JPH08127207A - Tire air pressure detector - Google Patents

Abstract

PURPOSE: To give warning of air pressure drop by predicting tire air pressure exactly even after replacing a tire. CONSTITUTION: Pickup coils 2a-2d which transmit wheel speed signals including the oscillating frequency components of tires 1a-1d while a vehicle is running are mounted. An electronic controller 4 extracts the resonance frequency of the tires 1a-1d from wheel speed, and predicts wheel air pressure based on the extracted resonance frequency. If the predicted wheel air pressure is lower than prescribed limit air pressure, warning of air pressure drop is made and displayed on a display device 5. An up-tp-date switch 41 is provided, and when the switch 41 is turned on after replacing the tire, the electronic controller 4 changes and sets the limit air pressure based on the resonance frequency extracted at this time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire air pressure detecting device for detecting a tire air pressure, and more particularly to a tire air pressure detecting device preferably used for detecting a decrease in air pressure and issuing an alarm.

[0002]

2. Description of the Related Art Conventionally, as a device for detecting tire pressure in real time, there has been known a device for detecting the tire pressure by detecting the wheel speed of the lower hand of the same vehicle speed by utilizing the fact that the tire radius changes according to the pressure. Was there. However, there are large individual differences in tire radius due to wear, turning,
It is easily affected by vehicle running conditions such as braking. For radial tires, etc., which have become very popular in recent years, the air pressure is 1 kg /
Even if it is reduced by about cm ^2, the change in the tire radius is only about 1 mm, and for this reason, it is difficult to accurately predict the air pressure due to the change in the tire radius.

Therefore, the inventors have previously found that the resonance frequency of the tire (generated by the torsional vibration of the tire and the coupled vibration of the front and rear springs of the suspension) is included in the unsprung vibration frequency component of the vehicle. Attention was paid and a device for predicting tire air pressure based on such resonance frequency or spring constant was proposed (Japanese Patent Application No. 5-119607).

[0004]

Although the above-mentioned proposed device can more accurately predict the tire air pressure as compared with the conventional device based on the tire radius, it still has a point to be improved. . That is, even if the tire pressure is the same, the resonance frequency changes when the tire or the wheel is replaced. As a result, an error may occur in the air pressure detection, and an abnormal air pressure may be falsely alarmed.

The air pressure abnormality in this case means a tire air pressure condition that affects the functions of the tire and the vehicle under various running conditions of the vehicle, such as the contact state between the tire and the road surface, the life of the tire and the fuel consumption. Say. Therefore, the present invention solves such a problem, and an object of the present invention is to provide a tire air pressure detection device that can accurately predict tire air pressure by adapting to various vehicle forms even when tires or the like are replaced.

[0006]

In order to solve the above-mentioned problems, a tire pressure detection device according to the present invention outputs a running signal including a vibration frequency component of a tire installed in a vehicle when the vehicle is running. Means, an extracting means for extracting a tire resonance frequency or a tire spring constant from the traveling signal, and a tire air pressure predicting means for predicting a tire air pressure based on the resonance frequency or the tire spring constant extracted by the extracting means. In the tire air pressure detection device including: a signal generating means for generating a predetermined signal when the tire is replaced with a tire having a specified air pressure; a change in resonance frequency or spring constant extracted by the extracting means; And a signal generating means for storing a substantially linear relationship with the change in the air pressure of the vehicle in advance for each vehicle type. Said predetermined signal upon detecting of
Calculation for calculating the limit resonance frequency or the limit spring constant for the limit air pressure of the currently mounted tire based on the relationship stored in the storage means and the resonance frequency or the spring constant extracted by the extracting means. Means and judging means for judging the tire pressure based on the limit resonance frequency or the limit spring constant by the calculating means,
Further, when the vehicle is traveling, a traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle, and a resonance frequency of the tire or the tire from the traveling signal. Extraction means for extracting the spring constant of, the limit resonance frequency or limit spring constant corresponding to the limit air pressure as a reference to determine the tire pressure abnormality in a predetermined standard wheel,
And storage means for storing a standard resonance frequency or a standard spring constant in a state where the tire on the standard wheel has a specified air pressure, and a predetermined signal when the standard wheel is replaced with a vehicle having the specified air pressure. Generating signal generating means, and calculating means for calculating a deviation between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means when detecting the signal generated by the signal generating means. A change means for changing the limit resonance frequency or the limit spring constant based on a deviation which is a calculation result of the calculating means, and to judge the tire pressure based on the limit resonance frequency or the limit spring constant. You may make it employ | adopt the tire pressure detection apparatus characterized by the above.

Further, when the vehicle is traveling, a traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle, and a resonance frequency of the tire or a spring constant of the tire are extracted from the traveling signal. Extraction means, tire air pressure predicting means for predicting tire air pressure based on the resonance frequency or spring constant extracted by the extracting means, and tire resonance frequency or spring constant in a state in which the prescribed air pressure is supplied to a predetermined standard tire. Is stored as a standard resonance frequency or a standard spring constant, further storing means for storing a limit resonance frequency or a limit spring constant corresponding to the limit tire air pressure as a reference for judging abnormality of the air pressure in the standard tire, and the extracting means. Stored by the storage means and the extracted resonance frequency or spring constant. First judging means for judging an abnormality in tire air pressure in the standard tire based on a field resonance frequency or a limit spring constant; and a predetermined signal generated when the standard tire is replaced with a tire having the specified air pressure. Calculation for calculating the relationship between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means when the predetermined signal generated by the signal generating means is detected. Means, changing means for changing the limiting resonance frequency or limiting spring constant based on the calculation result by the calculating means, and the resonance extracted by the extracting means after the calculating means detects the predetermined signal. The tire based on the frequency or the spring constant and the limit resonance frequency or the limit spring constant changed by the changing means. May be adopted a tire air pressure detecting device characterized by comprising a second determination means for determining an abnormality in tire air pressure kick, the.

The calculating means calculates the deviation between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means, and the changing means calculates the limit resonance corresponding to the standard tire. A tire air pressure detecting device may be adopted which is characterized by calculating the limit resonance frequency or the limit spring constant after tire replacement by adding the deviation to the frequency or the limit spring constant.

The first judging means or the second judging means
The tire air pressure detection device described above may be provided with an abnormality warning device for notifying an occupant when it is determined that the tire air pressure is abnormal by the determination device. Further, the resonance frequency or the spring constant extracted by the extracting means after the calculation means detects the predetermined signal generated by the signal generating means exists within a predetermined resonance frequency range or a predetermined spring constant. And a prohibiting means for prohibiting the changing of the limit resonance frequency or the limit spring constant by the changing means when the conformity judging means makes a negative decision. A characteristic tire air pressure detection device may be adopted.

Further, the conformity judging means for judging whether or not the value of the deviation as the calculation result of the calculating means is within a predetermined range value, and the modification if the conformity judging means makes a negative judgment. It is also possible to employ a tire air pressure detection device characterized by comprising prohibiting means for prohibiting the change of the limit resonance frequency or the limit spring constant by the means.

Further, the resonance frequency or the spring constant extracted by the extracting means after the calculating means detects a predetermined signal generated by the signal generating means,
If a negative judgment is made by the matching judgment means for judging whether or not it exists within a predetermined resonance frequency range or within a predetermined spring constant, and if a negative judgment is made by the matching judgment means, the tire pressure is predicted by the air pressure predicting means. You may make it employ | adopt the tire pressure detection apparatus characterized by including the prohibition means to prohibit.

Further, the conformity judging means for judging whether or not the deviation value which is the calculation result of the calculating means is within a predetermined range value, and the air pressure when the judgment is negative. A tire air pressure detecting device may be employed, which comprises a prohibiting means for prohibiting the prediction of the tire pressure by the predicting means. Also,
The resonance frequency or the spring constant extracted by the extracting means after the calculating means detects the predetermined signal generated by the signal generating means is within a predetermined resonance frequency range or a predetermined spring constant. Tire pressure detection, comprising: a conformity determining means for determining whether or not there is any, and a prohibiting means for prohibiting notification to the occupant by the abnormality warning means when a negative determination is made by the conformity determining means. A device may be adopted.

Further, the conformity judging means for judging whether or not the deviation value which is the calculation result of the calculating means is within a predetermined range value, and when the conformity judging means makes a negative judgment, the abnormality A tire air pressure detecting device may be adopted, which is provided with a prohibiting unit that prohibits the occupant from being notified by the alarm unit. Further, a tire air pressure detection device characterized by further comprising switch means for issuing the above predetermined signal may be adopted.

Further, when the vehicle is traveling, a traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle, and a resonance frequency of the tire or a spring constant of the tire are extracted from the traveling signal. Extraction means, tire air pressure predicting means for predicting tire air pressure based on the resonance frequency or spring constant extracted by the extracting means, and tire resonance frequency or spring constant in a state in which the prescribed air pressure is supplied to a predetermined standard tire. Is stored as a standard resonance frequency or a standard spring constant, further storing means for storing a limit resonance frequency or a limit spring constant corresponding to the limit tire air pressure as a reference for judging abnormality of the air pressure in the standard tire, and the extracting means. Stored by the storage means and the extracted resonance frequency or spring constant. First judging means for judging an abnormality in tire air pressure in the standard tire based on a field resonance frequency or a limit spring constant; and a predetermined signal generated when the standard tire is replaced with a tire having the specified air pressure. Based on the standard resonance frequency or the standard spring constant and the limit resonance frequency or the limit spring constant stored in the storage unit when the predetermined signal generated by the signal generation unit and the signal generation unit is detected. , Calculating means for calculating the relationship between the change of the resonance frequency or the spring constant extracted by the extracting means in the standard tire and the air pressure of the standard tire as an inclination, and the inclination by the calculating means and the extracting means after the tire replacement Based on the resonant frequency or spring constant, the limiting resonance for the limiting tire pressure after replacement. Calculating means for calculating a wave number or a limiting spring constant; and, after the calculating means detects the predetermined signal, the resonance frequency or spring constant extracted by the extracting means and the limiting resonance frequency calculated by the calculating means. It is also possible to employ a tire air pressure detection device characterized by comprising a second judgment means for judging an abnormality in tire air pressure in the tire based on the limit spring constant.

Further, when the vehicle is traveling, a traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle, and an extracting means for extracting a tire resonance frequency or a tire spring constant from the traveling signal. And a tire air pressure predicting unit that predicts a tire air pressure based on the resonance frequency or the tire spring constant extracted by the extracting unit, in the tire air pressure detecting device, the resonance frequency or the spring constant extracted by the extracting unit. Of the vehicle pressure and the tire pressure is stored in advance as a substantially linear inclination for each type of vehicle, and a signal is generated to generate a predetermined signal when the tire having a specified tire pressure is replaced. Means and, when the predetermined signal from the signal generating means is detected, stored by the storage means. That on the basis of the resonance frequency or the spring constant extracted by the slope and the extraction means,
The present invention further comprises a calculating means for calculating a limiting resonance frequency or a limiting spring constant for the limiting air pressure of the currently mounted tire, and a determining means for determining the tire pressure based on the limiting resonance frequency or the limiting spring constant by the calculating means. The tire air pressure detection mounting may be adopted.

Further, the judging means includes a comparing means for comparing the resonance frequency or the spring constant extracted by the extracting means with the limiting resonance frequency or the limiting spring constant calculated by the calculating means. A tire pressure detecting device is provided, which is provided with an abnormality warning means for notifying an occupant of a tire pressure insufficient state when the resonance frequency or the spring constant is equal to or lower than the limit resonance frequency or the spring constant in the comparison result. You may do it.

Further, when the vehicle is traveling, a traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle, and an extracting means for extracting a tire resonance frequency or a tire spring constant from the traveling signal. A tire air pressure predicting means for predicting a tire air pressure based on a resonance frequency or a tire spring constant extracted by the extracting means, and a tire resonance frequency or a spring constant in a state in which a predetermined standard tire is supplied with a predetermined air pressure. Is stored as a standard resonance frequency or a standard spring constant, and a storage means for storing the relationship between the change in the resonance frequency or spring constant of the standard tire and the air pressure of the standard tire as a substantially linear inclination, and the storage means. The resonance frequency or spring constant corresponding to the limit air pressure of the standard tire is calculated based on the obtained inclination. Abnormal tire pressure in the standard tire based on the first limit air pressure calculating means, the resonance frequency or spring constant extracted by the extracting means, and the limit resonance frequency or limit spring constant calculated by the limit air pressure calculating means. First determining means for determining, and signal generating means for generating a predetermined signal when the standard tire is replaced with a tire having the specified air pressure,
Deviation calculating means for calculating a deviation between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means when the predetermined signal generated by the signal generating means is detected; Changing means for changing the limit resonance frequency or limit spring constant based on the inclination stored in the means, and the resonance frequency extracted by the extracting means after the deviation calculating means detects the predetermined signal. Or a second judging means for judging an abnormality of the tire air pressure in the tire based on the spring constant and the limiting resonance frequency or the limiting spring constant changed by the changing means, and the deviation of the deviation which is the calculation result of the deviation calculating means. If the determination by the conformity determining means for determining whether the value is within a predetermined range value and the conformity determining means, And inhibiting means for inhibiting a change in the limit resonant frequency to limit the spring constant by serial changing means may be adopted tire pressure detecting apparatus characterized by comprising a.

Further, the changing means calculates the limiting resonance frequency or the limiting spring constant after tire replacement by adding the deviation to the limiting resonance frequency or the limiting spring constant corresponding to the standard tire. A tire air pressure detection device may be adopted. Further, when the vehicle is traveling, a traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle, and an extracting means for extracting a resonance frequency of the tire or a spring constant of the tire from the traveling signal. And a limit resonance frequency or a limit spring constant corresponding to a limit air pressure that serves as a reference for determining a predetermined standard tire air pressure abnormality, and a standard extracted from the traveling signal in a state where the standard tire has a specified air pressure. Storage means for storing a resonance frequency or a standard spring constant, signal generating means for generating a predetermined signal when the standard tire is replaced with a tire having the specified air pressure, and a signal generated by the signal generating means is detected. In doing so, the deviation between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means is calculated. A tire air pressure detecting device comprising: a difference calculating means; and a changing means for changing the limit resonance frequency or the limit spring constant based on a deviation which is a calculation result of the deviation calculating means. You may

[0019]

In the structure of claim 1, the tire air pressure is predicted from the resonance frequency or the spring constant. The resonance frequency and the spring constant have a predetermined correlation. Further, the relationship between the tire frequency and the extracted value of the resonance frequency or the spring constant that is the basis of tire pressure prediction is
Changes when tires or wheels are replaced.
In addition, the resonance frequency or spring constant and tire pressure are
There is a substantially linear relationship that is determined for each type of vehicle, and this relationship is stored in advance. Further, even when the tires, wheels, etc. are replaced, the above-mentioned substantially linear relationship is maintained in the relationship between the resonance frequency or the spring constant and the tire pressure if the type of vehicle is the same. Therefore, the limit resonance frequency or the limit spring constant can be calculated based on such a linear relationship stored in advance and the resonance frequency or the spring constant extracted in the tire having the specified air pressure. In addition,
The limit resonance frequency or the limit spring constant corresponds to the lower limit value or the upper limit value of the tire air pressure, and the abnormality of the tire air pressure is judged based on this.

According to the second aspect of the present invention, a standard tire is defined, and the standard resonance frequency or standard spring constant of the standard tire is stored in advance. As described above, the relationship between the resonance frequency or the spring constant and the tire air pressure is approximately linear, and the limit resonance frequency or the limit spring constant after tire replacement is accurately set and changed based on the magnitude of the deviation. be able to.

When the tire has not been replaced with the standard tire as in claim 3, the tire pressure may be determined by using the standard resonance frequency or the standard spring constant stored in advance. In addition, after the tire is inflated with the specified air pressure, by using the substantially linear relationship, the standard resonance frequency or the standard spring constant, and the resonance frequency of the tire after replacement extracted by the extracting unit or The limit resonance frequency or limit spring constant of the tire after replacement can be set easily and accurately based on the relationship with the spring constant. Therefore, if the tire air pressure is judged based on such a limit resonance frequency or a limit spring constant, the tire air pressure can be accurately detected even after the tire is replaced from the standard tire.
At this time, even after the tire replacement, the substantially linear relationship is based on the fact that the magnitude of the resonance frequency with respect to the tire air pressure simply moves up and down in parallel with the standard resonance frequency or the standard spring constant and the tire after replacement. The relationship between the resonance frequency and the spring constant is calculated.

According to a fourth aspect of the present invention, the calculating means calculates the relationship between the standard resonance frequency or the standard spring constant and the resonance frequency or spring constant of the tire after the replacement, after the replacement with the standard resonance frequency or the standard spring constant. It is possible to easily and accurately change the limit resonance frequency or the limit spring constant by calculating the deviation from the tire resonance frequency or the limit spring constant and converting the deviation into the limit resonance frequency or the limit spring constant of the standard tire. .

As described in claim 5, when the tire air pressure is abnormal, the occupant may be informed. Further, when the tire is replaced from the standard tire, the resonance frequency or the spring constant may not be accurately measured, and the tire air pressure may not be accurately detected, depending on how the tire is soaked or the type thereof. However, if the value of the resonance frequency or the spring constant extracted by the extracting means does not fall within the predetermined range as described in claim 6, the change of the limit resonance frequency or the limit spring constant is prohibited. It is possible to avoid the judgment after the decrease in air pressure to some extent.

According to the seventh aspect of the present invention, the magnitude of the deviation value at the time of tire replacement is used as a criterion, and if the magnitude of the deviation does not fall within a predetermined range, the limit resonance frequency or the limit spring constant. Even if the change is prohibited, it is possible to obtain the same operational effect as in the case of adopting the configuration of claim 6. Further, as described in claims 8 to 11, the prediction of the tire air pressure itself or the notification to the occupant of the tire air pressure abnormal state may be prohibited.

According to claims 2 to 11,
When replacing the tire, calculate the deviation between the standard resonance frequency or spring constant of the standard tire and the resonance frequency or spring constant of the currently installed tire having the specified air pressure,
Although the limit resonance frequency or the limit spring constant is changed using this deviation, in claim 13, the standard resonance frequency or the standard spring constant of the standard tire and the limit resonance frequency or the limit spring of the standard tire at the time of tire replacement. Using the constant, the slope in the relationship between the resonance frequency or the spring constant and the tire pressure, which differs depending on the type of the vehicle, is calculated and specified. Then, the resonance frequency or the spring constant extracted after the tire replacement is used to identify which point the straight line passes through in this inclination, and the limit resonance frequency or the spring constant for the limit air pressure is calculated. Therefore, after tire replacement, the tire air pressure is determined based on the updated new limit resonance frequency or limit spring constant, so that accurate determination can be realized.

In the second to thirteenth aspects, the standard resonance frequency standard or the spring constant and the limit resonance frequency or the limit spring constant of the standard tire are stored, and the deviation or the inclination is calculated to calculate the limit resonance frequency or the tire after the tire replacement. The limit spring constant was changed accurately. However,
In the configuration according to any one of claims 14 to 17, the resonance frequency or the spring constant and the substantially linear inclination of the tire pressure are substantially the same if the types of vehicles are the same, and the inclination is stored in advance. Then, using this inclination, the limit resonance frequency or the limit spring constant after tire replacement is changed.

First, according to the fourteenth aspect, the relationship between the resonance frequency or spring constant and the tire air pressure is stored as a substantially linear inclination for each vehicle type, and the tire having the specified air pressure is extracted by the extracting means. Depending on the resonance frequency or spring constant, the straight line in the relationship between the resonance frequency or spring constant of the currently installed tire and the air pressure can be limited, and the limit resonance frequency or the spring constant for the limit air pressure can be set. . By storing the inclination in this way, it is not necessary to limit the standard tires, but simply for each tire in which the prescribed air pressure is injected,
It is possible to accurately set the limit resonance frequency or limit spring constant for the limited air pressure of the tire.

According to the sixteenth aspect of the invention, if the inclination is stored and a standard tire is defined and at least a standard resonance frequency or a standard spring constant of the standard tire is stored, tire pressure detection can be performed depending on the vehicle type. By establishing the following standard, it is possible to accurately determine from the magnitude of the deviation whether or not the resonance frequency or the spring constant extracted after the tire replacement shows an extremely deviated value in this vehicle type.

When a standard tire as a reference for storing the standard resonance frequency or the standard spring constant and the limit resonance frequency and the limit spring constant is detected each time the tire is changed, that is, a predetermined signal is detected. May be updated to. That is, after the tire replacement, the resonance frequency or spring constant extracted when the newly installed tire has the specified air pressure is set as the new standard resonance frequency or standard spring constant, and the limit changed by the changing means. The resonance frequency or the limit spring constant becomes a reference value in the deviation calculating means or the changing means when the predetermined signal is detected next.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A case where a drop in air pressure is detected and displayed will be described below as an example of an abnormal air pressure. FIG. 1 shows the entire configuration of the device, and the tires 1a to 1d on the front, rear, left, and right of the vehicle.
Are provided with pulsers 2a to 2d integrally with the axle, and these pulsers 2a to 2d are gear bodies made of a magnetic material. The pulsars 2a to 2d are provided with pickup coils 3a to 3d at a constant interval from the outer peripheral surface, and the pickup coils 3a to 3d pulsate each time the tooth profile of the pulsars 2a to 2d passes, that is, each tire 1a to An AC output signal having a cycle corresponding to the rotation speed of 1d is emitted. This is shown in FIG.

Output signals from the pickup coils 3a to 3d are input to an electronic control unit (ECU) 4. The ECU 4 includes a waveform forming circuit, a CPU, a ROM, a RAM, and the like, and performs signal processing described below according to a processing program. E
An indicator 5 is connected to the CU 4 to warn the tire pressure drop as a result of signal processing. Further, an update switch 41 is connected to the ECU 4 and is turned on at the time of tire replacement or the like to update the critical frequency for lowering the air pressure as described later.

FIG. 2 shows the signal processing means of the ECU 4.
Although the same processing is actually performed for each tire 1a to 1d, the processing for one tire will be described below. In step 101, it is confirmed whether or not the updating switch 41 described above has been turned on. Normally, since the switch 41 is not turned on, the process proceeds to step 201 and subsequent steps in FIG. Further, when the vehicle is embarked after factory shipment, the updating switch 41 indicating tire replacement is turned on. If this is done, steps 102 and 103 will be performed when embarking.
The ECU4 in step 110 etc.
The specified frequency f0A or the limit frequency fLA for the standard tire is read out, and in steps 111 to 113, the tire air pressure is determined by fOA = fOB, Δf1 = 0, fLB = fLA.

Further, the frequency calculated at the beginning of embarkation at the time of factory shipment may be stored as the prescribed frequency fOA of the standard tire. When replacing the tire, the tire is supplied with an air pressure of a specified pressure (for example, 2 Kg / cm ² ) in advance. In step 102, flag F
Is set, and if not set, the wheel speed V is calculated in step 103. This forms the output signals of the above-described pickup coils 3a to 3d into a pulse signal to form a pulse signal.
The wheel speed V is obtained by dividing the tooth profile spacing of the above by the time between pulses. A high frequency component including the vibration frequency of the tire is superposed on the wheel speed V, and the high frequency component is extracted by filtering. This is shown in FIG.

Subsequently, at step 104, the road surface condition is judged. This is to confirm that the magnitude ΔV (Fig. 5) of the high frequency component of the wheel speed V is between the reference values VL and VH. If the above ΔV is too large or too small, the resonance frequency is calculated accurately. Because you can't. Continued Step 1
In 05, it is confirmed whether the time ΔT (FIG. 5) in which the ΔV is within the proper range exceeds the predetermined time to, and in the subsequent step 106, the frequency analysis of the high frequency component (for example, the fast Fourier transform FFT or the linear prediction method is performed). )I do.

The FFT operation will be described below as an example. This is shown in FIG. 6 and shows random frequency characteristics as shown by the influence of minute irregularities on the road surface that appear irregularly. Therefore, in order to reduce the fluctuation of the FFT calculation result, the FFT calculation is performed no times (steps 107 and 108), and this is averaged. (Step 109). This process is shown in FIG.

In FIG. 7, when the wheel speed V obtained during this period is No times, FFT calculation is performed no times (upper and middle stages in the figure), and the obtained FFT calculation results are averaged (in the figure). (Lower limit), the gains of the respective frequency components are averaged, random noise fluctuations are offset, and a resonance peak appears in the clear. The FFT calculation result averaged in step 109 has resonance peaks at two positions on the frequency axis as shown in FIG. 8, and when the tire air pressure decreases and the spring constant of the tire rubber portion decreases, the broken line in the figure indicates As shown,
The resonance frequency also shifts to the low frequency side. Therefore, the resonance frequency and the tire air pressure uniquely correspond to each other.

After the averaging process in step 109,
In step 110, the resonance frequency fOB is calculated. This resonance frequency fOB is due to the replacement tire B supplied with the specified pressure, as shown in FIG. The replacement tire B in the figure is a flatter and more rigid tire than the standard tire, and its resonance frequency fOB is higher than that of the standard tire fOA.

According to a study made by the inventors, the sizes of tires and wheels mounted on the same type of vehicle have an allowable range if the vehicle type is the same. Even if is replaced, the tire air pressure and the resonance frequency move up and down in parallel while maintaining the linear relationship of the inclination α. The replacement tire C in the figure shows, for example, an aluminum wheel replaced with an iron wheel, and in this case, the resonance frequency thereof is lower than that of the standard tire as compared with the standard tire.

However, the fact that the slope representing the relationship between the resonance frequency and the tire air pressure is constant depending on the type of vehicle is used, and in step 111 of FIG. 2, under the specified pressure supplied to the tire in advance at the time of factory shipment or the like. The difference Δf1 between the resonance frequencies (hereinafter referred to as the prescribed frequencies) fOA and fOB is calculated, and in the subsequent step 112, a new limit frequency fLB is obtained from the following equation, and the limit threshold fLA for the standard tire is updated (step 113). .

FLB = fLA + Δf1 The above-mentioned limit frequencies fLA and fLB correspond to the limit pressure at which a tire pressure drop warning should be issued, and this is a constant value depending on the vehicle type. In addition, the limit frequency fLA for the standard tire and the resonance frequency fOA when the standard tire is inflated with the prescribed air pressure are determined by the EC even after the standard tire is replaced.
It should be stored in U4 or the like. In this case, when a new limit frequency fLC is obtained when the tire is changed from the second time onward, the deviation Δf2 from the frequency fOA is calculated using the limit frequency fLA of the standard tire, and is calculated from the following formula. You may

FLC = fLA + Δf2 ... When updating the limit frequency from the above formula, the standard tire is fixed, and the specified frequency and the limit frequency of this standard tire are also changed after the second tire replacement. It serves as a reference when calculating the limit frequency of the tire after replacement. In this way, if the specified frequency and limit frequency of the standard tire are stored and the limit frequency, which is the criterion for determining the air pressure of a new tire, is updated using this value, the update criterion does not change and tires are replaced many times. Even in, the accurate air pressure detection can be continued.

If the specified frequency FOA and the limit frequency fLA of the standard tire are not stored after the first tire change, a new limit frequency fLC should be calculated as follows at the second and subsequent tire changes. To That is, assuming that the frequency in the state where the prescribed pressure is injected into the new tire is fOC, the deviation Δf3 between the frequency fOC and the frequency fOB of the currently mounted tire is calculated, and the limit frequency fLC1 is calculated by the following formula. .

FLC1 = fLB + Δf3 In other words, when the limit frequency is updated from the above formula, the base frequency and the limit frequency are not fixed by the standard tire in the following flow, and the tire after tire replacement is The limit frequency and frequency are changed. Even in this case, the same effect can be obtained.

Once the above processing is performed, step 1
In step 13, the limit frequency fLA of the standard tire is updated to the limit frequency fLB of the tire after replacement, and the flag F is set in step 114. Therefore, in the flow from the next time, until the next tire replacement is executed, that is, the flag Until the update is performed, the tire pressure is predicted by the limit frequency fLB of the currently installed tire.
Further, even if the updating switch 41 is kept turned on after the ignition switch is turned on, the flag F is set in step 114 and the flag setting status, that is, the flag counter value is confirmed in step 102. Step 201 and subsequent steps are performed.
Therefore, the processes from step 103 onward are executed only once after the ignition switch is turned on.

The processing of steps 201 to 208 is the same as the processing of steps 103 to 110 in FIG.
Then, the resonance frequency fk during traveling obtained in step 208
Is compared with the updated limit frequency fLB, and if the former is smaller than the latter, an air pressure drop alarm is issued in step 210.
If the update switch is not turned on at the time of embarkation from factory shipment, in step 209,
Limit frequency fLA and resonance frequency f set from the beginning
Compare with k. Further, in this step 209, every time tire replacement is performed, the updating switch 41 is turned on, and one flow is completed, the limit frequency is fLA → fLB → fLC ...
Is updated sequentially.

In this embodiment, it is possible to always display the tire pressure. For this purpose, the relationship between the tire pressure and the resonance frequency of the standard tire is stored in the map in advance, and the map is corrected by the difference Δf1 obtained for the replacement tire. Thereby, the tire air pressure of the replacement tire can be accurately predicted, and this predicted value is displayed on the display unit 5.

[0047]

[Embodiment 2] In the first embodiment, the alarm for lowering air pressure is issued by the limit frequency. However, the alarm for lowering air pressure may be issued when the difference from the specified frequency exceeds a predetermined amount. Procedures shown in FIGS. 10 and 11 Steps 301 to 310 in FIG. 10 are the same as Steps 101 to 110 in FIG. 2 in the first embodiment, and in this embodiment, they correspond to steps 111 to 113 in the first embodiment. The step to perform can be omitted. Steps 401 in FIG. 11
˜408 are steps 201 and 2 of FIG. 3 in the first embodiment.
It is the same as 08.

In step 409 of FIG. 11, the resonance frequency fk calculated in step 409 is the resonance frequency (specified frequency) f calculated in step 310 of FIG.
It is confirmed with respect to OB whether or not it is within a predetermined range Δf2, and if it exceeds the predetermined range, a warning is issued as to a decrease in tire pressure (step 410). If the first tire replacement is not executed and the standard tire is covered, it is confirmed whether the standard tire is within the predetermined range Δf2 with respect to the specified number of weeks fOA. Further, in this step 409, every time the tire is replaced, the updating switch 41 is turned on, and one flow is completed, the limit frequencies to be compared with Δf2 are sequentially set as fLA → fLB → fLC. Will be updated.

This embodiment has the same effect as that of the first embodiment, and it is not necessary to calculate the limit frequency fLB. In addition, the present embodiment can give an alarm even when the tire pressure is excessively increased.

[0050]

Third Embodiment Although the resonance frequency is extracted in each of the above embodiments, the spring constant of the tire may be calculated. The processing procedure in this case is shown in FIGS. 12 and 13, and is basically the same as the processing procedure shown in FIGS. 2 and 3 in the first embodiment. Less than,
The difference will be described. In step 506 of FIG. 12, from the high frequency component of the wheel speed V, for example, Japanese Patent Laid-Open No. 5-119
The spring constant K is calculated by the method described in Japanese Patent No. 607. This spring constant K is calculated no times (step 50
7, 508) and averaging is performed in step 509 to obtain the final specified spring constant (OB of the tire at the specified air pressure) KOB of the replacement tire. In step 510, the difference ΔK from the standard spring constant KOA of the standard tire is calculated, and then the limit spring constant (the tire spring constant at the limit air pressure) KLB of the replacement tire is calculated by the following formula (step 5)
11). Then, in step 512, the limit spring constant KLA of the standard tire is updated with the limit spring constant KLB.

KLB = KLA + ΔK ... Spring constant K in steps 604, 605 and 606 of FIG.
Is calculated no times, and the averaging process is performed in step 607 to obtain the current spring constant K of the replacement tire. Then, in step 608, the panel constant K is set to the limit spring constant K.
Compared with LB, if the former is smaller than the latter, an air pressure drop alarm is issued in step 609.

This embodiment also has the same effects as those of the above embodiments.

[0053]

Fourth Embodiment In the processing shown in FIG. 2 of the first embodiment, step 1
An abnormality determination step 701 shown in FIG. 14 is inserted between 10 and step 111. By providing step 701, the resonance frequency f calculated in step 110 is calculated.
If OB is not within the normal range of fOL to fOH (Fig. 15),
The limit frequency is not updated in step 111, and the process proceeds from step 701 to step 702 to perform abnormality processing. The abnormality processing includes cancellation of the resonance frequency fOB, prohibition of changing the reference value, re-learning, warning display, and the like.

The abnormality determining step 801 may be inserted between the steps 500 and 510 shown in FIG. 12 of the third embodiment to eliminate the spring constant KOB which is not in the normal range. Further, in step 801 described above, the range of the value of the resonance frequency is set. However, for example, the range of the difference Δf calculated in step 111 of FIG. If it deviates from the range, abnormality processing may be executed.

Further, although the above-mentioned abnormality processing is prohibition of updating of the limit frequency, that is, prohibition of change of the reference value, etc., it is not limited to this, for example, step 209 in FIG.
In, the execution of the comparison between the resonance frequency and the limit frequency may be prohibited, and the tire pressure prediction may be prohibited. In addition, the warning display in step 210 of FIG. 3 is prohibited,
It is also possible to prohibit the passengers from being notified of tire pressure abnormalities. Even in this case, the passenger can be accurately notified of the decrease in air pressure.

[0056]

Fifth Embodiment In the above-described embodiments, the limit frequency after tire replacement is updated based on the frequency of the tire having the specified pressure (specified frequency) and the limit frequency corresponding to the limit air pressure of the tire. . However, in the fifth embodiment, the inclination in the substantially linear relationship between the resonance frequency and the tire air pressure, which is determined for each vehicle type, is stored in advance. Then, after the tire replacement, the setting of the limit frequency of a new tire is updated using this inclination. In the fifth embodiment, the standard tire is not limited, the limit frequency is obtained for each tire mounted by tire replacement, and the tire air pressure is detected according to the limit frequency. On this occasion,
Immediately after tire replacement, it is assumed that the tire is inflated with the specified air pressure.

The fifth embodiment will be described with reference to FIG. When the ignition switch is turned on, the process is started from step 801, but the process up to step 808 is substantially the same as the flow in the above-described embodiment, and therefore the description thereof will be omitted. In step 809, the update switch 41
It is determined whether or not is input, and if it is input, the process proceeds to step 810. Further, since the updating switch 41 is not normally turned on, the process proceeds to step 812. It should be noted that the switch 41 for updating is set to be turned on in advance when the vehicle is embarked after the shipment from the factory.
Proceed to.

First, the process when the tires are replaced or when the vehicle is embarked after the factory shipment will be described. In this case, the update switch 41 is in the closed state,
In step 810, the flag is confirmed. This flag is not set at the time of embarkation after shipment from the factory,
Further, when the ignition is once turned off for tire replacement, the flag is released, and the process proceeds to step 811. In step 811, the limit frequency fLK is calculated and stored using the slope of the relationship between the frequency and the tire air pressure stored in advance in the ECU 4 or the like for each vehicle type and the resonance frequency fK calculated in step 808. Limit frequency F
When calculating LK, since the specified frequency value when the specified air pressure value is provided, the limit air pressure value and the value of the slope representing the relationship between each of these frequencies and the tire air pressure, the limit frequency fKL with respect to the limit air pressure value Can calculate exactly one value.
The resonance frequency fk calculated at the time of factory shipment or the resonance frequency fk calculated at the time of tire replacement is used as the specified frequency.

In step 812, the flag F is set. Then, the process proceeds to step 813, the limit frequency fLK is compared with the resonance frequency fk, and a warning is output in step 814 according to the result. When tires are replaced or when the vehicle is launched after shipment from the factory,
After passing through the steps 811 and 812 described above, the update switch 41, which has not been subjected to tire replacement or the like, is not turned on or after the ignition is turned on.
In the case of the closed state, if the steps 811 and 812 are once passed, the processing skipping the steps 811 and 812 is executed. That is, when the update switch 41 is not turned on, a negative determination is made in step 809, and therefore the process proceeds from step 809 to step 813. Further, when the update switch 41 is in the closed state but once passes through the steps 811, 812, since the flag F is set in the step 812 in the previous flow, an affirmative decision is made in the step 810, and the step 813 is carried out. move on. The updating switch 41 is reset to the non-closed state when the ignition is turned off.

As described above, in the fifth embodiment, the standard tire is not set, and the inclination representing the relationship between the resonance frequency and the tire pressure is simply stored for each vehicle type. Can be detected. In addition,
Also in this fifth embodiment, the abnormality determination step 701 described in the fourth embodiment is performed in steps 811 and 81.
It can be inserted between 2 and the like. That is, when the flow proceeds to the process of step 811, the update switch 41 is used when the vehicle is started and when the tires are replaced.
It is assumed that the tires installed at this time are inflated with the specified air pressure. However, when the resonance frequency fk does not exist within the predetermined range, it is determined that the resonance frequency is not normally detected, and in abnormal processing, processing such as prohibiting detection of tire air pressure is performed. By doing so, it is possible to avoid erroneous notification of tire pressure abnormality.

[0061]

[Sixth Embodiment] In the fifth embodiment, the limit frequency is calculated by using the inclination, but the standard tire is limited and the specified frequency and the limit frequency in the standard tire are not stored and are not used for the control. It was In the sixth embodiment, the limit frequency is calculated using the inclination, and the specified frequency of the standard tire is stored and used for control.

The control will be briefly described below. In the same manner as in steps 101 to 111 of FIG. 2 in the first embodiment, in step 112, as in step 811 of the fourth embodiment in FIG. The limit frequency of the current tire is calculated using the specified frequency. Then, in step 113, the limit frequency is updated. When the update switch 41 is not turned on and when the update switch is kept turned on after the limit frequency is updated, the steps from step 201 are executed as in the first embodiment. The limit frequency for standard tires is EC
It may be specified in advance in U4 or the like, or may be calculated from the stored inclination and specified air pressure.

In this embodiment, step 11 in FIG.
An abnormality determination step 901 (see FIG. 17) having the same operation as that of the fourth embodiment is inserted between 1 and step 113. For example, when inserted after step 111. In step 901, it is determined whether or not a deviation Δf1 between the value of the standard frequency of the standard tire and the value of the standard frequency of the tire mounted this time is within the range of Δf1 to Δfh. That is, for example, if the deviation Δf1 is too large, it is determined that the resonance frequency of the currently mounted tire is not correctly detected for some reason, and the process proceeds to step 902 to execute the abnormality processing. This abnormality processing may be performed by the same thing as described above in the fourth embodiment.

By thus defining the specified frequency of the standard tire, the abnormality judgment after the tire replacement can be executed on the basis of the specified frequency of the standard tire, and the accurate abnormality judgment can be executed.

[0065]

As described above, according to the tire air pressure detecting device of the present invention, even when the tire or wheel is replaced, the tire air pressure is always accurately predicted based on the resonance frequency or the spring constant, and if necessary. A warning of low air pressure can be issued.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall configuration of a tire air pressure detection device according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of an electronic control unit.

FIG. 3 is a flowchart showing a processing procedure of an electronic control unit.

FIG. 4 is a waveform diagram of an output signal of a pickup coil.

FIG. 5 is a waveform diagram of a high frequency component of wheel speed.

FIG. 6 is a frequency analysis diagram of high-frequency components of wheel speed.

FIG. 7 is a diagram illustrating a process of averaging frequency analysis results.

FIG. 8 is a frequency analysis diagram of high-frequency components of wheel speed after moving average processing.

FIG. 9 is a diagram showing a relationship between a resonance frequency and a tire pressure.

FIG. 10 is a flowchart showing a processing procedure of the electronic control unit according to the second embodiment of the present invention.

FIG. 11 is a flowchart showing a processing procedure of the electronic control unit.

FIG. 12 is a flowchart showing a processing procedure of an electronic control unit according to a third embodiment of the present invention.

FIG. 13 is a flowchart showing a processing procedure of the electronic control unit.

FIG. 14 is a main part flowchart showing a processing procedure of an electronic control device according to a fourth embodiment of the present invention.

FIG. 15 is a diagram showing the relationship between resonance frequency and tire pressure.

FIG. 16 is a flowchart showing a processing procedure of an electronic control unit according to a fifth embodiment of the present invention.

FIG. 17 is a main part flowchart showing a processing procedure of the electronic control unit according to the sixth embodiment of the present invention.

FIG. 18 is a diagram corresponding to a complaint.

[Explanation of symbols]

1a, 1b, 1c, 1d Tires 2a, 2b, 2c, 2d Pulsers 3a, 3b, 3c, 3d Pickup coil (travel signal output means) 4 Electronic control device (extraction means, tire air pressure prediction means,
Prediction reference value changing means) 41 Update switch (switch means) 5 Display

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuyoshi Ono, 1-1, Showa-cho, Kariya, Aichi Prefecture, Nihon Denso Co., Ltd. (72) Inventor, Ikuo Hayashi, 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Stock Company Japan Auto Parts Research Institute (72) Inventor Yoshihiro Nishikawa 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Stock Company Japan Auto Parts Research Institute

Claims (18)

[Claims] 1. A traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle when the vehicle is traveling, and an extracting means for extracting a tire resonance frequency or a tire spring constant from the traveling signal. And a tire air pressure predicting unit that predicts a tire air pressure based on a resonance frequency or a tire spring constant extracted by the extracting unit, wherein the tire is replaced with a tire having a specified air pressure. At this time, a signal generating means for generating a predetermined signal, and a storage means for pre-storing a substantially linear relationship between a change in resonance frequency or spring constant and a change in tire air pressure extracted by the extracting means for each vehicle type And when the predetermined signal from the signal generating means is detected, the relationship and the extraction stored in the storage means are detected. Calculating means for calculating a limiting resonance frequency or a limiting spring constant with respect to the limiting air pressure of the currently mounted tire based on the resonance frequency or the spring constant extracted by the outputting means; and the limiting resonance frequency or the limiting spring by the calculating means. A tire air pressure detection device comprising: a determination unit that determines a tire air pressure based on a constant. 2. A traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle when the vehicle is traveling, and a resonance frequency of the tire or a spring constant of the tire is extracted from the traveling signal. And a limiting resonance frequency or a limiting spring constant corresponding to a limit air pressure that serves as a reference for determining a tire pressure abnormality in a predetermined standard wheel, and a standard in a state where the tire on the standard wheel has a specified air pressure. Storage means for storing a resonance frequency or a standard spring constant; signal generating means for generating a predetermined signal when the standard vehicle is replaced with a vehicle having the specified air pressure; and a signal generated by the signal generating means. Then, the deviation between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means is calculated. And a changing means for changing the limiting resonance frequency or the limiting spring constant on the basis of a deviation which is a calculation result by the calculating means, the tire pressure based on the limiting resonance frequency or the limiting spring constant. A tire air pressure detection device, characterized in that 3. A traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle when the vehicle is traveling, and a resonance frequency of the tire or a spring constant of the tire is extracted from the traveling signal. Extraction means, tire air pressure predicting means for predicting tire air pressure based on the resonance frequency or spring constant extracted by the extracting means, and tire resonance frequency or spring constant in a state in which the prescribed air pressure is supplied to a predetermined standard tire Is stored as a standard resonance frequency or a standard spring constant, further storing means for storing a limit resonance frequency or a limit spring constant corresponding to the limit tire pressure as a reference for judging an abnormality of the air pressure in the standard tire, and by the extracting means. The extracted resonance frequency or spring constant and the limit stored by the storage means. First determining means for determining an abnormality in tire air pressure in the standard tire based on a resonance frequency or a limiting spring constant; and a predetermined signal when the standard tire is replaced with a tire having the predetermined air pressure. A signal generating means, and a calculating means for calculating a relationship between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means when detecting the predetermined signal generated by the signal generating means. Changing means for changing the limiting resonance frequency or the limiting spring constant based on the calculation result by the calculating means, and the resonance frequency extracted by the extracting means after the calculating means detects the predetermined signal. Or to the tire based on the spring constant and the limit resonance frequency or limit spring constant changed by the changing means. By comprising a second determination means for determining an abnormality in tire air pressure kicking a tire air pressure detecting device according to claim. 4. The calculating means calculates a deviation between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means, and the changing means calculates a limit resonance corresponding to the standard tire. The tire air pressure detection device according to claim 3, wherein the limit resonance frequency or the limit spring constant after tire replacement is calculated by adding the deviation to the frequency or the limit spring constant. 5. An abnormality warning means for notifying an occupant when tire pressure is determined to be abnormal by the first judgment means or the second judgment means. Tire pressure detection device. 6. The resonance frequency or spring constant extracted by the extracting means after the calculating means detects a predetermined signal generated by the signal generating means is within a predetermined resonance frequency range or a predetermined spring constant. And a prohibition means for prohibiting the change of the limit resonance frequency or the limit spring constant by the changing means when the conformity judging means makes a negative decision. The tire air pressure detection device according to claim 2 or 4, characterized in that. 7. A conformity determining means for determining whether or not a deviation value, which is a calculation result of the calculating means, is within a predetermined range value; and a change if the conformity determining means makes a negative determination. And a prohibition means for prohibiting a change of the limit resonance frequency or the limit spring constant by the means.
The tire pressure detection device according to. 8. The resonance frequency or spring constant extracted by the extracting means after the calculating means detects a predetermined signal generated by the signal generating means is within a predetermined resonance frequency range or a predetermined spring constant. A suitability determining means for determining whether or not the vehicle is present in the vehicle, and a prohibiting means for inhibiting the tire pressure prediction by the air pressure predicting means when the suitability determining means makes a negative determination. The tire air pressure detection device according to claim 2 or 4. 9. A conformity determining means for determining whether or not a deviation value, which is a calculation result of the calculating means, is within a predetermined range value; and a pneumatic pressure when the conformity determining means makes a negative determination. A means for prohibiting prediction of tire air pressure by the predicting means, and means for preventing tire pressure prediction.
The tire pressure detection device according to. 10. The resonance frequency or spring constant extracted by the extracting means after the calculating means detects a predetermined signal generated by the signal generating means is within a predetermined resonance frequency range or a predetermined spring constant. A conformity determining means for determining whether or not it exists in the inside, a prohibiting means for prohibiting the occupant from being notified by the abnormality warning means when a negative determination is made by the conformity determining means, and the conformity determining means. The tire pressure detection device according to claim 5, further comprising: a prohibiting unit that prohibits the occupant from being notified by the abnormality warning unit when a negative determination is made. 11. A conformity determining means for determining whether or not a deviation value, which is a calculation result of the calculating means, is within a predetermined range value, and the information if the conformity determining means makes a negative determination. The tire air pressure detection device according to claim 5, further comprising: a prohibiting unit that prohibits the occupant from being notified by the reporting unit. 12. The tire air pressure detection device according to claim 3, further comprising switch means for outputting the predetermined signal. 13. A traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle when the vehicle is traveling, and an extraction for extracting the tire resonance frequency or the spring constant of the tire from the traveling signal. Means, a tire air pressure predicting means for predicting a tire air pressure based on a resonance frequency or a spring constant extracted by the extracting means, and a tire resonance frequency or a spring constant in a state in which a prescribed air pressure is supplied to a predetermined standard tire. Stored as a standard resonance frequency or a standard spring constant, and further storing means for storing a limit resonance frequency or a limit spring constant corresponding to a limit tire pressure as a reference for judging abnormality of the air pressure in the standard tire, and extracted by the extracting means. The stored resonance frequency or spring constant and the limit stored by the storage means. First determining means for determining an abnormality in tire air pressure in the standard tire based on a resonance frequency or a limiting spring constant; and a predetermined signal when the standard tire is replaced with a tire having the predetermined air pressure. When the signal generating means and the predetermined signal generated by the signal generating means are detected, based on the standard resonance frequency or standard spring constant and the limit resonance frequency or limit spring constant stored in the storage means, In the standard tire, a calculating unit that calculates the relationship between the change in the resonance frequency or the spring constant extracted by the extracting unit and the air pressure of the standard tire as a slope, and the slope by the calculating unit and the tire after the tire replacement is extracted by the extracting unit. Based on the resonance frequency or the spring constant, the limit resonance circumference for the limit air pressure of the tire after replacement is Calculating means for calculating a wave number or a limiting spring constant; and, after the calculating means detects the predetermined signal, the resonance frequency or spring constant extracted by the extracting means and the limiting resonance frequency calculated by the calculating means. A second determination means for determining an abnormality in tire air pressure of the tire based on a limit spring constant, and a tire air pressure detection device. 14. A traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle when the vehicle is traveling, and an extracting means for extracting a tire resonance frequency or a tire spring constant from the traveling signal. And a tire air pressure predicting unit that predicts a tire air pressure based on a resonance frequency or a tire spring constant extracted by the extracting unit, wherein a resonance frequency or a spring constant extracted by the extracting unit is provided. Of the vehicle pressure and the tire air pressure as a substantially linear inclination for storing in advance for each type of the vehicle, a signal generating means for generating a predetermined signal when the tire is replaced with a tire having a specified air pressure. And when the predetermined signal from the signal generating means is detected, it is stored by the storage means. Calculating means for calculating the limit resonance frequency or the limit spring constant for the limit air pressure of the currently mounted tire based on the inclination and the resonance frequency or the spring constant extracted by the extracting means, and the limit resonance by the calculating means. A tire air pressure detection device comprising: a determination unit that determines a tire air pressure based on a frequency or a limit spring constant. 15. The judging means comprises a comparing means for comparing the resonance frequency or the spring constant extracted by the extracting means with the limiting resonance frequency or the limiting spring constant calculated by the calculating means. 15. The tire according to claim 14, further comprising: abnormality warning means for notifying an occupant of a tire pressure insufficient state when the resonance frequency or the spring constant is equal to or lower than the limit resonance frequency or the spring constant as a result of comparison. Air pressure detection device. 16. A traveling signal output means for outputting a traveling signal including a vibration frequency component of a tire installed in the vehicle when the vehicle is traveling, and an extracting means for extracting a resonance frequency of the tire or a spring constant of the tire from the traveling signal. A tire air pressure predicting means for predicting a tire air pressure based on a resonance frequency or a tire spring constant extracted by the extracting means; and a tire resonance frequency or a spring constant in a state in which a prescribed air pressure is supplied to a predetermined standard tire. Is stored as a standard resonance frequency or a standard spring constant, and further, storage means for storing the relationship between the change in the resonance frequency or spring constant of the standard tire and the air pressure of the standard tire as a substantially linear inclination, and the storage means. The resonance frequency or spring constant corresponding to the limit air pressure of the standard tire is calculated based on the obtained inclination. Abnormal tire pressure in the standard tire based on the first limit air pressure calculation means, the resonance frequency or spring constant extracted by the extraction means, and the limit resonance frequency or limit spring constant calculated by the limit air pressure calculation means. First determining means for determining whether the standard tire is a signal generating means for generating a predetermined signal when the standard tire is replaced with a tire having the specified air pressure, and detecting the predetermined signal for generating the signal. In doing so, deviation calculating means for calculating a deviation between the standard frequency or the standard spring constant and the resonance frequency or the spring constant extracted by the extracting means, and the limit based on the inclination stored in the storage means. Changing means for changing the resonance frequency or the limit spring constant, and after the deviation calculating means detects the predetermined signal,
Second judging means for judging an abnormality in tire air pressure in the tire based on the resonance frequency or spring constant extracted by the extracting means and the limit resonance frequency or limit spring constant changed by the changing means; Conformity determining means for determining whether or not the value of the deviation, which is the calculation result of the calculating means, is within a predetermined range value; and, if the conformity determining means makes a negative judgment, the limit resonance frequency or the limiting resonance frequency by the changing means A tire air pressure detection device comprising: a prohibition unit that prohibits a change in the limit spring constant. 17. The changing means calculates the limit resonance frequency or the limit spring constant after tire replacement by adding the deviation to the limit resonance frequency or the limit spring constant corresponding to the standard tire. Claim 1
6. The tire pressure detection device according to item 6. 18. A traveling signal output means for outputting a traveling signal including a resonance frequency component of a tire installed in the vehicle when the vehicle is traveling, and a resonance frequency of the tire or a spring constant of the tire is extracted from the traveling signal. Extracting means, and a limiting resonance frequency or a limiting spring constant corresponding to the limiting air pressure that serves as a criterion for determining an abnormal air pressure of a predetermined standard tire, and extracted from the traveling signal in a state where the standard tire has a specified air pressure. Storage means for storing the standard resonance frequency or standard spring constant, signal generating means for generating a predetermined signal when the standard tire is replaced with a tire having the specified air pressure, and the signal generating means When a signal is detected, the deviation between the standard frequency or standard spring constant and the resonance frequency or spring constant extracted by the extracting means is detected. A deviation calculating means for calculating a, based on the deviation which is a calculation result of said deviation calculation means, the tire air pressure detecting device comprising changing means for changing the limit resonant frequency to limit spring rate, that comprises a.