JPH0536780Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Object of the Invention] (Field of Industrial Application) The present invention relates to an anti-skid brake device that can appropriately operate an inlet valve that increases braking force.

(Prior Art) In recent years, many vehicles have been equipped with anti-skid brake devices that reduce the braking force when the wheels tend to lock to prevent the wheels from locking during braking.

Such an anti-skid brake device is known from Japanese Patent Laid-Open No. 7747/1983.

(Problem to be solved by the invention) Since the device disclosed in the above publication performs control according to the wheel deceleration, the brake hydraulic pressure is controlled according to the coefficient of friction that dynamically occurs between the road surface and the wheels. It simply controls the brake hydraulic pressure during pressure increase so that maximum brake efficiency can be obtained.

Furthermore, since the above publication requires that the wheel deceleration αw exceeds a predetermined value −α1 for the start of pressure increase, the wheel deceleration αw at the start of pressure increase should be almost constant regardless of the road surface condition. , the initial pressure increase amount corresponds to a value near the predetermined value - α1. Therefore, it is impossible to set the initial value of the pulse width of the inlet valve according to the road surface friction coefficient.

This invention was developed in view of the above points, and its purpose is to set the initial value of the pulse width of the inlet valve according to the coefficient of friction of the road surface, and to appropriately operate the inlet valve that increases the braking force. An object of the present invention is to provide an anti-skid brake device that can perform the following steps.

[Structure of the invention] (Means for solving the problem) A wheel speed sensor that detects wheel speed from the rotation of the wheel, and a deceleration calculation means that calculates the deceleration of the wheel speed output from the wheel speed sensor. , a pseudo vehicle speed calculation means that separates the pseudo vehicle speed from the wheel speed according to the deceleration outputted from the deceleration calculation means, and a pseudo vehicle speed calculated from the previous separation speed and the current separation speed of the pseudo vehicle speed. Friction coefficient calculation means for calculating a friction coefficient of a road surface based on vehicle body deceleration;
It is equipped with means for setting an initial value of a pulse width indicating the opening time of an inlet valve that is intermittently driven when increasing the braking force of the anti-skid brake in accordance with the friction coefficient, and gradually decreasing the subsequent pulse width. This anti-skid brake device is characterized by:

(Function) In addition to the friction coefficient calculation means that calculates the friction coefficient of the road surface based on the car body deceleration obtained from the previous separation speed and the current separation speed of the pseudo vehicle speed, the inlet is intermittently driven when increasing the braking force. The initial value of the pulse width, which indicates the opening time of the valve, is set according to the above-mentioned friction coefficient, and this makes it possible to generate an appropriate braking force from the beginning when increasing the braking force according to the friction coefficient of the road surface. Sufficient braking force can be exerted within a range that does not cause premature wheel locking.

(Embodiment) An anti-skid brake device for a four-wheel drive vehicle according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the structure of an anti-skid brake system for a four-wheel drive vehicle having two channels of brake system piping. In FIG. 1, WF1 is the right front wheel, WF2 is the left front wheel, WR1 is the right rear wheel, and WR2 is the left rear wheel. The rotational speed of the front right wheel WF1 is detected by a wheel speed sensor 11, and the rotational speed of the front left wheel WF2 is detected by a wheel speed sensor 12. In addition, the front right wheel WF1 and the rear left wheel WR2 have the same channel piping BL1.
The front left wheel WF2 and the rear right wheel WR1 are connected to the piping BL2 through the same channel.
Interposed by In addition, the above piping BL1, BL2
Master cylinders 13 and 14 are interposed therein. An operation signal for the brake 15 is input to the master cylinders 13 and 14, and the operation signal is input to the microcomputer 16. Further, 16 is a microcomputer, and the wheel speed sensor 1 is
Wheel speed pulses RP and LP output from 1 and 12
is input, and the master cylinder 13,1
4, a control signal for opening and closing a valve, which will be described later, is output. Further, 17 is a warning lamp that indicates an abnormality in the device.

Next, one of the two channels of piping described above will be described with reference to FIG. 2. In FIG. 2, pressure oil is sent from a master cylinder to a front wheel cylinder and a rear wheel cylinder via a shutter valve (SV) 21 and a hydraulic control valve (PCV) 23. The upstream and downstream sides of the shut valve 21 are connected by a differential pressure switch 22. This differential pressure switch 22 is turned on when a differential pressure of a predetermined value or more occurs between the upstream side and the downstream side of the shut valve 21. Further, 24 is an accumulator in which pressure oil is stored, and the pressure oil stored in this accumulator 24 is transferred to an inlet valve (IV) 25,
It is sent to the front wheel cylinder and rear wheel cylinder via the PCV 23. Further, the pressure oil discharged from the front and rear wheel cylinders is discharged to the reservoir 27 via the PCV 23 and the outlet valve (OV). A brief description of normal brake operation and anti-skid brake operation will be given below. In the case of normal braking operation,
Valve SV is open and valves IV and OV are closed. Therefore, by stepping on the brake 15, the pressure oil generated in the master cylinder 13 is sent to the front and rear wheel cylinders via the valve SV, and the brakes are applied. On the other hand, when anti-skid brake (ASB) is applied, valve SV is closed. And the valve
When only IV is opened, pressure oil from the accumulator 24 is sent to the front wheel cylinder and rear wheel cylinder to apply the brake.
When only valve OV is opened, the pressure oil in the front wheel cylinder and rear wheel cylinder is sent to the reservoir 27, so the braking force is relaxed.

Next, the microcomputer 16 has RAM
(not shown), and this RAM has flags as shown in FIGS. 3 to 5. In Figure 3, flag A (right) is the flag for the right channel,
Flag B (left) shows the stored contents of the flag for the left channel. Here, FGWM is a G flag during overshoot, FUST is an undershoot flag that is set to "H" when undershoot, and FOST is an overshoot flag that is set to "H" during overshoot.

FIG. 4 shows flags indicating opening and closing of outlet valves, inlet valves, etc. In FIG. 4, flag C is the flag for the right channel;
Flag D is the flag for the left channel. Here, FREL is the outlet flag, FIN
is the inlet flag, FEND is the END flag,
FASB is a flag indicating that the anti-skid brake (ASB) is in operation.

Next, FIG. 5 shows a memory in which the flags NEXT, LOFF, and ROFF necessary for controlling the valve are set. The LOFFF flag or ROFF flag is set to whichever is turned off next, and the NEXT flag is set when the right and left valves are turned on.

Next, FIG. 6 shows data set in ports 1, 2, A, and B of the microcomputer 16 that controls this device.

Next, the operation of an embodiment of the present invention configured as described above will be explained. The overall operation of this apparatus performed by the microcomputer 16 will be explained with reference to the flowchart shown in FIG.
First, initialization is performed (step S11),
Wheel speed pulses output from wheel speed sensors 11 and 12 are taken into microcomputer 16. This wheel speed pulse acquisition process is carried out in the eighth
This will be described later with reference to the drawings. Next, step S12 above
The acquisition of wheel speed pulses performed by
This is carried out for 14 msec, and when it is carried out for 14 msec (step S13), the wheel speed VW is calculated (step S14). This wheel speed VW calculation is 14ms
Wheel speed pulse RP input at (set time),
It is calculated by counting the LP and taking into account the effective radius of the tire, etc. Next, as a filter process, a process for quickly converging the wheel speed VW is performed (step S15). Next, the wheel deceleration GF is calculated (step S16). This deceleration is calculated by calculating the temporal change in the wheel speed VW determined in step S15. Then, calculation of the pseudo vehicle speed VP, which will be explained with reference to the flowchart in FIG.
S17). And ASB (anti skid brake)
As preprocessing, calculation of DV=VP-VW, etc. is performed (step S18). Thereafter, ASB processing, which will be described in detail later using FIG. 10, is performed. This ASB process includes opening and closing of valve SV, calculation of pulse widths for setting the opening times of valves IV and OV, etc. (step S19). Next, processing is performed to monitor the internal calculation results externally (step S20).
After 5.6 ms, valves IV and OV are controlled to open (step S21) as output processing, the details of which will be described later with reference to FIG. After the set time has elapsed, valves IV and OV, which were controlled to open in step S21, are opened as shown in the flowchart of FIG.
Control is performed to close the OV (step S22). ASB processing is performed in this way. and,
After 0.4ms (step S23), the above step
Return to processing in S12.

Next, the wheel speed pulse acquisition process will be described with reference to FIG. First, it is determined whether the pulse input to the microcomputer 16 is the wheel speed pulse RP output from the right wheel speed sensor 11 (step S31). If it is determined as [YES] in this step S31, the wheel speed pulse RP is inputted into the microcomputer 16 by the time ICR
1 is stored in the memory area TMRR2, and the pulse counter PC1 is incremented by 1 (step S32).
Then, it is determined whether the pulse counter PC1 is "1", that is, whether the first pulse has been input to the microcomputer 16 (step S33). If the determination in step S33 is ``YES'', the time at which the pulse stored in the memory area TMRR2 was entered is stored in the memory area TMRR1 (step S34). Next, it is determined whether the pulse input to the microcomputer 16 is the wheel speed pulse LP output from the left wheel speed sensor 12 (step S35). If it is determined as "YES" in this step S35, the time ICR2 when the wheel speed pulse LP was input to the microcomputer 16 is stored in the memory area.
It is stored in TMRL2, and pulse counter PC2 is incremented by "+1" (step S36). Then, it is determined whether the pulse counter PC2 is "1", that is, whether the first pulse has been input to the microcomputer 16 (step S37). If it is determined as "YES" in this step S37, the memory area TMRL
The time when the pulse entered which is stored in 2 is the memory area.
Stored in TMRL1. And the above steps
The processing in steps S31 to S38 is continued until it is determined as "YES" in step S13 in FIG. 7 and the elapse of 14 msec is confirmed. In this way, the time when the pulse from the right wheel speed sensor 11 is input to the memory area TMRR1 is determined by the memory area TMRR1.
The time when the pulse from the left wheel speed sensor 12 is input to TMRL1 is set.

Next, calculation of the pseudo vehicle speed VP will be explained with reference to the flowchart of FIG. First, it is determined whether there is an undershoot, that is, whether the undershoot flag FUST is at the "L" level. During the period indicated by a in FIG. 11, undershooting has not yet occurred, so the determination is ``YES'', and it is determined whether the timer NUST, which counts the undershoot time of the wheel speed VW, is ``0''. Since the undershoot in Figure 13 has not occurred, the timer
Since NUST is "0", the process advances to step S43, where the timer NUST is set to 0, and the undershoot time JST of the previous time is also set to "0".

Next, whether the wheel deceleration GF is greater than 1.5g,
In other words, it is determined whether the wheel speed VW is in a state of acceleration. Here, if the wheel speed VW is accelerated as shown by b in Fig. 14, it is determined that the wheel is idling, and the overshoot flag is
FOST is set to “H” level and pseudo vehicle speed VP
is set to the wheel speed VW (step S45). On the other hand, if the determination in step S44 is "NO", it is determined whether the wheel deceleration GF is smaller than -1.5g (step S46). That is, this is the case when the brake is applied and the wheel speed VW is decreasing with negative acceleration. If the determination in step S46 is "NO", the wheel speed VW has a positive acceleration (1.5g) and a negative acceleration (-1.5g).
g) is not increased or decreased, so in the period shown by a in Fig. 13, the pseudo vehicle speed is
VP is assumed to be the same value as the wheel speed VW (step
S47).

By the way, if "YES" is selected in step S46 above,
If it is determined that the brake 15 has been depressed, it is determined based on the operation signal from the brake 16 (step S48). For example, at time t1 in FIG. 13, when the wheel deceleration GF<-0.5g, the brake 16
is depressed, an undershoot of the wheel speed VW is detected. Therefore, the undershoot flag FUST is set to “H” level,
The previous undershoot time NUST0 is set to the previous undershoot time JST, and the undershoot timer is set to the previous undershoot time NUST0.
The count value of NUST is set, and the undershoot timer NUST is set to “1” (step
S49). And the undershoot timer from the time before last.
It is determined whether NUST0 is "0" (step S50).
Here, since NUST0=0, VW is set to the previous pseudo vehicle speed VP0 (step S51).
Then, the estimated road surface μ is set to 1, the previous estimated road surface μ is set to 1, and the previous undershoot timer is set to 1.
NUST0 is set to 7 (step S52). Thereafter, the processes from step S41 onwards are repeated.

Since the undershoot flag FUST is already at the "H" level in the determination at step S41, the determination is "NO" and the pseudo vehicle speed is
VP is calculated (step S53). That is, the time
From t1, the pseudo vehicle speed VP is separated from the wheel speed VW. Then, it is determined whether the pseudo vehicle speed VP<0 (step S54), and if "NO", the undershoot timer NUST is incremented (step S55). On the other hand, pseudo vehicle speed VP<
If it is 0, VP is set to 0 (step S56).
Next, there is an undershoot timer NUST<35,
As long as VP>VW (steps S57, S58), the processes from step S41 onward are repeated, and the pseudo vehicle speed VP is updated (step S53).

By the way, if the undershoot timer FUST≧35, that is, if VW does not match VP even after 0.7 seconds have passed since the pseudo vehicle speed VP was separated from the wheel speed VW, as shown by z in Fig. 13, It is determined that the estimation of the pseudo vehicle speed VP is incorrect, the undershoot flag FUST is reset, the estimated road surface μ is set to "1" (step S59), and the pseudo vehicle speed VP is set to be equal to the wheel speed VW (step S59).
S60). Also, at time t2 in Fig. 13, “VP=
VW”, so the judgment in step S58 is “NO”.
It is determined that the above step S59 and S60 are executed.
The undershoot flag FUST is reset, and the pseudo vehicle speed VP is set to be equal to the wheel speed VW. In other words,
Between time t2 and t3 in Figure 13, the pseudo vehicle speed VP
is matched with wheel speed VW.

Below is the time when the second undershoot occurs.
At t3, ``YES'' is determined in steps S46 and S48, and processing such as storing the contents of the undershoot timer NUST in the previous undershoot time NUST0 is performed (step
S49). Therefore, the judgment in step S50 is "NO".
It is determined that the coefficient of friction MU of the road surface is calculated (step S53). The calculation formula in step S53 uses the deceleration of the vehicle body obtained by dividing the difference between the previous separation speed VPO and the current separation speed VW by the time period NST0-1. Here, the deceleration of the vehicle body depends on the road surface μ since the braking performance with almost maximum efficiency is exhibited during the anti-skid control. Below, VP0
=VW, and the process returns to step S41 and thereafter, and the same process as the first undershoot is repeated.

Next, ASB processing will be explained with reference to FIG. First, it is determined whether the flag FASB is at the "H" level, that is, whether the anti-skid brake is operating (step S71). Then the flag FEND
It is determined whether the anti-skid brake is at the "H" level, that is, whether the anti-skid brake has been completed (step S72).
If this is the first time you have come to this ASB process, the determination in steps S71 and S72 above will be "NO", and the process will proceed to step S71 and S72.
Proceed to processing after S73. If the brake is being depressed and the pseudo vehicle speed VP obtained in step S53 of Fig. 9 is greater than 7 km/h (steps S73 and S74), the pulse width to open valve IV or valve OV is determined. PW is determined (step S75). Calculation of this pulse width PW will be described later using FIGS. 15 to 18. Then, it is determined whether the pulse width PW≧10 (step S76). Then, if the pulse width PW≧10, the flag FASB is set to the “H” level (step S77), the shut valve SV is turned on (step S78), and the master cylinder 13 and PCV are turned on (step S78).
23 is shut off, and the braking force applied to the rear wheel cylinder or front wheel cylinder is controlled by opening/closing IV 25 or OV 26. Then, the timer TPSW, which counts the time that the differential pressure switch 22 is on, is reset and counting starts (step S79). Hereinafter, in the output process described later with reference to FIG. 11, opening/closing control of the IV 25 and OV 26 is performed to perform anti-skid brake processing. By the way, if the determination in step S76 is "NO", the anti-skid brake process will not be performed, so the pulse width PW and the undershoot timer NUST are set to "0" (step S80), and the undershoot flag is set. FUST, inlet valve FIN, and outlet flag FREL are all set to L level (step S81).

In addition, when the ASB process is executed again after the actual anti-skid brake process has been performed in the output process described later, the flag FASB is set, so it is determined as "YES" in step S71 and the process from step S82 onward is executed. move on. This step
In S82, it is determined whether the brake is depressed. If the brake is not depressed, there is no need to perform the anti-skid brake process, and therefore a process is performed to end the anti-skid brake operation. That is, the pulse width PW is set to 0 (step S83), the inlet flag FIN is set to L, and it is set that there is no need to send pressure oil to the rear wheel cylinder and the front wheel cylinder (step S84). Furthermore, the flag FASB=L
Therefore, it is set that the anti-skid brake is not operating (step S85), and the flag FEND=
H, and it is set that the anti-skid brake operation is completed (step S86). below,
The flag FREL is set to “L” (step
S87).

On the other hand, if it is determined in step S82 that the brake is depressed, the pseudo vehicle speed is
It is determined whether VP<7Km/h (step
S88). Here, if it is determined that the pseudo vehicle speed VP is less than 7 km/h, the anti-skid brake is applied, and it is determined that the vehicle speed is decreasing, PW = 10 is set (step S89), and the engine speed is reduced. The let flag FIN is set to the "H" level (step S90), and through steps S85 to S87, it is set that this is the final anti-skid brake operation.

On the other hand, in step S88 above, the pseudo vehicle speed is
If it is determined that VP≧7 Km/h, it is determined whether the differential pressure switch timer TPSW is <50, that is, less than 1 second (step S91). If "1" second has elapsed since the anti-skid brake was activated, the differential pressure switch timer TPSW is set to "0" (step S92) when it is determined that there is a certain amount of pressure, and the process starts from step S83 above. Proceed to process
The anti-skid brake process is completed. On the other hand, if it is determined in step S91 that "1" second has not elapsed since the anti-skid brake was activated, the pulse width PW is calculated in the same manner as in step S75 (step
S93). Then, it is determined whether TIN≠0, that is, inlet is in progress (step S94). When it is determined that the inlet is in progress, it is determined whether the differential pressure switch (PSW) 22 is on (step S95), and if it is on, the differential pressure switch timer TPSW is incremented (step S95).
S96). Then, the pulse width PW is set to 0 (step S97), and the inlet flag FIN is set to "L" (step S98). On the other hand, if the determination in step S95 is "NO", the differential pressure switch timer TPSW is set to "0" (step S99).

By the way, if the end flag FEND has already been set to the "H" level when the ASB processing is started, the determination in step S72 is "YES". Then, the process proceeds to step S100, where it is determined whether the differential pressure switch 22 is off, and if it is off, the end flag FEND is set to the "L" level (step S101), and the shut valve (SV) 21 is set to the "L" level. is turned off, and the anti-skid brake operation is ended (step S102). Subsequent braking operations are performed by sending pressure oil from the master cylinder 13 to the rear wheel cylinder or front wheel cylinder.

On the other hand, if it is determined in step S100 that the differential pressure switch 22 is on, the pulse width PW is set to "10" (step S103),
The inlet flag FIN is set to the "H" level and the process proceeds to the subsequent steps (step S104).

Next, step S75 in FIG. 10 above or
Pulse width, which is the time to open the inlet valve (IV) or outlet valve (OV), with reference to Figures 15 to 17 performed in S93.
We will explain how to calculate PW.

First, a first method for calculating the pulse width PW that determines the time to open the outlet valve (OV) will be explained with reference to FIG. In this case, the coefficient M1 obtained from the characteristic diagram of DV (= VP - VW) - M1 in Fig. 15A and GF - in Fig. 15B
The smaller one of the coefficients M2 obtained from the characteristic diagram of M2 is selected as the coefficient M3, and the pulse width PW is calculated from the pulse width PW-M3 characteristic diagram shown in FIG. 15C. This pulse width PW is 10≦PW≦20
value is adopted. In this way, coefficient M1 and coefficient M2
By adopting the smaller of the two, it is possible to prevent the brake from loosening too much.

Next, a second method for calculating the pulse width PW that determines the time to open the outlet valve (OV) will be explained with reference to FIG. In this case, determine the coefficient M4 from the DV-M4 characteristic diagram, and
The pulse width PW is calculated from the PW-M4 characteristic diagram shown in Figure B. In this case, a time of 10≦PW≦15 msec is adopted.

Next, a third method for calculating the pulse width PW that determines the time to open the outlet valve (OV) will be explained with reference to FIG. In this case, if the pseudo vehicle speed VP is equal to or greater than the threshold value V×3, 20 msec is adopted as the pulse width PW.

Next, the calculation of the pulse width PW performed in step S93 in FIG. 10 described above will be explained. When applying the anti-skid brake, the inlet valve (IV) 25 is opened to generate braking force.
Initial value of pulse width PW corresponding to opening time
PW0 (first time) changes depending on the magnitude of the road surface μ as shown in FIG. Then, the pulse widths PW1, PW2, ..., from the second time onwards are PW _o = PW _o-1 -1
are calculated sequentially. By the way, the time to open the inlet valve 25 is determined by the pulse width PW, and the time interval Tin for opening the inlet valve 25 is determined by the GF in period c when the anti-skid brake is loosened, as shown in FIG. Memorize the maximum value (Max GF) of
The inlet interval Tin is calculated from FIG. 20 according to GF. In this way, the larger the acceleration GF of the wheel speed VW, the shorter the inlet interval Tin is to apply the anti-skid brake.

Next, the output processing shown in FIG. 7 will be explained with reference to FIG. 11. First, the VOFF flag shown in Fig. 5 is cleared to "0", the pulse width PW for the right channel is converted to the unit of μs TVR, and the pulse width for the left channel is
TVL obtained by converting PW into μs units is set to "0" (step S110). If the pulse width PWR for the right channel is not "0", the pulse width PWR is converted into units of μs and stored in the TVR (steps S111 and S112). Similarly, the pulse width PWL for the left channel is "0".
If not, the pulse width PWL is converted into μs units and stored in TVL (step S113,
S114). If TVR and TVL are not "0" (step S115), the process advances to steps S119 and subsequent steps, and the valves of the right channel and the left channel are also turned on. Further, if only the TVR is not "0" (step S116), the process advances to steps S134 and subsequent steps, and a process for turning on only the valve of the right channel is executed. On the other hand, if only TVL is not "0" (step S117), the process advances to steps S140 and subsequent steps, and processing for turning on only the valve of the left channel is executed. When the above processing is completed, interrupts are prohibited and the process returns to the main routine (step S118).

Hereinafter, the process of controlling the valves of the right channel and the left channel to perform the anti-skid brake operation, which is performed in the process after step S119, will be explained. First, it is determined whether "TVR<TVL" (step S119). This step S119
If it is determined as “YES”,
DTV = TVL - TVR is calculated (step
S120). And outlet flag FREL=H
(Step S121). Here, if the determination in step S121 is "NO", the inlet valve IV25 of the right channel is turned on (opened), and the brake is applied via the right channel (step S122). On the other hand, if the determination in step S121 is ``YES'', the right outlet valve OV26 is turned on (opened) and the brake is released via the right channel (step S123). Above steps
After the brake is applied or released in S122 or S123, among the VOFF flags shown in Fig. 5, NEXT is set to "H" level, LOFF is set to "L" level, and ROFF is set to "H" level. “The level is set. Setting "H" to NEXT means that the left and right channel valves are operated. Further, by setting the "H" level to ROFF, it is indicated that the valve of the right channel is turned off first. and,
Free running counter FRC + TVR on ΦCR2
(Step S125). Then, interrupt permission is issued to ΦCR2 and the process returns to the main routine (step S126).

If the determination in step S119 is "NO", DTV=TVR-TVL is calculated (step S127). Then, it is determined whether the outlet flag FREL=H (step S128). Here, if the determination in step S128 is "NO", the inlet valve of the left channel
IV25 is turned on (opened) and the brake is applied via the left channel (step S129).
On the other hand, if the determination in step S128 is "YES", the left outlet valve OV
26 is turned on (opened) and the brake is released via the left channel (step S130). After the brakes are applied or released in steps S129 to S130, the brakes shown in FIG.
Among the VOFF flags, NEXT has “H” level,
The "H" level is set for LOFF, and the "L" level is set for ROFF. Further, by setting the "H" level to ROFF, it is indicated that the valve of the left channel is to be turned off first. And ΦCR2
Then, the free running counter FRC+TVL is set (step S132). Then, interrupt permission is issued to ΦCR2 and the process returns to the main routine (step S133).

Next, when driving the valve of the right channel (if determined as "YES" in step S116)
Then, it is determined whether the outlet flag FREL is "H" (step S134). And the above steps
If S134 is determined to be “NO”, the inlet valve IV25 of the right channel is turned on (opened).
and the brake is applied via the right channel (step S135). On the other hand, if the determination in step S134 is ``YES'', the outlet valve OV26 of the right channel is turned on (opened), and the brake operation is relaxed through the right channel (step S136). Next, as shown in Figure 5
Among the VOFF flags, NEXT has “L” level,
The "L" level is set for LOFF, and the "H" level is set for ROFF. Furthermore, by setting ROFF to the "H" level, it is indicated that the valve of the right channel will be turned off next (step S137).
And a free running counter in ΦCR2
FRC + TVR (step S138). and,
Interrupt permission is issued to ΦC2 and the process returns to the main routine (step S138).

Next, when driving the valve of the left channel (if determined as "YES" in step S117)
Then, it is determined whether the outlet flag FREL is "H" (step S140). And the above steps
If S140 determines “NO”, inlet valve IV25 of the left channel is turned on (opened).
and the brake is applied via the left channel (step S141). On the other hand, if the determination in step S140 is YES, the outlet valve OV26 of the left channel is turned on (opened), and the brake operation is relaxed through the left channel (step S142). Next, as shown in Figure 5
Among the VOFF flags, NEXT has “L” level,
The "H" level is set for LOFF, and the "L" level is set for ROFF. Furthermore, by setting the "H" level to LOFF, it is indicated that the valve of the left channel will be turned off next (step S143).
And a free running counter in ΦCR2
FRC + TVL (step S144). and,
Interrupt permission is issued to ΦC2 and the process returns to the main routine (step S145).

Next, the above steps S125, S132, S138, S144
When the time set in ΦCR2 comes, the valve closing process shown in the flowchart of FIG. 12 is performed. The processing will be explained below. First, it is determined whether ROFF is "H" (step S150). If it is determined as “YES” in this step S150, the right inlet valve IV25
And outlet valve OV26 is turned off (closed). (Step S151). Next, it is determined whether NEXT=H (step S152). This step S152
If the judgment is “NO”, LOFF=ROFF
=NEXT=L and interrupts are prohibited (step S154).

On the other hand, if it is determined as "YES" in this step S152, LOFF=H, ROFF=NEXT=L
This indicates that the left valve also needs to be turned off (step S155). And ΦCR2
=ΦCR2+DTV and returns to the main routine (step S156). This causes the left valve to turn off later, with a delay of DTV.

If the determination in step S150 is "NO", the left inlet valve IV25 and outlet valve OV26 are turned off (closed).
(Step S157). Next, it is determined whether NEXT=H (step S158). In this step S158,
If the judgment is “NO”, LOFF=ROFF=
NEXT=L and interrupts are prohibited (step S159).

On the other hand, if the determination in step S158 is ``YES'', ROFF=H and LOFF=NEXT=L are set, indicating that the valve on the right side also needs to be turned off (step S161). And ΦCR2=
ΦCR2+DTV is set and the process returns to the main routine (step S162). This causes the right valve to turn off later, with a delay of DTV.

In addition, in the calculation of the pseudo vehicle speed shown in FIG. 9 in the above example, the threshold value of the deceleration GF is 1.5.
g, but the deceleration was changed as shown in Figure 21.
The GF threshold value may be increased in proportion to the road surface μ. In this way, the deceleration GF is set small on slippery low μ roads, and
It can be set high on the road, and anti-skid braking can be applied effectively on any road surface.

[Effects of the invention] As detailed above, according to the invention, there is provided a friction coefficient calculation means for calculating the friction coefficient of the road surface based on the vehicle deceleration obtained from the previous separation speed and the current separation speed of the pseudo vehicle speed. At the same time, the initial value of the pulse width, which indicates the opening time of the inlet valve that is intermittently driven when increasing the braking force, is set according to the above-mentioned coefficient of friction, thereby increasing the braking force according to the coefficient of friction of the road surface. It is possible to provide an anti-skid brake device that can generate appropriate braking force from the initial stage of strengthening and can exert sufficient braking force within a range that does not cause early wheel locking.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an anti-skid brake device for a four-wheel drive vehicle according to an embodiment of the present invention, and FIG. 2 is a diagram showing brake piping for one channel.
3 shows the configuration of flags A and B, FIG. 4 shows the configuration of flags C and D, FIG. 5 shows the configuration of the VOFF flag, and FIG. 6 shows the configuration of ports 1, 2,
A diagram showing the configuration of A and B, FIG. 7 is a flowchart showing the overall operation, FIG. 8 is a flowchart showing the intake of wheel speed pulses, FIG. 9 is a flowchart showing calculation of pseudo vehicle speed, Fig. 10 is a flowchart showing the anti-skid brake (ASB) processing, Fig. 11 is a flowchart showing the output processing, Fig. 12 is a flowchart showing the ΦC1 processing, and Figs. 13 and 14 are each a simulated vehicle body. A diagram showing the relationship between speed VP and wheel speed VW, Figure 15A is a DV-M1 characteristic diagram, Figure 15B
is the GF-M2 characteristic diagram, Figure 15C is the PW-M3 characteristic diagram, Figure 16A is the DV-M4 characteristic diagram, and Figure 16B is
is a PW-M4 characteristic diagram, Figure 17 is another diagram for determining the pulse width PW for releasing the valve, and Figure 18 shows the relationship between the initial pulse width PW0 for inleting the valve and the road surface μ. Figure, No. 19
The figure shows the relationship between the pseudo vehicle speed VP and the wheel speed VW, Figure 20 shows the relationship between the maximum value of GF and the valve inlet time Tin, and Figure 21 shows the relationship between the road surface μ and the deceleration threshold G. It is a figure which shows the relationship with x1. 11, 12... Wheel speed sensor, 13, 14...
Master cylinder, 15...Brake, 16...Microcomputer, 21...Shut valve (SV), 22...Differential pressure switch, 23...PCV,
25... Inlet valve (IV), 26... Outlet valve (OV).

Claims (1)

[Scope of Claim for Utility Model Registration] A wheel speed sensor that detects the wheel speed from the rotation of the wheel, a deceleration calculation means that calculates the deceleration of the wheel speed output from the wheel speed sensor, and the deceleration calculation means. a pseudo-vehicle speed calculation means that separates the pseudo-vehicle speed from the wheel speed according to the output deceleration; A friction coefficient calculation means for calculating a friction coefficient, and an initial value of a pulse width indicating an opening time of an inlet valve that is intermittently driven when increasing the braking force of an anti-skid brake are set in accordance with the friction coefficient, and thereafter An anti-skid brake device comprising: means for gradually decreasing the pulse width of the anti-skid brake device.