ANTI-SKID STUD

Abstract: The invention relates to an anti-skid stud the operation of which is based on a larger than conventional diameter of the tip part (1) of the anti-skid stud and on its primarily annular contact with the road surface during normal driving, with a slight projection of the tip and with a small surface pressure, the projection increasing in situations in which it is needed, for example during braking, the external force P caused by the braking tilting the anti-skid stud in its position, whereupon the projected edge (5) of the tip part will penetrate over its entire width into the road surface.

Description: Anti-skid stud Anti-skid studs for vehicle tires are largely based on the principle of a spike projecting out from the tire and being made up of a thin hard-metal stud, 2 - 3 mm in diameter, which is surrounded in a varying manner by metal or plastic or by a combination of the two. All of them have the disadvantage that the small hard-metal tip subjects the road to a relatively hig surface pressure, which wears an ice-free road, and that, on the other hand, its grip is very poor on a thin so-called blac ice surface, which the tip of the stud cannot penetrate. As a result, a stud, rounded by wear, will skate on the ice surface with a friction coefficient even lower than that of rubber. 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 drawings, in which Figures 1 and 5 depict each a vertical section of a side eleva tion of an anti-skid stud according to the invention, Figure 2 depicts the anti-skid stud installed in a vehicle tire, the tire part being at rest or rolling against an icy road surface, Figure 3 depicts the anti-skid stud in a vehicle tire against the road surface when braking force or some other horizontal force is acting between the road and the tire, Figure 4 depicts the wide and deep contact area produced by th anti-skid stud in an icy road surface at the time of braking o acceleration, or when the vehicle tends, for example, to side¬ slip. An anti-skid stud according to the invention is characterized in that the flanged anti-skid stud (Figures 1 and 5), installe in a vehicle tire in a conventional manner, has no conventiona hard-metal pin? the anti-skid tip 1 of the stud has in the gripping area 5 a diameter (in general 5... 12 mm) which is large in comparison with the total length of the anti-skid stud. In Figure 1 the tip of the stud constitutes a concave or straight surface 2, in which case its road contact is primaril annular and wide when the stud is in its basic position perpen dicular to the road surface (Figure 2) . Owing to the width of the contact area, the surface pressure against the road is relatively low. The core part, i.e. the body material la, of the anti-skid stud is not so hard as its mantle surface 3, and this prevents the tip 2 of the stud from obtaining a convex shape as the stud wears down. Anti-skid studs according to the invention are placed in a vehicle tire in a conventional manner, installed in bed-holes 10 prepared in advance in the tire tread rubber 4 (Figure 2), i.e. around the whole tire, in a suitable number, usually the maximum number permitted in the regulations. Unloaded, the annular tip 5 of the anti-skid stud protrudes somewhat from the surface 6 of the vehicle tire. In Figure 2 the tire is pressed by the weight of the vehicle against the ice surface 8 on the road surface 1 , whereupon the annular tip 5 of the anti-skid stud will penetrate somewhat into the ice surface 8. When the vehicle is traveling, without acceleration or braking, on a road covered with glare ice, the anti-skid stud is in its stand-by position in accordance with Figure 2. When there is braking, acceleration or, for example, a danger of sideslip¬ ping, the stud tilts under the action of an external force P (Figure 3). Owing to the tilting of the stud, its annular tip 5 tends outward from the tire tread 6, against the direction of movement, whereupon the tip 5 of the stud will form a wide, claw-like obstacle which will penetrate into the ice, i.e. producing a chisel-like grip which effectively reduces the danger of sideslipping and skidding. Figure 4 depicts the shape of the impression 9 caused by the stud tip 5, the shape being oriented against the tendency to skid and having width B and depth H (Figure 3) . The anti-skid stud, made of one material, according to Figure is made of a material which can be processed so as to be hard on its surface, for example of cemented steel with a cementa¬ tion depth of approx. 1 mm and a surface hardness of over 800 HV within the area 3, the core part la which will wear into a concave shape remaining softer. The tip part 2 which will wear so as to obtain a concave shape can be left uncemented, in which case it will initially operate as a straight plane and will gradually wear into a concave shape, or it can be machine into a concave shape after the cementation. Although an anti¬ skid stud thus made is somewhat heavier than conventional studs, owing to its greater exterior diameter, its road-wearin action is considerably less than that of conventional studs, owing to the considerably lower surface pressure against the road surface during normal rolling. However, in a skid situa¬ tion the grip against the road is good. The material of the anti-skid stud may also be some other material which can be processed to be hard on its exterior surface but is lighter than cemented steel. In an anti-skid stud according to Figure 5, made of a suitably hard material or of a material which can be processed so as to be hard, the concavity 2 in Figure 1 has been replaced by a void 11, which will maintain the straightness of the tip 5 and its annular contact with the road surface during rolling. For example, rapid steel, cemented steel, and various ceramic mate rials are suitable materials. Made in this manner, for example the weight of an anti-skid stud made of cemented steel may be reduced and the hardest possible cementation is obtained for almost all of the material 12 coming into contact with the road, as cementation also takes place inside the void 11. The void 11 may, when necessary, be filled up with some lightweigh material softer than the material 12. The invention is not restricted to the embodiments and raw materials described above but may in its details vary greatly within the scope of the patent claim.

Claims: Claim An anti-skid stud, provided with a fastening flange, to be installed in a conventional manner in a bed-hole (10) pre¬ pared in advance in the tread of vehicle tires, character¬ ized in that the anti-skid tip part (1) of the stud made of one material has a relatively large diameter, approx. 5 - 12 mm, in comparison with the total length of the anti-skid stud, and the central part of that area of the tip part (1) which comes into contact with the road surface is made lighter either by means of a bed-hole (11) or by processing the material of the cylindrical or otherwise shaped mantle surface (3) in that area of the tip (1) which comes into contact with the road surface to a suitable depth so as to resist wear, i.e. primarily to be harder than the core material of the tip part (1) , the surface (2) of the tip of the tip part (1) , when alternatively thus implemented, not obtaining a convex shape under the effect of wear but ob¬ taining a concave shape during wear, or remaining almost straight. AMENDED CLAIMS [received by the International Bureau on 12 May 1992 (12.05.92); original claims 3 and 4 cancelled; original claims 1 and 2 amended; (1 page)] 1. An anti-skid stud, provided with a fastening flange, to be installed in a conventional manner in a bed-hole (10) pre¬ pared in advance in the tread of a vehicle tire, characterized in that the tip (2) of the tip part (1) , equal or somewhat smaller in diameter than the fastening flange of the anti-skid stud, is flat or concave, and that the grip of the anti-skid stud against a slippery road surface (8) occurs when the edge (5) of the tip (2) of the anti-skid stud projects from the surface (6) of the vehicle tire to a greater extent than in its stand-by position (Figure 2) when the anti-skid stud tilts, under the action of an external force (P) during braking, for example, whereupon the projecting edge (5) of the tip part will produce a wide (B in Figure 4) grip, deeper (H in Figure 3) than in the stand-by position of the stud, against the icy road surface. 2. An anti-skid stud according to Claim 1, characterized in that in the anti-skid stud the central part of that area of the anti-skid tip part (1) which comes into contact with the road surface is provided with a void (11) to prevent the tip from obtaining a convex shape during wear, or that the mantle sur¬ face (3) of the tip part (1) is, to a suitable depth, of a material more resistant to wear, i.e. primarily harder than the core material of the tip part (1), the tip of the tip part, when thus implemented, not obtaining a convex shape under the effect of wear during driving but obtaining a concave shape on its surface (2) or remaining almost flat.

Inventors: TEERI NIILO HEIKKI, TEERI, NIILO, HEIKKI
Applicants: TEERI NIILO H, TEERI, NIILO, HEIKKI
Application year: 1991
Main classification: B60C11
IPC codes: B60C11