IMPROVED REINFORCING STRUCTURE

The present invention relates to improvements in or relating to reinforcements and in particular relates to lightweight reinforcements that can be used to strengthen seats particularly seats employed in transport systems such as automobiles, busses, trucks, railroad coaches and aircraft.

Seats are often based on a tubular structure that is provided with appropriate padding for the comfort of the user. It is important that the structure be sufficiently strong to support the user and it is also desirable that adequate strength be achieved with minimum increase in the weight of the article.

United States Patent 5,255,487 provides a reinforcement for a door comprising a tube which is locally strengthened by means of an internal welded insert. This however suffers from the disadvantage that the tube is difficult to manufacture with the need to provide the insert inside the core of the tube. Furthermore, the entire reinforcing tube must be replaced in the event of damage to the tube.

There therefore remains a need for a lightweight reinforcement that can be readily applied and removed and which can be easily replaced in the event of damage.

The present invention therefore provides a reinforcing material, preferably a double shell material, which may be fastened around the exterior of a structure and subsequently foamed to provide a reinforcement to the structure. When the material is a double shell the inner layer is the foamable layer.

The invention therefore further provides a reinforcing material comprising an outer layer and an inner expandable layer and provided with means whereby the material may be fastened around an article to be reinforced whereby the inner layer may be foamed to provide reinforcement and to bond to the article to be reinforced.

The invention further provides an article having a reinforcing material as previously described fastened thereto and also provides such a reinforced article wherein the foamable material has been foamed.

In a preferred embodiment the double shell is hinged so that it may be folded around the article to be reinforced and is provided with fastening means whereby it is held in

place when it has been folded around the article to be reinforced. The fastening means may comprise a clip, a clamp, a rivet or a protrusion and the means of fastening may be a self fastening action between parts of the reinforcing double shell or it maybe an action whereby the double shell is fastened to the structure to be reinforced. In a preferred embodiment the fastening means comprises a clip on one edge of the double shell which is a snap fit with a mating recess at the other edge when it is folded around the article to be reinforced. In a further embodiment the outer layer of the double shell is made of a rigid material such as metal for example aluminium or steel, or thermoplastic such as polypropylene or nylon, glass filled nylon is particularly preferred. In some instances such a double shell material is referred to as a composite. In a further embodiment the reinforcing material may be a single layer of foamable material which may be applied to and attached to the structure to be reinforced and subsequently foamed by these techniques.

The inner layer of the double shell material of this invention is of a foamable material and is preferably a heat activated foamable material and is preferably an epoxy foam. In a preferred embodiment when the reinforcement is used for the reinforcement of automobile seats the foamable material is selected so that it will foam at temperatures to which the seat is exposed during its manufacture, preferably it will foam at a temperature in the range 80 ⁰ C to 240 ⁰ C. The heating may be accomplished by oven heating, infra red heating, ultrasound or microwave heating. In some instances the foaming can be caused to occur at ambient temperature by physical activation. The foamable material is preferably dry to the touch at ambient temperature and develops adhesive properties when it is heated to the foaming temperature.

When the reinforcing material is a double shell material the outer section of the reinforcing member may be made from any suitable material, for example it may be made of metal or plastic and the material will be chosen according to the preferred fabrication method. This in turn is driven by economics and the complexity of the shape of the article to be reinforced. Reinforcing members for simple cross sections may be prepared by extrusion and the materials could be co-extruded whilst injection moulding may be required for more complex structures. Metal members may be produced by stamping and/or forming. Where extrusion is used the members may be of metal or thermoplastics; where injection moulding is used thermoplastics are preferred. Polyamides, particularly glass filled polyamides are suitable materials due to their high strength to weight ratio. Alternatively injection moulding or die casting of

metal alloys may be employed. Injection moulding is particularly preferred because this allows the segments to be moulded together with an integrally moulded, flexible, interconnecting piece to provide the desired degree of flexibility.

The outer section of the reinforcing member of the present invention, when present, may be of any thickness depending upon the nature of the structure to be reinforced and the preferred shape and structure of the member will depend upon where it is to be located e and the reinforcing function it is to perform. In the preferred embodiment for reinforcing tubular members the outer member is from 0.2 to 1 mm thick and is cylindrical.

The expandable adhesive material may be co-extruded with the outer section. Alternatively it may be injected, sprayed or coated onto the inner surface of the outer section. The expandable material serves two main functions, it will expand to fill the space between the outer sleeve and the seat structure and it will also bond to the article to be reinforced. Accordingly, the expandable material is preferably an expandable adhesive material which can be activated to both expand (typically foam) and to act as an adhesive. Accordingly, in order to provide reinforcement the expandable adhesive must expand at the desired temperature and be sufficiently adhesive to firmly bond the reinforcing member inside the vehicle structure. Once foamed it should be sufficiently strong that it does not contribute any weakness to the overall reinforcing effect provided.

Prior to activation, the expandable adhesive material is preferably dry and not tacky to the touch, since this facilitates shipping and handling and prevents contamination.

Examples of preferred expandable materials for the production of reinforcing materials include foamable epoxy-base resins and examples of such materials are the products L5206, L5207, L5208 and L5209, which are commercially available from

L & L Products of Rome, Michigan, USA, and the Betacore Products BC 5204, 5206, 5205 and 5208 available from L & L Products Europe, Strasbourg, France. The product should be chosen according to the rate of expansion and foam densities required. It is further preferred that it expand at the temperatures experienced in the electrocoat baking oven, typically 13O ⁰ C to 200 ⁰ C, preferably 130 ⁰ C to 15O ⁰ C. If the invention is to be used to provide acoustic insulation as well as reinforcement the expandable material may be a thermoplastic such as copolymer of ethylene and vinyl acetate or an ethylene acrylate copolymer.

The invention may be used to reinforce a variety of articles that are based on frame, particularly tubular frame structures. Examples of such structures include scaffolding as used in the construction industry and structures employed in transport systems such as automobiles, busses, trucks, military vehicles, railroad trucks, coaches, children's push chairs, wheelchairs, motorcycle frames, sports vehicles, ladders, locomotives, aircraft, trailers and sports equipment. The invention is particularly useful in the reinforcement and strengthening of tubular frame in sealing such as automobile, but and aircraft seating.

The invention is illustrated but in no way limited by reference to the accompanying drawings in which

Figure 1 shows a reinforcing double shell member according to the invention.

Figure 2 shows a tubular element of an automobile seat with the reinforcing member in an undipped state.

Figure 3 shows a reinforcing material clipped around the tubular element of Figure 2.

Figure 4 shows the tubular member of Figure 2 provided with the reinforcing member of Figure 1.

Figure 5 shows the frame of a vehicle seat provided with two reinforcing members according to the present invention.

Figure 1 shows the reinforcing member as two semi cylindrical sections (1) and (2) joined by a hinge (3). Each section comprising an outer metal piece (4) provided internally with a foamable metal (5). Section (2) is provided with a clip (6) which is a snap fit into locating groove (7) provided in section (1).

Figure 2 shows the reinforcing member placed around a tubular element (8) of an automobile seat and Figure 3 shows the reinforcing element (1) being applied to the tubular element (8).

Figure 4 shows the reinforcing element in place around the tubular element (8) with the foamable material having been foamed to provide a reinforcing foam layer (9) around the tubular member (8).

Figure 5 shows where a reinforcing member may be applied to the frame of an automobile seat in order to provide a reinforcement.

The invention therefore provides a simple to apply light weight reinforcing structure. It can be readily applied to the location it is desired to locate. No welding or tooling is required to secure the reinforcement and it requires little space to provide reinforcement in that the layers of the reinforcing material can be thin and thus can reduce the weight required of the seat for a given strength. The reinforcement can be shaped to provide the desired reinforcement to any shape or size of member.