting portion to a distal end thereof.
In the auto tensioner of the present invention, because the wearing particles generated by wearing with a passage of time are collected in the wearing particles collecting portion and the wearing particles are discharged from a gap between the friction plate and a mating plate which the friction plate contacts so that they are unlikely to remain therein, the friction resistance of the friction plate is hard to change.
If the wearing particles collecting portions are provided at plural positions spaced along the circumference, the wearing particles generated from the friction plate can be collected there over a wide range. As a result, as compared to a case of a wearing particles collecting portion provided, the discharge amount of the wearing particles is sufficient and the wearing particles from a wide range of the friction plate can be discharged.
If the wearing particles discharging portion opening to outside is provided at the wearing particles collecting portion, the wearing particles collected therein is successively discharged from the wearing particles collecting portion to outside. As a result, the wearing particles in the wearing particles collecting portion is prevented from returning to a gap between the friction plate and a mating plate which the friction plate contacts.
If the wearing particles collecting portion is a belt-like groove extending in the diameter direction, the wearing particles collecting portion is
Ohta Hideyuki
Yamakawa Tadasu
Bucci David A.
Charles Marcus
Jacobson Price Holman & Stern PLLC
Koyo Seiko Co. Ltd.
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