Hinge mechanism and vehicle seat comprising such a mechanism

Hinge mechanism comprising first and second frames connected together by an adjustment device comprising a first set of gear teeth integral with the first frame and a first mobile toothed element engaging with the first set of gear teeth A second toothed element, mounted mobile on the second frame, engages with an additional set of gear teeth integral with the first frame.

FIELD OF THE INVENTION

The present invention relates to hinge mechanisms for vehicle seats and seats comprising such mechanisms.

More particularly, the invention relates to a hinge mechanism comprising:first and second frames rotatably mounted in relation to each other about an axis of rotation,a geared adjustment device connecting the first and second frames together to allow adjustment of a relative angular position of said first and second frames, said adjustment device comprising:at least one first set of gear teeth integral with one of the first and second frames,at least one first toothed element (for example, a cam-controlled locking cam follower when the adjustment device is a locking device, or a circular set of gear teeth oriented radially outwards when the adjustment device is a hypocycloidal gear device, etc.) capable of engaging with said first set of gear teeth and mobile in relation to said first set of gear teeth,and a first actuation device capable of actuating the first toothed element for controlling the adjustment device,and a second toothed element borne by the second frame, said second toothed element engaging with an additional set of gear teeth integral with the first frame.

BACKGROUND OF THE INVENTION

The document FR-A-2 708 237 describes an example of such a hinge mechanism, in which:the first set of gear teeth is integral with the first frame,the first toothed element is an eccentric circular set of gear teeth with respect to the first set of gear teeth, oriented radially outwards and integral with the second frame,and the second toothed element is a set of eccentric circular gear teeth with respect to the additional set of gear teeth, oriented radially inwards and integral with the second frame.

This hinge mechanism gives complete satisfaction. In particular, the additional set of gear teeth and the second toothed element of this hinge mechanism make it possible to increase the mechanical strength of the hinge mechanism, in particular in the case of a road accident when this mechanism is used in a vehicle seat. However, this principle can be used only with a hypocycloidal gear adjustment device.

OBJECTS AND SUMMARY OF THE INVENTION

The aim of the present invention is to improve the hinge mechanisms of the previously mentioned type, in particular to propose an arrangement that is compatible not only with hypocycloidal gear adjustment devices, but also with locking adjustment devices (i.e. capable of selectively immobilizing or releasing the relative rotation of the first and second frames in relation to each other).

To this end, according to the invention, a hinge mechanism of the type in question is characterized in that the second toothed element is mounted mobile in relation to the second frame,

and in that said hinge mechanism comprises a second actuator device capable of actuating said second toothed element.

Thanks to these arrangements, the second toothed element and the additional set of gear teeth can be used to provide an additional functionality with respect to the adjustment device (additional locking, control of the relative rotation between the first and second frames, or other), even when the adjustment device is a locking device.

In different embodiments of the hinge mechanism according to the invention, it is moreover possible, optionally, to make use of one and/or another of the following arrangements:the additional set of gear teeth is oriented radially outwards;the first set of gear teeth is oriented radially inwards;the adjustment device is capable of selectively immobilizing and releasing the relative rotation of the first and second frames in relation to each other;the first toothed element is mounted mobile in relation to the one of the two frames which is not integral with the first set of gear teeth, said first toothed element being displaceable between, on the one hand, a locking position where said first toothed element is engaged with the first set of gear teeth and, on the other hand, an unlocking position where said first toothed element is not engaged with said first set of gear teeth;the first set of gear teeth is integral with the first frame and the first toothed element is mounted mobile in relation to the second frame;the first actuation device comprises at least one first cam mobile between first and second positions and elastically loaded towards the first position, said first cam acting on the first toothed element so that it is in locking position when said first cam is in first position and in unlocking position when said first cam is in second position;the first cam is capable of pushing back the first toothed element into locking position when said first cam is in the first position and allowing the first toothed element to be displaced towards the unlocking position when said first cam is in the second position;the first cam is integral with an unlocking plate capable of displacing the first toothed element into the unlocked position when said first cam is in second position;the second toothed element is mounted mobile in relation to the second frame between, on the one hand, a locking position where said second toothed element is engaged with the additional set of gear teeth and, on the other hand, an unlocking position where said second toothed element is not engaged with said additional set of gear teeth;the second actuation device comprises at least one second cam mobile between first and second positions and acting on the second toothed element;said second cam is elastically loaded towards the first position;the second cam is capable of placing the second toothed element in the unlocking position when said second cam is in the second position and allowing the second toothed element to be displaced towards the locking position when said second cam is in the first position;the second toothed element is elastically loaded towards the locking position;the first and second cams are integral with each other;the second toothed element comprises teeth each having first and second flanks oriented in first and second angularly opposed directions and the additional set of gear teeth also comprises teeth having two flanks, the second toothed element being arranged such that only the first flanks of its teeth come into contact with the tooth flanks of the additional set of gear teeth when the first toothed element is fully engaged in the first set of gear teeth;the second toothed element is angularly offset, in relation to a position in which its teeth would be fully engaged in the teeth of the additional set of gear teeth when the first toothed element is fully engaged in the first set of gear teeth;the second toothed element is arranged to engage with the additional set of gear teeth after the first toothed element has engaged with the first set of gear teeth when the first and second cams are displaced from the second towards the first position;the second actuation device is capable of displacing the second toothed element into the locking position when said hinge mechanism is subjected to adequate acceleration;the second actuation device comprises a second cam controlled by a lever bearing a counterweight;the second actuation device comprises means of retention for retaining the counterweight in a position corresponding to the unlocking position of the second toothed element so long as it is not subjected to an acceleration greater than a predetermined value;the second cam is capable of placing the second toothed element in the locking position when said second cam is in the second position and allowing the second toothed element to be placed in the unlocking position when said second cam is in the first position, the second toothed element being elastically loaded towards the unlocking position;the first and second cams are integral with first and second coupling elements, the second coupling element being capable of acting on the first coupling element, displacing the first cam from the first to the second position when the second cam is actuated to be displaced from the first to the second position, while the first coupling element is adapted so that it does not foul the second coupling element when the first cam is actuated to be displaced from the first to the second position;the first and second coupling elements are levers;the second frame comprises a guide capable of guiding the second toothed element while keeping it engaged with the additional set of gear teeth during a rotation between the first and second frames after an actuation of the second cam towards the second position;the guide extends angularly between the first and second stops and comprises a notch at the position of the first stop, said notch allowing the second toothed element to be displaced into the unlocking position only at the position of the first stop;the second toothed element comprises a lateral pin and the second frame comprises a flexion spring arranged close to the first stop, said flexion spring comprising an end ramp which is capable of engaging on the pin when the second toothed element is angularly displaced in the guide towards the first stop, and said flexion spring being capable of elastically loading the second toothed element towards the unlocking position when said second toothed element is at the position of the first stop;the second toothed element is a pinion which is mounted rotatably on the second frame and which engages with the additional set of gear teeth;the second actuation device comprises an electric motor driving the second toothed element;the first actuation device is electrically controlled synchronically with said electric motor to displace the first toothed element into the unlocking position when said electric motor rotates;the second actuation device is a pump device actuated by a handle and driving the second toothed element;said handle is mounted pivotally in relation to the second frame, said handle being elastically loaded towards a position of rest and being displaceable in a first direction starting from the position of rest, in a first angular sector, and in a second direction opposed to the first direction starting from the position of rest, in a second angular sector, and the pump device is capable of:positively driving the second toothed element, respectively in first and second angularly opposed directions, when the handle is displaced in a direction away from the position of rest respectively in one or the other of the first and second directions,and not driving the second toothed element when the handle is displaced towards the position of rest;the first actuation device comprises at least one first cam mobile between first, second and third positions and elastically loaded towards the first position, said second and third positions being situated on either side of the first position, said first cam acting on the first toothed element so that it is in locked position when said first cam is in first position and in unlocked position when said first cam is not in first position;the first cam is integral with an unlocking plate capable of displacing the first toothed element into the unlocked position when said first cam is not in first position.

Moreover, a subject of the invention is also a vehicle seat comprising a seat base and a backrest mounted pivotally in relation to the seat base by means of at least one hinge mechanism as previously defined.

MORE DETAILED DESCRIPTION

The same references denote identical or similar elements on the different figures.

FIG. 1represents a vehicle seat1, for example a front seat of a motor vehicle, which comprises a seat base2fixed on the floor3of the vehicle, for example by means of longitudinal runners3a, and a backrest4mounted pivotally in relation to the seat base2about a horizontal transverse axis of rotation Y, by means of at least one hinge mechanism5controlled for example by a handle6or similar.

In all the embodiments of the invention described hereinafter, the hinge mechanism5comprises (see for exampleFIGS. 2 to 5):a first rigid metal frame7which is integral for example with the structure of the backrest4and which can be realized in particular in the form of a flange extending approximately perpendicular to the axis of rotation Y,a second rigid metal frame8which is fixed for example to the structure of the seat base2(the first frame7could if necessary be fixed to the structure of the seat base2and the second frame8be fixed to the structure of the backrest4) and which can be realized in particular in the form of a flange extending approximately perpendicular to the axis of rotation Y,a closure element9, for example a rigid metal gusset fixed to the second frame6, for example by welding, which holds captive the first and second frames7,8, against each other while allowing a relative rotation of these two frames7,8in relation to each other about the axis of rotation Y, the first and second frames7,8thus forming an enclosed housing which delimits an internal space,and an adjustment mechanism10, arranged in the previously mentioned internal space and making it possible to adjust a relative angular position between said first and second frames.

The adjustment mechanism10of the different embodiments of the invention described herein can be an immobilizing mechanism capable of selectively immobilizing or releasing the relative rotation between the first and second frames7,8.

The adjustment mechanism10can be for example of the type described in the document FR-A-2 740 406, thus comprising (seeFIGS. 4 and 5):a first set of gear teeth11which is integral with one of the first and second frames7,8, for example the first frame7, wherein said first set of gear teeth11can be in particular a circular set of gear teeth centered on the axis Y and oriented radially inwards,at least one first toothed element12, and for example three first toothed elements12arranged at 120° from each other about the axis Y, this or each first toothed element12being mounted mobile in relation to said first set of gear teeth with respect to the second frame8, between, on the one hand, a locking position where said first toothed element12is engaged with the first set of gear teeth11and, on the other hand, an unlocking position where said first toothed element12is not engaged with said first set of gear teeth11.

The adjustment mechanism10of the different embodiments of the invention described herein is therefore an immobilizing mechanism capable of selectively immobilizing or releasing the relative rotation between the first and second frames7,8in relation to each other.

In the different embodiments described herein, the first toothed element12is realized in the form of a rigid metal plate extending in a plane perpendicular to the axis of rotation Y and having an external set of gear teeth13as well as first and second pins14,15projecting axially in the direction of the axis Y and radially offset in relation to each other.

In the different embodiments described herein, the adjustment mechanism10also comprises a first actuation device capable of actuating the first toothed element12to control the adjustment device10. This first actuation device can for example comprise:a first rigid metal cam16which can extend in a plane perpendicular to the axis Y and which can for example be integral with a drive shaft17extending along the axis Y,an unlocking control disk18integral with the first cam16and being for example in the form of a rigid metal plate parallel to the first cam16, said control disk comprising cutouts19into which the first pins14of the first toothed elements12are introduced.

The first cam17and the control disk18are mounted pivotally about the axis Y between:a first position where the first cam16pushes back each first toothed element12outwards so that it is in locked position (seeFIG. 5),and a second position where the first cam16stops pushing each first toothed element12radially outwards and/or the corresponding cutout19acts by cam effect on the first pin14to displace the first toothed element12radially inwards into the unlocking position.

Moreover, in the different embodiments described herein, the first toothed elements12are slidably mounted radially between guides20formed in the first frame by stamping (seeFIG. 5) and the second pin15of each first toothed element can be capable of coming to bear against a circular ramp centered on the axis Y and belonging to the first frame7(this circular ramp is not shown on the drawings, but is described and shown in the previously mentioned document FR-A-2 740 406) to prevent the first toothed elements12engaging with the first set of gear teeth11in certain relative angular positions of the first and second frames.

The first cam16and the control disk18can be elastically loaded towards their first position, for example by means of springs21arranged in the inside space between the first and second frames7,8and integral with the second frame8.

Moreover, according to the invention, the hinge mechanism also comprises at least one second rigid metal toothed element which is mounted mobile in relation to the second frame8and which is controlled by a second actuation device, said second toothed element comprising a set of gear teeth22aoriented radially inwards and engaging with an additional integral set of gear teeth23of the first frame7

Advantageously, the sets of gear teeth22aand23can be arranged in a mutually corresponding fashion, approximately in a common plane perpendicular to the axis Y.

In the first embodiment of the invention, which is shown inFIGS. 2 to 6, the second toothed element22is mounted mobile in relation to the second frame8between, on the one hand, a locking position where said second toothed element22is engaged with the additional set of gear teeth23and, on the other hand, an unlocking position where said second toothed element22is not engaged with said second additional set of gear teeth23. The additional set of gear teeth23in question can be a circular set of gear teeth centered on the axis Y (forming a circle which can be complete or not), formed on an external periphery of the first frame7and oriented radially outwards.

The second toothed element22, for its part, can be in the form of a rigid metal cam follower extending in a plane perpendicular to the axis Y and mounted for example slidably approximately radially with respect to the axis Y between the second frame8and the gusset9, in a guide9aformed in the gusset9for example by stamping.

The second toothed element22can be elastically loaded towards its locking position, for example by means of a spring24bearing on the gusset9and/or on the second frame8.

The second actuation device, which controls the second toothed element22, can also comprise a second cam25which can for example be integral with the drive shaft17and thus be mobile between said first and second positions with the first cam16.

The second cam25can for example have the form of a sheet metal plate extending in a plane perpendicular to the axis Y and having an end edge which comprises first and second circular portions26,27centered on the axis Y, the second circular portion27having a radius greater than the first circular portion26and being connected to said first circular portion26by an inclined ramp28(seeFIG. 2).

Moreover, the second toothed element22is integral with a rigid metal rod29or other which projects axially in the direction of the axis Y and passes through a radial opening30provided in the second frame8(seeFIGS. 2 and 4).

Under the effect of the spring24, the rod29is pressed towards the end edge of the second cam25. When the second cam25and the first cam16are in their first position, the rod29is opposite the first portion26of the end edge of the second cam25, such that the second toothed element22can engage with the additional set of gear teeth23.

However, when the first and second cams16,25are displaced into their second angular position:on the one hand, the first toothed elements12are displaced into their unlocking position (seeFIG. 6),and the second portion27of the end edge of the second cam25pushes back the rod29and the second toothed element22radially outwards, such that said second toothed element22is placed in the unlocking position again, thus making it possible for a user to adjust the angular position of the backrest4as required, by manual action or by action of the back on said backrest4.

When the handle6is released by the user, the first and second cams16,25, return to first position, such that the first toothed elements12and the second toothed element22return to locking position.

Thanks to the presence of the second toothed element22, the mechanical strength of the hinge mechanism5is increased, which enhances the safety of users of the seat1.

The second embodiment of the invention is very similar to the first embodiment of the invention and therefore will not be described in detail.

The second embodiment of the invention, shown inFIGS. 7 and 8, is distinguished from the first embodiment previously described only by the fact that the second toothed element22is slightly angularly offset about the axis of rotation Y, with respect to the position that it occupies in the first embodiment.

In fact, in the first embodiment of the invention, the position of the second toothed element22is such that its teeth are fully engaged with the teeth of the additional set of gear teeth23when the first toothed elements12are fully engaged with the first set of gear teeth11, while in the second embodiment, the teeth of the second toothed element22are not fully engaged with the teeth of the additional set of gear teeth23when the first toothed elements12are fully engaged with the first set of gear teeth11.

On the other hand, in the second embodiment, when the adjustment device10locks and the teeth of the first toothed element12fully engage with the first set of gear teeth11, only the flanks31of the teeth of the set of gear teeth22a, oriented in a first angular direction33, come into contact with the flanks of the teeth of the additional sets of gear teeth23(seeFIG. 8). In this position, the opposite flanks32of the teeth of the set of gear teeth22a, oriented in the opposite angular direction34, are not in contact with the corresponding flanks of the teeth of the additional set of gear teeth, such that the contact between the set of gear teeth22aand23presses the first frame in the angular direction33. This pressure takes up any play which may be present in the adjustment device10.

In the second embodiment of the invention, the second toothed element22can be arranged such as to engage with the additional set of gear teeth23after each first toothed element12has engaged with the first set of gear teeth11when the first and second cams are displaced from the second to the first position;

The third embodiment of the invention, shown inFIGS. 9 to 11, is also very similar to the first embodiment of the invention and therefore will not be described in detail.

Said third embodiment is distinguished from the first embodiment only by the following points:the hinge mechanism does not comprise either the second cam25, or the rod29, or the opening30, or the spring24,the second toothed element12is normally in the unlocking position (said second toothed element can for example be mounted freely sliding vertically with friction in the guide9a, and be arranged on the lower part of the hinge mechanism such that its unlocking position is the low position, as in the example shown; in a variant, the second toothed element could be elastically loaded towards its unlocking position),the second actuation device, which controls the second toothed element, is capable of displacing said second toothed element into the locking position when the seat is subjected to an adequate acceleration (positive or negative).

The second actuation device can comprise for example a second rigid metal cam35which is mounted pivotally in relation to the second frame about a horizontal axis of rotation Yl, parallel to the axis Y and perpendicular to the direction of displacement of the vehicle in which the seat1is installed. Said second cam can be mounted pivotally for example by means of a rigid metal shaft36rotating in the second frame, said shaft36being integral with a rigid metal lever37extending downwards and bearing a counterweight38.

The second cam35can pivot with the counterweight between:a first position (shown on the drawings) where the lever37extends vertically downwards and where it allows the second toothed element to remain in its unlocking position,and at least one second position (preferably two second positions, not shown) where the lever37is inclined and where said cam displaces the second toothed element into its locking position.

The second cam can have a symmetrical form with respect to the vertical plane containing the axis Yl so as to push back the second toothed element22into locking position both when the lever37pivots forwards and when it pivots backwards.

Means of retention can be provided to keep the counterweight38and the second cam35in the previously mentioned first position such that said counterweight it is not subjected to acceleration greater than said predetermined value. For example, the counterweight38can have a convex form and be engaged on a complementary concave face39of a bearing piece40(made of plastic or other material) integral with the second frame8, so as to be normally retained in the position of rest by the bearing piece40: when the counterweight is subjected to an adequate acceleration in one direction or in the other, for example when the vehicle in which the seat1is installed experiences a traffic accident, it releases from the bearing piece and makes the lever37and the second cam35pivot. Thus, at the exact moment of the accident, the second cam thus places the second toothed element22in locking position, increasing the strength of the hinge mechanism, which enhances the safety of the user seated on the seat.

It would of course be possible to replace the bearing piece40by other retention means, for example a frangible element, immobilizing the counterweight38, or the lever37, or the second cam35, or the second toothed element.

Further, it would also be possible to remove the counterweight and to actuate the lever37by another means, for example by a pyrotechnic pretensioner controlled by an electronic circuit connected to an impact sensor, an accelerometer or similar.

In the fourth embodiment of the invention, shown inFIGS. 12 to 20, the hinge mechanism5is similar to that described previously and therefore will not be described again in detail: only the differences with respect to the hinge mechanism5previously described are explained hereinafter.

As shown inFIGS. 15 and 16, the second toothed element22of the fourth embodiment is normally in the unlocking position, as in the third embodiment, and can be displaced towards its locking position by means of a rigid metal cam35integral with a rigid metal shaft36which turns in the second frame8. The shaft36is itself integral with a rigid metal lever37(seeFIG. 13), which, in contrast to the third embodiment, extends for example approximately horizontally until reaching a free end integral with one end of a cable41, the other end of which is controlled by a handle41aat the top of the backrest, or otherwise (seeFIG. 12). The lever37, whose utility will become apparent hereinafter, could if necessary be controlled by a control device other than the cable41and the handle41a. For example, the lever37could be directly integrated with a control handle.

The handle41a, or other control element, allows a user to fold the backrest4of the seat forwards, in the direction of the arrow45(FIG. 12), for example to allow the user to gain access to the space situated to the rear of the seat1in a three-door vehicle.

In a manner known per se, folding the backrest4of the seat1can moreover unlock the runners3aof the seat, allowing the user to move the seat base2of the seat forward in order to further improve the access to the space situated to the rear of the seat1.

As shown inFIG. 13, the shaft36and the lever37are also integral with an additional rigid metal lever42which, in the example shown, extends approximately vertically upwards in the position of rest, to reach a free end which comes to bear against one of the lateral edges of another lever formed for example by a rigid metal plate43integral with the shaft17and extending downwards from the shaft17. The plate43and the lever42respectively form first and second coupling elements which are arranged such that an actuation of the shaft17in the angular direction45, to unlock the adjustment mechanism10, does not foul the lever42, but such that an actuation of the handle41acauses the levers37and42to pivot in the angular direction46opposite to the direction45, such that the free end of the lever42displaces the plate43, the control shaft17and the first cam16in the angular direction45, unlocking the adjustment device10.

Moreover, as shown inFIGS. 16 and 17, the closure element9here comprises an enlarged part forming a circular guide44, centered on the axis of rotation Y, which extends in the angular direction45starting from the position normally occupied by the second toothed element22at rest. In this position of rest shown inFIG. 16, said second toothed element22is engaged with a notch44aof the guide44in contact with the previously mentioned guide9aforming a first stop, which allows said second toothed element not to be engaged with the additional set of gear teeth23of the first frame7in the position of rest.

The second toothed element22comprises a rear edge22b, opposite to its set of gear teeth22a, which has a circular form of the same radius as the previously mentioned guide44. Further, the second toothed element comprises a pin22cprojecting laterally parallel to the axis Y, in a pressing47of the closure element9.

Finally, a flexion spring48, for example a spring wire or a spring blade, bears on the pin22cin such a way as to place a load elastically on the second toothed element22towards its unlocking position, while normally retaining it in the previously mentioned notch44a. This flexion spring is attached to the closure element9(therefore also to the second frame8) by one of its ends, and its opposite end forms a ramp48aextending radially inwards at an angle in the angular direction45(seeFIG. 17).

The hinge mechanism according to the fourth embodiment of the invention, operates as follows.

When a user actuates the handle6(FIG. 1) to adjust the angular position of the backrest4, this actuation unlocks the adjustment device10, but has no action on the second toothed element22, which remains lodged in the notch44aof the guide44. Adjustment of the backrest4is therefore carried out in a standard fashion.

On the other hand, when the user actuates the handle41a, it causes the lever37, the shaft36, the second cam35and the lever42to pivot in the angular direction45(seeFIG. 18), such that the second cam35displaces the second toothed element22into locking position, where its set of gear teeth22ais engaged with the additional set of gear teeth23of the first frame7. Further, the free end of the lever42then acts by cam effect on the lever43by causing it to pivot in the angular direction45with the first cam16, thus unlocking the adjustment device10.

The backrest4can then pivot freely forwards in the angular direction45, as shown inFIGS. 19 and 20, until the second toothed element22encounters a second stop44bat the end of the guide44. During this movement, the second toothed element22is kept engaged with the additional set of gear teeth23by its rear edge22bbeating against the circular guide44. During this movement, even if the handle41ais released, the adjustment device10can be retained in the unlocked position by the pins15of the first toothed elements12bearing on the previously mentioned circular ramps of the first frame7(non shown, but described for example in the previously mentioned document FR-A-2 740 406). If the handle6or41ais released by the user when the backrest is in the angular adjustment range (i.e. when the pins15of the toothed elements12axe not opposite the circular ramps in question), the backrest locks, thus avoiding the eventuality of the backrest inadvertently being left unlocked. Optionally, the previously mentioned circular ramps can be omitted, which ensures that the backrest re-locks as soon as the handle6or41ais released.

When the backrest4is then raised (with actuation of the handle6or41aby the user), the first frame7pivots with the second toothed element22in the angular direction46opposite to the angular direction45, until the second toothed element reaches the position opposite the notch44a, abutted against the previously mentioned guide9aof the closure element. When returning to this position, the lifted free end48aof the flexion spring48passes above the pin22cof the second toothed element, such that said flexion spring48again presses the second toothed element22downwards, to engage it in the notch44a. The hinge mechanism then returns to its position of rest as shown inFIG. 16, the backrest being in the angular position that it occupied before being folded forwards.

In the fifth embodiment of the invention, shown inFIGS. 21 to 24, the adjustment device10is identical or similar to that described previously, and therefore will not be described again.

On the other hand, in this fifth embodiment of the invention, the second toothed element50is a pinion provided with an external involute set of gear teeth51, integral with a shaft52which rotates on the second frame8and the closure element9so as to be capable of turning about an axis of rotation Yl parallel to the previously mentioned axis of rotation Y.

The external set of gear teeth51of the pinion engages with the previously mentioned additional set of gear teeth23of the first frame7, this additional set of gear teeth here being an involute set of gear teeth.

As shown inFIG. 22, the shaft52of the second toothed element50can be driven rotatably by an electrically-operated geared motor53. Moreover, the drive shaft17of the adjustment device10can be controlled rotatably by an actuator54, for example an actuator with an electromagnet capable either of displacing the drive shaft17in the direction of unlocking of the adjustment device10, or of not acting on the drive shaft17.

As shown inFIG. 21, the hinge mechanism5can be controlled by an electrical control console49which can for example comprise two switches55,56(or if appropriate a three-position switch).

As shown inFIG. 24, the geared motor53(M) and the actuator54(DEV) can be powered for example by direct current from the battery57of the vehicle.

When the switches55,56are in the position of rest, neither the geared motor53nor the actuator54are powered.

When the switch55is actuated, the actuator54is powered and unlocks the adjustment device10, and the geared motor53is powered with a specific polarization which causes it to rotate for example in the direction of folding of the backrest4forwards. As soon as the user stops actuating the switch55, the geared motor53stops and the actuator54allows the adjustment device to return to the locked position.

When the user actuates the switch56, the actuator54is powered (with the same polarization as in the case of the actuation of the switch55), which unlocks the adjustment device10, and the geared motor53is powered with a polarization which is the reverse of that obtained during the actuation of the switch55, such that said geared motor rotates in the opposite direction to that previously described, i.e. for example in the direction of a backwards pivoting of the backrest4.

In the fifth embodiment of the invention, an electrically-controlled hinge mechanism5is thus obtained which, thanks to the presence of the adjustment device10, has excellent mechanical strength.

In the sixth embodiment of the invention, shown inFIGS. 25 to 27, the hinge mechanism5is similar to that described in the fifth embodiment of the invention, since its second toothed element50is once again a pinion which engages with the additional set of gear teeth23.

On the other hand, in this sixth embodiment of the invention, the hinge mechanism is not controlled by an electrical device, but by a pump device actuated by the previously mentioned handle6.

Pump devices of this type are known, and for example a pump device of the type described in the document FR-A-2 826 320 could be used.

As shown inFIG. 25, the handle5is mounted pivotally in relation to the second frame8about the axis of rotation Yl, said handle6being elastically loaded towards a position of rest N and being displaceable in a first angular direction45starting from the position of rest N, in a first angular sector58, and in a second angular direction46opposite to the first direction, starting from the position of rest N, in a second angular sector59.

The pump device60(seeFIG. 27) the output element of which is integral with the shaft52, is capable of:positively driving the second toothed element50, respectively in first and second angularly opposed directions, when the handle6is displaced by moving away from the position of rest N, respectively in one or the other of the first and second angular directions45,46,and not driving the second toothed element50, when the handle6is displaced towards the position of rest N.

As shown inFIG. 27, the housing of the pump device60can be fixed to the second frame8of the hinge mechanism.

Further, as shown inFIG. 28, the adjustment device10can be similar to that described previously in all the other embodiments of the invention, with the following differences:the first cam16has a symmetry of order3about the axis of rotation Y so as to be displaceable either in the first angular direction45, or in the second angular direction46, starting from its position of rest,the adjustment device10no longer comprises the springs21, the cam16being simply returned to its position of rest by one or more springs internal to the pump device60, the first cam16being coupled to the handle6for example by means of a rigid metal rod61which is integral with the control ring18and which extends parallel to the axis of rotation Y, passing through an opening61ain the form of a segment of a circle, centered on the axis of rotation Y and arranged in the second frame8, said rod61being inserted between the two times of a fork62integral with the handle6, said fork62delimiting a slit extending radially with respect to the axis of rotation Yl,and the cutouts19of the control ring18each comprise, in their outside edge, a central notch19aflanked by two portions19bof a smaller radius than the central notch, the first pin14of each first toothed element12being in correspondence with the central notch19awhen the adjustment device10is locked, as shown inFIG. 28.The hinge mechanism according to the sixth embodiment of the invention operates as follows: when a user displaces the handle6by moving it away from the position of rest N, this movement rotatably drives the control ring18using the fork62, so that the cam16no longer holds the first toothed elements12in locking position and the portions19bof the cutouts19act on the respective first pins14of the different first toothed elements12to displace said first toothed elements into the unlocking position.

Further, the movement of the handle6drives the second toothed element50rotatably about its axis of rotation Yl, which second toothed element in turn drives the first frame7rotatably about the axis Y using the additional set of gear teeth23(seeFIG. 29).

When the handle6is released by the user, it returns to the neutral position N under the effect of springs internal to the pump device60, without driving the second toothed element50but driving with it the first cam16and the control ring18which return to the position ofFIG. 28, returning the adjustment device10into locked position.

In the sixth embodiment of the invention, a hinge mechanism is thus obtained, controlled by a pump device and having an excellent mechanical strength thanks to the adjustment device10.

Of course, the hinge mechanism5according to the present invention could be used in applications other than the angular adjustment of a backrest.

Such a hinge mechanism can be used if required for example for controlling lifting mechanism allowing adjustment of the height and/or the angle of the seat base, or in any other application where it is desired to control a relative pivoting movement between two elements of a vehicle seat.