Linear actuator with shock absorption

Abstract

The invention relates to a linear actuator (1) comprising a movable pushing element (2) that moves linearly in a longitudinal direction (I-I) in an outer tube (3), wherein the movable pushing element (2) is driven by actuation means (4) with a helical connection (5) between a retracted position and at least one extended position relative to the outer tube (3), and wherein the movable pushing element (2) extends between a proximal end (2a) and a distal end (2b) and comprises a proximal section (2c) that is displaced by the actuation means (4) with the helical connection (5). A connecting body (10), fixedly secured to a free end of the proximal section (2c), allows sudden pushes and / or sudden pulls to be absorbed.

Description

LINEAR ACTUATOR WITH SHOCK DAMPING TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of linear actuators usable to generate linear motion.

[0002] We know a linear actuator AL as illustrated in the figure, comprising a push element EMP that can be moved linearly along a longitudinal direction DL in an external tube TE, said push element EMP being movable by actuation means MA with helical linkage LH between a retraction position and at least one extension position relative to said external tube TE, the push element EMP extending between a proximal end EP and a distal end ED and comprising a proximal section TP forced into displacement by the actuation means MA with helical linkage LH.

[0003] The helical link LH is here of the type ball screw VB having a nut EC indexed in rotation in the outer tube TE and movable by sliding in said outer tube TE when a threaded rod TF is driven in rotation by a motor M. It should be noted that the drive connection linking the motor M to the threaded rod TF is not represented here precisely.

[0004] In the present invention, the helical linkage may include a component other than a ball screw but operating on the screw / nut principle. For example, a satellite roller screw or a trapezoidal screw may be used.

[0005] During certain uses, the EMP push mobile element is subjected to sudden pulls (tending to move the EMP push mobile element towards its extension position) and / or sudden pushes (tending to move the EMP push mobile element towards its retraction position).

[0006] These sudden pulls and / or pushes generate shocks that propagate from the distal end of the moving thrust element (EMP) into the helical linkage (LH). This presents a significant risk of damage to the helical linkage.

[0007] Document CA 2 979 102 A1 describes a linear actuator that provides shock damping only when the thrust element reaches its retracted or fully extended position. No shock damping is provided when the thrust element is between these two extreme positions. The distal end of the thrust element (intended to be coupled to a load) is rigidly and permanently coupled to the internal tube of the thrust element: between the retracted and fully extended positions of the thrust element, sudden thrusts and pulls induce shocks directly in the threaded connection.

[0008] US document 2022 / 136591 A1 describes a linear actuator that provides shock absorption only in the event of sudden thrusts.

[0009] One problem addressed by the present invention is to effectively limit the risks of degradation of the helical linkage actuation means of a linear actuator in the event of sudden pulls.

[0010] To achieve this and other objectives, the invention proposes a linear actuator comprising a moving thrust element that can be linearly displaced along a longitudinal direction in an external tube, said moving thrust element being displaced by helical linkage actuation means between a retracted position and at least one extended position relative to said external tube, the moving thrust element extending between a proximal end and a distal end and comprising a proximal section subjected to displacement by the helical linkage actuation means; according to the present invention, said moving thrust element further comprises: - a connecting body, adapted to be fixedly attached to a free end of the proximal section, and comprising: a first transverse traction surface oriented towards the proximal end of the moving thrust element,a first transverse thrust surface oriented towards the distal end of the moving thrust element, - a distal section suitable for coupling to a load to be moved, arranged to slide along the longitudinal direction relative to the connecting body, and comprising: a second transverse traction surface oriented towards the distal end of the moving thrust element, a second transverse thrust surface oriented towards the proximal end of the moving thrust element, and in that said linear actuator comprises a compressible traction damping element, arranged longitudinally between the first transverse traction surface and the second transverse traction surface.

[0011] In the linear actuator according to the invention, if a sudden pull occurs on the moving thrust element (tending to move the moving thrust element towards its extension position), the compressible traction damping element is compressed between the first transverse traction surface and the second transverse traction surface, and thus absorbs at least part of the shock.

[0012] This effectively limits the risks of degradation of the helical linkage actuation means of the linear actuator.

[0013] The compressible tensile damping element always works in compression to absorb shocks. This effectively limits the risk of degradation of the compressible tensile damping element, particularly when the compressible tensile damping element is made of an elastomer-type material.

[0014] In order to effectively limit the risks of degradation of the helical linkage actuation means of a linear actuator in the event of sudden thrusts, the linear actuator may advantageously include a compressible thrust damping element, arranged longitudinally between the first transverse thrust surface and the second transverse thrust surface.

[0015] If a sudden thrust occurs on the moving thrust element (tending to move the moving thrust element towards its retraction position), the compressible thrust damping element is compressed between the first transverse thrust surface and the second transverse thrust surface, and thus absorbs at least part of the shock.

[0016] This therefore limits the risks of degradation of the helical linkage actuation means of the linear actuator even more effectively.

[0017] The compressible thrust damping element always works in compression to absorb shocks. This effectively limits the risk of degradation of the compressible thrust damping element, particularly when the compressible thrust damping element is made of an elastomer-type material.

[0018] In applications that give rise to little or no sudden thrusts, it will suffice to provide the compressible tension damping element.

[0019] In applications involving sudden pulls and pushes, a compressible tension damping element and a compressible push damping element may be provided. In such cases, the compressive properties of the tension damping element and the push damping element may be identical or different, depending on the intensities and frequencies of the sudden pulls and pushes.

[0020] In a first embodiment of the present invention, it can be provided that: - the connecting body comprises a transverse wall carrying the first transverse traction surface and the first transverse thrust surface on either side of said transverse wall, - the distal section comprises: a proximal body comprising the second transverse traction surface, a distal body comprising the second transverse thrust surface, connecting means engaged by sliding through the transverse wall of the connecting body and rigidly coupling the proximal body to the distal body.

[0021] Advantageously, in a first variant of said first embodiment, the connecting means may include a connecting rod passing through the center of the transverse wall of the connecting body. Such a structure allows the use of compressible thrust and / or tension damping elements in the form of a ring or bushing, and thus partially deforming radially inward during compression. This promotes good compactness.

[0022] Advantageously, the linear actuator may include rotational indexing means between the connecting body and the distal body of the distal section. These indexing means may preferably include keys allowing longitudinal sliding of the distal body of the distal section relative to the connecting body. The indexing means avoid the need for indirect indexing of the helical linkage, thus avoiding constraints on the design of the element actuated by the moving thrust element.

[0023] Advantageously, in a second variant of the first embodiment, the connecting means may comprise a plurality of connecting rods eccentrically radially with respect to the center of the transverse wall of the connecting body. The indexing means again avoid the need for indirect indexing of the helical joint by constraining the design of the element actuated by the moving thrust element.

[0024] This structure also allows the use of compressible thrust and / or tension damping elements in the form of a solid cylinder when the intensity of the impacts requires it. However, these compressible thrust and / or tension damping elements will deform radially outwards during compression, resulting in reduced compactness.

[0025] Preferably, it can be provided that: - the connecting body has a cylindrical side wall in which the distal body is guided by sliding motion, - the proximal section of the moving thrust element includes a tube with a cylindrical side wall in which the proximal body of the distal section is guided by sliding motion.

[0026] Such sliding guides promote shock absorption by compressing the compressible tension damping element and / or the compressible thrust damping element.

[0027] In a second embodiment of the present invention, it can be provided that: - the connecting body comprises: a proximal transverse wall, carrying the first transverse thrust surface, a distal transverse wall, carrying the first transverse traction surface, a cylindrical lateral wall, - the distal section comprises: a proximal body disposed longitudinally between the proximal transverse wall and the distal transverse wall, and carrying the second transverse traction and thrust surfaces, said proximal body being guided by sliding by the cylindrical lateral wall of the connecting body, a distal body, connecting means engaged by sliding through the distal transverse wall of the connecting body and rigidly coupling the proximal body to the distal body.

[0028] The sub-assembly formed by the connecting body and the distal section is more easily integrated into an existing linear actuator.

[0029] Preferably, the connecting means may include: - a connecting rod extending from and away from the proximal body, comprising a threaded free end and passing through the center of the distal transverse wall of the connecting body, - an internally threaded housing provided in the distal body, suitable for receiving by screwing the threaded free end of the connecting rod.

[0030] Advantageously, the linear actuator can include rotational indexing means between the connecting body and the distal body of the distal section. These indexing means avoid the need for indirect indexing of the helical linkage, thus eliminating constraints on the design of the element actuated by the thrust moving element.

[0031] Preferably, it can be provided that: - the connecting means include a section with a non-circular cross-section, - the distal cross-sectional wall of the connecting body includes a through passage with a non-circular cross-section in which the section with a non-circular cross-section of the connecting means is slidably engaged, - said non-circular cross-sections cooperate by interference of shapes to prohibit any relative rotation around the longitudinal direction between the connecting body and the distal body of the distal section.

[0032] Such indexing is reliable and compact.

[0033] Advantageously, the compressible tension damping element and / or the compressible thrust damping element can be, for example: - a block of an elastomeric material, - a spring, - a Belleville washer.

[0034] Although the invention here relates to a linear actuator comprising a compressible tension damping element in order to effectively limit the risks of degradation of the helical linkage actuation means of a linear actuator in the event of sudden pulls, the applicant expressly reserves the right to seek independent patent protection, in particular by means of a divisional application, of a linear actuator as previously described without a compressible tension damping element but comprising a compressible thrust damping element (possibly in combination with one or more of the optional features previously stated) in order in particular to effectively limit the risks of degradation of the helical linkage actuation means of a linear actuator in the event of sudden thrusts.Indeed, in applications that give rise to little or no sudden pulling, it will suffice to provide a compressible thrust damping element. SUMMARY DESCRIPTION OF THE DRAWINGS

[0035] Other objects, features and advantages of the present invention will become apparent from the following description of particular embodiments, made in relation to the accompanying figures, among which:

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

[0037] Laest is a schematic longitudinal cross-sectional view of a first variant of a first embodiment of a linear actuator according to the present invention, with a moving push element in the retracted position;

[0038] This is a schematic perspective view of the linear actuator, with a moving thrust element in the extended position;

[0039] This is a schematic longitudinal cross-sectional and detailed view of the linear actuator, in the absence of push or pull on the moving push element;

[0040] This is a schematic longitudinal and detailed cross-sectional view of the linear actuator when a sudden push occurs on the moving push element (tending to move the moving push element towards its retraction position);

[0041] This is a schematic longitudinal and detailed cross-sectional view of the linear actuator when a sudden pull occurs on the moving thrust element (tending to move the moving thrust element towards its extension position);

[0042] Laest a schematic longitudinal sectional and detailed view of the linear actuator in an alternative (not part of the invention) intended to receive mainly only sudden thrusts;

[0043] This is a schematic longitudinal cross-sectional and detailed view of the linear actuator in an alternative designed to receive mainly only sudden pulls;

[0044] This is a schematic cross-sectional view of the linear actuator along the PT1 plane shown in figures 4 to 8;

[0045] Laest is a schematic longitudinal sectional and detail view of a second variant of the first embodiment of a linear actuator according to the present invention;

[0046] This is a schematic longitudinal sectional and detailed view of the linear actuator when a sudden push occurs on the moving thrust element;

[0047] This is a schematic longitudinal sectional and detailed view of the linear actuator when a sudden pull occurs on the moving thrust element;

[0048] Laest a schematic longitudinal sectional and detailed view of the linear actuator in an alternative (not part of the invention) intended to receive mainly only sudden thrusts;

[0049] This is a schematic longitudinal cross-sectional and detailed view of the linear actuator in an alternative designed to receive mainly only sudden pulls;

[0050] This is a schematic cross-sectional view of the linear actuator along the PT2 plane shown in figures 10 to 14;

[0051] Laest is a schematic longitudinal cross-sectional and detailed view of a second embodiment of a linear actuator according to the present invention;

[0052] This is a schematic longitudinal sectional and detailed view of the linear actuator when a sudden push occurs on the moving thrust element;

[0053] This is a schematic longitudinal sectional and detailed view of the linear actuator when a sudden pull occurs on the moving thrust element;

[0054] Laest a schematic longitudinal sectional and detailed view of the linear actuator in an alternative (not part of the invention) intended to receive mainly only sudden thrusts;

[0055] This is a schematic longitudinal cross-sectional and detailed view of the linear actuator in an alternative designed to receive primarily only sudden pulls; and

[0056] This is a schematic cross-sectional view of the linear actuator according to the PT3 plane identified in figures 16 to 20. DESCRIPTION OF PREFERRED IMPLEMENTATION METHODS

[0057] When identical numerical references are used in several figures, embodiments, variants or alternatives of the invention, these numerical references designate identical or similar elements in each of the figures, embodiments or variants.

[0058] Figures 2 to 9 illustrate a first variant of a first embodiment of linear actuator 1 according to the present invention.

[0059] Figures 2 to 6 show a first alternative, capable of absorbing both sudden pushes and sudden pulls.

[0060] On the other hand, this is a second alternative (not part of the invention), capable of only dampening sudden thrusts.

[0061] On the other hand, this is a third alternative, capable of absorbing only sudden pulls.

[0062] We see more particularly on which the linear actuator 1 comprises a moving thrust element 2 that can be moved linearly along a longitudinal direction II in an external tube 3, said moving thrust element 2 being movable by actuation means 4 with helical linkage 5 between a retraction position () and at least one extension position () with respect to said external tube 3.

[0063] The moving thrust element 2 extends between a proximal end 2a and a distal end 2b, and includes a proximal section 2c stressed in displacement by the actuation means 4 with helical linkage 5.

[0064] Here, the helical link 5 is of the ball screw type having a nut 6 indexed in rotation in the external tube 3 and movable by sliding in said external tube 3 when a threaded rod 7 is driven in rotation by a motor 8. It should be noted that the drive connection 9 linking the motor 8 to the threaded rod 7 is not represented here precisely because its structure can be arbitrary within the framework of the present invention.

[0065] It should be noted that the helical linkage 5 may include a component other than a ball screw, but operating on the screw / nut principle. For example, a helical linkage 5 of the satellite roller screw type, or of the trapezoidal screw type, may be used.

[0066] It is clearer on this page that the moving thrust element 2 also includes a connecting body 10, adapted to be fixedly attached to a free end of the proximal section 2c. In practice, the proximal section 2c terminates with a tubular section T1 receiving the connecting body 10 by a screw connection. To achieve this, the connecting body 10 has an external thread that engages by screwing with an internal thread formed in the tubular section T1.

[0067] The connecting body 10 comprises: - a first transverse traction surface STT1 oriented towards the proximal end 2a of the push mobile element 2, - a first transverse push surface STP1 oriented towards the distal end 2b of the push mobile element 2.

[0068] The moving thrust element 2 further comprises a distal section 2d suitable for coupling to a load to be moved, arranged to slide along the longitudinal direction II relative to the connecting body 10, and comprising: - a second transverse traction surface STT2 oriented towards the distal end 2b of the moving thrust element 2, - a second transverse thrust surface STP2 oriented towards the proximal end 2a of the moving thrust element 2.

[0069] In the alternative illustrated on the, the linear actuator 1 simultaneously comprises: - a compressible tension damping element 11, arranged longitudinally between the first transverse tension surface STT1 and the second transverse tension surface STT2, - a compressible thrust damping element 12, arranged longitudinally between the first transverse thrust surface STP1 and the second transverse thrust surface STP2.

[0070] In practice, the connecting body 10 includes a transverse wall 13 carrying the first transverse tension surface STT1 and the first transverse thrust surface STP1 on either side of said transverse wall 13.

[0071] The distal section 2d comprises: - a proximal body 14 including the second transverse traction surface STT2, - a distal body 15 including the second transverse thrust surface STP2, - connecting means 16 engaged by sliding through the transverse wall 13 of the connecting body 10 and rigidly coupling the proximal body 14 to the distal body 15.

[0072] More precisely, the connecting means 16 comprise a connecting rod 17 passing through the center of the transverse wall 13 of the connecting body 10. The connecting rod 17 is hollow and receives a screw 18 which is screwed into a threaded housing 19 provided in the distal body 15.

[0073] The compressible tension damping elements 11 and thrust damping elements 12 have a general annular shape to allow passage of the connecting means 16.

[0074] The compressible tensile damping element 11 is fixed to the second transverse tensile surface STT2. The compressible thrust damping element 12 is fixed to the second transverse thrust surface STP2.

[0075] The connecting body 10 and the distal body 15 of the distal section 2d are coupled in rotation by rotational indexing means 20. It can be seen more particularly on the, which is a cross-section along the transverse plane PT1, that the rotational indexing means 20 comprise two keys 20a and 20b which allow longitudinal sliding of the distal body 15 relative to the connecting body 10, while blocking any relative rotation around the longitudinal direction II between the distal body 15 and the connecting body 10.

[0076] The shock damping during the operation of the linear actuator 1 is explained by means of figures 5 and 6.

[0077] On the , the movable thrust element 2 receives a thrust on its distal body 15 along the longitudinal direction II, as illustrated by arrow P. Under the effect of this thrust, the distal body 15 slides relative to the connecting body 10. The compressible thrust damping element 12 is then axially compressed between the first STP1 and second STP2 transverse thrust surfaces, thus damping a portion of the stresses induced on the helical joint 5 by the thrust. The axial compression of the compressible thrust damping element 12 between the first STP1 and second STP2 transverse thrust surfaces causes its radial deformation (in the direction of and away from the longitudinal direction II).

[0078] On the , the movable thrust element 2 receives a tension on its distal body 15 along the longitudinal direction II, as illustrated by arrow T. Under the effect of this tension, the distal body 15 slides relative to the connecting body 10, carrying the proximal body 14 with it. The compressible tension damping element 11 is then axially compressed between the first STT1 and second STT2 transverse tension surfaces, thus damping part of the stresses induced on the helical joint 5 by the tension. The axial compression of the compressible tension damping element 11 between the first STT1 and second STT2 transverse thrust surfaces causes its radial deformation (in the direction of and away from the longitudinal direction II).

[0079] The alternative in figures 5 and 6 thus makes it possible to cushion the shocks during both sudden pushes and sudden pulls.

[0080] Figure 1 illustrates an alternative (not part of the invention) linear actuator 1 primarily subjected to sudden thrusts. It provides only a single compressible damping element, namely the compressible thrust damping element 12, interposed between the first STP1 and second STP2 transverse thrust surfaces. When the compressible thrust damping element 12 is at rest (held between the first STP1 and second STP2 transverse thrust surfaces without being compressed, or only very slightly), the first STP1 and second STP2 transverse traction surfaces are in contact with each other.

[0081] In the alternative of the, there is damping of sudden pushes, but there is no damping of sudden pulls.

[0082] Figure 1 illustrates an alternative linear actuator 1 primarily subjected to sudden pulls. Only a single compressible damping element is provided, namely the compressible tension damping element 11, interposed between the first STT1 and second STT2 transverse tension surfaces. When the compressible tension damping element 11 is at rest (held between the first STT1 and second STT2 transverse tension surfaces without being compressed, or only very slightly), the first STT1 and second STT2 transverse thrust surfaces are in contact with each other.

[0083] In the alternative of the, there is damping of sudden pulls, but there is no damping of sudden pushes.

[0084] Figures 10 to 15 illustrate a variant of the first embodiment, according to three alternatives illustrated respectively in figures 10 to 12, on the and finally on the.

[0085] This variant differs in particular from the variant illustrated in Figures 4 to 9 in that the connecting means 16 comprise a plurality of connecting rods 17a to 17h eccentric radially with respect to the center of the transverse wall 13 of the connecting body 10 (see in particular Figure 1, which is a cross-section along the transverse plane PT2). The connecting rods 17a to 17h are received in corresponding threaded recesses 15a to 15h formed in the distal body 15. Such connecting means 16 allow longitudinal sliding of the distal body 15 relative to the connecting body 10, while blocking any relative rotation around the longitudinal direction II between the distal body 15 and the connecting body 10.

[0086] In the variant of figures 10 to 15, the compressible tension damping elements 11 and thrust damping elements 12 have a generally solid cylindrical shape.

[0087] The compressible tensile damping element 11 is fixed to the second transverse tensile surface STT2. The compressible thrust damping element 12 is fixed to the second transverse thrust surface STP2.

[0088] The shock damping during the operation of the linear actuator 1 is explained by means of figures 11 and 12.

[0089] On the, the mobile thrust element 2 receives on its distal body 15 a thrust along the longitudinal direction II and illustrated by the arrow P. Under the effect of this thrust, the distal body 15 slides relative to the connecting body 10. The compressible thrust damping element 12 is then compressed between the first STP1 and second STP2 transverse thrust surfaces, and its radial deformation (away from the longitudinal direction II) thus dampens part of the stresses induced on the helical connection 5 by the thrust.

[0090] On the, the mobile thrust element 2 receives on its distal body 15 a tension along the longitudinal direction II and illustrated by the arrow T. Under the effect of this tension, the distal body 15 slides relative to the connecting body 10, taking with it the proximal body 14. The compressible tension damping element 11 is then compressed between the first STT1 and second STT2 transverse tension surfaces, and its radial deformation (away from the longitudinal direction II) thus dampens part of the stresses induced on the helical connection 5 by the tension.

[0091] The alternative in figures 11 and 12 thus makes it possible to cushion the shocks during both sudden pushes and sudden pulls.

[0092] Figure 1 illustrates an alternative (not part of the invention) linear actuator 1 primarily subjected to sudden thrusts. It provides only a single compressible damping element, namely the compressible thrust damping element 12, interposed between the first STP1 and second STP2 transverse thrust surfaces. When the compressible thrust damping element 12 is at rest (held between the first STP1 and second STP2 transverse thrust surfaces without being compressed, or only very slightly), the first STP1 and second STP2 transverse traction surfaces are in contact with each other.

[0093] In the alternative of the, there is damping of sudden pushes, but there is no damping of sudden pulls.

[0094] Figure 1 illustrates an alternative linear actuator 1 primarily subjected to sudden pulls. Only a single compressible damping element is provided, namely the compressible tension damping element 11, interposed between the first STT1 and second STT2 transverse tension surfaces. When the compressible tension damping element 11 is at rest (held between the first STT1 and second STT2 transverse tension surfaces without being compressed, or only very slightly), the first STT1 and second STT2 transverse thrust surfaces are in contact with each other.

[0095] In the alternative of the, there is damping of sudden pulls, but there is no damping of sudden pushes.

[0096] In all variants and alternatives of the first embodiment, we see that: - the connecting body 10 has a cylindrical side wall 10a in which the distal body 15 is guided by sliding, - the proximal section 2c of the moving thrust element 2 includes a tube 21 with a cylindrical side wall 21a in which the proximal body 14 of the distal section 2d is guided by sliding.

[0097] The variants and alternatives of the first embodiment thus require a tube 21 with a specific conformation (cylindrical side wall 21a of guidance followed by a tubular section T1 of larger internal diameter and internally threaded).

[0098] Figures 16 to 21 illustrate a second embodiment, according to three alternatives shown respectively in figures 16 to 18, on the and finally on the.

[0099] In this second embodiment, we see more particularly on which the connecting body 10 comprises: - a proximal transverse wall 22, carrying the first transverse thrust surface STP1, - a distal transverse wall 23, carrying the first transverse traction surface STT1, - a cylindrical lateral wall 10a.

[0100] Still on the, we see that the distal section 2d comprises:- a proximal body 14 arranged longitudinally between the proximal transverse wall 22 and the distal transverse wall 23, and carrying the second transverse traction surfaces SST2 and thrust surfaces STP2, said proximal body 14 being guided by sliding by the cylindrical lateral wall 10a of the connecting body 10,- a distal body 15,- connecting means 16 engaged by sliding through the distal transverse wall 23 of the connecting body 10 and rigidly coupling the proximal body 14 to the distal body 15.

[0101] More specifically, the connecting means 16 include: - a connecting rod 17 extending from and away from the proximal body 14, comprising a threaded free end 170 and passing through the center of the distal transverse wall 23 of the connecting body 10, - an internally threaded housing 24 provided in the distal body 15, suitable for receiving by screwing the threaded free end 170 of the connecting rod 17.

[0102] The distal body 15 is thus rigidly coupled (in translation as well as in rotation) to the proximal body 14.

[0103] Here again, rotational indexing means 20 are provided between the connecting body 10 and the distal body 15 of the distal section 2d. We see more particularly on the figure, which is a cross-section along the transverse plane PT3, that: - the connecting means 16 comprise a section T2 (of the connecting rod 17) with a non-circular cross-section, - the distal transverse wall 23 of the connecting body 10 comprises a through passage 23a with a non-circular cross-section in which the section T2 with a non-circular cross-section of the connecting means 16 is engaged by sliding, - said non-circular cross-sections of the section T2 and the through passage 23a cooperate by interference of shapes to prohibit any relative rotation around the longitudinal direction II between the connecting body 10 and the distal body 15 of the distal section 2d (via the proximal body 14 to which the distal body 15 is rigidly coupled).

[0104] The second embodiment requires a tube 21 with a simpler shape than the first embodiment. Here, only an internally threaded tubular section T1 is needed to receive the connecting body 10 by screwing it in.

[0105] The compressible tensile damping elements 11 and thrust damping elements 12 again have a general annular shape to allow passage of the connecting means 16 (compressible tensile damping element 11) and to increase compactness through deformation that occurs partly radially inwards during compression. If compactness is not critical, the compressible tensile damping element 11 can be in the form of a solid cylinder (as in Figures 10 to 12 and 14).

[0106] The compressible tensile damping element 11 is fixed to the second transverse tensile surface STT2. The compressible thrust damping element 12 is fixed to the second transverse thrust surface STP2.

[0107] The shock damping during the operation of the linear actuator 1 is explained by means of figures 17 and 18.

[0108] On the, the mobile thrust element 2 receives on its distal body 15 a thrust along the longitudinal direction II and illustrated by the arrow P. Under the effect of this thrust, the distal body 15 slides relative to the connecting body 10. The compressible thrust damping element 12 is then compressed between the first STP1 and second STP2 transverse thrust surfaces, and its radial deformation (in the direction of and away from the longitudinal direction II) thus dampens part of the stresses induced on the helical connection 5 by the thrust.

[0109] On the, the mobile thrust element 2 receives on its distal body 15 a tension along the longitudinal direction II and illustrated by the arrow T. Under the effect of this tension, the distal body 15 slides relative to the connecting body 10, taking with it the proximal body 14. The compressible tension damping element 11 is then compressed between the first STT1 and second STT2 transverse tension surfaces, and its radial deformation (in the direction of and away from the longitudinal direction II) thus dampens part of the stresses induced on the helical connection 5 by the tension.

[0110] The alternative in figures 17 and 18 thus makes it possible to cushion the shocks during both sudden pushes and sudden pulls.

[0111] Figure 1 illustrates an alternative (not part of the invention) linear actuator 1 primarily subjected to sudden thrusts. It provides only a single compressible damping element, namely the compressible thrust damping element 12, interposed between the first STP1 and second STP2 transverse thrust surfaces. When the compressible thrust damping element 12 is at rest (held between the first STP1 and second STP2 transverse thrust surfaces without being compressed, or only very slightly), the first STP1 and second STP2 transverse traction surfaces are in contact with each other.

[0112] In the alternative of the, there is damping of sudden pushes, but there is no damping of sudden pulls.

[0113] Figure 1 illustrates an alternative linear actuator 1 primarily subjected to sudden pulls. Only a single compressible damping element is provided, namely the compressible tension damping element 11, interposed between the first STT1 and second STT2 transverse tension surfaces. When the compressible tension damping element 11 is at rest (held between the first STT1 and second STT2 transverse tension surfaces without being compressed, or only very slightly), the first STT1 and second STT2 transverse thrust surfaces are in contact with each other.

[0114] In the alternative of the, there is damping of sudden pulls, but there is no damping of sudden pushes.

[0115] The compressible tension damping element 11 and / or the compressible thrust damping element 12 may in particular be: - a block of an elastomeric material, - a spring, - a Belleville washer.

[0116] The compressible tension damping elements 11 and thrust damping elements 12 can be of the same type (for example, both made of an elastomeric material) or of different types (for example, one made of an elastomeric material and the other a spring). Their compressibility can also be identical or different, depending in particular on the direction, frequency, and intensity of the shocks to be endured during the operation of the linear actuator 1.

[0117] The present invention is not limited to the embodiments that have been explicitly described, but includes the various variants and generalizations contained within the scope of the following claims.

Claims

Linear actuator (1) comprising a moving thrust element (2) that can be moved linearly along a longitudinal direction (II) in an external tube (3), said moving thrust element (2) being movable by actuation means (4) with helical connection (5) between a retraction position and at least one extension position relative to said external tube (3), the moving thrust element (2) extending between a proximal end (2a) and a distal end (2b) and comprising a proximal section (2c) subjected to displacement by the actuation means (4) with helical connection (5), in which said moving thrust element (2) further comprises: - a connecting body (10), adapted to be fixedly attached to a free end of the proximal section (2c), and comprising: a first transverse traction surface (STT1) oriented towards the proximal end (2a) of the moving thrust element (2),a first transverse thrust surface (STP1) oriented towards the distal end (2b) of the moving thrust element (2), - a distal section (2d) adapted to be coupled to a load to be moved, slidably arranged along the longitudinal direction (II) relative to the connecting body (10), and comprising: a second transverse traction surface (STT2) oriented towards the distal end (2b) of the moving thrust element (2), a second transverse thrust surface (STP2) oriented towards the proximal end (2a) of the moving thrust element (2), characterized in that said linear actuator (1) comprises a compressible traction damping element (11), arranged longitudinally between the first transverse traction surface (STT1) and the second transverse traction surface (STT2). Linear actuator (1) according to claim 1, characterized in that it comprises a compressible thrust damping element (12), arranged longitudinally between the first transverse thrust surface (STP1) and the second transverse thrust surface (STP2). Linear actuator (1) according to one of claims 1 or 2, characterized in that: - the connecting body (10) comprises a transverse wall (13) carrying the first transverse traction surface (STT1) and the first transverse thrust surface (STP1) on either side of said transverse wall (13), - the distal section (2d) comprises: a proximal body (14) comprising the second transverse traction surface (STT2), a distal body (15) comprising the second transverse thrust surface (STP2), connecting means (16) engaged by sliding through the transverse wall (13) of the connecting body (10) and rigidly coupling the proximal body (14) to the distal body (15). Linear actuator (1) according to claim 3, characterized in that the connecting means (16) comprise a connecting rod (17) passing through the center of the transverse wall (13) of the connecting body (10). Linear actuator (1) according to claim 4, characterized in that it comprises rotational indexing means (20) between the connecting body (10) and the distal body (15) of the distal section (2d), preferably by means of keys (20a, 20b) allowing longitudinal sliding of the distal body (15) of the distal section (2d) relative to the connecting body (10). Linear actuator (1) according to claim 3, characterized in that the connecting means (16) comprise a plurality of connecting rods (17a-17h) eccentric radially with respect to the center of the transverse wall (13) of the connecting body (10). Linear actuator (1) according to any one of claims 3 to 6, characterized in that: - the connecting body (10) has a cylindrical side wall (10a) in which the distal body (15) is guided by sliding motion, - the proximal section (2c) of the moving thrust element (2) comprises a tube (21) with a cylindrical side wall (21a) in which the proximal body (14) of the distal section (2d) is guided by sliding motion. Linear actuator (1) according to claim 1 or 2, characterized in that: - the connecting body (10) comprises: a proximal transverse wall (22), carrying the first transverse thrust surface (STP1), a distal transverse wall (23), carrying the first transverse traction surface (STT1), a cylindrical lateral wall (10a), - the distal section (2d) comprises: a proximal body (14) disposed longitudinally between the proximal transverse wall (22) and the distal transverse wall (23), and carrying the second transverse traction (STT2) and thrust (STP2) surfaces, said proximal body (14) being guided by sliding by the cylindrical lateral wall (10a) of the connecting body (10), a distal body (15), connecting means (16) engaged by sliding through the distal transverse wall (23) of the connecting body (10) and rigidly coupling the proximal body (14) to the distal body (15). Linear actuator (1) according to claim 8, characterized in that the connecting means (16) comprise: - a connecting rod (17) which extends from and away from the proximal body (14), comprising a threaded free end (170) and passing through the center of the distal transverse wall (23) of the connecting body (10), - an internally threaded housing (24) provided in the distal body (15), suitable for receiving by screwing the threaded free end (170) of the connecting rod (17). Linear actuator (1) according to claim 9, characterized in that it comprises rotational indexing means (20) between the connecting body (10) and the distal body (15) of the distal section (2d). Linear actuator (1) according to claim 10, characterized in that: - the connecting means (16) comprise a section (T2) with a non-circular cross-section, - the distal cross-wall (23) of the connecting body (10) comprises a through passage (23a) with a non-circular cross-section in which the section (T2) with a non-circular cross-section of the connecting means (16) is slidably engaged, - said non-circular cross-sections cooperate by interference of shapes to prohibit any relative rotation around the longitudinal direction (II) between the connecting body (10) and the distal body (15) of the distal section (2d). Linear actuator (1) according to any one of claims 1 to 11, characterized in that the compressible tension damping element (11) or the compressible thrust damping element (12): - is a block of an elastomeric material, - is a spring, - is a Belleville washer.

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