ONE-PIECE RECIRCULATION PART, RECIRCULATION THREADED COMPONENT AND BALL SCREW MECHANISM

Abstract

A one-piece recirculation part (22) intended to be housed in a cavity (24) of a threaded member (12, 14) of a ball screw mechanism (10) comprises a base (32), turned in a reference direction (200) of a reference axis (300), a recirculation path (34) turned in the opposite direction and intended to pass through a thread (26) of the threaded member (12, 14), and at least one deflector (48), projecting from the recirculation path (34) in the opposite direction to the reference direction (200). The deflector (48) forms a guide face (50) located at a distance from the recirculation path (34) and turned in the reference direction (200), opposite a light (52) in the one-piece part (22) which extends parallel to the reference axis (300) and opens onto the bottom (32) and onto the recirculation path (34).In orthogonal projection onto a reference plane (400) perpendicular to the reference axis (300), the first light (52) surrounds or coincides with the guiding face (50) of the first deflector (48). (Abstract figure: Figure 4).

Description

Title of the invention: MONOBLOCK RECIRCULATION PART, RECIRCULATION THREADED PART AND 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 two adjacent portions of a groove in a thread of the ball screw mechanism on either side of a thread. It relates in particular to a recirculator for such a mechanism, and to a recirculating threaded element, which may be a screw or a nut, incorporating such a recirculator. PREVIOUS STATE OF THE ART

[0002] Document EP 1 537 345 B1 describes a ball screw mechanism in which the nut has a ball guide thread and is equipped with a one-piece recirculation element housed in a nut cavity. This element passes through one thread of the screw to define an S-shaped recirculation path connecting two portions of the thread groove on either side of the thread. The one-piece recirculation element has guide faces designed to deflect the balls along the S-shaped path. Direct molding of the element would be impossible due to excessive undercuts. Therefore, the one-piece element consists of two half-pieces connected by a hinge, allowing the element to be molded in the open position in an axial mold, and then closed in its final operational position. However, such a manufacturing method remains complex. Description of the invention

[0003] The invention aims to remedy the drawbacks of the prior art and to provide a single-piece recirculation unit that is simple to manufacture.

[0004] To this end, according to a first aspect of the invention, a

[0005] Monobloc recirculation part intended to be housed in a cavity of a threaded element of a ball screw mechanism, the monobloc recirculation part having: 1. a bottom, turned in a reference direction parallel to a reference axis of the recirculation part and intended to bear against a bottom of the cavity of the threaded element; 2. a recirculation path turned in a direction opposite to the reference direction, intended to pass through a thread of the threaded element along a recirculation path; 3. at least one first deflector, projecting from the recirculation path culation in the opposite direction to the reference direction, the first deflector forming a guide face, located at a distance from the recirculation path and facing in the reference direction; and 4. at least one first light which opens on one side onto the bottom and on the other side onto the recirculation path, opposite the guide face, the first light having an orthogonal projection onto a reference plane perpendicular to the reference axis, which surrounds or coincides with the orthogonal projection of the guide face of the first deflector onto the reference plane.

[0006] The first opening prevents overlap between the first deflector and the body of the one-piece part, delimited by the bottom, side walls, and recirculation path, as seen in projection onto the reference plane. This allows for axial molding of the guide face without undercuts along an axis parallel to the reference axis. The invention takes advantage of the fact that in the area where the deflector is needed to curve the recirculation path, the balls of the ball screw mechanism, which form a line of balls with very little relative play, are progressively lifted from the recirculation path to bear against the guide face of the deflector. It is therefore possible to incorporate the opening, which at least partially interrupts the recirculation path, without affecting the guidance of the balls along the recirculation path.Incidentally, the light helps to reduce the amount of material needed to construct the single-piece recirculation unit.

[0007] According to one embodiment, the monobloc recirculation piece includes a second deflector, projecting from the recirculation path in the direction opposite to the reference direction, the second deflector forming a guide face, located at a distance from the recirculation path and turned in the reference direction, the monobloc piece having at least a second light which opens onto the bottom and onto the recirculation path of the monobloc recirculation piece, opposite the guide face of the second deflector, the second light having an orthogonal projection onto the reference plane, which surrounds or coincides with the orthogonal projection of the guide face of the second deflector onto the reference plane.

[0008] According to one embodiment, the recirculation path describes an S-shaped trajectory with two ends, each intended to be continuous with a threaded end on one side of the thread traversed by the recirculation path. Preferably, the first deflector is located at a curved portion of the S-shaped trajectory, and the second deflector is located at a second curved portion of the S-shaped trajectory.

[0009] According to one embodiment, the bottom of the one-piece recirculation unit is plan. Preferably, the bottom of the monobloc recirculation unit is perpendicular to the reference axis. Alternatively, the bottom of the monobloc unit can be a warped surface, for example concave or convex, for example a cylindrical envelope surface.

[0010] The first light, and where applicable the second light, preferably have an envelope consisting of a ruled surface, preferably with a generatrix making a draft angle with the reference axis preferably greater than 2°, open towards the bottom of the one-piece part.

[0011] According to a preferred embodiment, the first opening, and optionally the second opening, are uncut in the reference direction, meaning that when any two sections of an opening are projected orthogonally onto the reference plane by section planes parallel to the reference plane, the projection of the section by the section plane closest to the bottom of the one-piece part surrounds, and optionally touches, the projection of the section by the section plane furthest from the bottom of the one-piece part. The one-piece part can then be manufactured by axial molding.

[0012] According to another aspect of the invention, this relates to a recirculating threaded element for a ball screw mechanism, the recirculating threaded element having a thread, the recirculating threaded element being equipped with one or more recirculators, each of the recirculators being housed in a housing cavity of the recirculating threaded element, the housing cavity passing through a thread of the thread, characterized in that each of the recirculators is a one-piece recirculating part according to any one of the preceding claims, the bottom of the one-piece recirculating part being supported against a bottom of the housing cavity, the recirculation path of the one-piece recirculating part connecting two portions of a groove of the thread on either side of the thread through which the housing cavity passes.Preferably, the recirculating threaded element is equipped with a number N greater than or equal to two, and preferably equal to three, of recirculators, angularly offset from each other by an angle around a helix axis of the thread.

[0013] According to one embodiment, the recirculating threaded element can be a ball screw mechanism screw or a ball screw mechanism nut.

[0014] According to another aspect of the invention, it relates to a ball screw mechanism comprising two threaded elements, namely a screw and a nut, and balls, one of the two threaded elements being a recirculating threaded element as described above, the ball screw mechanism further comprising balls forming one or more rows of balls, each associated with one of the monobloc recirculating elements, and each arranged along a loop path passing through the recirculation path. The culation of the associated one-piece recirculation unit and by the two portions of the threaded groove on either side of the thread through which the housing cavity passes. BRIEF DESCRIPTION OF THE FIGURES

[0015] Other features and advantages of the invention will become apparent from the following description, with reference to the attached figures.

[0016] [Fig.1] Fig.1 illustrates a ball screw mechanism according to an embodiment of the invention.

[0017] [Fig.2] Fig.2 illustrates a threaded recirculation element, in this case a screw, of the ball screw mechanism of [Fig.1], equipped with one-piece recirculation parts according to an embodiment of the invention.

[0018] [Fig.3] Fig.3 illustrates in section along a cutting plane 111-111, a detail of the insertion of one of the monobloc recirculation parts into the threaded component of the [Fig.2]

[0019] [Fig.4] The [Fig.4] illustrates the one-piece part of the [Fig.2].

[0020] [Fig. 5] [Fig. 5] illustrates an orthogonal projection of a detail of the part monobloc of the [Fig.2] on a reference plane.

[0021] For clarity, identical or similar elements are identified by identical reference signs throughout the figures. DETAILED description of implementation methods

[0022] Figure 1 illustrates a ball screw mechanism 10 comprising two threaded members, namely a screw 12 and a nut 14, and balls 16, arranged between a thread 18 of the screw 12 and a thread 20 of the nut 14, to guide the relative helical movement between the screw 12 and the nut 14. Each thread 18, 20 is defined by a helical groove whose flanks form a helical thread.

[0023] One of the two threaded members, in this embodiment the screw 12, will be referred to hereafter as a recirculating threaded member because it is equipped with recirculators 22, as illustrated in Figures 2 and 3. Each of the recirculators 22 is housed in an associated housing cavity 24, formed in the recirculating threaded member 12, and which passes through a thread 26 of the thread 18 of the recirculating threaded member 12. To open onto two portions 28, 30 of the thread groove on either side of the thread 26.

[0024] In this embodiment, there are four recirculators 22, and each defines, with the portions 28, 30 of the thread groove on either side of the thread 26, a loop trajectory over one revolution for a string of balls 16. The four recirculators 22 are arranged at a distance from each other along the axis 100 of the recirculating threaded element 12, axially separated by a distance greater than one helix pitch P of the thread of the recirculating threaded element, and angularly offset by 90° from each other. It will be understood, however, that in other embodiments In this arrangement, the number N of recirculators can be arbitrary. For a balanced and compact arrangement, an angular offset of and an axial distance of .#±1.p between two adjacent recirculators 22 can be chosen.

[0025] Remarkably, each recirculator 22 is in the form of a single-piece component manufactured by casting in an axial mold. The single-piece component 22, illustrated in [Fig. 4], comprises a bottom 32, rotated in a reference direction 200 parallel to a reference axis 300 of the single-piece component 22, an upper face opposite the bottom 32 and on which a recirculation path 34 is formed, and side walls 36 joining the bottom to the upper face. The recirculation path 34 is a groove whose profile may be, for example, an arc or an ogive, which defines a recirculation trajectory between two ends 38 of the groove.When the monobloc recirculation part 22 is housed in the associated housing cavity 24 of the recirculating threaded member 12, the bottom 32 of the monobloc recirculation part 22 rests against a bottom 40 of the housing cavity 24, the side walls 36 of the monobloc recirculation part 22 rest against side walls 42 of the housing cavity 24, and the ends 38 of the recirculation path 34 are arranged in alignment with the portions 28, 30 of the thread groove on either side of the thread 26 of the recirculating threaded member 12.

[0026] The recirculation path 34 is preferably S-shaped with a middle portion 44 connected to the ends 38 by two curved portions 46 ensuring two changes of direction.

[0027] The monobloc recirculation piece 22 further comprises two deflectors 48, each positioned at one of the two curved portions 46, projecting from the recirculation path 34 in the direction opposite to the reference direction 200, and each forming a guide face 50, turned in the reference direction 200, at a distance from the recirculation path 34 in the direction opposite to the reference direction 200.

[0028] Remarkably, the one-piece part 22 has two openings 52, each associated with one of the two deflectors 48. The two openings 52 extend parallel to the same reference axis 300 of the one-piece part and open at one end onto the bottom 32 and at the opposite end onto the recirculation path 34, opposite the associated deflector 48. The two openings 52 have a draft angle open towards the bottom 32, sufficient to allow their axial demolding, for example greater than 2°.

[0029] In orthogonal projection onto a reference plane 400 perpendicular to the reference axis 300, and as illustrated in [Fig. 5], each light 52 has an inner perimeter 54 which surrounds or coincides with the orthogonal projection 56 of the guide face 50 of the associated deflector 48. In practice, this makes it possible to create the face of guide 50, and in this case the whole of the monobloc recirculation part 22, by injection molding in a two-shell mold not requiring drawers to make the deflectors 48. Indeed, it is possible to make, in one of the shells forming the cavity of the mold, reliefs which constitute, in the finished molded part, the bottom 32, the lights 52 and the guide face 50, complementary reliefs being provided in the other shell, to delimit the opposite face of the deflectors 48, the ejection axis of the mold being parallel to the reference axis 300 of the part.

[0030] Along a looped path defined by two adjacent portions 28, 30 of the thread groove, on either side of a thread 26 of the recirculating threaded element 12, and by an associated recirculator 22, as well as by the thread 20 of the other threaded element 14 of the ball screw mechanism 10, the balls 16 form a continuous line, the clearance between two adjacent balls being less than the radius of the balls 16, and preferably less than 1 / 10th of the radius of the balls. When a ball 16 reaches one of the curved portions 46 where one of the openings 52 opens, the ball 16 is no longer in contact with the recirculation path 34, but is instead lifted by the neighboring balls to come into contact with the guide face 50 of the deflector 48. The presence of the openings 52 therefore does not impair the guidance of the balls 16.Furthermore, the opening 52 is preferably sized so that the balls 16 cannot enter it, in order to manage an extreme operating case, in which a ball 16 would come into contact with the opening 52. Since the balls 16 have very little charge in the recirculation circuit, the operation will not be impacted.

[0031] Naturally, the example shown in the figures and discussed above is given for illustrative purposes only. The principle of inserting one or more openings into the one-piece recirculation unit is also applicable to recirculators positioned on a ball screw mechanism nut. It is also applicable to a recirculator 22 with a single deflector 48.

Claims

Demands

1. A one-piece recirculation component (22) intended to be housed in a cavity (24) of a threaded element (12, 14) of a ball screw mechanism (10), the one-piece recirculation component (22) having: - a bottom (32), turned in a reference direction (200) parallel to a reference axis (300) of the recirculation part (22) and intended to come to rest against a bottom (40) of the cavity (24) of the threaded element (12, 14); - a recirculation path (34) facing in a direction opposite to the reference direction (200), intended to pass through a thread (26) of the threaded element (12, 14) along a recirculation path; and - at least one first deflector (48), projecting from the recirculation path (34) in the opposite direction to the reference direction (200), the first deflector (48) forming a guide face (50), located at a distance from the recirculation path (34) and turned in the reference direction (200); characterized in that the one-piece part (22) has at least one first light (52) which opens on one side onto the bottom (32) and on the other side onto the recirculation path (34), opposite the guide face (50), the first light (52) having an orthogonal projection (54) onto a reference plane (400) perpendicular to the reference axis (300), which surrounds or coincides with the orthogonal projection (56) of the guide face (50) of the first deflector (48) onto the reference plane (400).

2. A one-piece recirculation component (22) according to claim 1, characterized in that it comprises a second deflector (48), projecting from the recirculation path (34) in the direction opposite to the reference direction (200), the second deflector (48) forming a guide face (50), located at a distance from the recirculation path (34) and facing in the reference direction (200), the one-piece component comprising at least a second opening (52) which opens onto the bottom (32) and onto the recirculation path (34) of the one-piece recirculation component (22), opposite the guide face (50) of the second deflector (48). deflector (48), the second light (52) having an orthogonal projection (54) on the reference plane (400), which surrounds or coincides with the orthogonal projection (56) of the guide face (50) of the second deflector (48) on the reference plane (400).

3. One-piece recirculation part (22) according to any one of the preceding claims, characterized in that the recirculation path (34) describes an S-shaped trajectory with two ends (38), each intended to be in continuity with a threaded root (28, 30) on one side of the thread (26) through which the recirculation path (34) passes.

4. Monobloc recirculation piece (22) according to claim 3 in combination with claim 2, characterized in that the first deflector (48) is located at a curved portion (46) of the S-shaped trajectory, and the second deflector (48) is located at a second curved portion (46) of the S-shaped trajectory.

5. One-piece recirculation part (22) according to any one of the preceding claims, characterized in that the bottom (32) of the one-piece recirculation part (22) is flat.

6. Monobloc recirculation piece (22) according to claim 5, characterized in that the bottom (32) of the monobloc recirculation piece (22) is perpendicular to the reference axis (300).

7. One-piece recirculation piece (22) according to any one of the preceding claims, characterized in that the first light (52), and where applicable the second light (52), open without undercut in the reference direction (200).

8. A recirculating threaded element (12) for a ball screw mechanism (10), the recirculating threaded element (12) having a thread (18), the recirculating threaded element (12) being equipped with one or more recirculators (22), each of the recirculators (22) being housed in a housing cavity (24) of the recirculating threaded element (12), the housing cavity (24) passing through a thread (26) of the thread (18), characterized in that each of the recirculators (22) is a single-piece recirculating element according to any one of the preceding claims, the bottom (32) of the single-piece recirculating element (22) bearing against a bottom (40) of the housing cavity (24), the recirculation path (34) of the single-piece recirculating element (22) connecting two portions (28, 30) of a groove of the thread on either side of the thread (26) through which the housing cavity (24) passes.

9. Recirculating threaded element (12) according to claim 8, characterized in that it is equipped with a number N greater than or equal to two, and preferably equal to three, of recirculators (22), angularly offset from each other by an angle around a helix axis (100) of the thread N (18).

10. Recirculating threaded element (12) according to any one of claims 8 to 9, characterized in that the recirculating threaded element (12) is a ball screw mechanism screw.

11. Recirculating threaded element according to any one of claims 8 to 10, characterized in that the recirculating threaded element is a nut (14) of a ball screw mechanism (10).

12. Ball screw mechanism (10) comprising two threaded members, namely a screw (12) and a nut (14), and balls (16), one of the two threaded members being a recirculating threaded member (12) according to any one of claims 8 to 11, the ball screw mechanism (10) further comprising balls (16) forming one or more ball strings, each associated with one of the monobloc recirculating pieces (22), and each arranged along a loop path passing through the recirculation path (34) of the associated monobloc recirculating piece (22) and through the two portions (28, 30) of the thread groove on either side of the thread (26) through which the housing cavity (24) passes.

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