JP2003312222A - Judging device for tire pneumatic pressure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To precisely estimate tire pneumatic pressure regardless of type of an environmental factor affecting the estimating precision of the tire pneumatic pressure following each estimation rule by effectively using a plurality of estimation rules for estimating the vehicular tire pneumatic pressure. <P>SOLUTION: A resonance frequency estimated value and a dynamic load radius are respectively estimated from the wheel speed detected by each wheel speed sensor for each wheel and following two estimation rules. When a predetermined correlation exists between the two estimated values (S31 and S32) with regards to the tire pneumatic pressure of the same wheel or the same wheel group, the tire pneumatic pressure is judged following at least one of the two predetermined judgement rules corresponding to the two estimation rules (S33 or S35). <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for determining tire air pressure in a vehicle, and in particular,
The present invention relates to a technique for estimating the air pressure of a tire based on the rotation speed of the tire.

[0002]

2. Description of the Related Art There is already a technique for estimating a tire pressure for the purpose of finding an abnormality in a tire of a vehicle while the vehicle is running.

In one example of this technique, a wheel speed sensor for detecting the wheel speed of a wheel in which a tire is mounted on the wheel is mounted on the vehicle body side for use. Tire pressure is estimated by the wheel speed sensor.

Specifically, a reflection value reflecting the tire air pressure is acquired based on the wheel speed detected by the wheel speed sensor, and the tire air pressure is estimated based on the acquired reflection value.

Some specific methods for estimating tire pressure have already been proposed.

One is the dynamic load radius method. In this method, if the tire air pressure changes, the dynamic load radius of the tire changes, and as a result, the rotation speed of the tire, that is, the wheel speed detected by the wheel speed sensor changes, focusing on the phenomenon that Based on the wheel speed, a dynamic load radius reflection value reflecting the dynamic load radius is calculated, and tire air pressure is detected based on the calculated dynamic load radius reflection value.

In this dynamic load radius method, the dynamic load radius reflection value constitutes one example of the reflection value reflecting the tire air pressure. A conventional example of this dynamic load radius method is described in Japanese Patent Laid-Open No. 8-164720.

Another method is a tire vibration method. In this method, attention is paid to the phenomenon that the characteristics of the tire vibration change if the tire air pressure changes, and that change is reflected in the wheel speed, and based on the wheel speed, the tire vibration characteristics are represented. The vibration characteristic value is calculated, and the tire air pressure is detected based on the calculated tire vibration characteristic value.

In this tire vibration system, the tire vibration characteristic value constitutes an example of the above-mentioned reflection value reflecting the tire air pressure.

The tire vibration method includes a resonance frequency method and a disturbance observer method.

In the resonance frequency system, paying attention to the phenomenon that the resonance frequency of the vibration of the tire changes when the air pressure of the tire changes, the resonance frequency is detected as the tire vibration characteristic value based on the wheel speed, Tire pressure is estimated based on the detected resonance frequency. A conventional example of this resonance frequency method is Japanese Patent No. 28366.
No. 52 publication.

On the other hand, in the disturbance observer system, it is possible to estimate a change in tire air pressure as a disturbance to the tire according to a modern control theory called a disturbance observer, and based on the wheel speed, The disturbance is calculated as the tire vibration characteristic value, and the tire air pressure is estimated based on the calculated disturbance.
A conventional example of this disturbance observer system is Japanese Patent Laid-Open No. 2000-2.
It is described in Japanese Patent No. 38516.

[0013]

As is apparent from the above description, the rule utilizing the dynamic load radius is used as an estimation rule for estimating the tire air pressure by estimating the reflection value reflecting the tire air pressure based on the wheel speed. , A plurality of estimation rules such as a rule using a resonance frequency and a rule using a disturbance observer have already been proposed.

In order to accurately estimate the tire pressure while the vehicle is running regardless of the vehicle environment, any one of the plurality of estimation rules is adopted independently, while there is a method of performing necessary data processing. There is also a method of adopting at least two of the plurality of estimation rules while selecting at least two of the estimation rules according to the vehicle environment.

The estimation accuracy when the tire pressure is estimated according to each estimation rule may depend on the vehicle speed, which is the traveling speed of the vehicle.

Specifically, when the rule using the resonance frequency or the disturbance observer (hereinafter referred to as "tire vibration utilization rule") is adopted, a high vehicle speed range (for example, about 80 to about 120 [km / h] is used. ] In the above vehicle speed range), it is difficult to estimate tire air pressure with high accuracy. On the other hand, when the rule using the dynamic load radius (hereinafter referred to as “dynamic load radius utilization rule”) is adopted, it is possible to estimate the tire pressure with high accuracy even in such a high vehicle speed range. It has the property of being

Therefore, in order to accurately estimate the tire air pressure in the entire range of the changeable vehicle speed, the present applicant
As described in Japanese Patent Application Laid-Open No. 9-2031, a hybrid system has been proposed in which a tire vibration utilization rule and a dynamic load radius utilization rule are combined. According to this hybrid system, the tire vibration utilization rule is selected in the low speed region and the dynamic load radius utilization rule is selected in the vehicle speed region higher than that as the tire pressure estimation rule.

As described above, this prior art is made in view of the fact that the estimation accuracy when the tire pressure is estimated according to each estimation rule depends on the vehicle speed.

On the other hand, the present inventor has found that there are factors other than the vehicle speed on which the estimation accuracy of the tire air pressure depends, and other vehicle environments such as the motion state of the vehicle and the characteristics of the road surface on which the vehicle travels, It was also found that there are cases in which it may depend on the type of tire (shape, rigidity, temperature characteristics, etc. described in terms of use, performance, flatness, etc.).

For example, when the tire pressure is estimated in accordance with the dynamic load radius utilization rule, even if the true tire pressure is the same, the motion state of the vehicle is constant speed running and acceleration running. However, there is a tendency that the estimated values of tire air pressure differ from each other. If the tire air pressure decreases and the wheel dynamic load radius decreases, the wheel speed increases accordingly.The phenomenon of such wheel speed increase is that the dynamic load radius does not decrease and the wheel slip amount decreases. This is because even if the number increases, the same occurs.

Further, for the same reason, when the tire air pressure is estimated in accordance with the dynamic load radius utilization rule, even if the true tire air pressure is the same, whether the vehicle is in the straight running or in the turning running. There is also a tendency that the estimated values of tire air pressure differ from each other in some cases.

If the tire air pressure estimation rule is switched according to the vehicle environment factor that affects the tire air pressure estimation accuracy, the tire air pressure estimation rule is switched according to only the vehicle speed according to the prior art described in the above publication. The estimation accuracy of the tire pressure can be easily improved.

In any case, however, the method of switching the tire air pressure estimation rule according to the vehicle environment factor is, in effect, judged whether or not each estimation rule actually matches the vehicle environment, and the result is determined. This is a method of previously identifying a vehicle environmental factor that causes the occurrence of

Therefore, when the estimation accuracy of the tire air pressure fluctuates due to a vehicle environmental factor that is not specified in advance, the tire air pressure estimation rule is switched so that the tire air pressure estimation accuracy is improved. It is difficult.

In view of the above-mentioned circumstances, the present invention effectively utilizes a plurality of estimation rules for estimating tire air pressure, so that the vehicle environmental factors that affect the estimation accuracy of the tire air pressure according to each estimation rule. It is an object to accurately estimate the tire air pressure regardless of the type.

[0026]

MEANS FOR SOLVING THE PROBLEMS AND EFFECTS OF THE INVENTION The following aspects are obtained by the present invention. Each mode is divided into sections, numbers are attached to each section, and the numbers of other sections are referred to as necessary. This is for facilitating the understanding of some of the technical features described in the present specification and some of the combinations thereof, and the technical features described in the present specification and the combination thereof are as follows. It should not be construed as limiting. (1) A device which is provided in a vehicle having a plurality of wheels in which air is sealed under pressure inside a tire mounted on the wheels, and which is a device for determining tire pressures of the plurality of wheels. A plurality of wheel speed sensors that are respectively provided in relation to the wheel speeds that detect the wheel speed of each wheel, and for each wheel, based on the wheel speeds detected by each wheel speed sensor, and according to a plurality of different estimation rules. When a plurality of types of reflection values reflecting the tire air pressure are estimated, and among the estimated plurality of types of reflection values, regarding a tire air pressure of the same wheel or the same wheel group, a predetermined correlation is established. In the judgment, the tire pressure is judged according to at least one of a plurality of predetermined judgment rules according to the plurality of estimation rules. A tire pressure determination device including a calibrator.

As described above, the method of switching the tire air pressure estimation rule depending on the vehicle environment factor effectively determines whether or not each estimation rule actually matches the vehicle environment, and produces the result. This is a method of previously specifying the vehicle environmental factor that is the cause.

On the other hand, in the device according to this section,
For each wheel, a plurality of types of reflection values reflecting tire air pressure are estimated according to a plurality of different estimation rules. Between the estimated multiple types of reflection values,
When a predetermined correlation is established with respect to the tire pressures of the same wheel or the same wheel group, the determination of the tire pressure is performed by at least one of a plurality of determination rules predetermined according to the plurality of estimation rules. According to one.

Therefore, in this device, the determination as to whether or not each estimation rule actually fits the vehicle environment is based on the consistency between the plurality of types of reflection values estimated according to the plurality of estimation rules. It will be focused on.

Therefore, according to this apparatus, the tire pressure is estimated according to the estimation rule that actually matches the vehicle environment, regardless of the type of the vehicle environment factor that affects the estimation accuracy of the tire pressure according to each estimation rule. It becomes possible.

Further, according to this apparatus, in order to estimate the tire pressure according to the estimation rule that actually matches the vehicle environment, the vehicle environment to be noticed is specified in advance and the specified vehicle environment is detected. No need to add functions to the vehicle.

Specifically, for example, even if a vehicle does not have a function for detecting acceleration traveling and turning traveling of the vehicle, which is a vehicle environment in which the above-mentioned dynamic load radius utilization rule does not conform, the vehicle does not have such a function. In the environment, there is no correlation between the reflection value estimated according to the dynamic load radius utilization rule and the reflection value estimated according to another rule regarding the tire air pressure of each wheel or each wheel group.

Therefore, in the acceleration traveling and the turning traveling of the vehicle, the device according to this section is implemented so as to avoid or invalidate the determination of the tire air pressure according to the dynamic load radius utilization rule. Is possible.

In this section and the following sections, "determination of tire air pressure" is interpreted to mean estimating an absolute value of tire air pressure, or a relative value (that is, a change) to a threshold value of tire air pressure. It is meant to mean that the tire pressure is larger or smaller than a threshold value, that is, to judge the magnitude of the tire pressure. Can be interpreted as

In this section and each of the following sections, "a predetermined correlation is established with respect to the tire air pressure of each wheel or each wheel group among a plurality of types of reflection values" means, for example, which reflection Corresponding values indicate that the tire pressure on one wheel is lower than the set pressure or the tire pressure on another particular wheel, other reflected values are similar, as the tire pressure on the same wheel is set or set to a certain pressure. It can be taken to mean that it is lower than the tire pressure of another wheel.

Furthermore, "a predetermined correlation is established with respect to the tire air pressure of each wheel or each wheel group among a plurality of types of reflected values" means that each reflected value indicates a specific change in tire air pressure. When it is assumed to reflect, it can be interpreted to mean that the specific change in the assumed tire air pressure is common to a plurality of kinds of reflected values.

In this section and the following sections, the "wheel group" can be defined as, for example, a combination of a plurality of wheels having a fixed relative positional relationship with each other in a vehicle.

Specifically, the "wheel group" is defined as two coaxial wheels arranged in the left-right direction on the front side or the rear side of the vehicle, or two one-side wheels arranged in the front-rear direction on the right side or the left side of the vehicle. Or as a pair of wheels in diagonal positions on the vehicle. (2) The determiner follows each of the estimation rules for each wheel, and reflects values of each type based on the wheel speeds sequentially detected by the wheel speed sensors in the same temporal section. The tire pressure determination device according to item (1), including a reflection value estimation means for estimating

In this device, a plurality of types of reflection values are estimated based on a plurality of wheel speeds sequentially detected by each wheel speed sensor within the same temporal section, and as a result, the plurality of types of reflection values are calculated. Will be estimated under the same vehicle environment.

Therefore, according to this apparatus, it is easy to match the theory and reality with respect to the success or failure of the correlation between the plurality of types of reflection values. Specifically, according to this device, the occurrence of a situation in which a correlation between a plurality of types of reflection values theoretically holds is not actually met, on the contrary, a vehicle environment not theoretically holds It becomes easy to avoid the occurrence of a situation that actually holds. (3) The reflection value estimation means, based on a plurality of wheel speeds sequentially detected by the wheel speed sensors within the same temporal section, according to each of the plurality of estimation rules for each wheel. (2), which includes means for tentatively and sequentially estimating the reflection values of, and finally estimating each type of reflection value as a representative value of the plurality of provisionally and sequentially estimated reflection values. Tire pressure determination device. (4) In any one of (1) to (3), the judging device includes an update avoiding means for avoiding updating of the tire air pressure judgment result when the predetermined correlation is not established. Tire pressure determination device.

The fact that no correlation is established between the plurality of types of reflection values means that at least one of the plurality of estimation rules does not match the actual vehicle environment, and thus, among the plurality of estimation rules. When the tire pressure is determined by estimating the reflection value according to at least one of the above, it means that the determination result is likely to include an error.

Based on such knowledge, in the device according to this section, updating of the tire air pressure determination result is avoided when a correlation does not hold between a plurality of types of reflection values.
Specifically, for example, when the correlation between the plurality of types of reflected values is not established, the tire pressure is not determined, or it is determined that the determination result of this time is different from the previous determination result. Also, the determination result of this time is invalidated and the determination result of the previous time is used as it is as the determination result of this time.

Therefore, according to this device, there is no influence of the determination of the tire air pressure when the correlations between the plurality of types of reflected values are not established, and as a result, the determination of the tire pressure is performed throughout the operation of the device. It becomes easy to improve the reliability for. (5) Any of (1) to (3), wherein the determiner includes abnormality determination avoiding means for avoiding determination that the tire pressure is abnormal when the predetermined correlation is not established. Cylinder tire pressure determination device.

As described above, the fact that no correlation is established between the plurality of types of reflection values means that at least one of the plurality of estimation rules is not suitable for the actual vehicle environment, and, by extension, the plurality of the plurality of estimation rules. When the tire pressure is judged by estimating the reflection value according to at least one of the above estimation rules, it means that the judgment result is likely to include an error.

Therefore, it is difficult to accurately determine the tire pressure in a vehicle environment in which a correlation does not hold between a plurality of types of reflection values. In such a vehicle environment, it is possible to adopt the concept of treating the tire pressure equivalently when the tire pressure is normal, or the idea that the tire pressure is treated equivalently when the tire pressure is abnormal. is there.

However, it may be truly normal to inform the user of the vehicle that the tire pressure is abnormal only when it is determined that the tire pressure is abnormal with high accuracy. If the tire pressure is maintained, it is possible to prevent the user of the vehicle from feeling anxious rather than notifying that the tire pressure is abnormal.

Based on such knowledge, the apparatus according to this section avoids the determination that the tire pressure is abnormal when a correlation does not hold between a plurality of types of reflection values. (6) Furthermore, when the judging device judges that the tire pressure is abnormal, the judging device includes an alarm device that is activated to warn that the tire pressure is abnormal. The tire pressure determination device according to any one of (1) to (3), including an operation avoiding means for avoiding an operation of the alarm device when the predetermined correlation is not established. (7) The tire according to (6), wherein the operation avoiding unit includes a pseudo normality determining unit that pseudoly determines that the tire air pressure is normal when the predetermined correlation is not established. Air pressure determination device. (8) When the determiner establishes the predetermined correlation, the determination result of the tire air pressure acquired according to at least one of the plurality of determination rules indicates abnormality of the tire air pressure. The tire air pressure determination device according to any one of (1) to (7), further including first abnormality determination means for determining that the tire air pressure is abnormal.

According to this apparatus, the tire air pressure is abnormal after waiting for the tire air pressure determination results to show that the tire air pressure determination results obtained in accordance with the plurality of determination rules all indicate tire pressure abnormalities. It becomes easier to make a response to the change from the normal tire pressure to the abnormal tire pressure more quickly than in the case where it is determined that (9) When the predetermined correlation is established by the determiner, a plurality of determination results of the tire air pressure obtained according to the plurality of determination rules respectively indicate an abnormality in the tire air pressure. The tire air pressure determination device according to any one of (1) to (7), further including second abnormality determination means for determining that the tire air pressure is abnormal under the above condition.

According to this device, the tire pressure is judged to be abnormal on the condition that the tire pressure judgment result obtained according to at least one of the plurality of judgment rules indicates the tire pressure abnormality. It becomes easier to execute with higher reliability than when there is a determination. (10) The determiner expresses at least one of the plurality of types of reflection values estimated according to the plurality of estimation rules for the same wheel as a magnitude relationship with a predetermined threshold value. The tire air pressure determination device according to any one of items (1) to (9), including first correlation determination means for determining success or failure of the predetermined correlation by handling. (11) The determiner estimates at least one of the plurality of types of reflection values estimated for the same wheel according to the estimation rules according to the same estimation rule for another predetermined wheel. The tire pressure according to any one of (1) to (9), including second correlation determining means for determining success or failure of the predetermined correlation by expressing and handling as a magnitude relationship with a reflected value. Judgment device. (12) The plurality of estimation rules includes, for each wheel, a resonance frequency of the tire vibration or a physical quantity related to the resonance frequency of the tire based on the wheel speed detected by each wheel speed sensor, as one of the plurality of reflection values. Based on the wheel speed detected by each wheel speed sensor for each wheel, the dynamic load radius of the tire or a physical quantity related thereto is defined as one of the reflection values of the plurality of types. A second estimation rule to estimate and a disturbance observer that estimates a change in the tire air pressure as a disturbance to the tire for each wheel, and the plurality of types of the disturbance based on the wheel speed detected by each wheel speed sensor. And a time series data of wheel speed detected by each wheel speed sensor for each wheel. Any one of (1) to (11) including at least two of a fourth estimation rule for estimating a vibration level of a wheel speed signal in a specific frequency region as one of the plurality of types of reflection values. The tire pressure determination device according to. (13) The tire pressure determination device according to item (12), wherein the plurality of estimation rules include the first estimation rule and the second estimation rule. (14) In the first determination rule, the magnitude relationship between the reflection value estimated for each wheel and a predetermined threshold value may match the predetermined magnitude relationship individually for each wheel. The tire air pressure determination device according to item (13), which is a rule that determines that the tire air pressure is abnormal under the condition. (15) The second determination rule combines a plurality of reflection values estimated for the plurality of wheels according to the same second estimation rule into one value according to a predetermined combination rule, and the combined value Is a rule for collectively determining that the tire pressures of the plurality of wheels are abnormal, provided that the magnitude relationship between the predetermined threshold value and the predetermined threshold value matches the predetermined magnitude relationship (13). ) Or the tire air pressure determination device according to (14).

[0050]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, some more specific embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram conceptually showing the hardware structure of the tire abnormality determining apparatus according to the first embodiment of the present invention. This tire abnormality determination device is mounted on a vehicle.

The vehicle (for example, a passenger car) has wheels on the front, rear, left and right thereof. In Fig. 1, "F
"L" is the left front wheel, "FR" is the right front wheel, "RL" is the left rear wheel,
“RR” means the right rear wheel, respectively. The total number of wheels is four.

As is well known, each wheel is constructed by enclosing air under pressure inside a rubber tire mounted on a metal wheel.

As shown in FIG. 1, the tire abnormality determining device has a wheel speed sensor 10 for each wheel.
As is well known, each wheel speed sensor 10 is a sensor that detects the angular speed of each wheel as a wheel speed.
Specifically, the wheel speed sensor 10 is an electromagnetic pickup, and outputs a voltage signal that periodically changes according to passage of a large number of teeth formed on the outer circumference of a rotor that rotates together with the wheel.

The four wheel speed sensors 10 are shown in FIG.
As shown in, it is electrically connected to the determiner 20.
The determiner 20 is a device that mainly includes a computer 22, and determines whether or not the tire air pressure is abnormally low based on the output signals of the four wheel speed sensors 10.

In addition, in addition, in the following description,
The term tire anomaly is used as a term that means an abnormally low tire pressure.

FIG. 2 is a block diagram conceptually showing the hardware structure of the computer 22. As is well known, the computer 22 includes a CPU 30 (an example of a processor), a ROM 32 (an example of a memory), and an RA.
An M34 (an example of a memory) is connected to each other via a bus 36.

As shown in FIG. 2, various programs including a tire abnormality determination program are stored in the ROM 32 in advance.

The tire abnormality judging program is a program executed to judge whether or not the tire is abnormal for each wheel individually or collectively for a plurality of wheels. Details of this tire abnormality determination program will be described later.

As shown in FIG. 1, an alarm device 40 is also connected to the judging device 20. The alarm 40 is activated to visually or audibly notify the driver of the vehicle that there is an abnormally low tire pressure among the wheels. The alarm 40 can be designed to provide the driver of the vehicle with information that identifies the position of the wheel of the plurality of wheels that has been determined to have an abnormally low tire pressure.

When the alarm device 40 is configured to visually notify information, it should be configured as a dedicated lamp or as a multi-display that selectively displays a plurality of different information at the same display position. Is possible.

As shown in FIG. 1, the decision unit 20 is further connected to an initialization switch 50. When the initialization switch 50 is operated by the user (including the driver) of the vehicle, the initialization request for requesting the initialization of the air pressure detection characteristic in the determination unit 20 is required by the determination unit 20. It means that it was output to 20.

The initialization switch 50 is operated by the user of the vehicle when tires are replaced in the vehicle, for example. In its operation, it is reasonable to assume that for all wheels the tire pressure is equal to each set pressure.

A brake switch 52 is also connected to the judging device 20. This brake switch 52
Is a switch that detects that the vehicle has been braked in response to, for example, the driver operating a brake operating member of the vehicle. The reason for connecting the brake switch 52 to the determiner 20 will be described later.

An outside air temperature sensor 54 for detecting the outside air temperature of the vehicle is also connected to the judging device 20. The outside air temperature sensor 54 is used in the determiner 20 to estimate the tire temperature.

FIG. 3 is a flow chart conceptually showing the contents of the tire abnormality determination program. This tire abnormality determination program is executed while the computer 22 is powered on.

In this tire abnormality determining program, first, step S1 (hereinafter simply referred to as "S1").
In other steps), the determination unit 20 initializes the air pressure detection characteristic.

In this initialization, for example, under the assumption that the tire air pressure of each wheel is equal to the set pressure, the tire air pressure is adjusted so that the air pressure detection characteristic matches the actual tire characteristic of each wheel. Initial value X of the reflected value reflected
₀ and Y ₀ are calculated. After this initialization is complete,
The calculated initial value X ₀ of the reflected value at each time,
The change amount from Y ₀ is calculated, and when the absolute value of the calculated change amount exceeds the threshold values A and B, it is determined that the tire pressure is abnormal.

Next, in S2, it is judged whether or not the initialization is completed. If the initialization is not completed yet, the judgment is NO, and the process returns to S1.

As a result of repeating the execution of S1 and S2, if the initialization is completed and the determination of S2 is YES, the elapsed time t is set to 0 in S3. The elapsed time t is incremented by 1 by the computer 22 with the passage of time.

Then, in S4, resonance frequency data processing is performed. In this resonance frequency data processing, basically, for each wheel, each wheel speed sensor 10
Based on the wheel speed sequentially detected by, the resonance frequency of tire vibration, which is an example of a reflected value reflecting the tire air pressure, is sequentially estimated and accumulated. Here, the resonance frequency is an example of a provisional reflection value.

As shown in the graph of FIG. 4A, the resonance
As for the frequency, the tire pressure is set to P ₀As it falls from
It is a physical quantity that decreases due to

The elapsed time t is used to manage the storage time of the resonance frequency. Therefore, the elapsed time t has a threshold value t _TH having a value equal to the specified value of the accumulation time.
Is set.

However, in this resonance frequency data processing, data selection is performed to select only wheel speeds suitable for use in estimating the resonance frequency. The brake switch 52 is used for this data selection, and the wheel speed detected when the vehicle is braked is excluded from the target of the resonance frequency estimation.

Further, in this resonance frequency data processing, data correction for correcting the estimated resonance frequency based on the tire temperature is also performed. The tire temperature is estimated using the outside air temperature sensor 54.

Furthermore, in this resonance frequency data processing, a plurality of product sums are calculated for a plurality of resonance frequencies successively estimated as described above. This operation is
For example, the least squares method (an example of smoothing processing for multivariate)
1 representing a plurality of resonance frequencies that are sequentially estimated by
One value is calculated as the resonance frequency estimation value α. Here, the resonance frequency estimated value α is an example of a final reflected value.

In FIG. 5, the resonance frequency (provisional value) is set during one data accumulation period which starts at the time when the passage time t = 0 and ends at the time when the passage time t = the threshold value t _TH. Is conceptually represented as a sequence of sequentially estimated and accumulated.
In the figure, each arrow indicates the calculation period for each resonance frequency (provisional value), and the gap between the arrows indicates the period during which the estimation of the resonance frequency (provisional value) is prohibited for the data selection. Shows.

As shown in FIG. 5, when one data storage period ends, one resonance frequency representing them is estimated based on a plurality of resonance frequencies (temporary values) accumulated so far. It is calculated as the value α (final value).

That is, in the present embodiment, the first for calculating the resonance frequency estimated value α based on the wheel speed is used.
And the rule for determining whether the tire pressure is abnormal based on the resonance frequency estimated value α calculated according to the first estimation rule,
It is adopted as the first determination rule corresponding to the first estimation rule.

Subsequently, in S5 of FIG. 3, dynamic load radius data processing is performed. In this dynamic load radius data processing, basically, for each wheel, the dynamic load radius of the tire, which is an example of the reflected value reflecting the tire air pressure, based on the wheel speed sequentially detected by each wheel speed sensor 10. The dynamic load radius related quantity related to is sequentially estimated and accumulated. Here, the dynamic load radius related amount is an example of a provisional reflection value.

As shown in the graph of FIG. 4B, the dynamic load radius is a physical quantity that decreases as the tire air pressure decreases from the set pressure P ₀ , like the resonance frequency.

Like the resonance frequency data processing, this dynamic load radius data processing also includes data selection, data correction, and product-sum calculation.

As in the case of the resonance frequency, FIG. 5 conceptually shows that the dynamic load radius related quantity is successively estimated and accumulated during one data accumulation period. When one data storage period ends, one dynamic load radius related amount representing them is calculated as the dynamic load radius estimated value β based on the plurality of dynamic load radius related amounts accumulated so far. Here, the dynamic load radius estimated value β is an example of a final reflected value.

That is, in this embodiment, the second method for calculating the dynamic load radius estimated value β based on the wheel speed is used.
And the rule for determining whether or not the tire air pressure is abnormal based on the dynamic load radius estimated value β calculated according to the second estimation rule,
It is adopted as the second determination rule corresponding to the second estimation rule.

Then, in S6 of FIG. 3, the elapsed time t
It is determined whether the current value of is greater than or equal to the threshold value t _TH . This time, assuming that it is not above the threshold t _TH ,
The determination is NO, and the process returns to S4.

Assuming that the current value of the elapsed time t is equal to or greater than the threshold value t _TH as a result of repeating the execution of S4, S5 and S6, the determination in S6 is YES and the process proceeds to S7.

At S7, the resonance frequency estimated value α is calculated based on the plurality of resonance frequencies accumulated during the current data accumulation period.

Thereafter, in S8, as in S7, the dynamic load radius estimated value β is calculated based on the plurality of dynamic load radius related amounts accumulated during the current data accumulation period.

Subsequently, in S9, it is determined whether or not the tire air pressure has dropped. The details of this step S9 are shown in the flowchart of FIG. 6 as a routine for determining a decrease in air pressure.

In this air pressure drop determination routine,
First, in S31, there is a predetermined correlation between the resonance frequency estimated value α and the dynamic load radius estimated value β calculated as described above, that is, whether there is a relationship that both reflect the same tire air pressure state. Is determined. The details of S31 are shown as a correlation determination routine in a flowchart in FIG. 7, which will be described later.

Next, in S32, it is determined whether or not it is determined in S31 that a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. This time, if the correlation is determined to be established, the determination is YES.
Becomes

Subsequently, in S33, it is determined whether or not the tire air pressure is reduced according to the first determination rule. Specifically, for example, among a plurality of wheels, a wheel in which the difference between the resonance frequency estimation value α and the initial value X ₀ calculated in the initialization step for that is larger than the threshold value A (hereinafter,
It is determined whether or not there is a "air pressure drop wheel").

In addition, it should be noted that, when focusing on the resonance frequency of the tire, it is possible to individually determine the tire pressure for each wheel, whereas when focusing on the dynamic load radius of the tire, Normally, tire pressures are collectively determined for a plurality of wheels. In the present embodiment, both the determination rule focusing on the resonance frequency and the determination rule focusing on the dynamic load radius are adopted.
The tire pressure is collectively determined for a plurality of wheels in common with one determination rule.

This time, assuming that the above-described wheel with reduced air pressure exists, the determination is YES, and in S35,
While the tire pressure is normal in the reset state, the decrease flag indicating that the tire pressure is decreasing in the set state is set. This drop flag indicates RO
It is prepared in advance in the non-volatile rewritable memory unit in M32. This is the end of one execution of the air pressure decrease determination routine.

On the other hand, this time, assuming that there is no wheel with reduced air pressure, the determination in S33 is NO and S33
At 34, it is determined according to the second determination rule whether the tire air pressure is decreasing. Specifically, for example, first, a plurality of dynamic load radius estimated values β calculated respectively for a plurality of wheels are combined into one value. This combined value is a dynamic load radius reflection value R that collectively reflects the dynamic load radius for a plurality of wheels.

The dynamic load radius reflection value R is calculated, for example, by the following equation.

R = (V _FR / V _FL ) − (V _RR / V _RL ) where V _{FL is} the wheel speed of the left front wheel (the estimated dynamic load radius β of the left front wheel)
Equivalent to _FL ) V _FR : Wheel speed of the right front wheel (dynamic load radius estimated value β of the right front wheel)
Equivalent to _FR ) V _RL : Wheel speed of left rear wheel (Estimated dynamic load radius β of left rear wheel)
Equivalent to _RL ) V _RR : Wheel speed of the right rear wheel (dynamic load radius estimated value β of the right rear wheel)
Equivalent) the dynamic load radius reflection value R and _RR are also, for example, it can be calculated by the following equation.

R = (V _FL + V _RR ) − (V _FR + V _RL ) Then, in S34, the dynamic load radius reflection value R calculated in this way and the initial value calculated in the initialization step for it. It is determined whether or not the difference from the value Y ₀ is larger than the threshold value B.

If it is assumed that the difference is larger than the threshold value B this time, the determination is YES and the decrease flag is set in S35. This is the end of one execution of the air pressure decrease determination routine.

On the other hand, if there is no correlation between the resonance frequency estimation value α and the dynamic load radius estimation value β, the determination in S32 is NO, and the determination rule focusing on the resonance frequency is also used. If it is determined that the tire air pressure has not decreased even by the determination rule focusing on the load radius, and therefore the determinations in S33 and S34 are both NO, the alarm device 40 is activated in S36. Since it is not necessary to alert the vehicle user, the low flag is reset.

As will be described later, this lowering flag can be considered as an operation permission flag that permits the operation of the alarm device 40 in the sense that it is a flag that determines whether the alarm device 40 is operated or stopped. .

As described above, in the present embodiment, when there is no correlation between the resonance frequency estimated value α and the dynamic load radius estimated value β, it is the same as when it is determined that the tire air pressure has not dropped. In addition, the determination that the tire pressure is abnormal and the operation of the alarm device 40 are avoided.

Thus, one execution of this air pressure drop determination routine is completed.

After that, in S10 of FIG. 3, it is determined whether or not it is determined that the tire air pressure is reduced by referring to the reduction flag. If it is determined that the level has not dropped, the determination in S10 is NO and S11
At, the alarm 40 is turned off. In contrast,
If it is determined that the temperature is decreasing, the determination in S10 is Y.
It becomes ES, and the alarm device 40 is turned on in S12.

In any case, thereafter, in S13, it is determined whether or not an initialization request is issued in response to the operation of the initialization switch 50. This time, assuming that the initialization request has not been issued, the determination becomes NO and S3
However, if it is assumed that the initialization request is issued this time, the determination becomes YES and the process returns to S1.

Here, the contents of the correlation determining routine will be described in detail with reference to FIG.

Firstly, conceptually, in this correlation determination routine, regarding the height of the tire pressure between the resonance frequency estimated value α and the dynamic load radius estimated value β for each wheel group, It is determined whether a positive correlation is established.

FIG. 8 shows, in a tabular form, six conditions that should be satisfied together in order to determine that a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. The contents of these conditions will be described below. (1) First condition The first condition is that the magnitude relationship regarding the resonance frequency estimation value α and the magnitude relationship regarding the dynamic load radius estimation value β coincide with each other for the first wheel group including the right front wheel and the left front wheel. Applies when you do.

The fact that the magnitude relationship regarding the resonance frequency estimated value α and the magnitude relationship regarding the dynamic load radius estimated value β coincide with each other means that the resonance frequency estimated value α _FL of the left front wheel is subtracted from the resonance frequency estimated value α _FR of the right front wheel. The sign of the value (positive or negative) and the sign (positive or negative) of the value obtained by subtracting the estimated dynamic load radius β _FL of the left front wheel from the estimated dynamic load radius β _FR of the right front wheel agree with each other. means. And this means that the sign of the product of the previous subtraction value and the subsequent subtraction value is positive.

Therefore, in FIG. 8, the first condition is expressed by the inequality of (α _FR −α _FL ) · (β _FR −β _FL )> 0. This also applies to other conditions described below. (2) Second condition The second condition is that the magnitude relationship regarding the resonance frequency estimation value α and the magnitude relationship regarding the dynamic load radius estimation value β are mutually related for the second wheel group including the right front wheel and the right rear wheel. Applies when they match. (3) Third condition The third condition is that the magnitude relationship regarding the resonance frequency estimated value α and the magnitude relationship regarding the dynamic load radius estimated value β are mutually related for the third wheel group including the right front wheel and the left rear wheel. Applies when they match. (4) Fourth condition The fourth condition is that the fourth wheel group including the front left wheel and the rear right wheel has a magnitude relationship regarding the resonance frequency estimated value α and a magnitude relationship regarding the dynamic load radius estimated value β mutually. Applies when they match. (5) Fifth Condition The fifth condition is that the magnitude relationship regarding the resonance frequency estimation value α and the magnitude relationship regarding the dynamic load radius estimation value β are mutually related for the fifth wheel group including the left front wheel and the left rear wheel. Applies when they match. (6) Sixth Condition The sixth condition is that the sixth relation is made between the resonance frequency estimated value α and the dynamic load radius estimated value β for the sixth wheel group including the right front wheel and the left rear wheel. Applies when they match.

Here, the correlation determining routine will be described in detail with reference to FIG.

In this correlation determining routine, S5
In each of 1 to S56, it is determined whether or not the above six conditions are satisfied. If all of these six conditions are satisfied and, as a result, the determinations in S51 to S56 are all YES, in S57, the resonance frequency estimation value α for all the wheel groups, that is, for the plurality of wheels as a whole. It is determined that a correlation is established between and the dynamic load radius reflection value β.

On the other hand, if any of the six conditions is not satisfied and, as a result, the result of any of the determinations in S51 to S56 is NO, then in S58, for all wheel groups, that is, a plurality of It is determined that the correlation does not hold between the resonance frequency estimation value α and the dynamic load radius reflection value β for all the wheels.

In either case, as described above, one execution of this correlation determining routine is completed.

As is apparent from the above description, in the present embodiment, the tire abnormality judging device constitutes an example of the "tire air pressure judging device" according to the present invention, and the judging device 20 is referred to in the above item (1). It constitutes an example of a "determiner".

Further, in this embodiment, the decision unit 2
The portion of 0 that executes S3 to S8 in FIG. 3 constitutes an example of the "reflection value estimation means" in the item (2) or (3).

Further, in the present embodiment, the decision unit 2
6 is an example of "abnormality determination avoiding means" in the item (5), an example of "operation avoiding means" in the item (6), or " It constitutes an example of "pseudo-normality determining means".

Further, in this embodiment, the decision unit 2
The portion of 0 that executes S33 to S35 of FIG. 6 constitutes an example of the "first abnormality determination means" in the item (8).

Further, in this embodiment, the decision unit 2
The portion of 0 that executes the correlation determination routine of FIG. 7 constitutes an example of the “second correlation determination means” in the item (11).

Further, in this embodiment, the first
The above-mentioned estimation rule constitutes an example of the "first estimation rule" in the above item (12), and the second estimation rule constitutes an example of the "second estimation rule" in the same item.

Next, a second embodiment of the present invention will be described.
However, since the present embodiment has a common hardware configuration with the first embodiment, and has a common software configuration except for the correlation determination routine, the same names and reference numerals are used for common elements. A detailed description will be omitted by quoting, and only different elements will be described in detail.

As described above, when trying to estimate the tire pressure by paying attention to the dynamic load radius of the tire, a comparison is made when trying to estimate the tire pressure by paying attention to the resonance frequency of the tire vibration. The estimation accuracy tends to decrease depending on the difference in the motion state of whether the vehicle is in the steady running state or the accelerated running state, and the difference in the movement state of the vehicle in the straight running state or the turning running state. .

Therefore, for example, when the dynamic load radius estimated value β decreases for each of only one of a pair of two coaxial wheels (a combination of left and right front wheels and left and right rear wheels) in the vehicle, the cause is It is considered that the tire air pressure decreased, and that the wheel speed increased without lowering the tire air pressure. If the reason why the estimated dynamic load radius β for each of the two coaxial wheels is decreased is that the tire air pressure is truly decreased, it is between the right front wheel and the right rear wheel or the left front wheel and the left wheel. There should be a difference between the rear wheel and the resonance frequency estimate α.

That is, when the dynamic load radius estimation value β decreases for each of the two coaxial wheels, the resonance frequency is estimated between the right front wheel and the right rear wheel or between the left front wheel and the left rear wheel. If there is a difference regarding the value α, the correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. In this case, it can be considered that the success or failure of the correlation is determined with the right front wheel, the left front wheel, the right rear wheel, or the left rear wheel as a reference individually.

The reason why such a correlation does not hold is considered to be a vehicle acceleration state in which only one of the two coaxial wheels is accelerated (driven) by the power source of the vehicle.

Therefore, if the tire pressure is not judged to be abnormal when such a correlation is not established, as a result, the tire pressure is mistakenly abnormal due to the vehicle being in an accelerated state. Occurrence of a situation to be judged can be avoided.

Further, for example, when the dynamic load radius estimated value β decreases for each of only one pair of two wheels on one side of the vehicle (combination of the right front wheel and the left front wheel), the cause is as follows. It is considered that the tire air pressure truly decreased and that the wheel speed increased without lowering the tire air pressure. If the reason why the dynamic load radius estimated value β of each of the two wheels on one side is decreased is that the tire pressure is truly decreased, it is between the right front wheel and the left front wheel or between the right rear wheel and the left wheel. There should be a difference between the rear wheel and the resonance frequency estimate α.

That is, when the dynamic load radius estimation value β decreases for each of the two wheels on one side only, the resonance frequency is estimated between the right front wheel and the left front wheel or between the right rear wheel and the left rear wheel. If there is a difference regarding the value α, the correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. In this case as well, it can be considered that the success or failure of the correlation is determined with the right front wheel, the left front wheel, the right rear wheel, or the left rear wheel as a reference individually.

The reason why such correlation does not hold is that the vehicle is in a turning state in which only one of the two coaxial wheels is accelerated.

Therefore, if the tire pressure is not judged to be abnormal when such a correlation is not established, as a result, the tire pressure is erroneously abnormal due to the vehicle turning state. Occurrence of a situation to be judged can be avoided.

The correlation determining routine in this embodiment is constructed based on the knowledge described above. FIG. 9 is a flowchart conceptually showing the contents of this correlation determination routine. The contents of this correlation determination routine will be described in detail below, but prior to that, a conceptual explanation will be given.

In this correlation determining routine, basically, for each wheel, a positive correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β with respect to the tire air pressure. It is determined whether or not.

However, the purpose of this correlation determination routine is to avoid the occurrence of a situation in which the tire pressure is erroneously determined to be abnormal due to the vehicle being in an accelerating state or in a turning state. It is in. Therefore, in the present embodiment, by determining whether or not the dynamic load radius estimated value β is below the threshold value together for a pair of wheels (two coaxial wheels or two wheels on one side) which are related to each other, It is determined whether the dynamic load radius estimated value β has decreased for each wheel.

Further, the resonance frequency estimation value α is more likely to change with time than the dynamic load radius estimation value β due to a change in tire temperature between day and night and between seasons, and the value and threshold value at a certain moment. It is not familiar to judge the magnitude of the resonance frequency estimated value α by comparison with. for that reason,
In the present embodiment, the resonance frequency estimation value α is determined by determining whether or not the resonance frequency estimation value α has a difference between a pair of wheels (two coaxial wheels or two wheels on one side) associated with each other. It is determined whether or not the wheels have decreased. According to this determination, the result does not have to be affected so much by changes in tire temperature.

FIG. 10 shows the resonance frequency in this embodiment.
Correlation is established between the number estimate α and the dynamic load radius estimate β
The four conditions that should be met in order to determine that
It is represented in the format. The contents of those conditions are explained below.
It (7) Seventh condition The seventh condition is the dynamic load radius for both the left and right front wheels.
Estimated value β is the threshold value β _TH1Smaller and rear left and right wheels
For both, the estimated dynamic load radius β is the threshold β
_TH2In the above case, the resonance frequency estimation value α
Difference between right two wheels Δα_RHOr the difference between the two left wheels Δα_LH
Is the threshold Δα_TH2When it is larger, it holds. (8) Eighth condition The eighth condition is the dynamic load radius for both the left and right rear wheels.
Estimated value β is the threshold value β _TH2Smaller and front left and right wheels
For both, the estimated dynamic load radius β is the threshold β
_TH1In the above case, the difference Δα_RHOr the difference Δα_LH
Is the threshold Δα_TH2When it is larger, it holds. (9) Ninth condition The ninth condition is that the dynamic load radius for both right two wheels
Estimated value β is the threshold value β _TH1(For the right front wheel) or β_TH2
(For the right rear wheel) smaller and on both left wheels
For this reason, the estimated dynamic load radius β is the threshold β_TH1(Front left
(For a wheel) or β_TH2(For the left rear wheel) If it is above
The difference Δα between the left and right front wheels with respect to the resonance frequency α
_FOr the difference between the left and right rear wheels Δα_RIs the threshold Δα_TH1Greater than
It is established at a certain time. (10) Tenth condition The tenth condition is that the dynamic load is half for both the left two wheels.
Diameter estimate β is threshold β_TH1(For left front wheel) or β
_TH2Smaller than (for the left rear wheel) and two wheels on the right side
In this case, the estimated dynamic load radius β is the threshold β
_TH1(For the right front wheel) or β_TH2(For the right rear wheel)
The difference Δα_FOr the difference Δα_RIs the threshold
Δα_TH1When it is larger, it holds.

Here, the correlation determination routine will be described in detail with reference to FIG.

In this correlation determining routine, first, in step S101, the estimated dynamic load radius α _FR of the right front wheel is set.
Is smaller than the threshold β _TH1 . This time, assuming that it is small, the determination is YES and S10
At 2, it is determined whether the estimated dynamic load radius β _FL of the left front wheel is smaller than the threshold β _TH1 . If it is small this time, the determination is yes, and the process proceeds to S103.

In S103, it is determined whether the estimated dynamic load radius β _RR of the right rear wheel is equal to or greater than the threshold β _TH2 . This time, if it is assumed that the threshold value is β _TH2 or more, the determination is YES, and it is determined in S105 whether the estimated dynamic load radius β _RL of the left rear wheel is the threshold β _TH2 or more. It This time, assuming that the threshold value is _{equal to} or greater than the threshold value β _TH2 , the determination is YES, and the process proceeds to S106.

At S106, the difference Δα _RH and the difference Δα _LH are calculated, and the calculated difference Δα _RH is calculated.
_It is determined whether or not at least one of the fact that _RH is larger than the threshold value Δα _TH2 and that the calculated difference Δα _LH is larger than the threshold value Δα _TH2 are satisfied. That is,
It is determined whether or not the seventh condition is satisfied.

This time, assuming that the condition is satisfied, the judgment is Y.
ES is reached, and it is determined in S107 that a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. On the other hand, if it is not established this time, the determination is NO, and in S108, it is determined that the correlation does not hold between the resonance frequency estimated value α and the dynamic load radius estimated value β.

In either case, one execution of this correlation determining routine is completed.

The determination in S103 or S105 is N.
When it is O, in S104, this time, it is determined that the relationship between the resonance frequency estimated value α and the dynamic load radius estimated value β is indefinite.

[0143] In addition, in addition, the correlation determination with the indefiniteness is determined as the correlation determination between the resonance frequency estimated value α and the dynamic load radius estimated value β, or the correlation determination not performed. It can be handled in the same manner as judgment.

If the correlation determination with the indefiniteness is treated in the same manner as the correlation determination with the incomplete, the determination of S32 in FIG. 6 is made when the correlation determination with the indefiniteness is performed. Becomes NO, and as a result, the determination that the tire pressure is abnormal is avoided. As a result, in a vehicle environment in which the tire abnormality determination device does not conform, due to the incompatibility, the tire pressure may be erroneously determined to be abnormal even though the tire pressure is truly normal. Occurrence is avoided.

Thus, one execution of this correlation determining routine is completed.

Although the determination in S101 is YES, S10
If the determination of 2 is NO, it is determined in S109 whether the estimated dynamic load radius β _RR of the right rear wheel is smaller than the threshold β _TH2 . This time, assuming it's small,
The determination is YES, and in S110, it is determined whether the estimated dynamic load radius β _RL of the left rear wheel is equal to or greater than the threshold β _TH2 . This time, assuming that the threshold value is _{equal to} or greater than the threshold value β _TH2 , the determination becomes YES, and the process proceeds to S111.

At S111, the difference Δα_Fand
Difference Δα_RIs calculated and the calculated difference Δα_F
Is the threshold Δα_TH1Greater than and its calculated
Difference Δα _RIs the threshold Δα_TH1At least with greater
Also, it is determined whether or not one is established. The ninth condition
It is determined whether or not is satisfied.

This time, assuming that the condition is satisfied, the judgment is Y.
ES is reached, and it is determined in S107 that a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. On the other hand, if it is not established this time, the determination is NO, and in S108, it is determined that the correlation does not hold between the resonance frequency estimated value α and the dynamic load radius estimated value β.

In either case, the execution of this correlation determining routine is completed.

The determination in S109 or S110 is N.
When it is O, in S104, this time, it is determined that the relationship between the resonance frequency estimated value α and the dynamic load radius estimated value β is indefinite. With the above, one execution of this correlation determination routine is completed.

If the determination in S101 is no, S
At 112, it is determined whether the estimated dynamic load radius β _FL of the left front wheel is greater than or equal to the threshold β _TH1 . This time, assuming that it is equal to or greater than the threshold value β _TH1 , the determination becomes YES, and in S113, the estimated dynamic load radius value β of the right rear wheel is set.
_It is determined whether _RR is smaller than the threshold value β _TH2 . This time, assuming that it is small, the determination is YES and S1
Move to 14.

In S114, it is determined whether the estimated dynamic load radius β _RL of the left rear wheel is smaller than the threshold β _TH2 . This time, assuming that it is small, the judgment is YES.
Then, the process proceeds to S106, and it is determined whether the eighth condition is satisfied. After that, S107 or S108 is selectively executed according to the judgment of S106, and the above is the end of one execution of this correlation judgment routine.

The determination in S113 or S114 is N.
If it is O, the one-time execution of this correlation determination routine ends through S104.

If the determinations in S101 and S112 are both NO, it is determined in S115 whether the estimated dynamic load radius β _RR of the right rear wheel is equal to or greater than the threshold β _TH2 . If it is assumed that the threshold value is _{equal to} or greater than the threshold value β _TH2 this time, the determination is YES and the process proceeds to S116.

In S116, it is determined whether the estimated dynamic load radius β _RL of the left rear wheel is smaller than the threshold β _TH2 . This time, assuming that it is small, the judgment is YES.
Then, the process proceeds to S111, and it is determined whether the tenth condition is satisfied. Then, S106
S107 or S108 is selectively executed according to the judgment of No., and the above is the end of one execution of this correlation judgment routine.

The determination in S115 or S116 is N.
If it is O, the one-time execution of this correlation determination routine ends through S104.

As is clear from the above description, in the present embodiment, S101 and S1 in FIG.
02, S103, S105, S109, S110 and S112 to S116 are the same as the above (1
It constitutes an example of the "first correlation determining means" in the item 0).

Further, in this embodiment, the decision unit 2
The portion of 0 that executes S106 and S111 of FIG. 9 constitutes an example of the "second correlation determining means" in the item (11).

In addition, it should be noted that the correlation determining routine of this embodiment can be used in combination with the correlation determining routine of the first embodiment. In this case, when it is determined by the correlation determining routine in the first embodiment that the correlation is established, the determination result is maintained independently of the determination result by the correlation determining routine in the present embodiment, while the first embodiment is performed. When it is determined that the correlation is not established by the correlation determination routine in 1), the present invention can be implemented in such a manner that the determination result is overridden by the determination result by the correlation determination routine in the present embodiment.

Next, a third embodiment of the present invention will be described.
However, the present embodiment has a common hardware configuration with the first or second embodiment, and has a common software configuration except for the correlation determination routine. Therefore, common elements are given the same names and reference numerals. Detailed descriptions will be omitted by using and quoting, and only different elements will be described in detail.

In the second embodiment, the dynamic load radius estimated value β is either one of the two coaxial wheels or one of the two wheels.
It is determined whether or not a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β under the condition that both wheels having only wheels, that is, both of the two vehicles related to each other, are reduced. To be done.

On the other hand, in the present embodiment, the correlation between the resonance frequency estimated value α and the dynamic load radius estimated value β is provided on the condition that the dynamic load radius estimated value β is reduced for only one wheel. It is determined whether or not is satisfied.

FIG. 11 is a flowchart conceptually showing the contents of the correlation determining routine in this embodiment. Hereinafter, this correlation determination routine will be described in detail, but prior to that, it will be schematically described with reference to FIG.

FIG. 12 shows the resonance frequency in this embodiment.
Correlation is established between the number estimate α and the dynamic load radius estimate β
The four conditions that should be met in order to determine that
It is represented in the format. The contents of those conditions are explained below.
It (11) Eleventh condition Eleventh condition is the estimated dynamic load radius for the right front wheel.
β is the threshold β_TH1Smaller and other wheels
For, the dynamic load radius estimate β is the threshold β _TH1(left
Front wheel) or threshold β_TH2(For each rear wheel)
In some cases, left and right front with respect to the resonance frequency estimation value α
Difference between rings Δα_FIs the threshold Δα_TH1When it is larger,
Stand up. Here, the left and right front wheels are the left and right front wheels and the left and right rear wheels.
Of the (pair of coaxial wheels), the estimated dynamic load radius β is
Value β_THThe smaller right front wheel belongs. (12) Twelfth condition The twelfth condition is the estimated dynamic load radius for the left front wheel.
β is the threshold β_TH1Smaller and other wheels
For, the dynamic load radius estimate β is the threshold β _TH1(right
Front wheel) or threshold β_TH2(For each rear wheel)
In some cases, left and right front with respect to the resonance frequency estimation value α
Difference between rings Δα_FIs the threshold Δα_TH1When it is larger,
Stand up. Here, the left and right front wheels are the left and right front wheels and the left and right rear wheels.
Of the (pair of coaxial wheels), the estimated dynamic load radius β is
Value β_THThe smaller left front wheel belongs. (13) 13th condition The thirteenth condition is that the estimated dynamic load radius for the right rear wheel
β is the threshold β_TH2Smaller and other wheels
For, the dynamic load radius estimate β is the threshold β _TH1(each
Front wheel) or threshold β_TH2(For left rear wheel)
In some cases, left and right rear with respect to the resonance frequency estimate α
Difference between rings Δα_RIs the threshold Δα_TH1When it is larger,
Stand up. Here, the left and right rear wheels are the left and right front wheels and the left and right rear wheels.
Of the (pair of coaxial wheels), the estimated dynamic load radius β is
Value β_THThe smaller right rear wheel belongs. (14) Fourteenth condition The 14th condition is that the estimated dynamic load radius is for the left rear wheel.
β is the threshold β_TH2Smaller and other wheels
For, the dynamic load radius estimate β is the threshold β _TH1(each
Front wheel) or threshold β_TH2(For the right rear wheel)
In some cases, left and right rear with respect to the resonance frequency estimate α
Difference between rings Δα_RIs the threshold Δα_TH1When it is larger,
Stand up. Here, the left and right rear wheels are the left and right front wheels and the left and right rear wheels.
Of the (pair of coaxial wheels), the estimated dynamic load radius β is
Value β_THThe smaller left rear wheel belongs.

Here, the correlation determination routine in this embodiment will be described in detail with reference to FIG.

In this correlation determining routine, first, in step S201, the estimated dynamic load radius α _FR of the right front wheel is set.
Is smaller than the threshold β _TH1 . This time, assuming that it is small, the determination is YES and S20
At 2, it is determined whether the estimated dynamic load radius β _FL of the left front wheel is greater than or equal to the threshold β _TH1 . This time, if it is assumed that the threshold value is β _TH1 or more, the determination is YES, and the process proceeds to S203.

In S203, it is determined whether the estimated dynamic load radius β _RR of the right rear wheel is equal to or greater than the threshold β _TH2 . This time, if it is assumed that the threshold value is β _TH2 or more, the determination is YES, and in S204, it is determined whether the estimated dynamic load radius β _RL of the left rear wheel is the threshold β _TH2 or more. It This time, if it is assumed that the threshold value is _{equal to} or greater than the threshold value β _TH2 , the determination is YES, and the process proceeds to S205.

In step S205, the difference Δα _F is calculated, and the calculated difference Δα _F is set to the threshold Δ.
It is determined whether or not it is larger than α _TH1 . That is, it is determined whether or not the eleventh condition is satisfied.

This time, if it is assumed that the condition is satisfied, the judgment is Y.
ES is reached, and it is determined in S206 that a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. On the other hand, if it is assumed that this is not true this time, the determination is NO, and it is determined in S207 that no correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β.

In either case, this is the end of one execution of this correlation determining routine.

The determination in S203 or S204 is N.
If it is O, in S208, this time, it is determined that the relationship between the resonance frequency estimated value α and the dynamic load radius estimated value β is indefinite.

Although the determination in S201 is YES, S20
If the determination of 2 is NO, the execution of this correlation determination routine once ends through S208.

If the determination in S201 is no, S
At 209, it is determined whether the estimated dynamic load radius β _FL of the left front wheel is smaller than the threshold β _TH1 . This time, if it is assumed to be small, the determination is YES, and the steps from S203 are executed in the same manner as in the above case. This time, by determining whether or not the twelfth condition is satisfied, it is determined whether or not a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β. With the above, one execution of this correlation determination routine is completed.

On the other hand, this time, assuming that the estimated dynamic load radius β _FL of the left front wheel is not smaller than the threshold value β _TH1 , the determination in S209 is NO, and the process proceeds to S210.

In S210, it is determined whether the estimated dynamic load radius β _RR of the right rear wheel is smaller than the threshold β _TH2 . This time, assuming that it is small, the judgment is YES.
Then, in S211, it is determined whether or not the estimated dynamic load radius value β _RL of the left rear wheel is equal to or greater than the threshold value β _TH2 .
This time, assuming that the threshold value is _{equal to} or greater than the threshold value β _TH2 , the determination is yes, and the process proceeds to S212.

In S212, the difference Δα _R is calculated, and the calculated difference Δα _R is set to the threshold Δ.
It is determined whether or not it is larger than α _TH1 . It is determined whether or not the thirteenth condition is satisfied.

After that, S206 or S207 is selectively executed according to the determination result of S212.
One execution of this correlation determination routine ends.

When the determination in S211 is NO, S
After 208, one execution of this correlation determination routine ends.

When the determination in S210 is NO, S
At 213, it is determined whether the estimated dynamic load radius β _RL of the left rear wheel is smaller than the threshold β _TH2 . This time, if it is assumed to be small, the determination is YES, and the steps from S212 are executed in the same manner as in the above case. This time, it is determined whether or not the correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β by determining whether or not the fourteenth condition is satisfied. With the above, one execution of this correlation determination routine is completed.

If the determination in S213 is NO, the execution of this correlation determining routine is completed once through S208.

As is apparent from the above description, in the present embodiment, the part of the decision unit 20 that executes S201 to S204 and S209 to S213 of FIG. 11 is the "first correlation" in the above item (10). This constitutes an example of "sex determining means".

Further, in this embodiment, the decision unit 2
The part of 0 that executes S205 and S212 of FIG. 11 is the “second correlation determining means” in the above (11).
It constitutes one example.

In addition, it should be noted that the correlation determination routine of this embodiment can be used in combination with the correlation determination routine of the first or second embodiment. In this case, when it is determined by the correlation determining routine in the first or second embodiment that the correlation is established, the determination result is maintained regardless of the determination result by the correlation determining routine in the present embodiment. When it is determined that the correlation is not established by the correlation determination routine of the first or second embodiment, the present invention can be implemented in a manner that the determination result is overridden by the determination result of the correlation determination routine of the present embodiment. Is.

Next, a fourth embodiment of the present invention will be described.
However, the present embodiment has a common hardware configuration with the first to third embodiments, and has the same software configuration except for the air pressure drop determination routine.
The common elements are referred to by using the same names and reference numerals to omit detailed description, and only different elements will be described in detail.

In the first to third embodiments, when it is determined that the tire air pressure is lowered in at least one of the resonance frequency estimated value α and the dynamic load radius reflection value R. Finally, it is determined that the tire air pressure has dropped.

On the other hand, in the present embodiment, when it is determined that the tire air pressure is lowered both when the resonance frequency estimated value α is focused and when the dynamic load radius reflected value R is focused. Is finally determined to be a decrease in tire pressure.

FIG. 13 is a flow chart conceptually showing the contents of the air pressure drop determination routine in this embodiment.

In this air pressure drop determination routine,
First, in S301, correlation determination is performed. This correlation determination is executed by executing a correlation determination routine similar to the correlation determination routine in the first to third embodiments.

Next, in S302, it is determined whether or not a correlation is established between the resonance frequency estimated value α and the dynamic load radius estimated value β in S301. If it is determined that the correlation is established this time, the determination is YES.

Subsequently, in S303, it is determined whether or not the tire air pressure is reduced according to the first determination rule. Specifically, as in S33 of FIG. 6, for example, it is determined whether or not there are air pressure lowering wheels among the plurality of wheels.

This time, assuming that there is a wheel with reduced air pressure, the determination is YES, and in S304, it is determined whether or not the tire air pressure is reduced according to the second determination rule. Specifically, for example, the dynamic load radius reflection value R is calculated in the same manner as in S34 of FIG. 6, and further, the dynamic load radius reflection value R thus calculated and the calculation in the initialization step. Initial value Y ₀
It is determined whether the difference between and is larger than the threshold value B.

This time, assuming that the difference is larger than the threshold value B, the determination is YES, and in S305,
The low flag is set. This is the end of one execution of the air pressure decrease determination routine.

On the other hand, if the determination in S303 or S304 is NO, the reduction flag is reset in S306. This is the end of one execution of the air pressure decrease determination routine.

Similarly, when the determination in S302 is NO, one execution of this air pressure decrease determination routine is completed through S306.

As is apparent from the above description, in the present embodiment, the part of the determiner 20 that executes S303 to S305 of FIG. 13 is an example of the "second abnormality determining means" in the item (9). Is configured.

Some of the embodiments of the present invention have been described above in detail with reference to the drawings. However, these are merely examples, and the embodiments described in the section [Means for Solving the Problems and Effects of the Invention] are described. It is possible to carry out the present invention in other forms in which various modifications and improvements are made based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a block diagram showing a hardware configuration of a tire abnormality determination device according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a hardware configuration of a computer in FIG.

FIG. 3 is a flowchart conceptually showing the content of a tire abnormality determination program in FIG.

FIG. 4 is a graph for explaining characteristics with respect to a tire pressure for each of a resonance frequency, a dynamic load radius related value, and a dynamic load radius reflected value used as variables in the tire abnormality determination program of FIG.

5 is a graph for conceptually explaining execution contents of S3 to S8 in FIG.

FIG. 6 is a flowchart conceptually showing the details of S9 in FIG. 3 as an air pressure drop determination routine.

7 is a flowchart conceptually showing the details of S31 in FIG. 6 as a correlation determination routine.

FIG. 8 is a diagram for explaining, in a tabular form, six conditions for determining success or failure in the correlation determination routine of FIG.

FIG. 9 is a flowchart conceptually showing the content of a correlation determination routine of a tire abnormality determination program in the tire abnormality determination device according to the second embodiment of the present invention.

FIG. 10 is a diagram for explaining, in a tabular form, four conditions for determining success or failure in the correlation determination routine of FIG.

FIG. 11 is a flowchart conceptually showing the content of a correlation determination routine of the tire abnormality determination program in the tire abnormality determination device according to the third embodiment of the present invention.

FIG. 12 is a diagram for explaining, in a tabular form, four conditions for determining success or failure in the correlation determination routine of FIG. 11.

FIG. 13 is a flowchart conceptually showing the contents of an air pressure drop determination routine of the tire abnormality determination program in the tire abnormality determination device according to the fourth embodiment of the present invention.

[Explanation of symbols]

10 Wheel speed sensor 20 Judgment device 22 Computer 32 ROM 40 alarm

Claims (6)

[Claims] 1. A device provided in a vehicle equipped with a plurality of wheels in which air is sealed under pressure inside a tire mounted on the wheels, wherein the tire pressure is determined for the plurality of wheels. A plurality of wheel speed sensors that are provided in relation to the respective wheels and that detect the wheel speed of each wheel, and a plurality of different estimates based on the wheel speed detected by each wheel speed sensor for each wheel. According to the rule, each of a plurality of types of reflection values reflecting the tire pressure is estimated, and among the estimated plurality of types of reflection values, regarding a tire pressure of the same wheel or the same wheel group, a predetermined correlation is established. In this case, at least one of a plurality of determination rules predetermined according to the plurality of estimation rules is used to determine the tire pressure.
And a tire pressure determination device including a determination device according to one of the claims. 2. The judging device according to each of the plurality of estimation rules for each wheel, based on the plurality of wheel speeds sequentially detected by the respective wheel speed sensors in the same temporal section, The tire air pressure determination device according to claim 1, further comprising reflection value estimation means for estimating a reflection value. 3. The determination device according to claim 1, further comprising abnormality determination avoiding means for avoiding determination that the tire air pressure is abnormal when the predetermined correlation is not established. Tire pressure determination device. 4. The determination result of the tire air pressure obtained according to at least one of the plurality of determination rules is an abnormality of the tire air pressure when the determiner establishes the predetermined correlation. The tire air pressure determination device according to any one of claims 1 to 3, further comprising: first abnormality determination means that determines that the tire air pressure is abnormal. 5. If the determination unit establishes the predetermined correlation, all the plurality of determination results of the tire air pressure obtained according to the plurality of determination rules are abnormal tire pressures. The tire air pressure determination device according to any one of claims 1 to 3, further comprising a second abnormality determination means that determines that the tire air pressure is abnormal. 6. The resonance frequency of the tire vibration or a physical quantity related to the resonance frequency of the plurality of types of reflection values is calculated based on the wheel speed detected by each wheel speed sensor, for each wheel, based on the wheel speed detected by each wheel speed sensor. Based on the first estimation rule that is estimated as one and the wheel speed detected by each wheel speed sensor for each wheel, the dynamic load radius of the tire or a physical quantity related thereto is set to one of the reflection values of the plurality of types. And a second observer that estimates a change in the tire air pressure as a disturbance to the tire for each wheel, based on the wheel speed detected by each wheel speed sensor. Third estimated as one of multiple types of reflection values
And the vibration level in a specific frequency region of the wheel speed signal, which is time-series data of the wheel speed detected by each wheel speed sensor, is estimated for each wheel as one of the plurality of reflection values. At least two of the fourth estimation rules
The tire air pressure determination device according to any one of claims 1 to 5, including one.