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    • 专利摘要:
    ENHANCED SNOW AND DRY TIRES TIRED TIRE This invention generally relates to tires that have tread patterns with a configuration and / or properties to provide adequate snow and dry traction, and, more specifically, a tire that has a tread that has a maximum value for lamella density in the contact patch, a minimum value for the lateral groove density in the contact patch, and a minimum value for the longitudinal CSR. In certain embodiments, the pitch length of the pitches or tread repeat geometry units along the circumferential direction of the tire are within a certain range and the tread depth is below a specified value. Tires with tread that have a configuration that falls within these design parameters present a desirable level of traction in both snow and dry conditions.
    公开号:BR112014007805B1
    申请号:R112014007805-0
    申请日:2012-09-05
    公开日:2021-02-02
    发明作者:Cyril Guichon；Olivier Piffard
    申请人:Compagnie Generale Des Etablissements Michelin；
    IPC主号:
    专利说明:

    BACKGROUND OF THE INVENTION Field of the Invention
    [0001] This invention generally relates to tires that have treads with a configuration and / or properties to provide adequate snow and dry traction, and, more specifically, to a tire that has a tread that has a value maximum lamella density in the contact patch, a minimum value for the lateral groove density in the contact patch, and a minimum value for the longitudinal CSR. In certain embodiments, the pattern length of the tread pattern or repeat units of tread geometry along the circumferential direction of the tire is within a certain range and the tread depth is below a specified value. Tires with tread that have a configuration that falls within these design parameters present a desirable level of traction in both snow and dry conditions. Description of the Related Art
    [0002] Those skilled in the art are familiar with the compromise inherent in projecting a tire that has doubly good traction on snow and good traction on dry. For example, typical techniques for improving dry traction involve some increase in the stiffness of the carving, so that the tire tends to adhere to the road surface more effectively. Also, the tread geometry itself can be changed so that the tread is geometrically more rigid. This can be done in a number of ways, including removing the void area found on the tread such as sipes and / or grooves. On treads that have ribs and / or tread blocks that are defined by grooves that are necessary for wet traction and / or the prevention of hydroplaning, the tread depth can be reduced so that the tread become more rigid in the contact patch. When tread blocks are employed, the length of the tread block in the circumferential direction of the tire, which is the direction the tire rotates, can be increased.
    [0003] On the other hand, a typical method for improving tire snow traction has been to decrease the stiffness of the tread or tire tread. This can be done in a number of ways, including adjusting the material properties of the tread compound as well as its module. By decreasing the modulus of the tread compound, the tread becomes smoother and more flexible, which allows the tread to better penetrate the snow and secure or adhere to a road surface. In addition, the tread geometry can be changed to make it less rigid or more malleable. This can be achieved by adding a void area in the sculpture, including sipes and / or tread grooves. On treads that have ribs and / or tread blocks that are defined by grooves that are necessary for wet traction and / or the prevention of hydroplaning, the tread depth can be increased so that the tread become less rigid in the contact patch and so that the grooves have greater volume for snow consumption. When tread blocks are employed, the length of the tread block in the circumferential direction of the tire, which is the direction the tire rotates, can be shortened.
    [0004] As can be seen, there is an obvious and strong compromise between these two performances and associated properties of compounds and geometric configurations of the tread which are necessary to optimize these performances. A prior technical solution has been to use different treads for summer and winter times. This solution requires the sale, manufacture and placement of summer tires in the spring period and the sale, manufacture and placement of winter tires in the autumn period. While this is an excellent way to optimize tire performance, it has the significant disadvantage of cost and operational inefficiency. In other words, this costs the user and the tire manufacturer a significant amount of money to buy, assemble and manufacture two sets of tires for use on a vehicle during the calendar year. Thus, the design and sale of tires for all seasons has gained more popularity over seasonal winter and summer tires.
    [0005] However, this requires that the tread of a tire for all seasons provides properties that are suitable for dry and snow traction, and overcome the difficulty of increasing both performances without deleteriously affecting the performance of the tire. another for the reasons defined above. Normally, all-season tires do not provide snow and dry traction performance that is comparable to the predictably strong performance of seasonal tires.
    [0006] Thus, it is desirable to find a construction for the tread of a tire that can avoid traction in dry and snow conditions so that a tire for all seasons can be used throughout the civil calendar and provides a desired level of performance that is comparable to that of a seasonal tire. In addition, it would be advantageous if the solution involved some kind of optimization of the tread geometric configuration using the same tread compound. Summary of the Invention
    [0007] An apparatus characterized by the fact that it comprises a tread for use with a tire defining lateral, longitudinal and radial directions, the said tread having elements of tread and lamellae, lateral grooves and longitudinal grooves and a density associated with lamella, density of the lateral groove and contact surface ratio (CSR), in which: the device may also have a tread with a band depth less than 8.5 mm and may in fact be 8 mm.
    [0008] In some cases, the tread in addition has patterns that have an associated pattern length in which said pattern length ranges from 15 to 35 mm. Preferably, the patterning length can vary from 19 to 29 mm.
    [0009] The tire using said tread can be a tire size 205 / 55R16.
    [0010] In this case, the tread can have two circumferential grooves that have a width ranging from 8 to 10 mm. In addition, their sipes can be spaced about 10 mm away from each other in the longitudinal direction of the tire. This tread can have two additional circumferential grooves that have a width ranging from 3 to 5 mm.
    [0011] In some cases, the tread elements are in the form of tread blocks.
    [0012] In other applications, the longitudinal CSR is in fact 0.87.
    [0013] In some cases, the density of the lateral groove is 38 mm-1.
    [0014] In yet another modality, the lamella density is 20 mm-1.
    [0015] In some modalities, in addition to the optimization of lamella density, lateral groove density and longitudinal CSR, there may also be a variation between the intralamela distance in the tire shoulder region and the intralamela distance in the central region of the tire. In particular, the intralamela distance measured between adjacent lamellae in the shoulder region of the tire measured in the longitudinal direction may be greater than the intralamela distance measured between adjacent lamellae in the central region of the tire measured in the longitudinal direction. In addition, there may be a chamfer found in a plurality of side grooves along its side edges.
    [0016] The precedents and other objects, features and advantages of the invention will be evident from the following more detailed descriptions of certain modalities, as illustrated in the accompanying drawings, in which similar reference numbers represent similar parts of the invention. Detailed Description of Drawings
    [0017] Fig. 1 is a top view of a footprint area of a PRIMACY MXV4 tire.
    [0018] FIG. 2 is a top view of the ground contact area of FIG. 1 showing its contact patch and its associated area Ac using hatch.
    [0019] FIG. 3 shows examples of patterns using the ground contact area of FIG. 1.
    [0020] FIG. 4 is an example of how the lamella density (SD) of a pattern is calculated using the pattern of FIG. 3.
    [0021] FIG. 5 is an example of how the lateral groove density (LGD) of a pattern is calculated using the pattern of FIG. 3.
    [0022] FIG. 6 is a top view of the ground contact area of FIG. 1, showing its longitudinal groove area Along using narrow hatch.
    [0023] FIG. 7 shows the area represented by the quantity (Ac - Along) for the area of contact with the soil of FIG. 1 using hatch.
    [0024] FIG. 8 is a top view of a tire ground contact area according to the first embodiment of the present invention.
    [0025] FIG. 9 is a top view of the ground contact area of FIG. 1 showing your contact patch and its associated area Ac.
    [0026] FIG. 10 shows an example of patterns using the ground contact area of FIG. 8.
    [0027] FIG. 11 is an example of how the lamella density (SD) of a pattern is calculated using the pattern of FIG. 10.
    [0028] FIG. 12 is an example of how the lateral groove density (LGD) of a pattern is calculated using the pattern of FIG. 10.
    [0029] FIG. 13 is a top view of the ground contact area of FIG. 8 showing its longitudinal groove area Along.
    [0030] FIG. 14 shows the area represented by the quantity (Ac - Along) using hatch for the area of contact with the soil of FIG. 8.
    [0031] FIG. 15 is a graph showing that, for a given lateral groove and lamella density, increasing the longitudinal CSR avoids traction / braking compromise in snow versus dry.
    [0032] FIG. 16 is a partial top view of a real tread that makes contact with the ground of FIG. 8.
    [0033] FIG. 17 is a partial perspective view of a tread according to a second embodiment of the present invention.
    [0034] FIG. 18 is a partial top view of a real tread according to a third embodiment of the present invention.
    [0035] FIGS. 19 through 22 show the groupings of scenarios that fit within the optimized parameter windows of the present invention (FIGS. 19 through 21) and their expected associated performance of dry braking and snow traction (FIG. 22).
    [0036] FIGS. 1 through 14 are ink graphics of the ground contact area of a tire that is under an operating load. It is to be understood, therefore; that the dimensions indicated are slightly different from the dimensions of the tire in an undeviated state. For the sake of clarity, all values for the given dimensions that are associated with FIGs. 1 through 14 are for the tire in a deflected state. For a passenger car, measurements are taken by an area of contact with the ground of a passenger car tire when that tire is loaded at 85% of the maximum load as marked on the sidewall of the tire with an inflation pressure of 35 psig. For a light truck tire, measurements are taken by an area of contact with the ground of a passenger car tire when that tire is loaded at 85% of the maximum load (single) as shown on the sidewall of the tire with the associated inflation pressure as marked on the sidewall of the tire. Definitions
    [0037] The longitudinal or circumferential direction, X is the direction of the tire along which it rolls or rotates and which is perpendicular to the axis of rotation of the tire.
    [0038] The lateral direction, Y, is the direction of the tire along the width of its tread which is substantially parallel to the axis of rotation of the tire.
    [0039] The radial direction, Z, is the direction of a tire, as seen from its side, which is parallel to the radial direction of the tire's generally annular shape and is perpendicular to its lateral direction.
    [0040] By groove, is meant any channel in the tread of a tire that has two opposite side walls leading from the top of tread surfaces and that are spaced at least 2.0 mm apart from each other , that is, that the average distance of separation of the side walls between the upper opening of the channel and the bottom of them is on average equal to or greater than 2.0 mm. By the lateral groove, we mean a groove that extends in a direction that is oblique to the longitudinal direction. By longitudinal groove, we mean a groove that extends substantially in the longitudinal direction.
    [0041] By a lamella, is meant any incision that is less than 2.0 mm and has side walls that come in contact from time to time, according to the tread block or rib that contains the incision rotates inwards and out of the tire contact patch as the tire rotates on the ground.
    [0042] Tread element means any type or shape of a structural feature found in the tread that comes into contact with the floor. Examples of tread elements include the tread blocks and ribs.
    [0043] Rib is an element of the tread which travels substantially in the longitudinal direction X of the tire and which is not interrupted by any grooves running in a substantially lateral Y direction or any other grooves oblique to it.
    [0044] Tread block means a tread element that has a perimeter defined by one or more grooves, creating an isolated structure in the tread.
    [0045] By area of contact with the ground, it is understood the area of contact between the tire and the ground or road surface as the tire rotates. Your area excludes those areas that do not actually touch the road or the ground. An area of contact with the ground 100 of a tire is shown in Figure 1 and is defined by the sinuous perimeter of each tread element of the tread shown therein. So, its area is equivalent to the area shown that is hatched. In contrast, contact patch 102 is defined by the outer perimeter of the area shown in figure 2 designated by line 104 and is not defined by the amount of void area found within the area in contact with the ground. The contact patch area A c is the area surrounded by line 104 unaffected by any void areas found there as best seen in figure 2.
    [0046] By pattern 106, it is understood a repetitive geometric pattern of a tire tread that is organized in a circular arrangement over the circumference of a tire. In many cases, these patterns are molded using identical mold components also arranged in a circular arrangement over the circumference of a mold that forms and heals the tire tread geometry. See Figure 3 for an example of a pattern 106 in the ground contact area 100 of a tire. In some cases, a tire's tread design may consist of several unique geometric patterns or patterns that are each duplicated around the circumference of the tire as is the case here. Note that a first pattern 106 is repeated twice and is adjacent to another pattern 106 '. This difference between patterns is more noticeable when looking at the presence of two tread blocks 108 'in the intermediate lines 107 of the tread blocks 109 of pattern 106' while a single tread block 108 is in the same position for pattern 106. This pattern of 2-1 is repeated across the circumference of the tire.
    [0047] Lamella density (SD) means the projected total length of the lamellae (Ls) divided by the approximate area of the contact patch (Ap) of a single pattern independent of those areas that do not actually touch the floor, such as example, due to the presence of a void area. As shown in Figure 4, this approximate area (Ap) is calculated by multiplying the width of the ground contact area (FW), measured in the lateral Y direction from the leftmost part of the ground contact area to the rightmost part of the area in contact with the ground, by the patterning length (PL), measured in the longitudinal direction X from the midpoint of a lateral groove 112 that forms the anterior end of the patterning to the midpoint of another groove forming the posterior end of pattern 112 as best seen in Figure 3.
    [0048] The predicted length of the lamellae (Ls) is calculated by adding their individual lengths. The projection is made along the Z direction on the road surface or the XY plane and the distances are measured in the Y direction. The length is measured in millimeters and the area is measured in mm2 and the ratio is then multiplied by 1000. This relationship it can be expressed in terms of the following equation: where the units of the calculation are reciprocal mm. An example of this calculation is shown in figure 4 where fifteen slides 110, designated L1 through L15, are used to calculate the SD. Note that two slides 108 are shown on each tread block 110 of pattern 106 shown in Figure 4.
    [0049] In some cases, where the tread pattern is made up of different patterns, then the lamella density (SD) of the tread pattern is the weighted average of the lamella density of each pattern (SDw) of the pattern of tread. Weighing is based on the percentage of circumference of a given pattern around the tread pattern. For example, in the situation where there are three different patterns used in the circumference of the tire, the weighted average can be calculated using equation 2 below:

    [0050] When there are three different patterns being used, then SDw is calculated as follows, using the following data: Pattern Length 1: PL1 Pattern Number 1: PL1 Pattern Density of Pattern 1: SD1, as calculated using EQ . 1 Patterning Length 2: PL2 Patterning Number 2: NP2 Lamella Density of Patterning 2: SD2, as calculated using EQ. 1 Pattern Length 3: PL3 Pattern Number 3: NP3 Lamella Density of Pattern 3: SD3, as calculated using EQ. 1, and equation 2 becomes:

    [0051] As an additional example, when these variables have the following values: PL1 = 35 mm, NP1 = 20, SD1 = 50, PL2 = 30 mm, NP2 = 25, SD2 = 60, PL3 = 25 mm, NP3 = 30, SD3 = 70; then the weighted SDw is calculated to be 60.23.
    [0052] Lateral groove density (LGD) means the projected total length of the lateral grooves (L1) divided by the approximate area of the contact patch (Ap) of a single pattern, regardless of those areas that do not really touch the floor, for example, due to the presence of an empty area. This approximate area (Ap) is calculated by multiplying the width of the ground contact area (FW), measured in the lateral direction Y by the pattern length (PL), measured in the longitudinal direction X, while the projected length of the lateral grooves is calculated through the sum of their individual lengths, all in the same way as described above for the lamella density (SD). The projection is made along the Z direction on the road surface or the XY plane and the distances are measured in the Y direction. The length is measured in millimeters and the area is measured in mm2 and the ratio is then multiplied by 1000. This relationship can be expressed through the terms of the following equation:
    where the units of the calculation are reciprocal mm. An example of this calculation is shown in figure 5 where eight side grooves designated G1 through G8 are used to calculate the LGD. Note that the presence of these side grooves 112 is actually immediately adjacent to the pattern shown in the forward or backward direction X. In other words, the side grooves are not actually shown, but can be seen by following the line that defines the extent further forward or backward from pattern 106 shown in figure 3. In addition, the calculation is performed by only a set of lateral grooves that define the field and not for both.
    [0053] In some cases, where the tread pattern is composed of different patterns, then the Tread Groove Density of the tread pattern is the weighted average of the Tread Groove Density of each pattern of the tread pattern. . Weighing is based on the percentage of circumference of a given pattern around the tread pattern. For example, in the situation where there are three different patterns used in the circumference of the tire, the weighted average can be calculated using equation 4 below:

    [0054] When there are three different patterns being used, then LGDw is calculated as follows, using the following data: Pattern Length 1: PL1 Pattern Number 1: NP1 Lateral Density of Pattern 1: LGD1, as calculated using the EQ. 3 Patterning Length 2: PL2 Patterning Number 2: NP2 Lateral Density of Patterning 2: LGD2, as calculated using the EQ. 3 Pattern Length 3: PL3 Pattern Number 3: NP3 Lateral Groove Density of Pattern 3: LGD3, as calculated using EQ. 3.

    [0055] As an additional example, when these variables have the following values: PL1 = 35 mm, NP1 = 20, LGD1 = 50, PL2 = 30 mm, NP2 = 25, LGD2 = 60, PL3 = 25 mm, NP3 = 30.
    [0056] LGD3 = 70, so the heavy LGD is calculated to be 60.23.
    [0057] Due to the longitudinal contact surface (longitudinal CSR), the contact surface ratio of the longitudinal grooves is understood. This is the total projected area of the longitudinal grooves (Along) found in the contact patch at any instance of time as the tire rotates divided by the total area of the contact patch (Ac) regardless of those areas that do not actually touch the ground, such as example, due to the presence of a void area (see Figure 6 for an example of Along). The projection is made along the Z direction on the road surface or the X-Y plane. Both areas are measured in mm2. This relationship can be expressed through the terms of the following equation: CSR longitudinal = (Ac mm2 - Along mm2) / Ac mm2 EQ. 5 where the equation results in a dimensionless number. An example of the amount of (Ac mm2 - Along mm2) for the area of contact with the soil in Figure 1 is shown by the area hatched in Figure 7. Detailed Description of Specific Modalities
    [0058] Modalities of the present invention include constructions that modify the stiffness of the tread elements found in the tread of a tire in order to avoid the compromise found between snow and dry traction performances. It should be noted that any, all or any combination of the modalities discussed below may be satisfactory to obtain these desired performances, depending on the application. In addition, these techniques can be used on a number of tread elements, including tread blocks and ribs.
    [0059] Looking again at Figure 1, a top view of an area of contact with the ground of a tire tread that was previously used in a tire for all seasons can be seen. This is a tire size 205 / 55R16 currently sold by the assignee of the present invention under the trademark PRIMACY MXV4. This tire has six longitudinal grooves 114, two intermediate lines 107 of tread blocks 108, two central ribs 116 and four shoulder lines 118 of tread blocks 108. The width of the longitudinal grooves varies from 8 to 10 mm in the center of the tread and is about several millimeters for the grooves found on the shoulder of the tread and the distance between adjacent sipes 110 is, on average, about 8.5 mm in the longitudinal direction X.
    [0060] Referring again to Figures 2 through 7, the components that are used to define and / or calculate the design parameters defined above for this tire, including lamella density, lateral groove density and longitudinal CSR are shown. In figure 2, the total surface area or A c in the contact patch is shown as described by line 104 while Figure 3 defines the patterns for this tire that are repeated over its circumference. Figures 4 and 5 show the length portions used to measure the length of the lamellae and lateral grooves. Figure 6 shows the surface area shown by the design regions used to calculate Along. Finally, Figure 7 depicts the amount of (Ac mm2 - Along mm2) for the area of contact with the soil in Figure 1 using a hatched pattern. Note that the number of patterns and tread depth is not shown in any of the figures for this tire.
    [0061] Figure 8, on the contrary, shows the area of contact with the ground 200 of a modality of the present invention. This tread is used in conjunction with a tire size 205 / 55R16 and has three center lines 207 of tread blocks 208 and two shoulder rows of tread blocks 208 separated by four longitudinal grooves 214. The width of the grooves is about 9 mm, for the two central longitudinal grooves and about 3.5 mm for the two outer longitudinal grooves and the distance between a lamella 210 and one end of the tread block 208 is about 10 mm in the longitudinal direction X. The tread blocks are furthermore defined by lateral grooves 212 that have a general corkscrew shape orientation.
    [0062] In a similar manner as mentioned above, Figures 9 through 14 show the components that are used to define and / or calculate the design parameters defined above for this tire, including lamella density, lateral groove density and longitudinal CSR. In figure 9, the total surface area or Ac in the contact patch 202 is shown as described by line 204 while figure 10 shows the definition of a single pattern 206 for this tire. Unlike PRIMACY MXV4, there is only one pattern that is repeated around the entire circumference of the tire. Figures 11 and 12 show the length portions used to measure the length of lamellae 210 and lateral grooves. Figure 13 shows the surface area shown by the hatched regions used to calculate Along. Finally, figure 14 depicts the amount of (Ac mm2 - Along mm2) for the area of contact with the soil in Figure 8 using a hatched pattern. Note that the number of patterns and tread depth is not shown in any of the figures for this tire.
    [0063] The calculated values of these parameters for the state of the art band shown in figure 1 and the tread configured according to a modality of the present invention, as shown in figure 8 are contained in table 1 below. In addition to lamella density, groove density and longitudinal CSR, additional design parameters, including the pattern length, which is associated with each pattern or geometric pattern that is repeated along the circumference of the tire in the X direction, as well as the depth standards, are also given. A smaller patterning depth improves dry braking, but worsens snow traction. Decreasing the number of patterns or increasing the patterning length, while maintaining the longitudinal CSR is better for dry braking and worse for snow traction. In many cases, the mold components that make a repeating pattern or geometric pattern of a tread are identical so that several sets are used. Therefore, the number of patterns is generally equal to the number of identical mold components that are used to form the tread.
    [0064] Since the PRIMACY MXV4 uses two different types of patterns that are organized in a 2-1 repetitive sequence over its circumference, while modality No. 1 uses only one pattern that is repeated over its circumference, the lamella densities and mean lateral groove of the PRIMACY MXV4 tire were calculated in a weighted way using equations 2 and 4 respectively, while the lamella density and lateral groove density of mode no. 1 were calculated using equations 1 and 3, respectively. Consequently, it is contemplated that tires with multiple patterns that have different configurations would have their lamella densities and lateral furrow densities calculated using the weighted average method similar to equations 2 and 4 and these values would determine their performance and whether they are covered by the added claims. .Table 1
    * Correction of typo in the origin order.
    [0065] As can be seen, the previous tire has a longer tread length, more or less the same tread depth, smaller longitudinal CSR, lower lateral groove density and higher lamella density than the first modality of present invention discussed in this document. Looking at the respective figures that graphically show the components that make up these parameters, the contrast between these tires in the geometric configuration of their tread is apparent. For example, the distance between the side grooves for mode No. 1 is less than for the PRIMACY MXV4 tire. In fact, it is believed by the inventor (s) that the PRIMACY MXV4 tire is representative of the state of the art and was consequently chosen as the reference tire. Research conducted by the inventors indicates that a typical all-season tire that is currently on the market has a pattern length greater than 35 mm, a lateral groove density that is less than 30 and a longitudinal CSR that is less than 0.85. As evidenced below, changing one or more of these parameters produced critical and unexpected results.
    [0066] Both the PIRMACY MXV4 tire and the tire according to the first modality of the present invention were tested in dry braking and snow traction. More precisely, they were tested for dry braking by measuring the required braking distance from 96.5 km / h to 0 km / h for a vehicle that has tires fitted for testing. This test is carried out on a dry asphalt surface by means of sudden braking. A higher value than that of a reference tire, which is arbitrarily set to 100, indicates an improved result, that is, a shorter braking distance and improved dry grip. Snow traction was measured using the GM rotation test which is well known in the technical field (also known as ASTM F1805). The results are shown in Table 2 below. Unexpectedly for someone with a common skill in the technique, an increase in dry braking of about 4% and snow traction of about 28% has been achieved. Not only is the amount of unexpected improvement, especially the 28% increase in snow traction, but the fact that both snow and dry traction have been improved simultaneously shows that the critical result of avoiding dry snow traction compromise has been achieved, at least in part, by changing these design parameters.Table 2

    [0067] The inventor (s) believe that, by changing the design parameters, particularly, increasing the longitudinal CSR, increasing the density of the lateral groove and decreasing the lamella density, that the the void area necessary to consume snow and to provide a malleable tread that increases snow traction, it can be used without negatively impacting dry traction. Instead of using a large number of sipes that negatively impact dry traction, fewer sipes are used and more grooves. Thus, the sculpture was duly rigid, having a low lamella density and also having a large void area for snow consumption. Consequently, dry traction has not been affected in a deleterious way but has actually been improved, while at the same time snow traction has also been improved.
    [0068] Looking now at Figure 15, the way in which the compromise between snow traction and dry traction / braking has been avoided can be seen more clearly. This graph shows that for a given lateral groove and lamella density, there is close to a linear relationship between dry and snow traction. This means that, for a given lateral groove and lamella density, depending on the dimensions and locations of the grooves and lamellae, there is a strong compromise between dry and snow traction, such that, improving the performance of one, the other is negatively affected . However, by increasing the longitudinal CSR, this linear relationship is shifted to the right as shown in the graph, avoiding this compromise and improving snow traction while maintaining dry traction / braking. Having a first order effect, the tread stiffness is proportional to the reciprocal of the sum of the lamella and groove densities. Since the efficiency of a groove is greater than the efficiency of a slide for snow traction, increasing the density of the lateral groove and the longitudinal groove CSR and decreasing the density of the lamella increases the performance in snow, while simultaneously the performance in dry conditions it is also improved due to the increase in the tread stiffness.
    [0069] In fact, this improvement is attributable to additional tread features other than simply lamella density, lateral groove density and longitudinal CSR optimization alone. Turning to Figure 16 where a part of the actual tread 200 of the first mode is shown, for example, the tread also varies in the distance between the sipes 210 found in the central parts of the tire's tread in the direction circumferential X, which in this case are the central rows of tread blocks 207, and in the shoulder portions of the tire tread, which in this case are the shoulder rows of tread blocks 208. In particular, it is it is desirable to have a greater distance between adjacent lamellae in the longitudinal direction X in the shoulder regions than in the central region of the tread. As mentioned earlier, the distance between sipes is approximately 10 mm in the longitudinal direction X of the tread. Note that there is no lamella in the shoulder parts, which is equivalent to having an infinite distance between the lamellae. This increase in the distance between sipes in the shoulder regions of the tire has a positive impact on snow traction without negatively affecting dry braking performance. It is ideal if the distance between sipes found in the central part of the tread is at least half that compared to the shoulder part of the tread.
    [0070] Likewise, another feature is present that helps to improve both dry braking and snow traction. This feature is the addition of chamfers 216 at the lateral ends of the tire grooves 214. It is ideal for the chamfers to form a 45 degree angle with the tangent of the tire circumference and to have a 1.5 x 1.5 mm configuration in which the chamfer length is measured in a direction that is perpendicular to the turning axis. of the lateral groove and its depth is measured in the Z direction. In order to optimize the improvement of traction in snow, it is ideal that the width of the lateral groove, measured in a direction that is perpendicular to the axis of rotation of the groove, is between 2 to 4 mm. More information on this technique can be found in the patent application published on. WO2011062595 (A1), which is commonly owned by the assignee of the present invention.
    [0071] Using simulation tools, the inventors of the present invention determined the relative contribution to snow and dry traction provided by the variation of intralamellar distance between the central and shoulder parts of the tire and the chamfer characteristics subtracted from the performances observed in test so that the actual contribution provided by optimizing lamella density, lateral groove density and longitudinal CSR can be calculated. Table 3 below gives this information.


    [0072] As can be seen, the largest gain in snow traction of 13% and the second largest gain in dry traction of 1.5% were achieved through the optimization of lamella density, lateral groove density and longitudinal CSR. Also, both dry braking and snow traction have been improved simultaneously, indicating that the present invention avoids compromising between dry and snow traction, which is a surprising result.
    [0073] Figure 17 shows a second modality of a tread 300 of the present invention which is a tire size 205 / 55R16 that uses a Chevron design of lateral grooves 312 that have no lamellae in the shoulder regions and neither any type of longitudinal groove. The width of the lateral grooves varies from 2.5 mm to 6 mm and the angle of rotation that they form with the circumferential direction near the center of the tire is approximately 45 degrees and the angle that they form near the shoulder regions is close to 90 degrees. The side grooves 312 also have chamfers 316 configured in the same way for what was described for the first modality. Finally, the distance from a 310 slide to the end of a tread block or side groove is approximately 9.5 mm in the X longitudinal direction. The relative comparison of the design parameters calculated as defined above between the PRIMACY MXV4 tire and the second modality is shown below in table 4.Table 4

    * Correction of typo in the origin order.
    [0074] As can be seen, there is a significant difference between lamella density, lateral groove density and longitudinal CSR for these respective tires. Tests of the second modality were performed and their snow and dry traction performances were compared with those of the PRIMACY MXV4 tire and the relative contributions of various resources to the improvement in both performances were calculated in a similar way to that used for the first modality. above. These data are provided below by Table 5.Table 5

    [0075] This modality had as its highest gains for dry traction and snow traction about 5% and 50% of those that are attributable to the optimization of lamella density, density of the lateral groove and longitudinal CSR. Again, the compromise between snow and dry traction has been demonstrated to be avoided, as both performances improved simultaneously and a 50% gain in snow traction is surprisingly high. Therefore, these results are critical and surprising for someone skilled in the art.
    [0076] Still a third modality is shown by Figure 18. This embodiment comprises a tread 400 for a tire size 205 / 55R16 that has lateral grooves oriented in the form of a corkscrew 412, a series of angled lateral grooves 414 connecting some of the corkscrew-shaped side grooves 412, chamfers 416 in a plurality of side grooves 412 and an intralamellar distance 410 in the shoulder lines 408 of the 12 mm tread blocks and intralamellar distance 410 in the central rows 407 of 7.5 mm tread blocks. The width of the side grooves varies from 2.5 mm to 8 mm. The relative comparison of the design parameters, calculated as defined above between the PRIMACY MXV4 tire and the third modality, is shown below in table 6. Table 6
    * Correction of typo in the origin order.
    [0077] Again, there is a significant difference between lamella density, lateral groove density and longitudinal CSR for these respective tires. Tests of the third modality were performed and their snow and dry traction performances were compared with those of the PRIMACY MXV4 tire and the relative contributions of various resources to the improvement in both performances were calculated in a similar way to that used for the first modality. above. These data are provided below by Table 7.Table 7

    [0078] Looking at these results, it appears that when using all three feature sets, that dry braking was essentially maintained and that snow traction increased by 66%. This makes this tire a good candidate for those who need good traction on snow and cannot accept the lack of improvement in dry braking. However, the adjusted figures indicate that this modality lost 3.5% of dry braking due to the optimization of lamella density, lateral groove density and longitudinal CSR. This decrease is attributable, in part, to the increased 9 mm tread depth compared to the smaller tread depths of the first and second modes. Despite this, the optimization of the present invention provided a 49% improvement in snow traction. This huge increase in snow traction is still surprising for someone skilled in the art.
    [0079] Using the same simulation tools above, the inventors determined a window of parameters that would give these surprising results, by mapping various scenarios with specified longitudinal CSR, lamella density and lateral groove density, while maintaining the other parameters of design the same as the CSR and tread depth. These scenarios were then plotted on a graph showing their respective snow traction and dry braking performance.
    [0080] Looking at Figures 19 to 22, it can be seen that it is possible to improve the traction in snow and in the dry of a tire tread when the lateral groove density is greater than 35 mm-1, lamella density is less than 40 mm-1, and the longitudinal CSR is greater than 0.85. These numbers show that when these parameters are within these ranges, then an improvement in snow traction is almost always achieved and that in many instances, dry braking is also improved, avoiding the compromise between snow traction and dry braking (better seen in figure 22). This can be seen by looking at the correlation of those meeting points that fall within the windows of the present invention and those that do not fall within the windows of the present invention. In these cases when dry braking is somewhat negatively impacted, this can be counteracted by adding other features such as using a variation in the intralamellar distance between the central and shoulder regions of the tire and / or adding chamfers to the grooves lateral, as was the case Modality N ° 3. The inventors also believe that it is useful if the average pattern length of the patterns or repetitions of identical geometric tread patterns is between 15 and 35 mm and preferably between 19 and 29 mm and the tread depth is less than 8.5 mm for reasons explained above.
    [0081] As can be seen, certain embodiments of the present invention help to avoid compromise between dry and snow performances both in combination and by themselves. Thus, different combinations of modalities discussed in this document are foreseen by the inventor and are considered part of the disclosure and can be useful for different tire applications. For example, having only specified ranges of longitudinal CSR values, lamella density and lateral groove density may be sufficient to practice the present invention.
    [0082] Although this invention has been described with reference to specific modalities thereof, it should be understood that such description is by way of illustration and not by way of limitation. For example, the present invention can be combined with material properties of the tread rubber to produce other improvements. Similarly, this invention can be applied to tires having all types of tread elements, including ribs and tread blocks. In addition, particular dimensions have been given, but it is within the competence of someone skilled in the art to make adjustments to these dimensions and still exercise the spirit of the present invention. Thus, the scope and content of the invention should be defined only by the terms of the appended claims.
    权利要求:
    Claims (15)
    [0001]
    1. Tire characterized by the fact that it comprises a tread (300; 400) defining lateral, longitudinal and radial directions (Y, X, Z), said tread having tread elements and sipes (110; 210 ; 310), lateral grooves (212) and longitudinal grooves (114; 214) arranged in one or more patterns (106; 206) around the tire and having a lamella density (SD) less than 40 mm-1, the density lamella density defined as a weighted average of a lamella density of one or more patterns, the lamella density of a single one or more patterns being expressed as
    [0002]
    2. Tire according to claim 1, characterized by the fact that said tread (300; 400) additionally comprises a tread depth of less than 8.5 mm.
    [0003]
    3. Tire according to claim 1, characterized by the fact that said tread (300; 400) additionally comprises a plurality of patterns (106) and an associated average pattern length, wherein said pattern varies between 15 and 35 mm.
    [0004]
    4. Tire according to claim 1, characterized by the fact that said tread (300; 400) is used with a tire of size 205 / 55R16.
    [0005]
    5. Tire according to claim 4, characterized by the fact that said tread (300; 400) has two circumferential grooves that have a width ranging from 8 to 10 mm.
    [0006]
    6. Tire according to claim 5, characterized by the fact that said tread (300; 400) has sipes (110; 210; 310) that are spaced about 10 mm apart from each other in the longitudinal direction of the tire .
    [0007]
    7. Tire according to claim 6, characterized by the fact that said tread (300; 400) has two circumferential grooves that have a width ranging from 3 to 5 mm.
    [0008]
    Tire according to claim 1, characterized by the fact that the tread (300; 400) has tread elements in the form of tread blocks (108; 208).
    [0009]
    9. Tire according to claim 2, characterized by the fact that the tread depth (300; 400) is 8 mm.
    [0010]
    10. Tire according to claim 3, characterized by the fact that the depth of the pattern is 29 mm.
    [0011]
    11. Tire according to claim 1, characterized by the fact that the longitudinal CSR is 0.87.
    [0012]
    12. Tire according to claim 1, characterized by the fact that the lateral groove density (LGD) is 38 mm-1.
    [0013]
    13. Tire according to claim 1, characterized by the fact that the lamella density (SD) is 20 mm-1.
    [0014]
    14. Tire according to claim 1, characterized by the fact that the intralamela distance between adjacent lamellae (410) in the shoulder region (408) of the tread measured in the longitudinal direction is greater than the intralamela distance between lamellae (410) adjacent to the central region (407) of the tread measured in the longitudinal direction.
    [0015]
    15. Tire according to claim 1, characterized by the fact that a plurality of lateral grooves (214; 312; 412) have chamfers (216; 316; 416) located along its lateral edges.
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    同族专利:
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    法律状态:
    2017-12-26| B25A| Requested transfer of rights approved|Owner name: COMPAGNE GENERALE DES ETABLISSEMENTS MICHELIN (FR) |
    2018-12-11| B06F| Objections, documents and/or translations needed after an examination request according art. 34 industrial property law|
    2019-10-29| B06U| Preliminary requirement: requests with searches performed by other patent offices: suspension of the patent application procedure|
    2020-06-16| B06A| Notification to applicant to reply to the report for non-patentability or inadequacy of the application according art. 36 industrial patent law|
    2020-11-17| B09A| Decision: intention to grant|
    2021-02-02| B16A| Patent or certificate of addition of invention granted|Free format text: PRAZO DE VALIDADE: 20 (VINTE) ANOS CONTADOS A PARTIR DE 05/09/2012, OBSERVADAS AS CONDICOES LEGAIS. |
    优先权:
    申请号 | 申请日 | 专利标题
    USPCT/US2011/053980|2011-09-29|
    USPCT/US2011/053980|2011-09-29|
    PCT/US2012/053773|WO2013048682A1|2011-09-29|2012-09-05|Tire with tread having improved snow and dry traction|
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