JPH10175411A - Tire air ressure estimating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further more improve estimating accuracy of a tire air pressure of a drive wheel by performing no drive wheel compensation at running time of so-called stride road. SOLUTION: A device has wheel speed sensors 32FL to 32RR detecting a speed of each wheel, vibration component extraction block 38 extracting a vibration component of the speed of each wheel caused by vibration of a tire from a speed signal of each wheel, correction block 40 obtaining a vibration component of the wheel speed after correction of a right/left drive wheel by removing the same phase component from a vibration component of the speed of the right/left drive wheels, and a drive wheel use tire air pressure estimation block 42 estimating a tire air pressure of the right/left drive wheels based on a vibration component of the wheel speed after correction. A difference degree arithmetic block 46 calculating a difference degree of a vibration component of a speed of a right/left driven wheel is provided, when the difference degree exceeds a reference value, estimation of a tire air pressure of the right/left drive wheel by the drive wheel use tire air pressure estimation block 42 is inhibited by an estimation inhibiting block 48.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tire pressure estimating apparatus for estimating the air pressure of a tire of an automobile or the like, and more particularly to a tire air pressure for estimating a tire air pressure by obtaining a tire spring constant based on a wheel speed signal. It relates to an estimation device.

[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. Tire pressure estimation that extracts a vibration component of the wheel speed caused by the tire vibration from the speed signal, obtains a vertical or vertical resonance frequency of the tire based on the vibration component, and estimates a tire pressure based on the resonance frequency. 2. Description of the Related Art Various types of apparatuses have been proposed in the related art, and one example is described in Japanese Patent Application Laid-Open No. 6-122304 filed by one of the present applicants.

According to such a tire pressure estimating apparatus, the tire pressure is estimated based on the resonance frequency of the vibration component of the wheel speed, so that there is no need for a means for directly detecting the tire pressure, such as a pressure sensor. Can be estimated.

In the tire pressure estimating apparatus as described above, the tire pressure of the driving wheel is accurately estimated due to the fact that the vibration component of the driving wheel includes the resonance component of the differential gear device and the suspension member. In order to solve this problem, the present applicant has disclosed in Japanese Patent Application No. 7-278338 a tire pressure estimating device in which so-called driving wheel compensation is performed, that is, "left driving wheel and right driving. Wheel speed detecting means for detecting the wheel speed of the wheel, and vibration component extracting means for extracting a vibration component of the wheel speed of the left and right driving wheels caused by the vibration of the tire from a wheel speed signal of the left and right driving wheels from the wheel speed detecting means. Correction means for obtaining a corrected vibration component of the wheel speed of the left and right drive wheels by removing the in-phase component from the vibration component of the wheel speed of the left and right drive wheels; A tire pressure estimation device having estimation means for estimating the tire pressure of the left and right drive wheels based on the vibration component of the wheel speed of the left and right drive wheels, and "a wheel for detecting the wheel speed of the left drive wheel and the right drive wheel" Speed detection means, vibration component extraction means for extracting a vibration component of the wheel speed of the left and right drive wheels caused by tire vibration from a wheel speed signal of the left and right drive wheels from the wheel speed detection means, and wheels of the left and right drive wheels First estimating means for estimating the first tire air pressure of the left and right driving wheels based on the vibration component of the speed, and removing the in-phase components from the vibration components of the wheel speeds of the left and right driving wheels to correct the left and right wheels. Correction means for determining a vibration component of the wheel speed of the drive wheel, comparison means for comparing the first tire pressure of the left and right drive wheels, and the corrected wheel speed for the drive wheel having the lower first tire pressure. of Second estimating means for estimating tire air pressure based on a dynamic component, and the first tire air pressure and the tire air pressure estimated by the second estimating means for the drive wheel having the lower first tire air pressure. A third estimating means for calculating the deviation, and estimating the tire pressure of the driving wheel having the higher first tire pressure to a value obtained by subtracting the deviation from the first tire pressure of the driving wheel. A tire pressure estimation device characterized by the fact that

[0005]

However, the present inventor has conducted an experimental study. According to the tire pressure estimating apparatus according to the above-mentioned proposal, the tire pressure estimating apparatus according to the present invention has a more accurate drive than the conventional tire air pressure estimating apparatus. Although it is possible to estimate the tire pressure of the wheels, when the vehicle travels on a so-called "crossover road" in which the road surface inputs to the left and right drive wheels are significantly different, the accuracy of the estimation of the tire pressure of the drive wheels is rather reduced by the drive wheel compensation. It became clear that the tire pressure of the driving wheels was estimated to be considerably lower than the actual pressure, and that it was sometimes impossible to properly determine the tire pressure abnormally.

In Japanese Patent Application No. 7-278338, "the means for determining the deviation of the magnitude of the disturbance inputted to the left and right driving wheels from the road surface within a predetermined time, and the method for determining the deviation when the deviation exceeds a reference value. A tire pressure estimating apparatus having means for stopping estimation of tire pressure ", and" means for obtaining a deviation of the magnitude of disturbance inputted from the road surface to the left and right driving wheels within a predetermined time, and the deviation exceeds a reference value. Sometimes, a tire pressure estimating apparatus having means for using the first tire pressure estimated by the first estimating means as the tire air pressure of the left and right driving wheels "has also been proposed.

[0007] According to these configurations, the driving wheel compensation is always performed irrespective of the magnitude of the deviation of the magnitude of the disturbance inputted to the left and right driving wheels from the road surface within a predetermined time. It is possible to improve the estimation accuracy of the tire pressure. However, the left and right driving wheels are connected to each other by a driving system, and the disturbance inputted to one driving wheel is transmitted to the other driving wheel, so that the deviation of the magnitude of the disturbance inputted to the left and right driving wheels causes Cannot effectively determine whether or not the vehicle is traveling on a straddle road, and it has been found that it is not possible to effectively prevent deterioration of the estimation accuracy of the tire air pressure of the drive wheels due to the drive wheel compensation.

The present invention has been made in view of the above-mentioned problems in the tire pressure estimating apparatus according to the above-mentioned proposal, and a main problem of the present invention is whether or not a vehicle is traveling on a straddle road. In addition to accurately determining whether or not the vehicle is traveling normally (when traveling on a non-crossing road), the driving wheel compensation is performed. Is to be further improved.

[0009]

According to the present invention, the main problems as described above are attributable to the wheel speed detecting means for detecting the wheel speed of each wheel, and to the wheel speed signal of each wheel resulting from the vibration of the tire. A vibration component extracting means for extracting a vibration component of the wheel speed of each wheel, and a vibration component of the corrected wheel speed of the left and right drive wheels by removing those in-phase components from the vibration components of the wheel speed of the left and right drive wheels. In a tire pressure estimating apparatus having a correcting means to be obtained and a driving wheel estimating means for estimating the tire pressure of the left and right driving wheels based on the vibration component of the corrected wheel speed, the vibration of the wheel speed of the left and right driven wheels is A tire air pressure estimating device comprising means for calculating the degree of difference between the components, wherein when the degree of difference exceeds a reference value, the estimation of the tire air pressure of the left and right driving wheels by the driving wheel estimating means is prohibited. ( Configuration of claim 1) or a wheel speed detecting means for detecting a wheel speed of each wheel, and a vibration component extracting means for extracting a vibration component of a wheel speed of each wheel caused by a tire vibration from a wheel speed signal of each wheel. Correction means for determining the corrected wheel speed vibration component of the left and right drive wheels by removing those in-phase components from the right and left drive wheel wheel speed vibration components; and A driving wheel estimating device for estimating the tire air pressure of the left and right driving wheels based on the driving wheel estimating device. A tire pressure estimating device for estimating the tire air pressure of the left and right driving wheels based on a vibration component of the wheel speed before correction of the left and right driving wheels when the degree of difference exceeds a reference value. Two It is achieved by formation).

According to the results of the experimental research conducted by the inventor of the present application, the wheel speed signal of the driving wheels includes the front-rear resonance component and the pitching resonance component of the differential gear device and the suspension member, and these resonance components are included. Appear in the left and right driving wheels in the same phase and the same amplitude, so that the resonance component of the driving system can be canceled by calculating the difference between the wheel speed signals of the left and right driving wheels. In addition, since the resonance components of the tires of the left and right driving wheels are unique to each other, even if the difference between the wheel speed signals of the left and right driving wheels is obtained, the resonance component of the tire is not eliminated.

According to the first and second aspects of the present invention, the in-phase components are removed from the vibration components of the wheel speeds of the left and right driving wheels, thereby obtaining the corrected vibration components of the wheel speeds of the left and right driving wheels. Since the tire pressures of the left and right drive wheels are estimated based on the corrected vibration components of the wheel speeds of the left and right drive wheels, the tire pressures of the left and right drive wheels are accurately estimated without being affected by drive system resonance.

According to the results of an experimental study conducted by the inventor of the present invention, when a vehicle travels on a straddle road, when a large vibration input is given to only one of the drive wheels, the wheel speed of the other drive wheel is increased. In the signal, vibration as the output of the quaternary system appears as a main component, and the frequency range in which the phase difference between the wheel speed signals of the left and right driving wheels is close to 180 ° (out of phase) is lower than the resonance frequency of the tire. Therefore, if the drive wheel compensation for removing the drive system vibration of the in-phase component is performed by the difference between the wheel speed signals of the left and right drive wheels, the opposite-phase components will be added, and the frequency appears in the opposite-phase region apparently. It has been found that a peak of the spectrum appears, and as a result, the tire pressure of the drive wheel is estimated to be lower than the actual pressure.

The left and right driving wheels are connected to each other by a driving system, whereas the left and right driven wheels are generally independent of each other. That is, according to the degree of difference between the vibration components of the wheel speeds of the left and right driven wheels, it is effective to determine whether the vehicle is traveling on a straddle road as compared with the case of the deviation of the magnitude of the disturbance inputted to the left and right drive wheels. Can be determined.

According to the above construction, the difference between the vibration components of the wheel speeds of the left and right driven wheels is calculated, and when the difference exceeds a reference value, the tires of the left and right driving wheels are determined by the driving wheel estimating means. Since the estimation of the air pressure is prohibited, it is reliably determined whether the vehicle is traveling on a straddle road, and when the vehicle is traveling on a straddle road, the estimation accuracy of the tire pressure of the drive wheel is improved by the drive wheel compensation. On the contrary, the deterioration is reliably prevented, so that the estimation accuracy of the tire pressure of the drive wheel is further improved.

According to the second aspect of the present invention, the difference between the vibration components of the wheel speeds of the left and right driven wheels is calculated, and the drive wheel estimating means corrects the left and right drive wheels when the difference exceeds the reference value. Since the tire pressures of the left and right driving wheels are estimated based on the vibration component of the preceding wheel speed, it is reliably determined whether or not the vehicle is traveling on a straddle road. The compensation surely prevents the estimation accuracy of the tire pressure of the drive wheel from deteriorating, thereby further improving the estimation accuracy of the tire pressure of the drive wheel, and further improving the estimation accuracy of the drive wheel when the vehicle runs on a straddle road. Is prevented from being estimated at all.

[0016]

[Principle of Estimating Air Pressure in the Present Invention] Prior to the description of the embodiment, first, the principle of estimating tire air pressure in the present invention, in particular, drive wheel compensation will be described.

In general, there is a resonance phenomenon on the driving wheel side that is not seen on the driven wheel side, and this peculiar resonance phenomenon is caused by front-rear resonance of the differential gear device and the suspension member and pitching resonance of the differential gear device. Yes, when the force received by the tire from the road surface is broken down into vertical force, longitudinal force, and rotational moment force, the longitudinal force excites the longitudinal resonance of the differential gear device and the suspension member, and the rotational moment force excites the pitching resonance of the differential gear device. It is thought to be.

FIG. 5 is a schematic plan view showing front-rear resonance of the suspension member, and FIG. 6 is a schematic perspective view showing pitching resonance of the differential gear device.

In these figures, 10L and 10R denote a left driving wheel and a right driving wheel, respectively. The left driving wheel 10L and the right driving wheel 10R correspond to the tires 12L and 12R and the figures for supporting the same. And wheels not shown, and are rotatably supported by wheel carriers 14L and 14R. The wheel carriers 14L and 14R are a pair of suspension arms 16L and 16R, respectively.
The drive wheels 10L and 10R are rotationally driven by a differential gear device 22 via drive shafts 20L and 20R, respectively.

According to the results of experiments conducted by the inventor of the present invention, as shown in FIGS. 5 and 6, the suspension member 18 and the differential gear device 22 are in phase.
That is, they vibrate integrally with each other, and the longitudinal resonance is generated by the suspension member 18 and the differential gear device 22 via the suspension arms 16L and 16R.
And the driving wheels 10L and 10R vibrate in opposite phases, and the pitching resonance is propagated to the left and right driving wheels 10L and 10R via the drive shafts 20L and 20R. The pitching resonances are in phase with each other.

The front-rear resonance frequency and the pitching resonance frequency fluctuate depending on the running conditions of the vehicle. This is considered to be due to the non-linear characteristics of the mount spring of the suspension member and the front-rear spring. Therefore, it is difficult to strictly model the suspension member, the differential gear device, and the like using a spring and a mass point system to compensate for the drive system resonance.

Therefore, in the present invention, attention is paid to the fact that the phase relation of the drive system resonance is the same between the left and right drive wheels, and the effect of the drive system resonance is removed by utilizing this fact.

According to the results of experiments conducted by the inventor of the present application, the front-rear resonance and the pitching resonance hardly appear in the difference between the wheel speed signals of the left and right driving wheels, which means that the front-rear resonance and the pitching resonance do not change. It means that they have the same phase and the same amplitude in between. On the other hand, since the resonance components of the tires of the left and right driving wheels are unique, they do not disappear even in the difference between the wheel speed signals of the left and right driving wheels. Therefore, by calculating the difference between the wheel speed signals of the left and right driving wheels, the influence of the drive system resonance can be compensated, and the tire air pressure free of the influence of the drive system resonance can be estimated.

As shown in FIG. 7, the left and right drive wheels 1
0L and 10R are rim side masses 10LR and 10R, respectively.
RR, belt-side masses 10LV and 10RV, and springs 10LS, 10RS and a damper 10 located therebetween.
Consider a model that is assumed to be composed of LD and 10RD, and in which rotational motion is expediently represented as linear motion.

FIG. 7 shows that L and R relate to the left driving wheel and the right driving wheel, respectively. In particular, T _OL and T _OR indicate road disturbance, and Ts indicates the suspension member 18 and the differential gear device 2.
2, the torque (right and left in-phase) received by the drive wheels due to front-rear resonance and pitching resonance, J _1L and J _1R indicate rim inertia, J _2L and J _2R indicate belt inertia, θ _1L and θ _1R
Indicates the rotational displacement of the rim (the differential value is the wheel speed), theta _2L and theta _2R shows the rotational displacement of the belt, K _L and K _R represents a spring constant of the tire, the C _L and C _R 4 shows a tire damping coefficient.

The equations of motion of the left and right driving wheels in the model shown in FIG. 7 are expressed by the following equations 1 and 2, respectively.

[0027]

(Equation 1)

(Equation 2)

The state equations of the left and right driving wheels in the model shown in FIG. 7 are expressed by the following equations (3) and (4), respectively.

[0029]

(Equation 3)

(Equation 4)

However, in Equations 3 and 4, θ
_12L = _{θ 1L -θ 2L,} a θ _12R = θ _1R -θ _2R.

When considering the left driving wheel, the dimension of the disturbance in Equation 3 is 2, but actually only the wheel speed can be detected, so that the disturbance can be estimated only in one dimension. Here, the first element of the disturbance is estimated. Spring constant K _L of a parameter is changed to K _L + [Delta] K _L, the damping coefficient C _L is C _L
Assuming that the fluctuation has changed to + ΔC _L , the estimated disturbance is represented by the following equation 5, and similarly, the estimated disturbance of the right driving wheel is represented by the following equation 6. In Equations 5 and 6, T _OL ′ and T _OR ′
Represents the influence of road disturbance.

[0032]

(Equation 5)

(Equation 6)

If a disturbance observer designed under the same conditions is used for the left and right driving wheels, the left-right in-phase relationship is maintained even in the estimated disturbance, so that the difference between the estimated disturbance and
That is, the influence of drive system resonance can be removed by the following equation (7). The rim inertia J _1L and J _{1R of the} left and right drive wheels
Assume that is known.

(Equation 7)

When Equation 7 is calculated and arranged, Equation 8 is obtained, and the term of Ts representing the in-phase component can be eliminated.

(Equation 8)

Therefore, using the equation (8) and the least squares method, the fluctuation amounts ΔK _L and ΔK _{R of} the spring constant and the fluctuation amount Δ of the damping coefficient Δ
By determining C _L and ΔC _R , it is possible to determine a tire air pressure free from the influence of drive system resonance. Equation 9 below is a calculation formula of the least squares method.

[0036]

(Equation 9)

[0037]

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 (A) and a block diagram (B) showing a first embodiment of a tire pressure estimation device according to the present invention.

In FIG. 1A, the left front wheel 30FL, the right front wheel 30FR, the left rear wheel 30RL, and the right rear wheel 30RR have respective wheel speeds Vwi (i = fl, fr, rl, rr). Wheel speed sensors 32FL, 32FR, 32RL that detect
32RR is provided. The signal indicating the wheel speed Vwi is input to the tire pressure estimation calculating device 34, which calculates the tire pressure Pi (i = fl, fr, rl, rr) of each wheel based on the wheel speed Vwi as described later. The calculation is performed by the estimation, and a control signal is output to the alarm device 36 as necessary, thereby issuing an alarm to the occupant of the vehicle.

As shown in FIG. 1B, the tire pressure estimating and calculating device 34 calculates a vibration component of the wheel speed of each wheel due to the vibration of the tire from the wheel speed signals supplied from the wheel speed sensors 32FL to 32RR. A vibration component extraction block 38 for extracting the vibration component of the wheel speed of the left and right drive wheels, a correction block 40 for obtaining a vibration component of the wheel speed of the left and right drive wheels after correction by removing those in-phase components from the vibration components of the wheel speed of the left and right drive wheels, And a drive wheel tire pressure estimation block 42 for estimating the tire pressure of the left and right drive wheels based on the vibration component of the wheel speed of the left and right drive wheels.

The tire pressure estimation calculating unit 34 determines whether or not the estimated value of the tire pressure is equal to or less than the reference value. If the estimated value is equal to or less than the reference value, the tire pressure of the corresponding wheel is abnormal. An abnormality determination block 44 for outputting a control signal indicating the following to the alarm device 36, a difference degree calculation block 46 for calculating the difference between the vibration components of the wheel speeds of the left and right driven wheels, and a drive wheel for when the difference exceeds the reference value. Estimation prohibition block 48 that prohibits the tire pressure estimation block 42 from estimating the tire pressure of the left and right driving wheels.
And

Incidentally, the tire pressure estimating arithmetic unit 34 is actually, for example, a central processing unit (CPU), a read only memory (ROM), and a random access memory (RA).
M) and an input / output port device, which may be microcomputers connected to each other by a bidirectional common bus, and this is the same for a second embodiment described later.

When the vehicle is, for example, a rear-wheel drive vehicle, the tire pressure estimation and calculation device 34 of the first embodiment calculates the tire pressures P _RL of the right and left rear wheels, which are the drive wheels, according to the flowchart shown in FIG. The _PRR is estimated to determine whether the tire pressure is abnormal. The control according to the flowchart shown in FIG. 2 is repeatedly executed at predetermined time intervals.

First, in step 10, a signal indicating the wheel speed Vwi is read, and in step 20, a pre-processing filter process is performed on each wheel speed signal, that is, at a predetermined upper and lower cutoff frequency. Bandpass filter processing is performed. In step 30, the sum of squares is calculated for the wheel speeds V _FL and V _FR of the left and right front wheels after the pre-processing filter processing in accordance with Equations 10 and 11 below. Sum-of-squares values GFL and GFR representing the magnitude of the disturbance inputted to the left and right front wheels are calculated.

[0045]

[Equation 10] GFL = ΣV _FL i · V _FL i

[Equation 11] GFR = ΣV _FR i · V _FR i

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, it is determined whether or not the sum-of-squares value GFL exceeds α · GFR, where α is a constant constant, for example, 2 or more and 7 or less. The routine proceeds to 90, and if a negative determination is made, a determination is made in step 80 as to whether or not the sum of squares GFR exceeds α · GFL. When a negative determination is made in this step, the routine proceeds to step 100, and when an affirmative determination is made, the routine returns to step 10 after the Na wheel speeds after the pre-processing filter processing are cleared in step 90.

In step 100, a process of a disturbance observer is performed. That is, the estimated disturbances w _RL and w _{RR of the} right and left rear wheels including the drive system resonance component are calculated according to the above-described equation in which L is replaced by LR in Equation 5 and the equation in which R is replaced by RR in Equation 6 above. And the torsional angles θ _12RL and θ _{12RR of} the right and left rear wheels and the torsional angular velocity θ of the tires
_12RL ( ^• ) and θ _12RR ( ^• ) are calculated. Step 11
0 in w is rewritten to w _R number 7 above based on the estimated disturbance of the left and right rear wheels at the L and R RL, respectively
And RR, the estimated disturbance w _R from which the influence of the drive system resonance has been removed is calculated.

In step 120, the estimated disturbance w _R ,
Based on the torsional angles θ _12RL and θ _{12RR of} the tire and the torsional angular _speeds θ _12RL ( ^• ) and θ _12RR ( ^• ) of the tire, the spring constants of the right and left rear tires are changed by the least squares method according to the equation corresponding to the above _equation (9). The amounts ΔK _RL and ΔK _RR and the fluctuation amounts ΔC _RL and ΔC _{RR of the} damping coefficient are calculated.

In step 130, j is incremented by one, and in step 140, j is set to the reference value Nb.
(A positive integer of about 100 to 10) is determined, and if a negative determination is made, step 1 is performed.
Go to step 70, and if a positive determination is made, step 15
Step 160 after j is reset to 0 at 0
Tire pressure P _RL and P _RR of the left and right rear wheels, respectively on the basis of the variation amount of the variation amount and the damping coefficient of the spring constant of the Na · Nb pieces of tire In is calculated.

In step 170, it is determined whether or not the tire pressures _PRL and _PRR of the right and left rear wheels are equal to or higher than a reference value. Returning to 10, tire pressure P
Alarm device 3 when _RL or P _RR is less than the reference value
When the control signal is output to 6, a warning is issued to the driver that the tire air pressure of the corresponding wheel is abnormal, and then the process returns to step 10.

As understood from the above description, step 10,
The function of the vibration component extraction block 38 in FIG. 1B is achieved by 20 and 100, the function of the correction block 40 is achieved by step 110, and the function of the tire pressure estimation block 42 for driving wheels is achieved by steps 120 to 160. Then, the function of the abnormality determination block 44 is achieved by step 170. Further, the functions of the difference degree calculation block 46 are achieved by steps 30 to 80, and
Thus, the function of the estimation prohibition block 48 is achieved.

Thus, according to the first embodiment, in step 30, the sum of squared products GFR and GFR representing the magnitude of the disturbance inputted to the left and right front wheels from the road surface are calculated, and in step 70 or 80, When a positive determination is made,
That is, when the difference between the magnitudes of the disturbances inputted to the left and right front wheels from the road surface is large within the time of the Na cycle in the flowchart shown in FIG. 2, steps 100 to 170 are not executed and the process proceeds to step 90. Since the Na wheel speeds after the processing filter processing are cleared and the tire pressures of the right and left rear wheels are not estimated and the abnormality determination is not performed, the magnitude of the disturbance inputted to the right and left rear wheels from the road surface is greatly different. Thus, it is possible to reliably prevent the tire pressure from being erroneously estimated to be a low value due to the drive wheel compensation being performed.

Further, according to this embodiment, the number of wheel speeds cleared in step 90 in the situation where the magnitude of the difference in the magnitude of the disturbance inputted to the left and right front wheels from the road surface within a predetermined time is Na is The wheel speed detected when the degree of the difference in the magnitude of the disturbance inputted to the left and right front wheels is small is effectively used for the calculation of the tire pressure. The tire pressure can be estimated more efficiently than when all wheel speeds are cleared.

Second Embodiment FIG. 3 is a block diagram of a second embodiment of the tire pressure estimation device according to the present invention, and FIG. 4 is a flowchart showing a tire pressure estimation routine in the second embodiment.
In FIG. 3, members corresponding to those shown in FIG. 1 (B) are given the same reference numerals as those shown in FIG. 1 (B), and in FIG. Steps corresponding to the steps shown in FIG. 2 are given the same step numbers as those given in FIG.

The tire air pressure estimating operation device 34 of this embodiment has a drive wheel compensation prohibition block 50 instead of the estimation prohibition block 48.
When the difference between the vibration components of the wheel speeds of the left and right driven wheels calculated by the difference calculation block 46 exceeds the reference value, the driving wheels in the tire pressure estimation block 42 for the right and left driving wheels are estimated by the driving wheel tire pressure estimation block 42. Prohibit compensation.

Steps other than step 95 of this embodiment are executed in the same manner as in the first embodiment, and if an affirmative determination is made in step 70 or 80, the first step is executed in step 95. By performing the same disturbance observer processing as in step 100 in the embodiment, signals indicating estimated disturbances w _RL and w _RR including resonance components of the suspension members and the like, the torsion angle θ _12RL of the tires of the left and right driving wheels, The variation of the spring constant and the variation of the damping coefficient are calculated based on the signal indicating θ _12RR and the torsional angular velocities θ _12RL ( ^• ) and θ _12RR ( ^• ) of the tire, and then the drive system resonance compensation is calculated (step 110). ) Is not performed, and the process proceeds to step 120.

Therefore, in this embodiment, the functions of the vibration component extraction block 38 of FIG. 3 are achieved by steps 10, 20, and 100, as in the first embodiment.
The function of the correction block 40 is achieved by step 110, and the function of the drive wheel tire pressure estimation block 42 is achieved by steps 120 to 160, and step 170
Thus, the function of the abnormality determination block 44 is achieved. The functions of the difference degree calculation block 46 are achieved by steps 30 to 80, and the function of the drive wheel compensation prohibition block 50 is achieved by step 95.

Thus, according to the second embodiment, in step 30, the sum of squares GFL and GFR representing the magnitude of the disturbance inputted to the left and right front wheels from the road surface are calculated, and in step 70 or 80, When a positive determination is made,
That is, when the difference between the magnitudes of the disturbances inputted to the left and right front wheels from the road surface is large within the time of the Na cycle in the flowchart shown in FIG. 4, steps 100 and 110 are not executed but step 95 is executed. Only the processing of the disturbance observer is performed, and the steps 120 to 170 are executed without performing the driving wheel compensation. Therefore, the driving is performed in a situation where the magnitude of the disturbance inputted to the right and left rear wheels from the road surface is largely different. It is possible to reliably prevent the tire pressure from being erroneously estimated to be a low value due to the wheel compensation being performed.

Further, according to this embodiment, even in a situation where the magnitude of the magnitude of the disturbance inputted to the left and right front wheels from the road surface within a predetermined time is large, the disturbance observer is processed in step 95. After that, steps 120 to 170 are executed, so that when the vehicle runs on a straddle road as in the case of the first embodiment in which the Na wheel speeds after the pre-processing filter processing are cleared. It is possible to reliably prevent the tire pressure of the wheel from being estimated at all.

In the first and second embodiments described above, only the tire pressures of the left and right rear wheels, which are the driving wheels, are estimated. In step 120, the disturbance observer is also processed for the left and right front wheels that are driven wheels.
In the left and right front wheels, the variation amounts ΔK _FL and ΔK _FR of the spring constants of the tires of the left and right front wheels and the variation amount Δ of the damping coefficient
By calculating C _FL and ΔC _FR , the tire air pressure may be estimated for the left and right front wheels in steps 160 and 170, respectively, and the abnormality determination may be performed.

In each of the above-described embodiments, the magnitude of the disturbance inputted to the left and right front wheels within a predetermined time is determined in step 3
0 is calculated as the sum of squared products according to Equations 10 and 11, but if the disturbance observer process is performed on the left and right front wheels as described above, the magnitude of this disturbance is It may be calculated as the sum of the squares of the disturbances w _FL and w _FR after the disturbance observer processing calculated in 100 or 95, and if sign X is the sign of the variable X, the calculation is performed according to the following equation (12) or (13). May be done.

[0063]

[Equation 12] GFL = ΣV _FL · signV _FL GFR = ΣV _FR · signV _FR

[Expression 13] GFL = Σw _FL · signw _FL GFR = Σw _FR · signw _FR

Further, in each of the above-described embodiments, whether or not the difference between the vibration components of the wheel speeds of the left and right driven wheels exceeds a quasi-value is determined by the disturbance input to the left and right front wheels within a predetermined time. The determination is made based on whether one of the magnitudes GFL and GFR exceeds α times the other. For example, the determination is made based on whether the absolute value of the deviation between GFL and GFR exceeds a reference value. May be done.

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 are included within the scope of the present invention. It will be clear to those skilled in the art that is possible.

For example, each of the above embodiments is an embodiment applied to a rear wheel drive vehicle. However, when the vehicle is a front wheel drive vehicle, the front wheels and rear wheels of the above embodiments are replaced with each other. The present invention is implemented in the form described above. That is, by executing step 30 for the left and right rear wheels, the sum of squares GRL and GRR of the left and right rear wheels that are driven wheels are calculated, and steps 70 and 80 are executed for these sums of squares GRL and GRR. Steps 90 to 170 or steps 95 to 170 are executed for the left and right front wheels that are the driving wheels.

[0067]

As is apparent from the above description, according to the structure of the first aspect, when the vehicle travels on a road surface other than a straddle road, the left and right drive wheels are not affected by the drive system resonance. The tire air pressure of the left and right driven wheels can be accurately estimated, and the difference between the vibration components of the wheel speeds of the left and right driven wheels is calculated. When the difference exceeds the reference value, the tire air pressure of the left and right driven wheels is estimated by the drive wheel estimating means. Estimation is prohibited, so it is reliably determined whether or not the vehicle is traveling on a straddle road, and when the vehicle is traveling on a straddle road, the accuracy of estimating the tire pressure of the drive wheel is rather deteriorated by the drive wheel compensation. Therefore, the estimation accuracy of the tire pressure of the drive wheel can be further improved.

According to the second aspect of the invention, when the vehicle travels on a road surface other than a stride road, the tire pressures of the left and right driving wheels can be accurately estimated without being affected by the drive system resonance. Further, the degree of difference between the vibration components of the wheel speeds of the left and right driven wheels is calculated. Since the air pressure is estimated, it is reliably determined whether the vehicle is traveling on a straddle road, and when the vehicle is traveling on a straddle road, the estimation accuracy of the tire pressure of the drive wheel is rather deteriorated by the drive wheel compensation. This reliably prevents the tire pressure of the drive wheels from being further improved, and the tire pressure of the drive wheels is not estimated at all when the vehicle travels on a straddle road. It is possible to avoid the Rukoto.

[Brief description of the drawings]

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

FIG. 2 is a flowchart illustrating a tire pressure estimation and determination routine according to the first embodiment.

FIG. 3 is a block diagram showing a second embodiment of the tire pressure estimation device according to the present invention.

FIG. 4 is a flowchart illustrating a tire air pressure estimation and determination routine according to a second embodiment.

FIG. 5 is an illustrative plan view showing front-rear resonance of a suspension member.

FIG. 6 is an illustrative perspective view showing pitching resonance of the differential gear device.

FIG. 7 is an explanatory diagram showing a vibration model of left and right drive wheels.

[Explanation of symbols]

 32FL-32RR ... Wheel speed sensor 34 ... Tire pressure estimation calculation device 36 ... Warning device 38 ... Vibration component extraction block 40 ... Correction block 42 ... Driving wheel tire pressure estimation block 44 ... Abnormality determination block 46 ... Difference degree calculation block 48 ... Estimation prohibition block 50: Driving wheel compensation prohibition block

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hideki Ohashi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Hiroyuki Kawai 1 Toyota Town Toyota City, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Hiroyoshi Kojima 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (72) Inventor Koji Umeno 41 Toyota Chuo R & D Laboratories Co., Ltd. Kenji Tomiita 1-1-1, Showa-cho, Kariya-shi, Aichi Prefecture Inside Denso Corporation (72) Inventor Taguchi Health 1-1-1, Showa-cho, Kariya City, Aichi Prefecture Inside DENSO Corporation

Claims (2)

[Claims] A wheel speed detecting means for detecting a wheel speed of each wheel; a vibration component extracting means for extracting a vibration component of a wheel speed of each wheel caused by a tire vibration from a wheel speed signal of each wheel; Correcting means for obtaining a corrected wheel speed vibration component of the left and right drive wheels by removing those in-phase components from the wheel speed vibration components of the drive wheels; and A tire pressure estimating device having driving wheel estimating means for estimating a tire pressure of a driving wheel, comprising: means for calculating a degree of difference between vibration components of wheel speeds of left and right driven wheels, wherein the degree of difference is a reference value. A tire pressure estimation device for prohibiting the estimation of the tire air pressure of the left and right driving wheels by the driving wheel estimation means when the vehicle pressure exceeds the threshold value. 2. A wheel speed detecting means for detecting a wheel speed of each wheel, a vibration component extracting means for extracting a vibration component of a wheel speed of each wheel caused by a tire vibration from a wheel speed signal of each wheel, Correcting means for obtaining a corrected wheel speed vibration component of the left and right drive wheels by removing those in-phase components from the wheel speed vibration components of the drive wheels; and A driving wheel estimating device having a driving wheel estimating means for estimating a driving wheel tire pressure, comprising: means for calculating a degree of difference between vibration components of wheel speeds of left and right driven wheels; A tire pressure estimating device for estimating the tire pressure of the left and right drive wheels based on a vibration component of the wheel speed before correction of the left and right drive wheels when the degree of difference exceeds a reference value.