JP3414216B2 - Anti-skid control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antiskid control device for adjusting wheel slip that occurs when a vehicle is braked.

[0002]

2. Description of the Related Art Conventionally, an anti-skid control device performs an anti-skid control for avoiding a wheel lock by obtaining a slip ratio for each wheel from a vehicle speed and a wheel speed and maintaining a slip state of the vehicle in an appropriate state. ing. The anti-skid control device has a master cylinder that generates brake fluid pressure in response to the driver's operation of the brake pedal, and a plurality of wheel cylinders that generate brake fluid pressure on each wheel based on the brake fluid pressure generated in the master cylinder. I have it. The anti-skid control device controls the slip state of the vehicle by increasing / decreasing the brake fluid pressure (hereinafter referred to as W / C pressure) in the wheel cylinders.

Specifically, the anti-skid control device is
When the above-mentioned slip ratio becomes large and the wheels tend to lock, the brake fluid pressure (hereinafter referred to as W / C pressure) is reduced by releasing the brake fluid in each wheel cylinder to the reservoir, and the lock tendency is released by this pressure reduction. The anti-skid control is performed by performing control such that the W / C pressure is held when the lock tendency is released and the W / C pressure is increased at a predetermined timing when the lock tendency is released.

[0004]

In the above device, since the W / C pressure is increased based on the brake fluid pressure generated by the master cylinder, when the W / C pressure is maintained or reduced, the master pressure is reduced. A brake fluid pressure generated in the master cylinder is prevented from being transmitted to the wheel cylinder by shutting off a predetermined holding valve provided in a pipe line connecting the cylinder and the wheel cylinder.

However, when the holding valve is closed, the movement of the brake pedal is limited, and if the movement of the brake pedal is limited for a long time,
If they feel like not depresses the brake pedal (hereinafter referred to as a plate feeling) will be given to the driver, there is a problem that exacerbates the pedal feel. The present invention has been made in view of the above points, and an object of the present invention is to provide an anti-skid control device for a good pedal feel by adjusting the time during which movement of the brake pedal is limited.

[0006]

In order to achieve the above object, the present inventors have examined a control method of an antiskid control device. The anti-skid control device performs anti-skid control by independently increasing / holding / depressing the W / C pressure corresponding to each wheel independently of each wheel.

A time chart for this anti-skid control is shown in FIG. 9 together with the operation amount of the brake pedal.
However, in FIG. 9, (a) shows a comparison between the vehicle body speed and the wheel speed, and (b) shows the opening / closing timing of the holding valve,
(C) shows the opening / closing timing of the pressure reducing valve, and (d) shows W /
C pressure, (e) returns the brake fluid released to the reservoir to the master cylinder without using a pump,
The operation amount of the brake pedal in a so-called pumpless system is shown, and (f) shows the brake fluid released to the reservoir to be returned to the master cylinder using a pump,
The operation amount of the brake pedal in a so-called pumped system is shown.

As shown in this figure, when the anti-skid control is started, the pressure reduction and the holding control are sequentially performed. Therefore, during this period, the holding valve is always closed so that the brake fluid pressure generated in the master cylinder is not transmitted to the wheel cylinder. As described above, since the movement of the brake pedal is restricted when the holding valve is shut off, the driver receives the gap between the plates, so if the holding valve is not shut off for a long time, the driver Is not affected by the feel of the board and is considered not to deteriorate the pedal feel.

Based on the above examination, the present invention adopts the following technical means. In the invention according to claim 1, when the anti-skid control means prohibits the flow of the brake fluid in all of the plurality of pipelines during the first predetermined time (KT1) or more during the anti-skid control. At least one wheel is selected from the plurality of wheels (1 to 4), and the holding valves (21 to 24) corresponding to the wheel cylinders (11 to 14) of the selected wheels are set to the communicating state. , Allowing the flow of the brake fluid between the master cylinder (16) and the wheel cylinders (11-14), and reducing the pressure reducing valve (31) corresponding to the selected wheel.
~ 34) are in communication, and the wheel of the selected wheel is
The conduits and reservoirs (3) corresponding to the cylinders (11-14)
It is characterized in that it allows the flow of the brake fluid between 7 and 39) .

As described above, the master cylinder (16) and the wheel cylinder (1) for depressurizing the master cylinder (16) for the first predetermined time (KT1) or more, which is earlier than the time during which the driver can feel the board.
1 to 14), the holding valves (21 to 21) corresponding to the wheel cylinders (11 to 14) of at least one of the plurality of wheels (1 to 4) when the flow of the brake fluid is prohibited. Since the brake fluid is allowed to flow between the master cylinder (16) and the wheel cylinders (11 to 14) by putting the brake pedal (24) into a communication state, the brake pedal (27 ) Can be enabled. As a result, an anti-skid control device having a good pedal feel can be obtained. In addition, the pressure reducing valve together with the holding valve (21 to 24)
(31 to 34) are in communication with each other, the holding valve (2
1 to 24) are put in communication with each other
Driver (11-14) without increasing the pressure
It is possible to avoid giving a feeling of board.

It should be noted that the first time during which the driver can feel the board is first.
After the predetermined time (KT1), the second predetermined time (KT
2) If the time has passed, if any of the holding valves (21 to 24) is in communication with each other within this time, the driver does not feel a plate. Therefore, as described in claim 2, the plurality of wheels (1 to 4) is provided only when the flow of the brake fluid is not allowed to flow in all of the plurality of pipelines during the second predetermined time (KT2). ), At least one wheel is selected, and the holding valve (21-2) corresponding to the wheel cylinder (11-14) in this selected wheel is selected.
You may make 4) into a communicating state.

According to the third aspect of the invention, the time for which the holding valves (21 to 24) are in the communicating state is changed according to the pressure of the wheel cylinders (11 to 14) of the selected wheel. I am trying. If the selected valve keeps the pressure of the wheel cylinders (11 to 14) at a predetermined pressure and the holding valve is kept open for a long time, the pressure of the wheel cylinders (11 to 14) is greatly increased. Will end up. Therefore, depending on the pressure of the wheel cylinders (11 to 14) of the selected wheel, the holding valve (2
It is possible to prevent the pressure of the wheel cylinders (11 to 14) from being greatly increased by changing the time for bringing the wheels 1 to 24) into the communication state.

[0013]

[0014] In the invention described in 請 Motomeko 4, anti-skid control means, out of the plurality of wheels (1-4), the wheel pressure increase control of the last time has elapsed the most time from taking place It is characterized by being selected.

For the wheel that has passed the most time since the previous boosting control was performed, since the time has passed since the previous boosting output was executed, the W / C pressure is not too high and increases. It seems that there is room to press. Therefore, by selecting such a wheel, the anti-skid control can be more suitably performed. Moreover, as shown in claim 5 ,
If the wheel with the lowest slip ratio is selected, the wheel slip can be more specifically prevented. And claim 6
As shown in, the wheel with the smallest sum of the time during which the pressure increase output is performed from the previous pressure decrease output to the present may be selected. That is, since the W / C pressure is considered to be lower than that of the other wheels in the wheel for which the sum of the time periods during which the pressure boosting output is performed is the smallest, the desired pressure boosting control can be performed while preventing the wheel slip. It can be carried out.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention shown in the drawings will be described. FIG. 1 is a schematic diagram showing the configuration of an anti-skid control device to which the present invention is applied. As shown in FIG. 1, right front wheel 1, left front wheel 2, right rear wheel 3 and left rear wheel 4
An electromagnetic pickup type or electric resistance element (MRE) type wheel speed sensor 5-8 is arranged in each of the above, and a pulse signal is generated according to the rotation of each wheel 1-4.

Further, wheel cylinders 11 to 14 are arranged on the wheels 1 to 4, respectively, and brake fluid pressure from the master cylinder 16 is passed through holding valves 21 to 24 as valve means and hydraulic lines. It is sent to each wheel cylinder 11-14. The master cylinder 16 is the brake pedal 2
The brake fluid pressure is generated by the depression of 7, and the depression state of the brake pedal 27 is detected by the stop switch 29.

Further, the wheel cylinders 11 and 14 are connected to the reservoir 37 via pressure reducing valves 31 and 34, and the wheel cylinders 32 and 33 are connected to the reservoir 39 via pressure reducing valves 32 and 33. The holding valves 21 to 24 and the pressure reducing valves 31 to 34 are electromagnetic two-position valves each having a communication position and a cutoff position. In addition, the holding valve 21
Up-and-downstream of 24 to 24 are provided with the bypass valves 41 to 44 by the check valves 41a to 44a, through which only the pressure oil from the wheel cylinders 11 to 14 toward the master cylinder 16 flows through the holding valves 21 to 24. ing. Furthermore, the reservoirs 37 and 39 and the master cylinder 16 are connected to the check valve 4
It is connected by a hydraulic line via 7, 49, and only the flow of pressure oil from the reservoirs 37, 39 to the master cylinder 16 is allowed.

Detection signals from the wheel speed sensors 5 to 8 and the stop switch 29 are input to an electronic control circuit (hereinafter referred to as ECU) 50. ECU50 is CPU, R
A well-known microcomputer having an OM, a RAM, and an I / O generates signals for controlling the holding valves 21-24 and the pressure reducing valves 31-34 based on the detection signals. This control signal is composed of a pressure increase output, a hold output and a pressure decrease output generated for each of the wheels 1 to 4. Here, the operation of the holding valves 21 to 24 and the pressure reducing valves 31 to 34 corresponding to each output will be described by taking the right front wheel 1 as an example.

To generate a boosted pressure output to the right front wheel 1 is to generate a control signal to bring the holding valve 21 into the communicating position and the pressure reducing valve 31 into the shut-off position. As a result, the brake fluid pressure generated by the master cylinder 16 is directly supplied to the wheel cylinder 11. To generate the holding output to the right front wheel 1 means to generate a control signal so that both the holding valve 21 and the pressure reducing valve 31 are in the shut-off position.
As a result, the brake fluid pressure in the wheel cylinder 11 is maintained. If the brake pedal 27 is loosened while the holding output continues, pressure oil flows through the bypass pipe 41, and the brake fluid pressure in the wheel cylinder 11 is reduced.

To generate a pressure-reducing output to the right front wheel 1 is to generate a control signal so that the holding valve 21 is in the shut-off position and the pressure-reducing valve 31 is in the communicating position. As a result, the pressure oil of the wheel cylinder 11 flows into the reservoir 37, and the brake fluid pressure is reduced. The ECU 50
The same output is performed for the other wheels 2 to 4. Also, in each of the control signals of pressure reduction output, pressure increase output, and hold output,
The state of the control signal may be changed depending on which output control signal the previous time was.

Next, details of the processing executed by the ECU 50 will be described with reference to the flowcharts of FIGS. ECU5
0 executes the main routine shown in FIG. 2 when the ignition switch is turned on. The ECU 50 executes this main routine for each of the wheels 1 to 4 in a time division manner. When the processing is started, the initialization processing is first executed in step 1000. By this initialization processing, initialization processing such as memory clear and flag reset is performed, and in the subsequent step 2000, the predetermined time Ta has elapsed in order to execute the transition calculation processing every predetermined time Ta (for example, 5 ms). By determining whether or not it waits for the predetermined time Ta to elapse.

If Yes at step 2000, the process proceeds to step 3000 and each wheel speed sensor 5
The wheel speeds VW ** of the wheels 1 to 4 are calculated based on the rotation speed signals from .about.8. Here, "**" is for each wheel 1
4 is a general term for symbols FR, RL, RR, and FL, that is, “VW **” is VWFR, VWRL, VWRR,
VWFL is shown, and wheel speeds for the right front wheel 1, the left rear wheel 2, the right rear wheel 3, and the left front wheel 4 are shown.

In the following step 4000, in step 30
The wheel acceleration dVW ** of each of the wheels 1 to 4 is calculated by differentiating the wheel speed VW ** obtained in 00.
Then, in step 5000, the vehicle body speed (estimated vehicle body speed) is calculated based on the maximum speed VWmax of the wheel speeds VW ** of the respective wheels 1 to 4 obtained in step 3000. This processing is performed by, for example, the wheel speed V of each wheel 1 to 4.
The maximum speed VWmax of WFR to VWRL is a deceleration limit value obtained by subtracting a predetermined value from the vehicle body speed VB (n-1) from an acceleration limit value Vα obtained by adding a predetermined value to the previously obtained vehicle body speed VB (n-1). Judge whether it is within the range up to Vβ,
If the maximum speed VWmax is within the range from the acceleration limit value Vα to Vβ, the maximum speed VWmax is maintained as it is.
B, and the maximum speed VWmax is the acceleration limit value Vα.
The acceleration limit value Vα is set as the vehicle body speed VB if it exceeds the maximum speed, and the deceleration limit speed Vβ is set as the vehicle body speed VB if it is less than the maximum speed VWmax deceleration speed limit value Vβ.

In step 6000, step 5
The vehicle body deceleration dVB is calculated by differentiating the vehicle body speed VB obtained by 000. And step 70
In 00, the calculated vehicle body speed VB and wheel speed VW **
The slip ratio SW ** of each wheel 1 to 4 is calculated by. After that, in step 8000, each wheel 1 to 4 is
Actuators 21 to 24 for each wheel 1 to 4 based on the slip ratio SW ** and the wheel acceleration dVW ** at
The control mode is calculated. The details of this process will be described with reference to the flowchart of the four-wheel control mode calculation shown in FIG.

Then, in step 9000, it is determined whether or not the holding valve is open, and the opening request of the holding valve and the pressure reducing valve is set for the wheel that meets the predetermined condition. The details of this process will be described with reference to the flow chart of the holding valve and pressure reducing valve open determination shown in FIG. Then, in step 10000, the process according to each control mode selected in step 8000 and step 9000 is performed, and the solenoids in the holding valves 21-24 and the pressure reducing valves 31-34 are driven. The details of this process will be described with reference to the flowcharts of the respective wheel output controls shown in FIGS.

Next, the details of step 8000 in FIG. 2 will be described based on the flowchart shown in FIG. This routine is performed by holding valves 21 to 24 on wheels 1 to 4 respectively.
Also, the control mode setting process of the pressure reducing valves 31 to 34 is performed, and is executed four times for the FR wheel 1, the FL wheel 2, the RR wheel 3, and the RL wheel 4. The setting of the control mode is performed to determine the control conditions such as how many ms and in what state the pressure increasing output, the pressure reducing output, and the holding output are performed in each wheel 1 to 4. The details of each control mode will be described later.

First, at step 210, it is judged if the stop switch 26 is ON, that is, if the vehicle is being braked. Until the stop switch 26 is turned on, the routine proceeds to step 220, where the control flag of the wheel is reset, and the control mode of the holding valves 21-24 and the pressure reducing valves 31-34 on the wheel is set to the pressure increasing mode. Then, the process ends. Here, the pressure increasing mode is a mode in which the pressure increasing output is continuously generated. That is, in the normal brake during vehicle braking, the brake fluid pressure generated by the master cylinder 16 is the same as that of the wheel cylinder 11
~ 14.

On the other hand, when the stop switch 26 is turned on, the routine proceeds to step 240, where it is judged if the control flag is set. That is, since the in-control flag is in the reset state immediately after the stop switch 26 is turned on, if No in step 240, step 2
Proceed to 50, and the slip ratio SW of the wheel that is the determination target
It is determined whether ** is larger than the target slip ratio KS0 (for example, 20%).

If No at step 250,
In step 220, the control flag is reset, the control mode of the wheel is set to the pressure increasing mode, and the process ends. If Yes in step 250, the process proceeds to step 260, the control-in-progress flag is set, and the process proceeds to step 27.
Go to 0. Next, in step 270, it is determined whether the slip ratio SW ** of the wheel is larger than a predetermined slip ratio KS1. This predetermined slip ratio KS1 is
It is smaller than the target slip ratio KS0, for example, KS 0 =
If 20%, KS1 = 15% is set.

Then, if Yes at Step 270, the routine proceeds to Step 280, where the wheel acceleration dVW * of the wheel concerned.
It is determined whether or not * is smaller than zero acceleration (0G), that is, whether the wheel is controlled in the deceleration direction or is reversed from the deceleration direction to the acceleration direction. If Yes in step 280, step 29
In step 0, the pressure reducing mode is set as the control mode of the holding valves 21 to 24 and the pressure reducing valves 31 to 34, and the process ends. If No in step 280, step 30
0, the holding mode is set as the control mode of the holding valves 21-24 and the pressure reducing valves 31-34, and the process is ended.

Here, the pressure reducing mode is a mode in which the above-mentioned holding output and pressure reducing output are alternately repeated (for example, switching every 15 ms), and the holding mode continuously generates the above-mentioned holding output. Mode. That is,
When the wheel acceleration dVW ** is 0 G or less and the wheels are locked, the brake fluid pressure in the wheel cylinders 11 to 14 is gradually reduced by the pressure reduction mode, and the wheel acceleration dVW ** exceeds 0 G and slip occurs. When it is gradually released, the brake fluid pressure is held in the holding mode. In the pressure-reducing mode, the control mode setting determines the change cycle of the pressure-reducing output and the holding output.

Specifically, the duty ratio of the pressure reducing output is increased if the number of pressure increasing outputs in the previous pressure increasing mode is large (or if the pressure increasing output time is long). On the other hand, if No in step 270, the process proceeds to step 310, and it is determined whether or not the control mode of the pulse pressure increasing mode has been executed a predetermined number of times. Here, the pulse pressure boosting mode is to alternately change the pressure increase output and the pressure hold output with respect to the holding valves 21 to 24 and the pressure reducing valves 31 to 34 in a predetermined cycle to change the wheel cylinder pressure of the brake device in the changing cycle. In this mode, the pressure is gradually increased in accordance with the pressure increase pattern.

Specifically, the change cycle of the pressure increasing mode, etc.
It is determined by the number of pressure reduction outputs in the previous pressure reduction mode (or the accumulated time of pressure reduction outputs). For example, if the accumulated time of the pressure-reducing output in the previous pressure-reducing mode is long, it is assumed that the W / C pressure can be increased to a certain degree and abruptly, and the change cycle to the output in the current pressure-increasing mode is accelerated. Also,
If the accumulated time of pressure reduction output during the previous pressure reduction mode is short,
The change cycle of boost output in this boost mode is delayed. As a result, the pressure boost output timing in the pressure boost mode changes, but it is possible to estimate the schedule of the pressure boost output in the pressure boost mode based on the change cycle thus determined.

If Yes at step 310, the slip of the wheel is completely suppressed, and it is assumed that the wheel does not slip even if the hydraulic control is terminated.
Go to step 220, reset the control flag,
The control mode of the holding valves 21 to 24 and the pressure reducing valves 31 to 34 is set to the pressure increasing mode, and the process is ended. That is, it returns to the normal brake. On the other hand, if No in step 310, the process proceeds to step 320, the control of the pulse increasing mode is continuously set as it is, and the process is ended.

Details of step 9000 in FIG. 2 will be described with reference to the flowchart shown in FIG.
This routine determines a case where the driver may feel a feeling of board in the future, selects the most suitable wheel for opening the holding valves 21 to 24, and holds the holding valve for the selected wheel. A request to open the pressure reducing valves 31 to 24 (hereinafter referred to as a holding valve opening request) is set, and when the pressure reducing valves 31 to 34 are opened at the same time when the holding valves 21 to 24 are opened, a request for opening the pressure reducing valves 31 to 34 (hereinafter, This is a process for setting a pressure reducing valve opening request).

First, in step 410, the holding valve 21 is kept for at least a predetermined time KT1 for all four wheels since the pressure boosting output was made to any one of the wheel cylinders 11 to 14 last time.
.About.24 are opened to determine if there is no output. That is, unless the holding valves 21 to 24 are opened further after the predetermined time KT1, the brake fluid in the master cylinder 16 is not consumed, and therefore the master cylinder 16 is not consumed.
The brake fluid inside does not move to the wheel cylinder side, and the driver feels that he cannot step on the brake pedal,
This is because the pedal feel gets worse. If Yes at step 410, the process proceeds to step 420 and No.
If so, the process ends.

When the affirmative determination is made in step 410, all four wheels are set to the depressurization mode or the holding mode, and in this state for a predetermined time KT1.
When the time has elapsed, at least one of the four wheels is set to the pressure boosting mode, but it is conceivable that a predetermined time KT1 has elapsed from the previous pressure boosting output based on the change cycle to the pressure boosting output.

At step 420, after the predetermined time KT1 has passed since the last time any one of the holding valves 21 to 24 was opened, 4 times within the time until the predetermined time KT2 is further passed.
It is determined whether or not the holding valves 21 to 24 are scheduled to be opened for any of the wheels. That is, assuming that the time when the holding valves 21 to 24 are not opened exceeds the predetermined time KT1 and further exceeds the predetermined time KT2, it is the time when the above-described plate feeling is felt. If the holding valves 21 to 24 are not opened for the wheel of, the pedal feel will be deteriorated.

Therefore, if Yes at step 420, the routine proceeds to step 430, where the holding valves 21 to 24 and the pressure reducing valve 3 are
Select the wheels to open 1-34. This wheel selection is performed based on whether or not the brake fluid may flow into the reservoirs 37 and 39 by opening the pressure reducing valves 31 to 34 among the wheels, and specifically, the wheels are selected. Among the 1 to 4, the wheel of the system in which the inflow amount of the brake fluid in the reservoirs 37 and 39 is the smallest is selected. This is because it is considered that the reservoirs 37 and 39 corresponding to the wheels of this system have room to store the brake fluid. On the other hand, if No in step 420, the pedal feel does not deteriorate, and the process ends.

When the wheels are selected in step 430, the process proceeds to step 440, in which a valve opening request is set for the selected wheel according to the state of the selected wheel, and the process ends. . Specifically, this valve opening request is set by selecting whether to set only the holding valve opening request or to set the pressure reducing valve opening request together with the holding valve opening request. That is, the case where only the hold valve open request is set is when the hold output is set in the pulse pressure increasing mode or when the W / C pressure is not substantially zero. In these cases, since it is necessary to maintain the W / C pressure,
The W / C pressure is prevented from being reduced by not opening the pressure reducing valves 31 to 34. On the other hand, when the pressure reducing valve opening request is set together with the holding valve opening request, the holding mode is set and the W / C pressure is substantially zero, or the pressure reducing mode is set. In this case, since it is not necessary to hold the W / C pressure, the holding valve open request and the pressure reducing valve open request are set.

Whether or not the W / C pressure is substantially zero is determined by W
The determination is made by directly detecting the / C pressure using a pressure sensor or the like, or by estimating the W / C pressure from the vehicle body deceleration before the pressure is reduced. For example, when the W / C pressure is estimated by the vehicle deceleration before the pressure is reduced, it is determined whether the W / C pressure is substantially zero based on the pressure reduction time and the pressure reduction curve.

When the valve opening determination is completed in this way, as shown in FIG.
In step 10000, the four-wheel output control process is executed. The details of step 10000 are shown in FIG.
~ It demonstrates based on the flowchart shown in FIG. In this routine, the solenoid drive corresponding to each of the pressure increase output, the pressure decrease output, and the hold output is performed in accordance with the previously set control mode of each wheel 1 to 4 while giving priority to the result of the valve opening request determination in step 9000. Set the pattern. In addition, this routine is performed by FR wheel 1, FL wheel 2, RR.
The wheel 3 and the RL wheel 4 are executed four times in total.

First, one wheel is set from each of the wheels 1 to 4, processing is performed for that wheel, and if the pressure increasing mode is set for that wheel, the process proceeds to step 510,
Set the solenoid drive pattern for boost output. If the pulse pressure increasing mode has been set for the set wheel, the routine proceeds to step 520, where it is determined whether or not it is the pressure increasing output timing for that wheel at present. The pressure increase output timing is determined according to the change cycle set in step 310. If it is the pressure boost output timing, the routine proceeds to step 510, where the solenoid drive pattern for the pressure boost output is set, and if it is not the pressure boost output timing, the routine proceeds to step 530, where the solenoid drive pattern for the hold output is set.

If the holding mode has been set for the set wheel, the routine proceeds to step 530, where the solenoid drive pattern for holding output is set. Then, when the solenoid drive pattern for the holding output is set in step 530, the process proceeds to step 540 to execute the pressure reducing valve open output determination processing. FIG. 6 shows a flowchart of the pressure reducing valve opening output determination processing, and the details of step 540 will be described.

In this routine, when the holding valves 21-24 corresponding to the selected wheels are opened, it is determined whether or not the pressure reducing valves 31-34 corresponding to the selected wheels are also opened. That is, it is determined whether to open the pressure reducing valves 31 to 34 in response to the valve opening request set in step 440 illustrated. Step 61
At 0, it is determined at step 440 whether the pressure reducing valve opening request is set. Then, in step 610, Ye
If s, the process proceeds to step 620, and if No, the process ends.

At step 620, the current pressure reducing valves 31 to 3 are currently used.
It is determined whether or not it is the output timing for opening No. 4. That is, the time for opening the pressure reducing valves 31 to 34 is set in advance, and for example, the setting is made such that the pressure reducing valves 31 to 34 are continuously opened during TR1 time. It is determined that the output timing is to be opened, and when TR1 time has elapsed, it is determined that it is not the output timing to open the pressure reducing valves 31 to 34. Therefore, if all the holding valves 21 to 24 are closed for the time KT1 continuously,
After that, at time TR1, the pressure reducing valves 31 to 34 are opened. However, this time TR1 does not have to be a constant, and may be changed according to the W / C pressure.

If Yes in step 620, the flow advances to step 630 to set the pressure reducing valve opening output pattern and the process ends, and if No, the process ends. In this way, when the pressure reducing valve open output pattern is set, this pressure reducing valve open output pattern has priority over the solenoid drive pattern in the previously set hold output, and the pressure reducing valves 31 to 34 are forcibly opened. It becomes a drive pattern.

When the pressure reducing valve opening output determination processing in step 540 is completed in this way, the process proceeds to step 550 and the holding valve opening output determination processing is executed. FIG. 7 shows a flowchart of processing for determining the holding valve open output, and details of step 550 will be described. In this routine, the holding valves 21-24
To open or not. That is, the holding valves 21 to 24 are responsive to the valve opening request set in step 440 described above.
To open or not.

In step 710, it is determined whether or not the holding valve open request is set in step 440. Then, if Yes in step 710, the process proceeds to step 720, and if No, the process ends. In step 720, it is determined whether or not it is the output timing for opening the holding valves 21 to 24 at present. That is, the holding valves 21 to 2
The time to open 4 is preset, for example, time TH1
Is set to open the holding valves 21 to 24 continuously, it is determined that the output timing is to open the holding valves 21 to 24 during the time TH1, and the holding valves 21 to 24 are opened after the time TH1. It is determined that it is not the output timing to open. Therefore, when all the holding valves 21 to 24 are continuously closed for the time KT1, the holding valves 21 to 24 are opened for the time TH1. However, this time TH1 does not have to be a constant and may be changed according to the W / C pressure.

Then, if Yes in step 720, the process proceeds to step 730 to set the pressure reducing valve open output pattern to end the process, and if No, the process ends. Thus, when the holding valve open output pattern is set, this holding valve open output pattern has priority over the solenoid drive pattern in the previously set holding output, so that the holding valves 21 to 24 are forcibly opened. It becomes such a solenoid drive pattern.

Further, if the pressure reduction mode has been set for the set wheel, the routine proceeds to step 560, where it is judged whether or not it is the pressure reduction output timing for that wheel at present. The pressure reduction output timing is determined according to the change cycle set in step 290. If it is not the pressure reduction timing, the routine proceeds to step 530, where the solenoid drive pattern for the holding output is set, and if it is the pressure reduction timing, the routine proceeds to step 570 for setting the solenoid drive pattern at the pressure reduction output.

When the solenoid drive pattern of the holding output is set in step 530, the process proceeds to step 540 to make the above-described pressure reducing valve open output determination, and then the process proceeds to step 550. Further, when the solenoid drive pattern for the reduced pressure output is set in step 570, the process proceeds to step 550. Then, in step 550, the above-described holding valve opening output determination is performed.

Here, when the solenoid drive pattern for pressure reduction output is set, the pressure reduction valve opening output determination in step 540 is not performed because the pressure reduction valves 31 to 34 are opened for the solenoid drive pattern for pressure reduction output. This is because it is a pattern, and in this case, the pressure reducing valves 31 to 34 are opened at the timing of the normal pressure reducing output.

In this way, when the solenoid drive pattern corresponding to each control mode is set, step 5
In step 80, it is determined whether the solenoid drive pattern has been set for all four wheels. And step 58
If 0 and Yes, the process proceeds to step 590 and each holding valve 21 is operated according to the previously set solenoid drive pattern.
.About.24 and the solenoids provided in the pressure reducing valves 31 to 34 are driven to move the two-position valve to the valve position corresponding to each output. On the other hand, if No in step 580, the process proceeds to step 600, in which the next wheel different from the currently processed wheel is set and the process for that wheel is executed.

As described above, before the driver feels a feeling of board,
By opening the selected holding valves 21 to 24, the driver can depress the brake pedal 27. FIG. 8 shows a time chart when the anti-skid control based on such processing is performed. However, in FIG. 8, for simplification, only the wheel selected in step 430 of the above control is shown in the time chart. In addition, in FIG. 8, (a) shows a comparison between the vehicle body speed and the wheel speed, (b) shows the opening / closing timing of the holding valves 21 to 24 on the selected wheel, and (c) shows the pressure reducing valve on the selected wheel. Three
1 to 34 show opening and closing timings, (d) shows W / C pressure, and (e) shows so-called pumpless that returns the brake fluid released to the reservoir toward the master cylinder without using a pump. The operation amount of the brake pedal in the system is shown, and (f) shows the operation amount of the brake pedal in the so-called pumped system in which the brake fluid released to the reservoir is returned to the master cylinder using the pump. .

As shown in FIG. 8A, when the wheel speed falls below the vehicle body speed, pressure reduction control is started and the pressure reduction mode is set in step 290. After that, when the wheel speed is restored and the locking tendency is avoided, the holding mode is set. While the pressure reducing mode and the holding mode are set, as shown in FIG. 8B, the holding valve is set. The state in which 21 to 24 are closed continues.

However, even in such a case, the state where the holding valves 21 to 24 are closed continues for the time KT1,
Further, if it is not planned that the holding valves 21 to 24 are opened during the time KT2, the time KT is changed as described above.
As 1 passes, the optimum wheel is selected and the holding valves 21-24 corresponding to that wheel are opened. That is, since one of the holding valves 21 to 24 is opened after the time KT1 has elapsed and before the time KT2 has further elapsed, it is possible to depress the brake pedal 27 before the driver feels a board feeling.

Further, the holding valve 2 corresponding to the selected wheel
1 to 24 are opened, and the pressure reducing valves 31 to 34 corresponding to the wheels are simultaneously opened as shown in FIG. 8 (c). That is, as shown in FIG. 8 (d), the W / C pressure is substantially zero due to the pressure reduction control executed previously.
Since it is not necessary to maintain the pressure, the holding valves 21 to 24 are opened and the pressure reducing valves 31 to 34 are opened to prevent the W / C pressure from increasing. When the holding mode is set and the W / C pressure is held at a predetermined pressure, only the holding valve open request is set in step 440.
/ C pressure is not reduced.

As described above, by making the holding valves 21 to 24 open before the driver feels the feeling of the board, the anti-skid control device can have a good pedal feel. Further, by opening the holding valves 21 to 24 and also opening the pressure reducing valves 31 to 34, the holding valves 21 to 24 are opened even if the holding mode or the pressure reducing mode is set. It is possible to prevent the pressure from increasing.

In the above embodiment, step 430 is executed.
At the time of selecting the wheel in FIG. 3, the wheel of the system in which the amount of the brake fluid in the reservoirs 37 and 39 is small is selected among the wheels 1 to 4, but the amount of the brake fluid inflow into the reservoirs 37 and 39 is selected. Can be detected directly from the amount of movement of the pistons of the reservoirs 37 and 39, or indirectly from the sum of the time when the reduced pressure output is executed.

In the wheel selection in step 430, the wheel for which the pressure reduction mode is currently set may be selected. Since the pressure reducing mode is set, it means that the pressure reducing valves 31 to 34 may be opened. Therefore, if the holding valves 21 to 24 are opened and the pressure reducing valves 31 to 34 are opened, the wheel cylinders 11 to 14 are pressurized. This is because it is possible to prevent the driver from having a feeling of board.

Further, in the wheel selection in step 430, it is possible to select the oldest wheel for which pressure increase output was performed last time or the wheel with the smallest wheel slip ratio. This is because it is considered that the wheel does not slip even if the pressure is increased on the wheel. In addition, when selecting a wheel in which the pressure reduction mode is currently set or when selecting a wheel with the smallest wheel slip ratio, it is not limited to the case where the so-called pumpless system shown in FIG. 1 is applied,
It can also be applied to a so-called system with a pump.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an anti-skid control device according to the present invention.

FIG. 2 is a flowchart showing a main routine of the anti-skid control device shown in FIG.

FIG. 3 is a flowchart of control mode calculation processing in FIG.

FIG. 4 is a flowchart of a four-wheel output mode determination process in FIG.

5 is a flowchart of a four-wheel output control process in FIG.

FIG. 6 is a flowchart of a pressure reducing valve opening output determination in FIG.

FIG. 7 is a flowchart of holding valve open output determination in FIG.

FIG. 8 is a time chart showing the operation based on the processing of the anti-skid control device of FIG. 1.

FIG. 9 is a time chart showing an operation based on processing of a conventional anti-skid control device.

[Explanation of symbols]

1 ... right front wheel, 2 ... left front wheel, 3 ... right rear wheel, 4 ... left rear wheel, 5
... 8 ... Wheel speed sensor, 11-14 ... Wheel cylinder,
21-24, 31-34 ... 2-position valve, 27 ... Brake pedal, 29 ... Stop switch, 50 ... ECU.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-11-20650 (JP, A) JP-A-2-249753 (JP, A) JP-A-7-329754 (JP, A) JP-A-58- 164460 (JP, A) JP-A-4-191157 (JP, A) JP-A-62-83242 (JP, A) JP-A-2-200556 (JP, A) Actual development 1-158268 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60T 8/00 B60T 8/32-8/96

Claims (6)

(57) [Claims] 1. A plurality of wheel cylinders (11 to 14) for applying a wheel braking force to each of a plurality of wheels (1 to 4) during vehicle braking, and a brake fluid toward the plurality of wheel cylinders during vehicle braking. A master cylinder (16) for providing a plurality of pipes, a plurality of conduits that communicate the master cylinder with each of the plurality of wheel cylinders, and a slip state detection unit (7000) that detects a slip state of the plurality of wheels. and anti-skid control means for performing anti-skid control by adjusting the brake fluid pressure applied to the plurality of wheel cylinders on the basis of the detection result of the slip state detecting means, holding a plurality provided in each of the plurality of conduits The valves (21 to 24) and the reservoir (3 for releasing the brake fluid in the plurality of pipelines ).
7, 39) and the flow of brake fluid from the plurality of conduits to the reservoir.
And a plurality of pressure reducing valves (31 to 34) for controlling the above, and the anti-skid control means, during the anti-skid control, reduces or holds the brake fluid pressure of any one of the plurality of wheel cylinders. When performing the holding control, the holding valve corresponding to the wheel cylinder for depressurizing / holding is shut off to prohibit the flow of the brake fluid between the master cylinder and the wheel cylinder for depressurizing, and the plurality of wheels are controlled. When performing pressure increase control to increase the brake fluid pressure of any one of the cylinders, the brake fluid between the master cylinder and the wheel cylinder to increase the pressure is set by connecting the holding valve corresponding to the wheel cylinder to increase the pressure. It is adapted to permit the flow of, and forum for the pressure reduction control
In the case of
Control the pressure reducing valve to prevent
Brake fluid between the corresponding pipeline and the reservoir
When the holding control or pressure increase control is allowed by allowing the flow of
Corresponds to the wheel cylinder that boosts and holds the pressure.
A wheel cylinder for controlling the pressure reducing valve to reduce the pressure.
The break between the conduit and the reservoir corresponding to
Further, the anti-skid control means is configured to prohibit the flow of the liquid, and the anti-skid control means, during the anti-skid control, for a first predetermined time (KT1) or more, the brake liquid in all of the plurality of pipelines. First determination means (41) for determining whether or not the flow of
Has 0), this when the first affirmative determination by the determination means has been made, the pre-Symbol select even one wheel less among the plurality of wheels, corresponding to the wheel cylinder in the selected wheel wherein The holding valve is set in the communication state to allow the flow of the brake fluid between the master cylinder and the wheel cylinder, and also to correspond to the selected wheel.
The pressure reducing valve to be in communication with the wheel of the selected wheel.
Between the conduit and the reservoir corresponding to the oil cylinder
An anti-skid control device characterized in that it allows the flow of brake fluid in . 2. The anti-skid control means, in the anti-skid control, in any one of the plurality of pipelines during a second predetermined time (KT2) after exceeding the first predetermined time. Second determination means (420) for determining whether or not the flow of the brake fluid is to be permitted
Has, the second if a negative determination by the determination means has been made, the previous SL selects a plurality of even one wheel less among the wheels, the holding valve corresponding to the wheel cylinders in the selected wheel in the communicating state and is characterized in that is adapted to permit the flow of brake fluid between the said master cylinder and the wheel cylinder according
Item 1. The anti-skid control device according to Item 1 . Wherein the anti-skid control means, the time for the holding valve corresponding to the wheel cylinder in said selected wheels in communication with, Ru varied according to the pressure of the wheel cylinder in said selected wheel So
Anti-skid control apparatus according to have become to claim 1 or 2, characterized in. 4. The anti-skid control means comprises
Of the number of wheels, the most time has elapsed since the last boost control was performed.
The anti-skid control device according to any one of claims 1 to 3, wherein a wheel whose time has elapsed is selected . Wherein said anti-skid control means, among the plurality of wheels, to any one of claims 1 to 3, characterized in that slip rate is adapted to select the smallest wheel Antiskid control device as described. 6. The anti-skid control means is configured to increase the pressure of the plurality of wheels from the time of the previous pressure reduction control.
Anti-skid control apparatus according to any one of claims 1 to 3, characterized in that the time is adapted to select the shortest wheel.