internal and external recirculation deflector, and associated ball screw mechanism

Abstract

A recirculation deflector (22) intended to be housed in a housing cavity (24) of a recirculating threaded member (13) of a ball screw mechanism (10), the recirculation deflector (22) having a reference axis (200) intended to coincide with a helical axis (100) of a helical raceway of the recirculating threaded member (13), a radial reference direction (300), centrifugal or centripetal, and a functional recirculation zone (30) having at least two distinct and disjoint recirculation paths (34,36) intended to guide balls of the ball screw mechanism (10) out of the raceway, characterized in that the at least two distinct and disjoint recirculation paths (34,36) comprise an internal recirculation path (34) and an external recirculation path (36). (Abstract figure: 2)

Description

Title of the invention: Internal and external recirculation deflector and associated ball screw mechanism. Technical field of the invention

[0001] The invention relates to a ball screw mechanism, and more specifically to a ball screw mechanism equipped with recirculators for connecting a groove in a thread of the ball screw mechanism to a recirculation channel of a threaded element of the ball screw mechanism. It also relates to a recirculator, also referred to hereafter as a recirculation deflector, for such a ball screw mechanism. Prior art

[0002] Ball screws are particularly efficient mechanical devices for transmitting linear and rotary motion, used in various fields such as aeronautics, robotics, and automotive engineering. Their operating principle is based on the interposition of balls between the threaded shaft of the screw and a nut. Thanks to this system, ball screws offer superior efficiency compared to traditional screw-nut devices, minimizing friction while allowing them to support significant loads.

[0003] Ball screws are primarily distinguished according to how the closed-loop circulation of the balls within the mechanism is achieved. In so-called internal recirculation mechanisms, the balls follow a helical trajectory for slightly less than one turn between the two threaded members, then are deflected from one end of this helical trajectory to the other by a recirculator connected to one of the two threaded members, called the recirculation threaded member, which allows them to pass through a thread of the other threaded member without losing contact with that other threaded member. The recirculation trajectory is then said to be S-shaped, due to its form.In so-called external recirculation mechanisms, the balls follow a helical path over several turns between the two threaded members. At the recirculating threaded member, a recirculation path causes the balls to lose contact with the other threaded member of the mechanism, forcing them to pass over several turns in a recirculation channel to connect the two ends of the helical path. In both types of ball screws, internal and external recirculation, the recirculating threaded member is most often the nut, but can also be the screw itself.

[0004] The capacity of a ball screw mechanism, which can be measured statically or dynamically by the load under which the mechanism remains functional without deteriorating, depends on various parameters, including the number and size of the active balls between the flanks of the screw and nut threads. The efficiency of the The mechanism, the ratio of energy delivered to energy supplied, depends on the friction in the mechanism, which is generated by the contact of the active balls with each other in the loaded area between the flanks of the screw and nut threads, and to a lesser extent by the contact between the balls passing through the recirculation areas.

[0005] To increase capacity without increasing the number of recirculators in external recirculation mechanisms, the number of turns in the helical path of the balls between the screw and the nut can be increased, thereby increasing the number of balls in contact with the thread flanks of the screw and nut. However, the contact forces between the balls, which push against each other progressively in the loaded zone, increase with the length of the helix in the loaded zone. This has a dual effect: it increases frictional forces with the thread flanks and increases the risk of failure due to ball spalling. Furthermore, the number of balls simultaneously present in the recirculation channel increases proportionally. Thus, external recirculating ball screw mechanisms face a difficult compromise between capacity and efficiency.

[0006] In internal recirculating ball screw mechanisms, the number of balls not in simultaneous contact between the flanks of the two threads is small compared to the total number of balls, which is favorable to efficiency. However, the number of revolutions is limited to one per recirculator, thus limiting capacity. The solution to increase capacity is to increase the number of recirculators. But this increase requires increasing the volume and / or the number of recesses reserved in the recirculating threaded element for the recirculators, and distributing these recesses along the entire length of the recirculating threaded element. These constraints result in longer machining times, and sometimes make machining impossible when the desired recess location is inaccessible.They also result in less axial compactness, as a significant portion of the threading of the recirculating threaded component remains unused.

[0007] The challenge then is to determine a means of recirculation combining the advantages of the two modes of recirculation, being efficient in terms of capacity, efficiency and axial compactness, while maintaining a great deal of freedom in the positioning of the recirculators and / or minimizing their number. Description of the invention

[0008] The invention aims to remedy the disadvantages of the prior art and to propose a recirculator allowing efficient recirculation combining the advantages of the two modes of recirculation, while being easy to produce so as not to increase production costs.

[0009] To this end, according to a first aspect of the invention, a recirculation deflector is proposed for housing in a cavity for a recirculating threaded element of a ball screw mechanism, the recirculation deflector having a reference axis intended to coincide with a helical axis of a helical thread of the recirculating threaded element, and a functional recirculation zone oriented in a radial reference direction, either towards the reference axis or in the opposite direction to the reference axis, the functional recirculation zone having at least two distinct and disjoint recirculation paths for guiding balls of the ball screw mechanism out of the thread, notable in that the at least two distinct and disjoint recirculation paths comprise: • an internal recirculation path rotated in the radial reference direction and describing an internal S-shaped trajectory with two internal ends located radially at the same distance DI from the reference axis and axially at a distance L1 from each other; and • an external recirculation path describing an external trajectory with two external extremities, the first of the two external extremities being located at a distance from the reference axis equal to the distance Dl, the second of the two external extremities being located radially inset from the first of the two external extremities, seen in the radial reference direction, the two external extremities being located radially at a distance H from each other.

[0010] The recirculation deflector makes it possible to achieve, on the same recirculating threaded element having a helical raceway of pitch L1 and radius Dl, two distinct and disjoint types of recirculation directly adjacent in a reduced footprint and in a common housing cavity, requiring only one machining operation of the recirculating threaded element.

[0011] According to one embodiment, the two inner ends are tangent to two separate turns of a helix of radius Dl and constant pitch centered on the reference axis, creating an internal recirculating circuit that minimizes the number of successive balls in contact under load. This helix of radius Dl corresponds to a helix described by the center of a ball of radius R0 circulating between the threads of the recirculating threaded element. Preferably, the first of the two outer ends is tangent to one of the two turns of the helix of radius Dl and constant pitch centered on the reference axis, in order to allow the external trajectory to connect with the trajectory described by the balls on the helix of radius Dl and circulating between the threads of the recirculating threaded element.

[0012] According to one embodiment, the second of the two external ends is tangent to a cylinder of radius Dl+H centered on the reference axis allowing the balls of the The external recirculation circuit allows for a smooth transition from the thread to an external recirculation path formed within the recirculating threaded element, i.e., without any steps. In this scenario, the recirculation path is preferably at a constant distance from the helix axis of the recirculating threaded element. It could, for example, be a cylinder whose axis is at a distance Dl+H. In this scenario, it is preferable that the second of the two external ends be parallel to the reference axis.

[0013] Preferably, the internal path comprises an intermediate portion located radially recessed with respect to the two internal extremities, viewed in the radial reference direction, the intermediate portion of the internal path being located at least partially at a distance D2 from the reference axis, the internal recirculation path having, in any plane perpendicular to the internal path, a concave profile with a radius of curvature greater at every point than a predetermined radius RO, such that 2RO <L1, et RO<ID2-D1I.The dimensions of the internal trajectory of the internal recirculation path are chosen to allow balls with a diameter equal to 2R0 to be deflected axially by a value L1 corresponding to the helix pitch of the recirculating threaded element, which is always greater than a ball diameter of 2R0, and radially by a value ID2 - DU sufficient to cross the thread separating two adjacent turns of the rolling path of the other threaded element, a thread whose height is always less than the ball radius RO.

[0014] Preferably, 2R0 <H. Les dimensions de la trajectoire externe du chemin de recirculation externe sont choisies quant à elles pour permettre un déport radial des billes d’une valeur H supérieure à la profondeur du chemin hélicoïdal de l’organe fileté de recirculation.

[0015] According to one embodiment, the recirculation deflector includes a functional positioning area intended to be housed, adjusted, or clamped into the housing cavity of the threaded recirculating element. Preferably, the functional positioning area includes at least one positioning shoulder, preferably two positioning shoulders rotated radially in the reference radial direction. The functional positioning area may have special shapes to facilitate the insertion and correct positioning of the recirculation deflector in the housing cavity. Preferably, the recirculation deflector includes keying features to prevent incorrect insertion into the housing cavity. If necessary, an elastic hook or other device may be provided on the recirculation deflector to allow the recirculation deflector to be held in the housing cavity if required.

[0016] According to one embodiment, the external recirculation path is formed by walls of the recirculation deflector which, seen in any cross-sectional plane perpendicular to the external trajectory, they form an open profile. The external recirculation path is then intended to face complementary walls of the recirculating threaded element, so as to form, in any cutting plane perpendicular to the external trajectory, a set of guide walls that is closed on itself.

[0017] According to one embodiment, the internal recirculation path is formed by walls of the recirculation deflector which, viewed in any cutting plane perpendicular to the internal path, form an open profile. The internal recirculation path is then designed to face complementary walls of the threaded element opposite the recirculating threaded element, so as to form, in any cutting plane perpendicular to the internal path, a set of guide walls that is closed upon itself.

[0018] The advantage of an open profile is that it simplifies the geometry of the recirculation deflector, and facilitates either its manufacture by molding in one or more pieces, or the machining of the recirculation paths if it is carried out, at least partially, by techniques with material removal.

[0019] According to one embodiment, the recirculation deflector is made in one piece. It can in particular be manufactured by machining, by additive manufacturing, or preferably by molding.

[0020] In the description just given, the radial reference direction can be oriented indifferently towards the reference axis (assuming the recirculating threaded element is a nut) or in the opposite direction (assuming the recirculating threaded element is a screw).

[0021] According to another aspect of the invention, it relates to a threaded assembly comprising a recirculating threaded element of a ball screw mechanism, the recirculating threaded element comprising: • a helical thread rotated radially in a radial thread direction, the thread defining a helix axis and forming an external helical raceway, and • at least two housing cavities opening onto the external raceway and located axially at a distance from each other, the recirculating threaded assembly further comprising • at least one recirculation channel opening into both housing cavities and positioned radially at a distance from the external helical raceway, recessed relative to the external helical raceway, viewed in the radial thread direction, • at least two recirculation deflectors, each housed at least partially in an associated housing cavity among the two cavities of housing and each having an external recirculation path connecting the external helical raceway to the recirculation channel, notable in that at least one of the two recirculation deflectors is a recirculation deflector as defined above, whose radial reference direction is oriented in the radial thread direction, and whose two internal ends of the internal S-shaped path of the internal recirculation path open at two corresponding ends of an internal raceway formed by the thread.

[0022] The assembly thus combines the advantages of an internal recirculation system and an external recirculation system in a particularly compact design. More specifically, the assembly as defined, and the ball screw mechanism in which it is inserted, allow for the selection of a helical raceway length between the two housing cavities, and therefore a recirculation channel length, that is sufficiently short to avoid excessive stress on the balls, while benefiting from an additional ball rotation thanks to the internal recirculation achieved by each of the double-recirculation deflectors according to the first aspect of the invention. This makes it possible to obtain a large capacity and good efficiency.Furthermore, the dual-function, double-recirculating deflector gives the threaded assembly and mechanism excellent axial compactness, since the useful areas of the helical raceway, guiding the balls in external recirculation on one side and the balls in internal recirculation on the other, are directly adjacent. This result is achieved with a limited number of housing cavities (only two) and a similarly limited housing cavity size.

[0023] If the recirculation deflector includes a functional positioning zone intended to be housed, fitted, or clamped within the housing cavity of the recirculating threaded element, the associated housing cavity of the recirculating threaded element preferably includes a zone complementary to the functional positioning zone of the recirculation deflector. If the functional positioning zone includes at least one positioning shoulder, preferably two positioning shoulders rotated radially in the radial reference direction, the complementary zone preferably includes one or more bearing surfaces against which the shoulder(s) of the recirculation deflector bear. Thus, the housing cavity is configured to accommodate the recirculation deflector while ensuring proper positioning of the part within it.In addition, the housing cavity may have counterforms if it is intended to accommodate a recirculation deflector including keying features and / or a fixing hook.

[0024] According to one embodiment, the two inner ends are continuous with a pitch line of the internal helical raceway, and the internal recirculation path, present at the two inner ends of the wall trajectory, is continuous with the internal helical raceway. Similarly, the first outer end is continuous with a pitch line of the external helical raceway of the recirculating threaded element, and the external recirculation path, present at the first outer end of the walls, is continuous with the external helical raceway. Furthermore, the second outer end opens tangentially into the recirculation channel of the recirculating threaded element, and the external recirculation path, present at the second outer end of the wall trajectory, is continuous with the recirculation channel.The recirculation deflector is sized to minimize sharp edges in contact with the balls, and to facilitate ball guidance.

[0025] The recirculation channel can be formed outside the recirculating threaded element, for example by an added part. However, preferably, the recirculation channel is formed in the recirculating threaded element or on an external face of the recirculating threaded element.

[0026] Assuming that the external recirculation path is made up of walls of the recirculation deflector which, seen in any cutting plane perpendicular to the external path, form an open profile, the associated housing cavity has walls which face the walls of the recirculation deflector which form the external recirculation path.

[0027] The recirculating threaded element may be a screw. However, preferably, the recirculating threaded element is a nut, with the radial direction of the thread facing the helix axis. In this case, the presence of external recirculation provides an additional advantage, which is to offer considerable design freedom for the portion of the nut's outer surface located between the two recirculation deflectors. Thus, according to a particularly advantageous embodiment, the nut comprises a flange located axially between the two housing cavities and axially at a distance from the two housing cavities.

[0028] Naturally, it is advantageous to symmetrical the threaded assembly and to provide two internal recirculation sections on either side of the external recirculation section. In this scenario, the other of the two recirculation deflectors is a recirculation deflector according to the first aspect of the invention, as described above. The two recirculation deflectors can then, if necessary, be identical.

[0029] According to another aspect of the invention, a ball screw mechanism notable in that it comprises: • a recirculating threaded assembly as described previously, • a complementary threaded element, having a complementary helical thread oriented radially towards the helical thread of the recirculating threaded element, • external recirculation balls housed in a volume delimited at least partially by the external helical raceway, the complementary helical mesh, the recirculation channel and the external recirculation path, and a second external recirculation path formed by a second recirculation deflector, • internal recirculation balls housed in a volume delimited at least partially by the internal helical raceway, the complementary helical raceway and the internal recirculation raceway.

[0030] Such a mechanism provides all the advantages discussed above. The second recirculation deflector can be a prior art recirculation deflector with a single recirculation path, in this case the second external recirculation path. Alternatively, the second recirculation deflector can also be a recirculation deflector according to the first aspect of the invention, as described above. The two recirculation deflectors can then, if necessary, be identical.

[0031] According to one embodiment, the external recirculation balls and the internal recirculation balls have the same diameter. Brief description of the figures

[0032] Other features and advantages of the invention will become apparent from the following description, with reference to the attached figures.

[0033] [Fig-1] Fig. 1 illustrates, in a cross-sectional view, an assembly according to a first embodiment, the assembly comprising a nut and two recirculation deflectors.

[0034] [Fig.2] Fig.2 illustrates a cross-sectional view of a mechanism comprising the assembly according to the first embodiment, a screw and balls.

[0035] [Fig.3] Fig.3 illustrates another cross-sectional view of the mechanism comprising the assembly according to the first embodiment, and a screw.

[0036] [Fig.4] Fig.4 illustrates, in an isometric view, the recirculation deflector of the first embodiment.

[0037] [Fig.5] The [Fig.5] illustrates a view in a cross-section of the mechanism comprising the assembly according to the first embodiment, and a screw.

[0038] [Fig.6] Fig.6 illustrates a view in a section along an internal recirculation trajectory of the mechanism.

[0039] [Fig.7] Fig.7 illustrates in perspective a mechanism comprising a set according to a second embodiment, the assembly includes a screw and recirculation deflectors, as well as a partially cut nut.

[0040] [Fig.8] Fig.8 illustrates in an isometric view the recirculation deflector of the second embodiment.

[0041] [Fig.9] Fig.9 illustrates in a longitudinal cross-sectional view the mechanism comprising the assembly according to the second embodiment and a nut.

[0042] [Fig. 10] Fig. 10 schematically illustrates the assembly comprising a screw and four deflectors, one of which is a hybrid.

[0043] [Fig. 11] Fig. 11 schematically illustrates the assembly comprising a screw, four deflectors, one of which is triple, presenting three distinct recirculation paths.

[0044] [Fig. 12] Fig. 12 schematically illustrates the assembly comprising a nut and four deflectors, two of which are hybrid.

[0045] [Fig. 13] Fig. 13 schematically illustrates the assembly comprising a screw, two recirculation channels and five deflectors, including two double hybrids and one triple hybrid.

[0046] [Fig. 14] Fig. 14 schematically illustrates the assembly comprising a nut, two recirculation channels and five deflectors, including two double hybrids and one triple hybrid.

[0047] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. Detailed description of implementation methods

[0048] Figures 1 to 6 illustrate a ball screw mechanism 10 comprising two threaded members, namely a nut 12 and a screw 14 aligned on a common reference axis 100, and balls 16A, 16B (Figure 2) disposed between a thread 18 of the nut 12 and a thread 20 of the screw 14, to guide the relative helical movement between the nut 12 and the screw 14. Each thread 18, 20 has a helical groove forming a number C of helical raceways, with C 2, and comprising at least one internal raceway 18A and one external multi-turn raceway 18B, both helical. The respective flanks of the helical raceways form a helical thread 26.72 of pitch P, following a profile that is constant in any cutting plane perpendicular to the helical thread. In this first embodiment C=3.Each of the helical raceways has a mean radius extending radially between the common reference axis 100 and the center of a mean radius of curvature of the flanks of the helical groove of said helical raceway. Furthermore, the nut 12 has an outer annular surface 60 having a useful area 62. The useful area 62. may include a structural element and / or a coating that cannot be machined, a collar or a flange 64 for example.

[0049] One of the two threaded elements, in this embodiment the nut 12, will be referred to hereafter as the recirculation threaded element 13, because it is equipped with two recirculation deflectors 22 and a recirculation channel 32, the other threaded element, here the screw 14, being designated as the complementary threaded element 15. The recirculation threaded element 13 generally comprises a number B > 1 of recirculation channels (here, B=1). The recirculation threaded element 13 and the associated recirculation deflectors 22 form a threaded assembly 70. Each of the recirculation deflectors 22 can be made of metal, particularly lightweight metal, or, preferably, of plastic. Each of the recirculation deflectors 22 is housed in a housing cavity 24 formed in the recirculation threaded member 13, and which passes through a thread 26 of the thread 18 of the recirculation threaded member 13, to open onto two areas 28 of the groove of the thread 18 on either side of the thread 26.The housing cavities 24 are here oriented radially and are through-holes, but may be blind holes, mortises for example. Each housing cavity 24 has side walls preferably parallel to a radial direction of the housing cavity 24, and two junction zones with the two zones 28 of the thread groove 18. The housing cavities 24 may further have keying features, i.e. shapes or devices which ensure that the recirculation deflector 22 can only be inserted correctly, thus preventing assembly errors.

[0050] The threaded assembly 70 generally comprises a number N of housing cavities 24 and a number M of recirculation deflectors 22, with M N. In this embodiment, there are two housing cavities 24 and recirculation deflectors 22 (M=N=2), and each of the recirculation deflectors 22 has a reference axis 200, which, after assembly in the associated housing cavity 24, is intended to coincide with the helix axis 100 of the thread 18 of the recirculation threaded element 13. Each of the recirculation deflectors 22 has a radial reference direction 300, which, after assembly in the associated housing cavity 24, is intended to be rotated in the same direction as the thread 18 of the recirculating threaded element 13, therefore, in this embodiment, towards the reference axis 200 and the helix axis 100.The threaded assembly 70 also includes a number Q of recirculation deflectors comprising at least one external recirculation path 36, with Q B+l (here, Q=2).

[0051] Furthermore, each recirculation deflector 22 has a generally rectangular functional recirculation zone 30 in which at least two distinct and disjoint recirculation paths 34, 36 are defined and, more specifically, at least one internal recirculation path 34 and one external recirculation path 36 , so that each recirculation deflector 22 can be described as a multiple deflector (in the sense that it has several recirculation paths) and a mixed deflector, also called a hybrid, in the sense that it has at least one internal recirculation path and at least one external recirculation path.

[0052] For each point on the wall of the internal recirculation path 34, it is possible to define a cutting plane passing through said point and perpendicular to the wall, in which the wall is concave and has a minimum radius of curvature. An internal recirculation path Tl can then be defined step by step, which is a line formed by the successive centers of curvature with the smallest radius of the internal recirculation path 34. This line also represents the successive passage points of the centers of the balls rolling on the walls of the internal recirculation path. This internal path Tl has an S-shape, with two internal ends 40, 140 connected by an intermediate portion 42 comprising two curved transition zones 43 separated by a median zone 38.The two internal ends 40, 140 are located radially at the same distance DI from the reference axis 100 and axially at a distance L1 from each other. The intermediate portion 42 is located radially recessed relative to the two internal ends 40, 140, viewed in the radial reference direction 300; that is, the intermediate portion 42 is located at least partially at a distance D2 from the reference axis 100, which is greater than D1, as illustrated in particular in Figures 3 and 6. The internal recirculation path has a bottom 50 radially closer to the thread 26 of the threaded element at the internal ends 40, 140 than at any other point. The bottom 50 is tangent to a bottom 44 of the thread 26 at the internal ends 40, 140. The bottom 50 and the bottom 44 of the net 26 are, at the level of the internal ends 40,140, ​​radially at the same distance from the net 26.The internal recirculation path 34 has, in any plane perpendicular to the internal recirculation trajectory Tl at S, a concave profile with a radius of curvature greater at every point than a predetermined radius R0, such that 2M) < L1, and R0 < ID2 - D1. The two internal ends 40, 140 of the internal trajectory Tl open into the groove of the thread 18 of the recirculating threaded element 13, preferably at a point located on a pitch line of the groove of the thread 18 of the recirculating threaded element 13. The portion of the groove of the thread 18 located between the two internal ends 40, 140 defines an internal raceway 18A, over less than one turn of the thread 18, for internally recirculating balls 16A, which circulate in a closed loop in a volume delimited by the internal raceway 18A. 34 and the thread groove 20 of the complementary threaded element constituted here by the screw 14.The two internal ends 40,140 of the internal trajectory Tl are located on the same helix of radius Dl and of constant pitch equal to the pitch P of the threaded organ. of recirculation 12 and centered on the reference axis 100, and are oriented in opposite angular directions.

[0053] The external recirculation path 36 has at least one part turned in the centripetal reference direction 300 and another part turned in a direction parallel to the recirculation channel 32, itself parallel to the reference axis 100. The external recirculation path 36 describes an external trajectory T2, which is a line formed by the successive centers of curvature of smallest radius of the external recirculation path 36. This external trajectory T2 has an L shape with a first external guide end 46 and a second external guide end 48, between which extends a transitional portion 51.The first external guide end 46 is located at the same distance DI from the reference axis 100 as the two internal guide ends 40, 140, the second 48 of the two ends of the external recirculation path 36 being located radially recessed relative to the first 46 external end, viewed in the radial reference direction 300. More specifically, the two external ends 46, 48 are located radially at a distance H from each other, such that 2Φ0 < H. The external recirculation path 36 has a bottom 52 which forms, at the first external guide end 46, a scoop projecting relative to the bottom 44 of the thread 18, in the radial reference direction 300, and then, from the first external guide end 46 to the second external guide end 48, moves radially away continuously from the thread 26 of the thread 18 of the threaded member. recirculator 13.The first external guide end 46 is located on the same helix of radius DI and constant pitch equal to the pitch P of the recirculating threaded member 13 and centered on the reference axis 100, as the two internal guide ends 40,140.

[0054] Preferably, the first external guide end 46 and the second internal end 140 open in opposite directions onto the same helix turn of radius DI and constant pitch centered on the reference axis 100. The first external guide end 46 and the first internal end 40 are adjacent, separated axially by a distance equal to the pitch P, and by one helix turn from each other.

[0055] Each recirculation deflector 22 further comprises a positioning base 54 opposite the recirculation functional zone 30. The positioning base 54 is connected to the recirculation functional zone 30 by a connecting functional zone 56. The positioning base 54 and / or the connecting functional zone 56 may have shoulders 58 and / or positioning shapes, flats or elastic tabs, for example, forming counterforms of the housing cavity 24 and its locating features in which the positioning base 54 and / or the connecting functional zone 56 are intended to be housed. The shoulders 58 are of preference formed when the recirculation deflector 22 is intended to be inserted into the nut 12, as illustrated in [Fig.1].

[0056] Each recirculation deflector 22 can be made in one piece, for example by additive manufacturing, or preferably by molding, because it has few undercuts.

[0057] An assembly 70 is formed when the mixed recirculation deflectors 22 are in the operating position, i.e. housed in the associated housing cavities 24 of the threaded recirculating recirculation element 13. The axial offset between the two internal ends 40,140 of the internal recirculation path 34 allows the balls to pass through the thread 26 of the thread 18, as illustrated in [Fig. 6], radially bypassing a thread 72 of the thread 20 and thus achieving internal recirculation on one turn of the helix of the thread 18. The radial offset between the first external guide end 46 and the second external guide end 48 allows the thread 18 and the recirculation channel 32 to be continuously linked, as illustrated in Figures 3 to 5, the recirculation channel 32 being tangent to the second external guide end 48 and the thread 18 being tangent to the first external guide end 46.Finally, the axial offset between the second external guide ends 48 of the two recirculation deflectors 22 opening onto the recirculation channel 32 allows a connection between the two axial ends of the recirculation channel 32 and a portion of the thread groove 18 of the recirculating threaded element 13 which has several turns, preferably more than two turns, for example five turns or more, this portion being designated as the multi-turn bearing raceway or external bearing raceway 18B.

[0058] In this embodiment, each mixed recirculation deflector 22 allows the recirculation of the balls 16A, 16B in two simultaneous but distinct ways: • a portion of the balls 16A is recirculated in an internal recirculating circuit, consisting of the internal raceway 18A over less than one turn of the helix of the thread 18, and the internal recirculation raceway 3 4; and • another part of the balls 16B is in recirculation in an external recirculation circuit, consisting of the multi-turn rolling track 18B (in this embodiment, four turns), the recirculation channel 32 and the two external recirculation paths 36 formed in the two recirculation deflectors 22.

[0059] Thus, the ball screw mechanism 10 comprising two mixed recirculation deflectors 22 and has two internal recirculation circuits positioned axially on either side of an external recirculation circuit, directly adjacent to the latter.

[0060] All the 16A balls of the internally recirculating circuit are in continuous contact with the two threaded members of the mechanism or one of the two threaded members and the Internal recirculation path 34, and all are active, in the sense that they can transmit a load between the two threaded members, except those located on the internal recirculation path 34. The internal recirculation circuit, which has only slightly less than one helix turn between the two internal ends 40, 140, allows for a significant increase in load, but with a slight increase in friction. During operation, the ball 16B of the external recirculation circuit subjected to the greatest stress is the one that, in the direction of rotation, pushes the others at one of the end turns. It is therefore advantageous to have internal recirculation circuits at both ends of the threaded members 12, 14, since they allow for recirculation with a proportionally larger number of balls than external recirculation, giving it better efficiency, and thus helping to support a greater load.

[0061] Such a ball screw mechanism 10 thus allows, via the external recirculation circuit, a nut 12 having an unmachined outer annular surface 60 in the working area 62. In this way, the coating or element of the outer annular face 60 of the nut 12 is not damaged. Furthermore, the two internal recirculation circuits located respectively at the two ends of the recirculating threaded member 13, having increased resistance to the stresses to which the balls of these internal recirculation circuits are subjected, support the external recirculation circuit.

[0062] According to another embodiment illustrated in figures 7 to 13, 18 and 20, the recirculating threaded member 13 is the screw 14. The radial reference direction 300 is then opposite to that of the previous embodiment and the recirculation channel 32 is in the body of the screw 14.

[0063] According to an unillustrated embodiment, the mechanism 10 may have only one mixed recirculation deflector 22. In this embodiment, it is then necessary for the mechanism to include another recirculator having only the function of an external recirculator (known in the prior art), so that the external recirculation circuit initiated by the recirculation deflector 22 is closed. This embodiment can be used, in particular, if it is necessary to further reduce the axial dimensions of the mechanism 10, as this embodiment allows for the elimination of one turn.

[0064] According to another variant, illustrated in Figures 13 and 14, the recirculation deflector 22 can be triple, that is, have three distinct recirculation paths. For example, the triple mixed recirculation deflector 22 can have two successive internal recirculation paths and one external recirculation path. Also, if the mechanism 10 has an additional recirculation channel 32', and more particularly located substantially near the recirculation channel 32, the Triple recirculation deflector 22 may have an internal recirculation path between two external recirculation paths, each external recirculation path being linked to one of the two recirculation channels.

[0065] Of course, variants of these mixed recirculators can be implemented with a predetermined number of internal recirculation paths between the two external recirculation paths. In other words, a mixed recirculator can comprise at most two external recirculation paths and any number of internal recirculation paths, provided that each external recirculation path has only one adjacent internal recirculation path.

[0066] Each deflector generally has dimensions that depend on the radius and pitch of the helix as well as the radius of curvature of the flanks of the thread with which the recirculation paths of said deflector must cooperate.For example, if either of the two threaded elements has a first portion of average radius of helical raceway RI and a second portion of average radius of helical raceway R2, with RI * R2, this characteristic being sought to allow the volume and / or quantity of material of at least a portion of the recirculating threaded element 22 and / or the complementary threaded element to be reduced, the same mechanism 10 of variable helix radius may have two double hybrid recirculators, having an internal recirculation path and an external recirculation path and intended to open onto distinct helical raceways of different dimensions, each disposed on a portion of the thread of different helix radius.

[0067] In summary, double or triple and / or hybrid deflectors allow the recirculation functions of two or three distinct recirculation paths to be shared on a single recirculation deflector 22, resulting in increased compactness, a reduction in the number of parts to be produced, and simplified assembly of a ball screw mechanism 10 comprising this type of recirculation deflector 22. This sharing, for example of two recirculation functions of two distinct recirculation paths on the same deflector, is made possible when the first external guide end 46 and the second internal end 140 open onto the same helix turn with a radius identical to the average radius of the helical raceway and a constant pitch centered on the reference axis 100.The first external guide end 46 and the first internal end 40 are therefore juxtaposed, separated by a distance less than the width of the thread 26, and open onto the two distinct turns of the helix.

[0068] Naturally, the examples shown in the figures and discussed above are given only by way of illustration and are not intended to be limiting. It is explicitly intended that one can combine the different illustrated methods of implementation to propose others.

Claims

Demands

1. A recirculation deflector (22) intended to be housed in a housing cavity (24) of a recirculating threaded element (13) of a ball screw mechanism (10), the recirculation deflector (22) having a reference axis (200) intended to coincide with a helix axis (100) of a helical thread of the recirculating threaded element (13), and a recirculation functional zone (30) rotated in a radial reference direction (300), either towards the reference axis or away from the reference axis, the recirculation functional zone (30) having at least two distinct and disjoint recirculation paths (34, 36) intended to guide balls of the ball screw mechanism (10) out of the thread, characterized in that the at least two recirculation paths (34,36) distinct and disjoint include: - an internal recirculation path (34) rotated in the radial reference direction (300) and describing an internal S-shaped path (T1) with two internal extremities (40, 140) located radially at the same distance DI from the reference axis (200) and axially at a distance L1 from each other; and - an external recirculation path (36) describing an external path (T2) with two external extremities, a first (46) of the two external extremities being located at a distance from the reference axis (200) equal to the distance D1, a second (48) of the two external extremities being located radially recessed with respect to the first (46) of the two external extremities, viewed in the radial reference direction (300), the two external extremities (46, 48) being located radially at a distance H from each other.

2. Recirculation deflector (22) according to claim 1, characterized in that the two inner ends (40, 140) are tangent to two separate turns of a helix of radius Dl and constant pitch centered on the reference axis (100).

3. Recirculation deflector (22) according to claim 2, characterized in that the first (46) of the two external ends is tangent to one of the two turns of the helix of radius Dl and constant pitch centered on the reference axis (100).

4. Recirculation deflector (22) according to any one of the preceding claims, characterized in that the second (48) of the two external ends is tangent to a cylinder of radius Dl+H centered on the reference axis (100).

5. Recirculation deflector (22) according to claim 4, characterized in that the second (48) of the two external ends is parallel to the reference axis (100).

6. Recirculation deflector (22) according to any one of the preceding claims, characterized in that the internal path (Tl) comprises an intermediate portion (42) located radially recessed with respect to the two internal extremities (40, 140), viewed in the radial reference direction (300), the intermediate portion (42) of the internal path (Tl) being located at least partially at a distance D2 from the reference axis (200), the internal recirculation path (34) having in any plane perpendicular to the internal path (Tl) a concave profile with a radius of curvature greater at every point than a predetermined radius R0, such that 2R0 < Ll, and R0 < ID2-D1I.

7. Recirculation deflector (22) according to claim 6, characterized in that 2M) < H.

8. Recirculation deflector according to any one of the preceding claims, characterized in that the external recirculation path (36) is constituted by walls of the recirculation deflector (22) which, seen in any cutting plane perpendicular to the external path (T2), form an open profile.

9. Recirculation deflector according to any one of the preceding claims, characterized in that the internal recirculation path (34) is constituted by walls of the recirculation deflector (22) which, seen in any cutting plane perpendicular to the internal path (Tl), form an open profile.

10. Recirculation deflector according to any one of the preceding claims, characterized in that it is made in one piece.

11. A recirculating threaded assembly comprising a recirculating threaded element (13) of a ball screw mechanism (10), the recirculating threaded element (13) comprising: - a helical thread rotated radially in a radial thread direction, the thread defining a helix axis and forming an external helical bearing track (18B), and - at least two housing cavities (24) opening onto the external raceway (18B) and located axially at a distance from each other, the recirculating threaded assembly further comprising - at least one recirculation channel (32) opening into the two housing cavities (24) and positioned radially at a distance from the external helical raceway (18B), set back from the external helical raceway (18B), viewed in the radial thread direction, - at least two recirculation deflectors, each housed at least partially in a housing cavity (24) associated with one of the two housing cavities, and each having an external recirculation path (36) connecting the external helical rolling path (18B) to the recirculation channel (32), characterized in that at least one of the two recirculation deflectors is a recirculation deflector (22) according to any one of the preceding claims, the radial reference direction (300) of which is oriented in the radial thread direction, and the two internal ends (40, 140) of the internal S-shaped path (Tl) of the internal recirculation path (34) open at two corresponding ends of an internal rolling path (18A) formed by the thread.

12. Recirculating threaded assembly according to claim 11, characterized in that the two internal ends (40, 140) are in continuity with a pitch line of the internal helical raceway (18A), and the internal recirculation raceway present at the two internal ends (40, 140) of the path (Tl) of the walls in continuity with the internal helical raceway (18A).

13. A recirculating threaded assembly according to any one of claims 11 to 12, characterized in that the first external end (46) is in continuity with a pitch line of the external helical raceway (18B) of the recirculating threaded member (13), and the external recirculation raceway (36) is present at the first end external (46) of the walls in continuity with the external helical rolling path (18B).

14. Recirculating threaded assembly according to any one of claims 11 to 13, characterized in that the second external end (48) opens tangentially into the recirculation channel (32) of the recirculating threaded member (13), and the external recirculation path present at the second external end (48) of the path (T2) of the walls in continuity with the recirculation channel (32).

15. Recirculating threaded assembly according to any one of claims 11 to 14, wherein the recirculation deflector (22) is according to claim 8, characterized in that the associated housing cavity has walls facing the walls of the recirculation deflector which form the external recirculation path.

16. Recirculating threaded assembly according to any one of claims 11 to 15, characterized in that the recirculating threaded member is a nut, the radial direction of the thread being turned towards the helix axis.

17. Recirculating threaded assembly according to claim 16, characterized in that the nut comprises a flange (64) located axially between the two housing cavities, and axially at a distance from the two housing cavities.

18. Ball screw mechanism (10) characterized in that it comprises: - a recirculating threaded assembly according to any one of claims 11 to 17, - a complementary threaded element, having a complementary helical thread oriented radially towards the helical thread of the recirculating threaded element, - external recirculating balls (16B) housed in a volume delimited at least partially by the external helical raceway (18B), the complementary helical thread, the recirculation channel and the external recirculation raceway, and a second external recirculation raceway formed by a second recirculation deflector, - internal recirculating balls (16A) housed in a volume delimited at least partially by the internal helical raceway (18A), the raceway complementary helical and internal recirculation pathway.

Images