KR100808300B1 - Method for designing tread pattern of noise reduction tire - Google Patents

Abstract

A method for designing a tread pattern of a tire having low noise is provided to reduce the noise generated from the tire by controlling the frequency band through moving a shoulder longitudinal groove widthwise along a tread. In a method for designing a tread pattern of a tire, a shoulder longitudinal groove(G2) is aligned by moving the shoulder longitudinal groove widthwise of a tread so that a width of a shoulder block(B3) is different from that of a center block(B2). A location of the shoulder longitudinal groove is shifted toward the center block such that the width of the shoulder block is greater than that of the center block. A ratio of the width of the shoulder block to the width of the center block is about 1.09:1 to 1.15:1.

Description

Low noise tire tread pattern design method {METHOD FOR DESIGNING TREAD PATTERN OF NOISE REDUCTION TIRE}

1 is a diagram showing the ground pressure distribution of a smooth tire without a tread pattern.

2 is a diagram showing a stress distribution of a tire without a tread pattern.

Figure 3 is a schematic diagram of the tread pattern in tread PTN unit pitch to explain the design method of the tire tread pattern according to the present invention.

Figure 4 is a view showing the ground pressure distribution for each tire tread pattern shape according to the present invention.

FIG. 5 is a diagram illustrating sound pressure characteristics of a frequency band of 500 Hz or less according to models in FIG. 4. FIG.

FIG. 6 is a diagram illustrating sound pressure characteristics of a frequency band of 1000 Hz or higher for each model in FIG. 4. FIG.

The present invention relates to a method of designing a low noise tire tread pattern, wherein a tread of a longitudinal groove in a tire circumferential direction with little change in tread pattern shape is distributed so as to distribute the ground pressure distribution on the shoulder portion inward or outward based on the shoulder portion. The present invention relates to a method for designing a low noise tire tread pattern which enables efficient noise tuning by moving in the width direction to adjust a desired frequency band.

Generally, a pneumatic tire includes a tread, which is a part in contact with a road surface, a body ply forming a skeleton of the tire, a belt layer composed of a plurality of layers between the tread and the body ply, an inner liner for preventing air leakage, It comprises a side wall for protecting the body fly and flexible flexing movement, a shoulder portion located between the tread and the side wall, and a bead portion for mounting the tire on the rim. The tread pattern includes a plurality of tread blocks and longitudinal grooves formed in a circumferential direction of the tire between the plurality of tread blocks and the plurality of tread blocks and a horizontal groove formed in the width direction thereof.

Tires having such a structure may generate vibration and noise while driving a vehicle. There are many causes, but the frequency is mainly caused by an input force generated by the tire from the road surface. Occurs while changing

In other words, tire noise is caused by the wall vibration of tires and aerodynamic phenomena on the ground (Helm-Holtz Resonance, Air Pumping, Shack Wave). Phenomenon). For example, during the aerodynamic phenomenon, the pumping of the air expands when the compressed air exits the ground plane because it is trapped in a plurality of grooves on the ground plane in the course of repeating the tread contact with the road surface when the tire rolls. It refers to the phenomenon, and the noise caused by the expansion sound occurs.

It is known from many studies so far that noise sources below 1 kHz are mostly generated by structural vibrations of tires, and the aerodynamic phenomenon is known to be an important noise source in a frequency band of 1 kHz or more. This is because most of the resonant frequency bands of the radial tire structure for a passenger car are in the region of 1 kHz or less, while the resonant frequency due to the aerodynamic phenomenon associated with the tire tread pattern shape is 1 kHz or more.

Considering the noise transmission and low pass filter of the vehicle, the noise caused by the tire structural vibration is the primary noise control target. The generation process of noise due to tire wall vibration may be regarded as tire wall vibration (response) due to excitation force between road surfaces / tires generated during driving and radiation phenomenon (radiation) of noise due to air transfer of such vibration energy. Such tire noise vibration can be reduced by controlling the response through excitation force or tire structure change.

As a method for reducing tire pattern noise, it can be divided into two types.

First, by preventing the tire noise from being concentrated at a specific frequency and becoming a tone, the noise that is actually heard by the driver is reduced even if the noise energy is the same. This method uses a method of distributing the frequency of noise by slightly varying the size of the tread pattern block that is repeatedly arranged on the tire circumference.

Secondly, the excitation force due to the tread pattern block is reduced to reduce the noise generating energy when the road surface is in contact with the tread block. Since the tire is grounded at a finite length with the road surface, a sudden acceleration change occurs at the edge to be grounded. This change in acceleration also occurs in the case of a smooth tire without a tread pattern. However, the smooth tire is different from the pattern tire having a tread pattern in that the excitation force does not change along the tire circumference. If there is a tread pattern, a change in the excitation force occurs along the circumferential direction of the tire, causing a relatively loud noise compared to the smooth tire. Reducing such tire pattern noise is possible by reducing the amplitude of the excitation force along the circumferential direction.

In order to reduce the excitation force through this method, it is necessary to define the excitation force as a mathematical model when predicting the noise generated from the tire tread pattern through simulation in the design stage before production. In defining the excitation force that causes noise from the tire pattern shape, conventionally, for example, as disclosed in Korean Patent Laid-Open Publication No. 199-0017176, the sum of the widthwise ground areas of the tire, that is, the distribution of the ground planes causes the pattern noise. The sound wave waveform has been used to predict tire noise, and it is assumed that the ground pressure at the road surface and tire ground plane is uniform.

However, the dynamic ground pressure that is mounted on the vehicle and applied to the ground plane of the tire that is actually running is not uniform. In particular, there is a tendency that the ground pressure is greatly applied to the shoulder portion in the width direction of the tire ground surface, and the ground pressure is applied to the corner portion of each block in the running direction. Therefore, there is a significant error between the tire noise generated during the actual driving and the experimental results through simulation, which has resulted in a problem that the time and cost required for the development of new tires are increased.

Meanwhile, in Korean Patent Laid-Open No. 2000-0014285, it is assumed that the width of the ground pressure in the tread pattern block is proportional to the magnitude of the excitation force by the unit tread element. Although it shows the process of predicting tire tread pattern noise by considering the variable ground pressure distribution applied to the block as the weighting factor, the noise is effectively complicated and requires a long time in the tuning process. Could not be tuned.

Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and treads longitudinal grooves in the tire circumferential direction with little change in the tread pattern shape so as to distribute the ground pressure distribution of the shoulder portion inward or outward with respect to the shoulder portion. An object of the present invention is to provide a method for designing a low noise tire tread pattern which enables efficient noise tuning by moving in the width direction to adjust a desired frequency band.

In order to achieve the above object, the present invention is a center longitudinal groove formed in the circumferential direction of the tire and formed in the center portion of the tread, a shoulder longitudinal groove formed in the shoulder portion of the tread, and formed in the tread width direction of the tire and in the center of the tread. Design of a tire tread pattern comprising a center transverse groove formed at the site, a shoulder transverse groove formed at the shoulder portion of the tread, a center block partitioned by the groove and formed at the center portion of the tread, and a shoulder block formed at the shoulder portion In the method,

The shoulder longitudinal groove may be arranged by moving its position left or right in the tread width direction so that the width of the shoulder block and the width of the center block are different.

In addition, in the present invention, the position of the shoulder longitudinal groove is characterized in that the width of the shoulder block is moved in the direction of forming the center block larger than the width of the center block.

In the present invention, the width of the shoulder block / the width of the center block is characterized in that 1.09 to 1.15.

Hereinafter, with reference to the accompanying drawings, the present invention will be described in detail.

In general, the longitudinal groove position formed in the circumferential direction of the tire when the tire is serialized (the tire size required for each vehicle is different even in the same tread pattern, and a tire of 30 to 50 standard is commercialized in the same tread pattern) is specified. Not very different. At this time, the indoor noise permeation characteristics of the vehicle mounting the tire by tire specifications are different, so it is important to design the circumferential longitudinal groove position by tire specifications for efficient tire noise tuning.

Accordingly, the present invention is to optimize the tone / sound pressure for each noise frequency characteristic by appropriately designing the position of the circumferential longitudinal groove with little change in the tire tread pattern shape.

Prior to describing the design method of the longitudinal groove, the structure of the tread pattern of the tire according to the present invention will be described with reference to FIG.

As shown in FIG. 3, the tread pattern of the tire is divided into a plurality of blocks B1, B2, and B3 by longitudinal grooves G1 and G2 formed in the circumferential direction (driving direction) of the tire, and in the width direction of the tire. A plurality of lateral grooves G3 and G4 are formed.

The longitudinal grooves G1 and G2 include a center longitudinal groove G1 formed longitudinally at the center portion of the tread and a shoulder longitudinal groove G2 formed longitudinally at the shoulder portion of the tread. In addition, the horizontal grooves G3 and G4 communicating with the longitudinal grooves G1 and G2 include a center horizontal groove G3 formed laterally at the center of the tread and a shoulder formed laterally at the shoulder of the tread. It consists of lateral grooves (G4). The blocks B1, B2, and B3 divided by the longitudinal grooves G1 and G2 and the horizontal grooves G3 and G4 are formed of the main block B1 and the center block B2 formed at the center of the tread and the tread. It consists of a shoulder block (B3) formed on the shoulder portion. The main block B1 is not necessarily formed, and may be omitted depending on the shape of the tread pattern of the tire. In this case, only one center longitudinal groove G1 may be present between the left and right center blocks B2.

The tire tread of this structure shows different ground pressure distributions in the grounding direction and the running direction under the load of the vehicle. In general, tire noise includes structural vibration noise and tire tread pattern block vibration noise generated when the tire tread pattern block is in contact with the road surface. The pattern block noise is caused by the ground pressure distribution in the direction of the uneven tread width of the tire tread surface. This distribution shows a drastic difference for each frequency band. Accordingly, the present invention is a method capable of effectively controlling such a difference, so that the low frequency band (500 Hz or less) and the high frequency generated by the pattern block can be reflected to reflect the characteristics of the road surface required by the vehicle and the tire sound required by the driver. By separating the band (1000Hz), we have found and described a method to efficiently tune noise.

In general, in order to calculate the ground pressure distribution of a tire without a tread pattern, the tire is fixed to the rotating shaft so that the tire can be driven at a predetermined pressure, and a constant load (for example, a 510 kg vehicle load applied to one tire) is applied to the tire to be pressed at a predetermined pressure. In this condition, the tire is driven through the measuring plate parallel to the road surface at a constant speed. Here, the measuring plate is provided with one sensor per unit section (width direction and circumferential direction), so that when the tire passes through the measuring plate, the measured value is input to the controller from the sensor of the measuring plate. The measured values are analyzed to calculate the shape of the ground plane and the distribution of ground pressure for each unit time.

According to this simulation method, as shown in FIG. 1, it can be seen that the ground pressure is suddenly applied to the shoulder portion of the end of the tread pattern. As a result of analyzing the distribution of the ground pressure distribution, the shoulder portion as shown in FIG. 2 is stressed. You can see that this takes a lot. Therefore, since the portion that transmits the greatest impact from the road surface to the tire is the shoulder portion of the tire tread, the present invention is to control the noise by distributing the ground pressure distribution of this portion to the inside or the outside of the tread width.

3 shows a tire tread pattern in which blocks are divided at equal intervals about the center of the tread width, when moving to the left (outer) or to the right (inner) with respect to the shoulder longitudinal groove G2, that is, The shoulder longitudinal grooves G2 are moved left and right in the tread width direction, respectively, to indicate that the ratio of the width of the shoulder block and the width of the center block (in the range of 10% to 20%) can be set differently. 4 illustrates a model for analyzing how noise characteristics change when the width ratio of each block is set as described above.

In Figure 4, model 1 is the ground pressure distribution when the position of the shoulder longitudinal groove is moved 4 mm inward in the tread width direction, i.e., when the width of the center block is 20% smaller than the width of the shoulder block, model 2 is the length of the shoulder longitudinal groove. When the position is moved 2 mm inward in the tread width direction, i.e. when the width of the center block is 10% less than the width of the shoulder block, model 3 shows the reference tire tread pattern of which the position of the shoulder longitudinal groove is not shifted at all. The earth pressure distribution is shown. The model 4 has a ground pressure distribution when the position of the shoulder longitudinal groove is moved 2 mm outward in the tread width direction, that is, when the width of the shoulder block is 10% smaller than the width of the center block, and the model 5 has a position of the shoulder longitudinal groove. The ground pressure distribution is shown when the width of the shoulder block is 20% smaller than the width of the center block when the width of the shoulder block is moved 4 mm outward in the tread width direction.

Thus, the noise characteristics change when the width of the shoulder block is 10% to 20% less than the width of the center block, or vice versa, is 10% to 20% less than the width of the shoulder block. As shown in FIG. 6, it is understood that the sound pressure is rapidly different for each frequency band as a result of dividing the signal into 500 Hz or less and 1000 Hz bands by measuring the noise level.

In general, when subjective tuning of tire noise (Subjective Tuning), the noise of less than 500Hz is mainly referred to as the paging (Phasing) noise characteristics, 1000Hz band is called the (Whine) noise characteristics, the shoulder longitudinal loop applied in the present invention The shift method of (G2) is very effective. That is, the tire that is a problem at the mid-low frequencies of the 500 Hz band can lower the sound pressure by shifting the longitudinal groove in the circumferential direction, that is, the shoulder longitudinal groove G2 in the direction of the formation of the outer center block B2, and the high frequency band ( When lowering the sound pressure of 1000 Hz), shifting the shoulder longitudinal groove G2 in the direction in which the center block B2 is formed is ideal for optimizing the noise tuning.

Particularly, the position of the shoulder longitudinal groove G2 where both low and high frequency noises are optimal is when the width of the shoulder block B3 is larger than the width of the center block B2, that is, the width / center block of the shoulder block B3. When the width of B2 is 1.09 to 1.15, the tire pattern noise state is most optimally represented.

Thus, the present invention, in the tread pattern shape tuned to a certain level of tire noise, in the circumferential longitudinal groove, only the position of the stress-bearing shoulder longitudinal groove (G2) by simply adjusting the characteristics of the noise change according to the ground pressure displacement By analyzing using the test tire, the designer of the tire tread pattern can have the desired noise frequency characteristics.

As described above, according to the present invention, the shoulder longitudinal grooves of the longitudinal circumference of the tire circumferential longitudinal grooves with little change in the tread pattern shape can be moved left and right in the tread width direction so as to distribute the ground pressure distribution of the shoulder portion inward or outward. By adjusting, the effective noise tuning for noise reduction can be performed.

Claims (3)

delete delete A center longitudinal groove G1 formed in the circumferential direction of the tire and formed at the center portion of the tread; a shoulder longitudinal groove G2 formed at the shoulder portion of the tread; and a center formed in the tread width direction of the tire and formed at the center portion of the tread; The center block B2 and the shoulder portion defined by the horizontal groove G3, the shoulder horizontal groove G4 formed at the shoulder portion of the tread, and the grooves G1, G2, G3, G4 formed at the center portion of the tread. In the tire tread pattern design method comprising a shoulder block (B3) formed in, The shoulder longitudinal grooves G2 are arranged by moving their positions left or right in the tread width direction so that the width of the shoulder block B3 and the width of the center block B2 are different from each other. The position of the shoulder longitudinal groove G2 is moved in the direction of forming the center block B2 such that the width of the shoulder block B3 is larger than the width of the center block B2, The width of the shoulder block (B3) / width of the center block (B2) is 1.09 to 1.15 design method of the low noise tire tread pattern.

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