WO1996028310A1

WO1996028310A1 - Stud

Info

Publication number: WO1996028310A1
Application number: PCT/FI1995/000132
Authority: WO
Inventors: Niilo Heikki Teeri
Original assignee: Taiti Oy
Priority date: 1995-03-10
Filing date: 1995-03-10
Publication date: 1996-09-19

Abstract

The invention relates to an anti-skid stud the traction of which against a slippery road surface is produced by the tilting of the stud during braking or on a road curve, and the tip section (1) of which, taking part in the traction, forms by its outer mantle (3) a cone which converges towards the fastening flange (4) of the stud.

Description

Stud

Anti-skid studs for winter tires of vehicles have a major dis- advantage in that they cause a strong wear of a bare snowless or iceless road, which is mainly due to the rolling impact of the projection of the tip of a conventional hard-metal spike against the road surface, which impact grinds the stone aggre¬ gate in the road surface under the effect of the energy dis- charged in the impact. This has given rise to the objective of radical lightening of hard-metal spikes, but the impact and surface pressure caused even by a lightened conventional spike tip are too great for reasonable resistance of the stone aggregate of the road.

The anti-skid stud according to the invention, having a tip which works with a slight and even a negative free projection and remains almost flat, reduces the above disadvantages, and it is based on a system the main characteristics of which are given in the patent claim.

The invention is described below in greater detail, with ref¬ erence to the accompanying drawings, in which

Figure 1 depicts a stud according to the invention, in¬ stalled in the wear surface of a winter tire of a vehicle in such a manner that the stud has a slight free projection x,

Figure 2 depicts the same stud during rolling against an ice-free hard road surface,

Figure 3 depicts the same stud in the wear surface of a nearly worn-out winter tire, during rolling against an ice-free hard road surface, Figure 4 depicts the stud according to Figure 1 during rolling against a road surface covered with thin ice,

Figure 5 depicts the stud according to Figure 1 in trac¬ tion against an ice-covered road surface, the stud tilting under the horizontal force on the stud tip, the force being caused by braking, acceleration or a curve in the road, and

Figures 6-12 depict different structural applications of the stud according to the invention.

A stud according to the invention is characterized in particu- lar in that the stud disclosed in FI Patent 89688 is applied so that the stud tip section 1 (Figure 1) , the tip area 2 of which, having been subjected to wear by driving, remains flat or almost flat, forms by its outer mantle 3 a cone converging towards the fastening flange 4 of the stud, the cone angle being = a . Angle c. forms at the junction of the outer surface

3 of the conical section and the tip plane 2 an angle β which is less than 90°, i.e. a positive chip angle β₂ - c_, which chip angle activates the stud tilt, shown in Figure 5, at the initial stage of the tilting of the stud. This activation pro- motes the traction of the stud against the road surface, espe¬ cially on thin, so-called black ice, on which the penetration of the stud into the slippery road surface during rolling is slight owing to the thinness of the ice layer. In Figure 1 the stud has been installed in the tire in such a manner that the free projection x is small. The free projection x may also be, for example, 0 without hindering appropriate functioning of the stud.

In Figure 2 the stud is shown rolling against a bare ice-free road surface. Owing mainly to the yield z, due to the loading of the tire, of the wear surface rubber 5, the mantle 4 of the stud is pressed against the rubber body of the tire with force Pj and at the same time against the road surface 6 with a force of approximately P,. The flat surface 2 keeps the stud in its basic position, perpendicular to the road surface 6, thus maintaining the stability of the stud position perpendicular to the road surface, regardless of the size of the flat tip 2. When the stud gradually becomes worn as the wear surface of the tire becomes worn (Figure 3), the length of the stud decreases, which would mean an increasing stability against the tilting of the stud, for example, in a braking situation, if the diameter of the flat tip 2 of the stud did not decrease. However, as the stud becomes shorter through wear, the conical shape of the tip section 1 of the stud causes a suitable reduction in the diameter of the tip 2; this at the same time maintains, through a reduction of stability, a suitable propensity to tilt, important for the functioning of the stud. Through this property the conical shape is thus useful for the functioning of the stud according to the invention when there is a threat of sliding or skidding or when sliding or skidding does occur.

Figure 4 depicts a stud according to the invention during rol¬ ling against an icy road surface, at which time the tip plane 2 of the stud presses slightly into the ice surface 8 under compressive force P₂, but remains, however, during rolling perpendicular to the road surface 8 and 6, owing to the tip plane 2. In Figure 5, braking and partial sliding has taken place. The stud tilts under the effect of anti-skid force P₃ aimed at the projecting edge 9 of the tip 2. When the tilt has reached the extent of the cone angle α;, as in the situation drawn in Figure 5, the chip angle β₂ (indicated in Figure 1) becomes zero and, when the tilting increases, it becomes negative. At this stage the road surface (8 and 6) even as such suitably activates the tilting of the stud during braking, and the projecting edge 9 of the stud presses into the ice 8, producing traction. When the said ice surface 8 is thin (so-called black ice) , the tip 9b presses through the ice against the hard surface 6 of the paving, thus enhancing the braking effect. The same phenomena also occur during acceleration and during driving on a road curve. Figures 6-12 show different stud alternatives according to the invention. The studs of Figures 6 and 7 are in accordance with those shown in Figures 1-5 and made entirely of a suitable hard material. In the stud in Figure 6, the tip plane 2 has a concave recess 10 to maintain its flatness during rolling, and in Figure 7 there is a hole 11 running through the stud. In Figure 8 the conical tip 12, made of a hard material, is secured to a flange body 13 by various known methods. In Figure 9, the wear-resistant tip section 14 is secured to a plastic body, a molded piece 15, or the like, likewise in Figure 10, in which, in addition, the upper surface 16 of the fastening flange is convex, mainly to shift the center of tilting, when necessary, and to overcome other properties of rubber. In Figure 11 the conical section 17 of the stud is fastened to a sleeve-like metal body 18 by various possible methods, and Figure 12 shows mainly a hot-pressed and tempered product, which has recesses 19 and 20 in both ends of the stud.

The invention is not limited to the embodiments described above; it may vary greatly in its details without deviating from the scope of the invention.

Claims

Claim

An anti-skid stud having a fastening flange and being install¬ able in a pin hole pre-made in the wear surface of a vehicle tire in a conventional manner, characterized in a combination in which the tip (2) of the tip section (1) , having a diameter approximately equal or slightly smaller than that of the fas¬ tening flange (4) of the stud, is flat or almost flat, and that the traction of the stud against a slippery road surface

(8) occurs when, as the stud tilts (Figure 5) under the effect of an external force (P₃) , for example during braking, the edge

(9) of the stud tip (2) projects out from the vehicle tire surface more than in its initial position (Figure 4) , where¬ upon the projecting edge (9) of the tip section will produce, against the direction of sliding or skidding, a wide traction, deeper than the initial position of the stud, against the icy road surface, and the stud tip section (1) , the tip (2) of which remains flat or almost flat as it wears down during driving, forms by its outer mantle (3) a cone which converges towards the fastening flange (4) of the stud.