FR2938475A1 - Seat for motor vehicle, has locking mechanism for authorizing movement of base, control unit for placing another locking mechanism in unbolted state, and locking hook assembled on one part of translational body - Google Patents

Abstract

The seat has a first locking mechanism for authorizing movement of seat base, and a second locking mechanism for authorizing movement of a rotary backrest. A third locking mechanism authorizes relative movement of two parts (29, 30) of a translational body. The third locking mechanism is automatically placed in its unlocked state in an inclined position of the seat base with respect to a base (11), where the inclined position being intermediate between two positions of seat during its rotation.

Description

VEHICLE SEAT. The present invention relates to vehicle seats.

More particularly, the invention relates to a motor vehicle seat comprising: a base adapted to be fixed to the floor, a seat adapted to receive a seat occupant, the seat being rotatably mounted relative to the base around a seat; axis of rotation, between a first position in which the seat extends horizontally, and a second position in which the seat extends vertically, - a first locking mechanism adapted to take alternately a locked state in which it prohibits a movement of the seat relative to the base between its first and second positions, and an unlocked state, in which it authorizes said movement, - a backrest adapted to receive the back of an occupant, the backrest being rotatably mounted on the sitting around an axis of folding between a nominal position in which an occupant can take place in the seat, and a folded position in which the file goes out nd parallel to the seat, - a second locking mechanism adapted to take alternately a locked state in which it prohibits movement of the backrest relative to the seat between its nominal and folded positions, and an unlocked state, in which it authorizes said movement, a second control member adapted to be placed by a user in an active state in which he places the second locking mechanism in its unlocked state. For example, FR 2 779 688 describes such a seat element, which is very satisfactory.

Furthermore, it will be noted that, in the nominal position of the seat, in this document, the longitudinal position of the seat is adjustable relative to the floor with slides.

The modularity of seats has become a major selling point for motor vehicles. The seats must make it possible to implement different storage possibilities, regardless of the interior volume of the vehicle. It is thus sought to allow such types of seat elements to be used in a larger number of types of motor vehicles. For this purpose, according to the invention, a seat of the type in question is characterized in that the seat comprises: a structure adapted to receive a seat occupant, - a translation member comprising a first portion mounted on the structure, and a second part mounted on the base, the first and second parts being mounted movable relative to each other according to a degree of freedom of translation, - a third locking mechanism adapted to take alternately a locked state in which it prohibits a relative movement of the first and second parts according to the degree of freedom of adjustment, and an unlocked state, in which it authorizes said movement, - the seat being shaped to automatically place the third locking mechanism in its unlocked state in an inclined position of the seat relative to the base, said inclined position being intermediate between the first and second po sitions of the seat during its rotation around the axis of rotation. Thanks to these provisions, it introduces an additional degree of translation during the rotation of the seat between its horizontal and vertical positions, which facilitates the use of such seat elements, especially in small footprints. In preferred embodiments of the invention, one or more of the following arrangements may also be used: the seat structure extends substantially from a rear end, adapted to receiving the pelvis of an occupant at an opposite forward end along a longitudinal direction, and the axis of rotation is at the forward end; the seat comprises a third control member adapted to place the third locking mechanism in its unlocked state, in which the third control member is secured to the second part of the translation member, and the third control member places the third locking mechanism in its unlocked state in the inclined position; the seat further comprises: a fourth locking mechanism adapted to take alternately a locked state in which it holds together the second part of the translation member and the base, and an unlocked state, in which it releases the second part; the translation member of the base, a fourth control member adapted to be placed in an active state in which the fourth locking mechanism is in its unlocked state; the third locking mechanism comprises: a locking hook movably mounted on the first part of the adjustment member; a complementary locking member, integral with the second part of the adjustment member via the fourth locking mechanism, the locking hook and the complementary locking member cooperating in the locked state of the third locking mechanism to hold together said first and second parts, and no longer cooperating together, in the unlocked state of the third locking mechanism for releasing said first and second parts from each other, the fourth locking mechanism comprises: a locking hook movably mounted on the second part of the adjustment member, a complementary locking member , secured to the base, the locking hook and the complementary locking member cooperating in the t locked the fourth locking mechanism to retain together said second part and the base, and no longer cooperating together, in the unlocked state of the fourth locking mechanism to release said second part and the base from each other, l complementary locking member of the third and fourth locking mechanisms are the same common member; the first locking mechanism is mounted directly on the structure; and the seat comprises a first control member adapted to be placed by a user in an active state, in which he places the first locking mechanism in its unlocked state. Other features and advantages of the invention will become apparent from the following description of one of its embodiments, given by way of non-limiting example, with reference to the accompanying drawings. In the drawings: FIG. 1 is a schematic side view of an interior vehicle part comprising a seat according to one embodiment, in nominal position; FIG. 2 is a detailed perspective view of the seat of FIG. 1 is a partially sectional plan view along the line III-III of FIG. 4, of an exemplary reclining reclining locking mechanism, FIG. 4 is a partially sectional view according to FIG. IV-IV of Figure 3 of the mechanism of Figure 3, - Figure 5 is a sectional view of an example of locking mechanism of the rear part of the seat 10 to the floor, - Figures 6a and 6b are views in opposite perspectives of a translation member in the nominal position of the seat, - Figure 7 is a detail view in section of Figure 6b, - Figure 8 is a view corresponding to Figure 2 of the seat of FIG. 2 in a second position of the seat, FIGS. 9a and 9b. have views corresponding to FIGS. 6a and 6b in the second position of the seat. In the different figures, the same references designate identical or similar elements. Figure 1 shows a seat 1 of a motor vehicle adapted to receive one or more occupants, 25 and mounted on a chassis 2 of a motor vehicle. Such a seat can be mounted in various orientations in the vehicle, the front, rear, left, right and other orientation terms relating to the seat in the description referring only to the orientation of the seat itself, regardless of the orientation of the seat in the vehicle. For example, the seat 1 considered is a second-row seat, located behind another seat 3 of a so-called intermediate or front row comprising the driver's seat.

According to the embodiment shown in Figure 1, in its nominal position in which an occupant classically takes place in the seat, the seat 1 has a backrest 6, a front face 6a is intended to receive the back of the occupant. As can be seen in particular in FIG. 2, the backrest conventionally consists of a rigid frame 7, for example a metal frame, carrying a flexible padding 8, such as, for example, a polyurethane foam (shown in phantom lines). The armature 7 may for example be made in the form of a frame having two lateral arms 12a, 12b, parallel extending substantially vertically, and interconnected by an upper rail 18 and a lower rail 19.

Each side arm 12a, 12b, in the example shown, can be nested and fixed in a corresponding side flange 20a, 20b extending substantially in the same direction. Returning now to Figure 1, the backrest 6 is rotatably mounted on the seat 10 about a first axis of rotation X1. This rotary assembly can be done by means of an inclination locking mechanism 17 of any known type such as for example described later in connection with FIGS. 3 and 4.

The seat also comprises a seat 10 having an upper face 10a adapted to receive the pelvis and the legs of the occupant. The seat 10 extends from a rear end 4 to a front end 5 in a longitudinal direction Z. At the rear end 4, it is mounted on the backrest 6, pivoting relative to the backrest about the axis of the seat. rotation X1. As can be seen in FIG. 2, the seat may also be in the form of a structure comprising a rigid frame 21, for example a metal frame, carrying a flexible pad 22 (shown in phantom lines) of polyurethane or other type. The seat frame 21 may for example be made in the form of a stretcher comprising two lateral arms 23a, 23b connected together by a rear crossmember 24 and a front crossmember 25, and by a horizontal bottom 26, for example made in the form of a shaped flat plate, extending from one side arm to the other, and disposed between the rear cross member 24 and the front cross member 25. As can be seen in Figure 2, the mechanism of locking 17 is for example arranged between the lower part of the lateral flange 20a of the backrest and the rear portion of the lateral arm 23a of the seat. This locking mechanism 17 can take an active state in which it prohibits a rotation of the backrest 6 relative to the seat 10 around the axis XI. This locking mechanism 17 can be placed, by a user actuating an unlocking control 16 (Figure 1) in an inactive state in which it allows the rotation of the backrest 6 relative to the seat 10 about the axis XI. It is possible to arrange a similar locking device between the lateral flange 20b of the backrest and the side arm 23b of the seat on the opposite side of the seat and to provide that the control 16 makes it possible to simultaneously place these two locking mechanisms in their inactive state. .

At the front, the seat 10 is mounted on a base attached to the floor. This base comprises two front feet 11. At the front end, the seat frame 21 is slidably mounted relative to the front foot 11 in a sliding direction C by means of translation members 27, which will be described in greater detail hereinafter with reference to FIGS. 6a and 6b. Each translation member 27 comprises a locking mechanism 31 provided to take alternately an active state in which it prohibits a sliding along the direction C, and an inactive state in which it allows such sliding. There is only one state of the translation member where the locking mechanism is in its active state. The locking mechanism is placed in its inactive state automatically by the forward rotation of the seat. At the front end, the seat is also pivotally mounted on the front foot 11 around a second axis of rotation X2. This rotary assembly is here carried out by means of bearings carried by the two translation members 27. The rear end of the seat 10 is fixed on the frame 2 in a releasable manner by means of a locking mechanism 9 , which will be described in more detail below with reference to FIG. 5. Such a locking mechanism may take alternatively an active state in which the rear of the seat 10 is held integral with the frame 2. Alternatively, for example under the effect of the control of a user operating a release control 15 (Figure 1), the locking mechanism 9 can take an inactive state in which it releases the back of the seat 10 of the frame 2. According to others connections of the seat to the frame, this release can be total or partial, in which case it allows a movement of the seat 10 relative to the frame 2 according to a degree of freedom, as is the case in the present mo of realization. Alternatively, the locking mechanism 9 can be placed in its inactive state automatically by rotating the backrest relative to the seat. Furthermore, the seat 10 is releasably mounted on the front foot by means of a locking mechanism 44 which will be described in detail below, in connection with Figure 6b. This locking mechanism 44 can take an active state in which it maintains the seat 10 on the front foot 11, the seat 10 being however free to rotate relative to the front foot about the axis X2. The locking mechanism 44 may alternatively take an inactive state in which it does not retain the seat 10, so that it can be released completely from the frame 2. The locking mechanism 44 can be placed in its inactive state by a control member 45 suitable. The seat 1 of this first embodiment has a folding control member 14 such as, for example, a handle located on one side of the backrest, and adapted so that the user can, by actuating, bring the seat in a folded position in which the backrest extends substantially parallel to the seat. This crimping control member 14 is part of a crimping control system, for example cable, for transmitting the control of the folding of the occupant to the locking mechanism 17. Where appropriate, according to the characteristics of the mechanism of tilt lock, the seat 1 may also have a tilt adjustment control member 16 such as, for example, a handle located directly on the tilt lock mechanism 17, and adapted so that the user can, by actuating it, adjust the inclination of the backrest relative to the foot in a so-called inclination comfort angle angular zone in which it can take place in the seat. Where appropriate, if appropriate, the same member serves as tilt adjustment control member and tilt control member, the two functions being differentiated by different positions or operating directions different from the organ. An illustrative example of a tilting lock mechanism 17 is described below in connection with FIGS. 3 and 4. As shown in FIGS. 3 and 4, the tilt lock mechanism 17 comprises: a first flange 101 said base which is fixed on the lateral seat arm 23a, - a second flange 102 said mobile, fixed on the side flange 20a of the backrest, and which pivots about the first axis of rotation X1, the fixed and movable flanges together forming a round housing, and the movable flange 102 having a circular toothing 103 oriented radially inwards and arranged inside the housing, - a sheet metal ring 104 which is crimped on the periphery of the fixed flange 101 and which partially covers the flange mobile 102 to close the housing and maintain the periphery of the two flanges against each other, - three metal grains 105 (a single grain being shown in Figure 2) each provided with an external toothing the three grains being guided in radial sliding in guide grooves 107 formed in the fixed flange, the sliding directions of the three grains being shifted mutually by 120 degrees around the inner flange. X1 axis, - a cam 108, rotatable about the axis XI and acting on the three grains 105, this cam being angularly movable between, on the one hand, a rest position where it pushes the grains to a locking position for which the external teeth 106 of the grains cooperate with the internal toothing 103 of the mobile flange thus blocking said movable flange, and secondly, an unlocking position for which said cam allows the grains 105 to move back to an erased position for which their external teeth are disengaged from the internal toothing of the mobile flange, - three springs 109, here constituted by winding blades spiral, which angularly bias the cam 108 to its angular position of rest corresponding to the locking of the joint (springs of which only one has been shown in Figure 3), and a shaft 110 of axis XI integral with the cam 108 and linked to the crutch control handle 14. In addition, there is provided on each grain 105 a pin 112 projecting on the grain in the direction of the axis X1, and is made integral with the movable flange 102 a track 111 to the projections surrounding the pins 112 (shown in phantom lines in FIG. 3), comprising circular arcs A and B of different diameters centered on the axis X1, the diameters of the arches A and B being determined so that: a section A of larger diameter is opposite a pin 112, the latter, and therefore the corresponding grain 105, can describe the totality of its radial stroke (see FIG. 3), and that, on the contrary, when a smaller diameter section B is in With regard to such a pin 112, after sufficient relative angular displacement of the track 111 and the pin 112 about the axis XI (due to the rotation of the backrest), said pin 112 is radially in abutment on said section B in FIG. its unobstructed position, the closest to the axis X1, corresponding to the unlocking of the joint. This measurement makes it possible to keep the grains 105 in their unlocked unlocking positions, even if the user releases the handle 14 as long as the backrest is in an inclined position such as a portion of an arc B of the track 111 is located radially opposite each of the pins 112.

The angular positions in question of the backrest are defined in an angular zone for which it is desired that the joint remains unlocked, and correspond, for example, to folding the backrest forward to the tablet position. The section A defines the angular zone of tilt adjustment. In addition, there is provided on each grain 105 a second pin 113 protruding on the grain in the direction of the axis X1, and is made integral with the cam 108 a thin plate 114 recessed by lights 115 each traversed by one second lumens 113. Each lumen 115 is elongated circumferentially about the axis XI and its edge farthest from this axis has a projection in that it comprises two circular arcs D and E of different diameters connected to each other by an oblique ramp R. The diameters of the arches D and E are determined so that: - when the arc D of larger diameter is radially opposite the corresponding pin 113, it is free to describe the whole of its radial stroke, and that, on the contrary, when the arc E of smaller diameter is opposite the pin, this arc is then applied radially against this pin and holds it in its position closest to the axis corresponding to the unlocking d e articulation. Thanks to the obliquity of the ramp R, a simple rotation of the plate 114 allows, by sliding the pin 113 against this ramp, positively move it to its unlocked position. Figure 5 now shows an example of a locking mechanism 9 for connecting the rear end of the seat to the frame. This locking mechanism is shown here purely for illustrative purposes, and any other type of suitable locking mechanism could also be used in the context of the present invention. It will therefore be recalled that such a locking mechanism may, according to the example shown, before fixing the seat 10 to the floor 2, be in the form of a substantially cylindrical body 32 fixed on the bottom 26 of the seat. Before fixing the seat on the floor, an internal spring (not shown) pushes a control rod 35 into contact with a plurality of balls 36 held in an inactive position inside the cylindrical casing of the body 32. a cylindrical ring 37, itself urged by an external spring 34. Upon insertion of the body 32 into a cylindrical opening of the floor, of a size corresponding to the diameter of the body 32, the ring 37 is removed by compressing the spring 34 and the balls 36 are biased outwardly of the body 32 by the downward displacement of the control rod 35 biased by the internal spring. The balls 36 are however retained by the body 32 because they have a diameter too large to be able to fully exit the recesses formed for their effect, and engage under the lower surface of the floor, to prevent vertical movement upward of the sitting 10 in this active position. The tilt control handle 15 is connected to the control rod 35 to move it up against the biasing of the inner spring, to unlock the locking mechanism 9. The balls 36 are then free to retract inside the body, and the body 32 to be removed from the floor 2 by a vertical movement upwards. A translation member 27 is shown in detail in Figures 6a and 6b. The translational member 27 is for example made in the form of a rail comprising a first profile 29, permanently fixed on the front cross member 25 of the seat, and a second profile 30, of complementary shape of the first profile 29, and adapted to slide relative to that along a longitudinal sliding direction C. For example, the longitudinal sliding direction C is substantially aligned with the rear-front direction of the seat. A locking mechanism 31 is provided to alternatively prohibit relative sliding of the first 29 and second 30 profiles along the sliding direction C, in an active state, or, in an inactive state, to allow such sliding. By way of non-limiting example, the locking mechanism 31 may for example be made by a hook 32 having a connecting portion 35 by which it is movably mounted on the first section 29, for example rotatable relative to the first section 29 around an axis parallel to the axis X1. The hook 32 may further comprise a hooking portion 36 which, in the active position of the hook cooperates with the front foot 11 to prevent sliding and, in the inactive position of the hook, is disengaged from the front foot 11. The hook can also include an actuating portion 38 which controls the rotation of the hook 32 about its axis relative to the first profile 29.

The hook 32 is biased in its active state, shown in Figure 6a, by a spring, not visible in Figure 6a (for example a spiral spring disposed between the hook 32 and the first section 29 in Figure 6a).

Around the hooking portion 39 of the front foot 11, the first section 29 forms a step 40 which partially surrounds this attachment portion 39 (see Fig. 6b). A control bar 41 is facing the actuating portion 38 of the hook 32 in the nominal position of the seat shown in Figures 6a and 6b.

This control bar 41 is secured to the front foot 11 in the example shown. Referring to Figure 6b, we will now describe the locking mechanism 44 of release of the front of the seat of the frame. This may for example be in the form of a hook 42 rotatably mounted on the second section 30 in a connecting portion 43 about an axis of rotation parallel to the axis X2. The hook 42 also comprises a hooking portion 46 which surrounds from the top the hooking portion 39 of the front foot 11. The hook 42 also comprises a control pin 45 adapted to rotate the hook 42 about its connecting axis relative to the second profile 30. A return spring, not shown, biases the hook 42 in its position shown in FIGS. 6a and 6b, referred to as active state, in which the hooking portion 46 of the hook cooperates with the portion hooking 39 of the front foot 11 to prohibit the release of the second section 30 relative to the front foot 11. Furthermore, the second profile 30 comprises a guide flange 47 comprising a guide portion 48 of substantially complementary shape to the portion of the hooking 46 of the hook 42, and which grips at the bottom the hooking portion 39 of the front foot 11, so that the hooking portion 46 of the hook and the guide portion 48 together form a n compensate for the rotation about the axis X2 of the second profile 30 relative to the front foot 11.

The seat just described works as follows. The nominal position of use of the seat has already been described above with reference to FIG. 2. In this nominal position of the seat, both the backrest and the seat are in a so-called nominal position. All locking mechanisms are in their active state. For a comfort setting of reclining the backrest in the comfort adjustment range, the occupant actuates the handle 16 so as to unlock the reclining locking mechanism 17. The backrest 6 is then free to rotate relative to the 10. Upon reaching the desired position, the occupant releases the handle 16 and, subject to always being in the comfort adjustment range (arc A) of the tilt lock mechanism 17, the latter resumes its position. locked. When the user wishes to place his seat in said tablet position, he actuates the folding handle 14, which causes the unlocking (placement in idle state) of the tilting lock mechanism 17. The user is then free to rotate the backrest 6 forward relative to the seat 10 of the nominal position to a folded position. In the folded position, or shelf (not shown), the backrest 6 extends substantially horizontally and / or parallel to the seat 10 and / or parallel to the floor of the vehicle. The seat can be returned to its nominal position by a reverse movement. In the tablet position, the user is free to operate the tilt control member 15 (control, which, alternatively, can be automatic in a predetermined position of the backrest, for example the tablet position or an intermediate position between the nominal positions and tablet), so as to place the locking mechanism 9 in its inactive state. Note that alternatively, the tilt control member 15 could be operable by a user in the nominal position of the folder. In all cases, the rear portion of the seat 10 is released from the floor 2, and the seat 10 is no longer retained on the floor 2 by the free rotational mounting of the seat on the front foot 11 around the X2 axis. The user is then free to initiate a rotation of the seat relative to the floor 2 about the axis X2, so that the rear portion 4 of the seat rises upward towards a position called FIG. 8. During this rotation, the translation members 27 rotate around the axis X2 relative to the front legs 11 and, consequently, the hooks 32 carried by the fixed profiles 29 also start such a rotation. . Since the control bar 41 remains, in turn, fixed on the frame, in an intermediate inclined position of the seat, the control bar 41 cooperates with the actuating portion 38 of the hooks 32 to cause the rotation of the hooks 32 relative to the first sections 29 around their connecting portion 35, until placing the hooks 32 in their inactive state, that is to say that the hooking portion 36 of the hooks 32 is disengaged from the portion of hooking 39 of the front legs 11. This takes place simultaneously for the two hooks 32. Thus, the control bar 41 is automatically placed in an active position relative to the seat, by means of the displacement of the seat relative to the control bar 41.

This locking mechanism is now in its inactive state, the adjustment member 27 allows the sliding of the first section 29 relative to the second section 30 along the sliding direction C, moving the seat frame away from the frame , during the continuous rotation of the seat around the axis X2. This rotation is therefore, at this stage, guided by the guide portion 48 of the second profile 30 and by the hooking portion 46 of the hook 43, forming together a rotation bearing. A spring (not shown) of assistance can be used to urge the first section 29, and the rest of the seat structure backwards and upwards relative to the second profile 30, during this movement. Note that, in the example presented, there is no other relative position of the first and second profiles of the translation member in which its locking mechanism can take an active state that their position in the nominal position of the seat. Figure 8 thus shows the seat in its position wallet, where the seat extends vertically, its upper face 10a facing the front seat. Figures 9a and 9b show in detail the state of the translation member 27 in the wallet position of Figure 8.

At this point, to return the seat to the previous position, simply slide along the sliding direction the first section 29 on the second section 30 against the bias of the assistance spring, until recreating the hook 32 on the attachment portion 39 of the front foot 11. Starting from the position of Figures 8 and 9a, 9b, it is alternatively possible to completely release the seat floor 2 of the vehicle by placing the locking mechanism 44 in its state inactive. For this, the user can simply manually actuate the control pin 45 of each of the hooks 42, so as to rotate the hook 42, around its connecting portion 43, relative to the second section 30, to its active position, not shown, wherein the attachment portion 46 is released from the attachment portion 39 complementary to the front foot 11. The seat can then be removed completely from the vehicle. The seat can be reinserted into the vehicle by an opposite movement of the hook 42.35

Claims (7)

REVENDICATIONS1. Motor vehicle seat comprising: a base (11) adapted to be fixed to the floor; - a seat (10) adapted to receive a seat occupant, the seat being rotatably mounted relative to the base around an axis of rotation (X2), between a first position in which the seat extends horizontally, and a second position in which the seat extends vertically, - a first locking mechanism (9) adapted to take alternately a locked state wherein it prohibits a movement of the seat (10) relative to the base (11) between its first and second positions, and an unlocked state, in which it authorizes said movement, - a backrest (6) adapted to receive the back of an occupant, the backrest (6) being rotatably mounted on the seat (10) around a folding axis (X1) between a nominal position in which an occupant can take place in the seat, and a folded position in which the folder (6) extends parallel to the seat (10), - a second locking mechanism (17) adapted to take alternately a locked state in which it prohibits a movement of the backrest (6) relative to the seat ( 10) between its nominal and folded positions, and an unlocked state, in which it authorizes said movement, a second control member (14) adapted to be placed by a user in an active state in which he places the second locking mechanism in its unlocked state, characterized in that the seat comprises: - a structure (21) adapted to receive a seat occupant, a translation member (27) comprising a first portion (29) mounted on the structure, and a second portion (30) mounted on the base, the first and second parts being movably mounted relative to each other by a degree of freedom of translation (C), a third locking mechanism (31) adapted for alternatively take a locked state in which it prohibits a relative movement of the first and second parts (29, 30) according to the degree of freedom of adjustment, and an unlocked state, in which it authorizes said movement, - the seat being shaped to place automatically the third locking mechanism (31) in its unlocked state in an inclined position of the seat (10) relative to the base (11), said inclined position being intermediate between the first and second positions of the seat during of its rotation around the axis of rotation. 2. Seat according to claim 1, wherein the seat structure (21) extends substantially from a rear end, adapted to receive the basin of an occupant, at an opposite front end, along a direction longitudinal (Z), and wherein the axis of rotation (X2) is at the front end. Seat according to any one of the preceding claims, comprising a third control member (41) adapted to place the third locking mechanism (31) in its unlocked state, in which the third control member (41) is integral with the second part (30) of the translation member, and wherein the third control member (41) places the third locking mechanism in its unlocked state in the inclined position. The seat as claimed in any one of the preceding claims, further comprising: a fourth locking mechanism (44) adapted to alternately assume a locked state in which it holds together the second portion (30) of the translation member and the base (11), and an unlocked state, in which it releases the second part of the translation member of the base, a fourth control member (45) adapted to be placed in an active state in which the fourth mechanism of lock is in its unlocked state. The seat element according to claim 4, wherein the third locking mechanism (31) comprises: a locking hook (32) movably mounted on the first portion (29) of the adjustment member, - a complementary member locking device (39) secured to the second part of the adjustment member (30) via the fourth locking mechanism (44), the locking hook and the complementary locking member co-operating in the state locked the third locking mechanism to retain together said first and second parts, and no longer cooperating together, in the unlocked state of the third locking mechanism to release said first and second parts from each other, wherein the fourth locking mechanism (44) comprises: a locking hook (42) movably mounted on the second portion (30) of the adjusting member, a complementary locking member (39), secured to the base (11), the locking hook and the complementary locking member cooperating in the locked state of the fourth locking mechanism to hold together said second part and the base, and no longer cooperating together, in the state unlocked from the fourth locking mechanism to release said second portion and the base from each other, wherein the complementary locking member (39) of the third and fourth locking mechanisms are the same common member. Vehicle seat according to any one of the preceding claims, wherein the first locking mechanism is mounted directly on the structure (21). Vehicle seat according to one of the preceding claims, further comprising a first control member (15) adapted to be placed by a user in an active state in which he places the first locking mechanism (9) in its state. déverrouillé.15