The present invention relates to a movable tire stud system that allows adjustability of tire studs while a vehicle is either in motion or parked to quickly help solve the problems related to driving on slippery and icy roads.

Many attempts have been made to solve these problems. Most systems do not function properly over long periods due to the considerable wear and tear the studding equipment must endure during the course of driving. Some adjustable studding systems require air pressure to move studs in and out. Unfortunately, such systems function inefficiently. When the studs are pressed against road surfaces, the air tends to compress, thus the studs are forced back down into the tires. A similar effect of insufficient pressure is seen when air is entering vehicle brake system hoses. Other systems requires studs to penetrate the tire casing. This is considered by professionals to be quite unacceptable in the long run due to the heavy friction, wear, and tear leading to air leakage and humidity penetrating into the tire causing steel .belt corrosion and thus tire separation within a short period of time. Other known systems of movable studs are useless because the studs are either too big, too complicated, expensive, or they consist of components that are vulnerable to sandy water, frost, shocks, etc. and consequently become easily damaged, jammed, or worn too quickly.

Swedish patent application #871224 shows an arrangement of studs and consists of a movable wall which combined with the inner wall of the tire forms an air chamber. Consequently, the above mentioned problems are not solved in that system because it is based on air and requires penetration of the tire easing. German off. schrift #2602544 and #1680491 and U.S. Patent #3766956, 3340921, and 3095918 are likewise either based on the use of air or penetration of the tire casing thus leaving the above mentioned problems unsolved. Besides, such movable stud types often need much space. Moreover, when placing movable studs under or in the tire tread, a considerable tread thickness is normally required. Thick tread tends to cause tire heating and consequently reduced driving quality.

Icelandic laid-open publication #131970 also shows a system of movable studs based on air pressure and has all the disadvantages mentioned above. Furthermore, such a system of hoses rotating inside the tire at a high speed increases the danger of explosion (flat tire). Moreover, a flat tire will probably also damage this studded system.

U.S. Patent #2941566 uses fluid to move the studs, but requires penetration of the tire casing thus leaving the above mentioned problems unsolved.

Experiments confirm that the stud system mentioned herein has several advantages. First, it is more durable than the air systems of the cited publications because of the combination of stud jacks mounted in the shoulder of the unsiped tread blocks and the construction of the system being similar to a vehicle's brake system. When pressing the brake pedal, the piston in the brake cylinder is forced against the brake shoes. In the present invention, the tire studs are pressed against the road surface by an equivalent force. Another advantage is that thick hydraulic fluid or brake fluid is less likely to leak as compared to air systems. Hydraulic jacks were also considered when designing studs for varying conditions (figs. 20-28). The studs are in other words mini jacks which by the use of valves, (fig. 3. 12) may be pumped out and remain in a protruding position until a return valve (fig. 1. 1) or O-switch (fig. 13.2) is operated from the dashboard. Adjustment of the studs can also be made possible in a simple, manual fashion via a handle (fig. 5.3).

Different from the above cited publications, the studs of the present invention are mounted in extra large, unsiped shoulder blocks (fig 2.4) of the tread without penetrating the tire casing. Studs may also be mounted elsewhere on the tire tread if allowed by the tire dimensions, for instance on truck tires. Regarding this system for smaller vehicles, few tires have shoulder blocks of the tread of the necessary dimension. However, it is possible to produce such tires. Some rugged terrain tires (fig. 2) have sufficient tread thickness for mounting small movable studs without penetration of the tire casing. Adaptability of the stud system may be improved through further development.

Ice can be removed by a heating wire (fig. 3.5) which can be molded into the tire together with the hydraulic tube (optional). Air can be removed from the hydraulic tube by means of a valve at the end of the tube located on the outside of the wheel by the rim (fig. 2.6). Practically speaking, a functioning system of movable studs is required infrequently. This system gives vehicle owners the convenience of not having to change tires every autumn and spring or use chains. While traditional studding systems are in use the whole winter season and are quickly worn out, movable studs will stay sharper because they are not used as often. Sharper studs means better traffic safety. Studs being used continuously throughout the winter season also means enormous extra expenses for road maintenance as well as increased air pollution. Because stationary studs are used throughout the winter season, they must be smaller than movable studs to reduce wear on roads. Consequently, professionals point out that movable studs may protrude more than traditional stationary studs, thereby reducing the braking distance on icy roads considerably, especially compared to tires without studs. There is generally no better alternative than using tires with good studs when driving on newly fallen snow on icy roads.

Consequently, there is an obvious need for the movable stud system as presented herein. The need is met by making available a stud system of the type precisely defined in the appended patent claims.

The stud system in accordance with the present invention is hereby described more closely by referring to exemplary embodiments thereof and with reference to the enclosed drawings wherein:

Figure 1 shows the main part of the adjustable stud system except the branching hydraulic tubes to the rear wheels, here only partly shown for the right and left rear wheels (fig. 1.7)

Figure 2 shows a type of tire having rugged unsiped shoulder tread blocks suitable for this stud system. The hydraulic tube (fig. 2.8) is here indicated by a white line from the axle center to the rim edge on the inside of the rim (fig. 2.9) and further molded into the tire. The hydraulic tube may possibly cross the tire tread in one of the wear indicators, which is a thick rubber section under the tire tread. The tube will normally not penetrate the tire casing. Connection between the tube on the rim and in the tire may be made where the tire is pressed against the edge of the rim. The small tube orifice at the edge of the tire is pressed against a small tube orifice in the rim edge when the tire is inflated. If desired, a manual coupling on the outside of the tire / rim edge may be used when it is more convenient to connect the hydraulic tubes in such a manner.

Figure 3 shows a cross section of the wheel with a rotating union (fig. 3. 10) conducting the hydraulic oil into a tube or a hole / channel drilled in the axle center (fig. 3. 11), through to the valve (fig. 3. 12) under the hub cap (fig. 3. 13). Gaskets (fig 3. 14) prevent leakage of hydraulic fluid. A metal spring (fig 3. 15) pressed against the inside of the brake drum may transfer electric current from the vehicle battery to a heating wire (fig. 3.5 ) in or by the hydraulic tube or to other parts requiring supply of electric current. Wireless remote control (fig. 3. 16) may be used for the above mentioned parts if desired. Inside the rim cap (fig. 3. 17) which may have a rubber gasket, there are air tight compartments (fig 3. 18) with the ability to withstand the air pressure needed for storage of air reserves for the tires. Filling or transfer of air from the rim to the tire may be done through several valves (fig. 3. 19)

The hydraulic tube (fig. 3.8) goes from the valve (fig. 3. 12) to the edge of the rim and then into the side of the tire. The tube, molded into the outer rubber layer of the tire, is passing

so close to the pressure chambers (fig. 3.20) of the studs that it may transfer hydraulic fluid to these chambers, thereby moving the studs (fig. 3.21) when required.

Figure 4 shows a cross section of a wheel having rim compartments (fig. 4.22) for storage of hydraulic fluid. A possible air pressure in the rim compartments (fig. 4. 18) will then be able to press a flexible wall (fig. 4.23) against the hydraulic fluid, thereby stabilizing it from rippling and maintaining wheel balance when driving. In the central part of the wheel there is a dynamo on which a weight has been mounted, thereby providing a pendulum dynamo (fig. 4.24). It delivers current to an electromotor (fig. 4.25) and if necessary to a battery (fig. 4.26). Combined with the wireless remote control (fig. 4. 16) and switches on the dashboard (fig. 13) it is possible to control the in/out positions of the movable tire studs. When the driver pushes the "Stud Out" switch (fig. 13.27) on the dashboard, a signal is sent by the wireless remote control to the electromotor, making it rotate and thereby screw the piston (fig. 4.28) against the pressure chamber (fig. 4.29). In this manner the hydraulic fluid is pressed into the stud jacks, moving the studs to an extended position. If the system does not function satisfactorily due to frost, the driver may press the defrost switch (fig. 13.30) on the dashboard making a heating wire along the hydraulic tube remove the ice. When studs are no longer needed, the switch for "Studs In" (fig. 13.2) is pressed.

Figure 5 shows a cross section of the wheel having a less expensive and simpler manual stud system where a handle is used instead of electromotor, remote control etc. Piston, pressure chamber and hydraulic fluid are situated like in fig. 4. If desired, only hydraulic fluid in the pressure chamber (fig. 5.29) and only air in the other rim compartments.

Figure 6 shows a more detailed drawing of the axle part seen in fig 3. with a rotating union (fig. 3. 10). Gasket rings (fig 6.31) enclose the tight compartment where hydraulic fluid is transferred to a rotating axle center. These gaskets may be so called V-Rings, radial tightening or the like. Next to these gaskets is a ball bearing or roller bearing (fig. 6.32) and/or lock rings (fig 6.33) may be mounted. These parts are placed in an axle casing (fig. 6.34). The hydraulic fluid in the center of the axle shaft (fig. 6.35) may be kept in place without leakage when mounting or dismounting wheels by using the valve handle (fig. 6.36) to press the valve in a locked position. When using the stud system, the handle is normally turned and pulled out to keep the valve open. The valve (fig. 6. 12) may be either of the manual type previously described or for instance a remote control return / magnet valve. Between the wheel rim (fig. 6.37) and the axle part (fig. 6.35) and possibly other nearby parts like for instance the wheel drum, gaskets (fig. 6. 14) may be used to prevent leakage of hydraulic fluid. Likewise, under the hub cap (fig. 6. 13).

Figure 7 shows a simple type of wheel axle which normally is not a driving axle. No rotating union is needed here. Instead, a hole is simply drilled in the axle center (fig. 7.38) and an attachment (fig. 7.39) for the hydraulic tube.

Figure 8 shows nuts (fig. 8.40), lock disc (fig. 8.41) and split pin (fig. 8.42) to be mounted on the axle (fig. 9).

Figure 9 is an enlargement of figure 7.

Figure 10 shows a type of axle shaft requiring a rotating union. The hydraulic tube (fig. 10.8) conducts the fluid to a chamber where gasket rings (fig. 10.31) are kept in the right position by a spring (fig. 10.43). The latter gaskets are rotating with the axle and may be of the so-called V-Ring type, radial gaskets, or the like. A non rotating gasket (fig. 10.44) lies next to the above mentioned gaskets and is kept in place by screws and nuts or a lock disc. Moreover, grease and oil may be used for tightening and lubrication of the parts of this stud system.

Figure 11 shows the part of the wheel (fig. 1 1.45) normally used for disc brakes and which mount on the axle (fig. 9). The hydraulic tube (fig. 11.8) may also continue directly into the rim without passing through a valve, but that will probably cause more leakage of hydraulic fluid, for instance when mounting and dismounting wheels.

Figure 12 shows a simple rotating union to be used where the axle does not have a casing. An attachment (fig. 12.46) keeps a non rotating ring (fig. 12.47) in place. The hydraulic tube (fig. 12.8) goes through this ring. Two locking rings (fig. 12.49) keep two so-called V-Rings or radial gaskets pressed against the non rotating ring. The V-rings enclose the axle tightly and thus rotate with it. Possibly, this rotating union may be encapsulated as protection and possibly to keep grease or lubrication in place around the rings.

Figure 13 is an example of dashboard switches to be used for the hydraulic system illustrated in fig. 4. The left switch is pressed when the studs are withdrawn. The middle switch is pressed when the studs are moved out to the extended position. The right switch is pressed for removing ice from the stud system.

Figures 14 - 19 show six different examples of hydraulic tube branches in the wheel. Fig. 14 corresponds to the branches of fig. 2. Exact choice of branching will depend on the actual type of tire and wheel and long term experience.

Figure 20 shows an example of the most simple type of movable metal studs (fig. 20 & 21). It is enclosed in an unsiped tire shoulder tread block (fig. 20.4) functioning both as walls of the pressure chamber (fig. 20.50) as well as an elastic gasket. The hydraulic tube (fig. 20.8) conducts hydraulic fluid into the pressure chamber thereby pressing the stud through the narrow pass (fig. 20.51) in the stud hole. A safety valve (fig. 1.52) protects the stud from being extended further than to the position illustrated in fig 20. When there is sufficient pressure on the studs, a pressure gauge (fig. 1.53) on the dashboard alerts the driver by light or other means (fig. 1.54) . The stud is withdrawn into the tire again when the hydraulic pressure is removed. This is done by pulling a handle (fig. 1.55) on the dashboard or when pressing the left switch (fig 13.2). As long as there is enough hydraulic fluid (fig. 1.56) in the hydraulic fluid reservoir (fig. 1.57), it is possible to increase the pressure sufficiently to move the studs out by pumping the stud pedal (fig. 1.58) or by use of the switch (fig. 13.27). Possibly, grease may be pressed onto the stud holes at regular intervals when needed. A notch (fig. 20.59) will make it easier to pull out studs to be replaced. When the hydraulic fluid pressure is removed, the pressure from the road surface will press the studs back into the stud hole and through the narrow pass. To make this system function satisfactorily, an accurate adjustment of studs and stud holes is important.

Figure 21 resembles fig. 20 aside from the stud point (fig. 21.60) being straight. Testing will show whether this stud also is useful and easily exchangeable. A reinforcement belt or ply (fig. 21.61) should be a few millimeters away from the stud hole to avoid damages.

Figure 22 shows the same type of stud as in fig. 20 but the stud hole wall is of somewhat springy material (fig. 22.62), for instance Teflon, which from the outside may be worn down at the same rate as the surrounding tire tread.

Figure 23 shows a stud having close similarities to a small jack: a surrounding metal cylinder (fig. 23.63), a spring (fig. 23.64), and an elastic gasket (fig. 23.65). It is mounted into the stud hole, (may be drilled). A flange (fig. 23.66) prevents the stud and cylinder from falling out when driving. If desired, glue or adhesive may further secure it's position. The lower part may consist of a ring (fig. 23.67) if needed to support the tire stud against side bending, which at the same time may consist of a material that may be worn down at the same rate as the tire tread.

Figure 24 shows a type of stud resembling fig 23, except for an elastic gasket (fig. 24.68) to counteract moisture, sand, etc. from the road surface. The lower ring has threads and possibly glue to secure it's position if necessary.

Figure 25 shows a type of stud which may have its lower gasket screwed more tightly in place. The same applies to the upper gasket attached to the stud jack.

Figure 26 shows a simple type of stud placed directly in the tire shoulder tread block (fig. 26.4) and a return spring (fig. 26.69).

Figure 27 shows a stud like the one in fig. 26 but surrounded by Teflon or similar material which may be worn at the same rate as the tire tread.

Figure 28 shows a stud like the one in fig. 26, however, with a support ring inserted which will be worn at the same rate as the rest of the tire tread.

The stud holes of the present stud system may be molded under production, equipping the molding matrixes with molding pins of an adequate size. For some types of studs it might be sufficient to drill a hole of a suitable diameter.

If desired, protection for the studs against humidity, sand particles, and the like is possible by means of some packing gaskets, e.g. under return springs, or by a somewhat larger stud diameter on the lower part of the stud, tightening the stud hole better when the stud is withdrawn into the stud hole / stud cylinder.

A wireless remote control (fig. 3. 16) may also be mounted on the outside of the wheel with the signal transmitter placed just inside and on the edge of the mudguard, and the receiver on or nearby the rim cap (fig. 3. 17). This will give easy access for regular cleaning of the components.