A back support element for seats, particularly motor-vehicle seats

Abstract: A back support element (1), preferably a lumbar support element, for motor-vehicle seats is generally hour-glass- or butterfly-shaped and is constituted by two symmetrical, complementary portions (3). Each of the portions is supported on one of the uprights (7) of the backrest (B) by means of a horizontal tie (4) which extends through a hole (11) in a flag-like element (8) articulated (9) on the outer end of the respective complementary portion (3). Traction means, such as flexible- or Bowden-cable controls (13) enable the free ends of the flag-like elements (8) to be pulled outwardly. As a result of the outward movement of the free ends of the flag-like elements (8) thus achieved, the outer ends of the complementary portions (3) are urged forwardly, modifying the horizontal profile of the support element (1) towards a more concave condition, so that the lateral restraint achieved by the backrest (B) is more marked.

Description: The present invention relates to a back support element for the backrests of seats, for example, motor-vehicle seats, the support element including two complementary portions which are interconnected for pivoting relative to each other about a vertical axis in use, so that the general concavity of the support element is variable, in which: a flag-like element associated with each complementary portion has a first end which cooperates in a generally hinged configuration with the outer end, with respect to the seat, of the respective complementary portion so as to be pivotable relative thereto about a substantially vertical axis in use, and a second, free end which can project towards the other complementary portion, and operating means associated with the flag-like elements act on the free ends of both flag-like elements in order selectively to move the free ends apart, thus projecting the outer ends of the complementary portions forwards so as to vary the profile of the support element towards a generally more concave configuration. A back support element of the type specified above is described, for example, in the Applicant's EP-A-0 518 830 (to be taken into consideration under Article 54(3)EPC). The object of the present invention is to provide a further improvement to the solution described in this prior patent application, particularly as regards the possibility of providing the same transverse restraint for the seat-occupant's body with the use of fewer parts thus achieving a technical simplification which may be beneficial for the purposes of reducing costs. According to the present invention, this object is achieved by virtue of a back support element having the specific characteristics recited in the characterizing portion of Claim 1. The invention will now be described, purely by way of non-limiting example, with reference to the appended drawings, in which: Figure 1 shows schematically a portion of a seat, such as a motor-vehicle seat, in which a support element according to the invention is mounted, Figures 2 and 3 are two views, a plan view and a lateral rear elevation, respectively, showing the structure of one of the elements illustrated in Figure 1 in greater detail, and Figure 4 shows a possible variant of the solution according to the invention. In the drawings, a back support element is generally indicated 1, and is intended to be fitted in the backrest B of a seat such as a motor-vehicle seat S, the profile of which is shown partially in broken outline in Figure 1. In practice, the element 1 is constituted by a band or strip which extends generally horizontally at the level of the lumbar portion of the back of the person occupying the seat S, and is generally hour-glass- or butterfly-shaped, that is, it is narrowest in its central portion and its depth increases gradually towards its outer ends which face the lateral uprights 2 of the backrest frame. The element 1 is constituted substantially by two complementary portions 3 which are generally specularly symmetrical with respect to the vertical median plane of the backrest B. Each portion 3 is connected to the respective upright 2 of the backrest by means of a horizontal tie 4 (constituted, in the embodiment illustrated, by a helical spring). The two portions 3, which are made of rigid material (e.g. metal or rigid plastics) with weight-reducing holes, are hinged together at their mutually-facing inner edges, that is, in correspondence with the vertical median plane of the backrest B, by means of a coupling element 5 constituted, for example, by a sleeve of resilient material (for example, rubber). This is all according to general principles and for purposes described in greater detail in the Applicant's European patent application EP-A-0 420 824 to which reference may usefully be made for a more detailed description of the structural characteristics of the element 1. In particular, it can be seen that the hook-shaped inner ends of the springs 4 are hooked onto brackets or fins 6 projecting from the rear faces of the portions 3 which are generally concave towards the front of the backrest B. More precisely, the brackets 6 have a plurality of holes 6a which can be used selectively for the engagement of the inner ends of the springs 4. The springs 4 are not usually engaged in the holes 6a directly but with the interposition of coupling rings 4a (for example, split metal rings which are inserted in holes 6a and then closed) which in turn form seats for the engagement of the ends of the springs 4. The arrangement described has the advantage that it enables the springs 4 to be hooked onto the element 1 in several configurations, for example, so that a back support element 1 of the same type can be used for backrests of seats having different dimensions and/or characteristics. The outer ends (with respect to the seat as a whole), of the springs 4 also have hook-shaped end portions which can be engaged, for example, in generally C-shaped eylets 7 which project from the central portions of the lateral uprights 2 of the backrest. Two arm-like elements 8 of rigid material (for example, metal or hard plastics) are also mounted on the rear (convex) faces of the portions 3, again generally symmetrically with respect to the vertical median plane of the backrest B, and cooperate with the portions 3 in a generally flag-like configuration. Specifically, in the embodiment of Figures 2 and 3, the outer end (with reference to the seat as a whole) of each flag-like element 8 has a shaft 9 which is approximately vertical and which engages two articulation lugs 10 above and below the flag-like element 8, respectively, so that the flag-like element 8 can pivot generally relative to the respective portion 3 about a vertical axis which corresponds to the axis of the shaft 9. In other words, a kind of hinged coupling is formed between the element 8 and the portion 3. An important characteristic of the solution according to the invention in the embodiment to which Figures 2 and 3 relate is the general connection arrangement adopted for the articulation lugs 10. As can better be seen in the plan view of Figure 2, in practice, the lugs 10 are configured as two brackets or " flat pieces" which are mounted at the outer ends of the respective portions 3 and, more precisely, in correspondence with a rounded, rearwardly-facing end edge 30. As has been seen, each portion 3 is generally concave at the front, that is, towards the front of the backrest 2. At its outer edges (with respect to the seat as a whole), however, the element 1 has two channel-shaped formations defined by the end edge 30 itself. These channel-shaped formations are open rearwardly at the rear of the element 1 and can thus constitute cavities for housing the articulation lugs 10 for the flag-like elements 8. In the embodiment to which Figures 2 and 3 refer specifically, the articulation lugs 10 do not constitute integral parts of the respective portions 3 of the element 1. On the contrary, they constitute parts of U-shaped inserts (made of metal or particularly strong plastics material) the end flanges of which define the lugs 10 and the central portions of which are inserted in the channel-shaped cavities defined by the rounded end edges 30. These inserts are fixed to the portions 3, for example, by the engagement of screws or pins 31 (Figure 2) which are inserted (snap-engaged, if appropriate) in corresponding holes 32 in the walls of the portions 3. The firm connection which can transmit forces between the lugs 10 and the respective portions 3 is preferably further reinforced as a result of the presence of a tooth or rib 33 which projects from the rear wall of each portion 3 and engages a corresponding cavity 34 in the periphery of the articulation lug 10. Naturally, in a possible alternative embodiment of the invention, the lugs 10 could be formed integrally with the respective portion 3, for example, by moulding in plastics material. Regardless of the method adopted to form the articulation lugs 10 (separate fitted inserts or co-moulded elements), it can be seen that the rounded edge 30 constitutes a kind of stiffening rib which can absorb the stresses transmitted to the lugs 10 towards the respective portion 3 as a result of the pivoting of the flag-like elements 8 which will be mentioned further below. Moreover, tests carried out by the Applicant have shown that the articulation of the outer ends of the flag-like elements 10 in positions coinciding with the outermost edges of the portions 3 (or possibly even further out, as in the present case: it will be noted from Figure 2 that the shaft 9 is situated further out than the edge 30 with respect to the seat as a whole) is particularly advantageous for achieving the movement which will be described below. In the variant to which Figure 4 relates, the articulation lugs 10 and the members associated therewith are completely eliminated and, as regards the flag-like elements (in this case indicated 8'), use is made of the presence of the rounded edge 30 and the rearwardly-open cavity defined by the edge to achieve a general connection configuration which may be defined as generally cup-shaped. More specifically, in the embodiment of Figure 4, the flag-like elements which, in the embodiment of Figures 2 and 3, are of generally rectilinear and flattened shape, have generally rounded outer end portions, indicated 35, which can engage the channel-shaped formations defined by the edges 30. In the embodiment shown, the rounded outer edge 35 is formed simply by the hook- or crook-like shaping of the plate constituting the flag-shaped element 8' (for example, of bent metal or plastics material moulded to shape). This solution has been found particularly advantageous in terms of simplicity and functional efficiency and also because it can give the element 8' generally resilient characteristics. Naturally variants of the same principle may be considered and put into effect. In particular, it will be appreciated from Figure 4 that the bending operation (actual or theoretical) for forming the rounded end 35 is effected from the outside inwardly (in other words, the tip portion of the hook-shaped free end of the flag-like element 8' is arranged so as to face inwards with respect to the backrest of the seat). It is thus possible to define an axis or position for the pivoting of the flag-like elements 8' relative to the respective portion which is located as far out as possible, with respect to the backrest of the seat : this is all according to the criteria and with the advantages already described above with reference to the embodiment of Figures 2 and 3. In both the embodiments described, each flag-like element 8, 8' has an opening 11 near its free end for the passage of the spring 4 which connects the respective portion 3 of the support element to the homologous upright 2. The free ends of the flag-like elements 8, 8' are preferably interconnected by a resilient element 12 (such as a spring, shown only in Figure 1) which acts in a direction such that it biases the two flag-like elements 8, 8' towards each other so as to extend the two portions 3 of the element 1 or move them apart generally at the front. Under the action of the biasing spring 12 alone, the element 1 thus tends spontaneously to adopt the less vertically concave condition to which Figure 1 relates explicitly. Each of two flexible-cable controls (so-called "Bowden cables"), indicated 13, has a sheath 14 which extends from the centre of the backrest B to the region of the bracket 6 so as to react against the edge of a hole 15 in the respective flag-like element 8, 8' whilst the active element of the control 13 extends outwards relative to the seat so that its end engagement element 13a abuts the upright 2. For this purpose, the upright 2 usually has a slot or hole the edges of which form reaction surfaces for the end element 13a which is constituted by a small ball co-moulded on the end of the cable 13 or by any element fixed firmly to the cable 13. When the flexible-cable controls 13 are operated (by known means, for example, by means of a manual control lever or a motor, which are not shown since they are not relevant per se for the purposes of an understanding of the invention), as a result of the reaction of the sheaths 14 against the free ends of the flag-like elements 8, 8', the free ends are moved apart towards the uprights 2 so that the flag-like elements 8, 8' cause a generally forward movement of the region (the shaft 9 and the lugs 10 in the embodiment of Figures 2 and 3; the cavities defined by the edge 30 in the embodiment of Figure 4) in which each flag-like element 8, 8' is articulated (an actual hinge in the embodiment of Figures 2 and 3 - a cup-shaped coupling in the embodiment of Figure 4) on the respective portion 3 of the element 1. In practice, this corresponds to a forward movement (shown by a broken outline in Figure 4) of the outer ends of the portions 3, and hence of the support element 1, which thus tends to adopt a more arcuate and concave shape than in its rest position shown in Figure 1. In these conditions, the backrest can achieve accentuated lateral restraint of the seat-occupant's back substantially as occurs, for example, in the seats of some sports cars. Naturally, if the flexible-cable controls 13 are slackened, the free ends of the flag-like elements 8, 8' tend to move towards each other, possibly under the biasing force exerted by the spring 12, so that the element 1 tends to return to the less convex position of Figure 1. In these conditions, particularly when the resilient biasing element 12 is present, the element 1 retains a very good ability to adapt automatically to the dimensions of the seat-occupant's back and to the stresses applied to the backrest B thereby. It will be appreciated that, in practice, the result described is achieved by virtue of the fact that each of the two portions 3 which constitute the support element 1 is associated with a flag-like element 8, 8' which is connected to the respective portion 3 in a generally hinged arrangement by means of an articulation axis (an actual shaft in the case of the embodiment of Figures 2 and 3, and a nominal axis in the case of the embodiment of Figure 4) which is substantially vertical and is located at the outer edge of the portion 3. This is all so that the movement apart of the free ends of the flag-like elements 8, 8' (and also the sliding connection existing between the elements and the resilient ties 4 which extend through the holes 11) gives rise to a generally forward movement of the coupling region and hence of the outer ends of the portions 3 mentioned above. In the solution according to the invention, the springs 4 perform a dual function, that is to say, that of connecting the respective portions 3 of the support element 1 to the perimetral structure of the backrest (the lateral upright 2) as well as that of providing guides for the sliding of the respective flag-like elements 8, 8' when the free ends of the elements are pulled outwardly as a result of the traction exerted by means of the flexible-cable control 13. As each flag-like element 8, 8' moves outwardly it therefore slides along the corresponding spring 4, which acts as a guide. As is clearly shown in Figures 2 to 4, in order to permit this movement, the helical portions 4b of the springs in question occupy only a portion, usually a small portion, of the overall length of each spring 4, generally in the central region with respect to each spring as a whole. The helical portion 4b is generally situated slightly further out than the plane located in the middle of the length of the spring 4 and the rest of the length of the spring is taken up by the two hooked bearing ends for connection to the bracket 6 and to the upright 2, respectively. Naturally, the helical portion 4b is separated from the hook-shaped end which is intended to be connected to the ring 4a (and hence to the bracket 6) by a straight portion, the length of which is equal to the travel envisaged for the sliding movement of the flag-like element 8, 8' relative to the spring 4. By virtue of the general channel-shaped configuration of the outer edge 30 of the portion 3, it is possible to form, within a generally thin element 1, a very strong structure which can absorb the pressure stresses applied by the flag-like elements either indirectly (by means of the lugs 10 in the embodiment of Figures 2 and 3) or directly (in the case of the cup-shaped coupling of the embodiment of Figure 4). In a particuarly preferred embodiment, the flag-like element 8' of Figure 4 is formed of a material (for example, a metal such as steel) which has marked resilience characteristics, so that the coupling angle relative to the portion 3 can be varied, by virtue of its resilient flexibility characteristics. In particular, the use of a resilient flag-like element 8' avoids the need for any biasing elements (such as the springs 12) for preventing the flag-like elements 8 from accidentally reaching and passing a dead-point position during their outward travel (the furthest forward projection of the outer edges of the portions 3) which would prevent them from returning spontaneously towards the closure position shown in Figure 1 simply as a result of the slackening of the flexible-cable controls 13, 13.

Claims: A back support element for the backrests (B) of seats (S), for example, motor-vehicle seats, the support element including two complementary portions (3) which are interconnected (5) for pivoting relative to each other about a vertical axis in use, so that the general concavity of the support element (1) is variable, in which: a flag-like element (8, 8') associated with each complementary portion (3) has a first end (9) which cooperates in a generally hinged configuration with the outer end, with respect to the seat, of the respective complementary portion (3) so as to be pivotable relative thereto about a substantially vertical axis in use, and a second free end which can project towards the other complementary portion (3), and operating means (13) associated with the flag-like elements (8, 8') act on the free ends of both flag-like elements (8, 8') in order selectively to move the free ends apart, thus projecting the outer ends of the complementary portions (3) forwards so as to vary the profile of the support element (1) towards a generally more concave configuration, characterised in that the outer end of each complementary portion (3) has a substantially channel-shaped edge (30) for cooperating with the first end of a respective flag-like element (8, 8') in a relationship such that forces can be transmitted. An element according to Claim 1, characterised in that it includes force-transmission means (10) which are hinged on the flag-like elements (8) and fitted within the channel-shaped edge (30). An element according to Claim 2, characterised in that the force-transmission means (10) constitute separate means (31) fitted on the complementary portions (3). An element according to Claim 2, characterised in that the force-transmission means (10) are formed integrally with the complementary portions (3). An element according to any one of the preceding claims, characterised in that the flag-like elements (8) are hinged (10) on the complementary portions (3). An element according to Claim 1, characterised in that the flag-like elements (8') are coupled to the complementary portions (3) in a generally cup-shaped coupling configuration. An element according to Claim 6, characterised in that the flag-like elements (8') are constituted by plate-like bodies each shaped into a generally hook-like configuration so as to form a rounded end (35) for engaging the channel-shaped edge (30). An element according to Claim 7, characterised in that the rounded end (35) is shaped like a hook and its tip faces generally inwards with respect to the seat. An element according to any one of the preceding claims, characterised in that the flag-like elements (8') are resiliently flexible. An element according to any one of the preceding claims, characterised in that it includes resilient means (12) for biasing the free ends of the flag-like elements (8, 8') towards each other against the action of the operating means (13). An element according to any one of the preceding claims, characterised in that the complementary portions (3) are interconnected in correspondence with the vertical median plane of the backrest (B). An element according to any one of the preceding claims, characterised in that the complementary portions (3) are interconnected by means of a generally annular connecting element (5). An element according to any one of the preceding claims, characterised in that it is generally hour-glass- or butterfly-shaped, being narrowest in correspondence with the region of the connection between the complementary portions (3) and increasing gradually in depth towards the outer ends of the complementary portions (3). An element according to any one of the preceding claims, characterised in that the channel-shaped edge is generally rounded in shape. An element according to any one of the preceding claims, characterised in that the operating means (13) comprise at least one flexible-cable control (13, 14). An element according to Claim 15, characterised in that the operating means comprise two flexible cables (13, 14) which act on the flag-like elements (8, 8') in a generally specularly symmetrical arrangement. An element according to Claim 15 or Claim 16, characterised in that said flexible-cable control includes a sheath (13) which bears against the free end of the flag-shaped element (8, 8') in a relationship such that forces can be transmitted. An element according to any one of Claims 15 to 17, characterised in that said flexible-cable control includes an active operating element (13) which abuts (13') a lateral upright (2) of the backrest. An element according to any one of the preceding Claims 15 to 18, characterised in that the flag-like elements (8') have holes (15) through which the active elements of the flexible-cable controls (13, 14) are intended to extend. An element according to any one of the preceding claims, characterised in that it carries associated spring means (4) for supporting the complementary portions (3) on the lateral uprights of the backrest of the seat. An element according to Claim 20, characterised in that the flag-like elements (8') have holes (11) through which the spring means (4) are intended to extend in a configuration such that the spring means (4) define guide formations for the pivoting movement of the flag-like elements (8, 8'). An element according to Claim 21, characterised in that said spring means (4) has a central helical portion (4b) as well as at least one substantially straight end portion which is intended to extend slidably through said holes (15) in said flag-like elements (8, 8').

Inventors: DAL MONTE ANTONIO, DAL MONTE, ANTONIO
Applicants: FIAT AUTO SPA, FIAT AUTO S.P.A.
Application year: 1993
Main classification: B60N2
IPC codes: B60N2