JP5418767B2 - Pneumatic tire - Google Patents

Description

  The present invention relates to a pneumatic tire that is used, for example, as a racing tire mounted on a vehicle that competes on a circuit.

  In recent years, in racing car competitions on the circuit, not only the improvement of the maximum speed but also the low fuel consumption has become an important factor affecting the competition results. That is, increasing the maximum speed is advantageous for overtaking the preceding vehicle, and improving fuel efficiency can reduce the number of pit-ins and significantly reduce the time.

  In general, improvement in maximum speed and fuel efficiency depends on engine performance and aerodynamic performance of the vehicle body, but it is also effective to reduce tire rolling resistance. In order to reduce the rolling resistance of the tire, use low heat-generating rubber for the tread, increase the dimensional specifications of the tire as much as possible, reduce the weight of the tire itself, and reduce the deflection of the tire structure under load. It is conceivable to adopt a tread pattern with little road resistance and heat generation.However, since the material and structure of such a tire also affect the steering stability and grip performance of the tire, these performance and Therefore, there is a limit to reducing rolling resistance.

  On the other hand, since it is considered that the speed and fuel consumption are affected by the air resistance of the tire, it is possible to improve the maximum speed and reduce the fuel consumption by reducing the air resistance of the tire. That is, as the vehicle speed (tire rotation speed) increases, the rolling resistance also increases, but in addition to this, the air resistance of the tire also increases. Therefore, in circuit races where the speed exceeds 200 km to 300 km per hour, driving of ordinary vehicles The air resistance of the tire is remarkably increased compared to the above, and particularly when the entire tire is exposed like a formula car, the influence of the air resistance of the tire is further increased.

  Therefore, in order to reduce the air resistance of the tire, a turbulent flow prevention region that does not have uneven portions such as grooves, patterns, letters, etc. is provided in the buttress portion extending from the tread end portion to the sidewall portion. It is known that the air resistance on the tire surface is reduced by preventing the above (for example, see Patent Document 1).

JP 2003-127615 A

  However, when the turbulent flow of the buttress is prevented, the air flow around the tire becomes a laminar flow, so that the pressure behind the tire when the vehicle travels becomes low, and the force to pull the tire back acts. become. For this reason, even if the air resistance on the tire surface is reduced, there is a problem in that a low pressure portion is generated behind the tire, so that the effect of reducing the air resistance during high-speed running cannot be obtained sufficiently.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a pneumatic tire that can effectively reduce the air resistance during high-speed running.

In order to achieve the above object, the present invention provides a pneumatic tire used as a racing tire in which a plurality of recesses are provided in a predetermined region on the outer surface of the tire in the tire circumferential direction and the tire radial direction. The shape is asymmetric between the inner side in the tire direction and the outer side in the tire radial direction, and is formed so as to have a shape with greater air peeling effect than the symmetrical shape, and each recess is formed to a depth of 0.5 mm or more and 5 mm or less. The maximum size of the opening surface is 2 mm or more and 8 mm or less, and the recesses are arranged so that the density increases as it goes outward in the tire radial direction .

As a result, turbulent flow is generated around the tire when the vehicle travels due to a large number of recesses provided on the outer surface of the tire. As a result, the drag by the low pressure part (the force to pull back) is reduced accordingly. In this case, the turbulent flow generation effect is further improved by making each concave portion an asymmetric shape having a larger air separation effect than the symmetrical shape .

  According to the present invention, it is possible to reduce a drag force that pulls the tire backwards during traveling, so that air resistance during high-speed traveling can be effectively reduced. In particular, in circuit races where the speed exceeds 200 km to 300 km per hour, the increase in tire air resistance is significant compared to the driving of ordinary vehicles. Therefore, the maximum speed can be increased by reducing the tire air resistance, and low The fuel efficiency can be improved, which is extremely advantageous as a racing tire.

Partial front sectional view of a pneumatic tire showing a first reference example of the present invention Partial side view of pneumatic tire Top view of the recess Side sectional view of recess The partial side view of the pneumatic tire which shows the 2nd reference example of this invention The partial side view of the pneumatic tire which shows the 3rd reference example of this invention Top view of the recess Side sectional view of recess The top view which shows the modification of a recessed part Side sectional view showing a modified example of the recess Partial front sectional view of a pneumatic tire showing a fourth reference example of the present invention Partial side view of pneumatic tire Side sectional view of the protrusion The top view which shows the modification of a protrusion Side surface sectional drawing of the recessed part which shows the 1st Embodiment of this invention Top view of the recess Side surface sectional drawing of the recessed part which shows the 2nd Embodiment of this invention Top view of the recess Schematic showing the air flow around the tire Diagram showing test results

Hereinafter, a first reference example of the present invention will be described with reference to FIGS. The pneumatic tires shown in the figure are racing tires used in circuit races (for example, circuit races stipulated in the FIA International Motor Sports Competition Rules) (eg tires stipulated in the 2008 FIA Formula 1 World Championship Rules). A tread portion 1 formed on the tire outer peripheral surface side, a pair of sidewall portions 2 formed on both sides in the tire width direction, a pair of bead portions 3 formed on both sides in the tire width direction, A buttress portion 4 is formed between the tread portion 1 and the sidewall portion 2.

  The pneumatic tire includes an inner liner 5 disposed on the inner surface of the tire, a carcass member 6 disposed on the outer side of the inner liner 5, a pair of bead members 7 disposed on both sides in the tire width direction, and the carcass member 6 The belt 8 is arranged on the outer side of the tire, the tread member 9 is arranged on the tire outer peripheral surface side, and the pair of sidewall members 10 are arranged on both sides of the tire.

  The inner liner 5 is made of a sheet-like rubber having low gas permeability, and is disposed on the inner peripheral surface side of the carcass member 6.

  The carcass member 6 is formed by covering a plurality of reinforcing cords 6a with sheet-like rubber, and is folded back toward the sidewall portion 2 from the inner side to the outer side in the tire width direction so as to enclose the bead member at both ends.

  The bead member 7 includes a bead core 7a formed by bundling wires such as metal wires and a bead filler 7b formed of rubber having a substantially triangular cross section. The bead filler 7b is disposed on the outer peripheral side of the bead core 7a.

  The belt 8 is formed by coating a belt cord made of steel, high-strength fiber, or the like with a sheet-like rubber, and is disposed on the outer peripheral surface side of the carcass member 6.

  The tread member 9 is made of rubber formed by extrusion molding, and is disposed so as to cover the center side in the width direction of the carcass member 6 and the outer peripheral surface side of the belt 8.

  The sidewall member 10 is made of rubber formed by extrusion molding and is disposed so as to cover both sides of the carcass member 6 in the tire width direction.

  Many in the tire circumferential direction and the tire radial direction in a predetermined region A (for example, a range of 35% to 85% of the tire cross-section height H from the tire radial direction inner end portion) on the outer surface of the pneumatic tire. The recess 11 is provided. The tire cross-sectional height refers to the tire cross-sectional height when the tire is filled with air pressure of 130 kPa and the load is 3000 N. Each recess 11 is formed in a circular spherical shape having a central portion depth H of 0.5 mm or more and 5 mm or less and a maximum size L (diameter) of the opening surface of 2 mm or more and 8 mm or less. Formed at regular intervals. In this case, each recess 11 is formed so that the total area (area of all the recesses 11 on the tire surface) is 30% or more and 80% or less with respect to the region A. In addition, the recessed part 11 does not include the recessed part which consists of a character, a symbol, or a mark displayed on a tire side surface.

In the pneumatic tire, turbulent flow is generated around the tire when the vehicle travels due to the large number of recesses 11 provided on the outer surface of the tire, and air is easily separated from the tire surface. As a result, as shown in FIGS. 19 (a) and 19 (b), the low-pressure portion P (the region having a low air density) generated behind the tire T1 having the recess 11 is smaller than the tire T2 having no recess 11, and accordingly. As a result, the drag (force to pull back backward) due to the low pressure portion P is reduced.

As described above , according to the pneumatic tire, by providing a large number of recesses 11 in the tire circumferential direction and the tire radial direction in the predetermined region A on the tire outer surface, each recess 11 causes turbulent flow to the air around the tire. Therefore, it is possible to reduce the drag force to pull the tire backward, and to effectively reduce the air resistance of the tire during high speed running. In particular, in circuit races where the speed exceeds 200 km to 300 km per hour, the increase in tire air resistance is significant compared to the driving of ordinary vehicles. Therefore, the maximum speed can be increased by reducing the tire air resistance, and low The fuel efficiency can be improved, which is extremely advantageous as a racing tire. In addition, the racing car has an aerodynamic design in which the vehicle body is pressed against the road surface in order to prevent the vehicle from lifting when traveling at high speeds. If a turbulent flow is generated around the tire, an appropriate lift is imparted to the tire and the contact pressure is reduced, which is advantageous in improving fuel efficiency.

  Further, each recess 11 is formed to a depth H of 0.5 mm or more and 5 mm or less and the maximum size L of the opening surface is formed to be 2 mm or more and 8 mm or less. There is an advantage that the flow generation effect does not become insufficient, and the concave portion 11 is too large so that the rubber thickness is not insufficient.

In the reference example , the concave portions 11 are arranged at equal intervals. However, as shown in the second reference example of FIG. 5, the density increases as the concave portions 11 are located on the outer side in the tire radial direction. You may make it arrange | position to. Thereby, many recessed parts 11 can be arrange | positioned in the tire radial direction outer side where a rotational speed becomes relatively faster than a tire radial direction inner side, and the turbulent flow generation effect by each recessed part 11 can be heightened more. In this case, the density of the recesses 11 is preferably 6 to 9 per square centimeter on the outer side in the tire radial direction and 1 to 3 per square centimeter on the inner side in the tire radial direction.

In the reference example , the circular recess 11 is provided. However, as shown in the third reference example of FIGS. 6 to 8, a large number of circular recesses 12 and a large number of squares are provided. The recess 13 may be mixed. Thereby, the unevenness | corrugation in the area | region A becomes irregular, and can improve the turbulent flow generation effect more.

  Further, as shown in FIG. 9 (a), a concave portion 14 having chamfered square corners, an elliptical concave portion 15 as shown in FIG. 9 (b), and a triangular concave portion as shown in FIG. 9 (c). 16 may be provided, or two or more kinds of recesses may be mixed.

  The recess may be formed to a uniform depth, but the inner surface is tapered as shown in FIG. 10 (a) and the inner surface is tapered as shown in FIG. 10 (b). A concave portion 18 having a narrow bottom surface and a concave portion 19 having a concave bottom surface as shown in FIG. 10 (c) may be provided, or two or more types of concave portions may be mixed. May be.

Furthermore, in the third reference example, a configuration in which a large number of circular recesses 12 and a large number of quadrangle recesses 13 are mixed is shown. In the fourth reference example of FIGS. As shown, a large number of conical protrusions 20 may be mixed in addition to the circular recess 12 and the rectangular recess 13. That is, since the protrusions 20 are mixed in the recesses 11 and 13, the irregularities in the region A can be made more irregular, which is extremely advantageous for improving the effect of generating turbulence. In FIG. 12, the protrusion 20 is painted in black to distinguish it from the recess 12.

  In this case, turbulent flow is generated by the protrusions 20 by forming each protrusion 20 so that its height H is 1 mm or more and 5 mm or less and the maximum size L in the tire radial direction of its bottom surface is 5 mm or less. An effect can be sufficiently obtained, and an increase in air resistance due to the projection 20 being too large can be suppressed.

  Moreover, by providing each protrusion 20 so that the ratio is less than the number of the recesses 11 and 13, an increase in air resistance due to the excessive protrusion 20 can be suppressed. In this case, the ratio of the number 1 to 2 of the protrusions 20 to the number 5 to 7 of the recesses 11 and 13 is preferable.

In the fourth reference example , the one having the conical (triangular cross-sectional) protrusion 20 is shown. However, as shown in FIG. As shown in FIG. 14 (b), a protrusion 22 having a trapezoidal shape with a narrow upper surface, and a protrusion 23 having a curved upper surface as shown in FIG. 14 (c) are provided. Alternatively, two or more types of recesses may be mixed. In this case, a protrusion having a rectangular, elliptical, or triangular bottom may be provided.

In the fourth reference example , the recesses 11 and 13 and the protrusions 20 are arranged at equal intervals. However, as in the second reference example , the recesses 11 and 13 and the protrusions are arranged. You may arrange | position 20 so that a density may become so high that it becomes a tire radial direction outer side.

The first embodiment of the present invention shown in FIGS. 15 and 16 is provided with a recess 23 having an asymmetric shape between the inner side in the tire radial direction and the outer side in the tire radial direction. That is, the concave portion 23 is formed in a circular spherical shape, and a raised portion 23a bulging outward from the tire is formed at an opening edge on the inner side in the tire radial direction (right side in the drawing). As a result, the height H1 from the bottom of the recess 23 at the opening edge on the inner side in the tire radial direction becomes higher than the height H2 from the bottom of the recess 23 at the opening edge on the outer side in the tire radial direction. As shown in FIG. 5, the air peeling effect due to the air flowing from the front hitting the raised portion 23a is improved as compared with the symmetrical shape, and the turbulent flow generating effect can be further improved. In this case, it is possible to suppress an increase in air resistance due to the raised portion 23a by forming the raised portion 23a so as to rise smoothly.

In addition, the second embodiment of the present invention shown in FIGS. 17 and 18 is provided with recesses 24 of other shapes that are asymmetrical on the inner side in the tire radial direction and the outer side in the tire radial direction. That is, the recess 24 is formed in a spherical shape, and the opening edge side on the outer side in the tire radial direction (left side in the figure) forms a gentler slope than the opening edge side on the inner side in the tire radial direction (right side in the figure). Is formed. As a result, air easily enters the concave portion 24 from the opening edge on the tire radial direction outer side, so that air flowing from the front hits the opening edge on the inner side in the tire radial direction as shown by a solid line arrow in the figure. The peeling effect is improved as compared with the symmetrical shape, and the turbulent flow generation effect can be further improved.

The recesses 23 and 24 in the first and second embodiments are merely examples, and the recesses having a shape different from those in the first and second embodiments may be used as long as they have an asymmetric shape having a greater air separation effect than the symmetrical shape. May be provided .

In here, the reference examples 1 to 5 and Conventional Example was subjected to a test at a maximum speed and fuel economy, the results shown in FIG. 20 were obtained. In this test, a conventional example having no recesses and protrusions is used, Reference Examples 1 and 2 have only circular recesses, and Reference Examples 3 and 4 have a circular recess and a square shape. In the reference example 5, a mixture of a circular recess, a square recess, and a conical protrusion was used. In this case, in Reference Examples 1 and 3, the density of the recesses is uniform in the tire radial direction inside and outside, and in Reference Examples 2, 4 and 5, the density of the recesses in the tire radial direction inside is 100, The thing whose density of the recessed part in a tire radial direction outer side is set to 130 was used.

  In this test, a racing tire having a tire size of 240/45 VR13 and an air pressure of 130 kPa was mounted on a Formula 4 machine and traveled on a race circuit.

In the maximum speed test, the speed when the maximum speed was reached in the race circuit was indexed, and Reference Examples 1 to 5 were evaluated with the conventional example as 100. In this case, the larger the index value, the more superior. As a result of the test, it was found that Reference Examples 1 to 5 can increase the maximum speed as compared with the conventional example.

In the test of low fuel consumption, the fuel consumption when running 50 laps at an average speed of 100 km / h on a race circuit was measured and indexed, and Reference Examples 1 to 5 were evaluated using the conventional example as 100. In this case, the larger the index value, the more superior. As a result of the test, it was found that Reference Examples 1 to 5 were more excellent in fuel efficiency than the conventional examples.

  DESCRIPTION OF SYMBOLS 1 ... Tread part, 2 ... Side wall part, 3 ... Bead part, 4 ... Buttress part, 11, 12, 13, 14, 15, 16, 17, 18, 19 ... Recessed part, 20, 21, 22, 23, 24 ... protrusion, A ... area.

Claims (3)

In pneumatic tires used as racing tires,
A number of recesses are provided in a predetermined region on the outer surface of the tire over the tire circumferential direction and the tire radial direction ,
Each recess is a shape that is asymmetric between the tire radial inner side and the tire radial outer side, and is formed to have a shape with a greater air peeling effect than the symmetrical shape,
Each recess is formed to a depth of 0.5 mm to 5 mm, and the maximum size of the opening surface is 2 mm to 8 mm,
A pneumatic tire characterized in that each recess is arranged so that the density increases as it goes outward in the tire radial direction . The pneumatic tire of claim 1, wherein each recess opening edge of the inner side in the tire radial direction is equal to or formed on the high becomes asymmetrical than the opening edge portion of the outer side in the tire radial direction. The pneumatic tire of claim 1, wherein each recess opening edge side of the tire radial direction outer side, characterized in that the formed asymmetrically forming a gentle slope than the opening edge side of the inner side in the tire radial direction.

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