Abstract: An electric power steering system includes: a steered shaft, a housing containing the steered shaft therein in a movable manner; a ball screw nut engaged threadedly to the steered shaft via a plurality of balls and configured to move the steered shaft in an axial direction; a double row angular contact ball bearing configured to retain the ball screw nut and to support the retained ball screw nut rotatably relative to the housing; a wall portion placed at either side of the double row angular contact ball bearing in the axial direction of the steered shaft, the wall portion being formed integrally with the housing; and an elastic member provided between the wall portion and the outer ring portion and configured to retain the double row angular contact ball bearing to be elastically displaceable in the axial direction.

Abstract: An electric power steering device includes a worm which is swingably connected to the rotation shaft of an electric motor through a joint. A first end portion and second end portion of the worm are supported by a first bearing and a second bearing, respectively. A pair of elastic members elastically urge the worm to an axial neutral position. An annular leaf spring which is held by a housing urges the second end portion toward a worm wheel through the second bearing. A synthetic resin member having a sliding contact surface which is in contact with the leaf spring is integrally disposed on the second bearing.

Abstract: In a speed reducer of an electric power steering system, a first bearing supports a first end portion of a worm so that the first end portion is movable in an axial direction. Elastic members elastically support the worm in the axial direction. A second bearing supports a second end portion of the worm. An urging member oscillates and urges the worm. The sum of first frictional resistance in the axial direction between an inner ring of the first bearing and the worm and second frictional resistance in the axial direction between the urging member and an outer circumference of an outer ring of the second bearing is less than engagement frictional resistance in the axial direction of the worm.

Abstract: A cross shaft joint includes a bearing cup, a cross shaft, and a joint yoke. The bearing cup includes a cylindrical portion in which an opening portion for receiving a shaft portion is formed in one end of the cylindrical portion in an axis direction, and a bottom portion that closes the other end of the cylindrical portion in the axis direction. The bearing cup is press-fitted into the fitting hole and supports the shaft portion through a rolling element so that the shaft portion is able to rotate. The bearing cup is fitted onto the shaft portion inside the fitting hole and holds the rolling element with the shaft portion. A diameter of an inner peripheral surface of the cylindrical portion is smaller on the opening portion side than the bottom portion side in a free state of the bearing cup before being press-fitted into the fitting hole.

Abstract: An electric power steering device includes a worm which is swingably connected to the rotation shaft of an electric motor through a joint. A first end portion and second end portion of the worm are supported by a first bearing and a second bearing, respectively. A pair of elastic members elastically urge the worm to an axial neutral position. An annular leaf spring which is held by a housing urges the second end portion toward a worm wheel through the second bearing. A synthetic resin member having a sliding contact surface which is in contact with the leaf spring is integrally disposed on the second bearing.

Abstract: In a speed reducer of an electric power steering system, a first bearing supports a first end portion of a worm so that the first end portion is movable in an axial direction. Elastic members elastically support the worm in the axial direction. A second bearing supports a second end portion of the worm. An urging member oscillates and urges the worm. The sum of first frictional resistance in the axial direction between an inner ring of the first bearing and the worm and second frictional resistance in the axial direction between the urging member and an outer circumference of an outer ring of the second bearing is less than engagement frictional resistance in the axial direction of the worm.

Abstract: A cross shaft joint includes a bearing cup, a cross shaft, and a joint yoke. The bearing cup includes a cylindrical portion in which an opening portion for receiving a shaft portion is formed in one end of the cylindrical portion in an axis direction, and a bottom portion that closes the other end of the cylindrical portion in the axis direction. The bearing cup is press-fitted into the fitting hole and supports the shaft portion through a rolling element so that the shaft portion is able to rotate. The bearing cup is fitted onto the shaft portion inside the fitting hole and holds the rolling element with the shaft portion. A diameter of an inner peripheral surface of the cylindrical portion is smaller on the opening portion side than the bottom portion side in a free state of the bearing cup before being press-fitted into the fitting hole.

Abstract: An electric power steering system includes: a steered shaft, a housing containing the steered shaft therein in a movable manner; a ball screw nut engaged threadedly to the steered shaft via a plurality of balls and configured to move the steered shaft in an axial direction; a double row angular contact ball bearing configured to retain the ball screw nut and to support the retained ball screw nut rotatably relative to the housing; a wall portion placed at either side of the double row angular contact ball bearing in the axial direction of the steered shaft, the wall portion being formed integrally with the housing; and an elastic member provided between the wall portion and the outer ring portion and configured to retain the double row angular contact ball bearing to be elastically displaceable in the axial direction.

Abstract: A curvature radius of a raceway groove of an inner ring of a first bearing supporting a first end portion of a worm shaft and a curvature radius of a raceway groove of an outer ring of the first bearing are larger than 50% of a diameter of each rolling element of the first bearing, whereby the worm shaft is pivotable about the first end portion. Internal clearances in the first bearing are eliminated because the first bearing is pressed in a radial direction by a pressing member. When the worm shaft vibrates relative to a housing in an axial direction, paired second elastic members and damp and absorb the vibration.

Abstract: A curvature radius of a raceway groove of an inner ring of a first bearing supporting a first end portion of a worm shaft and a curvature radius of a raceway groove of an outer ring of the first bearing are larger than 50% of a diameter of each rolling element of the first bearing, whereby the worm shaft is pivotable about the first end portion. Internal clearances in the first bearing are eliminated because the first bearing is pressed in a radial direction by a pressing member. When the worm shaft vibrates relative to a housing in an axial direction, paired second elastic members and damp and absorb the vibration.

Abstract: A roller bearing is provided with an elastic member that is fitted to an annular groove that is formed in the outer circumference of an outer ring. A chamfered portion, formed on one side face of the groove, is made larger than a chamfered portion formed on the other side face, and has a distance from the bottom face of the groove that is set to ½ or more of the thickness of the elastic member.

Abstract: Deep groove ball bearings are used as bearings supporting both side portions of a worm. In the first bearing on the side of a motor, the curvature radius of a raceway groove in an inner ring or the curvature radius of a raceway groove in an outer ring are set to a specific numerical range with respect to the diameter of a ball.

Abstract: A roller bearing 5 is provided with an elastic member 27 that is fitted to an annular groove 28 that is formed in the outer circumference of an outer ring 21. A chamfered portion 29, formed on one side face of the groove 28, is made larger than a chambered portion 30 formed on the other side face, and has a distance from the bottom face of the groove 28 that is set to ½ or more of the thickness of the elastic member 27.

Abstract: Deep groove ball bearings are used as bearings supporting both side portions of a worm. In the first bearing on the side of a motor, the curvature radius of a raceway groove in an inner ring or the curvature radius of a raceway groove in an outer ring are set to a specific numerical range with respect to the diameter of a ball.

Abstract: A ferrofluid seal apparatus comprises magnetic fluid holding means for storing a magnetic fluid with one of an inner and an outer elements which are relatively rotated. The magnetic fluid holding means has a storage section for storing a part of the magnetic fluid which flows out of said magnetic fluid holding means.

Abstract: A ferrofluid seal apparatus comprises magnetic fluid holding or positing means for storing or retaining a magnetic fluid in a sealing arrangement wherein inner and outer elements are relatively rotated. The magnetic fluid holding means includes an arrangement for retaining the magnetic fluid which flows out from its original position.