WO2018147229A1 - ボールねじ装置及び電動パワーステアリング装置 - Google Patents
ボールねじ装置及び電動パワーステアリング装置 Download PDFInfo
- Publication number
- WO2018147229A1 WO2018147229A1 PCT/JP2018/003820 JP2018003820W WO2018147229A1 WO 2018147229 A1 WO2018147229 A1 WO 2018147229A1 JP 2018003820 W JP2018003820 W JP 2018003820W WO 2018147229 A1 WO2018147229 A1 WO 2018147229A1
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- WIPO (PCT)
- Prior art keywords
- nut
- ball
- return hole
- surface portion
- curved surface
- Prior art date
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
- F16H25/2204—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls
- F16H25/2214—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members with balls with elements for guiding the circulating balls
- F16H25/2219—Axially mounted end-deflectors
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/0442—Conversion of rotational into longitudinal movement
- B62D5/0445—Screw drives
- B62D5/0448—Ball nuts
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/22—Screw mechanisms with balls, rollers, or similar members between the co-operating parts; Elements essential to the use of such members
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
- F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
- F16H25/20—Screw mechanisms
- F16H25/24—Elements essential to such mechanisms, e.g. screws, nuts
Definitions
- the present invention relates to a ball screw device and an electric power steering device.
- a ball screw device is known as a device that converts rotational motion into straight motion.
- the ball screw device includes a screw shaft, a nut, and a plurality of balls.
- Patent Document 1 describes an example of a ball screw device.
- the ball screw device described in Patent Document 1 includes a rolling groove formed between a screw shaft and a nut, a circulating top (end deflector) fitted in a notch on the end surface of the nut, and a nut penetrating in the axial direction. And a ball return passage.
- the plurality of balls circulate infinitely through a rolling groove, a ball circulation path formed by a notch on the nut end face and an end deflector, and a ball return path.
- This invention is made in view of said subject, Comprising: It aims at providing the ball screw apparatus which can make the motion of a ball
- a ball screw device includes a screw shaft having a first screw groove on an outer peripheral surface, a second screw groove provided on an inner peripheral surface, and a notch provided on an end surface. And a nut provided on the bottom surface of the notch perpendicular to the axial direction of the screw shaft and having a return hole penetrating in the axial direction, and between the first screw groove and the second screw groove A plurality of balls that roll, and an end deflector that fits into the notch, and the nut includes a curved surface portion at a position between the second screw groove and the return hole in the side surface of the notch, In a first cross section in which the nut is cut in a plane perpendicular to the axial direction and passing through the second thread groove and the notch, the curved surface portion is a radial direction centered on the rotation axis of the nut. Centered on a point located outside the second thread groove And it includes a portion of an arc
- the ball screw device can smooth the movement of the ball. Further, the ball screw device can suppress the generation of sound due to the collision of the ball.
- the nut includes a first recess at an edge of the return hole on the bottom surface. Therefore, the movement when the ball enters the return hole and the movement when the ball exits the return hole become smooth.
- the surface of the first recess is the return hole in the radial direction. It is preferable to include a portion that draws an arc centered on a point located on the inner side. Thereby, the movement of the ball from the curved surface portion toward the return hole and the movement of the ball from the return hole toward the curved surface portion become smoother.
- the nut includes a second concave portion at an end of the bottom surface on the second screw groove side.
- the thickness of the part corresponding to a 2nd recessed part among end deflectors becomes large. For this reason, durability of an end deflector improves.
- a first tangent that is a tangent at an end portion of the curved surface portion far from the second screw groove is equal to a tangent of the return hole.
- the nut includes a flat surface portion that is located on the opposite side of the curved surface portion across the bottom surface of the side surface of the notch, and includes the flat surface portion in the first cross section.
- the straight line is preferably not parallel to the first tangent.
- the electric power steering device includes a ball screw device. Thereby, the electric power steering apparatus can smooth the movement of the member to which the auxiliary steering force is transmitted.
- FIG. 1 is a schematic diagram illustrating an outline of a steering apparatus according to the present embodiment.
- FIG. 2 is a sectional view of the periphery of the ball screw device according to the present embodiment.
- FIG. 3 is a front view of the ball screw device according to the present embodiment.
- 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG.
- FIG. 6 is a perspective view of the end deflector according to the present embodiment.
- FIG. 7 is a perspective view of the nut and the end deflector according to the present embodiment.
- FIG. 8 is a front view illustrating a range in which the ball is separated from the second thread groove.
- FIG. 9 is a cross-sectional view corresponding to the BB cross section of FIG. 4 in the first modification.
- FIG. 10 is a cross-sectional view corresponding to the BB cross section of FIG. 4 in the second modification.
- FIG. 11 is a perspective view of a nut according to a third modification.
- FIG. 12 is a perspective view of an end deflector according to a third modification.
- FIG. 13 is a perspective view of a nut according to a fourth modification.
- FIG. 14 is an enlarged perspective view of the notch of the nut according to the fourth modification.
- 15 is a cross-sectional view taken along the line CC in FIG.
- FIG. 16 is a perspective view of an end deflector according to a fourth modification.
- FIG. 1 is a schematic diagram illustrating an outline of a steering apparatus according to the present embodiment.
- FIG. 2 is a sectional view of the periphery of the ball screw device according to the present embodiment.
- the electric power steering device 80 includes a steering wheel 81, a steering shaft 82, a universal joint 84, a lower shaft 85, a universal joint 86, in the order in which the force given by the operator is transmitted.
- a pinion shaft 87, a pinion 88, a ball screw device 1, and an electric motor 93 are provided.
- the steering wheel 81 is connected to a steering shaft 82.
- One end of the steering shaft 82 is connected to the steering wheel 81, and the other end of the steering shaft 82 is connected to the universal joint 84.
- the lower shaft 85 is connected to the steering shaft 82 via the universal joint 84.
- One end of the lower shaft 85 is connected to the universal joint 84, and the other end is connected to the universal joint 86.
- One end of the pinion shaft 87 is connected to the universal joint 86 and the other end is connected to the pinion 88.
- the ball screw device 1 includes a rack 2 (screw shaft), a nut 3, and a ball 4.
- the pinion 88 meshes with the rack 2.
- the pinion 88 and the rack 2 convert the rotational motion transmitted to the pinion shaft 87 into a straight motion.
- the rack 2 is connected to the tie rod 89. The wheel angle changes as the rack 2 moves.
- the electric motor 93 is, for example, a brushless motor, but may be a motor including a brush (slider) and a commutator (commutator). As shown in FIG. 2, the electric motor 93 is fixed to the housing 930. For example, a small pulley 11 is attached to the shaft of the electric motor 93. The small pulley 11 is connected to the large pulley 13 via the belt 12. The large pulley 13 is attached to the nut 3. For this reason, when the electric motor 93 is driven, the nut 3 rotates around the rotation axis Z.
- the rack 2 passes through the nut 3.
- the nut 3 is fixed to the housing 930 via the bearing 10.
- the bearing 10 includes an outer ring 15, an inner ring 17, and rolling elements 16 positioned between the outer ring 15 and the inner ring 17.
- the outer ring 15 is fixed to the housing 930.
- the inner ring 17 is formed integrally with the nut 3, for example.
- the nut 3 is positioned in the axial direction of the rack 2 (hereinafter simply referred to as the axial direction). That is, the nut 3 can rotate but does not move in the axial direction.
- a plurality of balls 4 are arranged between the first screw groove 21 on the outer peripheral surface of the rack 2 and the second screw groove 31 on the inner peripheral surface of the nut 3.
- the ball 4 circulates infinitely between the first screw groove 21 and the second screw groove 31.
- the ball screw device 1 converts rotational motion into linear motion. Due to the torque generated by the electric motor 93, the force required to move the rack 2 is reduced.
- the electric power steering device 80 employs a rack assist type.
- the electric power steering apparatus 80 includes an ECU (Electronic Control Unit) 90, a torque sensor 94, and a vehicle speed sensor 95.
- the electric motor 93, the torque sensor 94, and the vehicle speed sensor 95 are electrically connected to the ECU 90.
- the torque sensor 94 is attached to the pinion 88, for example.
- the torque sensor 94 outputs the steering torque transmitted to the pinion 88 to the ECU 90 by CAN (Controller Area Network) communication.
- the vehicle speed sensor 95 detects the traveling speed (vehicle speed) of the vehicle body on which the electric power steering device 80 is mounted.
- the vehicle speed sensor 95 is provided in the vehicle body and outputs the vehicle speed to the ECU 90 by CAN communication.
- the ECU 90 controls the operation of the electric motor 93.
- the ECU 90 acquires signals from each of the torque sensor 94 and the vehicle speed sensor 95.
- the ECU 90 is supplied with electric power from a power supply device 99 (for example, an in-vehicle battery) in a state where the ignition switch 98 is on.
- the ECU 90 calculates an auxiliary steering command value based on the steering torque and the vehicle speed.
- the ECU 90 adjusts the power value supplied to the electric motor 93 based on the auxiliary steering command value.
- the ECU 90 acquires information on the induced voltage from the electric motor 93 or information output from a resolver or the like provided in the electric motor 93. As the ECU 90 controls the electric motor 93, the force required to operate the steering wheel 81 is reduced.
- FIG. 3 is a front view of the ball screw device according to the present embodiment.
- 4 is a cross-sectional view taken along the line AA in FIG. 5 is a cross-sectional view taken along the line BB in FIG.
- FIG. 6 is a perspective view of the end deflector according to the present embodiment.
- FIG. 7 is a perspective view of the nut and the end deflector according to the present embodiment.
- the nut 3 includes a second thread groove 31, a notch 33, and a return hole 35.
- the second thread groove 31 has, for example, a Gothic arc shape (a shape formed by a combination of two arcs).
- the first thread groove 21 of the rack 2 also has, for example, a Gothic arc shape as shown in FIG.
- the ball 4 rolls between the first screw groove 21 and the second screw groove 31.
- the ball 4 is in contact with the points 21 a and 21 b on the first screw groove 21 and the points 31 a and 31 b on the second screw groove 31.
- the groove bottom line C1, the ball outline C2, and the ball center line C3 are aligned on a straight line.
- the groove bottom line C ⁇ b> 1 is a line drawn by the bottom of the second screw groove 31.
- the ball outline C2 is a line (trajectory) drawn by a point on the surface of the ball 4 located between the point 31a and the point 31b.
- the ball center line C3 is a line (trajectory) drawn by the center of the ball 4.
- the notch 33 is provided on one end surface and the other end surface of the nut 3. That is, the nut 3 includes two notches 33. As shown in FIG. 5, the notch 33 includes a bottom surface BS that is a surface orthogonal to the rotation axis Z, an auxiliary bottom surface AS that is parallel to the bottom surface BS and is axially displaced from the bottom surface BS, and a bottom surface And a side surface LS that is a surface orthogonal to the BS. The portion corresponding to the bottom surface BS of the notch 33 is deeper in the axial direction than the portion corresponding to the auxiliary bottom surface AS of the notch 33.
- the return hole 35 is provided in the bottom surface BS and penetrates the nut 3 in the axial direction. The return hole 35 extends from the notch 33 on one end face of the nut 3 to the notch 33 on the other end face.
- the nut 3 includes a first curved surface portion 61, a first flat surface portion 64, a second curved surface portion 69, and a second flat surface portion 66 on the side surface LS.
- the first curved surface portion 61 is a curved surface that is orthogonal to the bottom surface BS and is connected to the second screw groove 31.
- FIG. 5 is a cross section taken along the line BB of FIG. 4, in other words, a cross section obtained by cutting the nut 3 along a plane orthogonal to the axial direction and passing through the second screw groove 31 and the notch 33. More specifically, FIG.
- FIG. 5 is a cross section obtained by cutting the nut 3 along a plane that is orthogonal to the axial direction and passes through the bottom end of the second thread groove 31.
- the first curved surface portion 61 draws an arc centered on the point P61.
- the point P61 is located outside the second screw groove 31 in the radial direction around the rotation axis Z (hereinafter simply referred to as the radial direction).
- a point P611 at one end of the first curved surface portion 61 is located on the groove bottom line C1.
- a tangent line L1 of the first curved surface portion 61 passing through the point P611 is equal to a tangent line L2 of the groove bottom line C1 passing through the point P611.
- the point P61 that is the center of the first curved surface portion 61, the point P611 that is the intersection of the first curved surface portion 61 and the groove bottom line C1, and the point PZ on the rotation axis Z are on a straight line.
- the first plane portion 64 is a plane orthogonal to the bottom surface BS and is connected to the first curved surface portion 61. As shown in FIG. 5, one end of the first flat surface portion 64 overlaps the point P612 at the other end of the first curved surface portion 61.
- a point P612 is an end portion of the first curved surface portion 61 that is far from the second screw groove 31.
- a point P642 at the end of the first flat surface portion 64 far from the first curved surface portion 61 is located on a circle drawn by the return hole 35.
- a tangent line L3 of the first curved surface portion 61 passing through the point P612 is equal to a tangent line L4 of the return hole 35 passing through the point P642.
- the tangent line L3 overlaps the first flat surface portion 64.
- the second curved surface portion 69 is a curved surface that is orthogonal to the bottom surface BS.
- the second curved surface portion 69 is located on the opposite side of the first curved surface portion 61 and the first flat surface portion 64 with the return hole 35 interposed therebetween.
- the second curved surface portion 69 draws an arc centered at a point located outside the second screw groove 31 in the radial direction, but between the second screw groove 31 and the return hole 35.
- the first curved surface portion 61 is different from the first curved surface portion 61 in that the first curved surface portion 61 is not disposed.
- the second plane portion 66 is a plane orthogonal to the bottom surface BS, and is located on the opposite side of the first curved surface portion 61 and the first plane portion 64 with the bottom surface BS interposed therebetween.
- the second flat surface portion 66 is connected to the inner peripheral surface of the nut 3.
- the straight line L5 including the second plane part 66 intersects the tangent line L3 (tangent line L4). That is, the straight line L5 is not parallel to the tangent line L3 (tangent line L4).
- the angle ⁇ formed by the straight line L5 and the tangent line L3 (tangent line L4) is preferably 45 ° or less.
- the nut 3 includes a first recess 71 and a second recess 72 on the bottom surface BS.
- the first recess 71 is, for example, a plane orthogonal to the axial direction.
- the first recess 71 is disposed at the edge of the return hole 35.
- the 1st recessed part 71 surrounds the return hole 35 over a perimeter seeing from an axial direction.
- the return hole 35 is provided on the bottom surface of the first recess 71.
- the 2nd recessed part 72 is a plane orthogonal to an axial direction, for example.
- the second recess 72 is disposed at the end of the bottom surface BS on the second screw groove 31 side.
- the ball screw device 1 includes an end deflector 5 shown in FIG.
- the end deflector 5 fits into the notch 33 of the nut 3 as shown in FIG.
- the end deflector 5 is a member for guiding the ball 4 reaching the end of the second screw groove 31 to the return hole 35.
- the ball 4 reaching the end of the second thread groove 31 reaches the return hole 35 through a passage 36 (see FIG. 7) formed between the notch 33 and the end deflector 5.
- the end deflector 5 is also a member for guiding the ball 4 coming out from the return hole 35 to the end of the second screw groove 31.
- the ball 4 coming out of the return hole 35 reaches the end of the second screw groove 31 through the passage 36.
- one end deflector 5 guides the ball 4 from the second screw groove 31 to the return hole 35, and the other end deflector 5 moves the ball 4 coming out of the return hole 35. Guide to the second thread groove 31.
- the end deflector 5 includes a base 50, a protrusion 59, a first arm 51, and a second arm 52.
- the base 50 overlaps the return hole 35 in the axial direction.
- the base 50 includes a first convex portion 501 on an end surface 505 on the side facing the bottom surface BS of the notch 33.
- the first convex portion 501 fits into the first concave portion 71 of the notch 33.
- the protrusion 59 protrudes from the base 50 toward the side opposite to the second screw groove 31.
- the protrusion 59 contacts the auxiliary bottom surface AS of the notch 33 and the second curved surface portion 69. Thereby, the end deflector 5 is stabilized (is less likely to be displaced).
- the first arm 51 protrudes from the base 50 toward the second screw groove 31.
- the first arm 51 includes a curved surface portion 51 a along the first curved surface portion 61 of the notch 33.
- the second arm 52 protrudes from the base 50 toward the second screw groove 31.
- a gap is provided between the first arm 51 and the second arm 52.
- the second arm 52 includes a curved surface portion 52 a along the first curved surface portion 61 of the notch 33.
- the second arm 52 includes a second convex portion 522 on the side facing the bottom surface BS of the notch 33. The second convex portion 522 fits into the second concave portion 72 of the notch 33.
- FIG. 8 is a front view for showing a range in which the ball is separated from the second thread groove. Since the second screw groove 31 has a spiral shape centered on the rotation axis Z, the number of balls 4 increases as the number of turns of the spiral increases. The load applied to one ball 4 decreases as the number of balls 4 increases. On the other hand, when the ball 4 passes through the passage 36 (see FIG. 7) and the return hole 35, the ball 4 does not contact the second screw groove 31. That is, the ball 4 is separated from the second thread groove 31 and no load is applied to the ball 4. As the number of balls 4 in the range in which the balls 4 are separated from the second thread grooves 31 increases, the load applied to one ball 4 increases.
- the range in which the balls 4 are separated from the second thread grooves 31 is reduced, the number of balls 4 that receive the load increases, so the load applied to one ball 4 is reduced. If the load applied to the ball 4 is large, the life of the ball screw device 1 is shortened. Therefore, it is desirable that the range in which the ball 4 is separated from the second screw groove 31 is small.
- the range in which the ball 4 is separated from the second thread groove 31 is a range delimited by the plane S1 and the plane S2.
- the plane S1 is a plane including the rotation axis Z and passing through a point where the ball 4 is separated from the second thread groove 31.
- the plane S2 is a plane including the rotation axis Z and passing through a point where the ball 4 starts to contact the second thread groove 31.
- the angle ⁇ formed by the plane S1 and the plane S2 is twice the angle ⁇ formed by the plane S1 and the plane S3.
- the plane S3 is a plane that includes the rotation axis Z and passes through the center of the return hole 35.
- the range in which the ball is separated from the thread groove is a range delimited by the plane S1X and the plane S2X as shown in FIG.
- the plane S1X is a plane including the rotation axis Z and passing through the intersection of the circle drawn by the second screw groove 31 and the straight line T1 when viewed from the axial direction.
- the straight line T1 is a common tangent line between the circle drawn by the return hole 35 and the circle drawn by the second screw groove 31 when viewed from the axial direction.
- the plane S2X is a plane including the rotation axis Z and passing through the intersection of the circle drawn by the second screw groove 31 and the straight line T2 when viewed from the axial direction.
- the straight line T2 is a straight line symmetrical to the straight line T1 with respect to the plane S3.
- the range in which the ball 4 is separated from the second screw groove 31 is smaller than the case where the notch is formed in a linear shape.
- the angle ⁇ formed by the plane S1 and the plane S2 is smaller than the angle ⁇ formed by the plane S1X and the plane S2X.
- the life tends to be long (the load capacity tends to be large).
- the end deflector 5 is likely to be smaller than when the notch is formed in a straight line. Since the first arm 51 and the second arm 52 are shortened, the durability of the end deflector 5 is improved. In addition, the end deflector 5 can be easily manufactured.
- the ball screw device 1 is not necessarily used for the electric power steering device 80.
- the ball screw device 1 can be widely applied to devices that need to convert rotational motion into linear motion.
- the tangent line L1 at the end of the first curved surface portion 61 may not be equal to the tangent line of the groove bottom line C1.
- the tangent at the end of the first curved surface portion 61 may not coincide with the tangent of the groove bottom line C1.
- the first curved surface portion 61 does not necessarily have to draw an arc centered on the point P61 over the entire length.
- the 1st curved surface part 61 should just contain the part which draws the circular arc centering on the point located in the radial direction outside the 2nd screw groove 31.
- the first curved surface portion 61 may include a plurality of arcs having different centers.
- the ball screw device 1 includes a screw shaft (rack 2), a nut 3, a plurality of balls 4, and an end deflector 5.
- the screw shaft has a first screw groove 21 on the outer peripheral surface.
- the nut 3 includes a second screw groove 31 provided on the inner peripheral surface, a notch 33 provided on the end surface, and a return hole 35 provided on the bottom surface BS of the notch 33 orthogonal to the axial direction and penetrating in the axial direction.
- the end deflector 5 fits into the notch 33.
- the nut 3 includes a curved surface portion (first curved surface portion 61) at a position between the second screw groove 31 and the return hole 35 in the side surface LS of the notch 33.
- first curved surface portion first curved surface portion 61
- the curved surface portion is in the radial direction. And includes a portion that draws an arc with the point located outside the second thread groove 31 as the center of P61.
- the notch 33 is arranged so as to be positioned on the upper side in the vertical direction, so that the ball 4 can always be brought closer to the screw shaft side by the weight of the ball 4. It is. This prevents the ball 4 from colliding with the edge of the second screw groove 31.
- the position of the notch 33 cannot be fixed.
- the curved surface portion (first curved surface portion 61) causes the curved surface when the ball 4 enters the second screw groove 31 from the notch 33 side. The ball 4 is brought closer to the first screw groove 21 side by the portion (first curved surface portion 61).
- the ball 4 is in contact with the first screw groove 21 and guided by the first screw groove 21 before entering the second screw groove 31 from the notch 33 side.
- the ball 4 guided by the first screw groove 21 passes through the middle of the first screw groove 21. For this reason, a collision is suppressed at the edge of the ball 4 and the nut 3. Therefore, the ball screw device 1 can smooth the movement of the ball 4. Further, the ball screw device 1 can suppress the generation of sound due to the collision of the balls 4.
- the nut 3 includes a first recess 71 at the edge of the return hole 35 of the bottom surface BS. Thereby, the movement when the ball 4 enters the return hole 35 and the movement when the ball 4 exits the return hole 35 become smooth.
- the nut 3 includes a second recess 72 at the end of the bottom surface BS on the second screw groove 31 side.
- the thickness (the 2nd arm 52) of the part corresponding to the 2nd recessed part 72 among the end deflectors 5 becomes large. For this reason, the durability of the end deflector 5 is improved.
- the first tangent line (tangent line L3) that is a tangent line at the end portion (point P612) of the curved surface portion (first curved surface portion 61) far from the second thread groove 31 is , Equal to the tangent L4 of the return hole 35.
- the nut 3 is a flat surface portion (second flat surface portion 66) located on the opposite side of the curved surface portion (first curved surface portion 61) across the bottom surface BS of the side surface LS of the notch 33. Is provided.
- the straight line L5 drawn by the plane portion (second plane portion 66) is not parallel to the first tangent line (tangent line L3). Accordingly, the position of the return hole 35 can be easily arranged on the inner side in the radial direction, so that the distance from the second screw groove 31 to the return hole 35 can be shortened.
- the electric power steering device 80 includes a ball screw device 1. Thereby, the electric power steering apparatus 80 can smooth the movement of the member (rack 2) to which the auxiliary steering force is transmitted.
- FIG. 9 is a cross-sectional view corresponding to the BB cross section of FIG. 4 in the first modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
- the notch 33A according to the first modification has a first curved surface portion 61A having a shape different from that of the first curved surface portion 61 described above.
- One end of the first curved surface portion 61 ⁇ / b> A is connected to the second screw groove 31.
- the first curved surface portion 61A draws an arc centered on the point P61A.
- the point P61A is located outside the second screw groove 31 in the radial direction.
- a point P611A on the extension line of the first curved surface portion 61A is located on the ball outline C2.
- a tangent L1A of the first curved surface portion 61A passing through the point P611A is equal to a tangent L2A of the ball outline C2 passing through the point P611A. That is, the point P61A that is the center of the first curved surface portion 61A, the point P611A that is the intersection of the first curved surface portion 61A and the ball outline C2, and the point PZ on the rotation axis Z are in a straight line.
- FIG. 10 is a cross-sectional view corresponding to the BB cross section of FIG. 4 in the second modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
- the notch 33B according to the second modification has a first curved surface portion 61B having a shape different from that of the first curved surface portion 61 described above.
- One end of the first curved surface portion 61B is connected to the second screw groove 31.
- the first curved surface portion 61B draws an arc centered on the point P61B.
- the point P61B is located outside the second screw groove 31 in the radial direction.
- a point P611B on the extension line of the first curved surface portion 61B intersects the ball center line C3.
- a tangent line L1B of the first curved surface portion 61B passing through the point P611B is equal to a tangent line L2B of the ball center line C3 passing through the point P611B. That is, the point P61B that is the center of the first curved surface portion 61B, the point P611B that is the intersection of the first curved surface portion 61B and the ball center line C3, and the point PZ on the rotation axis Z are in a straight line.
- FIG. 11 is a perspective view of a nut according to a third modification.
- FIG. 12 is a perspective view of an end deflector according to a third modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
- the nut 3C according to the third modified example does not have the first concave portion 71 and the second concave portion 72 described above in the notch 33C.
- the end deflector 5C according to the third modification does not have the first convex portion 501 and the second convex portion 522 described above. Thereby, manufacture of nut 3C and end deflector 5C becomes easy.
- the radius of curvature of the locus 40C drawn by the center of the ball 4 when the ball 4 passes the edge of the return hole 35 is, for example, 0.7 times the diameter of the ball 4.
- FIG. 13 is a perspective view of a nut according to a fourth modification.
- FIG. 14 is an enlarged perspective view of the notch of the nut according to the fourth modification.
- 15 is a cross-sectional view taken along the line CC in FIG.
- FIG. 16 is a perspective view of an end deflector according to a fourth modification. Note that the same components as those described in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.
- the nut 3D according to the fourth modification includes a first recess 75 in the bottom surface BS of the notch 33D.
- FIG. 15 is a CC cross section in FIG. 14, in other words, a cross section in which the nut 3D is cut along a plane orthogonal to the bottom surface BS and passing through the center of the return hole 35.
- the surface of the first recess 75 draws an arc centered on a point P75 located inside the return hole 35 in the radial direction.
- the radius of curvature D40 of the locus 40D drawn by the center of the ball 4 when the ball 4 passes over the surface of the first recess 75 is, for example, 1.5 times the diameter of the ball 4.
- the curvature radius D40 is preferably greater than 0.7 times the diameter of the ball 4 and not more than 1.5 times.
- the end surface 505D is smaller than the end surface 505 described above.
- a portion overlapping the first recess 75 in the axial direction is cut away.
- the end surface 505D is in contact with the positioning surface 76 shown in FIGS.
- the positioning surface 76 is a part of the bottom surface BS.
- the surface of the first recess 75 is , Including a portion that draws an arc centering on a point P75 located inside the return hole 35 in the radial direction.
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Abstract
Description
図1は、本実施形態に係るステアリング装置の概略を示す模式図である。図2は、本実施形態に係るボールねじ装置の周辺の断面図である。図1に示すように、電動パワーステアリング装置80は、操作者から与えられる力が伝達する順に、ステアリングホイール81と、ステアリングシャフト82と、ユニバーサルジョイント84と、ロアシャフト85と、ユニバーサルジョイント86と、ピニオンシャフト87と、ピニオン88と、ボールねじ装置1と、電動モータ93と、を備える。
図9は、第1変形例における、図4のB-B断面に相当する断面図である。なお、上述した実施形態で説明したものと同じ構成要素には同一の符号を付して重複する説明は省略する。
図10は、第2変形例における、図4のB-B断面に相当する断面図である。なお、上述した実施形態で説明したものと同じ構成要素には同一の符号を付して重複する説明は省略する。
図11は、第3変形例に係るナットの斜視図である。図12は、第3変形例に係るエンドデフレクタの斜視図である。なお、上述した実施形態で説明したものと同じ構成要素には同一の符号を付して重複する説明は省略する。
図13は、第4変形例に係るナットの斜視図である。図14は、第4変形例に係るナットの切欠きを拡大した斜視図である。図15は、図14におけるC-C断面図である。図16は、第4変形例に係るエンドデフレクタの斜視図である。なお、上述した実施形態で説明したものと同じ構成要素には同一の符号を付して重複する説明は省略する。
2 ラック(ねじ軸)
21 第1ねじ溝
3 ナット
31 第2ねじ溝
33 切欠き
35 戻し穴
36 通路
4 ボール
5 エンドデフレクタ
50 基部
501 第1凸部
51 第1アーム
52 第2アーム
522 第2凸部
59 突起
61 第1曲面部
64 第1平面部
66 第2平面部
69 第2曲面部
71 第1凹部
72 第2凹部
80 電動パワーステアリング装置
81 ステアリングホイール
82 ステアリングシャフト
84 ユニバーサルジョイント
85 ロアシャフト
86 ユニバーサルジョイント
87 ピニオンシャフト
88 ピニオン
89 タイロッド
90 ECU
93 電動モータ
94 トルクセンサ
95 車速センサ
98 イグニッションスイッチ
99 電源装置
AS 補助底面
BS 底面
C1 溝底線
C2 ボール外形線
C3 ボール中心線
LS 側面
Z 回転軸
Claims (7)
- 外周面に第1ねじ溝を有するねじ軸と、
内周面に設けられる第2ねじ溝、端面に設けられる切欠き、及び前記ねじ軸の軸方向に対して直交する前記切欠きの底面に設けられ且つ前記軸方向に貫通する戻し穴を有するナットと、
前記第1ねじ溝と前記第2ねじ溝との間を転がる複数のボールと、
前記切欠きに嵌まるエンドデフレクタと、
を備え、
前記ナットは、前記切欠きの側面のうち前記第2ねじ溝と前記戻し穴との間の位置に曲面部を備え、
前記軸方向に対して直交し且つ前記第2ねじ溝及び前記切欠きを通る平面で前記ナットを切った第1断面において、前記曲面部は、前記ナットの回転軸を中心とした放射方向で前記第2ねじ溝よりも外側に位置する点を中心とした円弧を描く部分を含む
ボールねじ装置。 - 前記ナットは、前記底面の前記戻し穴の縁に第1凹部を備える
請求項1に記載のボールねじ装置。 - 前記底面に対して直交し且つ前記戻し穴の中心を通る平面で前記ナットを切った第2断面において、前記第1凹部の表面は、前記放射方向で前記戻し穴よりも内側に位置する点を中心とした円弧を描く部分を含む
請求項2に記載のボールねじ装置。 - 前記ナットは、前記底面のうち前記第2ねじ溝側の端部に第2凹部を備える
請求項1から3のいずれか1項に記載のボールねじ装置。 - 前記第1断面において、前記曲面部の前記第2ねじ溝から遠い側の端部における接線である第1接線は、前記戻し穴の接線と等しい
請求項1から4のいずれか1項に記載のボールねじ装置。 - 前記ナットは、前記切欠きの側面のうち前記底面を挟んで前記曲面部とは反対側に位置する平面部を備え、
前記第1断面において、前記平面部を含む直線は前記第1接線に対して平行でない
請求項5に記載のボールねじ装置。 - 請求項1から6のいずれか1項に記載のボールねじ装置を備える電動パワーステアリング装置。
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CN201880009310.6A CN110234909B (zh) | 2017-02-13 | 2018-02-05 | 滚珠丝杠装置及电动助力转向装置 |
EP18742389.2A EP3399213B1 (en) | 2017-02-13 | 2018-02-05 | Ball screw device and electric power steering device |
US16/073,409 US11204083B2 (en) | 2017-02-13 | 2018-02-05 | Ball screw device and electric power steering device |
KR1020197021156A KR102021026B1 (ko) | 2017-02-13 | 2018-02-05 | 볼 나사 장치 및 전동 파워 스티어링 장치 |
JP2018523833A JP6365809B1 (ja) | 2017-02-13 | 2018-02-05 | ボールねじ装置及び電動パワーステアリング装置 |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2004036644A (ja) | 2002-06-28 | 2004-02-05 | Nsk Ltd | ボールねじ装置 |
JP2013024321A (ja) * | 2011-07-20 | 2013-02-04 | Nsk Ltd | ボールねじ機構及びこれを使用した電動パワーステアリング装置 |
JP2014077459A (ja) * | 2012-10-09 | 2014-05-01 | Nsk Ltd | 電動パワーステアリング装置 |
JP2017002978A (ja) * | 2015-06-09 | 2017-01-05 | 日本精工株式会社 | 電動パワーステアリング装置 |
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TWM292650U (en) * | 2005-10-21 | 2006-06-21 | Comtop Technology Co Ltd | Improved structure of ball screw nut and circulator |
CN2921456Y (zh) * | 2006-03-23 | 2007-07-11 | 全球滚珠科技股份有限公司 | 滚珠螺帽及其循环器 |
WO2007114036A1 (ja) * | 2006-03-31 | 2007-10-11 | Thk Co., Ltd. | ボールねじ装置 |
CN202392064U (zh) * | 2011-11-25 | 2012-08-22 | 昇章机械有限公司 | 循环器 |
JP5967233B2 (ja) * | 2015-01-28 | 2016-08-10 | 株式会社ジェイテクト | ボール螺子装置及び電動パワーステアリング装置 |
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- 2018-02-05 EP EP18742389.2A patent/EP3399213B1/en active Active
- 2018-02-05 WO PCT/JP2018/003820 patent/WO2018147229A1/ja active Application Filing
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
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JP2004036644A (ja) | 2002-06-28 | 2004-02-05 | Nsk Ltd | ボールねじ装置 |
JP2013024321A (ja) * | 2011-07-20 | 2013-02-04 | Nsk Ltd | ボールねじ機構及びこれを使用した電動パワーステアリング装置 |
JP2014077459A (ja) * | 2012-10-09 | 2014-05-01 | Nsk Ltd | 電動パワーステアリング装置 |
JP2017002978A (ja) * | 2015-06-09 | 2017-01-05 | 日本精工株式会社 | 電動パワーステアリング装置 |
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EP3399213B1 (en) | 2020-03-25 |
EP3399213A1 (en) | 2018-11-07 |
KR20190091556A (ko) | 2019-08-06 |
TWI675974B (zh) | 2019-11-01 |
KR102021026B1 (ko) | 2019-09-11 |
TW201833459A (zh) | 2018-09-16 |
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