Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B60—VEHICLES IN GENERAL
  • B60C—VEHICLE TYRES; TYRE INFLATION; TYRE CHANGING; CONNECTING VALVES TO INFLATABLE ELASTIC BODIES IN GENERAL; DEVICES OR ARRANGEMENTS RELATED TO TYRES
  • B60C11/00—Tyre tread bands; Tread patterns; Anti-skid inserts
  • B60C11/14—Anti-skid inserts, e.g. vulcanised into the tread band
  • B60C11/16—Anti-skid inserts, e.g. vulcanised into the tread band of plug form, e.g. made from metal, textile
  • B60C11/1606—Anti-skid inserts, e.g. vulcanised into the tread band of plug form, e.g. made from metal, textile retractable plug

Definitions

• the present invention relates to a stud for a rubber tyre for a vehicle, comprising a cylinder-formed capsule in which a spring-loaded, movable core is mounted which has a flange at the lower end that abuts against a corresponding edge internally in the capsule when the core is pushed outwards in the capsule by a preloaded compression spring that lies inside a hollow space in the lower section of the capsule.
• the invention relates in particular to a spring-loaded, compressible core or point of a hard metal which is mounted internally in a capsule of steel or plastic, intended to be inserted in rubber tyres for vehicles to improve the grip on the road during wintery conditions.
• Standard studs that have been used up until now are composed of a solid casing of steel, plastic or a light metal moulded to which is a central point of a hard metal and where the point at all times has a certain length, or protrusion beyond the surface of the rubber tyre.
• Such studs can have a good effect on ice or a compact cover of snow, but have almost no function on loose ground/slushy conditions.
• the biggest disadvantage is that the studs exert much wear, with resulting unwanted economic and environmental consequences, when they come into contact with the tarmac surface on the road.
• the flange is equipped with at least one slit opening designed to let air through from the hollow space where the preloaded compression spring is located and to a hollow space which is created on the other side of the flange when the core is forced into the capsule.
• a gasket is used to provide the counter pressure, but it must be said that other means can be used, for example, the capsule can surround the core so closely that a narrow passage arises which leads to a friction effect against the pressing out.
• Another significant advantage and effect with the present solution is that the effect of the stud on ice or snow is improved, as the core of the stud can be made larger and thicker than today' s stud types and that the number of studs in each tyre can be increased due to the reduced wear .
• the compressible stud according to the invention is built up so that the core part or the point of the stud has a constant length at all times when driving on ice or snow, but that it is automatically forced into the capsule or casing of the stud when it hits a harder surface such as tarmac or concrete and that it will remain- approximately stationary in this position as long as the driving on the harder surface occurs.
• a harder surface such as tarmac or concrete
• the fact that the core of the stud lies well protected inside the capsule at all times during driving on tarmac means that it is not subjected to wear and will therefore retain its shape and good gripping characteristics over a very long time.
• the present invention is based on the basic fact that a road surface of tarmac or concrete has a much higher compressive strength than when it is covered by snow or ice.
• a compressive strength between 1.5 and 3.0 MPa (N/mm 2 ) , dependent on the temperature, while for snow it will, of course, be much smaller.
• For concrete and/or the hard particles in a tarmac surface one can assume a compressive strength of at least 35 MPa, i.e. at least 10 times higher than for ice. Normally, one can assume that a standard tarmac contains at least 70% hard particles.
• the load from each wheel will be about 4.0 kN and with a typical wheel diameter of about 550 mm the load surface against the road surface will be about 120x150 mm and the pressure against the road surface about 0.2 MPa. If one assumes about 100 studs in each tyre, about seven of these will, at any time, be in contact with the road surface. With a length, or protrusion, outside the surface of the rubber tyre of, for example, 1.5 mm, one is able to work out that the core or the core of every stud is subjected to a force corresponding to a load surface of about 1200 mm 2 or about 240 N.
• a stud core with a thickness of about 2 mm will then exert a pressure against the road surface of about 80 MPa, i.e. more than twice of what is considered to be the minimal compressive strength for a tarmac and/or concrete road surface. It is clear that if the stud core does not yield to this pressure it will lead to much wear on the road surface/tarmac and on the core of the stud itself.
• the present stud for a rubber tyre for a vehicle is characterised in that the flange is equipped with at least one slit opening arranged to let through air from the hollow space and to a hollow space that is formed on the other side of the flange when the core is forced into the capsule, and that a counter-pressure is formed inside the capsule that works against the force of the compression spring and which is arranged to provide an inertia against the core being forced out, as said counter-pressure contributes to the core having a constant protrusion outside the surface of the rubber tyre during driving on ice or snow, but during driving on harder surfaces, such as tarmac or concrete, is automatically forced into the capsule and remains approximately stationary as long as the vehicle is in motion.
• the preloaded compression spring can be conical and the enlarged section at the lower end of the capsule can also be conical, whereupon it is fastened to a base plate ring.
• the core has preferably a concave form at the top.
• the flange on the core can have several slit openings.
• a gasket can be mounted to the flange, arranged to provide said counter-pressure, with the counter-pressure being provided in the hollow space.
• Said gasket can be an elastic, lamellar gasket which is fixed in a groove in the core at the flange .
• the capsule can surround the core very closely, whereby a narrow passage is provided which gives an inertia against the pressing out of the core.
• Fig. 1 shows a stud in a load-free position in a new studded tyre Al.
• Fig. 2 shows the same as fig. 1 with the stud core being forced in past the surface of the rubber tyre Al.
• Fig. 3 shows the same as fig.l after the rubber surface is worn down to a lower level A2.
• Fig. 4 shows the same as fig.3 when the core of the stud is forced all the way in past the rubber surface A2.
• Fig. 5 shows a cross section of the stud core flange with slit openings.
• Fig. 6 shows a stud core as it meets a surface of ice B on an underlying tarmac or concrete surface C. The arrow indicates the direction of rotation for the wheel.
• Fig 7 shows the position of the studs in a studded tyre A that is either standing still or is in motion on a surface of ice or snow B.
• Fig. 8 shows the same as fig. 7 as the vehicle starts on a surface C of tarmac or concrete.
• the arrow indicates the direction of rotation of the wheel.
• Fig. 9 shows the same as fig. 7 for a studded tyre A which is in motion on a surface C of tarmac or concrete.
• Fig. 10 shows the same as fig. 7 for a studded tyre A that is standing still on a surface C of tarmac or concrete .
• Fig. 11 shows the stud according to the invention.
• the stud according to the invention has a core 3 which will yield for a force " corresponding to the preload of the conical compression spring 4. This force can, for example, be around 15 N.
• the concave form 3A of the core head will result in that pressure of penetration will be at least 2-3 times higher than the maximum compressive strength of ice. This will immediately lead to crushing of the ice underneath and in the vicinity of the stud core 3, so that the ice loses its compressive strength, and the stud core 3 will then be forced all the way down into the layer of ice almost without meeting further resistance.
• the stud core 3 will not meet any noticeable resistance, but when it hits a hard particle in a tarmac surface it will be forced into the capsule 1 with a force that, for example, can be at least 10-15 times greater than the outwardly directing spring force from the preloaded compression spring 4.
• a force that, for example, can be at least 10-15 times greater than the outwardly directing spring force from the preloaded compression spring 4.
• the distance between the innermost and outermost position of the core 3 is about 3 mm. If one assumes that the core 3, when it is not subjected to a load, is forced out in the course of, for example, 30 seconds, the movement will be about 0.1 mm per second. When driving on tarmac or concrete at, for example, 60-70 km/h, the core 3 will be "hit" against the surface 8-10 times per second and the movement of the core beyond each "hit” will consequently be only about 0.01 mm. i.e. practically zero. Thus, the inertia against being forced out, either due to a gasket or friction, constitutes an essential aspect of the present invention.
• the capsule 1 of the stud according to the invention can, for. example, be made from Teflon, a plastic material that has a self-lubricating effect and minimum friction against steel.
• the opening for the core 3 at the top of the capsule 1 can be adjusted so that a permanent pressure force/pressing force that ensures a compact, airtight and approximately friction-free connection between these two parts is established.
• the elastic lamellar gasket 5 does not need to be tightly mounted, but is adapted so that it lets in air into the hollow space 8 back to the hollow space 7 during a certain time - for example 30 seconds - when the compression spring forces the core 3 outwards when it is in a load-free stat.
• a core 3 of a hard metal and a size as given in the preceding drawings will have a mass of about 1.0 g. At a speed of about 50 km/h this mass will be subjected to an outwardly directed dynamic slinging force of about 5 N. At 80 km/h, this force will increase to about 15 N and at 100 km/h to about 23 N.
• This slinging force, together with the built-in preloaded force from the compression spring 4, will give the stud core 3 even greater penetration effect on a road surface of hard ice or snow.
• This increased penetration effect will be particular relevant at great speeds, i.e. when there really can be a need for the largest possible resistance to skidding.
• the thickness of the " stud core 3 can be much greater than for today's studs without it affecting- the ability of the stud to penetrate into a road surface of hard ice or snow.
• the reason for this is the concave shape of the top surface 3A of the core which ensures that the penetration ability on ice will be at least as great as for a stud core with only half the thickness.
• the core 3 of the stud can be manufactured, for example, with a thickness of about 4.6 mm and this will lead to a doubling of the resistance to skidding on ice or snow compared to today's studs which have a core thickness of only about 2 mm.
• the protrusion of the stud core 3 beyond the rubber surface Al and A2 will increase correspondingly and thereby provide at least the same resistance to skidding on ice or snow as for a new stud tyre. If one assumes that the stud, when it is inserted into a new studded tyre has a mounting depth of, for example, about 12 mm, the protrusion of the core 3 will be about 1.5 mm. After the rubber surface has been worn to a level A2, as shown in fig. 3, the protrusion of the stud core 3 will be twice as long. As can be seen in fig. 4, the rubber surface A2 together with the surface of the capsule 1 could be worn down even more before the stud loses its effect.
• the object of the invention is that means to at least partially counteract that the core 3 is driven out, are provided in the capsule 1, after the core 3 is forced into the capsule 1 during driving on a harder surface, as the reaction from said means is less than the pressure from the surface of ice or snow.
• This can be obtained as in the example shown above, or in that another form for counter-active force is provided.
• An alternative is, therefore, that the capsule 1 is shaped so that it surrounds the core 3 very snugly, whereby a narrow passage is provided that offers the desired inertia against pressing out the core 3.
• a "friction resistance" is provided between the contact surfaces of the capsule and the core, in contrast to what is explained above in connection with the first example and which is adapted to provide sufficient counter-acting force.
• the two described solutions can also be combined.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Tires In General (AREA)

Applications Claiming Priority (2)

Publications (2)

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Family Applications (1)

Country Status (3)

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Citations (3)

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• 2009
  • 2009-05-05 NO NO20091791A patent/NO330285B1/no not_active IP Right Cessation
• 2010
  • 2010-05-03 WO PCT/NO2010/000162 patent/WO2010128862A1/en active Application Filing
  • 2010-05-03 EP EP10772303.3A patent/EP2427338A4/de not_active Withdrawn

Patent Citations (3)

Non-Patent Citations (1)

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