JPH1090125A - Method for measuring tire noise - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method by which the slipping sound produced between a tire and a road surface can be measured. SOLUTION: In a method for measuring tire noise, tires 2R and 2L having different dynamic load radii r1 and r2 are supported on tire rotating shafts TC which are rotated at the same rotating speed and simultaneously brought into contact cylindrical drums 5 fixed on a drum rotating shaft DC which is set in parallel with the shafts TC and has a radius R. Then the shafts TC or the shaft DC is rotationally driven while the tires 2R and 2L are held in a state where their positions are restricted in the running directions and, at the same time, the slip ratio S which is the ratio sk(r1-r2)/(rl+r2)| of the difference between the dynamic load radii r1 and r2 of the tires 2R and 2L to the sum (r1+r2) of the radii r1 and r2 is set at >=0.05 and <=0.20. Therefore, slips can be caused between the tires 2L and 2R and drums 5 and the slipping sounds between the tires 2R and 2L and drums 5 can be measured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of measuring tire noise, and more particularly to a method of easily measuring a slip noise generated between a tire and a road surface.

[0002]

2. Description of the Related Art As a method of evaluating tire noise generated when a tire travels on a road surface, conventionally, a vehicle is coasted with an engine turned off (or in a neutral state). 2. Description of the Related Art A coasting noise test using an actual vehicle for measuring noise at a time is known.

On the other hand, in ISO 362, TRIAS 20, and the like, there is also known an acceleration running noise test in which a vehicle passes through a noise measurement position while being fully accelerated.

FIG. 6 shows the results of these coasting and acceleration running noise tests in comparison. In the test, 265 / 70R16 test tires were mounted on a test vehicle (modified muffler), the coasting speed was 50 km / H in the coasting test, and the acceleration speed was 50 km / H in the acceleration running test, and the third gear was fully opened and accelerated. And

[0005] Comparing the results of these coasting and acceleration running noise tests, it can be seen that the acceleration running noise has a higher sound pressure level on the high frequency side of about 800 to 2000 Hz than the coasting running noise. In recent years, various studies have been made on the increase in the sound pressure level, and it has been found that the slipping noise of the tire caused by the relative slip between the tire and the road surface due to the driving force at the time of vehicle acceleration has been found. .

As described above, when the vehicle is accelerating, the tire noise is higher on the high frequency side than when coasting, so that the tire noise during the vehicle acceleration (the noise contributed by the tire to the total noise) is accurately measured. This is also important in the development of technologies to respond to European and Japanese acceleration noise regulations and to reduce tire noise.

However, while the vehicle is accelerating on the road,
Since the engine noise and the wind noise of the vehicle body also increase, it is difficult to accurately measure the contribution ratio of the tire noise to the total running noise of the vehicle.

In order to quantitatively grasp the tire noise from the total running noise of the vehicle, the engine noise can be reduced by using a vehicle in which the intake and exhaust systems have been subjected to soundproofing. A method of obtaining the tire noise (Nt) by subtracting the engine noise (Ne) from the total noise (Na) during acceleration of the vehicle has been proposed.

However, at present, the engine noise (N
e) is also affected by temperature, humidity, etc. at the time of measurement,
It is difficult to grasp this accurately. Further, in any of the methods, since it is necessary to accelerate the actual vehicle, the measurement of noise requires a great deal of labor and time.

The present invention has been devised in view of the above-described problems. In particular, it is possible to prevent slippage occurring between a tire and a road surface without actually running the vehicle on the road surface, for example, in an anechoic room or the like. It is an object of the present invention to provide a method for measuring tire noise by making it relatively easy even in a test room.

[0011]

According to the first aspect of the present invention, a tire having different dynamic load radii r1 and r2 is supported on a tire rotation axis having the same rotation speed, and the two tires are mounted on the tire. Along with a cylindrical drum having a radius R fixed to a drum rotating shaft substantially parallel to the rotating shaft,
While the position in the tire running direction is restrained and held, the ratio | (r1−r2) / (r1 + r) of the difference (r1−r2) of the dynamic load radius of the tire and the sum (r1 + r2) of the dynamic load radius.
2) The slip ratio S of | is 0.005 or more and 0.0
25 or less, by rotating the tire rotation axis or the drum rotation axis, causing a slip between the tire and the cylindrical drum, and measuring sound near the tire, This is a method of measuring tire noise.

In the invention described in claim 2, the tire having a large dynamic load radius is a smooth tire having no groove formed on a tread surface in contact with the cylindrical drum. It is a smooth tire.

The term "dynamic load radius of a tire" as used herein refers to the distance from the center of the tire rotation axis to the road surface when the tire is rolling. Tires having different dynamic load radii have the same load and rotational speed conditions. The ones with different dynamic load radii below.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described.
The case of using an actual vehicle in an anechoic room will be described with reference to the drawings. First, in this embodiment, as shown in FIGS. 1 and 2, a four-wheel vehicle 1 of a rear wheel drive type (FR) is used as a test vehicle, and different right and left rear wheels are provided with different dynamic load radius tires. 2R (dynamic load radius = r1) and 2L (dynamic load radius = r2) are mounted (r1> r2).

In this embodiment, the tire 2R having a large dynamic load radius is mounted with a smooth tire having no groove formed on the tread surface. A non-smooth tire having a groove on the tread surface is mounted on the tire 2L having a small dynamic load radius. Thereby, in the present example, the tire 2R has a higher grip force with the cylindrical drum 5 described later than the tire 2L.

Similarly, from the viewpoint of enhancing the grip force of one tire, the tire 2R having a large dynamic load radius has a larger tread width than the tire 2L having a small dynamic load radius, in combination with the above method. Can be employed alone.

The tires 2L, 2R having different dynamic load radii.
Is rotationally driven via an automobile engine E, a transmission G, a propeller shaft P, and a differential device D. In the present embodiment, the tires 2L and 2R are supported on the tire rotation axis TC having the same rotation speed by locking the differential device D and inhibiting the differential rotation. If the differential device locking means (so-called differential lock) is not provided, the differential device D of the automobile 1 may be modified for testing.

Thus, when the engine E of the automobile 1 is driven, the tires 2L and 2R can both rotate at the same rotational speed even if the rolling loads acting on the left and right tires 2L and 2R are different. The bigger tire is
The relative slip with the traveling road surface is larger than that of the tire on the side with the smaller load. Note that any tire may be mounted on the front wheel 4 of the automobile 1.

Next, the two tires 2 on the rear wheel side of the automobile 1
L and 2R are brought into contact with a cylindrical drum 5 having a radius R fixed to a drum rotation axis DC substantially parallel to the tire rotation axis TC, and restrained and held in a position in the tire running direction. It should be noted that since they are “substantially parallel”, the drum rotation axis DC
The case where the difference between the tire and the tire rotation axis TC is based on the camber angle of the tire can also be included in the scope of the present invention.

In this embodiment, the cylindrical drum 5 is directly connected to the left and right drum bodies 5L and 5R by a drum rotating shaft DC so as to be rotatable at the same rotational speed, and is rotatably supported. An example is shown. The drums 5L, 5R are partially exposed to the outside through the openings 6 on the floor surface, so that the tires 2L, 2R
Can abut.

In the present embodiment, the product names "Safety Walk" manufactured by Sumitomo 3M Co., Ltd. are attached to the surfaces of the drum bodies 5L and 5R. This "Safety Walk"
Sets the surface of the drum to, for example, a friction coefficient substantially similar to that of a dry asphalt road surface and finishes the drum with the same radius R.

As means for restraining and holding the position in the tire running direction, in this embodiment, a well-known tire stopper 7 is installed on the left and right front tires 4 of the automobile 1, and in this embodiment, the vehicle is mounted. A wire rope body 9 having one end fixedly supported on a road surface is locked at the four corners of the vehicle body.

Therefore, even if the automobile 1 drives the engine E to rotate both tires 2L, 2R of the rear wheels, the two tires 2L, 2R that are driven and rotated are rotated in a direction opposite to the tires and rotate. Since it stops rotating on the drum 5, it is restrained at the position of the spot.

In this embodiment, a load measuring device 10 such as a load cell is interposed in the wire rope body 9 locked at the rear of the vehicle. Thereby, the left and right wire rope bodies 9, 9 can monitor the force of pressing the vehicle 1 against the road surface. For example, a turn buckle or the like is used so that the loads acting on both the rear tires 2L, 2R become equal in advance. The length of the wire rope body 9 can be adjusted by the adjusting tool 11.

Thus, both rear tires 2L, 2L
When R is driven to rotate (including any of acceleration, constant speed, and deceleration driving), both tires 2L and 2R rotate integrally at the same rotation speed regardless of the left and right rolling loads as described above. , Because the dynamic load radii are different, the tire 2
Slip occurs between L, 2R and the cylindrical drum 5. The slip noise generated by the slip may be measured using a sound level meter 12 installed near the tire 2L or 2R in accordance with the rules of each noise test.

In this embodiment, since a smooth tire having a high gripping force is mounted on the tire 2R having a large dynamic load radius, the cylindrical drum 5 is substantially equal to the running distance of the tire 2R having a large dynamic load radius. Rotation distance (2π × r1 ×
(N).

Therefore, the tire 2 having a small dynamic load radius
The travel distance of L (2π × r2 × number of rotations) is smaller than the rotation distance of the cylindrical drum 5, and the slip amount is larger than that of the tire 2R having a large dynamic load radius due to being displaced from the drum side.

Therefore, in the present embodiment, more noise is measured by installing the sound level meter 12 near the tire 2L having a large amount of slip and a small dynamic load radius. Further, by mounting the smooth tire on the tire 2R having a large dynamic load radius, a preferable effect of reducing a pattern noise based on a tread pattern, which is a noise other than the tire noise, can be obtained.

The sound level meter is placed, for example, at a height of 0.25 m from the floor and at a distance of 1 laterally from the tire equator according to the test on a single tire stand. It can be arranged at an appropriate position.

As described above, in the present embodiment, slippage can be generated between the cylindrical drum 5 and the tire by a very simple method. Therefore, the tire slip noise can be obtained without actually running the vehicle on the road. Can be measured in a test room such as an anechoic chamber.

Incidentally, the tire 2L mounted on the rear wheel,
Ratio of difference (r1-r2) of dynamic load radius of 2R and sum of dynamic load radii (r1 + r2) | (r1-r2) / (r1 + r)
2) It is important that the slip ratio S defined by | is set to 0.005 or more and 0.025 or less.

Such a limitation of the slip ratio is described in "Study on the effect of driving torque on tire / road noise" reported by Japan Automobile Research Institute (JARI).
Is determined based on the relationship between the driving force acting on the tires of the actual vehicle and the slip ratio.

The graph of FIG. 3 shows various sizes (165S
R15, 195 / 70R15, 205 / 65R15, 2
15 / 65R15), the relationship between the driving force (N) and the slip ratio was measured using a tire characteristic test vehicle for passenger car tires of various patterns (the load per tire was 45
00 (N) and a speed of 30 (km / H)).

As is apparent from the figure, the slip ratio is set at 0.
It can be seen that in the range of 005 to 0.025, the driving force smoothly increases and a favorable slip at the time of acceleration can be obtained. In addition,
If the slip ratio exceeds 0.025, the slip becomes too large, the driving force decreases, and the test tire tends to wear out undesirably. Preferably, the slip ratio S is more desirably in the range of 0.01 to 0.02.

FIG. 4 shows the relationship between the slip ratio of each tire and the amount of increase in the sound pressure level of the noise when the driving force during acceleration running of the test vehicle is about 2000 (N). From this figure, it can be seen that the slip ratio S is 0.005 to 0.0.
In the range of 25, it can be confirmed that the slip ratio has a positive correlation with the amount of increase in noise.

The method for measuring tire noise as described above can be performed in a laboratory such as an anechoic chamber as in this embodiment without actually running the vehicle on the road.
Noise other than tire noise can be largely eliminated.

Further, for example, even if the engine is driven at a constant rotation speed and the tire is driven at a constant speed, it is possible to cause a tire having a small dynamic load radius to slip.
Compared with the actual vehicle acceleration test, it is also possible to exclude the engine acceleration sound.

Conversely, the tire 2L having a small dynamic load radius
It is preferable that a non-smooth tire having a groove formed in the tread surface is mounted to promote a slip with a lower grip than a tire having a large dynamic load radius.

Further, in the present embodiment, the case of driving the tire rotating shaft has been described as an example. However, both the rear tires 2L, 2R are supported so as to be freely rotatable together, and the drum rotation of the cylindrical drum 5 is performed. Driving the shaft with a motor or other prime mover can also measure tire slip noise.

The method of restraining the vehicle (tire) is not limited to the above method, but may be a method of fixing a wheel hub of a front wheel, a torque box of a vehicle body frame (a securing device used for transporting a freight car of a vehicle). Various methods such as a method of locking the hole) with a fixing pin or the like can be adopted.

When a front-wheel drive (FF) vehicle is used for the test, the front-wheel-side tires may be brought into contact with the rotating drum 5, but at this time, the steering of the front wheels is fixed in a straight-ahead state. Thereby, it can also be measured in the same manner as in the above method.

Further, in the above embodiment, the case where the actual vehicle is used has been described. However, the present invention is not limited to the case where the actual vehicle is used. Can be measured. In this case, by employing a motor instead of the engine, it is easy to further reduce engine noise, and it may not be necessary to take measures against exhaust gas.

[0043]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A tire noise measuring method according to the present invention and an acceleration running noise test method using an actual vehicle are performed as shown in Table 1.
The correlation between the two was examined. The tires were of the same size and used by four different manufacturers.

[0044]

[Table 1]

FIG. 5 shows the results of the test, in which the vertical axis represents the maximum value d of the overall vehicle acceleration noise (3rd gear fully open).
B (A), and the horizontal axis represents a partial overall (PO) of 1 to 4 KHz of the noise measured using the method of the present invention.
A) represents dB (A). As is clear from the figure,
About the measured noise of the method of the present invention and the actual vehicle acceleration test,
It was confirmed that there was a positive correlation. Therefore, it is possible to obtain effective data on tire noises related to actual vehicle data.

[0046]

As described above, according to the method of the present invention, tire slippage is generated on the basis of a simple configuration in which the dynamic load radii of the left and right tires are changed without actually accelerating the vehicle on the road surface. Therefore, for example, the sound can be measured in a laboratory such as an anechoic chamber, and the measurement accuracy of tire slip noise can be improved by largely removing noise other than tire noise.

Further, for example, even if the test tire is run at a constant speed, the tire can slip, so that the engine acceleration sound can be reduced as compared with the actual vehicle acceleration test.

Further, the tire having a large dynamic load radius is a smooth tire having no groove formed on the tread surface in contact with the cylindrical drum, so that the grip between the tire and the cylindrical drum is enhanced, and at the same time, other than the slipping noise, , Such as pattern noise based on the tread pattern, can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic plan view for explaining a method of the present invention.

FIG. 2 is a schematic side view for explaining the method of the present invention.

FIG. 3 is a graph showing a relationship between a driving force and a slip ratio.

FIG. 4 shows a driving force of about 2,000 when the test vehicle accelerates.
It is a graph which shows the relationship between the slip ratio of each tire at the time of (N), and the sound pressure level rise amount of noise.

FIG. 5 is a graph showing a relationship between a tire noise according to the present invention and an acceleration noise test using an actual vehicle.

FIG. 6 is a graph showing the results of a coasting running noise test and an acceleration running noise test.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Four-wheeled vehicle 2L Tire with small dynamic load radius 2R Tire with large dynamic load radius 5 Cylindrical drum 12 Sound level meter E Engine D Differential device TC Tire rotation axis DC drum rotation axis

Claims (2)

[Claims] 1. Tires having different dynamic load radii r1 and r2 are supported on a tire rotation axis having the same rotation speed, and the two tires are fixed to a drum rotation axis substantially parallel to the tire rotation axis. While being brought into contact with the cylindrical drum, the position in the tire running direction is restrained and held, and the ratio | (r1) of the difference (r1−r2) of the dynamic load radius of the tire and the sum of the dynamic load radii (r1 + r2). -R2) / (r1
+ R2) | is set to 0.005 or more and 0.025 or less, and the tire or the cylindrical drum is caused to slip by rotating the tire rotation axis or the drum rotation axis. And measuring the sound in the vicinity of the tire. 2. The tire having a large dynamic load radius is a smooth tire having no groove formed on a tread surface in contact with the cylindrical drum, and the tire having a small dynamic load radius is a non-smooth tire. Claim 1
The tire noise measurement method described.