JP2023022878A - ball screw device - Google Patents

Abstract

To provide a ball screw device which can restrict movement of a connection component to one side in an axial direction.SOLUTION: A ball screw device includes: a nut provided with an inner peripheral raceway surface; a screw shaft which is provided with an outer peripheral raceway surface and penetrates through the nut; balls disposed between the inner peripheral raceway surface and the outer peripheral raceway surface; and a connection component attached to the screw shaft. The screw shaft includes: a screw shaft body provided with the outer peripheral raceway surface; and an attachment part provided with a groove surface which is continuous with the outer peripheral raceway surface. An outer diameter of the attachment part is larger than a root diameter of the groove surface and smaller than an outer diameter of the screw shaft body. A step surface extending in a radial direction and a circumferential direction is provided at a border between the screw shaft body and the attachment part. The connection component has an annular connection part body into which the attachment part is inserted. An inner peripheral surface of the connectin part body is provided with a thread which threadedly engages with the groove surface. The step surface contacts with the connection part body from a first direction in which the screw shaft body is disposed when viewed from the attachment part of the axial direction.SELECTED DRAWING: Figure 4

Description

The present invention relates to a ball screw device.

A ball screw device is a device that includes a nut, a screw shaft, and a plurality of balls arranged between the nut and the screw shaft. A ball screw device is sometimes used in such a way that rotational motion generated by a motor is input to a nut, and the screw shaft moves in the axial direction. Moreover, there are cases where parts such as anti-rotation and stoppers are non-rotatably attached to the end of the screw shaft. Hereinafter, the parts connected to the screw shaft, such as anti-rotation and stoppers, are collectively referred to as connecting parts. Further, in the axial direction of the screw shaft, the portion provided with the outer raceway surface is called the screw shaft main body, and the portion to which the connecting part is attached is called the mounting portion.

The outer peripheral surface of the screw shaft body is provided with an outer peripheral raceway surface on which the balls roll. According to the following patent document, the outer peripheral surface of the mounting portion is also provided with a helical groove surface continuous with the outer peripheral raceway surface. On the one hand, the connecting piece comprises an annular portion into which the mounting portion is inserted. The inner peripheral surface of this annular portion is provided with a thread. The thread is screwed into the groove surface, and the connecting part is attached to the screw shaft.

JP 2010-270887 A

The connecting part disclosed in the above-mentioned patent document is freely movable in the spiral direction along the grooved surface of the mounting portion. That is, the connecting part moves in the axial direction with respect to the screw shaft.

The present disclosure has been made in view of the above problems, and an object thereof is to provide a ball screw device capable of restricting movement of a connecting component in at least one of the axial directions.

In order to achieve the above object, a ball screw device according to an aspect of the present disclosure includes a nut having an inner peripheral raceway surface provided on its inner peripheral surface, and an outer peripheral raceway surface provided on its outer peripheral surface, penetrating the nut. A screw shaft, a plurality of balls arranged between the inner raceway surface and the outer raceway surface, and a connecting part attached to the screw shaft. The screw shaft includes a screw shaft main body and an attachment portion that is continuously arranged with respect to the screw shaft main body in an axial direction parallel to the screw shaft. The screw shaft main body is provided with the outer peripheral raceway surface. The mounting portion is provided with a groove surface that is continuous with the outer peripheral raceway surface. The outer diameter of the mounting portion is larger than the root diameter of the groove surface and smaller than the outer diameter of the screw shaft main body. A stepped surface extending in the radial direction and the circumferential direction is provided at the boundary between the screw shaft main body and the mounting portion. The connecting component has an annular connecting portion main body into which the mounting portion is inserted. The inner peripheral surface of the connecting portion main body is provided with a screw thread that is screwed into the groove surface. The stepped surface abuts on the connecting portion main body from a first direction in which the screw shaft main body is disposed when viewed from the mounting portion in the axial direction.

According to the above configuration, the connecting component is attached to the screw shaft by screwing. The connecting portion main body abuts on the step surface and does not move in the first direction. Therefore, the connecting component is restricted from moving in the first direction (axial direction).

As a desirable aspect of the above-described ball screw device, the outer peripheral surface of the mounting portion is provided with an annular recess recessed radially inward. A C-shaped retaining ring is fitted in the recess when viewed from the axial direction. The retaining ring abuts on the connecting portion main body from a second direction opposite to the first direction.

According to the above configuration, the connecting portion main body abuts against the retaining ring and does not move in the second direction. As a result, the connecting part is restricted from moving to both sides in the axial direction, and does not move in the spiral direction along the groove surface. As a result, the connecting part is fixed so as not to rotate relative to the screw shaft.

As a desirable aspect of the above ball screw device, the screw shaft has a male thread portion positioned in a second direction opposite to the first direction with respect to the mounting portion. The male threaded portion is provided with a locking nut to be screwed thereon. The locking nut abuts the coupling body from the second direction.

According to the above configuration, the coupling body abuts against the locking nut and does not move in the second direction. As a result, the connecting part is restricted from moving to both sides in the axial direction, and does not move in the spiral direction along the groove surface. As a result, the connecting part is fixed so as not to rotate relative to the screw shaft.

As a desirable aspect of the above ball screw device, the screw shaft has a crimped portion located in a second direction opposite to the first direction with respect to the mounting portion. The crimped portion is in contact with the connecting portion main body from a second direction opposite to the first direction.

According to the above configuration, the connecting portion main body contacts the crimped portion and does not move in the second direction. As a result, the connecting part is restricted from moving to both sides in the axial direction, and does not move in the spiral direction along the groove surface. As a result, the connecting part is fixed so as not to rotate relative to the screw shaft.

According to the ball screw device of the present disclosure, the connecting component does not move in at least one of the axial directions.

FIG. 1 is a cross-sectional view of the electric actuator of Embodiment 1 cut in the axial direction. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 3 is a perspective view of a portion of the screw shaft mounting portion and the screw shaft main body of Embodiment 1. FIG. 4 is a sectional view taken along line IV-IV in FIG. 2. FIG. FIG. 5 is a cross-sectional view of the screw shaft of Embodiment 1 cut in a direction perpendicular to the axis. FIG. 6 is a cross-sectional view of the screw shaft of Modification 1. FIG. FIG. 7 is a cross-sectional view of the screw shaft of Modification 2. FIG. FIG. 8 is a side view of the ball screw device of Embodiment 2 as seen from the second direction. 9 is a cross-sectional view taken along line IX-IX of FIG. 8. FIG. FIG. 10 is a side view of the ball screw device of Embodiment 3 as seen from the second direction. 11 is a cross-sectional view taken along line XI-XI of FIG. 10. FIG.

Hereinafter, the present disclosure will be described in detail with reference to the drawings. The present disclosure is not limited by the following modes for carrying out the invention (hereinafter referred to as embodiments). In addition, components in the following embodiments include those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that fall within a so-called equivalent range. Furthermore, the constituent elements disclosed in the following embodiments can be combined as appropriate.

(Embodiment 1)
FIG. 1 is a cross-sectional view of the electric actuator of Embodiment 1 cut in the axial direction. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 3 is a perspective view of a portion of the screw shaft mounting portion and the screw shaft main body of Embodiment 1. FIG. 4 is a sectional view taken along line IV-IV in FIG. 2. FIG. FIG. 5 is a cross-sectional view of the screw shaft of Embodiment 1 cut in a direction perpendicular to the axis. FIG. 6 is a cross-sectional view of the screw shaft of Modification 1. FIG. FIG. 7 is a cross-sectional view of the screw shaft of Modification 2. FIG.

As shown in FIG. 1, the electric actuator 100 of Embodiment 1 includes a motor 101, a transmission device 102, a housing 103, and a ball screw device 1. The electric actuator 100 is a device that converts rotary motion generated by the motor 101 into linear motion by the ball screw device 1 . The electric actuator 100 is used, for example, as a brake booster.

The motor 101 includes a stator (not shown), a rotor (not shown), and an output shaft 101a. Motor 101 is supported by housing 103 . The output shaft 101 a is parallel to the screw shaft 5 of the ball screw device 1 . Hereinafter, a direction parallel to the screw shaft 5 is referred to as an axial direction.

The transmission device 102 includes a first gear 102a fitted to the output shaft 101a and a second gear 102b meshing with the first gear 102a. The second gear 102b is fitted to the nut 4 of the ball screw device 1. As shown in FIG. The second gear 102b has a larger diameter than the first gear 102a. Therefore, the rotational motion generated by the motor 101 is reduced by the transmission device 102 and transmitted to the nut 4 .

The ball screw device 1 includes an anti-rotation 2 which is a connecting part, a snap ring 3 , a nut 4 , a screw shaft 5 and a plurality of balls 6 . The nut 4 is a cylindrical part. An inner peripheral raceway surface 4 a is provided on the inner peripheral surface of the nut 4 . The nut 4 is arranged inside the housing 103 so as to open in the axial direction. The outer ring of the bearing device 7 is fitted to the inner peripheral surface of the housing 103 . The nut 4 is fitted to the inner ring of the bearing device 7 . As described above, the nut 4 is supported by the housing 103 so as to be rotatable about the axis O of the screw shaft 5 .

The screw shaft 5 is an axially extending solid component. The screw shaft 5 includes a screw shaft body 10 and a mounting portion 11 . The screw shaft main body 10 and the mounting portion 11 are arranged continuously in the axial direction. Among the axial directions, the direction in which the screw shaft body 10 is arranged when viewed from the mounting portion 11 is referred to as a first direction X1. A direction opposite to the first direction X1 is referred to as a second direction X2.

The screw shaft 5 has an end face 5a facing the second direction X2. An outer peripheral raceway surface 13 is provided on the outer peripheral surface of the screw shaft main body 10 . The screw shaft main body 10 is arranged so as to pass through the nut 4 . The attachment portion 11 is arranged so as to be positioned in the second direction X2 with respect to the nut 4 . The outer raceway surface 13 of the screw shaft body 10 faces the inner raceway surface 4 a of the nut 4 . A track is formed between the outer circumference raceway surface 13 and the inner circumference raceway surface 4a.

A plurality of balls 6 are arranged on a track. The nut 4 is provided with a circulation path (not shown) for circulating the balls 6 arranged at one end of the track to the other end of the track. Therefore, when the nut 4 rotates, the ball 6 rolls on the track and moves to one end of the track, and then circulates to the other end of the track by the circulation path. Therefore, the balls 6 endlessly circulate on the rolling path. Further, when the nut 4 rotates, it is converted into axial motion by the inner circumferential raceway surface 4a and the outer circumferential raceway surface 13, and the screw shaft 5 moves in the axial direction.

An anti-rotation 2 and a retaining ring 3 are attached to the attachment portion 11 . As shown in FIG. 2 , the anti-rotation 2 includes an annular connecting portion main body 20 and three arms 21 extending radially outward from the connecting portion main body 20 . The connecting portion main body 20 is fitted to the mounting portion 11 . The arm portions 21 are arranged at regular intervals in the circumferential direction. A radially outer end of the arm portion 21 is inserted into the guide groove 103 a of the housing 103 . The arm portion 21 is movable along the guide groove 103a. The guide groove 103a extends in the axial direction (see FIG. 1). As described above, the anti-rotation 2 is supported by the housing 103 so as to be movable in the axial direction and unrotatable around the axis.

In addition, as shown in FIG. 2, the nut 4 has an end surface 4b facing the second direction X2. The end surface 4b is provided with a restricting portion 4c that protrudes in the second direction X2. When the screw shaft 5 moves in the first direction X1 and the anti-rotation 2 approaches the nut 4, the restricting portion 4c abuts against one of the three arms 21 from the circumferential direction. As a result, the position of the screw shaft 5 in the axial direction becomes constant when the electric actuator 100 starts to be driven. In this embodiment, the restricting portion 4c of the nut 4 abuts (contacts) the arm portion 21 of the antirotation 2, but the present disclosure is not limited to this. A protrusion may be provided on the end surface of the antirotation 2, and the restricting portion 4c of the nut 4 may abut (contact) the protrusion.

The retaining ring 3 is a C-shaped component. The retaining ring 3 is a component for restricting the anti-rotation 2 from coming off from the mounting portion 11 . The retaining ring 3 is fitted to the outer peripheral surface 11 a of the mounting portion 11 . The retaining ring 3 is arranged in the second direction X2 when viewed from the anti-rotation 2. As shown in FIG.

Next, details of the screw shaft 5 and the connecting portion main body 20 will be described. As shown in FIG. 3, a screw groove 12 is formed on the outer peripheral surface of the screw shaft 5 . This thread groove 12 is a groove for forming an outer peripheral raceway surface 13 on the outer peripheral surface 10 a of the screw shaft main body 10 . The thread groove 12 is positioned in the second direction X2 as it goes leftward (counterclockwise, see arrow A in FIG. 3) when viewed from the second direction X2. Moreover, the thread groove 12 has an equal pitch. A thread groove 12 is formed from the end of the screw shaft 5 in the first direction X1 to the end in the second direction X2. Accordingly, the thread groove 12 is also formed on the outer peripheral surface 11a of the mounting portion 11 (see the region marked with a lattice pattern in FIG. 3). Hereinafter, the concave surface of the thread groove 12 provided on the outer peripheral surface 11 a of the mounting portion 11 is referred to as a groove surface 14 . The groove surface 14 is continuous with the outer circumference raceway surface 13 .

Further, portions between the screw grooves 12 in the screw shaft main body 10 are thread ridges 16 . The thread 16 is positioned in the second direction X2 as it goes counterclockwise (see arrow A in FIG. 3) when viewed from the second direction X2.

As shown in FIG. 4 , the outer diameter r1 of the mounting portion 11 is smaller than the outer diameter r2 of the screw shaft body 10 . That is, as shown in FIG. 3, the outer peripheral surface 11a of the mounting portion 11 has a smaller diameter than the outer peripheral surface 10a of the screw shaft main body 10. As shown in FIG. Therefore, a stepped surface 15 (see hatched area in FIG. 3) facing the second direction X2 is provided at the boundary L between the mounting portion 11 and the screw shaft body 10 .

The outer peripheral surface 11a has a circular shape centering on the axis O when viewed from the axial direction. Further, a part of the side surface 16a of the screw thread 16 facing the second direction X2 is shaved to form the stepped surface 15. As shown in FIG. In addition, in the present disclosure, the outer peripheral surface 11a and the stepped surface 15 of the mounting portion 11 may be formed by a method other than polishing.

As shown in FIG. 4 , the outer diameter r1 of the mounting portion 11 is larger than the root diameter r4 of the groove surface 14 . That is, as shown in FIG. 3, even if the diameter of the outer peripheral surface 11a of the mounting portion 11 is reduced by polishing, the groove surface 14 remains on the outer peripheral surface 11a of the mounting portion 11. As shown in FIG. The root diameter r4 of the groove surface is the same as the root diameter r3 of the outer circumferential raceway surface 13 .

The step surface 15 extends radially and circumferentially. That is, the step surface 15 is a surface perpendicular to the axis O and does not extend in the spiral direction. Further, the stepped surface 15 is C-shaped when viewed from the axial direction, and is not annular.

In FIG. 5, dots are added to make it easier to see the range overlapping the step surface 15 in the axial direction. A radially inner edge portion 15 a (see FIGS. 3 and 5 ) of the stepped surface 15 extends circumferentially along the outer peripheral surface 11 a of the mounting portion 11 . A circumferential center portion 15 b (see FIGS. 3 and 5 ) of the radially outer edge portion of the step surface 15 extends circumferentially along the outer peripheral surface 10 a of the screw shaft body 10 . Circumferential end portions 15c (see FIGS. 3 and 5) of the radially outer edge portion of the stepped surface 15 are inclined radially inward toward the circumferentially outer side.

As shown in FIG. 4, the outer peripheral surface 11a of the mounting portion 11 is provided with a concave portion 17 that is recessed radially inward. The inner peripheral side of the retaining ring 3 is fitted into the recess 17 . Thereby, the snap ring 3 is fixed to the screw shaft 5 so as not to move in the axial direction. The concave portion 17 is located near the end of the mounting portion 11 in the second direction X2. A diameter r5 of the recessed portion 17 is smaller than a root diameter r4 of the groove surface 14 . Further, the recess 17 extends in the circumferential direction and has an annular shape. Therefore, as shown in FIG. 3 , when viewed from the radially outer side, a portion of the recess 17 (see the dotted area in FIG. 3 ) in the circumferential direction overlaps the groove surface 14 .

As shown in FIG. 4 , a thread 22 is provided on the inner peripheral surface of the connecting portion main body 20 of the antirotation 2 . The cross-sectional shape of the thread 22 corresponds to the groove surface 14 and is semicircular. The root diameter r6 of the thread 22 is smaller than the outer diameter r2 of the screw shaft main body. Thread 22 is the same lead as groove surface 14 . The screw thread 22 enters the groove surface 14 of the mounting portion 11 , and the connecting portion main body 20 is screwed into the mounting portion 11 . Note that the cross-sectional shape of the thread 22 of the present disclosure is not limited to a semicircular shape. The cross-sectional shape of the thread 22 is not particularly limited as long as it can be screwed into the groove surface 14, such as a trapezoidal shape.

The connecting portion main body 20 includes a first end face 23 facing the first direction X1 and a second end face 24 facing the second direction X2. The first end surface 23 facing the first direction X1 is in contact with the stepped surface 15 . The second end surface 24 is in contact with the snap ring 3 . As described above, the anti-rotation 2 is fixed to the screw shaft 5 so as not to move in the axial direction. Also, the anti-rotation 2 does not move in the spiral direction along the groove surface 14 . Therefore, the anti-rotation 2 is fixed to the screw shaft 5 so as not to rotate relative to it. As described above, the screw shaft 5 is axially movably and non-rotatably supported by the housing 103 via the anti-rotation 2 .

As described above, the ball screw device 1 of Embodiment 1 includes the connecting component (anti-rotation 2), the nut 4, the screw shaft 5, and the plurality of balls 6. The connecting part is attached to the threaded shaft. The nut 4 is provided with an inner circumferential raceway surface 4a on its inner circumferential surface. The screw shaft 5 is provided with an outer raceway surface 13 on its outer peripheral surface and passes through the nut 4 . The balls 6 are arranged between the inner raceway surface and the outer raceway surface. The screw shaft 5 includes a screw shaft main body 10 provided with an outer peripheral raceway surface 13, and a groove surface 14 which is arranged continuously with the screw shaft main body 10 in an axial direction parallel to the screw shaft 5 and which is continuous with the outer peripheral raceway surface 13. and a mounting portion 11 provided with. The outer diameter r1 of the mounting portion 11 is larger than the root diameter r4 of the groove surface 14 and smaller than the outer diameter r2 of the screw shaft body 10 . A boundary L between the screw shaft main body 10 and the mounting portion 11 is provided with a step surface 15 extending in the radial direction and the circumferential direction. The connecting part has an annular connecting part main body 20 into which the mounting part 11 is inserted. A screw thread 22 that is screwed into the groove surface 14 is provided on the inner peripheral surface of the connecting portion main body 20 . The stepped surface 15 abuts on the connecting portion main body 20 from the first direction in which the screw shaft main body 10 is disposed when viewed from the mounting portion 11 in the axial direction.

The connecting part (anti-rotation 2) is attached to the screw shaft 5 by screwing. The connecting portion main body 20 is in contact with the step surface 15 . Therefore, the connecting component is restricted from moving in the first direction X1.

Further, an annular recess 17 that is recessed radially inward is provided on the outer peripheral surface 11a of the mounting portion 11 of the first embodiment. A C-shaped retaining ring 3 is fitted in the concave portion 17 when viewed from the axial direction. The retaining ring 3 abuts on the connecting portion main body 20 from the second direction X2, which is the opposite direction to the first direction X1.

The connecting portion main body 20 is in contact with the retaining ring 3 . Therefore, movement in the second direction X2 is restricted. Thereby, the connecting part does not move in the spiral direction along the groove surface 14 . That is, the connecting parts are connected to the screw shaft 5 so as not to rotate relative to each other.

Although the first embodiment has been described above, the present disclosure is not limited to the first embodiment. For example, the connecting part that connects to the screw shaft 5 is not limited to the anti-rotation 2 . In the present disclosure, the connecting component may be a stopper that contacts the regulating portion 4c of the nut 4. FIG. Alternatively, the present disclosure may be a connecting component in which the anti-rotation 2 having a stopper function is connected to the screw shaft 5 .

Moreover, although the thread grooves 12 of Embodiment 1 are formed at an equal pitch, in the present disclosure, the pitch of the outer circumferential raceway surface 13 and the pitch of the groove surface 14 may be different. In other words, in the screw shaft of the present disclosure, the pitch of the groove surface 14 may be larger than the pitch of the outer circumferential raceway surface 13 . Hereinafter, the relationship between the pitch of the thread groove 12 and the stepped surface 15 will be described with reference to modified example 1 (see FIG. 6) and modified example 2 (see FIG. 7).

As shown in FIG. 6, the pitch of the thread groove 12A of the threaded shaft 5A of Modification 1 is smaller than that of the thread groove 12 of the threaded shaft 5 of the first embodiment. As shown in FIG. 7, the thread groove 12B of the screw shaft 5B of Modification 2 has a smaller pitch than the thread groove 12B of the screw shaft 5A of Modification 1. As shown in FIG. As shown in FIGS. 5 to 7, the areas of the step surfaces 15, 15A, and 15B decrease in the order of the first embodiment, the first modification, and the second modification. Thus, when the pitch of the thread groove is large, the step surface 15 provided on the side surface of the thread groove has a long circumferential length and a large area.

Therefore, if the pitch of the grooved surface 14 is larger than the pitch of the outer circumferential raceway surface 13 of the screw shaft 5 as described above, the area of the stepped surface 15 (the area of contact with the connecting component) is increased. As a result, movement of the connecting component in the first direction X1 can be more reliably restricted.

Next, Embodiment 2 and Embodiment 3 will be described. Embodiments 2 and 3 are examples in which a method other than the snap ring 3 is used to restrict movement of the connecting component in the second direction X2.

(Embodiment 2)
FIG. 8 is a side view of the ball screw device of Embodiment 2 as seen from the second direction. 9 is a cross-sectional view taken along line IX-IX of FIG. 8. FIG. A ball screw device 1D of the second embodiment differs from the ball screw device 1 of the first embodiment in that a screw shaft 5D is provided instead of the screw shaft 5. FIG. Further, the ball screw device 1D is different from the ball screw device 1 of the first embodiment in that a stop ring 3 is replaced with a stop nut 8 . The following description focuses on the differences.

The screw shaft 5D includes a screw shaft main body 10, a mounting portion 11, and a male thread portion 18 arranged in order from the first direction X1. An outer diameter r7 of the male threaded portion 18 is smaller than a root diameter r4 of the groove surface 14 of the mounting portion 11 . Therefore, the groove surface 14 (screw groove 12 ) does not remain on the male threaded portion 18 . Further, the outer peripheral surface 18a of the male threaded portion 18 is provided with a thread groove into which the stop nut 8 is screwed. The locking nut 8 is screwed onto the male threaded portion 18 . The locking nut 8 is in contact with the second end surface 24 of the coupling body 20 .

As described above, the screw shaft 5 of the ball screw device 1</b>D of the second embodiment has the male threaded portion 18 positioned in the second direction X<b>2 opposite to the first direction X<b>1 with respect to the mounting portion 11 . The male threaded portion 18 is provided with a locking nut 8 to be screwed therewith. The locking nut 8 abuts on the connecting portion main body 20 from the second direction X2.

Also in such a ball screw device 1D, the anti-rotation 2 does not move in the spiral direction along the groove surface 14, as in the first embodiment. That is, the anti-rotation 2 is connected to the screw shaft 5D so as not to rotate relative to it.

(Embodiment 3)
FIG. 10 is a side view of the ball screw device of Embodiment 3 as seen from the second direction. 11 is a cross-sectional view taken along line XI-XI of FIG. 10. FIG. A ball screw device 1E of the third embodiment differs from the ball screw device 1 of the first embodiment in that a screw shaft 5E is provided instead of the screw shaft 5. FIG.

The screw shaft 5E includes a screw shaft main body 10, a mounting portion 11, and a crimped portion 19, which are arranged in order from the first direction X1. The crimped portion 19 is generated by crushing the end portion of the mounting portion 11 in the second direction X2. In other words, the crimped portion 19 is formed without cutting or otherwise processing the outer peripheral side of the mounting portion 11 . In addition, a circular hole 5b is provided in the central portion of the end face 5a of the screw shaft 5 in order to facilitate crushing of the mounting portion. The crimped portion 19 is in contact with the second end surface 24 of the connecting portion main body 20 .

As described above, the screw shaft 5E of the ball screw device 1D of the second embodiment has the crimped portion 19 located in the second direction X2 opposite to the first direction X1 with respect to the mounting portion 11. As shown in FIG. The crimped portion 19 contacts the connecting portion main body 20 from the second direction X2, which is the opposite direction to the first direction X1.

In such a ball screw device 1E as well, the anti-rotation 2 does not move in the spiral direction along the groove surface 14, as in the first embodiment. That is, the anti-rotation 2 is connected to the screw shaft 5E so as not to rotate relative to it.

1, 1D ball screw device 2 anti-rotation (connecting parts)
3 retaining ring 4 nut 5, 5A, 5B, 5E screw shaft 6 ball 8 locking nut 10 screw shaft main body 11 mounting portion 12 screw groove 13 outer circumference raceway surface 14 groove surface 15, 15A, 15B step surface 16 screw thread 17 concave portion 18 male screw Part 19 Crimped Part 20 Connecting Part Body 21 Arm 22 Thread 23 First End Face 24 Second End Face 100 Electric Actuator 101 Motor 102 Transmission Device 103 Housing

Claims (4)

a nut having an inner circumferential raceway surface on its inner circumferential surface;
a screw shaft provided with an outer peripheral raceway surface on the outer peripheral surface and penetrating the nut;
a plurality of balls arranged between the inner raceway surface and the outer raceway surface;
a connecting part attached to the screw shaft;
with
The screw shaft is
a screw shaft body provided with the outer peripheral raceway surface;
a mounting portion disposed continuously with respect to the screw shaft main body in an axial direction parallel to the screw shaft and provided with a groove surface continuous with the outer peripheral raceway surface;
with
The outer diameter of the mounting portion is larger than the root diameter of the groove surface and smaller than the outer diameter of the screw shaft main body,
A step surface extending in a radial direction and a circumferential direction is provided at a boundary between the screw shaft main body and the mounting portion,
The connecting part has an annular connecting part body into which the mounting part is inserted,
The inner peripheral surface of the connecting portion main body is provided with a screw thread that is screwed into the groove surface,
The stepped surface is in contact with the coupling portion main body from a first direction in which the screw shaft main body is disposed when viewed from the mounting portion in the axial direction. An annular recess recessed radially inward is provided on the outer peripheral surface of the mounting portion,
A retaining ring having a C shape when viewed from the axial direction is fitted in the recess,
The ball screw device according to claim 1, wherein the retaining ring is in contact with the connecting portion main body from a second direction opposite to the first direction. the screw shaft has a male thread portion positioned in a second direction opposite to the first direction with respect to the mounting portion;
The male threaded portion is provided with a locking nut to be screwed together,
The ball screw device according to claim 1, wherein the locking nut is in contact with the connecting portion main body from the second direction. The screw shaft has a crimped portion positioned in a second direction opposite to the first direction with respect to the mounting portion,
The ball screw device according to claim 1, wherein the crimped portion is in contact with the connecting portion main body from a second direction opposite to the first direction.

Images