Ball screw device

Abstract

The present application realizes the restriction of the stroke end of the nut as a linear motion element with a small number of parts, realizes the miniaturization of the ball screw device, and realizes the improvement of the control. A protrusion-shaped non-rotation side engaging portion (13) is provided at the end of the axial one side of the nut (3), and a circular arc-shaped rotation side engaging groove portion (18) is provided at the driving member (5) which is fixed to the threaded shaft (2) and rotates the threaded shaft (2), the rotation side engaging groove portion (18) can insert the non-rotation side engaging portion (13) in the axial direction, and the end portion in the circumferential direction can be engaged with the non-rotation side engaging portion (13) in the circumferential direction.

Description

Technical Field

[0001] This invention relates to ball screw devices. Background Technology

[0002] A ball screw is a mechanical component used to convert linear motion into rotary motion, or vice versa. Because balls roll between a threaded shaft and a nut, it offers higher efficiency compared to a sliding screw where the threaded shaft and nut are in direct contact. Therefore, ball screws are used in various mechanical devices, such as electric brake systems in automobiles, automatic manual transmissions (AMTs), and positioning devices in machine tools, to convert rotary motion from drive sources like electric motors into linear motion.

[0003] A ball screw assembly comprises: a threaded shaft having helical ball thread grooves on its outer circumferential surface; a nut having helical ball thread grooves on its inner circumferential surface; and a plurality of balls disposed between the ball thread grooves on the shaft side and the ball thread grooves on the nut side. Depending on the application, the ball screw assembly uses one of the threaded shaft and the nut as a rotary motion element and the other as a linear motion element.

[0004] In a ball screw assembly, to prevent the linear motion element from moving beyond a predetermined range, the end of the stroke of the linear motion element is limited. Figure 35 This refers to the ball screw device 100 with a conventional structure as described in Japanese Patent Application Publication No. 2016-70281, which has a structure for limiting the end of the stroke of a linear motion element.

[0005] The ball screw assembly 100 includes a threaded shaft 101, a nut 102, a plurality of balls (not shown), and a limiting member 103.

[0006] The threaded shaft 101 has a threaded portion 104 and a mating shaft portion 105 disposed adjacent to one axial side of the threaded portion 104. A helical axial ball thread groove 106 is formed on the outer peripheral surface of the threaded portion 104. The mating shaft portion 105 has an outer diameter smaller than that of the threaded portion 104 and external splines are formed on its outer peripheral surface. The threaded shaft 101 is coaxially disposed with the nut 102 when the threaded portion 104 is inserted into the inside of the nut 102.

[0007] The nut 102 has a cylindrical shape and has a helical ball thread groove (not shown) and a generally S-shaped circulation groove on its inner circumferential surface. The nut 102 has an engaging portion 107 at one end on the axial side.

[0008] The shaft-side ball thread groove 106 and the nut-side ball thread groove are arranged radially opposite to each other, forming a helical load path. The beginning and end points of the load path are connected by a circulation groove formed on the inner circumferential surface of the nut 102. Therefore, the balls reaching the end point of the load path return to the beginning point of the load path through the circulation groove. Furthermore, the beginning and end points of the load path change according to the direction of the relative axial displacement (relative rotation direction) between the threaded shaft 101 and the nut 102.

[0009] The limiting member 103 has a protrusion 108 and a claw 109. The protrusion 108 has an annular shape, and the claw 109 has a protruding shape. The protrusion 108 is externally engaged with the engagement shaft portion 105 of the threaded shaft 101 without relative rotation. Specifically, the protrusion 108 is externally engaged with the external spline teeth formed on the inner peripheral surface of the engagement shaft portion 105 by engaging the internal spline teeth formed on the outer peripheral surface of the engagement shaft portion 105. The claw 109 protrudes radially from a portion of the circumferential direction of the outer peripheral surface of the protrusion 108.

[0010] In the existing ball screw device 100, when either the threaded shaft 101 or the nut 102 reaches the end of its stroke, the engaging portion 107 on the nut 102 and the claw portion 109 on the limiting member 103 engage in the circumferential direction. This prevents rotation of either the threaded shaft 101 or the nut 102, thus limiting the end of the stroke of the linear motion element.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2016-70281 Summary of the Invention

[0014] The problem that the invention aims to solve

[0015] In the existing ball screw assembly 100 disclosed in Japanese Patent Application Publication No. 2016-70281, a limiting member 103, which is a dedicated component, is used to limit the end of the stroke of the linear motion element. Therefore, in cases where, for example, the threaded shaft 101 is used as the rotary motion element and the nut 102 is used as the linear motion element, a drive component for rotating the threaded shaft 101 needs to be provided separately from the limiting member 103. Consequently, the number of parts increases, and the ball screw assembly 100 is prone to becoming larger.

[0016] Furthermore, in the existing ball screw device 100 described in Japanese Patent Application Publication No. 2016-70281, when the engaging portion 107 provided on the nut 102 and the claw portion 109 provided on the limiting member 103 engage in the circumferential direction, the limiting member 103 undergoes elastic deformation, and the threaded shaft 101 twists between the limiting member 103 and the drive member. This presents a possibility that the drive member may stop after the threaded shaft 101 rotates a further amount. Thus, the rotation stop position of the drive member may deviate from its initial position. Consequently, it becomes difficult to strictly manage the axial position (stroke) of the nut 102, potentially resulting in reduced controllability of the ball screw device 100.

[0017] The present invention was made to solve the above-mentioned problems, and its object is to provide a ball screw device that can limit the end of the stroke of the nut, which is a linear motion element, with a small number of parts, thereby achieving miniaturization and improving controllability.

[0018] Solution for solving the problem

[0019] One aspect of the present invention provides a ball screw device comprising a threaded shaft, a nut, a plurality of balls, and a drive component.

[0020] The aforementioned threaded shaft has a helical axial ball thread groove on its outer circumferential surface and rotates during use.

[0021] The nut has a helical ball thread groove on its inner circumferential surface and a protruding non-rotating engagement portion at one end on the axial side, and moves linearly during use.

[0022] The aforementioned multiple balls are arranged between the aforementioned shaft-side ball thread groove and the aforementioned nut-side ball thread groove.

[0023] The aforementioned drive component is fixed to the aforementioned threaded shaft in a way that prevents relative rotation, and drives the aforementioned threaded shaft in a rotational manner.

[0024] In a ball screw device according to one aspect of the present invention, the drive component has an arc-shaped rotating side engagement groove, which allows the non-rotating side engagement portion to be inserted axially, and its end in the circumferential direction to engage with the non-rotating side engagement portion in the circumferential direction.

[0025] In one embodiment of the ball screw device of the present invention, the rotating side engagement groove can be a through groove that passes through the drive member in the axial direction, or a bottomed groove that opens on the side of the drive member on the other side in the axial direction.

[0026] In one embodiment of the ball screw device of the present invention, the aforementioned rotating side engagement groove is a bottomed groove with a constant axial depth.

[0027] In one embodiment of the ball screw device of the present invention, the aforementioned rotating side engagement groove can be a bottomed groove whose axial depth varies along the circumferential direction.

[0028] In this case, the inclination angle of the bottom surface of the rotating engagement groove relative to the imaginary plane orthogonal to the central axis of the drive component can be the same as or smaller than the lead angle of the axial ball thread groove.

[0029] In one embodiment of the present invention, the ball screw device can include multiple of the aforementioned rotating side engagement grooves.

[0030] In this case, multiple rotating side engaging slots can be arranged at equal intervals in the circumferential direction of the drive component.

[0031] Furthermore, in this case, the non-rotating side engaging portion can also be one, or the same number as the rotating side engaging groove portion.

[0032] In one embodiment of the ball screw device of the present invention, the center angle of the rotating side engagement groove can be 36 degrees or more and 324 degrees or less.

[0033] In a ball screw device according to one aspect of the present invention, the size of the central angle of the rotating side engagement groove can be made larger than the size of the central angle of the non-rotating side engagement.

[0034] In a ball screw device according to one aspect of the present invention, the size of the central angle of the portion of the drive member that separates from the rotating side engagement groove in the circumferential direction is larger than the size of the central angle of the non-rotating side engagement portion.

[0035] In one embodiment of the ball screw device of the present invention, the aforementioned rotating side engagement groove portion can have a reinforcing portion in the circumferential direction at the middle portion, which connects the inner surface of the radially outer side and the inner surface of the radially inner side in a radial direction.

[0036] In a ball screw device according to one aspect of the present invention, the aforementioned drive component can have a torque input section on its outer peripheral surface.

[0037] In this case, the threaded shaft can have: a threaded portion having the aforementioned axial ball thread groove formed on its outer peripheral surface; and a fitting shaft portion having the aforementioned drive component externally fixed to one axial side of the threaded portion and not rotatably disposed thereon; and the aforementioned torque input portion is radially disposed at a position overlapping the portion of the aforementioned rotating side fitting groove that engages with the aforementioned non-rotating side fitting portion.

[0038] In this case, the aforementioned driving component can be any one of a gear, a pulley, or a sprocket.

[0039] In one embodiment of the ball screw device of the present invention, the aforementioned drive component can also be a motor shaft.

[0040] Invention Effects

[0041] According to one aspect of the present invention, the ball screw device can limit the end of the stroke of the nut, which is a linear motion element, with a small number of parts, thereby achieving miniaturization and improved controllability. Attached Figure Description

[0042] Figure 1 This is a front view of the ball screw device of the first embodiment of the present invention, viewed from the axial side.

[0043] Figure 2 Regarding the ball screw device in the first example, it indicates a state that limits the end of the nut's stroke. Figure 1 A-A sectional view.

[0044] Figure 3 yes Figure 2 A magnified view of a portion of the image.

[0045] Figure 4 This is a three-dimensional diagram of the first example of a ball screw device.

[0046] Figure 5 This is a three-dimensional view of the nut that constitutes the ball screw device in the first example.

[0047] Figure 6 This is a front view of the drive components of the ball screw device that constitutes the first example, viewed from the opposite axial side.

[0048] Figure 7 yes Figure 6 A perspective view of the drive component shown.

[0049] Figure 8 The first example of the ball screw device is shown as a schematic diagram illustrating the axial and circumferential positional relationship between the non-rotating engagement portion and the rotating engagement groove portion near the end of the nut's stroke.

[0050] Figure 9 This is a front view of the drive component of the ball screw device constituting the second embodiment of the present invention, viewed from the other side of the axial direction.

[0051] Figure 10 This is a perspective view of the nut constituting the ball screw device in the second example, viewed from the axial side and radially outward.

[0052] Figure 11 The ball screw device in the second example is equivalent to Figure 8 The image.

[0053] Figure 12 This is a front view of the drive component of the ball screw device constituting the third embodiment of the present invention, viewed from the other side of the axial direction.

[0054] Figure 13 The ball screw device in the third example is equivalent to Figure 8 The image.

[0055] Figure 14 This is a perspective view of the nut of the ball screw device constituting the fourth embodiment of the present invention, viewed from the axial side and radially outward.

[0056] Figure 15 This is a front view of the drive component of the ball screw device constituting the fifth embodiment of the present invention, viewed from the other side of the axial direction.

[0057] Figure 16 yes Figure 15 A perspective view of the drive component shown.

[0058] Figure 17 yes Figure 15 Sectional view along the B-O-B line.

[0059] Figure 18 This is a front view of the drive component of the ball screw device constituting the sixth embodiment of the present invention, viewed from the other side of the axial direction.

[0060] Figure 19 yes Figure 18 A perspective view of the drive component shown.

[0061] Figure 20 This is a front view of the drive component of the ball screw device constituting the seventh embodiment of the present invention, viewed from the other side of the axial direction.

[0062] Figure 21 yes Figure 20 A perspective view of the drive component shown.

[0063] Figure 22 The ball screw device of the eighth embodiment of the present invention is equivalent to Figure 2 The image.

[0064] Figure 23 The ball screw device of the ninth embodiment of the present invention is equivalent to Figure 2 The image.

[0065] Figure 24 yes Figure 23 A magnified view of a portion of the image.

[0066] Figure 25This is a front view of the drive component of the ball screw device constituting the ninth example, viewed from the opposite axial side.

[0067] Figure 26 yes Figure 25 A cross-sectional view along the C-O-C line.

[0068] Figure 27 yes Figure 25 A perspective view of the drive component shown.

[0069] Figure 28 The ball screw device in the ninth example is equivalent to Figure 8 The image.

[0070] Figure 29 This is a front view of the drive component of the ball screw device constituting the tenth embodiment of the present invention, viewed from the other side of the axial direction.

[0071] Figure 30 The ball screw device in the tenth example is equivalent to Figure 8 The image.

[0072] Figure 31 The ball screw device of the eleventh embodiment of the present invention is equivalent to Figure 8 The image.

[0073] Figure 32 The ball screw device of the twelfth embodiment of the present invention is equivalent to Figure 2 The image.

[0074] Figure 33 The ball screw device of the thirteenth embodiment of the present invention is equivalent to Figure 2 The image.

[0075] Figure 34 The ball screw device of the fourteenth embodiment of the present invention is equivalent to Figure 2 The image.

[0076] Figure 35 This is a perspective view of an existing ball screw device. Detailed Implementation

[0077] [First example]

[0078] use Figures 1 to 8 The first example of an embodiment of the present invention will be described.

[0079] [Overall structure of the ball screw assembly]

[0080] In this example, the ball screw device 1 is installed in an electric brake booster for converting the rotary motion of the electric motor, which is the drive source, into linear motion, thereby actuating the piston of the hydraulic cylinder.

[0081] The ball screw assembly 1 includes a threaded shaft 2, a nut 3, multiple balls 4, and a drive component 5.

[0082] The threaded shaft 2 is a rotary motion element that is driven to rotate by a drive source (not shown) via a drive component 5. The threaded shaft 2 is inserted into the inside of the nut 3 and is coaxially arranged with the nut 3. The nut 3 is a linear motion element that is prevented from rotating relative to the threaded shaft 2 by an anti-rotation mechanism (not shown) and performs linear motion during use. Therefore, the ball screw device 1 in this example is used in a manner that the threaded shaft 2 is driven to rotate, causing the nut 3 to move linearly.

[0083] A helical load path 6 is provided between the outer circumferential surface of the threaded shaft 2 and the inner circumferential surface of the nut 3. Multiple balls 4 are rotatably arranged in the load path 6. When the threaded shaft 2 and the nut 3 are rotated relative to each other, the balls 4 that have reached the end of the load path 6 return to the beginning of the load path 6 through the circulation groove 7 formed on the inner circumferential surface of the nut 3. The structure of each component of the ball screw device 1 will be described below.

[0084] In the description of the embodiments of the present invention including this example, unless otherwise specified, axial, radial, and circumferential directions refer to the axial, radial, and circumferential directions related to the threaded shaft 2. Axial side refers to... Figures 2-5 The right side, the other side of the axis refers to Figures 2-5 The left side. In embodiments of the present invention, the limitation of the end of the stroke of the nut 3, which is a linear motion element on one side of the axial direction, is characterized. In addition, the circumferential direction side refers to the rotational direction of the threaded shaft 2 that causes the nut 3 to move linearly in one side of the axial direction.

[0085] <Threaded Shaft>

[0086] The threaded shaft 2 is made of metal and has a threaded portion 8 and a mating shaft portion 9 arranged adjacent to the threaded portion 8 on one axial side. The threaded portion 8 and the mating shaft portion 9 are coaxially arranged and constitute a single unit. The mating shaft portion 9 has a smaller outer diameter than the threaded portion 8.

[0087] The threaded portion 8 has a helical axial ball thread groove 10 on its outer peripheral surface. The axial ball thread groove 10 is formed by grinding (cutting) or rolling the outer peripheral surface of the threaded portion 8. In this example, there is one axial ball thread groove 10. The groove shape (groove bottom shape) of the cross-section of the axial ball thread groove 10 is a Gothic arch groove or a circular arc groove. In this example, the forming direction (winding direction) of the axial ball thread groove 10 is restricted to a direction in which the nut 3 moves linearly in the axial direction when the threaded shaft 2 rotates in the circumferential direction.

[0088] The mating shaft portion 9 has external spline teeth 11 covering its entire outer circumference. Therefore, the mating shaft portion 9 is a spline shaft portion. In the illustrated example, the external spline teeth 11 are involute spline teeth, but they can also be angular spline teeth.

[0089] The threaded shaft 2 is coaxially configured with the nut 3 when the threaded portion 8 is inserted into the inside of the nut 3. In this example, the threaded shaft 2 is composed of the threaded portion 8 and the fitting shaft portion 9. However, in the implementation of the present invention, the threaded shaft may also include a support shaft portion (second fitting shaft portion) for fixing a rolling bearing or the like that is rotatably supported relative to the housing or the like, a spline portion that functions as a torque transmission portion, a fine tooth portion, etc.

[0090] <Nut>

[0091] Nut 3 is made of metal and has an overall cylindrical shape. Nut 3 has a helical ball thread groove 12 and a circulation groove 7 on its inner circumferential surface.

[0092] The nut-side ball thread groove 12 has a helical shape and is formed by performing a machining process on the inner circumferential surface of the nut 3, such as grinding (cutting) or rolling tapping (cutting tapping). The nut-side ball thread groove 12 has the same lead as the shaft-side ball thread groove 10. Therefore, with the threaded portion 8 of the threaded shaft 2 inserted into the inner side of the nut 3, the shaft-side ball thread groove 10 and the nut-side ball thread groove 12 are arranged radially opposite each other, forming a helical load path 6. The number of nut-side ball thread grooves 12 is the same as that of the shaft-side ball thread groove 10, which is one. The groove shape of the cross-section of the nut-side ball thread groove 12 is also a Gothic arch groove or a circular arc groove, just like the shaft-side ball thread groove 10.

[0093] The circulation groove 7 has a generally S-shaped shape and is formed on the inner circumferential surface of the nut 3 by, for example, forging (cold forging). The circulation groove 7 smoothly connects the axially adjacent portions of the ball thread groove 12 on the nut side, connecting the start and end points of the load path 6. Therefore, the ball 4 that has reached the end point of the load path 6 returns to the start point of the load path 6 through the circulation groove 7. Furthermore, the start and end points of the load path 6 are changed according to the direction of the relative displacement (relative rotation direction) between the thread shaft 2 and the nut 3 in the axial direction.

[0094] The circulation groove 7 has a generally semi-circular cross-sectional shape. The circulation groove 7 has a groove width slightly larger than the diameter of the ball 4, and a groove depth in which the ball 4 moving in the circulation groove 7 can pass over the thread teeth of the axial ball thread groove 10.

[0095] The nut 3 has a protruding non-rotational engaging portion 13 at one end on the axial side. The non-rotational engaging portion 13 is provided on a circumferential portion of the side surface 3a on the axial side of the nut 3 and protrudes towards the axial side. The non-rotational engaging portion 13 has a fan-shaped structure.

[0096] The non-rotating engagement part 13 is located on the other side in the circumferential direction. Figure 4 and Figure 5 The side near the front, Figure 8 The left side of the nut 3 has a flat, non-rotational limiting surface 14. The non-rotational limiting surface 14 is arranged substantially parallel to the central axis of the nut 3. In addition, the front end face (the end face on one side of the axial direction) of the non-rotational engaging portion 13 exists on an imaginary plane orthogonal to the central axis of the nut 3.

[0097] The axial dimension of the non-rotational engagement portion 13 (non-rotational limiting surface 14) can be set, for example, to a size greater than or equal to the lead of the axial ball thread groove 10. The circumferential range of the non-rotational engagement portion 13 is appropriately determined within a range that prevents interference with the side surface 15a on the other axial side of the substrate portion 15 (described later) and can support the force applied to the non-rotational limiting surface 14 from the rotational limiting surface 22. That is, the circumferential range (central angle α) of the non-rotational engagement portion 13 can be smaller than the circumferential range (central angle θ) of the rotational engagement groove portion 18 (described later). Therefore, the relationship α < θ is satisfied. In this example, the non-rotational engagement portion 13 is formed in approximately 1 / 12 of the entire area of ​​the side surface 3a on one axial side.

[0098] In this example, the nut 3 is integrally formed with the non-rotational side engaging portion 13. However, in the case of implementing the present invention, the nut can also be formed by combining and fixing a cylindrical component with a nut-side ball thread groove and a circulation groove on the inner circumferential surface and the non-rotational side engaging portion.

[0099] In this example, the ball screw device 1 uses the nut 3 as a linear motion element. Therefore, in this example, the nut 3 is prevented from rotating by an anti-rotation mechanism (not shown). Various known structures can be used as the anti-rotation mechanism. For example, a structure in which a protrusion (key) provided on the inner circumferential surface of a fixed component such as a housing engages with a groove formed axially on the outer circumferential surface of the nut 3 can be used.

[0100] <ball bearing>

[0101] The ball 4 is a steel ball with a predetermined diameter, which is rotatably disposed in the load path 6 and the circulation groove 7. The ball 4 disposed in the load path 6 rolls while bearing a compressive load, while the ball 4 disposed in the circulation groove 7 is not subjected to a compressive load and is pushed by the subsequent ball 4 to roll.

[0102] <Drive Components>

[0103] The drive component 5 drives the threaded shaft 2 to rotate by transmitting torque input from a drive source such as an electric motor. In this example, the drive component 5 not only drives the threaded shaft 2 to rotate, but also limits the end of the stroke of the nut 3, which is a linear motion element.

[0104] In the ball screw assembly 1 of this example, when the drive component 5 is rotated in the circumferential direction, the nut 3 moves relative to the threaded shaft 2 in the axial direction. Conversely, when the drive component 5 is rotated in the other circumferential direction, the nut 3 moves relative to the threaded shaft 2 in the other axial direction.

[0105] The drive component 5 includes a base plate portion 15, a cylindrical portion 16, a torque input portion 17, and a rotation-side engaging groove portion 18. The drive component 5 is made of metal such as carbon steel or stainless steel, or of synthetic resin. For example, gears, pulleys, and sprockets can be used as the drive component 5.

[0106] The base plate portion 15 has a circular flat plate shape. The base plate portion 15 has a mounting hole 19 extending axially through its radial center. Internal spline teeth 20 are formed on the inner circumferential surface of the mounting hole 19. The base plate portion 15 is externally fixed relative to the fitting shaft portion 9 by spline engaging the internal spline teeth 20 formed on the inner circumferential surface of the mounting hole 19 with the external spline teeth 11 formed on the outer circumferential surface of the fitting shaft portion 9, preventing relative rotation. The radially inner portion of the side surface 15a on the other axial side of the base plate portion 15 abuts against or nearly faces the end face on one axial side of the threaded portion 8 constituting the threaded shaft 2.

[0107] The cylindrical portion 16 has a cylindrical shape and is provided at the radially outer end of the drive member 5. The axial end of the cylindrical portion 16 is connected to the radially outer end of the base plate portion 15. The cylindrical portion 16 has an inner diameter larger than the outer diameter of the nut 3. The cylindrical portion 16 covers the periphery of the axial end of the threaded portion 8.

[0108] The torque input section 17 is provided on the outer peripheral surface of the drive member 5. In this example, the torque input section 17 is provided on the outer peripheral surface of the cylindrical portion 16. Therefore, the torque input section 17 is arranged radially at a position overlapping with the threaded portion 8. In the illustrated example, the outer diameter of the portion of the cylindrical portion 16 where the torque input section 17 is provided is larger than the outer diameter of the portion that is axially separated from the torque input section 17. That is, the torque input section 17 is provided on the larger diameter portion of the cylindrical portion 16.

[0109] When a gear is used as the drive component 5, the torque input unit 17 is a toothed part; when a pulley is used as the drive component 5, the torque input unit 17 is a belt bearing surface (toothed part) on which the belt is mounted; and when a sprocket is used as the drive component 5, the torque input unit 17 is a toothed part on which the chain is mounted. In any case, torque from the drive source is input to the torque input unit 17.

[0110] The rotating-side engaging groove 18 allows the protruding non-rotating-side engaging portion 13 to be inserted axially, and it can also engage with the non-rotating-side engaging portion 13 circumferentially at its end on the other side. The rotating-side engaging groove 18 has an arcuate shape (C-shape) when viewed axially, and is located at the radial center of the side surface 15a on the other side of the axial direction of the base plate portion 15. The rotating-side engaging groove 18 is formed by performing processes such as machining or forging on the side surface 15a on the other side of the axial direction of the base plate portion 15.

[0111] The rotating side engaging groove 18 is a through groove that passes through the base plate 15 along the axial direction.

[0112] The rotating-side engaging groove 18 has a radial width dimension that allows the non-rotating-side engaging part 13 to be inserted axially. Therefore, the radially outer inner surface 21a of the rotating-side engaging groove 18 is a partially concave cylindrical surface centered on the central axis of the driving member 5, and has an inner diameter slightly larger than the diameter of the circumscribed circle passing through the outer peripheral surface of the non-rotating-side engaging part 13. Conversely, the radially inner inner surface 21b of the rotating-side engaging groove 18 is a partially convex cylindrical surface centered on the central axis of the driving member 5, and has an outer diameter slightly smaller than the diameter of the inscribed circle passing through the inner peripheral surface of the non-rotating-side engaging part 13. The radially outer inner surface 21a and the radially inner inner surface 21b of the rotating-side engaging groove 18 are arranged concentrically.

[0113] The rotating side engagement groove 18 has a flat rotating side limiting surface 22 facing the circumferential direction at its end on the other side of the circumferential direction. The rotating side limiting surface 22 contacts the non-rotating side limiting surface 14 when the nut 3 moves relative to the threaded shaft 2 in one direction of the axial direction and reaches the end of its stroke. Therefore, the rotating side limiting surface 22 exists on an imaginary plane containing the central axis of the drive member 5. Furthermore, the circumferential position (phase) of the rotating side limiting surface 22 can be specified when the drive member 5 is externally fixed to the engagement shaft 9 of the threaded shaft 2, and visually identifiable identification marks, recesses, holes, grooves, wrench opening shapes, etc., can be marked on the outer surface of the drive member 5 in such a way that visually identifiable identification shapes can be formed, such as recesses, holes, grooves, wrench opening shapes, etc.

[0114] The axial dimension of the rotation-side limiting surface 22 is the same as the axial thickness dimension of the base plate portion 15. The axial dimension of the rotation-side limiting surface 22 is set to ensure sufficient engagement amount (axial width of the contact portion with the non-rotation-side limiting surface 14) δ between it and the non-rotation-side engaging portion 13 to prevent rotation of the threaded shaft 2. In this example, the axial dimension of the rotation-side limiting surface 22 is larger than the axial dimension of the non-rotation-side engaging portion 13 (non-rotation-side limiting surface 14).

[0115] The rotating side engaging groove 18 has a flat, stepped surface 23 facing the circumferential direction at one end.

[0116] In this example, such as Figure 6 and Figure 7 As shown, the central angle θ of the rotating side engagement groove 18 is approximately 180 degrees. Therefore, the rotating side engagement groove 18 is formed over half the entire area of ​​the substrate portion 15.

[0117] The circumferential range (center angle θ) of the rotating-side engaging groove 18 is related to the engagement amount δ of the non-rotating-side limiting surface 14 and the rotating-side limiting surface 22. For example, if the center angle θ of the rotating-side engaging groove 18 is increased, the engagement amount δ tends to increase; if the center angle θ of the rotating-side engaging groove 18 is decreased, the engagement amount δ tends to decrease. However, if the center angle θ of the rotating-side engaging groove 18 is too large, the axial clearance between the side surface 3a of the nut 3 on one axial side and the side surface 15a of the drive component 5 on the other axial side, when the nut 3 reaches the end of its stroke on one axial side and the non-rotating-side limiting surface 14 and the rotating-side limiting surface 22 are engaged, becomes smaller, and interference between the nut 3 and the drive component 5 is likely to occur. Therefore, the center angle θ of the rotating-side engaging groove 18 needs to be set to a size that ensures the minimum engagement amount δ required to prevent the rotation of the threaded shaft 2, and also prevents interference between the nut 3 and the drive component 5.

[0118] Specifically, in order to prevent the rotation of the threaded shaft 2, it is preferable to ensure that the engagement amount δ is at least 1 / 10 (10%) of the lead of the shaft-side ball thread groove 10. Therefore, the lower limit of the center angle θ of the rotating side engagement groove 18 can be set to 36 degrees.

[0119] On the other hand, to prevent interference between the nut 3 and the drive component 5, it is preferable to ensure that the axial clearance between the side surface 3a on one axial side of the nut 3 and the side surface 15a on the other axial side of the base plate portion 15, when the non-rotational side limiting surface 14 and the rotational side limiting surface 22 are engaged, is at least 1 / 10 (10%) of the lead of the axial ball thread groove 10. Therefore, the upper limit of the center angle θ of the rotational side engaging groove portion 18 can be set to 324 degrees. When the center angle θ of the rotational side engaging groove portion 18 is set to 324 degrees, the engagement amount δ can be ensured to a maximum of 9 / 10 (90%) of the lead of the axial ball thread groove 10.

[0120] As mentioned above, the center angle θ of the rotating side engaging groove 18 can be set in the range of 36 degrees or more and 324 degrees or less.

[0121] Furthermore, to ensure the strength of the drive component 5, the size (360-θ) of the central angle of the portion of the base plate portion 15 that separates from the rotating side engaging groove portion 18 in the circumferential direction is ensured to be at a certain level. In this example, the central angle (360-θ) of the portion that separates from the rotating side engaging groove portion 18 in the circumferential direction is made larger than the central angle (α) of the non-rotating side engaging portion 13. That is, the relationship 360-θ > α is satisfied. Therefore, in this example, the central angle α of the non-rotating side engaging portion 13 and the central angle θ of the rotating side engaging groove portion 18 satisfy the relationship α < θ < 360-α.

[0122] <Instructions for the Operation of the Ball Screw Mechanism>

[0123] In this example, the ball screw device 1 uses a drive source (not shown) to rotate the threaded shaft 2 via the drive member 5, thereby causing the nut 3 to move linearly. Specifically, in this example, when the drive member 5 (threaded shaft 2) is rotated in the circumferential direction via the torque input section 17 provided on the drive member 5, the nut 3 moves relative to the threaded shaft 2 in the axial direction. Conversely, when the drive member 5 (threaded shaft 2) is rotated in the opposite circumferential direction via the torque input section 17, the nut 3 moves relative to the threaded shaft 2 in the opposite axial direction.

[0124] When nut 3 moves relative to threaded shaft 2 in one axial direction and approaches the end of its stroke, as Figure 8 As shown in (A), the axial end (front end) of the non-rotating engagement portion 13 enters the inner side of the rotating engagement groove 18 provided in the drive member 5. Specifically, the axial end of the non-rotating engagement portion 13 enters the circumferential portion of the rotating engagement groove 18.

[0125] When the drive component 5 is further rotated in the circumferential direction, the nut 3 moves axially by an amount corresponding to the lead of the axial ball thread groove 10. Therefore, the non-rotating engagement portion 13 moves axially as indicated by the black arrow, thereby increasing the axial insertion amount relative to the rotating engagement groove 18, and moves relative to the rotating engagement groove 18 from one side of the circumferential direction to the other side, as indicated by the hollow arrow. As a result, the non-rotating engagement portion 13... Figure 8 The sequence A-B-C moves relative to the other side in the circumferential direction from the inside of the rotating side engaging groove 18.

[0126] When the nut 3 reaches the end of its stroke on one side of the axial direction, the end of the non-rotating engagement portion 13 on the other side of the circumferential direction of the rotating engagement groove portion 18 engages with the rotating engagement groove portion 18 in the circumferential direction. Specifically, as Figure 8 As shown in state (C), the non-rotational side limiting surface 14, which is provided on the side of the non-rotational side engaging portion 13 in the circumferential direction, and the rotational side limiting surface 22, which is provided at the end of the rotational side engaging groove portion 18 in the circumferential direction, engage in the circumferential direction. In this example, the non-rotational side limiting surface 14 and the rotational side limiting surface 22 are in surface contact. As a result, rotation of the threaded shaft 2 is prevented.

[0127] Furthermore, when the drive component 5 is rotated from the circumferentially engaged state of the non-rotational side limiting surface 14 and the rotational side limiting surface 22 to the other side in the circumferential direction, the non-rotational side engaging portion 13 follows... Figure 8 The sequence C-B-A moves relative to each other in the circumferential direction on the inner side of the rotating side engaging groove 18 and in the axial direction on the other side. Then, the non-rotating side engaging part 13 does not contact the stepped surface 23 of the rotating side engaging groove 18 and disengages from the end of the rotating side engaging groove 18 on the circumferential direction to the outer side of the rotating side engaging groove 18.

[0128] As described above, according to the ball screw device 1 of this example, the drive component 5 can be used to limit the end of the stroke related to the relative axial movement of the nut 3 relative to the threaded shaft 2 to one side. Furthermore, the end of the stroke related to the relative axial movement of the nut 3 relative to the threaded shaft 2 to the other side can be limited using various known stroke limiting mechanisms.

[0129] According to the ball screw device 1 in this example, the stroke end limit of the nut 3, which is a linear motion element, can be achieved with fewer parts, thus enabling the miniaturization of the ball screw device 1 and improving controllability.

[0130] That is, in this example, the drive component 5 can not only rotate the drive threaded shaft 2, but also limit the end of the stroke related to the relative axial movement of the nut 3 relative to the threaded shaft 2. Therefore, it is unnecessary to use a dedicated component (limiting member) for limiting the end of the nut's stroke, as is done in the existing structure described in Japanese Patent Application Publication No. 2016-70281. Therefore, the ball screw device 1 according to this example can reduce the number of parts. In addition, by omitting the dedicated component for limiting the end of the stroke, the axial dimension of the threaded shaft 2 can be shortened, and therefore the axial dimension of the ball screw device 1 can be shortened. Therefore, miniaturization of the ball screw device 1 can be achieved.

[0131] In this example, the non-rotational side limiting surface 14 of the non-rotational side engaging portion 13 and the rotational side limiting surface 22 of the rotational side engaging groove 18 of the drive member 5 can be engaged in the circumferential direction while the non-rotational side engaging portion 13 of the nut 3 is axially inserted into the inner side of the rotational side engaging groove 18. Therefore, it is possible to ensure the stroke of the nut 3 and to achieve miniaturization of the ball screw device 1.

[0132] In this example, to limit the end of the stroke of the nut 3, the non-rotating engagement portion 13 of the nut 3 and the rotating-side limiting surface 22 of the rotating-side engagement groove 18 of the drive member 5 are engaged in the circumferential direction. Therefore, when the non-rotating engagement portion 13 of the nut 3 and the rotating-side limiting surface 22 of the drive member 5 are engaged in the circumferential direction, the rotation of the drive member 5 can be stopped immediately. Thus, it is possible to suppress the deviation of the rotation stop position of the drive member 5 from its initial position. As a result, the axial position (stroke amount) of the nut 3 can be strictly managed, and the controllability of the ball screw device 1 can be improved.

[0133] Furthermore, by making the rotating side engaging groove 18 a through groove that passes through the base plate 15 in the axial direction, the drive component 5 can be made lighter compared to the case where the rotating side engaging groove is a bottom groove.

[0134] Furthermore, the torque input portion 17, which is located on the outer peripheral surface of the cylindrical portion 16 constituting the drive component 5, is arranged radially at a position overlapping with the threaded portion 8. Therefore, it is advantageous in terms of shortening the axial dimension of the ball screw device 1.

[0135] In this example, the torque input section 17 is radially positioned to overlap with the portion of the rotating-side limiting surface 22 that abuts against the non-rotating-side limiting surface 14 on the opposite axial side. In other words, as... Figure 3As shown, in the axial direction, within the range R where the torque input section 17 exists, there is a portion of the rotating side limiting surface 22 that abuts against the non-rotating side limiting surface 14. Therefore, from this perspective, the axial dimension of the ball screw assembly 1 can also be shortened. Furthermore, it is possible to prevent the application of impact-based torque loads from the torque input section 17 to the drive source side, which are generated by the collision between the non-rotating side limiting surface 14 and the rotating side limiting surface 22.

[0136] [Second Example]

[0137] use Figures 9-11 A second example of an embodiment of the present invention will be described.

[0138] In this example, the center angle θ of the rotating side engagement groove 18a constituting the drive member 5a is smaller than that in the first example. Specifically, the center angle θ of the rotating side engagement groove 18a is set to a lower limit of 36 degrees.

[0139] In addition, when the center angle θ of the rotating side engagement groove 18a is set to 36 degrees, in order to ensure that the engagement amount δ between the non-rotating side limiting surface 14 and the rotating side limiting surface 22 is 1 / 10 (10%) of the lead of the axial ball thread groove 10, the shape of the front end face (the end face on one side of the axial direction) of the non-rotating side engagement part 13a is improved.

[0140] That is, a flat inclined surface (chamfer) 24 is formed on the front end face of the non-rotational engaging portion 13a, which is inclined relative to an imaginary plane orthogonal to the central axis of the nut 3. Specifically, the entire front end face of the non-rotational engaging portion 13a is formed with an inclined surface 24 that is inclined in a direction that recedes towards the axial direction as it moves towards the circumferential direction. The inclination angle of the inclined surface 24 can be greater than or equal to the lead angle β of the axial ball thread groove 10. In the illustrated example, it is set to an angle slightly larger than the lead angle β of the axial ball thread groove 10.

[0141] In this example, when the nut 3 moves relative to the threaded shaft 2 in one axial direction and approaches the end of its stroke, as... Figure 11 As shown by the dashed line, the axial end (front end) of the non-rotational engaging portion 13a enters the inner side of the rotational engaging groove 18a. Specifically, the axial end of the non-rotational engaging portion 13a enters the circumferential portion of the rotational engaging groove 18a. In this example, an inclined surface 24 is formed on the front end face of the non-rotational engaging portion 13a. Therefore, the front end face of the non-rotational engaging portion 13a and the axial side surface 15a of the substrate portion 15 do not interfere with each other, and the circumferential end of the axial end of the non-rotational engaging portion 13a enters the circumferential portion of the rotational engaging groove 18a.

[0142] When the drive component 5a is rotated further in the circumferential direction, the non-rotating engagement portion 13a increases the axial entry amount relative to the rotating engagement groove portion 18a, and moves relative to the rotating engagement groove portion 18a from one side in the circumferential direction to the other side in the circumferential direction.

[0143] When the nut 3 reaches the end of its stroke on one side of the axial direction, the end of the non-rotating engagement portion 13a on the other side of the circumferential direction of the rotating engagement groove portion 18a engages with the rotating engagement groove portion 18a in the circumferential direction. Specifically, as Figure 11 As shown by the solid line, the non-rotational limiting surface 14, which is located on the side of the non-rotational engaging portion 13a in the circumferential direction, and the rotational limiting surface 22, which is located on the end of the rotating engaging groove portion 18a in the circumferential direction, engage in the circumferential direction. As a result, rotation of the threaded shaft 2 is prevented.

[0144] In this example, the engagement amount δ when the non-rotational side limiting surface 14 and the rotational side limiting surface 22 engage in the circumferential direction is 1 / 10 of the lead of the axial ball thread groove 10.

[0145] Furthermore, in this example, the central angle θ of the rotating side engagement groove 18a is smaller than that of the first example. Therefore, the rotation amount of the drive member 5a that enters the inner side of the rotating side engagement groove 18a from the axial end of the non-rotating side engagement part 13a and engages with the non-rotating side limiting surface 14 and the rotating side limiting surface 22 in the circumferential direction is smaller than that of the first example.

[0146] In this example, by forming an inclined surface 24 on the front end face of the non-rotational engagement portion 13a, interference between the front end face of the non-rotational engagement portion 13a and the side surface 15a on the other axial side of the base plate portion 15 can be prevented. Therefore, when the center angle θ of the rotational engagement groove portion 18a is set to 36 degrees, it can be ensured that the engagement amount δ is 1 / 10 of the lead of the axial ball thread groove 10. Therefore, the reduction in strength of the drive member 5a caused by the formation of the rotational engagement groove portion 18a can be suppressed, and the rotation of the threaded shaft 2 can be prevented. Furthermore, in the implementation of the present invention, the inclined surface formed on the front end face of the non-rotational engagement portion is not limited to a flat surface, but can also be configured as a convex curved surface or a concave curved surface.

[0147] The other structures and effects of the second example are the same as those of the first example.

[0148] [Third Case]

[0149] use Figures 12-13 A third example of an embodiment of the present invention will be described.

[0150] In this example, the center angle θ of the rotating side engagement groove 18b constituting the drive member 5b is made larger than that in the first example. Specifically, the center angle θ of the rotating side engagement groove 18b is set to an upper limit of 324 degrees.

[0151] Therefore, in the substrate portion 15, the portion located radially inner to the rotating side engagement groove portion 18b and the portion located radially outer to the rotating side engagement groove portion 18b are connected via a connecting portion 25 located in the discontinuity of the rotating side engagement groove portion 18b and having a central angle of 36 degrees.

[0152] In this example, to ensure that the engagement amount δ is 9 / 10 (90%) of the lead of the axial ball thread groove 10, and to ensure that the axial clearance C between the axial side surface 3a of the nut 3 and the axial side surface 15a of the base plate 15 is 1 / 10 (10%) or more of the lead of the axial ball thread groove 10, the center angle θ of the rotating side engagement groove 18b is set to 324 degrees, and the axial dimension of the non-rotating side engagement part 13b is set to be the same as the lead of the axial ball thread groove 10. Furthermore, a flat inclined surface 24 is formed on the front end face of the non-rotating side engagement part 13b, which is inclined relative to an imaginary plane orthogonal to the central axis of the nut 3. Specifically, similar to the construction in the second example, an inclined surface 24 is formed on the front end face of the non-rotating side engagement part 13b, which is inclined in a direction that recedes towards the axial direction from the circumferential direction. The tilt angle of the inclined surface 24 can be set to be greater than or equal to the lead angle β of the axial ball thread groove 10. In the example shown, it is set to an angle slightly larger than the lead angle β of the axial ball thread groove 10.

[0153] In this example, when nut 3 moves relative to threaded shaft 2 in one axial direction and approaches the end of its stroke, as... Figure 13 As shown by the dashed line, the axial end (front end) of the non-rotational engaging portion 13b enters the inner side of the rotational engaging groove 18b. Specifically, the axial end of the non-rotational engaging portion 13b enters the circumferential portion of the rotational engaging groove 18b. In this example, an inclined surface 24 is formed on the front end face of the non-rotational engaging portion 13b, so the front end face of the non-rotational engaging portion 13b and the axial side surface 15a of the substrate portion 15 do not interfere with each other, and the circumferential end of the axial end of the non-rotational engaging portion 13b enters the circumferential portion of the rotational engaging groove 18b.

[0154] When the drive component 5b is rotated further in the circumferential direction, the non-rotating engagement portion 13b increases the axial entry amount relative to the rotating engagement groove portion 18b, and moves relative to the rotating engagement groove portion 18b from one side in the circumferential direction to the other side in the circumferential direction.

[0155] When the nut 3 reaches the end of its stroke on one side of the axial direction, the non-rotating engagement portion 13b engages circumferentially with the rotating engagement groove portion 18b at the end on the other side of the circumferential direction. Specifically, as... Figure 13 As shown by the solid line, the non-rotational limiting surface 14, which is located on the side of the non-rotational engaging portion 13b on the other side in the circumferential direction, and the rotational limiting surface 22, which is located on the end of the rotational engaging groove portion 18b on the other side in the circumferential direction, engage in the circumferential direction. As a result, rotation of the threaded shaft 2 is prevented.

[0156] In this example, the engagement amount δ of the non-rotational side limiting surface 14 and the rotational side limiting surface 22 when engaged in the circumferential direction is 9 / 10 of the lead of the axial ball thread groove 10. Furthermore, the axial clearance C between the nut 3 and the drive member 5b is 1 / 10 of the lead of the axial ball thread groove 10. Additionally, in this example, the central angle θ of the rotational side engaging groove 18b is larger than in the first example. Therefore, the axial end of the non-rotational side engaging portion 13b enters the inner side of the rotational side engaging groove 18b until the rotation amount of the drive member 5b, where the non-rotational side limiting surface 14 and the rotational side limiting surface 22 are engaged in the circumferential direction, is greater than in the first example.

[0157] In this example, the engagement amount δ can be ensured to be 9 / 10 of the lead of the axial ball thread groove 10, thus effectively preventing the rotation of the threaded shaft 2. Furthermore, the axial clearance C between the nut 3 and the drive component 5b can be ensured to be 1 / 10 of the lead of the axial ball thread groove 10, thus preventing interference between the nut 3 and the drive component 5b. Additionally, the stroke of the nut 3 can also be ensured.

[0158] The other structures and effects of the third example are the same as those of the first example.

[0159] [Fourth Case]

[0160] use Figure 14 A fourth example of an embodiment of the present invention will be described.

[0161] In this example, an inclined surface 24a is formed on the front end face of the non-rotating engagement portion 13c, extending from the middle of the circumferential direction to the end on one side of the circumferential direction, excluding the circumferential direction. Therefore, the end on the other side of the circumferential direction of the front end face of the non-rotating engagement portion 13c exists on an imaginary plane orthogonal to the central axis of the nut 3. The inclination angle of the inclined surface 24a can be set to be greater than or equal to the lead angle β of the axial ball thread groove 10.

[0162] Compared to the first example where the front end face of the rotating side engagement part is set as a flat surface existing on an imaginary plane orthogonal to the central axis of the nut, in this example, to prevent contact with the drive component 5 (see reference 5) Figure 2 Interference from (etc.), and ensure that the magnitude of the engagement quantity δ is advantageous.

[0163] The other structures and effects of the fourth example are the same as those of the first example.

[0164] [Fifth Case]

[0165] use Figures 15-17 A fifth example of an embodiment of the present invention will be described.

[0166] This example is a variation of the third example. In this example, the drive component 5c has a reinforcing part 26 in the middle of the circumferential direction of the rotating side engaging groove 18b (the central part in the illustrated example), which connects the radially outer inner surface 21a and the radially inner inner surface 21b radially. The reinforcing part 26 connects the axial end of the radially outer inner surface 21a and the axial end of the radially inner inner surface 21b. Viewed axially, the reinforcing part 26 has a fan shape.

[0167] The circumferential position and thickness of the reinforcing portion 26 are limited to prevent interference with the non-rotating side engaging portion 13 that enters the inner side of the rotating side engaging groove portion 18b. In the illustrated example, the thickness of the reinforcing portion 26 is approximately one-quarter of the thickness of the substrate portion 15. Furthermore, in implementing the present invention, the reinforcing portion can also be provided at multiple locations in the circumferential direction of the rotating side engaging groove portion.

[0168] In this example, the reinforcing portion 26 is integrally formed with the substrate portion 15. However, in implementing the present invention, the reinforcing portion and the substrate portion can also be integrally formed and fixed relative to the substrate portion. For example, the radially outer end and the radially inner end of the reinforcing portion can be fixed relative to the radially outer inner surface and the radially inner inner surface of the rotating side engaging groove portion by bonding or welding.

[0169] In this example, in the base plate portion 15, the portion located radially inner to the rotating side engagement groove portion 18b and the portion located radially outer to the rotating side engagement groove portion 18b are connected not only by the connecting portion 25 but also by the reinforcing portion 26. Therefore, the rigidity of the portion surrounding the mounting hole 19 located radially inner to the rotating side engagement groove portion 18b in the base plate portion 15 can be improved. Therefore, even when the central angle θ of the rotating side engagement groove portion 18b formed in the base plate portion 15 is large, the rigidity (torsional rigidity) of the internal spline teeth 20 formed on the inner circumferential surface of the mounting hole 19 can be ensured. Therefore, a large torque can be transmitted to the threaded shaft 2 using the drive member 5c.

[0170] The other structures and effects of the fifth example are the same as those of the first and third examples.

[0171] [Sixth Case]

[0172] use Figures 18-19 A sixth example of an embodiment of the present invention will be described.

[0173] The drive member 5d in this example differs in construction from that in the first to fifth examples, with two rotating-side engaging grooves 18c formed on the substrate portion 15. In this example, the central angle θ of each of the two rotating-side engaging grooves 18c is set to 150 degrees. Furthermore, the two rotating-side engaging grooves 18c are arranged at equal intervals along the circumferential direction of the drive member 5d. Therefore, the central angle of the portion existing between the two rotating-side engaging grooves 18c is the same (30 degrees). Additionally, the diameters of the radially outer inner surface 21a and the radially inner inner surface 21b of the two rotating-side engaging grooves 18c are the same. However, in implementing the present invention, for multiple rotating-side engaging grooves, the centers can be different, and the diameters of the radially outer inner surface and the radially inner inner surface can also be different.

[0174] The two rotating-side engaging grooves 18c each have a rotating-side limiting surface 22 at their ends on the opposite side in the circumferential direction. In the illustrated example, the two rotating-side limiting surfaces 22 exist on the same imaginary plane containing the central axis of the driving member 5d.

[0175] In this example, the drive component 5d described above is constructed similarly to that in the first to fifth examples, and the nut 3 (see reference) has only one non-rotating side engagement portion 13 (13a to 13c). Figure 5 (etc.) can be used in combination.

[0176] In this example, the drive component 5d has two rotating-side engaging grooves 18c. Therefore, during the assembly of the ball screw assembly 1, only one rotating-side engaging groove 18c needs to be aligned with the non-rotating-side engaging part 13. Thus, compared to a structure with only one rotating-side engaging groove, the assembly process is simplified. Furthermore, the two rotating-side engaging grooves 18c are evenly spaced along the circumference of the drive component 5d, ensuring good rotational balance.

[0177] As a variation of this example, a drive member 5d having two rotating-side engaging slots 18c and a nut having the same number of non-rotating-side engaging slots as the rotating-side engaging slots 18c can also be used together. In this case, by simultaneously engaging the two rotating-side engaging slots 18c and the two non-rotating-side engaging slots in the circumferential direction, the end of the nut's stroke is limited. Therefore, the force acting on each rotating-side engaging slot 18c can be reduced, and damage to the drive member 5d can be effectively prevented.

[0178] The other structures and effects of the sixth example are the same as those of the first example.

[0179] [Seventh Case]

[0180] use Figure 20 and Figure 21 A seventh example of an embodiment of the present invention will be described.

[0181] In this example, the drive member 5e has three rotating-side engaging grooves 18d formed on the substrate portion 15. In this example, the central angle θ of each of the three rotating-side engaging grooves 18d is 95 degrees. Furthermore, the three rotating-side engaging grooves 18d are arranged at equal intervals along the circumferential direction of the drive member 5e. Therefore, the central angle of the portion existing between two adjacent rotating-side engaging grooves 18d in the circumferential direction is the same (25 degrees). Additionally, the diameters of the radially outer inner surface 21a and the radially inner inner surface 21b of the three rotating-side engaging grooves 18d are the same.

[0182] The three rotating side engaging grooves 18d each have a rotating side limiting surface 22 at the end of the other side in the circumferential direction.

[0183] In this example, compared to a structure with only one rotating side engaging groove, the assembly process can be simplified. Furthermore, by arranging three rotating side engaging grooves 18d at equal intervals along the circumference of the drive member 5e, good rotational balance of the drive member 5e can be achieved.

[0184] Similar to the sixth example, the drive component 5e in this example can also be used in combination with a nut 3 that has only one non-rotating side engagement portion 13 (13a to 13c), or in combination with a nut that has the same number of non-rotating side engagement portions as the rotating side engagement slot portion 18.

[0185] The other structures and effects of the seventh case are the same as those of the first and sixth cases.

[0186] [Case 8]

[0187] use Figure 22 The eighth embodiment of the present invention will be described.

[0188] In this example, unlike the first to seventh examples, the rotating side engaging groove 18e constituting the drive member 5f is provided as a bottomed groove (recess) with an opening on the side 15a on the axial side of the base plate 15 and a constant axial depth (groove depth) throughout the circumferential direction. Therefore, the bottom surface 27 of the rotating side engaging groove 18e exists on an imaginary plane orthogonal to the central axis of the drive member 5f.

[0189] The axial dimension of the rotating side limiting surface 22, which corresponds to the axial depth of the rotating side engaging groove 18e, is set to ensure an engagement amount δ that sufficiently prevents the rotation of the threaded shaft 2 between it and the non-rotating side limiting surface 14 of the non-rotating side engaging portion 13. In this example, the axial dimension of the rotating side limiting surface 22 is greater than the axial dimension of the non-rotating side engaging portion 13 (non-rotating side limiting surface 14).

[0190] In this example, the rotating side engagement groove 18e is a bottomed groove. Therefore, compared with the case where the rotating side engagement groove is a through groove, the reduction in strength of the drive component 5f caused by the formation of the rotating side engagement groove can be suppressed.

[0191] Furthermore, in this example, the rotation-side engaging groove 18e is formed in the radial middle portion of the side surface 15a on the axial side of the substrate portion 15. Therefore, an outer diameter side cylinder portion 29, protruding to the axial side of the groove bottom surface 27 of the rotation-side engaging groove 18e, is formed in the substrate portion 15 at a radially outer portion. Additionally, an inner diameter side cylinder portion 30, protruding to the axial side of the groove bottom surface 27 of the rotation-side engaging groove 18e, is formed in the substrate portion 15 at a radially inner portion. Moreover, in this example, the rotation-side limiting surface 22 is connected to both the outer diameter side cylinder portion 29 and the inner diameter side cylinder portion 30. Therefore, the rigidity of the rotation-side limiting surface 22 can be improved. Furthermore, in implementing the present invention, if the rotation-side limiting surface is connected to at least one of the outer diameter side cylinder portion and the inner diameter side cylinder portion, the rigidity of the rotation-side limiting surface can be improved.

[0192] The other structures and effects of the eighth example are the same as those of the first example.

[0193] [Ninth Case]

[0194] use Figures 23-28 The ninth example of an embodiment of the present invention will be described.

[0195] In this example, unlike the first to eighth examples, the rotating side engaging groove 18f constituting the drive member 5g is provided as a bottomed groove (recess) with an opening on the side 15a on the other side of the axial direction of the base plate 15 and an axial depth (groove depth) varying along the circumferential direction.

[0196] Specifically, the axial depth of the rotating-side engagement groove 18f increases (deeperses) as it moves from one side of the circumferential direction toward the other. Therefore, the groove bottom surface 27a of the rotating-side engagement groove 18f is inclined relative to an imaginary plane orthogonal to the central axis of the drive member 5g. In this example, the groove bottom surface 27a is inclined at an angle α1 (α1 = β1) with the same lead angle β1 as the axial ball thread groove 10 (and the nut-side ball thread groove 12) in the direction from the imaginary plane orthogonal to the central axis of the drive member 5g toward the axial direction as it moves toward the other side of the circumferential direction.

[0197] The rotating-side engaging groove 18f has a radial width dimension that allows the non-rotating-side engaging part 13, which is fitted to the nut 3, to be inserted axially. Therefore, the radially outer inner surface 21a of the rotating-side engaging groove 18f has an inner diameter slightly larger than the diameter of the circumscribed circle passing through the outer circumferential surface of the non-rotating-side engaging part 13. Conversely, the radially inner inner surface 21b of the rotating-side engaging groove 18f has an outer diameter slightly smaller than the diameter of the inscribed circle passing through the inner circumferential surface of the non-rotating-side engaging part 13. The radially outer inner surface 21a and the radially inner inner surface 21b of the rotating-side engaging groove 18f are arranged concentrically.

[0198] The rotating-side engaging groove 18f has a flat rotating-side limiting surface 22 facing the circumferential direction at its end on the side with the greatest axial depth. Therefore, the end of the groove bottom surface 27a of the rotating-side engaging groove 18f on the other side in the circumferential direction is connected to the side surface 15a of the base plate 15 on the other side in the axial direction via the rotating-side limiting surface 22. The rotating-side limiting surface 22 contacts the non-rotating-side limiting surface 14 when the nut 3 has moved relative to the threaded shaft 2 in the axial direction and reached the end of its stroke. Therefore, the rotating-side limiting surface 22 is arranged approximately parallel to the central axis of the drive member 5g. The axial dimension of the rotating-side limiting surface 22 is set to a size δ that ensures sufficient engagement (axial width of the contact portion with the non-rotating-side limiting surface 14) between it and the non-rotating-side limiting surface 14 of the non-rotating-side engaging part 13 of the nut 3 to prevent rotation of the threaded shaft 2. In this example, the axial dimension of the rotating side limiting surface 22 is approximately the same as the axial dimension of the non-rotating side engaging portion 13 (non-rotating side limiting surface 14), which is about 2 / 5 of the axial thickness dimension of the base plate portion 15 (for example, about 3.5 mm in the case of a ball screw device with an electric brake booster).

[0199] The rotating-side engaging groove 18f has a flat, stepped surface 23 facing the circumferential direction at its end on the side with the smallest axial depth. Therefore, the end of the bottom surface 27a of the rotating-side engaging groove 18f on the circumferential direction is connected to the side surface 15a of the base plate 15 on the other axial direction via the stepped surface 23. In the illustrated example, the axial dimension of the stepped surface 23 is approximately 1 / 4 of the rotating-side limiting surface 22 (for example, approximately 1.0 mm in the case of a ball screw device incorporating an electric brake booster). In implementing the present invention, the stepped surface can be omitted. In this case, the end of the bottom surface of the rotating-side engaging groove on the circumferential direction and the side surface of the drive member on the other axial direction can be smoothly connected without the stepped surface.

[0200] In this example, such as Figure 25 As shown, the center angle θ of the rotating side engagement groove 18f is approximately 300 degrees. Therefore, the rotating side engagement groove 18f is formed over a 5 / 6 extent of the entire side surface 15a on the axial side of the substrate portion 15. The circumferential range (center angle θ) of the rotating side engagement groove 18f is determined based on the magnitude of the lead angle β1 of the axial ball thread groove 10 and the magnitude of the engagement amount δ between the non-rotating side limiting surface 14 and the rotating side limiting surface 22.

[0201] In this example, when the nut 3 moves relative to the threaded shaft 2 towards one axial direction and approaches the end of its stroke, the axial end (front end) of the non-rotating engagement portion 13 enters the inner side of the rotating engagement groove 18f equipped on the drive member 5g. By moving further axially, the amount of entry relative to the axial direction of the rotating engagement groove 18f increases, and the nut 3 moves relative to the rotating engagement groove 18f from one circumferential direction to the other. In this example, the inclination angle α1 of the groove bottom surface 27a of the rotating engagement groove 18f is set to the same size as the lead angle β1 of the axial ball thread groove 10. Therefore, while maintaining a constant gap 28 between the axial end face of the non-rotating engagement portion 13 and the groove bottom surface 27a, the non-rotating engagement portion 13... Figure 28 The sequence A-B-C moves relative to each other in the circumferential direction from the inner side of the rotating side engaging groove 18f. When the nut 3 reaches the end of its stroke on one axial side, the end of the non-rotating side engaging part 13 on the other circumferential direction of the rotating side engaging groove 18f engages with the rotating side engaging groove 18f in the circumferential direction. In this example, even when the non-rotating side limiting surface 14 and the rotating side limiting surface 22 are in contact, a gap 28 exists between the end face of the non-rotating side engaging part 13 on one axial side and the groove bottom surface 27a.

[0202] In this example, when the drive component 5g is rotated to the other side in the circumferential direction, the non-rotating engagement part 13, while maintaining a gap 28 between its end face on one side of the axial direction and the bottom surface 27a of the groove, proceeds according to... Figure 28 The sequence C-B-A in the rotating side engagement groove 18f moves relative to each other in the circumferential direction and axial direction. Then, the non-rotating side engagement part 13 does not contact the step surface 23 and disengages from the end of the rotating side engagement groove 18f in the circumferential direction to the outside of the rotating side engagement groove 18f.

[0203] In this example, the rotating side engagement groove 18f is a bottomed groove. Therefore, compared with the case where the rotating side engagement groove is a through groove, the reduction in strength of the drive component 5g caused by the formation of the rotating side engagement groove can be suppressed.

[0204] In this example, the axial depth of the rotating engagement groove 18f increases from one side in the circumferential direction to the other. Therefore, compared to the case where the axial depth of the rotating engagement groove 18f is constant throughout the circumferential direction as in the eighth example, the amount of machining required for the rotating engagement groove 18f can be reduced. This reduces the machining time of the drive component 5g, thereby lowering manufacturing costs. Furthermore, compared to the case where the axial depth of the rotating engagement groove 18f is constant throughout the circumferential direction, the axial thickness of the substrate portion 15 constituting the drive component 5g can be ensured in the portion where the rotating engagement groove 18f is formed, excluding the end on the other side in the circumferential direction. Therefore, the rigidity and strength of the drive component 5g can be ensured.

[0205] Furthermore, by setting the inclination angle α1 of the groove bottom surface 27a of the rotating side engaging groove 18f to the same size as the lead angle β1 of the axial ball thread groove 10, the non-rotating side engaging part 13 can move relative to the rotating side engaging groove 18f in the circumferential direction while maintaining a constant gap 28 between the axial end face of the non-rotating side engaging part 13 and the groove bottom surface 27a. Therefore, interference between the axial end face of the non-rotating side engaging part 13 and the groove bottom surface 27a can be prevented. Thus, by preventing interference between the axial end face of the non-rotating side engaging part 13 and the groove bottom surface 27a before the non-rotating side limiting surface 14 and the rotating side limiting surface 22 engage in the circumferential direction, positional displacement at the end of the stroke of the nut 3 can be prevented.

[0206] In this example, the rotation-side engaging groove 18f is also formed in the radial middle portion of the side surface 15a on the other axial side of the base plate portion 15. That is, in this example, the rotation-side limiting surface 22 is connected to the partially cylindrical outer diameter side cylinder portion 29 and the partially cylindrical inner diameter side cylinder portion 30. The outer diameter side cylinder portion 29 is formed in the base plate portion 15 in a radially outer portion than the rotation-side engaging groove 18f and protrudes to the other axial side than the groove bottom surface 27a. The inner diameter side cylinder portion 30 is formed in the base plate portion 15 in a radially inner portion than the rotation-side engaging groove 18f and protrudes to the other axial side than the groove bottom surface 27a. Therefore, the rigidity of the rotation-side limiting surface 22 can be improved. Furthermore, in implementing the present invention, if the rotation-side limiting surface is connected to at least one of the outer diameter side cylinder portion and the inner diameter side cylinder portion, the rigidity of the rotation-side limiting surface can be improved.

[0207] The other structures and effects of the ninth example are the same as those of the first example.

[0208] [Case 10]

[0209] use Figure 29 and Figure 30 The tenth embodiment of the present invention will be described.

[0210] In this example, similar to the ninth example, the inclination angle α2 of the bottom surface 27b of the rotating engagement groove 18g relative to an imaginary plane orthogonal to the central axis of the drive member 5h is the same as the lead angle β2 of the axial ball thread groove 10 (α2 = β2). However, in this example, the lead angle β2 of the axial ball thread groove 10 and the inclination angle α2 of the bottom surface 27b of the rotating engagement groove 18g are set to values ​​larger than those in the ninth example (β2 > β1, α2 > α1).

[0211] In this example, the center angle θ of the rotating side engagement groove 18g is approximately 180 degrees. Therefore, the rotating side engagement groove 18g is formed over half the area of ​​the side surface 15a on the other side of the axial direction of the substrate portion 15.

[0212] In this example, compared to the construction in the ninth example, the machining range of the rotating side engagement groove 18g can be reduced. Therefore, it is advantageous in terms of achieving the rigidity and strength of the drive component 5h.

[0213] The other structures and effects of the tenth case are the same as those of the first and ninth cases.

[0214] [Case 11]

[0215] use Figure 31 The eleventh example of an embodiment of the present invention will be described.

[0216] In this example, unlike the ninth example and the tenth example of the embodiment, the inclination angle α3 of the bottom surface 27c of the rotating side engaging groove 18h relative to the imaginary plane orthogonal to the central axis of the drive member 5i is smaller than the lead angle β1 of the axial ball thread groove 10 (α3 < β1).

[0217] Therefore, the gap 28a between the axial end face of the non-rotational engaging portion 13, which enters the inner side of the rotating engaging groove 18h, and the groove bottom surface 27c decreases as the non-rotational engaging portion 13 moves relative to the other side in the circumferential direction within the rotating engaging groove 18h. However, in this example, the inclination angle α3 of the groove bottom surface 27c and the axial dimension of the rotating limiting surface 22 are limited so that the gap 28a between the axial end face of the non-rotational engaging portion 13 and the groove bottom surface 27c is not zero even when the non-rotational limiting surface 14 and the rotating limiting surface 22 are in contact.

[0218] In this example, compared to the ninth example, the machining amount of the rotating side engagement groove portion 18h can be reduced. Therefore, the machining time of the drive component 5i can be reduced, resulting in a reduction in manufacturing costs. Furthermore, it is advantageous in ensuring the rigidity and strength of the drive component 5i.

[0219] The other structures and effects of the eleventh case are the same as those of the first and ninth cases.

[0220] [Case 12]

[0221] use Figure 32 The twelfth example of an embodiment of the present invention will be described.

[0222] In the ball screw assembly 1a of this example, a motor shaft is used as the drive component 5j. The drive component 5j supports a rotor (not shown) on one axial side, and a stator (not shown) is arranged around the rotor. The drive component 5j has a mounting hole 19a that opens radially at the center of its side surface (end face) on the other axial side. Internal spline teeth 20 are formed on the inner circumferential surface of the mounting hole 19a. The drive component 5j is externally engaged with the internal spline teeth 20 formed on the inner circumferential surface of the mounting hole 19a by spline engaging with the external spline teeth 11 formed on the outer circumferential surface of the engaging shaft portion 9, preventing relative rotation with respect to the engaging shaft portion 9.

[0223] The drive component 5j has a rotating side engagement groove 18f on the other side of the axial direction. As for the rotating side engagement groove 18f, the axial depth increases from one side of the circumferential direction to the other side of the circumferential direction, and at the end of the other side of the circumferential direction, it engages with the non-rotating side engagement part 13 provided on the nut 3 in the circumferential direction, limiting the end of the stroke of the nut 3.

[0224] In this example, the stroke end of the nut 3, which is a linear motion element, can be achieved with fewer parts, and the ball screw device 1a can be miniaturized.

[0225] The other structures and effects of the twelfth case are the same as those of the first and ninth cases.

[0226] [Case 13]

[0227] use Figure 33 The thirteenth example of an embodiment of the present invention will be described.

[0228] In this example, an annular protrusion 31 is provided radially inward of the rotating-side engagement groove 18 in the side surface 15a of the base plate portion 15 constituting the drive member 5k on the axially opposite side. The annular protrusion 31 protrudes toward the axially opposite side and has an annular shape. The end face of the annular protrusion 31 on the axially opposite side abuts against the end face of the threaded portion 8 constituting the threaded shaft 2 on the axially opposite side.

[0229] The outer diameter of the annular protrusion 31 is slightly smaller than the inner diameter of the nut 3, and larger than the inner diameter of the groove bottom of the axial ball thread groove 10 formed on the outer circumferential surface of the threaded shaft 2. Preferably, the outer diameter of the annular protrusion 31 is the same as the outer diameter of the thread teeth of the axial ball thread groove 10. More preferably, the outer diameter of the annular protrusion 31 is larger than the outer diameter of the thread teeth of the axial ball thread groove 10.

[0230] In this example, with the non-rotating limiting surface 14 of the nut 3 and the rotating limiting surface 22 of the drive member 5k engaged in the circumferential direction, the annular protrusion 31 is axially inserted into the inner diameter side of the axial end of the nut 3. Then, the outer circumferential surface of the annular protrusion 31 and the axial end of the inner circumferential surface of the nut 3 are brought to near opposition throughout the entire circumference.

[0231] In this example, when the nut 3 moves relative to the threaded shaft 2 in one axial direction, the annular protrusion 31 enters the inner diameter side of the axial end of the nut 3, thereby allowing the annular protrusion 31 to push the grease filled inside the nut 3 back to the other axial direction. This effectively prevents the grease from remaining on the axial end of the inner circumferential surface of the nut 3 and leaking out from the opening on the axial side of the nut 3.

[0232] The other structures and effects of the thirteenth case are the same as those of the first and ninth cases.

[0233] [Case 14]

[0234] use Figure 34 The fourteenth example of an embodiment of the present invention will be described.

[0235] This example is a variation of the thirteenth example. In this example, with the non-rotational limiting surface 14 of the nut 3 and the rotational limiting surface 22 of the drive member 5k engaged in the circumferential direction, the outer peripheral surface of the annular protrusion 31 and the end of the inner peripheral surface of the nut 3 on one axial side are nearly opposed to each other throughout the entire circumference, and the side surface 15a of the base plate portion 15 of the drive member 5k on the other axial side and the side surface 3a of the nut 3 on one axial side are nearly opposed to each other throughout the entire circumference.

[0236] In this example, when the annular protrusion 31 is axially inserted into the inner diameter side of the axial end of the nut 3, leakage of grease from the gap between the side surface 15a of the base plate portion 15 of the drive member 5k on the other axial side and the side surface 3a of the axial side of the nut 3 can be suppressed. Therefore, grease leakage from the nut 3 to the outside can be prevented more effectively.

[0237] The other structures and effects of the fourteenth case are the same as those of the first, ninth, and thirteenth cases.

[0238] The embodiments of the present invention have been described above, but the present invention is not limited thereto, and appropriate modifications can be made without departing from the technical concept of the invention. Furthermore, the various embodiments of the present invention can be appropriately combined and implemented as long as they do not create contradictions.

[0239] In various embodiments of the present invention, a fan-shaped non-rotational side engaging portion is shown as an example of a protruding non-rotational side engaging portion. However, in the case of implementing the present invention, the shape of the non-rotational side engaging portion is not limited to the fan-shaped portion, and other shapes such as cylindrical or rectangular column shapes can be used.

[0240] In implementing this invention, when the drive component is provided with multiple rotating-side engaging slots, the number of rotating-side engaging slots is not limited to two or three, but can be four or more. Furthermore, the central angles of the multiple rotating-side engaging slots can be different from each other, and the multiple rotating-side engaging slots can be arranged at unequal intervals in the circumferential direction of the drive component.

[0241] In various embodiments of the present invention, the following configuration is shown: the mating shaft portion of the threaded shaft has external splines on its outer peripheral surface, and the driving member has a mounting hole with internal splines on its inner peripheral surface, so that the driving member is splinedly mated with the mating shaft portion. However, in implementing the present invention, the fixing configuration of the driving member relative to the mating shaft portion is not particularly limited. For example, the following configuration can also be adopted: the mating shaft portion has an oblong (elliptical) cross-section and a wrench opening shape with a pair of parallel flat outer surfaces on its outer peripheral surface; the mounting hole of the driving member is an oblong (elliptical) hole and a wrench opening shape with a pair of parallel flat inner surfaces on its inner peripheral surface, so that the driving member is non-circularly mated with the mating shaft portion.

[0242] In various embodiments of the present invention, a construction in which a circulation groove is formed directly on the inner circumferential surface of the nut has been described. However, in the case of implementing the present invention, the circulation groove can also be formed as a circulation component (e.g., a die) separate from the nut, and the circulation component can be fixed relative to the nut.

[0243] Symbol Explanation

[0244] 1. 1a—Ball screw assembly; 2—Threaded shaft; 3—Nut; 3a—Side side; 4—Ball; 5. 5a~5k—Drive components; 6—Load path; 7—Circulation groove; 8—Threaded part; 9—Matching shaft part; 10—Shaft-side ball thread groove; 11—External spline; 12—Nut-side ball thread groove; 13. 13a, 13b, 13c—Non-rotating side engaging part; 14—Non-rotating side limiting surface; 15—Base plate part; 15a—Side side; 16—Cylinder part; 17—Torque input part; 18. 18a~18h—Rotating side engaging groove part; 19. 19a—Mounting hole; 2 0—Internal spline teeth; 21a, 21b—Inner surface; 22—Rotational side limiting surface; 23—Step surface; 24, 24a—Inclined surface; 25—Connecting part; 26—Reinforcing part; 27, 27a~27c—Groove bottom surface; 28, 28a—Gap; 29—Outer diameter side cylinder; 30—Inner diameter side cylinder; 31—Annular protrusion; 100—Ball screw device; 101—Threaded shaft; 102—Nut; 103—Limiting element; 104—Threaded part; 105—Matching shaft part; 106—Shaft-side ball thread groove; 107—Interlocking part; 108—Protrusion; 109—Claw part.

Claims

1. A ball screw device, characterized in that, have: A threaded shaft has a helical axial ball thread groove on its outer circumferential surface and rotates during use; The nut has a helical ball thread groove on its inner circumferential surface and a protruding non-rotating engagement part on one axial side end, and moves linearly during use. Multiple balls are disposed between the shaft-side ball thread groove and the nut-side ball thread groove; and A drive component, which is fixed to the threaded shaft without relative rotation, and drives the threaded shaft to rotate. The drive component has an arc-shaped rotating side engaging groove, which allows the non-rotating side engaging part to be inserted axially, and its circumferential end can engage with the non-rotating side engaging part in the circumferential direction.

2. The ball screw device according to claim 1, characterized in that, The rotating side engaging groove is either a through groove that passes through the drive component in the axial direction, or a bottomed groove that opens on the side of the drive component on the other side in the axial direction.

3. The ball screw device according to claim 2, characterized in that, The rotating side engagement groove is a bottomed groove with a constant axial depth.

4. The ball screw device according to claim 2, characterized in that, The rotating side engaging groove is a bottomed groove whose axial depth varies along the circumferential direction.

5. The ball screw device according to claim 4, characterized in that, The angle of inclination of the bottom surface of the rotating engagement groove relative to an imaginary plane orthogonal to the central axis of the drive component is the same as or smaller than the lead angle of the axial ball thread groove.

6. The ball screw device according to claim 1, characterized in that, It has multiple rotating side engaging grooves.

7. The ball screw device according to claim 6, characterized in that, The plurality of the rotating side engaging slots are arranged at equal intervals in the circumferential direction of the drive component.

8. The ball screw device according to claim 1, characterized in that, The central angle of the rotating side engaging groove is greater than 36 degrees and less than 324 degrees.

9. The ball screw device according to claim 1, characterized in that, The size of the central angle of the rotating side engagement groove is larger than the size of the central angle of the non-rotating side engagement.

10. The ball screw device according to claim 1, characterized in that, The size of the central angle of the portion of the drive component that separates from the rotating side engagement groove in the circumferential direction is larger than the size of the central angle of the non-rotating side engagement portion.

11. The ball screw device according to claim 1, characterized in that, The rotating side engaging groove has a reinforcing part in the middle part of the circumferential direction that connects the inner side of the radially outer side and the inner side of the radially inner side in the radial direction.

12. The ball screw device according to claim 1, characterized in that, The drive component has a torque input section on its outer peripheral surface. The torque input section is located radially outward from the non-rotating engagement section.

13. The ball screw device according to claim 12, characterized in that, The threaded shaft has: a threaded portion having a axial ball thread groove formed on its outer peripheral surface; and a fitting shaft portion disposed on one axial side of the threaded portion and externally fixed to the drive component in a non-rotatable manner. The torque input portion is radially positioned at a location that overlaps with the portion of the rotating-side engaging portion that engages with the non-rotating-side engaging portion.

14. The ball screw device according to claim 12 or 13, characterized in that, The driving component is any one of a gear, a pulley, and a sprocket.

15. The ball screw device according to any one of claims 1 to 11, characterized in that, The driving component is a motor shaft.

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