FIXED SPIKE, RESPECTIVELY SLEEVE-MOUNTED SPIKE, FITTED ON A VEHICLE TYRE

Abstract: A fixed spike, respectively a sleeve-mounted spike, fitted on a vehicle tyre. The fixed spike, respectively the sleeve-mounted spike, features an asymetric region which is disposed to produce a force component (F2) turning the fixed spike, respectively the sleeve-mounted spike (20) so that the fixed spike, respectively the sleeve-mounted spike (20) is arranged, at initial contact with the road surface (17), to meet the road surface (17) substantially in vertical position.

Description: Fixed spite, respectively sleeve-___unted spite, fitted on a vehicle tyre The present iirventiαn concerns a fixed spite, respectively a sleeve- mounted spite, fitted on a vehicle tyre. Increasing traffic load and spite tyres in cxxribinatiαn have proved to be a i^eαnar able road attrition factor. In seme countries this has even led to prohibition of spite tyres, or at least to considerable restrictions. In Nordic conditions, the beneficial effect of an anti-slip means on the safety and flexibility of traffic has on the other hand been irre¬ futably demonstrated, and this effect should not be sacrificed: instead, the associated drawbacks should be eliminated. Good results will be achieved by further developing both the road επjperetructures and the anti-slip tyres. As a pneumatic autancfoile -tyre rolls on an even surface, it is con¬ siderably flattened radially, owing to its flexibility, whereby in the contact region longitudinal as well as transversal forces are generated owing to changes of the rolling radius. The longitudinal forces acting on the spite when the tyre is rolling are due to bending of the body structure, to longitudinal slipping and to the stress wave in the rubber. Jhen a spite approaches the point of contact with the road, the -tyre body undergoes bending such that the radius of the bent part is significally smaller than that of equivalent parts of the load-free -tyre. This deflects the spite, which has been mounted at right angles against the surface, to assume a vertical position before contact with the road. Owing to the protrusion of the spite point, however, the spite is not turned into sufficiently upright position: it meets the road surface in an oblique position. At this stage, the forces due to slipping tendency also begin to exert their influence. As the rotating tyre surface and the protruding body (the spite) attached thereto meet the road surface, a dynamically caused impact against the road surface is produced. The attrition of the road can be significally reduced if said impact can be eliminated or reduced. The impact has been found to be due to the kinetic energy of the spite, in other words, to the mass of the spite and its velocity in the direction against the road surface. The effective mass is influ¬ enced by the spite mass itself and, in addition, by a friction force, its magnitude depending, in its turn, on the spite design in that the friction of a spite body mounted in a sleeve results from sliding between the sleeve and the metallic body, while the friction force of a fixed spite is active between the spite body and the rubber. The mass of a fixed spite is influenced, owing to its shaping, partly also by the mass of the _a__τσur__ing rubber. Prior designs have not eliminated the abrasion effect from the dynamic impact in any other way than by reducing the mass of the spite, and it is believed that the practical minimum limit has already been reached in this respect. As taught by the new invention, certain design features are suggested for the spite and the tyre with the express aim to reduce the cryramic initial contact peak and the ulti¬ mate scratch. Traditionally, the shape of the spite has been symmetric and it has been mounted in a hole, perpendicular against the wear surface of the tyre, whereby it meets the road in a slightly oblique position as the forces mentioned affect its position. The oblique contact of -the spite with the road, as well as its being pushed deeper into the tyre in oblique position during the initial part of road contact, cause damage to the rubber and to the spite which .impairs the friction properties of the spite, detract from the durability of the spite and increase its road attrition properties. The aim of the invention is to achieve an improvement in currently known fixed spite designs, respectively sleeve-mounted spite designs. The more specific aim of the invention is to provide a fixed spite, respectively a sleeve-incunted spite, in which the drawbacks embarrass- ing designs of prior art have been avoided. The aims of the invention are achieved by means of a fixed spite, respectively a sleeve-mounted spite, which is mainly characterized in that the fixed spite, respectively the sleeve-mounted spite, features an asymmetric region which has been disposed to produce a force cosjponent -turning the fixed spite, respectively the sleeve mounted spite, in such manner that the fixed spite, respectively the sleeve-mounted spite, has been arranged to meet the road surface, at initial contact with the road surface, in a position which is sub- stantially perpendicular. The rest of the characteristic features of the fixed spite, respect¬ ively sleeve-mounted spite, of the invention are presented in claims 2-8. As -taught fcy the invention, the dynamic impact force is reduced by exerting an effect cn the spite just before the onset of road contact in that its movement is stopped by directing a lifting force ccanponent thereon. In addition, the road contact is made less abrasive on the road when the spite is lifted to a more nearly vertical position in relation to the road surface; the more upright position of the spite also reduces the εκxra-t iing wear in the -terminal part of the road contact area and increases the durability of the spite in the yre. when an a_y_____fcric spite is mounted in a cx-awentional spite hole, it becomes so positioned at installation already that its road contact will take place with the spite in a position which is επjbstantially more upright against the road surface than that of an equivalent symmetric spite. Ey designing the configuration of the asymmetric beak and of the region generating the ccunterforce, and by the extent to which the spite projects, the position of the spike at the moment i_traediately before road contact is adjusted to be optimal. The invention is described in the following more in detail by refer¬ ring to seme advantageous e__ocχ______nts of the invention, presented in the figures of the drawing attached, yet to which, the invention is not meant to be exclusively confined. Fig. 1 presents an advantageous embodiment of the fixed spite of the invention. Fig. 2 presents an advantageous esι__odiment of the sleeve-mounted spite of the invention. In Fig. 1 the fixed spite of the invention in general is indicated by reference nvjmeral 10. The fixed spite 10 is cxanposed of a body part 11, a flange part 12 and a point 13. The rubber of the vehicle tyre is indicated by reference r__meral 14, and the wear surface of the tyre by reference numeral 16. AS described by the basic idea of the invention, the fixed spite 10 is made ..symmetric, m the present embodiment, asymnetry has been implemented by designing the flange 12 to be a≤ τπmetric on one margin 15. The εsy metric part 15 need not necessarily occur on the flange 12: a similar asymmetric part 15 may also be provided on the body art 11. In the most advantageous embodiment, the asymmetric part 15 constitutes a kind of beak disposed to take up the resultant of the road contact force, indicated in Fig. 1 by arrows RQ-.^ * ϊh F ^3- 1 / ■ the driving direction is indicated by arrow A and the road surface, by reference rωmeral 17. In the embodiment of Fig. 2, the sleeve-mounted spite of the invention in general is indicated by reference numeral 20. The sleeve-mounted spite 20 consists of a rivet 21, of the flange 22 of the rivet 21, of a point 23 and of a sleeve 24. The protrusion of the spite from the wear surface 16 is indicated by e. As taught by the basic idea of the invention, the sleeve 24 is pro¬ vided with an -.symmetric region 25 disposed to take up the resultant RQ-R2 of the road contact force in a way similar to that in the e__odiment of Fig. 1. In this embodiment, the asymmetric region is provided on the sleeve at a height which is substantially consistent with the location of the flange 22 of the rivet 21. The asymmetric region 25 is a claw-lite region. The asymmetric region 25 may, of course, equally be located slightly lower on the sleeve, that is, similarly as in the embodiment of Fig. 1, in other words, in the sleeve region at the height co_τe_ _ιnc__ng to the upper part of the rivet 21. The other reference riumerals correspond to those in the embodiment of Fig. 1. When the spite of the invention is installed in the hole, the spite causes a static stress region in the snrrounding rubber. When the stress wave caused by compression of the tyre meets the stress region of the spite -.symmetrically, and exceeds it, the spite turns owing to the compressed state of the rubber. At the same time, the spite is j_r__l___nced by forces arising from the rotation of the tyre. The situation is illustrated by Figs 1 and 2. In a static situation and at low speeds, the pressure effect orig¬ inating from the contact angle K of the rubber is uniform and its resultant Rg is very close to vertical. The rear margin of the rubber piece bulges cut rearwards and the contact surface, forward against the road. With higher speed, the pressure resultant turns forward in the direction R A , and the pressure pattern becomes more pror-3uncedly oval. The pressure resultant is also turned forward because in the region B the pressure in the rubber is lower since no cσmpressive force is present there. Owing to the rotation of the tyre and the compression of the rubber, the pressure resultant also moves forward to the point R2, whereby it encounters the spite flange and iπparts to it an upward acceleration, with the ccsrpαnent F x , and at the same time -turns it from the position as installed to a position more nearly perpendicular against the road surface, with the component F 2 . The spite is enabled to turn because there is no compression forward of it. It is possible to influence the utilization of said forces by the mode of installing the spite and by its shape features. A shaped st-_τ_τture also creates cn the side where said pressure resultants act, a wider local pressure region on which the pressure resultant from the compressed rubber exerts an even sore powerful effect.

Claims: Claims 1. A fixed spite, respectively a sleeve-mounted spite, fitted on a vehicle tyre, c________terized in that the fixed spite, respectively the sleeve-mounted spite, presents an asymmetric region disposed to produce a force αxtpαnent (F 2 ) turning the fixed spite (10) , respect¬ ively the sleeve-mcunted spite (20), so that the fixed spite (10) , respectively the sleeve-mcunted spite (20) , is arranged, at initial contact with the road surface (17) , to meet the road surface (17) in a εnjbstantially perpendicular position. 2. Fixed spite according to claim 1, characterized in that the fixed spite (10) is asymmetric. 3. Sleeve-mounted spike according to claim 1, C-haracterized in that the sleeve (20) of the sleeve-πounted spite is asymmetric. 4. Fixed spite according to claim 1 or 2, diεccacterized in that the flange (12) of the fixed spite (10) has an asymmetric region (15) . 5. Fixed spite according to claim 1 or 2, characterized in that the body part (11) of the fixed spite (10) has an asymmetric region (15) . 6. Sleeve-mounted spite accoπiing to claim 1 or 3, c____ract__rized in that the sleeve (24) of the sleeve-mcunted spi e (20) is asyranetric in the region co__cesponding to the flange (22) of the rivet (21) . 7. Sleeve-DMunted spite according to claim 1 or 3 , c__-__ac±er-__ed in that the asymmetric region (25) of the sleeve (24) is located sub- stantieilly in the region of the upper part of the rivet (21) . 8. Fixed spike, respectively sleeve-mcunted spite, according to any one of claims 1-7, cføracterized in that the asymmetric region (15,25) is at the same time disposed to produce a force cαπ onent (F ) lifting the fixed spite (10) , respectively the sleeve-mcunted spite (20) , whereby the velocity, due to rotation of the tyre, at which the spite and the road meet has at the same time been arranged to be sιd_€tantially reduced.

Inventors: LINDEN UNTO, LINDEN, UNTO
Applicants: NESTE OY
Application year: 1987
Main classification: B60C11
IPC codes: B60C11