Linear actuator with improved indexing means

Abstract

The invention relates to a linear actuator (1) comprising: - an actuating rod (2) arranged in an outer tube (3) and capable of being moved linearly in a longitudinal direction (I-I) between a retracted position and an extended position; - an actuating member (4) comprising a threaded rod (5) that is rotatable about the longitudinal direction (I-I) and a nut (6) engaging with the threaded rod (5) by screwing, the nut (6) being mechanically coupled to the actuating rod (2); - means (7) for indexing the rotation of the nut (6) in the outer tube (3), including a first longitudinal groove (8) provided in the outer tube (3) and comprising two opposing lateral bearing paths (8a, 8b), and a first indexing member (10) rigidly connected to the nut (6). The first indexing member (10) comprises rollers which are each permanently pressed bearing against the two lateral bearing paths of the first longitudinal groove (8).

Description

LINEAR ACTUATOR WITH IMPROVED INDEXING MEANS TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to linear actuators, and more particularly relates to the guiding of an actuating rod of a linear actuator.

[0002] A linear actuator AL according to the state of the art as illustrated in the comprises: - an actuating rod TA arranged telescopically in an external tube TE and linearly movable in a longitudinal direction DL between a retracted position and at least one extended position relative to said external tube TE, - an actuating member OA (here a ball screw VB) shaped to generate the longitudinal movements of the actuating rod TA, comprising a threaded rod TF rotatable about the longitudinal direction DL and a nut EC cooperating by screwing with the threaded rod TF to be moved bidirectionally in translation in the longitudinal direction DL by rotation of said threaded rod TF, said nut EC being mechanically coupled to the actuating rod TA, - indexing means MI in rotation of the nut EC in the external tube TE, shaped so as to lock in rotation the nut EC relative to the external tube TE.

[0003] In the linear actuator AL illustrated in the, the indexing means comprise:- two longitudinal grooves RL1 and RL2 formed in the external tube TE and each comprising two opposite lateral support paths,- two indexing members OI1 and OI2 secured to the nut EC and respectively engaged in guided translation between the two lateral support paths of the longitudinal grooves RL1 and RL2.

[0004] In practice, the indexing devices consist of pads made of a material with a low coefficient of friction in the longitudinal grooves.

[0005] To be mounted in the longitudinal grooves, the indexing members are inserted between the lateral support paths of the corresponding longitudinal groove, and a lateral clearance must be provided between the indexing members and the lateral support paths.

[0006] A first disadvantage is that the lateral play induces an inaccuracy in the longitudinal position of the nut when the threaded rod is rotated.

[0007] A second disadvantage is that the indexing members wear too quickly due to their friction against the lateral support paths. This premature wear increases the inaccuracy in the longitudinal position of the nut.

[0008] A third disadvantage is that lateral play is a source of shocks (especially when reversing the direction of rotation of the threaded rod) which can lead to premature wear of the indexing members, especially when the linear actuator is used in high-frequency applications with high forces. This premature wear also increases the inaccuracy in the longitudinal position of the nut.

[0009] These disadvantages are even more significant when the stroke of the indexing members in the longitudinal grooves is very long, because the longer the stroke, the more the lateral clearance increases in order to take into account the machining tolerances of the longitudinal grooves.

[0010] From EP 2 886 908 A1, a linear actuator is known, the position of the rollers of which can be adjusted by means of an eccentric sleeve so as to arrange said rollers in contact with the lateral support paths of the longitudinal groove. However, there is no permanent pressing of the rollers against the lateral support paths of the longitudinal groove. The adjustment thus carried out in a particular axial position of the longitudinal groove does not make it possible to ensure permanent contact of the rollers against the lateral support paths of the longitudinal groove throughout the longitudinal groove, in particular if the width of the longitudinal groove increases compared to that of the particular axial position at which the positions of the rollers were adjusted due to machining tolerances.Furthermore, if the width of the longitudinal groove decreases in relation to that of the particular axial position to which the roller positions have been set, excess pressure occurs on the rollers and the lateral support paths of the longitudinal groove, said excess pressure being able to lead to premature deterioration.

[0011] From document US 9,618,103 B2, a linear actuator is known according to the preamble of claim 1. The indexing member described therein has a significant bulk resulting from the addition of a lateral leaf spring. In addition, the pressing of the rollers against the lateral support paths of the longitudinal groove, carried out by means of the leaf spring with necessarily limited stiffness, is not sufficient to absorb, under high loads, the torque induced in the nut by the rotation of the threaded rod. This also results in inaccuracy in the longitudinal position of the nut.

[0012] A problem addressed by the present invention is to provide a linear actuator with improved indexing means, exhibiting less inaccuracy in the longitudinal position of its nut, and reducing the risks of premature shocks and wear.

[0013] At the same time, the present invention aims to provide a linear actuator with indexing means having a small footprint and which can easily have: - a stiffness high enough to reduce rotations and limit the risks of impacts when abutting against the lateral support paths of the longitudinal groove under the effect of the rotation torque induced in the nut by the rotation of the threaded rod, - a stiffness low enough to limit the risks of overpressure on the rollers and the lateral support paths of the longitudinal groove.

[0014] To achieve these and other objects, the invention provides a linear actuator comprising:- an actuating rod arranged telescopically in an outer tube and linearly movable in a longitudinal direction between a retracted position and at least one extended position relative to said outer tube,- an actuating member shaped to generate the longitudinal movements of the actuating rod, comprising a threaded rod rotatable about the longitudinal direction and a nut cooperating by screwing with the threaded rod to be moved bidirectionally in translation in the longitudinal direction by rotation of said threaded rod, said nut being mechanically coupled to the actuating rod,- means for indexing in rotation the nut in the outer tube, shaped so as to lock in rotation the nut relative to the outer tube,and comprising:at least one first longitudinal groove formed in the outer tube and comprising two opposite lateral support paths,at least one first indexing member secured to the nut and slidingly engaged between the two lateral support paths of the first longitudinal groove,in which:- the first indexing member comprises a first pair of rollers substantially aligned longitudinally and having diameters smaller than the width between the two lateral support paths,- the first pair of rollers is carried by a first support element secured to the nut,- the first support element is shaped so as to permanently press a first roller of said first pair of rollers against one of said two lateral support paths and the other roller of said first pair of rollers against the other of said lateral support paths; according to the invention: - the first support element extends longitudinally in a first direction between a first end and a second end and extends transversely in a second direction between first and second lateral edges, - the first support element comprises at least one first arm extending along the first lateral edge towards a free end located in the vicinity of the first end, - said at least one first arm comprises at its free end means for receiving a first roller,shaped to receive a first roller in a rotatable manner about a direction of rotation substantially perpendicular to the first and second directions, - the free end of said at least first arm can be moved towards the second lateral edge by elastic bending of said at least first arm.,

[0015] The actuating member may be a ball screw or any other helical-linked member operating on the screw / nut principle.

[0016] The rollers being permanently pressed elastically against the two opposite lateral paths, the indexing member is received without lateral play in the first longitudinal groove, which effectively limits the risk of shocks when reversing the direction of rotation of the threaded rod. The precision in determining the longitudinal position of the nut as a function of the rotation of the threaded rod (which can be determined by means of an encoder, for example) is also increased.

[0017] The permanent elastic pressing of the rollers against the two opposite lateral paths also makes it possible to compensate for manufacturing tolerances in the longitudinal groove, particularly if the latter is long. It also promotes rolling with little (or no) sliding of the rollers against the lateral support paths, which limits the risk of premature wear.

[0018] Such indexing means are compact. In addition, said at least one arm can easily present (by a conformation giving it a suitable quadratic moment):- a sufficiently high stiffness to reduce rotations and limit the risks of impacts in abutment against the lateral support paths of the longitudinal groove under the effect of the rotational torque induced in the nut by the rotation of the threaded rod,- a sufficiently low stiffness to limit the risks of overpressure on the rollers and the lateral support paths of the longitudinal groove.

[0019] Preferably, for more reliable, more precise and more balanced indexing around the longitudinal direction, it can be provided that:- the indexing means comprise at least one second longitudinal groove formed in the external tube and comprising two opposite lateral support paths,- the indexing means comprise at least one second indexing member secured to the nut and slidably engaged between the two lateral support paths of the second longitudinal groove,- the second indexing member comprises a second pair of rollers substantially aligned longitudinally and having diameters smaller than the width between the two lateral support paths,- the second pair of rollers is carried by a second support element secured to the nut,- the second support element is shaped so as to permanently press a first roller of said second pair of rollers against one of said two lateral support paths and the other roller of said second pair of rollers against the other of said lateral support paths.,

[0020] To further reduce the risk of premature wear, the rollers can advantageously be of the ball, roller or needle bearing type, with a coaxial inner ring and outer ring between which balls, rollers or needles are arranged.

[0021] Preferably, when an indexing member is arranged at rest outside the corresponding longitudinal groove, the rollers define between them a maximum width, taken transversely to their substantially longitudinal alignment direction, which is greater than the width of the corresponding longitudinal groove.

[0022] The mounting of the indexing member in the corresponding longitudinal groove is thus carried out in a pre-stressed state which guarantees good support of the rollers against the two opposite lateral support paths, and which considerably extends the service life of said indexing member.

[0023] Advantageously, it can be provided that:- the first and / or the second support element extends longitudinally in a first direction between a first end and a second end and extends transversely in a second direction between first and second lateral edges,- the first and / or the second support element comprises a first arm extending along the first lateral edge towards a free end located in the vicinity of the first end and a second arm extending along the second lateral edge towards a free end located in the vicinity of the second end,- each arm comprises at its free end means for receiving a roller shaped to receive a roller in a rotatable manner about a direction of rotation substantially perpendicular to the first and second directions,- the free end of the first arm can be moved towards the second lateral edge by elastic bending of said first arm while the free end of the second arm can be moved towards the first lateral edge by elastic bending of said second arm.,

[0024] Such a support element makes it possible to provide the indexing organs with identical behavior regardless of the direction in which the actuating rod is moved. Such a support element also remains simple, inexpensive to produce, compact and reliable.

[0025] Preferably, it can be provided that:- the elastic displacement capacity of the first arm in the direction of the second lateral edge is provided by a slot provided in the support element from its first end in the direction of its second end,- the elastic displacement capacity of the second arm in the direction of the first lateral edge is provided by a slot provided in the support element from its second end in the direction of its first end.

[0026] The elastic displacement capabilities of the first and second arms are thus achieved simply with a compact support element.

[0027] For even smaller space requirements, the slots can be made to overlap in the first direction.

[0028] Advantageously, the indexing member(s) are received in the respective longitudinal groove(s) by deformation of the first and / or second arms of the support elements. The arms of the support elements, having a tendency to return to their initial position (before deformation), thus press the rollers against the lateral support paths.

[0029] Preferably, the support elements are respectively attached and fixed by means of a flange in respective radial recesses provided in the outer wall of the nut. The flange allows the support elements to be fixed in a precise and constant orientation on the nut.

[0030] Advantageously, the linear actuator may comprise first and second longitudinal grooves provided in the outer tube in diametrically opposite positions.

[0031] Preferably, each longitudinal groove may be delimited by two opposite side rails added and fixed in a longitudinal slot provided in the side wall of the outer tube. The side rails may be machined easily and separately from the outer tube, therefore with greater precision. The side rails may be made of a material less subject to premature wear and undergo finishes and treatments (particularly heat treatments) giving them better wear resistance than the outer tube.

[0032] Alternatively, however, it can be provided that each longitudinal groove can be machined directly in the constituent mass of the external tube.

[0033] To make the sliding of the nut in the outer tube more reliable, it is advantageous to provide a guide ring arranged between the nut and the inner surface of the outer tube, preferably two guide rings spaced apart from each other in the longitudinal direction.

[0034] The guide ring(s) may preferably be made of a polymer material. For example, guide rings marketed under the name TURCITE® T59 by TRELLEBORG AB may be used. SUMMARY DESCRIPTION OF THE DRAWINGS

[0035] Other objects, characteristics and advantages of the present invention will emerge from the following description of particular embodiments, made in relation to the attached figures, among which:

[0036] This is a longitudinal sectional view of a linear actuator according to the prior art;

[0037] This is a longitudinal sectional view of a particular embodiment of a linear actuator according to the present invention;

[0038] This is a perspective view of an external tube of the linear actuator in which a nut is guided in translation;

[0039] This is a perspective view of the outer tube and the lapris nut in longitudinal section;

[0040] This is a longitudinal sectional view of the outer tube and nut of the;

[0041] This is a partial top view of the outer tube and nut of the ;

[0042] This is a partial, bottom view of the outer tube and nut of the ;

[0043] Theis a partial cross-sectional view of the outer tube and nut according to a first transverse plane;

[0044] Theis a partial cross-sectional view of the outer tube and nut according to a second transverse plane;

[0045] This is a perspective view of a support member used in the embodiment of the ;

[0046] The is a top view of the support element in a resting state;

[0047] La is a top view of the support element in a state of partial elastic deformation; and

[0048] This is a perspective view of an alternative support member used in another particular embodiment of a linear actuator according to the present invention. DESCRIPTION OF PREFERRED EMBODIMENTS

[0049] When identical reference numerals are used in several figures, embodiments or variations of the invention, these reference numerals designate identical or similar elements in each of the figures, embodiments or variations.

[0050] In the schematic figures 2 to 12 is illustrated a particular embodiment of linear actuator 1 according to the present invention (the linear actuator 1 is shown only partially compared to the linear actuator of the prior art illustrated in the).This linear actuator 1 comprises: - an actuating rod 2 arranged telescopically in an external tube 3 and linearly movable in a longitudinal direction II between a retracted position and at least one extended position relative to said external tube 3, - an actuating member 4 shaped to generate the longitudinal movements of the actuating rod 2, comprising an (externally) threaded rod 5 rotatable about the longitudinal direction II and a nut 6 (internally threaded) cooperating by screwing with the threaded rod 5 to be moved bidirectionally in translation in the longitudinal direction II by rotation of said threaded rod 5, said nut 6 being mechanically coupled to the actuating rod 2, - indexing means 7 for rotation of the nut 6 in the external tube 3, shaped so as to lock the nut 6 in rotation relative to the external tube 3.

[0051] The actuating member 4 is shown here only schematically. It may be a ball screw (as in the prior art) or any other member with a helical connection operating according to the screw / nut principle.

[0052] In the embodiment of Figures 2 to 12, the indexing means 7 comprise:- a first longitudinal groove 8 formed in the outer tube 3 and comprising two opposite lateral support paths 8a and 8b (see Figures 8 and 9 more specifically),- a second longitudinal groove 9 formed in the outer tube 3 and comprising two opposite lateral support paths 9a and 9b (see Figures 8 and 9 more specifically),- a first indexing member 10 secured to the nut 6 and engaged in longitudinal displacement between the two lateral support paths 8a and 8b of the first longitudinal groove 8,- a second indexing member 11 secured to the nut 6 and engaged in longitudinal displacement between the two lateral support paths 9a and 9b of the second longitudinal groove 9.

[0053] The first indexing member 10 comprises a first pair of rollers 10a and 10b, offset longitudinally relative to each other and having diameters D10a and D10b less than the width L8 between the two lateral support paths 8a and 8b. The first pair of rollers 10a and 10b is carried by a first support element 12 secured to the nut 6. The first support element 12 is shaped so as to permanently press the roller 10a in rolling contact against the lateral support path 8a and the other roller 10b in rolling contact against the other lateral support path 8b. As can be seen in the figure, there remains a clearance J10a between the roller 10a and the lateral support path 8b, as well as a clearance J10b between the roller 10b and the lateral support path 8a.

[0054] Similarly, the second indexing member 11 comprises a second pair of rollers 11a and 11b offset longitudinally relative to each other and having diameters D11a and D11b less than the width L9 between the two lateral support paths 9a and 9b. The second pair of rollers 11a and 11b is carried by a second support element 13 secured to the nut 6. The second support element 13 is shaped so as to permanently press the roller 11a in rolling contact against the lateral support path 9a and the other roller 11b in rolling contact against the other lateral support path 9b. As can be seen in the figure, there remains a clearance J11a between the roller 11a and the lateral support path 9b, as well as a clearance J11b between the roller 11b and the lateral support path 9a.

[0055] The support elements 12 and 13 are respectively attached to the nut 6 by means of a flange 20 or 21 in respective radial housings 22 or 23 provided in the outer wall of the nut 6 (figures 4 and 5).

[0056] As can be seen more particularly in Figures 8 and 9, which are partial sections respectively along a first transverse plane P1 and along a second transverse plane P2, the rollers 10a, 10b, 11a and 11b are of the ball bearing type with an inner ring 14 and an outer ring 15 coaxial between which balls 16 are arranged. It is nevertheless possible to use rollers 10a, 10b, 11a and 11b of the roller or needle bearing type, or any other type of rotary roller.

[0057] It can be seen more particularly in Figures 10 to 12 that each of the first 12 and second 13 support elements extends longitudinally in a first direction II-II (intended to be parallel to the longitudinal direction II) between a first end 12a or 13a and a second end 12b or 13b, and extends transversely in a second direction III-III between a first 12c or 13c and a second lateral edge 12d or 13d. The first 12 and second 13 support elements comprise a base body 26 substantially in the form of a plate extending in the first direction II-II and second direction III-III.

[0058] The support elements 12 and 13 each comprise a first arm 12e or 13e extending along the first lateral edge 12c or 13c towards a free end 120e or 130e located in the vicinity of the first end 12a or 13a. The support elements 12 and 13 each also comprise a second arm 12f or 13f extending along the second lateral edge 12d or 13d towards a free end 120f or 130f located in the vicinity of the second end 12b or 13b.

[0059] Each arm 12e, 13e, 12f or 13f comprises at its free end receiving means 17 for a roller 10a, 10b, 11a or 11b which are shaped to receive a roller 10a, 10b, 11a or 11b in a rotatable manner about a direction of rotation IV-IV or VV substantially perpendicular to the first II-II and second III-III directions. Here, the receiving means 17 comprise a tube 17a with an internal thread 17b. The tube 17a extends from and away from the base body 26 substantially perpendicular to the plane defined by the first direction II-II and second direction III-III. Around the tube 17a is fitted with a small clearance the inner ring 14 of the rollers 10a, 10b, 11a or 11b which are then held captive on their respective tube 17a by a screw 17c engaging in the internal thread 17b (see figures 8 and 9).

[0060] As more particularly illustrated in the, the free end 120e or 130e of the first arm 12e or 13e can be elastically displaced towards the second lateral edge 12d or 13d, while the free end 120f or 130f of the second arm 12f or 13f can be elastically displaced towards the first lateral edge 12c or 13c.

[0061] The elastic displacement capacity of the first arm 12e or 13e towards the second lateral edge 12d or 13d is provided by a slot 18 provided in the support element 12 or 13 from its first end 12a or 13a towards its second end 12b or 13b. The elastic displacement capacity of the second arm 12f or 13f towards the first lateral edge 12c or 13c is provided by a slot 19 provided in the support element 12 or 13 from its second end 12b or 13b towards its first end 12a or 13a. The displacements of the free ends 120e, 130e, 120f or 130f are made by elastic bending of the first arms 12e or 13e, or by elastic bending of the second arms 12f or 13f.

[0062] The stiffness of the 12th or 13th arm during its elastic displacement towards the second lateral edge 12d or 13d is easily adaptable by means of the distance separating the slot 18 from the 12th or 13th lateral edge.

[0063] The stiffness of the arm 12f or 13f during its elastic displacement towards the second lateral edge 12c or 13c is easily adaptable by means of the distance separating the slot 19 from the lateral edge 12d or 13d.

[0064] The slots 18 and 19 have an overlap R along the first direction II-II. This overlap R can be increased to provide the support elements 12 and 13 with an even smaller footprint along the first direction II-II.

[0065] On the, the arms 12e, 13e, 12f and 13f are not elastically displaced, so that the slots 18 and 19 have respective widths L18 and L19 which are substantially constant over their entire length.

[0066] Thus, when an indexing member 10 or 11 is arranged outside the corresponding longitudinal groove 8 or 9, the rollers 10a and 10b, or the rollers 11a and 11b, define between them a maximum width LM (), taken transversely to their substantially longitudinal alignment direction (first direction II-II), which is greater than the width L8 or L9 (or 7) of the corresponding longitudinal groove 8 or 9.

[0067] On the, the arms 12e, 13e, 12f and 13f are elastically displaced, so that the slots 18 and 19 have respective widths L18 and L19 which are not constant over their entire length. The rollers 10a and 10b, or the rollers 11a and 11b, then define between them a width L, taken transversely to their substantially longitudinal alignment direction (first direction II-II), which is less than or equal to the width L8 or L9 of the corresponding longitudinal groove 8 or 9: the indexing elements 10 or 11 can then be inserted into the corresponding groove 8 or 9.

[0068] In other words, the indexing members 10 and 11 are received in a compressed state in the respective longitudinal grooves 8 and 9 by deformation of the first arms 12e or 13e, and / or by deformation of the second arms 12f or 13f of the support elements 12 or 13. After insertion and fixing of the support elements 12 and 13, the elasticity of the arms 12e or 13e pushes the roller 10a or 11b against the lateral support path 8a or 9b, and the elasticity of the arms 12f or 13f pushes the roller 10b or 11a against the lateral support path 8b or 9a.

[0069] In the embodiment of Figures 2 to 12, and as is more particularly visible in Figures 8 and 9, the longitudinal grooves 8 and 9 are delimited by two opposite lateral rails 80a and 80b on the one hand, and two opposite lateral rails 90a and 90b on the other hand, attached and fixed in a respective longitudinal slot 800 or 900 formed in the lateral wall of the external tube 3.

[0070] Alternatively, the longitudinal grooves 8 and 9 can be machined directly into the mass constituting the side wall of the outer tube 3.

[0071] It can be seen more particularly in Figures 4 and 5 that guide rings 24 and 25 are arranged between the nut 6 and the inner surface 3a of the outer tube 3. The two guide rings 24 and 25 are spaced from each other in the longitudinal direction II.

[0072] The guide rings make it possible to maintain satisfactory coaxiality between the nut 6 and the inner surface 3a of the outer tube 3.

[0073] As previously explained, the indexing members 10 and 11 are received in the respective longitudinal grooves 8 and 9 by elastic deformation of the first arms 12e or 13e, and / or by elastic deformation of the second arms 12f or 13f of the support elements 12 or 13. There thus remains overall no lateral play between the first pair of rollers 10a and 10b transversely to the first longitudinal groove 8. Similarly, there remains overall no lateral play between the second pair of rollers 11a and 11b transversely to the second longitudinal groove 9.

[0074] When the nut 6 slides in the external tube 3, the respective indexing members 10 and 11 remain permanently in contact (by rolling) with the lateral support paths 8a and 8b on the one hand, and with the lateral support paths 9a and 9b on the other hand, thanks to the elasticity of the arms 12e, 13e, 12f and 13f which makes it possible to absorb the geometric imperfections of the longitudinal grooves 8 and 9 and to absorb the shocks during a reversal of the direction of rotation of the threaded rod 5. Simultaneously, better precision is provided in determining the longitudinal position of the nut 6 when the threaded rod 5 is rotated.

[0075] Illustrated here is an alternative support element 12 or 13 used in another particular embodiment of linear actuator 1 according to the present invention.

[0076] The support element 12 or 13 of the differs from that illustrated in Figures 10 to 12 in that it comprises only a single arm 12e or 13e extending along the first lateral edge 12c or 13c towards a free end 120e or 130e located in the vicinity of the first end 12a or 13a. The single arm 12e or 13e comprises at its free end 120e or 130e means 17 for receiving a first roller 10a or 11b, shaped to receive a first roller 10a or 11b in a rotatable manner about a direction of rotation IV-IV substantially perpendicular to the first II-II and second III-III directions. The free end 120e or 130e of the single arm 12e or 13e can be moved towards the second lateral edge 12d or 13d by elastic bending of the single arm 12e or 13e.

[0077] The second roller 10b or 11a is received on receiving means 17 in a rotatable manner about a direction of rotation IV-IV substantially perpendicular to the first II-II and second III-III directions. The tube 17a of the receiving means 17 of the second roller 10b or 11a extends from and away from a zone Z of the base body 26. The zone Z extends in the first direction II-II and is devoid of a slot, in particular between the lateral edge 12c or 13c and the lateral edge 12d and 13d. The zone Z thus does not have a slot such as the slot 19 illustrated in FIGS. 10 to 12. The second roller 10b or 11a is thus held in a fixed position relative to the base body 26, which is substantially in the form of a plate. In other words, the second roller 10b or 11a cannot be elastically displaced towards the first side edge 12c or 13c.

[0078] The single arm 12th or 13th is sufficient to induce elastic and permanent pressing of the first roller 10a or 11b and of the second roller 10b or 11a against the lateral support paths 8a and 8b on the one hand or against the lateral support paths 9a and 9b on the other hand.

[0079] The operation of the support element 12 or 13 of lane comprising only one arm 12e or 13e is close to that of the support element 12 or 13 of figures 10 to 12, except that only one arm 12e or 13e deforms. On the other hand, the support element 12 or 13 of lane does not provide identical behaviors to the indexing members 10 and 11 in the two directions of rotation of the threaded rod 5.

[0080] The present invention is not limited to the embodiments which have been explicitly described, but it includes the various variations and generalizations contained within the scope of the following claims.

Claims

Linear actuator (1) comprising:- an actuating rod (2) arranged telescopically in an outer tube (3) and linearly movable in a longitudinal direction (II) between a retracted position and at least one extended position relative to said outer tube (3),- an actuating member (4) shaped to generate the longitudinal movements of the actuating rod (2), comprising a threaded rod (5) rotatable about the longitudinal direction (II) and a nut (6) cooperating by screwing with the threaded rod (5) to be moved bidirectionally in translation in the longitudinal direction (II) by rotation of said threaded rod (5), said nut (6) being mechanically coupled to the actuating rod (2),- indexing means (7) for rotation of the nut (6) in the outer tube (3), shaped so as to lock the nut (6) in rotation relative to the outer tube (3),and comprising:at least one first longitudinal groove (8) formed in the outer tube (3) and comprising two opposite lateral support paths (8a, 8b),at least one first indexing member (10) secured to the nut (6) and slidably engaged between the two lateral support paths (8a, 8b) of the first longitudinal groove (8),in which:- said at least one first indexing member (10) comprises a first pair of rollers (10a, 10b) offset longitudinally relative to each other and having diameters (D10a, D10b) less than the width (L8) between the two lateral support paths (8a, 8b),- the first pair of rollers (10a, 10b) is carried by a first support element (12) secured to the nut (6),- the first support element (12) is shaped so as to continuously pressing a first roller (10a, 10b) of said first pair of rollers (10a, 10b) in rolling contact against one of said two lateral support paths (8a,8b) and the other roller (10a, 10b) of said first pair of rollers (10a, 10b) in rolling contact against the other of said lateral support paths (8a, 8b),characterized in that:- the first support element (12) extends longitudinally in a first direction (II-II) between a first end (12a) and a second end (12b) and extends transversely in a second direction (III-III) between first (12c) and second (12d) lateral edges,- the first support element (12) comprises at least one first arm (12e) extending along the first lateral edge (12c) towards a free end (120e) located in the vicinity of the first end (12a),- said at least one first arm (12e) comprises at its free end (120e) means (17) for receiving a first roller (10a, 10b), shaped to receive a first roller (10a,10b) rotatably about a direction of rotation (IV-IV) substantially perpendicular to the first (II-II) and second (III-III) directions,- the free end (120e) of said at least first arm (12e) can be moved towards the second lateral edge (12d) by elastic bending of said at least first arm (12e)., Linear actuator (1) according to claim 1, characterized in that:- the indexing means (7) comprise at least one second longitudinal groove (9) formed in the external tube (3) and comprising two opposite lateral support paths (9a, 9b),- the indexing means (7) comprise at least one second indexing member (11) integral with the nut (6) and slidably engaged between the two lateral support paths (9a, 9b) of the second longitudinal groove (9),- the second indexing member (12) comprises a second pair of rollers (11a, 11b) offset longitudinally from each other and having diameters (D11a, D11b) less than the width (L9) between the two lateral support paths (9a, 9b),- the second pair of rollers (11a, 11b) is carried by a second element of support (13) secured to the nut (6), - the second support element (13) is shaped so as to permanently press a first roller (11a,11b) of said second pair of rollers (11a, 11b) in rolling contact against one of said two lateral support paths (9a, 9b) and the other roller (11a, 11b) of said second pair of rollers (11a, 11b) in rolling contact against the other of said lateral support paths (9a, 9b)., Linear actuator (1) according to one of claims 1 or 2, characterized in that the rollers (10a, 10b, 11a, 11b) are of the ball, roller or needle bearing type, with an inner ring (14) and an outer ring (15) coaxial between which balls (16) are arranged. Linear actuator (1) according to any one of claims 1 to 3, characterized in that, when an indexing member (10, 11) is arranged outside the corresponding longitudinal groove (8, 9), the rollers (10a-10b, 11a-11b) define between them a maximum width LM, taken transversely to their substantially longitudinal alignment direction, which is greater than the width (L8, L9) of the corresponding longitudinal groove (8, 9). Linear actuator (1) according to any one of claims 1 to 4, characterized in that:- the first and / or second support element (12, 13) extends longitudinally in a first direction (II-II) between a first end (12a, 13a) and a second end (12b, 13b) and extends transversely in a second direction (III-III) between first (12c, 13c) and second (12d, 13d) lateral edges,- the first and / or second support element (12, 13) comprises a first arm (12e, 13e) extending along the first lateral edge (12c, 13c) towards a free end (120e, 120f) located in the vicinity of the first end (12a, 13a) and a second arm (12f, 13f) extending along the second edge lateral (12d, 13d) towards a free end (120f, 130f) located in the vicinity of the second end (12b, 13b),- each arm (12e, 13e, 12f, 13f) comprises at its free end (120e, 130e, 120f, 130f) means for receiving (17) a roller (10a, 10b, 11a,11b), shaped to receive a roller (10a, 10b, 11a, 11b) in a rotatable manner about a direction of rotation (IV-IV) substantially perpendicular to the first (II-II) and second (III-III) directions,- the free end (120e, 130e) of the first arm (12e, 13e) can be moved towards the second lateral edge (12d, 13d) by elastic bending of said first arm (12e, 13e), while the free end (120f, 130f) of the second arm (12f, 13f) can be moved towards the first lateral edge (12c, 13c) by elastic bending of said second arm (12f, 13f)., Linear actuator (1) according to claim 5, characterized in that:- the elastic displacement capacity of the first arm (12e, 13e) in the direction of the second lateral edge (12d, 13d) is provided by a slot (18) provided in the support element (12, 13) from its first end (12a, 13a) in the direction of its second end (12b, 13b),- the elastic displacement capacity of the second arm (12f, 13f) in the direction of the first lateral edge (12c, 13c) is provided by a slot (19) provided in the support element (12, 13) from its second end (12b, 13b) in the direction of its first end (12a, 13a). Linear actuator (1) according to claim 6, characterized in that the slots (18, 19) are made so as to have an overlap (R) in the first direction (II-II). Linear actuator (1) according to any one of claims 5 to 7, characterized in that the indexing member(s) (10, 11) are received in the respective longitudinal groove(s) (8, 9) by deformation of the first (12e, 13e) and / or second (12f, 13f) arms of the support elements (12, 13). Linear actuator (1) according to any one of claims 1 to 8, characterized in that the support elements (12, 13) are respectively attached and fixed by means of a flange (20, 21) in respective radial housings (22, 23) provided in the outer wall of the nut (6). Linear actuator (1) according to any one of claims 1 to 9, characterized in that it comprises a first (8) and a second (9) longitudinal grooves formed in the external tube (3) in diametrically opposite positions. Linear actuator (1) according to any one of claims 1 to 10, characterized in that each longitudinal groove (8, 9) is delimited by two opposite lateral rails (80a-80b, 90a-90b) attached and fixed in a longitudinal slot (800, 900) formed in the lateral wall of the external tube (3). Linear actuator (1) according to any one of claims 1 to 10, characterized in that each longitudinal groove (8, 9) is machined directly in the constituent mass of the external tube (3). Linear actuator (1) according to any one of claims 1 to 12, characterized in that at least one guide ring (24, 25) is arranged between the nut (6) and the inner surface (3a) of the outer tube (3), preferably two guide rings (24, 25) spaced from each other in the longitudinal direction (II). Linear actuator (1) according to claim 13, characterized in that the guide ring(s) (24, 25) are made of a polymer material.

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