WO1991012972A1

WO1991012972A1 - An arrangement in studded tires

Info

Publication number: WO1991012972A1
Application number: PCT/NO1991/000029
Authority: WO
Inventors: Mindor Hesthaug
Original assignee: Mindor Hesthaug
Priority date: 1990-03-01
Filing date: 1991-02-28
Publication date: 1991-09-05

Abstract

In order to reduce road surface wear when studded tires are used and to achieve improved safety when studded tires are used on a dry road surface studded tires are used in which the studs (1) are movable between an active and a passive position. For the stud to be maintained in an active, or a passive position, respectively, it is provided in a casing (2) which is provided with a locking mechanism (3; 10, 11, 12) which can lock the stud (1) in a passive and/or an active position. Said locking mechanism may be actuated by electromagnetic means. The casing is provided with sealing means in the expansion end of the studs.

Description

An arrangement in studded tires

The invention relates to an arrangement in studded tires, in which the studs are movable between an active and a passive position, by which arrangement each stud is provided in a surrounding casing, with a locking mechanism provided in said casing to be controllable for locking in a passive/active position by the aid of electromagnetic means. Such arrangements are known from Norwegian patent applications Nos. 89 0882 and 90 0881. The invention also relates to means for electro¬ magnetic actuation of a mechanical locking means for studs in a studded tire.

Studded tires with firmly arranged studs are used in many countries, where there are icy and slippery road surfaces in the winter, and such studded tires are commonly in use during the whole witner half of the year, also for driving on dry road surfaces. The wear due to the studs is very heavy and results in yearly reparations of the road surface costing large sums, at the same time as the use of studded tires on a dry road surface causes a markedly reduced grip relative to that of tires without studs. For these reasons studded tires are totally prohibited in several countries in spite of the fact that there are slippery roads in periods of the year and a need for improved grip. This is, thus, a problem of conflict¬ ing interests, i.e. on the one hand it is desirable to use studded tires for safety, whereas, on the other hand economical reasons and considerations of wear of the road surface prohibit use of studded tires.

An obvious remedy is to make the studs movable in and out of the studded tire, and several suggestions for achieving tires with such studs that are movable by the aid of pneumatic or manual means are known. Examples of such tires with movable studs are to be found in DE-OS 16 80 491, DE-OS 26 02 544, US- PS 3 340 921, NO 3050/71, and SE 8503589-7. The concepts presented in said examples, however, proved to involve a series of disadvantages, and they were hardly affective in practice. One of the biggest disadvantages was that the tire proper had to be specially manufactured and the means that were used to move the studs, e.g. pneumatic means, made the tire disproportionally expensive. Until now a commercially applicable concept, thus, has not been found.

As mentioned above there are also previously known arrangements for moving the studs between the active and the passive position by means of electromagnetic or magnetic means. In DE-OS-2 101 225 tension rings are moved in and out of slots by means of the action from an electromagnet. A similar arrange¬ ment with a ball is described in NO patent applications Nos. 89 0882 and 90 0881.

In Japanese patent publications Nos. 62-137205, 60-154902, and 61-263808 there are described further magnetic and electro¬ magnetic arrangements for moving studs in and out of a tire.

It is an object of the present invention to provide an arrangement in studded tires, permitting the studs to move between an active and and a passive position, and permitting use of ordinary standard tires. A futher object of the invention is that it should be possible to use stud providing equipment of a conventional kind, or equipment which is at least not substantially more complicated than the kind of stud providing equipment used to day.

Another object of the invention is to provide a device permitting the studs to be activated into a position for use when this is necessary for reasons of safety, whereas the studs are in a passive position for normal driving on dry road surface, so that a most suitable grip is also maintained on a dry road surface. By the aid of the invention tires should, thus, be provided which can be used all through the year, which is of special importance for the transport trade, requiring vehicles to get on in all kinds of weather and road conditions. Another object of the invention is to provide a means that may cause activation/deactivation of the stud, so that it may be brought into an active position, and vice versa, by simple actuation. Still another object is that the movement of the stud shall not be influenced by dirt, mud, ice etc. in the environment of the tire.

Said objects are achieved by the aid of a device and a means which are characterized by the features stated in the claims. By use of the invention studs designed with a means according to the invention may be provided in standard tires, e.g. in winter tires or all-year tires, in approximately the same manner as common studs. Then the stud may be moved into an active position, its mechanism being actuated by the aid of a means according to the invention, which influences either the stud or its locking means, via electronic forces. Reversal of the forces exerted by said means will return the stud to a passive retracted position, in which it does not influence the road surface, at least not to a degree worth mentioning. Both permanent magnetic studs and non-magnetic studs may be used, a locking means in any case being provided to control the stud between said two positions and to lock it in at least one of said extreme positions. A rotating tire will, obviously, be influenced by strong centrifugal forces, which may, if desired, also be utilized in moving the stud.

As mentioned, electromagnetic actuation of the means according to the invention is used to control the stud between one and the other position, and said means may be provided immediately adjacent to the wheel, but it may also form a separate element, e.g. in a road surface, on a petrol station, in a garage, or the like. A means for retracting the stud may, e.g. be provided in the road surface, immediately outside an area where it is absolutely not desirable to use studs, e.g. in towns.

Normal pressure of the tire or the vehicle on the ground may also be used to move the stud, or rollers may be provided to push the studs back. The invention is disclosed in more detail below with reference to embodiments shown in the drawings, in which:

Figure 1 is a diagrammatic section through a tire with a movable stud, illustrating the known principle of an actuation means;

Figures 2A and 2B show a device according to the prior art with a permanent magnetic stud;

Figures 3A-3C show an embodiment of the device according to the invention in a passive position, an active position, and an intermediate position;

Figures 4A and 4B show a second embodiment of the invention in a passive, and an active position, respectively;

Figure 5A and 5B illustrate a third embodiment in a passive, and an active position, respectively, and

Figure 6 shows an alternative retraction of studs to a passive position, e.g. in connection with embodiments as shown in figures 3-5.

Figure 1 is a sectional view of a tire with a stud and an actuating unit in the form of an electromagnet. The stud means is designed with a permanent magnetic core. The actuation means is designed to be a circuit with an electromagnet, generally designated 6, a source of current 7, and a reversing switch 8 for reversing the direction of the current and, thus, the polarization of electromagnet 6 to move the stud in, and out, respectively. Such actuation means are known and are for instance described in the above-mentioned NO patent appli¬ cations.

The magnetic field from electromagnet 6 of the actuation means is assumed to influence the studs in an area of the tire, in which the studs are not in contact with the road surface. By actuation the studs are subjected to an electromagnetic force of attraction from electromagnet 6. Stud 1 will, thus be extended from its casing 2 to project from the rim of the tire like a conventional stud, and it will be kept locked in said position. The locking method is disclosed in connection with figure 2. By reversing the direction of the current, the electromagnet 6 will actuate the magnetical stud 1 in the reverse direction and at the same time actuate the locking mechanism, so that the stud is released and may again be moved into its casing 2 to be placed at a distance from the surface of tire 5.

In Figures 2A and 2B the structure according to the prior art as described in NO patent applications Nos. 89 0882 and 90 0881 is shown, and is of the a kind which may be used in the embodiment shown in Figure 1. A permanent magnetic stud 1 is provided in a casing 2, which is inserted in tire 5 in a conventional manner. In this casing the stud 1 proper is movable up and down by a distance defined by the path of movement inside the casing of foot portion 9 of stud 1. The stud may be locked in two positions by the aid of a locking mechanism comprising a bushing 3 with a locking sphere 10. Bushing 3 is movable in a slot in casing 2. In the original position, i.e. a passive position of the stud it will be in the position illustrated in figure 2A. Bushing 3 and stud 1 are then in their lowermost position. Sphere 10 is forced into the uppermost recess 11 of the lateral edge of stud 1 and keeps it locked in this position. By activation of electromagnet 6 in figure 1, the stud as well as bushing 3 which is magnetic, will be pulled up into the position as shown in figure 2B. In the course of this movement sphere 10 will be aligned with hole 13 in bushing 3 and may, thus, slide off laterally, so that the stud can move up to the position of figure 2B. When bushing 3 is in its uppermost position it will again block sphere 10, which in the meantime has reached its new position in the lower recess 11 and, thus, locks the stud in this position. By reversing the direction of magnetization the reverse process will occur and the bushing will be guided down in groove 12, the sphere will leave hole 13 and slide back into the uppermost recess 11 to lock the stud once again.

The embodiment illustrated in Figure 2 is only meant to illustrate prior art and does not belong to the invention. The disadvantage of such an embodiment is that dirt and mud may be pressed in or may follow the stud into the space between stud and casing and inhibit movement and possibly stop any displace¬ ment. In addition the actuation force must be relatively high as no assisting actuation means are provided.

In Figures 3A-C a first embodiment of the present invention is illustrated.

In the same manner as in the figure discussed above, a stud 1 is used which is movable in a casing 2, and a locking mechanism

3 is provided in said casing. Additionally, a sealing material

4 is here provided in a sealing manner about the stud and in connection with casing 2. The concept which is illustrated in figures 3A-C is based on the fact that the sealing material, e.g. a rubbery elastomer plastic, in addition has an inherent spring action which will always seek to place the stud in an expanded position, i.e. an active position as shown in Figure 3B.

The locking mechanism comprises two permanent magnetic "screw shaped" anchores of opposite polarization, one provided on each side of the stud. Said anchores are rotatable about shafts provided at 14 and forming part of the slide box or casing proper of the stud. Said anchors will cause locking due to the fact that they are provided with an inclined portion adapted to a corresponding inclined portion of the stud and a with a portion filling the cavity of the locking portion in casing 2. Turning of the anchor lock is actuated by opposed polarisation of an external magnetic field. The axes of the anchors must be oriented normal to the direction of rotation of the wheel. By turning away from the position shown in Figure 3B and by slight depressing of the stud, the locking mechanism or the inclined faces of the locking mechanism will engage the portion of the stud with an inclined face, e.g. as shown in Figure 3C, and pull the stud down. The stud will be kept down in this position. In case of wear between stud and locking mechanism it will still be possible to keep the stud off the road surface even in the position shown in Figure 3A.

The concept of this figure is most suited for activation/de- activation by units that are not provided directly on the vehicle proper, but, e.g. in the road surface, at a petrol station, in front of a road block, the mouth of a tunnel, etc. , since the weight of the vehicle will ensure deactivat- ion. Activation then must be caused when the car drives across a specially prepared grid, so that the studs can be freely expanded by the spring action of the sealing material.

If deactivation is to occur during driving by a unit in the vehicle, the design will depend on the use of a pressure roller against the tyre path, as illustrated in Figure 6.

The variant of Figure 3 may also be designed with an arrangement of the spring action of the sealing material in the opposite direction, i.e. towards a passive position of the stud. Such a design requires a strong enough combination of magnetic forces, sliding angle of the anchor portion, and centrifugal force to pull the stud out into an active position.

In Figures 4A and 4B a second embodiment of a stud arrangement according to the present invention is shown. In this concept a sealing material having spring action and seeking to hold the stud in an extended and active position is used, like in the embodiment of Figure 3. The same reference numerals as in the aboe figure are used for the stud, stud casing, locking mechanism, and sealing material.

This embodiment differs from the last mentioned in that the locking mechanism comprises two permanent magnetic slides of opposite polarization, which are provided one on each side of the stud. The slides are designated 15. The slide moves in a groove (not shown) forming part of the slide box proper in casing 2. The grooves must have an orientation normal to the direction of rotation of the wheel. In an active position the slides will lie immediately below stud 1 and lock the latter in an active position. When changing into a passive position as shown in Figure 4A, slides 15 will be pulled aside so that the stud may be pushed down either by the pressure from the road surface, or by a roller against the surface of the tire. The stud will be kept in this position by the grip of slide 15 against the inclined faces lowermost on the stud. In this case as well, there will be a sufficient surface of attack between both inclined faces to absorb a certain wear in this area. The sealing material 4 will pull the stud up from a passive into an active position by release, i.e. by pulling the slides 15 outwards.

This concept is most suitable for activating/deactivating by units outside the vehicle in the same manner as the embodiment in Figure 3. In the present case as well, it may be necessary to use a pressure roller of the kind that is illustrated in Figure 6 in order to deactivate during driving.

A further embodiment is illustrated in Figures 5A and 5B. In this embodiment there is also a stud 1, a stud casing 2, a locking mechanism 3, and a sealing material 4. In this embodiment the sealing material, however, must not have a spring action, and the sealing material may, thus, be selected from more simple criteria than in the above mentioned ^* embodiments.

The locking mechanism proper comprises a permanent magnetic screw, which is provided in a threaded hole in the central area of the stud. Said screw can be moved alternately in one or the other direction depending on actuating force from outside. The actuating force from outside acts on the screw blades 3 of the screw which are provided lowermost in casing 2 and can rotate causing a screwing movement of the screw which screws stud 1 up or down, depending on the direction of rotation. The screw blades 3 are actuated by electromagnetic force.

An embodiment of this kind will be suitable for activation/- deactivation by use of units which are provided in the vehicle, but it may also be actuated by units in the road surface or the like. It is essential in this case that the blade portions of the screw are made to rotate to cause lifting or lowering of the stud.

In Figure 6 a pressure roller means is diagrammatically illustrated. Such a pressure roller means may influence the tire tread to squeeze the stud back into a passive position, e.g. in the embodiments shown in Figures 3 and 4. The roller is raised and lowered by the aid of a hydraulic cylinder and a spring and it may, if desired, be combined with an electromagnetically acting means releasing the locking mechanism to shift the stud from an active into a passive position. An alternative illustrated lowermost in the figure shows the arrangement of such an electromagnetic actuator means in the road surface. Since the locking mechanisms should preferably be actuated in the transversal direction of the tire, such actuator means should be provided with a magnetic field the lines for force of which extend transversally, as illustrated in Figure 6.

Different embodiments are discussed above for moving the studs between an active and a passive position, and a means for use in this connection is also disclosed. It should, however, be quite obvious that such means may be designed in many different manners all incorporating the main technical solution according to the present invention.

Claims

PATENT CLAIMS:

1. An arrangement in connection with studded tires, in which the studs are movable between an active and a passive position, by which arrangement each stud is provided in a surrounding casing, with a locking mechanism provided in said casing to be controlable for locking in a passive/active position by the aid of electromagnetic means, c h a r a c t e r i z e d i n that the surrounding casing is provided with sealing means in the expansion end of the studs.

2. An arrangement as stated in claim 1, c h a r a c t e r i z e d i n that the sealing means is a resiliently biased means exerting a directed force on the stud in its direction of movement.

3. An arrangement as stated in claim 2, c h a r a c t e r i z e d i n that the stud is provided with a head outside the sealant.

4. An arrangement as stated in claims 1 and 2, c h a r a c t e r i z e d i n that below the stud in the casing a locking member which is designed for cooperation with the lower portion of the stud is provided to be rotatable or displaceable by the aid of electromagnetic actuation.

5. An arrangement as stated in claim 4, c h a r a c t e r i z e d i n that the stud has a cone shaped area at its lower portion for cooperation with corre¬ sponding faces of the locking member.

6. An arrangement as stated in claim 4, c h a r a c t e r i z e d i n that the end of the stud is cylindrically curved for cooperation with the corresponding curvature of a locking member which is transversally displace^¬ able.

7. An arrangement as stated in claim 4, c h a r a c t e r i z e d i n that the locking member has an upwards projecting screw member which is designed for cooperation with screw faces of the stud when said member is turned.

8. A means for electromagnetic actuation of a mechanical locking means for studs in studded tires, c h a r a c t e r i z e d i n that said means comprises an electric coil with a magnetizable core and that said means is provided in the wheel tread, in the wheel case above the wheel, or forms a separate member, which may be provided, e.g. in a road surface, a garage, or the like.