JPH0592708A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve the riding comfortableness while maintaining the practicable traveling performance of the steering stability or the like. CONSTITUTION:The vibration transmission ratio of a side wall part 3a to be set to a wheel offset side of a rim (R) (where the wheel offset side means the side where the distance between a rim end part and a disc connecting point is shorter in the case where a disc part (D) is offset the center (C) of the rim width) is set smaller than that of the side wall part 3b to be set on the wheel counter-offset side, in a pneumatic tire fitted to a wheel (W) where the connecting position of the disc part (D) relative to the rim (R) is offset the center (C) of the rim width.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire which improves riding comfort without substantially lowering driving performance such as steering stability.

[0002]

2. Description of the Related Art Recent pneumatic tires are required to have further improved riding comfort as well as running performance such as steering stability. The riding comfort of this tire is represented by the impact value and noise level of the vibration that is brought into the vehicle from the road surface through the tire.The transmission path of the vibration to the vehicle is the tread portion of the tire, It is designed to be transmitted to the vehicle body through the side wall, the left and right beads, and the rim / disc.

For this reason, a conventional general method for improving riding comfort has been to reduce the rigidity of both sidewall portions and reduce the restoring force of external force received from the road surface. However, if the rigidity of both sidewall portions is reduced in this way, the problem that the traveling performance such as steering stability is deteriorated accordingly cannot be avoided. on the other hand,
Along with the front wheel drive (FF) of vehicle drive systems and the expansion of vehicle interior space in recent years, the asymmetric structure that maximizes the back side space of the wheel structure has progressed, and the connection position of the disc part to the rim from the rim width center There is a tendency to gradually increase the amount of change that offsets the wheel front side. The present inventors, while investigating the relationship between such asymmetric structure of the wheel and vibration transmission of the tire, found that there is a strong correlation between the two. That is, when the vibration transmissibility transmitted from the sidewall portions on the left and right sides of the tire to both rim ends of the wheel having an asymmetric structure is examined, the transmissibility passing through the rim end on the wheel front side (disc portion offset side) is measured on the back side of the wheel (disc portion reverse side). It was found that it was larger than the transmissibility through the rim end (on the offset side), and this tendency became larger as the offset change amount became larger.

The present invention described below is based on the above-mentioned new knowledge, and by devising the structure of the pneumatic tire, the riding comfort is substantially reduced without substantially lowering the running performance such as steering stability. It is intended to improve.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a pneumatic tire which improves riding comfort while substantially maintaining driving performance such as steering stability.

[0006]

According to the present invention to achieve the above object, a pneumatic tire mounted on a wheel in which a connecting position of a disc portion to a rim is offset from a rim width center is set on an offset side of the rim. It is characterized by having an asymmetric structure in which the vibration transmissibility of the side wall portion to be formed is smaller than that of the side wall portion set on the anti-offset side.

Here, the offset side means the side where the distance between the rim end and the disc connecting point is shorter when the disc portion is offset from the center of the rim width, and the anti-offset side means the rim. The side with the longer distance between the end and the disc connection point. In this way, the structure of the front and back sidewalls has a structure in which the vibration transmissibility is relatively reduced on the side that is mounted on the rim end of the wheel front side (offset side) where the vibration transmissibility is large. It is possible to reduce the amount of vibration transmitted to the vehicle body via the vehicle and improve riding comfort. On the other hand, behind the wheel (anti-offset side)
If the rigidity of the sidewall portion attached to the rim end is the same as or higher than that of the conventional one, the running performance such as steering stability is not substantially reduced.

In the present invention, the vibration transmissibility is the ratio of the axial reaction force in the same direction as the input force to the force when the front side shoulder and the back side shoulder are respectively randomly excited in the direction normal to the outer circumference of the tire, that is, the axial reaction force. / The input is measured and the overall value up to 400 Hz is determined, which is defined as the vibration transmissibility. At this time, the offset amount of the wheel desk surface is 0 mm, and the wheel whose cross-sectional shape is symmetrical is used.

In the present invention, the magnitude of the vibration transmissibility can be typically represented by the magnitude of the rigidity, and the vibration transmissibility can be made smaller as the structure becomes less rigid. It can also be expressed by the magnitude of the vibration damping rate, and the vibration transmissibility can be reduced as the structure has a larger vibration damping rate. The present invention will be specifically described below with reference to the drawings. In FIG. 1, W is a wheel mounted on the axle O, and T is a tire of the present invention mounted on the wheel W. The wheel W has a disc portion D and a rim R, and has a non-symmetrical structure in which a connecting portion P of the disc portion D to the rim R is offset from the rim width center C to the wheel front side A by a distance e.

In the pneumatic tire T, left and right sidewall portions 3a, 3b are attached to the rim R via bead portions 4a, 4b. The side wall portions 3a and 3b are structured to have different vibration transmissibility on the left and right sides, and the side wall portion 3a mounted on the front side A of the wheel has a rear side B of the wheel.
The vibration transmissibility is smaller than that of the sidewall portion 3b attached to the.

Such an asymmetric structure in which the left and right vibration transmissivities are different from each other is, for example, as shown in FIG. 2, the carcass layer 2 and the inner liner layer on the side of the sidewall 3a mounted on the rim end of the wheel front side A. 5, the tie rubber layer 6 is interposed between the tie rubber layer 6 and the tie rubber layer 6, and the damping property thereof is made larger on the side wall portion 3a side than on the side wall portion 3b side of the wheel back side B.

As described above, in the pneumatic tire T mounted on the asymmetric wheel W, the vibration is transmitted from the road surface to the vehicle body as follows. That is, as shown in FIG. 1, the vibration caused by the unevenness of the road surface E is transmitted from the tread portion 1 of the tire T to both end portions of the rim R of the wheel W through the left and right side wall portions 3a and 3b, and then to the disc. Axle O through connecting portion P with portion D and disk portion D
Be transmitted to. However, as described above, the disc portion D
In the tire T mounted on the wheel W in which the connecting portion P with respect to the rim R is largely offset from the rim width center C to the wheel front side A, the vibration from the road surface E is preferentially connected via the side wall portion 3a side. It is transmitted to the portion P and is reduced on the side wall portion 3b side. However, since the vibration transmissibility is small on the side of the side wall portion 3a where the amount of vibration transmission is large, the amount of vibration transmission is reduced, and as a result, riding comfort is improved. On the other hand, since the rigidity on the side wall portions 3a and 3b side is the same as that of the conventional tire, running performance such as steering stability can be maintained.

The configuration in which the vibration transmissibility is asymmetrical is not limited to that shown in FIG. 2, but the rubber composition constituting the sidewall portion may be varied, or the number and type of the reinforcing layers may be varied. Obtainable. For example, the bead filler 7a on the A side can be made smaller than before, and the bead filler 7b on the B side can be made larger by that amount. In this case as well, the rigidity of the A side is reduced, so that the vibration transmissibility is reduced and the riding comfort is improved. Further, although the rigidity on the A side is reduced, the rigidity on the B side is increased, so that steering stability can be maintained.

The tire of the above-mentioned asymmetric structure of the present invention is
In order to achieve the desired effect by combining with the wheel of asymmetric structure, which side should be mounted on the front side of the rim (front side of the wheel) and the rim offset amount of the matching wheel are displayed on the side wall surface. Is desirable. For example, ““ Front side when mounted ”, compatible rim offset: 30 to 40 mm”, ““ SIDE FA
CING OUTWARDS, RIM OFFSET:
"30-40 mm""is displayed. Character size and shape are arbitrary, but in the case of convex characters 0.3-
Approximately 6 mm so that it protrudes from the tire surface, in the case of concave characters, it is engraved at a depth of 0.3 to 1 mm, or the one with the displayed characters transferred to a rubber sheet is attached to a grin tire and integrated during vulcanization You can also do it. Also, from the tire surface
It is also possible to provide a platform with a protrusion of about 3 mm and to display convex characters or concave characters on it.

[0015]

EXAMPLES The following two types of tires of the present invention and comparative tires were manufactured. These tire sizes have the same P
175 / 70R13. The tire of the present invention: A tie rubber layer having a thickness of 1.2 mm is provided on the entire circumference of the tire over a width of 85 mm between the carcass layer and the inner liner layer on the tire inner surface corresponding to one side of the sidewall portion, and the side provided with the tie rubber layer. A tire having the structure shown in FIG. 2 in which the vibration transmissibility of the wall portion side is 100 and the vibration transmissibility of the sidewall portion side where the tie rubber layer is not provided is 105. Comparative tire: except that tie rubber layers were not arranged on both sides of the left and right sidewall parts and the vibration transmission rate was set to 105,
The tire has the same structure as the tire of the present invention.

Each of these two types of tires was rim-assembled to an asymmetric wheel (rim size: 13 × 5JJ, rim offset amount: 35 mm), and the following protrusion passing test was conducted.
An actual vehicle road noise test and steering stability test were conducted. Table 1 shows the results of the bump overriding test and the steering stability test, and FIG. 3 shows the results of the actual vehicle road noise test. In these tests, the tire of the present invention was mounted on the wheel so that the side wall portion side not provided with the tie rubber layer was located on the back side of the wheel. Overhang test : Air pressure 2.0 kg / cm ² , load 2
A running test was performed on a drum having a drum diameter of 1707 mm provided with a protrusion of 5 mm under the conditions of 00 kg and a speed of 50 km / hr, and the difference between the maximum value and the minimum value of the front-back impact force (kgf) at that time (this The larger the difference, the worse the riding comfort). The evaluation results are shown by an index with the value of the comparative tire as a reference (100). The smaller the index value, the better the riding comfort.

Actual vehicle road noise test : tire internal pressure 2.0
A FF vehicle with a displacement of 1600 cc / kg / cm ² and a microphone placed at the ear position on the window side of the driver's seat in the passenger compartment when traveling on a rough road surface at a speed of 50 km / hr, and the sound pressure [dB (A )] Was measured and evaluated. FIG. 3 shows the result of the 1/3 octave analysis. The larger the value of this sound pressure, the more noisy the passenger compartment is and the more remarkable the noise is. Steering stability test : A slalom test road in which pylons are set up at regular intervals is run by the same vehicle as in the actual vehicle road noise test. Steering stability is evaluated by the average speed, and the value of a comparative tire is used as a standard (100 ). The larger the index value, the better the steering stability.

[0018] From Table 1, the tires of the present invention have a significantly reduced impact force in the front-rear direction when riding over protrusions as compared with the comparative tires, and although they have excellent riding comfort, there is substantially no difference in steering stability. I understand. Further, from FIG. 3, the tire of the present invention has a lower sound pressure level in substantially the entire frequency band than the comparative tire.

[0019]

According to the present invention, in the structure of the left and right sidewall portions, the side where the rim end on the wheel front side (offset side) having a large vibration transmission rate is mounted has a relatively small vibration transmission rate, and the vibration is reduced. Since the damping rate is increased, the amount of vibration transmitted from the tire to the vehicle body via the wheel can be reduced, and riding comfort can be improved. On the other hand, since both tires have the same rigidity in both sidewall portions, driving performance such as steering stability is not substantially reduced.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an example of a tire of the present invention mounted on an asymmetric disc wheel.

FIG. 2 is a schematic cross-sectional view showing an example of the tire of the present invention.

FIG. 3 is a graph showing a relationship between frequency (Hz) and sound pressure (dB) in an actual vehicle road noise test of a comparative tire.

[Explanation of symbols]

 3a, 3b Sidewall part 6 Thai rubber layer T Pneumatic tire D Disk part P Connection part C Rim width center R Rim W wheel

Claims (1)

[Claims] 1. A pneumatic tire mounted on a wheel in which a coupling position of a disc portion with respect to a rim is offset from a rim width center, and a vibration transmissibility of a sidewall portion set on a wheel offset side of the rim is defined as a wheel. A pneumatic tire with an asymmetric structure that is smaller than that of the sidewall part that is set on the anti-offset side. Here, the offset side refers to the side where the distance between the rim end and the disc connection point is shorter when the disc portion is offset from the center of the rim width, and the anti-offset side refers to the rim end. The side with the longest distance from the disk connection point.