IE880880L

IE880880L - Impact absorber for vehicle doors

Info

Publication number: IE880880L
Application number: IE880880A
Authority: IE
Inventors: Simon Frank
Original assignee: Alusuisse
Priority date: 1987-03-25
Filing date: 1988-03-24
Publication date: 1988-09-25
Also published as: DK156988A; EP0284566A2; DK164215B; DE3881734D1; EP0284566A3; DK156988D0; DK164215C; DE3709489C1; IE62501B1; EP0284566B1

Abstract

An impact beam for vehicle doors is proposed which is made from a light metal alloy by an extrusion process and can be fixed in the vehicle door running approximately in the direction of travel in such a way that one profiled wall of the impact beam as the inner cord faces the interior of the vehicle and a second profiled wall of the impact beam spaced a distance from the first forms an outer cord. The outer cord (21) of the impact beam (20, 20f) is provided roughly halfway along its length with a pair of edge mouldings (40), each of which lies at a distance (g) from and on different sides of a transverse plane through the impact beam, this transverse plane falling in the middle of the length (N) of the impact beam or running at a small distance (s1, s2) from it. An impact beam of this type has a high degree of dimensional stability a low weight and adequate ability to compensate for the deformation energy occurring. <IMAGE> [EP0284566A2]

Description

62501 10 IMPACT BAR FOR VEHICLE DOORS, 15 ESPECIALLY FOR DOORS OF PASSENGER CARS.

This invention relates to an impact bar for vehicle doors, especially for doors of passenger cars, which is produced by extrusion from a light metal alloy and can be fixed to either end of the vehicle door extending in the direction of travel in such a manner that one 20 profile wall of the impact bar forms an inner flange facing towards the interior of the vehicle and a second profile wall of the impact bar provided at a distance therefrom forms an outer flange.

Impact bars of this type are provided in the vehicle doors for 25 securing the passengers against lateral deforming forces in collisions, i.e. forces acting transversely of the travelling direction. Such impact bars with an I-shaped cross-section, which when installed have their central flange extending horizontally inside the vehicle door, can be appreciated for example from EP-OS 00 63 325, 30 and, when compared with impact bars built up from sheet metal sections or in the form of steel tubes, have the advantage of lower weight and - especially when compared with the said sheet metal sections -simpler manufacture. 62501 - 2 - A principal disadvantage of an I-cross-section , when made in dimensions suitable for installation in vehicle doors, is its insufficient rigidity against twisting in impact deformation. An extruded, hollow profile which presents the same flange may alleviate this, but now and again breaks under high impact force.

Aware of this state of the art, the inventpr has set himself the task of improving an impact bar of the type mentioned in the introduction, so that while being of small weight it exhibits a high degree of shape stab lity and sufficient ability to compensate for the deformation energy arising, and assumes under impact a controllable shape with an undamaged inner flange. Manufacturing and handling of the impact absorber must also be simple.

The invention accordingly provides an impact bar for vehicle doors, especially for doors of passenger cars, which is produced by extrusion from a light metal alloy and can be fixed to either end of the vehicle door extending in the direction of travel in such a manner that one profile wall of the impact bar forms an inner flange facing towards the interior of the vehicle and a second profile wall of the impact bar provided at a distance therefrom forms an outer flange, characterised in that the outer flange of the impact bar is provided with a pair of edge indentations applied to opposing longitudinal edges of the flange, each of which is situated at the same distance from and on different sides of a transverse plane through the impact bar corresponding to the bearing line of a pressure body used in a load test, this transverse plane falling in the longitudinal centre of the impact bar or extending at a distance therefrom.

A single such pair of edge indentations is sufficient in the case of impact bars intended for installation in front door; a respective edge indentation of the pair is disposed on either side of the mid-point of the length of the impact bar.

By reason of their adaptation to the rear wheel arch, rear doors have a very asymmetrical shape, so that an impact usually strikes not in the mid-point of the length of the rear door impact bar, but displaced somewhat towards the wheel arch.

On this account it has proved necessary to provide the impact bar for the rear door with two pairs of edge indentations of the kind mentioned. The median planes of both pairs include between them a plane through the mid-point of the length of the impact bar Advantageously one edge indentation of each pair approximately adjoins this mid-point." The edge indentations exhibit arcuate cut edges, the depth of the edge indentation from the edge £>eing preferably a fifth of the width thereof, or about a third of the radius of curvature of the edge cut. The radius measures about 15 mm in a. preferred embodiment.

As shown by experiments, the impact absorber deforms uniformly into a curve thanks to this provision, without giving rise to a fracture. The inner •'flange is admittedly bent into a U-shape, as seen from above, but remains otherwise undamaged. A section of the outer flange has its plane displaced, that section being defined by tbe two edge indentations and standing inclined to the long axis of the flange; a favourable material flow takes place during the deformation process thanks to the edge indentations in the metal of the impact absorber, and dangerous accumulations of material in the region of the impact site are avoided. Further details as to the shape and dimensioning of the edge indentations can be gleaned from the dependent claims.

Further advantages, features and details of the invention appear from the following description of preferred embodiments and with respect to the drawings, in which Fig 1 is the front elevation of a vehicle door with an impact bar provided therein; Fig 2 is an oblique view of a cutoff portion of an impact bar with an inner and outer web, shown approx imately full size; Fig 3 is the cross-section through another impact Bar shown on an enlarged scale; - 4 - Fig 4 is a plan view on the outer flange of an embodiment of the impact bar; Fig 5 is the side elevation corresponding to Fig 4; Fig 6 is the plan view on the outer flange of another 05 embodiment of the impact bar; Fig 7 is a part of the side elevation corresponding to Fig 6; Fig 8 is an enlarged section taken from Fig 6; Fig 9 is an enlarged cross-section through Fig 8 along the 10 line IX-IX therein; Fig 10 is an enlarged plan view on a portion of the outer flange after deformation thereof; Fig 11 is the side elevation corresponding to Fig 10; Fig 12 is the cross-section through another embodiment; and 15 Fig 13 is a force/displacement diagram based on loading experiments.

An extruded aluminium section extends in the form of an impact bar 20 inside a closed lower door envelope 11 in a vehicle door 10 for a passenger vehicle which, for 20 simplicity in representation, is not illustrated. Its displacement i from the upper edge 14 of the door envelope 11 is greater than the depth of descent of a window pane 13 visible in a frame 12.

In the cross-section of the impact bar 20 as shown in 25 Fig 2, there are two parallel walls with a spacing h^ of eg 24 mm, and of thickness a, 4 mm in this example. These walls, in the installed condition of the impact b.ar 20, form an inner flange 22 directed towards the vehicle interior, as well as an outer flange 21 adjacent the outer 30 surface of the door. The outer flange, joined to the.inner flange 22 by two narrow transverse walls 24, completes a hollow section with an inner chamber 27. The width e of the chamber is 30 mm in this example.

Both the outer flange 21 and the inner flange 22 - hereinafter also called flange walls - project on both sides beyond the outer surfaces 25 of the transverse walls 24 by a distance m, and thus form flange rib sections 23 (see Fig 3, upper r i ght).

In an impact absorbing profile 20 according to Figure 3, having an overall height h of eg 27.4 mm, an overall width b of 38 mm and a height a of the profile wall long edges 19 of 4.7 mm, it can be clearly seen that a main axis A running parallel to the transverse walls 24, constitutes an axis of symmetry for the cross-section, as does a transverse axis Q which intersects said main axis. At a distance k (about 5 mm) from the transverse axis Q, on the main axis A, lies the centre M for a radius r (about 20 mm), which determines the internal cross-sectional contour of the flange walls 21, 22 which accordingly have a correspondingly curved interior surface 28; the mean thickness a^ is 3 mm in this case, so that a clear chamber height n of about 32 mm results.

The transverse walls 24 with their mean internal spacing-apart e of 22.4 mm, and a thickness f on the transverse axis Q of 1.8 mm in this example, meet the two flange walls 21, 22 with curved transition regions. The outer surface 25 and the inner surface 26 of the transverse wall 24 are mutually inclined, from that transition as far as the transverse axis Q, at angles w of 2.5*, so that a cross-section of the transverse wall 24 results which for this reason tapers towards the transverse axis Q.

The impact bar 20^ of Figs 4 and 5 has an overall length q^, for example, of about 974 mm, for installation in a front door, and the impact bar 20 of Fig 6, intended for a rear vehicle door 10, has an overall length q of about 672 mm. The impact bars 20, 20^ are each bevelled at both ends along a line E, which encloses with the lower side 29 of the bar (or its plane F) an acute - 6 - angle t. This oblique sectioning gives rise to a terminal edge 30, which is upwardly displaced by a displacement v out of the plane F of the original contour of the inner side 29 of the bar. 05 In the plan view of Figs 4 and 6 the oblique surface 31 resulting from the aforementioned bevelling can be seen. This surface is made up from the cut surfaces of the transverse walls 24 and of the inner flange 22 and is of U-shape. 10 The direction of the force arising in an impact, indicated in Fig 7 by an arrow P, makes particularly clear the above described disposition of the impact bar 20 in the construction of a door: the force P acts against the outer flange 21 which tends to deform towards the interior of the 15 car. The spacing of an assumed straight line N, along which the force P acts in this example, and which bisects the length of the profile in Fig 7, from the attachment point (the bore 36 in the inner flange 22)" is designated q2 jn Fig 7 and in this case, by way of example, measures 475 mm. 20 The profiled ends 35 which result from the described cutting plane E and the associated cropping of the inner side 29 of the bar, as has been mentioned, are fitted into grooves of the door frame (not illustrated) and secured by means of screws passing through the bores 36. 25 Reference numeral 45 in Fig 7 designates a part of the door construction which abuts and outlies that bar inner side 29.

In the outer flange 21, as shown in Fig. 6, on either side of the transverse plane defined by the straight line N, at 30 equal mean distances g of about 30 mm in this instance, a respective edge indentation 40 is applied to each flange long edge 39, ie each flange section rib 23 of the outer flange 21 contains a respective such edge indentation 40. These indentations lie however on opposite sides of said plane of 35 the line N and possess a circular arcuate cut edge 42 as - 7 - seen in plan view. The radius R thereof measures 15.5 mm in this case, with an edge depth u of about 5 mm, so that the edge width d is for example 22 mm.

In the exemplary embodiment of Figs 4 and 5 two edge 05 indentations 40, 41n are present on each long flange edge 39, on either side of the plane through the mid-point N of the profile. The edge indentation 40 which, on either edge, is adjacent the plane, is spaced apart therefrom in this instance by 12.5 mm (spacing g), and the other edge 10 indentation 40n by about 60 mm (spacing g^).

While the embodiment 20 of Figs 6 and 7 is always installed in front doors in such a way that the impact force P may be expected to act at the mid-point N of the length of the profile, both pairs of edge indentations are needed in 15 vehicle rear doors 10 (for installation on the right and on the left); according to the side installed, the impact force P acts in a line Nj or Ng (Fig 5).

Pairs of edge indentations 40, 40n in Figs 4 and 5, or 40, 40 in Figs 6 and 7 effect a favourable deformation 20 behaviour of the impact bar . 20, 20^, and it has been shown that the spacing g of 20 to 40 mm is particularly useful. In extruded hollow profiles 20, 20^, but also in I-shaped profiles 20m according to Fig 12, or other forms of other cross-sectional shapes, thanks to the edge inden-25 tations 40 there takes place a uniform deformation under impact with an approximate mean plane through the straight line N, or N£. The spacing of the line N from the line Nj or is designated s^ or s^- As shown in Figs 10 and 11, the impact bar 20 is 30 deformed under impact in such manner that the outer and inner flanges 21, 22 are bent towards the car interior. At the same time a portion of the outer flange 21 is displaced or pushed out of its long axis C (angle y of about 8* in - 8 - Fig 10). The one limit of this deformed section is approximately defined by the upper edge indentation 40 (to the right in Fig 10), from where the outer flange 21 rises in an angle y^ of for example 15*, to fall again in the region of 05 the lower edge indentation 40 at the same angle y, back to the original contour. At the deepest point of the edge indentations 40, the cut edge 42 thereof is wider, as shown especially in Fig 11. The described deformation of the outerflange 21 leads to a limiting contour G represented in 10 Fig 11, outside of whica the impact bar 22 retains its original shape almost unaltered, apart from the illustrated bending towards the car interior.

The force/displacement diagram according to Fig 12 shows a curve Z described across the bending distance S in milli-15 metres in dependence on the compressive force P (kN) as the result of a loading test of an impact bar 20 or 20^ of the above described length q or q^, anchored at the bores 36, under a mean stress, from a compression tool, of a force P of about 1.4 tonnes, at a compression velocity 20 below 12.7 mm/sec. The curve Y gives the corresponding characteristic for steel tubes, by way of conventional profiles. Curve Y shows a kink towards the displacement axis S, in the verticals X. 4 - 9 -

Claims

1. Impact bar (20, 20^, 20^) for vehicle doors (10), especially 5 for doors of passenger cars, which is produced by extrusion from a light metal alloy and can be fixed to either end of the vehicle door extending in the direction of travel in such a manner that one profile wall of the impact bar forms an inner flange (22) facing towards the interior of the vehicle and a second profile wall of the impact bar 10 provided at a distance therefrom forms an outer flange (21), characterised in that the outer flange (21) of the impact bar (20, 20f, 20m) is provided with a pair of edge indentations (40) applied to opposing longitudinal edges (39) of the flange, each of which is situated at the same distance (g) from and on different sides of a 15 transverse plane through the impact bar corresponding to the bearing line of a pressure body used in a load test, this transverse plane falling in the longitudinal centre (N) of the impact bar or extending at a distance (Sj, s2) therefrom. 20

2. Impact bar according to claim 1, characterised in that a transverse plane (Nj, N2) for a pair of edge indentations (40, 40n) extends at the same distance (Sj, s2) on either side of its longitudinal centre (N). 25

3. Impact bar according to claim 2, characterised in that one edge indentation (40) of each pair (40, 40n) contacts the longitudinal centre (N) (Fig. 4).

4. Impact bar according to claim 1 or claim 2, characterised in that 30 the ratio of its length (q) to the average distance (g) between the edge indentation (40) and its transverse plane is 30:1 to 40:1, preferably 35:1.

5. Impact bar according to claim 2 or claim 3, characterised in that 35 the ratio of its length (q^) to the average distance (s^, s2) between the straight line (N) and the plane (N^, N2) of the pairs of edge indentations (40, 40n) is 14:1 to 20:1, preferably 17:1. - 10 -

6. Impact bar according to one of claims 1 to 5, characterised by edge indentations (40, 40n) with partially circular cut edges (42).

7. Impact bar according to claim 6, characterised in that the edge depth (u) of the edge indentation (40, 40n) corresponds to a fifth of the edge width (d) or a third of the radius of curvature (R) of the cut edge (42).

8. Impact bar according to claim 6 or claim 7, characterised by a radius of curvature (R) of 15mm.

9. Impact bar for vehicle doors, especially doors of passenger cars, as claimed in claim 1 and substantially as herein described with reference to or as illustrated in the accompanying drawings. TOMKINS & CO.