JP3277155B2 - Tire wear life prediction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire wear life prediction method, and more particularly to a tire wear life prediction method for predicting a tire wear life in an actual running state.

[0002]

2. Description of the Related Art Conventionally, in order to predict the tire wear life of a vehicle, a vehicle equipped with a tire to be predicted is actually run for a predetermined distance, and the wear life is predicted based on the tire wear state at that time. The way to do it was taken.

However, in this method, it is necessary to accurately measure the amount of wear of the tire in order to make a highly accurate prediction, and it is necessary to increase the distance over which the vehicle travels. There is a problem that it takes time to predict the time.

In order to solve this problem, Japanese Patent Publication No.
According to the technology described in Japanese Patent No. 56374, at least two pairs of test tires are mounted on a test vehicle, and the two pairs of test tires are driven on a real road at a desired rotational speed difference, and the tires are driven by a driving force and a braking force. It is possible to simultaneously evaluate the abrasion state.

On the other hand, there is a Sharalamach wear amount formula as a calculation formula for estimating the tire wear amount. According to this theoretical formula, the tire wear amount M per unit traveling distance is calculated.
Is said to be proportional to the friction energy, (1)
It is expressed by an equation.

M = γρF ² / C (1) where γ is the degree of wear of the tire, ρ is resilience, F is an external force acting on the tire, and C is the rigidity against a force in the front-rear direction or the left-right direction. Here, when the rigidity C is represented by the rigidity Cd in the front-rear direction, that is, the rigidity Cd in the driving direction, the rigidity Cb in the braking direction, and the rigidity Cs in the left-right direction, the Sharalamach's wear amount equation is expressed by the following equation (2).

[0007] ^{M = γρF 2 / (Cd +} Cb + Cs) = γρ (Fx + 2 / Cd + Fx - 2 / Cb + Fy 2 / Cs) (2) where, Fx ₊ the force before they occur by the driving force,
Fx _- the force after generated by the braking force, Fy is a lateral direction input.

[0008]

However, in the technique described in Japanese Patent Publication No. 1-56374, the evaluation time is shortened as compared with the case where one pair of test tires is evaluated on one actual road run. Can do, but at least one
It is necessary to perform a long-time running test on the road, and in this case also, there is a problem that it takes time to predict the tire wear life.

On the other hand, in the above-mentioned Sharalamach wear amount formula, the driving direction, the braking direction, and the stiffness in the left-right direction are taken into consideration. There is a problem that it is difficult to accurately predict the wear life of the mounted tire.

That is, factors that affect the tire wear phenomenon during running of the vehicle on the actual road include the characteristics of the rubber in the tire tread portion, the tread pattern and structure of the tire, and the market running on the tire (when the vehicle actually runs). There are many factors such as input during driving in the situation where the vehicle is used, and these factors affect the wear of the tire when the vehicle is traveling. There is a problem that it is difficult to accurately predict using the Sharamach's wear amount formula that is considered.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a tire wear life predicting method capable of accurately predicting the wear life of a tire in a short time. .

[0012]

According to a first aspect of the present invention, there is provided a tire wear life estimating method for a tire in a state where a friction energy Ewf and a toe angle of the tire during free rolling are given. Friction energy Ew
a is obtained, and the camber angle, the toe angle, and the load are applied in consideration of the dynamic change when the tire is used, the state where the lateral force is applied, and the driving force is applied. Energy Ews, friction energy Ewd, and friction energy Ewb in each of the state where the tire is treaded and the state where the braking force is applied, and the similarity of a rubber sample made of the same material as the tire tread portion when the vehicle is running on the market. Of the friction energy ew and the wear depth W per a predetermined traveling distance are obtained, and the friction energy ew is divided by the wear depth W to obtain a value ew / W.
The tire wear life is predicted on the basis of a value including a product Gi / Ew of a rubber index Gi which is the following formula and a reciprocal 1 / Ew of the friction energy Ew expressed by the following equation.

Ew = Ewf + Ewa + Ews + Ewb + Ewd Here, the principle of the tire wear life prediction method according to claim 1 will be described.

First, it has been assumed that tire wear can be broadly classified into two, a contribution G of the rubber material of the tire tread portion and a contribution E of the tread pattern and structure of the tire.

The rubber wear resistance index Gl (%) of the tire tread obtained by the Lambourn abrasion test is used as the contribution G of the rubber material of the tire tread, and the contribution E of the tread pattern or structure of the tire is taken as the contribution E of the tire. The frictional energy Ew (kgf / cm ² (N / m ² in SI unit system)) at the time of traveling a unit distance per unit area, which is standardized by the rolling radius, was measured and applied. The Lambourn abrasion test is standardized according to JIS K 6264. Among the abrasion tests for vulcanized rubber and other elastic materials, the abrasion resistance is measured using a Lambourn abrasion tester. The wear resistance index Gl
Can be obtained.

The wear resistance index Gl obtained by the Lambourn wear test is described in 1987, 131st A
In CS Meeting No. 79, etc., it is reported that the index is effective as an index indicating the wear performance of the top rubber (rubber surface) of the tire.

Further, regarding the friction energy Ew, 1
In "Preliminary Collection of the 982 Autumn Meeting of the Automotive Engineers of Japan," One Trial on Indoor Evaluation of Tire Wear "(Yokohama Rubber Co., Ltd.), etc., it is effective to evaluate the contribution of tread pattern and structure to tire wear. It is reported that it is a physical quantity.

Therefore, an attempt was made to predict the wear resistance performance of a tire using the rubber wear resistance index Gl and the friction energy Ew.

It is considered that the larger the wear resistance index Gl, the longer the wear life, and the larger the friction energy Ew, the shorter the wear life. Therefore, the wear resistance coefficient m is defined by the following equation (3).

M = Gl / Ew (3) Next, it is considered that the deeper the remaining groove of the tire, the longer the wear life. Therefore, based on the wear resistance coefficient m, the tire wear life expectancy is calculated using the following equation (4). The value Tl was defined.

Tl = m × (NSD-1.6) = (Gl / Ew) × (NSD-1.6) (4) where NSD is the groove depth (mm) of the tire and 1.6.
Corresponds to the remaining groove 1.6 (mm), which is regarded as the tire rejection limit.

Similarly to the Sharamach wear equation, the friction energy Ew is the friction energy Ews of the tire when the lateral force (lateral force) is applied and the friction energy Ews when the driving force is applied. Tire friction energy Ew
d, considering that the frictional energy Ewb of the tire in a state where the braking force is applied is given by the following equation (5).
Transformed into a formula.

Tl = {Gl / (Ews + Ewd + Ewb)} × (NSD-1.6) (5) Next, using the equation (5), five kinds of general market driving inputs are performed. The expected wear life value Tl was calculated, and the wear life of the tire was actually measured by a running test using an actual vehicle.

FIG. 1 is a graph showing the relationship between the calculated expected life expectancy Tl and the wear life obtained by a running test using an actual vehicle. As shown in the figure, there is a low correlation between the expected wear life value Tl and the wear life obtained by the running test using the actual vehicle, and if it is left as it is, the prediction accuracy of the tire wear life finally obtained based on the expected wear life value Tl. Can not be raised.

Next, to clarify the cause of the low correlation,
As a result of examining each friction energy in detail, FIG.
As shown in (C), for each of the four types of tires A to D, the friction energy Ews, Ewd,
Each of Ewb was proportional, as discussed by Sharamach, but the graph did not pass through the origin, and it was found that a positive intercept was present.

Therefore, as a result of examining the positive intercept in detail, the frictional energy Ewf of the tire at the time of free rolling (at the time of free rolling) and the frictional energy Ewa of the tire at the time when the toe angle is given are calculated as follows. It was found to be a major component of the friction energy corresponding to the positive intercept.

From these, the friction energy Ew is calculated using the following equation (6). Ew = Ewf + Ewa + Ews + Ewb + Ewd (6) The expected wear life Tl of the tire is calculated using the following equation (7). It was decided to calculate.

Tl = (Gl / Ew) × (NSD-1.6) (7) Using the above equation (7), the same five kinds of inputs as in the case of studying the above equation (5) are performed. As a result of obtaining the expected wear life value Tl, as shown in FIG. 3, the correlation between the expected wear life value Tl and the wear life obtained by the running test using the actual vehicle becomes higher, and the final value is determined based on the expected wear life value Tl. It has been found that the prediction accuracy of the tire wear life that can be obtained can be improved.

[0029] Since the alignment and the load applied to the tires vary depending on the attitude of the vehicle when the vehicle is running, the factors relating to the dynamic alignment change and the load movement during the vehicle running are friction energies Ews and Ewd. , And Ewb. As this method, friction energy Ews, Ewd,
When obtaining each of Ewb and Ewb, a camber angle, a toe angle, and a load in consideration of a dynamic change when the tire is used are applied to the tire.

As a method of obtaining a camber angle, a toe angle, and a load in consideration of the dynamic change when the tire is used,
5 or more degrees of freedom including front-back (direction), left-right (direction), yawing, rolling, and pitching that cause changes in the dynamic alignment of the running vehicle (including up-down (direction) as necessary) (6 degrees of freedom) were calculated as follows.

First, the camber angle, the toe angle, and the load applied to the tire when obtaining the friction energy Ews are set with the speed and the centripetal acceleration (acceleration with respect to the turning center) during turning of the vehicle. Is used to calculate the camber angle, the toe angle, and the load of the tire mounted on the vehicle during a steady circular turn by computer simulation. Even in various input states such as when the vehicle is running on the market, the vehicle can be replaced with a steady circular turn by setting the representative speed and the representative acceleration of the vehicle as the speed and the centripetal acceleration when the vehicle turns. In practice, it is preferable to use the average speed of the driving mode assumed as the representative speed and the RMS value of the acceleration of the driving mode assumed as the representative acceleration.

The camber angle, the toe angle, and the load applied to the tire when calculating the frictional energy Ewd are determined by setting the driving acceleration of the vehicle and mounted on the vehicle at the time of driving using the vehicle model. Tire camber angle,
The toe angle and the load are calculated by computer simulation. Even in various input states such as when driving in the market, it is possible to replace the vehicle with a constant inertial force state by setting the representative driving acceleration of the vehicle as the driving acceleration of the vehicle. In practice, the RMS value of the acceleration in the driving mode assumed as the representative driving acceleration is used.

Similarly, the camber angle, the toe angle, and the load applied to the tires when the friction energy Ewb is obtained set the braking acceleration of the vehicle and are mounted on the vehicle at the time of braking using the above vehicle model. The camber angle, the toe angle, and the load of the tire are calculated by computer simulation. Even in various input states such as when the vehicle is running on the market, it is possible to replace the vehicle with a constant inertial force state by setting the representative braking acceleration of the vehicle as the braking acceleration of the vehicle. Actually, the RMS value of the acceleration in the driving mode assumed as the representative braking acceleration is used.

On the other hand, the expected life Tl shown in FIG.
The improvement of the correlation between the wear life obtained by the running test with the actual vehicle was not sufficient. As a result of further investigation, the wear surface of the rubber specimen in the Lambourn abrasion test (the state of surface wear) and the use of the actual vehicle It has been found that it is highly likely that this is due to a large difference between the worn skin of the tire tread portion and the tired tire. This is because the severity of the Lambourn wear test (representing the severity of friction, the greater the severity, the greater the slip rate and the friction energy) is much greater than the tire severity in a real vehicle. That is, the allowable range of the slip ratio in the normal Lambourn wear test standardized by JIS K 6264 is from 5% to 80%, and the unit distance travel per unit area when the slip ratio is the minimum of 5%. The range of friction energy at the time is 100 × 10 ^{−5 to} 300 × 10
^-5 (kgf / cm ² ), whereas the range of the friction energy per unit area traveling per unit area when traveling on the market is 10 × 10 ^-5 to 40 × 10 ^-5 (kgf / cm ² ). Yes, this value is very different.

Therefore, using a tester capable of performing a wear test of a rubber test piece at a similarity (slip ratio of about 0.5% to 5%) as that at the time of running on the market, using a tester having a similarity at the time of running on the market. Friction energy ew (kgf / cm ² ) at the time of traveling a unit distance per unit area and wear depth W per predetermined traveling distance (here, 1000 k
m, the wear depth of the rubber test piece (mm / 1000)
km)), and a rubber index Gi is defined by the following equation (8) as an alternative to the frictional resistance index Gl. Gi = ew / W (8) The following equation (9) is calculated using the rubber index Gi. Thus, an attempt was made to calculate the expected wear life Tl of the tire.

Tl = (Gi / Ew) × (NSD-1.6) (9) Using the above equation (9), when the same five kinds of inputs as in the examination of the above equation (5) are performed. As a result of obtaining the expected wear life value Tl, as shown in FIG. 4, the correlation between the expected wear life value T1 and the wear life obtained by the running test using the actual vehicle was obtained by the equation (7) shown in FIG. It is significantly higher than the correlation between the expected wear life Tl and the wear life obtained by the running test with the actual vehicle, and the tire wear life finally obtained based on the expected wear life Tl of the above equation (9). It has been found that the prediction accuracy can be significantly improved.

According to the method for predicting tire wear life according to the first aspect, the friction energy Ewf of the tire during free rolling and the friction energy Ewa of the tire in the state where the toe angle is given are obtained based on the above principle. While the camber angle, toe angle, and the state in which the load is applied, taking into account the dynamic change when the tire is used, the state in which the lateral force is applied, the state in which the driving force is applied, Energy Ews and friction energy Ew in each of the states where the braking force is applied
d and the friction energy Ewb are obtained, and the friction energy ew and the wear depth W per a predetermined traveling distance of the rubber sample of the same material as that of the tire tread portion at the same severity as that at the time of running on the market are obtained. The toe angle at this time is the angle of the tire equatorial plane with respect to the traveling direction,
The lateral force is a force in a direction orthogonal to the rolling direction of the tire, the driving force is a force in the traveling direction of the tire when driving the tire, and the braking force is a force in a direction opposite to the driving force direction during tire braking. Further, when obtaining the friction energy Ewf of the tire during the free rolling, it is preferable to give an initial camber angle of the vehicle to which the tire is mounted.

Thereafter, the friction energy ew is changed to the wear depth W.
And the reciprocal 1 / E of the frictional energy Ew expressed by the above equation (6).
The wear life of the tire is predicted based on a value including the product Gi / Ew with w.

As described above, according to the tire wear life predicting method of the first aspect, the tire friction energy Ews and the driving force applied when the lateral force (lateral force) is applied. Tire friction energy Ewd at
In addition to the tire friction energy Ewb when the braking force is applied, the tire friction energy Ewf during free rolling, and the tire friction energy Ewa when the toe angle is applied, are the tire wear life. Since it is used as an element for predicting the driving direction, the braking direction, and the wear life formula using the Sharalamach wear amount formula that considers only the rigidity in the left-right direction, a more accurate Since the wear life of the tire can be predicted, and the rubber index Gi at the same level of siberity as when driving on the market is measured and used for the prediction of the wear life, the ordinary Lambourne standardized by JIS K 6264 is used. Compared to the case of using the wear resistance index obtained by the wear test, more accurate tire wear life prediction was performed. In obtaining the friction energies Ews, Ewd, and Ewb, the camber angle, the toe angle, and the load are given to the tire in consideration of a dynamic change when the tire is used. Compared to the case where the camber angle, the toe angle, and the load are not applied, it is possible to more accurately predict the wear life of the tire.

As in the tire wear life predicting method according to the second aspect, in the tire wear life predicting method according to the first aspect, the value including the product Gi / Ew is equal to the product Gi / Ew.
It is preferable that the value be one of the value of Ew and the value obtained by multiplying the product Gi / Ew by the depth of the remaining groove until reaching the tire rejection limit. Here, the remaining groove depth up to the tire rejection limit uses a value obtained by subtracting a value regarded as a tire rejection limit, for example, 1.6 (mm) from the tire groove depth NSD. Is preferred. Further, the groove depth NSD of the tire at this time may be, for example, an average value of a plurality of groove depths of the tire tread portion or a minimum value of the plurality of groove depths of the tire tread portion.

According to a third aspect of the present invention, there is provided the tire wear life predicting method according to the first or second aspect, wherein each of the friction energy Ews, the friction energy Ewd, and the friction energy Ewb is different from each other. , A forward force Fx ₊ generated by the driving force, and a rearward force F generated by the braking force.
x _-, undetermined coefficients S, using D, B and indices ns, nd, and ^{nb, Ews = S × Fy ns} , Ewd = D × Fx + nd, Ewb =
B × Fx ₋ ^nb , where the undetermined coefficients S, D, B and the indices ns, n
d and nb are the input Fy in the left and right direction, the force Fx ₊ in the forward direction,
And the rear force Fx _- frictional energy when the respective imparting Ews, the friction energy Ewd, and friction energy Ewb, determined in advance based on each of the measurement values of the right and left direction of the vehicle center of gravity position at the time of market driving Of the acceleration distribution of the vehicle and the acceleration distribution in the longitudinal direction of the position of the center of gravity of the vehicle
Input Fy of the right and left directions based on the value, the forward force Fx _+, and the direction of the force Fx after the _- determines the input Fy of determined the lateral direction, the front direction of the force Fx _+, and said rear force Fx _- and, based on the above formula, the friction energy Ews, the friction energy Ewd, and obtaining the friction energy Ewb.

According to the tire wear life prediction method of the third aspect, each of the friction energy Ews, the friction energy Ewd, and the friction energy Ewb in the tire wear life prediction method of the first or second aspect is left and right. Direction input Fy, forward force Fx generated by driving force
_+, A force in a direction after it generated by the braking force Fx _-, undetermined coefficients S, D, B and indices ns, nd, with ^{nb, Ews = S × Fy ns} (10) Ewd = D × Fx + nd (11 ) Ewb = B × Fx ₋ ^nb (12) where undetermined coefficients S, D, B and indices ns, nd,
nb gives a frictional energy Ews, a frictional energy Ewd, and a frictional energy E when a left-right input Fy, a forward force Fx ₊ , and a rearward force Fx _- are applied, respectively.
wb, and is determined in advance based on the respective measured values of wb. In addition, each of the left-right direction, the front direction, and the rear direction in the above is a direction with respect to the traveling direction of the tire when the tire is rotated.

On the other hand, based on the RMS values of the acceleration distribution in the lateral direction of the center of gravity of the vehicle and the acceleration distribution in the longitudinal direction of the center of gravity of the vehicle during running on the market, the input Fy in the left and right directions, the forward force Fx ₊ , force Fx _- are determined. Here, the RMS value is a value obtained by the square root of the average value of the square of each acceleration in a predetermined range in each acceleration distribution.

Further, the input Fy in the left-right direction, the forward force Fx ₊ , and the rearward force Fx determined as described above.
_-, And based on the above equations (10) to (12), that is, by substituting these values into the above equations (10) to (12), the friction energy Ews, the friction energy Ewd, and the friction energy Ewb are obtained. Is required.

As described above, according to the tire wear life prediction method of the third aspect, the friction energy Ews,
Friction energy Ewd and friction energy Ewb are:
It is determined based on the RMS value of each of the left-right acceleration distribution of the vehicle center of gravity position and the longitudinal acceleration distribution of the vehicle center of gravity position during market driving, and thus reflects the input during market driving. Therefore, it is possible to more accurately predict the wear life of the tire as compared with the case where the input during market driving is not reflected.

According to a fourth aspect of the present invention, there is provided the tire wear life predicting method according to the first or second aspect, wherein each of the friction energy Ews, the friction energy Ewd, and the friction energy Ewb is different from each other. , A forward force Fx ₊ generated by the driving force, and a rearward force F generated by the braking force.
x _-, undetermined coefficients S, using D, B and indices ns, nd, and ^{nb, Ews = S × Fy ns} , Ewd = D × Fx + nd, Ewb =
B × Fx ₋ ^nb , where the indices ns, nd, and nb are values from 1.5 to 3, and the undetermined coefficients S, D, and B are input to the input Fy in the left-right direction, the force Fx ₊ in the forward direction, and force Fx _- each imparting friction energy Ews of time, the friction energy Ewd, and friction energy Ewb, of previously obtained based on each measurement value, the left and right direction of the acceleration of the vehicle center of gravity position at the time of market driving The input Fy in the left-right direction, the force Fx _{+ in the} front direction, and the force Fx in the rear direction based on the distribution and the RMS value of the acceleration distribution in the front-rear direction of the position of the center of gravity of the vehicle.
_- determining the input Fy of determined the lateral direction, the front direction of the force Fx _+, and the rear force Fx _- and, based on the above formula, the friction energy Ews, the friction energy Ewd, And the friction energy Ewb is determined.

According to the tire wear life predicting method of the fourth aspect, the indices ns, nd, nb obtained based on the measured values in the tire wear life predicting method of the third aspect.
Is a value from 1.5 to 3, more preferably a value from 2 to 3, and the undetermined coefficients S, D, and B are the input F in the horizontal direction.
y, the frictional energy Ews and the frictional energy E when the forward force Fx ₊ and the backward force Fx ₋ are applied, respectively.
wd and friction energy Ewb are obtained in advance based on the measured values.

Therefore, according to the tire wear life prediction method of the fourth aspect, the same effect as that of the tire wear life prediction method of the third aspect can be obtained, and the indexes ns, n
Since d and nb are fixed values of 1.5 to 3, the exponent ns,
The undetermined coefficients S, D, and B can be easily obtained as compared with the case where nd and nb are not fixed values.

When the vehicle makes a right turn and a left turn, the friction energy at the same generated force with respect to the tire mounted on the vehicle is different, but the generated force is also different due to the influence of the toe angle and the like. It is known that the generated force differs between a right turn and a left turn in addition to the influence of the toe angle and the influence of the difference in the actual steering angle of the left and right wheels due to the Ackerman characteristic of the vehicle. Therefore, the input Fy in the left-right direction is calculated as the cornering power Cp (kgf / rad),
Using the toe angle θ _toe (rad) and the difference θ between the actual steering angles of the left and right wheels due to the Ackerman characteristic θ Ackerman (rad), the following formulas (13) and (14) are used to calculate the right-left direction when turning right. an input Fy _+, the right and left direction when the left turn input Fy _- 2
It is preferable to consider the two equations.

Fy ₊ = (Fy / 2 ^1/2 ) + [Cp × {θ _toe + (θ Ackerman / 2)}] (13) Fy ₋ = (Fy / 2 ^1/2 ) − [Cp × Δθ _toe + (θ Ackerman / 2)}] (14) Accordingly, the frictional energy Ews of the tire in the state in which the lateral force is applied also increases in the state in which the lateral force in the right turn is applied. friction energy Ews the friction energy Ews _+, in a state in which the lateral force when turning left is granted
_- divided into and is preferably represented by the following equation (15).

[0051] _{Ews = Ews + + Ews - (} 15) where the difference between the actual steering angle of the left and right wheels by the Ackerman characteristic θ Ackerman is calculated as follows.

That is, assuming a steady circular turn that generates a left-right input (preferably an RMS value) of the vehicle at the average speed of the vehicle obtained from the market input, the turning radius is calculated, and the circular turning is performed at the speed 0. Then, the actual steering angles of the left and right wheels at which the slip angles are both 0 when the vehicle travels are calculated. (Ideal Ackerman) And since the actual vehicle has no Ackerman (parallel link) and an Ackerman characteristic that is about the middle of the ideal Ackerman, half of the above calculated value is used as the actual value of the left and right wheels based on the Ackerman characteristic of the vehicle. It is assumed that the steering angle difference θ is Ackerman.

If the vehicle has Ackerman characteristics,
It may be used as it is. Also, a left-right input Fy ₊ when turning right and a left-right input Fy when turning left.
_- it may be calculated by a computer simulation using the above 5 or more degrees of freedom of the vehicle model. In this case, since the difference between the slip angles of the left and right wheels due to yawing can also be taken into account, the prediction accuracy of the wear life becomes higher.

Therefore, the tire wear life prediction method according to claim 5 is the tire wear life prediction method according to claim 1 or 2, wherein the friction energy Ews is
Based on the Ackerman characteristic and the toe angle of the vehicle, the friction energy Ews ₊ when the vehicle in the case of mounting the tire on the vehicle is turning right, the friction energy Ews when the vehicle turns left _- calculated separately in the , the friction energy Ews, and the friction energy Ews _+, the friction energy Ews _- sum of Ews ₊ + Ews _- by seeking.

A method for predicting tire wear life according to claim 5
According to this, the tire wear life according to claim 1 or 2
In the prediction method, the friction energy Ews is calculated based on the vehicle energy.
Based on the Kerman characteristics and toe angle, tires can be
Friction energy when the vehicle turns right when mounted
Ews₊And the friction energy E when the vehicle makes a left turn
ws_-And the friction energy Ews is calculated as
Friction energy Ews ₊And friction energy Ews_-When
Sum Ews₊+ Ews_-Required by

As described above, according to the tire wear life prediction method of the fifth aspect, the friction energy Ews in the tire wear life prediction method of the first or second aspect is described.
But on the basis of the Ackerman characteristic and the toe angle, the friction energy Ews ₊ when the vehicle when fitted with a tire on the vehicle is turning right, the friction energy Ews when the vehicle turns left _- sought separately to the and the friction energy Ews, the friction energy Ews _+, the friction energy Ews _- sum of Ews ₊ + Ews _- by so determined, as compared to the case of obtaining the friction energy Ews not based on the Ackerman characteristic and the toe angle, more It is possible to obtain the friction energy Ews close to the situation when the vehicle is running.

In addition to the Ackerman characteristics and the toe angle described above, it is possible to consider the influence of compliance steer and the like.

[0058] Also, the tire wear life prediction method according to claim 6, wherein, in the tire wear life prediction method according to claim 5, wherein the friction energy Ews _+, the friction energy Ews _-, the friction energy Ewd, and the friction energy Each of Ewb is input to the left and right direction Fy ₊ when the vehicle turns right, input to the left and right direction Fy ₋ when the vehicle turns left, and forward force F generated by the driving force.
x ₊ , rearward force Fx ₋ generated by the braking force, undetermined coefficients S1, S2, D, B and indices ns1, ns2, n
d, with _{nb, Ews + = S1 × Fy} + ns1, Ews - = S2 × Fy -
^ns2 , Ewd = D × Fx ₊ ^nd , Ewb = B × Fx ₋ ^nb, and the undetermined coefficients S1, S2, D, B and the indices ns1, ns2, nd, nb are input to the left and right input F
y ₊ , the input Fy _{− in the} left-right direction, the force Fx _{+ in} the forward direction, and the friction energy Ews ₊ , the friction energy Ews ₋ , and the friction energy E when the force Fx _{− in the} rear direction are applied.
wd and the frictional energy Ewb, which are obtained in advance based on the RMS values of the acceleration distribution in the left-right direction of the center of gravity of the vehicle during market driving and the acceleration distribution in the front-rear direction of the position of the center of gravity of the vehicle. Input F in the left and right direction
y ₊ , the input Fy _{− in the} left-right direction, the force Fx in the front direction
_+, And the rear force Fx _- determining the input Fy ₊ the determined the lateral direction, the right and left direction input Fy _-,
The forward force Fx _+, and the rear force Fx _- and,
Based on the above equation, the friction energy Ews ₊ , the friction energy Ews ₋ , the friction energy Ew
d and the friction energy Ewb are determined.

According to the tire wear life prediction method of the sixth aspect, the friction energy Ews ₊ and the friction energy Ew in the tire wear life prediction method of the fifth aspect are described.
s _-, friction energy Ewd, and friction energy Ew
b is an input F in the left-right direction when the vehicle makes a right turn
y ₊ , a left-right input Fy ₋ when the vehicle makes a left turn,
Force direction before they occur by the driving force Fx _+, a force in a direction after generated by the braking force Fx _-, undetermined coefficients S1, S2,
D, using B and indices ns1, ns2, nd, and _{nb, Ews + = S1 × Fy} + ns1 (16) Ews - = S2 × Fy - ns2 (17) Ewd = D × Fx + nd (18) Ewb = B × Fx _- denoted as ^nb (19), undetermined coefficients S1, S2, D, B and indices ns
The friction energy Ew when 1, ns2, nd, and nb respectively apply a left-right input Fy ₊ , a left-right input Fy ₋ , a forward force Fx ₊ , and a rearward force Fx _−.
s _+, the friction energy Ews _-, friction energy Ew
d and the friction energy Ewb are obtained in advance based on the measured values. In addition, each of the left-right direction, the front direction, and the rear direction in the above is a direction with respect to the traveling direction of the tire when the tire is rotated.

On the other hand, the left-right input Fy ₊ , the left-right input Fy ₋ , the right-left input Fy ₋ , the right-left input Fy ₋ , The directional force Fx ₊ and the backward force Fx _- are determined. Here, the RMS value is a value obtained by the square root of the average value of the square of each acceleration in a predetermined range in each acceleration distribution.

[0061] Furthermore, input Fy ₊ in the determined horizontal direction by the above, the lateral direction input Fy _-, before the direction of the force F
x ₊ , the rearward force Fx _−, and the above formulas (16) to (1)
9), that is, these values are set to the above (1)
Friction energy Ews by substituting 6) to (19) _+, the friction energy Ews _- friction energy Ewd, and friction energy Ewb is obtained.

[0062] Thus, according to the tire wear life prediction method according to claim 6, friction energy Ews in a tire wear life prediction method according to claim 5 _+, the friction energy Ews - _friction energy Ewd, and friction energy Ewb is obtained based on the RMS value of each of the lateral acceleration distribution of the vehicle center of gravity position and the longitudinal acceleration distribution of the vehicle center of gravity position during market driving, and reflects the input during market driving. Therefore, it is possible to more accurately predict the wear life of the tire as compared to a case where the input during market driving is not reflected.

A tire wear life prediction according to claim 7
The method is the tire wear life prediction method according to claim 5.
And the friction energy Ews₊, The frictional energy
Ews_-, The friction energy Ewd, and the friction energy
The left and right of the energy Ewb when the vehicle turns right
Direction input Fy₊, When the vehicle turns left
Input Fy_-, The forward force F generated by the driving force
x₊, The rearward force Fx generated by the braking force_-, Undecided
Coefficients S1, S2, D, B and exponents ns1, ns2, n
Using d and nb, Ews₊= S1 × Fy₊ ^ns1, Ews_-= S2 × Fy_-
^ns2, Ewd = D × Fx₊ ^nd, Ewb = B × Fx_- ^nb And the indices ns1, ns2, nd, nb are 1.5
The undetermined coefficients S1, S2, D, B
To the input Fy in the left-right direction₊, Left and right input Fy _-,Previous
Direction force Fx₊, And rearward force Fx_-Respectively
Friction energy at time Ews₊, Friction energy Ews
_-, Friction energy Ewd, and friction energy Ew
b, determined in advance based on the measured values of
The acceleration distribution in the left and right direction of the center of gravity of the vehicle during traveling, and the vehicle
Based on the RMS value of the acceleration distribution in the front-rear direction at both center of gravity positions
Input Fy in the left-right direction₊, The input Fy in the left-right direction
_-, The forward force Fx₊, And the rearward force Fx_-
Is determined, and the determined input Fy in the left-right direction is determined.₊And said
Left-right input Fy_-, The forward force Fx₊And before
Post-writing force Fx_-And, based on the above equation, the friction
Energy Ews₊, The frictional energy Ews_-,Previous
The friction energy Ewd and the friction energy Ew
Find b.

According to the tire wear life predicting method of the present invention, the indexes ns1, ns2,
nd and nb are values of 1.5 to 3, more preferably 2
As undetermined coefficients S1, S2, D, B
But the left-right direction inputs Fy _+, the lateral direction input Fy _-, forces forward Fx _+, and rear force Fx _- frictional energy when the respective imparting Ews _+, the friction energy Ews
_- , Friction energy Ewd, and friction energy Ew
b, is obtained in advance based on each measurement value.

Therefore, according to the tire wear life predicting method of the seventh aspect, the same effect as that of the tire wear life predicting method of the sixth aspect is obtained, and the indexes ns1, n
Since s2, nd, and nb are fixed values of 1.5 to 3, the undetermined coefficients S1, S2, D, and B are easily obtained as compared with the case where the exponents ns1, ns2, nd, and nb are not fixed values. be able to.

By the way, the wear resistance of a tire is often evaluated based on the average value of the depth of the remaining grooves in the tire tread portion, the average value of the tire as a whole such as the amount of weight reduction of the tire, etc. When a tire is actually mounted on a vehicle and used, the wear of the tire will be uneven in the tread width direction.If the most severely worn part reaches the tire rejection limit, the other parts will be rejected. Even if the limit has not been reached, it is often considered a rejection limit. For this reason, it is preferable to predict the distribution of the wear amount in the tread width direction, instead of predicting the wear resistance performance based only on the average value of the entire tire.

Therefore, a tire wear life predicting method according to claim 8 is the tire wear life predicting method according to any one of claims 1 to 7, wherein the tire wear life is predicted at a plurality of locations on the tire. I do.

As described above, according to the tire wear life predicting method of the present invention, since the wear life of a plurality of places of the tire is predicted, the plurality of places are regarded as a plurality of places in the tread width direction of the tire tread portion. By doing so, the distribution of wear life in the tread width direction (uneven wear) can be predicted.

As in the tire wear life predicting method according to the ninth aspect, in the tire wear life predicting method according to any one of the first to eighth aspects, the frictional energy Ew is the rolling radius of the tire. It is preferable that the frictional energy at the time of traveling a unit distance per unit area, which is standardized by the formula In this case, it becomes possible to mutually compare the prediction results of the wear life of a plurality of tires having different tire sizes.

[0070]

Embodiments of the present invention will be described below in detail with reference to the drawings.

[First Embodiment] The tire wear life prediction method of the first embodiment will be described with reference to the flowchart of FIG.

First, in step 100, a tire (for example, tire size 225/55) for which wear life is to be predicted.
The standard temperature (for example, 25 degrees) of a rubber test piece as a rubber sample of the same material as the rubber of the tire tread portion of the R16 tire)
C) and a rubber index Gi at substantially the same severity as that during driving on the market (a value of the slip ratio in the range of about 0.5% to 5%).

At this time, the rubber index Gi was measured as follows:
For example, it can be performed using a wear test apparatus whose main part is shown in FIG. The present wear test apparatus has a configuration using a Lambourn wear test apparatus, and includes a grindstone drive shaft 2 to which a rotating grindstone 1 which is a rotating body that models a running road surface is attached at one end. The other end of the grinding wheel drive shaft 2 is connected to a rotation drive means such as a servo motor (not shown). The grinding wheel 1 is rotated at an angular velocity ω _d (rad / min) by the rotation driving means via the grinding wheel drive shaft 2.

A rubber test piece drive shaft 3 is provided to extend in parallel with the grindstone drive shaft 2, and a disc-shaped rubber test piece 4 is attached to one end of the rubber test piece drive shaft 3. A holder 5 for holding the motor is provided, and the other end is connected to a rotation drive unit such as a servo motor (not shown), which is separate from the rotation drive unit. Coupling) 90, clutch 6, and torque meter 83
Etc. are provided.

Here, the holder 5 is provided with a receiving pad 5a provided on the rubber test piece drive shaft 3 side and a cylinder disposed directly below the rubber test piece drive shaft 3 by the receiving pad 5a.
And a clamp pad 5b which is displaced forward and backward.
These two pads 5a and 5b sandwich the rubber test piece 4 disposed between them with a predetermined force from the thickness direction of the rubber test piece 4 so that the circumferential surface of the rubber test piece 4 faces the circumferential surface of the grindstone 1. Let it be positioned. Therefore, based on the rotation operation of the rubber test piece drive shaft 3, the rubber test piece 4 rotates at the same speed as the drive shaft 3 together with both pads 5a and 5b.

When the clutch 6 is connected, the rotational force of the rotational drive means is transmitted to the rubber test piece drive shaft 3. When the clutch 6 is released, the rotational force of the rotational drive unit is not transmitted to the rubber test piece drive shaft 3,
The rubber test piece 4 rotates freely.

The rubber test piece drive shaft 3 is mounted on a movable base 7. The movable base 7 is attached to a guide rail 9 laid on the fixed base 8 in a direction orthogonal to the axis of the rubber test piece drive shaft 3 so as to be able to advance and retreat. Therefore, the rubber test piece drive shaft 3 can approach and separate from the grindstone drive shaft 2 while maintaining the parallel state with the grindstone drive shaft 2.

The movable base 7 is moved by a load applying device (not shown), whereby the grindstone 1 and the rubber test piece 4 are pressed. When the grindstone 1 and the rubber test piece 4 are pressed, a longitudinal force is generated on the rubber test piece 4. This longitudinal force can be detected by a force gauge 89 (see FIG. 12).

Here, the longitudinal force refers to a force in a tangential direction of a surface where the grinding wheel 1 and the rubber test piece 4 are in contact with each other, and in FIG. 6, a force in a direction perpendicular to the paper surface.

Further, in order to detect the relative displacement of the movable base 7 with respect to the fixed base 8, a laser displacement meter (displacement sensor) 82 including a light shielding plate 80 and a sensor head 81.
Is provided. The light shielding plate 80 is attached to the movable base 7, and the sensor head 81 is attached to the fixed base 8.

The displacement sensor 82 receives the laser beam emitted from the light emitting portion 81a of the sensor head 81 and enters the light receiving portion 81b according to the amount of the light shielding plate 80 attached to the movable base 7 entering the sensor head 81. The amount of displacement of the movable base 7 with respect to the fixed base 8 from the reference position is detected based on the fluctuation of the light amount.

The reference position of the movable base 7 is such that the distance between the center axis of the rubber test piece 4 and the peripheral surface of the grindstone 1 (rubber test piece 4 side) is equal to the theoretical radius of the rubber test piece 4. This is the position of the movable base 7 with respect to the fixed base 8 when the movable base 7 is positioned as described above.

As shown in FIGS. 12A and 12B, in the present embodiment, a pair of brackets 85 located on the movable base 7 with the declination-allowable coupling 90 interposed therebetween. The bracket 85 protrudes upward.
One end of the swing arm 86 is attached to the upper end portion of the rubber test piece drive shaft 3 at the free end side of the eccentric coupling 90,
In other words, the swing arm 86 is engaged with the rubber test piece drive shaft 3, thereby enabling the swing arm 86 to vertically swing and follow the rubber test piece drive shaft 3 accurately.

Here, the engagement of the swing arm 86 with the rubber test piece drive shaft 3 is preferably carried out via a ball slide unit 87 which allows a relative displacement in the horizontal direction between them. The intermediate portion of the swing arm 86 is also engaged with the rubber test piece drive shaft 3 via the same slide unit 87, whereby the component force of the pressing force of the rubber test piece 4 against the grindstone 1 due to the movement of the movable base 7. The constraint on the total 89 was removed, and only the longitudinal force of the rubber test piece 4 could be correctly detected.

Here, at the upper end of the bracket 85,
A fixed arm 88 having high rigidity is mounted horizontally toward the free end side of the rubber test piece drive shaft 3.
And a direction intersecting the drive shaft between the swing arm 86 and
In the figure, a force gauge 89 for detecting a vertical force is provided.

According to this configuration, as described above, the longitudinal force generated in the rubber test piece 4 is applied to the rubber test piece drive shaft 3,
Since the force is smoothly transmitted to the force sensor 89 via the swing arm 86, the longitudinal force can be detected with high accuracy.

In this case, since a general load cell can be used as the force transducer 89, high measurement accuracy can be maintained for a long time under excellent durability without fear of failure or necessity of maintenance management. , And there is no possibility that the durability of components such as the drive shaft is reduced. Furthermore, since the constricted portion of the drive shaft is not required, the rigidity of the drive shaft is increased, and there is no problem that the sample is bound.

FIG. 13 is a perspective view of a main part showing another embodiment, and FIG.
The distal end portion of the swing arm 86 engaged with the rubber test piece drive shaft 3 and the distal end portion of the fixed arm 88 form the main body portion 8.
8a, and is provided between the gate-shaped protruding portion 88b protruding upward from the gate 8a, and according to this, the gate is provided as compared with those shown in FIGS. 6, 12 (a) and 12 (b). Even if a large force is applied in the direction perpendicular to the front-rear force direction to the oscillating arm that is engaged with the deflected coupling, the component force meter It is protected by 88b and is not affected at all.

In the apparatus shown in FIG. 13B, horizontal shafts 88d are protruded from both ends of a top wall-equivalent portion 88c of the gate-shaped projection 88b shown in FIG. The shaft 88d is bearing-supported by a side wall-equivalent portion 88e. According to this, the top wall equivalent portion 88c is in the axial direction of the horizontal shaft 88d, in other words, the rubber test piece drive shaft 3
The horizontal displacement caused by the load in the direction perpendicular to the longitudinal direction is suppressed by suppressing the horizontal displacement in the direction perpendicular to the axis, and the component force is used to detect the frictional force of the sample in the longitudinal direction. By disposing a bearing in the connection portion between the top wall-equivalent portion 88c and the side wall-equivalent portion 88e where the meter is disposed, the side wall-equivalent portion 88e can be easily rotated and displaced about the axis of the horizontal shaft 88d. Further, by providing the ball slide unit below the fixed arm 88, it is possible to accurately detect the frictional force of the sample with the force gauge.

Next, a method for measuring the rubber index Gi using this wear test apparatus will be described in detail.

First, the mass m1 of the rubber test piece 4 is measured. Further, while holding the rubber test piece 4 in the holder 5 and the clutch 6 of the rubber test piece drive shaft 3 is released, the rubber test piece drive shaft 3 (directly, the movable base 7) is subjected to the above-mentioned load. The loading device is advanced and displaced toward the grinding wheel drive shaft 2 side. Thus, the peripheral surface of the rubber test piece 4 can be pressed against the peripheral surface of the grindstone 1 with a predetermined pressure. When the grindstone 1 is rotated at an angular velocity ω _d by the rotation driving means, the rubber test piece 4 can freely rotate by releasing the clutch 6, so that the rubber test piece 4 rotates at a slip ratio of 0 due to the frictional force on the grindstone 1. (Turn around). In addition,
At this time, the above-mentioned longitudinal force F _o is detected by the force sensor 89.

The distance between the rotation axis of the rubber test piece 4 and the peripheral surface of the grindstone during the corotating rotation is obtained from the displacement of the movable base 7 with respect to the reference position, which is detected by the displacement sensor 82. The rubber specimen 4
Is the effective dynamic load radius Rr. That is, the effective dynamic load radius R
r is the actual radius of the pressure-bonded portion of the rubber test piece 4 to the grindstone 1 during the test.

The distance between the rotation axis of the rubber test piece and the peripheral surface of the grindstone slightly changes depending on the molding error of the rubber test piece 4 and the circumferential contact position between the rubber test piece 4 and the grindstone 1. However, the influence of the change can be sufficiently reduced by measuring the interval a plurality of times during the rotation of the rubber test piece 4 and averaging the measured values.

Note that an effective rolling radius can be applied instead of the effective dynamic load radius.

Next, based on the effective dynamic load radius Rr of the rubber test piece 4 obtained as described above, the slip ratio S (0.5% to 5% (preferably 1% to 3%) is within the range. For example,
2% = S ₀ ) is set based on the equation (20).

[0096]

(Equation 1) Here, ω _s is the angular velocity (rad / min) of the rubber test piece,
R _d is the radius of the rotary grindstone 1.

In setting the slip ratio, in the present wear test, the clutch 6 of the rubber test piece drive shaft 3 was connected, and the peripheral speed (ω _d × R
_d ) and the peripheral speed (ω _s × R _r ) of the rubber specimen 4
This can be realized by providing a peripheral speed difference satisfying the expression (20). That is, by rotating at an angular velocity omega _s obtained the rubber test piece 4 (21), it is possible to set the slip ratio S = S _0.

[0098]

(Equation 2) Here, the slip ratio S in the range of 0.5% to 5% is substantially the same as that in the case of driving on the market if a test is performed by setting the slip ratio S in the range of 0.5% to 5%. This is because the frictional energy at the severity can be realized by the rubber test piece 4. In other words, when the slip ratio exceeds 5%, the wear mode starts to show elastic wear, which is undesirably different from the actual vehicle wear mode. On the other hand, if the slip ratio is less than 0.5%, not only does it take much time but also the amount of wear is reduced, resulting in insufficient accuracy. In consideration of a case where an error occurs, the slip ratio is preferably set in a range of 1% to 3%, more preferably 2%.

As described above, the actual effective dynamic load radius Rr at the time of the test of the rubber test piece 4 is obtained, and the slip ratio is set from the obtained effective dynamic load radius Rr. It can be set with high accuracy. Therefore, the test accuracy of the present wear test can be effectively improved.

Then, the rubber test piece 4 and the grindstone 1 are rotated at a slip ratio S ₀ for a predetermined time. Also, the longitudinal force F ₁ when is rotated at a slip ratio S ₀ component force meter 8
9 to detect. Further, the holding by the holder 5 is released, and the mass m2 of the rubber test piece 4 is measured.

[0102] Then, when the slip ratio 0 (in free rolling, or free during rotation) with the longitudinal force F _1, and the slip ratio S ₀ when the longitudinal force F _0, the slip ratio S ₀ of (22 ), The friction energy ew (kgf / cm ² ) at the time of traveling a unit distance per unit area is determined.

Ew = (F ₁ −F _O ) · S ₀ / (2πR _r · D) (22) Further, the wear depth W (mm / 1000 km) is calculated by measuring the measured wear amount W _O (= m1−m2). ) And (g) to obtain (2)
3) Obtained from the equation. Here, ρ (g / cm ³ ) is the density of the sample, t (min) is the test time, D (cm) is the width of the sample, and V _d (cm / min) is the peripheral speed of the grindstone 1.

[0103]

(Equation 3) Further, the rubber index Gi is obtained by the above equation (8) from the friction energy ew and the wear depth W at the time of traveling a unit distance per unit area obtained by the equations (22) and (23).

When the rubber index Gi is obtained as described above, in step 102 in FIG. 5, the tire for which the wear life is predicted, the tire's friction energy Ewf at the time of free rolling and the tire with the toe angle applied are given. , The frictional energy Ews of the tire when the lateral force is applied, and the frictional energy E of the tire when the driving force is applied.
wd and the frictional energy Ewb of the tire in a state where the braking force is applied. Here, each of the friction energies Ewf, Ewa, Ews, Ewd, and Ewb is a friction energy at the time of traveling a unit distance per unit area standardized by a rolling radius of the tire, and each unit is (kg).
f / cm ² ).

The measurement of each friction energy at this time can be performed by using, for example, a tire tread tread measuring device 10 described in JP-A-7-63658 shown in FIG.

That is, using the grounding section measuring device 10,
At the time of free rolling, the slip amount S in each of the state where the toe angle is applied, the state where the lateral force is applied, the state where the driving force is applied, and the state where the braking force is applied cm) and a shear force τ (kgf) using a three-component force converter 32 provided on the road surface 22.
/ Cm ² ). As described in JP-A-7-63658, the frictional work E of the tire tread is expressed by the following equation (24).

E = ∫τds (24) Accordingly, the slip amount S measured by the contact part measuring device 10
The frictional work of the tire tread is calculated by the equation (24) using the torque and the shearing force τ, and this is used as each frictional energy.

As a method of giving the toe angle at the time of measuring the friction energy Ewa, when the tire 30 is mounted on the upper portion of the tire support 54, the mounted tire 3
The mounting is performed so that the angle with respect to the traveling direction of 0 becomes a desired toe angle. In this case, a camber angle may be given as needed. In order to apply the lateral force, the tire support 54
Is moved leftward and rightward with respect to the traveling direction of the road surface, or by making an angle between the traveling direction of the road surface 22 and the wheel surface. Further, when measuring each of the friction energies Ews, Ewd, and Ewb at this time, a camber angle, a toe angle, and a load in consideration of a dynamic change when the tire is used are applied to the tire. In this case, the camber angle, the toe angle, and the load are determined by computer simulation using a vehicle model having five or more degrees of freedom as described above. As a method of applying the camber angle, the toe angle, and the load obtained as described above to the tire, when the grounding portion measuring device 10 of FIG. 7 is used as a measuring device, the tire 30 is connected to the grounding portion measuring device. When the tire is mounted on the upper portion of the tire support 54 in FIG. 10, the angle of the mounted tire 30 with respect to the vertical direction is the determined camber angle, and the angle of the mounted tire 30 with respect to the traveling direction is the determined toe angle. And the tire 30 is brought into contact with the three-component force converter 32 provided on the road surface 22 so that the pressing force of the tire 30 against the road surface 22 becomes the pressing force corresponding to the determined load. , By making adjustments.

Next, a method for measuring the slip amount S and the shearing force τ of the contact portion of the tire tread using the contact portion measuring device 10 will be described in detail.

[0110] Arbitrary position of the grounding section (for example, block)
When the slip amount S of the tire is measured, marking is performed at an arbitrary position on the tire tread. The tire 30 is rotated so that the marked block is positioned directly above, and the position of the tire support 54 is adjusted so that the marking is positioned directly below the television camera 60. Next, the road surface 22 is moved such that the central portion of the transparent plate 24 is located directly above the marked block. Next, the sub-frame 36 is raised, and the tire tread of the tire is pressed against the transparent plate 24 on the road surface 22. Here, in order to determine the pressing force of the tire 30, the road surface 22 is moved and the tire 30 is brought into contact with the three-component force converter 32 to perform measurement and adjustment.

Next, the road surface 22 is moved to one side in the longitudinal direction of the horizontal frame 18, and the road surface 22 is moved toward the other side in accordance with a predetermined speed, for example, a tire peripheral speed.

As a result, the television camera 60 can catch the center of the photographing area with time from the point at which an arbitrary position on which the tire tread marking is made is in contact with the transparent plate 24 to the point at which it is separated.

In the grounding section measuring device 10, the television camera 6
Since 0 is fixed to the road surface 22, if any position of the road surface 22 that touches the transparent plate 24 does not slip,
The marking is displayed in the center of the screen of the TV monitor in a stationary state.

On the other hand, if an arbitrary position that touches the transparent plate 24 slips, it means that the relative position between the transparent plate 24 and the arbitrary position has shifted, and the image is displayed on the television monitor. Since the marking moves from the center of the screen, this movement amount is measured as the slip amount S.

Therefore, the contact part measuring device 10 can easily track the state from the first contact of the tire tread with the transparent plate 24 on the road surface 22 until the tire tread is separated.

Further, in the contact part measuring device 10, it is not necessary to take an image of the entire contact surface, and a small area (for example, one block) to be measured is substantially filled in the angle of view of the television camera 60, and the slip amount S is reduced. It can measure with high accuracy.

The shearing force τ acting on the ground contact surface is
Is measured by the three-component force converter 32 provided in the first stage.

When the friction energies are measured as described above, in step 104 of FIG. 5, the rubber index Gi measured in step 100 is compared with that of step 102.
The tire wear life expected value Tl is calculated by substituting each of the friction energies measured in the above and the groove depth NSD of the tire into the equation (9). In addition, the groove depth NSD of the tire in the first embodiment is obtained by measuring the groove depths of a plurality of portions of the tire tread portion and calculating an average value thereof in advance. Further, the friction energy Ew in the equation (9) is calculated by the equation (6).

In the next step 106, step 104
The wear life of the tire is predicted on the basis of the expected wear life value Tl calculated in. In this case, the wear life of the tire is predicted by, for example, comparing with the expected wear life value Tl of another tire to predict that the wear life is longer or shorter than that of the other tire, or a certain tire. 4 is prepared in advance, and a method of obtaining a wear life value based on the graph and the calculated expected wear life value Tl is exemplified.

As described above in detail, the method for estimating tire wear life according to the first embodiment uses the tire friction energy Ews when the lateral force is applied and the tire friction energy Ews when the driving force is applied. Tire friction energy Ew
d. In addition to the tire friction energy Ewb when the braking force is applied, the tire friction energy Ewf during free rolling, and the tire friction energy Ewa when the toe angle is applied, Since it is used as an element for predicting the wear life, compared to the case of predicting the wear life using the Sharama Mach's wear amount formula that considers only the driving direction, braking direction, and lateral rigidity, Since it is possible to accurately predict the wear life of the tire and to measure the rubber index Gi at the same level of siberity (slip ratio) as when the vehicle is running on the market, it is used to predict the wear life.
As compared with the case of using a wear resistance index determined by a normal Lambourn wear test standardized by H.264,
More accurate tire wear life prediction can be performed.

Further, the method for predicting tire wear life according to the first embodiment includes the friction energies Ews, Ewd, and Ed.
When measuring wb, a camber angle, a toe angle, and a load were applied to the tire in consideration of a dynamic change at the time of using the tire. When such a camber angle, a toe angle, and a load were not applied, , It is possible to more accurately predict the tire wear life.

Further, the tire wear life predicting method according to the first embodiment measures the rubber index Gi using a wear test device whose main part is shown in FIG. 6 and the friction index using the contact portion measuring device shown in FIG. Since the wear life of the tire can be predicted only by measuring the energy, it is not necessary to perform a running test with an actual vehicle, and the prediction can be performed in a short time.

In the first embodiment, the case where the tire tread tread measuring device 10 (see FIG. 7) described in Japanese Patent Application Laid-Open No. 7-63658 is used to measure each friction energy has been described. However, the present invention is not limited to this. For example, the friction energy was measured in "One Attempt for Indoor Evaluation of Tire Wear" (Yokohama Rubber Co., Ltd.) US Precision Measurement
Tire Pressure an, a ground pressure / displacement measuring device manufactured by Co.
d Slip Plate may be used.

Further, in the first embodiment, the case where the groove depth NSD of the tire is an average value of a plurality of groove depths of the tire tread portion has been described, but the present invention is not limited to this. For example, a configuration may be adopted in which the minimum depth of the plurality of grooves in the tire tread portion is set.

In the first embodiment, the product Gi / Ew of the rubber index Gi and the reciprocal 1 / Ew of the friction energy Ew is multiplied by the value obtained by multiplying the depth of the remaining groove until reaching the tire rejection limit. Although the case of predicting the wear life has been described, the present invention is not limited to this,
For example, when obtaining an approximate value of the expected wear life value Tl,
Only the product Gi / Ew may be used.

Further, in the first embodiment, the case has been described where each friction energy is normalized by the rolling radius. However, the present invention is not limited to this, and the standardization is performed by the rolling radius. It may not be. The unit of each friction energy in this case is (kgf /
cm).

[Second Embodiment] Next, a second embodiment of the present invention will be described. In the second embodiment, the frictional energy Ews of the tire in the state where the lateral force is applied is determined by comparing the frictional energy Ews of the tire when the vehicle turns right when the tire is mounted on the vehicle. Friction energy Ews
₊ And the friction energy Ews in a state in which the lateral force is applied when the vehicle turns left _- divided into the friction energy Ews friction energy Ews ₊ and the friction energy E
ws _- sum of, i.e. Ews ₊ + Ews _- with and request, the friction energy Ews _+, Ews
_- , Ewd, and Ewb reflect the input at the time of driving in the market. Further, in the second embodiment, a plurality of predicted points in the tread width direction of the tire tread portion are defined, and the expected wear life value T at each predicted point is determined.
By calculating 1 or an expected wear amount as required, the uneven wear state of each point in the tread width direction of the tire is predicted. The expected value of the wear amount is determined by the friction energy E
This is obtained by dividing w by the rubber index Gi, and the larger the value, the larger the amount of wear.

Next, a method of estimating a tire wear life (amount of wear if necessary) according to the second embodiment will be described with reference to the flowcharts of FIGS. In the second embodiment, the index n in the above equations (16) to (19) is used.
A case where s1, ns2, nd, and nb are each fixed to 2 will be described.

First, in step 200, a tire tread of a tire (for example, a tire having a tire size of 225 / 55R16) for which the wear life or the wear amount is predicted by the same method as in step 100 of FIG. 5 in the first embodiment. A rubber index Gi at a standard temperature (for example, 25 ° C.) of a rubber test piece as a rubber sample of the same material as that of the rubber of the part and a substantially equality to that at the time of running on the market is determined.

In the next step 202, using the grounding section measuring device 10 shown in FIG. 7, FIG.
The friction energy Ewf and Ewa are measured for one of the predicted points in the same manner as in step 102 of the above.

[0131] In the next step 204, the friction energy derived procedure shown in the flowchart of FIG. 9, the friction in the point of the prediction point on the measurement object in step 202 energy Ews _+, Ews _-, E
wd and Ewb are derived. Below, with reference to FIG. 9, the friction energy Ews _+, Ews _-, Ewd, and Ewb be described procedure of deriving the details.

[0132] First, in step 250, the friction energy Ews _+, Ews _-, Ewd, and Ewb the input Fy ₊ in the left-right direction when the vehicle turns right, the input Fy in the horizontal direction when the vehicle turns left _- the driving force Forward force F generated by
x ₊ , and the rearward force Fx ₋ generated by the braking force,
Undetermined coefficients S1, S2, D, B and indices ns1, ns2,
Using nd and nb, the undetermined coefficients S1, S2, D and B in the case of the above equations (16) to (19) are obtained. Here, the input Fy ₊ in the left-right direction when the vehicle turns right, the input Fy in the horizontal direction when the vehicle turns left - _the power of forward direction generated by the driving force Fx _+, and force after generated by the braking force Fx _- units of is (kgf).

The undetermined coefficients S1, S2, D and B are obtained by the following method, for example. That is, the undetermined coefficient S1
First, frictional energy Ews ₊ is measured for tires whose wear life or wear amount is to be predicted, when a plurality of (preferably three or more) left and right inputs Fy ₊ are applied when the vehicle turns right. , The measured friction energy E
From the equation (16), that is, Ews ₊ / Fy ₊ ² is calculated in reverse from the ws ₊ and the square of the input Fy _{+ in} the left-right direction when the vehicle is turned rightward, which is given to the tire at that time. The undetermined coefficient S1 is obtained, and the average value thereof is obtained. Similarly, the undetermined coefficient S2 is a plurality (preferably three or more) of tires whose wear life or wear amount is to be predicted.
Vehicle in the left-right direction at the time of left turn input Fy of _- friction energy in the case where the applied Ews _- respectively measured, the measured friction energy Ews _- and, in the left-right direction when the vehicle left turn granted to the tire at the time input Fy _- from the square of (1
7) backward from formula, namely Ews _{- /} Fy - ² the calculated seek multiple undetermined coefficients S2, determined as the average value thereof.

The undetermined coefficient D is obtained by measuring a friction energy Ewd when a plurality (preferably three or more) of forward forces Fx ₊ are applied to a tire whose wear life or wear amount is to be predicted. Then, from the measured friction energy Ewd and the square of the forward force Fx _{+ applied} to the tire at that time, back calculation is performed from the equation (18), that is, Ewd / Fx ₊ ² is calculated to obtain a plurality of undetermined values. A coefficient D is obtained and an average value thereof is obtained. Furthermore, the undetermined coefficient B
Is a plurality of (preferably three or more) rearward forces F on a tire whose wear life or wear amount is to be predicted.
x _- measured each friction energy Ewb in the case of imparting a measured friction energy Ewb, force Fx after application to the tire at that time _- from the square of (19)
A plurality of undetermined coefficients B are obtained by calculating backward from the equation, that is, by calculating Ewb / Fx ₋ ^2, and obtaining an average value of them.

In this case, the friction energy Ews ₊ ,
Ews _-, Ewd, and measurement of Ewb is performed for example using a grounding portion measuring device 10 shown in FIG.

In the second embodiment, the frictional energy Ew is set in order to reproduce the operating conditions in an actual vehicle as much as possible.
s _+, Ews _-, Ewd, and when measuring is Ewb, as in the first embodiment, the camber angle in consideration of dynamic changes in use tire, toe angle, and the load to the tire Each friction energy when applied is measured.

In the next step 252, a road (for example, a general road in Japan) which represents a market for which wear life or wear amount is to be predicted is specified, and a vehicle is determined for the specified road. By measuring the acceleration (G) in the left-right direction of the center of gravity of the vehicle and the acceleration (G) in the front-rear direction of the center of gravity of the vehicle when the vehicle travels a predetermined distance at predetermined time intervals, the center of gravity of the vehicle during market driving is measured. , And the acceleration distribution in the front-rear direction of the position of the center of gravity of the vehicle. Each acceleration can be measured by, for example, installing a G sensor at the position of the center of gravity of the vehicle and using the G sensor. FIG. 10A shows an example of the longitudinal acceleration distribution of the vehicle center of gravity position, and FIG. 10B shows an example of the lateral acceleration distribution of the vehicle center of gravity position.

[0138] In the next step 254, the RMS value As of the acceleration distribution in the lateral direction, the RMS value of the acceleration distribution in the front direction Ax _+, and the rear direction of the acceleration distribution of RMS value Ax _- is calculated. Here, the RMS value is a value obtained by the square root of the average value of the square of the acceleration in a predetermined range in each acceleration distribution. Also, the RMS value Ax of the acceleration distribution in the forward direction
₊ When obtaining the the vehicle the RMS value of greater than zero acceleration in the acceleration distribution in the longitudinal direction of the center of gravity position, the RMS value of the acceleration distribution in the backward direction Ax _- when determining the the longitudinal acceleration of the vehicle center-of-gravity position The RMS value of the acceleration smaller than 0 in the distribution is obtained.

[0139] In the next step 256, obtained by the above RMS value As, Ax _+, and Ax _- and, in a state in which the tire load w ₁ in a state in which the lateral force is applied, the driving force is applied The following (2) is obtained by the tire load w ₂ of the tire and the tire load w ₃ in the state where the braking force is applied.
5) to (27) input Fy in the horizontal direction by the equation, the force of the forward Fx _+, and rear force Fx _- a finding. In addition,
The unit of the tire load is (kg).

Fy = w ₁ × As (25) Fx ₊ = w ₂ × Ax ₊ (26) Fx ₋ = w ₃ × Ax ₋ (27) However, as for the forward force Fx ₊ , two driving wheels are provided. In a vehicle with only two wheels, a force for accelerating the entire vehicle must be generated only by two of the drive wheels, so that the sum of the generated forces of the two drive wheels is set as the inertia force of the center of gravity.

[0141] Further, the vehicle in a situation such as to generate a RMS value simulation calculation, the Fx _+, Fx _-, F
y (Fy ₊ , Fy ₋ ) may be obtained.

Thereafter, based on the input Fy in the left-right direction obtained as described above, the following expressions (13) and (14) are used.
Toe angle and Ackerman characteristic of the left and right direction when the vehicle turns right to consider input Fy _+, and the input Fy in the horizontal direction when the vehicle turns left _- a finding.

In the next step 258, the undetermined coefficient S1 obtained as described above and the input Fy _{+ in the} left-right direction are calculated as (1
6) By substituting into equation, friction energy Ews
₊ A, the undetermined coefficients S2 lateral direction input Fy _- and (1
7) Friction energy Ews
_- by substituting a into (19) _- and the friction energy Ewd by substituting the unknown coefficients and D and the front direction of the force Fx ₊ to (18), the undetermined coefficient B and the rear direction force Fx The friction energy Ewb is determined.

[0144] Incidentally, the Fy ₊ in advance the step _{256, Fy -, Fx +,} Fx - if is known, without performing step 250, in step 258, the Fy _+, fy _-, Fx _+, Fx _- conditions directly friction energy by using the ground portion measuring device 10 at Ews _+, Ews _-, Ewd, it is also possible to determine by measuring the Ewb.

As described above, the friction energies Ews ₊ , Ew
s _-, Ewd, and when Ewb is derived, in step 205 in FIG. 8, and determines whether to perform the prediction of wear life, the process proceeds to step 206 when performing the prediction of wear life, the Groove depth N near the prediction point
SD is measured, and in the next step 208, the rubber index Gi measured in step 200 and the friction energy E measured in step 202 are determined.
By substituting wf, Ewa, the friction energies Ews ₊ , Ews ₋ , Ewd, and Ewb derived in step 204 and the groove depth NSD measured in step 206 into equation (9). Then, the expected wear life value Tl at the predicted point is calculated. In addition,
Friction energy Ews used when calculating the friction energy Ew, the friction energy Ews ₊ and the friction energy Ews _- sum of, i.e. Ews ₊ + Ews _- and calculating the.

After the expected wear life value Tl has been calculated, in the next step 210, it is determined whether or not the calculation of the expected wear life value Tl has been completed at all of a plurality of predetermined prediction points. If not, the procedure is terminated after calculating the expected wear life value Tl at each predicted point in steps 202 to 208 until the procedure is completed. Thereafter, the wear life at each prediction point may be predicted using the expected wear life value Tl at each prediction point, or the average of the expected wear life value Tl at each prediction point may be used. The average wear life of the entire tire may be predicted.

On the other hand, if it is determined in step 205 that the wear life is not to be predicted, it is assumed that the wear amount is to be predicted, and the routine proceeds to step 212, where the expected wear amount at the predicted point is determined. With the rubber index Gi measured in step 200, the friction energies Ewf and Ewa measured in step 202, and the friction energies Ews ₊ , Ews ₋ , Ewd and Ewb derived in step 204.
And is calculated based on

After the expected wear amount is calculated, it is determined in next step 214 whether or not the calculation of the expected wear amount has been completed for all of the plurality of predetermined prediction points.
If not completed, the above step 20 is performed until the process is completed.
After calculating the expected value of the wear amount at each prediction point in Steps 2 to 214, the procedure is terminated.

FIG. 11 shows expected wear amounts at seven or six predicted points from the leftmost shoulder in the tread width direction to the rightmost shoulder in the tread width of the three types of tires obtained by the above method. FIG. 11 (A) shows the wear amount of the above-described seven or six places by the actual vehicle on the same graph. FIG. 11 (A) shows the tire size of 225/55.
FIG. 11B is a graph showing a case where the tire of R16 is used as a front tire of a vehicle.
FIG. 11 (C) shows a graph in the case where a tire of / 65R15 is used as the front tire of the vehicle, and FIG. 11 (C) shows a graph in the case where the tire of 175 / 70R14 is used as the front tire of the vehicle. As shown in the drawing, it can be seen that the uneven wear state of the tire in the tread width direction can be predicted with high accuracy from the distribution state of the expected wear amount at each prediction point obtained by the above method.

As described above in detail, the tire wear life predicting method according to the second embodiment is similar to the first embodiment in that the tire friction energy Ews, In addition to the tire friction energy Ewd when the driving force is applied and the tire friction energy Ewb when the braking force is applied, the tire friction energy Ewf during free rolling and the toe angle are applied. Energy E of the tire when it is
Since wa is used as an element for predicting the wear life of the tire, when the wear life is predicted using the Sharama Mach's wear amount formula that considers only the driving direction, the braking direction, and the rigidity in the left-right direction. In comparison, it is possible to more accurately predict the wear life of the tire, and to measure the rubber index Gi at the same level of siberity (slip ratio) as when the vehicle is running on the market, and use it to predict the wear life. Compared to the case of using a wear resistance index determined by a normal Lambourn wear test standardized by JIS K 6264, it is possible to more accurately predict the wear life of a tire.

Further, the tire wear life predicting method according to the second embodiment, when measuring the friction energies Ews, Ewd and Ewb, is similar to the first embodiment, when the tire is used. Since the camber angle, the toe angle and the load in consideration of the dynamic change are applied, more accurate prediction of the wear life of the tire than in the case where the camber angle, the toe angle and the load are not applied. Can be performed.

The tire wear life predicting method according to the second embodiment uses the tire friction energy Ews and the driving force when the lateral force is applied and the driving force is applied according to the first embodiment. Tire friction energy E
wd and the frictional energy Ewb of the tire in the state where the braking force is applied, respectively, the acceleration distribution in the left-right direction of the center of gravity of the vehicle and the acceleration distribution in the front-rear direction of the position of the center of gravity of the vehicle when driving on the market. Is obtained based on the RMS value of the distribution of the tire, the input at the time of driving on the market is reflected, so that the tire wear life can be more accurately compared with the tire wear life prediction method shown in the first embodiment. Can be predicted.

In the method for predicting tire wear life according to the second embodiment, the vehicle is turned to the right based on the Ackerman characteristic and the toe angle based on the frictional energy Ews of the tire in the state where the lateral force is applied. as the sum of _- derived in two and, and a friction energy Ews and the friction energy Ews ₊ frictional energy Ews _- the friction energy Ews ₊ tire when the friction energy Ews of a tire at the time of left turn Since the friction energy Ews is obtained, the friction energy Ews closer to the situation when the vehicle is actually running can be obtained as compared with the case where the friction energy Ews is obtained without being based on the Ackerman characteristic and the toe angle.

Further, in the tire wear life prediction method according to the second embodiment, the expected wear life values Tl (expected wear amount values as necessary) at a plurality of locations in the tread width direction of the tire are obtained. It is possible to predict the distribution (uneven wear) of the wear life (or wear amount) in the tread width direction.

In the second embodiment, when the friction energies Ewf and Ewa are measured, a method disclosed in Japanese Unexamined Patent Publication No. 7-636 is used.
No. 58, a tire tread tread measuring device 10
Although the case of using (see FIG. 5) has been described, the present invention is not limited to this. For example, similarly to the first embodiment, “Preparation of the 1982 Fall Automobile Technology Conference Lecture Collection” One trial for evaluation "(Yokohama Rubber Co., Ltd.) may use a Tire Pressure and Slip Plate, a ground pressure / displacement measuring device manufactured by Precision Measurement Co., which is used for measuring friction energy.

In the second embodiment, the expressions (16) to (16) are used.
As a method of obtaining the undetermined coefficients S1, S2, D, and B in the equation (19), the indices ns1, ns2, nd, and nb are fixed to 2 and each friction energy when a plurality of inputs are performed is measured. Using the input and frictional energy, (1
Although the case where the value is calculated by back calculation using equations 6) to (19) has been described, the present invention is not limited to this.
The index ns1, ns2, nd, and nb are not fixed values, and each friction energy when a plurality of inputs are performed is measured.
The undetermined coefficients S1, S2, D, B and the indices ns1, ns2, nd, nb may be approximately determined from the relationship between each input and the friction energy by the least square method, the deviation area method, or the like. In this case, the indices ns1, ns2, nd,
Compared to the case where nb is a fixed value, more accurate wear life prediction can be performed.

In the second embodiment, the expected wear life value or the expected wear amount value at each of a plurality of predicted points is set to one.
Although the case of calculating each point has been described, the present invention is not limited to this, and as a form of simultaneously calculating a wear life expectation value or a wear amount expectation value after measuring each friction energy at each prediction point. Is also good.

In each of the above embodiments, the camber angle, the toe angle, and the load applied to the tire when measuring each of the friction energies Ews, Ewd, and Ewb in consideration of the dynamic change when the tire is used. Has been described by computer simulation using a vehicle model having five degrees of freedom or more. However, the present invention is not limited to this. For example, the camber angle, toe angle, and load are determined by an actual vehicle running test. You may.

Further, in each of the above embodiments, the case where the wear test apparatus whose main part is shown in FIG. 6 is used to derive the rubber index Gi has been described. However, the present invention is not limited to this. Any device can be used as long as it can measure the wear state at the time of low siberity of about 0.5% to 5%, which is the same as the slip rate at the time of running on the market. For example, the elasticity described in Japanese Patent Application No. 9-7168 can be used. A body abrasion tester may be used.

In each of the above embodiments, when measuring the rubber index Gi, the effective dynamic load radius of the rubber test piece is determined from the displacement of the movable base with respect to the reference position. However, the present invention is not limited to this. Instead, the circumference of the rubber test piece may be obtained, and the rolling radius of the rubber test piece may be obtained from the obtained circumference.

That is, the circumference of the rubber test piece can be obtained as follows. That is, each disk that rotates in synchronization with the rotation of the rubber test piece and the grindstone and that has a notch at the end is disposed corresponding to the rubber test piece and the grindstone. Further, an optical sensor including a light emitting unit and a light receiving unit is provided on each locus of the notch due to the rotation of the disk so as to sandwich the disk. The light sensor generates a pulse when the light from the light emitting unit is received by the light receiving unit. Then, the circumference of the rubber test piece is obtained from the interval between each of the pulses generated from the grindstone side and the rubber test piece side and the circumference of the grindstone.

In each of the above embodiments, when measuring the rubber index Gi, the grindstone is fixed and the rubber test piece is moved and pressed, but the present invention is not limited to this. Move the whetstone by fixing the piece,
The grindstone and the rubber test piece may both be moved to perform pressure bonding.

Further, in each of the above embodiments, the longitudinal force is detected by the force gauge when measuring the rubber index Gi. However, the present invention is not limited to this, and the present invention is not limited to this. The longitudinal force during driving may be measured. However, a torque generated by a bearing or the like is also included, and the measurement accuracy is lower than that measured by the force sensor 89.

Further, in each of the above embodiments, when measuring the rubber index Gi, the angular rate of the grindstone is fixed, and the angular rate of the rubber test piece is adjusted to set the slip ratio. However, the present invention is not limited to this. Instead, the slip rate may be set by adjusting the angular velocity of the grindstone by fixing the angular velocity of the rubber test piece, or by adjusting the angular velocity of both the grindstone and the rubber test piece.

[0165]

According to the tire wear life predicting method of the first and second aspects, the tire friction energy Ews and the driving force in the state where the lateral force (lateral force) is applied are applied. Friction energy Ewd of the tire in the state,
In addition to the tire friction energy Ewb when the braking force is applied, the tire friction energy Ewf during free rolling, and the tire friction energy Ewa when the toe angle is applied, are the tire wear life. Since it is used as an element for predicting the driving direction, the braking direction, and the wear life formula using the Sharalamach wear amount formula that considers only the rigidity in the left-right direction, a more accurate Since the wear life of the tire can be predicted, and the rubber index Gi at the same level of siberity as when driving on the market is measured and used for the prediction of the wear life, the ordinary Lambourne standardized by JIS K 6264 is used. Compared to the case of using the wear resistance index obtained by the wear test, more accurate tire wear life prediction was performed. In obtaining the friction energies Ews, Ewd, and Ewb, the camber angle, the toe angle, and the load are given to the tire in consideration of a dynamic change when the tire is used. As compared with the case where the camber angle, the toe angle, and the load are not applied, it is possible to obtain the effect that the wear life of the tire can be more accurately predicted.

According to the tire wear life predicting method of the third and fourth aspects, the friction energy Ew in the tire wear life predicting method of the first and second aspects is further improved.
s, friction energy Ewd, and friction energy Ewb
Is determined based on the RMS value of each distribution of the lateral acceleration distribution of the center of gravity of the vehicle when traveling on the market, and the acceleration distribution in the longitudinal direction of the center of gravity of the vehicle. Therefore, an effect is obtained that the wear life of the tire can be predicted with higher accuracy as compared with the case where the input during driving in the market is not reflected.

Further, the tire wear life prediction according to claim 5 is provided.
According to the method, the tire wear according to claim 1 or 2
The friction energy Ews in the life prediction method is
Tire mounted on vehicle based on vehicle characteristics and toe angle
Energy Ew when the vehicle makes a right turn
s₊And the friction energy Ews when the vehicle makes a left turn
_-And the friction energy Ews is
Friction energy Ews ₊And friction energy Ews_-When
Sum Ews₊+ Ews_-Acker
Friction energy E based on Man's characteristics and toe angle
Compared to the case of finding ws
It is possible to find a close friction energy Ews
The effect is obtained.

[0168] Also, according to claim 6 and a tire wear life prediction method according to claim 7, wherein the friction in the tire wear life prediction method according to claim 5, wherein the energy Ews _+, the friction energy Ews - _friction energy Ewd, and friction The energy Ewb is obtained based on the RMS value of each of the lateral acceleration distribution of the vehicle center of gravity position and the longitudinal acceleration distribution of the vehicle center of gravity position during market driving, thereby reflecting the input during market driving. It is assumed that
The effect is obtained that the wear life of the tire can be predicted with higher accuracy than when the input during market driving is not reflected.

Further, according to the tire wear life predicting method of the present invention, since the wear life of a plurality of locations of the tire is predicted, the plurality of locations are defined as a plurality of locations in the tread width direction of the tire tread portion. And the distribution of wear life (uneven wear) in the tread width direction can be predicted.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an expected value of tire wear life obtained by equation (5) and a tire wear life measured by an actual vehicle test.

FIG. 2A is a graph showing the relationship between the square of the input and the frictional energy Ews of the tire in a state where a lateral force is applied, and FIG. 2B is a graph showing the relationship between the square of the input and the driving force. And (C) is a graph showing the relationship between the square of the input and the friction energy Ewb of the tire in a state where the braking force is applied.

FIG. 3 is a graph showing a relationship between an expected value of tire wear life obtained by the equation (7) and a tire wear life measured by an actual vehicle test.

FIG. 4 is a graph showing a relationship between an expected value of tire wear life obtained by equation (9) and a tire wear life measured by an actual vehicle test.

FIG. 5 is a schematic flowchart illustrating a procedure of a tire wear life prediction method according to the first embodiment.

FIG. 6 is a plan view illustrating a main part of a wear test device used for measuring a rubber index Gi in the first embodiment.

FIG. 7 is a side view of a tire tread surface contact portion measuring device used to measure each friction energy in the first embodiment.

FIG. 8 is a schematic flowchart showing a tire wear life prediction method according to a second embodiment.

FIG. 9 shows the friction energy Ew in the second embodiment.
s _+, Ews _-, which is a simplified flowchart showing Ewd, and a procedure of deriving the Ewb.

10A is a graph illustrating an example of a longitudinal acceleration distribution of a vehicle center of gravity position in a market, and FIG. 10B is a graph illustrating an example of a lateral acceleration distribution of a vehicle center of gravity position in a market.

11A is a graph showing a relationship between an expected wear amount in a tread width direction of a front tire having a tire size of 225 / 55R16 and a wear amount in an actual vehicle, and FIG. 11B is a front tire having a tire size of 205 / 65R15. Is a graph showing the relationship between the expected value of the amount of wear in the tread width direction and the amount of wear in the actual vehicle, and (C) shows the tire size of 175 / 70R.
14 is a graph showing a relationship between an expected value of a wear amount in a tread width direction of a front tire 14 and a wear amount in an actual vehicle.

12A is a side view showing a portion for measuring a longitudinal force, and FIG. 12B is a side view as viewed from a direction A in FIG. 12A.

FIG. 13 is a perspective view showing a portion for measuring a longitudinal force according to a modification.

[Explanation of symbols]

 Reference Signs List 4 Rubber test piece (rubber sample) 10 Tread surface measuring device for tire tread 30 Tire 32 Three-component force transducer 89 Force gauge

Continued on the front page (72) Inventor Naohiro Sasaka 3-5-326, Ogawahigashi-cho, Kodaira-shi, Tokyo (72) Inventor Hiroshi Kobayashi 1 Toyota-cho, Toyota-shi, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Tetsuyuki Haraguchi 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Yasuyuki Kato 1 Toyota Town Toyota City, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A Hei 5- 107156 (JP, A) JP-A-1-141336 (JP, A) JP-A-4-157341 (JP, A) JP-B-6-63933 (JP, B2) JP-B-46-16681 (JP, B1) U.S. Pat. No. 3,679,843 (US, A) U.S. Pat. on a Vehicle ", SAE Technical Paper Series, USA, SAE, February 25, 1991, 910168, p. 1-8 (58) Field surveyed (Int. Cl. ⁷ , DB name) G01M 17/02 G01N 3/56 G01N 19/02 JICST file (JOIS)

Claims (9)

(57) [Claims] 1. The tire friction energy Ewf during free rolling, the tire friction energy Ewa in a state where a toe angle is given, and the camber angle taking into account the dynamic change when the tire is used. Toe angle and frictional energy Ews, friction in each state of a state where a lateral force is applied, a state where a driving force is applied, and a state where a braking force is applied in a state where a load is applied The energy Ewd and the friction energy Ewb are obtained, and the friction energy ew and the wear depth W per a predetermined traveling distance of the rubber sample of the same material as that of the tire tread portion at a similarity to that at the time of traveling on the market are measured.
Is obtained by dividing the frictional energy ew by the wear depth W.
The product Gi / E of the rubber index Gi that is w / W and the reciprocal 1 / Ew of the friction energy Ew represented by the following equation
A tire wear life prediction method for predicting a tire wear life based on a value including w. Ew = Ewf + Ewa + Ews + Ewb + Ewd 2. A value that includes the product Gi / Ew is the product G / Ew.
The tire wear life predicting method according to claim 1, wherein the value is i / Ew or a value obtained by multiplying the product Gi / Ew by a depth of a remaining groove until reaching a tire rejection limit. 3. The frictional energy Ews, the frictional energy Ewd, and the frictional energy Ewb are respectively converted into a left-right input Fy, a forward force Fx ₊ generated by a driving force, and a rearward force Fx ₊ generated by a braking force. Force Fx
_-, undetermined coefficients S, using D, B and indices ns, nd, and ^{nb, Ews = S × Fy ns} , Ewd = D × Fx + nd, Ewb =
B × Fx ₋ ^nb , the undetermined coefficients S, D, B and the indices ns, nd, nb
The input Fy in the horizontal direction, the forward direction of the force Fx _+, and rear force Fx _- friction energy Ew of when each imparted with
s, friction energy Ewd, and friction energy Ew
b), which are obtained in advance based on the measured values of the vehicle, and the acceleration distribution in the left-right direction of the vehicle center of gravity during market operation and the RMS value of the longitudinal acceleration distribution of the vehicle center of gravity in the left-right direction. Input Fy, the forward force F
x ₊ and the rearward force Fx _- are determined, and the determined left-right input Fy and the forward force F are determined.
x ₊ , the rearward force Fx _−, and the friction energy Ews, the friction energy E
3. The tire wear life prediction method according to claim 1, wherein wd and the friction energy Ewb are obtained. 4. Each of the frictional energy Ews, the frictional energy Ewd, and the frictional energy Ewb is converted into a left-right input Fy, a forward force Fx ₊ generated by a driving force, and a rearward force Fx ₊ generated by a braking force. Force Fx
_-, undetermined coefficients S, using D, B and indices ns, nd, and ^{nb, Ews = S × Fy ns} , Ewd = D × Fx + nd, Ewb =
B × Fx ₋ ^nb , where the indices ns, nd, and nb are values of 1.5 to 3, and the undetermined coefficients S, D, and B are input in the left-right direction input Fy, the forward force Fx ₊ , and the rear force Fx _- frictional energy when the respective imparting Ews, the friction energy Ewd,
And frictional energy Ewb, which are obtained in advance based on the RMS values of the acceleration distribution in the left-right direction of the center of gravity of the vehicle during market driving, and the acceleration distribution in the front-rear direction of the position of the center of gravity of the vehicle. Left-right input Fy, forward force F
x ₊ and the rearward force Fx _- are determined, and the determined left-right input Fy and the forward force F are determined.
x ₊ , the rearward force Fx _−, and the friction energy Ews, the friction energy E
3. The tire wear life prediction method according to claim 1, wherein wd and the friction energy Ewb are obtained. 5. The friction energy Ews ₊ when the vehicle turns right when the tire is mounted on the vehicle, and the friction energy Ews ₊ when the vehicle turns right, based on the Ackerman characteristic and the toe angle of the vehicle. friction energy Ews when _- determined divided into a, the friction energy Ews, the friction energy Ew
and s _+, the friction energy Ews _- the sum of the Ews _{+ +}
Ews _- claim 1 or claim 2 tire wear life prediction method according determined by. Wherein said frictional energy Ews _+, the friction energy Ews _-, the friction energy Ewd, and said each of the friction energy Ewb, the vehicle is in the left-right direction when the right turning input Fy _+, the vehicle is turning left Input Fy _{− in} the left-right direction, the forward force Fx ₊ generated by the driving force, and the rearward force F generated by the braking force.
x _-, undetermined coefficients S1, S2, D, B and indices ns1, n
s2, nd, with _{nb, Ews + = S1 × Fy} + ns1, Ews - = S2 × Fy -
^ns2 , Ewd = D × Fx ₊ ^nd , Ewb = B × Fx ₋ ^nb, and the undetermined coefficients S1, S2, D, B and the exponent ns1,
ns2, nd, and nb are represented by a left-right input Fy ₊ , a left-right input Fy ₋ , a forward force Fx ₊ , and a rearward force F
x _- each friction energy when granted Ews _+, the friction energy Ews _-, friction energy Ewd, and friction energy Ewb, determined in advance based on the measurement values of each of the left and right of the vehicle center of gravity position at the time of market driving The input Fy _{+ in} the left-right direction, the input Fy _{− in the} left-right direction, the force Fx _{+ in the} front direction, and the force Fx _{+ in the} front direction based on the RMS value of the acceleration distribution in the direction and the acceleration distribution in the front-rear direction of the center of gravity of the vehicle. Force F
x _- determines the input Fy of determined the lateral direction _+, the right and left direction of the input Fy _-, the front direction of the force Fx _+, and the rear force Fx _- and, based on the above equation, said friction energy Ews _+, the friction energy Ews _-, the friction energy Ewd, and tire wear life prediction method according to claim 5, wherein the obtaining the friction energy Ewb. Wherein said frictional energy Ews _+, the friction energy Ews _-, the friction energy Ewd, and said each of the friction energy Ewb, the vehicle is in the left-right direction when the right turning input Fy _+, the vehicle is turning left Input Fy _{− in} the left-right direction, the forward force Fx ₊ generated by the driving force, and the rearward force F generated by the braking force.
x _-, undetermined coefficients S1, S2, D, B and indices ns1, n
s2, nd, with _{nb, Ews + = S1 × Fy} + ns1, Ews - = S2 × Fy -
^ns2 , Ewd = D × Fx ₊ ^nd , Ewb = B × Fx ₋ ^nb, and the exponents ns1, ns2, nd, nb are values from 1.5 to 3 and the undetermined coefficients S1, S2, D, B , in the left-right direction inputs Fy _+, the lateral direction input Fy _-, forces forward Fx _+, and rear force Fx _- each friction when applying energy Ews _+, the friction energy Ews _-, friction energy Ewd, and The frictional energy Ewb is determined in advance based on each measured value, and the left and right acceleration distributions of the vehicle center of gravity position during market driving and the RMS values of the vehicle center of gravity position in the front and rear direction are calculated based on the RMS values. Direction input Fy ₊ , the left-right direction input Fy ₋ , the forward force Fx ₊ , and the rearward force F
x _- determines the input Fy of determined the lateral direction _+, the right and left direction of the input Fy _-, the front direction of the force Fx _+, and the rear force Fx _- and, based on the above equation, said friction energy Ews _+, the friction energy Ews _-, the friction energy Ewd, and tire wear life prediction method according to claim 5, wherein the obtaining the friction energy Ewb. 8. The tire wear life prediction method according to claim 1, wherein the wear life of the tire is predicted at a plurality of locations on the tire. 9. The tire wear life prediction according to claim 1, wherein the friction energy Ew is a friction energy at a time of traveling a unit distance per unit area, which is standardized by a rolling radius of the tire. Method.