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US 2018/0003275 A1Published application
Power steering device
AssigneeHitachi Automotive Systems, Ltd.
InventorOsamu YOSHIDA
Life of this patent
Estimating the term…
Abstract
A power steering device includes: first and second load transition regions provided in first and second predetermined ranges in a nut side ball screw groove from the other end side openings of the first and second connection passages along the nut ball screw groove, formed so that radial distances between a rotation axis of the nut and the nut side ball screw groove are gradually increased toward the other end side opening of the first and second connection passages, and formed so that the balls pass through first and second no load regions, and then pass through a first load region, when the balls in the first and second predetermined ranges are moved from the other end side opening of the first and second connection passages along the nut side ball screw groove.
Claims20
A power steering device comprising:
- a steered shaft arranged to be moved in an axial direction in accordance with a rotation of a steering wheel, and thereby to steer a steered wheel;
- a nut formed into a cylindrical shape surrounding the steered shaft, and arranged to be rotated relative to the steered shaft;
- a ball circulation groove including a shaft side ball screw groove having a helical groove shape, and provided on an outer circumference of the steered shaft, and a nut side ball screw groove having a helical groove shape, and provided on an inner circumference of the nut;
- a plurality of balls disposed within the ball circulation groove to be rolled within the ball circulation groove;
- a first connection passage including one end side opened on an outer circumference surface of the nut, and the other end side opened on an inner circumference surface of the nut, and opened on the one end side of the ball circulation groove;
- a second connection passage including one end side opened on the outer circumference surface of the nut, and the other end side opened on the inner circumference surface of the nut, and opened on the other end side of the ball circulation groove;
- a connection member connecting the first connection passage and the second connection passage to circulate the balls between the first connection passage and the second connection passage;
- an electric motor arranged to drive and rotate the nut, and thereby to provide a steering force to the steered shaft;
- a first load transition region provided in a first predetermined range in the nut side ball screw groove from the other end side opening of the first connection passage along the nut ball screw groove, formed so that a radial distance between a rotation axis of the nut and the nut side ball screw groove is gradually increased toward the other end side opening of the first connection passage, and formed so that the balls pass through a first no load region in which a load is not transmitted from the nut side to the steered shaft side, and then the balls pass through a first load region in which the load is transmitted from the nut side to the steered shaft side, when the balls in the first predetermined range are moved from the other end side opening of the first connection passage along the nut side ball screw groove;
- and
- a second load transition region provided in a second predetermined range in the nut side ball screw groove from the other end side opening of the second connection passage along the nut side ball screw groove, formed so that a radial distance between the rotation axis of the nut and the nut side ball screw groove is gradually increased toward the other end side opening of the second connection passage, and formed so that the balls pass through a second no load region in which the load is not transmitted from the nut side to the steered shaft side, and then the balls pass through a second load region in which the load is transmitted from the nut side to the steered shaft side, when the balls in the second predetermined range are moved from the other end side opening of the second connection passage along the nut side ball screw groove.
8 more elements
A power steering device comprising:
- a steered shaft arranged to be moved in an axial direction in accordance with a rotation of a steering wheel, and thereby to steer a steered wheel;
- a nut formed into a cylindrical shape surrounding the steered shaft, and arranged to be rotated relative to the steered shaft;
- a ball circulation groove including a shaft side ball screw groove having a helical groove shape, and provided on an outer circumference of the steered shaft, and a nut side ball screw groove having a helical groove shape, and provided on an inner circumference of the nut;
- a plurality of balls disposed within the ball circulation groove to be rolled within the ball circulation groove;
- a first connection passage including one end side opened on an outer circumference surface of the nut, and the other end side opened on an inner circumference surface of the nut, and opened on the one end side of the ball circulation groove;
- a second connection passage including one end side opened on the outer circumference surface of the nut, and the other end side opened on the inner circumference surface of the nut, and opened on the other end side of the ball circulation groove;
- a connection member connecting the first connection passage and the second connection passage to circulate the balls between the first connection passage and the second connection passage;
- an electric motor arranged to drive and rotate the nut, and thereby to provide a steering force to the steered shaft;
- a first load transition region provided in a first predetermined range in the nut side ball screw groove from the other end side opening of the first connection passage along the nut ball screw groove, formed so that a radial distance between a rotation axis of the nut and the nut side ball screw groove is gradually increased toward the other end side opening of the first connection passage, and formed so that the balls pass through a first no load region in which a load is not transmitted from the nut side to the steered shaft side, and then the balls pass through a first load region in which the load transmitted from the nut side to the steered shaft side is gradually increased, when the balls in the first predetermined range are moved from the other end side opening of the first connection passage along the nut side ball screw groove;
- and
- a second load transition region provided in a second predetermined range in the nut side ball screw groove from the other end side opening of the second connection so passage along the nut side ball screw groove, formed so that a radial distance between the rotation axis of the nut and the nut side ball screw groove is gradually increased toward the other end side opening of the second connection passage, and formed so that the balls pass through a second no load region in which the load is not transmitted from the nut side to the steered shaft side, and then the balls pass through a second load region in which the load transmitted from the nut side to the steered shaft side is gradually increased, when the balls in the second predetermined range are moved from the other end side opening of the second connection passage along the nut side ball screw groove.
8 more elements
Dependencies are inferred from the claim text.