MXPA00008562A - A seat, especially for a vehicle - Google Patents

Abstract

A vehicle seat, such as a car seat, comprising shells for bottom, backrest and headrest with a cellular plastic layer adjacent to the body of a user on the shell of the seat, the shell of the backrest and/or the shell of the headrest, respectively, covered by a surface layer. The cellular plastic layer is a layer of a substantially energy absorbing cellular plastic having a density of 30 - 110 kg/m3, an ILD at 65%indentation of 100 - 500 N, and a rebound of maximum 10%according to the Standard ASTM-D-1564.

Description

A SEAT, ESPECIALLY FOR A VEHICLE TECHNICAL FIELD The present invention relates to a vehicle seat, such as a car seat.

PREVIOUS TECHNIQUE The predominant method for the manufacture of vehicle seats is to empty the seat together with the optional steel inserts, etc., into one and the same material, usually plastic in the form of polyether cells in the form of foam. The seat cushion should be comfortable, while the sides that are supposed to support the thighs will be somewhat harder. This is achieved by foaming, in the same mold with different indices, for example, different amounts of isocyanate are used. More isocyanate gives a harder cellular plastic. Such foam material does not absorb energy, but rather results in rapid springing.

As part of personal protection in modern automobiles, the seats, especially the front seats, are made more rigid so as not to break in an accident. These types of seats give better protection at higher speeds, but work less well at low speeds. Due to the rigidity, the seat will not absorb the energy for example in a collision at the rear end at low speed, but rather the body, and especially the head will bounce back and forth resulting in so-called whiplash injuries in the spine. Insurance companies have established that the number of injuries increases every year and in Sweden 16,000 accidents are now reported each year and approximately 2,000 of these lead to disability.

THE INVENTION The object of the present invention is to provide a vehicle seat having energy absorbing characteristics, which compared to the prior art show improved protection against whiplash injuries in rear-end collisions. This and other objects of the invention are achieved with the vehicle seat according to the invention, as defined in the claim.

BRIEF DESCRIPTION OF THE INVENTION The objects, advantages and additional features of the invention will be obvious from the following detailed description of the preferred embodiments of the invention, with reference to the accompanying drawings, in which: Figure 1 illustrates a graph of energy absorption for plastic highly elastic cellular usually used in furniture, Figure 2 illustrates a corresponding graph for a cellular cell substantially energy absorbing, Figure 3 illustrates the structure of a highly elastic cellular plastic, and Figure 4 illustrates the structure of a substantially absorbing cellular plastic of energy, of the type used in the vehicle seat according to the invention.

DESCRIPTION OF THE PREFERRED MODALITIES OF THE INVENTION Behind the invention lies the fact that the glass transition temperature GTT for the cellular energy-absorbing plastic behaves completely differently compared to what is the case with other cellular plastics, relatively more elastic. The last mentioned cellular plastics have a large change in viscosity over a small temperature range, while the change in viscosity for a cellular energy absorbing plastic, for example, a polyurethane polymer, has a much wider temperature range , where the polymer slowly softens. Of this, for example, a seat with cellular energy-absorbing plastic can be felt hard at 0 ° C, but when someone sits on such a seat this can be felt as if it sank in successively when the cellular plastic is gradually heated by the person sitting. A cellular layer of energy-absorbing plastic adjacent to the body absorbs and moderates the energy that is brought into the body in a low-speed collision. The cellular energy absorbing plastics are known per se within the area of plastic materials and the characteristics of such cellular plastics are usually summarized among experts as visco-elastic, non-elastic, controlled recovery, memory foam, etc. The characteristics of the cellular plastic result in that after the indentation of one body or the other, it recovers slowly, which means that the indentation marks can be studied for a longer or shorter time. The absorption of energy can also be studied in a standard test, where a steel ball falls against the cellular plastic surface. A cellular plastic of maximum absorption of energy gives a rebound less than 2% of the height of fall, while a cellular plastic called highly elastic for furniture, will have a rebound of approximately 60%. The absorption of energy can also be studied graphically when the hardness of the indentation is measured according to ASTM-D- Thus, in figure 1, a graph for a highly elastic cellular plastic having a thickness of 50 mm is shown and an ILD (Indentation Load Deflection) at 65% indentation of more than 400 N. The surface between the load curve A and the discharge curve B is a measure of the absorption of energy, and as is evident, from the figure, this is insignificant. In Figure 2, the corresponding graph is shown for a substantially energy absorbing cellular plastic having the same thickness, i.e. 50 mm, with a 65% ILD of approximately 250 N. The indentation, in the illustrated example, has taken place in three steps, but it is clearly seen that the absorption of energy is substantial and this clearly shows the existing possibility of satisfactorily absorbing the energy, which in a conventional car seat in rear-end collisions, causes the lash damage discussed above . The phrase "substantially energy absorbing cellular plastic" is used in this context in order to distinguish the type of cellular plastic that is used in the vehicle seat according to the present invention, and which is exemplified in Figure 2 from of that type of highly elastic cellular plastic that to date is used for example in car seats and in furniture and which is identified in figure 1. The comfort of a car seat is partially given by the characteristics and design of the seat same, partly because of the characteristics and the shape of the backrest and headrest. From a safety traffic point of view, the function and comfort of all parts of the car seat are of the highest importance. When it arrives to reduce the risk of collision damage from the rear, the backrest and the headrest of the seat are of decisive importance. By accommodating the energy absorbing cellular plastic layer in the seat of the vehicle adjacent to a user's body, the main part of the energy emitted in the collision is absorbed by the cellular plastic layer. A suitable density for such cellular energy absorbing plastic is 30 to 110 kg / m3 and a 65% indentation ILD of 100-500 N, and a maximum 10% bounce according to the ASTM-D-1564 standard. A suitable thickness of the energy absorbing cellular plastic layer is approximately 50 mm, but of course this can be made thinner and thicker without departing from the inventive thinking. However, the cellular plastic layer must be at least 200 mm thick in order to give the desired effect. A formulation for a cellular energy absorbing plastic is one or more miscible or immiscible polyols, water or C02 as the blowing agent, an amine as catalyst, an organometallic compound as a gelation catalyst, together with additives such as stabilizer, coloring agent , filler, fire retardant and an antibacterial agent. As a hardener, toluene diisocyanate, either T80 or T65 or a mixture of these two, or methylene diisocyanate (MDI) or a prepolymer comprising one of the isocyanates can be used. An example of a typical formulation is: 70 parts (w / w) of polyol (OH 250), 30 parts of polyol (OH 50), 1.8 parts of water, 0.2 parts of tertiary amine, 0.6 parts of stabilizer (silicone oil), 0.1 parts of tin octoate, 5.0 parts of fire retardant, and variant index isocyanate . In order to further illustrate the invention, Figure 3 illustrates the cellular structure in a highly elastic cellular plastic for furniture. This cellular plastic has a structure that can be described as an octahedron, whose structure is rather prone to breakage. This structure will be compared with the cellular structure shown in Figure 4 for a cellular energy absorbing plastic, where the cells look more like balls. This cellular plastic absorbs the energy of impacts very well. The vehicle seat according to the invention can be provided with the energy absorbing cellular plastic layer either in the seat or in the backrest, preferably in both, as well as in the headrest. With this, the energy-absorbing cellular plastic layer is provided between the support part of the seat and a surface layer in the form of an upholstery, against which the user will rest. An inner layer of highly elastic cellular plastic can, if desired, be provided between the cover or protection and the energy absorbing cellular plastic layer. The provision can be made in different ways. According to one method, the energy absorbing cellular plastic layer is made so as to be glued on the cover or protection in a subsequent step, or if it is applicable on a layer of highly elastic, internal cellular plastic. The cellular energy absorbing plastic layer can also, as in a first step, be emptied into a mold, after which the remaining part of the cover or protection in question is emptied into the same mold. Another alternative is to vacuum-mold a mold with the upholstery, after which the energy-absorbing cellular plastic layer is emptied into the mold. Subsequently, the cellular plastic layer can be laminated on an upholstery that subsequently, with the use of the vacuum is coupled to a mold for the final emptying of the cover or protection in question. Alternatively, the cellular plastic laminate and the upholstery can be coupled onto a cover of any suitable shape.

Without adversely affecting the advantages obtained with the structure according to the invon, a temperature insensitive material in the form of a convonal filler material such as polyurethane foam or a fibrous material can be applied over the polyurethane foam energy absorber , as a comfort layer. With this, the disadvantage discussed above that the energy absorbing polyurethane foam is hard at 0 ° C, is reduced or eliminated. A suitable thickness can be from 20 to 30 mm.

Claims (1)

CLAIMING

1. A vehicle seat, such as a car seat, comprising covers or protections for the bottom, backrest and headrest with a cellular plastic layer adjacent to a user's body on the seat cover, the backrest cover and / or the cover of the head rest, respectively, covered by a surface layer, characterized in that the cellular plastic layer is a layer of a cell-shaped plastic, substantially energy absorbing, having a density of 30 to 110 kg / m3, an ILD to indentation of 65% from 100 to 500 N, and a bounce of 10% maximum according to Standard ASTM-D-1564.