FR2666053A1 - METHOD FOR DETERMINING THE DISTRIBUTION OF THE PROFILING OF THE BEARING BAND OF A TIRE. - Google Patents

Abstract

A method of subdividing the tread for diagonal groove profiling, taking into account certain characteristics of the tire such as drainage and noise generation. The tread is subdivided into V-modules. A dividing module comprises left and right elements in the middle zone and, for each of these, several dividing elements P1, P2, P3 in the areas of the shoulders. The minimum width of a shoulder element as well as the angle alpha of the obliquity of the elements of the medial zone and beta of the zones of the shoulders and in addition the width of a shoulder rib K and the offset V of division are determined according to special formulas. The division relates to diagonal arrow-shaped profiling.

Description

1 - The invention relates to a method for determining the division

  of the circumference of a tread of a motor vehicle tire Its profiled tread is composed of diagonal-shaped arrow-shaped elements formed of angled oblique grooves with an angled end. The object of the invention lies in the subdivision of this tread in the direction of the circumference by taking into consideration certain characteristics of the tire such that

  for example, adhesion to the ground when it is wet, drainage, general steering, frictional wear and precautions for noise clearance.

  The invention consists in determining the subdivision of the tread into sections of

  which are determined but selectable and which have different lengths of division depending on characteristic features of the profiling for all dimensions of the tire.

  According to an essential feature of the invention, the tread is subdivided into TM-V division modules which comprise elements 25 in the middle of the tread (P) and lateral shoulder elements (P 1, P 2). the width of the narrowest of these elements in the circumferential direction is determined by the formula

BKPU = 4

  1 in which RAD = outer diameter of the tire in mm, Pl = number of dividing elements P 1, P 2 of the same width, -2-Vi = ratio of division widths, m = number of different division widths, and the angle of orientation of the element of the middle tread module P being determined from the formula sarc sin BR nk BKPU in which J = angle of orientation of the element P of the module, that is to say the rib of the middle of the tread, measured between the edge of the module and the line of symmetry xx of the tire, BR = width of a rib of the profiling of the zone of the middle of the strip of rolling -> 13 mm, n = number of divisions of shoulder lateral element P 1, P 2, k = positive fraction of profiling in the middle zone of the tread.20 Each of the division modules TM V, which follow each other in the direction of the circumference according to the subdivision of the tread, consists of a n left element and a straight element P of division of the middle of the tread and preferably into several lateral shoulder splitting elements PI, Pu A main oblique groove of each of the right and left halves of the tire and the corresponding rib profiling of each of these halves as well as several auxiliary grooves, the shape and number of which are variable, and the corresponding auxiliary grooves of each of the zones;

  of a shoulder together form a division module TM.

  Different variants of division modules, for example different numbers of auxiliary grooves, give profiling patterns which are arbitrarily determined and aligned one after the other at the circumference of the tire. It is of importance.

  major, for the artwork of division modules, that there always exist between the different modules the same junction places which form the limits.5 Thus, these division modules determine a drawing of the profiling according to the construction system by blocks.

  The division of the dividing modules is provided along the direction of orientation of the groove and the rib of the diagonal profiling to prevent the splitting process from creating angular variations and bends in each groove and rib. . There is thus a subdivision of the tread in the zone of the shoulders from which the edges of the profiling have a radial orientation and a high number of division can be provided to lower the noise level, while in the middle zone of the tread, the orientation direction of the profiling is provided so that the angle it forms20 is as sharp as possible in order to obtain a good adhesion on wet ground and a strong reduction of the noise level. The diagonal profiling of the middle region of the tread comprises grooves and ribs which inscribe acute angles and which bend in the zone of the shoulders to take a more radial orientation A rib of the profiling which, to have rigidity required, should be at least 13 mm wide, would become large and over-proportional in the area of the shoulders, instead of bending. For this reason, the areas of the shoulders

  Thus, a large number of ribs in the profiling of the shoulder areas face fewer ribs in the middle region of the tread.

  This subdivision splits the zone of the shoulders of each individual division module into individual elements P1, P and each division element comprises a portion formed of a rib and an auxiliary groove or part of the main groove. Division modules are thus also realized by the combination of division elements of different widths. When the division width is the only one to be varied, the number of possible variants of the division module is A = m N, in which relation m = number different

  division widths and N = number of shoulder divisions in each division module This number corresponds to the number of auxiliary grooves + 1.

  For the zone of the shoulders, the compartmentalisation of the relatively broad set of

  Advantageously, the number of short ribs in the zone of the shoulders represents a multiple of the small number of ribs in the median zone of the tread in front of which they are located.

  The auxiliary grooves may have a blind end in the zone of the shoulders or they are connected to a main groove The width of the auxiliary grooves may differ from those of the main grooves It is necessary that the width of the grooves

  ribs in the zone of the shoulders are at least 14 mm so that they have sufficient rigidity and for adhesion to a wet floor, general steering and friction wear.

  When the zone of the shoulders of a division module TM consists of several grooves and ribs, these join in the zone of the main profiling in a rib and a main groove35 close to the latter. The division elements P 1, P 2 of the region of a shoulder converging into a division element P of the middle region of the tread The division module TM has in this latter zone a width ratio which has been established by forming the average of the width ratios of the dividing elements P 1, P 2, P 3 Any arbitrary division sequence is determined in the zone of the shoulders by alignment of different variants of the division module TM. However, it is necessary to optimize the division sequence of the point of division. When the division of a tread contour is constant, ie when the division elements P 1, P 2 have different widths The width of the auxiliary grooves can be equal to that of the main groove when all the dividing elements have a division ratio = 1 in the zone of the shoulders with the division module TM. narrower. The width of the rib must be at least 14 mm The division, the diagonal orientation angle of the dividing elements Pl, P 2, and the width of the rib of the shoulder element are determined by after the formula B Rsch = BKPU cos @_ks 2 14 mm, in which BR Sch = width of the rib in the zone of the shoulders, / 3 = angle of the obliquity of the orientation of the elements P 1, P 2 of the modulus or ribs of the shoulders, measured with respect to a parallel to the axis, BKPU = width of the smallest divisional element P 1, P 2 in the circumferential direction, 35 ks = positive fraction of the profiling in the area of the shoulders. The aforementioned formulas make it possible to obtain a subdivision of the tread into division modules in which the region of the shoulders, the edges of which of the profiling elements are oriented radially5 or inscribe an obliquity angle, may have a number The ribs and grooves must be rectilinear and have a relatively sharp angle in the middle zone of the tread to be oriented from the elbow into the zone. shoulders at a favorable angle of obliquity of the orientation which approximates a radial orientation. It is thus possible to obtain relatively good characteristics of wet running and noise emission. The distribution between parties

  Positive and negative parts of the profiling are symmetrical over the width of the tread and regular over the circumference due to noise and wear.

  It is possible to further improve, from the standpoint of noise clearance, profiling of a tread consisting of ribs and diagonal grooves by ensuring that the edges of the grooves 25 of the right and left areas of the shoulders do not begin or end up at the same level in the ground contact surface Thus, according to another advantageous feature of the invention, an improvement consists of shifting with respect to one another, in the direction of the circumference , the zones of the shoulders of each division element TM in V and thus the ribs and grooves of which the dividing elements

  Shoulder zones of the individual dividing modules are shifted relative to each other in the direction of the circumference so that an average offset V of the division results.

  7 - This shift of the division is determined according to the formula V = BKPU (v 1 + vm) / 4

  where v 1 = minimum of the division width ratio, 5 v = maximum of the division width ratio.

  The invention will be explained in more detail with reference to the accompanying drawings by way of non-limiting example and in which: Figure 1 is a schematic representation of a motor vehicle tire which comprises division modules which subdivide the band of

  Figure 2 illustrates in detail a division module.

  In FIG. 1, the tread L is divided into multiple circumferential division modules TM. This sharing takes into account considerations relating to certain characteristics of the tire, such as adhesion to the wet ground, drainage, general steering, frictional wear and noise clearance A division module TM comprises a left and a right element P which are in the middle region of the tread, and for each of the aforementioned elements, several divisional elements P 1, P 2, P 3 which are in the zones of the shoulders.

  The dividing module has a V shape and has an offset V of the tread areas which will be discussed in more detail in the description of FIG. 2.

  FIG. 2 shows in detail a module of the TM division. The axis of symmetry of the tread of the tire is designated by xx. The middle zone of the tread, ie the zone of the main profiling, carries the reference HP and the two zones of the shoulders, the reference Sh The limits of the -8-

  TM division module are shown in phantom.

  The direction of the diagonal, ie the direction of the obliqueness of the orientation in the main profiling zone is characterized by the angle i and the other5 direction of the diagonal, ie the direction the obliquity in the zone of the shoulders, is characterized by the angle / 3 The division module TM comprises a left element and a straight element P of the middle of the tread and, for each of these, three elements Lateral shoulders P 1, P 2 and P 3 The offset between the zones of the shoulders is designated by V. The width of the narrowest of the dividing elements P 1, P 2 or P 3 in the direction of the circumference is BKPU and is determined by the formula

B RRD

  KPU - in which RAD = outside diameter of the tire in mm, Pl = number of dividing elements P 1, P 2, P 3 having the same width, Vi = ratio of division widths and k = positive fraction of profiling zone principal.25 The zone of a shoulder is subdivided into individual elements, in the particular case in P 1, P 2, P 3 Each of these dividing elements comprises a section formed of a rib R, as well as a groove K K may be an auxiliary rib whose end is blind or part of the main groove The number of possible division variants is determined from the formula A = mn in which m = number of different division widths, -9 - n = number of divisions of a shoulder (elements of

  division) by division module, this number corresponding to that of the auxiliary grooves + 1.

  When a division is provided in two different widths, for example 1: 1.4 and a shoulder is divided into three elements, eight variants are possible. For a division 1 and another division 1,4, we obtain the division by two 1 / 1.4: m = 2. For a division of the shoulder such

  as indicated above, there are two auxiliary grooves.

  The division module TM has in the area of the main profiling a width ratio which represents the average of the width ratios of the division elements P1, P2, P3 of the zone of each shoulder; for example P 1, P 2, P 3 = 1 give P = 1; P 1 P 2 = 1, P 3 = 1.4 give P = 1.13;

Pl P 2, P 3 = 1.4 give P = 1.4.

  To obtain sufficient rigidity and bending stability, the rib D of the main profiling zone HP must be> 13 mm and the rib R of the zone of the shoulders Sh D 14 mm. Diagonal profiling for any dimensions, in which the number and shape of the auxiliary grooves are constant, is determined by the above-mentioned formula of BKPU = width of the narrowest element of division in the direction of the direction and after the angle of the obliquity of the orientation BR k arc sin mk BKPU A diagonal profile with three ribs R in the zone of the shoulders is allowed: division ratio 1 / 1.4 with 60 divisions, of which 30 are narrow and 30 -

  wide, for which Pl = P 2 = 30, v 1 = 1 and v 2 = 1.4.

  For a vehicle tire size of 205/50 VR 15, the outside diameter of the tire is 590.6 mm The positive / negative ratio must be 61% The positive / negative ratio k of the main HP area shall be

to be 58%; therefore k = 0.58.

  According to this, the calculation of B KPU gives a value of 25.77 mm and that of the angle do, a value of

16.853.

  The width of the rib R in the zone of a shoulder is calculated from the formula

RSCH BKPU cos / P ks, 14 mm.

  For the above example, this gives in the zone of the shoulders an angle of the obliqueness of the orientation 1 of 20, the positive fraction of the profiling k in the area of the shoulders being 61.2% and the width of the ribs shoulders correspond to a value of 14.8 mm It was assumed as a starting point a 61% overall positive / negative distribution ratio with a distribution

symmetrical.

  The groove of the main profiling bears the reference L and its length along the diagonal is

  The groove L and the rib D are parallel to the demarcation lines of the division module TM.

  The shift V in the circumferential direction between the zones of the shoulders Sh which are to the left and to the right of the middle part of the tread is an average of the shift of the division. It is given by the average of the hypothetical shift of smaller ratio of widths of division v 1 = 1 and largest ratio of widths vm; for example vm = 1.4. This divisional offset is calculated from the formula BKPU (V 1 + vm V = 11). This results for the above example of

  realization V = 0.6 B Kp U = 15.462 mm.

12 -

Claims (4)

  A method of determining the circumferential division of a tread of a motor vehicle tire for profiling consisting of diagonal-shaped, arrow-shaped elements formed of angled oblique grooves having a bent end, characterized by a a division module TM in the circumferential direction, which has a V-shape and which comprises the elements (P) in the middle of the rolling strip 10 and lateral shoulder elements (P 1, P 2), of which the width B Kp U of the narrowest element of the division is determined by the formula 8 KPU = 7 V   C j and the angle o L of the obliquity of the orientation of the tread center area is determined from the formula arc sin BR nkB KPU where BKPU = width of the element the most narrow of the division, 25 RAD = outside diameter of the tire in mm, Pi = number of elements of the division having the same width, vi = ratio of division widths, m = number of different division widths, 30 o = angle of division the orientation of the element P of a modulus in the middle of the tread or its rib, measured with respect to the axis of symmetry xx, BR = width of a rib of the profiling in the middle zone of the tread tread S 13 mm, n = number of the divisions of shoulder lateral element P 1, P 2, P 3 k = positive fraction of profiling in the middle zone of the tread.   2 A method of determining a division of a circumference according to claim 1, characterized in that the width of the rib of the zone of a shoulder is determined from the formula B Rsch = B Kpu Cos 0 / k S > 14 mm, in which B Rsch = width of the rib in the zone of a shoulder, / 3 = angle of the obliqueness of the orientation of the module element P1, P2, P3 or its rib of the shoulder, measured relative to a parallel to the axis, ks = positive fraction of the profiling in the zone of the shoulder. 3 A method of determining a division of a circumference according to one of claims 1 and 2, characterized in that the division module TM in the prof ilage zone has a ratio of widths which is the average of the width ratios divisional elements   (P 1, P 2) of the zone of the shoulders.   4 Process according to any one of   Claims 1 to 3, characterized in that the Sh areas   shoulders of a division module have an offset which is determined from the formula BKPU (vl vm) V = Method according to any one of claims 1 to 4, characterized in that variants of the division module are determined from the combination of existing division elements into different widths.