Recirculation deflector with internal and external recirculation, and associated ball screw mechanism

Abstract

The invention relates to a recirculation deflector (22) intended to be accommodated in a receiving cavity (24) of a threaded recirculating member (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 raceway of the threaded recirculating member (13), a reference radial direction (300), which is centrifugal or centripetal, and a functional recirculation zone (30) having at least two distinct and separate recirculation paths (34, 36) intended to guide balls of the ball screw mechanism (10) out of the raceway, characterised in that the at least two distinct and separate recirculation paths (34, 36) comprise an internal recirculation path (34) and an external recirculation path (36).

Description

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 aerospace, robotics, and automotive. Their operating principle is based on the interposition of balls between the screw's threaded shaft 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 classified into two types, depending on how the closed-loop circulation of the balls within the mechanism is achieved. In internal recirculation mechanisms, the balls follow a helical path for slightly less than one revolution between the two threaded members. They are then deflected from one end of this helical path to the other by a recirculator attached to one of the threaded members, called the recirculation threaded member. This recirculation member allows the balls to pass through a thread of the other threaded member without losing contact with it. The resulting recirculation path is described as S-shaped due to its contour.In so-called external recirculation mechanisms, the balls follow a helical path over several turns between the two threaded components. At the recirculating threaded component, a recirculation channel causes the balls to lose contact with the other threaded component 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 component 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 thread flanks of the screw and nut. The mechanism's efficiency, the ratio of energy delivered to energy supplied, depends on the friction within the mechanism. This friction is generated by the contact of the active balls with each other in the loaded area between the thread flanks of the screw and nut, and to a lesser extent by the contact between the balls passing through the recirculation zones.

[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 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 ball chipping failures. Furthermore, the number of balls simultaneously present in the recirculation channel increases proportionally. Thus, external recirculating ball screw mechanisms face a difficult trade-off 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 low 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 for the recirculators in the recirculating threaded element, and distributing these recesses along the entire length of the recirculating threaded element. These constraints result in longer machining times, and sometimes even the impossibility of machining when the desired recess location is inaccessible. They also result in reduced axial compactness, as a significant portion of the recirculating threaded element's thread remains unused.

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

[0008] The invention aims to remedy the disadvantages of the prior art and to propose a recirculator enabling efficient recirculation combining the advantages of both recirculation methods, 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, intended to be housed in a housing 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 rotated 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 intended to guide balls of the ball screw mechanism out of the thread,remarkable 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 extremities located radially at the same distance D1 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 D1, the second of the two external extremities being located radially set back from the first of the two external extremities, viewed in the radial reference direction, the two external extremities being located radially at a distance H from each other.

[0010] The recirculation deflector allows two distinct and separate types of recirculation to be achieved on the same recirculating threaded element having a helical bearing path of pitch L1 and radius D1, directly adjacent in a reduced footprint and in a common housing cavity, requiring only one machining operation of the recirculating threaded element.

[0011] In one embodiment, the two inner ends are tangent to two separate turns of a helix of radius D1 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 D1 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 D1 and constant pitch centered on the reference axis, so as to allow the external trajectory to connect with the trajectory described by the balls on the helix of radius D1 and circulating between the threads of the recirculating threaded element.

[0012] In one embodiment, the second of the two external ends is tangent to a cylinder of radius D1+H centered on the reference axis, allowing the balls of the external recirculating circuit to move smoothly from the thread to an external recirculation path formed within the recirculating threaded element, i.e., without any step. In this configuration, 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 D1+H. In this configuration, the second of the two external ends is preferably parallel to the reference axis.

[0013] Preferably, the internal path includes an intermediate portion located radially recessed from 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 R0, such that 2R0 <L1, et R0<|D2-D1|. Les dimensions de la trajectoire interne du chemin de recirculation interne sont choisies pour permettre à des billes ayant un diamètre égal à 2R0 d’être déviées axialement d’une valeur L1 correspondant au pas d’hélice de l’organe fileté à recirculation, qui est toujours supérieur à un diamètre de billes 2R0, et radialement d’une valeur sufficient to cross the thread separating two adjacent turns of the rolling path of the other threaded element, the height of which is always less than the ball radius R0.

[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] In 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 secure it in the housing cavity.

[0016] In one embodiment, the external recirculation path is formed by walls of the recirculation deflector which, viewed in any cross-sectional plane perpendicular to the external path, form an open profile. The external recirculation path is then designed to face complementary walls of the threaded recirculation element, so as to form, in any cross-sectional plane perpendicular to the external path, a set of guide walls that is closed upon itself.

[0017] In one embodiment, the internal recirculation path is formed by walls of the recirculation deflector which, viewed in any cross-sectional 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 cross-sectional 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] In one embodiment, the recirculation deflector is made in a single piece. It can be manufactured by machining, 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 apart from each other, the recirculating threaded assembly further comprising at least one recirculation channel opening into the two housing cavities and positioned radially apart from the external helical raceway, set back from 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 housing cavities, 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 onto 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 also 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 results in a high capacity and good efficiency.Furthermore, the dual-function, double-recirculating deflector gives the threaded assembly and mechanism excellent axial compactness, since the effective 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 only two housing cavities and a similarly limited housing cavity size.

[0023] If the recirculation deflector includes a functional positioning area 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 complementary area to the functional positioning area of ​​the recirculation deflector. If the functional positioning area includes at least one positioning shoulder, preferably two positioning shoulders rotated radially in the reference radial direction, the complementary area 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 anti-misfit features and / or a fixing hook.

[0024] In one embodiment, the two inner ends are continuous with a pitch line of the internal helical raceway, and the internal recirculation path, present at both inner ends of the wall path, 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 path, 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 within the recirculating threaded element or on an external face of the recirculating threaded element.

[0026] Assuming the external recirculation path is formed by walls of the recirculation deflector which, viewed in any cross-sectional 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 can be a screw. However, preferably, the recirculating threaded element is a nut, with the radial thread direction 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, in a particularly advantageous embodiment, the nut has 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 above, a complementary threaded member, having a complementary helical thread rotated radially towards the helical thread of the recirculating threaded member, external recirculating balls housed in a volume delimited at least partially by the external helical raceway, 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 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 previously. 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] Laillustre, in a cross-sectional view, shows an assembly according to a first embodiment, the assembly comprising a nut and two recirculation deflectors.

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

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

[0036] Laillustre, in an isometric view, the recirculation deflector of the first embodiment.

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

[0038] Laillustrate a view in a cross-section along an internal recirculation trajectory of the mechanism.

[0039] Laillustre en perspective un dispositif compris un ensemble selon un deuxième embodiment, l'ensemble compris un vise et des baffles decirculants, et un noix part coupé coupé.

[0040] Laillustre en une vue isométrique, le deflecteur decirculer de l’ seconde embodiment.

[0041] Laillustre in a longitudinal sectional view the mechanism comprising the assembly according to the second embodiment and a nut.

[0042] The schematic illustration shows the assembly comprising a screw and four deflectors, one of which is a hybrid.

[0043] The schematic illustration shows the assembly comprising a screw, four deflectors including a triple one presenting three distinct recirculation paths.

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

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

[0046] The diagram 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 symbols across all 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 motion 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 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 datum axis 100 and the center of a mean radius of curvature of the flanks of the helical groove of said helical raceway. In addition, the nut 12 has an external annular surface 60 having a working area 62. The working area 62 may include a structural element and / or a coating that cannot be machined, such as a collar or a flange 64.

[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 recirculating threaded element 13 generally comprises a number 1 of recirculation channels (here, B=1). The recirculating threaded element 13 and the associated recirculating deflectors 22 form a threaded assembly 70. Each of the recirculating deflectors 22 can be made of metal, particularly lightweight metal, or preferably plastic. Each of the recirculating deflectors 22 is housed in a housing cavity 24 formed in the recirculating threaded element 13, and which passes through a thread 26 of the thread 18 of the recirculating threaded element 13, opening onto two areas 28 of the thread groove 18 on either side of the thread 26. The housing cavities 24 are here oriented radially and are through holes, but can 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 cavities24 may also have keying features, i.e. shapes or devices which ensure that the recirculation deflector22 can only be inserted correctly, thus avoiding assembly errors.

[0050] The threaded assembly 70 generally comprises N housing cavities 24 and M recirculation deflectors 22, with M N. In this embodiment, there are two housing cavities 24 and recirculation deflectors 22 (M=N=2), and each recirculation deflector 22 has a reference axis 200, which, after mounting 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 recirculation deflector 22 has a radial reference direction 300, which, after mounting in the associated housing cavity 24, is intended to be oriented in the same direction as the thread 18 of the recirculation 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+1 (here, Q=2).

[0051] In addition, each recirculation deflector22 presents a generally rectangular functional recirculation zone30 in which at least two distinct and disjoint recirculation paths34,36 are defined and, more specifically, at least one internal recirculation path34 and one external recirculation path36, so that each recirculation deflector22 can be described as a multiple deflector (in the sense that it presents several recirculation paths) and as a mixed deflector, also called a hybrid, in the sense that it presents 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 cross-sectional 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 T1 can then be defined step by step. This path 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 T1 has an S-shape, with two internal extremities 40 and 140 connected by an intermediate portion 42 comprising two curved transition zones 43 separated by a median zone 38. The two internal extremities 40 and 140 are located radially at the same distance D1 from the reference axis 100 and axially at a distance L1 from each other.The intermediate portion 42 is located radially inset from the two internal ends 40, 140, viewed in the radial reference direction 300, that is to say that 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 level. The bottom 50 is tangent to a bottom 44 of the net 26 at the internal ends 40, 140. The bottom 50 and the bottom 44 of the net 26 are, at the internal ends 40, 140, radially at the same distance from the net 26. The internal recirculation path 34 presents, in any plane perpendicular to the internal recirculation trajectory T1 in S, a concave profile with a radius of curvature greater at every point than a predetermined radius R0, such that. , And The two internal ends 40, 140 of the internal trajectory T1 open into the groove of the thread 18 of the recirculating threaded member 13, preferably at a point located on a pitch line of the groove of the thread 18 of the recirculating threaded member 13. The portion of the groove of the thread 18 located between the two internal ends 40, 140 defines a so-called internal raceway 18A, on 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, the internal recirculation raceway 34 and the groove of the thread 20 of the complementary threaded member constituted here by the screw 14. The two internal ends40,140 of the internal trajectoryT1 are located on the same helix of radiusD1 and constant pitch equal to the pitch P of the threaded recirculation member12 and centered on the reference axis100, and are oriented in opposite angular directions.

[0053] The external recirculation path 36 has at least one portion oriented in the centripetal reference direction 300 and another portion oriented in a direction parallel to the recirculation channel 32, itself parallel to the reference axis 100. The external recirculation path 36 describes an external path T2, which is a line formed by the successive centers of curvature of smallest radius of the external recirculation path 36. This external path 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 D1 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 with respect to the first 46 external end, viewed in the radial reference direction 300.More specifically, the two external ends46,48 are located radially at a distance H from each other, such that. The external recirculation path 36 has a bottom 52 which forms, at the first external guide end 46, a scoop projecting from the bottom 44 of the thread 18, in the radial reference direction 300, 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 recirculating threaded element 13. The first external guide end 46 is located on the same helix of radius D1 and constant pitch equal to the pitch P of the recirculating threaded element 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 D1 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 preferably formed when the recirculation deflector 22 is intended to be inserted into the nut 12, as illustrated in the figure.

[0056] Each recirculation deflector22 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 recirculating threaded 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 Figure 3, 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 ends48 of the two recirculation deflectors22 opening onto the recirculation channel32 allows a connection between the two axial ends of the recirculation channel32 and a portion of the thread groove18 of the recirculating threaded element13 which has several turns, preferably more than two turns, for example five turns or more, this portion being designated as a multi-turn bearing raceway or external bearing raceway18B.

[0058] In this embodiment, each mixed recirculation deflector 22 allows the recirculation of the balls 16A, 16B in two simultaneous but distinct ways: a part of the balls 16A is recirculated in an internal recirculation circuit, composed of the internal rolling track 18A on less than one turn of the helix of the thread 18, and the internal recirculation track 34; and another part of the balls 16B is recirculated in an external recirculation circuit, composed of the multi-turn rolling track 18B (in this embodiment, four turns), the recirculation channel 32 and the two external recirculation tracks 36 reformed in the two recirculation deflectors 22.

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

[0060] All the balls 16A of the internal recirculation circuit are in continuous contact with the two threaded members of the mechanism, or with 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 for 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 small 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 parts12,14 since they allow for the implementation of a recirculation comprising proportionally more balls than external recirculation, giving it a 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 with 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 at the two ends of the threaded recirculating member 13, which have 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 variant, the mechanism 10 may have only one mixed recirculation deflector 22. In this variant, the mechanism must include another recirculator with 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 variant can be used, in particular, if it is necessary to further reduce the axial dimensions of the mechanism 10, as this variant 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 can 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, variations 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 include 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 thread flanks with which the recirculation paths of said deflector must cooperate. For example, if either of the two threaded elements has a first portion with a mean radius of helical raceway R1 and a second portion with a mean radius of helical raceway R2, with R1 R2, this characteristic being sought to allow the reduction of the volume and / or quantity of material of at least a portion of the recirculating threaded element22 and / or the complementary threaded element, the same mechanism10 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 rolling paths 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 combined on the same recirculation deflector22, resulting in increased compactness, a reduction in the number of parts to be produced, and simplified assembly of a ball screw mechanism10 incorporating this type of recirculation deflector22. This combining, for example of two recirculation functions from two distinct recirculation paths on the same deflector, is made possible when the first external guide end46 and the second internal end140 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 axis100.The first external guide end46 and the first internal end40 are therefore juxtaposed, separated by a distance less than the width of the thread26, and open onto the two distinct turns of the helix.

[0068] Naturally, the examples shown in the figures and discussed above are given for illustrative purposes only and are not exhaustive. It is explicitly intended that the different embodiments illustrated can be combined to create other solutions.

Claims

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 helical 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 D1 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 set back from 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. Recirculation deflector (22) according to claim 1, characterized in that the two internal ends (40, 140) are tangent to two separate turns of a helix of radius D1 and constant pitch centered on the reference axis (100). 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 D1 and constant pitch centered on the reference axis (100). 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 D1+H centered on the reference axis (100). 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). Recirculation deflector (22) according to any one of the preceding claims, characterized in that the internal path (T1) comprises an intermediate portion (42) located radially recessed with respect to the two internal ends (40, 140), viewed in the radial reference direction (300), the intermediate portion (42) of the internal path (T1) 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 (T1) a concave profile with a radius of curvature greater at every point than a predetermined radius R0, such that , And . Recirculation deflector (22) according to claim 6, characterized in that . 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. 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 (T1), form an open profile. Recirculation deflector according to any one of the preceding claims, characterized in that it is made in one piece. 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 raceway (18B), and at least two housing cavities (24) opening onto the external raceway (18B) and located axially apart 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 apart 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 among the two housing cavities, and each having an external recirculation path (36) connecting the external helical raceway (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 (T1) of the internal recirculation path (34) of which open at two corresponding ends of an internal raceway (18A) formed by the thread. Threaded recirculation assembly according to claim 11, characterized in that the two internal ends (40, 140) are in continuity with a primitive line of the internal helical raceway (18A), and the internal recirculation raceway present at the two internal ends (40, 140) of the trajectory (T1) of the walls in continuity with the internal helical raceway (18A). Threaded recirculating 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) has at the level of the first external end (46) walls in continuity with the external helical raceway (18B). Threaded recirculating 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 threaded recirculating member (13), and the external recirculation path present at the level of the second external end (48) of the trajectory (T2) of the walls in continuity with the recirculation channel (32). Threaded recirculation 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. Recirculating threaded assembly according to any one of claims 11 to 15, characterized in that the recirculating threaded element is a nut, the radial direction of the thread being turned towards the helix axis. Threaded recirculating 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. 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 member, having a complementary helical thread turned radially towards the helical thread of the recirculating threaded member, 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 complementary helical raceway and the internal recirculation raceway.

Images