WO1992013729A1

WO1992013729A1 - Anti-skid stud

Info

Publication number: WO1992013729A1
Application number: PCT/FI1992/000030
Authority: WO
Inventors: Niilo Heikki Teeri
Original assignee: Gyros Oy
Priority date: 1991-02-05
Filing date: 1992-02-04
Publication date: 1992-08-20
Also published as: FI90217B; FI910541A; FI90217C; FI910541A0

Abstract

The invention relates to an anti-skid stud consisting of a plug-like piece, equipped with a fastening flange, to be installed in the tread of a vehicle tire, the plug-like anti-skid stud being made of a resilient basic material (3) of the type of tire-tread rubber or of some other suitably hard type, the basic material containing fragments of a granular or some other form, i.e. frictiion fragments (2), which are fastened to the basic material (3) of the anti-skid stud by diffusion or by some other state-of-the art method. The friction fragments in the tip surface (1) of the anti-skid stud become replaced during wear and produce roughness, as if there were numerous small anti-skid studs in the tip surface of each anti-skid stud, and thereby cause a grip against even a thin layer of ice on road surface; however, owing to their small separate piercing forces they will not cause a strong wearing effect on the road surface during driving on a road free of snow and/or ice.

Description

Anti-skid stud

Anti-skid studs for vehicles are largely based on the principl of spike-like tips projecting out from the tread of the tire, the tip of an individual anti-skid stud being made up of a hard-metal pin approx. 2 - 3 mm in diameter. All of them have the disadvantage that the small hard-metal tip subjects the road to a relatively high surface pressure, which has a strong wearing effect on an ice-free road, and that, on the other hand, the grip of the slippery hard-metal tip is almost nil against thin glare ice occasionally present on the surface of road.

An anti-skid stud according to the present invention reduces the disadvantages referred to above, and it is based on a solu tion the characteristics of which are given in the patent de¬ scription and the patent claims.

The invention is described below in greater detail with ref¬ erence to the accompanying drawings, in which Figure 1 depicts a vertical sectional side elevation of an anti-skid stud according to the invention. Figure 2 depicts the same, as seen from above,

Figure 3 depicts an anti-skid stud installed in a vehicle tire, in contact with an icy road surface,

Figure 4 depicts the bed-hole in which the anti-skid stud is installed in the rubber of a vehicle tire,

Figures 5 ... 9 depict other basic solutions of the anti-skid stud, and

Figure 10 depicts an anti-skid stud according to the invention, equipped with a supplementary pin of a hard ceramic material, hard metal, or some other such material.

The grip of an anti-skid stud according to the invention against an icy road surface is, on softish snowy ice, based primarily on the roughness of its flat tip 1 and, on thin sur- face ice, on friction-material fragments 2 projecting out from the tip area 1 under surface pressure caused by the hard icy road, these pieces gripping against even a thin ice surface in a manner comparable to sand or gravel, thus, owing to the large number of the fragments, producing effective friction at the contact surface between the icy road and the vehicle tire.

Friction-material fragments 2 of a granular or some other form are, in connection with the preparation of the basic mix, caused to adhere to the resilient basic material 3 by dif¬ fusion, adhesion, actual chemical vulcanization, by fastening means on the friction fragments, or in so ^Λ other possible manner. The basic material 3 may be a material similar to the tread rubber of the vehicle tire or some other suitably hard resilient material. The friction fragments 2 of a granular or some other form may be of a hard material more resistant to wear than the basic material, for example a hard ceramic mate¬ rial, a hard metal, a suitable mineral aggregate, a rubber harder than the basic material, etc. , or a suitable mixture of these. Also, the friction-fragments may be, or some of them may be, of a hard or brittle material which wears out more rapidly than the basic material against the road surface and, by wear¬ ing, maintains in a suitable manner the unevenness or roughness of the surface 1. The size of the friction fragments may also vary from small chips of less than 1 mm to larger fragments of several millimeters, for example depending on the size of the anti-skid stud. The ratio of the volume of the basic material to the friction-fragment volume may vary according to the ob¬ jectives.

Figure 3 depicts an anti-skid stud installed in the tread of a vehicle tire. Since, owing to its hard friction fragments, the anti-skid stud is less prone to wear than the material of the tire tread 4, it will always project somewhat from the surface plane 5 of the tire tread. When impinging against soft snowy ice the projection a and the rough surface 1 as such serve to prevent skidding and side-slipping. Upon impinging against a hard thin ice surface 6, the roughness of the surface plane 1 of the anti-skid stud is emphasized as the surface pressure of the icy road surface 6 against the anti-skid stud presses the resilient basic material 3 away from the road surface, where¬ upon the friction fragments 2, being small fragments, penetrate into the thin ice surface 6, slightly but in large numbers.

Figure 4 depicts a bed-hole 7 made in the tread of a tire, the anti-skid stud being installed in the hole in a conventional manner. The bed-hole may be considerably larger than conven¬ tional, since the total diameter of the anti-skid stud may, owing to its manner of contact and its material, be made quite large.

The plug-like anti-skid stud according to Figures 1 and 2 is equipped with a fastening flange 8, which together with its fasteners 9 has been made of metal sheet. The anti-skid stud according to Figure 5 additionally has a beveling 10 to enhance the fastening of the anti-skid stud to the bed-hole 7 in Figure 4.

Figure 6 shows an alternative in which the fastening flange is made up of a flanged sleeve 11 and the friction material con¬ sists of wire fragments 12 of a hard ceramic. The basic mate¬ rial 3 has adhered to the sleeve 11 in a conventional manner during vulcanization. In Figure 7 the flanged sleeve at the same time constitutes the beveling 10 which enhances the fas¬ tening. In Figure 8 the whole anti-skid stud has been vul¬ canized inside a metal shell 13. In Figure 9 the fastening flange is made up of a cap 14 made of metal or some other suit¬ able material.

Figure 10 depicts an anti-skid stud according to the invention, the core of the stud being a moving pin 15 made of a ceramic material, a hard metal, or the like. The purpose of the pin 15 is to serve, on a soft or thick ice surface, as a spike pene¬ trating into the ice surface in the manner of a conventional anti-skid stud. When the vehicle arrives on thin glare ice int which the pin 15 cannot penetrate, it will rise into position 16, and the friction fragments 2 in the anti-skid stud will produce a grip against the glare ice in the manner described above. The piercing force of the pin 15 can be adjusted by means of the diameter 17 of the upper end of the pin, which pushes against the rubber of the vehicle tire. If the pin 15 is of a relatively lightweight material, for example a hard ceram¬ ic, the speed of the vehicle cannot to the conventional degree increase the piecing force of the tip of the pin 15 into the ice and cause wearing of the road surface to a conventional degree.

Friction fragments 2 are also significant during driving on a wet road if the material selected for them is one having a higher coefficient of friction against the road when wet than that of rubber. Mineral aggregate is one such material.

The invention is not restricted to the embodiments described above but may in its details vary greatly without falling out¬ side the scope of the invention.

Claims

1. An anti-skid stud to be installed in a bed-hole in the tread of a vehicle tire, characterized in that the anti-skid stud consists of a plug-like stud equipped with a fastening flange (8, 11, 14), the plug-like anti-skid stud being made of a resilient basic material (3) which is of the type of tire- tread rubber or otherwise suitably hard, which basic material contains fragments having a granular or some other form, i.e. friction fragments (2), which are fastened to the basic mate¬ rial (3) of the anti-skid stud by diffusion, adhesion, actual chemical vulcanization, fastening means on the friction frag¬ ments, or in some other possible manner.

2. An anti-skid stud according to Claim 1, characterized in that the material for the friction fragments (2) contained in the basic material (3) and pressing against the road surface is selected so that their wear against the road surface will be less than that of the resilient basic material (3) of the anti¬ skid stud.

3. An anti-skid stud according to Claims 1 and 2, charac¬ terized in that the material for some of the friction fragments (2) or all of the friction fragments (2) is selected so that the wear of the fragments against the road surface will be greater than that of the resilient material (3) of the anti¬ skid stud.

4. An anti-skid stud according to Claim 1, characterized in that the material selected for the friction fragments (2) is a material corresponding to the aggregate present in the road surface or some other suitable material resistant to wear, its friction coefficient against a wet road surface being greater than that of the rubber used in the tire tread.

5. An anti-skid stud according to Claims 1 ... 4, charac¬ terized in that in the center part of the anti-skid stud there is a pin-like part (15) of a hard ceramic or some other suit¬ able material, which moves in a hole inside the anti-skid stud and, on a hard-surfaced thin ice, when impinging against the ice, pushes against the rubber of the vehicle tire, withdrawing to the plane of the tip surface (1) of the anti-skid stud.