JP3929965B2 - Load sensitivity calculation method and apparatus for tire dynamic load radius, and tire load sensitivity calculation program - Google Patents

Description

  The present invention relates to a load sensitivity calculation method and apparatus for a dynamic load radius of a tire, and a tire load sensitivity calculation program. More particularly, the present invention relates to a load sensitivity calculation method and apparatus for a dynamic load radius of a tire that can improve the accuracy of pressure reduction determination, and a tire load sensitivity calculation program.

Conventionally, the tire pressure drop detection device uses the principle that when the tire is depressurized, the outer diameter (dynamic load radius of the tire) is smaller than that of a tire with normal internal pressure, so the rotational angular velocity is increased compared to other normal tires. ing. For example, in the method of detecting a decrease in internal pressure from the relative difference in the rotational angular velocity of the tire,
DEL = {(F1 + F4) / 2- (F2 + F3) / 2} / {(F1 + F2
+ F3 + F4) / 4} × 100 (%)
(Patent Document 1). Here, F1 to F4 are rotational angular velocities of the front left tire, the front right tire, the rear left tire, and the rear right tire, respectively.

  The conventional apparatus uses the difference between the sums of the rotational angular velocities at the diagonals of the four wheels in order to detect tire decompression using so-called decompression sensitivity, in which the dynamic load radius of the tire is reduced by decompression. Therefore, simultaneous decompression of the two front wheels, simultaneous decompression of the two rear wheels, and simultaneous decompression of all the wheels cannot be detected.

  Therefore, as a result of intensive research, the present inventor has shown that there is a correlation between the load sensitivity indicating how much the tire dynamic load radius changes depending on the load load of the vehicle while turning, and the pressure reduction sensitivity of the tire dynamic load radius. And proposed a method for detecting the simultaneous decompression of the tire using this correlation (Japanese Patent Application No. 2003-366395).

  In addition, the conventional device measures the decompression sensitivity, which is the magnitude of the change in the dynamic load radius due to decompression, for each of the preset tires (summer tires and winter tires). By setting a threshold value for sensitivity, there is no significant difference in detection sensitivity even when the tire is replaced. Therefore, the allowable range of the degree of decompression that issues an alarm cannot be reduced, and the set tire It cannot be applied to vehicles with many sizes.

  Therefore, as a result of extensive research, the present inventor has found that since the load sensitivity of the dynamic load radius of the tire has a correlation with the pressure reduction sensitivity, the pressure reduction sensitivity of the tire can be estimated from the load sensitivity. Proposed a method for improving the detection performance of Japanese Patent Application No. 2003-366398.

JP 63-305011 A

  However, in the methods proposed in Japanese Patent Application Nos. 2003-36697 and 2003-366398, the data for obtaining the load sensitivity varies depending on the speed, and there remains a problem that it is difficult to improve the accuracy of the decompression determination. Yes.

  Since the shift amount of the judgment value is proportional to the lateral acceleration and its slope is proportional to the load sensitivity of the tire, the slope of the relational expression between the judgment value and the lateral acceleration is obtained by regression. It takes time and it is difficult to make a pressure reduction judgment quickly.

  In view of the above circumstances, the present invention provides a method and an apparatus for calculating a load sensitivity of a dynamic load radius of a tire, and a load sensitivity calculation of a tire, which can improve the accuracy of pressure reduction determination by improving the accuracy of load sensitivity. The purpose is to provide a program.

  The load sensitivity calculation method for the dynamic load radius of the tire according to the present invention is a load sensitivity calculation method for obtaining the load sensitivity of the dynamic load radius due to the tire load fluctuation, the step of obtaining the lateral acceleration when the vehicle turns, and the vehicle A step of obtaining a shift amount of a judgment value, which is a relative comparison of wheel rotation information on a pair of diagonal lines of the vehicle at the time of turning, and load sensitivity which is a value obtained by dividing the shift amount by a lateral acceleration for each vehicle speed region And a step of obtaining the characteristic.

  Further, the load sensitivity calculation method for the dynamic load radius of the tire according to the present invention is a load sensitivity calculation method for obtaining the load sensitivity of the dynamic load radius due to the tire load fluctuation, and includes a step of obtaining a yaw rate, Obtaining a direction acceleration, obtaining a reciprocal of a turning radius obtained from wheel rotation information and a reciprocal of a turning radius obtained from the yaw rate, a reciprocal of a turning radius obtained from the wheel rotation information for each vehicle speed region, and And a step of obtaining a load sensitivity which is a value obtained by dividing a difference from the reciprocal of the turning radius obtained from the yaw rate by the lateral acceleration.

  Further, the load sensitivity calculation method for the dynamic load radius of the tire according to the present invention is a load sensitivity calculation method for obtaining the load sensitivity of the dynamic load radius due to the tire load fluctuation, and a step of obtaining a lateral acceleration when the vehicle turns. The step of obtaining the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the lateral acceleration, and the reciprocal of the turning radius obtained from the wheel rotation information and the lateral acceleration for each vehicle speed region. And a step of obtaining a load sensitivity which is a value obtained by dividing the difference from the reciprocal of the obtained turning radius by the lateral acceleration.

  The tire dynamic load radius load sensitivity calculation apparatus according to the present invention is a load sensitivity calculation apparatus for obtaining a load sensitivity of a dynamic load radius due to a tire load variation, and is a lateral direction for obtaining a lateral acceleration when the vehicle turns. Acceleration means, shift amount calculation means for obtaining a shift amount of a judgment value that is a relative comparison of wheel rotation information on a pair of diagonal lines of the vehicle when the vehicle is turning, and the shift amount for each vehicle speed region. Load sensitivity calculating means for obtaining load sensitivity, which is a value divided by the direction acceleration, is provided.

  The tire dynamic load radius load sensitivity calculation device according to the present invention is a load sensitivity calculation device for obtaining a load sensitivity of a dynamic load radius due to a tire load variation, a yaw rate detection means for detecting a yaw rate, a vehicle turning Means for obtaining lateral acceleration at the time, reciprocal computing means for obtaining the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the yaw rate, and the wheel rotation information for each vehicle speed region Load sensitivity calculating means for obtaining load sensitivity which is a value obtained by dividing the difference between the reciprocal of the turning radius obtained from the above and the reciprocal of the turning radius obtained from the yaw rate by the lateral acceleration.

  The tire dynamic load radius load sensitivity calculation apparatus according to the present invention is a load sensitivity calculation apparatus for obtaining a load sensitivity of a dynamic load radius due to a tire load variation, and is a lateral direction for obtaining a lateral acceleration when the vehicle turns. Means for acceleration, reciprocal calculating means for obtaining the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the lateral acceleration, and the reciprocal of the turning radius obtained from the wheel rotation information for each vehicle speed region And load sensitivity calculation means for obtaining load sensitivity which is a value obtained by dividing the difference between the reciprocal of the turning radius obtained from the lateral acceleration by the lateral acceleration.

  Further, the tire load sensitivity calculation program according to the present invention uses a computer to obtain the load sensitivity of the dynamic load radius due to the tire load fluctuation, and the relative rotation of the wheel rotation information on a pair of diagonal lines of the vehicle when the vehicle turns. It functions as a shift amount calculation means for obtaining a shift amount of a determination value that is a comparison, and a load sensitivity calculation means for obtaining a load sensitivity that is a value obtained by dividing the shift amount by a lateral acceleration when the vehicle turns for each vehicle speed region. It is characterized by that.

  In addition, the tire load sensitivity calculation program of the present invention uses a computer to calculate the load sensitivity of the dynamic load radius due to tire load fluctuations, and the reciprocal of the turning radius obtained from the wheel rotation information and the turning radius obtained from the yaw rate. A value obtained by dividing the difference between the reciprocal of the turning radius obtained from the wheel rotation information for each vehicle speed region and the reciprocal of the turning radius obtained from the yaw rate by the lateral acceleration at the time of turning of the vehicle. It is characterized by functioning as load sensitivity calculation means for obtaining the load sensitivity.

  Furthermore, the tire load sensitivity calculation program of the present invention uses a computer to calculate the load sensitivity of the dynamic load radius due to tire load fluctuations, the reciprocal of the turning radius obtained from the wheel rotation information, and the lateral direction when the vehicle turns. Reciprocal calculating means for obtaining a reciprocal of the turning radius obtained from the acceleration; and a difference between the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the lateral acceleration for each vehicle speed region in the lateral direction. It is characterized by functioning as load sensitivity calculation means for obtaining load sensitivity, which is a value divided by acceleration.

  According to the present invention, since the load sensitivity is speed-dependent like the decompression sensitivity, the load sensitivity, which is a value obtained by dividing the shift amount of the determination value by the lateral acceleration, is stored for each vehicle speed region. Thus, the load sensitivity at the vehicle speed at the time of turning can be obtained with high accuracy.

  In addition, by storing the load sensitivity, which is a value obtained by dividing the difference between the reciprocal of the turning radius calculated from the wheel speed and the reciprocal of the turning radius calculated from the yaw rate or the lateral acceleration by the lateral acceleration, for each vehicle speed region. The load sensitivity at the vehicle speed during turning can be obtained with high accuracy.

  Therefore, the accuracy of pressure reduction determination can be improved by improving the accuracy of load sensitivity.

  A tire load sensitivity calculation method and apparatus and a tire load sensitivity calculation program according to the present invention will be described below with reference to the accompanying drawings.

  As shown in FIG. 1, a tire pressure drop detecting device to which a load sensitivity calculating device for a dynamic load radius of a tire according to an embodiment of the present invention is applied has four tires FL, FR, RL provided in a vehicle. And normal wheel rotation information detection means 1 provided in association with RR and RR, respectively.

  The wheel rotation information detecting means 1 generates rotation pulses by using an electromagnetic pickup or the like, and rotates like a wheel speed sensor or dynamo for measuring the wheel speed information of the rotation angular velocity and the wheel speed from the number of pulses. It is possible to use an angular velocity sensor including one for generating power using this voltage and measuring the rotational angular velocity and wheel speed from this voltage. The output of the wheel rotation information detecting means 1 is given to a control unit 2 which is a computer such as ABS. Connected to the control unit 2 are a liquid crystal display element for informing a tire whose air pressure has decreased, a display 3 composed of a plasma display element or a CRT, an initialization button 4 that can be operated by a driver, and an alarm 5. Has been. The vehicle is also provided with a yaw rate detection means 6 for outputting a signal corresponding to the yaw rate of the vehicle body. The output of the yaw rate detection means 6 is given to the control unit 2.

  As shown in FIG. 2, the control unit 2 stores an I / O interface 2a necessary for signal exchange with an external device, a CPU 2b functioning as a center of arithmetic processing, and a control operation program for the CPU 2b. The ROM 2c and the RAM 2d into which data is temporarily written or the written data is read when the CPU 2b performs a control operation.

  The wheel rotation information detection means 1 outputs a pulse signal (hereinafter referred to as a wheel speed pulse) corresponding to the number of rotations of the tire. Further, the CPU 2b calculates the rotational angular velocity Fi of each tire at a predetermined sampling period ΔT (sec), for example, ΔT = 1 second, based on the wheel speed pulse output from the wheel rotation information detecting means 1.

By the way, since tires are manufactured with variations (initial differences) within the standard, the effective rolling radius of each tire (the value obtained by dividing the distance advanced by one rotation by 2π) is normal even for all tires. Even air pressure is not necessarily the same. Therefore, the rotational angular velocity Fi of each tire varies. Therefore, for example, there is a method of eliminating the influence of the initial difference from the rotational angular velocity Fi. In this method, first, initial correction coefficients K1, K2, and K3 shown below are calculated.
K1 = F1 / F2 (1)
K2 = F3 / F4 (2)
K3 = (F1 + K1 × F2) / (F2 + K2 × F4) (3)

Next, a new rotational angular velocity F1 _i is obtained using the calculated initial correction coefficients K1, K2, and K3 as shown in equations (4) to (7).
F1 ₁ = F1 (4)
F1 ₂ = K1 × F2 (5)
F1 ₃ = K3 × F3 (6)
F1 ₄ = K2 × K3 × F4 (7)

  Here, the initial correction coefficient K1 is a coefficient for correcting the difference in effective rolling radius due to the initial difference between the front left and right tires. The initial correction coefficient K2 is a coefficient for correcting the difference in effective rolling radius due to the initial difference between the rear left and right tires. The initial correction coefficient K3 is a coefficient for correcting a difference in effective rolling radius due to an initial difference between the front left tire and the rear left tire.

And based on said F1 _i , the wheel speed Vi of the tire of each wheel, the vehicle speed V, a lateral acceleration, etc. are calculated. For example, for the lateral acceleration of the vehicle, in the case of an FR vehicle, the speeds V1 and V2 of the driven wheel tires FL and FR are calculated, and then the turning radius R is calculated by the following equation (8).
R = {(V2 + V1) / (V2-V1)} × T _W / 2 (8)

Here, T _W is the distance between kingpins (tread width) (m).

Based on the turning radius R of the vehicle, the lateral acceleration of the vehicle can be calculated by the following equation (9).
Lateral acceleration = V ² / R (9)

  The lateral acceleration can also be obtained by a lateral acceleration sensor.

Further, in the present embodiment, as shown in the following equation (10), a determination value that is a relative comparison between wheel speeds on a pair of diagonal lines using the pressure reduction sensitivity of the dynamic load radius of the tire is used. That is, the average value of the wheel speeds from the other pair of wheels on the diagonal line is subtracted from the average value of the wheel speeds from the pair of wheels on the diagonal line, and the ratio between the result and the average value of the two totals is calculated. Used as a judgment value.
DEL = {(V1 + V4) / 2- (V2 + V3) / 2} /
{(V1 + V2 + V3 + V4) / 4} × 100 (%) (10)

  Here, V1 to V4 are wheel speeds of the front left tire FL, the front right tire FR, the rear left tire RL, and the rear right tire RR, respectively.

  Since the determination value DEL compares the diagonal sum of the wheel speeds on a pair of diagonal lines, the difference in wheel speed between the outside and inside of the turn is canceled during the turn, and there is no shift of the determination value DEL during the turn. It is a spear. However, in actuality, the judgment value DEL during turning shifts due to the influence of load movement during turning and the influence of slipping of the drive wheels.

(1) That is, first, in a vehicle that is turning, because the load is moved by lateral acceleration toward the outside of the turn, the load applied to the tire on the outside of the turn becomes heavy, and the load applied to the tire on the inside of the turn becomes light. The tire dynamic load radius (wheel speed) changes.

For example, if the increase amount (deceleration amount) of the front wheel tire and the rear wheel tire due to the load movement at the time of left turn is dVf and dVr, the determination value DEL of the equation (10) is
DEL '= {(V1-dVf + V4 + dVr) / 2- (V2 + dVf + V3-dVr) / 2} / {(V1 + V2 + V3 + V4) / 4} × 100 (%)
= {(V1 + V4)-(V2 + V3) -2 * (dVf-dVr)} /
{(2 × V)} × 100 (%) (11)
It is.

Taking the difference between Equation (10) and Equation (11),
ΔDEL = {(dVf−dVr) / V} × 100 (%) (12)
It becomes.

  This ΔDEL is the difference between the wheel speed change (dVf / V) due to the load movement of the front tire and the wheel speed change (dVr / V) due to the load movement of the rear tire, and the shift of the judgment value DEL during turning. It corresponds to the amount. This shift amount does not include the effect of slipping.

  The wheel speed changes (dVf / V) and (dVr / V) are rates of change representing how much the dynamic load radius of the tire changes depending on the load by normalizing with a proportional load movement amount. This is proportional to the load sensitivity of a certain front tire and the load sensitivity of a rear tire.

That is, the change in wheel speed (dVf / V) is proportional to the load movement amount and load sensitivity of the front tire, and the change in wheel speed (dVr / V) is proportional to the load movement amount and load sensitivity of the rear wheel tire. Since the load movement amount of the rear wheel is proportional to the lateral acceleration, the formula (12) is eventually expressed as follows. That is, when the lateral acceleration LG is taken on the X axis and ΔDEL is taken on the Y axis, ΔDEL is proportional to the lateral acceleration LG, and the inclination thereof is proportional to the tire load sensitivity. Note that the% display is omitted.
ΔDEL = α × LG × LSf−β × LG × LSr = (α × LSf−β × LSr) × LG
... (13)

Here, LG: lateral acceleration LSf: front wheel tire load sensitivity LSr: rear wheel tire load sensitivity α, β: coefficient.

Further, if the slope of the relationship between the lateral acceleration LG and ΔDEL (the shift amount of the DEL value) is F1,
F1 = α × LSf−β × LSr (14)
It is.

Further, the load sensitivity LSf, LSr decreases due to a decrease in the pressure reduction sensitivity of the front and rear wheel tires, and assuming that the load sensitivity is proportional to the pressure reduction rate, if the pressure is reduced at the same ratio for all four wheels, the slope F1 ′ after pressure reduction is
F1 ′ = γ × (α × LSf−β × LSr) (15)
It can be expressed as However, | γ | ≦ 1.

(2) Further, the determination value DEL is shifted because the slip caused by driving the lighter turning inner drive wheel is larger than the slip caused by driving the heavier turning outer drive wheel.

When the load movement amount of the front wheel and the rear wheel is the same (equal), the influence of the load movement amount is offset by the calculation of the determination value of the above formula ( 10 ), and therefore the determination value DEL after the slip correction even during turning. Does not shift. However, since the front-to-back ratio of the load movement amount of the vehicle during turning is not 1 and is substantially constant regardless of the magnitude of the lateral acceleration, the corrected determination value DEL shifts.

  However, since the load movement amount is proportional to the lateral acceleration generated by the turn, the shift amount ΔDEL of the determination value DEL after correcting the influence of the slip is also proportional to the lateral acceleration.

(3) Since the judgment value (DEL) during turning is shifted under the influence of the load movement and the slip due to driving, it is usually corrected as follows.
Correction DEL = DEL−F (f1, f2) (16)

  Here, F (f1, f2) is a function of the correction factor, f1 corresponds to the slope F1, and f2 is obtained from the relationship between the judgment value DEL and lateral acceleration × (front and rear wheel ratio−1). Factor. Therefore, F1 can be obtained by correcting only the influence of slip from the DEL value during turning and calculating f1.

  Here, the shift amount of the determination value is essentially zero when the lateral acceleration is zero, and the relationship between the lateral acceleration and the shift amount of the determination value should originally pass through the origin. If the shift amount of the determination value is divided by the lateral acceleration, the inclination is determined in principle at one arbitrary measurement point (measurement value). However, if the four-wheel tires are depressurized by the same amount at the same time, the judgment value when going straight goes to zero, so the measured value during turning = shift amount ΔDEL, so if this measured value is divided by the lateral acceleration LG, The slope can be calculated. If the determination value at the time of straight traveling is not zero, and is shifted by, for example, dDEL, it is necessary to subtract this dDEL from the measured value to calculate the shift amount ΔDEL and to divide by the lateral acceleration LG.

  In the present embodiment, the load sensitivity, which is the inclination, has a speed dependency as described later, as in the case of the pressure reduction sensitivity. Therefore, several vehicle speed regions are provided (for example, 0 to 90 km / h, 90 to 90). 120 km / h, 120 to 150 km / h, 150 km / h or higher), and load sensitivity is obtained for each vehicle speed region. Since the load sensitivity obtained in this way has little variation and good accuracy, the accuracy of the decompression determination can be improved.

  In addition, for tires that could not be detected at low pressure due to zero pressure reduction sensitivity at high speed, it is possible to detect pressure reduction by comparing the load sensitivity at high speed with the load sensitivity in the same vehicle speed range before pressure reduction. Become.

In addition, as a method for obtaining the load sensitivity for each vehicle speed region, for example, 0 to 90 km / h, 90 to 120 km / h, 120 to 150 km / h, 150 km / h or more, and the necessary data in each speed region Determine the score. For example, 90 points, 30 points, 30 points, and 30 points are collected in order, and data is collected in the normal air state in each speed region, and the value of the slope F1 and the speed (V) are averaged to obtain data of 4 points. This is regressed by aV ² + bV + c (function of speed), and constants a, b, and c are obtained. Thereby, the load sensitivity (reference | standard) in each speed is known. If this is compared with the current load sensitivity, a decompression determination can be made.

  Therefore, the load sensitivity calculation device according to the present embodiment includes a lateral acceleration calculation means, a shift amount calculation means for obtaining a shift amount of a determination value during turning of the vehicle, and the shift amount for each vehicle speed region in the horizontal direction. Load sensitivity calculation means for obtaining load sensitivity, which is a value divided by acceleration, is constructed. The lateral acceleration can be obtained by calculating a wheel speed by an arithmetic circuit, and can also be obtained by a lateral acceleration sensor. When the lateral acceleration sensor is used, the lateral acceleration calculation means calculates the lateral acceleration by calculating the lateral acceleration sensor value using a calculation circuit. . The tire load sensitivity calculation program causes the control unit 2 to function as lateral acceleration calculation means, shift amount calculation means, and load sensitivity calculation means.

  In addition, the load sensitivity calculation apparatus according to the present embodiment can be applied to a load sensitivity of a tire dynamic load radius due to load movement at the time of turning in a predetermined vehicle speed region and a new vehicle stored in advance or a tire replacement (normal air pressure). Applied to the tire pressure drop detection device that compares the load sensitivity of the tire dynamic load radius at the time of initialization (comparing the difference or ratio with a predetermined threshold value) to determine the tire pressure drop. can do.

For example, as described above, the load sensitivity at the normal air pressure is expressed by the function of speed f (V) = aV ² + bV + c as a method of detecting the pressure reduction using the load sensitivity obtained for each speed region. Assuming that the difference between the load sensitivity L _SV1 and f (V1) is obtained at the speed V1, and if | L _SV1 −f (V1) | put out. Here, K is a predetermined threshold value.

In the present invention, the load sensitivity of the dynamic load radius of the tire can also be obtained using a yaw rate sensor. For example, assuming that the yaw rate (sensor value) obtained from the yaw rate sensor is YR, the turning radius is R, and the vehicle speed is V,
YR = V / R
It is expressed.

Here, considering the reciprocal of the turning radius R at the time of left turn as the wheel speed change dV due to load movement at the time of turning, from the above equation (8),
1 / R = (2 / T _W ) × {(V2 + dV) − (V1−dV)} / {(V2 + dV) +
(V1-dV)}
= (1 / T _W ) × {(V2−V1) + 2 × dV)} / V (17)
Thus, the speed change due to load movement is an error. Note that (V1 + V2) = V / 2.

On the other hand, if the reciprocal of the turning radius R is calculated from the yaw rate, the wheel speeds V1 and V2 should be true values that are not affected by the load movement.
1 / R ′ = YR / V = (1 / T _W ) × (V2−V1) / V (18)
It is expressed.

Taking the difference between Equation (17) and Equation (18),
1 / R−1 / R ′ = (1 / T _W ) × dV / V (19)
It becomes.

  By normalizing the dV / V with the load movement amount (lateral acceleration), the load sensitivity can be obtained.

  Therefore, as described above, it is possible to provide several vehicle speed regions, obtain the load sensitivity for each vehicle speed region, and improve the accuracy of pressure reduction determination.

  The lateral acceleration can be measured by a lateral acceleration sensor, and can also be obtained by multiplying the yaw rate from the yaw rate sensor by the vehicle speed.

  Thus, in the present embodiment, reciprocal calculation means for obtaining the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the yaw rate, and the turning radius obtained from the wheel rotation information for each vehicle speed region. A load sensitivity calculation means for obtaining load sensitivity, which is a value obtained by dividing the difference between the reciprocal and the reciprocal of the turning radius obtained from the yaw rate by the lateral acceleration, can also be used. In this case, the tire load sensitivity calculation program also functions as reciprocal calculation means and load sensitivity calculation means.

  Next, the present invention will be described based on examples, but the present invention is not limited to such examples.

  In this example, for nine types of tires A to I as shown in Table 1, the tire pressures of all wheels are normal (196 kPa), and the vehicle speeds are 80 km / h and 160 km / h. The drum test was conducted with the above set, and the relationship between the speed and the reduced pressure sensitivity of the dynamic load radius of the tire was investigated. The result is shown in FIG. From FIG. 3, it can be seen that the pressure reduction sensitivity depends on the speed.

  The depressurization sensitivity in this example was determined by dividing the change in the dynamic load radius when the tire pressure was reduced from 196 kPa (normal pressure) to 137 kPa by the dynamic load radius at 196 kPa and expressed in%. The load at this time is 4.41 kN.

  Next, with respect to the same tire as described above, the case where the normal air pressure is 196 kPa and the pressure reduction is 137 kPa, the case where the vehicle speed is 80 km / h and 160 km / h, and the case where the loads are 2.94 kmN and 5.39 kmN are set. A drum running test was conducted to examine the relationship between the sensitivity of pressure reduction of the dynamic load radius of the tire and the load sensitivity. The result is shown in FIG. R in FIG. 4 is a correlation coefficient.

  As can be seen from FIG. 4, even if the speed changes, the correlation between the load sensitivity and the pressure reduction sensitivity remains unchanged. That is, from FIG. 4, the pressure reduction sensitivity and the load sensitivity have speed dependency.

  Therefore, it is understood that the load sensitivity should be measured for each vehicle speed or for each region.

  In addition, FIG. 4 shows that even when the pressure reduction sensitivity is zero, there is a difference between the load sensitivity at 196 kPa and 137 kPa, so that it is possible to detect the pressure reduction using the load sensitivity even under traveling conditions that could not be detected conventionally.

  The load sensitivity was expressed in% by dividing the difference between the dynamic load radius at 2.94 kN and the dynamic load radius at 5.39 kN by the dynamic load radius at 2.94 kN. This was done at speeds of 80 and 160 km / h and air pressures of 196 and 137 kPa.

1 is a block diagram showing a tire pressure drop detecting device to which a load sensitivity calculating device for a dynamic load radius of a tire according to an embodiment of the present invention is applied. FIG. 2 is a block diagram showing an electrical configuration of the tire pressure drop detecting device of FIG. 1. It is a figure which shows the relationship between the speed and the pressure reduction sensitivity of the dynamic load radius of a tire. It is a figure which shows the relationship between the pressure reduction sensitivity of the dynamic load radius of a tire, and load sensitivity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wheel rotation information detection means 2 Control unit 3 Display 4 Initialization switch 5 Alarm device 6 Yaw rate detection means

Claims (9)

A load sensitivity calculation method for obtaining a load sensitivity of a dynamic load radius due to a change in tire load, a step of obtaining a lateral acceleration during turning of the vehicle, and wheel rotation information on a pair of diagonal lines of the vehicle during turning of the vehicle Calculation of load sensitivity of a dynamic load radius of a tire, including a step of obtaining a shift amount of a determination value that is a relative comparison of the vehicle and a step of obtaining a load sensitivity that is a value obtained by dividing the shift amount by a lateral acceleration for each vehicle speed region Method. A load sensitivity calculation method for obtaining a load sensitivity of a dynamic load radius due to a change in tire load, a step of obtaining a yaw rate, a step of obtaining a lateral acceleration during turning of the vehicle, and a reciprocal of a turning radius obtained from wheel rotation information. And calculating the reciprocal of the turning radius obtained from the yaw rate and the difference between the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the yaw rate for each vehicle speed region as the lateral acceleration. A method for calculating a load sensitivity of a dynamic load radius of a tire including a step of obtaining a load sensitivity that is a value obtained by dividing the load sensitivity. A load sensitivity calculation method for obtaining a load sensitivity of a dynamic load radius due to a change in tire load, wherein a step of obtaining a lateral acceleration at the time of turning of the vehicle, a reciprocal of a turning radius obtained from wheel rotation information, and the lateral acceleration The step of obtaining the reciprocal of the turning radius obtained, and the difference between the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the lateral acceleration for each vehicle speed region is divided by the lateral acceleration. A method for calculating a load sensitivity of a dynamic load radius of a tire including a step of obtaining a load sensitivity which is a value. A load sensitivity calculation device for obtaining a load sensitivity of a dynamic load radius due to tire load fluctuation, a lateral acceleration calculation means for obtaining a lateral acceleration at the time of turning of the vehicle, and a pair of diagonal lines of the vehicle at the time of turning of the vehicle Shift amount calculating means for determining a shift amount of a determination value that is a relative comparison of wheel rotation information of the vehicle, and load sensitivity calculating means for determining load sensitivity that is a value obtained by dividing the shift amount by the lateral acceleration for each vehicle speed region; A load sensitivity calculating device for a dynamic load radius of a tire comprising: A load sensitivity calculation device for obtaining a load sensitivity of a dynamic load radius due to a tire load variation, a yaw rate detection means for detecting a yaw rate, a lateral acceleration calculation means for obtaining a lateral acceleration when the vehicle turns, and wheel rotation information Reciprocal computing means for obtaining the reciprocal of the turning radius obtained from the yaw rate and the reciprocal of the turning radius obtained from the wheel rotation information for each vehicle speed region, and the reciprocal of the turning radius obtained from the yaw rate. A load sensitivity calculation device for a dynamic load radius of a tire, comprising load sensitivity calculation means for obtaining load sensitivity that is a value obtained by dividing the difference between the two by the lateral acceleration. A load sensitivity calculation device for obtaining a load sensitivity of a dynamic load radius due to tire load fluctuations, a lateral acceleration calculation means for obtaining a lateral acceleration during turning of a vehicle, a reciprocal of a turning radius obtained from wheel rotation information, and Reciprocal calculation means for obtaining the reciprocal of the turning radius obtained from the lateral acceleration, and the difference between the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the lateral acceleration for each vehicle speed region. A load sensitivity calculation device for a dynamic load radius of a tire, comprising load sensitivity calculation means for obtaining a load sensitivity which is a value divided by a lateral acceleration. Shift amount calculation means for calculating a shift amount of a judgment value, which is a relative comparison of wheel rotation information on a pair of diagonal lines of a vehicle when the vehicle is turning, in order to determine load sensitivity of a dynamic load radius due to tire load fluctuations And a tire load sensitivity calculation program for causing load sensitivity calculation means to obtain load sensitivity, which is a value obtained by dividing the shift amount by the lateral acceleration when the vehicle turns for each vehicle speed region. In order to obtain the load sensitivity of the dynamic load radius due to the tire load fluctuation, the computer, reciprocal calculation means for obtaining the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the yaw rate, and for each vehicle speed region In order to function as load sensitivity calculation means for obtaining load sensitivity, which is a value obtained by dividing the difference between the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the yaw rate by the lateral acceleration during turning of the vehicle. For calculating load sensitivity of tires. In order to obtain the load sensitivity of the dynamic load radius due to the tire load fluctuation, the computer has reciprocal calculation means for obtaining the reciprocal of the turning radius obtained from the wheel rotation information and the reciprocal of the turning radius obtained from the lateral acceleration at the time of turning of the vehicle; A load sensitivity calculation for obtaining a load sensitivity that is a value obtained by dividing a difference between a reciprocal of the turning radius obtained from the wheel rotation information and a reciprocal of the turning radius obtained from the lateral acceleration for each vehicle speed region by the lateral acceleration. A tire load sensitivity calculation program for functioning as a means.

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