JP3328533B2 - Tire pressure abnormality judgment 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 abnormality judging device for judging an abnormal air pressure of a tire of an automobile or the like, and more particularly, to an abnormality of a tire air pressure based on a motion state amount of a wheel such as a wheel speed. The present invention relates to a tire pressure abnormality determining device for determining.

[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 vibration component of the wheel speed caused by the vibration of the tire is extracted from the speed signal, and a resonance frequency in a vertical direction or a front-rear direction of the tire or a spring constant of the tire is determined based on the vibration component. Conventionally, various configurations of tire pressure abnormality determination devices for determining abnormality have been proposed.

For example, Japanese Unexamined Patent Application Publication No.
Japanese Patent Application Laid-Open No. 15069/1999 discloses detecting the wheel speed of each wheel, and disturbing the tire from the road surface and the tire based on the wheel speed signal when the magnitude of the vibration input input to the tire from the road surface is within a predetermined range. A tire air pressure abnormality determining device configured to obtain a parameter representing a change in the spring constant of the tire by an observer, estimate a tire air pressure (spring constant of the tire) from these disturbances and parameters, and determine an abnormality in the tire air pressure. I have.

According to such a tire pressure abnormality determination apparatus, the wheel speed of each wheel is detected, and the tire speed is detected based on the wheel speed signal when the magnitude of the vibration input inputted to the tire from the road surface is within a predetermined range. Since the abnormality of the air pressure is determined, it is possible to determine the abnormality of the tire air pressure without the need for a means for directly detecting the tire air pressure such as a pressure sensor, and to determine the magnitude of the vibration input input to the tire from the road surface. Regardless, it is possible to determine the abnormality of the tire pressure with higher accuracy than when the abnormality of the tire pressure is determined.

[0005]

However, in the conventional tire pressure abnormality judging device as described above, when the vehicle speed is in a low vehicle speed range, the tire pressure is abnormally low even though the tire pressure is normal. In some cases, it is determined incorrectly.
The inventor of the present application has conducted various experimental studies on this point. As a result, the resonance point of the vibration in the yaw direction of the wheel, that is, the vibration about the vertical axis of the wheel exists in a frequency range lower than the resonance point of the tire, and When the vehicle speed is in a low vehicle speed range, the resonance level of the tire is low, so that the influence of the resonance noise in the yaw direction of the wheel becomes relatively high, so that the abnormality of the tire pressure is determined even though the actual tire pressure is normal. Was found to be wrong.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems in the conventional tire pressure estimating apparatus, and a main object of the present invention is to eliminate the influence of resonance noise in the yaw direction of the wheel. Thus, the accuracy of the tire pressure abnormality determination is further improved.

[0007]

Means for Solving the Problems] major challenges such as described above, according to the present invention, a means for detecting the motion state amount of the wheel, disturbance and against the wheel from the detection value of the motion variable of the wheel An observer for estimating a parameter representing a change in a spring constant of a tire; a means for calculating a correction amount for a disturbance estimated by the observer with respect to a yaw resonance of the wheel based on a detected value of a motion state amount of the wheel; and A tire pressure abnormality determination device (configuration of claim 1), comprising: means for correcting the estimated disturbance, and means for determining whether or not the tire pressure is abnormal based on the corrected estimated disturbance and the parameter. means for detecting a motion state amount of the wheel, against the wheel from the detection value of the motion variable of the wheel
And observer for estimating parameters representing the change in the spring constant of the disturbance and tire, means for calculating a correction amount for the spring constant of the tire for the yaw direction resonance of the wheel based on the detection value of the motion variable of the wheel, the estimated Means for calculating the spring constant of the tire based on the disturbance and the parameter; means for correcting the spring constant with the correction amount; and means for determining whether or not the tire air pressure is abnormal based on the corrected spring constant. A tire pressure abnormality determining device (constitution of claim 2) or means for detecting a wheel motion state quantity, and removing a signal in a yaw direction resonance frequency band of a wheel from a signal of a detected value of the wheel motion state quantity. estimating means for processing, a parameter representing a change in the spring constant of the disturbance and tire against the wheel from the detection value of the motion variable of the removal process by the wheel And observer, tire pressure based on the estimated disturbance and the parameter is achieved by the tire air pressure abnormality determining apparatus having a means for determining whether an abnormality (the third aspect).

[0008] According to the first aspect of the present invention, the observer
Out of the detected value of the wheel motion state
Estimation of parameters representing disturbance and changes in tire spring constant
Is, the correction amount for the estimated disturbance due observer for the yaw direction resonance of the wheel based on the detected value of the wheel motion state quantity is calculated, the estimated disturbance compensation by the correction amount, based on the corrected estimated disturbance and parameters Since it is determined whether or not the tire pressure is abnormal, even in a situation where the tire resonance level is low and the tire is likely to be affected by the yaw direction resonance noise included in the detected value of the wheel motion state quantity, the actual tire pressure is substantially reduced. The abnormality determination of the tire air pressure is performed based on the estimated disturbance and the parameter which are not affected by the yaw direction resonance noise, and therefore, the accuracy of the abnormality determination of the tire air pressure is further improved.

According to the second aspect of the present invention, the observer
From the detected value of the wheel motion state
Parameters representing the change in tire and spring constant are estimated.
The correction amount for the tire's spring constant for the yaw direction resonance of the wheel is calculated based on the detected value of the wheel motion state amount, the tire's spring constant is calculated based on the estimated disturbance and the parameters, and the spring constant is calculated based on the correction amount. Is corrected, and it is determined whether or not the tire air pressure is abnormal based on the corrected spring constant. Therefore, the tire resonance level is low and the yaw direction resonance noise of the wheel included in the detected value of the wheel motion state quantity is small. Even in a susceptible situation, the abnormality determination of the tire pressure is performed based on the spring constant of the tire substantially free from the influence of the resonance noise in the yaw direction, so that the accuracy of the abnormality determination of the tire pressure is further improved. .

According to the third aspect of the present invention, the signal in the resonance frequency band of the wheel in the yaw direction is removed from the signal of the detected value of the motion state of the wheel, and the removed motion state of the wheel is detected. estimated parameter representing a change in the disturbance and the spring constant of the tire against the wheel from the value by an observer, since whether the tire air pressure based on the estimated disturbance and parameters is abnormal, the resonance level of the tire Even in a situation where it is easily affected by the yaw resonance noise of the wheel included in the detected value of the wheel motion state amount, the disturbance is more than the detected value of the wheel motion state amount substantially free from the influence of the yaw direction resonance noise. And the parameters are estimated by the observer, so that the tire pressure abnormality determination is performed without being affected by the yaw direction resonance noise. Constant of accuracy is even more increased. According to the present invention, in any one of the first to third aspects, the motion state amount of the wheel is a wheel speed. Accordingly, the observer estimates parameters representing the disturbance from the road surface to the wheel and the change in the spring constant of the tire from the detected value of the wheel speed. The “wheel motion state quantity” in the present invention is not limited to the wheel speed, but can extract a vibration component caused by the vibration of the tire and determine the resonance frequency in the vertical direction or the front-rear direction of the tire based on the vibration component. What is necessary is just the motion state quantity of a wheel.

[0011]

According to a preferred embodiment of the present invention, in the configuration according to any one of claims 1 to 3, the observer uses the wheel speed as a moving state amount of the wheel. disturbance against the wheel, (preferably configured twist angle estimating a between the angular velocity and the rim portion and the belt portion of the tire of the belt portion of the tire as a parameter representing a change in the spring constant of the tire Aspect 1).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1, the means for determining whether or not the tire air pressure is abnormal includes a disturbance estimated by an observer, a belt-side portion. Is calculated based on the angular velocity of the tire and the torsion angle between the rim-side portion and the belt-side portion, and it is determined whether or not the tire pressure is abnormal based on the change amount. (Preferred embodiment 2).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 1 or 2, the correction amount for the estimated disturbance by the observer is configured to be calculated based on the wheel speed (preferably). Aspect 3).

According to another preferred embodiment of the present invention, in the configuration of the preferred embodiment 2, the correction amount for the tire spring constant is a correction amount for the change amount of the tire spring constant based on the wheel speed. It is configured to be operated (preferred mode 4).

According to another preferred embodiment of the present invention, in the configuration of the above-mentioned preferred embodiment 1 or 2, the signal elimination processing means detects a resonance value of the wheel in the yaw direction based on a signal of the detected value of the motion state amount of the wheel. A signal in a predetermined frequency band including a frequency band is removed, and the predetermined frequency band is configured to be variably set based on a wheel speed (preferred mode 5).

[0016]

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

First Embodiment FIG. 1 is a schematic configuration diagram showing a first embodiment of a tire air pressure abnormality judging device according to the present invention, FIG. 2 is an explanatory diagram showing a dynamic model of a wheel, and FIG. FIG. 2 is a block diagram of the tire pressure determination device shown in FIG. 1.

In FIG. 1, a left front wheel 10FL and a right front wheel 10
FR, left rear wheel 10RL and right rear wheel 10RR are provided with wheel speed sensors 12FL, 12FR, 12RL and 12RR, respectively. These wheel speed sensors are pulse signals corresponding to the wheel speeds of the corresponding wheels, as is well known. Is output. Generally, the wheel is a tired wheel having a tire mounted on the outer periphery of the wheel. Therefore, as shown in FIG. 2, the wheel 10 has a rim-side portion 20 and a belt-side portion 22 which are relatively rotatable by a torsion spring 24. Each wheel speed sensor detects the angular velocity of the rim-side portion 20 of the corresponding wheel strictly because it may be considered to be connected.

Each of the wheels 12FL to 12RR is provided with a torque sensor 14FL to 14RR for detecting a braking / driving torque Td acting on the shaft of the wheel. A pulse signal from each wheel speed sensor and a braking / driving torque signal from each torque sensor are input to a tire pressure determining device 16, and the determining device 16 determines tire air pressure (spring constant of tire) of each wheel based on these signals as described later. ) Is calculated by estimation, and it is determined whether or not the tire pressure of the wheels is abnormal. If the tire pressure is abnormal, a control signal is output to the alarm device 18 to warn the occupant of the vehicle. Has become.

As shown in FIG. 3, the tire pressure judging device 16 includes a wheel speed calculating block 26 which receives a pulse signal from each wheel speed sensor, and a pre-processing filter block 28.
And a disturbance observer 30 receiving a braking / driving torque signal from each torque sensor, a correlation calculation block 32, a normalization block 34, and an abnormality determination block 36 for determining whether or not the tire air pressure is abnormal. I have. Further, the tire pressure determination device 16 of this embodiment includes a disturbance correction value calculation block 38 and a disturbance correction block 40.

The tire pressure judging device 16 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 other embodiments described later.

The wheel speed calculation block 26 is a wheel speed sensor 1
The wheel speed (the rotation speed of the rim side portion) is calculated based on the pulse signals supplied from 2FL to 12RR, and the pre-processing filter block 28 is suitable for determining the tire air pressure among the wheel speeds calculated by the wheel speed calculation block 26. Those within a predetermined frequency range are extracted.

The disturbance observer 30 is constructed based on the model of the wheel 10 shown in FIG. The wheel 10 is connected to the rim-side portion 20 of the moment of inertia _JR and the moment of inertia J
A torsion spring 24 having a spring constant K and a belt side portion 22 of _B
If the wheels are modeled as connected by the following equation, the following state equations (1) to (3) are established, and thereby a linear system is configured.

[Number 1] _{J R ω R '= -Kθ RB} + T 1 ··· (1) J B ω B' = Kθ RB -T d ··· (2) θ RB '= ω R -ω B ··· (3) where ω _R : angular velocity of the rim side part 20 ω _R ': angular acceleration of the rim side part 20 ω _B : angular velocity of the belt side part 22 ω _B ': angular acceleration of the belt side part 22 θ _RB : rim side Torsion angle between portion 20 and belt side portion 22 T ₁ : braking / driving torque detected by torque sensor 14 T _d : disturbance torque from road surface

Although an actual wheel has a damper between the rim-side portion 20 and the belt-side portion 22, its influence is relatively small, and therefore its existence is neglected in this embodiment. .

If the above state equation is expressed using vectors and matrices, the following equation (4) is obtained.

(Equation 2)

If the air pressure of the tire changes and the spring constant of the torsion spring 24 changes from K to K + ΔK, the motion of the wheel 10 is expressed by the following equation (5).

(Equation 3)

That is, a change in the spring constant K by ΔK is equivalent to a disturbance represented by the last term on the right side of the equation (5) being applied to a normal tire. This disturbance contains information on the change amount ΔK of the spring constant K, and the spring constant K
Changes according to the tire air pressure, the amount of change in the tire air pressure can be estimated by estimating this disturbance. The disturbance observer technique is used to estimate the disturbance. If the torque _Td from the road surface is now treated as a disturbance, the disturbance w to be estimated is expressed by the following equation (6). .

(Equation 4)

However, since only one element of the disturbance [w] can be estimated theoretically, the second element of the equation (6) is set as a disturbance w _2, and this disturbance w ₂ is expressed by the following equation (7). In this case, the state equation of the wheel 10 is expressed by the following equation (8), and therefore, the disturbance observer is configured based on the equation (8).

[0029]

W ₂ = (− 1 / J _B ) T _d + (ΔK / J _B ) θ _RB (7)

(Equation 6)

The disturbance observer estimates a disturbance as one of the state variables of the system. Therefore, in order to include the disturbance w ₂ of (7) to the state of the system to approximate the dynamics of the disturbance to be estimated by the following equation (9).

## EQU7 ## w ₂ ′ = 0 (9)

This approximation means that a continuous smooth change of the disturbance is approximated to a stepwise change along it (zero order approximation), and the disturbance estimation speed of the disturbance observer 30 is changed to the disturbance to be estimated. This approximation is well tolerated if sufficiently fast. From the above equation (9), when the disturbance w ₂ is included in the state variables of the system, an extended system of the following equation (10) is configured.

(Equation 8)

In the equation (11), [ω _B θ _RB
w ₂ ] ^T is a state variable that cannot be detected. Therefore, if the disturbance observer 30 is configured based on this system, the disturbance w ₂ and the state variables ω _B , θ that cannot be measured originally
_RB can be estimated.

In order to simplify the description, the vectors and matrices of the equation (10) are decomposed and expressed as follows.

(Equation 9)

At this time, the state [z] = [ω _B θ _RB w
₂ ] The configuration of the minimum dimension observer for estimating ^T is expressed by the following equation (11).

[0035]

[Z _p ′] = [A ₂₁ ] [x _a ] + [A ₂₂ ] [z _p ] + [B ₂ ] [u] + [G] ｛[x _a ′] − ([A ₁₁ ] [X _a ] + [A ₁₂ ] [z _p ] + [B ₁ ] [u])｝ = ([A ₂₁ ] − [G] [A ₁₁ ]) [x _a ] + ([A ₂₂ ] − [G] [A ₁₂ ]) [z _p ] + [G] [x _a ′] + ([B ₂ ] − [G] [B ₁ ]) [u] (11) where [z _p ]: Estimated value of [z] [z _p ']: Change rate of estimated value [z _p ] [G]: Gain that determines estimated speed of disturbance observer 30

The error [e] between the true value [z] and the estimated value [z _p ] is set as [e] = [z] − [z _p ], and the rate of change of the error [e] is [e ′]. ], The following equation (12) is obtained.

[E ′] = ([A ₂₂ ] − [G] [A ₁₂ ]) [e] (12)

This represents the estimation characteristic of the disturbance observer 30, and the eigenvalue of the matrix ([A ₂₂ ] − [G] [A ₁₂ ]) is the pole of the disturbance observer 30. The observer gain [G] may be determined so that the estimated speed becomes a predetermined speed.

In the above, the disturbance w ₂ is given by the above equation (7).
That is, assuming that w ₂ = (− 1 / J _B ) T _d + (ΔK / J _B ) θ _RB , the disturbance w when the spring constant K of the torsion spring 24 of the disturbance observer 30 changes by ΔK. _Two
Has been described, the moment of inertia J _{B of the} belt-side portion 22 of the disturbance observer 30 is described.
There and disturbances in the case of changes in J _B + .DELTA.J _B, the moment of inertia of the rim portion 20 of the disturbance observer 30 J _R is J
_The portion for estimating the disturbance when it changes to _R + ΔJ _R can be similarly configured.

The correlation calculation block 32, based on the estimated value theta _RBp estimate w _2p and torsion angle theta _RB disturbance w ₂ estimated by the disturbance observer 30, the torsion and the estimated value w _2p of the disturbance w ₂ as described below the cross-correlation C (w of the angle estimated value θ _RBp
2p , θ _RBp ) and the autocorrelation C of the estimated torsion angle θ _RBp
(Θ _RBp , θ _RBp ) is calculated.

The normalization block 34 performs a normalization process, that is, an autocorrelation C (θ _RBp ,
cross-correlation C (w _2p for theta _RBp), calculates the L _K value as the ratio of theta _RBp), stored in the L _K value memory of RAM.

L _K = C (w _2p , θ _RBp ) / C (θ _RBp , θ _RBp ) (13)

The abnormality determination block 36 calculates a change amount ΔK of the spring constant based on the L _K value stored in the L _K value memory, and determines whether or not the tire air pressure is abnormal based on the change amount. I do.

That is, there is a relationship between the L _K value and the change amount ΔK of the spring constant expressed by the following equation (14) obtained based on the above equation (8).

L _K = (− 1 / J _B ) C ₀ + ΔK / J _B (14) where C ₀ is C (T _dp , θ _RBp ) / C (θ _RBp , θ
_RBp ), which is independent of the change in the spring constant K, and can be compensated for by _obtaining the tire pressure in a normal state in advance. Also, C
(T _dp , θ _RBp ) represents a cross-correlation between the estimated value of the disturbance torque T _{d and} the estimated value of the torsion angle θ _RB .

The relationship between L _K and ΔK is previously stored in the ROM as a spring constant change table, and therefore, L _K = C (w _2p , θ) stored in the L _K value memory.
_RBp ) / C (θ _RBp , θ _RBp )
The change amount ΔK of the spring constant K of No. 4 is calculated. Then, the change amount ΔK is compared with a reference value ΔK ₀ stored in the ROM. If the change amount ΔK is smaller than a reference value ΔK ₀ which is a negative constant, it is determined that the tire air pressure is abnormally low, and the alarm device 18 is activated. Generates an alarm.

The disturbance correction value calculation block 38 further includes a disturbance correction value Ka based on the wheel speed after the pre-processing filter processing, as described later, in order to eliminate the influence of the yaw direction resonance noise of the wheel.
And the disturbance correction block 40 calculates the disturbance observer 30
The disturbance w _2p estimated by the above is _replaced with a disturbance correction value Ka as described later.
Correct based on.

As can be understood from the above description, the wheel speed sensor 1
Function means for further detecting the motion state amount of the wheel to 2FL~12RR and the wheel speed calculation block 2 6 is achieved, the function of the observer by disturbance observer 30 is achieved, correlation calculation block 32, normalization block 34, and abnormal The function of means for determining whether or not the tire pressure is abnormal is achieved by the determination block 36. Furthermore, the disturbance correction value calculation block 38 and the disturbance correction block 40 achieve the function of a means for calculating the correction amount for the estimated disturbance by the observer for the yaw resonance of the wheel, and the function of the means for correcting the estimated disturbance by the disturbance correction block 40. Achieved.

FIG. 4 is a general flowchart showing a tire pressure abnormality determination routine executed by the tire pressure determination device 16 of the first embodiment. It should be noted that the abnormality determination of the tire air pressure according to the flowchart shown in FIG. 4 is repeatedly executed in the order of, for example, the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel, and the same applies to other embodiments described later.

First, in step 10, a pulse signal indicating the wheel speed of a wheel to be subjected to the tire pressure abnormality determination and a signal indicating braking / driving torque are read. In step 20, the wheel speed is indicated. The wheel speed Vwi is calculated based on the pulse signal, and in step 30, the wheel speed signal is subjected to pre-processing filtering, that is, band-pass filtering at predetermined upper and lower cutoff frequencies.

In step 40, i is incremented by one, and in step 50, i is incremented by a reference value Na (1).
(A positive constant of about 00 to 1000) is determined, and if a negative determination is made, step 1 is performed.
Returning to 0, when a positive determination is made, i is reset to 0 in step 60.

In step 70, the above-described disturbance observer processing is performed on the disturbance observer 30 based on the wheel speed Vwi and the corresponding braking / driving torque, whereby the estimated value w2p of the disturbance w2 and the change in the tire spring constant are determined. Represent
Estimate θRBp estimate .omega.B p及 Binejiri angle θRB angular velocity .omega.B belt portion 22 as a parameter are obtained.

In step 80, the above-mentioned disturbance correction value Ka of the disturbance correction value calculation block 38 is calculated based on the wheel speed after the pre-processing filter processing, that is, the angular speed ω _R of the rim side portion of the tire, by the following equation (15). In step 90, the estimated disturbance _w2p is corrected and calculated according to the following equation (16) for the disturbance correction block 40 as described above. Incidentally, the function f (ω _R ) of the equation (15) may be obtained experimentally, and the disturbance correction value Ka may be obtained by map calculation.

[0051]

## EQU14 ## Ka = f (ω _R ) (15)

[ _Equation 15] w _2p = w _2p + Ka · θ _RBp (16)

In step 100, the above-described correlation operation is performed on the correlation operation block 32 in accordance with the flowchart shown in FIG. 5, whereby the estimated value w _2p of the disturbance w _{2 and} the estimated torsion angle value θ _RBp are determined. Correlation C (w _2p ,
theta _RBp) and estimated torsion angle value theta _RBp of the autocorrelation C (theta
_RBp , θ _RBp ) are calculated.

In step 110, the above-described normalization processing is performed on the normalization block 36, whereby the cross-correlation C (w) with respect to the auto-correlation C (θ _RBp , θ _RBp ) is performed.
_2p , θ _RBp ), and the L _K value is calculated.
_The amount of change ΔK in the tire spring constant is calculated based on the _K value.

At step 120, it is determined whether or not the amount of change ΔK of the spring constant is smaller than its reference value ΔK ₀ (negative constant). If a negative determination is made, the routine proceeds directly to step 140. When an affirmative determination is made, a control signal is output to the alarm device 18 in step 130, and then the process proceeds to step 140. In step 140, after the data calculated in each of the above steps is cleared, the process returns to step 10, and the steps after step 10 are executed for the next wheel for which tire pressure abnormality determination is to be performed.

The above-described correlation calculation routine in step 100 is executed as follows in accordance with the flowchart shown in FIG.

In step 101, the current disturbance estimated value W _{2p (j)} and the torsion angle estimated value θ _{RBp (j)} calculated in step 70 are read. In step 102, the following ( According to equation (17), the cross correlation C (w _2p ,
θ _RB ) is calculated. That is, the product of the disturbance estimation value w _{2p (j)} and the torsion angle estimation value θ _{RBp (j)} is calculated, and the product is added to the cross-correlation C (w _2p , θ _RB ). However, when step 102 is first executed, the cross-correlation C (w _2p , θ _RBp )
Is 0, the disturbance estimation value w _{2p (j) is} stored in the cross-correlation memory.
Only the product of the torsion angle estimation value θ _{RBp (j)} is stored.

C (w _2p , θ _RB ) = C (w _2p , θ _RB ) + w _{2p (j)} · θ _{RBp (j)} (17)

Similarly, in step 103, the autocorrelation C (θ _RBp , θ _RBp ) is calculated according to the following equation (18). That is, the square of the estimated torsion angle θ _{RBp (j)} is calculated and added to the autocorrelation C (θ _RBp , θ _RBp ) in the autocorrelation memory.

(17) C (θ _RBp , θ _RBp ) = C (θ _RBp , θ _RBp ) + θ _{RBp (j)} ² (18)

In step 104, the integer j is incremented by one, and in step 105, the integer j is set to N
b (a positive constant integer) is determined, and
When a negative determination is made, the process returns to step 10, and when an affirmative determination is made, j is set to 0 in step 106.
To terminate the correlation calculation routine and proceed to the next step 110.

As understood from the above description, the functions of the wheel speed calculation block 26 of FIG. 3 are achieved by steps 10 and 20, and the pre-processing filter block 2 is determined by step 30.
8 is achieved, the function of the disturbance observer 30 is achieved by step 70, and the function of the correlation operation block 32 is achieved by step 100. Step 11
The function of the normalization block 34 is achieved by 0, and the function of the abnormality determination block 36 is achieved by steps 120 and 130. Further, the function of the disturbance correction value calculation block 38 is achieved by step 80, and the function of the disturbance correction block 40 is achieved by step 90.

Thus, according to the first embodiment, the disturbance w ₂ , the estimated value ωBp of the angular velocity ωB of the belt side portion 22, and the torsion angle θ _RB are estimated by the processing of the disturbance observer in steps 10 to 70, In step 80, the disturbance correction value Ka is calculated, and in step 90, the disturbance estimation value _w2P is corrected to remove the influence of the yaw direction resonance noise of the wheel from the disturbance estimation value. based on the estimated value theta _RBp correction estimated disturbance value after w _2p and torsion angle theta _RB, cross-correlation C (w _2p, θ _RBp) between the estimated value w _2p and torsion angle estimate theta _RBp of the disturbance w ₂ and the torsion The autocorrelation C (θ _RBp , θ _RBp ) of the angle estimation value θ _RBp is calculated, the normalization is performed in step 110, and the abnormality determination of the tire air pressure in steps 120 and 130 is performed.

Therefore, according to this embodiment, since the vehicle speed is low and the resonance level of the tire is low, even in a situation where the vehicle is easily affected by the yaw direction resonance noise of the wheel included in the wheel speed signal, the yaw is substantially reduced. Since the change amount ΔK of the spring constant of the tire is calculated based on the estimated disturbance or the like which is not affected by the direction resonance noise, the abnormality determination of the tire air pressure can be performed based on the change amount ΔK of the spring constant. Therefore, it is possible to prevent the tire pressure from being erroneously determined to be abnormal due to the above, and to perform the tire pressure abnormality determination with high accuracy.

Further, according to this embodiment, it is only necessary to add steps 80 and 90 to the conventional tire pressure abnormality determination routine, and a special sensor or the like for eliminating the influence of the yaw direction resonance noise of the wheel is provided. Is unnecessary, so that it is possible to inexpensively configure an abnormality determination device that determines the abnormality of the tire pressure with high accuracy without being affected by the resonance noise of the yaw direction of the wheels.

Second Embodiment FIG. 6 is a block diagram of a second embodiment of a tire air pressure abnormality judging device according to the present invention, and FIG. 7 shows a tire air pressure abnormality judging routine in the second embodiment. It is a general flowchart. In FIG. 6, the members corresponding to the members shown in FIG. 3 are denoted by the same reference numerals as those shown in FIG. 3, and are shown in FIG. Steps corresponding to the steps are given the same step numbers as those given in FIG.

As shown in FIG. 6, the tire pressure judging device 16 of this embodiment includes a wheel speed calculating block 26,
In addition to the pre-processing filter block 28, the disturbance observer 30, the correlation calculation block 32, the normalization block 34, and the abnormality determination block 36, a spring constant correction amount calculation block 42
And a spring constant correction block 44.

The spring constant correction amount calculation block 42 calculates a correction amount ΔKa for the change amount ΔK of the spring constant of the tire based on the wheel speed subjected to the pre-processing filter processing, as described later.
The spring constant correction block 44 corrects the change amount ΔK of the spring constant based on the correction amount ΔKa as described later, thereby eliminating the influence of the yaw direction resonance noise of the wheels. Accordingly, the function of the means for calculating the correction amount for the tire's spring constant for the yaw resonance of the wheel with respect to the yaw direction resonance of the wheel is achieved by the spring constant correction amount calculation block 42. Function is achieved.

Steps 112 and 1 of this embodiment
Steps 10 to 70 and steps 100 to 1 other than 14
Steps 40 are performed in the same manner as in the first embodiment. In step 112, the spring constant correction amount ΔKa is calculated according to the following equation (19) based on the wheel speed after the pre-processing filter processing in step 30, that is, the angular speed ω _R of the rim side portion of the tire, and in step 114 Then, according to the following equation (20), the change amount ΔK of the spring constant becomes the correction amount ΔK.
Corrected at a.

[0067]

ΔKa = f (w _R ) (19)

[0068]

(19) According to the second embodiment, the change amount ΔK of the spring constant calculated by the normalization in step 110 is calculated in step 1
Since the correction is made by the correction amount ΔKa in steps 12 and 114, even in a situation where the yaw direction resonance noise of the wheel included in the wheel speed signal is liable to be affected, the yaw direction resonance noise is not substantially affected. An abnormality determination of the tire air pressure can be performed based on the change amount ΔK of the spring constant. Therefore, it is possible to prevent the tire air pressure from being erroneously determined to be abnormal due to the yaw direction resonance noise of the wheel, and to prevent the tire air pressure from being abnormal. The abnormality determination can be performed with high accuracy.

Also in the case of this embodiment, steps 112 and 11 are performed in the conventional tire pressure abnormality determination routine.
4 only needs to be added, and a special sensor or the like for eliminating the influence of the yaw direction resonance noise of the wheel is unnecessary. It is possible to configure the abnormality determination device for performing the accuracy with low cost.

Third Embodiment FIG. 8 is a block diagram of a third embodiment of a tire pressure abnormality judging apparatus according to the present invention, and FIG. 9 shows a tire pressure abnormality judgment routine in the third embodiment. It is a general flowchart. In FIG. 8, members corresponding to those shown in FIG. 3 are denoted by the same reference numerals as those shown in FIG. 3, and are shown in FIG. Steps corresponding to the steps are given the same step numbers as those given in FIG.

As shown in FIG. 8, the tire pressure judging device 16 of this embodiment has a pre-processing filter setting block 46 in addition to the wheel speed calculating block 26 and the like. Variably sets the pass band of the band-pass filter processing in the pre-processing filter block 28 based on the wheel speed calculated by the wheel speed calculation block 26 as described later.

Steps 10 to 70 and steps 100 to 140 other than step 25 in this embodiment are executed in the same manner as in the first embodiment.
In step 5, when the wheel speed calculated in step 20, that is, the angular speed ω _R of the rim side portion of the tire is equal to or lower than ω _Ro at which resonance in the yaw direction of the wheel occurs, as shown in FIG. 10, for example. The lower limit cutoff frequency f _cl of the band pass filter in the pre-processing filter processing of No. 30
Set the pre-processing filter so that is higher.

Thus, according to the third embodiment, based on the wheel speed calculated in step 20, step 25
In the situation where the influence of the resonance noise in the yaw direction of the wheels is high at low vehicle speed, the lower limit cutoff frequency fcl of the band-pass filter in the pre-processing filter processing in step 30 is set high. In the situation where the influence of the yaw direction resonance noise of the wheel included in the wheel speed signal is excluded and the tire pressure can be determined with high accuracy, and the vehicle speed is high and the influence of the yaw direction resonance of the wheel is small, Since the lower limit cutoff frequency fcl is set low, the amount of signals passing through the band-pass filter can be increased, and the frequency of tire pressure abnormality determination can be increased.

Also in the case of this embodiment, it is only necessary to add step 25 to the conventional tire pressure abnormality determination routine, and a special sensor for eliminating the influence of the yaw direction resonance noise of the wheels is not required. Therefore, it is possible to inexpensively configure the abnormality determination device that performs the abnormality determination of the tire air pressure with high accuracy without being affected by the yaw direction resonance noise of the wheels.

In the first to third embodiments, the change ΔK in the tire spring constant calculated in step 110 or the change in the tire spring constant corrected in step 114 Step 120 based on the quantity ΔK
It is determined whether or not the tire air pressure is abnormal in the above. If necessary, the change amount ΔK of the spring constant
The tire pressure P may be calculated based on the tire pressure P, and the tire pressure P may be calculated as the sum of the normal tire pressure Po and the change ΔP. Further, in this case, the abnormality determination of the tire pressure is based on the calculated tire pressure P or the change amount Δ
It may be performed based on P.

In the third embodiment, the pre-processing filter is not set in step 25, but the wheel speed signal is obtained from the wheel speed signal before or after the pre-processing filter processing in step 30. May be performed, and this processing may be achieved by either soft signal processing or hardware signal processing.

Further, in each of the above-described embodiments, the disturbance observer 30 receives the braking / driving torque Td of each wheel as an input. with ₁ term is omitted, the torque sensor 14
FL to 14RR may be omitted.

Although the present invention has been described in detail with reference to specific embodiments, the present invention is not limited to these 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.

[0079]

As is apparent from the above description, according to the configuration of the first aspect, the abnormality determination of the tire air pressure is performed based on the estimated disturbance and the parameter substantially free from the influence of the yaw direction resonance noise. And claim 2
According to the configuration, the tire pressure abnormality can be determined based on the spring constant of the tire substantially free from the influence of the yaw direction resonance noise.
It is possible to estimate disturbances and parameters by an observer from the detected value of the motion state amount of the wheel substantially free from the influence of the yaw direction resonance noise, thereby performing abnormality determination of the tire pressure without being affected by the yaw direction resonance noise. Therefore, according to the present invention, even in a situation where the tire resonance level is low and the tire is likely to be affected by the yaw direction resonance noise included in the detected value of the wheel motion state quantity, the accuracy of the tire pressure abnormality determination can be improved. It can be further improved.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a dynamic model of a wheel.

FIG. 3 is a block diagram of the tire pressure determining apparatus shown in FIG. 1;

FIG. 4 is a general flowchart illustrating a tire pressure abnormality determination routine according to the first embodiment.

FIG. 5 is a step 10 of the flowchart shown in FIG. 4;
7 is a flowchart showing a correlation calculation routine at 0.

FIG. 6 is a block diagram of a tire pressure determination device according to a second embodiment.

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

FIG. 8 is a block diagram of a tire pressure determination device according to a third embodiment.

FIG. 9 is a general flowchart illustrating a tire air pressure abnormality determination routine according to a third embodiment.

FIG. 10 is a graph showing a relationship between an angular velocity ω _R of a rim side portion of a tire and a lower limit cutoff frequency f _cl of a band pass filter in a pre-processing filter process.

[Explanation of symbols]

 12FL-12RR ... wheel speed sensor 16 ... tire air pressure judging device 18 ... warning device 26 ... wheel speed calculation block 28 ... pre-processing filter block 30 ... disturbance observer 32 ... disturbance correction value calculation block 34 ... disturbance correction block 36 ... correlation calculation block 38: Normalization block 40: Abnormality determination block 42: Spring constant correction amount calculation block 44: Spring constant correction block 46: Pre-processing filter block

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kaoru Ohashi 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Hiroyoshi Kojima 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation ( 72) Inventor Taguchi Health 1-1, Showa-cho, Kariya-shi, Aichi Pref., Japan (72) Inventor Yuichi Inoue 1-1-1, Showa-cho, Kariya, Aichi pref., Denso Corporation (72) Inventor, Koji Umeno 41 Toyota Chuo R & D Co., Ltd., at 41, Chuchu-Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture (56) References JP-A-7-89304 (JP, A) JP-A-8-34215 (JP, A) 8-15069 (JP, A) JP-A-8-11085 (JP, A) JP-A-7-137509 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60C 23/00 -23/0 8 G01L 17/00

Claims (4)

(57) [Claims] And 1. A means for detecting the motion state amount of the wheel, the observer for estimating parameters representing the change of the disturbance and the spring constant of the tire against the wheel from the detection value of the motion variable of the wheel, the wheel Means for calculating a correction amount for the estimated disturbance by the observer for the yaw direction resonance of the wheel based on the detected value of the motion state amount; means for correcting the estimated disturbance with the correction amount; and the corrected estimated disturbance and the Means for determining whether or not the tire pressure is abnormal based on the parameter. 2. A means for detecting the motion state amount of the wheel, the observer for estimating parameters representing the change of the disturbance and the spring constant of the tire against the wheel from the detection value of the motion variable of the wheel, the wheel Means for calculating a correction amount for the tire spring constant for the yaw resonance of the wheel based on the detected value of the motion state amount; means for calculating the tire spring constant based on the estimated disturbance and the parameter; A tire pressure abnormality determination device, comprising: means for correcting the spring constant; and means for determining whether or not the tire pressure is abnormal based on the corrected spring constant. 3. A means for detecting a motion state amount of a wheel, a means for removing a signal in a yaw direction resonance frequency band of a wheel from a signal of a detected value of the wheel motion state amount, and and observer for estimating parameters representing the change in the spring constant of the disturbance and tire against the wheel from the detection value of the motion variable, the estimated disturbance and means for determining whether the tire air pressure is abnormal based on the parameter And a tire air pressure abnormality determining device. 4. The tire pressure abnormality determination device according to claim 1, wherein the motion state quantity of the wheel is a wheel speed.