JP3303660B2 - Tire pressure determination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire pressure judging device for estimating the air pressure of a tire of an automobile or the like and judging whether or not the air pressure is abnormal. And a tire pressure determination device for estimating and determining the tire pressure.

[0002]

2. Description of the Related Art The fact that there is a fixed relationship between the tire air pressure and the tire spring constant and that there is a fixed relationship between the tire spring constant and the tire resonance frequency makes use of the wheel. A tire pressure determination device that determines a resonance frequency in a vertical direction or a front-rear direction of a tire based on a vibration component of a speed signal, and estimates a tire pressure from the tire to determine an abnormality based on the resonance frequency has conventionally been proposed in various configurations. One example is described in, for example, JP-A-5-133831.

According to such a tire pressure judging device, there is no need to provide a sensor for detecting the pressure in the tire on the rotating wheel or to transmit a signal indicating the detection result from the sensor in a wireless manner. And an abnormality can be determined. However, for example, when the vehicle speed increases and the wheel speed becomes equal to or higher than a predetermined value, it becomes difficult to determine the tire vibration phenomenon based on the signal from the wheel speed sensor. Therefore, the tire air pressure is estimated based on the detection result of the disturbance torque. There is a problem that the tire pressure cannot be estimated by a conventional tire pressure determining device of a so-called disturbance observer method or a conventional tire pressure determining device of a so-called FFT method that estimates the tire pressure based on the resonance frequency of the tire. .

As means for solving the above problems, for example, Japanese Patent Application No. 7-1 filed with a joint application between the present applicant and two other persons
As described in the specification of Japanese Patent No. 71477, it is determined whether or not the vehicle is running at a high speed where the vehicle speed is equal to or higher than a predetermined value. If the vehicle is not running at a high speed, the tire pressure is estimated by a disturbance observer method or an FFT method. When the vehicle is running, it is conceivable that the relationship between the dynamic load radii of the tires is obtained from the wheel speed signal based on the dynamic load radius method, and the tire pressure is estimated based on this.

[0005]

However, by estimating the tire air pressure by the dynamic load radius method, only the relative air pressure relationship can be known. Therefore, the air pressure cannot be accurately estimated and the abnormality cannot be accurately determined. The upper limit vehicle speed at which the tire pressure can be estimated by the disturbance observer method or the FFT method is not a value common to all four wheels, but depends on the support load of the wheels. The higher the support load, the higher the upper limit vehicle speed.
In general, since the support load of the front wheels is higher than the support load of the rear wheels, the estimation of the tire pressure of the front wheels by the disturbance observer method or the FFT method can be performed up to a vehicle speed range higher than the rear wheels.

However, in the tire pressure judging device according to the above proposal, when the vehicle speed exceeds the upper limit vehicle speed of the rear wheels, the judgment of the tire pressure of the front wheels is also switched to the dynamic load radius method. The tire air pressure of the front wheels in the vehicle speed range higher than the upper limit vehicle speed of the wheels and lower than the upper limit vehicle speed of the front wheels cannot be accurately estimated, and the abnormality cannot be determined accurately.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the conventional tire pressure judging apparatus, and a main object of the present invention is to provide a disturbance observer system or an FFT system and a dynamic load radius system. By estimating the tire pressure by the method and selecting the estimation result by both methods according to the wheel speeds of the front and rear wheels, the tire pressure is estimated and determined as accurately as possible even in a relatively high vehicle speed range. That is.

[0008]

According to the present invention, there is provided a tire pressure determining apparatus for estimating and determining tire pressure based on a wheel speed signal. First tire pressure estimating means for obtaining the tire spring constant from the vibration component of the wheel speed signal and estimating the tire air pressure based on the tire constant; and obtaining the relationship between the tire's dynamic load radius from the wheel speed signal and the tire air pressure based on this. a second tire pressure estimation means for estimating a, a first counter for the average wheel speed of the front wheels is counted up when the above first wheel speed reference value, the average wheel speed of the rear wheels second wheel speed A second counter that counts up when the count value is equal to or greater than a reference value, and a second counter that counts up when the count value of the first counter is equal to or less than a first determination reference value. To determine the abnormal air pressure of the tire,
When the count value of the first counter exceeds the first determination reference value, front wheel pressure determination means for determining an abnormality in the front tire pressure based on the estimated value by the second tire pressure estimation means; and When the count value of the counter is equal to or less than the second determination reference value, it is determined that the tire pressure of the rear wheel is abnormal based on the estimated value by the first tire pressure estimation means, and the count value of the second counter is And a rear wheel pressure judging device for judging an abnormal air pressure of the rear tire based on the estimated value by the second tire pressure estimating device when the second reference value is exceeded. Is done.

According to the configuration of the first aspect, the flatness of the front wheel is provided.
When the average wheel speed is equal to or higher than the first wheel speed reference value, the first
And the average rear wheel speed is
The second counter counts when the wheel speed
When the count value of the first counter is equal to or less than the first determination reference value, it is determined that the tire pressure of the front wheel is abnormal based on the value estimated by the first tire pressure estimation means,
When the count value of the first counter exceeds the first determination reference value, it is determined that the tire pressure of the front wheel is abnormal based on the value estimated by the second tire pressure estimation means, and the count value of the second counter is equal to the second value. When the tire pressure is equal to or less than the determination reference value, an abnormality in the tire pressure of the rear wheel is determined based on the estimated value by the first tire pressure estimation means, and when the count value of the second counter exceeds the second determination reference value, the second tire is determined. An abnormality in the tire pressure of the rear wheel is determined based on the estimated value by the air pressure estimating means. Even in a relatively high vehicle speed range, the tire pressure is accurately estimated and determined.

According to one particular aspect of the invention,
In order to effectively achieve the above-mentioned main problem, in the configuration of claim 1, the first wheel speed reference value is set according to a supporting load of a front wheel, and the second wheel speed reference value is The setting is made according to the supporting load of the rear wheel (the configuration of claim 2).

According to the configuration of the second aspect, since the first and second wheel speed reference values are set according to the supporting loads of the front wheels and the rear wheels, respectively, the supporting loads of the front wheels and the rear wheels are different. The higher wheel speed reference value is set higher than the other,
Therefore, as compared with the case where the tire pressure estimating means of the front wheel and the rear wheel are simultaneously switched depending on whether the vehicle speed is equal to or higher than the reference value, the air pressure of the tire having the higher support load among the front wheel and the rear wheel is relatively high. It is accurately estimated and determined even in the vehicle speed range.

According to another specific feature of the present invention, there is provided a method for effectively solving the above-mentioned main problem.
In the configuration, the second tire pressure estimating means is configured to estimate the tire pressure of the front and rear wheels based on the wheel speed ratio of the corresponding front and rear wheels, and the supporting load of the front wheels is larger than the supporting load of the rear wheels. High, the first wheel speed reference value is higher than the second wheel speed reference value, the count value of the first counter is less than or equal to the first determination reference value, and the count value of the second counter When the value exceeds the second determination reference value, the rear wheel pressure determining means determines the estimated value of the corresponding front wheel tire pressure estimated by the first tire pressure estimating means and the second tire pressure estimating means. Is configured to determine an abnormality in the air pressure of the rear wheel tire based on the estimated value by the following method.

According to the third aspect of the present invention, when the count value of the first counter is equal to or less than the first determination reference value and the count value of the second counter exceeds the second determination reference value, Since the abnormality in the rear wheel tire pressure is determined based on the estimated value of the corresponding front wheel tire pressure estimated by the first tire pressure estimation means and the estimated value by the second tire pressure estimation means, the first The abnormal air pressure of the rear wheel tire is accurately determined as compared to a case where the corresponding estimated value of the air pressure of the front wheel tire estimated by the tire air pressure estimating means is not considered.

[0014]

According to a preferred aspect of the present invention, in the configuration of the first aspect, the first tire pressure estimating means calculates a predetermined number of wheel speed signals and the estimated tire pressure. A predetermined number of wheel speed signals for the left and right front wheels are stored in the storage means, and the spring constants of the right and left front wheels are obtained from the vibration components of the predetermined number of wheel speed signals. A step of estimating the tire pressure of the tire, a step of clearing a predetermined number of wheel speed signals of the left and right front wheels from the storage means when the estimation of the tire pressure of the left and right front wheels is completed, and storing a predetermined number of wheel speed signals of the left and right rear wheels Means for obtaining the spring constants of the left and right rear wheel tires from the vibration components of the predetermined number of wheel speed signals, estimating the air pressure of the left and right rear wheel tires based thereon, and calculating the air pressure of the right and left rear wheel tires. Presumption Ryosuru and configured to repeatedly perform the step of clearing from the storage means a predetermined number of wheel speed signals of the left and right rear wheels.

According to this configuration, a predetermined number of wheel speed signals are stored in the storage means for all four wheels, and the tire pressures are estimated for all four wheels substantially simultaneously. In addition, the storage capacity of the storage means can be reduced, and the cost of the tire pressure determination device can be reduced.

In the first aspect of the present invention, the relationship between the dynamic load radii of the tires is obtained for estimating the tire air pressure. If the ratio of the dynamic load radii of the tires is obtained, the tire air pressure is reduced. Since it can be estimated, the "relationship of the dynamic load radius of the tire" is a concept including not only the dynamic load radius in the narrow sense, that is, the relationship of the dynamic load radius itself, but also the relationship of the value corresponding to the dynamic load radius in the narrow sense. .

[0017]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the accompanying drawings, in which: FIG.

FIG. 1 is a schematic diagram (A) and a block diagram (B) showing a first embodiment of a tire air pressure judging device according to the present invention.

In FIG. 1A, the left front wheel 10FL, the right front wheel 10FR, the left rear wheel 10RL, and the right rear wheel 10RR have their respective wheel speeds Vwi (i = fl, fr, rl, rr). Wheel speed sensors 12FL, 12FR, 12RL that detect
12RR is provided. A signal indicating the wheel speed Vwi is input to the tire pressure determining device 14, and the tire pressure determining device 14 estimates the tire pressure Pi (i = fl, fr, rl, rr) of each wheel based on the wheel speed Vwi as described later. Calculate,
By outputting a control signal to the alarm device 16 as necessary, an alarm is issued to the occupant of the vehicle.

As shown in FIG. 1B, the tire pressure judging device 14 obtains a spring constant of the tire from a vibration component of a wheel speed signal supplied from the wheel speed sensors 12FL to 12RR and, based on this, a tire air pressure. A first tire pressure estimating block 18 for estimating Pi, and a second tire pressure estimating block of a so-called dynamic load radius type for estimating the tire pressure Pi based on the relationship between the tire dynamic load radius based on the wheel speed signal. 20 and an X counter 22 as a first counter that counts up when the average wheel speed Vwf of the left and right front wheels is equal to or greater than a first wheel speed reference value Vwx (positive constant).
And the average wheel speed Vwr of the left and right rear wheels is the second wheel speed reference value V
A Y counter 24 is provided as a second counter that counts up when the value is equal to or more than wy (a positive constant).

Particularly, the vehicle to which the illustrated embodiment is applied is a general vehicle in which the front wheel support load is higher than the rear wheel support load, and the first wheel speed reference value Vwx is equal to the second wheel speed reference value. It is higher than Vwy. The first tire pressure estimation block 18 obtains an estimated disturbance from N (positive constant integer) wheel speed signals, obtains a tire spring constant from the estimated disturbance, and estimates a tire pressure based on the obtained disturbance observer. The system estimates the tire pressure.

The tire pressure judging device 14 has a front wheel pressure judging block 26 and a rear wheel air pressure judging block 28. As shown in Table 1 below, the front wheel air pressure determination block 26 determines that the count value X of the X counter is 0.
When the value is equal to or less than a criterion value M which is a positive constant larger than N and smaller than N, the first tire pressure estimation block 18
Are determined based on the estimated values Pflo and Pfro, and the abnormality in the front tire pressure is determined based on these estimated values. When the count value X of the X counter exceeds the determination reference value M, the estimation by the second tire pressure estimation block 20 is performed. Value Pfld
, Pfrd, and an abnormality in the air pressure of the front tire is determined based on these estimated values.

[Table 1] Count value X Estimated value of selected tire air pressure 0 ≦ X ≦ M Estimated value Pflo, Pfro M <X ≦ N of disturbance observer method Estimated value Pfld, Pfrd of dynamic load radius method

Similarly, as shown in Table 2 below, when the count value Y of the Y counter is equal to or less than the determination reference value M, the rear wheel pressure determination block 28 estimates the value Prlo by the first tire pressure estimation block 18. , Prro, and the tire pressure abnormality of the rear wheel is determined based on these estimated values. When the count value Y of the Y counter exceeds the determination reference value M, the estimated value Prld by the second tire pressure estimation block 20 is determined. Prrd is selected, and the tire pressure abnormality of the rear wheel is determined based on these estimated values.

Table 2 Count value Y Estimated value of tire pressure to be selected 0 ≦ Y ≦ M Estimated value Prlo, Prro M <Y ≦ N of disturbance observer method Estimated value Prld, Prrd of dynamic load radius method

The tire pressure judging device 14 is actually, for example, a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM).
And an input / output port device, which may be microcomputers connected to each other by a bidirectional common bus. This is the same for a second embodiment described later.

The tire pressure judging device 14 according to the first embodiment estimates the tire pressure Pi of each wheel according to the general flowchart shown in FIG. 2 and judges whether or not the tire pressure is abnormal. The control according to the flowchart shown in FIG. 2 is repeatedly executed at predetermined time intervals.
Further, in the flowchart shown in FIG.
o relates to whether or not the wheel whose tire pressure is estimated by the disturbance observer method is a front wheel, and 0 and 1 mean that the pressure estimation wheel is a front wheel and a rear wheel, respectively.

First, in step 10, a signal indicating the wheel speed Vwi is read, and in step 20, a number of pulse signals of the wheel speed at which the tire pressure can be estimated by the dynamic load radius method are read. If a negative determination is made, the wheel speed data is stored in step 30. If an affirmative determination is made, the dynamic load is calculated in step 40 according to the following equation (1). The tire pressure Pid of each wheel is estimated and calculated by the radius method.

## EQU1 ## Pfld = (Vwrl / Vwfl) * PfloPfrd = (Vwrr / Vwfr) * PfroPrld = (Vwfl / Vwrl) * Prlo Prrd = (Vwfr / Vwrr) * Prro

In the above equation 1, Pio (i = fl, fr, r
l, rr) are the latest air pressures calculated by the disturbance observer method in steps 90 and 150 described later,
When the air pressure Pio has not been calculated, the standard tire pressure Pni (i = fl, fr, r) of each wheel is used instead of Pio.
l, rr) (constant).

In step 50, it is determined whether or not the flag Fo is 0, that is, whether or not the wheel for estimating the air pressure by the disturbance observer method is the front wheel. Proceeding to 120, when an affirmative determination is made, the process of the X counter is performed in step 60 according to the routine shown in FIG.

In step 70, it is determined whether or not the wheel speed signals of the N left and right front wheels from which the tire pressure can be estimated by the disturbance observer method are read.
When a negative determination is made, the wheel speed data of the left and right front wheels is stored in step 80. When an affirmative determination is made, in step 90, the vibration component of the wheel speed signals of the left and right front wheels is obtained by a disturbance observer method. The spring constant of each tire is obtained, and the tire pressures Pflo and Pfro of the left and right front wheels are estimated and calculated based on the spring constant.

In step 100, the tire pressures Pflo, Pfr of the left and right front wheels are set according to the routine shown in FIG.
It is determined whether or not o is abnormal, and step 110
In this case, the wheel speed data of the left and right front wheels is cleared, and the flag Fo is set to 1.

In step 120, the process of the Y counter is performed in accordance with the routine shown in FIG. 5, and in step 130, the N left and right rear wheels capable of estimating the tire pressure by the disturbance observer method. It is determined whether or not the speed signal has been read. If a negative determination is made, the wheel speed data of the left and right rear wheels is stored in step 140, and if an affirmative determination is made, the process proceeds to step 150. In the disturbance observer method, the spring constant of each tire is obtained from the vibration component of the wheel speed signal of the right and left rear wheels, and based on this, the tire pressures Prlo and Prr of the right and left rear wheels are obtained.
o is estimated.

In step 160, the tire pressures Prlo and Prr of the left and right rear wheels are set in accordance with the routine shown in FIG.
A determination is made whether o is abnormal or not, and step 180
In this case, the wheel speed data of the left and right rear wheels and the tire pressure data of each wheel are cleared, and the flag Fo and the count values X and Y are reset to zero.

In general, when estimating the tire air pressure by the disturbance observer method, the estimated disturbance is obtained from the wheel speed signal by the disturbance observer, the tire spring constant is obtained from the estimated disturbance, and the tire air pressure is estimated based on this. However, the method of estimating the tire pressure by the disturbance observer method is well known in the art, and since various methods have been proposed in the related art, a detailed description thereof will be omitted.

At step 61 of the X counter processing routine at step 60, that is, at step 61 of the routine shown in FIG. 3, the average wheel speed Vwf of the left and right front wheels is calculated. At step 62, the average of the left and right front wheels is calculated. It is determined whether or not the wheel speed Vwf exceeds the wheel speed reference value Vwx. When a negative determination is made, the process directly proceeds to step 70, and when an affirmative determination is made, the count of the X counter is performed at step 63. The value X is incremented by one.

Further, in the front wheel tire pressure determination routine in step 100, that is, in step 101 of the routine shown in FIG. 4, it is determined whether or not the count value X of the X counter exceeds the determination reference value M. When the negative determination is made, the tire pressures Pfl and Pfr of the left and right front wheels are set to Pflo and Pfro respectively calculated in step 90 in step 102, and when the affirmative determination is made, the process proceeds to step 103. At this time, the tire pressures Pfl, Pfr of the left and right front wheels are set to Pfld, Pfrd calculated in step 40, respectively.

In step 104, it is determined whether or not the tire pressure Pfl of the left front wheel is less than a reference value Pcfl (positive constant) for abnormality determination. If a negative determination is made, the process proceeds directly to step 106. When the affirmative determination is made, a control signal is output to the alarm device 16 in step 105 to issue an alarm indicating that the tire pressure of the left front wheel is abnormal.

In step 106, it is determined whether or not the tire pressure Pfr of the right front wheel is smaller than a reference value Pcfr (positive constant) for abnormality determination. If a negative determination is made, the process directly proceeds to step 110. When the affirmative determination is made, a control signal is output to the alarm device 16 in step 107 to issue an alarm indicating that the tire pressure of the right front wheel is abnormal.

Similarly, the processing routine of the Y counter in step 120, that is, in step 121 of the routine shown in FIG. 5, the average wheel speed Vwr of the left and right rear wheels is calculated. Average rear wheel speed V
It is determined whether or not wr exceeds the wheel speed reference value Vwy (positive constant). If a negative determination is made, the process directly proceeds to step 130, and if an affirmative determination is made, Y is determined in step 123. The count value Y of the counter is incremented by one.

Further, in the rear wheel tire pressure determination routine in step 160, that is, in step 161 of the routine shown in FIG. 6, it is determined whether or not the count value Y of the Y counter exceeds the determination reference value M. When a negative determination is made, the tire pressures Prl and Prr of the left and right rear wheels are set to Prlo and Prro calculated in step 150, respectively, in step 162, and when an affirmative determination is made, the process proceeds to step 162. In 163, the tire pressures Prl and Prr of the left and right rear wheels are set to Prld and Prrd calculated in step 40, respectively.

In step 164, it is determined whether or not the tire pressure Prl of the left rear wheel is less than a reference value Pcrl (positive constant) for abnormality determination. If a negative determination is made, step 166 is performed. When the determination is affirmative, the control signal is output to the alarm device 16 in step 165 to issue an alarm indicating that the tire pressure of the left rear wheel is abnormal.

In step 166, it is determined whether or not the tire pressure Prr of the right rear wheel is less than a reference value Pcrr (positive constant) for abnormality determination. If a negative determination is made, step 180 is performed. When the affirmative determination is made, a control signal is output to the alarm device 16 in step 167 to issue an alarm indicating that the tire pressure of the right rear wheel is abnormal.

Thus, in this embodiment, when the vehicle runs at low to medium speed, the count value X of the X counter
Becomes equal to or less than the determination reference value M, the tire pressures of the left and right front wheels become the estimated values Pflo, Pfro of the disturbance observer method.
It is determined whether or not there is an abnormality on the basis of, and when the count value Y of the Y counter becomes equal to or less than the determination reference value M,
It is determined whether the tire pressures of the left and right rear wheels are abnormal based on the estimated values Prlo and Prro of the disturbance observer method,
Therefore, it is possible to accurately determine the abnormality of the tire air pressure not only in the case of puncture but also in the case of natural decompression.

When the vehicle runs at high speed, X
Although the count value X of the counter is equal to or less than the determination reference value M,
In some cases, the count value Y of the Y counter exceeds the determination reference value M. In this case, it is determined whether the tire pressures of the left and right front wheels are abnormal based on the estimated values Pflo and Pfro of the disturbance observer method. It is possible to accurately determine the abnormality of the tire pressure of the left and right front wheels, and it is determined whether the tire pressure of the right and left rear wheels is abnormal based on the estimated values Prld and Prrd of the dynamic load radius method. Abnormalities in the tire air pressure of the left and right rear wheels can be reliably determined.

When the vehicle travels at a higher vehicle speed, both the count values X and Y exceed the determination reference value M, so that the tire pressures of all four wheels become the estimated values Pfld, Pfrd of the dynamic load radius method. , Prld, Prrd, it is determined whether or not there is an abnormality. Unless there is a special case where the left rear wheel or the right front wheel is punctured simultaneously, the abnormality of the tire pressure of each wheel is reliably determined. be able to.

Also, according to this embodiment, step 60
If the tire pressures of the left and right front wheels are estimated and determined by the disturbance observer method in Steps 100 to 100, Step 110
When the wheel speed data of the left and right front wheels is cleared at step 120, conversely, at steps 120 to 160, the tire pressures of the left and right rear wheels are estimated and determined by the disturbance observer method. Since the speed data is cleared, N wheel speed data for all four wheels are stored in a storage device such as a RAM, and the air pressures of all four wheels are estimated and determined substantially simultaneously. The storage capacity of the storage device may be small, so that the cost of the tire pressure determination device can be reduced.
This is the same for the second embodiment described later.

FIG. 7 is a general flowchart showing a main routine of tire pressure determination in the second embodiment of the tire pressure determination device according to the present invention, and FIG. 8 is a rear wheel pressure determination in the second embodiment. 9 is a flowchart showing a subroutine of FIG. Note that in FIGS. 7 and 8,
Steps corresponding to the steps shown in FIGS. 2 and 6 are given the same step numbers as those given in FIGS. 2 and 6, respectively.

The main routine of the tire pressure determination of this embodiment is the same as that of the first embodiment except that the rear tire pressure determination routine in step 160 is executed according to the routine shown in FIG. It is the same as the main routine.

Steps 161 to 168 of the rear tire pressure determination routine shown in FIG. 8 are executed in the same manner as in the above-described first embodiment. After completion of step 163, steps 169 to 174 are executed. You.

In step 169, it is determined whether or not the tire pressure Pfl of the left front wheel is less than a reference value Pcfl for determining an abnormality. If an affirmative determination is made, the process proceeds directly to step 171 and a negative determination is made. If so, go to step 170. In step 170, it is determined whether or not the tire pressure Prl of the left rear wheel is less than a reference value Pcrl for abnormality determination. If a negative determination is made, the process directly proceeds to step 172, and an affirmative determination is made. In step 171, a control signal is output to the warning device 16 in step 171 to issue a warning that the tire pressure of the left rear wheel is abnormal.

Similarly, in step 172, it is determined whether or not the tire pressure Pfr of the front right wheel is less than the reference value Pcfr for determining abnormality. If the determination is affirmative, the process proceeds directly to step 174, and the determination is negative. When the determination is made, the process proceeds to step 173. In step 173, it is determined whether or not the tire pressure Prr of the right rear wheel is less than a reference value Pcrr for abnormality determination. If a negative determination is made, the process directly proceeds to step 180, and an affirmative determination is made. In step 174, a control signal is output to the alarm device 16 to issue an alarm indicating that the tire pressure of the right rear wheel is abnormal.

Therefore, also in this embodiment, when the vehicle runs at low to medium speed, the count value X of the X counter
Becomes equal to or less than the determination reference value M, the tire pressures of the left and right front wheels become the estimated values Pflo, Pfro of the disturbance observer method.
It is determined whether or not there is an abnormality on the basis of, and when the count value Y of the Y counter becomes equal to or less than the determination reference value M,
It is determined whether the tire pressures of the left and right rear wheels are abnormal based on the estimated values Prlo and Prro of the disturbance observer method,
Therefore, it is possible to accurately determine the abnormality of the tire air pressure not only in the case of puncture but also in the case of natural decompression.

When the vehicle runs at high speed, X
Although the count value X of the counter is equal to or less than the determination reference value M,
The count value Y of the Y counter may exceed the determination reference value M. In this case, as shown in Table 3 below, it is determined whether or not the tire pressures of the left and right front wheels are abnormal based on the estimated values Pflo and Pfro of the disturbance observer method regardless of the count value Y. Therefore, it is possible to accurately determine the abnormality of the tire air pressure including the natural decompression of the left and right front wheels. In Table 3, (e) means that the tire pressure is estimated by the disturbance observer method, and (dynamic)
Means that the tire pressure is estimated by the dynamic load radius method, which is the same in Table 4 described later.

[0053]

[Table 3]

On the other hand, as shown in (A) in Table 4 below, it is determined whether or not the tire pressures of the right and left rear wheels are abnormal based only on the estimated values Prld and Prrd of the dynamic load radius method. Instead of being determined, as shown in Tables 5 and 6 below, the estimated values Pflo and Pfro of the corresponding disturbance observer method for the front wheels and the estimated values Prld and Prrd of the dynamic load radius method for the rear wheels are shown. Since it is determined whether or not there is an abnormality based on both of them, it is possible not only to reliably determine the abnormality of the tire pressure of the left and right rear wheels due to puncture as in the case of the first embodiment, but also to determine the right and left due to natural pressure reduction. An abnormality in the tire pressure of the rear wheel can also be reliably determined.

[0055]

[Table 4]

[0056]

[Table 5]

[0057]

[Table 6]

In Tables 5 and 6, the estimated value Pflo or Pfro of the front wheels by the disturbance observer method is the pressure to be warned, and the estimated value P of the rear wheels by the dynamic load radius method.
When rld or Prrd is a normal value, there is a case where only the tire pressure of the front wheel is abnormal and the tire pressure of the rear wheel is normal, but when the estimated value of the front wheel is not considered, the tire of the rear wheel is not considered. Although the tire pressure of the corresponding front wheel may be determined to be normal due to the abnormal tire pressure even though the air pressure is abnormal, according to the illustrated embodiment, in such a situation, Since it is always determined to be abnormal, it is possible to reliably determine an abnormality in the tire pressure of the rear wheels as compared with a case where the estimated value of the front wheels is not considered.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and various other embodiments may be included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, in the first and second embodiments described above, the tire pressure Pio is calculated by the disturbance observer method in steps 90 and 150. The tire pressure may be calculated in any manner as long as the tire's spring constant is determined from the vibration component of the wheel speed signal and the tire pressure is calculated based on this.For example, the wheel speed may be calculated from the wheel speed signal. A so-called FFT in which a signal indicating a vibration component is extracted and frequency analysis is performed on the signal to calculate a tire resonance frequency, obtain a tire spring constant based on the resonance frequency, and calculate a tire air pressure. It may be performed by a method.

In the first and second embodiments, the reference values for the count value X and the count value Y, that is, the first reference value for the first counter and the reference value for the second counter are used. Although the two criterion values are the same M, the criterion values of the respective counters may be set to different values.

Further, the vehicle in the first and second embodiments is a general vehicle in which the supporting load of the front wheels is higher than the supporting load of the rear wheels. In the case of a vehicle in which the support load of the wheels is higher than the support load of the front wheels, the reference value Vwy for determining the wheel speed of the rear wheels is larger than the reference value Vwx of the wheel speed for the front wheels in accordance with the relationship between the support loads of the front and rear wheels. Set to a large value.

[0063]

As is apparent from the above description, according to the structure of the first aspect of the present invention, the average wheel speed of the front wheels is equal to the first wheel speed.
The first counter counts when the wheel speed reference value is
And the average wheel speed of the rear wheels is below the second wheel speed reference value.
When it is above, the second counter is counted up, and when the count value of the first counter is equal to or less than the first determination reference value, it is determined that the tire pressure of the front wheel is abnormal based on the value estimated by the first tire pressure estimation means. When the count value of the first counter exceeds the first determination reference value, it is determined that the tire pressure of the front wheel is abnormal based on the estimated value by the second tire pressure estimation means, and the count value of the second counter is equal to the second tire pressure. When it is equal to or less than the second determination reference value, it is determined that the tire pressure of the rear wheel is abnormal based on the estimated value by the first tire pressure estimation means, and when the count value of the second counter exceeds the second determination reference value, the second The tire pressure abnormality of the rear wheel is determined on the basis of the estimated value by the tire pressure estimating means. Therefore, the front and rear wheel pressures are determined based on whether the vehicle speed is equal to or higher than the reference value. The tire pressure of each wheel can be accurately estimated even in a relatively high vehicle speed range, as compared with the case where the tire pressure estimation means are switched at the same time, thereby accurately determining the abnormality of the tire pressure of each wheel. can do.

According to the second aspect of the present invention, the first and second wheel speed reference values are set according to the supporting loads of the front wheels and the rear wheels, respectively. Is higher than the other wheel speed reference value, so that the front wheel and rear wheel tire pressure estimating means are simultaneously switched depending on whether the vehicle speed is equal to or higher than the reference value. In addition, the air pressure of the tire having the higher support load among the rear wheels can be accurately estimated even in a relatively high vehicle speed range, whereby the abnormality of the air pressure of the tire can be accurately determined.

According to the third aspect of the present invention, when the count value of the first counter is equal to or less than the first judgment reference value and the count value of the second counter exceeds the second judgment reference value, Since the tire pressure abnormality of the rear wheel is determined based on the estimated value of the corresponding front wheel tire pressure estimated by the first tire pressure estimating means and the estimated value by the second tire pressure estimating means, the first The tire pressure abnormality of the rear wheel can be accurately determined as compared with a case where the corresponding estimated value of the tire pressure of the front wheel estimated by the tire pressure estimating means is not considered.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram (A) and a block diagram (B) showing a first embodiment of a tire air pressure judging device according to the present invention.
It is.

FIG. 2 is a general flowchart illustrating a main routine of tire pressure determination according to the first embodiment.

FIG. 3 is a flowchart illustrating a subroutine of an X counter process according to the first embodiment.

FIG. 4 is a flowchart showing a subroutine for determining front wheel air pressure according to the first embodiment.

FIG. 5 is a flowchart illustrating a subroutine of a Y counter process according to the first embodiment.

FIG. 6 is a flowchart illustrating a subroutine for determining rear wheel air pressure according to the first embodiment.

FIG. 7 is a general flowchart illustrating a main routine of tire pressure determination according to a second embodiment.

FIG. 8 is a flowchart illustrating a subroutine for determining rear wheel air pressure according to the second embodiment.

[Explanation of symbols]

 12FL-12RR: Wheel speed sensor 14: Tire pressure determination device 16: Alarm device 18: First tire pressure estimation block 20: Second tire pressure estimation block 22: X counter 24: Y counter 26: Front wheel pressure determination block 28 … Rear wheel air pressure judgment block

Claims (3)

(57) [Claims] In a tire pressure determining apparatus for estimating and determining tire pressure based on a wheel speed signal, a tire spring constant is obtained from a vibration component of the wheel speed signal, and a tire pressure is estimated based on the spring constant. Tire pressure estimating means, a second tire pressure estimating means for obtaining a relationship between the dynamic load radius of the tire from the wheel speed signal and estimating the tire pressure based on the relationship, and an average wheel speed of the front wheels based on the first wheel speed reference A first counter that counts up when the value is equal to or greater than a value, a second counter that counts up when the average wheel speed of the rear wheels is equal to or greater than a second wheel speed reference value, and a count value of the first counter is When the pressure is equal to or less than the first determination reference value, it is determined that the tire pressure of the front wheel is abnormal based on the estimated value by the first tire pressure estimation means, and the count value of the first counter is equal to the first tire pressure value. A front wheel pressure judging means for judging an abnormality in the front wheel tire pressure based on an estimated value by the second tire pressure estimating means when the judgment reference value is exceeded; and a count value of the second counter being equal to or less than a second judgment reference value. In the case of, determine the tire pressure abnormality of the rear wheel based on the estimated value by the first tire pressure estimation means,
When the count value of the second counter exceeds the second determination reference value, there is provided rear wheel pressure determination means for determining a tire pressure abnormality of a rear wheel tire based on an estimated value by the second tire pressure estimation means. A tire pressure judging device characterized by the above-mentioned. 2. The tire air pressure judging device according to claim 1, wherein the first wheel speed reference value is set according to a front wheel supporting load, and the second wheel speed reference value is a rear wheel supporting load. A tire pressure determination device, wherein the tire pressure determination device is set according to the following. 3. The tire pressure judging device according to claim 1, wherein said second tire pressure estimating means is configured to estimate the tire pressure of the front and rear wheels based on the wheel speed ratio of the corresponding front and rear wheels. Is higher than the supporting load of the rear wheel, the first wheel speed reference value is higher than the second wheel speed reference value, and the count value of the first counter is the first determination reference value. Below and when the count value of the second counter exceeds the second determination reference value,
The rear wheel pressure determining means determines an abnormal air pressure of the rear wheel tire based on the estimated value of the corresponding front wheel tire pressure estimated by the first tire pressure estimating means and the estimated value by the second tire pressure estimating means. A tire pressure determining device for determining.