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US 8,505,405 B2Granted
Ball screw apparatus and electric power steering apparatus
AssigneeJtekt Corporation
InventorsTetsuya Kaneko, Masayoshi Asakura, Takashi Hara
Life of this patent
Estimating the term…
Abstract
The ball screw apparatus includes a returning way L2 by mounting a circulating member 15 in mounted holes 16, 17 formed in the ball screw nut 13. The ball screw nut 13 includes a base portion 51 and an expanding portion 52. In the base portion 50 a distance from an axis center O1 of the rack shaft 3 to a bottom portion 14a of the nut side screw groove 14 is constant, and in the expanding portion 52 the distance is larger than that of the base portion 51. The expanding portion 52 includes a connecting area 34.
Claims15
A ball screw apparatus comprising:
- a screw shaft having a shaft side screw groove formed on an outer peripheral surface thereof;
- a ball screw nut having a nut side screw groove formed on an inner peripheral surface thereof;
- a plurality of balls installed in a spiral rotating way formed by facing said nut side screw groove to said shaft side screw groove;
- and
- a circulating member mounted on a mounting hole formed in said ball screw nut and forming a returning way to connect one end and the other end of said rotating way, wherein
- said nut side screw groove includes a connecting area connecting said rotating way to said returning way, wherein
- said connecting area faced to said mounting hole in said nut side screw groove is machined to substantially eliminate possible steps at a jointing point of said rotating way and said returning way, wherein
- said ball screw nut has a base portion and an expanding portion,
- in said base portion a distance from an axis center of said screw shaft to a bottom portion of said nut side screw groove is constant in order to rotate said ball being put between said nut side screw groove and said shaft side screw groove,
- in said expanding portion said distance is larger than that of the base portion, and
- said expanding portion includes said connecting area.
8 more elements
A ball screw apparatus comprising:
- a screw shaft having a shaft side screw groove formed on an outer peripheral surface thereof;
- a ball screw nut having a nut side screw groove formed on an inner peripheral surface thereof, said ball screw nut is fixed at one end thereof along an axial direction,
- a plurality of balls installed in a spiral rotating way formed by facing said nut side screw groove to said shaft side screw groove;
- and
- a circulating member mounted on a mounting hole formed in said ball screw nut and forming a returning way to connect one end and the other end of said rotating way, wherein
- said nut side screw groove includes a connecting area connecting said rotating way to said returning way, wherein
- said connecting area faced to said mounting hole in said nut side screw groove is machined to substantially eliminate possible steps at a jointing point of said rotating way and said returning way, wherein
- said ball screw nut has a base portion and an expanding portion,
- in said base portion a distance from an axis center of said screw shaft to a bottom portion of said nut side screw groove is constant in order to rotate said ball being put between said nut side screw groove and said shaft side screw groove, wherein
- said expanding portion includes said connecting area mounted at a side of said one end of said ball screw nut, and a gradual changing area being adjacent to said base portion and formed within 180 degrees in a way that said distance is gradually and continuously reduced in accordance with approaching from said jointing point to said base portion, wherein
- said expanding portion includes a non-contacting area where said ball does not contact with one of said shaft side screw groove and said nut side screw groove, and
- said non-contacting area is formed from said jointing point continuously.
9 more elements
An electric power steering apparatus having a ball screw apparatus, wherein
- said ball screw apparatus comprising:
- a screw shaft having a shaft side screw groove formed on an outer peripheral surface thereof;
- a ball screw nut having a nut side screw groove formed on an inner peripheral surface thereof;
- a plurality of balls installed in a spiral rotating way formed by facing said nut side screw groove to said shaft side screw groove;
- and
- a circulating member mounted on a mounting hole formed in said ball screw nut and forming a returning way to connect one end and the other end of said rotating way, wherein
- said nut side screw groove includes a connecting area connecting said rotating way to said returning way, wherein
- said connecting area faced to said mounting hole in said nut side screw groove is machined to substantially eliminate possible steps at a jointing point of said rotating way and said returning way, wherein
- said ball screw nut has a base portion and an expanding portion,
- in said base portion a distance from an axis center of said screw shaft to a bottom portion of said nut side screw groove is constant in order to rotate said ball being put between said nut side screw groove and said shaft side screw groove,
- in said expanding portion said distance is larger than that of the base portion, and
- said expanding portion includes said connecting area.
9 more elements
An electric power steering apparatus having a ball screw apparatus,
- wherein said ball screw apparatus comprising:
- a rack shaft having a shaft side screw groove formed on an outer peripheral surface thereof;
- a ball screw nut having a nut side screw groove formed on an inner peripheral surface thereof, said ball screw nut is fixed at one end thereof along an axial direction,
- a plurality of balls installed in a spiral rotating way formed by facing said nut side screw groove to said shaft side screw groove;
- and
- a circulating member mounted on a mounting hole formed in said ball screw nut and forming a returning way to connect one end and the other end of said rotating way, wherein
- said nut side screw groove includes a connecting area connecting said rotating way to said returning way, wherein
- said connecting area faced to said mounting hole in said nut side screw groove is machined to substantially eliminate possible steps at a jointing point of said rotating way and said returning way, wherein
- said ball screw nut has a base portion and an expanding portion,
- in said base portion a distance from an axis center of said rack shaft to a bottom portion of said nut side screw groove is constant in order to rotate said ball being put between said nut side screw groove and said shaft side screw groove, wherein
- said expanding portion includes said connecting area mounted at a side of said one end of said ball screw nut, and a gradual changing area being adjacent to said base portion and formed within 180 degrees in a way that said distance is gradually and continuously reduced in accordance with approaching from said jointing point to said base portion, wherein
- said expanding portion includes a non-contacting area where said ball does not contact with one of said shaft side screw groove and said nut side screw groove, and
- said non-contacting area is formed from said jointing point continuously.
10 more elements
An electric power steering apparatus having a ball screw apparatus,
- wherein said ball screw apparatus comprising:
- a rack shaft having a shaft side screw groove formed on an outer peripheral surface thereof;
- a ball screw nut having a nut side screw groove formed on an inner peripheral surface thereof, said ball screw nut is fixed at one end thereof along an axial direction and said nut side screw groove is constructed with an arc part;
- a plurality of balls installed in a spiral rotating way formed by facing said nut side screw groove to said shaft side screw groove;
- and
- a circulating member mounted on a mounting hole formed in said ball screw nut and forming a returning way to connect one end and the other end of said rotating way, wherein
- said nut side screw groove includes a connecting area connecting said rotating way to said returning way, wherein
- said connecting area faced to said mounting hole in said nut side screw groove is machined to substantially eliminate possible steps at a jointing point of said rotating way and said returning way, wherein
- said ball screw nut has a base portion and an expanding portion,
- in said base portion a distance from an axis center of said rack shaft to a bottom portion of said nut side screw groove is constant in order to rotate said ball being put between said nut side screw groove and said shaft side screw groove, wherein
- said expanding portion is formed in a way that a center of said arc part is offset to a direction of said circulating member in relating to said shaft center of said rack shaft, wherein
- said expanding portion includes said connecting area mounted at a side of said one end of said ball screw nut, and a gradual changing area being adjacent to said base portion and formed within 45 degrees in a way that said distance is gradually and continuously reduced in accordance with approaching from said jointing point to said base portion, wherein
- said expanding portion includes a non-contacting area where said ball does not contact with one of said shaft side screw groove and said nut side screw groove, and
- said non-contacting area is formed from said jointing point continuously.
11 more elements
Dependencies are inferred from the claim text.