JPH07267068A - Antiskid brake device for vehicle - Google Patents

Abstract

PURPOSE:To adapt antiskid brake control to an actual condition by preventing sudden pressure reduction by performing gentle pressure reducing operation when either left or right wheel is put in a lock condition, and quickly recovering grip force by performing speedy pressure reducing operation when left and right wheels are put in a lock condition. CONSTITUTION:A control unit 24 calculates acceleration and deceleration of respective wheels 1 to 4 according to detecting wheel speed signals from wheel speed sensors 27 to 30. Respective road surface friction coefficients and pseudo- car body speeds are also calculated with every prescribed minute time. Next, a nonslip rate is calculated from respective wheel speeds and the pseudo-car body speeds, and a slip tendency of the respective wheels is judged. A control threshold value is set, and lock judging processing is performed, and when either left or right wheel among the wheels 1 to 4 is put in a lock condition, gentle pressure reducing operation to brake devices 11 to 14 is performed on the corresponding wheels. When both left and right wheels are put in a lock condition, speedy pressure reducing operation is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-skid brake device that suppresses an excessive braking force when a vehicle is being braked to effectively control the braking.

[0002]

2. Description of the Related Art As a vehicle braking system, an anti-skid brake device has been put into practical use, which prevents a wheel from being locked or a skid state from occurring during braking. This type of anti-skid brake device includes a wheel speed sensor that detects a wheel speed of a wheel, an electromagnetic control valve that adjusts brake hydraulic pressure, and a control device that controls the electromagnetic control valve based on the wheel speed detected by the wheel speed sensor. Have and. This control device, for example, determines the acceleration / deceleration of the wheel based on the detected wheel speed, and when the wheel deceleration becomes equal to or less than a predetermined value, the electromagnetic control valve is pressure-reduced to reduce the braking pressure, and the braking pressure is reduced. When the wheel speed increases and the wheel acceleration reaches a predetermined value, the braking pressure is increased by increasing the pressure of the control valve. By continuing such a series of braking pressure control (hereinafter referred to as ABS control) until, for example, the vehicle stops, a wheel lock or skid state during sudden braking is prevented and vehicle directional stability is ensured. While stopping, it is possible to stop at a short braking distance. The ABS control is performed by increasing pressure, maintaining pressure, reducing pressure, and maintaining reduced pressure.
Control of multiple cycles with one phase as one cycle,
Alternatively, it is usually executed under the control of a plurality of cycles in which the two phases of pressure increase and pressure decrease are one cycle.

The brake hydraulic control system for each wheel is
Normally, the front wheels are configured by an independent control system that controls the left and right wheels independently, and the rear wheels are configured by a so-called integrated control system that commonly controls the left and right wheels. That is, the hydraulic control system of the anti-skid brake device is 3
Has two channels. In the ABS control, the switching of the hydraulic control phase is performed by judging the slip ratio of the wheels, that is, the degree of the locked state. In this case, the determination of the locked state is such that the threshold value of the wheel slip rate is set in advance, and the phase is switched when the calculated slip rate exceeds the threshold value. In the case of the above-described three-channel anti-skid brake device, the slip ratio of the front wheels is calculated based on the wheel speed detected for each of the left and right sides, so that ABS control with different contents may proceed for each wheel. Becomes On the other hand, in the ABS control of the rear wheels, the wheel speeds of the left and right wheels are detected independently, but since the hydraulic control system is provided for the left and right wheels in common, the brake hydraulic pressure control for applying the braking force to the left and right wheels is common. Become.

However, making the ABS control of the rear wheels into the integrated control as described above means that when the behaviors of the left and right wheels are different,
The problem arises that proper control cannot be achieved. For example, when one of the wheels satisfies the ABS control start condition or the control phase change condition, the ABS control is started or changed regardless of the condition of the other wheel, so that the behavior of the other wheel is changed. You will lose control. Considering the difference in the behavior of the left and right wheels A
As the BS control, in Japanese Patent Laid-Open No. 4-59458, when the speed difference between the left and right wheels of the wheels for which the integrated control is performed is equal to or more than a predetermined value, the pressure increasing rate of the wheel on the high speed side is increased. ABS control is disclosed.

[0005]

However, the disclosed technique is configured such that the hydraulic control of the rear wheels can be performed independently on the left and right sides, and the normal complete left and right integrated control is performed. However, there is a problem that the device is complicated and the number of parts is large. An object of the present invention is to provide an ABS control that is at least suited to the actual situation in the anti-skid brake device equipped with a hydraulic control system that performs integrated control of the left and right wheels for at least one of the front and rear wheels. An object is to provide an anti-skid brake device that can be operated.

[0006]

The present invention is configured as follows to achieve the above object. That is, the anti-skid brake device according to the present invention includes a wheel speed detection unit that detects at least the rotational speeds of the left and right wheels, and a hydraulic pressure adjustment that adjusts the brake hydraulic pressure to perform integrated control of the braking force of the left and right wheels. Means, anti-skid brake control means for performing hydraulic control including at least the pressure increasing phase for increasing the brake hydraulic pressure and the pressure decreasing phase for decreasing the brake hydraulic pressure by the hydraulic pressure adjusting means, and one of the left and right wheels is locked. First lock state detecting means for detecting a first lock state indicating that
Second lock state detecting means for detecting a second lock state indicating that both the left and right wheels are in a lock state; and a case where the first lock state is detected when the second lock state is detected. In contrast to the above, the pressure reducing correction means for rapidly reducing the pressure of the brake hydraulic pressure in the pressure reducing phase is provided.

In a preferred mode, the anti-skid brake control means starts control when the first lock state is detected. Further, according to another feature of the present invention, when the first lock state is determined for one of the left and right wheels and the anti-skid brake control is started, the lock state of the other wheel is further detected. Therefore, when the second lock state is achieved, the lock determination threshold value for determining the lock state of the other wheel is set to a threshold value lower than the determination threshold value for the first lock state. That is, when the first skid state is detected, the anti-skid brake device is actuated, and once the ABS control is started,
Further, when the locked state progresses, the first
The lock state of the wheel other than the wheel for which the lock state is determined is determined.

[0008]

According to the anti-skid brake device of the present invention, one of the left and right wheels of the integrated control is in the locked state in light of the lock determination threshold value, and both the left and right wheels are in the locked state. In some cases, ABS control according to different integrated control is performed. Since the running situation of the vehicle is different when one of the left and right wheels is in the locked state and when both are in the locked state,
It is judged that it is preferable to change the ABS control correspondingly. In other words, in the first lock state in which either the left or right wheel is in the locked state, the other wheel is not in the locked state. Therefore, if the pressure reducing operation is suddenly performed, the lock can be released, but the braking effect deteriorates. However, there arises a problem that the braking performance is deteriorated. Therefore, in such a case, control is performed so that the brake hydraulic pressure is not suddenly reduced. Even if a relatively gentle pressure reducing operation is performed in this manner, the other wheel that is not in the locked state secures a certain degree of gripping force as seen from the entire vehicle, so that the gripping force does not unduly decrease.

In contrast to this, when both the left and right wheels are in the locked state, the gripping force of the left and right wheels as a whole is impaired. In this case, if the brake hydraulic pressure is continuously increased. , There is a possibility that the traveling of the vehicle becomes unstable. Therefore, in the second lock state, it is necessary to perform a quick decompression operation to recover the grip force immediately. From this point of view, in the present invention, when the left and right wheels are in the second locked state in which the wheels are in the locked state, the pressure is relatively rapidly reduced and the locked state is quickly released. By monitoring the behavior of both the left and right wheels and changing the content of the integrated control of the left and right wheels in accordance with the situation in this manner, ABS control that responds to the situation of the vehicle becomes possible.
The start timing of the integrated ABS control as described above is preferably started when either one of the wheels is in a locked state, and such control makes it possible to perform control with good responsiveness. Most typically, the lock determination threshold for determining the first lock state and the decompression start threshold for starting the decompression phase may be set to the same threshold. In this case, the high speed wheel is usually locked among the left and right wheels. Therefore, when the locked state of the high speed wheel is detected, the first locked state is determined, and at the same time, the pressure reducing correction means is operated. The content of the ABS control may be changed.

Then, when the anti-skid brake control is started by determining the first locked state of one of the left and right wheels, the second locked state is detected by further detecting the locked state of the other wheel. In this case, the lock determination threshold for determining the locked state of the other wheel is set to a threshold lower than the determination threshold for the first locked state. That is, when the anti-skid brake device is activated by the detection of the first lock state and the lock state further progresses after the ABS control is started, the first lock state is detected. The lock state of the wheel other than the determined wheel is determined. Since the threshold value at this time is set to a value lower than the lock determination threshold value in the first lock state, it is possible to detect even a light lock state. For this reason, when the first lock state is generated by this and the ABS control is performed at a predetermined pressure reduction rate, it is possible to perform a rapid pressure reduction operation by further detecting the second lock state. It becomes possible to get out of the locked state. That is, in the present invention, even when the first lock state of one of the left and right wheels is detected and a predetermined depressurizing operation is started, the lock state further deepens and the second lock state is entered. The pressure reduction control can be corrected correspondingly. Therefore, according to the present invention, either one of
When the ABS control is started by exceeding the predetermined threshold value, that is, when the first lock state is detected, further, after the ABS control is started by the detection of the first lock state, the lock state is changed. In any case where the pressure reducing control of the ABS control is corrected by advancing and detecting the second lock state, it is possible to appropriately respond.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in the vehicle according to this embodiment, the left and right front wheels 1 and 2 are driven wheels, and the left and right rear wheels 3 and 4 are driving wheels, and the output torque of the engine 5 is from the automatic transmission 6. It is configured to be transmitted to the left and right rear wheels 3, 4 via the propeller shaft 7, the differential device 8 and the left and right drive shafts 9, 10. Each of the wheels 1 to 4 includes a disk 11a to 14a that rotates integrally with the wheel, and a brake device 11 including a caliber 11b to 14b that receives the supply of a braking pressure and brakes the rotation of the disk 11a to 14a.
14 are provided respectively, and these brake devices 11 to 14 are provided.
There is provided a brake control system 15 for operating the. The brake control system 15 includes a booster device 17 for increasing a stepping force on a brake pedal 16 by a driver.
And a master cylinder 18 that generates a braking pressure according to the stepping force increased by the booster 17. The front wheel braking pressure supply line 19 from the master cylinder 18 is branched into two paths, and the front wheel branch braking pressure lines 19a and 19b are respectively connected to the calibers 11a and 12a of the left and right front wheel 1 and 2 brake devices 11 and 12, respectively. An electromagnetic on-off valve 20a is connected to one front wheel branch braking pressure line 19a that is connected to the brake device 11 for the left front wheel 1.
Similarly, a first valve unit 20 including an electromagnetic relief valve 20b is provided, and similarly to the first valve unit 20, the other front-wheel branch braking pressure line 19b communicating with the brake device 12 of the right front wheel 2 is also provided. A second valve unit 21 including an electromagnetic on-off valve 21a and an electromagnetic relief valve 21b is provided.

On the other hand, in the rear wheel braking pressure supply line 22 from the master cylinder 18, an electromagnetic on-off valve 23a and an electromagnetic relief valve 23b are provided, as in the first and second valve units 20 and 21. 3rd valve unit 23 consisting of
Is provided. This rear wheel braking pressure supply line 22
Is branched into two paths on the downstream side of the third valve unit 23, and these rear wheel branch braking pressure lines 22a and 22b are respectively applied to the calibers 13b and 14b of the brake devices 13 and 14 of the left and right rear wheels 3 and 4, respectively. It is connected. The brake control system 15 variably controls the braking pressure of the brake device 11 for the left front wheel 1 via the first valve unit 20.
A channel, a second channel for variably controlling the braking pressure of the brake device 12 for the right front wheel 2 via the second valve unit 21, and both brake devices 13 for the left and right rear wheels 3, 4 via the third valve unit 23. , 14 for variably controlling the braking pressure, and the first to third channels are controlled independently of each other. The brake control system 15 is provided with a control unit 24 for controlling the first to third channels. The control unit 24 has a brake signal from a brake switch 25 for detecting ON / OFF of the brake pedal 16 and a steering wheel. Receiving a steering angle signal from a steering angle sensor 26 that detects a steering angle and a wheel speed signal from wheel speed sensors 27 to 30 that respectively detect the rotation speeds of the wheels, the braking pressure control according to these signals. Signals 1st to 3rd
By outputting to the valve units 20, 21, and 23, respectively, braking control for slippage of the left and right front wheels 1, 2 and rear wheels 3, 4, that is, ABS control is performed in parallel for each of the first to third channels. Has become.

The control unit 24 controls the opening / closing valve 20 in each of the first to third valve units 20, 21 and 23 based on the wheel speed detected by each wheel speed sensor 27-30.
a, 21a, 23a and relief valves 20b, 21b, 23
By controlling the opening and closing of b and b respectively, the braking force is applied to the front wheels 1 and 2 and the rear wheels 3 and 4 with the braking pressure according to the locked state. The relief valves 20b and 21 in the first to third valve units 20, 21 and 23, respectively.
The brake oil discharged from b 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, the braking pressure control signal is not output from the control unit 24, and the first to third valve units 2 as shown in FIG.
Relief valves 20b, 21b, 2 at 0, 21, 23
3b are respectively held closed, and each unit 20, 21, 2
Since the on-off valves 20a, 21a and 23a of No. 3 are each held open, the braking pressure generated in the master cylinder 18 according to the depression force of the brake pedal 16 is applied to the front wheel braking pressure supply line 19 and the rear wheel braking pressure supply. Brake devices 11 to 1 for left and right front wheels 1 and 2 and rear wheels 3 and 4 via a line 22
4, 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 2
4 is the deceleration DVw1 to DVw4 for each wheel based on the wheel speeds Vw1 to Vw4 indicated by the signals from the wheel speed sensors 27 to 30.
And the accelerations AVw1 to AVw4 are calculated respectively. Explaining the method of calculating the acceleration or deceleration, the control unit 24 divides the difference between the previous value of the wheel speed and the current value by the sampling period Δt (for example, 7 ms), and then converts the result into the gravitational acceleration. Update the value as the current acceleration or deceleration. The control unit 24 also executes a predetermined rough road determination process to determine whether or not the traveling road surface is a bad road. Explaining the outline of this rough road determination processing, for each wheel corresponding to each channel, the wheel acceleration or wheel deceleration, during a predetermined period, count the number of times the predetermined rough road determination threshold value or more, When the number of times is less than or equal to the predetermined value, the rough road flag Fak is set to 0, and when the number of times is larger than the predetermined value, the rough road flag Fak is set to 1. Further, the control unit 24 selects the rear wheels 3 and 4 that represent the wheel speed and acceleration / deceleration for the third channel, but detects the detection error of both wheel speed sensors 29 and 30 of the rear wheels 3 and 4 at the time of slip. 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.

Further, the control unit 24 calculates the road surface friction coefficient for each of the three channels and the pseudo vehicle body speed Vr at predetermined predetermined time intervals. The control unit 24 controls the rear wheel speed and the wheel speed sensor 27 obtained from the signals from the wheel speed sensors 29 and 30,
The non-slip ratios for the first to third channels are calculated from the wheel speeds of the left and right front wheels 1 and 2 detected at 28 and the vehicle body speed Vr. The rate is calculated. Non-slip rate = (wheel speed / pseudo vehicle speed) × 100 Therefore, the greater the deviation of the wheel speed from the vehicle speed Vr, the smaller the non-slip rate and the greater the slip tendency of the wheel. Next, the control unit 24 sets various control threshold values used for controlling the first to third channels, respectively, and uses these control threshold values to perform the lock determination processing for each channel and the first to third The phase determination processing for defining the control amount for the third valve units 20, 21, 23 and the cascade determination processing are performed. Here, the lock determination process will be described. For example, in the lock determination process for the first channel for the left front wheel, the control unit 24
First, the current value of the continuation flag Fcnl for the first channel is set as the previous value, and then the vehicle speed Vr and the wheel speed V are set.
wl is a predetermined condition (for example, Vr <5 Km / H, Vwl <7.
5 km / H) is satisfied, and when these conditions are satisfied, the connection flag Fcal and the lock flag Flokl are reset to 0 respectively, and if they are not satisfied, the lock flag Flokl is set to 1. It is determined whether it has been done.

Unless the lock flag Flokl is set to 1, when the predetermined condition is satisfied (for example, the wheel deceleration is -3.
When it becomes G), set 1 to the lock flag Flokl. On the other hand, when the lock flag Flokl is set to 1, the control unit 24 sets the phase flag P1 of the first channel to 5 indicating the phase V and sets the non-slip rate Sl to the 5-1 non-slip rate, for example. Continuation flag Fcnl when it is larger than the threshold value Bsz
Set 1 to. The lock determination process is similarly performed for the second and third channels. Explaining the outline of the phase determination process, the control unit 24 indicates the ABS non-control state by comparing the respective control threshold values set according to the running state of the vehicle with the wheel acceleration / deceleration and the non-slip rate. Phase O, Phase I which is a pressure increasing state during ABS control, Phase II which is a holding state after pressure increasing, Phase II which is a pressure reducing state
I, a phase IV that is a sudden pressure reduction state, and a phase V that is a holding state after pressure reduction are selected. In the cascade determination process, particularly on a low friction road surface such as ice burn, even if a small braking pressure is applied to the wheels, the wheels are easily locked. 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
A braking pressure control signal corresponding to the phase instructed by the phase flag P1 is output to each of the first to third valve units 20, 21, and 23 for each channel. As a result, the braking pressure of the front wheel branch braking pressure lines 19a, 19b and the rear wheel branch braking pressure lines 22a, 22b on the downstream side of the first to third valve units 20, 21, 23 is increased or decreased. , The pressure level after pressure increase or pressure reduction is maintained. A method of calculating the road surface friction coefficient (road surface μ) will be described. First, when the road surface friction coefficient Mul of the first channel is calculated, the road surface friction coefficient Mul is calculated based on the wheel speed Vwl of the front wheels 1 and its acceleration Vg. A 500 ms timer and a 100 ms timer are used. , The acceleration Vg does not become sufficiently large after the start of acceleration 5
The acceleration Vg is calculated by the following equation from the change of the wheel speed Vwl for 100 ms every 100 ms until the lapse of 00 ms. Vg = K1 × [Vwl (i) -Vwl (i-100)] After the lapse of 500 ms when the acceleration Vg becomes sufficiently large, from the change of the wheel speed every 500 ms for 500 ms,
The acceleration Vg is calculated by the following equation.

Vg = K2 × [Vwl (i) -Vwl (i-500)] In the above equation, Vwl (i) is the current wheel speed, Vwl
(I-100) is the wheel speed 100 ms before, Vwl (i-5
00) is the wheel speed before 500 ms, and K1 and K2 are predetermined constants. The road surface friction coefficient Mul is calculated by three-dimensional complementation from the μ table shown in FIG. 2 using the wheel speed Vwl and the acceleration Vg thus obtained. However, road surface μ = 1.0 to 2.5 corresponds to low friction, and road surface μ
= 2.5-3.5 corresponds to medium friction, road surface μ = 35-
5.0 corresponds to high friction. Next, when the road surface friction coefficient Mu2 of the second channel is calculated, it is calculated in the same manner as above using the wheel speed Vw2, and the surface friction coefficient Mu3 of the third channel is calculated.
Is set equal to the smaller one of the road surface friction coefficient Mu1 and the road surface friction coefficient Mu2. However, the road surface μ detected by three dedicated road surface μ sensors corresponding to the first to third channels may be applied. Next, the calculation processing of the vehicle body speed Vr will be described with reference to the flowchart of FIG. First, the control unit 24 reads various data (S2
0), and then the wheel speed V indicated by the signals from the sensors 27 to 30.
Calculate the maximum wheel speed Vwm from w1 to Vw4 (S21),
Next, the maximum wheel speed change amount ΔVwm per sampling period Δt of the maximum wheel speed Vwm is calculated (S22).

Next, the control unit 24 sets S2.
3 in the friction state value Mu (first to first) from the map shown in FIG.
The vehicle body speed correction value CVr corresponding to the road surface friction value of the third channel) is read out, and it is determined in S24 whether the maximum wheel speed change amount ΔVwm is equal to or less than the vehicle body speed correction value CVr.
As a result of the determination, the wheel speed change amount ΔVwm is the vehicle body speed correction value C.
When it is determined that it is equal to or lower than Vr, the value obtained by subtracting the vehicle body speed correction value CVr from the previous value of the vehicle body speed Vr is replaced with the current value in S25. Therefore, the vehicle body speed Vr decreases with a predetermined gradient according to the vehicle body speed correction value CVr. On the other hand, when the control unit 24 determines in S24 that the wheel speed change amount ΔVwm is greater than the vehicle body speed correction value CVr, that is, when the maximum wheel speed Vwm shows an excessive change, the control unit 24 determines in S26 the maximum value from the pseudo vehicle body speed Vr. It is determined whether or not the value obtained by subtracting the wheel speed Vwm is equal to or greater than a predetermined value Vo. That is, it is determined whether or not there is a large difference between the maximum wheel speed Vwm and the vehicle body speed Vr. If there is a large difference, the value obtained by subtracting the vehicle body speed correction value CVr from the previous value of the vehicle body speed Vr is replaced with the current value in S25.

Further, when there is no large difference between the maximum wheel speed Vwm and the vehicle body speed Vr, the control unit 24 replaces the maximum wheel speed Vwm with the vehicle body speed Vr in S27. Thus, the vehicle body speed Vr of the vehicle is equal to each wheel speed Vw1.
It is updated every sampling period Δt according to Vw4. Next, the process of setting various control threshold values will be described with reference to FIG.
Will be described with reference to the flowchart of FIG. still,
The control threshold setting process is executed independently for each channel, but here, the control threshold setting process for the first channel for the left front wheel will be described. The control unit 24 reads various data in S30, and then in S31, as shown in FIG. 6, from a table preset with the vehicle speed range and the road surface μ as parameters,
A running state parameter is selected according to the friction state value Mu and the vehicle speed Vr. For example, when the friction state value Mu is 1 indicating a low friction road surface and the vehicle body speed Vr is in the medium speed range, the LM for the medium speed low friction road surface is set as the running state parameter.
2 is selected. The friction state value Mu is the friction coefficient Mu1
~ Mu3 is determined from the minimum, in FIG. 6, Mu = 1 is a low friction state, Mu = 2 is a medium friction state,
Mu = 3 corresponds to a high friction state.

On the other hand, the bad road flag Fak is 1 indicating a bad road condition.
When it is set to, the running state parameter corresponding to the vehicle body speed Vr is selected as shown in FIG. In this case, for example, when the vehicle body speed Vr belongs to the medium speed range, the HM2 for the medium speed / low friction road surface is forcibly selected as the traveling state parameter. In other words, the road surface μ tends to be estimated to be small because the wheel speed fluctuates greatly during traveling on a rough road. After the selection of the traveling condition parameter, the control unit 24 reads each control threshold value corresponding to the traveling condition parameter 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 1-2 intermediate deceleration threshold value B for switching from phase I to phase II is determined.
12, 2 for judging switching from phase II to phase III
-3 Intermediate non-slip rate threshold value Bsg, 3-5 for determining switching from phase III to phase V 3-5 Intermediate deceleration threshold value B35, 5 for determining switching from phase V to phase I
The -1 non-slip ratio threshold value Bsz and the like are set for each running state parameter. In this case, the deceleration threshold value that greatly affects the control force is such that the frictional state value Mu is set in order to achieve a high level of both the braking performance when the road surface μ is large and the control response when the road surface μ is small. The lower the level of, that is, the smaller the road surface μ, the closer to 0G. Here, when the control unit 24 selects the LM2 for medium speed / low friction road surface as the traveling state parameter, as shown in the column of LM2 in the control threshold setting table of FIG.
2 Intermediate deceleration threshold B12, 2-3 Intermediate non-slip ratio threshold Bsg, 3-5 Intermediate deceleration threshold B35, 5-
1 As the non-slip rate threshold value Bsz, -0.5G, 90
The respective values of%, 0G and 90% are read out respectively.

Next, the control unit 24 sets S3.
At 3, it is determined whether or not the frictional state value Mu is set to 3, which indicates a high friction road surface, and when Yes is determined, at S34, it is determined whether or not the rough road flag Fak is set to 0. As a result of the judgment, a bad road Brag Fak
Is 0, it is determined in S35 whether the absolute value of the snake angle θ detected by the snake angle sensor 26 is smaller than 90 °, and the absolute value of the snake angle θ is not smaller than 90 °. At step S36, the control threshold value is corrected according to the snake angle θ. This control threshold value correction processing is performed based on the control threshold value correction table illustrated in FIG.
That is, in the control threshold value correction table of FIG. 8, in order to secure the steerability when the road is not a bad road with low friction, medium friction, and high friction, and when the steering wheel operation amount is large, 2-3 intermediate non- The value obtained by adding 5% to the slip ratio threshold value Bsg and the 5-1 intermediate non-slip ratio threshold value Bsz is the final 2
-3 non-slip rate threshold value Bsg and final 5-1 non-slip rate threshold value Bsz are set, and other intermediate threshold values are set as they are as final threshold values. In order to ensure the running performance when the steering wheel operation amount is small, on a rough road with a high friction (flag Fak = 1), 2-3
The values obtained by subtracting 5% from the intermediate non-slip ratio threshold Bsg and the 5-1 intermediate non-slip ratio threshold Bsz are the final 2-3 non-slip ratio threshold Bsg and the final 5-1 non-slip ratio, respectively. It is set as a threshold value Bsz. next,
When the determination result in S35 is No, each of the intermediate threshold values is directly set as the final threshold value.

On the other hand, the control unit 24 uses S3
When it is determined that the rough road flag Fak is set to 1 in 4, the flow proceeds to S37 and the relation between the rough road flag Fak and the snake angle θ is determined based on the control threshold correction table of FIG. The values obtained by correcting the 2-3 intermediate non-slip rate threshold value Bsg and the 5-1 non-slip rate threshold value Bsz are
A correction process for setting the final 2-3 intermediate non-slip ratio threshold Bsg and the final 5-1 non-slip ratio threshold Bsz is executed, and then in S38, the control threshold correction table of FIG. Based on this, a correction process of setting a value obtained by subtracting 1.0 G from the 1-2 intermediate deceleration threshold value B12 as the final 1-2 deceleration threshold value B12 is performed. This is because the wheel speed sensors 27 to 30 are used when determining a rough road.
Is likely to cause erroneous detection, 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. Further, when the control unit 24 determines in S33 that the frictional state value Mu is not 3, the control unit 24 proceeds to S35. The control thresholds are set for the second and third channels as in the case of the first channel.

Next, a control signal output process for setting the phase and outputting the braking control signal of each phase to the valve unit will be described with reference to the flow charts of FIGS. 9 to 13 using the first channel as an example. . At first,
Various data are read (S40), and then it is determined whether the brake switch 25 is ON. If the determination is NO, the process returns through S42, and if the determination is Yes, S is returned.
At 43, the vehicle body speed Vr is a predetermined value C1 (for example, 5.0
Km / H) or less and the wheel speed Vw1 is a predetermined value (for example, 7.
5 km / H) or less. When the determination is Yes, the vehicle is sufficiently decelerated, and there is no need for ABS control, and therefore the process returns via S42, but the determination of S43 is N.
When it is o, the process proceeds to S44. In S42, the phase flag P1, the lock flag Flok1, and the continuation flag Fcn1 are 0.
Respectively, and then returns to S40. Next, in S44, it is determined whether or not the lock flag Flok1 is 0, and if the flag Flok1 is 0 before the ABS control is started, S is executed.
45, the deceleration DVw1 of the wheel speed Vw1 (however, Dw1
It is determined whether or not Vw1≤0 is equal to or less than a predetermined value D0 (for example, -3G). If the determination is Yes, the process proceeds to S46. On the other hand, when the determination in S44 is No, the process proceeds to S49.

Next, if the determination in S45 is Yes, S
The lock flag Flok1 is set to 1 in 46, the flag P1 is set to 2 in S47, and the process proceeds to phase II (holding phase after pressure increase), and then S48.
The first braking control signal preset for Phase II is
Output to the valve unit 20 and then return. A
Since the flag Flok1 is set to 1 after the BS control is started, the process proceeds from S44 to S49, and it is determined whether the flag P1 is 2 or not. If the flag P1 is 2, the process proceeds to S50 and the flag P1 is 2 If not, the process proceeds to S54. In S50, the non-slip rate S1 is 2-3 non-slip rate threshold B
It is determined whether or not sg or less, and it is determined as No at the beginning. Therefore, the process proceeds from S50 to S48, but when it is repeated and the non-slip ratio S1 becomes equal to or less than the threshold value Bsg, S
The process proceeds from S50 to S51. In S51, the flag P1 is set to 3 and the process moves to phase III (phase of pressure reduction). Next, in S52, the timer T3 for counting the decompression time of the phase III is reset and then started, and then in S53, a braking control signal preset for the phase III is output to the first valve unit 20, and thereafter. To return.

When the flag P1 is not 2, the process proceeds from S49 to S54 to determine whether the flag P1 is 3, and when the determination is Yes, the process proceeds to S55 and the determination is No.
If so, the process proceeds to S59. Next, in S55, it is determined whether or not the deceleration DVw1 is equal to the 3-5 intermediate deceleration threshold value B35, and it is determined as No at the beginning, so S5
When the deceleration DVw1 becomes equal to the threshold value B35 by repeating the process from 5 to S53, the process proceeds to S56, the flag P1 is set to 5 in S56, and the process proceeds to phase V. Next, in S57, the depressurization time Td is calculated from the count value of the timer T3 and stored.
Next, in S58, a braking control signal preset for phase V is output to the first valve unit 20, and then the process returns. Next, when the determination in S54 is No,
In S59, it is determined whether or not the flag P1 is 5, and if the determination is Yes, the process proceeds to S60, and if No, S
Move to 67. When the flag P1 is 5, it is determined in S60 whether the non-slip rate S1 is 5-1 non-slip rate threshold value Bsz or more.

At the beginning, since it is determined as No, S6
The transition from 0 to S58 is repeated. Then, in the phase V, the non-slip rate S1 increases and S60
If the determination is Yes, the process proceeds to S61. In S61, the flag P1 is set to 1 and the phase I (pressure increase phase) is entered, and the continuation flag Fco1 is set to 1. Next, in S62, the rapid pressure increase time Tpz of the initial rapid pressure increase executed at the beginning of the phase I is calculated.
This subroutine will be described later with reference to FIG. Next, in S63, the timer T1 that counts the elapsed time after the start of the phase I is reset and then started, and then in S64, the count time T1 of the timer T1.
Is determined to be less than or equal to the rapid pressure increase time Tpz set in S62, and when the pressure is less than or equal to the rapid pressure increase time Tpz in the beginning, the process proceeds from S64 to S65, and is preset for the initial rapid pressure increase in phase I in S65. The braking control signal is output to the first valve unit 20, and then the process returns. Next, after the shift to phase I, the determination in S59 is No, so the process proceeds from S59 to S67, and it is determined in S67 whether the flag P1 is 1, and when the flag P1 is 1, S
At 68, it is determined whether or not the deceleration DVw1 is equal to or less than the 1-2 intermediate deceleration threshold value B12. Since the determination is No at the beginning, the process proceeds from S68 to S64, and the rapid pressure increase time Tpz elapses. Before that, the process of shifting from S64 to S65 is repeated. While repeating this, after shifting to Phase I,
When the rapid pressure increase time Tpz has elapsed, the determination in S64 is No, so the process proceeds from S64 to S66, and the braking control signal preset for the slow pressure increase in phase I is output to the first valve unit 20. , And then return again.

Next, when the determination in S68 is Yes, S6
In step S9, the flag P1 is set to 2, and in step S70, the pressure increase time Ti is set based on the time measured by the timer T1.
(That is, the period of Phase I) is calculated and stored,
Then, the process proceeds to S48. In this way, after the ABS control is started, it is executed over a plurality of cycles in the order of phase II, phase III, phase V, phase I, phase II, phase III, ... When the switch 25 is turned off, the ABS control ends (see FIG. 15). Next, regarding the control signal output processing of determining the phase and outputting the braking control signal of each phase to the valve unit, referring to the flowcharts of FIGS. 9 to 13 and FIGS. 14 to 16 using the first channel as an example. While explaining. Note that this process is, for example, a process that is repeated every 4 ms. First, various data is read (S40), and then it is determined in S41 whether the brake switch 25 is ON. If the determination is No, the process returns through S42, and if the determination is Yes, the vehicle body is determined in S43. It is determined whether the speed Vr is less than or equal to a predetermined value C1 (for example, 5.0 km / H) and the wheel speed Vwl is less than or equal to a predetermined value (for example, 7.5 km / H). If the determination is Yes, it means that the vehicle has been sufficiently decelerated and A
Since there is no need for BS control, the process returns via S42, but if the determination in S43 is No, the process proceeds to S44.

In S42, the phase flag P1, the lock flag Flokl, the continuation flag Fcnl, and the flag F are reset to 0, respectively, and then the process returns to S40. Then S
At 44, it is judged whether or not the lock flag Flokl is 0, and A
Before the BS control is started, when the flag Flokl is 0, the process proceeds to S45, and the deceleration DVwl of the wheel speed Vwl (where DVwl ≦
It is determined whether the value of 0 is equal to or less than a predetermined value DO (for example, -3G). If the determination is Yes, the process proceeds to S46. On the other hand, when the determination in S44 is No, the process proceeds to S49. Next, if the determination in S45 is Yes, the lock flag Flokl is set to 1 in S46, the flag P1 is set to 2 in S47, and the phase II (holding phase after pressure increase) is entered, Next, in S48, a braking control signal preset for phase II is output to the first valve unit 20, and then the process returns. After the ABS control is started, the flag Flokl is set to 1, so S4
4 to S49 to determine whether the flag P1 is 2 or not,
When the flag P1 is 2, the process proceeds to S50, and when the flag P1 is not 2, the process proceeds to S54.

At S50, it is determined whether the slip rate S1 is equal to or less than the 2-3 slip rate threshold value Bsg, and N is initially set.
Since it is determined to be o, the process moves from S50 to S48.
By repeating this, when the slip ratio S1 becomes equal to or lower than the threshold value Bsg, the process proceeds from S50 to S51. In S51, the flag P1 is set to 3 and the process moves to phase III (phase of pressure reduction). Next, in S52, the timer T for counting the elapsed time after the start of the phase III is reset and then started, and then in S53, the braking control signal for the phase III is sent to the first valve unit 20.
Output, and then returns. However, the subroutine of S53 has a configuration peculiar to the present application, which will be described later with reference to FIGS. 11 to 13. If the result of determination in S49 is that the flag P1 is not 2, S49 to S54
Then, it is determined whether the flag P1 is 3 or not. If the determination is Yes, the process proceeds to S55, and if the determination is No, the process proceeds to S59. Next, in S55, the deceleration DVwl
Is determined to be equal to the 3-5 intermediate deceleration threshold value B35, and is initially determined as No. Therefore, the process proceeds from S55 to S53, but this is repeated until the deceleration DVwl
Becomes equal to the threshold value B35, the process proceeds to S56 and S
At 56, the flag P1 is set to 5 and the phase V
(Phase for holding after depressurization). Next, S57
Flag F used in the subroutine of S53 in
Is reset to 0.

Next, in S58, a braking control signal preset for phase V is output to the first valve unit 20, and then the process returns. Next, if the determination in S54 is No, it is determined in S59 whether the flag P1 is 5, and if the determination is Yes, the process proceeds to S60, and if No, the process proceeds to S67. When the flag P1 is 5, it is determined in S60 whether or not the slip ratio S1 is equal to or greater than the 5-1 slip ratio threshold Bsz. N at first
Since it is determined to be o, the transition from S60 to S58 is repeated. Then, in phase V, when the slip ratio S1 increases and the determination in S60 becomes Yes, S61
Then, in S61, the flag P1 is set to 1 and the phase I (pressure increase phase) is entered, and the continuation flag Fcnl is set to 1. Next, in S62, the rapid pressure increase time Tpz of the initial rapid pressure increase executed at the beginning of the phase I (phase of pressure increase) is calculated. This rapid pressure increase time Tpz is set as a value proportional to the pressure increase time Ti of the previous cycle calculated and stored in S70.
Next, in S63, the timer T1 that counts the elapsed time after the start of phase I is reset and then started,
Next, in S64, the count time T1 of the timer T1 is S
It is determined whether or not the rapid pressure increase time Tpz set in 62 is less than or equal to
At the beginning, when the pressure increase time Tpz is less than or equal to Tpz, S64 to S
65, the braking control signal preset for the initial rapid pressure increase of phase I is output to the first valve unit 20 in S65, and then the process returns.

Next, after the shift to phase I, the determination in S59 is No, so the flow shifts from S59 to S67,
In 67, it is determined whether or not the flag P1 is 1, and the flag P
When 1 is 1, the deceleration DVwl is 1-
2 It is determined whether or not the intermediate deceleration threshold value B12 is less than or equal to B12. Since the determination is No at the beginning, S68 to S64
Transition to S6 and before the rapid pressure increase time Tpz elapses from S64 to S6.
The process of shifting to 5 is repeated. While repeating this,
After the transition to Phase I, when the rapid pressure increase time Tpz has elapsed, S
Since the determination result in No. 64 is No, the process proceeds from S64 to S65, where a preset braking control signal for phase I slow pressure increase is output to the first valve unit 20, and then the process returns. Next, the determination in S68 is Yes.
Then, the flag P1 is set to 2 in S69, and the pressure increase time Ti (phase I period) is calculated and stored based on the time measured by the timer T1 in S70, and then the process proceeds to S48. Thus, after the ABS control is started, Phase II, Phase III, Phase V,
Phase I, phase II, phase III, ... Are sequentially executed over a plurality of cycles, and the determination in S43 is Yes.
When the switch is turned on or the brake switch 25 is turned off, the ABS control ends (see FIG. 15).

Next, the subroutine of S53 will be described with reference to FIGS. 11 to 13 and 14 to 16. First
As shown in FIG. 16, the depressurization in the phase III of the cycle is performed by opening the relief valve 20b intermittently in five times from the first time to the fifth time. It is set with the opening time of 20b. The decompression level / decompression amount table illustrated in FIG. 14 describes the decompression start time of each decompression, the decompression level, and the decompression amount of each decompression. Decompression level DL, DM, DS, DV
S is set from the pressure reduction variable DV calculated by the following equation. DV = Slip amount Sm + kc × Absolute value of wheel speed deceleration Note that in the above equation, the slip amount Sm is (vehicle body speed Vr-wheel speed Vw) and kc is a predetermined constant. When k3 ≦ DV, decompression level = DL, (decompression level is large) When k2 ≦ DV <k3, decompression level = DM, (during decompression level) When k1 ≦ DV <k2, decompression level = DS, (decompression level) Small) When DV <k1, decompression level = DVS (small decompression level) For example, k3 = 0.25Vr, k2 = 0.10Vr, k1 =
It is 0.05 Vr.

In this way, the pressure reduction variable DV is calculated from the slip amount Sm and the wheel speed deceleration, and the pressure reduction levels DL, DM, DS, DVS are calculated from the pressure reduction variable DV and the vehicle body speed Vr.
The pressure reduction amount is determined from this pressure reduction level based on the map of FIG. 14, and in each pressure reduction, the pressure reduction is executed by outputting the braking control signal for opening the relief valve 20b for the time of the pressure reduction amount. In the flowchart of FIG. 11, first, when the pressure reduction variable DV and the pressure reduction level are calculated in S80, the continuation flag Fcn is then calculated in S81.
It is determined whether l is 0, the flag Fcnl is 0, and the first
In Phase III of the cycle, the process proceeds to S82 and S82
The determination regarding the flag F is executed in S84 to S84. When the flag F is 0 at the beginning, the process proceeds to S86, and the control signal for the initial pressure reduction is output. This initial decompression is a decompression of a predetermined amount (for example, decompression time 8 ms, decompression time 16 ms when road surface μ is high) regardless of the decompression level, and a control signal for opening the relief valve 20b for 8 ms or 16 ms is output.
Next, in S87, the flag F is set to 1, and the process returns. When the flag F is 1, the process proceeds from S82 to S88, and the depressurization amount of the second depressurization corresponds to the depressurization level.
Is calculated based on the map of
It is determined whether or not the time count T of the timer T started in 2 becomes 8 ms, and when T = 8 ms, a control signal for opening the relief valve 20b for the time of the pressure reduction amount is output in S90, and then in S91. After the flag F is set to 2, the process returns. That is, the second pressure reduction is performed subsequent to the first predetermined amount of pressure reduction.

When the road surface μ is high, [Note] in FIG.
As described in, the decompression amount of the second decompression is increased and corrected by +3 ms. Next, when the flag F = 2, the process shifts from S83 to S92, and it is determined whether or not the time T counted by the timer T is 40 ms. When T <40 ms, return is repeated until T = 40 ms. In step S94, the depressurization amount for the third depressurization is calculated based on the depressurization level and the map of FIG. 14, and then in S94, a control signal for opening the relief valve 20b for the time of the depressurization amount is output, and then in step S95.
Then, the flag F is set to 3, and the process returns. In other words, the third depressurization is 40 ms after the start of timer T
It will be executed from the time when it has passed. As shown in [Note] in FIG. 14, when the road surface μ is low, the decompression amount of the decompression after the third time is increased and corrected by +2 ms. Next, flag F
= 3, the process proceeds from S84 to S96, it is determined whether or not the time T counted by the timer T is 80 ms, and when T <80 ms, return is repeated. When T = 80 ms, S97
At 4th decompression, the decompression amount of the fourth decompression is calculated based on the decompression level and the map of FIG. 14, then a control signal for opening the relief valve 20b for the time of the decompression amount is output at S98, and then the flag F at S99. Set to 4 and return. That is, the fourth depressurization is executed when 80 ms has elapsed after the start of the timer T start.

Next, when the flag F = 4, the process proceeds from S85 to S100 and the time T of the timer T is 120 ms.
If T = 120 ms, the depressurization amount for the fifth depressurization is calculated based on the depressurization level and the map of FIG. 14, and then S102. At, the control signal for opening the relief valve 20b for the time corresponding to the pressure reduction amount is output.
Next, in step S103, the flag F is reset to 0 and the process returns. That is, the fifth depressurization is executed when 120 ms have elapsed after the start of the timer T. As a result of the determination in S81, if the continuation flag Fcnl is 1, that is, in the phase III after the second cycle, S1 in FIG.
Move to 04. In S104 to S106, the flag F is determined, and when the flag F is initially 0, S10 is selected.
In step 7, the decompression amount of the initial decompression is calculated. However, after the second cycle, as shown in FIG.
The decompression amount of the initial decompression is also calculated based on the decompression level and the map of FIG. Next, in S108, a control signal for opening the relief valve 20b for the time corresponding to the pressure reduction amount is output, and then in S109, the flag F is set to 1 and the process returns. When the road surface μ is high, the decompression amount of the initial decompression is increased and corrected by +3 ms.

Next, when the flag F is 1, the process proceeds from S104 to S110, and it is determined whether the time T of the timer T is 40 ms. If T <40 ms, return is repeated until T = 40 ms. Then, in S111, the depressurization amount of the second depressurization is calculated based on the depressurization level and the map of FIG. 14, then, in S112, the control signal for opening the relief valve 20b for the time of the depressurization amount is output, and then S1.
At 13, the flag F is set to 2, and the process returns. That is, the second depressurization is performed 40 times after the start of the timer T start.
It is executed from the time when ms has elapsed. When the road surface μ is low, the decompression amount of the second and subsequent decompressions is increased and corrected by +2 ms. Next, when the flag F = 2, S105 to S
The process proceeds to 114, determines whether the time T of the timer T is 80 ms, and repeats returning for T <80 ms,
When T = 80 ms, the depressurization amount of the third depressurization is calculated in S115 based on the depressurization level and the map of FIG. 14, and then in S116, a control signal for opening the relief valve 20b for the time of the depressurization amount is output, Next, S11
In step 7, the flag F is set to 3, and the process returns. In other words, the third decompression is 80ms after the start of timer T
It will be executed from the time when it has passed.

Next, when the flag F = 3, S106
To S118, the measured time T of the timer T is 120
It is determined whether or not it is ms, and the process returns repeatedly for T <120 ms. When T = 120 ms, 4 is returned in S119.
The depressurization amount of the second depressurization is calculated based on the depressurization level and the map of FIG. 14, and then in S120, a control signal for opening the relief valve 20b for the time of the depressurization amount is output,
Next, in step S121, the flag F is reset to 0 and the process returns. That is, the fourth depressurization is executed when 120 ms have elapsed after the start of the timer T start. here,
As a countermeasure when the road surface μ suddenly changes from high μ to low μ, in parallel with the subroutines of FIG. 11 and FIG.
The subroutine is executed. By the determination of S130,
Before the time T measured by the timer T has reached 40 ms, the process repeats returning and then, in S131, 40 ms ≦ T <
It is determined whether it is 80 ms, and if the determination is Yes, S13
Move to 2. In S132, it is determined whether or not the pressure reduction level is DL. When the pressure reduction level is DL and the degree of pressure reduction is high, a control signal for continuously opening the relief valve 20b to continuously reduce the pressure is output in S133, and thereafter. To return. When the pressure reduction level is lowered by the continuous pressure reduction and the determination in S132 is No, a control signal for stopping the continuous pressure reduction is output in S134, and then the process returns.

Next, when T ≧ 80 ms, the process proceeds from S131 to S135, where the pressure reduction level is D
When the pressure reduction level is DL and the degree of pressure reduction is high, a control signal for continuously opening the relief valve 20b to continuously reduce the pressure is output in S136, and then the process returns. When the pressure reduction level is lowered by the continuous pressure reduction and the determination in S135 is No, S1 is set.
Move to 37. In S137, it is determined whether or not the pressure reduction level is DM, and when the pressure reduction level is DM and the degree of pressure reduction is still high, a control signal for continuously opening the relief valve 20b for continuously reducing the pressure is output in S138,
Then return. If the pressure reduction level is lowered by the continuous pressure reduction and the determination in S137 is No, S139 is performed.
At, a control signal for stopping the continuous depressurization is output, and then the process returns. Next, the operation of the ABS control described above will be described with reference to the time chart of FIG. 15 by taking the ABS control for the first channel as an example. In the ABS non-controlled state during deceleration, the braking pressure generated by the depression operation of the brake pedal 16 gradually increases, and the rate of change of the wheel speed Vwl of the left front wheel 1 (deceleration DVwl).
Has reached -3G, the lock flag Flokl of the first channel is set to 1, and ABS is started from the time ta.
Control is started.

In the first cycle immediately after the start of this control, the frictional state value Mu is set to a value corresponding to the road surface frictional state, and various control threshold values are set according to the running state parameter. Next, the non-slip ratio S1, the wheel deceleration DVwl, and the wheel acceleration AVwl obtained from the wheel speed Vwl are compared with various control threshold values, and phase 0 to phase II are compared.
The braking pressure will be maintained at the level immediately after the pressure increase. When the non-slip rate S1 falls below the 2-3 intermediate slip rate threshold value Bsg, the phase shifts from phase II to III, and the relief valve 20b is turned on / off by the depressurization characteristic peculiar to the present application as described above, and from that time tb. The braking pressure decreases at a predetermined gradient, the braking force gradually decreases, and the rotational force of the front wheels 1 begins to recover. Further, when the braking pressure continues to be reduced and the wheel deceleration DVwl is reduced to the threshold value B35 (0G), the phase III is shifted to V and the braking pressure is maintained at the reduced pressure level from time tc. This phase V
When the non-slip rate S1 becomes equal to or higher than the 5-1 slip rate threshold value Bsz, the continuation flag Fcnl is set to 1, and the ABS control shifts from the time td to the second cycle. At this time, the phase is forcibly shifted to the phase I, and immediately after the shift to the phase I, the opening / closing valve 20a has the rapid pressure increase time Tpz set using the pressure increase time Ti of the previous cycle as a parameter as described above. While the relief valve 20b is closed, the opening / closing valve 20a is opened at a duty ratio of 100%,
The braking pressure is increased steeply, and after the rapid pressure increase time Tpz elapses, the on-off valve 20a is turned ON / OF at a predetermined duty ratio.
The braking pressure is gradually increased and the braking pressure gradually increases with a gentler gradient. Thus, immediately after the transition to the second cycle,
The braking pressure is reliably increased, and good braking pressure is secured.

On the other hand, even after the second cycle, an appropriate friction state value Mu is determined, and these friction state values Mu are determined.
Since various control threshold values corresponding to the running state parameters corresponding to the vehicle speed Vr and the vehicle body speed Vr are selected from the control threshold value setting table in FIG. 7, precise control of the braking pressure according to the running state should be performed. become. Then, in phase V in the second cycle, for example, when it is determined that the non-slip ratio S1 is larger than the threshold value Bsz, the process proceeds to phase I in the third cycle. In the ABS control of the present embodiment, as shown in FIG. 11, when the continuation flag Fcnl is 0, that is, in the pressure reducing phase of the first cycle, in S86, the pressure reducing amount of the first pressure reducing is set to the predetermined amount (opening the relief valve 20b. The time is set to 8 ms (however, 16 ms when the value is high) and the pressure reduction is performed. Therefore, the minimum necessary location is not affected by the unstable slip ratio and wheel speed deceleration at the start of ABS control. A fixed amount of initial decompression can be performed. The above is a description of the contents of ABS control generally performed for the first, second and third channels. TECHNICAL FIELD The present invention relates to an anti-skid brake device provided with an integrated control system in which common hydraulic control is performed for left and right wheels.

Therefore, in the anti-skid brake device of this embodiment, the present invention can be effectively applied to the ABS control of the rear wheels. In the anti-skid brake device of this example, the ABS control of the rear wheels is executed by the hydraulic control system of the third channel as described above. In the present invention, the rear wheels 3, 4
The content of the ABS control is changed according to the lock state of No. 1, and the integrated control is controlled so as to reflect the behaviors of both the target rear wheels 3 and 4 as much as possible. Hereinafter, description will be given with reference to the flowchart of FIG. The control unit 24 uses the procedure performed in step S46 in FIG. 9 described above to determine that the deceleration of the rear wheels 3 and 4 is the threshold value D0.
It is determined whether or not (for example, -3 G or less), and when it exceeds the threshold value D0, the lock flag Flok1 is set to 1 and the ABS control is started (step S1). As a result, the brake hydraulic pressure of the third channel is reduced.
Then, in step S2, it is determined whether or not both the rear wheels 3 and 4 are locked. Step S2
The determination in 1 is performed in a state where any one of the rear wheels 3 and 4 is already in the locked state. When determining whether the other wheel is also locked, the control unit 24 may set the threshold value of the non-slip ratio S1 to the 2-3 non-slip ratio threshold B _sg to be the same as the threshold value D0, but is preferably small. Set to a high value.

In this example, as shown in FIG.
3 It is set to a value closer to the vehicle speed by 2% than the non-slip ratio threshold Bsg. Then, with respect to the threshold value close to the vehicle speed Vr, when the other wheel, that is, the wheel which is not the wheel in which the first lock state is detected in step S2, is further determined to be in the lock state, the decompression amount is set. Control to increase (step S
3). In this way, when the second lock state is detected and the pressure reduction amount is set to be large, the pressure increase amount in the next pressure increase phase is controlled to increase. This depressurization amount increase control is performed by adding 4 ms to each depressurization time of the depressurization levels DL, DM, DS, DVS calculated by the procedure described above with reference to FIG. Then, according to the finally calculated depressurization time, the control unit 24 depressurizes at a predetermined timing (in this example, depressurization is performed five times in the first cycle of ABS control and depressurized four times in the second cycle). Depressurize. That is, the control unit 24 controls the pressure reduction level D
The pressure reducing control is executed by outputting the braking control signal for opening the relief valve 20b for the pressure reducing time corresponding to L, DM, DS, and DVS.

In the judgment of step S2, the first
When it is determined that the vehicle is in the locked state, that is, when the non-slip ratio S1 of one of the rear wheels 3 and 4 related to the third channel is equal to or less than the predetermined threshold value D0, the first lock is performed. 16 to FIG.
The normal ABS control described in relation to (1) is performed (step S4). By this control, when it is determined that either one of the rear wheels 3 and 4 is in the first lock state in which the rear wheels 3 and 4 are in the lock state, the pressure reduction control in the normal pressure reduction phase is performed,
And the non-slip ratio threshold B in which one of the rear wheels 3 and 4 is determined to be in the first lock state and the other is further changed 2-3
When it is determined that sg is in the locked state, the pressure reduction amount is increased and the pressure reduction control is performed. That is, when only one of the rear wheels 3 and 4 is in the locked state, the pressure reduction control is performed at a normal level. The reason for this is
This is because the locked state of the wheel sump on one side is considered to be relatively shallow, and therefore the gripping force of the wheel is likely to be recovered without performing large pressure reduction control. If the amount of pressure reduction is excessively increased, the subsequent pressure increasing operation tends to be delayed,
This is because the braking performance of the ABS control will deteriorate. When only one of the wheels is in the locked state, the other wheel is not in the locked state and holds the grip force. This is because it is contrary to the original purpose of the ABS control, and the braking performance is similarly deteriorated.

However, when both the rear wheels 3 and 4 are in the locked state, that is, first, one of the rear wheels 3 and 4 is in the first position.
The locked state is reached, and then the locked state is comparatively deep when the other wheel enters the locked state without canceling this locked state, and it is unlikely that the gripping force can be recovered by normal level depressurization control. In view of this, when both rear wheels 3 and 4 are in the locked state, in this example, the pressure reduction is increased. From another point of view, when both wheels are in the locked state, it means that the gripping force of the rear wheels 3 and 4 is impaired as a whole, so that the running stability of the vehicle is also improved. This is because it is necessary to recover the grip force quickly. As described above, the rear wheels 3, 4 are controlled by the control of this example.
The ABS control of the vehicle is an accurate ABS according to the situation of the behavior of each wheel within the range of the integrated control common to both.
Control can be achieved.

[0046]

As described above, according to the present invention,
In the anti-skid brake device that performs ABS integrated control of the left and right wheels, the state of each wheel is detected and the ABS integrated control with different contents is performed according to the state, so compared to the conventional ABS integrated control device. As a result, the locked state of the wheels can be recovered more quickly, and thus an anti-skid brake device with improved braking performance can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an anti-skid brake device for a vehicle according to an embodiment.

FIG. 2 is a diagram of a μ table.

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 part of a flowchart of a control signal output process.

FIG. 10 is the rest of the flowchart of the control signal output process.

FIG. 11 is a part of a flowchart of a control signal output subroutine of S53 of FIG.

12 is the rest of the flowchart of the control signal output subroutine of S53 of FIG.

FIG. 13 is a flowchart of a control signal output subroutine executed in parallel with FIGS. 11 and 12.

FIG. 14 is a diagram of a pressure reduction level / pressure reduction amount table.

FIG. 15 is an operation time chart of the anti-skid brake device.

16 is an operation time chart of Phase III in the first cycle of FIG.

FIG. 17 is a flow chart of control for setting conditions when performing ABS integrated control of the anti-skid brake device.

FIG. 18 is a graph showing the relationship between the 2-3 non-slip ratio threshold value B _sg and the vehicle body speed in the ABS integrated control.

[Explanation of symbols]

 1, 2 Front wheels 3, 4 Rear wheels 11-14 Brake device 15 Brake control system 27-30 Wheel speed sensor 20, 21, 23 1st-3rd valve unit 20a, 21a, 23a Open / close valve 20b, 21b, 23b Relief valve 24 control unit

Claims (3)

[Claims] 1. Wheel speed detection means for respectively detecting rotational speeds of at least left and right wheels, hydraulic pressure adjustment means for adjusting brake hydraulic pressure for performing integrated control of braking force for the left and right wheels, and at least the brake hydraulic pressure. A first anti-skid brake control means for performing hydraulic control including a pressure increase phase increasing and a pressure decrease phase decreasing by the hydraulic pressure adjusting means, and a first wheel indicating that one of the left and right wheels is locked. First lock state detecting means for detecting a lock state, second lock state detecting means for detecting a second lock state indicating that both the left and right wheels are in a lock state, and the second lock state is detected When the first lock state is detected, compared with when the first lock state is detected, the pressure reduction control for rapidly decreasing the brake hydraulic pressure in the pressure reduction phase is performed. Antiskid brake apparatus for a vehicle, characterized in that a positive means. 2. The antiskid brake device according to claim 1, wherein the antiskid brake control means starts control when the first lock state is detected. 3. The method according to claim 1, further comprising detecting the lock state of the other wheel when the first lock state of one of the left and right wheels is determined and the anti-skid brake control is started. When the second lock state is brought about by the above, the lock determination threshold value for determining the lock state of the other wheel is set to a threshold value lower than the determination threshold value for the first lock state. Brake device.