WO2016121781A1

WO2016121781A1 - Screw device

Info

Publication number: WO2016121781A1
Application number: PCT/JP2016/052237
Authority: WO
Inventors: 中村　太; 哲弘西出; 祐次久保田; 勉富樫
Original assignee: Thk株式会社
Priority date: 2015-01-28
Filing date: 2016-01-27
Publication date: 2016-08-04

Abstract

Provided is a screw device with which it is possible to provide an allowance in the precision of a recess at the end surface of a nut. A nut 2 is provided with a communicating hole 7 that passes therethrough in the axial direction, and a recess 8 that communicates with the communicating hole 7 is provided at an end surface 2d in the axial direction of the nut 2. A circulating member 4 having a direction changing passage is placed in the recess 8. When the circulating member 4 is placed in the recess 8, the direction changing passage of the circulating member 4 connects with a load rolling-body rolling groove 2c and the communicating hole 7 of the nut 2, thus forming a circulating passage for a rolling body 3. A gap g1 is provided between the circulating member 4 and a wall surface of the recess 8 so that the circulating member 4 can be moved. The circulating member 4 placed in the recess 8 is not fixed to the recess 8 and is covered with a lid member 5 that is attached to the nut 2.

Description

Screw device

The present invention relates to a screw device in which a rolling element is interposed between a screw shaft and a nut so that the rolling element circulates.

A screw device in which a rolling element is interposed between the screw shaft and the nut is used as a mechanical element that converts the rotational motion of the screw shaft into the linear motion of the nut, or converts the linear motion of the screw shaft into the rotational motion of the nut. It is done. Since this screw device uses the rolling motion of the rolling elements, the screw device and the nut can be easily moved.

As a type of screw device, a so-called end piece type screw device is known in which a circulating member is attached to an end face in the axial direction of a nut to circulate rolling elements (see Patent Document 1). In this screw device, a communication hole that penetrates the nut in the axial direction is formed in the nut. On the end face in the axial direction of the nut, a recess that communicates with the communication hole and the loaded rolling element rolling groove of the spiral is processed. The circulation member has a direction change path. When the circulation member is fitted in the recess, the direction change path of the circulation member is connected to the load rolling element rolling groove and the communication hole of the nut, and the circulation path of the rolling element is configured. After the circulation member is fitted into the recess of the nut, the circulation member is firmly fixed to the recess of the nut by a bolt or a C-shaped ring. The rolling element that has rolled to one end of the rolling element rolling groove of the nut passes through the direction change path of the circulation member, the communication hole, and the direction change path of the opposite circulation member to the other end of the load rolling element rolling groove. Return to.

JP 2007-247778 A

In the conventional screw device, the recess on the end face of the nut is machined from the end face side of the nut by a milling machine or the like after a threaded rolling element rolling groove is machined on the nut. However, there is a problem that it is difficult to accurately match the position of the loaded rolling element rolling groove and the position of the recess when processing the recess on the end face of the nut. For example, if the recess is displaced from the normal position in the circumferential direction of the nut, the load rolling element rolling groove has a lead, and therefore the connecting portion between the load rolling element rolling groove and the recess is displaced in the axial direction of the nut. If it becomes like this, even if it fits a circulation member in a crevice, a load rolling element rolling groove and a communicating hole cannot be smoothly connected in a direction change course of a circulation member, and smooth circulation of a rolling element is inhibited. The same is true even if the depth of the concave portion deviates from the normal depth. In order to avoid this, it is necessary to process the recess with high accuracy.

Therefore, the present invention provides a screw device that can provide a margin for the accuracy of the recesses on the end face of the nut.

In order to solve the above problems, an aspect of the present invention includes a screw shaft having a spiral rolling element rolling groove on an outer peripheral surface, a through hole in which the screw shaft is rotatably arranged, and an inner peripheral surface. A nut having a spiral loaded rolling element rolling groove facing the rolling element rolling groove, and a rolling motion between the rolling element rolling groove of the screw shaft and the loaded rolling element rolling groove of the nut. A plurality of rolling elements that intervene, and the nut has a communicating hole that penetrates the nut in the axial direction, and communicates with the communicating hole and the load rolling element rolling groove on an axial end surface. In the rolling element screw device, the circulating member is provided with a circulation member having a direction change path connected to the load rolling element rolling groove and the communication hole of the nut. And the circulation member is movable between the recess and the wall surface of the recess. A gap is provided so as, the circulation member disposed in the recess is a screw device that is covered by a lid member attached to said nut.

According to the present invention, the circulating member can move in the recess. Even if the recess is displaced with respect to the rolling rolling element rolling groove of the nut, the position of the circulating member is determined according to the movement of the rolling element, and the rolling element can be circulated smoothly. You can make room.

1 is a perspective view of a screw device according to a first embodiment of the present invention. It is a disassembled perspective view of the nut of the screw device of this embodiment. Fig.3 (a) is a front view of the end surface of the nut of this embodiment (the state which has arrange | positioned the circulation member in the recessed part of a nut), FIG.3 (b) is a front view of the end surface of the nut of this embodiment. Yes (with the circulation member removed). FIG. 4A is a perspective view of the circulation member of the present embodiment, and FIG. 4B is a perspective view of the concave portion of the nut of the present embodiment. Fig.5 (a) shows the perspective view of the nut and circulation member of this embodiment, FIG.5 (b) shows the A section enlarged view of Fig.5 (a). It is a perspective view of the circulation member of this embodiment. It is the B section enlarged view of Drawing 5 (b), and is a side view of the projection of the circulation member of this embodiment. FIG. 8A is a circulation member of the present embodiment as viewed from the axial direction of the screw shaft (when the circulation member rotates clockwise), and FIG. 8B is also the circulation member of the present embodiment ( FIG. 8C is also the circulation member of this embodiment (when the circulation member rotates counterclockwise). It is a side view of the circulation member (circulation member in the state arrange | positioned at a recessed part) of this embodiment. It is the front view seen from the axial direction of the circulation member of this embodiment. It is a disassembled perspective view of the nut of the screw device of the 2nd Embodiment of this invention. It is a side view of the circulation member (circulation member in the state accommodated in the recessed part) of the screw apparatus of the 2nd Embodiment of this invention.

Hereinafter, a screw device according to a first embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view of a screw device, and FIG. 2 is an exploded perspective view of a nut 2 of the screw device. Throughout the accompanying drawings and the following specification, the same reference numerals are given to the same components.
(First embodiment)

As shown in FIGS. 1 and 2, the screw device of the present embodiment includes a nut 2, a screw shaft 1 rotatably provided inside the nut 2, a ball 3 (see FIG. 9) as a plurality of rolling elements, and a nut. 2 is provided with a circulation member 4 disposed on the end surface 2d in the axial direction, and a seal cap 5 as a lid member attached to the end surface 2d in the axial direction of the nut 2.

As shown in FIG. 1, the nut 2 has a cylindrical shape and has a through hole 2a penetrating in the axial direction at the center. The screw shaft 1 passes through the through hole 2a. A flange 2b is provided at one end of the nut 2 in the axial direction. The flange 2b is provided with a through hole through which a bolt for attaching the nut 2 to the counterpart component is passed.

As shown in FIG. 2, a spiral loaded rolling element rolling groove 2 c is formed on the inner peripheral surface of the nut 2. The load rolling element rolling groove 2c faces the spiral rolling element rolling groove 1a (see FIG. 1) on the outer peripheral surface of the screw shaft 1. A plurality of balls 3 (see FIG. 9) are interposed between the loaded rolling element rolling groove 2c of the nut 2 and the rolling element rolling groove 1a of the screw shaft 1 so as to be capable of rolling motion.

A recess 8 communicating with one end of the load rolling element rolling groove 2c is formed on the end face 2d of the nut 2 in the axial direction. The recess 8 is formed on both

end surfaces

2d and 2e of the nut 2 in the axial direction. Although FIG. 2 shows only the concave portion 8 on the end surface 2 d on the near side of the nut 2, a concave portion having the same structure is formed on the end surface 2 e on the far side of the nut 2.

FIG. 3 (b) shows the end face 2d of the nut 2 as viewed from the axial direction. FIG. 3A shows an end face 2 d of the nut 2 in which the circulation member 4 is disposed in the recess 8. Note that the X axis in FIG. 3B is the direction in which the ball 3 coming out of the communication hole 7 faces the load rolling element rolling groove 2c, and is the tangential direction of the load rolling element rolling groove 2c. The Y axis is a direction orthogonal to the X axis. The Z axis is an axis orthogonal to the paper surface and is the axial direction of the screw shaft 1.

3 (b), a through hole 2a is formed at the center of the nut 2, and a loaded rolling element rolling groove 2c is formed on the inner peripheral surface of the nut 2. As shown in FIG. On the side of the through hole 2 a of the nut 2, a communication hole 7 that penetrates the nut 2 in the axial direction is provided. The end surface 2d of the nut 2 is provided with a recess 8 communicating with the communication hole 7 and the load rolling element rolling groove 2c. The concave portion 8 includes an insertion portion concave portion 11 having a deep depth in the Z-axis direction in which the direction changing path is formed, and an overhang portion concave portion 12 (for the overhang portion) having a shallower depth in the Z-axis direction than the insertion portion concave portion 11. The bottom surface of the recess 12 is indicated by a dot). The insertion portion recess 11 forms a direction change path in cooperation with the circulation member 4. The direction change path includes a straight line portion P1 arranged in a tangential direction of the load rolling element rolling groove 2c, and a circular arc portion P2 having a central angle of about 90 degrees connecting the straight line portion P1 and the communication hole 7 (see FIG. 9).

4 (a) shows a perspective view of the circulation member 4, and FIG. 4 (b) shows a perspective view of the recess 8. FIG. Also in FIG.4 (b), the bottom face of the overhang | projection part recessed part 12 is shown with a dot. The circulation member 4 includes an insertion portion 21 to be inserted into the insertion portion recess 11 and an extension portion 22 that protrudes outward from the insertion portion 21 and is disposed in the extension portion recess 12. The inner peripheral side of the arc portion P2 of the direction change path is formed in the insertion portion recess 11. An outer peripheral side of the arc portion P 2 of the direction change path is formed in the insertion portion 21 of the circulation member 4. The straight line portion P1 of the direction change path is divided on the XY plane shown in FIG. One side of the divided straight line portion P1 is formed in the insertion portion concave portion 11. The other side of the divided linear portion P 1 is formed on the overhang portion 22 of the circulation member 4. An arc-shaped step portion 13 (the step portion 13 is indicated by oblique lines, see also FIG. 3B) in which the tip of the insertion portion 21 of the circulation member 4 is disposed is formed in the insertion portion recess 11. The concave portion 8 further includes an arc-shaped movement limiting concave portion 14 adjacent to the communication hole 7 (the movement limiting concave portion 14 is indicated by oblique lines, see also FIG. 3B) and a rib concave portion 15 (FIG. 3B). Reference). The movement restricting recess 14 is deeper in the Z-axis direction than the rib recess 15.

As shown in FIG. 3 (b), one end 12a in the circumferential direction of the overhanging recess 12 of the recess 8 opens toward the through hole 2a, and as shown in FIG. 3 (a), the recess 8 The circulation member 4 arranged in the position can be rotated in the clockwise direction CW around the insertion portion 21. As shown in FIG. 3 (b), the other end 12b in the circumferential direction of the overhanging recess 12 is also open toward the through hole 2a, and is arranged in the recess 8 as shown in FIG. 3 (a). The circulating member 4 thus made can rotate in the counterclockwise direction CCW around the insertion portion 21.

As shown in FIG. 3A, the circulation member 4 is disposed in the recess 8. A gap g 1 is provided between the circulation member 4 and the wall surface of the recess 8 so that the circulation member 4 can move in the recess 8. As described above, the circulation member 4 includes the insertion portion 21 and the overhang portion 22. As shown in FIG. 4, between the insertion portion 21 of the circulation member 4 and the wall surface of the insertion portion recess 11 (see the hatched portion 11 c in FIG. 5B) so that the circulation member 4 can move. A gap is provided, and a gap is also provided between the protruding portion 22 of the circulation member 4 and the wall surface of the protruding portion recess 12 (see the hatched portion 12c in FIG. 5B). The size of the gap g1 is not particularly limited, and is, for example, 50 μm to 100 μm.

FIG. 5 (a) shows a perspective view of the nut 2 and the circulation member 4, and FIG. 5 (b) shows an enlarged view of part A of FIG. 5 (a). FIG. 6 shows a perspective view of the circulation member 4 as viewed from the insertion portion 21 side. As shown in FIG. 5A, the overhang portion 22 of the circulation member 4 is formed in a plate shape that curves along the through hole 2a. As shown in FIG. 5B, the overhanging portion 22 has a first leg portion 23 that protrudes in the circumferential direction on the inner peripheral side of the circumferential end portion 22a. The overhanging portion 22 has a second leg portion 24 protruding in the circumferential direction on the inner circumferential side of the other end portion 22b in the circumferential direction. As shown in FIG. 3A, the inner periphery 22 d of the overhang portion 22, the first leg portion 23, and the second leg portion 24 protrude in the inner diameter direction from the through hole 2 a of the nut 2.

As shown in FIG. 6, the insertion portion 21 of the circulation member 4 projects from the overhang portion 22 toward the nut 2. The insertion part 21 comprises the outer peripheral side of the circular arc part P2 of a direction change path. The cross section orthogonal to the direction change path of the insertion part 21 is circular arc shape. The circulation member 4 is further provided with a substantially columnar raised portion 25, a rib 26 for reinforcing the raised portion 25, and a movement restricting convex portion 27. The hoisting portion 25 is curved so as to follow the rolling element rolling groove 1a of the screw shaft 1, and has a function of scooping up the ball 3 moving in the rolling element rolling groove 1a of the screw shaft 1. The ribs 26 are connected to the hoisting part 25 to reinforce the hoisting part 25. The movement restricting convex portion 27 has an arc shape and is adjacent to the insertion portion 21. There is a step between the movement restricting convex portion 27 and the rib 26, and the movement restricting convex portion 27 protrudes further toward the nut 2 than the rib 26. As shown in FIG. 4, when the circulation member 4 is disposed in the recess 8, the movement restricting protrusion 27 is disposed in the movement restricting recess 14. Then, the rib 26 is disposed in the rib recess 15.

As shown in FIG. 5B, the projecting portion 22 of the circulating member 4 has a flat surface 22c (end surface in the Z-axis direction) facing the seal cap 5. On the facing surface 22 c of the circulation member 4, a projection 28 that protrudes from the facing surface 22 c toward the seal cap 5 is formed at one end 22 a that is away from the communication hole 7. As shown in the side view of the circulation member 4 in which the protrusion 28 of FIG. 7 is enlarged, the surface 28a of the protrusion 28 is formed in a plane. A gap g 3 is provided between the surface 28 a of the protrusion 28 and the seal cap 5. The size of the gap g3 is not particularly limited and is, for example, 20 μm to 40 μm. A gap g 2 is provided between the facing surface 22 c of the circulation member 4 and the seal cap 5. The size of the gap g2 is larger than the size of the gap g3. The size of the gap g2 is not particularly limited, and is, for example, 50 μm to 150 μm. The circulation member 4 is made of resin.

As shown in FIG. 2, after the circulation member 4 is disposed in the recess 8, the circulation member 4 is covered with a seal cap 5. The seal cap 5 is formed in a ring-shaped thin plate shape. The seal cap 5 has a plurality of through holes 5a through which bolts 9 as fastening members pass. The seal cap 5 is firmly fixed to the end surface 2 d of the nut 2 by the bolt 9. The seal cap 5 is made of resin. When the circulation member 4 is arranged in the recess 8 of the nut 2, the load rolling element rolling groove 2 c of the nut 2 and the direction change path of the circulation member 4 are connected, and the communication hole 7 of the nut 2 and the direction change path of the circulation member 4 are connected. .

There is a gap g 1 between the circulation member 4 and the wall surface of the recess 8, and the circulation member 4 can move in the recess 8. Even if the recess 8 is displaced relative to the loaded rolling element rolling groove 2 c of the nut 2, the ball 3 can be smoothly circulated, so that the accuracy of the recess 8 can be given a margin.

Further, the circulation member 4 has an insertion portion 21 and an overhang portion 22. When the ball 3 is circulated, as shown in FIG. 3A, the circulating member 4 swings around the Z axis in the clockwise direction CW and the counterclockwise direction CCW around the insertion portion 21. Even if the load rolling element rolling groove 2c and the circulation member 4 are displaced due to the circulation member 4 swinging around the Z axis, the position of the circulation member 4 is determined according to the movement of the ball 3. The ball 3 smoothly moves through the connecting portion between the loaded rolling element rolling groove 2c and the direction change path.

The circulation member 4 and the recess 8 of the present embodiment have a function of restricting the movement of the circulation member 4 by a predetermined amount while ensuring the movement of the circulation member 4. The function for restricting this movement will be described below with reference to FIGS. 5 and 8 to 10. 5A, the Z axis is the axial direction of the screw shaft 1, the X axis is the direction in which the ball 3 exiting the communication hole 7 faces the load rolling element rolling groove 2c, and the Y axis is Z It is a direction orthogonal to the axis and the X axis. In the present embodiment, while allowing the circulation member 4 to move in the X-axis, Y-axis, and Z-axis directions, Zθ that is the rotation of the circulation member 4 around the Z-axis is limited, and the rotation of the circulation member 4 around the Y-axis is limited. A certain Yθ is limited, and the movement of the circulation member 4 in the X-axis direction is limited.

The limitation of Zθ of the circulation member 4 is performed as follows. FIG. 8 shows the circulation member 4 as viewed from the axial direction of the screw shaft 1. FIG. 8B shows the case where the circulation member 4 is in the center position, and FIG. 8A shows the case where the circulation member 4 rotates in the clockwise direction CW around the insertion portion 21, and FIG. c) shows the case where the circulating member 4 rotates counterclockwise CCW around the insertion portion 21. As shown in FIG. 8 (a), the second leg 24 of the circulating member 4 projects the recess 8 before the first leg 23 of the circulating member 4 rotating clockwise CW hits the screw shaft 1. It is comprised so that it may hit one wall surface C1 of the recessed part 12 for parts. Then, as shown in FIG. 8C, the first leg 23 of the circulation member 4 is recessed before the second leg 24 of the circulation member 4 rotating in the counterclockwise direction CCW hits the screw shaft 1. It is comprised so that it may contact the other wall surface C2 of the recessed part 12 for 8 overhang | projection parts. Thereby, interference with the circulation member 4 and the screw shaft 1 which rock | fluctuate centering on the insertion part 21 can be avoided. In addition, by arranging the first and

second leg portions

23 and 24 at the end portions in the circumferential direction of the circulation member 4, the swing angle of the circulation member 4 can be controlled with high accuracy.

The restriction of Yθ of the circulation member 4 is performed as follows. FIG. 9 shows the circulation member 4 as seen from the Y-axis direction of FIG. If the circulation member 4 tilts counterclockwise CCW around the Y axis, the tip of the insertion portion 21 of the circulation member 4 protrudes into the communication hole 7, and the ball 3 coming out of the communication hole 7 is inserted into the insertion portion 21 of the circulation member 4. There is a risk of hitting the tip. Providing the protrusion 28 in contact with the seal cap 5 at one end 22a of the circulation member 4 far from the communication hole 7 can restrict the circulation member 4 from tilting counterclockwise about the Y axis. Since the gap g3 is provided between the projection 28 and the seal cap 5, the circulation member 4 can move in the Z-axis direction by the gap g3.

On the other hand, a gap g2 is provided between the facing surface 22c of the circulation member 4 and the seal cap 5. Thereby, the circulation member 4 can be inclined clockwise CW with the protrusion 28 as a fulcrum. When the ball 3 is circulated, the circulation member 4 swings around the Y axis in FIG. 9, so that the ball 3 smoothly moves through the connection portion between the communication hole 7 and the direction change path.

Restriction of the X-axis movement of the circulation member 4 is performed as follows. As shown in FIG. 9, if the circulation member 4 moves in the X-axis direction, the distal end of the insertion portion 21 of the circulation member 4 protrudes into the communication hole 7, and the circulation member 4 rotates counterclockwise CCW around the Y-axis. The same phenomenon occurs as when rotating at the same time. In order to avoid this, as shown in FIG. 4 (a), the circulation limiting member 4 is provided with a movement restricting convex part 27, and as shown in FIG. 4 (b), a movement restricting concave part 14 is provided in the concave part 8. As shown in FIG. 10, when the circulation member 4 moves in the X-axis direction (downward in FIG. 9), the movement restricting convex portion 27 (the movement restricting convex portion 27 is indicated by hatching) and the movement restricting concave portion 14 come into contact with each other. The movement of the circulation member 4 in the X-axis direction is limited. By disposing the movement restricting recess 14 adjacent to the communication hole 7, as shown in FIG. 10, it becomes possible to dispose the movement restricting protrusion 27 inside the circulation member 4, and the space in the recess 8 is reduced. Effective use.
(Second Embodiment)

FIG. 11 shows an exploded perspective view of the nut of the screw device according to the second embodiment of the present invention. The screw device of the second embodiment also includes a screw shaft 1, a nut 2, a circulation member 4 disposed in the recess 8 of the nut 2, and a seal cap 5 that covers the circulation member 4. Since the configuration of the screw shaft 1, the nut 2, the concave portion 8 of the nut 2, and the seal cap 5 is the same as that of the screw device of the first embodiment, the same reference numerals are given and the description thereof is omitted.

In the first embodiment, as shown in FIG. 5B, one protrusion 28 is provided on the surface 22c of the circulating member 4 facing the seal cap 5, whereas in the second embodiment, it is shown in FIG. As described above, the two

protrusions

28 ₁ and 28 ₂ are provided on the surface 22 c of the circulating member 4 facing the seal cap 5. ₁ first projection 28, the communication hole 7 provided in the circumferential direction of the one end 22a away from (indicating the insertion portion 21 to be inserted into the communication hole 7 in FIG. 11), the seal cap 5 from a face 22c Protrusively toward. ₂ second projection 28 is provided at the other end 22b close to the communicating hole 7 in the circumferential direction, projecting toward the opposing surface 22c to the seal cap 5. Since the other structure of the circulation member 4 is the same as that of the circulation member 4 of the first embodiment, the same reference numerals are given and description thereof is omitted.

As shown in FIG. 12, the surface 28a ₁ of ₁ first projection 28 is formed on the plane. Between the surface 28a ₁ and the sealing cap 5, a gap g3 ₁ it is provided. The size of the gap g3 ₁ is not particularly limited, for example, 20 [mu] m ~ 40 [mu] m. Surface 28a ₂ of ₂ second projection 28 is also formed in a plane. A gap g < _b > 32 is provided between the surface 28 a ₂ and the seal cap 5. The size of the gap g3 ₂ is not particularly limited, for example, 20 [mu] m ~ 40 [mu] m. The gap g2 between the facing surface 22c and the seal cap 5 is, for example, 50 μm to 150 μm, similarly to the circulation member 4 of the first embodiment.

As a result of the demonstration experiment, it was possible to extend the life of the circulating member 4 by providing the circulating member 4 with the first and

second protrusions

28 ₁ and 28 ₂ .

It should be noted that the screw device of the present invention can be embodied in various forms, and is not limited to the embodiments described in this specification. This embodiment is provided with the intention of enabling those skilled in the art to fully understand the scope of the invention by fully disclosing the specification.

The shape of the concave portion and the shape of the circulation member of the present embodiment are examples, and other shapes can be adopted without changing the gist of the present invention. In this embodiment, the seal cap is fixed to the nut with a bolt, but may be fixed with a C-ring. In the present embodiment, the end face in the axial direction of the nut is slightly protruded from the end face of the flange, but the end face in the axial direction of the nut can be recessed from the end face of the flange. A roller can be used as a rolling element instead of a ball.

This specification is based on Japanese Patent Application No. 2015-014001 filed on Jan. 28, 2015 and Japanese Patent Application No. 2016-012901 filed on Jan. 27, 2016. All this content is included here.

DESCRIPTION OF SYMBOLS 1 ... Screw shaft, 1a ... Rolling element rolling groove, 2 ... Nut, 2a ... Through-hole, 2b ... Flange, 2c ... Load rolling element rolling groove, 2d, 2e ... End face of nut, 3 ... Ball (rolling element) 4 ... circulation member, 5 ... sealing cap (lid member), 7 ... communication hole, 8 ... recess, 11 ... recess for insertion, 12 ... recess for extension, 12a ... one end of extension for recess, 12b ... The other end portion of the recess for the overhang portion, 14 ... the movement limiting recess, 21 ... the insertion portion, 22 ... the overhang portion, 22a ... one end portion of the circulation member, 22b ... the other end portion of the circulation member, 22c ... the opposite surface of the circulation member, 23 ... first leg, 24 ... second leg, 25 ... raised portion, 26 ... rib, 27 ... movement restricting convex portion, 28 ... projection, 28 ₁ ... first projection, 28 ₂ ... second projections, 28a ... surface protrusions, 28a 1 _... the surface of the first projection, 28a 2 _... surface of the second projection, g ... gap, g2 ... gap, g3 ... gap, g3 1 _... gap, g3 2 _... gap

Claims

A screw shaft having a spiral rolling element rolling groove on the outer peripheral surface, and a spiral load rolling element facing the rolling element rolling groove on the inner peripheral surface, and having a through hole in which the screw shaft is rotatably arranged A nut having rolling grooves, and a plurality of rolling elements interposed between the rolling element rolling grooves of the screw shaft and the loaded rolling element rolling grooves of the nut so as to allow rolling motion,
The nut has a communication hole penetrating the nut in the axial direction, and has a recess communicating with the communication hole and the load rolling element rolling groove on an axial end surface;
In the rolling member screw device in which the circulation member having a direction change path connected to the load rolling element rolling groove and the communication hole of the nut is disposed in the concave portion of the nut,
A gap is provided between the circulation member and the wall surface of the recess so that the circulation member can move,
A screw device in which the circulating member disposed in the recess is covered with a lid member attached to the nut.
The circulation member has an insertion portion having the direction change path, and an overhang portion projecting outward from the insertion portion,
The said recessed part has the recessed part for insertion parts in which the said insertion part of the said circulation member is inserted, and the recessed part for overhang | projection parts by which the said overhang | projection part of the said circulation member is arrange | positioned. Screw device.
One end portion in the circumferential direction of the recess for the overhang portion is open toward the through hole so that the circulation member can rotate in one direction around the insertion portion,
The other end in the circumferential direction of the recess for the overhanging portion opens toward the through hole so that the circulating member can rotate in the other direction around the insertion portion,
The circulation member has a first leg portion that contacts a wall surface of the recess for the overhang portion before the circulation member that rotates in the other direction hits the screw shaft, at one end portion in the circumferential direction. 3. The screw according to claim 2, further comprising: a second leg that contacts the wall surface of the overhanging recess before the circulating member rotating in the one direction hits the screw shaft at the other end. apparatus.
The circulation member has a protrusion protruding toward the lid member from an opposing surface facing the lid member at one end portion away from the communication hole,
The screw device according to any one of claims 1 to 3, wherein a gap is provided between the facing surface of the circulation member and the lid member.
The circulating member has a first projection protruding from the facing surface facing the lid member toward the lid member at one end away from the communication hole, and at the other end near the communication hole, A second protrusion that protrudes from the facing surface facing the lid member toward the lid member;
The screw device according to any one of claims 1 to 3, wherein a gap is provided between the facing surface of the circulation member and the lid member.
A gap is provided between the protrusion and the lid member,
The screw device according to claim 4 or 5, wherein a gap is provided between the first and second protrusions and the lid member.
The recess has a movement limiting recess adjacent to the communication hole,
The circulation member has a movement restriction convex part arranged in the movement restriction concave part,
When the nut is viewed from the axial direction, the movement restricting concave portion and the movement restricting convex portion come into contact with each other, so that the circulating member moves the rolling element coming out of the communication hole toward the load rolling element rolling groove. The screw device according to any one of claims 1 to 6, wherein the screw device is restricted from moving in the X-axis direction.