JP5548116B2 - Test method of tire over bump performance - Google Patents

Description

The present invention relates to a test method for a tire overpass performance of a tire that can improve the evaluation performance of ride comfort.

  Conventionally, in order to evaluate the riding comfort of a vehicle equipped with a tire to be tested, as shown in FIG. 8 (a), as shown in FIG. 8A, an arc part a having a certain radius and a protruding part protruding from the arc part a In general, a method is used in which a tire is run on a drum d having an outer peripheral surface having b and a vertical vibration of 30 Hz or less below the spring when the tire passes over the protrusion b is measured. In this case, a tire with good riding comfort appears with lower vertical vibration of 30 Hz or less than a tire with poor riding comfort.

  By the way, the conventional protrusion b is made of a metal block having a triangular shape having a sharp protruding corner b1 protruding outward in the drum radial direction in a cross section perpendicular to the rotation center axis of the drum d. It is being fixed to the part a with fixing tools, such as a volt | bolt. Related technologies include the following.

Japanese Patent Publication No. 4-37376

  However, in the protrusion b as described above, as shown in FIG. 8 (b), when the tire passes over the protrusion, vertical vibration and longitudinal vibration of 30 to 50 Hz are also excited. The vertical vibration tends to be greatly amplified. With such a protrusion, there is a problem that the difference in vertical vibration of 30 Hz or less between the tire B with good riding comfort and the tire A with poor riding comfort cannot be clearly expressed, and it becomes difficult to evaluate the riding comfort. It was.

  As a result of intensive studies, the inventors have suppressed the vertical vibration of 30 to 50 Hz and the excitation of the longitudinal vibration and the vertical vibration of 30 Hz or less by making the protrusions have a sine wave shape that rises smoothly. It was found that it can be expressed accurately and ride comfort can be easily evaluated.

As described above, the main object of the present invention is to provide a test method for the tire overpass performance of a tire that can improve the evaluation performance of ride comfort.

According to one aspect of the present invention has a cylindrical drum that has and rotary driving and braking a running surface which is tested tire may travel on the outer peripheral surface is rotatably supported, said drum The outer peripheral surface has a cross section perpendicular to the center axis of rotation, and the protrusion performance of the tire is evaluated using a test device including an arc portion having a substantially constant radius and a protrusion protruding from the arc portion. A step of setting a maximum height h (m) of the protrusion and a vehicle speed for evaluating riding comfort as a rotational speed v (m / s) of the drum On the basis of the step of setting the evaluation frequency f (Hz) of the tire, the evaluation frequency f (Hz), the rotational speed v (m / s) and the maximum height h (m). The contour shape of the protrusion is defined as the circumferential length x of the drum. And a step of forming the protrusion y in a sine wave shape satisfying the following formula (1) .

The invention according to claim 2 is the test method of the tire overriding performance of the tire according to claim 1, wherein the evaluation frequency is 30 Hz or less .

  The test apparatus for evaluating the tire overpass performance of the present invention comprises a cylindrical drum having a running surface on the outer peripheral surface on which the tire to be tested can run and supported so as to be capable of rotational driving and braking. Yeah.

  The outer peripheral surface of the drum includes an arc portion having a substantially constant radius in a cross section perpendicular to the rotation center axis, and a protrusion portion that smoothly protrudes in a sinusoidal shape from the arc portion.

  Such protrusions can clearly represent up and down vibrations of 30 Hz or less, suppressing excitation of up and down vibrations of 30 to 50 Hz and longitudinal vibrations as compared with triangular protrusions as in the past. Comfort can be easily assessed.

It is a front view which shows the test apparatus of the protrusion protrusion performance of the tire of this embodiment. It is a front view which expands and shows a projection part. It is a graph which shows the test result (vibration level) of this embodiment. It is a graph which shows protrusion shape (x, y). It is a front view which shows the projection part which consists of a laminated body of a sheet | seat material. It is a front view which shows the testing apparatus of other embodiment. (A) is a graph which shows the acceleration of the unsprung vertical vibration, (b) is a graph which shows the acceleration of the unsprung longitudinal vibration. (A) is a front view which shows the conventional protrusion part, (b) is a graph which shows the conventional test result.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As schematically shown in FIG. 1, the tire overhang performance test apparatus (hereinafter, simply referred to as “test apparatus”) 1 according to the present embodiment includes a tire 10 to be tested, for example, a drum described later. 2 is used to measure the unsprung vertical vibration of 30 Hz or less when the projecting portion 7 provided on the vehicle 2 is moved over, and to evaluate the riding comfort of the vehicle equipped with the tire 10. It is desirable that the tire 10 be evaluated in a normal load state in which a normal rim is assembled, a normal internal pressure is filled, and a normal load is applied in order to bring the tire 10 closer to an actual running state.

  The “regular rim” is a rim determined for each tire in a standard system including a standard on which a tire is based. For example, JAMMA is a standard rim, TRA is “Design Rim”, or ETRTO. Then means "Measuring Rim".

  The “regular internal pressure” is the air pressure specified by the tire for each tire. The maximum air pressure for JATMA is the maximum value described in the table “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURES” for TRA. For ETRTO, “INFLATION PRESSURE”.

  Furthermore, “regular load” is the load that each standard defines for each tire in the standard system including the standard on which the tire is based. The maximum load capacity is specified for JATMA, and the table “TIRE LOAD LIMITS” for TRA. The maximum value described in "AT VARIOUS COLD INFLATION PRESSURES", or "LOAD CAPACITY" for ETRTO.

  The test apparatus 1 includes a cylindrical drum 2 having a traveling surface on which the tire 10 can travel on an outer peripheral surface 2o. In this embodiment, a tire holding device 3 that contacts the tire 10 with the outer peripheral surface 2o of the drum 2 and rotatably supports the tire 10, and a measuring device 4 that can measure a physical quantity of the tire 10 are further provided. It has been.

  The drum 2 has, for example, a support shaft 2s that forms a rotation center axis thereof, and the support shaft 2s is pivotally supported across a pair of support columns 5 fixed to the floor surface. The drum 2 can be rotationally driven by a driver (not shown) at a peripheral speed of 1 to 100 km / h, for example, and is braked by a brake device.

  Further, the outer peripheral surface 2o of the drum 2 includes an arc portion 6 having a substantially constant radius R1 and a protruding portion 7 protruding from the arc portion 6 in a cross section perpendicular to the rotation center axis. For example, the arc portion 6 of the present embodiment has a width of about 500 to 2000 mm and a radius R1 of about 800 to 1600 mm, and is formed larger than the tire 10.

  As shown in FIGS. 1 and 2, a friction sheet material 8 having substantially the same coefficient of friction as that of the dry asphalt road surface is disposed on the outer surface of the arc portion 6 and the protrusion portion 7 of the present embodiment. Such a friction sheet material 8 is useful for reproducing a state close to an actual asphalt road surface on the outer peripheral surface 2 o of the drum 2.

  The tire holding device 3 is a support that rotatably supports a pressing means 11 such as a cylinder fixed to the upper side of the drum 2 and a tire 10 that is assembled with a rim at the lower end of the pressing means 11 and filled with internal pressure. And means 12. Such a tire holding device 3 rotates the tire 10 at substantially the same speed as the outer peripheral surface 2o while applying the normal load to the outer peripheral surface 2o of the drum 2 by pressing by the pressing means 11. .

  Further, the tire holding device 3 of the present embodiment includes a suspension device 13 that absorbs the vertical vibration of the tire 10 between the pressing unit 11 and the support unit 12.

  The suspension device 13 of this embodiment includes a spring portion 13A that expands and contracts in the vertical direction and absorbs vertical vibrations, and a damper portion 13B that attenuates the swinging phenomenon of the spring portion 13A. Such a suspension device 13 can absorb vibration similarly to the suspension mounted on the vehicle, and is useful for reproducing a state close to actual vehicle running.

  The measuring device 4 is attached to the support means 12 and includes a load cell 15 that measures the physical quantity of the tire and an amplifier that amplifies the signal from the load cell 15, and calculates the physical quantity of the tire 10 based on the amplified signal. And a processing device 16 for measurement. As the load cell 15, a load cell 15 that can measure physical quantities related to at least unsprung vertical vibration, and in this embodiment, vertical vibration and longitudinal vibration is employed.

  Then, as shown in FIG. 2, the protruding portion 7 of the present embodiment is formed so as to rise smoothly in a sine wave shape in the cross section. As described above, in the triangular protrusion b having the protruding corner b1 shown in FIG. 8 (a), as shown in FIG. 8 (b), when the tire gets over the protrusion b, 30-50 Hz. The vertical vibration and the longitudinal vibration are also excited, and accordingly, the vertical vibration of 30 Hz or less tends to be greatly amplified.

  Therefore, as a result of intensive studies, the inventors have suppressed the excitation of vertical vibrations and longitudinal vibrations of 30 to 50 Hz by making the protrusions 7 of the present invention rise smoothly in a sinusoidal shape, It has been found that vertical vibrations of 30 Hz or less can be accurately represented and ride comfort can be easily evaluated.

  FIG. 3 shows the vibration levels of the unsprung vertical vibration and the longitudinal vibration of the tire A having a poor ride comfort and the tire B having a good ride comfort (using the test apparatus 1 having the protrusion 7 of the present invention). The result of measuring PSD (Power Spectral Density) is shown. This vibration level is a value obtained by frequency-analyzing a random signal of vibration and dividing the energy per unit time in each frequency band by the effective bandwidth of the frequency filter. The smaller the value, the better the vibration characteristics. is there.

  In this figure, it is shown that the tires A and B both suppress the excitation of vertical vibrations and longitudinal vibrations of 30 to 50 Hz as compared with FIG. 8B. Accordingly, it can be confirmed that the difference in vertical vibration of 30 Hz or less between the tire B having good riding comfort and the tire A having poor riding comfort becomes clear, and the evaluation of the riding comfort can be facilitated.

  As shown in FIGS. 2 and 4, the shape (outline) of the projection 7 is such that the length in the drum circumferential direction is x (m) and the height in the drum radial direction is y (m). It is desirable to form so as to satisfy the relationship of the following formula (1).

... (1)
h: Projection height (m)
f: Tire evaluation frequency (Hz)
v: Drum rotation speed (m / s)

  The protrusion height h (m) is, for example, a vehicle equipped with the tire 10 to be evaluated, riding over the protrusion 7 arranged on the road surface, and the same ride as when driving a real vehicle by the sensation of the test driver. It is set to the maximum height of the protrusion that gives comfort. Thereby, the road surface close | similar to a real vehicle driving | running | working can be reproduced on the drum 2 provided with the projection part 7. FIG.

  Further, the evaluation frequency f (Hz) of the tire 10 is inputted with an arbitrary value of 30 Hz or less, which is an index of riding comfort, and the vehicle for evaluating riding comfort is used as the rotational speed v (m / s) of the drum. Speed is set.

  Note that the projection shape (x, y) shown in FIG. 4 was substituted for h = 0.01 m (10 mm), f = 13 Hz, v = 16.7 m / s (60 km) into the above equation (1). Is the case.

  As described above, by using the above equation (1), the shape of the protruding portion 7 raised in a sine wave shape can be easily obtained according to the protrusion height h, the tire evaluation frequency f, and the drum rotation speed v. it can.

  In addition, although the projection part 7 can also be formed from various materials, such as a metal, it is desirable to form preferably from a soft material with a low density. Such a protrusion 7 has a small mass and can significantly reduce the centrifugal force generated by the rotation of the drum 2, so that even if the protrusion 7 is detached during the rotation of the drum 2, the metal The danger can be reduced compared to the ones.

If the density of the soft material is large, the mass and centrifugal force cannot be reduced as described above, and the risk may not be sufficiently suppressed. Therefore, the density is preferably 1.5 g / cm ³ or less. Is desirable. On the other hand, when the density is reduced, the rigidity of the protrusion 7 does not play a role as a protrusion decreases, preferably 1.0 g / cm ³ or more.

Further, it is desirable that a soft material having a small volume compressibility is employed so that the protrusion 7 can stably generate vibration in the tire. If the volume compression ratio is large, the protrusion 7 may contract when the tire gets over, and vibration may not be stably generated. On the other hand, if the volume compressibility is small, the vibration applied to the tire by the protrusion 7 becomes excessively large, and there is a possibility that the situation close to actual vehicle traveling cannot be reproduced sufficiently. From such a viewpoint, the volume compressibility is preferably 5% or less, and more preferably 3% or more. The volume compression rate is, for example, (h−h ₁ ) / h, where h ₁ is the height of the protrusion when the same pressure (230 kPa) as the internal pressure of the tire is applied in the height direction of the protrusion 7. Desired.

  Although one protrusion 7 is provided in the circumferential direction of the arc 6, two or more protrusions 7 can be provided continuously in order to adjust the magnitude of vibration. If the number of the protrusions 7 is large, vibration is excessively amplified, and the difference in vertical vibration of 30 Hz or less between the tire B and the tire A becomes small, and the ride comfort may not be easily evaluated. is there. From such a viewpoint, the number is preferably 3 or less.

  As shown in FIG. 5, the projecting portion 7 is formed by stacking a plurality of sheet materials 17 having the same thickness and different lengths on the outer peripheral surface of the arc portion 6 on the outer side in the drum radial direction. The protrusion shape (shown in FIG. 4) obtained by the above equation (1) and the above conditions may be formed.

  Such a protrusion 7 can be easily formed into a sinusoidal protrusion shape that is set based on conditions such as the evaluation frequency of the tire, simply by stacking and attaching a plurality of sheet materials 17. In addition, this protrusion 7 is superior in terms of manufacturing cost compared to, for example, a metal one, and it is not necessary to stock a plurality of different protrusions 7 depending on conditions such as the evaluation frequency of the tire. There is no need to secure a storage location for the protrusion 7.

Further, the protruding portion 7, on the outside of the laminate 18 that are stacked stepwise, since covered with friction sheet member 8 can be smoothly formed sinusoidally. Further, the sheet material 17 is preferably a friction sheet material 8. Thereby, since the projection part 7 can be formed from the existing material, manufacturing cost can be suppressed further. The friction sheet material 8 is preferably made of a soft material having a low density and a small volume compressibility as described above.

FIG. 6 shows a test apparatus 1 according to another embodiment.
In the test apparatus 1 of this embodiment, a vehicle 21 equipped with a test target tire 10 is used as the tire holding device 3.

  As the vehicle 21 of this embodiment, an FR vehicle is used, and the vehicle is tested with the front wheels 10F that are not affected by the gears and the parking brake. In the case of an FF vehicle, it is preferable to test the rear wheel 10B.

  Further, the front of the vehicle 21 is pulled by the wire 22, and the rear wheel 10 </ b> B is fixed by the jig 23. Further, the gear of the vehicle 21 is set to parking and a parking brake is applied. As a result, the vehicle 21 is restrained and the backward movement due to the rotation of the drum 2 is prevented.

  The left and right wheels of the drum 2 may be rotated by different drums 2 and 2 or may be rotated by the same drum. Further, two protrusions 7 are continuously arranged in the drum circumferential direction in order to amplify vibration. The load cell 15 is attached to the hub 24 of the front wheel 10F.

  In such a test apparatus 1, the tire 10 attached to the vehicle 21 is rotated by the rotation of the drum 2 and the vibration is measured, so that the ride comfort can be evaluated in a situation closer to actual vehicle travel.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

Using the test apparatus shown in FIG. 6, a tire A having a poor ride comfort and a tire B having a good ride comfort were mounted on the vehicle, and each ride comfort was evaluated. Also. Two protrusions were continuously attached to the outer peripheral surface of the drum. Further, the protrusion shape is set by substituting the protrusion height h = 0.01 m, the tire evaluation frequency f = 13 Hz, and the drum rotation speed v = 16.7 m / s into the above formula (1). A plurality of sheet materials having different lengths are laminated on the outer side in the drum radial direction. The test results are shown in FIG. 3 and FIG.
The common specifications are as follows.
Tire A:
Tire size: 225 / 50R17
Rim size: 17 × 7.5J
Internal pressure: 230 kPa
Tire B:
Tire size: 245 / 45R17
Rim size: 17 × 7.5J
Internal pressure: 230 kPa
Friction sheet material, sheet material:
Product name "Safety Walk" manufactured by Sumitomo 3M Co., Ltd.
Thickness: 0.6mm
Density: 1.2 g / cm ³
Volume compression ratio: 5%

  As a result of the test, as shown in FIGS. 7A and 7B, it was confirmed that both the tires A and B can increase only the vertical acceleration while suppressing the longitudinal acceleration. Thereby, as shown in FIG. 3, the excitation of the vertical vibration of 30 to 50 Hz and the excitation of the longitudinal vibration is suppressed, and the difference of the vertical vibration of 30 Hz or less between the tire A and the tire B becomes clear, and FIG. It was confirmed that the ride comfort can be evaluated more easily than the measurement results using the conventional test apparatus shown in FIG.

DESCRIPTION OF SYMBOLS 1 Test device for evaluating tire protrusion performance 2 Drum 3 Tire holding device 4 Measuring device 6 Arc portion 7 Protrusion portion

Claims (2)

It has a cylindrical drum that has a running surface on which the tire to be tested can run on its outer peripheral surface and is supported so as to be capable of rotational driving and braking, and the outer peripheral surface of the drum is a cross section perpendicular to its central axis of rotation. In, a test method for evaluating the tire overpass performance using a test apparatus comprising an arc portion having a substantially constant radius, and a projection raised from the arc portion ,
Setting a maximum height h (m) of the protrusion;
Setting a vehicle speed for evaluating riding comfort as the rotational speed v (m / s) of the drum;
Setting an evaluation frequency f (Hz) of the tire;
Based on the evaluation frequency f (Hz), the rotation speed v (m / s), and the maximum height h (m), the contour shape of the protrusion is changed to the circumferential length x of the drum and the protrusion. And a step of forming a sine wave in which the height y of the portion satisfies the following formula (1).

The test method of the tire overstep performance of the tire according to claim 1, wherein the evaluation frequency is 30 Hz or less .