JP2009018677A - Pneumatic tire and mounting method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of improving steering stability on both a road surface having a high friction coefficient and the road surface having a low friction coefficient. <P>SOLUTION: At least one of rubber property of a top tread at the rear wheel side and a tread pattern changes in the tire width direction, and an outside shoulder part 7 develops a high frictional force on the road surface having the low friction coefficient and an inside shoulder part 8 develops the high frictional force on the road surface having the high friction coefficient. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pneumatic tire that improves the steering stability of a vehicle, and a method for mounting a pneumatic tire.

  A pneumatic tire disclosed in Patent Document 1 is cited as a related to this type of conventional technology. In this pneumatic tire, a sipe-filled block for demonstrating on-ice performance is provided on the end side in the width direction from the main groove of the tread portion, and a non-sipe block is provided between the main grooves. It can be used continuously in summer and winter on low friction coefficient road surfaces and high friction coefficient road surfaces.

On the other hand, in Patent Document 2, a pneumatic tire having a small negative rate inside the vehicle is attached to the front wheel, and a pneumatic tire having a small negative rate outside the vehicle is attached to the rear wheel. A method is disclosed.
Japanese Patent Laid-Open No. 11-165509 JP 2002-178713 A

  However, both of the conventional techniques described above can improve the braking performance, but cannot improve the steering stability (cornering, lane change, turning characteristics, straight running stability, etc.).

  Accordingly, the present invention has been made to solve the above-described problems, and provides a pneumatic tire capable of improving steering stability on both a low friction coefficient road surface and a high friction coefficient road surface. With the goal.

  According to a first aspect of the present invention, there is provided a top tread formed on a surface of a tread portion that contacts a road surface in a vehicle-mounted state, wherein at least one of rubber physical properties and a tread pattern changes along a tire width direction, and the top tread A shoulder portion formed on each of the vehicle mounting inner side and the vehicle mounting outer side in the tire width direction, wherein the shoulder portion on the vehicle mounting inner side has a high frictional force on a road surface having a high coefficient of friction, and the shoulder portion on the vehicle mounting outer side. However, the pneumatic tire is characterized in that it exhibits a high frictional force on the road surface with a low coefficient of friction and is mounted on the rear wheel side of the vehicle.

  The invention of claim 2 is characterized in that at least one of the shape and structure of the tread portion excluding the top tread is formed asymmetrically with a center in the tire width direction as a boundary, and a conicity force is generated inward of the vehicle. The pneumatic tire according to claim 1.

  According to a third aspect of the present invention, there is provided a top tread formed on the surface of the tread portion that contacts the road surface in a vehicle-mounted state, wherein at least one of the rubber physical properties and the tread pattern changes along the tire width direction, A shoulder portion formed on each of the vehicle mounting inner side and the vehicle mounting outer side in the tire width direction, and the shoulder portion on the vehicle mounting inner side expresses a high frictional force on a road surface having a low coefficient of friction, and is on the front wheel side of the vehicle. A pneumatic tire characterized by being mounted.

The invention of claim 4
A top tread formed on the surface of the tread portion that contacts the road surface in a vehicle-mounted state and at least one of rubber physical properties and a tread pattern changes along the tire width direction, and the vehicle mounting inner side of the top tread in the tire width direction And a shoulder portion formed on each of the vehicle mounting outer sides, the vehicle mounting inner shoulder portion having a high frictional force on a road surface having a high friction coefficient, and the vehicle mounting outer shoulder portion having a low friction coefficient road surface. A pneumatic tire mounting method is characterized in that rear wheel tires that exhibit high frictional force are mounted on the rear wheel side of the vehicle.

  According to a fifth aspect of the present invention, a front wheel tire including the top tread and the shoulder portion, wherein the shoulder portion on the inner side of the vehicle expresses a high frictional force on a road surface having a low friction coefficient, is attached to the front wheel side of the vehicle. The pneumatic tire mounting method according to claim 4, wherein the pneumatic tire is mounted.

  According to the first and fourth aspects of the invention, a large lateral force is generated in the pneumatic tire on the rear wheel side during cornering or turning, or the overall steering stability is reduced by reducing the lateral force. Improvements can be made. Specifically, on the road surface with a high friction coefficient, since the road surface is difficult to slip, the shoulder portion on the inner side of the vehicle of the rear wheel side pneumatic tire expresses a high frictional force. Increase lateral force to make it more difficult to slip and improve steering stability. On the road surface with a low coefficient of friction, the road surface is slippery, and if the lateral force generated during cornering or turning is large, the vehicle behavior suddenly becomes unstable and becomes uncontrollable. Abrupt control because the shoulder on the outside of the tire wearing the tire expresses a high frictional force and the lateral force toward the outside of the vehicle is generated, thereby suppressing the lateral force toward the inside of the pneumatic tire on the rear wheel side. Avoid the impossibility and ensure the overall handling stability. As described above, it is possible to improve the steering stability on both the low friction coefficient road surface and the high friction coefficient road surface.

  In the invention of claim 2, in addition to the effect of the invention of claim 1, on the road surface with a low coefficient of friction, a concentric force directed toward the vehicle inner side of the front wheel side pneumatic tire is generated, so that the front wheel side faces the vehicle inner side. By generating the lateral force, the straight running performance can be improved by the same effect as if the toe-in was increased.

  According to the third and fifth aspects of the invention, on the road surface having a low coefficient of friction, a lateral force directed toward the inside of the vehicle is generated on the front wheel side due to the high frictional force generated by the shoulder portion on the vehicle mounting inner side on the front wheel side. Thus, straight running performance (straight running stability) can be improved by the same effect as if the toe-in was increased (or the negative camper was increased). In particular, the effect of improving the straight running performance is remarkable on snow and ice road surfaces that have a low friction coefficient and are susceptible to various disturbances.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a cross-sectional view showing a tread portion of a pneumatic tire according to a first embodiment of the present invention, FIG. 2 shows the first embodiment of the present invention, and (a) is a rear wheel side of a road surface with a high coefficient of friction. FIG. 3B is a conceptual diagram showing the lateral force applied to the pneumatic tire, FIG. 3B is a conceptual diagram showing the lateral force applied to the pneumatic tire on the rear wheel side on the road surface with a low friction coefficient, and FIG. 3 is the front wheel side according to the first embodiment. It is a conceptual diagram which shows the mounting pattern of the pneumatic tire on the rear wheel side. 2 and 3 and FIGS. 4 to 6 to be described later, the same hatching is applied to the same parts as those in the cross-sectional view of FIG. 1 for easy explanation.

  As shown in FIG. 3, the pneumatic tires 2A and 2B according to the present embodiment are mounted only on the rear wheel side of the vehicle 3, and standard pneumatic tires 1A and 1B, for example, all Seasonal type is installed. In the pneumatic tires 2A and 2B on the rear wheel side, the tread portion 4 includes the first rubber layer 5, the second rubber layer 6, the outer shoulder portion 7 (the shoulder portion on the vehicle mounting outer side), and the inner shoulder portion 8 (the vehicle). The cross section along the tire width direction of the tread portion 4 is formed in a trapezoidal shape, integrally formed from the shoulder portion on the inner side of the mounting) and the auxiliary rubber layers 9 and 10. Further, at least one of the shape and structure other than the top tread of the tread portion 4, that is, the second rubber layer 6 and the shoulder portions 7 and 8, is formed asymmetrically with respect to the center in the tire width direction. Occurs inward.

  The first rubber layer 5 is provided on the outer peripheral side of a belt (not shown). On the outer peripheral side of the first rubber layer 5, a second rubber layer 6 disposed in the center in the tire width direction and the second rubber. The outer shoulder portion 7 and the inner shoulder portion 8 are laminated on the outer side and the inner side of the layer 6 in the tire width direction, respectively. The side portions of the first rubber layer 5 and the shoulder portions 7 and 8 in the tire width direction are covered with auxiliary rubber layers 9 and 10.

  One pneumatic tire 2A is mounted on the left side of the vehicle 3, the outer shoulder portion 7 and the auxiliary rubber layer 9 are arranged on the outer side (that is, the left side), and the inner shoulder portion 8 and the auxiliary rubber layer 10 are on the inner side. (Ie right side). The other pneumatic tire 2B is mounted on the right side of the vehicle 3, and the outer shoulder portion 7 and the auxiliary rubber layer 9 are disposed on the outer side (that is, the right side), while the inner shoulder portion 8 and the auxiliary rubber layer 10 are disposed. Are arranged on the inner side (that is, on the left side).

  The outer shoulder portion 7 has at least one of a rubber property and a tread pattern that exhibits a high frictional force on a road surface (mainly winter season) with a low friction coefficient typified by a snow / ice road surface. For example, for a studless tire The outer shoulder portion 7 is formed of the foamed rubber, or a pattern having a large number of sipes is provided.

  The inner shoulder portion 8 has at least one of a rubber physical property and a tread pattern that expresses a high frictional force on a road surface (mainly summer season) with a high friction coefficient typified by a dry road surface. For example, a negative rate (groove area) The pattern has a small ratio), and in particular, when a high frictional force is extremely required, a grooveless pattern is provided.

  In the above configuration, in FIG. 2A, on the road surface having a high friction coefficient, for example, the lateral force received by the pneumatic tires 2A and 2B on the rear wheel side during cornering or turning depends on the friction coefficient of the road surface. The vehicle 3 is not slippery because it is high and firmly grips the road surface. Therefore, as long as the vehicle does not travel excessively, it travels stably under understeer conditions. Under this understeering condition, the steering stability increases when the lateral force inward of the vehicle 3 generated in the pneumatic tires 2A and 2B on the rear wheel side (especially those on the outside of the turn) is large. In the present embodiment, since the inner shoulder portion 8 of the pneumatic tire 2A mounted on the left side of the vehicle 3 exhibits a high frictional force, a relatively large lateral force F1 is generated in the right direction in FIG. Since the outer shoulder portion 7 exhibits a relatively low frictional force, a relatively small lateral force F2 is generated in the left direction in FIG. 2A. As a result, the entire tread portion 4 of the pneumatic tire 2A is directed toward the inside of the vehicle 3. Since a large lateral force is received from the road surface and the same applies to the right pneumatic tire 2B, the steering stability is good. Further, under the above-described understeer condition, a large lateral force is generated in the rear tire side pneumatic tires 2A and 2B by the force of concentricity toward the inside of the vehicle 3, so that the steering stability is also improved from this point. good.

  On the other hand, in FIG. 2B, on the road surface with a low friction coefficient, the lateral force generated in the pneumatic tires 2A and 2B on the rear wheel side during cornering or turning is relatively small and the grip on the road surface is easily lost. Therefore, there are many opportunities to travel under a situation where the vehicle changes from understeer to oversteer unless the vehicle is traveling at a low speed. Under such circumstances, it seems that it is harder to slip as the lateral force generated in the pneumatic tires 2A and 2B on the rear wheel side (especially those on the outside of the turn) increases. The vehicle behavior suddenly becomes unstable and it becomes very difficult to control the vehicle. And on the road surface with a low friction coefficient, the vehicle will immediately exceed the limit. If the lateral force generated in the pneumatic tires 2A, 2B on the rear wheel side is large, the vehicle controllability is suddenly lost during cornering or turning. It will be. Therefore, it is preferable from the viewpoint of steering stability that the lateral force generated in the pneumatic tires 2A and 2B on the rear wheel side during cornering or turning is small. In general, the rear wheel of the vehicle is often set to a negative camber in order to improve the steering stability when traveling mainly on a road surface with a high friction coefficient. In this case, when traveling on a road surface with a low friction coefficient, Since the camber thrust of the rear outer wheel (inward of the turning) is too large, the steering stability further decreases when traveling on the road surface having a friction coefficient. In the present embodiment, since the outer shoulder portion 7 of the pneumatic tire 2A mounted on the left side of the vehicle 3 exhibits a high frictional force, a relatively large lateral force F2 is generated in the left direction in FIG. On the other hand, since the inner shoulder portion 8 exhibits a relatively low frictional force, a relatively small lateral force F1 is generated in the right direction in FIG. 2B. As a result, the entire tread portion 4 of the pneumatic tire 2A faces the outside of the vehicle 3. In addition, the inward camber thrust of the pneumatic tire 2A can be suppressed and the same applies to the right pneumatic tire 2B. Therefore, the vehicle controllability after exceeding the limit as described above Can be prevented from being suddenly lost, and the handling stability can be improved.

(Second Embodiment)
FIG. 4 is a conceptual diagram showing a mounting pattern of a pneumatic tire according to the second embodiment. The pneumatic tires 1A, 1B, 2A, 2B according to the present embodiment include the same components as the pneumatic tires 1A, 1B, 2A, 2B according to the first embodiment. Therefore, the same components are denoted by common reference numerals, and redundant description is omitted.

  In the present embodiment, as shown in FIG. 4, the pneumatic tires 1 </ b> A and 1 </ b> B on the front wheel side include the inner shoulder portion 11 that expresses a high frictional force on a road surface with a low friction coefficient, and the pneumatic tires 1 </ b> A and 1 </ b> B At least one of the shape and structure other than the top tread, that is, the second rubber layer 6 and the inner shoulder portion 11 is formed asymmetrically with respect to the center in the tire width direction, and a conicity force is generated toward the inner side of the vehicle 3.

  In the above configuration, on the road surface with a low friction coefficient, the inner shoulder portion 11 of the pneumatic tires 1A and 1B on the front wheel side expresses a high frictional force, and a conicity force directed toward the inner side of the vehicle 3 is generated. Since a lateral force is generated inwardly, straight running performance (straight running stability) can be improved by the same effect as if toe-in is increased (or the negative camper is increased). In particular, the effect of improving the straight running performance is remarkable on snow and ice road surfaces that have a low friction coefficient and are susceptible to various disturbances. Steering stability can be improved.

<Example>
Using the method (c) or (d) in the example of “(Plastic, Film) Friction Coefficient Measuring Machine” described in JIS standard K7125 (1987), conventional examples, various comparative examples, and various examples of air The coefficient of friction of the tread member used for the entering tire was evaluated. FIG. 7 shows various data at that time, and FIG. 8 shows the friction coefficient measuring machine.

  In the friction coefficient measuring machine 20 shown in FIG. 8, a road surface material 22 is fixed on a table 21, a test piece 23 is placed on the road surface material 22, and the test piece 23 is driven by a sliding piece 24. The dynamic friction coefficient between the road surface material 22 and the test piece 23 is detected by measuring the force with the load cell 25. In order to measure the coefficient of friction using a 225 / 55R17 type pneumatic tire, the present applicant cut out a tread of the tire to prepare a test piece 23 of 20 mm long × 20 mm wide × 5 mm thick. An iron plate was used as the road surface material 22 with a high friction coefficient, and ice was used as the road surface material 22 with a low friction coefficient.

  In addition, in each test course on dry road surface (high friction coefficient road surface) and snow road surface (low friction coefficient road surface), conventional examples (all-season type tires), various comparative examples, and cornering of pneumatic tires of various examples. Feeling and straight running performance were evaluated with the same tire and the same test vehicle, and the score of the test driver was displayed as an index with the conventional example as a reference index (100). The larger the display index, the better the cornering feeling and straight running performance.

  In Comparative Example 1, as shown in FIG. 6 (a), the outer shoulder 7 of the pneumatic tires 2A and 2B on the rear wheel side exhibits a high frictional force on a road surface having a low friction coefficient. In Comparative Example 1, as shown in FIG. 7, cornering performance on a road surface with a low friction coefficient is improved, but a decrease in cornering performance on a road surface with a high friction coefficient is recognized, and on a road surface with a low friction coefficient. The straight running performance is only the same as the conventional example.

  In Comparative Example 2, as shown in FIG. 6B, the outer shoulder 7 of the rear tires 2A and 2B and the inner shoulder 11 of the front tires 1A and 1B have a low friction coefficient. This is a case where a high frictional force is expressed on each road surface. In Comparative Example 2, as shown in FIG. 7, the straight running performance and cornering performance on a road surface with a low friction coefficient are improved as compared with the conventional example, but a decrease in cornering performance on a road surface with a high friction coefficient is recognized.

  In Examples 1 and 2, as shown in FIGS. 3 and 4, the inner shoulder portions 8 of the pneumatic tires 2A and 2B on the rear wheel side exhibit a high frictional force on the road surface with a high friction coefficient, while the low friction coefficient is low. This is a case where the outer shoulder portion 7 of the rear wheel side pneumatic tire 2A, 2B develops a high frictional force on the road surface of the friction coefficient. In these Examples 1 and 2, as shown in FIG. 7, the cornering property was improved on both the high friction coefficient road surface and the low friction coefficient road surface. In particular, in Example 2, an improvement in straight running performance on a road surface having a low friction coefficient was also observed.

It is sectional drawing which shows the tread part of the pneumatic tire concerning 1st Embodiment of this invention. 1 shows a first embodiment of the present invention, (a) is a conceptual diagram showing lateral force applied to a pneumatic tire on a rear wheel side on a road surface with a high friction coefficient, (b) is a rear wheel side on a road surface with a low friction coefficient. It is a conceptual diagram which shows the lateral force applied to a pneumatic tire. It is a conceptual diagram which shows the mounting pattern of the pneumatic tire of the front-wheel side and rear-wheel side concerning 1st Embodiment. It is a conceptual diagram which shows the mounting pattern of the pneumatic tire of the front-wheel side and rear-wheel side concerning 2nd Embodiment of this invention. It is a conceptual diagram which shows the mounting pattern of the pneumatic tire of the front-wheel side and rear-wheel side concerning a prior art example. A comparative example is shown, (a) is a conceptual diagram showing a mounting pattern of pneumatic tires on the front and rear wheels according to Comparative Example 1, and (b) is a pneumatic on the front wheel and rear wheels according to Comparative Example 2. It is a conceptual diagram which shows the mounting pattern of a tire. Examples of the present invention are shown, and in each test course of a dry road surface (road surface with a high friction coefficient) and a snow road surface (road surface with a low friction coefficient), cornering fee of pneumatic tires of conventional examples, various comparative examples, and various examples It is a figure which shows various data at the time of evaluating a ring and rectilinear advance performance with the same tire and the same test vehicle. It is a front view which shows the friction coefficient measuring machine used when measuring the friction coefficient of a road surface.

Explanation of symbols

1A, 1B Pneumatic tire on the front wheel side 2A, 2B Pneumatic tire on the rear wheel side 3 Vehicle 4 Tread part 7 Outer shoulder part (shoulder part)
8 Inner shoulder (shoulder)
11 Inner shoulder (shoulder)

Claims (5)

A top tread formed on the surface of the tread portion that contacts the road surface in a vehicle-mounted state, wherein at least one of the rubber physical properties and the tread pattern changes along the tire width direction;
A shoulder portion formed on each of the vehicle mounting inner side and the vehicle mounting outer side in the tire width direction of the top tread,
The vehicle-mounted inner shoulder portion has a high frictional force on a road surface with a high coefficient of friction.
The shoulder part on the outside of the vehicle expresses a high frictional force on a road surface with a low coefficient of friction,
A pneumatic tire that is mounted on a rear wheel side of a vehicle.   2. The shape and structure of the tread portion excluding the top tread are formed asymmetrically with respect to the center in the tire width direction, and a conicity force is generated inward of the vehicle. Pneumatic tire. A top tread formed on the surface of the tread portion that contacts the road surface in a vehicle-mounted state, wherein at least one of the rubber physical properties and the tread pattern changes along the tire width direction;
A shoulder portion formed on each of the vehicle mounting inner side and the vehicle mounting outer side in the tire width direction of the top tread,
The shoulder portion on the inner side of the vehicle expresses a high frictional force on the road surface with a low coefficient of friction,
A pneumatic tire that is mounted on a front wheel side of a vehicle. A top tread formed on the surface of the tread portion that contacts the road surface in a vehicle-mounted state, wherein at least one of the rubber physical properties and the tread pattern changes along the tire width direction;
A shoulder portion formed on each of the vehicle mounting inner side and the vehicle mounting outer side in the tire width direction of the top tread,
The vehicle-mounted inner shoulder portion has a high frictional force on a road surface with a high coefficient of friction.
A method for mounting a pneumatic tire, characterized in that a rear tire is mounted on a rear wheel side of the vehicle in which a shoulder portion on the vehicle mounting outer side expresses a high frictional force on a road surface having a low friction coefficient. The top tread and the shoulder portion,
The method for mounting a pneumatic tire according to claim 4, wherein the shoulder portion on the inner side of the vehicle mounts a front wheel tire that expresses a high frictional force on a road surface with a low coefficient of friction on the front wheel side of the vehicle.

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