BALL SCREW DRIVE

Abstract

A ball screw drive includes a threaded spindle and a spindle nut with a plurality of balls that circulate endlessly in the intermediate space between the nut and the spindle. A ball return guide guides balls at one location out of the helical ball race by a ball deflector and feeds the balls back via a transition channel and another ball deflector. The ball deflectors are arranged in radial through-openings in the lateral surface of the nut. One or more small metal plates are provided on the nut, and are arranged in and/or adjacent to the radial through-openings and offset inwardly away from the lateral surface, and span the ball return guide in a planar manner. The ball return guide is fixed in a target position in the lateral surface of the nut, and when fully assembled the small metal plates do not protrude beyond the lateral surface.

Claims

1. A ball screw drive, comprising: a threaded spindle; a spindle nut which at least partially coaxially encloses the threaded spindle, the spindle nut has a substantially cylindrical lateral surface; a plurality of balls which circulate in an intermediate space between the threaded spindle and the spindle nut in a helical ball race; a ball return guide with two ball deflectors and a transition channel running therebetween; the ball deflectors are arranged in radial through-openings in the spindle nut such that, depending on a direction of rotation of the ball screw drive, the balls are radially lifted out of the ball race by one of the ball deflectors and are deflected into the transition channel, and after passing through the transition channel are guided by an other of the ball deflectors out of the transition channel back into the ball race; one or more metal plates on the spindle nut, the metal plates being arranged at least one of in or adjacent to the radial through-openings and being offset inwardly away from the lateral surface, and spanning the ball return guide in a planar manner to fix the ball return guide with the ball deflectors in a target position in the lateral surface of the spindle nut, and upon being fully assembled, the metal plates do not protrude beyond the lateral surface of the spindle nut.

2. The ball screw drive as claimed in claim 1, wherein at least one of in or adjacent to the through-openings of the spindle nut, the one or more metal plates are spot welded, adhesively bonded or clamped to the spindle nut.

3. The ball screw drive as claimed in claim 1, wherein the transition channel is configured as a longitudinally pressed-in, radially outwardly open channel or as a longitudinal bore which is introduced into the lateral surface of the spindle nut parallel to an axis of rotation of the spindle nut.

4. The ball screw drive as claimed in claim 1, wherein the ball return guide comprises a single piece with the two ball deflectors and the tubular transition channel that forms the transition arranged therebetween.

5. The ball screw drive as claimed in claim 1, wherein the ball return guide comprises the two ball deflectors which are each formed in one piece and which are separately inserted into the radial through-openings and a longitudinal bore located in the spindle nut therebetween as the transition channel.

6. The ball screw drive as claimed in claim 1, wherein in in a fully assembled position, the one or more metal plates terminate flush with the lateral surface of the spindle nut.

7. The ball screw drive as claimed in claim 1, wherein in a fully assembled position, the one or more metal plates are arranged to be at least partially countersunk in the lateral surface of the spindle nut.

8. The ball screw drive as claimed in claim 1, wherein the one or more metal plates provide a resilient pressing contact to ensure the fixing of at least one of the ball deflectors or the ball return guide to the spindle nut.

9. The ball screw drive as claimed in claim 1, further comprising at least one of a damping or resilient intermediate layer between the one or more metal plates and the ball return guide or at least one of the ball deflectors.

10. The ball screw drive as claimed in claim 1, wherein the one or more metal plates are produced from spring steel.

11. The ball screw drive as claimed in claim 1, wherein the one or more metal plates have a bulge along one axis and during assembly are oriented such that in a final assembled position the one or more metal plate exerts a continuous compressive force on at least one of the ball return guide or the ball deflectors.

12. The ball screw drive as claimed in claim 1, wherein one of the at least one metal plate closes a radial through-opening over an entire surface.

13. The ball screw drive as claimed in claim 1, wherein the at least one metal plate partially covers the radial through-opening.

14. The ball screw drive as claimed in claim 1, wherein the at least one metal plate at least partially covers a plurality of radial through-openings.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 shows schematically in a partial section a ball screw drive in a first embodiment of the invention.

[0037] FIG. 2 shows a ball screw drive with the spindle nut omitted. This illustrates the circulation of the balls.

[0038] FIG. 3 shows a longitudinal section through a ball screw drive in a second embodiment.

[0039] FIG. 4 shows a plan view of a ball screw drive in a third embodiment.

[0040] FIG. 5 shows a fourth embodiment of the invention.

DETAILED DESCRIPTION

[0041] FIG. 1 shows a ball screw drive 100 in a partial section. The internal threaded spindle 110 comprises the internal half of the helical ball race 140 which cooperates with its corresponding counterpart, the channel designed as an internal thread of the spindle nut 120. The balls 130 circulate endlessly due to the ball return guide. The ball return guide in this case is made up of a first ball deflector 150, a transition channel 160 and a further ball deflector 150′. The ball deflectors 150, 150′ are countersunk in through-openings 170, 170′, which in turn are closed by small metal plates 180, 180′. The through-openings are bores or milled portions in the spindle nut 120, which extend radially from the inside to the outside and serve for receiving the ball deflectors. The ball deflectors are designed as tubular or groove-shaped structural elements such that they remove the load from the balls of the ball race 140 and divert the balls both radially outwardly and toward the transition channel. As already mentioned, there are many types of transition channel: as axially parallel grooves or bores in the spindle nut, as discrete components or as assembled elements made of metal and/or plastics.

[0042] The spindle nut is shown here as a substantially cylindrical body with a radially enlarged flange 190.

[0043] FIG. 2 shows by way of illustration the endless circulation of the balls in a ball screw drive with the spindle nut omitted. The balls 130 are guided in the spiral ball race 140. A ball deflector 150 removes the balls from the ball race, guides the balls into the transition channel 160 at which a further ball deflector 150′ feeds the balls 130 back into the ball race 140.

[0044] FIG. 3 shows a second embodiment of the invention in longitudinal section. The ball screw drive 100 consists once again of the threaded spindle 100 and the spindle nut 120 which form therebetween the helical ball race 140 with the balls 130 guided therein. The ball return guide is implemented in a recess in the spindle nut 120, which also encompasses the through-openings for the inserted ball deflectors 150, 150′. It can be identified that in this embodiment the small metal plate 180 forms the outwardly or upwardly closing top of the transition channel 160. The portion of the transition channel 160 shown horizontally in the figure is implemented as a milled-out groove.

[0045] FIG. 4 shows one implementation of a ball screw drive, wherein the threaded spindle 110 is shown separately. The transition channel is implemented as an axially parallel longitudinal bore 210. It is only possible to identify the small metal plates 180, 180′ which form the closure of the radial through-openings which receive the ball deflectors. It can be identified that these small metal plates do not protrude beyond the originally cylindrical external contour of the spindle nut.

[0046] FIG. 5 shows a further variant of a spindle nut 120 without a threaded spindle in a perspective view with two ball deflectors 220, 220′. The through-openings 170, 170′ in each case form part of a groove in the threaded spindle 120 which comprises a one-piece ball return guide 220, 220′ which is to be inserted. A single small metal plate 180 secures the two ball deflectors in the manner of a bandage.