BALL DEFLECTOR FOR A BALL SCREW

Abstract

A ball screw including a threaded spindle and a spindle nut has a ball deflector arranged in an opening in the lateral surface of the spindle nut. The ball deflector is formed with an upper shell and a lower shell, the lower shell being arranged radially inwardly closer to the spindle nut longitudinal axis than the upper shell. The lower shell has a substantially half-shell-shaped contour. Both the upper shell and the lower shell are fastened in the spindle nut without any further, discrete mechanical fastening elements, and the ball deflector formed thereby does not protrude beyond the outer contour defined by the spindle nut.

Claims

1. A ball screw, comprising: a threaded spindle (12); a spindle nut (14) that coaxially at least partially encloses the threaded spindle (12); a plurality of balls adapted to circulate in an interstice between the threaded spindle (12) and the spindle nut (14); a ball deflector arranged in an opening (17) in a lateral surface of the spindle nut (14), the ball deflector comprising an upper shell (26) and a lower shell (25), the upper shell (26) being arranged radially inwardly closer to a longitudinal axis of the spindle nut than the upper shell (25); the lower shell having a substantially half-shell-shaped contour; and the upper shell (26) and the lower shell (25) are fastened in the spindle nut (14) without any further, discrete, mechanical fastening elements.

2. The ball screw according to claim 1, wherein the lower shell (26) and the upper shell (25) mounted in the spindle nut (14) dos not protrude beyond an outer contour defined by the spindle nut.

3. The ball screw according to claim 1, wherein the lower shell (25) comprises a moulded part, a deep-drawn part, a punched or stamped part, or an injection-moulded part, and is formed of metal or plastic.

4. The ball screw according to claim 1, wherein the lower shell (25) and the spindle nut (14) are connected by fusing, caulking, clamping, spot-welding or laser welding.

5. The ball screw according to claim 1, wherein the upper shell (26) comprises a moulded part, a deep-drawn part, a punched or stamped part, or an injection-moulded part, and is formed of metal or plastic.

6. The ball screw according to claim 1, wherein the upper shell (26) and the spindle nut (14) are connected by fusing, caulking, clamping, spot-welding or laser welding.

7. The ball screw according to claim 1, wherein the upper shell (26) and the spindle nut (14) are connected by a locking element comprising a spring element (30) on the upper shell (26) which, in an assembled state, engages in a groove (32) in a side wall of the opening (17) in the spindle nut (14) and secures the upper shell (26) in a defined position in the opening (17).

8. The ball screw according to claim 1, wherein the opening (17) is defined by side walls which are inclined conically inwards towards an outer face of the spindle nut (14) such that a bottom of the opening has a larger clearance than at an edge of the opening (17) at a surface of the spindle nut.

9. The ball screw according to claim 1, wherein the ball deflection channel (28) is formed at least in some sections by the upper shell (26), the lower shell (25) and side walls that define the opening (17) in an assembled state.

10. The ball screw according to claim 9, wherein the upper shell is an extended upper shell (40) which is formed of plastic, in a single piece, and is formed so as to entirely or mostly enclose the spindle nut (14) in an annular manner.

11. The ball screw according to claim 10, further comprising an extended upper shell (40) including an insert part for the opening (17), said insert part terminates at least one of the ball deflection channel (28) or the opening (17) to outside and is formed integrally to the single-piece, extended upper shell (40) by overmoulding the spindle nut (14).

12. A method for assembling a ball screw having the following method steps: providing a spindle nut (14); inserting a lower shell (25) into an opening (17) in the spindle nut (14) in a desired position for the lower shell (25); and fastening the lower shell (25) to the spindle nut (14) by fusing, caulking, clamping, spot-welding or laser-welding.

13. The method according to claim 12, further comprising: arranging an upper shell (26) in the opening (17) in a desired position, and fastening the upper shell (26) to the spindle nut (14) only by fusing, caulking, clamping, spot-welding or laser-welding.

14. The method according to claim 12, further comprising: providing the extended upper shell (40) formed of plastic; and mounting the upper shell by being pushed onto the spindle nut (14).

15. The method according to claim 12, further comprising: inserting an upper shell (26) formed of plastic into the opening (17) in the spindle nut (14) until a spring element (30) on the upper shell (26) engages in a groove (32) in a side wall that defines the opening (17) in the spindle nut (14) in a locking manner, to hold the upper shell (26) in a defined position.

16. The method according to claim 12, further comprising: inserting an upper shell (26) formed of plastic that is elastically deformable and into the opening (17) in the spindle nut (14) which has tapered sidewalls (17) forming a clamping fit between the upper shell and the opening in a desired end position.

17. The method according to claim 12, further comprising: inserting an upper shell (26) formed of plastic into an insert as a semi-finished product; placing the spindle nut (14) into a die of a plastic injection-moulding machine which encloses the spindle nut; and overmoulding the spindle nut such that the upper shell (26) becomes an integral constituent of an extended upper shell (40).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 shows a ball screw according to the prior art.

[0030] FIG. 2 shows a spindle nut 14 in a perspective plan view with a sectional plane Q and an oblique sectional plane S.

[0031] FIG. 3 shows a spindle nut 14 in an oblique section view along the sectional plane S, according to one embodiment of the invention.

[0032] FIG. 4 shows the spindle nut 14 in a perspective view, according to one embodiment of the invention.

[0033] FIG. 5 shows the spindle nut 14 with a ball deflection channel in a caulked design in a cross-sectional view.

[0034] FIG. 6 shows a cross-sectional view taken along the sectional plane Q at the end of a ball deflection channel, having an anchoring with a click-in design.

[0035] FIG. 7 shows a detail X from FIG. 6.

[0036] FIG. 8 shows the fixing of an upper shell in an opening having conically tapering walls

[0037] FIG. 9 shows, along a sectional plane S, a spindle nut 14 with an over-moulded design with an extended upper shell 40.

DETAILED DESCRIPTION

[0038] The invention is now explained by way of example using embodiments, with reference to the attached drawings.

[0039] FIG. 1 shows a ball screw 10 according to the prior art and has already been explained above. FIG. 2 is used to understand the sectional planes of FIGS. 3-9 better. The position of a cross-sectional plane and of an oblique sectional plane are indicated. The oblique sectional plane S is designed such that it intersects a ball deflection channel, running in an opening 17, lengthways.

[0040] FIG. 3 shows an embodiment of a ball screw according to the invention having a spindle nut 14 in oblique section S, which also shows the ball deflection flutes 20. A ball deflector is mounted in the opening 17 without a sleeve 18 and forms the ball deflection channel 28. The lower shell 25 is a half-shell design, a relatively shallow component. The upper shell 26 is likewise shown as a shallow shaped sheet metal part. The longitudinal ends are supported on protrusions made in the opening.

[0041] FIG. 4 shows this variant in a view from above. The upper shell(s) 26 cover the opening(s) 17. According to the invention, no further securing straps, screw-fastenings or securing sleeves are necessary.

[0042] FIG. 5 shows the caulking fastening type in cross-section. A relative shallow lower shell 15 and an upper shell 26 with a tunnel profile for the ball deflection channel 28 are arranged in the opening 17 in the spindle nut 14. The caulking process has formed two protrusions, noses or webs 22, 24 on the edge of the opening, which secure the ball deflector in place.

[0043] FIGS. 6 and 7 show the fastening type with a clip or spring element 30 in a groove 32. The assembly or insertion direction is indicated by an arrow 34. The locking occurs when the spring element 30 can engage in the groove 32.

[0044] FIG. 8 illustrates the fastening type of a combination of lower shell 25 and upper shell 26 in an opening 17 with upwardly (radially outwardly) conically tapering side walls 36, 38. The achieved clamping fit of the upper shell 26 can clearly be seen.

[0045] FIG. 9 shows a ball nut 14 which is over-moulded with plastic and thus obtains an extended upper shell 40. The lower shell 25 is installed as described above, while the upper half of the ball deflection channel 28 is produced as a single piece by the injection-moulding process, in which an inserted semi-finished product or insert part has predefined the upper shell.

[0046] The features of the invention disclosed in the above description, in the drawings and in the claims can be essential to the realisation of the invention both individually and in any desired but technically practical or advantageous combination.

LIST OF REFERENCE SYMBOLS

[0047] 10 Ball screw [0048] 12 Threaded spindle [0049] 14 Spindle nut [0050] 15 Ball deflector, second part [0051] 16 Ball deflector, first part [0052] 17 Opening [0053] 18 Sleeve [0054] 19 Nut body [0055] 20 Ball circulation flute in spindle nut [0056] 22, 24 Nose, web [0057] 25 Lower shell [0058] 26 Upper shell [0059] 28 Ball deflection channel [0060] 30 Spring element [0061] 32 Groove, flute, undercut [0062] 34 Assembly direction [0063] 36, 38 Side wall (of opening 17 in spindle nut 14) [0064] 40 Extended upper shell