rolling screw drive

Abstract

A rolling screw drive with a nut (11) on the inner circumference of which a grooved profile (15) is provided, and with a roller cage (1) in which pockets (3) arranged circumferentially around a longitudinal axis (A) of the roller cage (1) accommodate profile rollers (2), and the profile rollers (2) engage with the grooved profile (15) of the nut (11), wherein the roller cage (1) has two flanges (5) and several webs (6) arranged circumferentially around the longitudinal axis (A) of the roller cage (1) and delimiting the pockets (3), wherein the roller cage (1) has a first cage part (7) and a second cage part (8) which are arranged one behind the other in the longitudinal axis (A) of the roller cage (1), and these each have a flange (5) and are connected to each other and held in position relative to each other by means of a connecting element (9).

Description

[0001] The present invention relates to a rolling screw drive. Rolling screw drives convert rotary relative movements into translational relative movements.

[0002] US Patent 7,736,256 B2 discloses a rolling screw drive with a nut mounted on a threaded spindle and profile rollers arranged between the threaded spindle and the nut in the direction of the longitudinal axis of the rolling screw drive. The profile rollers are arranged such that they engage simultaneously with a thread formed on an outer circumference of the threaded spindle and with a groove profile of the nut.

[0003] The profile rollers are held in a roller cage located in the nut. The roller cage has two flanges which are integrally connected to each other via several webs arranged circumferentially around the longitudinal axis of the roller cage. Bearing pockets are formed between the webs on the flanges in the circumferential direction around the longitudinal axis of the roller cage. End pins of the profile rollers engage in the bearing pockets of the flanges of the roller cage, with the profile rollers being rotatably mounted about their own axis and the axis of the threaded spindle.

[0004] Stop elements are arranged at both ends of the nut. The nut, which is positioned around the roller cage, is held against the roller cage by means of these stop elements, thus preventing the roller cage from shifting out of the nut along its longitudinal axis.

[0005] The object of the present invention is to provide a roller screw drive with a roller cage that can be easily mounted with the nut.

[0006] This problem is solved by a rolling screw drive with a roller cage element having the features of independent claim 1.

[0007] Advantageous embodiments are the subject of claims 2 to 10.

[0008] The rolling screw drive according to the invention has a nut in the inner circumference of which a groove profile is formed. The groove profile can be formed from several grooves arranged one behind the other in the direction of a longitudinal axis of the rolling screw drive.

[0009] A roller cage is arranged in the nut of the rolling screw drive. The longitudinal axis of the rolling screw drive and the longitudinal axis of the roller cage are preferably arranged coaxially. The roller cage has pockets arranged circumferentially around its longitudinal axis, in which profile rollers are received. The profile rollers have grooves formed along one of their longitudinal axes, which engage with the groove profile of the nut.

[0010] The roller cage has two flanges arranged one behind the other along its longitudinal axis. The roller cage also features several webs distributed circumferentially around its longitudinal axis, which define the pockets. The flanges are connected to each other via these webs. The number of webs depends on the size of the roller cage and the number of profile rollers. The webs prevent the flanges from twisting and thus prevent the profile rollers from tilting.

[0011] The roller cage comprises a first cage section and a second cage section. The first and second cage sections are arranged one behind the other along the longitudinal axis of the roller cage. Each cage section has one of the two flange rings. The flange rings are connected to each other by means of a connecting element, so that the first and second cage sections are held securely in position relative to each other.

[0012] The roller screw drive according to the invention enables easy assembly of its components. The first cage part can be inserted from a first nut side, and the second cage part can be inserted from a second nut side. The first and second cage parts are connected and held in position by means of the connecting element. In this way, the roller cage can also be mounted even if the inner diameter of the nut, which may be formed by the tooth tips of the groove profile, is smaller than the outer diameter of the flange rings of the roller cage.

[0013] Another advantage of dividing the roller cage is that the profile rollers can be inserted into one of the cage parts before the other cage part is mounted, thus eliminating the need for radial insertion of the profile rollers from the inside.

[0014] The first and second cage sections of the roller cage can have several web sections distributed circumferentially around the longitudinal axis of the roller cage. For a rigid connection of the flanges, it can be advantageous to provide at least three web sections. The web sections can be integrally formed with the respective flange. The first cage section can have the same number of web sections as the second cage section. The web sections of the first cage section can, together with the web sections of the second cage section, form the webs of the roller cage. The connecting element can join the respective web sections to one another, with the connecting element being formed at the respective opposing ends of the web sections.

[0015] The connecting element can have an axial connecting section, a circumferential connecting section, and a radial connecting section. The axial connecting section can hold the first and second cage parts in position axially around the longitudinal axis of the roller cage. The circumferential connecting section can hold the first and second cage parts in position circumferentially around the longitudinal axis of the roller cage. The radial connecting section can hold the first and second cage parts in position radially transversely to the longitudinal axis of the roller cage.

[0016] The axial connection section can have a snap hook at both opposing ends of the web sections of a web. The snap hooks can interlock with each other. This snap connection allows for easy connection of the two cage sections and simple assembly of the two cage sections with the nut.

[0017] The circumferential connecting section can be formed at the mutually facing ends of the two web parts of a web, wherein at least one projection can be formed on one web part and at least one recess can be formed on the other web part which can engage in the projection.

[0018] A web section can have two or more web section segments. The projection can be formed on the first web section segment. The recess can be formed on the second web section segment.

[0019] The positive locking in the circumferential direction prevents the first cage part from twisting relative to the second cage part.

[0020] This positive locking in the circumferential direction allows the alignment of the first cage part relative to the second cage part during the assembly of the two cage parts together.

[0021] The radial connection section can be formed by the circumferential and / or the axial connection section. Due to the axial positive locking and / or the circumferential positive locking, the first cage part and the second cage part cannot be easily separated from each other after joining, thus ensuring a reliable connection.

[0022] If radial displacement by means of the circumferential and / or axial connecting section of the first cage part relative to the second cage part is not possible, this is particularly advantageous, as no further connecting sections or connecting means need to be introduced.

[0023] The first cage part can be identical in construction to the second cage part. Identical components allow the use of a common tool and reduce manufacturing costs.

[0024] Bearing pockets can be formed on the facing end faces of the two flange rings, into which the bearing journals of the profile rollers can engage. The bearing pockets can be formed circumferentially around the longitudinal axis of the roller cage at regular intervals on the flange rings. The profile rollers can be rotatably mounted in the bearing pockets about their roller axis.

[0025] The bearing pockets can have a mounting seat and an operating seat for the profile rollers. The mounting seats of the bearing pockets can be formed around a first diameter on the flange rings. The operating seats of the bearing pockets can be formed around a second diameter on the flange rings.

[0026] The first diameter can be smaller than the second diameter, allowing the profile rollers to be mounted radially inside the roller cage.

[0027] The first diameter can be larger than the second diameter, allowing the profile rollers to be mounted radially outside into the roller cage.

[0028] The bearing pockets can be designed in such a way that radial displacement of the profile rollers from the mounting seat to the operating seat of the respective bearing pocket and vice versa is possible.

[0029] The profile rollers are not engaged with the groove profile of the nut when it is in the assembly position. The profile rollers are engaged with the groove profile of the nut when it is in the operating position.

[0030] The design of the bearing pockets with a mounting seat and an operating seat has the advantage of simplifying the assembly of the roller cage with the nut. The profile rollers only need to be moved from the mounting seat to the operating seat to engage with the nut, thus eliminating the need to screw the nut onto the profile rollers, screw the threaded spindle between the profile rollers, or perform other complicated assembly procedures.

[0031] The flange rings can have an outer diameter larger than the inner diameter of the nut defined by the groove profile. The groove profile of the nut can be positioned between the two flange rings of the roller cage, along the longitudinal axis of the roller cage. This ensures a secure, captive connection between the roller cage and the nut.

[0032] The flange rings prevent the nut from migrating away from the roller cage along its length. This design is particularly advantageous because only the roller cage, and no other components, are required to create a secure connection with the nut. The two-part design of the roller cage makes it especially easy to install with this type of nut.

[0033] The roller cage, with a larger outer diameter of the flange rings than the inner diameter of the nut, can be mounted with the nut according to the following steps: - Inserting the profile rollers into the mounting seat of the bearing pockets of the first cage part, - Assembling the nut with the first cage part, whereby the nut is placed on the rim ring of the first cage part in the mounting direction of the profile rollers, - Inserting the second cage part, with the web parts of the first cage part lying behind the web parts of the second cage part in the direction of the longitudinal axis of the roller cage, - Connecting the first cage part and the second cage part, whereby the snap hooks of the cage parts snap into place, - Radial displacement of the profile rollers from the mounting seat of the bearing pockets to the operating seat of the bearing pockets of the cage parts.

[0034] The advantage of the described assembly method is that the assembly direction of all components is the same, which makes assembly simple and therefore cost-effective.

[0035] The rolling screw drive, consisting of a nut, roller cage, and profile rollers, can be supplemented by a threaded spindle that is screwed into the nut. The profile rollers can engage with a thread formed on the outer circumference of the threaded spindle as well as with the groove profile of the nut.

[0036] The roller cage can be manufactured by injection molding or casting from an injection-moldable or castable material, preferably plastic. In both processes, a closed mold is provided that defines the desired part. The injection-moldable or castable material is injected or poured into the mold in a liquid state. The material then hardens within the mold.

[0037] The advantage of injection molding or casting processes is that products can be manufactured cost-effectively in large quantities. Furthermore, these processes make it possible to produce complex geometries, such as snap hooks, at low cost.

[0038] A preferred embodiment of the invention is described in more detail below with reference to the figures. They show Fig. 1 a roller cage with profile rollers and with screwed-in threaded spindle, Fig. 2 a longitudinal section of the roller cage inserted into a nut made of Fig. 1, Fig. 3 a cage part in spatial representation, Fig. 4. The cage parts of the roller cage in exploded view, Fig. 5 the compound roller cage made of Fig. 4 in perspective view.

[0039] The one in the Fig. 1, Fig. 2, Fig. 3, Fig. 4 to Fig. The 5 illustrated roller screw drive shows in Fig. 1. A roller cage 1 with three profile rollers 2, which are rotatably mounted about their roller axis in three pockets 3. A threaded spindle 4 is screwed into the roller cage 1, the thread of which engages with the profile rollers 2 on its outer circumference.

[0040] The roller cage 1 has two flanges 5 and three webs 6 arranged around its circumference. Adjacent webs 6 define the pockets 3 in which the profile rollers 2 are arranged.

[0041] The roller cage 1 has a first cage part 7 and a second cage part 8 arranged axially one behind the other. The first cage part 7 and the second cage part 8 are connected to each other and held in position by means of a connecting element 9. Each of the cage parts 7, 8 has one of the flange rings 5. A web part 10 of the flange 6 is assigned to the first cage part 7 and a web part 10 is assigned to the second cage part 8. A web part 10 of the first cage part 7 and a web part 10 of the second cage part 8 together form a flange 6 of the roller cage 1. The web parts 10 are each firmly connected to one of the two flange rings.

[0042] The in Fig. The first cage part 7 and the second cage part 8 shown are manufactured as injection-molded components made of plastic.

[0043] Fig. Figure 2 shows the roller screw drive in longitudinal section. The roller cage 1 is made of Fig. 1 is inserted into a mother 11.

[0044] The first cage part 7 is positively connected to the second cage part 8. The web parts 10 of the first cage part 7 and the web parts 10 of the second cage part 8 have snap hooks 12. The snap hooks 12 of the respective web parts 10 engage with snap hooks 13 of the other web parts 10. The positive connection by means of the snap hooks 12, 13 forms an axial connection section 14.

[0045] The nut 11 is arranged in a captive manner between the flange 5 of the first cage part 7 and the flange 5 of the second cage part 8 along the longitudinal axis A of the roller cage. The nut 11 has a grooved profile 15 on its inner circumference, which engages with the profile rollers 2.

[0046] The groove profile 15 of the nut 11 defines a clear diameter D1. The flange rings 5 ​​of the roller cage 1 have an outer diameter D2 that is larger than the clear diameter D1 of the nut 11. Due to the radial overlap of the flange rings 5 ​​with the groove profile 15 of the nut 11, a captive connection is ensured.

[0047] Fig. Figure 3 shows one of the two identical cage parts 7, 8 in a perspective view looking at the free ends of the web parts 10, which extend from the flange 5. Bearing pockets 16 are clearly visible in the flange 5, into which the profile rollers 2 (not shown) engage with their end pins. These bearing pockets 16 each have a mounting seat 17 and a radially spaced operating seat 18 for the profile rollers 2. In the operating seat 18, the profile rollers 2 engage with the groove profile 15 of the nut 11.

[0048] The mounting seat 17 of the storage pocket 16 is designed such that a profile roller 2, not shown here, can be pressed from the mounting seat 17 into the operating seat 18.

[0049] The ends of the web sections 10 have triangular recesses 19. Furthermore, the ends of the web sections 10 have triangular projections 20. The respective projections 20 are designed such that they can engage positively in the respective recesses 19. The positive-locking connection between the projections 20 and the recesses 19 forms the circumferential connecting section 21.

[0050] Fig. Figure 4 shows cage parts 7 and 8. Fig. 3. The first cage part 7 is aligned with the second cage part 8 in such a way that they are arranged one behind the other in the direction of the longitudinal axis A of the roller cage 1 and the end faces of the rim rings 5 ​​on which the web parts 10 are formed are facing each other.

[0051] The first cage part 7 and the second cage part 8 are snapped together. As already mentioned... Fig. As the first cage part 7 is executed, the snap hooks 12 engage with the snap hooks 13 of the second cage part 8, and vice versa, forming the axial connecting section 14. The projections 20 of the first cage part 7 engage in the recesses 19 of the second cage part 8, and vice versa, forming the circumferential connecting section 21. A radial connecting section 22 is thus formed by the axial connecting section 14 and the circumferential connecting section 21. Together, the connecting sections 14, 21, and 22 form the connecting element 9. The first cage part 7 and the second cage part 8 are held in position relative to each other by means of the connecting element 9.

[0052] Fig. Figure 5 shows the roller cage 1 with the first cage part 7 and the second cage part 8 in snapped-in state. Reference symbol list 1 roller cage 2 profile roller 3 bags 4 threaded spindles 5 Bordring 6 Bridge 7 First cage part 8 Second cage part 9 Connecting element 10 Bridge section 11 Mother 12 snap hooks 13 snap hooks 14 Axial connection section 15 groove profile 16 storage bags 17 Assembly seat 18 Company headquarters 19 Exclusion 20 lead 21 Circumferential connection section 22 Radial connecting section D1 inner diameter D2 outer diameter A Longitudinal axis QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] US 7 736 256 B2

[0002]

Claims

A rolling screw drive with a nut (11) on the inner circumference of which a grooved profile (15) is provided, and with a roller cage (1) in which pockets (3) arranged circumferentially around a longitudinal axis (A) of the roller cage (1) accommodate profile rollers (2), and the profile rollers (2) are in engagement with the grooved profile (15) of the nut (11), wherein the roller cage (1) has two flanges (5) and several webs (6) arranged circumferentially around the longitudinal axis (A) of the roller cage (1) and delimiting the pockets (3), characterized in that the roller cage (1) has a first cage part (7) and a second cage part (8) which are arranged one behind the other in the longitudinal axis (A) of the roller cage (1), and these each have a flange (5) and are connected to each other and held in position relative to each other by means of a connecting element (9). Roller screw drive according to claim 1, wherein the first cage part (7) and the second cage part (8) each have at least three web parts (10) distributed circumferentially around the longitudinal axis (A) of the roller cage (1), which are integrally formed with the flange ring (5) of the respective cage part (7, 8), wherein the web parts (10) of the first cage part (7) together with the web parts (10) of the second cage part (8) form the webs (6) of the roller cage (1) and are connected to each other by means of the connecting element (9). A rolling screw drive according to claim 1 or 2, wherein the connecting element (9) has an axial connecting section (14), a circumferential connecting section (23), and a radial connecting section (24), wherein the axial connecting section (14) holds the first cage part (7) and the second cage part (8) in the axial direction of the longitudinal axis (A) of the roller cage (1), and wherein the circumferential connecting section (23) holds the first cage part (7) and the second cage part (8) in the circumferential direction about the longitudinal axis (A) of the roller cage (1), and wherein the radial connecting section (24) holds the first cage part (7) and the second cage part (8) in the radial direction transverse to the longitudinal axis (A) of the roller cage (1). Rolling screw drive according to claim 3, the axial connecting section (14) of which has snap hooks (12, 13) at both mutually facing ends of the two web parts (10) of a web (6) which engage behind each other. Rolling screw drive according to claim 3 or 4, the circumferential connecting section (23) of which has at least one projection (22) formed on one of the two web parts (10) of a web (6) at the mutually facing ends of the two web parts (10) and at least one recess (21) formed on the respective other web part (10) into which the projection (22) engages. Rolling screw drive according to claim 4 or 5, the radial connecting section (24) of which is formed by the circumferential connecting section (23) and / or by the axial connecting section (14). Rolling screw drive according to claims 1 to 6, the first cage part (7) of which is identical in construction to the second cage part (8). Rolling screw drive according to claims 1 to 7, the roller cage (1) of which has bearing pockets (16) for the profile rollers (2) on the facing end faces of the two flange rings (5), wherein the bearing pockets (16) each have a mounting seat (17) and an operating seat (18) for the profile rollers (2), wherein the profile rollers (2) are disengaged from the groove profile (15) of the nut (11) in the mounting seat (17), and wherein the profile rollers (2) are engaged with the groove profile (15) of the nut (11) in the operating seat (18). Rolling screw drive according to claims 1 to 8, wherein the flange rings (5) have an outer diameter (D2) that is larger than a clear diameter (D1) of the nut (11), wherein the groove profile (15) of the nut (11) is arranged in the direction of the longitudinal axis (A) of the roller cage (1) between the two flange rings (5) of the roller cage (2). Rolling screw drive according to claims 1 to 9, comprising a threaded spindle (4), wherein the profile rollers (2) engage with a thread formed on the outer circumference of the threaded spindle and with the groove profile (15) of the nut (11).

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