FR2886231A1 - Motor vehicle seat head rest has articulation system to allow angle adjustment relative to frame - Google Patents

Abstract

The head rest, having a frame with projecting legs for fitting it to a seat back and a cushion with a rigid structure, contains an articulation system (1) that allows the angle of the cushion to be adjusted. The system comprises and axle (2) with sets of friction rings (3) in two groups (4a, 4b) with a spring (6) between them and outer end stops (5). The alternate rings in each group are fixed (7) and rotating (8), the fixed ones being attached to the head rest frame and the rotating ones to the cushion structure by connectors (9, 10) so that one can be rotated relative to the other manually to provide a firm support for the user's head.

Description

The invention relates to a motor vehicle headrest.

  More particularly, the invention relates to a headrest comprising two parts articulated in rotation with each other, so as to allow its adjustment in comfort.

  It is known to produce rotationally articulated headrests comprising a backrest mounting frame and a headrest cushion provided with a rigid structure, said structure being rotatably associated with said armature by means of a articulation system so as to allow adjustment of the cushion.

  It is known, in particular from document EP-0 764 557, to use clamping systems of the metal clamp type, said clamp being associated with said structure and enclosing a cylindrical central metal part of said frame, so as to allow rotation said structure around said cylindrical portion.

  Such systems are applied for example on bell-type or D-type headrests. In a bell-type headrest, as described, for example, in US Pat. No. 6,634,715, the cushion structure is formed. a housing housing the upper part of the frame and the hinge system, said housing having a lower opening so as to be actuated in rotation relative to the frame.

  In a pallet headrest, as described for example in document FR-2 747 349, the cushion structure is formed of a pallet.

  In such headrests, when a clamp is used as a hinge system, the frictional torque between the clamp and the cylindrical portion is set to allow manual rotation of said cushion by the user while providing a firm support to the user's head when it is supported on said cushion.

  It is found that such systems are of uncertain reliability in use, in particular because of the dimensional dispersions of the clamp and / or the cylindrical portion. These dispersions cause very large fluctuations, of the order of 30%, in the friction torque, and all the more so as the friction surface between the clamp and the cylindrical portion is small. This results in a difficult manual rotation, resulting in adjustment difficulties, or a lack of firmness support for the head of the user.

  The invention aims to overcome this disadvantage by providing a headrest provided with a hinge system to ensure good control of the friction torque.

  For this purpose, the invention proposes a motor vehicle headrest comprising: E a mounting frame to a backrest, É a headrest cushion comprising a rigid structure, said structure being associated in rotation with said armature by means of a hinge system so as to allow adjustment of the cushion, said system comprising: E a cylindrical axis, É a plurality of washers threaded on said axis, said washers 25 forming at least one set of adjacent washers, E stop means disposed on either side of said axis, arranged so as to maintain said axis in said washers, E at least one resilient biasing means interacting with said washers being arranged so as to dispose said washers of one and the same set in successive support against each other, said washers of the same set being alternately fixed and movable in rotation, said fixed washers being associated with said and said movable washers being associated with said structure, said resilient biasing means being arranged to allow manual rotation of said cushion by the user while providing firm support for the user's head when in support on said cushion.

  In this description, the positioning terms in the space (upper, lower, transverse, ...) are taken in reference to a seat-mounted headrest.

  In such an embodiment, the friction torque is induced by the friction between the successive washers. The parameters controlling the friction torque are the friction surface between the fixed and moving washers, itself a function of the total number of washers, the force exerted by the elastic stressing means and the friction coefficients of the washers between them.

  The friction surface involved in such an embodiment is considerably increased compared to that of the prior art. This results in a much finer control of the friction torque, and therefore a good control of the dispersions observed in the friction torque.

  Other features and advantages of the invention will appear in the description which follows, with reference to the attached figures in which: Figure 1 is a schematic perspective representation of a hinge system according to an embodiment of the invention. FIG. 2 is a diagrammatic perspective view of a headrest according to a first embodiment, provided with a hinge system according to the invention; FIG. 3 is a diagrammatic representation in perspective of a headrest according to a second embodiment, provided with a hinge system according to the invention, With reference to FIG. 1, an embodiment of a hinge system 1 intended to be arranged in a motor vehicle headrest comprising a backrest mounting frame and a headrest cushion, said cushion comprising a rigid structure.

  The structure is associated in rotation with the frame by means of the articulation system 1 so as to allow adjustment of the cushion, said system comprising: a cylindrical axis 2, É a plurality of washers 3 threaded on said axis, said washers forming two similar sets 4a, 4b contiguous washers 3, arranged on either side of the axis 2, this to ensure a symmetrical distribution of the masses in the headrest, E stop means 5 disposed of on either side of said axis, in the form of elastic rings, arranged so as to maintain said axis in said washers, E an elastic stressing means 6, in the form of a helical spring threaded on the axle and prestressed in compression, disposed between the assemblies 4a, 4b, in interaction with the washers 3 and arranged so as to arrange the washers 3 of the same assembly 4a, 4b in successive support against each other, the assemblies 4a, 4b being contained between the fate and stop means 5.

  The washers 3 of the same set 4a, 4b are alternately fixed 7 and 20 movable 8 in rotation, the fixed washers 7 being associated with the frame and the movable washers 8 being associated with the structure.

  The resilient biasing means 6 is arranged to allow manual rotation of the cushion by the user while providing firm support for the user's head when he bears against said cushion.

  In one embodiment, the friction torque is approximately 4.5 m.N. The outer diameter of the washers 3 is 25 mm and their internal diameter 8 mm, substantially equal to that of the axis 2. The coefficient of friction is 0.1, the washers 7, 8 being alternately based on polyoxymethylene and polyamide. The spring is compressed to 45 daN. The total number of washers is 20. To ensure optimum control of the value of the force exerted by the spring, the latter is advantageously compressed very significantly, for example to 30% of its length in the state free.

  According to the embodiment shown, the stationary washers 7, respectively movable 8, are provided with radial protuberances 9, respectively 10 arranged so as to form association means, similar to clips or hooks, with reciprocal means provided on the frame , respectively the structure. The association is provided with a slight transverse clearance, so as to allow a slight movement of the washers 3 along the axis 2, so that the compressive force of said washers between them is defined only by the force exerted by the means of stress 6, independently of the dimensional dispersions of said washers and their wear. The protuberances 9, 10 are derived from material during the molding of the washers 3.

  According to the embodiments of Figures 2 and 3, the headrest cushion is articulated in the upper part of the frame.

  According to the embodiment of FIG. 2, said bell-shaped headrest, the cushion structure is formed of a housing 11 housing the upper part of the armature 12, comprising two branches 12a, 12b interconnected in the upper part of the headrest so as to form a U, and the articulation system. The housing 11 has a lower opening 13 so as to be actuated in rotation relative to said frame. The housing 11 comprises, not shown, reciprocal association means accommodating the association means movable washers 8. The double arrow symbolizes the rotation around the axis indicated in dotted lines.

  According to the embodiment of FIG. 3, said pallet headrest, the headrest is provided with a frame similar to that of the headrest of FIG. 2, the cushion structure is formed of a pallet 14. the pallet 14 comprises, not shown, reciprocal association means accommodating the association means movable washers 8. As a variant not shown, the armature may comprise only one branch.

  Other variants may be proposed remaining within the scope of the invention, in particular relative to headrests whose articulation is located in the lower part.

  The hinge system according to the invention can thus be adapted to any type of headrest provided with a movable cushion in rotation.

Claims (7)

  A motor vehicle headrest comprising: a backrest mounting frame; a headrest cushion comprising a rigid structure; said structure being rotatably associated with said armature; means of a hinge system (1) so as to allow adjustment of the cushion, said headrest being characterized in that said system comprises: io ^ a cylindrical axis (2), É a plurality of washers (3) threaded on said axis, said washers forming at least one set (4a, 4b) of adjoining washers, E abutment means (5) disposed on either side of said axis, arranged so as to maintain said axis in said washers, E at least one resilient biasing means (6) interacting with said washers and arranged to dispose said washers of the assembly (4a, 4b) in successive support against each other, said washers of the assembly (4a , 4b) being alternately fixed (7) and movable (8) in rotation, said fixed washers being associated with said armature and said movable washers being associated with said structure, said resilient biasing means being arranged so as to allow manual rotation of said cushion by the user while providing firm support for the head of the user when he bears on said cushion.   2) Headrest according to claim 1, characterized in that the fixed washers (7), respectively movable (8), are provided with radial protuberances (9, 10) arranged to form means of association with means reciprocal provided on the armature (12), respectively the structure (11, 14), a transverse clearance being provided, so as to allow a movement of the washers (3) along the axis (2).   3) Headrest according to claim 1 or 2, characterized in that the constraining means (6) is in the form of a helical spring threaded on the axis (2) and prestressed in compression.   4) Headrest according to any one of claims 1 to 3, characterized in that the articulation system (1) comprises two sets (4a, 4b) of washers (3) respectively abutting against the stop means ( 5), the constraint means (6) being disposed between said assemblies.   5) Headrest according to any one of claims 1 to 4, characterized in that the cushion is articulated in the upper part of the armature (12).   6) Headrest according to claim 5, characterized in that the cushion structure is formed of a housing (11) housing the upper part of the frame (12) and the hinge system (1), said housing having a lower opening (13) so as to be actuated in rotation relative to said frame, said housing comprising reciprocal association means accommodating the association means (10) of the movable washers.   7) Headrest according to claim 5, characterized in that the cushion structure is formed of a pallet (14), said pallet comprising reciprocal association means accommodating the association means (10) of the movable washers.