EP0986688B1 - Improved articulation device for a hatchback mounted on a motor vehicle body - Google Patents

Description

The present invention relates to a device articulation of a motor vehicle opening, in particular a tailgate, which is pivotally mounted on the structure of the vehicle body.

The invention relates more particularly to a device articulation in which the opening is pivotally mounted, in particular between a first extreme closed position and a second extreme position opened via a mechanism with two parallel axes of articulation connected by minus a link rod.

Such a device is for example described and shown in document FR-A-2.717.213.

In this document, a pair of parallel connecting rods of which a first front end is articulated on the structure of the vehicle body around a first articulation axis, including the second rear end is articulated on the sash around a second axis of articulation, parallel to the first axis of articulation, and it is provided means to control the movement of pivoting of the sash, relative to the second end of the connecting rod, at the pivoting movement of the first end of the connecting rod relative to the structure of the body of the vehicle.

Such a design makes it possible in particular to ensure the articulation of a vehicle tailgate, the handling requires little effort to switch from the closed position to an open position and which can be manipulated without significant effort from the position closed until fully open.

In document FR-A-2.739.349, a implementation of such a hinge device more particularly to ensure the pivoting mounting of a tailgate which, in the closed position, extends in a plane substantially vertical and which, in the open position; extends in a plane substantially horizontal above the vehicle.

When the rear part of a vehicle is fitted with a such tailgate, as is the case in vehicles for example of the "minivan" type, the tailgate is of dimensions and significant mass.

This second document thus proposes, to facilitate the tailgate handling, to incorporate into the hinge device means of balancing the opening which apply a balancing torque which compensates for the resisting torque due to the opening mass.

However, it can be seen that the user, in order to be able to open or close the tailgate easily, must have a relatively large minimum space at the rear of the vehicle to allow at least the tailgate travel between its extreme closed position and its extreme position open, travel during which the panel which constitutes the tailgate moves, during the first part of the trajectory from the closed position, substantially parallel to itself and oriented substantially vertically.

We can see that the panel goes through a substantially middle position between its two extreme positions in which it extends at a distance from the rear vertical plane of the vehicle which is substantially equal to the length of the connecting rods, this distance determining a trajectory of the lower edge of the panel, in an arc of a circle the radius increases due to the design of the articulation and movement control device which uses a rack whose longitudinal ends front and rear gears cooperate with fixed gears respectively on the structure of the opening body and on the structure of the panel.

The object of the invention is to remedy this drawback by proposing an improved articulation device which allows you to open the tailgate even if the space available at the rear of the vehicle is very limited, especially when another vehicle is parked near the bumper back.

To this end, the invention provides a device of the type mentioned above, characterized in what the direction of pivoting of the sash, relative to the second end of the connecting rod, reverses during pivoting movement of the first end of the connecting rod, relative to the structure of the vehicle body, between two extreme angular positions associated with the positions closed and open ends of the sash.

• les moyens d'asservissement comportent un mécanisme d'asservissement comportant notamment une crémaillère qui est montée coulissante longitudinalement par rapport au corps de la bielle, dont une première extrémité dentée coopère en permanence avec un premier pignon lié en rotation à la structure de la caisse du véhicule, et dont la seconde extrémité est conformée en une fourche dont les deux branches dentées sensiblement parallèles s'étendent vers l'arrière et sont susceptibles de coopérer alternativement avec l'un ou l'autre, respectivement, de deux secteurs dentés diamétralement opposés d'un second pignon lié en rotation à l'ouvrant ;
• chacune des deux branches de la fourche est montée tournante par rapport au corps de la crémaillère, autour d'un axe avant de rotation parallèle aux axes d'articulation de la bielle, et est sollicitée élastiquement en rotation autour de son axe dans le sens correspondant à l'engagement de la branche avec le secteur denté correspondant du second pignon, et chaque branche comporte des moyens de commande de sa position angulaire pour provoquer son engagement, ou son désengagement, avec les dents du second pignon en fonction de la position longitudinale de la seconde extrémité de la crémaillère par rapport au corps de la bielle ;
• les moyens de commande comportent un doigt de commande porté par la branche et qui s'étend latéralement pour coopérer avec une rampe de commande d'orientation sensiblement longitudinale, formée en vis-à-vis sur le corps de la bielle, au voisinage de la seconde extrémité arrière de cette dernière ;
• chaque rampe comporte deux tronçons consécutifs, externe de désengagement et interne d'engagement séparés par une fente d'inversion permettant le passage du doigt de commande de l'un à l'autre des deux tronçons, qui sont décalés transversalement l'un par rapport à l'autre et par rapport à l'axe longitudinal de coulissement de la crémaillère ;
• l'ouvrant est un hayon qui, en position fermée, s'étend dans un plan sensiblement vertical et qui, en position ouverte, s'étend dans un plan sensiblement horizontal au-dessus du véhicule ;
• le hayon est formé par un panneau masquant un évidement d'un cadre de la structure délimité par une traverse supérieure, par deux montants latéraux et par une traverse inférieure parmi lesquels chaque montant latéral porte un axe d'articulation de ladite extrémité d'une bielle d'articulation du hayon dont l'autre extrémité est articulée sur un axe d'articulation porté par le hayon ;
• le dispositif comporte des moyens d'équilibrage de l'ouvrant qui lui appliquent un couple d'équilibrage qui compense le couple résistant dû à la masse de l'ouvrant.

According to other characteristics of the invention:

• the servo means comprise a servo mechanism comprising in particular a rack which is slidably mounted longitudinally relative to the body of the connecting rod, a first toothed end of which cooperates permanently with a first pinion linked in rotation to the structure of the body of the vehicle, the second end of which is shaped like a fork, the two substantially parallel toothed branches of which extend rearward and are capable of cooperating alternately with one or the other, respectively, of two diametrically opposite toothed sectors d 'a second pinion linked in rotation to the opening;
• each of the two branches of the fork is mounted so as to rotate relative to the body of the rack, about an axis of rotation parallel to the articulation axes of the connecting rod, and is elastically stressed in rotation about its axis in the corresponding direction at the engagement of the branch with the corresponding toothed sector of the second pinion, and each branch comprises means for controlling its angular position to cause its engagement, or disengagement, with the teeth of the second pinion as a function of the longitudinal position of the second end of the rack relative to the body of the connecting rod;
• the control means comprise a control finger carried by the branch and which extends laterally to cooperate with a control ramp of substantially longitudinal orientation, formed opposite the body of the connecting rod, in the vicinity of the second rear end of the latter;
• each ramp has two consecutive sections, external disengagement and internal engagement separated by an inversion slot allowing the passage of the control finger from one to the other of the two sections, which are offset transversely with respect to to the other and relative to the longitudinal axis of sliding of the rack;
• the opening is a tailgate which, in the closed position, extends in a substantially vertical plane and which, in the open position, extends in a substantially horizontal plane above the vehicle;
• the tailgate is formed by a panel masking a recess in a frame of the structure delimited by an upper crossmember, by two lateral uprights and by a lower crossmember among which each lateral upright carries an axis of articulation of said end of a connecting rod articulation of the tailgate whose other end is articulated on a hinge pin carried by the tailgate;
• the device comprises means for balancing the opening which apply to it a balancing torque which compensates for the resistant torque due to the mass of the opening.

• la figure 1 est une vue latérale, avec arrachement partiel, de la partie arrière d'un véhicule automobile dont le hayon arrière est équipé d'un dispositif d'articulation conforme aux enseignements de l'invention et qui est illustré, en traits pleins, en position extrême ouverte et, en silhouette, en position extrême fermée et dans une position intermédiaire sensiblement médiane dans laquelle se produit l'inversion du sens de pivotement de l'ouvrant ;
• la figure 2 est une vue en élévation et à plus grande échelle du détail D2 de la figure 1 et sur laquelle sont représentés ses principaux éléments de l'extrémité avant d'une bielle d'articulation conforme aux enseignements de l'invention ;
• la figure 3 est une vue en élévation et à plus grande échelle correspondant au détail D3 de la figure 1 qui illustre l'extrémité arrière de la bielle d'articulation reliée au hayon ;
• les figures 4 et 5 sont des vues similaires à celle de la figure 3 correspondant aux détails D4 et D5 de la figure 1 ;
• les figures 6 et 7 sont des vues en coupe selon les lignes 6-6 et 7-7 de la figure 4 ;
• la figure 8 est une vue en section selon la ligne 8-8 de la figure 2 ; et
• la figure 9 est une vue partielle en perspective éclatée qui illustre les principaux composants actifs du dispositif d'articulation conforme aux enseignements de l'invention agencé au niveau de l'extrémité arrière de la bielle.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which:

• FIG. 1 is a side view, with partial cutaway, of the rear part of a motor vehicle, the tailgate of which is equipped with an articulation device in accordance with the teachings of the invention and which is illustrated in solid lines, in the extreme open position and, in silhouette, in the extreme closed position and in a substantially middle intermediate position in which the reversal of the direction of pivoting of the opening occurs;
• Figure 2 is an elevational view on a larger scale of the detail D2 of Figure 1 and on which are shown its main elements of the front end of a hinge rod according to the teachings of the invention;
• Figure 3 is an elevational view on a larger scale corresponding to the detail D3 of Figure 1 which illustrates the rear end of the articulation rod connected to the tailgate;
• Figures 4 and 5 are views similar to that of Figure 3 corresponding to the details D4 and D5 of Figure 1;
• Figures 6 and 7 are sectional views along lines 6-6 and 7-7 of Figure 4;
• Figure 8 is a sectional view along line 8-8 of Figure 2; and
• Figure 9 is a partial exploded perspective view which illustrates the main active components of the articulation device according to the teachings of the invention arranged at the rear end of the connecting rod.

FIG. 1 shows a side view of the rear part of a motor vehicle 10 whose body 12 is open at the rear to allow access to the passenger compartment 14 of the vehicle and for example its load.

For this purpose, the opening is delimited by a frame which extends in a substantially vertical plane and which is essentially consisting of two vertical lateral uprights one of which is shown in Figure 1, the side upright opposite being arranged symmetrically with respect to the plane longitudinal median of general symmetry of the vehicle, and by two upper 18 and lower 20 crosspieces which delimit a recess, the closure of which is ensured by an opening 22, also called tailgate, which is generally pivotally mounted relative to the structure of the vehicle body 12, around horizontal axes.

Tailgate 22 is shown in the extreme open position maximum in Figure 1.

According to a known design, the opening 22 is mounted swiveling on the body 12 by a two-axis system horizontal articulation geometries A1 and A2 thanks to a articulation mechanism with two parallel connecting rods which extend substantially parallel to the longitudinal axis of the vehicle, and one of which 24 is illustrated in the figures.

Referring to Figures 1, 2 and 8, we see that the first front end 26 is hinged on the structure of the vehicle body around the first front axis A1 while the second opposite end 28 is articulated on the opening 22 around the second rear axis of articulation A2, parallel to the first axis of articulation A1, these two axes extending in the general direction transverse of the vehicle.

The first articulation axis A1 is located vertically in the vicinity of the crosspiece 18 and, in the extreme position opening, the tailgate 22 extends in a plane substantially horizontal above the vehicle 10 and in particular partly at above his flag.

According to a known technique, which is by example described and represented in the documents FR-A-2.703.005 or FR-A-2.717.213, the contents of which are may refer for more details, the movement of pivoting of the opening 22 about the axis A2, relative to the second end 28 of the connecting rod 24, is generally controlled to the pivoting movement of the first end 26 of the connecting rod 24 relative to the structure 12, 16 of the body of the vehicle by a servo mechanism.

As can be seen in the figures, the body of the connecting rod 24 is essential consisting of a sheet metal part cut and stamped in the general form of a plate 32 whose longitudinal and parallel edges 34A and 34B are folded at a right angle.

The connecting rod 30 is thus in the form of a body hollow in which various components are arranged belonging to the servo mechanism.

The servo mechanism 30 includes a rack 36 whose tubular body is slidably mounted longitudinally inside the connecting rod 24 according to a sliding general direction C, in a first direction C1 forward and in a second direction C2 backward.

The free front end 38 of the rack 36 is a toothed sector whose teeth 40 cooperate with the teeth in opposite 42 of a first toothed pinion P1 of axis A1 fixed on a structural element of the vehicle body by through a screw 44 which carries a socket 46 for the rotational mounting, around axis A1, of the rear end 26 of the connecting rod 30.

The toothed end 38 is maintained in cooperation with the teeth of the pinion P1 by means of a roller 45 which la spring loaded under the action of a spring 46 fixed to the connecting rod 24.

From the position illustrated in Figure 2, we understands that the simultaneous rotation of the connecting rod 24 and the rack 36 around axis A1 causes sliding in direction C and in direction C2 of rack 36 by relative to the body of the connecting rod 24, the rack moving in the opposite direction C1 when the direction of rotation of the connecting rod is reversed with respect to the fixed gear P1.

As can be seen in particular in FIGS. 3 to 5, the rear free end 28 of the rod 30 body is shaped like a fork with two parallel branches 28A and 28B which are interconnected by the shaped body of plate 32.

Similarly, the second rear end of the rack 36 is shaped like a fork with two branches articulated.

For this purpose, its tubular body divides into Y by two rear end branches 50A and 50B each of which its free end, around a pivot 52A, 52B, a section toothed rack 54A, 54B.

The two toothed sections 54A, 54B thus extend longitudinally rearward, substantially parallel to the sliding direction C, from their longitudinal parts rear which are mounted articulated on the branches 50A and 50B around axes parallel to axes A1 and A2.

Each toothed branch or section 54A, 54B extends forward beyond the pivot 52A, 52B by a tail 56A, 56B each of which carries a finger 58A, 58B which extends laterally and which cooperates with one of the branches 60A, 60B of a spring in wire 60 whose body is helically wound around a finger 62 which is slidably mounted in a rectilinear light 64 formed in the plate 32 of the body of the connecting rod 24 and which extends longitudinally in direction C, being delimited by its front end edges 66 and rear end 68. For sliding finger 62 with the rack 36, its other end is crimped into a hole 69 in the body of the rack.

Thus, the toothed section 54A is resiliently stressed continuously rotating around the axis of the pivot 52A in clockwise considering Figures 3 to 5, while the opposite toothed section 54B is rotated in the counterclockwise, that is, the spring 60 tends to permanence of bringing teeth 72A, 72B closer to both sections towards each other and towards the second rear axis of articulation A2 located inside the fork.

As can be seen in particular in FIG. 7, the second plate 70 of the body of the connecting rod 24 door, in the vicinity from the rear end 28 of the latter, a pivot 74 of axis A2.

The pivot 74 is fixed to the plate 70 and it carries in rotation, with interposition of sliding rings 76, a sleeve bearing 78 on which is rotatably mounted, about the axis A2, the body of the second toothed pinion P2 with which the sections 54A and 54B of the rack 36.

The pinion P2 is centered by a shoulder 80 in a semicircular hole 82 of the rear part of the plate 32 of the rod body 24.

The bearing sleeve 78 has a radial groove internal 84 in which a complementary edge 86 is received a plate 88 belonging to the tailgate 22.

The pinion P2 is linked in rotation to the plate 88 of the tailgate 22 by means of a screw 90, eccentric with respect to the axis A2, which crosses the tab 88 and a socket 92, in which it is screwed, and which is itself carried by the pinion P2.

The sleeve 92 is slidably mounted in a light 94 in an arc formed in the plate 32 in the vicinity of the rear end 28 of the connecting rod 24 which is delimited by two rounded ends 96 and 98.

The pinion P2 is thus linked in rotation to the tab 88 of the tailgate 22 and the rear end 28 of the connecting rod 24 is mounted at rotation about the axis A2 relative to the leg 88 of the tailgate 22 and therefore relative to the pinion P2, the light 94 being centered on axis A2.

The toothed pinion P2 has two toothed sectors 100A and 100B centered around the axis A2, the radius of the sector toothed 100A being greater than the radius of the toothed sector 100B.

The teeth of the first toothed sector 100A are provided to mesh with the teeth opposite 72A of the section 54A of rack 36 while the teeth of the second sector toothed 100B are provided to mesh with the teeth 72B of the section 54B and this under the action of the spring 60.

As we can see in particular in Figures 4 and 7, each of the two sections 54A, 548 comprises a finger control 102A, 102B which extend laterally opposite folded edges 34A and 34B of the end branches rear 28A and 28B of the body of the connecting rod 24.

The folded edges 34A and 34B of the branches 28A and 28B of the rear end 28 of the connecting rod 24 constitute profiles or cams for controlling the angular positions of the sections teeth 54A and 54B which determine the engagement or engagement teeth 72A, 72B of these sections with the sectors teeth 100A and 100B of the second pinion P2.

Thus, the edge 34A of the branch 28A comprises at its free end rear an external surface 104A of clearance of section 54A, which is of centered curved profile around the axis A2 and which extends backwards, beyond a slot or notch 106A, by an internal face 108A of control of engagement or engagement of section 54A with sector 100A of pinion P2.

Similarly, the edge 34B has at the end rear of branch 28B an internal engagement profile 108B the toothed section 54B which extends beyond a slot or notch 106B, towards the front by an external face 106B of clearance of section 54B.

We will now describe the operation of the device of articulation with the reversing servo mechanism the direction of pivoting of the sash around the axis A2.

In the first closed extreme position illustrated in the Figure 3, the rack 36 occupies its extreme rear position relative to connecting rod 24, the pivot 68 and the spring 60 being in particular located opposite the rear end 68 of the light 64.

In this position, it is the toothed sector 100B of the pinion P2 which meshes with the teeth 72B of the toothed section 54B while the teeth of the toothed sector 100A do not mesh not with the teeth 72A of the toothed section 54A.

In this extreme rear position of the rack 36, the control finger 102A of the section 54A cooperates with the external clearance surface 104A towards which it is elastically stressed by the action of the strand 60A of the spring 60.

Conversely, the control finger 102B of the section toothed 54B cooperates with the internal engagement surface 108B, i.e. the toothed section 54B cannot rotate clockwise considering figure 3, around the axis of its pivot 52B, thus ensuring the engagement teeth 72B with teeth of the toothed sector 100B of the pinion P2, the teeth being further solicited in cooperation by the action of the strand 60B of the spring 60.

From this position, if the user starts to open the tailgate 22, it will generally cause rotation, counterclockwise considering the figures, of the connecting rod 24 around the axis A1. This rotation has the effect gradually drive the rack 36 sliding backward in direction C1 from the position shown in Figure 3.

Sliding backwards in direction C1 of the rack 36 drives the pinion P2 in rotation, relative to the connecting rod 24 and around the axis A2, clockwise in considering figure 3.

So, as can be seen in Figure 1 and during of the first part of its opening trajectory, the tailgate 22 will generally pivot around the horizontal articulation axis A2 clockwise, i.e. its lower edge 23 will not describe the circular path T 'centered around axis A1, as in the case of the state of the art, but that he will instead describe the first part of the trajectory T illustrated in the figure.

As seen in Figure 1, this first part trajectory during which the lower edge 23 gradually approaches the rear vertical plane of the vehicle greatly reduces the minimum distance L between the rear bumper 17 of the vehicle and the front bumper 19 of a vehicle parked behind and nearby.

Pivoting and moving movements relative which have just been described starting from figure 3 se continue to the middle position shown in Figure 4 which corresponds to the position in which reverses the relative direction of rotation between the rear end 28 of the connecting rod 24 and the opening 22.

In this intermediate position, the connecting rod 24 is substantially horizontal orientation.

The fingers 102A and 102B for controlling the sections teeth 54A and 54B are exactly opposite the slots 106A and 106B. The last tooth 100B 'of the toothed sector 100B of pinion P2 cooperates with the last tooth 72B 'of the toothed section 54B while the first tooth 100A 'of the toothed sector 100A cooperates with the first tooth 72A 'of the toothed section 54A.

The control finger 102A no longer cooperates with the external clearance surface 104A and, under the action of the strand 60A of the spring 60, the toothed section 54A pivots about the axis of the pivot 52A, clockwise when considering the figures, so as to cause the meshing of the first teeth 72A 'and 100A'.

It can be seen that the angular travel of the pinion P2 between the extreme closed position of FIG. 3 and the position of reversal of direction of figure 4 corresponds to the course complete with light 94, from its end 98 towards its end 96, by the sleeve 92 of the pivot 90.

The pivot 62 which carries the spring 60 is substantially mid-length of the light 64, i.e. the rack 36 is generally at mid-length of its maximum stroke by relative to the body of the connecting rod 24.

From the position illustrated in Figure 4, if the rack 36 continues to run in direction C1 forwards of the vehicle, i.e. if the tailgate opening phase continues, the teeth of the toothed section 54A will stop the clockwise rotation, considering figure 4, of the pinion P2 around the axis A2 and force the latter to rotate counterclockwise, that is, counterclockwise.

It is the teeth of the toothed sector 100B, for through its tooth 100B 'which, acting on the slope of the last tooth 72B 'of the toothed section 54B, then pivot this section 54B around the axis of the pivot 52B to cause its disengagement or disengagement, the finger 102B no longer pressing against the internal surface commitment 108B.

From the position illustrated in Figure 4, if the opening continues, the sliding movements and rotation continue until reaching the maximum position shown in Figure 5.

During the opening stroke of the tailgate 22 between the Figures 4 and 5, the control finger 102B of the toothed section 52B of the rack 36 cooperates with the external surface of clearance 104B and, despite the action of the spring strand 60B 60, the toothed section 54B cannot pivot around the axis of its pivot 52B, counterclockwise, so it cannot accidental engagement between teeth 72B and teeth of sector 100B of pinion P2.

On the contrary, the control finger 102A cooperates with the internal engagement surface 108A so as to guarantee that teeth 72A always mesh with the teeth of the toothed sector 100A.

The cooperation of the teeth of the toothed section 52A with the teeth of pinion P2, when sliding forwards in the C1 direction of the rack 36 relative to the connecting rod 24 - between the positions illustrated in Figures 4 and 5 - causes then simultaneously a rotation of the pinion P2, and therefore of the tailgate 22, relative to the rear end 28 of the connecting rod 30 counterclockwise considering Figures 4 and 5.

Considering Figure 1, we therefore see that, at from the middle position in which the connecting rod 24 is horizontal and up to the open top position in which the rod 24 is substantially vertical, the tailgate 22 rotates around axis A2 counterclockwise so to reach an extreme opening position of the tailgate 22 in which it extends substantially horizontally above the vehicle roof with its outer side facing up.

During this second part of the opening movement, the lower edge 23 of course deviates again towards the rear relative to the rear vertical plane of the vehicle but this in a high area in which there is no more risk of interference and collision with the game front of the vehicle body located immediately behind.

All sliding movements and rotation (s) which have just been described are reversed during the tailgate closure.

To facilitate maneuvers, the tailgate may well heard to be equipped with means (not shown on the figures) of known design which compensate for its mass and which facilitate its maneuvers.

Claims (8)

1. An articulation device for an opening member (22) mounted to pivot on the structure (12) of the body of an automobile vehicle (10), in particular between a first closed end position and a second open end position, by means of a mechanism with two parallel articulation pins (A1, A2) connected by at least one articulation rod (24), a first front end (26) of which is articulated on the structure of the body of the vehicle about a first articulation pin (A1) and a second end (28) of which is articulated on the opening member (22) about a second articulation pin (A2) parallel to the first articulation pin (A1) and of the type in which there are provided means (36) for the control of the pivoting movement of the opening member (22), with respect to the second end (28) of the rod (24), by the pivoting movement of the first end (26) of the rod, with respect to the structure (12) of the vehicle body, characterised in that the direction of pivoting of the opening member (22), with respect to the second end of the rod, is inverted during the pivoting movement of the first end (26) of the rod (24), with respect to the structure of the vehicle body, between two end angular positions associated with the closed and open end positions of the opening member.
2. An articulation device as claimed in the preceding claim, characterised in that the control means comprise a control mechanism in particular including a rack (36) which is mounted to slide longitudinally with respect to the body of the rod (24), a first toothed end (38) of which cooperates permanently with a first pinion (P1) connected in rotation to the structure (12) of the vehicle body and a second end of which is shaped as a fork whose two substantially parallel toothed arms (54A, 54B) extend rearwards and are able to cooperate alternatively with one or the other respectively of two diametrically opposing toothed sectors (100A, 100B) of a second pinion (P2) connected in rotation with the opening member (22).
3. An articulation device as claimed in the preceding claim, characterised in that each of the two arms (54A, 54B) of the fork is mounted to rotate with respect to the body (36, 50A, 50B) of the rack about a front axis (52A, 52B) of rotation parallel to the articulation pins (A1, A2) of the rod (24) and is elastically urged (60) in rotation about its axis in the direction corresponding to the engagement of the arm (54A, 54B) with the corresponding toothed sector of the second pinion, and in that each arm comprises means (102A, 102B) for controlling its angular position in order to cause its engagement, or its disengagement, with respect to the teeth of the second pinion (P2) as a function of the longitudinal position of the second end of the rack (36) with respect to the body of the rod (24).
4. An articulation device as claimed in the preceding claim, characterised in that the control means comprise a control finger (102A, 102B) borne by the arm (54A, 54B) which extends laterally in order to cooperate with a control ramp (104A, 104B, 106A, 106B, 108A, 108B) of substantially longitudinal orientation, formed opposite on the body of the rod (32, 34A, 34B) in the vicinity of the second rear end (28, 28A, 28B) of the latter (24).
5. An articulation device as claimed in the preceding claim, characterised in that each ramp comprises two consecutive sections, an outer disengagement section (104A, 104B) and an inner engagement section (108A, 108B), separated by an inversion slot (106A, 106B) enabling the control finger (102A, 102B) to pass from one to the other of the two sections, which are offset transversely with respect to one another and with respect to the longitudinal axis of sliding of the rack.
6. An articulation device as claimed in any one of the preceding claims, characterised in that the opening member is a rear door (22) which, in the closed position, extends in a substantially vertical plane and which, in the open position, extends in a substantially horizontal plane above the vehicle.
7. An articulation device as claimed in claim 6, characterised in that the rear door is formed by a panel masking a recess of a framework of the structure bounded by an upper transverse member (18), by two side uprights (16) and by a lower transverse member (20) of which each side upright bears an articulation pin (Al) of the end of an articulation rod (24) of the rear door whose other end is articulated on an articulation pin (A2) borne by the rear door.
8. An articulation device as claimed in any one of the preceding claims, characterised in that it comprises means for balancing the opening member which apply a balancing moment thereto which offsets the resistant moment due to the mass of the opening member.

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