HONEYCOMB BLOCK

Abstract: The honeycomb block, in accordance with the present invention, comprises at least two layers of honeycomb elements. These layers can be of the same or different thickness. Each layer comprises a middle part made up of the honeycomb cells, and two outer sheets delimiting the middle part. The honeycomb cell sizes can be the same or different for the layers. The specific combination of layer thicknesses and cell sizes depend upon the desired energy absorption properties which are to be imparted to the block. Honeycomb blocks according to the invention are particularly useful as side protection/impact force absorbing elements in the doors of vehicles. When using honeycomb element layers with varying cell sizes, the large size cells are usually facing out from the passenger compartment and, hence, the smaller size cells facing inwards. This construction enables an energy absorption with a desired progress, e.g. a smooth capture of a colliding object.

Description: TITLE: Honeycomb block. TECHNICAL FIELD: The present invention relates to a honeycomb block according to the preamble of claim 1. BACKGROUND OF THE INVENTION: Honeycomb panels with one layer of hexagonally shaped cells sandwiched between backing sheets are known. One use is as side protection/impact force absorbing elements in the doors of vehicles. These panels are e.g. made of paper which provides a cheap, simple and light construction. The problem is to achieve a door construction which on one hand can absorb a high proportion of the energy released in a collision and, on the other hand, does not add too much weight and cost to the vehicle. The known honeycomb panels do not have sufficient impact absorbing capacity for this use neither can their impact absorbing capacity be varied. SUMMARY OF THE INVENTION: It is therefore an object of the present invention to provide a honeycomb block which can absorb a high proportion of the energy directed towards the block, e.g. during a collision, but which still is light and simple and cheap to manufacture. A further object of the present invention is to provide a honeycomb block which has the desired properties regarding energy absorption also when it is desirable that these properties vary in the thickness direction of the block. This object is achieved in accordance with the present invention by a honeycomb block according to claim 1. CONFIRMATION COPY The honeycomb block, in accordance with the present invention, comprises at least two layers of honeycomb elements. These layers can be of the same or different thickness . Each layer comprises a middle part made up of the honeycomb cells, and two outer sheets delimiting the middle part. The honeycomb cell sizes can be the same or different for the layers. The specific combination of layer thicknesses and cell sizes depend upon the desired energy absorption properties which are to be imparted to the block. Preferred embodiments of the present invention are detailed in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS: The invention will be described in greater detail in the following by way of example only and with reference to the attached drawings, in which: Fig.l is a schematic view perpendicular to one of the backing sheets of a honeycomb block according to the invention, where the top right corner of the backing sheet has been removed, and Fig.2 is a schematic side view of one embodiment of the block in Fig. 1. Fig.3 is a schematic side view of another embodiment of the block in Fig. 1. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS: As is evident from Fig.l, the honeycomb cell structure 2 is covered by a front sheet 1 and a back sheet 3. The cells are made up of strips which are folded to form the honeycomb pattern and the strips are secured to each other, after which the sheets are attached. The cross sectional view of a block according to the invention represented in Fig.2 shows a block comprising two honeycomb element layers attached flat side to flat side. The layers are preferably glued together. Backing sheets 4 and 6 surround a honeycomb section 5, backing sheets 7 and 9 surround another honeycomb section 8. The section 5 has a thickness tj and the section 8 has a thickness t 2 . These thicknesses t x and t 2 can be equal or different. The honeycomb cell sizes in sections 5 and 8 can also be equal or different. The cell size is either the length of one side in the hexagonal, for equal sides, or the longest distance between two opposite corners, for a "stretched" hexagonal shape. The alternative embodiment shown in Fig.3 comprises three honeycomb element layers attached in a similar manner to the panel in Fig.2. Backing sheets 10 and 12 surround a honeycomb section 11, backing sheets 13 and 15 surround another honeycomb section 14 and backing sheets 16 and 18 surround yet another honeycomb section 17. The section 11 has a thickness t 3 , the section 14 has a thickness t 4 and the section 17 has a thickness t s . These thicknesses t 3 , t 4 and t 5 can be equal or different. The honeycomb cell sizes in sections 11, 14 and 17 can also be equal or different. A particularly preferable embodiment has a large cell size in section 11, a smaller cell size in section 14 and an even smaller cell size in section 17, i.e. the cell size decreases from a large size in section 11 to a small size in section 17. Honeycomb blocks according to the invention are particularly useful aε side protection/impact force absorbing elements in the doors of vehicles. When using honeycomb element layers with varying cell sizes, the large size cells are usually facing out from the passenger compartment and, hence, the smaller size cells facing inwards . This construction enables an energy absorption with a desired progress in the thickness direction of the block, e.g. a smooth capture of a colliding object. The honeycomb cells are advantageously fabricated from strips of recycled cardboard which are glued together to form the honeycomb pattern. The backing sheets have to have a higher strength than recycled paper can give, so they are preferably made from non-recycled cardboard/paper. The backing sheets can have one side covered with a layer of glue which fastens to the honeycomb cell structure. The honeycomb blocks can also be made in several segments to fit in different cavities in the door. Another advantageous embodiment is attained by wrapping the whole block in sealing plastic to protect the honeycomb blocks from moisture. Still another advantageous embodiment is to have only one backing sheet between two layers glued back to back, i.e. in Fig. 2 only one of the layers 6 and 7 would be present. It is also possible to glue two honeycomb structures together using no backing sheets, or, possibly, using only backing sheets facing outwards and inwards, e.g. in Fig. 2 only backing sheets 4 and 9 would be present and none of 6 and 7. The present invention is not restricted to the embodiments described above and illustrated by way of example in the drawings, but may be varied within the scope of the appended claims. It is to be understood that the term "honeycomb block" is intended to encompass at least two layers of honeycomb elements attached together flat side to flat side while the term "honeycomb element layer" denotes a honeycomb cell structure with one backing sheet covering each flat end of the structure.

Claims: CLAIMS: 1. A honeycomb block, c h a r a c t e r i z e d i n that it comprises at least two layers of honeycomb elements (5, 8, 11, 14, 17). 2. A honeycomb block according to claim 1, c h a r a c t e r i z e d i n that said layers (5, 8, 11, 14, 17) comprise a middle part made up of a honeycomb cell structure (2), and two outer backing sheets (1, 3) delimiting the middle part. 3. A honeycomb block according to one of claim 1 or 2, c h a r a c t e r i z e d i n that said layers (5, 8, 11, 14, 17) are of substantially the same thickness. 4. A honeycomb block according to one of claim 1-3, c h a r a c t e r i z e d i n that said layers (5, 8, 11, 14, 17) are of different thickness. 5. A honeycomb block according to one of claims 1-4, c h a r a c t e r i z e d i n that said layers (5, 8, 11, 14, 17) have substantially the same honeycomb cell size. 6. A honeycomb block according to one of claims 1-5, c h a r a c t e r i z e d i n that said layers (5, 8, 11, 14, 17) have different honeycomb cell sizes. 7. A honeycomb block according to one of claims 1-6, c h a r a c t e r i z e d i n that the honeycomb block is wrapped in sealing plastic. 8. A honeycomb block according to one of claims 1-7, c h a r a c t e r i z e d i n that the honeycomb block is fabricated from strips of cardboard which are glued together to form the honeycomb pattern cell structure (2), the backing sheets (1, 3, 4, 6, 7, 9, 10, 12, 13, 15, 16, 18) are made from cardboard and have one side covered with a layer of glue which fastens to the honeycomb cell structure. 9. A honeycomb block according to one of claims 1-8, c h a r a c t e r i z e d i n that the cell size in each honeycomb cell structure (2) decreases from a large size in one section (5, 11) to a smaller size in the neighbouring section (8, 14, 17). 10. A honeycomb block according to one of claims 1-9, c h a r a c t e r i z e d i n that said block comprises three layers of honeycomb elements (11, 14, 17). 11. A honeycomb block according to claim 10, c h a r a c t e r i z e d i n that the cell size in each honeycomb cell structure (2) decreases from a large size in one section (11) to a smaller size in the neighbouring section (14) and an even smaller size in the third section (17). 12. An impact force absorbing element in the door of a vehicle, c h a r a c t e r i z e d i n that the impact force absorbing element is constructed using at least one honeycomb block according to one of claims 1-11. 13. An impact force absorbing element according to claim 12, c h a r a c t e r i z e d i n that the cell size in each honeycomb cell structure (2) in said impact force absorbing element decreases from a large size in one section to a smaller size in the neighbouring section, where the section with large size cells is facing outwards and the section with the smallest size cells is facing inwards with respect to the passenger compartment of the vehicle.

Inventors: KLOMP PIET, WIELINGA HENK, KLOMP, PIET, WIELINGA, HENK
Applicants: KLOMP PIET, VOLVO AB, WIELINGA HENK, AB VOLVO, KLOMP, PIET, WIELINGA, HENK
Application year: 1996
Main classification: B32B3
IPC codes: B32B3, B60R21, F16F7