FR2606860A1 - Support mechanism for a member the position of which with respect to an axis it is desired to adjust - Google Patents

Abstract

Support mechanism for a member the position of which with respect to an axis 29 it is desired to adjust, characterised in that it includes a toothed rod 12 carrying the said member, a sheath 11 in which the rod is capable of sliding with a predetermined radial clearance 14, at least one locking boss 21, 34, 44 and at least one centring boss 20, 33, 43 which are associated with the sheath, these bosses interacting with elastic means 13, 41, 42 for constraining the sheath radially inwards so that the bosses are applied against the rod 12 and the locking boss becomes housed in one of the teeth 17 of the said toothed rod.

Description

 The present invention relates, in general, to a support mechanism for a member whose position it is desired to adjust along an axis.

 More precisely, the present invention proposes such a mechanism allowing manual step-by-step adjustment of the position of said member, with automatic locking and unlocking of the support of the member, constituted in this case by a rod, linked to a catching-up of radial clearance of said rod in a complementary housing.

 A particularly advantageous application of the present invention is that of adjusting the position of the head restraints on the seats of a motor vehicle.

 Known mechanisms for adjusting the position of a headrest have a number of drawbacks.

 First of all it is difficult to adjust the position manually. These mechanisms include for this purpose a notched device and it is necessary to exert a certain force in one direction or another to move the headrest so that either one does not exert a sufficient force and one cannot move the headrest, or, on the contrary, the instantaneous force is too high and the headrest is displaced by a number of notches greater than the desired number.

 In other mechanisms, to allow adjustment of the position of the headrest, it is necessary to unlock a locking member beforehand, which is sometimes awkward.

 In general, all known mechanisms are subject to unpleasant vibrations and very often to noises resulting, in particular, from these vibrations.

 The subject of the present invention is a support mechanism for a member whose position it is desired to adjust with respect to an axis, said member possibly being a headrest, free from the above drawbacks.

 To this end, the support mechanism according to the invention is particularly characterized in that it comprises a notched rod carrying said member, a sheath in which the rod is capable of sliding with a predetermined radial clearance, at least one locking boss and at least one centering boss associated with the sleeve, these bosses cooperating with elastic means of radial stress towards the inside of the sleeve so that the bosses are applied against the rod and the locking boss is received in one notches of said notched rod.

 Thanks to these provisions, and by applying the invention to the adjustment of a headrest, there is a mechanism for adjusting the position of this headrest which is particularly flexible to use, free from vibration and noise.

 Indeed, as the elastic means essentially have a radial action on the bosses towards the inside of the sheath, no force is exerted parallel to the axis of the notched rod.

 I1 follows that only a small effort, and therefore easily dosable, is necessary to move said notched rod along its axis, which overcomes the drawback mentioned above, namely the difficulty of adjusting the position of the head support.

But in addition the elastic means act on one or more centering and locking bosses, which has the effect of centering the rod, leaving a regular radial clearance, and of locking it inside the sheath, while having in addition the following advantages:
- the friction of the rod inside the sheath is reduced to the strict minimum, which makes manual adjustment of the rod position even easier,
- the elastic means cooperate with the various bosses to filter the major part of the vibrations,
the residual vibrations transmitted to the rod are of small amplitude, so that, due to the radial clearance, the rod does not vibrate against the inside of the sheath, which avoids the unpleasant noises mentioned above,
- It has been observed that when the notched rod is produced from a cylindrical rod on a generatrix from which "notches" of the notches, the rod undergoes deformations and the fluid material.

The - sonce of a radial clearance makes it possible to avoid friction caused by the deformation of the rod and the agglomerates of material at the level of the notches.

 According to a preferred embodiment of the present invention; the elastic means comprise a spring produced by means of a plastic or metal strip of shape complementary to the sheath, arranged outside the latter.

 The elastic means thus proposed are particularly simple and inexpensive. In addition, when the sheath and the strip spring are of cylindrical shape, it is easy to master the radial stress exerted by this type of spring, so while ensuring sufficient force against the locking boss, to thus guarantee a good locking of the mechanism, it is possible to prevent this force from being too great, which makes it even easier to adjust the position of the notched rod.

 In the preferred embodiment, and according to another characteristic of the invention, the bosses consist of balls. This embodiment is particularly simple to implement and the functions of said locking or centering bosses are, therefore, ensured in a fully satisfactory manner.

 However, in another embodiment, the bosses are an integral part of the sheath and are preferably carried by longitudinal blades formed in the sheath.

 Such an embodiment makes it possible to reduce the number of parts of the mechanism according to the present invention.

 It is the same in another variant embodiment of the present invention in which the elastic means comprise a cylindrical steel part carrying elastic longitudinal blades themselves carrying said bosses.

 In another embodiment of this variant, the sheath is constituted by the cylindrical piece of steel. Therefore, the mechanism according to the present invention no longer comprises, essentially, only two parts: a sheath assembly - elastic means, carrying the bosses and a notched rod.

The characteristics and advantages of the present invention will become apparent from the description which follows, with reference to the accompanying drawings in which:
FIG. 1 is a schematic view in partial elevation of a preferred embodiment of the present invention,
FIG. 2 is a partial elevation view of the notched rod of FIG. 1,
FIG. 3 is a sectional view along line III-III of FIG. 1,
FIG. 4 is a sectional view along the line IV-IV of FIG. 1,
- Figure 5 is a partial axial section along the line
VV of figure 4,
FIG. 6 is a perspective illustration of a sheath of another embodiment of the mechanism according to the present invention,
- Figure 7 is a longitudinal section along the line
VII-VII of Figure 6,
FIG. 8 is a perspective view of the elastic means used in this other embodiment,
FIG. 9 is a partial schematic view in longitudinal section of this other embodiment of the mechanism, the latter being mounted,
FIG. 10 illustrates, in perspective, the elastic means of another embodiment of a mechanism according to the present invention,
FIG. 11 is a partial longitudinal section of this other embodiment of a mechanism, the latter being mounted,
- Figure 12 is a view similar to Figure 11 and illustrates an alternative embodiment.

 According to the embodiment chosen and shown in FIG. 1, the support mechanism generally referenced in 10 essentially comprises a sheath 11, a notched rod 12, carrying a member such as a headrest, not shown, and elastic means constituted in this case by a spring 13 of the strip type.

 It is observed that these three elements are of generally cylindrical shape, the notched rod 12 being able to slide in the sheath 11 with a predetermined radial clearance, referenced in Figures 1 and 5 at 14. The strip spring 13 has a circumferential extension less than 3600 and an axial orientation opening formed in 15, FIGS. 3 and 4. This opening corresponds to a boss 16 for guiding the sleeve 11 which is engaged in said opening. The guide boss 16 therefore also has a substantially axial extension.

 Figure 2 illustrates the preferred embodiment of the notched rod. This rod is here made of steel. Notches 17 are spaced along a generatrix of the rod. In the embodiment shown, these notches are five in number and have a partially spherical shape. In another embodiment not shown, these notches can be constituted by a flat surface. Other forms of notches may be suitable.

 The sheath 11 has, in the vicinity of its upper end, three openings 18, arranged in a secant plane transverse to the axis 29 of the assembly, and regularly distributed over the circumference of the section. These openings have a generally frustoconical shape and allow communication between the interior volume of the sheath 11 and the exterior of this same sheath.

 Significantly below the secant median plane of the sheath 11 is an opening 19 similar to the openings 18 described above.

 In the embodiment chosen and shown, the openings 18, 19 are able to accommodate, partially, balls, three of the latter, called centering balls, being referenced at 20 and housed in the openings 18 which are then said, by convenience, centering openings. A ball 21, called a locking ball, is housed in the opening 19 which is then called, for convenience, a locking opening.

 It can be seen that the locking opening 19 has a substantially tapered cone shape than the centering openings 18, the small base of the cone trunk 19 being substantially larger in this opening than in the centering openings 18.

 We also observe; Figures 3 and 4, although the locking opening 19 is axially offset from the centering openings 18, the axis of the locking opening 19 is in a diametrical plane of the sleeve common to the axis of l 'one of the centering openings 18.

 The strip spring 13 has, at the locking housing 19, a stamping 22 so that the internal wall of the strip spring 13 curves substantially inward directly above the locking housing 19.

 The operation of the embodiment of the mechanism according to the invention presently described is as follows.

 Referring to Figure 5 where the mechanism is shown in partial axial section at the locking ball 21 and the locking housing 19, we see that the locking housing 19 has an axial extension corresponding substantially to the diameter of the ball delta locking 21. The latter in the normal position of the mechanism is snapped into one of the notches 17 of the rod 12. It is held in stress against this notch by the strip spring 13 and, more particularly, by the locking stamping 22 .

 The centering balls 20 come into contact with the external surface 24 of the rod 12. As explained above, the locking ball 21 is aligned on a diametrical plane of the mechanism common to one of the centering balls 20 and offset axially compared to these. Also the external surface 24 of the rod 12 is free of notches at the level of the centering balls 20. The latter are held in stress against the rod 12 by the strip spring 13 and the rod 12 is therefore self-centered , the radial clearance 14 therefore remaining almost evenly between the external surface 24 of the rod 12 and the internal surface 25 of the sleeve 11, FIGS. 1 and 5.

 The balls 20, 21 and the spring 13 have, in addition to their function of entry and locking, that of substantially filtering the vibrations to which the mechanism 10 may be subjected. The residual vibrations transmitted to the rod 12 then have an amplitude substantially less than the radial clearance 14 so that the external surface 24 of the rod 12 does not vibrate against the internal surface 12 of the sheath 11. The noise present in the mechanisms of the prior art is thus largely eliminated. In addition, the presence of vibrations of small amplitude on the rod 12 prevents them from vibrating strongly against other parts arranged between the sheath 11 and the headrest, not shown in the figures.

 It will be observed, however, that, in the embodiment described and shown, the single locking ball 21 is axially offset with respect to the centering balls. This locking ball can generate a very slight tilting of the rod 12 around an axis disposed in the plane carrying the centers of the balls 20, perpendicular to the direction of action of the ball 21.

 This tilting can create a weak contact between the rod 12 and an external part (in some cases the sheath 11). The residual vibrations of the rod 12 at the point of contact are insignificant and, in any event, clearly less noisy than in the prior art.

To avoid such a tilting it is possible to plan
- a second set of centering balls, axially offset from that shown in the figures,
- or a second locking ball diametrically opposite to that illustrated.

 It will also be noted that, if necessary, the radial clearance 14 makes it possible to compensate for any deformation of the rod 12 or a slight creep of material when striking the notches 17.

 When it is desired to change the position of the member carried by the rod 12 along the axis 29, it suffices to press or pull on this member by exerting a relatively weak force. At this moment, the movement of the rod causes the withdrawal of the locking ball 21 which spreads the spring 13. The rod 12 is then unlocked and slides tangentially on the ball 21 which falls by pressure into the next notch 17 and locks again because of this the mechanism.

 It will be noted that the angular position of the rod is kept constant so that the notches 17 come opposite the ball 21. Means are provided for this purpose and are; in this embodiment, arranged in the headrest which is here carried by two mechanisms 10.

 Finally, snap-fastening means 30 are here provided for fixing the mechanism 10 in a suitable housing at the top of the seat.

 As described in Figures 1 to 5, the mechanism according to the invention is susceptible to several variants.

 First of all the balls 20; 21 can be replaced by bosses, respectively called centering and locking, which can have any kind of shape. Advantageously, however, the shape of these bosses is; at least partially; spherical. It is the same for the shape of the notches.

 Furthermore; as explained in support of Figures 6 to it described below, these bosses can be an integral part of the sheath and even of the strip spring.

 It will also be noted that the elastic means acting on the balls or the bosses can take various forms; the strip spring 13 having been chosen here; shown and described as a preferred embodiment.

 We will also describe in support of Figures 6 to 11 two alternative embodiments. of a support mechanism according to the present invention. In these figures; the elements having a structure and a function similar to those described in support of FIGS. 1 to 5 retain the same references and will therefore not be described.

 In the embodiment shown in Figures 5 to 9; an island sheath comprises a series of elastic blades 31; 32. In the vicinity of the upper end of the sheath 11a; the elastic blades 31 carry centering bosses 33. These elastic blades 31 are then called "elastic blades supporting the centering boss'2.

 In the vicinity of the lower end of the island sheath; the elastic blade 32 carries a locking boss 34. Also the elastic blade 32 is said to be an "elastic blade supporting the locking boss.

Figure 7 illustrates in longitudinal section the structure of each boss assembly. It is observed that in this embodiment, the boss consists of two bulges, namely:
an internal bulge 35 having the function of either centering, as regards the bosses 33, or locking, as regards the bosses 34, and an external bulge 36 intended to cooperate with the sheath spring 13a illustrated in FIG. 8.

 It is observed that, therefore, the locking bosses 34 and centering 33 are an integral part of the pila sheath.

 The strip spring 13a illustrated in Figure 8 differs significantly from the spring 13 described in support of Figures 1 to 5. Thus it does not include locking stamping. This spring is produced from a metal sheet to which a cylinder shape has been given, the internal diameter of which corresponds substantially to the external diameter of the body of the sheath 11a (not including the thickness of the external bulges of the bosses 33, 34). The notch 15a is not intended to cooperate with a sleeve guide boss as in the embodiment illustrated in FIG. 4. Therefore, this notch does not need to have a precisely determined width .

 Advantageously, it follows that the spring 13a has a much simpler structure than the spring 13 described in support of FIGS. 1 to 5.

 FIG. 9 illustrates the operation of this variant. We recognize the rod 12 provided with notches 17 (four in this variant).

As explained above, the strip spring 13a has an outside diameter corresponding to that of the body of the island sheath so that the spring 13a acts on the external boss 36 and shifts the elastic blades 33, 34 radially inward. The internal bulge 35 of the boss 34 of the bolt lock fits into one of the locking notches 17 as before.

 As for the centering bosses 33; they play their role in the same way as the centering balls 20 described and illustrated in FIGS. 1 and 3.

 In the alternative embodiment illustrated in Figure lo; the sheath spring 13b is a generally cylindrical steel part provided with elastic tongues 41; 42.

 In the vicinity of the upper end of the part 13b; the three elastic tabs 41 carry bossaqes 43 of centraqe while in the vicinity of the lower end of the part 13b; the tongue 42 carries a bossaqe 44 of lock.

 In the rest position the tabs 41, 42 are inclined radially towards the inside of the part 13b.

 Figure 11 illustrates how this variant works.

 The tick 12 slides in a cylindrical sheath llb provided with lights 45 arranged opposite the tabs 41; 42. The part 13b is arranged radially outside the sheath 11b. The part 13b has an internal diameter corresponding to the external diameter of the sheath 11b.

 In FIG. 11, only the operation of the locking tab 42 is illustrated. The deformation of the tongues 42 radially inwards in the rest position is such that the boss 44 carried by this tongue 42 penetrates into one of the notches 17 of the notched tick 12 and thus ensures the locking of the mechanism.

 By exerting a pressure or a pull on the rod 12 upwards or downwards, the locking bpssaqe 44 is thus elastically separated radially outwards and; as in the embodiment shown in Figures 1 to 5; the notched rod 12 smooths tangentially on the locking boss 44 before the latter comes to lock in the next notch 17.

 Of course in the two alternative embodiments described in support of Figures 6 to îî; a radial clearance 14 is provided between the island sleeve or llb and the notched rod 12.

 It will also be noted that - in both of these embodiments, by providing for radial deformation towards the appropriate interior of the tongues 31, 32, 41, 42, these tongues are capable of fulfilling the function of the elastic means within the meaning of the present invention. In such a case, in the embodiment illustrated in Figures 6 to 9, the spring 13a does not have to be used.

 It is the same in the embodiment illustrated in Figures 10 and. 11 of scabbard llb. Thus in FIG. 12 the sheath spring lîc incorporates the elastic means constituted by tongues provided with bosses (only the locking tongue 42c is illustrated with its boss 44c).

 The mechanism according to the present invention then comprises only two parts: an assembly llc sheath - elastic means carrying the locking and centering bosses and a notched rod.

 Of course, the present invention is in no way limited to the embodiments described, but on the contrary covers any variant within the reach of the skilled person.

Claims (8)

 1. Support mechanism of a member whose position is to be adjusted relative to an axis (29); characterized in that it comprises a notched rod (12) carrying said member, a sheath (11) in which the rod is capable of sliding with a predetermined radial clearance (14), 8U less locking boss (21, 34,44 ) and at least one centering boss (20, 33, 43) associated with the sleeve, these bosses cooperating with elastic means (13, 41, 42) of radial stress towards the inside of the sleeve so that the bosses are applied against the rod (12) and that the locking boss is received in one of the notches (17) of said notched rod.  2. Mechanism according to claim 1, characterized in that the elastic means comprise a strip type spring (11), of shape complementary to the sheath (11), disposed outside of the latter.  3. Mechanism according to any one of claims 1, 2; characterized in that the sheath (island, llb) comprises elastic blades (31, 32, 41, 42) each carrying at least one boss (33; 34, 43, 44).  4. Mechanism according to claim 3, characterized in that said elastic blades (41, 42) constitute, at least partially, said elastic means.  5. Mechanism according to any one of claims 1 to 4, characterized in that it comprises at least two centering bosses (20, 33, 43) distributed, in a plane transverse to the axis of said rod, uniformly on the periphery of the sheath.  6. Mechanism according to any one of claims 1 to 5, characterized in that said bosses consist of balls (20, 21).  7. Mechanism according to any one of claims 1 to 5, characterized in that the bosses (33, 34, 43, 44) are part intes * ^ te of the sheath (island, llb).  8. mechanism according to any one of claims 1 to 7, characterized in that said elastic means (42c) are an integral part of the sleeve (llc).