WO2011138505A1

WO2011138505A1 - Vehicle winter tyre and stud for the tyre

Info

Publication number: WO2011138505A1
Application number: PCT/FI2011/050384
Authority: WO
Inventors: Heikki Salakari
Original assignee: Spikesafe Oy
Priority date: 2010-05-05
Filing date: 2011-04-28
Publication date: 2011-11-10
Also published as: EP2435261A1; RU2568621C2; RU2011147566A; FI20100194A; EP2435261A4; FI20100194A0

Abstract

The invention relates to a passenger car winter tyre equipped with studs. The number of studs in the tyre is greater than that stated in the amendment, dating 1 June 2009, to the Finnish Ministry of Transport and Communications Decree 408/2003 concerning vehicle tyre studs, in such a way that the winter tyre has more than 50 studs per one metre of the rolling circumference of the tyre. The invention also relates to a stud for a tyre, the tip of the stud, which resists wear, having a cross-sectional area of less than 3.14 mm².

Description

Vehicle winter tyre and stud for the tyre

The object of this invention is a vehicle winter tyre which is equipped with studs and which vehicle is intended for normal use.

For example Finnish patents FI- 115620 and FI- 115761 address vehicle tyre studs known as such. These studs and stud inventions aim to create lighter weight studs. Winter tyres equipped with lighter studs cause less wear on the surface material of roads, i.e. on asphalt. A stud solution, which is durable and as light as possible, has been under continuous development. Plastic and aluminium studs are known, but they are not as durable as studs with a steel body. Gravel and asphalt dust rapidly wear out the plastic or aluminium body surrounding the hard metal tip which easily leads to the hard metal tip coming off. Finnish patent applications 20080678 and 20080679 address studs and a winter tyre equipped with studs and include various solutions by which studs causing less wear to the road surface material can be created. There is a common decree in the Scandinavian countries concerning vehicle tyre studs and the measurements and use of studs. In Finland, the Ministry of Transportation and Communications has issued the corresponding Decree 20.5.2003/408 concerning vehicle tyre studs. In the decree the following is stated: area of application, the number and installation of studs, stud type approval, performer of meas- urements, the measurement of the piercing force of a passenger car tyre stud, the measurement of the piercing force of a light lorry tyre and a lorry tyre, and the studs intended for specified tyres. The new stud and its dimension according to the invention clearly fall within the permitted limits described in the Decree, although the number of studs is clearly greater than that stated in the Decree. The stud according to the invention has been thoroughly tested in various conditions by the VTT Technical Research Centre of Finland. The results achieved with the stud were compared to the limit values set in the Decree. A clear improvement in the wear of road surface material is achieved using the stud according to the invention, even when the number of studs in the tyre is doubled. The tests have indicated that only about 50 % of the road surface material wears out with the lighter weight studs as compared to other studs. Amendments to the decree mentioned above will be made on 1 June 2009, and these amendments have now been taken into consideration in this patent application.

A winter tyre according to the invention is characterized in that the number of studs in the tyre is greater than that stated in the amendment dating 1 June 2009 of the Finnish Ministry of Transport and Communications Decree 408/2003 concerning vehicle tyre studs, in such a way that the winter tyre has over 50 studs per one metre of the rolling circumference of the tyre.

As mentioned above, the tests carried out as such prove that a stud with these di- mensions wears out only half of the road surface compared to studs now in use. The tests also prove that the grip is essentially better in both acceleration and braking than with known studs. It is also worth mentioning that the number of studs in the tyre does not have an effect on the wearing out of the road surface. This is due to the fact that the area of the bottom flange is that much smaller than in known studs, that the piercing force directed at the road surface presses the stud inside the tyre. However, the piercing force of the stud tip is sufficient enough for its purpose, i.e. it penetrates an ice surface at a sufficient enough force.

The object of the invention is also a stud for the tyre, which comprises a body part with a tip which resists wear, the cross-section of the tip being essentially round- shaped. The stud according to the invention is characterized by the area of the tip of the stud being less than 3.14 mm². Various embodiments of the invention have been presented in the dependent claims. The essential facts in these embodiments are the dimensions and shape of the bottom flange of the stud, the number of studs in the tyre, and the projection of the wear-resistant tip of the stud from the surface of the tyre, as well as the position of the studs on the tread of the tyre.

Description of the invention.

The number of studs in the vehicle winter tyre is greater than that stated in the amendment to the Finnish Ministry of Transport and Communications Decree 408/2003 dating 1 June 2009 concerning vehicle tyre studs. The winter tyre has more than 50 studs per one metre of the rolling circumference of the tyre. The number can also be more than 60, 70, 80, 90 or even more than 100 studs per one metre of the rolling circumference of the tyre. The size, weight and/or shape of the stud in the tyre is such that the wear of the road surface caused by such a studded tyre is not greater than that of a studded tyre equipped with studs which fulfil requirements. The measurement of the stud piercing force and of the wear caused on the road surface by the studded tyre are performed using adequate measuring equipment, and the type approval of a stud measured in this way is valid only when used together with a compatible tyre. The projection from the surface of the tyre of the tip of the stud in a new tyre must be under 0.5 mm, and under 1.0 mm for a used tyre, advan- tageously c. 0.5-0.8 mm. The studs can be placed onto the entire area of the tyre tread. It has been established that the studs at the edges of the tyre tread cause more wear on the road surface than studs at the centre of the tread.

A stud according to the invention comprises a body part with a tip which resists wear, the cross-section of the tip being essentially round-shaped and the area of the tip being less than 3.14 mm².

The wear-resisting tip of the stud does not necessarily have to be a known hard metal tip; it can also be made of any other suitable material, such as a ceramic substance, an industrial diamond, or a carbon nitride (CN₃).

Claims

1. A vehicle winter tyre equipped with studs and which vehicle is a passenger car intended for normal use, characterized in that the number of studs in the tyre is greater than that stated in the amendment, dating 1 June 2009, to the Finnish Minis- try of Transport and Communications Decree 408/2003 concerning vehicle tyre studs, in such a way that the winter tyre has over 50 studs per one metre of the rolling circumference of the tyre.

2. A tyre according to claim 1, characterized in that the size, weight and/or shape of the stud in the tyre is such that the projection of the tip of the stud from the surface of a new tyre is less than 0.5 mm and remains less than 1.0 mm in a used tyre whereupon the wear caused to the road surface by this type of tyre is not greater than the wear caused by a studded tyre in compliance with regulations.

3. A stud for a tyre according to claims 1 or 2 comprising a body part with a tip which resists wear, the cross-section of the tip being essentially round-shaped, characterized in that the cross-sectional area of the tip of the stud is less than 3.14 mm².