Height adjustment device for a support rod of a headrest for motor-vehicle seats

Abstract: Height adjustment device for a support rod (R) of a headrest for motor-vehicle seats comprising a sleeve (2) having an enlarged hollow portion (3) in which an annular locking slider (9) is displaceable, incorporating a metal pin (12) for engagement, under the action of a thrust spring (19), of positioning notches (T) of the support rod (R) slidably fitted through the sleeve (2).

Description: The present invention is generally related to headrests for motor-vehicle seats, and is more particularly concerned with a height adjustment device for a support rod of such a headrest, the support rod having a row of positioning notches. From FR-A-2.671.587 an adjustment device for headrests is known, comprising a sleeve through which the support rod is axially slidably fitted and having an enlarged hollow portion in which an annular locking slider of moulded plastics material having a push button is displaceable perpendicularly to the support rod and adapted to cooperate, under the action of resilient thrust means, with said positioning notches so as to prevent displacement of the support rod relative to the sleeve. In this known solution the annular slider is integrally formed with a transverse element which constitutes a stop member cooperating with the positioning notches of the support rod. The resilient thrust means of the slider are also integrally formed therewith, and are constituted by an arcuate resilient arm. This arrangement, while on one hand has the advantage of being constructively simple and constituted by a reduced number of components, on the other hand is not capable of performing restraint of the support rod in a stable and safe way and without plays which may generate headrest vibrations. Additionally, the structure of the slider with the push button is relatively weak and may involve the risk of breakage, particularly as far as the integral transverse member, cooperating with the positioning notches of the support rod, is concerned. EP-A-0165593 and DE-A-3437803 disclose a height adjustment device having the features contained in the pre-characterising portion of claim 1 and comprising a locking slider which incorporates a U-shaped metal element whose ends are engaged with the slider and whose central section acts as an engagement member with the positioning notches of a support rod. In the solutions shown in these prior art documents, the locking slider is moulded over the ends of the U-shaped metal element. This solution is costly because it requires positioning of the U-shaped element in the mould and also because it requires bending operations for conferring the desired shape to the U-shaped metal member. The object of the present invention is to overcome the above drawbacks, and this object is achieved by a device according to claim 1. According to a preferred embodiment of the invention, said enlarged hollow portion of the sleeve has a bottom wall formed with a pair of spaced-apart apertures delimiting respective stepped catches, and said slider has a corresponding pair of front resilient projections formed with respective engagement teeth, said teeth being adapted to snap fit into said apertures upon assembling the device and to cooperate with said stepped catches, under the action of a compression helical spring acting between a seat of the enlarged hollow portion and a bar element of the slider integrally formed between said front projections. According to a further aspect of the invention, the sleeve has a tubular appendage beneath the enlarged hollow portion, intended to be axially fitted within an attachment tubular element fixed to the backrest structure of a motor-vehicle seat, said tubular appendage being formed with yelding axial tip sections resiliently tightened against the support rod. The invention will now be disclosed in detail with reference to the accompanying drawings, purely provided by way of non-limiting example, in which: figure 1 is a diagrammatic lateral elevational view of a height adjustment device for a support rod of a headrest for motor-vehicle seats according to the invention, figure 2 is a vertically sectioned and enlarged view of the adjustment device of figure 1 in the mounted condition, figure 3 is a horizontal section along line III-III of figure 2, and figure 4 is a vertically sectioned view along line IV-IV of figure 2. In the drawings, reference numeral 1 generally designates a height adjustment device for a support rod of a headrest (not shown in the drawings) for motor-vehicle seats. In a way known per se, the support rod is connected superiorly to the headrest framework, and is formed with a vertical row of positioning notches T by means of which the adjustment device 1 allows setting the desired vertical positioning of the headrest. Even in a way known per se, the headrest is provided with a pair of such support rods R, to each of which a respective adjustment device 1 is associated. The following description is applicable to both adjustment devices. The device 1 essentially comprises a sleeve 2 of moulded plastics material, through which the support rod R is axially slidably fitted, and having superiorly an enlarged hollow portion 3 and inferiorly a tubular appendage 4. As depicted in detail in figure 2, the tubular appendage 4 is intended for mounting within a tubular attachment member A fixed to the structure S of the backrest of a motor-vehicle seat. An anchoring tooth 5, projecting from the tubular appendage 4 and engaging a slit F, performs locking of the device 1 relative to the tubular attachment member A. The end of the tubular appendage 4 opposite to the enlarged hollow portion 3 is formed with axial slots 6 defining axial yelding tip sections 7 which are tightened, by means of an outer resilient ring 8 (figure 2), against the surface of the lower part of the support rod R. In this way sliding of the latter along the sleeve 2 is frictioned, and withdrawal thereof upwardly with respect to the sleeve 2 itself is also prevented. An annular slider 9, formed in one piece of moulded plastics material with an outer push-button 10, is slidable within the enlarged hollow portion 3, perpendicularly to the support rod R. In correspondence of its inner end, the slider 9 is formed with two integral fork elements 11 within which the opposite ends of a metal pin 12 are snap engaged, whose central section is placed along the sliding path of the support rod R. Forwardly to the metal pin 12, the slider 9 is formed with a pair of resilient front projections 13 provided with respective engagement teeth 14 movable into apertures 15 of the bottom wall 16 of the enlarged hollow portion 3. The inner edges of the apertures 15 define respective stepped catches 17 cooperating with the engagement teeth 14 of the slider 9. Between the two resilient projections 13, the slider 9 is further formed with an integral projecting bar element 18 over which one end of a compression helical spring 19 is wound, the opposite end of which bears against a seat 20 of the enlarged hollow portion 3. The above-disclosed arrangement is such that, upon assembling of the device 1, introduction of the slider 9 into the enlarged hollow portion 3 performs snap fitting of the teeth 14 into the apertures 15. In operation, the spring 19 is normally urging the slider 9 towards the outside of the enlarged hollow portion 3, placing the metal pin 12 into engagement with one of the positioning notches T of the support rod R. In this position the engagement teeth 14 of the slider 9 abut against the stepped catches 17 of the enlarged hollow portion 3. For the height adjustment of the support rod R, it is sufficient to operate the push button 10 so as to push the slider 9 against the action of the thrust spring 19, thus withdrawing the metal pin 12 from the positioning notch T. The support rod R can thus be displaced along the sleeve 2 until reaching the desired height adjustment, and then locked in that position by releasing the push button 10, whereby the spring 19 will displace the metal pin 12 into engagement with the corresponding positioning notch T. Naturally, the details of construction and the embodiments may be varied with respect to what has been described and illustrated, if not thereby departing from the scope of the present invention such as defined in the appended claims.

Claims: Height adjustment device for a support rod (R) of a headrest for motor-vehicle seats, wherein said support rod (R) is provided with a series of positioning notches (T), said adjustment device (1) comprising a sleeve (2) through which the support rod (R) is axially slidably fitted and having an enlarged hollow portion (3) in which an annular locking slider (9) of moulded plastics material having a push button (10) is displaceable perpendicularly to the support rod (R) and adapted to cooperate, under the action of resilient thrust means (19), with said positioning notches (T) so as to prevent displacement of the support rod (R) relative to the sleeve (2), said locking slider (9) incorporating a metal element (12) whose ends are engaged with said slider (9) and whose central section acts as an engagement member with said positioning notches (T) of the support rod, characterized said metal element is formed by a pin (12) whose opposite ends are snap fitted within corresponding fork elements (11) integrally formed with said slider (9). Device according to claim 1, characterized in that said enlarged hollow portion (3) has a bottom wall (16) formed with a pair of spaced-apart apertures (15) delimiting respective stepped catches (17), and in that said slider (9) has a corresponding pair of front resilient projections (13) formed with respective engagement teeth (14), said engagement teeth (14) being adapted to snap fit into said apertures (15) upon assembling the device (1) and to cooperate with said stepped catches (17), under the action of a compression helical spring (19) acting between a seat (20) of the enlarged hollow portion (3) and a bar element (18) of the slider (9) integrally formed between said front projections (13). Device according to claim 1 or claim 2, characterized in that said sleeve (2) has a tubular appendage (4) beneath said enlarged hollow portion (3), intended to be axially fitted within an attachment tubular element (A) fixed to the structure (S) of the seat backrest, said tubular appendage (4) being formed with yelding axial tip sections (7) resiliently tightened against the support rod (R).

Inventors: DE FILIPPO EMILIO IT, DE FILIPPO, EMILIO (IT)
Applicants: BRUZOLO MANIFATT GESTIND MB, GESTIND-M.B." MANIFATTURA DI BRUZOLO" S.P.A
Application year: 1995
Main classification: B60N2
IPC codes: B60N2