DE3706394C1 - Backrest for vehicle front seats - Google Patents

Abstract

Backrest for vehicle front seats, comprising deformation elements which can be deformed in an accident beyond the limit of elasticity. In the case of the backrest, the supporting parts include as deformation elements the extension and compression elements which are arranged along the rest of the backrest and the geometry and limit of elasticity of which change from top to bottom along the length of the backrest. <IMAGE>

Description

The invention relates to a backrest for vehicle front seats, comprising deformation elements that at deformed in an accident beyond the elastic limit can be. As the front seats of the vehicle all vehicle seats are understood to be free-standing are arranged, d. H. are not supported at the rear.

In Fig. 1, the structure of a conventional backrest for vehicle front seats is illustrated. The backrest 10 comprises, as load-bearing parts, two backrest bars 12 and a cross member 14 which closes off the backrest bars at the top and which are welded to one another. The backrest spars 12 and thus the backrest 10 as a whole is pivotable with respect to the seat part 8 of the vehicle about a shaft 16 which is mounted in a mounting section 18 .

The shape of the bars is chosen to suit the load. However, there must be a compromise between the load requirements with normal use and with dynamic Load and closed for people of different weights because there are different requirements the rigidity and function of the bars will.

In the event of a frontal or rear-end collision, the described backrests are loaded in such a way that they usually buckle out of their rigid mounting position when a certain force is exerted and thus only slightly absorb occupant energy due to deformation energy in a narrow range. The following applies to the deformation work performed: The force F acting on the backrest causes the backrest spars to deform, which is proportional to the path s , and performs the work W

As can be seen from the working diagram of FIG. 2a, a total deformation work W can be carried out on the backrest

W ≅ 1/2 F s

be used until the backrest buckles.

In the event of a rear-end collision, the backrest bars are bent backwards. The occupant energy can after the buckling the backrest bars are still so large that the passenger over the bent backrest that acts like a ramp in Is thrown towards the rear window. In the case of one A non-belted passenger is hit by a frontal impact a back seat against the front seat in front of him hurled. This can cause the backrest bars to buckle lead forward, and the unconverted kinetic energy of the passenger thrown forward is then on the passenger sitting in front of him and in his Restraint system introduced.

The force is applied to a conventional backrest off-center or the backrest bars are unequal stiff, this leads to a buckling of a backrest beam, whereby the second backrest spar over the backrest cross member is pulled sideways in a direction with less Stiffness.

To buckle the backrest, d. H. a fraction of the Backrest swivel bearing, to prevent or delay, various suggestions have been made. At one in DE-OS 19 57 496 described backrest of the beginning mentioned type are parts of the backrest frame, the Seat cushion frame and connecting parts as deformation elements trained to handle the stress in an accident of a buckled passenger to an acceptable level limit. The deformation elements are over the Elastic limit deformable and allow a uniform deformation of the seat with excessive force.

To avoid buckling of the backrest is in the DE-PS 25 04 646 the installation of an expansion member at least one side between the seat part and backrest has been proposed, one in the event of an impact effective stop is provided. With a dynamic The backrest is first loaded elastic adjustment of the backrest, then a plastic one Deformation and finally under very high loads after further deformation the fracture.

The invention has for its object a backrest for vehicle seats according to the type mentioned at the beginning create by passengers in the event of a vehicle impact transferred energy absorbs and becomes excessive Force deformed.

This task is with a backrest with the features of claim 1 solved. Advantageous further developments this backrest are the subject of the dependent claims.

The fact that the supporting parts of the backrest as deformation elements arranged along the length of the backrest Expanding and compressing elements are targeted Energy absorption through the backrest possible. This is supported by the fact that the geometry and Elastic limit of the expansion and compression elements along the Change the length of the backrest from top to bottom. By appropriate design of the backrest bars and cross members can control the deformation behavior of the backrest be that the energy absorption from the force application, d. H. usually from the upper backrest crossbeam, towards to the backrest pivot point. The stretch and Compression elements then speak from top to bottom with increasing Load, and they can do so be that they are only from a certain limit load deform. This makes it sufficient Ensure rigidity in normal use. By the limit load can also be increased be that for the deformation a greater deformation work is to be spent.

The step-by-step response of the expansion and compression elements provided according to the invention, which act in a graduated manner as energy absorbers, is particularly advantageous. This response behavior of the deformation elements, provided that force is applied, can be achieved predominantly on the upper back cross member by changing or increasing the energy required for the deformation from element to element, ie from top to bottom. Another measure can be to limit the path, ie the movement of the deformation elements. The total amount of deformation work W to be used should be maximal.

The force F exerted on a proposed backrest performs a deformation work according to the working diagram of FIG. 2b, where s is the path. The individual plateaus represent the force required in each case for maximum deformation of the individual deformation elements and illustrate the step-by-step (from top to bottom) response of the deformation elements described above. As can be seen from Fig. 2b, the deformation work applied to the backrest can be

W = ∫ F ds

represent as

W = F _m · s

where F _{m is} the mean force applied.

The proposed formation of a backrest enables one progressing from top to bottom in the backrest Energy conversion from kinetic to deformation energy. Through the sequential compression or expansion of the deformation elements (from top to below) the passenger can take a long time in the event of a rear impact be held in the seat. The accelerations acting on him are reduced, both for light and also for heavy passengers. In the event of a frontal impact are not belted passengers sitting in the back seat specifically braked by them on the backrest.

The upper area of the backrest can be in the desired manner be softly trained to relieve the strain on the cervical spine and the head if the head hits the Lower the backrest.

As can be seen from the above, the one proposed Backrest no buckling of the backrest as with conventional backrests. The passengers can - as mentioned - are held longer in the seat or become softer slowed down, and there is less danger of Hurling across the backrest. The security of the Passengers are thus improved.

The rigidity of the formed as deformation elements Expansion and compression elements not only advantageously change from one element to the next from top to bottom. According to a preferred embodiment of the invention the deformation elements at the same time expansion and compression elements. This makes the backrest in the event of a frontal or Rear impact particularly suitable in the same way.

Another development involves two Rows of expansion and compression elements in the direction of travel are arranged opposite each other such that a Expansion and compression element of one row, one expansion and Compression element opposite the other row, and vice versa. The distance between these rows expediently increases towards the back pivot so that there is a response the deformation elements from top to bottom or an increase in stiffness results. This arrangement will be the Total backrest load from both directions in the case a frontal or rear impact. For example causes a compression of a certain extent front to back spars on the Front edge in the case of a rigid frame the back and vice versa. In addition, the effect of Deformation elements hereby reinforced.

If the force in the backrest is slightly off-center the uppermost expansion / compression element speaks first of the more heavily loaded backrest beam until this goes to the stop. Then the force application increases, and as a result, so far less stressed backrest spear attacking force so high that their top expansion / compression element is activated.

If a backrest with as sheet metal stamping and bending parts executed backrest spar is used is the backrest according to a preferred embodiment trained as follows. The back edge a backrest spar has reference to its general Course (corresponding to the course of the backrest overall) lateral warping outwards. On the backrest spar plate a reinforcement plate is rigidly attached, the reinforcing plate at least the backrest plate partially covered laterally and in relation to the general Course of the rear edge of the backrest spar plate has lateral curvatures inwards, each opposite a lateral curvature of the backrest spar plate. These lateral curvatures and expansion elements. The backrest spar plate is useful and the reinforcement plate riveted to each other or welded, preferably spotted.

The arrangement, shape and dimension (height, width, depth, Wall thickness) of the deformation elements are according to the required rigidity, energy absorption capacity and Demand varies that the deformation elements from above should address down. This enables targeted Adjustment of the resilience of the deformation elements this construction.

The shape of the lateral curvatures can correspond to the Requirements may be different. For example two adjacent side curvatures together a cavity with approximately diamond-shaped or rectangular Form cross-section that extends from the rear spar edge rejuvenated. It can also be an elongated cavity Cross-section be formed, the walls of which increase of stiffness have stiffening deformations.

If a backrest is used in which the backrest bars as an extruded profile or die-cast or tubular construction are executed, is provided that a backrest spar two in each other Direction of travel opposite longitudinal beams, which stiffened by a framework of profile or pipe sections are, the longitudinal beams between two Joints with the sections of the truss expansion and have compression elements. This construction enables it, the backrest with exceptionally low weight and at the same time to train great stability. The first unloaded parts of the backrest are firmly attached to the Truss connected while the expansion and compression elements lie freely between the truss connection points.

When designing the backrest as an extruded profile Construction or as a construction with die-cast parts the expansion and compression elements in a preferred embodiment through meandering shape of the Sidelong formed. The side members thus have sections on in which their general course through after short transverse webs offset on the inside are interrupted, whereby two crossbars each through a connecting longitudinal web are connected and each result in this meander pattern. The rigidity of the deformation elements can thereby be increased that the meander web sections from the top to have a greater density below. By varying the Distances within a series of expansion and compression elements and the row spacing (force / displacement optimization) that The shape and dimension of the deformation elements are the desired Deformation behavior and response of the deformation elements as well as the required backrest stiffness reached.

In the case of a backrest design as a tubular construction are the expansion and compression elements in a preferred one Embodiment bellows-like. A Carrier then has bellows sections, which are at a load on the backrest from above and also from the side contract or, if necessary, expand a little to the side can. The bellows-like construction can thereby be formed be that several pipe sleeves with flanges are nested are slidable with respect to each other. The rigidity of the expansion and compression elements can be from above can be varied downwards in that the length, number and Dimension of the bellows segments is changed. For stiffening the backrest from top to bottom can be the tube diameter, the distance between the tubes of one side of the spar and the Wall thicknesses are increasingly formed.

Appropriate anchoring of the truss on the side members is provided in that the sections of the Truss through connecting plates, d. H. Gusset plates, are attached. The truss sections can also if necessary be continuous and only bent. At Such a bending point can be a node or connecting plate enclose the bow together with the side member, by being bent around the side member and on is riveted to the edges. This is a secure attachment of the framework possible.

Three embodiments of the invention are in the Drawing shown and are described in more detail below. In the drawing shows

Fig. 1 shows the structure of a conventional backrest,

Figures 2a and b are diagrams work. For illustration of (a) to a conventional and (b) at a back invention lehene spent deformation work,

Fig. 3a shows a schematic representation of a portion of a backrest according to a first embodiment, in which the backrest bars are designed as Blechstanz- and -biegeteile,

FIG. 3b is an enlarged view of a deformation element of the, in FIG. 3a shown backrest

FIG. 4a and b are enlarged views of another two embodiments of the deformation elements, in Fig. 3a shown backrest

FIG. 5a is a schematic representation of a back beam of a second embodiment of a backrest, wherein the backrest is designed as a spar Strangpreßprofilkonstruktion,

Fig. 5b is an enlarged schematic view of a deformation element of the, in FIG. 5a shown backrest Holms

Fig. 6 is a representation of a third embodiment of a backrest, in which the backrest beam is designed as a tubular structure, and

Fig. 7a and b show schematic representations of the arrangement of the backrest beams and deformation elements with one-sided and two-sided arrangement of the deformation elements in the backrest bars.

In all illustrated embodiments of the Invention are the supporting parts of the backrest as active expansion and compression elements.

In the first exemplary embodiment, which is shown schematically in FIG. 3, a backrest beam 12 of a backrest 10 is designed as a stamped sheet metal part. At the upper end of the backrest spar 12 there is a cross member 14 . The backrest pillar 12 , which is plate-like and is referred to below as the backrest pillar plate, is cut according to the general course of the backrest and has lateral bulges 22 on the rear edge 20 , the uppermost of which begins with the bottom edge of the cross member 14 . The edge profile of the backrest spar plate 12 is sinusoidal in the exemplary embodiment shown in relation to the general shape of the backrest spar, but can also be, for. B. be triangular. The dimensions of the lateral curvatures 22 increase from top to bottom, ie their width B , height H and depth T increase from top to bottom. On the inside of the backrest spar plate

12 extends, rigidly attached to this, a reinforcing plate 24 . The reinforcement plate 24 has lateral curvatures 26 on the level of the lateral curvatures 22 of the backrest beam plate 12 . The lateral curvatures 26 have the same height, width and depth as the curvatures 22 of the backrest spar plate. The two plates 12, 24 are connected to one another at the points corresponding to the general course of the backrest without the curvatures 22 and 26 by means of welding points or rivets 28 .

The reinforcement plate 24 stiffens the backrest spar plate 12 . The lateral curvatures 22 of the backrest spar plate 12 and the lateral curvatures 26 of the reinforcing plate 24 together form the expansion and compression elements. When the backrest beam is loaded in the direction of travel, the two plates 12 and 24 bulge laterally between the welded or riveted connections and are deformable in the area of the lateral curvatures. If the load is very high, the backrest may deform permanently or the backrest may bend. However, this is done in stages from top to bottom, corresponding to the individual expansion and compression elements 22, 26 . With increasing stress on the backrest, it then bends from top to bottom. A sudden buckling of the backrest bars with a correspondingly abrupt load on the passenger is completely ruled out.

The rigidity of the expansion and compression elements can be their shape can be influenced in the desired manner. For this needs z. B. only the curve, d. H. form, of the side warps to be changed. It can different sheet thicknesses can also be selected.

The side curvatures 22 shown in FIG. 3 and in an enlarged representation in FIG. 3a each form, together with the adjacent curvatures 26, a cavity with an approximately diamond-shaped cross section, which tapers towards the end remote from the rear edge 20 . Instead of a diamond-shaped cross section, z. B. a rectangular cross-section can be selected, as it is formed in Fig. 4a by the bulges 22 ', 26' . To reinforce the walls of the backrest plate 12 and the reinforcing plate 25 in the region of the lateral curvatures 22 '', 26 '' can also be formed with stiffening deformations 23 . This is illustrated in Figure 4b where the cavity has an elongated cross-section.

In the second exemplary embodiment illustrated in FIG. 5, the backrest is designed as an extruded profile construction. The illustrated backrest pillar 12 of the backrest 10 is connected at its upper end to a cross member 14 indicated in FIG. 3. The backrest beam 12 comprises a compact lower section 32 and two longitudinal beams 34, 36 which are stiffened or connected to one another by a truss 38 of zigzag profile sections. In the exemplary embodiment shown, the framework 38 comprises profile sections 40 which run obliquely from top to bottom between the longitudinal beams 34, 36 , of which two adjacent profile sections each form a transverse "V". The profile sections 40 open into the longitudinal beams 34, 36 at such an angle that the profile sections 40 optimally take over the force.

At certain distances from one another, the two longitudinal beams 34, 36 have deformation elements 42 , ie expansion and compression elements. The general course of the longitudinal beams 34, 36 is interrupted in these areas. At the end of a section there is in each case a crosspiece 44 which extends inwardly with respect to the backrest beam width, so that the longitudinal member has a greater width or thickness in this region. A crossbar 44 is also provided at the end of the opposite section. The two transverse webs 44 are connected to one another by a longitudinal web 46 , which bridges the interruption in the longitudinal beam course and extends laterally offset.

In Fig. 5b, a deformation element 42 is shown enlarged to illustrate the effect of the applied forces. When a downward, pressure-exerting force (component) F is applied in the longitudinal direction of the longitudinal beam 36 , a "disturbing" torque (F · l) is generated by the lever arm 1 of the crossbar 44 , which causes the "beam" at a specific load can buckle in the given direction (compression of the deformation element). In the event of a tensile load (upward force F _r ), the moment (F _r · l) causes bending and the deformation element is stretched. In the area of the deformation elements 42 , the longitudinal members 34, 36 are thus more flexible and can be compressed or stretched. These deformation elements 42 are each arranged between two connection points with the profile sections 40 of the framework 38 , so that a deformation element 42 lies opposite a connection point between two profile sections 40 with the opposite longitudinal member.

The flexibility and deformability of the backrest 10 can be adjusted in the desired manner by the number and configuration of the deformation elements 42 . In contrast to the more area-wise formation of the deformation elements in the first embodiment, the deformation elements in this second embodiment are rather discrete elements. The overall rigidity of the backrest beam 12 can be further influenced by the respective design of the framework 38 .

In the third exemplary embodiment illustrated in FIG. 6, the backrest spars 12 , one of which is partially illustrated, are designed as a tubular construction. The backrest beam 12 comprises two tubular longitudinal beams 34, 36 , which are connected and stiffened by a truss 38 of zigzag tube sections 50 . At the upper end, the side members 34, 36 are bent laterally to form cross member sections 14 a , 14 b and are connected to one another below the lower bend by a riveted connecting plate 52 .

The pipe sections 50 of the truss 38 are expediently formed in one piece by bending and welded to the corresponding longitudinal member 34, 36 at a respective bending point. These connection points are additionally secured by connecting plates 54 , which represent gusset plates and are each bent over the longitudinal beams 34 and 36 and riveted to the free edges.

Between two connecting plates 54 deformation elements 42, ie, stretch and compression elements are arranged in each case. In the exemplary embodiment shown, they are bellows-like and can be formed in that a plurality of pipe sections 56 with flanges 58 are inserted one into the other and are each held in position in a spring-loaded manner. In the exemplary embodiment shown, the number of bellows segments increases from top to bottom, namely from 3 to 4. The thickness of the tubes also increases from top to bottom, so that the bottom deformation element is stiffer than the other deformation elements. By choosing the number of bellows segments z. B. the rigidity of the deformation elements can be adjusted. The deformability of the backrest is in turn also determined by the number and arrangement of the deformation elements.

Fig. 7a shows a schematic representation of an example of one-sided arrangement of the deformation elements on a backrest Holm. In accordance with the desired response of the deformation elements 42 , their distance from one another or to the backrest pivot point changes, and the shape of the backrest spar also changes from top to bottom. The distance of the deformation elements arranged on the rear edge of the backrest beam from the front edge of the backrest beam thus changes from top to bottom. The distance between the deformation elements 42 is also correspondingly variable when arranged on both sides along the backrest spar (cf. FIG. 7b).

Claims (21)

1. Backrest for vehicle front seats, comprising deformation elements which can be deformed in an accident beyond the elastic limit, characterized in that the load-bearing parts ( 12; 32, 34 ) of the backrest ( 10 ) are arranged as deformation elements along the length of the backrest. and compression elements ( 22, 26; 42 ), the geometry and elastic limit of which change along the length of the backrest from top to bottom. 2. Backrest according to claim 1, characterized in that the rigidity of the expansion and compression elements ( 22, 26; 42 ) increases in each case from one element to an element arranged below it. 3. Backrest according to claim 1 or 2, characterized in that the deformation elements ( 22, 26; 42 ) are at the same time expansion and compression elements. 4. Backrest according to claim 3, characterized in that two rows of expansion and compression elements ( 42 ) are arranged opposite to each other in the direction of travel such that each expansion and compression element of one row is opposite an expansion and compression element of the other row, and vice versa. 5. Backrest according to claim 4, characterized in that the distances between the expansion and compression elements ( 42 ) of a row change from top to bottom. 6. Backrest according to claim 4 or 5, characterized in that the distance (A) of the expansion and compression elements ( 42 ) arranged opposite one another in two rows increases in the direction of the backrest pivot point. 7. Backrest according to one of claims 4 to 6, with backrest spars which are formed with the expansion and compression elements and as sheet metal stamping and bending parts, characterized in that the rear edge ( 20 ) of a backrest spar plate ( 12 ) with respect to it general course has lateral curvatures ( 22 ) to the outside and that in each case a reinforcing plate ( 24 ) is rigidly fastened to a backrest bar plate, the reinforcing plate at least partially covering the backrest bar plate laterally and with respect to the general course of its rear edge lateral curvatures ( 26 ) has on the inside, each opposite a lateral curvature of the backrest spar plate. 8. Backrest according to claim 7, characterized in that two adjacent lateral curvatures ( 22, 26 ) of the backrest spar plate ( 12 ) and the reinforcing plate ( 24 ) together form a cavity with an approximately diamond-shaped cross section, which extends to that of the rear edge ( 20 ) of the backrest spar or reinforcement plate tapering away end. 9. Backrest according to claim 7, characterized in that two adjacent lateral curvatures ( 22 ', 26' ) of the backrest spar plate ( 12 ) and the reinforcing plate ( 24 ) together form a cavity with an approximately rectangular cross-section, which extends to that of the rear Edge ( 20 ) of the backrest spar or reinforcement plate tapering away from a certain depth (T 1 ). 10. Backrest according to claim 7, characterized in that the walls of the lateral curvatures ( 22 '', 26 '' ) have stiffening deformations ( 23 ) and that two adjacent lateral curvatures ( 22 '', 26 '' ) of the backrest spar plate and Reinforcing plate ( 24 ) form a cavity with an elongated cross section, which tapers towards the end remote from the rear edge ( 20 ) of the backrest spar or reinforcing plate. 11. Backrest according to one of claims 7 to 10, characterized in that a backrest spar plate ( 12 ) and an associated reinforcing plate ( 24 ) are welded or riveted to one another, the connections ( 28 ) in each case in the central region between the lateral curvatures ( 22 ) the backrest spar plate or the bulges ( 26 ) of the reinforcing plate are arranged. 12. Backrest according to one of claims 7 to 11, characterized in that the depth (T) of the lateral curvatures ( 22 ) of the backrest spar plate ( 12 ) and / or of the lateral curvatures ( 26 ) of the reinforcing plate ( 24 ) changes from top to bottom. 13. Backrest according to one of claims 7 to 12, characterized in that the length (H) of the lateral curvatures ( 22 ) of the backrest spar plate ( 12 ) and / or the lateral curvatures ( 26 ) of the reinforcing plate ( 24 ) from top to bottom changes. 14. Backrest according to one of claims 7 to 13, characterized in that the width (B) of the lateral curvatures ( 22 ) of the backrest spar plate ( 12 ) and / or the lateral curvatures ( 26 ) of the reinforcing plate ( 24 ) from top to bottom changes. 15. Backrest according to one of claims 7 to 14, characterized in that the sheet thicknesses (s) change from top to bottom. 16. Backrest according to one of claims 4 to 6, with as an extruded profile or die-cast part or as a tubular construction backrest spars, characterized in that a backrest spar ( 16 ) each comprises two mutually opposite longitudinal beams ( 34, 36 ) by a truss ( 38 ) of profile or pipe sections ( 40, 50 ) are stiffened, the longitudinal beams each having expansion and compression elements ( 42 ) between two connection points with the sections of the framework. 17. Backrest in the form of an extruded profile or die-cast construction according to claim 16, characterized in that the expansion and compression elements ( 42 ) are formed by a meandering shape of the side members ( 36, 38 ). 18. Backrest according to claim 17, characterized in that the thickness of the meander web sections ( 44, 46 ) changes from top to bottom. 19. Backrest according to claim 17 or 18, characterized in that the thickness of the profile sections ( 40 ) of the framework changes from top to bottom. 20. Backrest according to one of claims 17 to 19, characterized in that the depth of the meandering sections ( 42 ) changes from top to bottom. 21. Backrest in the design as a tubular construction according to claim 16, characterized in that the expansion and compression elements ( 42 ) are bellows-like. 22. Backrest according to claim 21, characterized in that the tube sections ( 50 ) of the framework on the side members ( 34, 36 ) are fastened by connecting plates ( 54 ). 23. backrest according to one of claims 16, 21 or 22, characterized in that the tube diameter and change wall thicknesses from top to bottom. 24. Backrest according to one of claims 21 to 23, characterized in that the length and number of bellows segments ( 56, 58 ) of the expansion and compression elements ( 42 ) change from top to bottom.