Abstract: An electrically driven linear actuator with a smooth motion of a ball screw provides an even load distribution as well as a stable motion of the balls and has an electric motor (5) mounted on a housing (4). A nut (8 or 16), adapted to mate with the screw shaft (7), has a pair of supporting portions (14) at an axially central position on the outer circumferential surface of the nut (8 or 16) to engage one end of a link (2). The nut (8, 16) is formed with a screw groove (8a). Oval bridge windows (10) are formed in the nut (8 or 16) through a wall with a portion of the screw groove (8a) cut out over a distance of at least two pitches of the screw grooves (8a). A bridge member (11), forming the circulating member, is fitted in each of the bridge windows (10).

Abstract: A ball screw shaft supporting structure of a ball screw rotationally supported by a housing via supporting bearings has a screw shaft formed, on its outer circumference, with a fitting portion and a positioning shoulder. An inner ring of the supporting bearing is press fit onto the fitting portion via a predetermined interference. A steel spacer ring is fit onto the fitting portion from the outer side of the supporting bearing with the inner side of the inner ring abutted against the shoulder. A caulking portion is formed on the end of the fitting portion by plastically deforming the end of the fitting portion radially outward. The inner ring is axially immovably secured on the screw shaft by the caulking portion via, the spacer ring.

Abstract: A ball screw shaft supporting structure of a ball screw rotationally supported by a housing via supporting bearings has a screw shaft formed, on its outer circumference, with a fitting portion and a positioning shoulder. An inner ring of the supporting bearing is press fit onto the fitting portion via a predetermined interference. A steel spacer ring is fit onto the fitting portion from the outer side of the supporting bearing with the inner side of the inner ring abutted against the shoulder. A caulking portion is formed on the end of the fitting portion by plastically deforming the end of the fitting portion radially outward. The inner ring is axially immovably secured on the screw shaft by the caulking portion via, the spacer ring.

Abstract: An electrically driven linear actuator with a smooth motion of the ball screw provides an even load distribution as well as a stable motion of the balls and has an electric motor (5) mounted on a housing (4). A screw shaft (7) is coaxially connected to a motor shaft (5a) of the electric motor (5). The screw shaft (7) has a screw groove (7a) formed on its outer circumferential surface. A nut (8 or 16), adapted to mate with the screw shaft (7), has a pair of supporting portions (14) at an axially central position on the outer circumferential surface of the nut (8 or 16) to engage one end of a link (2). The nut (8, 16) is formed with a screw groove (8a), corresponding to the shaft screw groove (7a), on its inner circumferential surface. A number of balls (9) are contained between the screw grooves (7a and 8a). Ball circulating members (11), each being formed with an endless ball circulating passage, are positioned between the screw grooves (7a and 8a).

Abstract: A belt type infinite variable-speed drive using a ball-screw mechanism is compact and noise-free. A nut of the ball-screw mechanism is fixed to a casing and a threaded shaft is rotatably coupled to a movable pulley member through a ball bearing so that ball circulating portions on the nut will not rotate while the movable pulley member is movable axially. Also, the ball circulating portions, which are low in load bearing capacity, are oriented in such a direction that a load hardly acts on the ball-screw mechanism. This makes it possible to compactly and rationally design a belt type infinite variable-speed drive and to suppress noise due to vibration of balls in the ball circulating portions.

Abstract: A ball screw mechanism comprises a screw shaft, a nut and balls. The nut has a cylindrical portion in the axial middle on the outer peripheral surface thereof that becomes a fitting surface for fitting in a sleeve, and small diameter step portions in the opposite axial sides on the outer peripheral surface thereof that become non-fitting surfaces not fitting in the sleeve. A portion of a wheel steering shaft is provided with the screw shaft, and a plurality of balls are disposed in a rolling way defined between a thread groove formed in the outer periphery of the screw shaft and a thread groove formed in the inner periphery of the nut.

Abstract: A ball screw mechanism comprises a screw shaft, a nut and balls. The nut has a cylindrical portion in the axial middle on the outer peripheral surface thereof that becomes a fitting surface for fitting in a sleeve, and small diameter step portions in the opposite axial sides on the outer peripheral surface thereof that become non-fitting surfaces not fitting in the sleeve. A portion of a wheel steering shaft is provided with the screw shaft, and a plurality of balls are disposed in a rolling way defined between a thread groove formed in the outer periphery of the screw shaft and a thread groove formed in the inner periphery of the nut.

Abstract: A belt type infinite variable-speed drive using a ball screw is proposed which is compact and noise-free. The nut of the ball screw mechanism is fixed to a casing and the threaded shaft is rotatably coupled to a movable pulley member through a ball bearing so that ball circulating portions on the nut will not rotate while the movable pulley member is movable axially. Also, the ball circulating portions, which are low in the load bearing capacity, are oriented in such a direction that load hardly acts on the ball screw mechanism. This makes it possible to compactly and rationally design a belt type infinite variable-speed drive and to suppress noise due to vibration of the balls in the ball circulating portions.

Abstract: An electrically powered steering device comprises a ball screw mechanism for transmitting a steering force from a steering wheel to steerable vehicle wheels. The ball screw mechanism includes a rotary nut 11 having a nut body 11a in which a circulating passage 15 is formed so as to extend axially thereof, and end caps 14a and 14b secured respectively to opposite ends of the nut body 11a. Each of the end caps 14a and 14b has defined therein respective guideways 17a and 17b for balls 13 that communicate opposite ends of the circulating tunnel 14 with a ball rolling passage 12. The end caps 14a and 14b and the nut body 11a are made of a sintered alloy. The nut body 11a has an outer periphery of one end thereof that is axially progressively reduced in diameter to define a tapered surface.

Abstract: A ball screw mechanism (20) compact in size, employing a minimized number of component parts and having a high load capacity includes a rotary nut (22) having an internally threaded helical groove (26) and a mounting hole (30) both defined therein, and a simplified bridge member (24) mounted in the rotary nut (22). The bridge member (24) has a plurality of connecting grooves (28) defined on an inner surface thereof each operable to communicate neighboring convolutions of the internally threaded helical groove (26). The bridge member (24) has its opposite side edges formed with respective guide walls (36) protruding in a direction radially outwardly of the rotary nut (22) that are crimped to allow the bridge member (24) to be fixedly retained within the mounting hole (30).

Abstract: A ball screw mechanism (20) compact in size, employing a minimized number of component parts and having a high load capacity includes a rotary nut (22) having an internally threaded helical groove (26) and a mounting hole (30) both defined therein, and a simplified bridge member (24) mounted in the rotary nut (22). The bridge member (24) has a plurality of connecting grooves (28) defined on an inner surface thereof each operable to communicate neighboring convolutions of the internally threaded helical groove (26). The bridge member (24) has its opposite side edges formed with respective guide walls (36) protruding in a direction radially outwardly of the rotary nut (22) that are crimped to allow the bridge member (24) to be fixedly retained within the mounting hole (30).

Abstract: A homokinetic joint which can be manufactured at low cost. Its outer ring and inner ring has a spherical inner surface and a spherical outer surface both formed with a plurality of track grooves in which are received torque transfer balls retained by a cage. The spherical inner surface and the track grooves of the outer ring are finished by plastic working, so that no additional finishing work is necessary. Thus, the outer ring can be manufactured at low cost.

Abstract: The object of this invention is to reduce the cost of an autotensioner for keeping constant the tension of a belt.A pulley 13 is mounted on the pulley support 6 eccentrically supported by the support shaft 3. A tension imparting member is provided which rocks the pulley support in a direction in which the pulley stretches a belt. The pulley support 6 has a cylindrical portion 8a which is concentrical with the support shaft. Damper 20 is provided between the cylindrical portion 8a and the support shaft 3 to impart a rocking resistance to the pulley support. The pulley support 6 has an eccentric ring 7 and a rocking shaft 8. The rocking shaft has at one end the cylindrical portion 8a and at the other end a cylindrical small-diameter portion 8b which is inserted in the eccentric ring. The pulley support 6 is comprised of two members which are simple in shape and easy to manufacture.

Abstract: A method and apparatus for compensating for axial deformation of screw shafts due to heat treatment, wherein in the process of hardening of a screw shaft, the screw shaft is twisted to produce permanent twist deformation by an amount corresponding to the pitch error of the screw shaft caused by hardening, so as to correct the pitch error.

Abstract: A constant velocity joint adapted to transmit rotary motion from a driving shaft to a driven shaft at the same angular velocity comprises, for example, an outer joint member 10 associated with the driving shaft 1, an inner joint member 20 associated with the driven shaft 2 and a plurality of ball elements 3 interposed between these joint members with a cage member therebetween. The inner member 20 has an outer spherical surface 22, and a plurality of circumferentially distributed ball grooves 21 each having its groove bottom drawing a curved or arcuate line whose curvature center is located at a point B axially apart from the curvature center 0 of the outer spherical surface as viewed in axial section. The inner member is formed through two steps of forming works consisting of a first step for providing the ball grooves and the outer peripheral surface finished to the respective shapes as desired with respect to substantially a half l.sub.