JP4437854B2 - Pneumatic tire, pneumatic tire unit, and method of mounting pneumatic tire - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pneumatic tire, a pneumatic tire unit, and a method for attaching a pneumatic tire, and more particularly, a pneumatic tire, a pneumatic tire unit, and a pneumatic tire capable of improving turning performance and straight running stability at high speed. It relates to the mounting method.
[0002]
[Prior art]
Since the traveling vehicle is affected by disturbances caused by road surface conditions, wind, steering, etc., the disturbances have a great influence on the steering stability of the tire.
[0003]
On the other hand, with the development of the highway network and higher output of vehicles, opportunities for high-speed driving are increasing, but the straight running stability, which is important in this high-speed driving, is influenced by the above disturbance and the course correction by steering. The effect of ease of operation is large.
[0004]
[Problems to be solved by the invention]
Conventionally, in order to improve the above-mentioned performance, flattening has been attempted to increase the lateral rigidity of the tire in order to increase the lateral force (SF) generated at the time of steering. Is the current situation.
[0005]
In particular, when tires with a flatness ratio of 60% or less are mounted on a relatively heavy vehicle, the influence of disturbance is extremely large, and the current situation is that the straight running stability at high speed is not satisfactory. .
[0006]
In consideration of the above facts, the present invention improves the turning performance of the vehicle and improves the straight running stability at high speed running, and also improves the turning performance of the vehicle and high speed running. It is an object of the present invention to provide a method for mounting a pneumatic tire that can improve the straight running stability.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 is a pair of left and right bead portions in which bead cores are embedded, a carcass having end portions wound up around the bead portions and straddling from one bead portion to the other bead portion, and the carcass A pneumatic tire comprising a sidewall portion provided on the outer side in the tire width direction, a belt provided on the crown portion of the carcass, and a tread portion provided on the outer side in the tire radial direction of the belt,
The shape of the carcass in the cross-section in the width direction when it is assembled to a regular rim and filled with an internal pressure of 10% of the specified internal pressure is at least from the center of the bead core on the side portion side located in the vehicle width direction when the vehicle is mounted When the maximum height of the carcass measured along the tire radial direction is H, the maximum width position of the carcass measured along the tire radial direction from the center of the bead core is 0.4 to 0.6H. When the radius of curvature of the carcass at the maximum width position is Ra having a center of curvature inside the tire, the carcass in the range from the maximum width position to the end of the belt has an arc portion with a radius of curvature Ra. A circular arc portion having a center of curvature inside the tire and a tire having a radius of curvature Rb larger than the radius of curvature Ra inside the tire's virtual extension line, or a tire Arc portion having a center of curvature is characterized by being provided on the side.
[0008]
First, when the vehicle turns, a steering angle is added to the tire, and the tire generates a lateral force. At this time, the tire is bent and deformed laterally within the cross section in the width direction, and the ground contact end on the side of the lateral force is lifted. It makes me feel. Further, when the vehicle turns, the load on the tire on the outer side in the turning radius increases, so that a large lateral force acts on the tire on the outer side in the turning radius direction.
[0009]
For example, when turning right, a large lateral force acts on the left tire from the outside of the vehicle to the inside. When a lateral force acts on the left tire, each bead portion rotates and deforms around the bead core along with the lateral force deflection of the sidewall portion of the left tire and rotates to the left as viewed from the rear of the vehicle. For this reason, when turning right, the vehicle inner portion of the left tire on which a particularly large lateral force acts tends to float off the road surface. When turning left, on the contrary, the vehicle inner portion of the right tire tends to lift from the road surface.
[0010]
In order to improve the turning performance, it is effective to suppress the tread lift and secure the ground contact area. It is better to add a rigidity difference between the lateral force input side and the output side to increase the output side rigidity. .
[0011]
According to the pneumatic tire of the first aspect, on the side portion side located on the inner side in the vehicle width direction when the vehicle is mounted, the carcass on the bead portion side from the maximum width position of the carcass has a center of curvature inside the tire. An arc portion having a center of curvature inside the tire formed with a radius of curvature Rb larger than the radius of curvature Ra so as to be located inside the tire of the virtual extension line of the arc of the radius of curvature Ra at the maximum width position, or the outside of the tire Since the arc portion having the center of curvature is provided, when the normal internal pressure is filled, the arc portion having the center of curvature inside the tire formed with the radius of curvature Rb or the arc portion having the center of curvature outside the tire is formed. The bulge amount is larger than that of the arc portion formed with the curvature radius Ra, and the tension of the carcass is increased to increase the rigidity.
[0012]
Thereby, it is possible to suppress the lifting of the inner portion of the tire in the vehicle width direction when the lateral force is input.
[0013]
When the maximum width position of the carcass is less than 0.4 H from the center of the bead core, the internal pressure tension near the bead reinforcement layer is lowered, and the rigidity of the portion is lowered, which is not preferable for the above deformation.
[0014]
On the other hand, when the maximum width position of the carcass exceeds 0.6H from the center of the bead core, the tension from the belt end vicinity to the side upper end portion (buttress portion) is lowered, which is not preferable in terms of rigidity with respect to generation of lateral force.
[0015]
Therefore, the maximum width position of the carcass measured along the tire radial direction from the center of the bead core is set to 0.4 to 0.6H.
[0016]
In order to increase the tension of the carcass, when the center of curvature is inside the tire in the shape when the internal pressure of 10% of the specified internal pressure is filled, the radius of curvature Rb is set large and the radius of curvature Rb is infinite. That is, it is preferable to approximate a linear shape.
[0017]
Further, it is more preferable that the center of curvature is provided on the outer side of the tire and the outer side of the tire has a concave shape. In this case, the radius of curvature Rb is preferably smaller.
[0018]
The specified internal pressure here is the air pressure corresponding to the maximum load (maximum additional capacity) of a single wheel at the applicable size described in the following standard, and the normal rim is the application described in the following standard. Standard rim in size (or “Approved Rim”, “Recommended Rim”).
[0019]
The standard is determined by an industrial standard effective in the region where the tire is produced or used. For example, in the United States, “The Tire and Rim Association Inc. Year Book”, in Europe “The European Tire and Rim Technical Organization Standers Manual”, and in Japan, the Japan Automobile Tire Association “JATMA Year Book” It is prescribed.
[0025]
Claim 2 The invention includes a pair of left and right bead portions in which bead cores are embedded, a carcass whose ends are wound up around the bead portions and straddling from one bead portion to the other bead portion, and an outer side in the tire width direction of the carcass A pneumatic tire including a sidewall portion provided on a belt, a belt provided on a crown portion of the carcass, and a tread portion provided on an outer side in a tire radial direction of the belt, the tire being assembled to a regular rim and having a specified internal pressure The shape of the carcass in the cross section in the width direction when 10% of the internal pressure is filled is measured along the tire radial direction from the center of the bead core at least on the side portion side located on the inner side in the vehicle width direction when the vehicle is mounted. The carcass of the carcass measured along the tire radial direction from the center of the bead core when the maximum height of the carcass is H. The range from the maximum width position to the end of the belt when the large position is 0.4 to 0.6H and the radius of curvature of the carcass at the maximum width position is Ra having the center of curvature inside the tire In the carcass, an arc portion having a curvature center on the inside of the tire formed with a curvature radius Rb larger than the curvature radius Ra on the inner side of the virtual extension line of the arc portion of the curvature radius Ra, or a center of curvature on the outer side of the tire. An arc portion having a radius of curvature Rc larger than the radius of curvature Ra is formed in the carcass on the bead portion side portion from the maximum width position on the inner side of the virtual extension line of the arc portion of the radius of curvature Ra. An arc portion having a center of curvature is provided on the inner side of the tire, or an arc portion having a center of curvature is provided on the outer side of the tire.
[0026]
Claim 2 According to the pneumatic tire of the present invention, the carcass from the maximum width position of the carcass to the bead portion side has a center of curvature on the inner side of the carcass on the side portion side located on the inner side in the vehicle width direction when the vehicle is mounted. An arc portion having a center of curvature inside the tire and having a center of curvature outside the tire, or a center of curvature outside the tire, is formed with a radius of curvature Rb larger than the radius of curvature Ra so that the virtual extension line of the arc of the radius of curvature Ra is located inside the tire. Since an arc portion is provided, when a regular internal pressure is filled, an arc portion having a center of curvature inside the tire formed with a radius of curvature Rb or an arc portion having a center of curvature outside the tire is formed with a radius of curvature Ra. The amount of bulging becomes larger than that of the circular arc portion, and the tension of the carcass is increased to increase the rigidity.
[0027]
Further, the carcass on the bead side from the maximum width position of the carcass is formed with a curvature radius Rc larger than the curvature radius Ra so as to be located inside the tire of the virtual extension line of the arc of the curvature radius Ra at the maximum width position. Since an arc portion having a center of curvature is provided on the inner side of the tire or an arc portion having a center of curvature is provided on the outer side of the tire, an arc having the center of curvature on the inner side of the tire formed with a radius of curvature Rc when filled with a normal internal pressure. A portion or an arc portion having a center of curvature on the outer side of the tire has a larger bulge amount than an arc portion formed with a curvature radius Ra, and the tension near the bead portion increases to increase the rigidity.
[0028]
Thereby, it is possible to suppress the lifting of the inner portion of the tire in the vehicle width direction when the lateral force is input.
[0029]
When the maximum width position of the carcass is less than 0.4 H from the center of the bead core, the internal pressure tension near the bead reinforcement layer is lowered, and the rigidity of the portion is lowered, which is not preferable for the above deformation.
[0030]
On the other hand, when the maximum width position of the carcass exceeds 0.6H from the center of the bead core, the tension from the belt end vicinity to the side upper end portion (buttress portion) is lowered, which is not preferable in terms of rigidity with respect to generation of lateral force.
[0031]
Therefore, the maximum width position of the carcass measured along the tire radial direction from the center of the bead core is set to 0.4 to 0.6H.
[0032]
In order to increase the tension of the carcass, when the center of curvature is inside the tire in the shape when the internal pressure of 10% of the specified internal pressure is filled, the radius of curvature Rb is set large and the radius of curvature Rb is infinite. That is, it is preferable to approximate a linear shape.
[0033]
Further, it is more preferable that the center of curvature is provided on the outer side of the tire and the outer side of the tire has a concave shape. In this case, the radius of curvature Rb is preferably smaller.
[0034]
Claim 3 The invention of Claim 1 or claim 2 In this pneumatic tire, each bead portion is provided with a bead reinforcement layer, and the bead reinforcement layer of the bead portion located on the inner side of the vehicle mounting has higher rigidity than the bead reinforcement layer of the bead portion located on the outer side of the vehicle mounting. It is characterized by that.
[0035]
According to this configuration, the bead portion located on the inner side of the vehicle mounting is more rigid than the bead portion positioned on the outer side of both mountings, and lifting of the inner portion in the vehicle width direction when the tire is mounted on the vehicle can be further suppressed.
[0036]
In addition, when increasing the rigidity by arranging reinforcement on the side of the tire, avoid placing a reinforcing layer in the region from the vicinity of the maximum width position where the bending deformation at the time of contact is large to the belt end from the viewpoint of durability. Many. For this reason, the reinforcement by the reinforcing layer is set near the bead portion, and the side portion on the belt side from the vicinity of the maximum width position increases the tension of the carcass as described above, thereby achieving rigidity.
[0037]
Claim 4 The invention of Claim 1 or claim 2 This pneumatic tire is characterized in that the outer side in the vehicle width direction and the inner side in the vehicle width direction are symmetrical with respect to the tire equatorial plane.
[0038]
By making the vehicle width direction outer side and the vehicle width direction inner side symmetrical with respect to the tire equatorial plane, the rigidity of the vehicle width direction outer part of the tire can be increased similarly to the rigidity of the vehicle width direction inner part, The deformation due to the lateral force is suppressed, and there is a further effect as compared with the case where the rigidity of only the inner portion in the vehicle width direction is increased.
[0039]
Claim 5 The pneumatic tire unit has a symmetrical structure for the left and right wheels with respect to the center line in the vehicle width direction. The method according to any one of claims 1 to 3. It is characterized by comprising a pair of pneumatic tires.
[0040]
According to this configuration, since the pneumatic tire for the left wheel and the pneumatic tire for the right wheel have a symmetrical structure with respect to the center line in the vehicle width direction, when the pneumatic tire for the left wheel is mounted on the vehicle, The rolling characteristics attributed to the structure and the rolling characteristics attributed to the structure of the pneumatic tire for the right wheel are offset, and the straight traveling performance of the vehicle can be maintained. Similarly, since the turning performance of the vehicle can be maintained, the course correction performance by steering is not impaired, and the stability during turning of the vehicle can be maintained.
[0041]
Claim 6 How to install a pneumatic tire Claim 5 The pneumatic tire unit is mounted on a vehicle.
[0042]
Claim 6 In this pneumatic tire mounting method, since the pneumatic tire having a symmetrical structure for the left wheel and the right wheel with respect to the center line in the vehicle width direction is mounted on the vehicle, this is caused by the structure of the pneumatic tire for the left wheel. The rolling characteristics and the rolling characteristics resulting from the structure of the pneumatic tire for the right wheel are offset, and the straight traveling performance of the vehicle can be maintained. Similarly, since the turning performance of the vehicle can be maintained, the course correction performance by steering is not impaired, and the stability during turning of the vehicle can be maintained.
[0043]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the pneumatic tire of the present invention will be described with reference to FIGS.
[0044]
FIG. 2 shows a cross section of the left-wheel pneumatic tire 10A. FIG. 1 shows a left-wheel pneumatic tire 10A (hereinafter abbreviated as “left tire 10A”) and a right-wheel pneumatic tire 10A. (Hereinafter, abbreviated as “right tire 10B”).
[0045]
In the present embodiment, the left tire 10A and the right tire 10B have a left-right symmetrical structure with respect to the center line in the vehicle width direction when the vehicle is mounted, and therefore the details of the left tire 10A will be described below as a representative.
[0046]
In the bead portion 12 of the left tire 10A, a one-ply carcass ply 14 is folded around the bead core 18 from the tire inner side to the outer side.
[0047]
The carcass ply 14 includes an organic fiber cord such as a polyester cord or a nylon cord arranged in a radial arrangement, and is reinforced between the bead cores 18.
[0048]
A bead filler 16 extending from the bead core 18 to the outer side in the tire radial direction is embedded between the upper portion 14A of the carcass ply 14 and the main body portion 14B.
[0049]
When the left tire 10A is mounted on the vehicle, a reinforcing layer 28A is disposed on the inner surface of the upper portion 14A of the bead portion 12A located on the inner side of the vehicle, and the upper portion 14A of the bead portion 12B located on the outer side of the vehicle. A reinforcing layer 28B is disposed on the inner surface.
[0050]
The reinforcing layer 24A and the reinforcing layer 24B have a structure in which a plurality of organic fiber cords or steel cords are arranged in parallel and covered with rubber.
[0051]
Here, the reinforcement layer 28A positioned on the vehicle mounting inner side is set to have a larger bead portion deformation suppressing action than the reinforcing layer 28B positioned on the vehicle mounting outer side.
[0052]
In order to make the deformation suppressing action different as described above, at least one of the width of the reinforcing layer 24A and the reinforcing layer 24B, the rigidity (thickness and material) of the cord, the number of cords to be driven, the angle (direction) of the cord, and the number of layers. This can be done by changing one.
[0053]
A sidewall portion 24 is formed on the outer side of the carcass ply 14 in the tire width direction.
[0054]
A belt 20 is disposed outside the carcass ply 14 in the tire radial direction. The belt 20 is composed of two or more steel cord crossing layers.
[0055]
A wide spiral wound layer 21 (so-called cap layer 21) of an organic fiber cord, for example, nylon cord is disposed on the outer periphery of the belt 20, and a narrow spiral spiral layer of, for example, nylon cord is disposed on the outer periphery of the end of the cap layer 21. 23 (so-called layer layer 23) is provided.
[0056]
A tread rubber 22 that is continuous in a toroid shape is disposed between the sidewall portions 24.
[0057]
Here, in the left tire 10A of the present embodiment, the shape of the carcass ply 14 in the cross section in the width direction when it is assembled to a normal rim and filled with an internal pressure of 10% of the specified internal pressure is inward in the vehicle width direction when the vehicle is mounted. On the side of the side wall portion 24 that is positioned, it is defined as follows.
[0058]
First, when the maximum height of the carcass ply 14 measured along the tire radial direction from the center of the bead core 18 is H, the maximum width position P of the carcass ply 14 measured along the tire radial direction from the center of the bead core 18. The dimension up to is 0.4 to 0.6H.
[0059]
Further, when the radius of curvature of the carcass ply 14 at the maximum width position P is Ra (the center of curvature is inside the tire), the carcass ply 14 has a radius of curvature Ra in the range from the maximum width position P to the end of the belt 20. And an arc portion that is located inside the tire along a virtual extension line (illustrated by a dotted line) of the arc portion and is formed with a curvature radius Rb that is larger than the curvature radius Ra.
[0060]
Further, on the bead portion 12 side from the maximum width position P, the carcass ply 14 is formed with a radius of curvature Rc that is positioned inside the tire of a virtual extension line (illustrated by a dotted line) of an arc having a radius of curvature Ra and is larger than the radius of curvature Ra. It has an arc portion.
[0061]
In the present embodiment, the shape of the carcass ply 14 on the side of the sidewall portion 24 that is located on the outer side in the vehicle width direction when the vehicle is mounted deviates from the above definition. For example, there is a curvature on both sides of the maximum width position P. This is a general shape having an arc portion formed with a radius of curvature smaller than the radius Ra.
(Function)
In the left tire 10A of the present embodiment, the reinforcement layer 28A is disposed on the bead portion 12A located on the inner side of the vehicle, and the reinforcement layer 28B is disposed on the bead portion 12B located on the outer side of the vehicle. The deformation of 12B is suppressed. Since the reinforcing layer 28A located on the vehicle inner side has higher rigidity than the reinforcing layer 28B located on the vehicle outer side, the bead portion 12A relatively located on the vehicle inner side is located on the vehicle outer side. Deformation is suppressed more than 12B.
[0062]
Further, when the shape of the carcass ply 14 is assembled in the normal rim and filled with an internal pressure of 10% of the specified internal pressure, the maximum width is within the range from the maximum width position P to the end of the belt 20 when viewed in the cross section in the width direction. Since the arc portion formed with the curvature radius Rb larger than the curvature radius Ra is provided so as to be located inside the tire of the virtual extension line of the arc of the curvature radius Ra at the position P, when a prescribed internal pressure is filled, The arc portion formed with the radius of curvature Rb has a larger bulge amount (in FIG. 1, bulges from the dotted line position to the solid line position) than the arc portion formed with the curvature radius Ra, and the tension increases. And rigidity increases.
[0063]
Further, on the bead portion 12 side from the maximum width position P, an arc formed with a curvature radius Rc larger than the curvature radius Ra so as to be located inside the tire of the virtual extension line of the arc of the curvature radius Ra at the maximum width position P. When the specified internal pressure is filled, the arc portion formed with the curvature radius Rc bulges more than the arc portion formed with the curvature radius Ra (in FIG. 1, from the position of the dotted line to the solid line). Bulges to the position.) Increases, tension increases and rigidity increases.
[0064]
That is, the rigidity of the carcass ply 14 is increased on both sides of the maximum width position P, and the rigidity of the sidewall portion 24 is increased.
[0065]
Here, when the vehicle turns, a lateral force SF is generated in the left tire 10A and the right tire 10B.
[0066]
Specifically, when the vehicle turns to the right, as shown in FIG. 3, a lateral force SF acts on the left tire 10A from the outside of the vehicle to the inside.
[0067]
When a lateral force SF is applied to the left tire 10A, the bead portions 12A and 12B rotate and deform around the bead cores 18A and 18B in accordance with the lateral force deflection of the sidewall portion 24 of the left tire 10A, and rotate to the left as viewed from the rear of the vehicle (see FIG. 3 in the direction of arrow A).
[0068]
For this reason, as shown in FIG. 4, the vehicle inner side portion of the left tire 10 </ b> A to which a particularly large lateral force SF acts tends to lift from the road surface as indicated by a dotted line.
[0069]
However, in the left tire 10A of the present embodiment, the rigidity of the sidewall portion 24 inside the vehicle is improved by optimizing the cross-sectional shape of the carcass ply 14, and the rigidity of the bead portion 12A inside the vehicle is relatively improved. As a result, deformation of the bead portion 12A and the side wall portion 24 inside the vehicle when the lateral force SF is input is suppressed, and lifting of the vehicle inner portion when turning right is effectively prevented. Accordingly, it is possible to prevent the generation efficiency of the lateral force SF from being lowered.
[0070]
It should be noted that not only the bead portion 12A and the sidewall portion 24 inside the vehicle, but also the bead portion 12B and the sidewall portion 24 in the vehicle outer portion have the same configuration, and if the rigidity is increased, the bead portion 12A and the sidewall portion 24 inside the vehicle. As compared with the case where only the rigidity is increased, the effect becomes higher.
[0071]
Needless to say, similar effects can be obtained with the right tire 10B. By the way, in the right tire 10B, as shown in FIG. 3, the bead portion 12C and the bead portion 12D are rotationally deformed in the direction of arrow B when turning left, and the vehicle inside tends to float up. Further, since the rigidity of the side wall portion 24 is set to be larger than the rigidity of the bead portion 12D and the side wall portion 24 on the vehicle outer side, lifting of the vehicle inner side portion is effectively prevented.
[0072]
Further, by mounting the left tire 10A and the right tire 10B symmetrically on the vehicle, the rolling characteristics caused by the structure of the left tire 10A and the rolling characteristics caused by the structure of the right tire 10B can be offset, and the vehicle Can be kept straight.
[0073]
Furthermore, since the turning performance of the vehicle can be maintained, the course correction performance by steering is not impaired, and the stability during turning of the vehicle can be maintained.
[0074]
The shape of the carcass ply 14 in the cross section in the width direction when it is assembled to a regular rim and filled with an internal pressure of 10% of the specified internal pressure is the same as that of the side wall portion 24 located outside the vehicle width direction when the vehicle is mounted. It may be the same as that on the side of the side wall portion 24 located on the inner side in the vehicle width direction at the time of mounting (that is, the shape of the carcass ply 14 is made symmetrical with respect to the tire equatorial plane CL).
[0075]
Further, when the center of curvature of the arc portion of the radius of curvature Rb of the carcass ply 14 is inside the tire, or when the center of curvature of the arc portion of the radius of curvature Rc of the carcass ply 14 is inside the tire, In order to increase, it is preferable that the curvature radius Rb and the curvature radius Rc are larger. The tension at the time of internal pressure filling can be increased when the center of curvature of the arc portion of the carcass ply 14 is on the outer side of the tire than on the inner side of the tire, and the center of curvature of the arc portion of the radius of curvature Rb of the carcass ply 14 is on the outer side of the tire. In some cases, when the center of curvature of the arc portion of the radius of curvature Rc of the carcass ply 14 is on the outer side of the tire, it is preferable that the radius of curvature Rb and the radius of curvature Rc are smaller in order to increase the tension during filling with internal pressure.
(Test example)
Next, test examples will be described.
[0076]
In order to confirm the effect of the present invention, one type of tire of a comparative example and four types of tires of examples to which the present invention was applied were prepared, side forces were measured, and a linear stability test was performed.
[0077]
The test tire was a pneumatic tire for passenger cars having a size of 235 / 45ZR17. The carcass ply uses two plies of polyester cords of 1000D / 2, and the belt is composed of two layers of 1 × 5 steel cord crossing layers inclined at an angle of 22 ° with respect to the tire equator plane, and 1260D / 2 nylon cord cap layers and 1260 D / 2 nylon cord layer layers were used.
[0078]
The reinforcing layer includes a plurality of nylon cords inclined at an angle of 45 ° with respect to the tire radial direction.
[0079]
The table of FIG. 5 shows the radius of curvature (Ra, Rb, Rc) of the carcass ply, the maximum width position of the carcass, the width of the reinforcing layer, and the number of reinforcing layers in the comparative example and Examples 1 to 4. . Note that a minus value in the numerical value of the radius of curvature indicates that the center of curvature is outside the tire when the internal pressure is 10% of the specified internal pressure, that is, the outside of the tire has a concave shape.
[0080]
The value of the lateral force SF shown in the table of FIG. 5 is that a load of 4459 N, which is 70% of the specified maximum load capacity (6370 N), is obtained after assembling the tire on an 8JJ rim and filling the specified internal pressure of 235,000 Pa. Using a flat belt testing machine with a safety walk attached, the speed is 50 km / h, and the tire input direction is input to the tire under the condition that the deviation SA (slip angle) between the traveling direction and the rotating surface is 1 °. This is a value obtained by measuring the force SF.
[0081]
When the measurement result of the tire according to the invention is expressed as an index when the lateral force SF = 1770N in the conventional tire is set to 100, an increase in the lateral force SF is recognized in the tire to which the present invention is applied.
[0082]
Further, the tires of the comparative example and Examples 1 to 4 were used as test tires, and these tires were mounted on a test vehicle of a 2500 CC rear wheel drive vehicle (domestic sports type passenger vehicle), and the speed was measured by two passengers including the test driver. A straight run, a lane change run, etc. were carried out in the range of 60 to 120 km / h, and a feeling evaluation was performed by summarizing each run result.
[0083]
The performance evaluation was performed with the tire of the comparative example as a control tire and was evaluated with a maximum of 10 points, and the tires of Examples 1 to 4 were expressed as ± 10-level numerical values in comparison with the tire of the comparative example. Note that the larger the value on the plus side, the better the performance.
[0084]
From this result, it was recognized that the straight-line stability of each tire of the example was greatly improved.
[0085]
【The invention's effect】
According to the pneumatic tire, the pneumatic tire unit, and the pneumatic tire mounting method of the present invention, the turning performance is improved, and straight running stability, particularly straight running stability at high speed running, is hindered even when affected by disturbance. It has an excellent effect that there is nothing.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a pneumatic tire for a left wheel according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing an inner carcass line when the vehicle is mounted.
FIG. 3 is a cross-sectional view of a pneumatic tire for a left wheel and a right wheel.
FIG. 4 is a cross-sectional view of a tire for explaining deformation of the tire when a lateral force is input.
FIG. 5 is a table showing test tire specifications and test results.
[Explanation of symbols]
10 Pneumatic tire
12 Beads
14 Carcass ply (Carcass)
18 Beadcore
20 belts
22 Tread rubber (tread part)
24 Side wall
28 Reinforcement layer (bead reinforcement layer)
P Maximum width position

Claims (6)

A pair of left and right bead portions in which bead cores are embedded, a carcass whose end is wound up on the bead portion and straddles in a toroidal form from one bead portion to the other bead portion, and a side provided on the outer side in the tire width direction of the carcass A pneumatic tire comprising a wall portion, a belt provided on a crown portion of the carcass, and a tread portion provided on the outer side in the tire radial direction of the belt,
The shape of the carcass in the cross-section in the width direction when it is assembled to a regular rim and filled with an internal pressure of 10% of the specified internal pressure is at least on the side portion side located on the inner side in the vehicle width direction when the vehicle is mounted.
When the maximum height of the carcass measured along the tire radial direction from the center of the bead core is H, the maximum width position of the carcass measured along the tire radial direction from the center of the bead core is 0.4 to 0.4. 0.6H,
When the radius of curvature of the carcass at the maximum width position is Ra having the center of curvature inside the tire, the carcass in the range from the maximum width position to the end of the belt has an arc portion with a radius of curvature Ra. An arc portion having a center of curvature inside the tire and an arc portion having a center of curvature outside the tire, which is formed with a radius of curvature Rb larger than the radius of curvature Ra, is provided inside the tire of the virtual extension line. Pneumatic tires. A pair of left and right bead portions in which bead cores are embedded, a carcass whose end is wound up on the bead portion and straddles in a toroidal form from one bead portion to the other bead portion, and a side provided on the outer side in the tire width direction of the carcass A pneumatic tire comprising a wall portion, a belt provided on a crown portion of the carcass, and a tread portion provided on the outer side in the tire radial direction of the belt,
The shape of the carcass in the cross-section in the width direction when it is assembled to a regular rim and filled with an internal pressure of 10% of the specified internal pressure is at least on the side portion side located on the inner side in the vehicle width direction when the vehicle is mounted.
When the maximum height of the carcass measured along the tire radial direction from the center of the bead core is H, the maximum width position of the carcass measured along the tire radial direction from the center of the bead core is 0.4 to 0.4. 0.6H,
When the radius of curvature of the carcass at the maximum width position is Ra having the center of curvature inside the tire, the carcass in the range from the maximum width position to the end of the belt has an arc portion with a radius of curvature Ra. An arc portion having a center of curvature inside the tire formed with a radius of curvature Rb larger than the radius of curvature Ra is provided inside the tire of the virtual extension line, or an arc portion having a center of curvature outside the tire, and from the maximum width position. In the carcass of the bead portion side portion, an arc portion having a center of curvature inside the tire formed with a radius of curvature Rc larger than the radius of curvature Ra inside the virtual extension line of the arc portion of the radius of curvature Ra, or A pneumatic tire characterized in that an arc portion having a center of curvature is provided on the outer side of the tire. Each bead portion is provided with a bead reinforcement layer, and the bead reinforcement layer of the bead portion located on the inner side of the vehicle mounting has higher rigidity than the bead reinforcement layer of the bead portion located on the outer side of the vehicle mounting. The pneumatic tire according to claim 1 or 2 . The pneumatic tire according to claim 1 or 2, wherein the outer side in the vehicle width direction and the inner side in the vehicle width direction are symmetrical with respect to the tire equatorial plane. A pneumatic tire comprising a pair of pneumatic tires according to any one of claims 1 to 3 , wherein the left and right wheels are symmetrical with respect to a vehicle width direction center line. unit. A pneumatic tire mounting method according to claim 5, wherein the pneumatic tire unit is mounted on a vehicle.

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