Vehicle seat with adjustable lumbar support.

(74) Agent (s): Cabinet Plasseraud.

Improvements to the seats of vehicles with adjustable lumbar support.

(57) It is a vehicle seat with adjustable lumbar support which comprises an inextensible wire or cable 6 comprising at least one first extreme section 5 stretched horizontally across the backrest 2, in its portion providing lumbar support, a second end section 7 wound on a suitable drum 9 secured to a control handle 10 and an intermediate section 8 housed in a sheath 12 and connecting the two end sections.

FR 2 616 640 - Al

<img file="FR2616640A1_D0001.tif" />

»RiMooiMcniP ΝΔΤΙΟΝΑΙ F 27. rue de la Convention - 75732 PARIS CEDEX 15

Improvements to the seats of vehicles with adjustable lumbar support.

The invention relates to vehicle seats and more particularly to those of these seats, which are equipped with means for adjusting the degree of lumbar support of the persons seated on them.

In known seats of the genre in question, the adjustment considered generally uses a rotary cam capable of being controlled by a handle linked to this cam and this handle is mounted on the seat back, in the immediate vicinity of the cam.

These mechanisms have a certain number of drawbacks and in particular the high cost, the gradual deregulation due to the long-term slackening of the cushion portions which provide lumbar support, and above all the difficulty of use: indeed, access to the control handle is difficult for the person seated on the seat, so that this person is forced to place himself, during the adjustments, in a position for which his back is not pressing against the file, which does not allow him to immediately assess whether the settings made are correct.

The object of the invention is, above all, to remedy these various drawbacks.

To this end, the adjustment means of the kind in question are essentially characterized in that they comprise an inextensible wire or cable comprising at least a first extreme section stretched horizontally across the backrest, in its portion ensuring lumbar support and a second section. extreme wound on a suitable drum associated with a rotating control member.

In preferred embodiments, use is also made of one and / or the other of the following arrangements.

- the second extreme section is connected to the first (or to the first) by an intermediate section housed in a sheath,

- the first extreme sections are at least two in number, parallel and connected together in pairs by a semi-circular loop mounted so as to slide on a rigid guide itself mounted on the back frame,

- the drum and a control handle secured to this drum are mounted on the seat cushion in a place easily accessible to one hand of the person seated on the seat,

the drum is associated with means ensuring the irreversible control of the movements of the wire or cable wound on this drum,

- The wire or cable supports in its position of maximum insertion into the backrest a flexible sheet which is itself mounted resiliently on the back frame.

The invention includes, apart from these main provisions, certain other provisions which are preferably used at the same time and which will be more explicitly discussed below.

In what follows, a preferred embodiment of the invention will be described with reference to the attached drawing, of course in a non-limiting manner.

The single figure of this drawing very schematically shows an improved vehicle seat according to the invention.

This seat comprises a seat 1 and a backrest 2 itself comprising two parallel rigid arms 3 which are pivotally mounted on the seat around a horizontal transverse axis X.

The backrest 2 also comprises, in its lower zone corresponding to the support of the kidneys or lower back of the seated person, a flexible support which has been shown diagrammatically by the broken lines 4 and which is supported by at least a first section 5 of a wire or inextensible cable 6, 5 section extending transversely between the two back arms 3.

This first section 5 constitutes an extreme portion of the wire 6.

The opposite extreme portion 7 of this wire is rac10 strung to said section 5 by an intermediate section 8 and is wound around a drum 9 itself angularly linked to a rotary control handle 10.

The first section 5 could be unique, but it is preferably composed of n sections arranged pa15 parallel to one another along a surface substantially parallel to the carrying surface of the flexible support 4, the symbol &amp; a denoting an integer at least equal to 2 and generally at most equal to 5.

These different parallel sections are keyed to each other by semi-circular loops bearing on appropriate guides 11, such as grooved half-pulleys, mounted on the arms 3.

In the embodiment which has been illustrated in the drawing, the number n is equal to 2.

The end of the assembly constituted by the extreme section (s) 5, which is the most elbowed from the remaining portion 7.8 of the wire, is hooked on the back arm 3 corresponding to in any desirable manner, for example by passing a hollow hole 30 in said arm through a hook 18 anchored on said end.

The intermediate section 8 is housed under a flexible sheath 12, but axially undeformable, sheath wedged between two fixed stops 13 and 14 mounted respectively on the seat 1 and on one of the arms 3 of the backrest 2.

Because it is possible to give the intermediate section 8 a great length, the handle 10 can be placed in a location relatively distant from the useful end 5, of the lumbar.

Thus, illustrated, the handle 10 wire 6, which provides support in the embodiment is directly mounted on the seat 1, in a location easily accessible by a hand of the person seated on the seat.

The drum 9 is associated with a blocking mechanism known per se, such as those designated by the names brake-housing or auto-lock, making irreversible the control of the rotations of said drum: in other words, if it is easy to control the windings and unwinds of the wire 6 on the drum 9 by rotating the handle 10, it is not possible to provide these same commands by acting directly on the wire, in particular by pulling on this wire.

The drum 9 can also be associated with electrical means for driving in rotation.

The operation of the mechanism described above is as follows.

Each angular position of the handle 10 defines a well-determined degree for the length and the tension of the end sections 5 of the wire 6, that is to say for the lumbar support provided by the seat.

In fact, the insertion of the flexible support 4 into the backrest is limited by the sections 5 in question, due to the non-extensibility of the wire 6 and the attachment of its two ends to fixed points of the seat.

If, from this situation, the person sitting on the seat wishes to reinforce the support effect exerted on his kidneys by the flexible support 4, he just has to rotate the handle 10 in the direction corresponding to the winding of the wire 6 on the drum 9, that is to say an increase in its tension or a shortening of its end strands 5. '

The support thus reinforced is then maintained after letting go of the handle 10 due to the automatic blocking of the wound wire. ''

On the contrary, if the lumbar support is too marked, it suffices for the seat user to turn the handle 10 in the opposite direction to the previous one.

In the drawing, the flexible support 4 placed at the level of the kidneys of the seated person is a tablecloth com10 posed by two semi-rigid rods 15 parallel to the arms 3 and by transverse parallel wires 16 stretched between these two rods, these latter being -same suspended from the arms 3 of the backrest by helical tension springs 17.

With such a variant, the inextensible wire 6 serves to limit the amplitudes of the deflections of the flexible sheet above:

when the seat user does not press his back against the backrest, said sheet is in an elastically floating position for which the sections of wire 5 are not stretched,

- On the contrary, the progressive support of the user's back against this sheet results in an increasing depression of the latter and it is the extreme limit of this depression which is limited by the wire 6 in its stretched state.

As a result of which, and whatever the embodiment adopted, a vehicle seat is finally obtained, the constitution, operation and advantages of which result sufficiently from the above.

As it goes without saying, and as already follows from the above, the invention is in no way limited to those of its modes of application and embodiments which have been more especially envisaged; on the contrary, it embraces all variants.