FI123778B - Structure of the tread in an air-filled vehicle tire - Google Patents

Description

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Structure of the wear layer in the vehicle's inflated tire - Struk-tur av slitbanan i et luftfylt fordonskiäck

The invention relates to a tread layer structure in an inflatable tire of a vehicle comprising two shoulder areas and a circumferential vault having at least a rubberized belt structure and a tire tread having a tread width between the shoulders and having: a rubber layer, and at least an outer cap rubber layer having a first cap thickness and a first cap width coming into contact with the road.

EP-1 308 319 discloses an inflatable belt tire of a vehicle, in particular a tal-15 tire having a tread layer consisting of a single base rubber layer closer to the tire body and an outer cap tread forming a single core, the cap rubber layer having at least two different rubber layers axially parallel. The zone of the cap rubber layer of the tire which, when mounted under the car, is located at the edges of the car, consists of a rubber grade having a glass transition temperature ~ e.g. -20 ° C to ± 0 ° C ~ higher than its rubber grade glass transition temperature ~ between -60 ° C and -40 ° C - the zone of the tire which, when fitted under the car, is located towards the inside of the car. This publication also mentions the possibility that these bands of cap rubber layer parallel to the axial direction may be three to five, which cap bands are typically of equal width and the middle of which may have either the highest or lowest glass transition temperatures. The aim is to achieve good grip in both winter and summer conditions, and to reduce inaccurate handling and poor wet grip that occur when winter tires are used in summer conditions.

In addition, it has been sought to make the winter tire also suitable for summer conditions by g designing the tread pattern to be substantially asymmetric, as described, for example, in GB-1 588 575, wherein one side portion of the tread contains a lot of grooves and the other only minimal grooves.

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US-5,109,902 discloses an inflatable ring having a toroidal o-shaped body structure with axially opposing ends pivoted upwards around the foot portions, a belt disposed radially outside the body structure and a "tread" surrounding the belt. The belt consists of at least two 40 overlapped, rubberized coordinate layers and the wear layer consists of a foamed base rubber arranged radially inside the tire, which foam base rubber contains a large number of closed pores, and a non-foamed cap rubber arranged radially outside the tire. Thus, in this tire, the base rubber is wholly of foamed rubber and this center of the foam base 5 may be located in the center plane of the tire or may be offset from the "equatorial plane" such that the foam base rubber is completely off center. Specifically, the specification defines, inter alia, that the expansion ratio of the foam base rubber is 10% to 50%, its 10% compression modulus is between 0.2 and 0.61 kgf / mm 2, the width of the foam base rubber is less than the belt width and cap -10 rubber is on both opposite sides of the foam base rubber. From the proposed structure, the foamed base rubber, wherever placed axially in the tire wear layer, improves rolling resistance and ride comfort, but significantly reduces handling properties and causes tire wear pattern problems. Such a tire is also likely to be very susceptible to tread release, and driving resistance is likely to be inferior.

US 4,580,608 discloses an inflatable vehicle inflatable tire comprising a frame, two sidewall areas, two shoulder areas, a crown region, and a tire axis, the wear layer member covering the arch region 20 to form a road contact portion. koordiker-ros. The wear layer consists of a base rubber layer closer to the axis line and a cap rubber layer profiled for road contact on the above base rubber layer. To receive the cap rubber layer, the base rubber layer forms a trough with trough shoulders associated with said shoulder areas. Here, the base rubber 25 forms the shoulder areas of the ring, since they specifically form the trough shoulders, although the trough shoulders should be formed by multiple members and further at these locations, i.e., the furthest portions of the shoulder areas. Clearly, this means that the base rubber grade ^ 30 is the same as the rubber sidewall quality and extends to the tire surface at its shoulder regions. One figure shows a structure in which sidewalls of different thicknesses, e.g., base rubber or some other unspecified rubber grade, are disposed outwardly from the trough shoulders. The main aim of the publication is to reduce rolling resistance and thus energy losses and temperature increase, but it does not in any way indicate how the latter possibly asymmetrical shoulder rubber arrangement could contribute to this or what other effects it is supposed to have.

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US 5,429,164 describes an air-inflated tire for a vehicle having a foam rubber layer and an outer foam rubber layer for road contact. The radial layer thickness of the outer layer changes gradually, being different at different widths.

EP 1234587 discloses a vehicle tire in which the tread is formed of a cap layer and a base layer of different rubber and different hardness. The tread is asymmetrical with respect to its center line, such that the volume of the base layer is greater than the volume of the cap layer at the outer edge of the tire when the tire is mounted on the vehicle.

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Fl 20041214 relates to air-inflated radial-ply tires for vehicles with a frame structure and a tread of various rubber grades around its periphery. The tread layer has a cap rubber layer coming into contact with the road and a base rubber layer between it and the frame structure. The cap rubber twin layer consists of at least oils narrow strips and a middle strip therebetween, the middle strip being the first rubber grade and the shoulder strips the second and possibly third rubber grade having properties different from those of the middle strip.

It is an object of the invention to provide an inflatable radial tire of a vehicle which has excellent handling properties on both dry and wet road surfaces. It is a further object of the invention to provide such an inflatable vehicle tire having a good wear resistance and excellent traction, at least on a dry and wet road surface, that is to say a summer tire. Alternatively, it may be a further object of the invention to provide such an inflatable vehicle tire with good wear resistance and excellent traction on snowy and / or icy and / or wet and possibly dry road surfaces, i.e., a winter tire.

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The problems described above can be solved and the objects defined above are achieved by a wear layer structure according to the invention, characterized by what is defined in the characterizing part of claim 1.

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It has now surprisingly been found that, first, by arranging two cap layers of rubber over the base rubber layer in the wear layer, and additionally arranging the thickness of the inner cap rubber layer over one axial axial width of the wear layer in a than the thickness of this inner cap rubber layer over the remainder of the wear layer width, the entire width of the tire wear layer can be adapted to suit the particular weather so that both grip and handling are good. Another surprising advantage has been found that by applying the principle of the invention it is possible to provide a tread which is ideally suited to both dry and wet road, i.e. a summer tire, but also a tread which is particularly suitable for icy and wet and dry road. The advantage is that achieving these features of the invention does not necessarily require radical asymmetry of the tread pattern, but the patterning can be designed from other desired starting points, which of course does not prevent the utilization of some asymmetry. In addition, providing a greater width section of the inner cap rubber layer on the side of the tire which, when mounted in the car, faces outward from the car and its centerline, further enhances the benefits.

The invention will now be described in detail with reference to the accompanying drawings.

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Fig. 1 shows a first embodiment of a radial tire according to the invention, for which the figure shows the area of the tire wear layer and the sides of the tire, in cross-section along the axis of rotation of the tire. The tire rolling direction is perpendicular to the image plane. In this embodiment, the ring 20 is a round shoulder. One of the larger thicknesses of the second cap rubber layer is on the outer shoulder side.

Fig. 2 shows another embodiment of the belt ring according to the invention in the same view as in Fig. 1. In this embodiment, the second cap rubber layer has one greater thickness on the outer shoulder but the outer shoulder is sharp and the inner shoulder is circular.

Fig. 3 shows a third embodiment of the belt ring according to the invention in the same view as Fig. 1. In this embodiment, the ring is a round shoulder.

^ 30 The greater thickness of the second cap rubber layer is on the inner shoulder side and the larger and smaller thickness of the other cap kum cap rubber layer are connected by a wedge-shaped ό portion.

Fig. 4 shows a fourth embodiment of a belt ring according to the invention in the same view as Fig. 1. In this embodiment, the ring is a round shoulder.

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o One cap rubber layer has a greater thickness on the outer shoulder side and another o cap rubber layer has a larger and smaller thickness combined by a two-step ™ portion.

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In the present case, the structure of the tread on the vehicle's inflatable tire 1 comprises two shoulder regions 8a, 8b and a circumferential arch portion 10 having at least a rubberized belt structure 6 and a tire wear layer 9 on top thereof. between shoulders tread width-5 ys W9. From the shoulder regions 8a, 8b, the structure extends as the sides of the tire 13. The vehicle tire is also known to have a carcass 19 extending from the first leg region not shown in the figures to the second leg region, not illustrated here, on the upper side said belt structure 6 with an arch portion is viewed in the direction of the radius R of the ring 10. The wear layer 9 has at least one base rubber layer 2 in the direction of the radius R of the ring, and at least a first cap rubber layer 3 having a first cap thickness C1 and a first cap width W1 coming into the web. In use, the outermost surface P1 of the wear layer 9 comes into contact with the road surface.

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According to the invention, the wear layer 9 further comprises, between the base rubber layer and the first cap rubber layer 3, a second cap rubber layer 4 having a second cap thickness C2 and a second cap width W2. Specifically, the second cap thickness C2 of this second cap rubber layer 4 has at least one larger thickness 20 C2s for a first sub-width W2s of its second cap width W2 and at least one smaller thickness C2p for a second sub-width W2p of its second cap width W2. More specifically, the greater thickness C2s begins at one shoulder region 8a or 8b and extends from there to the end of the first partial width W2s, while the smaller thickness C2p begins at the opposite shoulder region 8b or 8a and extends from there to the second partial width W2p. Further, the first partial width W2s corresponding to the greater thickness C2s, measured along the interface of the first and second cap rubber layers and its extension 5, is at least 25% and at most 75% of the tread width W9. The interface between the first and second cap rubber layers and its extension, thus having this common reference numeral "5", provides a continuous and monotonous arc ("curve") which typically remains relatively at the same position. between the outermost surface P1 of the tread layer 9 and the outermost surface P2 of the base rubber layer ainakin 2, at least for a major portion of the tread width W9. This is true at least when the base rubber layer 2 is substantially uniform in tread width. The interface with extensions 5 is thus partly a computational measurement and comparison point.

In particular, it is noted that the rubber of the first cap rubber layer 3 is that which 5 is in contact with the road surface, even if the tire is worn in use. If the rubber of the second cap rubber layer 4 comes into contact with the road during the use of the tire, it is advisable to replace the tire, even if this is of the cap rubber grade. At this point, the remaining groove depth of the grooves 15 in the wear layer has already been significantly reduced. Thus, for example, with respect to the grip of the tire, the interaction between the rubber and the road surface of the first cap rubber layer 3 can be considered primarily, bearing in mind that the inner parts of the tire, i.e. the second cap rubber layer 4 and base rubber layer 2 and the belt structure 6 and affect tire performance.

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Further, according to the invention, the first cap thickness C1 of the first cap rubber layer 3 has at least one greater thickness C1s of the first part width W1s of its first cap width W1 as described above and at least one smaller thickness C1p of the first cap width W1 the greater and lesser thicknesses of the cap rubber layer and the second cap rubber layer in total C1s + C2p and respectively the smaller and greater thicknesses in total C1p + C2s are equal, i.e. C = C1s + C2p = C1p + C2s. Hereby, the combined thicknesses C of the first cap rubber layer 3 and the second cap rubber layer 4 are substantially equal at each point of the tread width W9, i.e. the first cap rubber layer and the second cap rubber layer together form a uniform thick layer combination. Of course, for said transverse and / or circumferential groove (s) 15 of the wear layer and for any fine gaps in the pattern blocks 16, this said layer combination does not have this described thickness C. Likewise, when approaching shoulder areas 8a, 8b, thickness C may vary from overall. Said first partial width W2s corresponding to the greater thickness C2s, measured along the interface of the first and second cap rubber layers and its extension 5, is at least 25% and at most 75% of the tread width W9, or preferably at least 35% and at most 50% of the tread width W9.

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Between the greater thickness C2s and the lower thickness C2p, the second cap rubber layer 4 has a range of change of part width W2v - which part width W2v occurs in the same direction as the tread width W9 - with a change in thickness C2s - C2p of the second cap rubber layer and 30, the thickness change C2s C2p in the change region may be one step 21, whereby the change area partial width W2v is zero, or several steps 22a, 22b or wedge 23, whereby the partial width W2v . With said transition region between said greater thickness C2s and the lower thickness C2p consisting of a plurality of ports 35a 22a, 22b or wedges 23, the second cap rubber layer 4 comprises one or more intermediate thicknesses C2v with a third partial width W2v of its second cap width W2. 3 and 4 are shown.

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According to the invention, the rubber quality 40a forming the first cap rubber layer 3 has a first cap hysteresis and a second quality rubber hingeresis 7 having a second cap rubber layer 4, both of which have a lower temperature cap-hysteresis xlci, xlc2 higher than the base rubber layer 2. or low-temperature base-hysteresis xlb of the rubber grades constituting the base rubber layers, i.e. xlci> tlb and tlc2> xlb · Such rubber grades of rubber cap layers 3 and 4, i.e. rubber compound 5, are characterized by the filler being both silica and carbon the polymer or elastomeric component is, for example, butadiene rubber BR or styrene-butadiene rubber or optionally natural rubber (NR = "natural rubber") or a mixture thereof. For the rubber grades of the base rubber layers 2 = rubber compounds, for example, consist of natural rubber butadiene. It will be appreciated that one skilled in the art 10 may also select other types of components as elastomers and / or fillers, as well as other additives appropriately selected to satisfy the hysteresis condition described above, and other hysteresis to the level required in the vehicle tire. More specifically, in this context, low-temperature hysteresis refers to hysteresis loss expressed as tan δ, measured at a predetermined low temperature between -10 ° and + 30 °, typically between -10 ° and + 10 ° and of course using the same frequency ("frequency") at 10 Hz and the same static strain rate of 2% and the same dynamic strain rate of 0.02%. Hystere internal losses are measurable in laboratories in a manner known per se, for example, according to ISO-4664. Possible alloy types are thus not further described. Further, the first cap-hysteresis xlci of the rubber grade forming the first cap rubber layer 3 is larger than the second cap-hysteresis xlc2 of the rubber grade forming the second cap rubber layer 4 The above-described hysteresis properties apply to both summer and winter tires. Thus, the rubber grade forming the first cap rubber layer 3, the rubber grade forming the second cap rubber layer 4 and the rubber grades forming the base rubber layer 2 or base rubber layers have the low temperature hysteresis properties described above, and in particular the hysteresis loss ratio tan δ.

§ 30 g In any case, the rubber grade constituting the first cap rubber layer 3 has been chosen to have good wear resistance over other high grade low temperature hysteresis rubber grades or other high cap hysteresis rubber grades with good ice holding - Thus, here, bid 35 refers to the first cap hysteresis. Actual wear resistance needs to be measured using the right tires, since the measurement of rubber wear under laboratory conditions can give misleading and even opposite results compared to actual tires - that is, even if a rubber grade has good wear resistance, 8 actually shows it bad, and vice versa. Comparative use tests must therefore be carried out.

It is a further feature of the invention that one of the tire shoulder regions 8a, 8b 5 may be a predetermined outer shoulder 8a and the other of the tire shoulder regions 8a may be a predetermined inner shoulder 8b. Thus, in a preferred embodiment, the aforementioned larger width C2s of the second cap rubber layer W2s is located in the wear layer 9 adjacent to said outer shoulder 8a, and the aforementioned lower thickness C2p partial width W2p is located in the wearing layer 109. In a second embodiment, however, the greater width C2s of the second cap rubber layer has a greater width C2s adjacent to said inner shoulder 8b in said wear layer 9 and said lower thickness C2p having a width W2p located adjacent said outer shoulder 8a.

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A further feature of the invention may be that said outer shoulder 8a has a first convex curvature K1 and the inner shoulder 8b has a second convex curvature K2, whereby the absolute value of the first convex curvature \ Κλ \ is greater than the absolute value of the second convex curvature | K2 | that is, I K \ | > IK2 \. Curvature, after all, denotes the rate of change of the curve or the tangent angle α of the curve and the curved surface, respectively, when the curve length s is taken as the basis. Mathematically, the curvature K of a given point is thus: „,. Δα da K = hm - = -

As ds 25 As -> 0

That is, the derivative of the tangent to the arc length. In most cases, for the sake of simplicity, the mean curvature of the curve K = Aa Ia s ("mean curvature") for each of the arcs can be applied, and so here too.

Finally, it is noted that the narrow strips through which the soot-rich base rubber extends through the cap rubber layers to the outer surface of the tire tread, as shown in the figures at the center of the tread width W9, are not considered, because their width is so small that the strip Q_ 35 is irrelevant to the tire's driving behavior.

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Claims (11)

A wear layer structure in an inflatable tire (1) of a vehicle comprising two shoulder areas (8a, 8b) and a circumferential arch portion 5 (10) therebetween having at least a rubberized belt structure (6) and a tire wear layer (9) thereon having a tread width (W9) between the shoulders and having: - at least one base rubber layer (2) having a base hysteresis of the rubber type (s) forming its shape, and - at least the first cap rubber layer (3) coming into contact with the road; 10 having a first cap-thickness (C1) and a first cap-width (W1) having a first cap-hysteresis of the rubber grade forming it, characterized in that the wear layer (9) further comprises a base rubber layer and a first cap rubber layer (3). in between, a second cap rubber layer (4) having a second cap thickness (C2) and a second cap width (W2) having a second cap hysteresis forming the rubber blade 15; that - said second cap thickness (C2) of the second cap rubber layer (4) has at least one greater thickness (C2s) with the first sub-width (W2s) of its second cap width (W2) and at least one smaller thickness (C2p) of the second cap -the second width (W2p) of its width (W2); and that said first partial width (W2s) corresponding to a greater thickness (C2s), measured along the interface of the first and second cap rubber layers and its extension (5), is at least 25% and at most 75% of the tread width (W9). A wear layer structure according to claim 1, characterized in that one of the tire shoulder regions is predetermined to the outer shoulder (8a) and the other of the tire shoulder regions is the predetermined inner shoulder (8b); and that said part width (W2s) of the second cap rubber layer is located in the wear layer (9) adjacent to said outer shoulder (8a), and said part width (W2p) of the lower thickness (C2p) is located in the wear layer (9) next to the inner shoulder (8b). CM CO A wear layer structure according to claim 1, characterized in that one of the tire shoulder regions is predetermined as an outer shoulder (8a) and the other tire shoulder region is a predetermined inner shoulder (8b); and that said partial width (W2s) of the second cap rubber layer (W2s) lies within the wear layer (9) adjacent to said inner shoulder (8b), and said partial width (W2p) of the smaller thickness (C2p) S ) is located on the wear layer (9) adjacent to said outer shoulder (8a). A wear layer structure according to claim 2, characterized in that the outer shoulder (8a) has a first convex curvature (/ O1) and the inner shoulder (8b) has a second convex curvature (K2); and that the absolute value (| KA \) of the first convex curvature is greater than the absolute value of the second convex curvature <k2 |). A wear layer structure according to any one of the preceding claims, characterized in that the rubber grade forming the outer first cap rubber layer (3) has a better wet grip in the finished tire than the rubber grade forming the second cap rubber layer (4). A wear layer structure according to any one of the preceding claims, characterized in that said hysteresis is a hysteresis loss measured at a low temperature between -10 ° and + 30 °; that said cap hysteresis are higher than base hysteresis; and that said first cap-hysteresis is higher than said second cap-hysteresis. 15 A wear layer structure according to any one of the preceding claims, characterized in that said first cap thickness (C1) of the first cap rubber layer (3) has at least one greater thickness (C1s) of the first partial width (W1s) of its first cap width (W1) and one smaller thickness (C1p) with a second partial width (W1p) of its first cap width (W1) such that the greater and the smaller thickness of the first cap rubber layer and the second cap rubber layer (C1s + C2p) and the smaller and larger thicknesses respectively (C1 p + C2s) are equal. A wear layer structure according to any one of the preceding claims, characterized in that said first partial width (W2s) corresponding to the greater thickness (C2s), measured along the interface of the first and second cap rubber layers and its extension (5) is at least 35% and at most 50%. tread width-cvj (W9). § 30 A wear layer structure according to any one of the preceding claims, characterized in that said range of change between the higher thickness ^ (C2s) and the lower thickness (C2p) of the second cap rubber layer (4) is one step (21) or £ several steps (22a, 22b). ) or wedge (23). c \ i 35 LO A wear layer structure according to claim 9, characterized in that, when said region of change between the greater thickness (C2s) and the lower thickness (C2p) is several steps (22a, 22b) or the wedge (23) comprises a second cap rubber layer. (4) one or more intermediate thicknesses (C2v) at the third or third widths (W2v) of their second cap widths (W2). Wear layer structure according to claim 6, characterized in that the rubber grade constituting the first cap rubber layer (3) is selected to have good wear resistance compared to other high cap hysteresis 5 rubber grades or other high cap hysteresis rubber rubber grades. C \ J δ c \ j i oo o o X cc CL C \ l m o δ o o CM