= 1 - Spike
[0001] The invention relates to a tyre stud for anchoring in a tyre stud hole of a tread of a pneumatic vehicle tyre, having a tyre stud body which has a base flange, and having a tyre stud pin of hard metal, which is anchored in an insert located in the tyre stud body and by way of an end portion protrudes beyond the tyre stud body wherein the base flange has lateral delimitation faces and the insert has a base part partly forming the base flange and has a pin holder that holds the tyre stud pin and wherein the tyre stud body optionally, except for the insert, is com- posed of non-metallic material which encases the base part at the base flange.
[0002] Tyre studs are normally held by a combination of form-fitting and clamping connections in the tyre stud holes of the tread of pneumatic vehicle tyres. Conven- tional tyre studs consist of a tyre stud body of aluminium or steel in which is held the tyre stud pin, made from hard metal and protruding over the tread surface.
[0003] It is usual to use a spreading material on wintry road surfaces to increase traffic safety. The use of sand was reduced in recent years in favour of a grit spreading material since sand has a tendency to be ground up by tyres into dust or fine particles, which is to be reduced or prevented for the health and safety of the population. The use of grit spreading material however has the result that the usual tyre studs used in pneumatic vehicle tyres become heavily worn, particularly if the tyre stud body is made of aluminium.
[0004] It has therefore already been proposed to use tyre studs with tyre stud bodies made of rubber or plastic. DE 2 202 373 A1 discloses a plastic spike which is made from a hard metal pin and a plastics casing wherein the hard metal pin is embedded in the plastic shaft by means of ultrasound vibrations. With further known methods for manufacturing plastic tyre studs the hard metal pin is injection moulded in ther- moplastic materials.
[0005] WO 2017/0888995 A1 discloses tyre studs in which the tyre stud pin and/or the base flange, which is made from plastic or aluminium, is or are embedded at
< 9 - least in some parts into a rubber sleeve or into rubber material. The particular advantages of these designs lie in the basic material properties of the rubber body. Through its low density of about 1g/cm?, rubber is particularly light compared to aluminium and steel. Replacing aluminium and steel by rubber as the body material therefore leads to a reduction in the tyre stud weight which has a particularly posi- tive effect on the road wear and fine particle formation. The road wear is mainly determined by the impact energy of the tyre stud. The elastic material properties of rubber have even further advantages. On the one hand the elastic body material dampens shocks so that lower forces act on stones in the road surface or on the particles of the grit material. Thus the road wear and fine particle formation are also thereby reduced. Tyre stud bodies of rubber are furthermore better in terms of abrasive behaviour compared to those of aluminium or steel since they have a com- pletely different wear behaviour. When a tyre rolls over stones of road coverings and in particular grit of spread material close to a conventional tyre stud then the profile is heavily deformed in the tread and escapes to the side. The fixed rigid tyre stud cannot follow these escape movements. A gap thereby forms between the tyre stud and rubber which opens up the surface and lateral face of the tyre stud body to the abrasive attack of the stones. Since stones in the road covering and the grit normally have a greater hardness than aluminium and even than steel, a tyre stud body of aluminium or steel is severely worn away whereby the height of the tyre stud body and the diameter of the tyre stud body are reduced. This has the result that the edge areas of the tyre stud hole are exposed to a cutting wear. They erode whereby the gap between the tyre stud and the surrounding rubber matrix is enlarged. This favours the penetration of sand and smaller stones whereby the wear on the tyre stud body is further accelerated. As a result of this the lateral holding forces on the tyre stud are reduced leading to a reduction in the winter properties through severe canting and worst case scenario to the loss of the tyre stud.
[0006] The DE 10 2009 026112 Al relates to a conventionally designed tyre stud which is stuck in the tyre stud hole wherein first a capsule containing liguid adhe- sive is inserted into the tyre stud hole so that the tyre stud base opens the capsule when the tyre stud is inserted, the liguid adhesive flows out and fixedly bonds the tyre stud in the tyre stud hole. The liquid adhesive can also be a two-component
< 3 - adhesive wherein the second component can likewise be located in a capsule, or the tyre stud is coated with the second component before being inserted into the tyre stud hole. With each of these designs the adhesive hardens whilst producing the adhesive connection, the hardened adhesive forms a thin hard layer between a partial area of the tyre stud body and the surrounding rubber material of the tread.
[0007] The object of the invention is therefore to design a tyre stud of the type mentioned at the beginning in such a way that the wear on the road and the for- mation of fine particles can be reduced even further, wherein the grip properties of the tyre stud on icy ground, the ice performance as well as optimum hold of the tyre stud in the tread are all ensured.
[0008] This is achieved according to the invention by a tyre stud according to Claim
1.
[0009] In the case of the tyre stud configured according to the invention therefore that part which is mainly responsible for anchoring the tyre stud in the rubber ma- terial of the tread, namely the base flange, is encased with a vibration-damping rubber material. Tyre studs according to the invention are therefore embedded in the rubber material of the tread in such a way that they can absorb and dampen the forces acting on them from outside in a particularly expedient manner. The tyre stud body is furthermore preferably and more advantageously made from an abra- sion-resistant and cutting-resistant material, preferably a corresponding rubber ma- terial or a thermoplastic vulcanizate, in that area which directly adjoins the tread periphery in the case of tyre studs inserted in a tread. The abrasion of the tyre stud body is therefore well adapted substantially to that of the surrounding rubber matrix of the tread. No gaps thereby form between the tyre study body and the tread ma- terial, whereby the tyre stud retains its winter properties and ice performance throughout the service life of the tyre. Tyre studs configured according to the in- vention furthermore have an advantageous low weight for low road wear and low fine dust formation.
[0010] In a preferred design the tyre stud body consists of the vibration-damping
< 4 - first rubber material encasing the base flange at least in part, and of the abrasion- resistant and cutting-resistant material.
[0011] A design is particularly preferred in which the vibration-damping first rub- ber material encases the base flange and the pin holder of the insert, the latter at least partially. It is advantageous, particularly for the base flange, to use a casing of vibration-damping material.
[0012] A design variation is furthermore particularly preferred in which the tyre stud body has at least one further tyre stud body part of a further rubber material between the casing of the base flange of the vibration-damping first rubber mate- rial, and the tyre stud body part of the abrasion-resistant and cutting-resistant ma- terial. This measure enables tyre studs to be produced with particular embedding and damping properties.
[0013] In one possible design variation the separation plane or planes between the different materials extends or extend transversely to the vertical axis of the tyre stud in an alternative design obliquely to the vertical axis of the tyre stud, prefera- bly running at an acute angle of 60° to 85» to this. This measure enables the em- bedding and damping properties of the tyre stud body to be adapted particularly well to the respective position of the tyre stud in the tread.
[0014] The invention further relates to a pneumatic vehicle tyre having a tread with tyre studs which are embodied according to the invention.
[0015] Further features, advantages and details of the invention will now be ex- plained in further detail with reference to the drawings which show exemplary em- bodiments. In the drawings:
Fig. 1 and Fig. 2 show side views of a first embodiment of a tyre stud;
Fig. 3 shows a plan view of the tyre stud according to the first embodiment;
Fig. 4 and Fig. 5 show sectional views along the lines IV-IV and V-V of Fig. 3;
Fig.6 and Fig. 7 show side views of a second embodiment of a tyre stud according to the invention;
Fig. 8 shows a plan view of the tyre stud according to the second embodiment; and Fig, 9 and Fig. 10 show sectional views along the lines IX-IX and X-X of Fig. 8.
[0016] In the description the references such as upper, lower, perpendicular and the like refer to the positions of the respective tyre stud in the figures.
[0017] The tyre studs 1 shown in the figures (Fig. 1 to Fig. 5) and 1” (Figs. 6 to 10) have a central vertical axis a and consist basically of a tyre stud body 2, 2? and an insert 5, 5” with a tyre stud pin 3.
[0018] In the embodiment shown in Figs. 1 to 5 the tyre stud body 2 has a circular cylindrical or approximately circular cylindrical part which sits in the centre on a base flange 4 which in plan view has an approximately oval shape with two side faces running parallel to one another in the longer extent of the oval. The circular cylindrical part has a diameter which in the illustrated embodiment corresponds to the width of the base flange 4 wherein the diameter can also be slightly smaller or larger than the width of the base flange 4. With the design shown in Figs. 6 to 10, the tyre stud body 2? has a part which in plan view has an oval shape wherein the oval remains constant or substantially constant over the vertical extent of the tyre stud body 2. The oval-shaped part is arranged virtually centrally on a base flange 4? which in plan view has an approximately oval shape with two side faces running along the longer extent of the oval and running oppositely inclined at a small acute angle to a single plane of symmetry Si of the base flange 4” that runs in the longi- tudinal extent of the base flange 4’. In the illustrated design the extent of the oval part of the tyre stud body 2”, seen in plan view, coincides with that of the oval of the base flange 4°.
[0019] In both designs inside the tyre stud body 2, 2? is the insert 5, 5” which has a base part 5a, 5’a, co-forming the base flange 4, 4° and configured substantially analogous therewith, and a pin holder 5b, 5’b. In the illustrated designs the pin holder 5b, 5'b is configured cylindrical or substantially cylindrical, and the tyre stud pin 3 is anchored in its centre. The height h of the insert 5, 5? preferably amounts to 40% to 60% of the tyre stud height H. The tyre stud pin 3 projects beyond the tyre stud body 3, 3” with an end portion 3a in known way.
[0020] The insert 5, 5” preferably consists of a metal, in particular of aluminium, but can also be made of a plastic, either of a thermosetting plastic or a thermoplastic material.
[0021] The tyre stud body 2, 2? consists of different non-metallic materials, as will be explained below.
[0022] With the design illustrated in Figs. 1 to 5 the base flange 4 is encased by a first rubber material, the casing 6 also covers the upper side of the base flange 4. The pin holder 5b as well as the portion of the tyre stud pin 3 running inside the tyre study body 2 are embedded in a second material which forms a tyre stud body part 7. The end portion 3a of the tyre stud 3 projecting beyond the tyre stud body 2 can also be covered with a thin layer of this material.
[0023] The rubber material of the casing 6 of the base flange 4 has particularly good vibration-damping properties. Compositions of rubber mixtures which are suitable for producing such rubber material have long been known to the person skilled in the art of tyres. The separation plane between the casing 6 and the tyre stud body part 7 runs horizontally, therefore at right angles to the vertical axis a of the tyre stud 1. The casing 6 has for the most part a layer thickness of 0.5 to 1.5 mm in the area of the base flange 4. The layer thickness can however also be higher in terms of position, for example in the area of an indentation formed on the under- neath side of the base part 5a of the insert 5 which is filled with the rubber material of the casing 6.
< 7 -
[0024] In an alternative design, not shown separately, the casing of the first rubber material extends at the base flange 4 only up into the area of its lateral delimitation surfaces, here directly adjoins the second material.
[0025] The tyre stud body part 7 consists of a cutting-resistant and abrasion-re- sistant material, either of a further rubber material or of a thermoplastic vulcani- zate. Compositions of rubber mixtures for producing a cutting-resistant and abra- sion-resistant rubber material have long been known to the person skilled in the art of tyres. A thermoplastic vulcanizate consists in known way of at least a thermo- plastic and an elastomer wherein the thermoplastic forms a continuous phase and the elastomer forms a disperse phase finely distributed therein. Elastomer particles are therefore encased by the thermoplastic in a thermoplastic vulcanizate. The thermoplastic is or contains in particular at least a thermoplastic of the group com- prising polyurethane (PU), polypropylene (PP), polystyrene (PS), polyamide (PA) or acrylonitrile butadiene styrene copolymer (ABS). The rubber mixture of the elastomer contains as the rubber material at least one of the rubbers of the group of natural rubbers (NR), synthetic polyisoprene (IR), polybutadiene (BR), styrene-bu- tadiene rubber (SBR) and nitrile-butadiene rubber (NBR).
[0026] With the embodiment shown in Figs. 6 to 10, the base part 5’a is likewise encased by a first rubber material which, analogous with the first embodiment, has particularly good vibration-damping properties. The casing 6’ extends up into the lower region of the pin holder 5*b and forms here a separation plane, running obliquely at an acute angle of for example 5» to 30° to the horizontal, to a tyre stud body part 7’a of strip-shaped section of a further rubber material wherein the part Ta encircles the pin holder 5’b and wherein the part 7'a is adjoined by a tyre stud body part 7'b of a cutting-resistant and abrasion-resistant material, either of a rub- ber material or of a thermoplastic vulcanizate. The tyre stud body part 7'b encases the upper portion of the pin holder 5”b and the portion of the tyre stud pin 3 running inside the tyre stud body 2?, as well as optionally the end portion 3a of the tyre stud pin 3, the latter thin-layered. The separation plane between the two tyre stud body parts a and 7'b preferably runs analogously obliquely to the separation plane be- tween the casing 6” and the tyre stud body part 7’a.
[0027] Particularly in the case of tyre studs which are inserted in tread strips of pneumatic vehicle tyres bonded in the running direction, particularly advantageous embedding and damping properties of the tyre studs can be achieved by the obliguely mixed separation planes.
[0028] In an alternative design, not shown separately, the separation planes be- tween the casing 6” and the tyre stud body part 7'a and between the tyre stud body parts 7'a and 7'b run horizontally, therefore at right angles to the central vertical axis a of the tyre stud 1°.
[0029] The tyre stud body part 7'a preferably consists of a rubber material which ensures particularly good connection between the two materials of the casing 6’ and of the tyre stud body part 7'b.
[0030] In further alternative designs, not shown separately, the casing 6,6? can ex- tend higher in the vertical direction than shown, in particular also encase the pin holder 5b, 5’b at least in part, and preferably also completely enclose this in the design shown in Figs. 1 to 5. Reference numeral list
[0031] 1,1 Tyre stud 2,2 Tyre stud body 3 Tyre stud pin 3a End portion 4,4 Base flange 5,5? Insert 5a,5’a Base part 5b,5’b Pin holder 6,6? Casing
7 Tyre stud body part Tab Tyre stud body part h Height of the insert a Vertical axis H Tyre stud height Si Plane of symmetry