JPH0446796B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pneumatic tire arrangement structure for a four-wheeled vehicle that can improve running performance on wet road surfaces.

[Prior art]

Generally, when a four-wheeled vehicle such as a passenger car runs on a wet road surface (straight road, curved road), the coefficient of friction between the tires and the road surface decreases. Especially when the water depth on the wet road surface is deep or the driving speed is high,
A layer of water forms between the tire and the road, significantly reducing the coefficient of friction. This condition is called hydroplaning.

If hydroplaning occurs, the vehicle may become uncontrollable and an accident may occur. This hydroplaning is likely to occur with flat tires that run at high speeds.

Therefore, various attempts have been made to prevent the occurrence of hydroplaning. For example, the shape of the grooves formed on the tread surface of a tire can be modified to improve drainage, a rubber composition with good wet grip properties can be placed on the tread to delay the formation of a water film, and the tread surface can be improved. A lug groove with a convex part is placed in the center of the width direction of the bag, and the convex part is used to repel water.

However, the current situation is that no satisfactory solution has yet been proposed, and in particular, no consideration has been given to driving performance during cornering.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire arrangement structure for a four-wheeled vehicle that can exhibit excellent driving performance when driving on a wet road surface, especially when cornering.

[Structure of the invention]

For this reason, the present invention provides a four-wheeled vehicle in which a pneumatic tire is mounted on each wheel, in which each of the pneumatic tires has a carcass layer mounted between a pair of left and right bead portions, and the carcass layer and the tread are connected to each other. A pneumatic tire is a radial tire having a structure in which a plurality of belt layers are arranged between the belt layers, and is attached to the wheel on the right side in the traveling direction when viewed from above of the four-wheeled vehicle. The cord inclination direction is downward to the left in the direction of travel, and the tread pattern on the tread surface includes a plurality of linear main grooves that are annular in the circumferential direction of the tire, and a plurality of linear main grooves that connect these linear main grooves and extend to both ground contact ends. A lug groove is provided, and the lug groove on the upper tread surface is bent into an inverted V-shaped convex shape having an apex in the traveling direction, and this bent portion is shaped to the right side in the traveling direction from the center of the tread development width. On the other hand, a pneumatic tire mounted on a wheel on the left side in the direction of travel has a cord inclination direction of the outermost belt layer on the sky side that is downward to the right in the direction of travel, and a tread pattern on the tread surface that is annular in the tire circumferential direction. A plurality of linear main grooves and a plurality of lug grooves connecting these linear main grooves and extending over both ground contact ends are provided, and the lug grooves on the upper tread surface are formed into an inverted V shape having an apex in the traveling direction. The gist of this invention is a pneumatic tire arrangement structure for a four-wheeled vehicle which is bent in a convex and convex shape and the bent part is on the left side of the center of the tread width in the traveling direction.

As described above, in the present invention, tires having different cord inclination directions and tread patterns of the belt layers are mounted on the left and right wheels of a four-wheeled vehicle, so that running performance on wet road surfaces can be improved.

Hereinafter, the configuration of the present invention will be explained in detail with reference to the drawings.

A pneumatic tire is generally constructed as shown in FIG. FIG. 1 is an explanatory half-sectional view in the meridian direction of an example of a pneumatic tire. In FIG. 1, 1 is a tread, and 2 is a carcass layer installed between a pair of left and right bead cores 4, 4. In the tread 1, an outer belt layer 3u and an inner belt surround the outer periphery of this carcass layer 2. Layer 3d is arranged. 5, 5 is a pair of left and right side wall portions connected to a pair of left and right bead portions, 6
is the crown portion consisting of the tread 1. In addition,
7 is a belt cover layer. In high-speed tires, a belt cover layer 7 made of nylon cord or the like, which has much lower rigidity than the belt layers 3u and 3d, is arranged circumferentially outside the outer belt layer 3u in order to improve high-speed durability. Since this belt cover layer 7 does not directly affect the performance of the present invention, description of the belt cover layer will be omitted here. Note that in the present invention, the belt cover layer 7 may or may not be provided.

(1) In the present invention, when tires having multiple belt layers are installed on a four-wheeled vehicle, the outermost belt layer on the sky side is attached to the right wheel in the direction of travel, as shown in FIG. Tires are arranged so that the cord inclination direction is downward to the left in the direction of travel when viewed from above the vehicle. On the other hand, as shown in FIG. 3, the wheel on the left side in the traveling direction is equipped with a tire in which the cord inclination direction of the outermost belt layer on the sky side is downward to the right in the traveling direction when viewed from above the vehicle. In addition, in these FIGS. 2 and 3, arrow E indicates the tire rotation direction as seen from above the vehicle. The tire rotation direction E and the vehicle traveling direction are the same.

As shown in FIG. 2, the tire on the right side in the traveling direction has the outermost belt layer 3 on the sky side.
The inclination direction of the cord 8 of the u is downward to the left with respect to the tire rotation direction E (hereinafter referred to as an L-stick structure). Further, as shown in FIG. 3, in the tire on the left side in the traveling direction, the inclination direction of the cord 8 of the outermost belt layer 3u on the sky side is downward to the right with respect to the tire rotation direction E (hereinafter referred to as R (referred to as a pasted structure). The angle of inclination of the cord 8 with respect to the tire rotation direction E is not specified, but may be about 15° to 35°.

(2) Furthermore, in the present invention, a tread pattern as shown in FIGS. 4A and 4B is formed on the upper tread surface of each tire.

FIG. 4A shows the tread pattern of the tire on the right side in the direction of travel, and FIG. 4B shows the tread pattern of the tire on the left side in the direction of travel.

These tread patterns are formed by dividing blocks 20 by a plurality of linear main grooves 10 that are annular in the circumferential direction of the tire and lug grooves 11 that connect these linear main grooves 10. The lug groove 11 is provided with a bent portion 12 bent into an inverted V-shaped convex shape having an apex in the tire rotation direction E, and this bent portion 12 extends from the center of the tread width T in the traveling direction (tire rotation direction E ) located on the outside.

That is, in the tire on the right side in the traveling direction, the bent portion 12 is located on the right side in the traveling direction from the center of the tread expansion width T (Fig. 4A)), while in the tire on the left side in the traveling direction, the bent portion 12 is located at the right side of the tread expansion width T. It is located to the left of the center of T in the direction of travel (Fig. 4B).

The number of linear main grooves 10 is three or more,
Five to seven pieces are preferred. The lug grooves 11 are linear or curved, and the angle of inclination with respect to the tire rotation direction E is not particularly limited, but is 20° to 80°, preferably 30° to 60°. The pitch interval P is 20 to 50 mm, preferably 25 to 30 mm. The groove width of the lug groove 11 is 3 to 10 mm, preferably about 5 mm.

The distance from the center of the tread development width T of the bent portion 12 is indicated by a in FIG. In Figure 5,
M is the center line of the tread development width T.

Regarding this distance a, the relationship between A=a/(tread development width T/2) and wet circle turning lap time was investigated, and the results shown in FIG. 6 were obtained. In FIG. 6, a positive value indicates that the bent portion 12 is on the outside, a negative value indicates that the bent portion 12 is on the inside, the vertical axis represents the lap time, and the horizontal axis represents the value of A (note that , on the horizontal axis, O indicates the center position of the tread development width T). Moreover, in FIG. 6, ● indicates the case where there is no bent portion. 6th
The figure shows that the larger the value, the slower the lap time and the worse the drainage performance. From FIG. 6, it can be seen that the A value is preferably in the range of 0.2 to 0.8. That is, if it is outside this range, the lap time will be slow and the drainage performance will be poor.

(3) As described above, the pneumatic tire of the present invention comprising the above (1) and (2) has a symmetrical profile structure in which the tread radius of the tire is the same on the left and right sides with respect to the tire equatorial plane. It is also possible to use an asymmetrical profile structure in which the tread radius of the tire is different on the left and right sides with respect to the tire equator plane, as shown in FIGS. 7A and 7B.

FIG. 7A shows a tire with an asymmetric profile structure on the right side in the direction of travel, and FIG. 7B shows a tire with an asymmetric profile structure on the left side in the direction of travel. In these FIGS. 7A and 7B, the tread radius TR ₁ is larger than TR ₂ , and the tread radius TR _{1 is mounted so that the TR 1} side faces outside of the vehicle.

Next, the reason for specifying the above (1) and (2) in the present invention will be explained using pneumatic tires with a symmetrical profile structure and an L-stacked structure and an R-stacked structure.

8, 9 and 10 show various tread patterns on the upper tread surface. Fig. 8A and B show the bent portion 1 of the lug groove 11.
2 is located on the right side of the tire rotational direction (in the direction of the arrow) from the center of the tread development width T, and FIGS. 9A and 9B show the case where the bent portion 12 of the lug groove 11 is located at the center of the tread development width T. 10A and 10B respectively show the case where the bent portion 12 of the lug groove 11 is located on the left side of the center of the tread development width T in the tire rotational direction (in the direction of the arrow).

Cornering force and tire rotational speed (Nrpm) were measured indoors on a wet road surface (water depth 4 mm) and a dry road surface (drum surface) for the following tires using the tread patterns of these three designs. This result is shown in Figure 11A,
Shown in B.

Tire A and tire D have the patterns shown in FIG. 8A and B.

Tire B and tire E have the patterns shown in FIG. 9A and B.

Tire C and tire F have the patterns shown in FIG. 10A and B.

Tires A, B, and C are L-stacked structure, and tire D is
E and F have R pasting structures. These relationships can be summarized as follows.

(a) Tires A, B, and C have L-layer structure.

() Tire A has the patterns shown in FIG. 8A and B.

() Tire B has the patterns shown in FIG. 9A and B.

() Tire C has the patterns shown in FIG. 10A and B.

(b) Tires D, E, and F have R pasting structure.

() Tire D has the patterns shown in FIG. 8A and B.

() Tire E has the patterns shown in FIG. 9A and B.

() Tire F has the patterns shown in FIG. 10A and B.

In Figures 11A and B, the horizontal axis is the speed (Km/
h), and the vertical axis represents tire rotation speed (Nrpm) and cornering force (CF (Kg)).
Further, FIG. 11A shows the case of a tire with an L-stacked structure, and FIG. 11 shows the case of a tire with a BR-stacked structure.

As is clear from FIG. 11A, in tires with an L-stack structure, in the case of a negative slip angle (left turning), the bent portion 12 of the lug groove 11 is on the right side (serial side) in the rotational direction of the tire (tire In A), the degree of decrease in cornering force on a wet road surface is low, the decrease in tire rotational speed is also low, and the friction between the road surface and the tire contact surface is large. It also has great cornering force on dry roads. As shown in Fig. 11B, for tires with an R pasting structure, when the slip angle is positive (turning to the right), the bent portion 12 of the lug groove 11 is on the left side in the rotational direction of the tire (tire F). The degree of decrease in cornering force on the road surface is low, the decrease in tire rotational speed is also low, and the friction between the road surface and the tire contact surface is large. It can also be seen that the cornering force on dry roads is also large.

In addition, in FIG. 11A, when the tire serial side is on the right side and the slip angle of the tire is toward the right side, it is assumed to be positive. In FIG. 11B, it is positive that the tire serial side is on the left side and the tire slip angle is on the right side.

By the way, normally when a vehicle tries to turn a corner, the load is transferred to the tires located on the outer side of the vehicle on the same axis when viewed from the center of the vehicle's turning radius.
Compared to when the vehicle is traveling straight, the load on the tires located on the outside becomes larger, while the load on the tires located on the inside becomes smaller. For this reason, in the present invention, the tread pattern is defined as described in (2) above, and the lug grooves on the tread surface of the tire located on the outer side, which is subjected to a large load during cornering, are oriented in the direction in which centrifugal force acts. Improves drainage during cornering. And, at this outer position, the cord inclination direction of the outermost belt layer of the tire is set as above.
By intersecting the lug grooves with the cords of this belt layer as specified in (1), the decrease in tread rigidity due to the provision of the lug grooves can be minimized, and centrifugal force can be reduced. By making the cord direction of the belt layer almost perpendicular to the direction of action, the resistance of the tread surface to centrifugal force is increased, thereby increasing the cornering force. Therefore, by mounting tire A on the right side and tire F on the left side, higher cornering force (frictional force) can be obtained even when driving on a wet road surface. This is because the positive slip angle of the left tire makes a large contribution to the cornering force when turning to the right, and the negative slip angle of the right tire makes a large contribution to the cornering force when turning to the left.

Therefore, in the case where the right side tire has an L-stack structure and the left side tire has an R-stack structure, the bent portion of the lug groove is located on the outside of the convex lug groove with respect to the rotational direction of each tire. It turns out that you can design it like this.

Examples are shown below.

EXAMPLE An actual vehicle running test was conducted using the tire arrangement as shown in FIG. 12 and below.

Tire arrangement S ₁ (comparative example shown in FIG. 12A): Tire structure; symmetrical profile.

Bent part of lug groove; center of tread expansion width.

Right tire: L-stacked structure (Fig. 9A).

Left tire: R pasting structure (Fig. 9A).

Number of linear main grooves 10: 5, linear main grooves 10
Depth: 8 mm, Width of the linear main groove 10: 10 mm, Depth of the lug groove 11: Maximum 8 mm, becoming shallower towards the shoulder, Width of the lug groove 11: 6 mm, Incline of the lug groove 11 with respect to the tire rotation direction E. Angle: 50°, pitch interval P: 40mm.

Tire arrangement S ₂ (example of the invention shown in FIG. 12B): Tire structure; symmetrical profile.

Lug groove bent part; outside.

Right tire: L-stack structure (Fig. 8A).

Left tire: R pasting structure (Fig. 10A).

Number of linear main grooves 10: 5, linear main grooves 10
Depth: 8 mm, Width of the linear main groove 10: 10 mm, Depth of the lug groove 11: Maximum 8 mm, becoming shallower towards the shoulder, Width of the lug groove 11: 6 mm, Incline of the lug groove 11 with respect to the tire rotation direction E. Angle: 50°, pitch interval P: 40mm.

Tire arrangement S ₃ (example of the invention shown in FIG. 12C): Tire structure; asymmetrical profile.

Lug groove bent part; outside.

Right tire: L-stack structure (Fig. 8A).

Left tire: R pasting structure (Fig. 10A).

Number of linear main grooves 10: 5, linear main grooves 10
Depth: 8 mm, Width of the linear main groove 10: 10 mm, Depth of the lug groove 11: Maximum 8 mm, becoming shallower towards the shoulder, Width of the lug groove 11: 6 mm, Incline of the lug groove 11 with respect to the tire rotation direction E. Angle: 50°, pitch interval P: 40mm.

The test car in this case was an Alpina B7S Turbo with tire size 225/50VR16. In addition, the actual vehicle running test was conducted by making a circular turn on a fixed circumference (including a part of the wet road surface (water depth 4 mm)) and measuring the running speed and lateral acceleration. The results are shown in FIG. In FIG. 13, ◯ indicates tire arrangement S ₁ , × indicates tire arrangement S ₂ , and △ indicates tire arrangement S ₃ . The vertical axis represents lateral acceleration (G), and the horizontal axis represents traveling speed (Km/h).

From FIG. 13, it can be seen that the tire arrangement S2, which has a bent lug groove on the outside of the tire, has a tread pattern design in which the tire arrangement _S2 , which has a lug groove bent part on the outside of the tire, has a higher speed in the lateral direction than the tire arrangement _S1 , which has a lug groove bent part in the center of the tire. It can be seen that the drop in acceleration is small and the critical speed for hydroplaning is high. In addition, the asymmetric profile of tire arrangement S ₃ has a smaller decrease in lateral acceleration than tire arrangement S ₂ , has the highest limit speed for hydroplaning, and can safely maneuver the vehicle even at high speeds. It shows that there is.

〔Effect of the invention〕

As explained above, according to the present invention, the belt layer has an L-stacked structure and an R-stacked structure, and the inverted V-shaped convex bent portions of the lug grooves in the tread pattern on the tread surface on the upper side can be adjusted to the tread development width. Since the tires are arranged on the four-wheeled vehicle so that they are positioned outward in the direction of travel from the center of the vehicle, the running performance on wet road surfaces can be sufficiently improved.

[Brief explanation of the drawing]

Fig. 1 is an explanatory half-section diagram in the meridian direction of an example of a pneumatic tire, Fig. 2 is an explanatory diagram of the tire on the right side in the direction of travel of coaxial left and right pneumatic tires mounted on a vehicle, and Fig. 3 FIG. 2 is an explanatory diagram of the tire on the left side in the traveling direction among the coaxial left and right pneumatic tires installed. Figure 4A is an explanatory diagram showing the tread pattern of the tire on the right side in the direction of travel;
FIG. B is an explanatory diagram showing the tread pattern of the tire on the left side in the traveling direction. FIG. 5 is an explanatory diagram showing the distance from the center of the tread development width of the bent portion of the lug groove, and FIG. 6 is a diagram showing the relationship between wrap time and A=a/(tread development width T/2). FIG. 7A is an explanatory diagram showing a tire with an asymmetric profile structure on the right side in the traveling direction, and FIG. 7B is an explanatory diagram showing a tire with an asymmetric profile structure on the left side in the traveling direction. Figure 8 A, B, Figure 9 A, B and Figure 10 A, B
is an explanatory diagram showing various tread patterns, No. 11
Figures A and B show speed (Km/h), tire rotation speed (Nrpm), and cornering force (CF
(Kg)). FIGS. 12A, B, and C are schematic diagrams of tires mounted on a vehicle, and FIG. 13 is a diagram showing the relationship between running speed and lateral acceleration. 1...Treasured, 2...Carcass layer, 3u...
Outer belt layer, 3d... Inner belt layer, 4... Bead core, 5... Side wall part, 6... Crown part, 7... Rim, 8... Cord, 10... Main groove, 11... Lug groove , 12...Bending part.

Claims (1)

[Claims] 1. In a four-wheeled vehicle in which each wheel is equipped with a pneumatic tire, each of the pneumatic tires has a carcass layer mounted between a pair of left and right bead portions,
The pneumatic tire is a radial tire having a structure in which a plurality of belt layers are arranged between the carcass layer and the tread, and is mounted on the right wheel in the traveling direction of the four-wheeled vehicle when viewed from above. The cord inclination direction of the belt layer on the outer circumferential side is downward to the left in the traveling direction, and the tread pattern on the tread surface connects a plurality of linear main grooves in an annular shape in the circumferential direction of the tire. In addition to providing a plurality of lug grooves spanning the ground contact end, the lug grooves on the upper tread surface are bent into an inverted V-shaped convex shape with an apex in the traveling direction, and this bent portion is extended from the center of the tread development width in the traveling direction. While shaping the right side,
The pneumatic tires to be attached to the wheels on the left side in the direction of travel are those in which the cord inclination direction of the outermost belt layer on the upper side is downward to the right in the direction of travel, and the tread pattern on the tread surface is annular in the tire circumferential direction. A plurality of lug grooves connecting the linear main grooves and extending over both ground contact ends are provided, and the lug grooves on the upper tread surface are formed with an inverted V-shaped convex having an apex in the traveling direction. bend into shape,
A pneumatic tire arrangement structure for a four-wheeled vehicle in which this bent part is located to the left of the center of the tread width in the direction of travel.