JPH06286597A - Control device for vehicle - Google Patents

Abstract

PURPOSE:To provide a control device for vehicle which judges air pressure drop of tires and performs antiskid control suitable for the air pressure drop condition. CONSTITUTION:This control device is provided with a first-a third valve units 20, 21, 23 to control the brake oil pressure of brake devices 11, 12, 13, 14 of four wheels of an automobile, and a control unit 24 for ABS control to perform antiskid control of the brake devices 11, 12, 13, 14 through the first the third valve units, based on the detected signals from wheel speed sensors 27, 28, 29, 30 to detect the wheel speed of the four wheels. A control unit 40 to judge the air pressure of tires based on the detected signals from the wheel speed sensors 27, 28, 29, 30 is provided, and when the air pressure of tires are judged to be lowered, the brake oil pressure are controlled in the direction of mitigating lock or in the direction of strengthening lock by means of a control unit 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control device, and more particularly to a vehicle equipped with an anti-skid brake device and a tire air pressure determination device, which has improved control of brake oil pressure when tire air pressure decreases.

[0002]

2. Description of the Related Art As a vehicle braking system, an anti-skid braking device has been put into practical use which prevents the wheel from locking or skiding during braking. This type of anti-skid brake device controls a wheel speed sensor that detects the wheel speed of four wheels, an electromagnetic control valve that adjusts the brake hydraulic pressure, and an electromagnetic control valve based on the wheel speed detected by the wheel speed sensor. And a control device. This control device, for example, obtains the acceleration / deceleration of the wheel based on the detected wheel speed,
When the wheel deceleration falls below a predetermined value, the electromagnetic control valve is pressure-reduced to reduce the braking pressure, and when the wheel speed increases due to the reduction of the braking pressure and the wheel acceleration reaches a predetermined value, the control valve The braking pressure is increased by controlling the pressure increase. Such a series of braking pressure control (hereinafter, A
(BS control) is continued until the vehicle stops, for example, to prevent the wheels from being locked or skided during sudden braking, so that the vehicle can be stopped at a short braking distance while ensuring directional stability. Becomes

On the other hand, it is not preferable to drive the vehicle with the tire air pressure lowered to a certain extent or more. Therefore, various tire air pressure determination devices have been conventionally proposed. For example, the tire pressure is detected by a sensor to determine a decrease in the tire pressure, or when the tire pressure decreases, the number of rotations of the wheel whose pressure has decreased decreases. It has been proposed that a wheel speed sensor for detecting is provided and a decrease in tire air pressure is determined based on the wheel speed detected by these wheel speed sensors.

For example, in Japanese Laid-Open Patent Publication No. 63-305011, the outputs from the wheel speed sensors of the four wheels are used to calculate the total wheel speed of a pair of wheels on the diagonal line and the other wheel on the other diagonal line. When the difference between the total wheel speed of a pair of wheels is greater than or equal to a predetermined value, it is determined that the tire pressure of any one of the pair of wheels with the larger total wheel speed has decreased, and When the larger one of the wheel speeds of the wheels is higher than the average value of the wheel speeds of the four wheels by a predetermined value or more, it is determined that the air pressure of the wheel has decreased, and the determination result is warned. A configured tire pressure determination device is described.

[0005]

When the tire air pressure of the vehicle is reduced, the frictional force acting on the tire is increased and the load on the tire is increased, or the grip force of the tire is decreased and the braking force is decreased. However, since the conventional anti-skid brake device and the tire air pressure determination device are configured to control each other independently, there is a problem that anti-skid control suitable for reducing tire air pressure cannot be performed. For example, when the tire air pressure is low, the grip force of the wheel whose air pressure is low is reduced, so that the running stability is reduced, and the tire whose pressure is reduced is significantly worn, resulting in a decrease in tire reliability. An object of the present invention is to provide a vehicle control device capable of performing anti-skid control suitable for reducing the tire pressure when the tire pressure is reduced.

[0006]

A vehicle control device according to a first aspect of the present invention is an anti-skid brake device having anti-skid control means for controlling brake hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting means. In a vehicle including a tire air pressure determination device that detects a decrease in tire air pressure of a wheel, the anti-skid control means receives a signal indicating a tire air pressure reduction from the tire air pressure determination device and locks the brake hydraulic pressure in a locking relaxation direction. It is provided with a hydraulic pressure correction means.

Here, the tire air pressure determination device includes an abnormal wheel detection means for detecting a wheel whose tire air pressure has dropped, and the oil pressure correction means uses the abnormal wheel detection means to specify a signal for specifying a wheel whose tire air pressure has dropped. In response to this, the brake hydraulic pressure of the wheel whose tire air pressure has dropped is corrected in the lock reducing direction (claim 2), and the hydraulic pressure correction means corrects only the brake hydraulic pressure of the left and right rear wheels in the lock reducing direction. (Claim 3), the hydraulic pressure correcting means corrects the brake hydraulic pressure of the rear wheels in the direction of lock relaxation more than the brake hydraulic pressure of the front wheels (Claim 4), the anti-skid control The means includes a frictional state detection means for detecting a frictional state of the road surface, and the hydraulic pressure correction means is provided when the frictional state detection means detects the road surface frictional state as a high frictional state. , Structure which is adapted to correct the brake pressure (claim 5), can be configured to equal the various aspects.

According to a sixth aspect of the present invention, there is provided an anti-skid brake device having anti-skid control means for controlling the brake hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting means, and a tire air pressure of the wheel. In a vehicle equipped with a tire air pressure determination device for detecting a decrease in the vehicle tire pressure, the anti-skid control means receives a signal indicating a tire air pressure reduction from the tire air pressure determination device and corrects the brake oil pressure in the lock strengthening direction. It is equipped with.

Here, the tire air pressure determination device includes an abnormal wheel detection means for detecting a wheel whose tire air pressure has dropped, and the hydraulic pressure correction means specifies a wheel whose tire air pressure has dropped from the abnormal wheel detection means. In response to the signal, the brake hydraulic pressure of the wheel whose tire pressure has dropped is corrected in the lock strengthening direction (claim 7), and the hydraulic pressure correcting means corrects only the brake hydraulic pressure of the left and right front wheels in the lock strengthening direction. According to the structure (claim 8), the anti-skid control means includes a frictional state detection means for detecting a frictional state of the road surface, and the hydraulic pressure correction means uses the frictional state detection means to detect a high frictional state of the road surface. The present invention can be configured in various modes such as a configuration in which the brake hydraulic pressure is corrected only when it is detected (claim 9).

[0010]

In the vehicle control device according to the present invention, the antiskid control means of the antiskid brake device controls the brake hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting means, The tire pressure determination device detects a decrease in tire pressure of a wheel. The oil pressure correction means provided in the anti-skid control means receives a signal indicating a decrease in tire air pressure from the tire air pressure determination device, and corrects the brake oil pressure in the lock relaxation direction. When the tire air pressure decreases, the frictional force of the tire whose air pressure has decreased increases and the load on the tire increases,
By correcting the brake hydraulic pressure in the lock relaxation direction, it is possible to reduce the load on the tire, suppress the wear of the tire, and prevent the reliability of the tire from decreasing.

According to the second aspect of the present invention, since the hydraulic pressure correction means corrects the brake hydraulic pressure of the wheel whose tire pressure has dropped in the direction of the lock relief, it is possible to suppress wear of the tire whose pneumatic pressure has dropped. In claim 3, the hydraulic pressure correction means corrects only the brake hydraulic pressures of the left and right rear wheels in the lock relaxation direction. Therefore, when the tire air pressure is reduced, the running stability is reduced due to the reduction of the braking force and the imbalance of the braking force. Can be suppressed. According to the fourth aspect, the hydraulic pressure correcting means corrects the brake hydraulic pressure of the rear wheels in the lock relaxation direction more than the brake hydraulic pressure of the front wheels. Therefore, the same action and effect as in the third aspect can be obtained. In the present invention, the hydraulic pressure correction means corrects the brake hydraulic pressure only when the frictional state detection means detects that the road surface frictional state is a high frictional state. Therefore, tire damage and running stability in the case of a high frictional road surface The decrease can be surely suppressed.

According to another aspect of the vehicle control device of the present invention, the anti-skid control means of the anti-skid brake device controls the brake hydraulic pressure adjusting means on the basis of the wheel speed detected by the wheel speed detecting means, and the tire air pressure determining device. Detects a decrease in tire air pressure on a wheel. The oil pressure correction means provided in the anti-skid control means receives a signal indicating a decrease in tire air pressure from the tire air pressure determination device, and corrects the brake oil pressure in the lock strengthening direction. When the tire pressure decreases, the frictional force of the tire increases and it becomes difficult to lock. Therefore, by correcting the brake hydraulic pressure in the lock strengthening direction, it is possible to prevent the tire grip force from decreasing and prevent the braking performance from decreasing. .

According to the seventh aspect of the present invention, the hydraulic pressure correcting means corrects the brake hydraulic pressure of the wheel whose tire air pressure has decreased in the lock strengthening direction, so that it is possible to prevent the reduction of the grip force of the wheel whose tire air pressure has decreased. In claim 8, the hydraulic pressure correction means corrects only the brake hydraulic pressure of the left and right front wheels in the lock strengthening direction, so that a decrease in braking force is suppressed.
At the same time, it is possible to prevent deterioration of running stability. In claim 9,
The hydraulic pressure correction means corrects the brake hydraulic pressure only when the frictional state detection means detects the road surface frictional state as a high frictional state, so that it is possible to suppress a decrease in braking force and ensure traveling stability.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is an example of the case where the present invention is applied to an anti-skid brake device and a tire pressure determination device for a rear-wheel-drive vehicle for riding. First, the anti-skid brake device will be described with reference to FIGS. 1 to 11. As shown in Fig. 1, in this vehicle, the left and right front wheels 1 and 2 are driven wheels, and the left and right rear wheels 3 and 4 are drive wheels, and the output torque of the engine 5 is from the automatic transmission 6 to the propeller shaft 7 to the differential gear. It is transmitted to the left and right rear wheels 3, 4 via the device 8 and the left and right drive shafts 9, 10. Each of the wheels 1 to 4 includes a disc 11a to 14a that rotates integrally with the wheel, and a braking device 11b that includes a caliper 11b to 14b that receives the supply of a braking pressure to brake the rotation of the disc 11a to 14a. 14 are provided respectively, and a brake control system 15 for operating these braking devices 11-14 is provided.

The brake control system 15 includes a booster device 17 for increasing the stepping force on the brake pedal 16 by the driver.
And a master shilling 18 for generating a braking pressure according to the stepping force increased by the booster 17. Front wheel braking pressure supply line 19 from this master shilling 18
Is branched into two routes, and the front wheel branch braking pressure line 19
a, 19b are connected to the calipers 11a, 12a of the brake devices 11, 12 of the left and right front wheels 1, 2 respectively, and the brake device 11 of the left front wheel 1 is connected.
One branch brake pressure line 19a for the front wheel, which is connected to, is provided with a first valve unit 20, which includes an electromagnetic on-off valve 20a and an electromagnetic relief valve 20b, which leads to the braking device 12 for the right front wheel 2. Branch braking pressure line 19 for the other front wheel
Similarly to the first valve unit 20, a second valve unit 21 including an electromagnetic on-off valve 21a and an electromagnetic relief valve 21b is also provided at b.

On the other hand, the rear wheel braking pressure supply line 22 from the master cylinder 18 is connected to the first and second valve units 20, 2.
As in the case of 1, a third valve unit 23 including an electromagnetic on-off valve 23a and an electromagnetic relief valve 23b is provided. The rear wheel braking pressure supply line 22 is branched into two paths on the downstream side of the third valve unit 23, and the rear wheel branch braking pressure lines 22a and 22b are connected to the brake devices 13 of the left and right rear wheels 3 and 4. , 14 calipers 13b, 14b are connected respectively. The brake control system 15 includes a first channel that variably controls the braking pressure of the braking device 11 for the left front wheel 1 via the first valve unit 20, and a braking device 12 for the right front wheel 2 via the second valve unit 21. Via the second channel that variably controls the braking pressure and the third valve unit 23, the left and right rear wheels
A third channel for variably controlling the braking pressure of both the braking devices 3, 14 is provided, and the first to third channels are controlled independently of each other.

The brake control system 15 includes the first to
A control unit 24 for controlling the third channel is provided. The control unit 24 includes a brake signal from a brake switch 25 for detecting ON / OFF of the brake pedal 16 and a steering angle sensor 26 for detecting a steering angle θ. Of the wheel speed signals from the wheel speed sensors 27 to 30 that detect the rotational speeds of the four wheels, and the braking pressure control signals corresponding to these signals are sent to the first to third valve units.
By outputting to 20,21,23 respectively, braking control for slips of the left and right front wheels 1,2 and rear wheels 3,4, that is, AB
The S control is performed in parallel for each of the first to third channels.

The control unit 24 controls the opening / closing valves 20a, 21a, 23a and the relief valves 20b, 21b in the first to third valve units 20, 21, 23 based on the wheel speeds detected by the wheel speed sensors 27-30. , 23b are controlled by duty control to open / close respectively, and the front wheels 1, 2 and the rear wheels 3, 2 are controlled by the braking pressure according to the slip condition.
Braking force is applied to 4. In addition, first to
Each relief valve 20b in the third valve unit 20, 21, 23
The brake oil discharged from 21b and 23b is returned to the reservoir tank 18a of the master cylinder 18 via a drain line (not shown).

In the ABS non-controlled state, no braking pressure control signal is output from the control unit 24, and the relief valves 20b, 21b and 23b in the first to third valve units 20, 21 and 23 are respectively, as shown in the figure. Since the valves are held closed and the on-off valves 20a, 21a, 23a of the units 20, 21, 23 are kept open, respectively, the braking pressure generated in the master cylinder 18 in response to the stepping force of the brake pedal 16 is applied to the front wheel braking. The left and right front wheels 1 and 2 via the pressure supply line 19 and the rear wheel braking pressure supply line 22.
Also, the braking force is supplied to the braking devices 11 to 14 of the rear wheels 3 and 4, and the braking force corresponding to these braking pressures is directly applied to the front wheels 1 and 2 and the rear wheels 3 and 4.

Next, an outline of the brake control performed by the control unit 24 will be described. Control unit 24
Are wheel speeds Vw1 to Vw4 detected by the wheel speed sensors 27 to 30.
Based on the above, the decelerations DVw1 to DVw4 and the accelerations AVw1 to AVw4 for the respective wheels are calculated. In this case, the difference between the previous value of the wheel speed and the current value is calculated as the sampling cycle Δt.
After dividing by (for example, 8 ms), a value obtained by converting the result into gravitational acceleration is updated as the current acceleration or deceleration.

Further, the control unit 24 executes a predetermined rough road judgment processing to judge whether or not the traveling road surface is a bad road. This rough road determination processing is executed as follows. For example, if the number of times the deceleration or acceleration of the rear wheels 3, 4 exceeds a predetermined upper limit value or lower limit value within a certain time is within a set value, the rough road flag Fak is maintained at 0, and if it is more than the set value. For example, the rough road flag Fak is set to 1 because the traveling road surface is a bad road. Further, the control unit 24 selects the rear wheels 3 and 4 which represent the wheel speed and acceleration / deceleration for the third channel, but the detection error of both wheel speed sensors 29 and 30 of the rear wheels 3 and 4 at the time of slip is selected. Considering this, the smaller wheel speed of the two wheel speeds is selected as the rear wheel speed, and the acceleration and deceleration obtained from the wheel speed are selected as the rear wheel acceleration and the rear wheel deceleration.

Furthermore, the control unit 24 estimates the road surface friction coefficient for each channel, calculates the pseudo vehicle body speed in parallel with it, calculates the wheel speeds of the left and right front wheels 1 and 2, the pseudo vehicle body speed, and the rear wheel wheels. The slip ratios corresponding to the first to third channels are calculated from the speed and the pseudo vehicle speed, respectively, and the slip ratio is calculated by the following relational expression. Slip rate = (wheel speed / pseudo vehicle speed) × 100 Therefore, as the deviation of the wheel speed from the pseudo vehicle speed increases, the slip rate decreases, and the slip tendency of the wheel increases.

Next, the control unit 24 includes
Various control threshold values used for controlling the third channel are set, and the lock determination processing for each channel is performed using these control threshold values, and the first to third valve units 2
Phase determination processing for defining control amounts for 0, 21, and 23 and cascade determination processing are performed. Here, regarding the lock determination process, for example, in the lock determination process for the first channel for the left front wheel, the current value of the continuation flag Fcn1 for the first channel is set as the previous value, and then the pseudo vehicle speed is set. It is determined whether Vr and the wheel speed Vw1 satisfy predetermined conditions (for example, Vr <5Km / H, Vw1 <7.5Km / H), and when these conditions are satisfied, the continuation flag Fcn1 and the lock The flags Flok1 are reset to 0, respectively, and if they are not satisfied, the lock flag Flok1 is reset.
Is set to 1 or not.

If the lock flag Flok1 is not set to 1, the lock flag Flok1 is set to 1 under a predetermined condition (for example, when the pseudo vehicle body speed Vr is higher than the wheel speed Vw1).
Set. On the other hand, when it is determined that the lock flag Flok1 is set to 1, for example, the phase value P1 of the first channel is set to 5 indicating the phase V,
When the slip ratio S1 is larger than 90%, the continuation flag Fcn1 is set to 1. The lock determination process is similarly performed for the second and third channels.

The outline of the phase determination processing will be described. Phase 0 indicating the ABS non-controlled state is obtained by comparing the respective control threshold values set according to the running state of the vehicle with the wheel acceleration / deceleration and the slip ratio. Phase I indicating the increased pressure state during ABS control, Phase II indicating the maintained state after increasing pressure, Phase III indicating the reduced pressure state, Phase IV indicating the rapid reduced pressure state and Phase V indicating the retained state after the reduced pressure are selected. It is configured to.

In the cascade determination process, the wheels are easily locked even with a small braking pressure, especially on a low friction road surface such as an ice burn. Therefore, the cascade locked state in which the wheels are continuously locked in a short time is determined. The cascade flag Fcs is set to 1 when a predetermined condition in which cascade lock is likely to occur is satisfied. In this way, the control unit 24 sets a control amount according to the phase value P1 set for each channel, and sends a braking pressure control signal according to the control amount to the first to third valve units 20, 21, 23. Output to each. With this,
Front wheel branch braking pressure lines 19a, 19b and rear wheel branch braking pressure lines on the downstream side of the third valve unit 20, 21, 23
The braking pressure of 22a, 22b is increased or decreased, or is maintained at the pressure level after the increased or decreased pressure.

The road surface friction coefficient estimation process is performed, for example, by
The first channel is performed as follows based on the flowchart of FIG. In the figure, the reference numeral Si (i = 1,
2, 3, ...) Show each step. Various data is read (S1), then ABS flag F
It is determined whether abs is set to 1 (that is, whether ABS control is in progress) (S2). This ABS flag F
abs is set to 1 when any of the lock flags Flok1, Flok2, and Flok3 of the first to third channels is set to 1, and the brake switch 25 is turned on.
It is reset to 0 when switching to the OFF state. When it is determined that the ABS flag Fabs is not set to 1, the friction coefficient value Mu1 is determined in S3.
Is set to 3 indicating a high friction road surface.

When it is determined in S2 that the ABS flag Fabs is set to 1, that is, when the ABS control is being performed, it is determined in S4 whether the wheel deceleration DVw1 in the previous cycle is smaller than -20G. If the result of the determination is Yes, it is determined in S5 whether or not the wheel acceleration AVw1 in the previous cycle is greater than 10 G. If the result of the determination is No, the friction coefficient value Mu1 is set in S6 to determine the low friction road surface. Set 1 as shown. On the other hand, when it is determined in S4 that the wheel deceleration DVw1 is not smaller than -20G, the process skips S5 and proceeds to S7, where it is determined whether the wheel acceleration AVw1 is greater than 20G, and the result of the determination is Yes. At some times, 3 is set as the friction coefficient value Mu1, while when it is determined to be No, at S9, 2 indicating the medium friction road surface is set as the friction coefficient value Mu1. The road friction coefficient is similarly estimated for the second and third channels.

Next, the calculation process of the pseudo vehicle body speed Vr will be described with reference to the flowchart of FIG. First,
Various data is read (S20), then sensors 27-30
The maximum wheel speed Vwm is calculated from among the wheel speeds Vw1 to Vw4 indicated by the signal from (S21), and the maximum wheel speed change amount ΔVwm per sampling cycle Δt of the maximum wheel speed Vwm is calculated (S22). Next, in S23, the vehicle speed correction value CVr corresponding to the representative friction coefficient value Mu (minimum value of the first to third channels) is read from the map shown in FIG.
In S24, the maximum wheel speed change amount ΔVwm is the vehicle body speed correction value CV.
It is determined whether or not r or less.

As a result of the determination, when the wheel speed change amount ΔVwm is equal to or less than the vehicle body speed correction value CVr, the value obtained by subtracting the vehicle body speed correction value CVr from the previous value of the pseudo vehicle body speed Vr is replaced with the current value in S25. Therefore, the pseudo vehicle body speed Vr decreases at a predetermined gradient according to the vehicle body speed correction value CVr. On the other hand, when it is determined in S24 that the wheel speed change amount ΔVwm is larger than the vehicle body speed correction value CVr, that is, when the maximum wheel speed Vwm shows an excessive change, the maximum wheel speed Vwm is subtracted from the pseudo vehicle body speed Vr in S26. It is determined whether the value is greater than or equal to the predetermined value V0. That is, the maximum wheel speed V
It is determined whether or not there is a large difference between wm and the pseudo vehicle body speed Vr. If there is no large difference, the value obtained by subtracting the vehicle body speed correction value CVr from the previous value of the pseudo vehicle body speed Vr is replaced with the current value in S27. .

Further, when there is a large difference between the maximum wheel speed Vwm and the pseudo vehicle body speed Vr, the control unit 24 replaces the maximum wheel speed Vwm with the pseudo vehicle body speed Vr in S27. In this way, the pseudo vehicle body speed Vr of the vehicle is updated every sampling period Δt according to the wheel speeds Vw1 to Vw4.

Next, the process of setting various control threshold values will be described with reference to the flowchart of FIG. The control threshold setting process is executed independently for each channel. Here, the control threshold setting process for the first channel for the left front wheel will be described. S31
Various data is read in, and then in S32,
As shown in FIG. 6, a traveling state parameter corresponding to the representative friction coefficient value Mu obtained from the wheel speeds Vw1 to Vw4 and the pseudo vehicle body speed Vr is selected from a table preset with the vehicle speed range and the road surface friction coefficient as parameters. . Here, the minimum value of the friction coefficient values Mu1 to Mu3 of the first to third channels is used as the representative friction coefficient value Mu. For example, when the representative friction coefficient value Mu is 1 indicating the low friction road surface and the pseudo vehicle body speed Vr belongs to the medium speed range, the LM2 for the medium speed low friction road surface is selected as the traveling state parameter.

When the bad road flag Fak is 1 indicating the bad road condition, as shown in FIG. 6, a running condition parameter corresponding to the pseudo vehicle speed Vr is selected. In this case, for example, when the pseudo vehicle body speed Vr belongs to the medium speed range, the HM2 for the medium speed and low friction road surface is forcibly selected as the traveling state parameter. This is because the road surface friction coefficient tends to be estimated to be small because the wheel speed fluctuates greatly when the vehicle runs on a rough road.

After selecting the running condition parameters, various control threshold values corresponding to the running condition parameters are read out from the control threshold value setting table shown in FIG. 7 in S32. Here, as various control threshold values, as shown in FIG. 7, a threshold value for switching from phase I to phase II is determined.
1-2 Intermediate deceleration threshold B12, Phase II to Phase
2-3 Intermediate slip ratio threshold value Bs for switching to III
g, 3-5 for judging switching from phase III to phase V
An intermediate deceleration threshold value B35, a 5-1 slip ratio threshold value Bsz for determining whether to switch from phase V to phase I, and the like are set for each running state parameter.

In this case, the deceleration threshold value that greatly influences the braking force is set so that the braking performance when the road surface friction coefficient is large and the control response when the road surface friction coefficient is small are compatible with each other at a high level. , As the level of the representative friction coefficient value Mu decreases, that is, as the road surface friction coefficient decreases, 0
It is set to approach G. Here, when LM2 for medium speed / low friction road surface is selected as the traveling state parameter, L in the control threshold setting table of FIG. 7 is selected.
As shown in the column of M2, 1-2 intermediate deceleration threshold B12,
2-3 as an intermediate slip ratio threshold Bsg, 3-5 as an intermediate deceleration threshold B35 and 5-1 slip ratio threshold Bsz as −0.
The respective values of 5G, 90%, 0G and 90% are read out respectively.

Next, in S33, the representative friction coefficient value M
It is determined whether u is set to 3, which indicates a high friction road surface. If Yes, it is determined whether the bad road flag Fak is set to 1 in S34. Bad road flag F
If ak is not 1, the process proceeds to S35, in which it is determined whether the absolute value of the steering angle θ indicated by the steering angle signal is smaller than 90 °. If the absolute value of the steering angle θ is not smaller than 90 °, S36 is executed. At, the control threshold value is corrected according to the steering angle θ. This control threshold correction processing is executed based on the control threshold correction table illustrated in FIG.

In the control threshold value correction table of FIG. 8, in order to ensure the steerability when the steering wheel operation amount is large,
2-3 The values obtained by adding 5% to the intermediate slip ratio threshold Bsg and 5-1 intermediate slip ratio threshold Bsz are the final 1-
2 Slip rate threshold value Bsg and final 5-1 slip rate threshold value Bsz are set, and other intermediate threshold values are set as final threshold values as they are. Incidentally, S35
If the determination result of is Yes, each intermediate threshold value is set as the final threshold value.

On the other hand, in S34, the rough road flag Fak is 1
If it is determined that the absolute value of the steering angle θ is smaller than 90 ° as in S35, the process proceeds to S37, and if YES, in S38,
Based on the control threshold correction table in FIG. 8, 2-3 intermediate slip ratio threshold Bsg and 5-1 slip ratio threshold B
The values obtained by subtracting 5% from sz are set as the final 2-3 intermediate slip ratio threshold value Bsg and the final 5-1 slip ratio threshold value Bsz, and further, in S39, a rough road is dealt with. , 1-2 The value obtained by subtracting 1.0 G from the intermediate deceleration threshold B12 is set as the final 1-2 deceleration threshold B12.

This is because the wheel speed sensors 27 to 30 are likely to make erroneous detections at the time of determining a rough road, so that the response of the control is delayed and a good braking force is secured. Incidentally, other intermediate threshold values are set as they are as final threshold values. When it is determined in S37 that the absolute value of the steering angle θ is not smaller than 90 °, the process proceeds to S39, and the control threshold value correction process is performed according to only the rough road. Furthermore, S
When it is determined in 33 that the representative friction coefficient value Mu is not 3, the process proceeds to S35.

Here, when the tire air pressure decreases, the contact area of the tire increases, the frictional force acting on the tire increases, the load on the tire increases, and the running force becomes stable due to the imbalance of the braking force of the four wheels. In view of the decrease in the property, the steps S40 and S41 are executed. S
At 40, it is determined whether or not the air pressure drop flag FA set in the tire air pressure determination control described later is 1.
When the tire pressure drops and the flag FA is 1,
In S41, the control threshold value correction process when the tire pressure is decreased is executed, and then the process returns and the flag FA is set to 1
If not, the correction process is not executed and S40 to S4 are executed.
Skip 1 and return. The control thresholds are set for the second and third channels as in the case of the first channel.

The correction process executed in S41 is the first
~ This is a process of correcting the brake oil pressure in the lock relaxation direction for all of the third channels, that is, a process of correcting the brake oil pressure to the lower side. This correction toward the lock relaxation direction (a) accelerates the transition time from the increased pressure state of Phase I to the retained state of Phase II, or (b) transitions from the retained state of Phase II to the decompressed state of Phase III. Advance the timing, or (c) delay the transition time from the phase III pressure reduction state to the phase V holding state, or (d) delay the transition time from the phase V holding state to the phase I pressure increasing state. It can be achieved by

In the control threshold value correction table of FIG.
Multiple correction patterns (A) for correction in 41
(C) is shown in the figure, and in the case of this embodiment, as shown in the correction pattern (A), when the flag FA is set to 1 by the judgment that the tire air pressure has decreased,
Various control threshold values for controlling the brake hydraulic pressure of the third channel are corrected as shown in the column of correction pattern (A). That is, the 1-2 intermediate deceleration threshold B12 is 0.2 G,
Also, the 2-3 intermediate slip ratio threshold Bsg is only 3%, the 3-5 intermediate deceleration threshold B35 is only 0.3 G, and
5-1 The slip ratio threshold Bsz is increased by 3% and corrected. However, the control thresholds B12, Bsg,
It is not necessary to incrementally correct all of B35 and Bsz, and only a part of the control threshold values may be incrementally corrected.

Various modifications of the correction in S41 will be described. As the running stability decreases when the tire pressure decreases, as shown in the correction pattern (B) in FIG. 9, the brake oil pressures of the left and right front wheels are not corrected, and only the brake oil pressures of the left and right rear wheels are released in the locking relief direction. You may correct.

Further, when the tire air pressure is reduced, the wheel whose air pressure is lowered is specified in the tire air pressure determination control, which will be described later, and when the air pressure of the left front wheel 1 is lowered, the flag FA = 1 and when the air pressure of the right front wheel 2 is lowered, the flag FA is set. = 2, again
Flag FA = 3 when the air pressure of the left or right rear wheel 3, 4 decreases
, And supplies the data of the flag FA to the control unit 24,
Then, receiving the data of the flag FA, as shown in the correction pattern (C) of FIG. 9, the brake hydraulic pressure of only the channel (air pressure lowering channel) corresponding to the wheel whose air pressure has decreased is corrected in the lock relaxation direction, The brake oil pressure of the channel (normal air pressure channel) corresponding to the wheel whose air pressure does not decrease may not be corrected.

Further, the correction pattern (A) or (B) or
The correction of the control threshold value in (C) may be executed only when the road friction state is a high friction state (that is, Mu = 3). That is, when the road surface friction coefficient is not large, even if the tire air pressure decreases, the influence is small.

As described above, when the tire pressure decreases, the contact area of the tire increases, the frictional force acting on the tire increases, and the load on the tire increases.
When the tire air pressure is reduced through steps S40 and S41, the brake hydraulic pressure is corrected in the lock relaxation direction to reduce the load on the tire and the damage due to the wear of the tire. To correct only the brake oil pressure of wheels 3 and 4 in the direction of relaxing the lock,
It is possible to suppress a decrease in running stability when the tire air pressure decreases. An example of a time chart of the ABS control for the first channel in the antiskid brake device described above is shown in FIG.

Next, the tire air pressure determination device will be described. As shown in FIG. 1, this tire air pressure determination device includes four wheel speed sensors 27 to 30 and an initial setting switch 33 (which is attached to an instrument panel for instructing the initial setting of tire air pressure determination). Warning lamp 3 attached to the instrument panel
4, the control unit 40, etc., the control unit 40, from the sensors and switches such as wheel speed sensors 27-30, brake switch 25, steering angle sensor 26, odometer 31, initial setting switch 33, etc. A signal is supplied, and the warning lamp 34 is drive-controlled by the control unit 40.

Each of the wheel speed sensors 27 to 30 has a disk 11
a formed on a -14a or formed on a detection disk (not shown) provided adjacent to the disks 11a -14a
The configuration is such that four detection units are detected by an electromagnetic pickup. The control unit 40 is a wheel speed sensor.
A filter for filtering the detection signal from 27 to 30, a circuit for shaping the waveform of the detection signal filtered by the filter, an AD converter for A / D converting various analog detection signals, an input / output interface, a CPU, a ROM and a RAM. And a control program and a map for tire air pressure determination control, which will be described later, are stored in advance in the ROM, and the RAM includes various memories (buffer, memory, Flags, counters, soft timers, etc.).

The tire air pressure determination control executed by the control unit 40 will be described below with reference to FIGS. In the flow chart, the reference symbol Si (i = 50, 51, ...) Indicates each step.
First, the outline of the tire air pressure determination control will be described. Basically, the tire air pressure determination is performed based on the wheel speeds Vw1 to Vw4 detected by the four wheel speed sensors 27 to 30, but the use of the vehicle is started. Initialization of a coefficient Cx (which corresponds to a compensation coefficient) for compensating a tire manufacturing error and characteristics is performed when one or a plurality of tires are replaced. After that, periodically (every predetermined mileage, or
The tire pressure determination process is executed every predetermined period) to determine whether the tire pressure is abnormal. If the tire pressure is low, an alarm is output via the warning lamp 34 and the ABS control is performed. The data of the flag FA corresponding to the state of decrease in tire air pressure is supplied to the control unit 24 for vehicle.

The initial setting processing is executed in the vehicle speed range set according to the road surface friction state, and the tire air pressure determination processing is executed in the vehicle speed range separately set according to the road surface friction state. To be executed. The tire air pressure determination control includes the initial setting process and the tire air pressure determination process, and data regarding road friction is supplied from the control unit 24 to the control unit 40.
However, the road surface friction coefficient can also be obtained from the change in the vehicle speed V during the acceleration state.

Next, the initial setting process of the coefficient Cx will be described with reference to FIG. The initial setting process of the coefficient Cx is performed by setting the a-contact type initial setting switch 33 attached to the instrument panel to 0 when the tire is replaced.
It is started when N is operated, then various data obtained by digitizing the signals from the sensors 27 to 30, 26 and the switch 25 are read (S50), and next, in order to show that the initial setting process is being executed, The warning lamp 34 is turned on, and the flag F is reset to 0 to prohibit the tire air pressure determination processing (S51). Next, it is determined whether or not the initial setting condition of the coefficient Cx is satisfied (S52), but the vehicle is not in the acceleration / deceleration state, is in the steady straight traveling state, and the vehicle speed V is shown in the map of FIG. The vehicle is in the initial permitted vehicle speed range of the coefficient Cx set according to the road friction state,
Is satisfied, the condition is determined to be satisfied, and the process proceeds to S53. When the condition is not satisfied, the process proceeds to S59.
The vehicle speed is applied as the vehicle speed V and is set equal to the average value of the wheel speeds Vw1 and Vw2 of the left and right driven wheels (front wheels 1 and 2), and acceleration / deceleration is detected from the change in the vehicle speed V.

Here, the lower limit value of the initially permitted vehicle speed range of the coefficient Cx shown in FIG. 16 is set to a predetermined value (for example, 20 Km / H) that is not excessively low, and the upper limit of the initially permitted vehicle speed range is set. The value is 40 to 5 depending on the road friction on the road surface.
It is set to a value in the range of 0 Km / H. Regarding the upper limit value, 40 km / H in the low μ state to 5 in the high μ state
It is set to increase linearly to 0 Km / H. still,
μ is the coefficient of friction of the road surface. In the high speed state of more than 50 km / H, the slip amount of the driving wheels increases, the wheel loads of the front wheels 1,2 and the rear wheels 3,4 change, and the detection accuracy of the wheel speeds Vw1 to Vw4 decreases. Therefore, it is desirable to execute the initial setting process when the vehicle speed is 50 Km / H or less, and the slip amount of the drive wheels increases when the vehicle speed is low, so 40
It is desirable to execute the initial setting process when the vehicle speed is Km / H or less.

Next, when it is determined in S52 that the condition is satisfied, the coefficient Cx for compensating the initial state of the four tires at the time of tire replacement, etc., in consideration of the tire manufacturing error and characteristics in S53 is four wheels. Using the wheel speeds Vw1 to Vw4, the sum of the wheel speeds of the left front wheel 1 and the right rear wheel 4 (Vw1 + Vw4) in one diagonal relationship, and the wheel of the right front wheel 2 and the left rear wheel 3 in the other diagonal relationship The ratio to the sum of speeds (Vw2 + Vw3) is calculated by the following equation. Coefficient Cx = (Vw1 + Vw4) / (Vw2 + Vw3) Next, in S54, it is determined whether or not the coefficient Cx is an appropriate value, but the tire diameter error due to the tire manufacturing error is 0.
Since it is 3%, it is determined that the coefficient Cx is an appropriate value when the coefficient Cx is within a predetermined range of approximately 1 (for example, 0.95 to 1.05).

When the coefficient Cx is a proper value, S55
The coefficient Cx rewriting process is executed in this step, the previous Cx (i-1) is given the current Cx (i), the warning lamp 34 is turned off, and a flag is set to permit the tire pressure determination process. F is set to 1, then S5
Move to 9. On the other hand, when the determination result of S54 is No,
In S57, it is determined whether or not the coefficient Cx is indefinite, and when it is indefinite, the process proceeds to S59. When it is not indefinite, the warning lamp 34 blinks in S58 for a predetermined time (for example, 2 seconds), and then the process proceeds to S59. In S59, it is determined whether or not the flag F is 1, and if Yes, this process ends, and if No, the process returns to S50. However, based on one ON operation of the switch 33, the initialization processing is executed a plurality of times to obtain a plurality of coefficients C.
It is also possible to obtain x and determine the final coefficient Cx from the average value of the plurality of coefficients Cx. In this way, the coefficient Cx for compensating the initial state of the four tires at the time of tire replacement is determined and stored in the memory of the RAM.

Next, the tire pressure determination process will be described with reference to the flowcharts of FIGS. 13 and 14.
This tire air pressure determination processing is, for example, processing executed for each mileage of 100 Km, and after the start of this processing,
Various data obtained by digitizing the signals from the sensors 27 to 30, 26 and the switch 25 are read (S70), and then,
It is determined whether the flag F is 1 (S71), and if Yes, it is determined in S72 whether the tire air pressure determination condition is satisfied. Regarding the tire pressure determination conditions, the vehicle is not in the acceleration / deceleration state, is in the steady straight traveling state, and the vehicle speed is within the tire pressure determination permission vehicle speed range set according to the road surface friction state shown in the map of FIG. Is satisfied, it is determined that the condition is satisfied and S7 is satisfied.
If the condition is not satisfied, the process proceeds to S74.

Here, the lower limit value of the tire pressure determination permission vehicle speed range shown in FIG. 17 is set to a predetermined value (for example, 20 Km / H) which is not excessively low, and the upper limit value of the tire pressure determination permission vehicle speed range. Is 4 depending on the road friction on the road surface.
It is set to a value in the range of 0 Km / H to maximum vehicle speed. The upper limit value is set to linearly increase from 40 Km / H in the low μ state to the maximum vehicle speed in the high μ state. Then, in the high speed state of more than 50 km / h, the slip amount of the driving wheels increases and the detection accuracy of the wheel speeds Vw1 to Vw4 decreases, but even if the accuracy decreases to some extent, the high speed running state of more than 50 km / h. Since it is desirable to detect the decrease of the tire air pressure in the above, the setting is made as described above. Also, low μ
Since the slip amount of the driving wheel increases at 40km,
It is desirable to execute the tire pressure determination process when the vehicle speed is less than / H.

In S73, the tire air pressure determination subroutine of FIG. 14 is executed, and then the process returns and S7 is executed.
If the determination result in 1 or S72 is No, the timer T in the tire pressure determination subroutine is determined in S74.
Is reset, the flags Fa and Ft are reset to 0, the counters I and J are reset to 0, and then the process returns.

Next, the tire air pressure determination subroutine of S73 will be described with reference to FIG. First, it is determined whether or not the flag Ft is 1 (S80). Since it is initially No, the timer T is started and the flag Ft is set to 1 in S81, and the process proceeds to S82. Further, when the flag Ft is set to 1, S80 to S
82. Next, in S82, the air pressure determination variable D is calculated by the equation shown, that is, the following equation.

D = 2 × [Cx (Vw2 + Vw3)-(Vw1 + Vw4)]
/ [Vw1 + Vw2 + Vw3 + Vw4] In the above equation, the coefficient Cx is set in advance so as to compensate for the initial state of the tire. Therefore, when the tire air pressure is normal, the air pressure determination variable D becomes a value substantially equal to 0. However, when the tire air pressure of the right front wheel 2 or the left rear wheel 3 is decreasing, the wheel speed Vw2 or the wheel speed Vw3 increases, so the air pressure determination variable D increases in the positive direction, and the left front wheel 1 or When the tire air pressure of the right rear wheel 4 is decreasing, the wheel speed Vw1 or the wheel speed Vw4 increases, so the air pressure determination variable D increases in the negative direction.

Next, in S83, it is judged whether or not the judgment variable D is a predetermined value D0 (for example, a predetermined value in the range of 0.020 to 0.050), and if the judgment result is Yes, the flag F
It is determined whether or not a is 1 (S84), and when the flag Fa is not 1, the counter I that counts the number of times the determination variable D is the predetermined value D0 or more is set to 1 and the flag Fa is set to 1 (S85). , And then shifts to S91.
When the flag Fa is set to 1, S
The routine shifts from S84 to S86, the counter I is incremented, and then proceeds to S91.

On the other hand, if the determination result in S83 is No, S
87, it is determined whether the determination variable D is less than or equal to a predetermined value −D0. If Yes, it is determined whether the flag Fa is 2 (S88), and if the flag Fa is not 2, the determination variable D is the predetermined value. -Counter J for counting the number of times D0 or less
Is set to 1 and the flag Fa is set to 2 (S
89) and then the process moves to S91. Further, when the flag Fa is set to 2, the process proceeds from S88 to S90, the counter J is incremented, and then S91.
Go to F.

Next, in S91, it is determined whether or not the count value T of the timer T has passed a predetermined time T0 (for example, 2 seconds), but in the beginning, the determination result is No, so S91. Repeatedly returning from
The steps S70 to S72 and S80 to S91 of FIG. 13 are repeatedly executed, and the count value T of the timer T and the count value I of the counter I or the count value J of the counter J are increased. Note that FIG. 18 illustrates the behavior of the air pressure determination variable D when the tire pressure is normal, and FIG. 19 illustrates the behavior of the air pressure determination variable D when the tire pressure of the right front wheel 2 or the left rear wheel 3 is abnormal. There is.

When the predetermined time T0 has elapsed, the determination result in S91 becomes Yes, so the process proceeds to S92, and it is determined whether the count value I of the counter I is the predetermined value K0 or more or the count value J of the counter J is the predetermined value K0 or more. If the determination result is No and the determination result is No, it is determined in S93 that the tire air pressure is normal, then the air pressure drop flag FA is reset to 0 in S94, and the ABS in S95.
The data of the flag FA is output to the control unit 24 for control, and then the process proceeds to S100. If the determination result in S92 is Yes, it is determined that the tire pressure is abnormal (decreased) in S96, and in S97, the warning lamp 34 is lit for a predetermined time (for example, 2 seconds) to warn the driver of the decrease in tire pressure. And then S
In 98, the flag FA is set to 1, and then in S99.
At, the data of the flag FA is output to the control unit 24, and then the process proceeds to S100. In S100, the timer T, the flag Fa, the flag Ft, the counter I, the counter J are prepared for the next tire air pressure determination process.
However, each is reset to 0, and the tire air pressure determination processing of this time ends.

Here, the abnormal air pressure wheel detection processing for identifying the wheel whose air pressure has dropped will be described with reference to FIG. This abnormal wheel detection process is a calculation process for every minute time, which is the same as the routine of FIG. 14, and is executed as an interrupt process for the routine of FIG. After start, wheel speed Vw1
Determination whether ≧ Vw4 (S110) and wheel speed Vw2 ≧ Vw3
Whether or not it is determined (S113) is executed, and the counters K1 to K4 that are determined to be larger are incremented (S111 to S115).

Until the time T counted by the timer T in FIG. 14 reaches the predetermined time T0, S110 to S116 are repeatedly executed and the counters K1 to K4 are incremented. Then, when the predetermined time T0 has elapsed after the start of the tire air pressure determination processing, in S117, S92 of FIG.
When the same judgment is made and the judgment result is No,
In S125, the flag FA is reset to 0, and when the determination result in S117 is Yes and the tire pressure is abnormal, it is determined in S118 whether the flag Fa is 1 (S118) and the flag Fa is 1 When is S
At 119, it is determined whether the count value K2 is equal to or greater than the count value K3. If K2 ≧ K3, it is determined at S120 that the tire pressure of the right front wheel 2 is abnormal, and the flag F
A is set to 2. The determination result of S119 is K2 ≧ K
If not 3, the tire pressure of the left rear wheel 3 is determined to be abnormal and the flag FA is set to 3 in S121.

When the determination result of S118 is No,
That is, when the flag Fa is 2, it is determined in S122 whether the count value K1 is greater than or equal to the count value K4, and K
When 1 ≧ K4, the tire pressure of the left front wheel 1 is determined to be abnormal in S123, and the flag FA is set to 1. If the determination result in S122 is not K1 ≧ K4, it is determined in S124 that the tire pressure of the right rear wheel 4 is abnormal, and the flag FA is set to 3. Incidentally, S12
At 5, after the counters K1 to K4 are cleared, the arithmetic processing ends.

In this way, the air pressure reduction flag FA is set to 1 when the air pressure of the left front wheel 1 is reduced, is set to 2 when the air pressure of the right front wheel 2 is reduced, and the left or right rear wheel 3, 4 is set. Set to 3 when the air pressure drops to
When the air pressure of all four wheels is normal, it is set to 0 and the data of the air pressure drop flag FA is set in the control unit 24.
Then, the control unit 24 specifies the wheel whose air pressure has decreased based on the data of the air pressure decrease flag FA and appropriately applies it to the ABS control.

Next, the operation of the tire air pressure determination device described above will be described. An initial setting switch 33 is provided on the instrument panel, and by operating the switch 33, the initial setting process for initializing the coefficient Cx is executed when necessary, such as when the tire is replaced. It is possible to set the coefficient Cx that compensates for manufacturing errors and characteristics. Since the initial setting process is executed in the vehicle speed range that is set according to the road friction state of the traveling road surface during steady straight traveling, it is caused by the slip of the driving wheel on the low μ road, the fluctuation of the wheel load, etc. It is possible to eliminate the error factors that occur as much as possible and initialize the coefficient Cx with high accuracy.

After the initial setting process, the tire air pressure determination process is executed using the coefficient Cx every time a predetermined distance travels or a predetermined period elapses. This tire pressure determination process is executed when the vehicle is traveling straight and in the vehicle speed range set according to the road friction state of the road surface.Therefore, as in the case of the initial setting process, slip of the drive wheels on low μ roads is performed. And eliminate the error factors caused by wheel load fluctuations, etc.
The accuracy and reliability of tire pressure determination can be improved. Particularly, in the anti-skid brake device and the tire air pressure determination device according to the present embodiment, when the tire air pressure decreases, the brake oil pressure of the four wheels, the brake oil pressure of the left and right rear wheels, or the brake oil pressure of the wheel with reduced air pressure. Is controlled in the lock relaxation direction, the load on the tire can be reduced, damage to the tire can be reduced, and running stability can be improved.

Next, another embodiment in which a part of the tire air pressure determination control is changed will be described with reference to FIGS. 20 and 21. 20 is a flowchart of the initial setting process corresponding to FIG. 12, and the same steps as those in FIG. 12 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, instead of the coefficient Cx, an initial deviation Δ for compensating a tire manufacturing error or the like is applied, and in S52A, as in S52, it is determined whether or not the initial deviation Δ initial setting condition is satisfied. When the condition is satisfied and the condition is satisfied, the initial deviation Δ is calculated by the equation shown in S53A. S54A
Then, it is determined whether or not the initial deviation Δ is an appropriate value. For example, when it is in the range of −0.05 to 0.05, it is determined to be an appropriate value, and the rewriting process of the initial deviation Δ is executed in S55A. If the initial deviation Δ is not an appropriate value, S5
In 7A, it is determined whether or not the initial deviation Δ is indefinite, as in S57.

Next, the tire air pressure determination subroutine of the tire air pressure determination processing of FIG. 13 will be described with reference to FIG.
21 is a diagram corresponding to FIG. 14, and the same steps as those in FIG. 14 are designated by the same reference numerals and the description thereof will be omitted. The tire air pressure determination variable D in the present embodiment is calculated by the formula shown in S82A, and in S83A,
It is determined whether (D-Δ) is equal to or greater than a predetermined value D0,
Further, in S87A, it is determined whether or not (D−Δ) is equal to or less than the predetermined value −D0.

Next, in the ABS control executed by the control unit 24, as shown in FIG.
Another embodiment of the content of the correction with respect to the control threshold value executed in S41 will be described. At the time of tire pressure drop, in order to secure the grip force of the tire, in consideration of the fact that the wheel becomes difficult to lock because the frictional force of the tire with reduced air pressure becomes large, at the time of tire pressure drop,
Correct the brake hydraulic pressure in the direction of strengthening the lock. in this case,
It is assumed that the control threshold value is corrected by any one of the correction pattern (D), the correction pattern (E), and the correction pattern (F) of the control threshold value correction table shown in FIG.

That is, in the case of the correction pattern (D), when the air pressure is reduced, the 1-2 intermediate deceleration threshold B12 is 0.2 G, the 2-3 intermediate slip ratio threshold Bsg is 3%, and , 3-5 Intermediate deceleration threshold B35 is 0.3 G only,
5-1 The slip ratio threshold Bsz is reduced by 3% and corrected. However, the control thresholds B12, Bsg,
It is not necessary to reduce and correct all of B35 and Bsz, and only a part of the control threshold values may be reduced and corrected.

Further, in the case of the correction pattern (E), when the tire air pressure is reduced, the braking force is reduced and the running stability is reduced. Therefore, without correcting the brake hydraulic pressure of the left and right front wheels, the left and right rear wheels are not corrected. Only the brake hydraulic pressure of is corrected to the lock strengthening direction. In the case of correction pattern (F), the brake hydraulic pressure of only the channel corresponding to the wheel whose air pressure has dropped (air pressure drop channel) is corrected to the lock strengthening direction, and the channel corresponding to the wheel whose air pressure does not drop (normal air pressure channel) The brake hydraulic pressure is not corrected. Further, the correction of the control threshold value of the correction pattern (D) or (E) or (F) is carried out when the frictional state of the road surface is a high frictional state (that is, Mu =
It may be configured to execute only in the case of 3). That is,
This is because in the low friction state, the correction of the brake hydraulic pressure in the lock strengthening direction is not very effective.

Here, instead of using the wheel speed as in the above-mentioned embodiment, the tire number is set using the cumulative number Nw1 to Nw4 of output pulses of the wheel speed sensors 27 to 30 in a predetermined period of continuous or intermittent as a parameter. It is also possible to perform the air pressure determination, and it is also possible to perform the tire air pressure determination using the time Tw1 to Tw4 per wheel rotation calculated from the predetermined period and the pulse numbers Nw1 to Nw4 as parameters. . Then, in this case, similarly to the above, the initial setting process is executed, and the cumulative output of the wheel speed sensors 27 to 30 in the continuous or intermittent predetermined period (the predetermined period is the same or different predetermined period). Calculate the number of pulses INw1 to INw4,
It is also possible to execute the tire pressure determination using the pulse number ratio (Nw1 / INw1) to (Nw4 / INw4) as a parameter. Note that the tire air pressure determination processing of the tire air pressure determination control may be constantly executed while the vehicle is running. Further, instead of the tire air pressure determination device, it is also possible to apply a tire air pressure determination device that detects the air pressure of each of the tires of the four wheels with an air pressure sensor and determines a decrease in tire air pressure based on the air pressure. Is.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an automobile anti-skid brake device and a tire air pressure determination device according to an embodiment.

FIG. 2 is a flowchart of road surface friction coefficient estimation.

FIG. 3 is a flowchart of a pseudo vehicle speed calculation process.

FIG. 4 is a diagram of a map of vehicle body speed correction values.

FIG. 5 is a flowchart of a control threshold value setting process.

FIG. 6 is a chart of a table in which running state parameters are set.

FIG. 7 is a chart of a table in which various control threshold values are set.

FIG. 8 is a chart of a table in which correction values of various control threshold values are set.

FIG. 9 is a chart of a table in which correction values of various control threshold values are set.

FIG. 10 is a chart of a table in which correction values of various control threshold values are set.

FIG. 11 is an operation time chart of the anti-skid brake device.

FIG. 12 is a flowchart of an initial setting process of a coefficient Cx of tire air pressure determination control.

FIG. 13 is a flowchart of tire air pressure determination processing of tire air pressure determination control.

FIG. 14 is a flowchart of a tire air pressure determination subroutine of FIG.

FIG. 15 is a flow chart of abnormal air pressure wheel detection processing.

FIG. 16 is a diagram showing a map of an initially permitted vehicle speed range of a coefficient Cx.

FIG. 17 is a diagram showing a map of a vehicle speed range in which tire pressure determination is permitted.

FIG. 18 is a diagram showing the behavior of the air pressure determination variable D when the tire air pressure is normal.

FIG. 19 is a diagram showing the behavior of the air pressure determination variable D when the tire air pressure is abnormal.

20 is a diagram corresponding to FIG. 12 in the tire air pressure determination control according to another embodiment.

FIG. 21 is a flowchart of a tire air pressure determination subroutine of the another embodiment.

[Explanation of symbols]

1, 2 front wheels 3, 4 rear wheels 11-14 brake device 20, 21, 23 1st-3rd valve unit 24 ABS control unit 25 brake switch 26 steering angle sensor 27-30 wheel speed sensor 33 initial setting switch 34 Warning lamp 40 Control unit for tire pressure judgment

Claims (9)

[Claims] 1. An anti-skid brake device having an anti-skid control means for controlling a brake hydraulic pressure adjusting means based on a wheel speed detected by a wheel speed detecting means, and a tire pressure determination for detecting a decrease in tire pressure of a wheel. In the vehicle including a device, the anti-skid control means includes a hydraulic pressure correction means that receives a signal indicating a decrease in tire air pressure from the tire air pressure determination device and corrects the brake hydraulic pressure in the lock relaxation direction. Vehicle control device. 2. The tire air pressure determination device includes abnormal wheel detection means for detecting a wheel whose tire air pressure has dropped, and the oil pressure correction means uses the abnormal wheel detection means to identify a wheel for which the tire air pressure has dropped. In response to this, the vehicle control device according to claim 1, wherein the brake hydraulic pressure of the wheel whose tire air pressure has decreased is corrected in the lock relaxation direction. 3. The vehicle control device according to claim 1, wherein the hydraulic pressure correction unit is configured to correct only the brake hydraulic pressures of the left and right rear wheels in the lock relaxation direction. 4. The control device for a vehicle according to claim 1, wherein the hydraulic pressure correction means is configured to correct the brake hydraulic pressure of the rear wheels in a lock relaxation direction more than the brake hydraulic pressure of the front wheels. . 5. The anti-skid control means includes a friction state detection means for detecting a friction state of a road surface, and the hydraulic pressure correction means is provided only when the friction state detection means detects a road friction state as a high friction state. The control device for a vehicle according to claim 1, wherein the control device is configured to correct the brake hydraulic pressure. 6. An anti-skid brake device having an anti-skid control means for controlling a brake hydraulic pressure adjusting means based on the wheel speed detected by the wheel speed detecting means, and a tire pressure determination for detecting a decrease in tire pressure of a wheel. In the vehicle including a device, the anti-skid control means includes a hydraulic pressure correction means that receives a signal indicating a decrease in tire pressure from the tire pressure determination device and corrects the brake hydraulic pressure in the lock strengthening direction. Vehicle control device. 7. The tire pressure determination device includes abnormal wheel detection means for detecting a wheel whose tire pressure has dropped, and the hydraulic pressure correction means outputs a signal from the abnormal wheel detection means for identifying a wheel whose tire pressure has dropped. In response to this, the vehicle control device according to claim 6, which is configured to correct the brake hydraulic pressure of the wheel whose tire air pressure has decreased in the lock strengthening direction. 8. The vehicle control device according to claim 6, wherein the hydraulic pressure correction unit is configured to correct only the brake hydraulic pressures of the left and right front wheels in the lock strengthening direction. 9. The anti-skid control means includes a friction state detection means for detecting a friction state of a road surface, and the hydraulic pressure correction means is provided only when the friction state detection means detects a road friction state as a high friction state. The control device for a vehicle according to claim 6, wherein the control device is configured to correct the brake hydraulic pressure.