GB2344922A

GB2344922A - A spine for a crash dummy

Info

Publication number: GB2344922A
Application number: GB9827701A
Authority: GB
Inventors: Bengt Morner
Original assignee: Autoliv Development AB
Current assignee: Autoliv Development AB
Priority date: 1998-12-16
Filing date: 1998-12-16
Publication date: 2000-06-21
Also published as: GB9827701D0

Abstract

A spine for a crash dummy comprises a plurality of substantially non-resilient vertebrae (19) which are aligned and which are separated by elements of resilient material. A channel extends axially of the vertebrae and a braided tube formed of diagonally woven threads (31) is located in the channel. The tube initially has a diameter smaller than that of the channel. Each end of the tube is sealed and fixed to a respective end of the spine. A fluid under pressure is then introduced into the tube (31) causing the diameter to increase and the overall length to reduce. Thus the vertebrae are biased towards each other, compressing the intermediate elements of resilient material. Two or more wires may be provided extending axially of the spine, the wires being attached to the ends of the spine and engaging each vertebra (Figure 7).

Description

Title : Improvements in or relating to a spine for a crash dummy.

Description of Invention This invention relates to a spine for a crash dummy, and to a crash dummy provided with such a spine.

A crash dummy is often used when it is desired to investigate safety features on a vehicle such as a motor car. One or more dummies are mounted in the vehicle which is then subjected to an accident situation. For example, the vehicle may be caused to impact with another vehicle or with a stationary object. The dummy may be provided with sensors to determine the nature of forces applied to the dummy and/or the movements of the dummy may be recorded, for example using a high speed camera, so that investigators can determine the nature of any injuries that would be imparted to a real human passenger in the vehicle during an accident of the type under investigation.

It is important that the dummy should respond to the forces that it experiences during the accident situation in a'life-like'manner, since otherwise investigators could be led to incorrect conclusions.

Crash dummies are now very sophisticated items of equipment, and many of the limbs of such dununies do exhibit lifelike responses in an accident situation. However, the spines of many crash dummies presently in use are of a simple, relatively stiff structure, which enables forward movement and some sideways movement. Such a spine does not truly recreate the effect of a human spine.

The present invention seeks to provide an improved spine for a crash dummy.

According to this invention there is provided a spine for a crash dummy, said spine comprising a plurality of substantially non-resilient vertebrae, the vertebrae being aligned and being separated by elements of resilient material, there being a channel extending axially of the vertebrae, there being a braided tube formed of diagonally woven threads located in the channel, which initially has a diameter smaller than the diameter of the channel, each end of the tube being sealed and being fixed to a respective end of the spine, the tube being associated with means to introduce a fluid under pressure into the tube, Preferably the inner surface of the braided tube is associated with means to provide a seal. The seal may be constituted by a sealant having elastic properties coated on the inner surface of the tube, or may be constituted by an inner tube of resilient material.

Conveniently a fluid under pressure has been injected into the braided tube to increase the diameter of the braided tube and to create an axial tension in the braided tube. Preferably the injected fluid was in the form of a curable fluid that cures to form a resilient solid, such as a curable silicone material.

Advantageously at least two external wires are provided which extend axially of the spine, each end of each wire being secured to a respective end of the spine. the wires engaging wire deflectors formed on each vertebra and being biased inwardly between adjacent vertebra by resilient elements which encircle the wires. In one embodiment there are four wires, Alternatively there may be two wires.

Conveniently the resilient elements which encircle the wires are resilient rings.

The spine may be made of vertebra of a plurality of sizes.

In a preferred embodiment each vertebra comprises a central tubular section carrying a radially outwardly directed flange.

Conveniently at least some vertebrae are provided with co-operating means which engage when adjacent vertebra become tilted relative to each other, thus imparting a twist to the spine.

The co-operating means may comprise means depending from a flange carried by an upper vertebra and upstanding means carried by a flange on a next-adjacent lower vertebra, each said means having an inclined face, the inclined faces lying in spaced apart parallel planes.

The invention also relates to a crash dummy incorporating a spine as described above.

In order that the invention may be more readily understood, and so that further features thereof may be appreciated, the invention will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a side view of part of a crash dummy provided with a spine in accordance with this invention, Figure 2 is a front view of the dummy of Figure 1, Figure 3 is a perspective view of a vertebra forming part of a spine in accordance with the invention, Figure 4 is a plan view of the vertebra of Figure 3, Figure 5 is a side view of a plurality of vertebrae and intermediate discs forming part f a spine in accordance with the invention, Figure 6 is a view of adjacent vertebrae of the spine of Figure 5 when the spine is bent, Figure 7 is a view in section, with parts cut away, of a spine in accordance with the invention, Figure 8 is a side view of the upper part of a spine which is similar to that of Figure 5 showing an attached head, and Figure 9 is a view of the upper part of the spine, as shown in Figure 8, in a different condition.

Referring initially to Figures 1 and 2 a crash dummy 1 has a spine 2, the upper end of which supports a head 3. An intermediate part of the spine carries. a chest-like torso, provided with pivoting fittings 5 adapted to be connected to arms. The lower end of the spine is connected to a box 6 to which the upper ends of two legs are connected. The dummy closely resembles a human form, and is intended to respond to the forces applied to it during a simulated accident situation in a way directly equivalent to that of the human form.

The spine 2 incorporates a plurality of vertebrae 10 of the type shown in Figures 3 and 4. Each vertebra is an element of solid substantially non resilient material provided with a central tubular portion 11. Extending radially outwardly from the centre point of the tube is a flange 12, the flange being of substantially square shape. Each of the four comers of the flange is provided with a diagonally extending slot, such as the slot 13. Each slot is provided with a transversely extending rod, such as the rod 14, which extends between the opposed sidewalls of the slot 13. The tubular central portion 11 defines an axially extending passage 15.

As shown in Figure 5 the vertebrae 10 are designed to be located adjacent each other, with the tubular central portions 11 in axial alignment. The flanges 12 are thus substantially parallel with each other, while being spaced apart.

Between each adjacent pair of vertebrae is a resilient disc 16. The disc 16 is dimensioned to be received between the opposed ends of the central tubular portions of the vertebrae and each disc is of an annular form, presenting a central aperture which is aligned with the passage defined by the central tubular portion of each vertebra. A channel is thus formed which extends axially of the spine.

As shown in Figure 5 the spine may be made of vertebrae of three different sizes. Relatively large vertebrae 17 are provided adjacent the base of the spine, medium sized vertebrae 18 in a central region and small vertebrae 19 towards the top of the spine.

Figure 6 shows two adjacent vertebrae 21,22, which are each of the form as described with reference to figures 4 and 5. The vertebrae have the same orientation, so that the flanges 12 carried by the vertebrae are aligned. An annular disc 16, which is formed of resilient material, is located between the vertebrae. A wire 23,24, is passed axially of the spine that incorporates the two illustrated vertebrae adjacent each set of the aligned slots 13. Thus four wires are provided, although only two are shown in Figure 6. A resilient ring 25 is provided which encircles the four wires at a position between each pair of vertebrae, the ring having a diameter less that the diametric spacing between two opposed rods 14 as provided on the flange'12 of the vertebrae. Thus each wire adopts a zig-zag form, with the resilient ring biasing the wire between two adjacent vertebrae resiliently inwardly. Each wire engages the transverse rods in the slots 13 with which it is aligned, with the rods 14 acting as wire deflectors.

Referring now to Figure 7 a braided tube 30 formed of diagonally woven threads extends axially through the channel constituted by the aligned central passages 15 of the central tubular portions 1 lof the vertebrae of the spine. It is a property of a diagonally woven braided tube that when the tube is inflated, while the diameter of the tube will increase, the length of the tube will decrease, as a consequence of the diagonal weaving of the tube. The diameter of the braided tube in its initial state is less than the diameter of the channel defined by the aligned passages 15.

The inner surface of the braided tube is associated with means to provide a sealing effect. Thus the inner surface of the braided tube may be coated with a sealant that has elastic properties, or an inner tube 31 of rubber or some other resilient material may be used.

At the lower end of the spine the braided tube 30 is secured to the lowcrmost vertebra 17 by means of an expansion device 32. The expansion device has a washer 33 that engages the terminal vertebra 30. A bolt 34 passes through a central aperture in the washer and extends into the braided tube. The bolt 34 carries a nut 35 which engages the inner wall of the tube 30 and is a friction fit, together with the tube 30, within the axial passage 15 of the terminal vertebra 17. Trapped between the nut 35 and the flange 33 is a bung of rubber or rubber like material. As the bolt 34 and nut 35 are tightened, so the bung 36 is deformed so that it expands outwardly and forms a tight seal between the tube 30 and the passage 15 of the terminal vertebra 17. The expansion device 32 may incorporate a one-way filling valve, for a purpose that will be described below. The filling valve 37 may be incorporated into the bolt 34.

At the upper end of the spine the braided tube is secured to the uppermost vertebra 19 by means of a corresponding expansion device 38 that has flange 39 engaging the terminal vertebra 19.

As can be seen from Figure 7 the ends of the wires 23,24 are secured to the ends of the spine by being fastened to the flanges 33,39.

The one way filling valve 37 is intended to be used to fill the interior of the braided tube 30 with a fluid which in a preferred embodiment will subsequently cure to form a resilient solid element A curable silicone rubber is the preferred material. As the liquid is injected under pressure into the braided tube 30, the braided tube will expand radially outwardly, and as a consequence will tend to shorten in length. As the opposed ends of the tube are fixed in position an axial tension is developed in the braided tube tending to draw the ends of the tube inwardly towards each other. Thus an axial compressing tension is applied to the spine, and the discs 16 between the adjacent vertebrae become slightly compressed. After the silicone rubber cures the discs are retained in their compressed state.

The combination of the wires 23,24 and the resilient rings 25 provide the spine with a lifelike response to a bending of the spine. As a consequence of the presence of the braided tube any twisting of the spine will result in a shortening of the spine, which is a characteristic of the spine of a human being. Indeed it has been found that spine, as described will resist many movements such as bending, shearing and twisting in a lifelike manner.

Figures 8 and 9 illustrate the upper part of a modifie spine in accordance with the invention. In this embodiment a sideways bending of the upper part of the spine will cause the spine to twist. In the embodiment of Figures 8 and the flange 40 of the uppermost vertebra carries, on each side of the spine (only one side is shown in the Figures) a depending finger 41which terminates with an inclined face 42. The flange 43 of the next adjacent vertebra carries an upstanding finger carrying a co-operating inclined face 46. The inclined faces 42,46 lie in parallel planes and are spaced slightly apart. The flange 43 also carries a depending finger 47 which co-operates in a similar manner with an upstanding finger 48 on the flange of the next adjacent vertebra. If the portion of the spine as shown is bent sideways, for example if the head 3 is tilted to the right, the adjacent vertebrae become titled relative to each other. Thus the inclined faces 42,46 of the fingers 41,45 will be brought into engagement, and will act as co-operating cam faces, causing the illustrated part of the spine to twist. The fingers 47 and 48 will also co-operate in this way, giving a noticeable twist to the upper part of the spine as a consequence of the bending of the upper part of the spine.

As described above the co-operating fingers will be provided on cither side of the spine, so that a tilting of the head in either direction will generate an appropriate twisting of the spine. The spine is thus very similar to the spine of a human.

Whilst the invention has been described above with specific reference to an embodiment in which there are four wires extending axially of the spine, it is envisaged that in an alternative practical embodiment, only two wires may be provided, one on each side of the spine. The vertebrae may thus be redesigend so that each vertebra only has two opposed wire deflectors.

Claims

CLAIMS.

1. A spine for a crash dummy, said spine comprising a plurality of substantially non-resilient vertebrae, the vertebrae being aligned and being seperated by elements of resilient material, there being a channel extending axially of the vertebrae, there being a braided tube formed of diagonally woven threads located in the channel, which initially has a diameter smaller than the diameter of the channel, each end of the tube being sealed and being fixed to a respective end of the spine, the tube being associated with means to introduce a fluid under pressure into the tube.

2. A spine according to claim 1 wherein the inner surface of the braided tube is associated with means to provide a seal.

3. A spine according to claim 2 wherein the seal is constituted by a sealant having elastic properties coated on the inner surface of the tube.

4. A spine according to claim 2 wherein the seal is constituted by an inner tube of resilient material.

5. A spine according to any one of the preceding claims wherein a fluid under pressure has been injected into the braided tube to increase the diameter of the braided tube and to create an axial tension in the braided tube.

6. A spine according to claim 5 wherein the injected fluid was in the form of a curable fluid that cures to form a resilient solid.

7. A spine according to claim 5 or 6 wherein the fluid is a curable silicone material.

8. A spine according to any one of the preceding claims wherein at least two external wires are provided which extend axially of the spine, each end of each wire being secured to a respective end of the spine, the wires engaging wire deflectors formed on each vertebra and being biased inwardly between adjacent vertebra by resilient elements which encircle the wires.

9. A spine according to claim 8 wherein there are four wires.

10-A spine according to claim 8 or 9 wherein the resilient elements which encircle the wires are resilient rings.

11. A spine according to any one of the preceding claims made of vertebra of a plurality of sizes.

12. A spine according to any one of the preceding claims wherein each vertebra comprises a central tubular section carrying a radially outwardly directed flange.

13. A spine according to any one of the preceding claims wherein at least some vertebrae are provided with co-operating means which engage when adjacent vertebra become tilted relative to each other, thus imparting a twist to the spine.

14. A spine according to claim 13 wherein said co-operating means comprise means depending from a flange carried by an upper vertebra and upstanding means carried by a flange on a next-adjacent lower vertebra, each said means having an inclined face, the inclined faces lying in spaced apart parallel planes.

15. A spine substantially as herein described with reference to and as shown in Figures 1 to 7 of the accompanying drawings.

16. A spine substantially as herein described with reference to and as shown in Figures 1 to 7 as modified by Figures 8 and 9 of the accompanying drawings.

17. A crash dummy incorporating a spine according to any one of the preceding claims.

18. Any novel feature or combination of features disclosed herein.