Ball screw device

Abstract

To provide a ball screw device in which a cooling liquid flow passage is formed, being a ball screw device which is further suppressed in the number of part items.SOLUTION: A ball screw device comprises a nut, a screw shaft and balls. The nut has a nut main body in which a plurality of recessed grooves are formed at a first end face which is formed at an end part in an axial direction of at least either of one end part and the other end part of a center shaft in an axial direction, a plurality of first seal members fit into the plurality of recessed grooves, and one cap attached to an end part in the axial direction in a state of covering the plurality of recessed grooves of the first end face, and blocking a flow passage in a circumferential direction in which a cooling liquid flows in a circumferential direction in the recessed groove which makes end parts of two flow passages in the axial direction out of the plurality of flow passages in the axial direction communicate to each other.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a ball screw device. [Background technology]

[0002] A ball screw device, for example, includes a nut provided with an inner circumferential raceway groove, a screw shaft penetrating the nut and provided with an outer circumferential raceway groove, a plurality of balls arranged between the inner circumferential raceway groove and the outer circumferential raceway groove, and a coolant flow passage provided inside the nut through which a coolant flows (see Patent Document 1). The coolant flow passage includes an axial flow passage extending in the axial direction of the nut and a circumferential flow passage extending in the circumferential direction of the nut. The circumferential flow passage is formed by a circumferential groove formed at an axial end of the nut and opening to the axial outside, a seal member fitted into the circumferential groove to seal the circumferential groove, and a seal member that seals the circumferential groove in a state of contact with the seal member. A plurality of circumferential grooves are provided, and a plurality of seal members and sealing members are also provided corresponding to the respective circumferential grooves. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3217729 Summary of the Invention [Problem to be solved by the invention]

[0004] Thus, a plurality of sealing members corresponding to the plurality of circumferential grooves are also provided in Patent Document 1. In a ball screw device provided with a coolant flow path, it is desirable to reduce the number of parts.

[0005] The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide a ball screw device having a coolant flow path and having a reduced number of parts. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, a ball screw device according to one embodiment includes a nut having an inner circumferential raceway groove on its inner surface and having a plurality of axial flow paths through which a coolant flows in an axial direction, a screw shaft penetrating the nut and having an outer circumferential raceway groove on its outer circumferential surface, and a plurality of balls arranged between the inner circumferential raceway groove and the outer circumferential raceway groove, wherein the nut has a nut body having a plurality of grooves formed in a first end face arranged at at least one of an axial end portion and an axial end portion of a central shaft, a plurality of first seal members fitted into each of the plurality of grooves, and a cap attached to the axial end portion in a state covering the plurality of grooves on the first end face, and blocking a circumferential flow path through which a coolant flows in a circumferential direction through a groove that communicates between ends of two of the plurality of axial flow paths.

[0007] As described above, in the ball screw device according to Patent Document 1, a plurality of circumferential grooves are provided, and a plurality of sealing members are also provided corresponding to the respective circumferential grooves. The sealing members correspond to the caps of the present disclosure.

[0008] In contrast, in the present disclosure, one cap is attached to the nut while covering the multiple sealing members. Thus, while Patent Document 1 requires multiple sealing members equivalent to the caps of the present disclosure, the present disclosure requires only one cap, which reduces the number of parts, thereby reducing the cost of the ball screw device and the number of installation steps.

[0009] In a preferred embodiment, the recessed groove includes a first groove that is recessed from the first end face toward the axial center, an outer shape of the recess extends along the circumferential direction of the nut as viewed from the axial direction of the nut, and the first seal member is fitted into the first groove, and a second groove that is provided inside the first groove as viewed from the axial direction of the nut, recessed from the bottom of the first groove toward the axial center, and in which the ends of the two axial flow paths are exposed inside. Therefore, the seal member can be fitted into the first groove, and the second groove can form a circumferential flow path.

[0010] In a preferred embodiment, a deflector is provided at at least one of the axial ends of the nut body, and the cap abuts against the deflector. In this manner, since the deflector abuts against the cap, the axial positioning of the deflector can be performed with higher accuracy by the cap.

[0011] In a preferred embodiment, a recess recessed toward the center in the axial direction is provided on the second end surface of the deflector on the cap side, and a second seal member that abuts against the cap is fitted into the recess. Therefore, according to the present disclosure, more seal members can be attached with one cap, compared to a case in which a cap for attaching only the second seal member is separately provided in addition to a cap for attaching the first seal member. Effect of the Invention

[0012] According to the present disclosure, it is possible to provide a ball screw device having a cooling liquid flow path and having a reduced number of parts. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is an exploded perspective view of a ball screw device according to a first embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the ball screw device according to the first embodiment. [Diagram 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a diagram showing a state in which the cap is removed from FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] 7 is a cross-sectional view taken along line VII-VII in FIG. 3 with the seal member removed. [Figure 8]FIG. 8 is a schematic diagram showing the flow of the coolant in the coolant flow passage in the nut. [Figure 9] FIG. 9 is a cross-sectional view of a ball screw device according to the second embodiment. [Figure 10] FIG. 10 is a cross-sectional view of a ball screw device according to a third embodiment. [Figure 11] FIG. 11 is a cross-sectional view taken along line XI-XI in FIG. 10, showing a state in which the cap is removed. [Figure 12] FIG. 12 is a cross-sectional view of a ball screw device according to a fourth embodiment. [Figure 13] FIG. 13 is an enlarged cross-sectional view of a portion of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] A detailed description of the embodiment of the present invention will be given with reference to the drawings. The present invention is not limited to the contents described in the following embodiment. The components described below include those that a person skilled in the art can easily imagine and those that are substantially the same. The components described below can be appropriately combined. The same reference numerals are used for parts with the same structure, and the description is omitted. The X direction indicates the axial direction, and the Y and Z directions indicate the radial directions. The Y and Z directions are perpendicular (intersect) with the X direction. The Y direction is perpendicular (intersect) with the Z direction. The X1 side indicates one side in the axial direction, and the X2 side indicates the other side in the axial direction. The Y1 side is the opposite side to the Y2 side, and the Z1 side is the opposite side to the Z2 side.

[0015] [First embodiment] A first embodiment will be described below. Fig. 1 is an exploded perspective view of the ball screw device according to the first embodiment. Fig. 2 is a cross-sectional view of the ball screw device according to the first embodiment.

[0016] As shown in FIGS. 1 and 2, a ball screw device 100 according to a first embodiment includes a screw shaft 1, a nut 2, a plurality of balls 12, and a coolant flow path 4.

[0017] The screw shaft 1 extends in the X direction (axial direction) of the central axis AX. An outer circumferential raceway groove 11 is provided on the outer periphery of the screw shaft 1. The outer circumferential raceway groove 11 extends spirally.

[0018] The nut 2 includes a nut body 20, a seal member 5, and caps 30 and 31. The nut body 20 has a cylindrical portion 21 and a flange portion 22.

[0019] The cylindrical portion 21 extends in the X direction (axial direction) of the central axis AX. An inner circumferential raceway groove 222 is provided on the inner circumferential surface of the cylindrical portion 21. The screw shaft 1 penetrates the inner circumferential surface of the cylindrical portion 21. The inner circumferential raceway groove 222 extends in a spiral shape. A plurality of balls 12 are arranged between the inner circumferential raceway groove 222 and the outer circumferential raceway groove 11. The cylindrical portion 21 has a cylindrical surface 211 on the outer periphery. The cylindrical portion 21 and the cylindrical surface 211 extend in the circumferential direction around the central axis AX. The flange portion 22 is provided at the end of the nut body 20 on the X2 side (the other side in the axial direction). That is, the flange portion 22 protrudes radially outward from the end of the nut body 20 on the X2 side (see Figs. 3 and 4). A plurality of mounting holes 221 are provided penetrating the flange portion 22 in the axial direction.

[0020] A coolant flow passage 4 is formed inside the nut 2. The coolant 40 flows inside the coolant flow passage 4. As shown in FIG. 2, the coolant flow passage 4 includes, for example, an inlet 402 provided in the flange portion 22, and a first axial flow passage 43 and a second axial flow passage 45 provided in the nut body 20. A first end face 23 is provided at the end on the X1 side (one axial end 24) and the end on the X2 side (the other axial end 25) of the nut body 20. The first end face 23 extends in a radial direction perpendicular to (intersecting) the axial direction. FIG. 1 shows the first end face 23 provided at the one axial end 24. A recessed groove 26 and a tapped hole 232 are formed in the first end face 23. A seal member 5 is fitted in the recessed groove 26. A central hole 301 is provided in the cap 30 at the radial center, and a plurality of bolt holes 302 are provided along the circumferential direction. The cap 30 has an annular shape. The bolt BL is passed through the bolt hole 302 of the cap 30 and fastened to the tapped hole 232. As a result, the cap 30 is attached to the one end portion 24 in the axial direction with the cap 30 covering the first end face 23, and the recessed groove 26 is sealed.

[0021] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 2. Fig. 5 is a view showing a state in which the cap is removed from Fig. 4.

[0022] 3 and 5, an outlet 401 is provided on the Z1 side of the flange portion 22, and an inlet 402 is provided midway between the Z1 side and the Y1 side. The coolant 40 flows into the coolant flow path 4 from the inlet 402, and then flows out from the outlet 401.

[0023] As shown in Fig. 3, two seal members (first seal members) 51 are provided at one axial end 24 of the nut body 20. Specifically, one seal member 51 extends circumferentially from the Z1 side to the Y2 side of the first end face 23. The one seal member 51 overlaps with the first circumferential flow passage 42 when viewed from the axial direction. The first circumferential flow passage 42 extends circumferentially of the nut body 20. The first circumferential flow passage 42 extends circumferentially of the nut body 20 from a flow passage end 421 to a flow passage end 422.

[0024] The other seal member 51 extends circumferentially from the Y1 side to the Z2 side of the first end face 23. The other seal member 51 overlaps with the third circumferential flow passage 46 when viewed from the axial direction. The third circumferential flow passage 46 extends circumferentially of the nut body 20 from a flow passage end 461 to a flow passage end 462.

[0025] As shown in FIG. 5, an O-ring (first seal member) 50, a seal member 51, and a seal member (first seal member) 52 are provided at the other end 25 in the axial direction of the nut body 20. Specifically, the O-ring 50 is provided at a flow path end 431 described later. The seal member 51 extends along the circumferential direction from the Y2 side to the Z2 side of the first end face 23. The seal member 51 overlaps with the second circumferential flow path 44 when viewed from the axial direction. The second circumferential flow path 44 extends along the circumferential direction of the nut body 20 from the flow path end 441 to the flow path end 442. The seal member 52 extends along the circumferential direction from the middle between the Z1 side and the Y1 side of the first end face 23 to the Y1 side. The seal member 52 overlaps with the fourth circumferential flow path 48 when viewed from the axial direction. The fourth circumferential flow path 48 extends along the circumferential direction of the nut body 20 from the flow path end 481 to the flow path end 482.

[0026] Fig. 6 is a cross-sectional view taken along line VI-VI in Fig. 3. Fig. 7 is a cross-sectional view taken along line VII-VII in Fig. 3 with the seal member removed.

[0027] 8, a recessed groove 26 is provided in each of one axial end portion (axial end portion) 24 and the other axial end portion (axial end portion) 25 of the nut body 20. The recessed groove 26 provided in the one axial end portion 24 will be described below, but the recessed groove 26 provided in the other end portion 25 has the same configuration.

[0028] As shown in FIG. 7, the recessed groove 26 includes a first groove 261 and a second groove 262. As shown in FIG. 7, the first groove 261 is recessed from the first end face 23 toward the X2 side (the center side in the axial direction). The first groove 261 faces inner walls 261a, 261b and first bottom faces 261c, 261d. The inner walls 261a, 261b extend toward the X2 side perpendicularly (intersecting) the first end face 23. The inner walls 261a and 261b face each other in the radial direction. The first bottom faces 261c, 261d extend along the first end face 23. Specifically, the first bottom face 261c extends toward the Z2 side from the end of the inner wall 261a on the X2 side. The first bottom face 261d extends toward the Z1 side from the end of the inner wall 261b on the X2 side. The width of the first groove 261 in the radial direction is width W10.

[0029] As shown in FIG. 7, the second groove 262 is recessed from the first bottom surfaces 261c, 261d toward the X2 side (the center side in the axial direction). The second groove 262 communicates with the first groove 261. The second groove 262 faces the inner walls 262a, 262b and the second bottom surface 262c. The inner walls 262a, 262b are perpendicular (intersect) with the first end surface 23 and extend toward the X2 side. The inner walls 262a and 262b face each other in the radial direction. The second bottom surface 262c extends along the first end surface 23. The second bottom surface 262c connects the end of the inner wall 262a on the X2 side and the end of the inner wall 262b on the X2 side. The first groove 261 and the second groove 262 each have a rectangular cross section as shown by the two-dot chain line. The width of the second groove 262 in the radial direction is width W20. Width W10 is greater than width W20. Therefore, when the recessed groove 26 is viewed from the axial direction, the first bottom surfaces 261c and 261d are exposed.

[0030] 6, in a cross section of a portion overlapping with the third axial flow passage 47 as viewed in the axial direction, the first groove 261 and the second groove 262 communicate with the third axial flow passage 47. That is, as shown in Fig. 6 and Fig. 7, the first groove 261 and the second groove 262 form the third circumferential flow passage 46. Note that the other circumferential flow passages, that is, the first circumferential flow passage 42, the second circumferential flow passage 44, and the fourth circumferential flow passage 48, are also formed by the first groove 261 and the second groove 262.

[0031] Here, the seal member 51 is fitted into the first groove 261. Specifically, the seal member 51 is accommodated in the first groove 261 in a state in which the seal member 51 abuts against the inner walls 261a, 261b, the first bottom surfaces 261c, 261d, and the rear surface 30a of the cap 30. As a result, the recessed groove 26 is sealed by the cap 30.

[0032] Next, the flow of the coolant will be described with reference to Fig. 8, which is a schematic diagram showing the flow of the coolant in the coolant flow passage in the nut.

[0033] 8, the axial flow passage 410 includes a first axial flow passage 43, a second axial flow passage 45, a third axial flow passage 47, and a fourth axial flow passage 49. The circumferential flow passage 420 includes a first circumferential flow passage 42, a second circumferential flow passage 44, a third circumferential flow passage 46, and a fourth circumferential flow passage 48.

[0034] First, as shown in FIG. 8, the coolant 40 flows from the inlet 402 into the first axial flow passage 43 through the flow passage end 431. The first axial flow passage 43 has flow passage ends 431 and 432. That is, the coolant 40 flows from the flow passage end 431 to the flow passage end 432. Thereafter, the coolant 40 flows along the first circumferential flow passage 42 from the flow passage end 421 to the flow passage end 422, and flows along the second axial flow passage 45 from the flow passage end 451 to the flow passage end 452. Thereafter, the coolant 40 flows along the second circumferential flow passage 44 from the flow passage end 441 to the flow passage end 442, flows along the third axial flow passage 47 from the flow passage end 471 to the flow passage end 472, and flows along the third circumferential flow passage 46 from the flow passage end 461 to the flow passage end 462. Then, the cooling liquid 40 flows along the fourth axial flow passage 49 from the flow passage end 491 to the flow passage end 492, flows along the fourth circumferential flow passage 48 from the flow passage end 481 to the flow passage end 482, and then flows out of the nut 2 from the outlet 401. In this way, the cooling liquid 40 flows alternately through the axial flow passages 410 and the circumferential flow passages 420, thereby uniformly cooling the entire nut 2.

[0035] As described above, the ball screw device 100 of the first embodiment comprises the nut 2 having an inner circumferential raceway groove 222 on its inner surface and a plurality of axial flow paths 410 through which coolant 40 flows in the axial direction, the screw shaft 1 penetrating the nut 2 and having an outer circumferential raceway groove 11 on its outer circumferential surface, and a plurality of balls 12 arranged between the inner circumferential raceway groove 222 and the outer circumferential raceway groove 11. The nut 2 has a nut body 20 having a first end face 23 disposed at at least one of the axial ends of one end and the other end in the axial direction of the central axis AX, and a sealing member (a plurality of first sealing members) 51, 52 fitted into each of the plurality of grooves 26, and one cap 30, 31 attached to the axial end in a state covering the plurality of grooves 26 of the first end face 23 and the plurality of sealing members 51, 5 and an O-ring 50, and blocking a circumferential flow path 420 through which the coolant 40 flows circumferentially through the groove 26 that communicates between the ends of two of the plurality of axial flow paths 410.

[0036] As described above, in the ball screw device according to Patent Document 1, a plurality of circumferential grooves are provided, and a plurality of seal members and sealing members corresponding to the respective circumferential grooves are also provided. The sealing members correspond to the caps 30 and 31 in this embodiment.

[0037] In contrast, in this embodiment, one cap 30, 31 is attached to the nut body 20 while covering the multiple sealing members 51, 52 and the O-ring 50. Thus, while Patent Document 1 requires multiple sealing members equivalent to the caps 30, 31 of this embodiment, this embodiment requires only one cap 30, 31, which reduces the number of parts, and therefore reduces the cost of the caps 30, 31 and the labor required for installation.

[0038] In addition, the recessed groove 26 is a recess that recesses from the first end face 23 toward the axial center, and when viewed in the axial direction of the nut 2, the outer shape of the recess extends along the circumferential direction of the nut 2, and includes a first groove 261 into which the sealing members 51, 52 fit, and a second groove 262 that is provided inside the first groove 261 when viewed in the axial direction of the nut 2, and is recessed from the bottom of the first groove 261 toward the axial center, with the ends of the two axial flow paths 410 exposed to the inside.

[0039] Therefore, the seal members 51 and 52 can be fitted into the first groove 261 and the circumferential flow passage 420 can be formed by the second groove 262 .

[0040] [Second embodiment] The second embodiment will be described below. Fig. 9 is a cross-sectional view of a ball screw device according to the second embodiment. In the ball screw device 100A according to the second embodiment, a seal member (first seal member) 53 and a seal member (first seal member) 54 are provided on the first end face 23. This will be described in detail below.

[0041] As shown in FIG. 9, the nut body 20 has a first end surface 23 at its end on the X1 side (one axial end 24) and at its end on the X2 side (the other axial end 25). The first end surface 23 on the X1 side has a recess 27. The recess 27 is located radially inside the recessed groove 26. A ring-shaped seal member 53 is accommodated in the recess 27. The thickness of the seal member 53 is equal to or greater than the depth of the recess 27. The O-ring 50 (see FIG. 5), the seal member 51 (see FIG. 5), the seal member 52 (see FIG. 5), and the seal member 53 are covered with the cap 30. That is, in a state in which the O-ring 50, the seal member 51, the seal member 52, and the seal member 53 are covered with the cap 30, the cap 30 is fastened to the axial end 24 of the nut body 20 via a bolt (not shown).

[0042] A recess 28 is provided on the first end face 23 on the X2 side. The recess 28 is located radially inside the recessed groove 26. An annular seal member 54 is housed in the recess 28. The thickness of the seal member 54 is equal to or greater than the depth of the recess 28. The O-ring 50 (see FIG. 5), the seal member 51 (see FIG. 5), the seal member 52 (see FIG. 5), and the seal member 54 are covered with the cap 31. That is, with the O-ring 50, the seal member 51, the seal member 52, and the seal member 54 covered with the cap 31, the cap 31 is fastened to the other axial end 25 of the nut body 20 via a bolt (not shown).

[0043] As described above, in the second embodiment, in addition to the O-ring 50, the seal member 51, and the seal member 52, the seal members 53 and 54 are attached to the nut body 20 while being covered with the caps 30 and 31, respectively. Therefore, the seal members 53 and 54 are also attached by the caps 30 and 31, respectively. Therefore, compared with the case where a cap to which only the seal member 53 is attached and a cap to which only the seal member 54 is attached are provided, according to this embodiment, even more seal members can be attached by one cap 30, 31.

[0044] [Third embodiment] The third embodiment will be described below. Fig. 10 is a cross-sectional view of the ball screw device according to the third embodiment. Fig. 11 is a cross-sectional view taken along line XI-XI in Fig. 10, showing a state in which the cap is removed. In the ball screw device 100B according to the second embodiment, deflectors 6 and 7 are provided at one end 24 and the other end 25 in the axial direction of the nut body 20. This will be described in detail below.

[0045] As shown in Fig. 10, a through hole 29 extending along the X direction (axial direction) is provided inside the nut body 20. The balls 12 pass through the inside of the through hole 29 along the X direction. A deflector 6 is provided at one axial end 24 (end on the X1 side) of the nut body 20, and a deflector 7 is provided at the other axial end 25 (end on the X2 side). That is, the deflectors 6 and 7 according to this embodiment are end deflectors. Note that, as shown in Fig. 11, the deflectors 6 and 7 are located on the Z1 side and the Y2 side as viewed from the X direction.

[0046] As shown in FIG. 10, the deflector 6 is provided with a scooping passage 61. One end 61a of the scooping passage 61 is located on the Z2 side of the deflector 6 and faces the outer circumferential raceway groove 11 on the outer periphery of the screw shaft 1. The other end 61b of the scooping passage 61 is located on the X2 side of the deflector 6 and communicates with the through hole 29. An end face 62 on the X2 side of the deflector 6 abuts on the end 20b on the X1 side of the radially inner part 20a of the nut body 20. A second end face 63 on the X1 side of the deflector 6 abuts on the back surface 30a of the cap 30. An inner surface 64 of the deflector 6 is in the same radial position as the inner surface 20d of the nut body 20. In other words, the inner surface 64 of the deflector 6 is flush with the inner surface 20d of the nut body 20.

[0047] 10, the deflector 7 is provided with a scooping passage 71. One end 71a of the scooping passage 71 is located on the Z2 side of the deflector 7 and faces the outer circumferential raceway groove 11 on the outer periphery of the screw shaft 1. The other end 71b of the scooping passage 71 is located on the X1 side of the deflector 7 and communicates with the through hole 29. An end face 72 on the X1 side of the deflector 7 abuts against an end 20c on the X2 side of the radially inner part 20a of the nut body 20. A second end face 73 on the X1 side of the deflector 7 abuts against a back surface 31a of the cap 31.

[0048] 10, the ball 12 moving along the outer peripheral raceway groove 11 of the screw shaft 1 is scooped up from the scooping passage 61 of the deflector 6 and moves axially through the through hole 29 toward the X2 side. Then, the ball 12 passes through the scooping passage 71 of the deflector 7 and returns to the outer peripheral raceway groove 11 of the screw shaft 1. When the rotation direction of the screw shaft 1 is reversed, the ball 12 moves from the scooping passage 71 of the deflector 7 through the through hole 29 toward the X1 side, and then returns to the outer peripheral raceway groove 11 of the screw shaft 1 from the scooping passage 61.

[0049] As described above, the deflectors 6, 7 are provided at least on one or the other axial end of the nut body 20, and the caps 30, 31 abut against the deflectors 6, 7, respectively.

[0050] In this manner, the X1-side end face 72 of the deflector 7 abuts against the X2-side end face 20c of the radially inner portion 20a of the nut body 20, and the X1-side second end face 73 of the deflector 7 abuts against the back surface 31a of the cap 31. Therefore, the caps 30 and 31 allow the deflector 7 to be positioned in the X direction with higher accuracy.

[0051] [Fourth embodiment] The fourth embodiment will be described below. Fig. 12 is a cross-sectional view of the ball screw device according to the fourth embodiment. Fig. 13 is a cross-sectional view of an enlarged portion of Fig. 12. The ball screw device 100C according to the fourth embodiment is provided with a seal member 53 and a seal member 54 on the first end surface 23, in comparison with the ball screw device 100B according to the third embodiment. This will be described in detail below.

[0052] As shown in FIG. 12, a deflector 6 is provided at one end 24 (end on the X1 side) in the axial direction of the nut body 20, and a deflector 7 is provided at the other end 25 (end on the X2 side) in the axial direction of the nut body 20. A recess 27A is provided at a second end face 63 on the X1 side of the deflector 6. A ring-shaped seal member (second seal member) 53 is accommodated in the recess 27A. The thickness of the seal member 53 is equal to or greater than the depth of the recess 27A. The seal member 53 is covered with the cap 30. That is, in a state where the seal member 53 is covered with the cap 30, the cap 30 is fastened to the one end 24 in the axial direction of the nut body 20 via a bolt (not shown). The seal member 53 and the second end face 63 abut against the back surface 30a of the cap 30.

[0053] As shown in Figs. 12 and 13, a recess 28A is provided on the second end surface 73 on the X2 side of the deflector 7. A ring-shaped seal member (second seal member) 54 is housed in the recess 28A. The thickness of the seal member 54 is equal to or greater than the depth of the recess 28A. The seal member 54 is covered with the cap 31. That is, in a state in which the seal member 54 is covered with the cap 31, the cap 31 is fastened to the other axial end portion 25 of the nut body 20 via a bolt (not shown). The seal member 54 and the second end surface 73 abut against the back surface 31a of the cap 31.

[0054] As described above, the second end faces 63, 73 of the deflectors 6A, 7A facing the caps 30, 31 are provided with recesses 27A, 28A recessed toward the axial center, and the seal members (second seal members) 53, 54 that abut against the caps 30, 31 are fitted into the recesses 27A, 28A.

[0055] Therefore, compared with the case where a cap to which only the seal member 53 is attached and a cap to which only the seal member 54 is attached are provided, according to this embodiment, more seal members can be attached to one cap 30, 31. [Explanation of symbols]

[0056] 1 Screw shaft 11 Outer raceway groove 12 Ball 100, 100A, 100B, 100C Ball screw device 2 Nuts 20 Nut body 20a Radial inner part 20b, 20c end 20d Inner surface 21 Cylindrical part 211 Cylindrical Surface 22 Flange 221 Mounting hole 222 Inner raceway groove 23 First end surface 232 Tapped hole 24 One end in the axial direction (axial end) 25 Other end in the axial direction (axial end) 26 Groove 261 First groove 261a Interior wall 261b Interior wall 261c 1st bottom surface (bottom) 261d 1st bottom surface (bottom) 262 2nd groove 262a Interior wall 262b Interior wall 262c 2nd bottom 27, 27A, 28, 28A recess 29 Through hole 30 Cap 30a back 301 Central hole 302 Bolt hole 31 Cap 31a back 4 Coolant flow path 40 Coolant 401 Outlet 402 Inlet 410 Axial flow passage 420 Circumferential flow path 42 First circumferential flow passage (circumferential flow passage) 421 Channel End 422 Channel End 43 First axial passage (axial passage) 431 Channel End 432 Channel End 44 Second circumferential flow passage (circumferential flow passage) 441 Channel End 442 Channel End 45 Second axial flow passage (axial flow passage) 451 Channel End 452 Channel End 46 3rd circumferential flow passage (circumferential flow passage) 461 Channel End 462 Channel End 47 Third axial flow passage (axial flow passage) 471 Channel End 472 Channel End 48 4th circumferential flow passage (circumferential flow passage) 481 Channel End 482 Channel End 49 4th axial flow passage (axial flow passage) 491 Channel End 492 Channel End 5 Sealing material 50 O-ring 51 sealing member (first sealing member) 52 sealing member (first sealing member) 53, 54 Seal member (second seal member) 6, 6A, 7, 7A Deflector 61, 71 Scooping passage 61a one end 61b Other end 62, 72 end face 63, 73 2nd end face 64 Inside AX center axis BL Bolt

Claims

1. a nut having a plurality of axial flow passages through which a coolant flows in an axial direction and which are spaced apart in a circumferential direction, and a plurality of recessed grooves extending in a circumferential direction and connecting axial ends of two axial flow passages adjacent in the circumferential direction, and having an inner circumferential raceway groove provided on an inner circumferential surface; a screw shaft that penetrates the nut and has an outer circumferential raceway groove on its outer circumferential surface; a plurality of balls disposed between the inner circumferential raceway groove and the outer circumferential raceway groove, The nut is A nut body having a first end surface disposed at at least one of an axial end portion and an axial end portion of a central shaft, the first end surface being provided with the plurality of recessed grooves; A plurality of first seal members each having an annular shape that extends along the circumferential direction of the nut and has a through-hole that penetrates in the axial direction on the inside, and that fit into each of the plurality of grooves; and a cap that closes the axial end of the nut body with the first seal member fitted in the plurality of recessed grooves on the first end surface. The groove is a first groove in which the first seal member is fitted, the first groove being a recess extending from the first end face toward a center in the axial direction, the outer shape of the recess extending along a circumferential direction of the nut when viewed from the axial direction of the nut; A second groove is recessed from a bottom of the first groove toward the axial center, and is provided on the inside of the first groove as viewed in the axial direction of the nut and communicates with the axial end of the axial flow path. a circumferential flow path through which a coolant flows in a circumferential direction is formed by the second groove, the through portion of the first seal member, and the cap abutting against the first seal member; Ball screw device.

2. A deflector is provided at at least one of the axial end portions of the nut body and the other axial end portion, The cap abuts against the deflector. The ball screw device according to claim 1 .

3. A recess is provided on a second end surface of the deflector facing the cap, the recess being recessed toward a center in the axial direction. A second seal member that abuts against the cap is fitted into the recess. The ball screw device according to claim 2 .

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