Rosenzweig, Nachum
| 1. | A multidirectional energy absorbing device capable of absorbing energy received from a wide range of impact directions comprising: at least one impact receiving element for receiving impact; and a plurality of unidirectional energy absorbing devices pivotably connected between said impact receiving element and a body to be decelerated; wherein at least two of said unidirectional energy absorbing devices are connected to form an angle therebetween. |
| 2. | A multidirectional energy absorbing device according to claim 1 and wherein said unidirectional energy absorbing devices are connected to each other in a truss formation. |
| 3. | 3• multidirectional energy absorbing device according to claim 2 and wherein said truss formation is a trianglebased three dimensional truss formation. |
| 4. | A multidirectional energy absorbing device according to claim 3 and wherein for every triangle of said truss formation, there are at least two unidirectional EA devices. |
| 5. | • A multidirectional energy absorbing device according to claim 1 and also comprising hinges for pivotably attaching said unidirectional energy absorbing devices to said impact receiving surface and to said body to be decelerated. |
| 6. | A multidirectional energy absorbing device according to claim 5 and wherein each hinge is comprised of a joint selected from the group consisting of a pin or a ball and socket joint. 1 2 7* A multidirectional energy absorbing bumper 3 for use with a vehicle, the bumper comprising: 4 a plurality of unidirectional energy 5 absorbing devices pivotably connected between said 6 bumper and said vehicle to be decelerated; . |
| 7. | wherein at least two of said unidirectional δ energy absorbing devices are connected to form an angle 9 therebetween .*& 10. |
| 8. | 11 δ. A multidirectional energy absorbing bumper 12 according to claim 7 and wherein said unidirectional 13 energy absorbing devices are connected to each other in 14 a truss formation. *& 15. |
| 9. | 16 9* A multidirectional energy absorbing bumper 17 according to claim 8 and wherein said truss formation Iδ is a trianglebased three dimensional truss formation. *& 19. |
| 10. | A multidirectional energy absorbing bumper 21 according to claim and wherein for every triangle of 22 said truss formation, there are at least two 23 unidirectional EA devices. 24 25 11. A multidirectional energy absorbing bumper 26 according to claim 7 and also comprising hinges for 27 pivotably attaching said unidirectional energy 2δ absorbing devices to said impact receiving surface and 29 to said body to be decelerated. *& 30. |
| 11. | A multidirectional energy absorbing bumper 32 according to claim 11 and wherein each hinge is 33 comprised of a joint selected from the group consisting 3 of a pin or a ball and socket joint. *& 35. |
| 12. | 36 13* A vehicle comprising: 37 a body; and 38 a multidirectional energy absorbing bumper attached to said body, the bumper comprising: a plurality of unidirectional energy absorbing devices pivotably connected between said bumper and said body to be decelerated; wherein at least two of said unidirectional energy absorbing devices are connected to form an angle therebetween. |
| 13. | A multidirectional energy absorbing pod for use with a landing device, the pod comprising: a plurality of unidirectional energy absorbing devices pivotably connected between said pod and said device; wherein at least two of said unidirectional energy absorbing devices are connected to form an angle therebetween. |
| 14. | A multidirectional energy absorbing pod according to claim 14 and wherein said unidirectional energy absorbing devices are connected to each other in a truss formation. l6. |
| 15. | A pod according to claim 15 and wherein said truss formation is trianglebased three dimensional truss formation. |
| 16. | A pod according to claim 14 and also comprising hinges for pivotably attaching said unidirectional energy absorbing devices to said impact receiving surface and to said body to be decelerated. |
| 17. | A pod according to claim 17 and wherein each hinge is comprised of a joint selected from the group consisting of: a pin or a ball and socket joint. |
| 18. | A multidirectional energy absorbing fence attached to a roadside obstruction, the fence comprising: a plurality of unidirectional energy absorbing devices pivotably connected between said fence and said roadside obstruction; wherein at least two of said unidirectional energy absorbing devices are connected to form an angle therebetween. |
| 19. | A multidirectional energy absorbing fence according to claim 19 and wherein said unidirectional energy absorbing devices are connected to each other in a truss formation. |
| 20. | A fence according to claim 20 and wherein said truss formation is trianglebased three dimensional truss formation. |
| 21. | A fence according to claim 1 and also comprising hinges for pivotably attaching said unidirectional energy absorbing devices to said impact receiving surface and to said body to be decelerated. 23* A fence according to claim 22 and wherein each hinge is comprised of a joint selected from the group consisting of: a pin or a ball and socket joint. |
3 l ENERGY ABSORBING DEVICE
5
6 The present invention relates to energy
7 absorbing devices generally and to wide angle energy
8 absorbing devices in particular.
9 1G 11 12
13 Energy absorbing devices are known in the
1*4 art. They are operative to absorb energy in the
15 presence of an impact force and, as a result of the lβ energy absorption, to provide a decelerating force of a
17 tolerable magnitude to a body which the energy
18 absorbing device is shielding.
19 Energy absorbing devices have a well-defined 2G direction of action, along which they resist the impact
21 force. However, if the impact occurs along a line other
22 than their direction of action, the devices perform
23 poorly and absorb only a very small portion of their 2*4 maximal amount of energy absorption.
25 Fig. PA-1 illustrates the operation of a
26 prior art energy absorption device 2, attached to a
27 body -4 which device 2 is to shield. Stabilizing fins 5
28 are shown which stabilize the device 2 in the event of
2 an impact. If an impact force, P, is along an axis 6
30 of symmetry of device 2, which axis is the direction of
31 action, the device properly strokes, thereby reducing
32 its length from a point a to a point a' while absorbing
33 its designated amount of kinetic energy.
3*4 If, however, impact force P impacts
35 laterally, at an angle a to the axis 6 as shown in Fig.
36 PA-2, the device 2 does not absorb energy through
37 compression as it is designed to do. Instead, the 3δ bending moment received may cause an unwanted collapse
of the device 2 and therefore, only a small amount of energy can be absorbed. For example, many automobile bumpers are now fitted with energy absorbing devices. These devices are designed to be operative when an impact is received in a direction normal to the front surface of the bumper. Unfortunately, bumpers can be hit at any angle between G to lδθo to the bumper. U.S. Patents 4,031,978 and 4,182,529 describe energy absorbing systems for a vehicle which absorbs energy and allows a high strength bumper to be deflected without being deformed. The system described in U.S. Patent 4,182,529 includes a first EA unit coupled between the vehicle engine and a center portion of the bumper, two EA units, one on each side of the vehicle, coupled between a frame' around the vehicle engine and the outer ends of the bumper and pivotal connections between the EA units and the bumper and the EA units and the frame and engine. The pivotal connections enable the bumper to swing to a deflecting position upon engagement with an obstruction. The EA units, during an engagement, absorb energy. However, the engine frame constrains the EA units to deflect a predefined amount. If an outer EA unit is deflected toward the engine, it will encounter the frame before reaching its full rotation angle. If the force causing the deflection is strong enough, the EA unit will be pushed against the frame, typically causing the EA unit to bend and not to absorb energy. DE 2,839.718 to Malik describes a crash protection system having tapered front and rear ends. The bumper is pivoted about a vertical axis at each end of the vehicle and is supported by angled EA devices. In a head-on or lateral collision, the force of the collision will be passed directly to the vehicle body since the bumper does not completely isolate the body from an uπdesired impact. U.S. 3.656,7 2 to Tavano describes a bumper
including EA units attached to the bumper via ball and socket joint. The ball and socket joint enables the EA units to be impacted in a direction other than along their axes of symmetry. However, a lateral impact will apply a bending moment on the EA units. U.S. Patent 3.331.^60 to Bacon describes a land vehicle provided with collision resistant safety features. The vehicle includes wheels attached to a pivotably interconnected contractible/expandible mainframe. The mainframe includes laterally and longitudinally positioned EA units wherein the end of one unit is connected to the end of the other unit via pivotable rigid struts. The vehicle can absorb lateral and longitudinal impact forces but cannot completely absorb impact forces received in any other direction. EP Patent Publication 246,545 to Magni describes a guard rail formed of a plurality of movable EA units mounted next to each other, each being mounted on pivot pins. The pivot pins are located in the center of the EA units and are attached to the ground. The EA units, when impacted, can rotate due to the pivot pins; however, the impacted units may become disengaged from their neighbors. Furthermore, the impact force typically causes a bending moment which tends to deform the EA units and may cause their pivot pins to be dislodged from the ground.
It is, therefore, an object of the present invention to provide an energy absorbing device capable of absorbing energy within a wide range of impact angles . There is therefore provided, in accordance with an embodiment of the present invention, a multidirectional energy absorbing device capable of absorbing energy received from a wide range of impact directions. The device includes at least one impact receiving element for receiving impact and a plurality of unidirectional energy absorbing devices pivotably connected between the impact receiving element and a body to be decelerated, wherein at least two of the unidirectional energy absorbing devices are connected to form an angle therebetween. There is further provided, in accordance with an embodiment of the present invention, a multidirectional energy absorbing bumper for use with a vehicle. The bumper includes a plurality of unidirectional energy absorbing devices pivotably connected between the bumper and the vehicle to be decelerated wherein at least two of the unidirectional energy absorbing devices are connected to form an angle therebetween. There is also provided, in accordance with an embodiment of the present invention, a vehicle including a body and a multidirectional energy absorbing bumper attached to the body. The bumper includes a plurality of unidirectional energy absorbing devices pivotably connected between the bumper and the body to be decelerated, wherein at least two of the unidirectional energy absorbing devices are connected to form an angle therebetween. There is additionally provided, in accordance with an embodiment of the present invention, a multidirectional energy absorbing pod for use with a landing device. The pod includes a plurality of
unidirectional energy absorbing devices pivotably connected between the pod and the device, wherein at least two of the unidirectional energy absorbing devices are connected to form an angle therebetween.
There is further provided, in accordance with an embodiment of the present invention, a multidirectional energy absorbing fence attached to a roadside obstruction. The fence includes a plurality of unidirectional energy absorbing devices pivotably connected between the fence and the roadside obstruction, wherein at least two of the unidirectional energy absorbing devices are connected to form an angle therebetween.
Additionally, in accordance with an embodiment of the present invention, the unidirectional energy absorbing devices are connected to each other in a truss formation. The truss formation can be two- or three-dimensional and is preferably triangle based.
Moreover, in accordance with an embodiment of the present invention, for every triangle of the truss formation, there are at least two unidirectional EA devices .
Finally, in accordance with an embodiment of the present invention, the device of the present invention includes hinges for pivotably attaching the unidirectional energy absorbing devices to the impact receiving surface and to the body to be decelerated. Each hinge is typically comprised of a joint selected from the group consisting of a pin joint, a ball and socket joint or any kind of joint that transfers only a tensile or a compressive force, but not a bending moment, to the unidirectional energy absorbing device.
The present invention will be understood and appreciated from the following detailed description, taken in conjunction with the drawings in which: Figs. PA-1 and PA-2 are illustrations of prior art unidirectional energy absorption . devices receiving a headon and lateral impact force, respectively; Figs. 1A and IB are illustrations of a multidirectional energy absorption device constructed and operative in accordance with the present invention, wherein Fig. 1A illustrates the absorption of a force normal to the direction of a body to be decelerated and Fig. IB illustrates absorption of a force at a non- normal angle to the body; Fig. 1C is an illustration of an embodiment of the device of Fig. 1A forming a non-equilateral triangle; Fig. 2 is an illustration of a linear energy absorption device useful in the device of Figs. 1A and IB; Fig. 3 s an illustration of a further alternative embodiment of the device of Fig. 1A forming two triangles; Figs. 4A and 4B are respectively detailed top and side view illustrations of the embodiment of Fig. 3; Fig. 5 is an illustration of a multidirectional energy absorbing bumper on an automotive vehicle constructed in accordance with the present invention; Fig. 6 is a cross-sectional top view illustration of a multidirectional energy absorbing safety fence around a bridge support column constructed in accordance with the present invention; Figs. 7A and 7B are illustrations of multidirectional energy absorbing pods for parachuting
payloads constructed in accordance with the present invention; and Figs. 8A, 8B, 8C, 8D, 8E and 8F are illustrations of alternative devices formed in three- dimensional truss shapes.
1 2
3 Reference is now made to Figs. 1A, IB, 1C and
4 2 which illustrate the multidirectional energy
5 absorbing device of the present invention. The device
6 comprises a multiplicity of linear energy absorbing
7 (EA) devices 10, formed into a truss formation. The EA
8 devices 10 can be any type of compressive linear EA de-
9 vice, such as those described in U.S. Patents 0 3.236,333, 3.380,557 or 3.428,150 or any of the ones 1 described in U.S. Patent 5.074,391 to the Applicant. 2 U.S. Patent 5,074,392 is incorporated herein by 3 reference. An example linear EA device 10 is shown in 4 detail in Fig. 2. 5 The EA devices 10 are connected to each other 6 and to a body 12 to be decelerated, via low friction 7 hinges 14, such as low friction pins or spherical 8 sockets. In accordance with the present invention, the 9 hinges 14 enable the EA devices 10 to not only absorb 0 energy but also to pivot in response to an impact force 1 P. 2 The EA devices 10 are designed to stroke upon 3 reaching a compressive force F. Hinges 14 ensure that 4 the compressive force F is not accompanied by a bending 5 moment. The EA devices may be subject to an impact 6 force which can be either tensile or compressive; 7 however, they will only absorb energy if the impact 8 force they receive is compressive. 9 In this way, energy from impact force P of 0 any direction can be absorbed. 1 A truss is defined, in Webster' s Third Ne 2 International Dictionary, Unabridged, 1981, published 3 by Merriam-Webster, as "an assemblage of members (as *-* beams, bars, rods) typically arranged in a triangle or 5 combination of triangles, to form a rigid framework (as 6 for supporting a load over a wide area) that cannot be 7 deformed by the application of an external force 8 without deformation of one or more of its members".
A simple multi-directional device is, as shown in Figs. 1A and IB, formed in a triangle formed of three hinges l4 and at least two EA devices 10. The corners of the triangle are denoted A, B and C. In Fig. 1A, impact force P is shown impacting the multidirectional device at corner B, in a direction normal to body 12. It will be appreciated that, in this example, the impact force P is received equally by both devices 10. In response to the impact force P, both devices 10 begin compression along their axes of symmetry 16. As they stroke, the angle between them increases and corner B moves to location B' . The new configuration is indicated in Fig. 1A with dotted lines. In Fig. IB, impact force P is shown impacting the multidirectional device at corner B, at an impact angle θ to the direction of body 12. In this Figure, the righthand EA device is labelled 10a and the lefthand EA device is labelled 10b. When the force in EA device 10b is less than |-F| , device 10b will begin to shorten while absorbing impact energy. Because of hinges 14, corner B will pivot to the left until the force in EA device 10b reaches -F. During the compression of EA device 10b, EA device 10a will continue to pivot about corner C. EA device 10a will remain a structural truss member, if the force it feels is a small compressive force or if it is any tensile force. If the compressive force it feels reaches -F, then EA device 10a will compress, thereby adding to the energy absorption of the . entire device. The final location of the device is shown by dotted lines. For certain angles θ greater than 90o and when the compressive force on the EA device 10a reaches -F, the EA device 10a will compress and EA device 10b will act as the structural truss member. The multidirectional EA devices of Figs. 1A
and IB are shown as generally equilateral triangles . This configuration enables ' both EA devices 10 to respond in a headon (θ is near 90o) impact situation, such as is shown in Fig. 1A. Additionally, in a lateral impact situation, such as is shown in Fig. IB, the pivoting of the triangle enables EA device 10b to approach an upright position (e.g. angle B 'AC approaches 90o) which enables EA device 10b to be more completely consumed. However, other configurations are possible. As shown in Fig. IC, the multidirectional EA device of the present invention can be formed of a non- equilateral triangle in which EA device 10a is longer than EA device 10b. In this embodiment, once corner B is generally colinear with corners A and C, as shown by corner B' , EA device 10b becomes in'operative for energy absorption. The length between corners A and B' is not available for energy absorption except from a pure lateral direction. For this reason, this embodiment is not considered preferable. Fig. 2 illustrates an example EA device 10. The device 10 comprises a discrete elongate solid body 20, which can be ductile, crushable or both, which receives an impact force. Device 10 also comprises a rigid element 22 defining a plurality of restricted spaces 24. Body 20 can be ductile, crushable or both and rigid element 22 can include a die element. When the body 20 is subjected to a force which induces it to pass through the restricted spaces 24, body 20 is pushed through the spaces 24 via extrusion, crushing, splitting, friction and/or plastic flow. The device 10 additionally includes a transmission element 26 for transmitting impact energy incident on the device to the body. In accordance with a preferred embodiment of the present invention, transmission element 26 and rigid element 22 each additionally comprise an integrally attached hinge element 27 forming a part of
hinge 14. In Fig. 2, the hinge element 27 is illustrated as a flange 28 having a hole 30 through which a pin (not shown) can be placed. Alternately, hinge element 27 could be the spherical part of a ball and socket joint. It will be appreciated that, in accordance with the present invention, any suitable hinge element 27 can be integrally attached ■ to any suitable linear EA device 10. Reference is now made Figs. 3. ^A and 4B which illustrate a multidirectional EA device 3 formed of two generally equilateral triangles. Fig. 3 is a schematic illustration, Fig. 4A is a top view and Fig. 4B is a side view of an implementation of the device of Fig. 3* The device 32 comprises four linear EA devices 40, labelled 4θa, 4θb, 40c and 4θd, and five hinges 44 at the corners of the triangles, labelled E, F, G, H and I. Additionally, the device 3 comprises a body 42 to be decelerated and an impact surface 46 which is impacted by impact force P at an impact angle θ to surface 46. As shown in Fig. 4B, in this embodiment, hinges 44 are formed of flanges, such as flanges 28 (Fig. 2) , through which a pin 48 is placed. Hinges 44 further comprise hinge support elements 50. typically having a U profile and a hole (not shown) through which is placed pin 48. Hinge support elements 50 are connected to body 42. In device 32, the EA devices 4θa and 4θc are operative to absorb energy from impact forces P arriving at impact angles θ less than 90o and EA devices 4θb and 4θd are operative to absorb energy from impact forces P arriving at impact angles θ greater than 0o. For headon or almost headon impact forces, all EA devices 40 are operative to absorb energy. The situation with θ greater than 90o can be seen from the dotted lines in Fig. 3 which also indicates the new locations F' and H' of corners F and
H after impact. EA devices 4θb and 4θd are compressed while EA devices 4θa and 4øc act as structual members and just pivot to new locations. It should be noted that, due to the impact, the impact surface 46 has also moved in the direction of the impact force. This is advantageous in that it enables the impacting object to slip away and disengage contact. It will be appreciated that the device 3 responds selectively to the impact angle θ. For impact angles close to 90o (headon collisions) , the multidirectional EA device requires a large force to cause compression, thereby absorbing a lot of energy, a generally desirable result due to the seriousness of headon collisions. For smaller impact angles, close to 0o or lδøo, the device requires less force to cause compression. However, in such collisions, there is less danger. The selectivity of device 32 is shown in Table 1 below, wherein -P/F is the relative force required to cause the device of Fig. 3 to collapse where P is the impact force and -F is the force at which each of the EA devices 40 begin compression.
Table 1: Selective Directional Response
θ(o): 0 15 30 5 60 75 85 -P/F: 2.0 1.8 1.7 1.8 2.0 2.4 3-0
θ(o): 90 105 120 -P/F: 3-5 2.4 2.0
It will be noted that the response is symmetric about an impact angle of 90o. D e to the changing geometry of device 32, the force at which it resists changes during an impact. For example, in the headon impact shown in Fig. 1A, the force at which the multidirectional EA device resists
decreases as stroking proceeds since the EA devices 10 approach a horizontal configuration. This can be corrected, if desired, by adding a central EA device 10. Reference is now made to Figs. 5. 6, 7A and 7B which illustrate applications of the multidirectional EA device of the present invention. Fig. 5 illustrates multidirectional energy absorbing bumpers 60 forming part of an automotive vehicle 62. The bumpers 60 typically comprise a plurality of multidirectional EA devices and are operative to absorb impact forces having headon and non-headon impact angles. Fig. 5 shows four multidirectional EA devices 32 placed in the four corners of the vehicle 62. It will be appreciated that any shape multidirectional EA device can be utilized and that any number of EA devices can be used. However, four devices 32, as shown, are minimally necessary. It will further be appreciated that the bumpers 60 will move laterally during an impact caused by the lateral movement of the multidirectional EA devices. This feature possibly may aid in deflecting the obstructing object and thus, may prevent a more severe engagement of the fronts of the colliding objects . Fig. 6 is a cross-sectional top view of a multidirectional energy absorbing fence 70 surrounding a bridge support column 72. The fence 70 is operative to protect vehicles upon colliding with bridge support columns and barriers when the direction of impact is not known a priori. The fence 70 comprises a plurality of multidirectional EA devices 7 , placed in close proximity to each other. The EA devices 74 typically comprise three generally equilateral triangles and an impact surface 76. Figs. 7A and 7B respectively illustrate
multidirectional EA pods 80 for parachuting payloads 82 before and after the payloads 82 land. In parachuting and airdropping of payloads, the touchdown impact N is accompanied by a horizontal velocity, such as caused by wind drift W. The horizontal velocity with respect to the ground generates a horizontal drag G. These forces result in a resultant impact force P with a ■ non~90o impact angle. The pods 80 comprise a multiplicity of multidirectional EA devices 84, typically having two or more generally equilateral triangles, which compress and move laterally in response to the resultant impact force P. It will be appreciated that the multidirectional EA device of the present invention is formed of a multiplicity of linear EA devices in any constrained geometric shape, such as a truss, which can be a triangle or a combination of triangles. The truss shape can be two- or three-dimensional as desired. Reference is now briefly made to Figs. 8A , 8B, 8C, 8D, 8E and 8F which illustrate possible three- dimensional configurations. As can be seen, Fig. 8A is a pentagonal pyramid, Fig. 8B is a hexagonal pyramid, Fig. 8C is a pyramid and Fig. 8D is a tetrahedron. Figs. 8E and 8F are other possible three-dimensional configurations . It will be appreciated that the three- dimensional trusses cannot be assembl'ed by joining the unidirectional EA devices 10 and the structural members at a single point due to the fact that the pivotal pins or spherical sockets have a finite size. To create a node of a three-dimensional truss, the axes of symmetry o all of members connected at the node must pass through the mathematical location of the node. It will be appreciated that the unidirectional EA devices 10 can be formed of devices, described in U.S. Patent 5.074,391 to the Applicant, which begin deformation in either the presence of
tensile or a compressive force. It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention is defined only by the claims that follow: