The present invention relates to a pulley structure (1) equipped with an outer rotating body (2), an inner rotating body (3), and a coil spring (4) provided between the outer rotating body (2) and the inner rotating body (3). The coil spring (4) is configured so as to undergo torsional deformation in a diameter-expanding or a diameter-contracting direction, thereby engaging the outer rotating body (2) and the inner rotating body (3) and transmitting torque, and to undergo torsional deformation in the direction opposite the direction in which torque is transmitted, thereby entering a disengaged state in which the coil spring slides with the outer rotating body (2) or the inner rotating body (3), thus interrupting the transmission of torque. The number of windings of the coil spring (4) is in a range between [M-0.125] and M (both inclusive), where M is a natural number.

The disclosure provides a position changing device capable of reducing the size of the entire device in a plane. A position changing device (30) includes four pulley mechanisms (40). In the pulley mechanism (40), a toothed belt (45) is wound around a driving pulley (41) and a driven pulley (43), and is held between the driving pulley (41) and an idler roller (42) by the idler roller (42) and held between the driven pulley (43) and an idler roller (44) by the idler roller (44), and when the driving pulley (41) is driven by a driving mechanism (46), the position of a movable base plate (31) is changed.

A drive force transmission mechanism includes a drive pulley, a driven pulley and an endless belt wound around the drive pulley and the driven pulley. The drive pulley and the driven pulley rotate around axes parallel to each other. At least one of the drive pulley and the driven pulley has a protruding part protruding outwardly in a radial direction around an outer circumferential face along an entire circumference. At least one axial end portion among both axial end portions of the protruding part in an axial direction of the rotational axis has a radius of curvature smaller than a radius of curvature of an axial center portion of the protruding part in the axial direction.

A screw nut on which a pulley is mounted is capable of promoting reductions in the size and weight thereof. The screw nut includes: an outer ring; and a nut rotatably assembled to the outer ring via a first rolling element. The nut includes: a nut body having a screw groove in an inner surface thereof; and a recirculation component provided at an end portion of the nut body in an axial direction, the recirculation component having a turn-around path for recirculating a second rolling element rolling along a screw groove. A pulley to be mounted on the nut is fitted on an outer surface of the nut body, and is brought into contact with an end surface of the nut in the axial direction. The pulley is mounted on the end surface of the nut with a fastening member.

The invention relates to a belt drive (24) with (a) a first pulley wheel (12) in the form of a drive sprocket with drive teeth (16), (b) a second pulley wheel in the form of an output sprocket (18) and (c) a toothed belt (22) that (i) connects the drive sprocket (12) and the output sprocket (18) for transmitting a force and (ii) has a belt back (38) and (iii) a plurality of teeth (34), wherein a tooth base (36) is situated between two adjacent teeth. According to the invention, (d) the toothed belt (22) comprises a plurality of recesses (26), each of which is configured in a tooth base (36), and (e) at least one pulley wheel features guide projections (28) for engaging in the recesses (26).

A belt drive device includes a first pulley, a second pulley, a first bulging portion, a belt, and a pressing portion. The first bulging portion is formed along an outer periphery of the second pulley to bulge outward in a radial direction of the second pulley at a center of the second pulley in an axial direction of the second pulley. The belt is stretched between the first pulley and the first bulging portion. The pressing portion presses an outer peripheral surface of the belt at a center of the belt in a width direction of the belt.

A screw nut on which a pulley is mounted is provided, the screw nut capable of promoting reductions in the size and weight thereof. A screw nut includes: an outer ring; and a nut rotatably assembled to the outer ring via a first rolling element. The nut includes: a nut body having a screw groove in an inner surface thereof; and a recirculation component provided at an end portion of the nut body in an axial direction, the recirculation component having a turn-around path for recirculating a second rolling element rolling along a screw groove. A pulley to be mounted on the nut is fitted on an outer surface of the nut body, and is brought into contact with an end surface of the nut in the axial direction. The pulley is mounted on the end surface of the nut with a fastening member.

A belt pulley decoupler for transmitting drive torque from the belt of an auxiliary unit belt drive to the shaft of one of the auxiliary units is provided, including: a belt pulley, a hub to be mounted on the shaft, a first sleeve, which is rotationally fixed in the pulley, a second sleeve, which is rotatable in the pulley, and a series circuit of a decoupler spring and a disposed in the drive torque flow between the belt pulley and the hub. The wrap-around band ends, which couple the two sleeves to one another non-rotatably while transmitting the drive torque, extend the wrap-around band radially. One of the two sleeves has a circumferentially extending slot and the wrap-around band end coupled to this sleeve is configured as a leg, which interlockingly engages in the slot non-rotatably in a direction of rotation of the drive torque.

A drive force transmission mechanism includes a drive pulley, a driven pulley and an endless belt wound around the drive pulley and the driven pulley. The drive pulley and the driven pulley rotate around axes parallel to each other. At least one of the drive pulley and the driven pulley has a protruding part protruding outwardly in a radial direction around an outer circumferential face along an entire circumference. At least one axial end portion among both axial end portions of the protruding part in an axial direction of the rotational axis has a radius of curvature smaller than a radius of curvature of an axial center portion of the protruding part in the axial direction.

A filtering pulley having a hub adapted to be fixed to a rotating shaft, a pulley ring mounted coaxial and rotationally free on the hub, and a plurality of elastic assemblies arranged circumferentially with respect to the hub and the pulley ring and each interposed between a pair of first elements integral with the hub and between a pair of second elements integral with the pulley ring is disclosed. Each elastic element forms with the first elements and with the second elements respective angular clearances, and the pulley ring and the hub have a free angle of relative rotation equal to the sum of the above-mentioned angular clearances.