KR20030085081A - Tread pattern for car tire - Google Patents

Abstract

The present invention relates to an automobile tire, wherein the automobile tire (1) of the present invention comprises at least one circumferential circumference positioned between the first and second circumferential grooves (3,4; 5,4; 6,5). Blocks 13; 14; 15; 213; 215; columns 9; 10; 11; 209; 211; each block 13; 14; 15; 213; 215 each having a first circumferential groove 3; A portion 103; 105; 106 of 5; 6 and a common, spaced apart and separated from the second circumferential groove 4; 5 by a continuous circumferential tread lip 20,24; 30 The boundary is determined by the first and second transverse grooves 16,18; 28,26; 38,36; 216,218; 236,238 that converge to vertices 19; 29; 39; 219; 239 and block 13 The second transverse groove (18; 26; 36; 218; 236), which determines the boundary of; 14; 15; 213, is the next block by the solid tread portion (21; 25; 31; 221; 231). A first lateral groove (16; 28; 38; 216; 238) that determines the boundary of (13; 14; 15; 213; 215).

Description

Tread pattern for car tires {TREAD PATTERN FOR CAR TIRE}

The present invention relates to an automobile, in particular a high performance automobile tire.

BACKGROUND OF THE INVENTION A vehicle tire is known which has a tread with blocks delimited by a circumferential groove extending in the longitudinal direction and a transverse groove extending in the substantially axial direction. The blocks formed by the intersections of the grooves are formed in a variety of suitably designed shapes, and also formed of adjacent circumferential rows, each circumferential row located between two successive circumferential grooves.

The circumferential grooves will affect the direction and running stability characteristics of the tire against side (sliding) thrust acting parallel to the axis of rotation of the tire.

Transverse grooves, on the other hand, will affect the traction characteristics of the tire, i.e. the ability to efficiently transmit tangential thrust parallel to the driving direction during acceleration and deceleration of the vehicle.

The circumferential groove and the lateral groove will also affect the drainage in the area (ground surface area) that contacts the road surface when running on a wet road surface.

In any case, the presence of circumferential grooves and transverse grooves affects the rolling noise of the tire. In fact, one of the main causes of noise is that the edges of the blocks sequentially hit the road.

Another source of noise is that blocks are dragged on the road surface as they enter and exit the contact area with the road surface. Basically this attraction is due to the deformation of the tread when the tire comes into contact with the road surface and becomes flat and when the tire returns to its expanded state as the tire exits the contact area with the road surface.

Periodic volume change of the grooves that determine the boundaries of the blocks due to the deformation of the tread when it comes into contact with the road contact area and when exiting the contact area, and thus the periodic compression and expansion of air trapped inside the groove Action occurs. This compression of air increases the rolling noise of the tire.

Various methods are known to help limit the rolling noise of a tire. One uses two or more different pitch values that are continuously distributed along the circumference of the circumference, called a "pitch arrangement," thereby varying the longitudinal dimensions of the blocks, e.g. the circumference of the tread. The lack of uniformity throughout the length. The purpose of this method is to disperse the acoustic energy due to the collision and drag of the blocks over a wide frequency range, thereby preventing the acoustic energy from concentrating on a particular frequency and producing a disturbing noise.

ISO / TC 31 / SC No. When measured according to the standard 623, tire noise is considered unacceptable if the following limits are exceeded.

Tire width ≤145 72 ㏈ (A)

145 <Tire Width ≤165 73 ㏈ (A)

165 <Tire width ≤185 74 ㏈ (A)

185 <Tire Width ≤215 75 ㏈ (A)

215 <Tire Width 76 ㏈ (A)

Tire noise is a difficult problem to solve because some methods that help reduce tire noise adversely affect the direction, traction and drainage characteristics.

For example, to improve drainage characteristics, the transverse grooves must be steep. That is, the slope of the transverse groove with respect to the circumferential groove should be small. On the other hand, in order to improve the uniformity of running and response time on a dry road surface, the inclination of the transverse channel with respect to the circumferential groove must be large. That is, the transverse grooves should be approximately perpendicular to the longitudinal grooves. However, the highly tilted lateral grooves further exacerbate the rolling noise of the tire.

Moreover, sounds at frequencies below 1500 Hz, more specifically below 1000 Hz, are much better heard internally than outside the vehicle, while sounds above 1500 Hz are much better heard outside the vehicle.

Thus, it is not possible to achieve low noise levels both inside and outside the car, and in each case it is difficult to obtain the best compromise possible.

EP-812,709 discloses a tire having a tread comprising two areas, at least one of which is provided with a plurality of inclined main grooves, each of which has a steep slope and Includes a gentle slope In the lateral band region of the two regions, there are two adjacent inclined main grooves and an inclined auxiliary groove and an inclined auxiliary groove located between two adjacent inclined main grooves.

In the first embodiment, the inclined main groove extends from the circumferential circumference groove to near the equator plane of the tire, and in the second embodiment, the end of the inclined main groove is blocked.

In the third embodiment, the steeply inclined portions of two adjacent inclined main grooves are joined by a thin transverse groove.

European patent EP-867,310 discloses a tire comprising blocks formed in the tread by a plurality of circumferential grooves and a plurality of directionally inclined grooves. At least some of the directionally inclined grooves extend from the circumferential groove to near the equator plane of the tire and extend toward one end of the tread area in contact with the ground. Each of the blocks has an angled portion formed by circumferential grooves and directionally inclined grooves, which form an acute angle between 10 ° -60 °. The surface of the angled portion of the block is sharpened in the longitudinal direction so that it gradually changes toward the wide portion over a distance between 10-30 mm from the pointed end.

Each of the inclined grooves in the tread of both documents described above determines the boundaries of one block and adjacent blocks located side by side along the circumference. That is, each directionally inclined groove divides two adjacent successive blocks and is common to both blocks.

As a result, both treads described above have circumferential rows of sickle-shaped adjacent blocks that are only split at a pitch of the same size as the sum of the circumferential circumferential lengths of the inclined grooves adjacent to one block.

However, the inventors of the present invention have noticed that if there are a large number of inclined grooves leading to the longitudinal grooves and their arrangements are close to each other, it adversely affects the rolling noise of the tire.

One object of the present invention is to provide a tire that is low in noise both on the inside and outside of a vehicle, and shows excellent performance on wet roads and dry roads.

The present invention provides an automotive tire having an equator plane comprising a tread and two shoulders having at least one circumferential row of blocks located between the first and second circumferential grooves, wherein each of the blocks is the first circumference. A boundary is determined by a portion of a circumferential groove and first and second transverse grooves extending from the first circumferential groove and converging to a common vertex spaced apart from the second circumferential groove by a distance. Is separated from the second circumferential groove by a continuous circumferential tread rib, wherein the second transverse groove that determines the boundary of the block extends from the first circumferential groove to the circumferential rib. The next block by a solid tread portion which forms an integral part with the circumferential rib and places the block and the next block away from each other by a distance. Of claim 1 for determining a boundary relates to a vehicle tire is separated from the lateral groove.

At least one of the first and second lateral grooves preferably increases in width in a direction from the common vertex toward the first circumferential groove.

In one embodiment, at least one of the first and second lateral grooves is sickle shaped.

At least one of the first and second lateral grooves preferably has a centerline formed by an arc having a predetermined radius of curvature.

Preferably, the center line has a first portion having a direction substantially parallel to the equator plane, a second portion having a predetermined slope with respect to the first circumferential groove, and a coupling portion coupling the first and second portions. Do.

In another embodiment, at least one of the first and second transverse grooves comprises a first portion having a direction approximately parallel to the equator plane, a second portion having a predetermined slope relative to the first circumferential groove, and And a joining portion joining the first and second portions.

Each block in at least one of the rows of blocks is preferably shark fin shaped.

The common vertices of the first and second transverse grooves of at least one of the rows of blocks are preferably arranged in the same direction in the longitudinal direction.

The tread is characterized by having a central circumferential block row and first and second side circumferential block rows.

In one embodiment, the common vertices of the first and second transverse grooves of the first side block row are opposite to the directions of the common vertices of the first and second transverse grooves of the center block row and the second side block row. Are arranged in the direction.

In another embodiment, the common vertices of the first and second lateral grooves of the three block rows are arranged in the same direction.

The tread is characterized by having a row of first and second side circumferential blocks and two central circumferential ribs separated by intermediate circumferential grooves.

The common vertices of the first side block rows are preferably arranged in directions opposite to the directions of the common vertices of the second side block rows.

Preferably the first and second lateral grooves of at least one of the first and second side circumferential block rows extend beyond each first circumferential groove and also extend into an axially inner region of one of the shoulders. Do.

At least one of the shoulders is characterized by having additional pairs of transverse grooves converging toward a common vertex in the axial outer region.

The additional converging lateral grooves are preferably separated from the first circumferential groove by the solid portion of the elastomeric material.

The further converging transverse grooves are characterized by extending from the first circumferential groove.

The axially inner region of one shoulder has a smaller void / solid ratio than the axially inner region of the other shoulder and is preferably located outside of the vehicle when the tire is mounted to the vehicle.

The tire according to the invention ensures great traction on wet roads, very low noise level values on both the inside and outside of the vehicle, and a high level of ride comfort and good maneuverability on dry roads.

In particular, in wet road conditions with poor traction, the tread according to the invention ensures proper drainage even at high speeds without affecting the grounding performance in both the longitudinal and transverse (lateral) directions. This behavior is evidenced by the aquaplaning test at the bend, which measures the lateral acceleration and the maximum speed that can be reached before the tire loses grip. When traveling along the curve of the road in heavily wet road conditions, the tire according to the present invention maintains an ideal ground state for a longer time at a higher speed compared to the tire to be compared.

In addition, upon lateral acceleration, there is a marked improvement in the maximum acceleration value and the maximum velocity value on the wet road surface.

Thus, the tire according to the invention and the vehicle on which the tire is mounted show optimum behavior in wet road conditions and ensure better steering safety.

The greater adhesion between the tire and the wet road surface ensures a shorter braking distance, thereby improving the performance of the vehicle on which the tire according to the invention is mounted.

The term "groove" in this specification and the appended claims is to be interpreted to mean a recess having a width of at least 1.5 mm.

The features and advantages of the present invention will now be described with reference to the embodiments shown in the accompanying drawings as examples which do not limit the scope of the invention.

1 is a front view of a tire with a tread according to the present invention.

FIG. 2 is a perspective view of the tire of FIG. 1. FIG.

3 is an enlarged plan view of the tire tread of FIG. 1.

4 is a plan view of a modification of the tread of FIG. 3.

5 is a plan view of another variant of the tread of FIG. 3.

6 is a plan view of yet another variant of the tread of FIG. 3.

7 is a plan view of the tread of the tire to be compared.

8 to 14 are graphs showing the results of tests performed with the tire of FIG. 1 and the tire of comparison 7.

1 and 2 show a tire 1 with a tread 2 bounded axially by two shoulders 8, 12. The tread 2 is provided with circumferential grooves 3, 4, 5, 6 (FIG. 3) extending in the longitudinal direction and parallel to the equator plane 7 of the tire. The tread 2 comprises three circumferential block rows 9, 10, 11, a central row 10 and two side rows 9, 11. The shoulder 8 is separated from the block row 9 by the circumferential groove 3. The block row 9 is located between the circumferential grooves 3, 4. The block row 10 is located between the circumferential grooves 4, 5. The block row 11 is located between the circumferential grooves 5, 6. The shoulder 12 is separated from the block row 11 by the groove 6.

Each of the shoulders 8, 12 includes an axially inner region 108, 112 and an axially outer region 208, 212, which are closer to the equator plane and affect the performance of the tire, The outer area is close to one sidewall and does not affect tire performance.

The circumferential grooves 3, 4, 5, 6 range from about 6 mm to about 15 mm in width and from about 5 mm to about 11 mm in depth. In the case of the tread 2 of FIGS. 1 to 3, the circumferential groove 3 is narrow at 9 mm and has a depth of 8.2 mm, and the circumferential grooves 4 and 5 are 13 mm wide and 8.8 in depth. The circumferential circumferential groove 6 is 11 mm wide and 11 mm in depth.

The block column 9 includes a series of blocks 13, the block column 10 includes a series of blocks 14, and the block column 11 includes a series of blocks 15. Blocks 13, 14 and 15 are shaped like shark fins or sickles.

Each block 13 is bounded by a circumferential groove portion 103 (base of the block) and transverse grooves 16, 18 coupled to each other. The lateral grooves 16, 18 coupled to each other extend from the ends of the circumferential groove portion 103 and converge at a common vertex 19. That is, they meet at a common point. The common vertices 19 of the grooves 16, 18 coupled to each other are arranged at a distance from the nearest circumferential groove 4 by a continuous circumferential lip 20 of elastomeric material. Each transverse groove 18 extends from the circumferential groove 3 to the circumferential lip 20 and is immediately followed by each lateral groove 16 by a continuous tread portion 21 which is integral with the circumferential lip. Separated from. The continuous portion 21 of the tread thus separates the two blocks 13 that follow immediately. The distance between the corresponding points of two immediately subsequent blocks 13 measured along the base of the blocks in each block row forms the pitch of that block row.

Common vertices 19 of all mutually coupled transverse grooves 16, 18 are arranged in the same direction in the longitudinal direction. That is, the blocks 13 of the block row 9 have a cup shape arranged in the same direction in the longitudinal direction.

The transverse grooves 16, 18 increase in width from the common vertex 19 toward the circumferential groove 3. The groove 16 increases from a minimum width of 1 mm, a maximum width of 6.1 mm, and a depth of 1 mm (at the vertex 19) to 8.7 mm. The groove 18 increases from a minimum width of 1 mm, a maximum width of 3.2 mm, and a depth of 1 mm (at the vertex 19) to 8.7 mm.

The grooves 16 and 18 are curved and have respective center lines 66 and 68 formed by arcs of a predetermined radius of curvature. The center line 66 includes a portion 166 having a direction substantially parallel to the equator plane 7, a portion 266 having a predetermined inclination with respect to the circumferential groove 3, and an engaging portion that joins the portions 166 and 266. Has (366). The radius of curvature of the center line of the grooves 18 is characterized by being 1.5 times the radius of curvature of the center line of the grooves 16. In the specific case of the tread 2 (FIG. 3), the radius of curvature of the centerline 66 of the groove 16 is 70 mm and the radius of curvature of the centerline 68 of the groove 18 is 105 mm.

Each block 14 is bounded by a circumferential groove portion 105 and respective lateral grooves 26 and 28 joined together in the same shape as the grooves 16 and 18. The groove 26 increases from a minimum width of 1 mm, a maximum width of 7.6 mm, and a depth of 1 mm (at vertex 29) to 8.7 mm. The groove 28 increases from a minimum width of 1 mm, a maximum width of 4 mm, and a depth of 1 mm (at the vertex 29) to 8.7 mm. The lateral grooves 26, 28 coupled to each other are arranged at a distance from the nearest circumferential groove 4 by a continuous circumferential lip 24 of elastomeric material. Each transverse groove 26 extends from the circumferential groove 5 to the circumferential lip 24, each next to the lateral groove 28 by a continuous tread portion 25 which forms an integral part with the circumferential lip. Separated from.

The common vertices 29 of all mutually coupled transverse grooves 26, 28 are arranged in the same direction in the longitudinal direction and are different from the direction of the common vertices 19 of the transverse grooves 16, 18 joined together. It is arranged in the opposite direction. That is, the blocks 14 have a cup shape disposed in a direction opposite to the cup-shaped direction of the blocks 13.

Each block 15 is bounded by a circumferential groove portion 106 and respective mutually coupled transverse grooves 36, 38 having the same shape and same size as the grooves 26, 28. The lateral grooves 36, 38 coupled to each other converge at a common vertex 39 which is spaced apart from the nearest circumferential groove 5 by a continuous circumferential lip 30 of elastomeric material. Each transverse groove 36 extends from the circumferential groove 6 to the circumferential lip 30 and is next to each next lateral groove 38 by a continuous tread portion 31 which is integral with the circumferential lip. ).

Common vertices 39 of all mutually coupled transverse grooves 36, 38 are arranged in the same direction in the longitudinal direction. The direction is the same as the direction of the common vertices 29 of the transverse grooves 26 and 28 coupled to each other, and the direction of the common vertices 19 of the transverse grooves 16 and 18 coupled to each other. to be.

The pattern of block rows 10, 11 is obtained from the pattern of block rows 9 by rotating the block row 9 180 degrees about the tire equator plane.

The lateral grooves 16, 18 of the block row 9 have extensions 41 and 42, respectively, which extend beyond the circumferential groove 3 into the axial inner shoulder region 108. The axial outer shoulder region 208 has a pair of transverse grooves 43, 44 that converge at the common vertex 45. The lateral grooves 43, 44 are located between the extensions 41, 42 and are spaced apart from the circumferential groove 3 by a continuous portion 46 of elastomeric material.

The lateral grooves 36, 38 of the block row 11 have extensions 51, 52, respectively, which extend beyond the circumferential groove 6 into the axial inner shoulder region 112. The axial outer shoulder region 212 has a pair of transverse grooves 53, 54 extending from the circumferential circumferential groove 6 and converging at a common vertex 55. Transverse grooves 53, 54 are located between the extensions 51, 52.

The common vertices 45 of the pairs of transverse grooves 43, 44 are arranged in the same direction in the longitudinal direction. The direction is the same as that of the common vertices 19. The common vertices 55 of the pairs of transverse grooves 53, 54 have the same direction in the longitudinal direction. The direction is the same as the direction of the common vertices 29 and 39 and opposite to the direction of the common vertices 45.

In the tread 2, the shoulder 8 has a smaller void / solid ratio than the shoulder 12. The shoulder 8 is located outside of the vehicle when the tire 1 is mounted on the vehicle, while the shoulder 12 is located inside.

The vacancy ratio of the tread 2 (FIG. 3) is 0.23 in the shoulder 8, 0.23 in the circumferential block row 9, 0.28 in the circumferential block row 10 and in the circumferential block row 11. 0.28, and 0.28 at shoulder 12.

The tread 2 has a pattern of asymmetrical form. That is, the tread 2 operates more efficiently when the tire is mounted on the vehicle in a predetermined direction rather than in the opposite direction. In other words, the tire has a preferred inside (vehicle side) and an outside. In the tread 2, this is achieved by applying different vacancy ratios on the inside and outside, ie by making the vacancy ratio smaller on the outside and larger on the inside. Low vacancy on the outside helps drive the car on dry roads. This is especially true if the car is a high-performance car that uses a larger camber angle to make the ground plane of the tire (tread) asymmetric.

FIG. 4 is a variant of the tread shown in FIG. 3 and the same parts represent the treads 62 indicated with the same reference numerals. The tread 62 is in the form of asymmetrical direction. That is, it is arrange | positioned in the direction which shows the traveling direction (arrow A) in a longitudinal direction. In the tread 62, the common vertices 19, 29, 39 of the transverse grooves 16, 18 and 26, 28 coupled to each other are arranged in the same direction in the longitudinal direction, respectively. In addition, the common vertices 45 and 55 are disposed in the same direction as the common vertices 19, 29 and 39.

In the tread 62, the shoulder 8 is located outside when the tire 1 is mounted to the motor vehicle.

FIG. 5 is a variant of the tread shown in FIG. 3 and the same parts represent the treads 72 indicated by the same reference numerals. The pattern of treads 72 is a mirror image of the treads 62, and is also in asymmetrical orientation.

FIG. 6 is a variant of the tread shown in FIG. 3 and the same parts represent the treads 82 indicated by the same reference numerals. The tread 82 is asymmetrical and has a column of circumferential blocks positioned between the shoulders 8,412, circumferential grooves 3,4, circumferential block rows 209, and circumferential grooves 5,6. 211, and two central circumferential ribs 230, 231 separated by an intermediate circumferential groove 232.

The intermediate circumferential groove 232 has a width in the range of 1.5 to 3 mm and a depth in the range of 1 to 4 mm. For example, the width is 1.5 mm and the depth is 2 mm.

Block row 209 includes a series of blocks 213, each block delimited by a circumferential groove portion 103 and two mutually coupled transverse grooves 216, 218. The lateral grooves 216, 218 which are joined to each other extend from the ends of the circumferential groove portion 103 and are spaced apart from the nearest circumferential groove 4 by a continuous circumferential lip 20 of elastomeric material. Converge to a common vertex 219. Each lateral groove 218 extends from the circumferential groove 3 to the circumferential lip 20 and is immediately followed by each lateral groove 216 by a continuous tread portion 221 that is integral with the circumferential lip. Separated from.

Block row 211 includes a series of blocks 215, each block bounded by a circumferential groove portion 106 and two mutually coupled transverse grooves 236 and 238. The lateral grooves 236 and 238 which are joined to each other extend from the ends of the circumferential groove portion 106 and are spaced apart from the nearest circumferential groove 5 by a continuous circumferential lip 30 of elastomeric material. Converge to a common vertex 239.

Each transverse groove 238 extends from the circumferential groove 6 to the circumferential lip 30 and is immediately followed by each lateral groove 236 by a continuous tread portion 231 forming an integral with the circumferential lip. Separated from.

The lateral grooves 216, 218 and 236, 238 coupled to each other include portions approximately parallel to the circumferential grooves and portions inclined with respect to the circumferential grooves. The grooves 216, 218, 236, 238 increase in width from the vertex 219 or 239 toward the circumferential groove 3 or 6.

Shoulder 412 has extensions 241 and 242 of lateral grooves 236 and 238 in axially inner region 112 and defines a pair of lateral grooves 243 and 244 converging to common vertex 245 in axially outer region. Have The lateral grooves 243 and 244 are located between the extensions 241 and 242 and are spaced apart from the circumferential groove 6 by a continuous portion 246 of elastomeric material.

The pattern of the shoulder 412 is obtained from the pattern of the shoulder 8 by rotating the pattern of the shoulder 8 180 degrees with respect to the tire equator plane.

FIG. 6 shows, by the elliptical line F1, a portion of the tread pattern that generates disturbances having a frequency proportional to the total number of transverse grooves that are subjected to collisions in the ground plane region. In the region bounded by elliptical line F2, the disturbance generated by the pattern is equal to half of the total number of transverse grooves described above, since the transverse grooves meet in pairs at the same vertex. Another advantage associated with the low noise level is that the pairs of grooves are blocked at a common vertex that converges, ie the pairs of grooves meet in the hollow of the tread and not in an open space, e.g. an additional groove. .

The structure of the tire 1 itself is of a conventional type, with a carcass, a tread band located at the crown of the carcass, an axially opposing pair that forms a distal end in the bead that is reinforced with the bead core and bonded with the bead filler. It includes sidewall of. The tire preferably also comprises a belt structure located between the carcass and the tread band. The carcass is reinforced with one or more carcass plies firmly secured to the bead core, while the belt structure comprises two belt strips disposed radially on top of each other. The belt strip is formed by a portion of the rubberized fabric which integrally comprises metal cords in each strip which are parallel to each other and intersect with metal cords of adjacent strips, preferably inclined symmetrically with respect to the equator plane. The belt structure preferably also comprises a third belt strip with cords arranged circumferentially at the outermost position in the radial direction, ie at an angle of zero degrees to the equator plane. Cords of zero degree belts are preferably made of fabric, even more preferably of heat shrinkable material. The tire 1 has a ratio H / C of the height of the right cross section and the maximum width, and the value is in the range of 0.65 to 0.20.

The tire 1 is preferably of a type having a very low cross section with an H / C ratio between 0.45 and 0.25.

A prototype of the tire according to the present invention having the tread 2 of FIGS. 1 to 3 was manufactured and subjected to a comparative test with the tire P shown in FIG. 7.

The comparative tire (P) was chosen because of its superior characteristics and type approval for high speed super high performance sports cars.

The tire according to the invention has a dimension of 225/40 R18, a wheel rim of 7.5 × 18 and an inflation pressure of 2.2 bar. The tires to be compared have the same dimensions.

The BMW 328i model car was initially equipped with four tires according to the invention, followed by four tires for comparison.

Mening phenomenon tests were performed on straight roads and bends, and braking tests on dry and wet roads, maneuverability tests on dry and wet roads, noise tests on and outside the vehicle, and ride comfort tests were also performed.

The water film development test on the straight road part was carried out in a straight part of a predetermined length (100 m) of a smooth asphalt pavement, and was provided with a layer of water having a predetermined predetermined height (7 mm) automatically restored to its original shape after each test vehicle passed. The vehicle entered at a constant speed (approximately 70 km / h) in full ground and accelerated until it completely lost its grip.

The hydromembrane test at the bend has a predetermined length, and a bend with a constant radius (100 m) of a smooth, dry asphalt road including an area of a predetermined length (20 m) submerged in a layer of water of a predetermined thickness (6 mm) at the end. Was performed in. The test was carried out at a constant rate for several different speed values.

During the test, the maximum centrifugal acceleration and the maximum speed of the car corresponding to the complete meningoidal state were recorded.

Braking tests were performed on straight asphalt roads for both dry and wet conditions, and recorded stopping distances from predetermined initial speeds, typically 100 km / h in dry and 80 km / h in wet.

Maneuverability tests in both dry and wet conditions were performed at specific locations, especially in circuit-controlled circuits. Some characteristic maneuvers, such as lane change, overtaking, slalom between skittles, entry and exit of bends, are simulated not only at constant speed but also at acceleration and deceleration, and the test driver for the behavior of the tires during the maneuver. The tire performance was evaluated by assigning numerical evaluation values.

The evaluation grade represents the subjective opinion expressed by the test operator in the test performed in turn on the comparable equipment.

Noise tests were performed both indoors and outdoors.

The indoor test was designed to rotate at different speeds, using an externally soundproofed chamber (semi-echo chamber), with the vehicle first equipped with the tire according to the invention and then with the tire to be compared. This was done by keeping the tire in contact with the rotating drum. Microphones were installed inside and outside the car to measure internal and external noise, respectively.

The outdoor test was carried out in a straight road section with a microphone. The vehicle entered the straight road section at a predetermined speed, and then the engine was turned off and noise outside the vehicle was measured in a neutral gear state.

Ride comfort was assessed by comparing the overall feeling felt by the test driver with the ability of the tire to absorb the bumps on the road surface.

Noise and ride testing were conducted under the conditions specified in the RE01 standard.

The results of the tests are shown in Table 1 and the values given are expressed as percentage of the value of the comparison tire fixed at 100.

Tires for comparison Invention tire Mening phenomenon on straight road 100 105 Flexure mening phenomenon 100 110 Dry road braking 100 103 Wet road braking 100 107 Dry road maneuverability 100 100 Wet road maneuverability 100 105 Internal noise 100 100 External noise * 100 110 Ride 100 100

* Recorded value during outdoor test

Values above 100 in Table 1 indicate an improvement over the tires being compared.

From the test results, it can be seen that the tire according to the present invention exhibited significantly better behavior than the tire of the comparison in wet road braking and external noise tests.

8 and 9 are graphs showing the noise levels of the exterior (FIG. 8) and the interior (FIG. 9) of the vehicle for the speed in the range of 150 to 20 km / h in ㏈ (A). Graphs A and A1 are for the tires to be compared and graphs B and B1 are for the tire of the present invention. The tire according to the present invention exhibits an external noise level of an average 1.5 ㏈ (A) lower than that of the comparison tire, while the internal noise level is substantially equivalent to that of the comparison tire.

10 to 13 are three-dimensional graphs showing the progress of sound pressure Pa of a sound wave signal with respect to speed (km / h) and frequency (Hz).

Figure 10 relates to the internal noise of a vehicle equipped with a tire of the present invention. 12 is related to the noise inside the vehicle in which the tire to be compared is mounted.

As shown in the graph, in the case of the tire according to the present invention, the noise has three different frequency ranges, namely the low frequency range (0-300 Hz), the tire pitch specific frequency range (800-1600 Hz), and the intermediate frequency range. Distributed at (300-800 Hz).

The comparative tires, on average, produce low levels of noise, but concentrate all disturbances in the low and high frequency portions.

The tire according to the invention, on the other hand, produces a weaker perceived noise by more evenly distributing the noise over the entire frequency range.

Figure 11 relates to the noise of the outside of the vehicle equipped with the tire of the present invention. Figure 13 relates to the noise of the outside of the vehicle equipped with the tire to be compared.

Unlike graphs for internal noise, graphs for external noise do not have a low frequency region specific to the transmission of noise "through solids" (via automobiles). On the other hand, noise generated in the mid and high frequency regions extending up to 2500 Hz ("air transfer") is prominent. The tire according to the invention in this case produces a distribution of noise over a wider frequency band, weakening the average intensity of the noise.

FIG. 14 shows a graph B2 for the tire of the present invention showing the intensity of the external noise ㏈ (A) versus speed (km / h) and a graph A2 for the tire to be compared.

The graphs are the so-called "coast-by-noise" tests performed on the vehicle described above on the track of Vizzola Ticino according to the ISO 10844 standard (ISO 362-1981, Corrected 1, 1985). Year). As is known, the reference speed in this test is 80 km / h.

The graphs of FIG. 14 demonstrate that the tire according to the invention is noisier by 2 kA (A) than the tire to be compared.

Claims (18)

Circumferential rows (9; 10; 11; 209) of blocks (13; 14; 15; 213; 215) located between the first and second circumferential grooves (3,4; 5,4; 6,5). An automotive tire (1) having an equatorial surface (7) comprising a tread (2) having at least one; 211 and two shoulders (8,12; 412), Each of the blocks 13; 14; 15; 213; 215 may have a portion 103; 105; 106 of the first circumferential groove 3; 5; 6, and the first circumferential groove 3; First and second transverse grooves 16, extending from 5; 6 and converging to a common vertex 19; 29; 39; 219; 239 spaced apart from the second circumferential groove 4; 5; 18; 28,26; 38,36; 216,218; 236,238 The common vertices (19; 29; 39; 219; 239) are separated from the second circumferential groove (4; 5) by successive circumferential tread ribs (20, 24; 30), The second lateral grooves 18; 26; 36; 218; 236, which determine the boundaries of the blocks 13; 14; 15; 213, are formed from the first circumferential grooves 3; 5; 6; A solid that extends to the lip (20; 24; 30) to form an integral body with the circumferential lip and that the block (13; 14; 15; 213; 215) and the next block are spaced apart from each other by a distance from each other; A first transverse groove 16; 28; 38; 216; 238 that defines the boundary of the next block 13; 14; 15; 213; 215 by the tread portion 21; 25; 31; 221; 231. Car tires isolated from the car. The method of claim 1, wherein at least one of the first and second lateral grooves (16,18; 28,26; 38,36; 216,218; 238,236) is the common vertex (19; 29; 39; 219; 239). In which the width increases in the direction toward the first circumferential groove (3; 5; 6). 3. The tire of claim 2, wherein at least one of the first and second lateral grooves (16, 18; 28, 26; 38, 36) is sickle shaped. 4. A centerline (66; 68) according to claim 3, wherein at least one of said first and second transverse grooves (16,18; 28,26; 38,36) is formed by an arc having a predetermined radius of curvature. Car tires, characterized in that having. 5. The centerline 66 according to claim 4, wherein the center line 66 has a predetermined slope with respect to the first portion 166 having a direction substantially parallel to the equator plane 7 and the first circumferential grooves 3; 5; 6. And a second portion (266) having a coupling portion and a coupling portion (366) for coupling the first and second portions (166, 266). 3. The method of claim 2, wherein at least one of the first and second transverse grooves (216, 218; 238, 236) comprises a first portion having a direction approximately parallel to the equator plane and a predetermined slope relative to the first circumferential groove. And a second portion having, and a joining portion for joining the first and second portions. The tire of claim 1, wherein each of the blocks 13; 14; 15; 213; 215 of at least one of the rows 9; 10; 11; 209; 211 has a shark fin shape. . The method of claim 1, wherein the first and second transverse grooves 16, 18; 28, 26; 38, 36; 216, 218; 238, 236 of at least one of the rows 9; 10; 11; 209; 211 of the blocks. Common vertices (19; 29; 39; 219; 239) are arranged in the same direction in the longitudinal direction. 2. Tire according to claim 1, characterized in that the tread (2) has a central circumferential block row (10) and first and second side circumferential block rows (9,11). 10. The method of claim 8 or 9, wherein the common vertices 19 of the first and second lateral grooves 16, 18 of the first side block row 9 are defined by the central block row 10 and For a motor vehicle, which is arranged in a direction opposite to the direction of the common vertices 29, 39 of the first and second transverse grooves 28, 26; 38, 36 of the second side block row 11. tire. 10. The common vertices 19 of claim 8 or 9, wherein the first and second transverse grooves 16, 18; 28, 26; 38, 36 of the three block rows 9, 10, 11. 29; 39 are automobile tires, characterized in that arranged in the same direction. 2. The tread (2) according to claim 1, wherein the tread (2) has two central circumferential ribs (230,231) separated by first and second side circumferential block rows (209,211) and intermediate circumferential grooves (232). A car tire characterized by the above-mentioned. The method of claim 12, wherein the common vertices 219 of the first side block row 209 are disposed in a direction opposite to the direction of the common vertices 239 of the second side block row 211. Car tires. 13. The first and second transverse directions of any one of claims 1, 9 and 12, wherein at least one of said first and second side circumferential block rows (9; 11; 209; 211). Grooves 16, 18; 28, 26; 38, 36; 216, 218; 238, 236 extend beyond each first circumferential groove 3; 6 and also in the axial direction of one of the shoulders 8; 12; 412. A tire for an automobile, characterized by extending into an interior region (108; 112). 4. The pair of additional transverse grooves (43) according to claim 1, wherein at least one of the shoulders (8; 12; 412) converges toward the common vertex (45, 55, 245) in the axial outer region (208; 212). And 44; 53,54; 243,244. 16. The method according to claim 15, characterized in that the additional converging lateral grooves (43, 44; 243, 244) are separated from the first circumferential groove (3; 6) by a solid portion (46) of elastomeric material. Car tires. 16. A tire according to claim 15, characterized in that the further converging lateral grooves (53,54) extend from the first circumferential groove (6). 18. The axially inner region 108 of one shoulder 8 has a smaller void / solid ratio than the axially inner region 112 of the other shoulder 12. And the tire (1) is located outside of the vehicle when the tire is mounted on the vehicle.