Evaluation method of tire noise performance

Abstract

To provide an evaluation method for evaluating noise which occurs due to a circumferential groove and a lateral groove, by considering a change of noise which occurs on a circumferential groove according to presence / absence of a lateral groove opened to the circumferential groove.SOLUTION: An evaluation method of noise performance of a pneumatic tire is configured to: ground an evaluation tire Te and a second tire T2 on which a circumferential groove 1 is formed; acquire power values Pw1, Pw2 of a sound frequency response function from outsides Q1 of respective tires T to a measurement point Q2 which is set between the circumferential grooves 1, 2 of the respective tires T and a grounding plane D1; and determine a change ratio H of noise caused by the circumferential grooves 1, 2 on the basis of the acquired power values Pw1, Pw2. The method is configured to: evaluate noise performance caused by the circumferential grooves 1, 2 on the evaluation tire Te and noise performance caused by the lateral groove 3, on the basis of respective sound pressure levels P1, P2, P3 measured in rolling of the first tire T1, second tire T2, and the evaluation tire Te on which the circumferential grooves 1, 2 and the lateral groove 3 are not formed, and the change ratio H.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for evaluating tire noise performance. [Background technology]

[0002] Various methods have been proposed for evaluating tire noise performance. For example, Patent Document 1 below proposes a method for measuring noise generated when a grooved tire and a grooved tire are mounted on a vehicle and driven, and evaluating the noise caused by the grooves in the tread from the measurement results of both tires.

[0003] This method is based on the premise that the noises generated by the circumferential grooves and the lateral grooves are generated independently of each other. However, when the lateral grooves open into the circumferential grooves, the noise generated by the circumferential grooves varies depending on the position and size of the lateral grooves, making it difficult to accurately evaluate using the conventional evaluation method. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2022-56046 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an evaluation method capable of evaluating noise generated due to circumferential grooves and lateral grooves, taking into account a change in noise of the circumferential grooves due to the provision of lateral grooves. [Means for solving the problem]

[0006] The present invention includes the embodiments set forth below.

[0007] [1] A method for evaluating noise performance of a test tire having a circumferential groove extending in a tire circumferential direction and a lateral groove extending in a tire axial direction and opening into the circumferential groove, comprising: A first step of acquiring a first sound pressure, which is a sound pressure level measured during rolling of a first tire having the same structure as the evaluation tire and having neither circumferential grooves nor lateral grooves formed in the tread; A second step of acquiring a second sound pressure, which is a sound pressure level measured during rolling of a second tire having the same structure as the evaluation tire, and having a circumferential groove formed in the tread and no lateral groove formed therein; A third step of acquiring a third sound pressure, which is a sound pressure level measured when the evaluation tire is rolling; A fourth step of acquiring a first power value, which is a power value of a frequency response function of a sound from the outside of the evaluation tire that is grounded to a first measurement point set between the circumferential groove and the ground contact surface of the evaluation tire, and a second power value, which is a power value of a frequency response function of a sound from the outside of the second tire that is grounded to a second measurement point set between the circumferential groove and the ground contact surface of the second tire, and determining a rate of change in noise caused by the circumferential groove based on the acquired first power value and second power value; a fifth step of evaluating a noise performance caused by the circumferential grooves and a noise performance caused by the lateral grooves in the evaluation tire based on the first sound pressure, the second sound pressure, the third sound pressure, and the rate of change; A method for evaluating tire noise performance comprising:

[0008] [2] A sound pressure level is measured between the circumferential groove and the ground contact surface of the evaluation tire while radiating an acoustic output from a volume velocity sound source to the evaluation tire that is grounded, thereby obtaining the first power value; The method for evaluating noise performance of a tire described in [1] above, further comprising: radiating an acoustic output from a volume velocity sound source to the second tire placed on the ground, while measuring a sound pressure level between the circumferential groove of the second tire and the contact surface, thereby obtaining the second power value.

[0009] [3] setting an evaluation tire model corresponding to the evaluation tire, a sound source point for inputting sound from an external source to the evaluation tire model placed on the ground, and a measurement point provided between a circumferential groove of the evaluation tire model and a ground contact surface, and performing an acoustic analysis to obtain the first power value; The method for evaluating noise performance of a tire according to the above-mentioned [1], further comprising: setting a second tire model corresponding to the second tire; a sound source point for inputting sound into the second tire model placed on the ground; and a measurement point provided between a circumferential groove of the second tire model and the contact surface; and performing acoustic analysis to obtain the second power value.

[0010] [4] A method for evaluating noise performance of a tire as described in [1] or [2] above, comprising determining a frequency band for evaluating noise performance based on a length of a circumferential groove in the contact surface of the evaluation tire, and determining the rate of change based on the sum of the first power values ​​and the sum of the second power values ​​in the determined frequency band.

[0011] [5] The circumferential groove includes a center circumferential groove and a shoulder circumferential groove, The method for evaluating noise performance of a tire according to any one of the above [1] to [4], wherein the rate of change is determined based on a first average value which is an average value of a first power value in the center circumferential groove and the first power value in the shoulder circumferential groove, and a second average value which is an average value of a second power value in the center circumferential groove and the second power value in the shoulder circumferential groove. Effect of the Invention

[0012] In the present invention, by providing the above-mentioned features, it is possible to evaluate the noise generated due to the circumferential grooves and the lateral grooves, taking into consideration the change in noise of the circumferential grooves due to the provision of the lateral grooves. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a development view showing the tread patterns of tires, in which (a) is an evaluation tire, (b) is a first tire, and (c) is a second tire. [Diagram 2]FIG. 2A is a view from the tire axial direction showing an evaluation test of the noise performance of a tire according to one embodiment of the present invention, and FIG. 2B is a view showing the tire contact surface and the positions of a microphone and a speaker during the evaluation test. [Diagram 3] Figure 2(a) viewed from the direction of arrow A [Figure 4] FIG. 1 is a diagram showing the configuration of an evaluation device for performing a method for evaluating tire noise performance according to an embodiment of the present invention. [Diagram 5] FIG. 1 is a diagram showing the configuration of an evaluation device for performing a method for evaluating tire noise performance according to a modified example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The embodiments will be described with reference to the drawings. Note that the embodiments described below are merely examples, and any appropriate modifications that do not depart from the gist of the present invention are included in the scope of the present invention.

[0015] The method for evaluating tire noise performance in this embodiment is a method for evaluating the noise performance caused by the circumferential grooves 1, 2 and the noise performance caused by the lateral groove 3 for an evaluation tire Te having in its tread circumferential grooves 1, 2 extending in the tire circumferential direction and a lateral groove 3 extending in the tire axial direction and opening into the circumferential grooves 1, 2.

[0016] This evaluation method includes first to third steps carried out by mounting an evaluation tire Te, which is a tire to be evaluated, a first tire T1, and a second tire T2 on a vehicle 7, and fourth and fifth steps carried out using an evaluation device 10 illustrated in FIG. 2.

[0017] (1) Configurations of the Evaluation Tire Te, the First Tire T1, and the Second Tire T2 As shown in Fig. 1(a), the test tire Te is a tire having, in its tread, circumferential grooves 1 and 2 extending in the tire circumferential direction, and lateral grooves 3 extending in the tire axial direction and opening into the circumferential grooves 1 and 2. The test tire Te of this embodiment is provided with, as circumferential grooves, a pair of center circumferential grooves 1 arranged on both sides of the tire equatorial plane CL, and a pair of left and right shoulder circumferential grooves 2 arranged axially outward of the center circumferential groove 1. The lateral grooves 3 extend in a direction intersecting the center circumferential groove 1 and the shoulder circumferential groove 2, and their ends open into the center circumferential groove 1 and the shoulder circumferential groove 2. A plurality of lateral grooves 3 are provided at intervals in the tire circumferential direction.

[0018] The first tire T1 has the same structure as the evaluation tire Te, and is a non-pattern tire in which, as shown in FIG. 1(b), neither the circumferential grooves 1, 2 nor the lateral grooves 3 are formed in the tread.

[0019] The second tire T2 has the same structure as the evaluation tire Te, and as shown in Figure 1 (c), the tread has a center circumferential groove 1 and a shoulder circumferential groove 2 of the same shape and at the same positions as the evaluation tire Te, but no lateral grooves 3.

[0020] The term "same structure" means that the internal structure of the tire, such as the bead core, carcass, and belt, the materials constituting the tire, and various dimensions are the same.

[0021] (2) Configuration of Evaluation Device 10 As shown in FIGS. 2 to 4, the evaluation device 10 has a support portion 11, a load application device 12, a volume velocity sound source 13, microphones 14 and 15, and a computer 16.

[0022] The support portion 11 supports the evaluation tire Te and the second tire T2. The load application device 12 presses the evaluation tire Te and the second tire T2 supported by the support portion 11 against the road surface R with a predetermined amount of force.

[0023] The volume velocity sound source 13 includes a speaker that generates a sound (sound output) in a predetermined frequency band based on sound data input from the computer 16. The volume velocity sound source 13 is disposed on the equatorial plane CL of the evaluation tire Te and the second tire T2 supported by the support part 11, at a position Q1 that is a predetermined distance away from the tire circumferential center (ground contact center) Gc of the portion (ground contact surface) G where the evaluation tire Te and the second tire T2 contact the road surface R, for example, at a position 1 m away from the ground contact center Gc and 25 cm above the road surface R. The volume velocity sound source 13 radiates sound output from this position toward the evaluation tire Te and the second tire T2 that are in contact with the road surface R.

[0024] The microphone 14 is, for example, a probe microphone having a sound collecting portion (measurement portion) 14a at the tip of a probe, or a Micro-Electrical-Mechanical Systems (MEMS) microphone.

[0025] The microphone 14 is disposed at a position Q2 in which the sound collecting portion 14a is set in a space S surrounded by at least one of the circumferential grooves 1 and 2 of the evaluation tire Te and the second tire T2 and the road surface R. While an acoustic output is being output from the volume velocity sound source 13, the microphone 14 measures the sound pressure of the acoustic output output from the volume velocity sound source 13 disposed at the position Q1 with the sound collecting portion 14a disposed at the position Q2 (see FIG. 2(b)).

[0026] Position Q2 where sound collecting portion 14a of microphone 14 is disposed is preferably the ground center Gc of space S. The probe and sound collecting portion 14a of microphone 14 are preferably provided with a diameter of, for example, 0.8 mm to 1.2 mm, which is smaller than space S surrounded by circumferential grooves 1, 2 and road surface R.

[0027] The microphone 14 measures the sound pressure of the acoustic output from the volume velocity sound source 13 and transmits the obtained measurement data to the computer 16 .

[0028] The microphone 15 measures the sound pressure of noise generated from the contact portions G of the evaluation tire Te, the first tire T1, and the second tire T2 when a vehicle equipped with the evaluation tire Te, the first tire T1, and the second tire T2 runs on the test road surface R.

[0029] The microphone 15 measures the sound pressure of the noise generated from the ground contact portions G of the test tire Te, the first tire T1, and the second tire T2, and transmits the obtained measurement data to the computer 16.

[0030] The computer 16 has a processing device and a storage device, and functions as a sound pressure data acquisition unit 31, a device control unit 32, and an evaluation unit 33 by the processing device reading and executing a program stored in the storage device.

[0031] The sound pressure data acquisition unit 31 acquires the microphone 14 and the measurement data by the microphone 14. The device control unit 32 controls the load application device 12.

[0032] The evaluation unit 33 evaluates the noise performance at a predetermined frequency caused by the circumferential grooves 1 and 2 and the noise performance at a predetermined frequency caused by the lateral groove 3 in the evaluation tire Te based on the measurement data acquired by the sound pressure data acquisition unit 31.

[0033] In the evaluation device 10, at least the support 11, the volume velocity sound source 13, and the microphone 14 are arranged in an environment suitable for measuring sound, such as an anechoic chamber or a semi-anechoic chamber. In this environment, an acoustic test is performed in which the acoustic output radiated from the volume velocity sound source 13 is measured by the microphone 14.

[0034] (3) Evaluation method for tire noise performance The method for evaluating tire noise performance in this embodiment is a method for evaluating the noise performance caused by the circumferential grooves 1 and 2 and the noise performance caused by the lateral groove 3 of an evaluation tire Te in an evaluation frequency band Fm (e.g., 708 Hz to 1414 Hz) which is a frequency band for noise evaluation, and performs a first step, a second step, a third step, a fourth step, and a fifth step. Note that the order of performing the first step, the second step, the third step, and the fourth step may be arbitrary.

[0035] In the first step, a first sound pressure P1, which is the sound pressure level of a sound (noise) in the evaluation frequency band Fm generated when a vehicle equipped with the first tire T1 runs on a test road surface for noise testing, is measured by the microphone 15. The first sound pressure P1 measured in the first step is noise in the evaluation frequency band Fm generated when the first tire T1 rolls, and includes noise caused by body vibration of the tire.

[0036] In the second step, a second sound pressure P2, which is the sound pressure level of a sound (noise) in the evaluation frequency band Fm generated when a vehicle equipped with the second tire T2 runs on a test road surface for noise testing, is measured by the microphone 15. The second sound pressure P2 measured in the second step is noise in the evaluation frequency band Fm generated when the second tire T2 rolls, and includes noise caused by the circumferential grooves 1 and 2 provided in the second tire T2 and noise caused by body vibration of the tire.

[0037] In the third step, a third sound pressure P3, which is the sound pressure level of a sound (noise) in the evaluation frequency band Fm generated when a vehicle equipped with the evaluation tire Te runs on a test road surface for noise testing, is measured by the microphone 15. The third sound pressure P3 measured in the third step is noise in the evaluation frequency band Fm generated when the evaluation tire Te rolls, and includes noise caused by the circumferential grooves 1 and 2 provided in the evaluation tire Te, noise caused by the lateral groove 3, and noise caused by tire body vibration.

[0038] In the first to third steps, when the vehicle is coasted at a predetermined speed, for example, 50 km / h, the first sound pressure P1, the second sound pressure P2, and the third sound pressure P3 are measured by a microphone installed at a position (7.5±0.05) m away from the vehicle centerline and (1.2±0.05) m above ground. In the first to third steps, the test surface for the noise test on which the vehicle is run is the external noise test surface specified in ISO10844;2011.

[0039] In the fourth step, a rate of change H of noise caused by the circumferential grooves 1 and 2 due to the presence or absence of the lateral grooves 3 is determined. That is, in the evaluation tire Te, the lateral grooves 3 are open to the circumferential grooves 1 and 2, so the air pressure in the circumferential grooves 1 and 2 during tire rotation is lower than in the second tire T2 that is not provided with the lateral grooves 3. Therefore, the evaluation tire Te has reduced air columnar resonance sound and reduced noise caused by the circumferential grooves 1 and 2 compared to the second tire T2.

[0040] Therefore, a change rate H of the noise caused by the circumferential grooves 1, 2 in the evaluation tire Te provided with the lateral grooves 3 relative to the noise caused by the circumferential grooves 1, 2 in the second tire T2 not provided with the lateral grooves 3 is determined.

[0041] Specifically, the fourth step includes a first power value obtaining step, a second power value obtaining step, and a change rate calculating step. The fourth step can be performed by an evaluation device 10 as shown in FIG. 2 and FIG. 3.

[0042] In the first power value acquisition process, the evaluation device 10 presses the evaluation tire Te supported by the support portion 11 against the road surface R with a predetermined force using the load application device 12, and positions the evaluation tire Te so that it comes into contact with the road surface R. In addition, the evaluation device 10 positions the sound collection portion 14a of the microphone 14 at a position Q2, for example, at the contact center Gc of the space S surrounded by the circumferential groove 1 of the evaluation tire Te and the road surface R.

[0043] The evaluation device 10 radiates an acoustic output including a sound in the evaluation frequency band Fm from the volume velocity sound source 13 arranged at position Q1 toward the evaluation tire Te, and measures a fourth sound pressure P4, which is the sound pressure level of the acoustic output radiated from the volume velocity sound source 13, by the sound collecting portion 14a of the microphone 14 arranged at position Q2. Here, the microphone 14 measures the fourth sound pressure P4 at a predetermined pitch (for example, every 1 Hz from 708 Hz to 1414 Hz) in the evaluation frequency band Fm.

[0044] It should be noted that while the evaluation device 10 is measuring the acoustic output radiated from the volume velocity sound source 13 by the microphone 14, the evaluation tire Te is stationary and not rolling.

[0045] When the sound pressure data acquisition unit 31 acquires the fourth sound pressure P4 measured by the microphone 14, the evaluation unit 33 calculates a first power value Pw1, which is the power value of the frequency response function of the sound from position Q1 to position Q2, based on the acoustic output Ue radiated from the volume velocity sound source 13 and the fourth sound pressure P4 measured by the microphone 14 at each predetermined pitch within the evaluation frequency band Fm, based on the following equation (1).

[0046]

number

[0047] In the second power value acquisition process, the evaluation device 10 presses the second tire T2 supported by the support portion 11 against the road surface R with a predetermined force using the load application device 12, and positions the second tire T2 so that it comes into contact with the road surface R. In addition, the evaluation device 10 positions the sound collection portion 14a of the microphone 14 at a position Q2, for example, at the contact center Gc of the space S surrounded by the circumferential groove 1 of the second tire T2 and the road surface R.

[0048] Then, the evaluation device 10 measures a fifth sound pressure P5, which is the sound pressure level of the sound output radiated from the volume velocity sound source 13 by the sound collection part 14a of the microphone 14 arranged at position Q2, while radiating the same sound output as the sound output radiated from the volume velocity sound source 13 in the first power value acquisition process from the volume velocity sound source 13 arranged at position Q1 toward the second tire T2. Here, the microphone 14 measures the fifth sound pressure P5 at every predetermined pitch within the evaluation frequency band Fm, similar to the first power value acquisition process.

[0049] It should be noted that while the evaluation device 10 is measuring the acoustic output radiated from the volume velocity sound source 13 by the microphone 14, the second tire T2 is not rolling but is stationary.

[0050] When the sound pressure data acquisition unit 31 acquires the fifth sound pressure P5 measured by the microphone 14, the evaluation unit 33 calculates a second power value Pw2, which is the power value of the frequency response function of the sound from position Q1 to position Q2, based on the acoustic output Ue radiated from the volume velocity sound source 13 and the fifth sound pressure P5 measured by the microphone 14 at each predetermined pitch within the evaluation frequency band Fm, based on the following equation (2).

[0051]

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[0052] When the total values ​​POAL1 and POAL2 are calculated, the evaluation unit 33 calculates the rate of change H based on the following formula (3).

[0053]

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[0054]

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[0055]

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[0056]

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[0057] The second energy E2 is noise generated when the second tire T2 rolls, and corresponds to the combined energy of noise energy e1 caused by tire body vibration and noise energy e'2 caused by circumferential grooves 1 and 2 that are not connected to the lateral groove 3.

[0058] The third energy E3 corresponds to a combination of noise energy e1 generated due to tire body vibration, noise energy e2 generated due to circumferential grooves 1 and 2 connected to the lateral groove 3, and noise energy e3 generated due to the lateral groove 3 opening into the circumferential grooves 1 and 2.

[0059] In addition, the rate of change H is the rate of change of the noise generated due to the circumferential grooves 1 and 2 in the evaluation tire Te, which has lateral grooves 3, relative to the noise generated due to the circumferential grooves 1 and 2 in the second tire T2, which does not have lateral grooves 3.

[0060] Therefore, the relationships of the following formulas (7) to (10) are established among the energies E1, E2, E3, the energies e1, e2, e'2, e3, and the rate of change H.

[0061]

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[0062]

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[0063]

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[0064]

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[0065]

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[0066]

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[0067]

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[0068] Specifically, the first contribution rate R1 is the ratio of noise caused by tire body vibration to the noise generated when the evaluation tire Te rolls. The energy of the noise generated when the evaluation tire Te rolls is e1+e2+e3, and the energy of the noise caused by tire body vibration is e1, so the first contribution rate R1 is calculated based on the following formula (14).

[0069]

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[0070]

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[0071]

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[0072] (5) Example of changes Modifications of the above-described embodiment will be described. Any one of the multiple modification examples described below may be applied to the above-described embodiment, or any two or more of the modification examples described below may be applied in combination. In addition to the following modification examples, various modifications are possible.

[0073] (5-1) Change example 1 In the above embodiment, in the fourth step, the acoustic output radiated from the volume velocity sound source 13 for the evaluation tire Te and the second tire T2 is measured by the microphone 14, and the first power value and the second power value are obtained based on the measurement results to determine the rate of change H. However, for example, the acoustic analysis unit 40 shown in FIG. 5 may perform acoustic analysis using an evaluation tire model and a second tire model corresponding to the evaluation tire and the second tire, and the rate of change H may be determined based on the analysis results.

[0074] For example, in this modified example, the computer 16 has a processing device and a storage device, and the processing device reads and executes a program stored in the storage device, thereby functioning as an acoustic analysis unit 40 in addition to a sound pressure data acquisition unit 31, a device control unit 32, and an evaluation unit 33.

[0075] The acoustic analysis unit 40 performs acoustic analysis using a model that reproduces an acoustic test in which the acoustic output radiated from the volume velocity sound source 13 placed at position Q1, which was performed in the first power acquisition process and the second power acquisition process described above, is measured by the sound collection part 14a of the microphone 14 placed at position Q2.

[0076] The acoustic analysis unit 40 analyzes the transmission of sound from a sound source point set in the model to a measurement point set in the model by a numerical analysis method using a model divided into elements and having nodes, specifically finite element analysis or boundary element analysis.

[0077] As shown in FIG. 5, the acoustic analysis section 40 includes a ground contact analysis section 41, an acoustic analysis model acquisition section 42, a sound source setting section 43, a measurement point setting section 44, and a frequency response function calculation section 45.

[0078] The ground contact analysis unit 41 uses finite element models of the above-mentioned evaluation tire Te, second tire T2, and road surface R to determine the shape of the ground contact surface when the evaluation tire Te or the second tire T2 is pressed against the road surface R and the deformed shapes of the evaluation tire Te and the second tire T2.

[0079] The acoustic analysis model acquisition unit 42 acquires an evaluation tire model which is a model for acoustic analysis corresponding to the evaluation tire Te, a second tire model which is a model for acoustic analysis corresponding to the second tire T2, and a road surface model which is a model for acoustic analysis corresponding to the road surface R. For example, when performing a finite element analysis, a finite element model is acquired as the model for acoustic analysis.

[0080] Moreover, a sound source setting unit 43 sets a sound source point in the acoustic analysis at a position corresponding to the position Q1 in the evaluation tire model and the second tire model. Moreover, a measurement point setting unit 44 sets a measurement point in the acoustic analysis at a position corresponding to the position Q2 in the evaluation tire model and the second tire model.

[0081] The frequency response function calculation unit 45 uses the model acquired by the acoustic analysis model acquisition unit 42 to analyze the transmission of sound from the sound source point set by the sound source setting unit 43 to the measurement point set by the measurement point setting unit 44. Then, the frequency response function calculation unit 45 calculates a frequency response function of sound from position Q1 to position Q2 in the evaluation tire model and a first power value that is its power value, for each predetermined pitch in the evaluation frequency band Fm, and also calculates a frequency response function of sound from position Q1 to position Q2 in the second tire model and a second power value that is its power value.

[0082] Then, similarly to the fourth step in the above-described embodiment, the evaluation unit 33 calculates a total value POAL1 by adding up all the first power values ​​calculated for each frequency in the evaluation frequency band Fm calculated by the frequency response function calculation unit 45. The evaluation unit 33 also calculates a total value POAL2 by adding up all the second power values ​​calculated for each frequency in the evaluation frequency band Fm calculated by the frequency response function calculation unit 45. When the total values ​​POAL1 and POAL2 are calculated, the evaluation unit 33 calculates the rate of change H based on the above formula (3).

[0083] In this modified example, the acoustic analysis unit 40 can calculate the change rate H by acoustic analysis using the evaluation tire model and the second tire model, so that the volume velocity sound source 13, the microphone 14, etc. are not required in the evaluation device 10, and the device can be simplified.

[0084] (5-2) Change example 2 In the above embodiment, the tires Te, T1, and T2 are mounted on a vehicle and the above steps 1 to 3 are performed, but for example, the tires Te, T1, and T2 may be rolled on the outer peripheral surface of a drum to perform the above steps 1 to 3. Also, in the above embodiment, the tires Te and T2 are pressed against the road surface R to perform the fourth step, but the fourth step may be performed by a bench test.

[0085] (5-3) Change example 3 The evaluation frequency band Fm for evaluating the noise performance of a tire can be set to any frequency band, but for example, the evaluation frequency band Fm may be set based on the length of the circumferential grooves 1, 2 in the contact surface of the evaluation tire Te.

[0086] For example, assuming that the length of the circumferential grooves 1 and 2 in the contact patch of the evaluation tire Te is L (m), the sound speed is c (m / s), and the correction coefficient is α, the evaluation frequency band may be set to a frequency band having a width of a predetermined percentage of the frequency f (e.g., ±20% of f) centered on the frequency f calculated based on the following formula (17). The correction coefficient α is a correction coefficient that takes the horn effect into consideration, and may be set to, for example, 0.7.

[0087]

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[0088] (5-4) Change Example 4 In the above-described embodiment, in the first power value acquisition process and the second power value acquisition process of the fourth step, the sound collection portion 14a of the microphone 14 was positioned between the center circumferential groove 1 of the evaluation tire Te or the second tire T2 and the road surface R to measure the fourth sound pressure P4 and the fifth sound pressure P5, but the microphone 14 may be positioned between the shoulder circumferential groove 2 and the road surface R to measure the fourth sound pressure P4 and the fifth sound pressure P5, or the microphone 14 may be positioned in both the center circumferential groove 1 and the shoulder circumferential groove 2 to measure the fourth sound pressure P4 and the fifth sound pressure P5.

[0089] When the microphones 14 are arranged in both the center circumferential groove 1 and the shoulder circumferential groove 2 to measure the fourth sound pressure P4 and the fifth sound pressure P5, the fourth sound pressure P4 may be measured by the microphone 14 arranged in the center circumferential groove 1 of the evaluation tire Te and the microphone 14 arranged in the shoulder circumferential groove 2, and the average values ​​of the first power values ​​calculated from the measured fourth sound pressures P4 may be added together in the evaluation frequency band Fm to calculate the sum POAL1. Alternatively, the fifth sound pressure P5 may be measured by the microphone 14 arranged in the center circumferential groove 1 of the second tire T2 and the microphone 14 arranged in the shoulder circumferential groove 2, and the average values ​​of the second power values ​​calculated from the measured fifth sound pressures P5 may be added together in the evaluation frequency band Fm to calculate the sum POAL2.

[0090] In this modified example, the change in noise in the center circumferential groove 1 and the shoulder circumferential groove 2 can be taken into consideration, and the noise generated due to the circumferential grooves 1, 2 and the lateral grooves 3 can be evaluated more accurately. [Explanation of symbols]

[0091] 1...center circumferential groove, 2...shoulder circumferential groove, 3...lateral groove, 10...evaluation device, 12...drum control device, 13...volume velocity sound source, 14...microphone, 15...microphone, 31...sound pressure data acquisition unit, 32...device control unit, 33...evaluation unit, 40...acoustic analysis unit, 41...ground contact analysis unit, 42...acoustic analysis model acquisition unit, 43...sound source setting unit, 44...measurement point setting unit, 45...frequency response function calculation unit, Fm...evaluation frequency band, G...ground contact portion, H...rate of change, T1...first tire, T2...second tire, Te...evaluation tire

Claims

1. A method for evaluating noise performance of a test tire having a circumferential groove extending in a tire circumferential direction and a lateral groove extending in a tire axial direction and opening into the circumferential groove, comprising: A first step of acquiring a first sound pressure, which is a sound pressure level measured during rolling of a first tire having the same structure as the evaluation tire and in which neither the circumferential groove nor the lateral groove is formed in a tread; a second step of acquiring a second sound pressure, which is a sound pressure level measured during rolling of a second tire having the same structure as the evaluation tire, the second tire having the circumferential groove formed in the tread and no lateral groove formed in the tread; A third step of acquiring a third sound pressure, which is a sound pressure level measured when the evaluation tire is rolling; a fourth step of acquiring a first power value, which is a power value of a frequency response function of a sound from the outside of the evaluation tire that is grounded to a first measurement point set between the circumferential groove and the ground contact surface of the evaluation tire, and a second power value, which is a power value of a frequency response function of a sound from the outside of the second tire that is grounded to a second measurement point set between the circumferential groove and the ground contact surface of the second tire, and determining a rate of change in noise caused by the circumferential groove based on the acquired first power value and second power value; a fifth step of evaluating a noise performance caused by the circumferential grooves and a noise performance caused by the lateral grooves in the evaluation tire based on the first sound pressure, the second sound pressure, the third sound pressure, and the rate of change; A method for evaluating tire noise performance comprising:

2. a volume velocity sound source radiates an acoustic output toward the test tire placed on the ground, while measuring a sound pressure level between the circumferential groove and the ground contact surface of the test tire to obtain the first power value; 2. The method for evaluating noise performance of a tire according to claim 1, wherein the second power value is obtained by measuring a sound pressure level between the circumferential groove and the contact surface of the second tire while radiating an acoustic output from the volume velocity sound source to the second tire that is grounded.

3. an evaluation tire model corresponding to the evaluation tire, a sound source point for inputting sound from an outside into the evaluation tire model placed on the ground, and a measurement point provided between a circumferential groove and a ground contact surface of the evaluation tire model are set, and an acoustic analysis is performed to obtain the first power value; 2. The method for evaluating tire noise performance according to claim 1, further comprising: setting a second tire model corresponding to the second tire, a sound source point for inputting sound to the second tire model placed in contact with the ground, and a measurement point provided between a circumferential groove of the second tire model and the ground contact surface, and performing acoustic analysis to obtain the second power value.

4. 2. The method for evaluating noise performance of a tire as described in claim 1, further comprising: determining a frequency band for evaluating noise performance based on a length of the circumferential groove in the contact surface of the evaluation tire; and determining the rate of change based on the sum of the first power values ​​and the sum of the second power values ​​in the determined frequency band.

5. The circumferential groove includes a center circumferential groove and a shoulder circumferential groove, 2. The method for evaluating noise performance of a tire according to claim 1, wherein the rate of change is determined based on a first average value that is an average value of the first power value in the center circumferential groove and the first power value in the shoulder circumferential groove, and a second average value that is an average value of the second power value in the center circumferential groove and the second power value in the shoulder circumferential groove.

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