Nhk Spring Co., Ltd.

Tanehira Amano

Takao Kobayashi

Takahiro Ito

Ikuomi Takahashi

Shigemasa Takahashi

Kazuo Ishii

Kenjiro Kawanabe

A tensioner having a simplified structure, using engaging teeth having increased strength and reduced backlash, constructed from a reduced number of parts, reduced in cost, and having increased design freedom. A tensioner comprises: a tubular member () having engaging teeth () formed thereon; one or more engaging elements () having formed thereon engaging teeth () engaging with the engaging teeth (); and a shaft member () provided inside the tubular member () and having an engaging-element receiving section () or an engaging-element supporting section which receives the engaging elements () of the tubular member (). Either the tubular member () or the shaft member () functions as an advancing member which is moved by urging force in an advancing and retracting manner. The tensioner is provided with a ratchet mechanism which, when the engaging elements () move in a diameter reducing direction and move over the engaging teeth of the tubular member (), allows the advancing member to advance forward, and when the engaging elements () move in a diameter expanding direction and engage with the engaging teeth of the tubular member (), prevents the advancing member to retract.

Tensioner

A tensioner has a cylindrical member having multiple locking teeth, one or multiple locking pieces having locking teeth to be engaged with the locking teeth, and a locking piece receiving part to receive the aforementioned locking pieces. A shaft member is disposed inside the cylindrical member, and either the cylindrical member or the shaft member constitutes a thrust member that can be driven forward and backward by a biasing force. A ratchet mechanism allows the thrust member to move forward by the locking pieces riding over the locking teeth of the cylindrical member as they move in a reduced-diameter direction and constrains retraction of the thrust member by the locking pieces engaging with the locking teeth of the cylindrical member as they move in an increased-diameter direction. The locking teeth are all thread-like teeth having a lead angle.

A tensioner, in which a bearing of the drive shaft is not necessary and the initial load of the torsion spring is maintained when the tensioner is disassembled, two shaft members that compose a set and that are engaged by screw portions, and a spring that is inserted in the driving unit by fastening onto the shaft members the hooking portions that are located at each end of the spring. The spring is inserted in the set of the shaft members under an appropriate windup condition. One shaft member moves forward from the loaded strength by the spring. The tensioner also includes, beside the driving unit, a case into which the driving unit is inserted, and a system that prevents the driving unit from coming off the case.

Driving unit and tensioner

A tensioner comprises shaft members that mate with each other by way of thread portions. A first shaft member is rotatable with respect to a casing and is restrained from moving in its axial direction. A second shaft member, which is restrained from rotating with respect to the casing, is movable in its axial direction. A torsion spring applies torque in a first direction to the first shaft member. A torque switching member, which can switch frictional torque in association with the rotation of the first shaft member, is provided between the first shaft member and the casing.

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Nagano, Japan

Tanehira Amano