Thin autotensioner
AssigneeUnitta Company
InventorsKazumasa Ayukawa, Hiromi Matsuura
Life of this patent
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Abstract
An autotensioner comprises a torsion coil spring interposed between a base and a rocking arm, and a tubular bushing provided between an inside surface of the base and an outside surface of the rocking arm. The torsion coil spring pushes and biases the rocking arm toward the bushing, and brings the pushing direction substantially in coincidence with the axial load direction of the force, acting on a stepped bolt supporting the rocking arm, from a belt. When the belt tension becomes high, the arm axial center displaces slightly from the base axial center, an extremely large first damping force acts on the rocking arm. When the belt tension becomes low, the smaller second damping force acts on the rocking arm.
Claims20
An autotensioner comprising:
- a base that has a bottomed tubular shape;
- a rocking arm that has a tubular part rotatably supported at the inside of said base;
- a pulley that is attached to one end of said rocking arm, and abuts against a belt;
- and
- a torsion coil spring that is housed in said base, and biases rotation of said rocking arm in a direction tensing said belt with respect to said base;
- said torsion coil spring being attached eccentrically to the axial center of said base, and said rocking arm being supported to be able to be displaced relative to said base, whereby the first damping force acting on said rocking arm when said belt is tensed becomes relatively larger than the second damping force acting on said rocking arm when said belt is slack.
A thin autotensioner comprising:
- a base that has a cup having an inside diameter;
- a rocking arm that is rotatably supported by said base;
- and
- a torsion coil spring that biases said arm in a predetermined direction, said torsion coil spring having an outside diameter larger than said inside diameter, said torsion coil spring being twisted in a direction in which said outside diameter is compressed so as to be housed inside said cup.
A method of assembly of a thin tensioner comprising:
- a first step of twisting a torsion spring coil having an outside diameter larger than an inside diameter of a cup to make the outside diameter smaller than said inside diameter;
- and
- a second step of interposing said twisted torsion coil spring between said cup and rocking arm.
A method of assembly of a thin tensioner comprising:
- a first step of engaging one end of a torsion coil spring having an outside diameter larger than an inside diameter of a cup, with said cup;
- a second step of engaging another end of said torsion coil spring with a rocking arm;
- a third step of rotating said rocking arm to twist said torsion coil spring and make the outside diameter smaller than said inside diameter;
- a fourth step of bringing said rocking arm into proximity with said cup to compress said torsion coil spring and house it in said cup;
- and
- a fifth step of rotatably fastening said rocking arm to said cup.
An autotensioner comprising:
- a base that has a first tubular part having a bottomed tubular shape;
- a rocking arm that has a second tubular part, which is attached rotatably to an open side of said base and is separated by a certain distance from said first tubular part in the radial direction;
- and
- a friction member that is provided between said first tubular part and said second tubular part, and brakes said rocking arm;
- said friction member being partially exposed, and being formed from a material mainly comprised of a polyphenylene sulfide resin.
A friction member in an autotensioner rotatably attaching a rocking arm to a base, characterized by being provided between said rocking arm and said base, and being formed by a material mainly comprised of a polyphenylene sulfide resin.
Dependencies are inferred from the claim text.