WO2009148365A1

WO2009148365A1 - Crash absorber for a vehicle and a vehicle comprising a crash absorber

Info

Publication number: WO2009148365A1
Application number: PCT/SE2008/000380
Authority: WO
Inventors: Lena Larsson
Original assignee: Volvo Lastvagnar Ab
Priority date: 2008-06-04
Filing date: 2008-06-04
Publication date: 2009-12-10

Abstract

The invention relates to a crash absorber (10) comprising an absorber structure (20) and a rod structure (30) interacting with the absorber structure (20) in case of an impact, the rod structure (30) comprising at least one longitudinally extending rod member (34) having its forward portion (31) adapted to be secured to a vehicle bumper (12). The absorber structure (20) is in operational connection to the at least one rod member (34) so that when the at least one rod member (34) is moving towards the absorber structure (20) an expandable portion (26) of the absorber structure (20) is expanded by action of the at least one rod member (34).

Description

D E S C R I P T I O N

Crash Absorber for a Vehicle and a Vehicle comprising a Crash Absorber

The invention relates to a crash absorber for a vehicle and a vehicle comprising a crash absorber according to the preambles of the independent claims.

Energy absorbing crash absorbers are known in the art. Crash absorbers are employed for reducing damage to a vehicle and its passengers when a crash occurs. Such crash absorbers typically comprise crash structures which can be deformed, thus transforming at least a part of the vehicle's kinetic energy into deformation energy. Another task of crash absorbers is to provide survival space for passengers in the vehicle's cabin by providing deformation in dedicated areas around the cabin. In trucks, particularly, the space available for such deformation areas is restricted.

In GB 876 341 a crash absorber is disclosed with corrugated absorber structures on the front and aft of slideably mounted tubes connected to a front bumper. Kinetic energy is absorbed by compression of the corrugated. An elastomeric absorber structure is disclosed in US 4,624,493. A longitudinally extending tubular member can side into an elastomeric bushing which is surrounded by a cylinder wall. A preloaded spring is concentrically disposed between the forward end of the bushing and a frame part. A predetermined impact load on the bumper causes the bushing to elastically deform in a radially outward manner such that upon contacting the cylinder wall a permanent set corrugated-like undulation is formed resulting in the dissipation of the impact kinetic energy. The coil spring expands to accommodate the reduced length of the bushing thereby returning the bumper to its original position. After a plurality of impacts the deformed bushing may be replaced.

It is an object of the invention to provide an improved crash absorber which is particularly useful for saving space in a vehicle structure. It is another object of the invention to provide an improved vehicle comprising a crash absorber.

The objects are achieved by the features of the independent claims. The other claims and the description disclose advantageous embodiments of the invention.

According to a first aspect of the invention, a crash absorber is proposed, comprising an absorber structure and a rod structure interacting with the absorber structure in case of an impact, the rod structure comprising at least one longitudinally extending rod member having its forward portion adapted to be secured to a vehicle bumper. The absorber structure is in operational connection to the at least one rod member so that when the at least one rod member is moving towards the absorber structure an expandable portion of the absorber structure is expanded by action of the at least one rod member.

The invention is particularly useful in a truck. The crash zone where the kinetic energy of a crash impact can be absorbed can favourably be moved backwards away from the driver cabin. This allows for saving space for other vehicular components and aggregates, such as coolant airflow, steering devices and the like. Being able to move the crash zone backwards means also being able to move weight backwards which results in a better stability of the truck. The impact can be controlled so that the load acing on the crash absorber components results in less damage to the components.

Preferably, the absorber structure can comprise an interface member to which the rod structure makes contact in case of a crash. The rod structure can be in contact with the interface member before the crash or be arranged in a way to make contact only during the crash, depending on the chosen design for the crash absorber.

The expandable portion can particularly comprise a corrugated structure. Alternatively or additionally, the expandable portion can comprise a spring coil structure. The expandable portion is expanded when the rod structure makes contact with the interface member. Particularly, the expandable portion can be adapted to be attached to a vehicle frame or chassis. The absorber structure can be in a stable contact to the vehicle frame or chassis which supports the action of the absorber structure.

Favourably, the expandable portion can comprise a hardened Boron-alloy steel. A Boron alloyed steel is a superhard steel characterized by a tensile strength between typically 1300 and 1500 Newton/mm². This kind of material can absorb a lot of energy when deformed, e.g. bent or corrugated, and very high forces are necessary to break such material. Moderate forces applied to the bumper and to the crash structure accordingly will not drive the e.g. corrugated crash absorber into a plastic loading area. Hence the bumper can spring back in its normal position after an impact with moderate forces. High forces applied to the bumper will drive the crash absorber into plastic loading area, hence the bumper can absorb energy and will stay in a recessed position after impact due to the elongation of the crash structure in the hidden rear of the crash absorber. A stopper element can be provided to stop a lateral movement of the rod member towards the absorber structure. The stopper element can protect the absorber structure from overload during crash when the rod structure is sliding towards the absorber structure. When a head member of the rod structure comes in contact with the stopper element, the sliding movement of the rod structure is stopped at once. The distance between the normal position of the head member and the stopper element is chosen in a way that a reasonable amount of kinetic energy has been absorbed when the head member reaches the stopper element. The distance is more or less the increase in length which is experienced by the absorber element when the rod member pushes the interface member in its sliding direction.

The absorber structure can be embodied e.g. as a tubular jacket which at least partially surrounds the at least one rod member with its expandable portion. Preferably, the interface member can be a bottom part of the tubular jacket. By moving the bottom part away from the opening of the tubular jacket, the walls of the tubular jacket are longitudinally expanded, as the open side of the tubular jacket is attached to the vehicle frame or chassis.

According to a favourable embodiment, two rod members can be provided, wherein each is in operational contact with one absorber structure. The arrangement can be positioned symmetrically to a longitudinal axis of the vehicle.

Alternatively, the rod structure can comprise one rod member provided with one absorber structure and guiding rods parallel to the one rod member. The one rod member can be arranged collinear with a longitudinal vehicle axis.

According to a further aspect of the invention, a vehicle comprising a crash absorber with one or more absorber structures is proposed, the crash absorber being embodied as set forth above. The vehicle can be particularly a truck or a trailer or a bus. The invention can also be used for passenger cars or other vehicles.

Preferably, the one or more absorber structures can comprise one or more expandable portions.

The crash absorber can be provided for the front of the vehicle only. Alternatively, one or more absorber structures can be provided both at a vehicle front end and at a vehicle rear end. The one or more absorber structures can protrude into an inner space area behind a vehicle axle. The crash absorber can be attached to a vehicle frame or chassis with its first end proximate to a vehicle bumper at an inner space behind a vehicle axle, giving a stable mounting of the crash absorber.

Favourably, one or more crash absorbers can be arranged at one or more sides of the vehicle.

A stopper element can be provided as a catch for a head element of a rod structure interacting with the absorber structure of the crash absorber.

According to a favourable development, a vehicle bumper and the crash absorber can comprise hardened Boron-alloy steel.

The present invention together with the above-mentioned and other objects and advantages may best be understood from the following detailed description of the embodiments, but not restricted to the embodiments, wherein is shown schematically:

Fig. 1 a first embodiment of a preferred vehicle having a crash absorber according to the invention comprising two absorber structures; Fig. 2 a second embodiment of a preferred vehicle having a crash absorber according to the invention comprising a central absorber structure; Fig. 3a, 3b a crash structure in a normal position (Fig. 3a) and after high impact (Fig.

3b);

Fig. 4 an alternative embodiment of an absorber structure comprising a spring coil; and

Fig. 5 an alternative embodiment of an absorber structure comprising a one sided expandable portion.

In the drawings, equal or similar elements are referred to by equal reference numerals. The drawings are merely schematic representations, not intended to portray specific parameters of the invention. Moreover, the drawings are intended to depict only typical embodiments of the invention and therefore should not be considered as limiting the scope of the invention.

Fig. 1 illustrates a first embodiment of a preferred crash absorber 10 in a preferred vehicle 50. The crash absorber 10 comprises a rod structure 30 and an absorber structure 20. The rod structure 30 interacts with the absorber structure 20 and a vehicle bumper 12 in case of an impact, which causes the rod structure towards the absorber structure 20.

By way of example the rod structure 30 comprises two parallel, longitudinally extending rod members 34 having their forward portion 31 adapted to be secured to the vehicle bumper 12. The forward portions 31 of the rod members 34 are connected with a bar 32 perpendicular to the longitudinal axis of the rod members 34. The rear ends 36 of the rod members 34 engage the absorber structure 20 which is embodied as a tubular jacket around the rear end 36 of each rod member 34. The rod members 34 are arranged symmetrically to a longitudinal middle axis of the vehicle 50.

The rod members 34 are slidably movable in longitudinal direction 14 which is indicated by a broad arrow. Guide elements 18 are provided to support an easy sliding movement. Stopper elements 16 are provided to stop a sliding movement of the rod members 34. The stopper elements 16 and the guide elements 18 are advantageously fixedly mounted to the frame or chassis 40 of the vehicle 50. The distance between the stopper element 16 and the normal position of the head element 32 of the rod structure 30 is matched to the actual geometrical set up and to the absorption properties of the absorber structure 20 and thus chosen to be long enough to let enough kinetic energy be absorbed and short enough to avoid an overload of the absorber structure 20. A typical distance can be e.g. several tens of centimetres.

The absorber structure 20 is preferably positioned in an inner space area 44 between two axles 42, 46 of the vehicle 50. The inner space area 44 denotes an inner space between the axles 42, 46 in distinction to an outer space, where the front bumper 12 in the front of the vehicle 50 or a rear bumper (not shown) in the aft of the vehicle 50 is arranged.

The absorber structure 20 is in operational connection to the at least one rod member 34 so that when the at least one rod member 34 is moving towards the absorber structure 20 in direction 14 the absorber structure 20 is expanded by the at least one rod member 34. The absorber structure 20 comprises an interface member 24 which is the bottom of the tubular jacket and to which the rod structure 30 makes contact in case of a crash.

The absorber structure 20 has an expandable portion 26 which forms a corrugated wall of the tubular jacket and which is being expanded when the rod structure 30 makes contact with the interface member 24. The expandable portion 26 is adapted to be attached with one end to a vehicle frame or chassis 40, preferably with its first end 21 proximate to the head element 32 of the rod structure 30. The interface member 24 is connected to a lower end 23 of the expandable portion 26 opposite to the front portion 21. The interface member 24 can move freely into the longitudinal direction 14 when pushed by the rod member 34.

Preferably, the expandable portion 26 comprises a hardened Boron-alloy steel.

The rod members 34 are long enough to engage with the absorber structure 20 embodied as tubular jacket and protrude into the inner volume 22 of the tubular jacket. The free ends 36 of the rod members 34 can be close or in contact with the bottom part (i.e. the interface member 24) of the tubular jacket in their normal positions before a crash.

Fig. 2 depicts an alternative example embodiment of a crash absorber according to the invention. The basic elements are the same as described in Fig. 1 except that there is only one central rod member 34 with a guiding rod 35 at each side. To guide the rod structure 30 during impact, the central rod member 34 as well as the guiding rods 35 can be supported by guide elements 18 attached to the vehicle frame or chassis 40.

Figs. 3a and 3b illustrate a detail of the crash absorber 10 depicted in Figs. 1 and 2. A rod member 34 is shown in a normal position (Fig. 3a) and in a crash situation where the rod structure 30 has been forced towards the absorber structure 20 by the impact. The head element 32 of the rod structure 30 has moved backward and is in contact with the stopper elements 16 whereas the rod member 34 has pushed the interface member 24 of the absorber structure 20 in longitudinal direction. The absorber structure 20, being rigidly attached to the vehicle frame or chassis 40 has been longitudinally expanded by a length corresponding to the distance between the head element 32 in its normal position and the stopper element 16.

An alternative embodiment of a crash structure 20 is depicted in Fig. 4. The expandable portion 26 of the crash structure 20 is formed as a spring coil concentrically wound around the end portion of the rod member 34 with its end 36 protruding into the coil spring. The spring coil formed expandable portion 26 is arranged between an interface element 24 and a vehicle frame or chassis 40. The expandable portion 26 is attached with_. its forward portion 21 to the vehicle frame of chassis 40 and with its lower end 23 to the interface element 24. When an impact occurs the rod member 34 pushes the interface element 24 longitudinally in direction 14 and the expandable portion 26 of the absorber structure 20 becomes expanded, as was indicated in Fig. 3b. An alternative embodiment of a crash structure 20 is depicted in Fig. 5. The crash structure 20 is arranged as a one sided connection between an interface element 24 and a vehicle frame or chassis 40. The connection comprises an expandable, e.g. corrugated, portion 26 which is attached with its forward portion 21 to the vehicle frame or chassis 40 and with its lower end to the interface element 24. When an impact occurs the rod member 34 pushes the interface element 24 longitudinally in direction 14 and the expandable portion 26 of the absorber structure 20 becomes expanded, as was indicated in Fig. 3b.

Generally, by using hardened Boron-alloy steel for the absorber structure 20 and particularly for the expandable portion, use can be made of the superior mechanical and elastic properties of this material. The length of the rod structure 30 (Fig. 1, Fig. 2) can be easily adjusted to given conditions of a given vehicle 50. The absorber structure 20 can be positioned in adequate positions in a vehicle 50 which provide enough space for such structures. As a result, precious construction space becomes available for components and aggregates which cannot be easily positioned in other areas of the vehicle.

Claims

C L A I M S

1. A crash absorber (10) comprising an absorber structure (20) and a rod structure (30) interacting with the absorber structure (20) in case of an impact, the rod structure (30) comprising at least one longitudinally extending rod member (34) having its forward portion (31) adapted to be secured to a vehicle bumper (12), characterized in that the absorber structure (20) is in operational connection with the at least one rod member (34) so that when the at least one rod member (34) is moving towards the absorber structure (20) an expandable portion (26) of the absorber structure (20) is expanded by action of the at least one rod member (34).

2. The crash absorber according to claim 1 , characterized in that the expandable portion (26) is adapted to be attached to a vehicle frame (40).

3. The crash absorber according to claim 1 or 2, characterized in that the absorber structure (20) comprises an interface member (24) to which the rod structure (30) makes contact in case of a crash, the interface member (24) being in contact with the expandable portion (26).

4. The crash absorber according to one of the preceding claims, characterized in that the expandable portion (26) comprises a hardened Boron-alloy steel.

5. The crash absorber according to one of the preceding claims, characterized in that the expandable portion (26) comprises a corrugated structure.

6. The crash absorber according to one of the preceding claims, characterized in that the expandable portion (26) comprises a spring coil structure.

7. The crash absorber according to one of the preceding claims, characterized in that a stopper element (16) is provided to stop a lateral movement of the rod member

(30) towards the absorber structure (20).

8. The crash absorber according to one of the preceding claims, characterized in that the absorber structure (20) is embodied as a tubular jacket which at least partially surrounds the at least one rod member (34) with its expandable portion (26). - -

9. The crash absorber according to claim 8, characterized in that the interface member (24) is a bottom part of the tubular jacket.

10. The crash absorber according to one of the preceding claims, characterized, in that two rod members (34) are provided each in operational contact with one absorber structure (20).

11. The crash absorber according to one of the preceding claims, characterized in that the rod structure (30) comprises one rod member (34) provided with one absorber structure (20) and guiding rods (35) parallel to the one rod member (34).

12. A vehicle (50), comprising a crash absorber (10) with one or more absorber structures (20), according to anyone of the preceding claims.

13. The vehicle (50) according to claim 12, characterized in that the one or more absorber structures (20) comprise one or more an expandable portions (26).

14. The vehicle according to claim 13, characterized in that a stopper element (16) is provided as a catch for a head element (32) of a rod structure (30) interacting with the one or more absorber structures (20) of the crash absorber (10).

15. The vehicle according to one of the claims 12 to 14, characterized in that at least one absorber structure (20) is provided for a vehicle front and a vehicle rear side.

16. The vehicle (50) according to one of the claims 12 to 15, characterized in that the one or more absorber structures (20) protrude into an inner space area (44) behind a vehicle axle (42).

17. The vehicle (50) according to one of the claims 12 to 16, characterized in that one or more crash absorbers (10) are arranged at least at one side of the vehicle (50).

18. The vehicle according to one of the claims 12 to 17, characterized in that a vehicle bumper (12) and the crash absorber (20) comprise hardened Boron-alloy steel.