Roller screw bidirectional axial preloading structure

Abstract

A bidirectional axial preload structure for a roller screw includes: a screw, a nut, a roller assembly, a retainer assembly, and two elastic members. The retainer assembly has two retainers, and the roller assembly has a plurality of staggered first and second rollers. The two ends of each of the first and second rollers are respectively connected to the two retainers, and staggered first and second gaps are formed between the first and second rollers and the retainers along the axial direction. The two elastic members apply axial force to the outer sides of the two retainers, causing the first and second rollers to be subjected to forces in opposite directions, thereby forming a staggered bidirectional preload effect to improve the transmission accuracy and motion stability of the roller screw.

Claims

1. A bidirectional axial preload structure for a roller screw, comprising: A screw, the outer circumferential surface of which is provided with a threaded structure; A nut is fitted onto the screw, and the inner side of the nut has at least one annular groove section; a roller assembly is disposed between the screw and the nut, having a plurality of staggered first rollers and second rollers, each of the first and second rollers having a plurality of annular teeth on its outer circumferential surface, respectively engaging with the thread structure and the annular groove section; a retainer assembly is disposed inside the nut, having a first retainer and a second retainer located at both ends of the roller assembly, the first retainer being connected to one end of the first rollers and the second rollers, and the second retainer being connected to the opposite end of the first rollers and the second rollers. The first rollers have a first gap between one end and the first retainer, and the second rollers have a second gap between one end and the second retainer. The first gap and the second gap are respectively arranged in an alternating manner at opposite ends of the roller assembly. Two elastic members are disposed in the nut and elastically abut against the outer sides of the first retainer and the second retainer along an axial direction. Each elastic member has a fastener on its outer side, thereby allowing the two elastic members to apply axial positive force to the first rollers and the second rollers respectively, forming an alternating bidirectional axial preload configuration.

2. The roller screw bidirectional axial preload structure as described in claim 1, wherein a bearing is provided between the retaining member assembly and the two elastic members respectively.

3. The roller screw bidirectional axial preload structure as described in claim 1, wherein the two elastic elements apply positive preload in opposite directions to the first rollers and the second rollers via the first and second retaining elements respectively.

4. The roller screw bidirectional axial preload structure as described in claim 1, wherein the inner side of the nut is provided with two grooves for the fastener to be embedded.

5. The roller screw bidirectional axial preload structure as described in claim 1, wherein: The first retainer is provided with a plurality of first positioning grooves, which accommodate one end of the first rollers and the second rollers, and the groove depths of the first positioning grooves are the same for each other; the second retainer is provided with a plurality of second positioning grooves, which accommodate the opposite ends of the first rollers and the second rollers, and the groove depths of the second positioning grooves are the same for each other; wherein the axial length of one end of the first roller accommodated in the first positioning groove is less than the axial length of its opposite end and the groove depth of the first positioning groove, so as to form the first gap; the axial length of one end of the second roller accommodated in the second positioning groove is less than the axial length of its opposite end and the groove depth of the second positioning groove, so as to form the second gap, and the first gaps and the second gaps are respectively formed at both ends of the roller assembly and are staggered.

6. The roller screw bidirectional axial preload structure as described in claim 1, wherein: The first retainer is provided with a plurality of first positioning grooves, which are used to accommodate one end of the first rollers and the second rollers, and the groove depths of the first positioning grooves accommodating the first rollers and the second rollers are different from each other; the second retainer is provided with a plurality of second positioning grooves, which are used to accommodate the other opposite end of the first rollers and the second rollers, and the groove depths of the second positioning grooves accommodating the first rollers and the second rollers are different from each other.

7. The roller screw bidirectional axial preload structure as described in claim 1, wherein a gasket is provided between the elastic element and the fastener.

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