(19)
(11)EP 0 849 477 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
09.04.2003 Bulletin 2003/15

(21)Application number: 97122905.9

(22)Date of filing:  24.12.1997
(51)International Patent Classification (IPC)7F16B 21/10, F16D 1/06, F16B 21/18, F16F 1/32

(54)

A device for locking and unlocking two mechanical members by means of a bistable elastic element

Vorrichtung zum Ver- und Entriegeln von zwei mechanischen Elementen durch ein elastisches Element mit zwei stabilen Positionen

Dispositif de verrouillage et de déverouillage de deux membres mécaniques par un élément élastique bistable


(84)Designated Contracting States:
DE FR GB IT SE

(30)Priority: 20.12.1996 IT TO961056

(43)Date of publication of application:
24.06.1998 Bulletin 1998/26

(73)Proprietor: SKF INDUSTRIE S.p.A.
10123 Torino (IT)

(72)Inventor:
  • Iarrera, Fabrizio
    10141 Torino (IT)

(74)Representative: Lotti, Giorgio et al
c/o Ing. Barzanò & Zanardo Milano S.p.A. Corso Vittorio Emanuele II, 61
10128 Torino
10128 Torino (IT)


(56)References cited: : 
EP-A- 0 272 967
FR-A- 1 090 293
GB-A- 2 210 662
DE-A- 4 240 131
FR-A- 2 618 504
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description


    [0001] The present invention relates to a device for locking and unlocking two mechanical members coupled for rotation as a unit, the device making use of a bistable elastic disc. More particularly, the invention refers to a device for locking and unlocking a constant-velocity joint to and from the hub of a driving wheel of a vehicle, in particular an automobile. The bistable elastic disc can deform elastically to shift alternately, under the action of a predetermined load, from and to first and second positions in which it takes different spatial arrangements.

    [0002] In a previous pending patent application, to the same Applicant, there is disclosed a hub-joint unit for a motor vehicle driving wheel, wherein the joint is coupled to the hub by means of a splined coupling with axially oriented toothing. The joint is axially locked to the hub by means of an expansion ring fitted in a circular seat formed in part on the joint and in part on the hub.

    [0003] In such a unit, in order to mount and dismount the joint to and from the hub, particularly when servicing the vehicle, provided near the seat for the elastic ring are radial through apertures for inserting a tool to compress the locking ring radially and disengage it from the joint. However, this solution has the disadvantage of requiring the use of bulky tools that have to act on diametrically opposite positions of the elastic ring. Furthermore, the radial apertures put the inner parts of the joint in communication with the outside through the clearances of the splined coupling. As a result, dirt and moisture can penetrate in the joint.

    [0004] Accordingly, an object of the present invention is to provide an improved locking/unlocking device capable of overcoming the disadvantages and limitations of the prior art. More particularly, it is a significant object of the present invention to provide a compact locking and unlocking device adapted to fit within the coupled members and operable from the outside, without jeopardising the sealing of the coupling.

    [0005] In accordance with the present invention, there is provided a device for locking and unlocking two mechanical members coupled for rotation as a unit by means of a splined coupling, said device comprising elastic means secured to a first member of said two mechanical members and adapted for co-operation with a second member of said two mechanical members, characterised in that said elastic means comprise a bistable elastic disc having first and second alternative steady positions, said bistable elastic disc being provided with hooking means projecting from the disc and adapted for co-operating in said first position with said second mechanical member to keep said members axially coupled, and for disengaging in said second position from said second member to allow separation of the mechanical members forming said coupled unit.

    [0006] These and other objects, advantages and features of the present invention will become readily apparent to those skilled in the art from a study of the following description of an exemplary preferred embodiment when read in conjunction with the attached drawings, in which:
    FIG. 1
    is a longitudinal cross sectional view of a coupling between a constant-velocity joint and a driving wheel hub of a motor vehicle fitted with a locking/unlocking device in accordance with the present invention;
    FIGS. 2a, 2b and 2c
    depict alternative embodiments, respectively, of the bistable elastic element of the device of FIG. 1;
    FIGS. 3a and 3b
    are partial cross sectional views showing two positions of an actuator device acting on the elastic element of FIG. 2;
    FIG. 4
    illustrates, to an enlarged scale, a functional detail of the elastic element of FIG. 1; and
    FIG. 5
    shows two embodiments of an inner member for actuating the device of FIG. 1.


    [0007] Referring now to FIG. 1, numeral 1 designates a coupling unit for coupling a first mechanical member 2 and a second mechanical member 3 together, in particular a constant-velocity joint 2, hereinafter referred to simply as joint, of conventional design and not described in further detail herein, and a corresponding hub 3 of a driving wheel, particularly for a motor vehicle. The joint 2 and the hub 3 are fast for rotation by means of a conventional splined coupling. Hub 3 rotates on a bearing 5 with a dual set of bearing balls 7 and 8, engaging corresponding outer raceways 9 and inner raceways 10 respectively formed in a stationary, radially outer ring 12 of the bearing 5. The outer ring 12 forms a radial flange 14 for connecting the hub-joint unit 1 to a vehicle suspension standard 15.

    [0008] Hub 3 forms by a cylindrical axle portion 16, providing an inner axial bore 17, open on opposite sides and defining, in the present non-limiting example, the inner ring of bearing 5 having two inner raceways 18 and 19, corresponding to outer raceways 9 and 10, respectively. Inner raceways 18 and 19 are formed one directly on hub 3 and the other on an intermediate ring 20, of known kind, forcefully fitted on hub 3. As an alternative, as shown in phantom line in FIG. 1, raceways 18 and 19 could be formed in respective rings 20', 20, both fitted on the hub 3.

    [0009] Hub 3 bears at one end 21 a radial flange 22 for mounting the driving wheel and terminates at an opposite end 23 with an annular rim 24.

    [0010] Axle portion rim 24 projects axially beyond a corresponding end portion 23a of stationary ring 12 of limited thickness, adapt to be cold formed by rolling, as better explained in the following.

    [0011] Intermediate ring 20 is forcefully fitted with accuracy with a slight interference onto a cylindrical centring seat 26 formed in the hub 3. Intermediate ring 20 extends axially in the direction of joint 2 with an annular portion 27. According to the not-limiting example shown in the drawing, on the outer and inner surfaces of annular portion 27 there are formed two axial toothings 29 and 30, respectively, for providing respective splined couplings for mechanically securing for rotation the joint 2 on one side with the hub 3 on the other side.

    [0012] More particularly, the inner toothing 30 is adapt to engage a corresponding toothing 32 of hub 3, whilst the outer toothing 29 engages toothing 33 formed within an axially protruding annular portion 34 of socket 35 of joint 2.

    [0013] After mounting the ring 20 in seat 26 of hub 3, the hub rim 24 is radially folded and headed tightly by cold forming, particularly by rolling, against the annular portion 28 of ring 20. In this manner, the ring 20 is rigidly and securely locked onto the hub 3.

    [0014] In order to mount and/or dismount the joint 2 onto/from hub 3 in a simple and quick manner, there is provided, in accordance with the invention, an axial locking/unlocking device fitted within the socket 35 of joint 2 and operable from the outside.

    [0015] The locking/unlocking device according to the invention comprises a bistable elastic disc 36, in the illustrated example consisting of an elastic, metallic diaphragm 36, preferably made out of spring steel and of annular disc-shape, slightly cup-shaped. Disc 36 is secured by means of a peripheral edge 38 thereof to one of the mechanical members to connect, e.g. a constant-velocity joint 2. Further, disc 36 provides an inner peripheral edge 40 defining a circular opening 41 facing the inner bore 17 of hub 3.

    [0016] When disc 36 is urged by an axial force alternately acting in one direction or in the opposite direction on the inner edge 40, disc 36 deforms elastically to alternately take two stable positions with oppositely directed concavities, of which one is shown in the drawings in full line and the other in dotted line.

    [0017] The outer edge 38 is accommodated in a circumferential seat within socket 35 with a certain radial play allowing slight adjustment of disc 36 when passing from one stable position to the other. Disc 36 is axially locked in seat 39 by a shoulder 43 on one side, and by an elastic expansion ring 44 housed in a circular groove 45 formed in the socket 35 opposite to the seat of disc 36.

    [0018] Disc 36 is fitted with hooking means 46 axially protruding from the disc surface towards the element to be connected, in this example the hub 3. The hooking means 46 are adapted to co-operate with a circular rim or relief 47 formed at the annular end portion 27 of ring 20.

    [0019] More particularly, the hooking means 46 consist of a number of hooks 48 half-blanked in radial apertures 49 of disc 36 (FIG. 2a). Hooks 48 are angularly equally spaced along a circle concentric to edges 38 and 40, in correspondence of the rim 47 of ring 20. Hooks 48 are formed so as to engage rim 47 when disc 36 is disposed in a first steady position 50 (illustrated in full line). In this manner, the hooks axially secure the hub 3 to the socket 35 of joint 2 to which disc 36 is fixed.

    [0020] When disc 36 is deformed by an axial force applied to the disc inner edge 40, it shifts to its second steady position 52 (illustrated in phantom line). In this shifting step, the hooks 48 rotate anti-clockwise (FIG. 4) about a virtual fulcrum coincident with the outer edge 38 and disengage from rim 47. Therefore, in this second position 52 of disc 36, the joint 2 ca be separated from the hub 3 by axially sliding along the toothing 30.

    [0021] To apply an axial actuating force to disc 36, a thin, elongated tool 54 (FIGS. 3a, 3b) is inserted through the axle portion bore 17. Tool 54 is composed of a cylindrical stem 55 ending with a portion 56 having a conical surface 57, around which there are disposed several blocks 58 in form of circular sectors. Blocks 58 are held by an elastic ring 59, for example a helical spring or a rubber O-ring. Blocks 58 are axially slidable along the conical surface 57 until they reach an end position 64 at the maximum diameter of conical portion 56. In this location, the blocks 58 are stopped by a stopping edge 56' axially limiting the conical surface 57 on the side opposite to stem 55. In the resting condition, owing to the action of elastic ring 59, the blocks 58 are disposed at the minimum diameter of conical portion 56, near stem 55. Blocks 58 are so sized in the radial dimension as to be inserted through the aperture 41 of disc 36.

    [0022] Fitted on stem 55 is an axially sliding sleeve 60 terminating at the end facing the blocks 58 with a circular seat 62. Seat 62 is delimited by a shoulder 63 and adapted for accommodating the inner edge 40 of disc 36.

    [0023] To unlock the joint 2 from the hub 3, operations are as follows. Tool 54 is inserted through the bore 17 of axle portion 16, until the blocks 58 pass over the inner edge 40 of disc 36 in the locking arrangement (to the left in FIG. 3a) and the inner edge 40 abuts against the shoulder 63. Then, the sleeve 60 is biased against the inner edge 40 to axially displace the disc 36 and make this overcome an intermediate, unsteady position, after which the disc 36 elastically snaps to the second steady position 52.

    [0024] In this arrangement, the hooks 48 disengage from hub 3, allowing to dismount the joint 2 from the hub.

    [0025] In the reverse operation, to lock the joint 2 to the hub 3 after the joint has been fitted over the axial toothing 30, the tool 54 is once again inserted through the aperture 41 of disc 36, or, vice versa, through the bore 17 of hub 3, passing beyond the inner edge 40 with blocks 58. Then, the sleeve 60 is pushed axially relative to the stem 55 to bring the blocks 58 to the maximum diameter of the conical portion 56 in contact with the axial stopping edge 56'. Finally, the stem 55 is pulled in the opposite direction, pushing the blocks 58 against the inner edge 40 of disc 36 and forcing disc 36 to move back to the first steady position 50, wherein the hooks 48 engage rim 47.

    [0026] FIGS. 2a to 2c illustrate in further detail three possible embodiments, respectively, of the elastic disc 36. In FIG. 2a, the hooks 48 are formed by folding outwardly from disc 36 a plurality of metal strips obtained by half-blanking radial slits 49 open towards the central opening 41 of disc 36. In FIG. 2b, the hooks 48 are formed in apertures 72 disposed in a circle proximate to the outer edge 38 of disc 36 near the radial slits 49. The outer edge 38 is not continuous, but formed by extensions 38a distributed at an angle near the apertures 72. Said extensions can be used for locking the disc 36, as an alternative to or in combination with the above described locking system (consisting of the shoulder 43 and the elastic expansion ring 44). The extensions snap-fit into respective seats formed within the joint socket portion 35. In FIG. 2c, the hooks 48 are formed in the zone 73 defined by two legs 74 of a Y-shaped slit. As apparent, due to the construction of slits 49, the inner edge 40 of disc 36 is discontinuous and the same slits define intermediate radial legs 75 which are helpful in facilitating the radial flexion of the disc as this passes from one steady position to the other.

    [0027] As an alternative to the use of a complex tool as described herein above, in accordance with another aspect of the present invention there is used a member 80 for actuating the disc 36 (FIG. 5). Actuating member 80 is mounted within the hub 3 and is operable from the outside. Actuating member 80 is composed of a pin 81 axially slidable within a central bore 82 of axle portion 16. Pin 81 extends axially towards joint 2 with an end portion 84 provided with a peripheral groove 85 for permanently accommodating the inner edge 40 of disc 36. The opposite end of pin 81 provides a dovetail tang 86 adapted to be grasped by a special actuator tool, not illustrated, inserted through the bore 17 of axle portion 16. Interposed between the pin 81 and the bore 82 is a sealing ring 87 for hermetically sealing the inner ambient of the joint 2. By moving the pin 81 in either direction, the disc 36 is shifted from one steady position to the other, thereby allowing to unlock or lock the joint 2 from or to the hub 3.

    [0028] In the bottom part of FIG. 5 there is shown an alternative construction of pin 81 wherein the tang 86 is replaced by a threaded bore 88 in which the actuator tool can be screwed.


    Claims

    1. A device for locking and unlocking two mechanical members (2, 3) coupled for rotation as a unit (1) by means of a splined coupling (30, 33), said device comprising elastic means (36) secured to a first member (2) of said two members (2, 3) and adapted for co-operation with a second member (3) of said two members (2, 3), characterised in that said elastic means (36) comprise a bistable elastic disc (36) having first (50) and second (52) alternative steady positions, said bistable elastic disc being provided with hooking means (46, 48) projecting from the disc (36) and adapted for co-operating in said first position (50) with said second member (3) to keep said members axially coupled, and for disengaging in said second position (52) from said second member (3) to allow separation of members (2, 3) forming said coupled unit (1).
     
    2. A device according claim 1, characterised in that said bistable elastic disc (36) consists of a metallic diaphragm, preferably made of spring steel, of substantially cup-like circular disc shape (36) adapt to elastically deform for alternatively reaching two steady positions (50, 52) in which its concavity faces opposite directions upon being subjected to axial forces of alternative, opposite directions.
     
    3. A device according claim 1 or 2, characterised in that said hooking means (46) consist of a number of hooks (48) axially folded and projecting from a surface of said disc (36), said hooks being angularly equally spaced on a circumference concentric and adjacent to an outer edge (38) of said disc (36), said hooks being so shaped as to engage a circular rim (47) disposed within an end (24) of said second mechanical member (3) when said disc is in said first steady position (50).
     
    4. A device according to any of the preceding claims, characterised in that said disc (36) has a peripheral outer edge (38), said disc being secured to said first member (2) by fitting said outer edge (38) in a circular seat (39) formed adjacent and close to said splined coupling (4) for connection to said second member (3).
     
    5. A device according to claim 4, characterised in that said outer edge (38) is axially locked in said seat (39) by means of a seat shoulder (43) and an elastic expansion ring (44) mounted in a seat formed opposite to the shoulder (43) relative to the edge of the disc (36).
     
    6. A device according to claim 4, characterised in that said outer edge (38) is discontinuous and formed by angularly equally spaced radial extensions (38a), said edge being axially locked in said seat (39) by snapping action of said radial extensions (38a).
     
    7. A device according to claim 5 or 6, characterised in that said disc (36) has an inner edge (40) defining a central aperture (41) facing an inner bore (17) of said second mechanical member (3), said disc (36) having angularly equally spaced elongated radial slits (49) communicating with said central aperture (41) on one side and adjacent to said hooks (48) at the opposite side.
     
    8. A device according to claim 7, characterised in that said disc (36) is adapted for being moved from one steady position to the other of said steady positions (50, 52) by means of an actuator tool (54) operable from the outside through said bore (17) to apply to said disc (36) an axial force alternately in either opposite direction.
     
    9. A device according to claim 8, characterised in that said tool (54) comprises a cylindrical stem (55) terminating with a conical portion (56) carrying a number of retractable blocks (58), said blocks being radially extendible by means of a sleeve (60) sliding on said stem, said sleeve having a circular shoulder (63) for engaging the inner edge (40) of said disc to apply a force in one direction, said blocks being adapted to push against said inner edge (40) to apply to said disc an axial force in the opposite direction.
     
    10. A device according to any of claims 5 to 7, characterised by further comprising a member (80) for actuating said disc (36), said actuator member (80) being comprised of a pin (81) axially sliding in a central bore (82) of said second mechanical member (3), said pin (81) being provided, at one end thereof, with a peripheral groove (85) adapted to accommodate said inner edge (40) of the disc (36); at the other end, said pin having a coupling member (86) for receiving a tool operable from the outside to move said disc (36) from and to said first and second steady positions.
     
    11. A device according to claim 10, characterised in that said coupling member is comprised of a dovetail tang (86).
     
    12. A device according to claim 10, characterised in that said coupling member is comprised of a threaded bore (88).
     
    13. A device according to any of the preceding claims, characterised in that said first and second mechanical members consist of a constant-velocity joint (2) and a hub (3), respectively, for a vehicle wheel, in particular an automobile wheel.
     


    Ansprüche

    1. Vorrichtung zum Ver- und Entriegeln von zwei mechanischen Elementen (2, 3), die mittels einer Schiebekupplung (30, 33) zur Drehung als Einheit (1) gekoppelt sind, wobei die Vorrichtung eine elastische Einrichtung (36) umfasst, die an einem ersten Element (2) der zwei Elemente (2, 3) befestigt und zum Zusammenwirken mit einem zweiten Element (3) der zwei Elemente (2, 3) angepasst ist, dadurch gekennzeichnet, dass die elastische Einrichtung (36) einen bistabilen, elastischen Teller (36) mit alternativen ersten (50) und zweiten (52) Dauerstellungen umfasst, wobei der bistabile, elastische Teller mit von dem Teller (36) vorstehenden Einhakmitteln (46, 48) versehen ist, die dazu angepasst sind, in der ersten Stellung (50) mit dem zweiten Element (3) zusammenzuwirken, um die Elemente axial miteinander gekoppelt zu halten, und die zum Ausrücken von dem zweiten Element (3) in die zweite Stellung (52) angepasst sind, um eine Trennung der die gekoppelte Einheit (1) bildenden Elemente (2, 3) zuzulassen.
     
    2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass der bistabile, elastische Teller (36) aus einer metallischen Lochscheibe, vorzugsweise aus Federstahl besteht, die im Wesentlichen die Form eines tassenförmigen Kreisrings (36) hat, der dazu angepasst ist, sich elastisch zu verformen, um alternative zwei Dauerstellungen (50, 52) einzunehmen, in denen ihre Konkavitäten in entgegengesetzte Richtungen zeigen, nachdem sie Axialkräften in einander entgegengesetzten Alternativrichtungen unterworfen wurden.
     
    3. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Einhakmittel (46) aus einer Anzahl von Haken (48) bestehen, die in Achsrichtung umlegt sind und von einer Fläche des Tellers (36) vorstehen, wobei die Haken auf einem konzentrisch zu und neben einer Außenkante (38) des Tellers (36) liegenden Umfang winklig gleichmäßig beabstandet angeordnet sind, wobei die Haken so geformt sind, dass sie einen Kreisrand (47), der an einem Ende (24) des zweiten mechanischen Elementes (3) angeordnet ist, ergreifen, wenn sich der Teller in der ersten Dauerstellung (50) befindet.
     
    4. Vorrichtung nach einem der voranstehenden Ansprüche, dadurch gekennzeichnet, dass der Teller (36) eine Außenumfangskante (38) besitzt, wobei der Teller an dem ersten Element (2) durch Einsetzen der Außenkante (38) in einen Ringsitz (39) befestigt ist, der neben und nahe der Schiebekupplung (4) zum Anschließen an das zweite Element (3) ausgebildet ist.
     
    5. Vorrichtung nach Anspruch 4, dadurch gekennzeichnet, dass die Außenkante (38) in dem Sitz (39) mittels einer Sitzschulter (43) und einem elastischen Spreizring (44) axial verriegelt ist, wobei der elastische Spreizring (44) in einem Sitz befestigt ist, der relativ zur Kante des Tellers (36) gegenüber der Schulter (43) ausgebildet ist.
     
    6. Vorrichtung nach Anspruch 4, dadurch gekennzeichnet, dass die Außenkante (38) unregelmäßig ist und von im Kreis gleichmäßig beabstandeten radialen Verlängerungen (38a) geformt ist, wobei die Kante in dem Sitz (39) durch Einschnappen der radialen Verlängerungen (38a) axial verriegelt ist.
     
    7. Vorrichtung nach Anspruch 5 oder 6, dadurch gekennzeichnet, dass der Teller (36) eine Innenkante (40) besitzt, die eine Mittelöffnung (41) definiert, die einer Innenbohrung (17) des zweiten mechanischen Elementes (3) zugewandt ist, wobei der Teller (36) auf einem Kreis gleichmäßig beabstandete, längliche radiale Schlitze (49) besitzt, die mit der Mittelöffnung (41) auf einer Seite in Verbindung stehen und benachbart zu den Haken (48) an der gegenüberliegenden Seite liegen.
     
    8. Vorrichtung nach Anspruch 7, dadurch gekennzeichnet, dass der Teller (36) dazu angepasst ist, von einer Dauerstellung zur anderen Dauerstellungen (50, 52) durch ein Betätigungsteil (54) bewegt werden, das von Außen durch die Bohrung (17) hindurch betätigbar ist, um auf den Teller (36) abwechselnd in jeder Gegenrichtung eine Axialkraft aufzubringen.
     
    9. Vorrichtung nach Anspruch 8, dadurch gekennzeichnet, dass das Betätigungsteil (54) einen zylindrischen Schaft (55) umfasst, der in einen konischen Abschnitt (56) endet, der eine Anzahl von ausfahrbaren Klötzen (58) trägt, wobei die Klötze durch eine auf dem Schaft gleitende Hülse (60) radial ausziehbar sind, wobei die Hülse eine kreisförmige Schulter (63) zum Ergreifen der Innenkante (40) des Tellers besitzt, um in einer Richtung eine Kraft aufzubringen, wobei die Klötze dazu angepasst sind, gegen die Innenkante (40) zu drücken, um eine Axialkraft in der gegenüberliegenden Richtung aufzubringen.
     
    10. Vorrichtung nach einem der Ansprüche 5 bis 7, ferner dadurch gekennzeichnet, dass sie ein Element (80) zum Betätigen des Tellers (36) umfasst, wobei das Betätigungselement (80) einen in einer Mittelbohrung (82) des zweiten mechanischen Elementes (3) axial gleitenden Stift (81) umfasst, wobei der Stift (81) an einem Ende mit einer Umfangsnut (85) versehen ist, die zur Aufnahme der Innenkante (40) des Tellers (36) angepasst ist, und an dem anderen Ende der Stift ein Kupplungselement (86) zur Aufnahme eines von Außen betätigbaren Teils hat, um den Teller (36) in die ersten und zweiten Dauerstellungen zu bewegen.
     
    11. Vorrichtung nach Anspruch 10, dadurch gekennzeichnet, dass das Kupplungselement einen schwalbenschwanzförmigen Mitnehmer umfasst.
     
    12. Vorrichtung nach Anspruch 10, dadurch gekennzeichnet, dass das Kupplungselement aus einer Gewindebohrung (88) besteht.
     
    13. Vorrichtung nach einem der voranstehenden Ansprüche, dadurch gekennzeichnet, dass das erste und zweite mechanische Element aus einem Doppelgelenk (2) und einer Nabe (3) für ein Fahrzeugrad, insbesondere ein Kraftfahrzeugrad besteht.
     


    Revendications

    1. Dispositif pour verrouiller et déverrouiller deux éléments mécaniques (2, 3) couplés pour tourner en tant qu'unité (1) au moyen d'un accouplement à cannelures (30, 33), ledit dispositif comprenant des moyens élastiques (36) fixés à un premier élément (2) parmi lesdits deux éléments (2, 3) et adaptés pour coopérer avec un second élément (3) parmi lesdits deux éléments (2, 3), caractérisé en ce que lesdits moyens élastiques (36) comprennent un disque élastique bistable (36) ayant une première (50) et une seconde (52) position régulière alternatives, ledit disque élastique bistable étant muni de moyens de crochetage (46, 48) faisant saillie depuis le disque (36) et adaptés pour coopérer dans ladite première position (50) avec ledit second élément (3) pour maintenir lesdits éléments axialement couplés, et pour se désolidariser dans ladite seconde position (52) dudit second élément (3) pour permettre la séparation des éléments (2, 3) formant ladite unité d'accouplement (1).
     
    2. Dispositif selon la revendication 1, caractérisé en ce que ledit disque élastique bistable (36) est constitué d'un diaphragme métallique, de préférence fabriqué à partir d'acier à ressort, ayant sensiblement la forme d'un disque circulaire semblable à un gobelet (36) adapté pour se déformer de manière élastique afin d'atteindre de manière alternative deux positions régulières (50, 52) dans lesquelles sa concavité fait face à des directions opposées après avoir été soumise à des forces axiales de directions opposées alternatives.
     
    3. Dispositif selon la revendication 1 ou la revendication 2, caractérisé en ce que les moyens de crochetage (46) sont constitués d'un certain nombre de crochets (48) pliés axialement et faisant saillie depuis une surface dudit disque (36), lesdits crochets étant espacés de façon égale angulairement sur une circonférence concentrique et adjacente à une arête extérieure (38) dudit disque (36), lesdits crochets étant formés de manière à mettre en prise un rebord circulaire (47) disposé à l'intérieur d'une extrémité (24) dudit second élément mécanique (3) lorsque ledit disque se trouve dans ladite première position régulière (50).
     
    4. Dispositif selon l'une quelconque des revendications précédentes, caractérisé ce que ledit disque (36) présente une arête extérieure périphérique (38), ledit disque étant fixé audit premier élément (2) en ajustant ladite arête extérieure (38) dans un appui circulaire (39) formé de manière adjacente et à proximité dudit accouplement à cannelures (4) pour la connexion audit second élément (3).
     
    5. Dispositif selon la revendication 4, caractérisé en ce que ladite arête extérieure (38) est verrouillée axialement dans ledit appui (39) au moyen d'un épaulement d'appui (43) et d'un anneau d'expansion élastique (44) monté dans un appui formé à l'opposé de l'épaulement (43) par rapport à l'arête du disque (36).
     
    6. Dispositif selon la revendication 4, caractérisé en ce que ladite arête extérieure (38) est discontinue et formée par des extensions espacées également de manière angulaire (38a), ladite arête étant verrouillée axialement dans ledit appui (39) par encliquetage desdites extensions radiales (38a).
     
    7. Dispositif selon la revendication 5 ou 6, caractérisé en ce que ledit disque (36) présente une arête intérieure (40) définissant une ouverture centrale (41) faisant face à un alésage intérieur (17) dudit second élément mécanique (3), ledit disque (36) ayant des fentes radiales allongées espacées de manière égale angulairement (49) communiquant avec ladite ouverture centrale (41) sur un côté et adjacentes auxdits crochets (48) au niveau du côté opposé.
     
    8. Dispositif selon la revendication 7, caractérisé en ce que ledit disque (36) est adapté pour être déplacé depuis une position régulière vers l'autre desdites positions régulières (50,52) au moyen d'un outil d'actionnement (54) pouvant fonctionner depuis l'extérieur à travers ledit alésage (17) pour appliquer audit disque (36) une force axiale de manière alternée dans chaque direction opposée.
     
    9. Dispositif selon la revendication 8, caractérisé en ce que ledit outil (54) comprend une tige cylindrique (55) se terminant par une partie conique (56) supportant un certain nombre de blocs rétractables (58), lesdits blocs pouvant s'étendre radialement au moyen d'un manchon (60) coulissant sur ladite tige, ladite tige ayant un épaulement circulaire (63) pour mettre en prise l'arête intérieure (40) dudit disque afin d'appliquer une force dans une direction, lesdits blocs étant adaptés pour pousser contre ladite arête intérieure (40) dans le but d'appliquer audit disque une force axiale dans la direction opposée.
     
    10. Dispositif selon l'une quelconque des revendications 5 à 7, caractérisé par le fait qu'il comprend en outre un élément (80) pour actionner ledit disque (36), ledit élément d'actionnement (80) étant composé d'une broche (81) coulissant de manière axiale dans un alésage central (82) dudit second élément mécanique (3), ladite broche (81) étant munie, au niveau d'une extrémité de celle-ci, d'une rainure périphérique (85) adaptée pour recevoir ladite arête interne (40) du disque (36) ; au niveau de l'autre extrémité, ladite broche ayant un élément d'accouplement (86) pour recevoir un outil pouvant être mis en fonctionnement depuis l'extérieur pour déplacer ledit disque (36) depuis et en direction desdites première et seconde positions régulières.
     
    11. Dispositif selon la revendication 10, caractérisé en ce que ledit élément d'accouplement est composé d'un tenon en queue d'aronde (86).
     
    12. Dispositif selon la revendication 10, caractérisé en ce que ledit élément d'accouplement se compose d'un alésage fileté (88).
     
    13. Dispositif selon l'une quelconque des revéndications précédentes, caractérisé en ce que lesdits premier et second éléments mécaniques sont constitués d'un joint homocinétique (2) et d'un moyeu (3), respectivement, pour une roue de véhicule, en particulier une roue d'automobile.
     




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