JPH075069B2 - Wheel braking control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a wheel braking control device for preventing rotational slip of a wheel when the vehicle starts or accelerates.

(Prior Art) When starting or accelerating a vehicle, especially when starting or accelerating on a snowy road or an icy road surface, the wheels are idling and the intended starting or accelerating is not brought about, or a pair of left and right wheels. One of them may idle and the other may move forward, and the direction of the vehicle may not be as intended. Therefore, conventionally, the slip ratio (rotational slip ratio) of the wheel is detected, and when it is a predetermined value or more, the engine output (wheel driving force) is reduced (for example, Japanese Patent Laid-Open No. 58-16948), It has been proposed to apply a brake (for example, JP-A-58-16947).

(Problems to be Solved by the Invention) However, in the above proposed former, there is a considerable delay time from the detection of the slip to the decrease of the wheel driving force, and the wheel drive after the slip is no longer detected. There is a delay before power is restored. Due to these delay times, the wheel driving force is high when there is slip and the wheel driving force is low when there is no slip, the starting and acceleration performance of the vehicle is reduced, and the vehicle speed pulsates. In the latter proposed, the brake is applied while the slip ratio exceeds the set value, and the brake is released when the slip ratio is less than the predetermined value, the wheel speed vibrates, the brake is periodically applied, and the vehicle body vibrates FF ( In the case of (front-wheel drive) vehicle, the steering wheel vibrates, which gives the driver an unpleasant feeling.

An object of the present invention is to improve the steering stability by reducing the pulsation of the vehicle speed and the vibration of the vehicle body.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a brake mounted on a wheel coupled to a prime mover via a power transmission means; a brake instruction means; Brake energizing means for energizing the brake in response to a control instruction including a pressure and a brake pressure instruction from the brake instructing means; a means for detecting a wheel rotation speed; a reference speed detecting means; a wheel acceleration / deceleration detection Means for calculating the slip ratio of the wheel from the rotational speed of the wheel and the reference speed; means for detecting the operating power of the prime mover; and corresponding to the combination of the slip ratio and the acceleration / deceleration of the wheel,
When the slip ratio and acceleration / deceleration are large, an instruction to increase pressure is issued.When the slip ratio and acceleration / deceleration are small, an instruction to depressurize is given to the brake urging means. Correspondingly, slip response control means for instructing high speed pressure increase when it is high and low speed pressure increase when it is low.

According to this, the wheel is braked when the slip ratio is large and the wheel acceleration / deceleration is high (the wheel rotation speed rises rapidly), and the slip ratio is small and the wheel acceleration / deceleration is low (the wheel rotation speed falls). When the wheel braking is released, that is, when the slip of the wheel rotation is large to a certain extent and the slip is further abruptly increased, the wheel braking is increased, the slip is reduced to a certain extent, and the slip is abruptly increased. When it gets smaller, the braking is released, the pulsation of the vehicle speed is reduced, the vibration of the vehicle body is also reduced,
The starting, acceleration and steering stability of the vehicle are improved.

A large slip rate and a high wheel acceleration / deceleration means that the wheel is accelerating while slipping, and it can be predicted that the slip rate further increases within a short time due to this acceleration. The above-mentioned wheel braking in this case is
In a sense, it can be said that braking is predicted to further increase the slip ratio in the near future. A small slip ratio and low wheel acceleration / deceleration means that the wheel is rotating at a constant speed, decelerating or slightly accelerating with no slip or a slight slip. It is unlikely that the slip ratio will rise, and it is expected that the slip ratio will decline further in the near future. The above-mentioned braking release in this case includes both braking release corresponding to the decrease of the slip ratio and braking release predicting the decrease of the slip ratio. In the present invention, the behavior of the slip ratio is predicted by referring to the wheel acceleration speed, and the wheel braking is controlled accordingly, so that the pulsation of the vehicle speed is reduced and the vibration of the vehicle body is also reduced. , Vehicle start-up, acceleration performance and steering stability are improved.

In addition, in the case of braking (pressure increase) as described above, when the operating power of the prime mover is high (wheel driving force is large), high-speed braking is performed, so an increase in slip is suppressed early and the operation of the prime mover is reduced. Low power (small wheel driving force)
At times, braking is performed at a low speed to prevent wheel over-braking, which further reduces pulsation of the vehicle speed and further suppresses vibration of the vehicle body. The starting, acceleration and steering stability of the vehicle are further improved.

In a preferred embodiment of the present invention, the brake is a fluid pressure brake that applies a braking force corresponding to the fluid pressure to the wheels; the brake instruction means is a brake pedal and a brake master cylinder that generates a brake pressure corresponding to the depression amount of the brake pedal. Yes; the brake urging means is housed in the input port communicating with the brake master cylinder, the output port communicating with the fluid pressure brake, the piston working space communicating with the input port and the output port, the piston working space, and inputting the working space. A main piston that divides into a space communicating with the port and a space communicating with the output port, a control piston whose one end abuts on one end of the main piston, and a control port communicating with the space on the other end side of the control piston. Of the device, the control port and the high pressure port of the fluid pressure source A first electromagnetic on-off valve for opening and closing and a second electromagnetic valve that opens and closes between the low pressure port of the control port in fluid pressure source, is made by.

Then, the control instruction includes a hold; the step response control means instructs the brake energizing means: depressurize when the slip ratio is less than the first set value; When the wheel acceleration / deceleration is less than the first set value, slip decompression is performed when the wheel acceleration / deceleration is less than the first set value, hold is held when the wheel acceleration / deceleration is not less than the first set value and less than the second set value, and step pressure increase is performed when the wheel acceleration / deceleration is not less than the second set value. When the slip ratio is equal to or more than the second set value, step decompression is instructed when the wheel acceleration / deceleration is less than the third set value, and step increase pressure is instructed when the wheel acceleration / deceleration is equal to or more than the third set value. The step depressurization is a combination of depressurization and hold, which is a depressurization for a first predetermined time, followed by a hold for a second predetermined time; a step pressure increase is a pressure increase for a first predetermined time, followed by a second pressure increase. It is a combination of pressure increase and hold for holding for a predetermined time. The high speed step pressure increase has a large ratio of the first predetermined time to the second predetermined time, and the low speed step pressure increase has a small ratio of the first predetermined time to the second predetermined time.

According to this preferred embodiment, braking includes high speed pressure increase (step pressure increase 1), low speed pressure increase (step pressure increase 2), hold, low speed pressure decrease (step pressure decrease) and high speed pressure decrease (step pressure increase). Decompression: continuous decompression), and the combination of slip ratio and wheel acceleration / deceleration is 6 stages.
Since each of the above five stages of braking is associated with each stage, the slip ratio, the wheel acceleration / deceleration, and the braking force are closely and smoothly associated with each other, and the vehicle start-up, acceleration performance, and steering stability are further improved. To do. The pulsation of the vehicle speed is further suppressed and the vibration of the vehicle body is further suppressed.

Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

(Embodiment) FIG. 1 shows the configuration of an embodiment of the present invention. This example
The present invention is applied to the slip control of the front wheels of a so-called FF (front wheel drive) vehicle in which the front wheels 10FL and 10FR are rotationally driven by the engine 12 via the differential gear 16 and the transmission 14.

The front left wheel 10FL, the front right wheel 10FR, the rear left wheel 10RL and the rear right wheel 10RR have wheel brakes 26 which are fluid pressure brakes.
Equipped with FL, 26FR, 26RL and 26RR. A brake pedal 22 is connected to a brake master cylinder 24 that is a brake command means. Brake oil pressure corresponding to the amount of depression of the brake pedal 22 is output from the master cylinder 24, and this is applied to the front left wheel wheel brake 26 via the left drive wheel brake pressure control valve 28FL, which is the brake urging means.
The front right wheel wheel brake 26FR is also connected to the FL via the right drive wheel brake pressure control valve 28FR which is also a brake energizing means.
To the rear left and right wheel brakes 26RL, 26RR.

The front left wheel 10FL, the front right wheel 10FR, the rear left wheel 10RL, and the rear right wheel 10RR have wheel rotation speed detectors 44FL, 44FR, 44, respectively.
RL and 44RR are combined and they generate a sine wave at a rate of one cycle for each predetermined rotation of the wheel. The sine waves generated by these are waveform-shaped (accurately pulsed) by the circuits 46FL, 46FR, 46RL and 46RR that perform amplification and pulse shaping, respectively, and then applied to the interrupt port of the microprocessor 58 that is the slip response control means. To be done.

A potentiometer-type throttle opening sensor 20 is coupled to the rotary shaft of the throttle valve of the engine 12, and the sensor 20 generates an analog signal indicating the throttle opening. This analog signal is amplified by the rotation angle detection circuit 50 and applied to the analog / digital conversion port AD1 of the microprocessor 58.

A light shield 40 is connected to the brake pedal 22 and
A photo sensor 42 is arranged in a rotation range of 40. When the brake pedal 22 is depressed to the brake operation start point, the light between the light emitting element and the light receiving element of the photo sensor 42 is blocked by the light blocking plate 40, and the photo sensor 42 blocks the light while the brake pedal 22 is in the brake operating range. Becomes That is,
The photo sensor 42 shields light (OFF) while the brake pedal 22 is in the operating range, and receives light (ON) when the brake is released.
Is. The photo sensor 42 is energized by a switch-on detection circuit 48. The switch-on detection circuit 48 is connected to the photo sensor 42.
The received light signal of is amplified and binarized, and the microprocessor 58
Give to.

The brake pressure control fluid supply port (high pressure port) 82 of the left drive wheel brake pressure control valve 58FL and the right drive wheel brake pressure control valve 28FR is connected to the accumulator 36, and the left drive wheel brake pressure control valve 28FL and the right drive wheel are connected. Brake pressure control valve 28FR
The brake pressure control fluid discharge port (low pressure port) 85 is connected to the control fluid reservoir 34. Reservoir
The fluid of 34 is sucked by the pump 32 and pressurized and supplied to the accumulator 36. The fluid pressure in the accumulator 36 is detected by the pressure sensor 38. The pressure sensor 38 produces an analog signal proportional to the fluid pressure. The pressure detection circuit 52 amplifies this analog signal and applies it to the analog / digital conversion port AD2 of the microprocessor 58. Pump 32 is motor 30
The motor 30 is rotationally driven by the motor driver 54. The motor driver 54 is a microprocessor 58
It is connected to the. When the pressure detected by the pressure sensor 38 becomes less than the first predetermined pressure, the microprocessor 58 drives the driver.
The driver 54 is instructed to rotate the motor 30, and when the pressure detected by the pressure sensor 38 becomes equal to or higher than the second predetermined pressure, the motor is sent to the driver 54.
Instruct to stop 30. As a result, the fluid pressure in the accumulator 36 is maintained within a predetermined narrow range (between the first predetermined pressure and the second predetermined pressure).

The left drive wheel brake pressure control valve 28FL and the right drive wheel brake pressure control valve 28FR have exactly the same structure, and roughly include a valve housing (60) as a fluid pressure increasing / decreasing device and a first solenoid opening / closing valve (SLO1 + 86) for increasing pressure. ) And a second solenoid valve for reducing pressure (SLO2 + 87).

FIG. 2 shows the structure of the left drive wheel brake pressure control valve 28FL in detail. The input port 61 of the housing 60 is the master cylinder 24
Of the brake pressure output port, and the output port 62 communicates with the wheel cylinder 26FL. The input port 61 is divided into the input pressure chamber 64 divided by the main piston 63, and the output port 62
Communicates with the output pressure chamber 65.

The control piston working space communicates with the input pressure chamber 64, and the control port 75 communicates with this working space.However, the control piston 74 shuts off between the control port 75 and the input pressure chamber 64. There is. The left end of the main piston 63 has a substantially small diameter cylinder, and its leftmost end is in contact with the right end of the control piston 74, but a slit 68 through which the stopper pin 67 easily passes is cut. The stopper pin 67 is fixed to the housing 67 and is stationary. A hole communicating with the inner space of the cylinder is formed in the center of the main piston 63, and a rod having a substantially triangular prism shape is inserted into this hole.
69 is inserted. A ball valve 72 is in contact with the right end of the rod 69. This ball valve 72 is a compression coil spring
Pressed to the left at 73. The right end of the compression coil spring 73 is supported by a spring seat 70 having a through hole 71. The spring seat 70 is fixed to the right end of the main piston 63.
A compression coil spring 66 is housed in the output pressure chamber 65, and the spring 66 pushes the main piston 63 to the left.

When the brake pedal 22 is not depressed, the main piston 63 is on the leftmost side as shown in FIG. 2, and at this time, the left end of the piston 63 contacts the right end of the control piston 74, and the ball valve 72 moves to the rod. Although 69 is pushed to the left, the rod 69 is stopped by the pin 67, and the ball valve 73 is separated from the center hole of the piston 63 to the right. If the pressure in the input pressure chamber 64 is higher than the pressure in the output pressure chamber 65, the piston 63 moves to the right and slightly separates from the control piston 74, which causes the fluid in the input pressure chamber 64 to move to the center hole of the piston 63. Through to the output pressure chamber, and the pressure in the output pressure chamber 65 equilibrates with the pressure in the input pressure chamber 64.

When the brake pedal 22 is depressed, the pressure in the input pressure chamber 65 rises and the piston 63 moves to the right. As a result, the fluid in the input pressure chamber 64 passes through the center hole of the piston 63 and the output pressure chamber 65.
Although the ball valve 72 closes the center hole of the piston 63 when the piston 63 moves slightly to the right, the pressure in the output pressure chamber 65 rises due to the pressure applied by the movement of the piston 63. To do. When the brake pedal 22 is released, the pressure in the input pressure chamber 64 drops, and the piston
63 moves to the left, and the pressure in the output pressure chamber 65 decreases.

The above is the normal braking operation when the brake pedal 22 is depressed. Next, the part of the present invention that is added for slip response brake pressure control will be described. When the control piston 74 is driven to the right, when the brake pedal 22 is depressed and the pressure in the input pressure chamber 64 rises. Similarly to the above, the main piston 63 is driven to the right, whereby the pressure of the output pressure chamber 65 rises, the brake pressure of the wheel cylinder 26FL rises, and the braking force acts on the wheel 10FL. Note that this has nothing to do with the depression of brake pedal 22. When the control piston 74 is returned to the left, the main piston 63 is driven to the left by the repulsive force of the coil spring 66 and the pressure of the output pressure chamber 65, and the pressure of the output pressure chamber 65 decreases (the braking force is released).

Such driving of the control piston 74 is performed by supplying a high-pressure fluid to the control port 75 (pressure increase: braking) and by removing the control fluid from the control port 75 (pressure reduction: braking release).
Next, the mechanism for supplying the control fluid to the control port 75 in this way will be described.

Low-pressure port 85 (second port communicating with low-pressure port of reservoir 30)
In the drawing), a space accommodating the second plunger 87 is communicated with each other through a passage 84 and a passage 83. Second Plunger 87 is through 83
Has a valve body for closing and a flow passage groove 77. Second Plunger
87 is pushed upward by a compression coil spring 89. In the state shown in FIG. 2 (the state in which the first and second electric coils are not energized), the control port 75 passes through the through hole 76 to the second position.
It communicates with the planier 87 storage space, through this space and through the ports 83 and 84 to the low pressure port 85. As a result, the control piston 74 is at the leftmost position as shown in FIG. When the second electric coil SOL2 is energized, the second plunger 87 is driven downward and its valve body closes the passage 83. As a result, the storage space for the second plunger 87 and the low pressure port 85 are shut off.

The storage space of the second plunger 87 is passed through the groove 77 for the flow of the second plunger 87 and the passage 78 of the fixed core to the first plunger 86.
It communicates with the storage space. The storage space of the first plunger 86 communicates with the high pressure port 82 communicating with the accumulator 36 through the passage 81, but the second plunger 86 is pushed upward by the compression coil spring 88, and the valve element of the plunger 86 opens. Since it is closed, when the first electric coil SLO1 is not energized, as shown in FIG. 2, the first plunger 86 storage space and the high-pressure port 82 are shut off. 1st electric coil SLO1
When electricity is applied to the first plunger 86, the first plunger 86 is driven downward,
The control port 75 has a passage 76, a groove 77, a passage 78, a storage space for the first plunger 86, a passage 79 and a groove 8 for the first plunger 86.
It communicates with the high-pressure port 82 through 0 and the passage 81. At this time, when the second electric coil SLO2 is energized, the second plunger 87 closes the passage 83, so that a high pressure is applied to the left end of the control piston 74, and the control piston 74
Pushes the main piston 69 to the right, which causes the output pressure chamber to
The pressure of 65 rises, the brake pressure of the wheel brake 26FL rises, and braking force is applied to the wheels 10FL.

The relationship between the energization (energization) and the non-energization (energization) of the first electric coil SOL1 and the second electric coil SOL2 described above and the braking of the wheel 10FL is summarized in Table 1 below.

As will be described later, the brake pressure control based on slip response is performed in five modes: step pressure increase 1, step pressure increase 2, hold, step pressure reduction, and pressure reduction (continuous pressure reduction). That is, the "pressure increase" mode includes a "step pressure increase 1" mode and a "step pressure increase 2" mode, and the "pressure reduction" mode includes a "step pressure reduction" mode and a "pressure reduction (continuous pressure reduction)" mode. There is.

"Step pressure increase 1" is the pressure increase shown in Table 1 for 5 msec.
During the next 5 msec, the hold shown in Table 1 is set as one cycle, and this cycle is repeated.

"Step pressure increase 2" is the pressure increase in Table 1 for 5 msec.
During the next 10 msec, the hold shown in Table 1 is set as one cycle, and this cycle is repeated. The step pressure increase 2 is twice as long as the step pressure increase 1 compared with the step pressure increase 1, so that the pressure increase rate (speed of increasing the braking force) is slow.

The "step depressurization" is a mode in which the depressurization of Table 1 is performed for 5 msec and the hold of Table 1 is performed for the next 5 msec, and this is set as one cycle, and this cycle is repeated.

The decompression (continuous decompression) mode is a mode in which the "decompression" in Table 1 is continued. In this decompression (continuous decompression) mode,
Since the "pressure reduction" in Table 1 is continued, the pressure reduction speed (speed at which the braking force is reduced) is higher than in the step pressure reduction mode.
Is high.

The relationship between the above-mentioned 5 modes and the modes shown in Table 1 is shown in FIG. 4a. In FIG. 4a, the right vertical column shows the above-mentioned 5 modes, and the words in the waveform chart show the modes in Table 1.

The right drive wheel brake pressure control valve 28FR shown in FIG. 1 has exactly the same structure and operation as the left drive wheel brake pressure control valve 28FL described above, and the same control mode.

The microprocessor 58 shown in FIG. 1 includes an interrupt count program for counting wheel rotation pulses obtained by pulsing the sine wave generated by the wheel rotation speed detectors 44FL, 44FR, 44RL, 44RR, and the wheels based on the pulse count number. A program for calculating the rotation speed, a program for calculating the wheel rotation acceleration / deceleration from the wheel rotation speed, a program for calculating the reference speed (corresponding to the vehicle body speed) from the wheel rotation speed, a status signal of the brake pedal sensor 42, a throttle opening, Referring to the wheel rotation speed, the wheel rotation acceleration / deceleration, and the reference speed,
Referring to the brake control program for slip control for energizing and deactivating the electric coil SOL1 and the second electric coil SOL2, and the pressure of the accumulator 36, the motor 30 is energized and deenergized so that it falls within a predetermined range. An accumulator pressure control program for controlling the power is stored.

3a to 3d show the control operation of the microprocessor 58 based on the above program. The illustration of the interrupt counting operation of the wheel rotation pulse and the accumulator pressure control is omitted.

First, refer to FIG. 3a. When the power is turned on, the microprocessor 58 initializes internal registers, flags, counters (program counters), timers (program timers), input ports and output ports (step 1: hereinafter referred to as "step" in Katsuko). Omit the word). Next, interrupts 1 to 4 are permitted (2). With this interrupt permission, each time the pulse generator 44FL, 44FR, 44RL, or 44RR generates one pulse, the interrupt process is executed and the count register associated with each of them is incremented by one. For example, when 44FL generates one pulse, the content of the count register assigned to 44FL is updated by one more than the previous content. The same applies when 44FR, 44RL or 44RR generate one pulse.

Generally speaking, steps 3 and subsequent steps after permitting the interruption (2) are slip response brake pressure control, and in this embodiment, they are repeated at a cycle of t ₁ = 5 msec. At the beginning of the brake pressure control for one cycle, first, the contents of the above-mentioned count register VFL (the contents of the register that counts the pulses generated by the pulse generator 44FL), VFR (pulse generator)
44FR generated pulse count register contents), VRL
Microprocessor for (contents of register that counts pulses generated by pulse generator 44RL) and VRR (contents of register that counts pulses generated by pulse generator 44RR)
58 Reads into the accumulator register inside and clears the count register that holds these (set contents to 0) (3). As a result, the interrupt count of the pulses generated by the pulse generators 44FL to 44RR is started from 0 again. , VFL, VFR, VRL and VRR values are
Since step 3 is executed at t ₁ = 5 msec cycle, pulse generators 44FL, 44FR, 44RL and 44R for 5 msec respectively
R shows the number of pulses generated, these are wheels 10F
Corresponds to L, 10FR, 10RL and 10RR rotation speeds.

When the wheel rotation speeds VFL, VFR, VRL and VRR are read, the microprocessor 58 sets a program timer t ₁ that takes a time limit of t ₁ = 5 msec (4), and averages the wheel rotation speeds for smoothing calculation. The original data is updated (5). In this, four sets of averaging source data registers (one set is M1 ~
The contents of (M5) are transferred to M1, the contents of M2 to M1, the contents of M3 to M2, the contents of M4 to M3, and the contents of M5 to M4, and the latest reading value is stored in M5. For example, regarding the set of registers (M1 to M5) assigned to the VFL, the VFL read this time is stored in the M5 after the above data shift. VFR, VRL and VRR are processed similarly. next. Wheel speed calculation (6) is performed. In this case, taking VFL as an example, the weighted average value VFL of the wheels 10FL is calculated by VFL = (6M5 + 4M4 + 3M3 + 2M2 + M1) / 16. In this equation, M1 to M5 indicate the contents of the registers M1 to M5. This weighted average is for preventing erroneous control operation based on erroneous detection due to noise. In the simple average, since the degree of reflection of the latest read value is too small, the most recent weight is given to the latest read value.

Next, the reference speed VBS corresponding to the vehicle speed is calculated (7). In this case, in this embodiment, since the rear wheels 10RL and 10RR are not directly rotationally driven by the engine, the rotational speed of the rear wheels is relatively accurately proportional to the vehicle body speed. Therefore, [VBS = VRL and VRR
Whichever is higher]. That is, the higher rear wheel rotation speed is set as the reference speed VBS.

Next, the acceleration / deceleration dFL (front left wheel) and dFR (front right wheel) of the front wheels, which are the driving wheels, are calculated (8). This is the value V calculated the last time (before t ₁ ) from the wheel speeds VFL and VFR calculated this time.
Obtained by subtracting FL _B and VFR _B. That is, dFL = VFL−VFL _B , d
Obtain acceleration / deceleration data as FR = VFR-VFR _B. dFL, dFR
Indicates acceleration when it is positive and deceleration when it is negative.

Next, the microprocessor 58 reads the throttle opening (9). In this, the analog signal input port AD1
The input of is converted to digital.

Next, referring to the status signal of the brake-on sensor 42 (10
a).

Here, if the sensor 42 detects the brake depression, the slip response control is not executed, and since the brake pressure due to the normal depression of the brake pedal is applied to the input port (64), the left drive wheel brake pressure control valve In order to reduce the pressure of 28FL (return the control piston 74 to the standby position: leftmost position), output registers SL1 (registers associated with the port SL1 assigned to control SLO1) and SL2 (ports assigned to control SLO2) Set low level L (corresponding to OFF in Table 1) to the register associated with SL2). Similarly, in order to reduce the pressure of the right drive wheel brake pressure control valve 28FR as well, the low level L is set in the output registers SR1 and SR2. Note that the contents of these output registers SL1, SL2 and SR1, SR2 are output ports SL1, SL2 and SR in step 13 to be described later.
Set to 1, SR2.

Next, since the brake pressure control of slip response is not performed,
The contents of registers, flags, counters, timers, etc. related to the control are cleared (12).

Then, the contents of the output register SL1 are output port SL1, the contents of the output register SL2 are output port SL2, and the output register SR.
The contents of 1 are set in the output port SR1, and the contents of the output register SR2 are set in the output port SR2 (13). As a result, the left drive wheel brake pressure control valve 28FL and the right drive wheel brake pressure control valve 28FR are set to the "pressure reduction" mode shown in Table 1.

Next, wait for the timer t ₁ (5 msec) to expire (1
4) When the time is over, the process returns to step 3 to read the wheel rotation speed.

Now, in step 10a, when the sensor 42 does not detect the depression of the brake, it is judged whether or not the accelerator pedal 18 is depressed (10b), and the reference speed (equivalent to the vehicle speed) is 50 Km / h or more. It is determined whether or not (15).
If the accelerator pedal 18 is not depressed (the throttle opening is equal to or smaller than the idling rotation opening), the vehicle does not start or accelerate, so the slip response control is unnecessary, so the routine proceeds to step 11. Further, in this embodiment, since the start acceleration slip prevention is focused on, the slip response control stop speed is set to 50 Km / h, so when the reference speed is 50 Km / h or more, the routine proceeds to step 11. The reference speed for canceling the slip response can be arbitrarily set as required.

At other times, that is, when the accelerator pedal 18 is depressed (throttle opening exceeds idling opening) and the reference speed is less than 50 Km / h, the brake control of slip response is performed as necessary. 3a to do
Steps 16R to 18R in the figure, the slip response brake control of the front right wheel shown in FIGS. 3b and 3c, and the slip response brake control of the front left wheel shown in FIG. 3d are executed.

First, the slip response brake control of the front right wheel shown in steps 16R to 18R of FIGS. 3a, 3b and 3c will be described. The front right wheel rotation speed VFR (correctly, the weighted average value) is 5 km.
/ 16 or more (16R), VFR is the reference speed VB
It is judged whether it exceeds S (17R). If the front right wheel rotation speed VFR is less than 5 km / h, the speed is extremely low (close to vehicle stop), and slip does not matter, and if the wheel rotation speed VFR exceeds the reference speed VBS. , Step 630R shown in Figure 3c, since no slip has occurred
Proceed to (63-65), set "pressure reduction" (pressure reduction in Table 1 = continuous pressure reduction in Fig. 4a), and increment the contents of the register RPRT for counting elapsed time of pressure reduction (continuous pressure reduction) by one increment, Proceed to the slip response brake control of the left wheel in FIG. 3d.

In steps 16R and 17R, the front right wheel rotation speed VFR is 5 Km / h
If the speed exceeds the reference speed VBS, it is considered that the front right wheel is rotating and there is a slip (rotation slip). Therefore, the right wheel slip ratio SFR is calculated (18R).

SFR = 100 x ( VFR- VBS) / VFR (%). After calculating the slip ratio SFR, the microprocessor 58 executes the following processing according to the right wheel slip ratio SFR and the right wheel acceleration / deceleration dFR.

(1) When SFR ≧ 35% and dFR> −0.2G (when the rotation slip ratio is high and the wheel rotation hardly decelerates).

Execute right step pressure increase 1 and 2 (210R).

A. When this condition is met for the first time, steps 21-22
Then, referring to the throttle opening (22), if the throttle opening is equal to or greater than a predetermined value (in this embodiment, a value approximately in the middle of the idling opening and the maximum opening), the step pressure increase 1
In order to execute (high speed brake pressure increase), the right pressure increase 1 flag is set and the right pressure increase 2 flag is cleared (23).
If the throttle opening is less than the predetermined value, step pressure increase 2
The right pressure increase 2 flag is set and the right pressure increase 1 flag is cleared to execute (low speed brake pressure increase) (24).
In any case, the high level H (first
High level H is set in the output register SR2 (corresponding to ON in the table) (increase pressure in Table 1) (25). And
Since the pressure is increased, the counters, flags, timers, etc. related to the pressure reduction are cleared (26), the slip response brake control of the front left wheel shown in FIG. Proceed to step 13 to set the contents of the output register to the output port. As a result, the pressure increase shown in Table 1 is set as the output.

B. Then go from step 13 to step 3 and step again
When entering 210R (right step pressure increase 1 and 2), there is a right pressure increase 1 flag or a right pressure increase 2 flag.
To 27 and refer to the presence / absence of the pause flag. At this time, since it is not present, L is set in the output register SR1 and H is set in the output register SR2 (28). As a result, the hold shown in Table 1 is set. Then, the right suspension flag is set (29), the slip response brake control of the front left wheel shown in FIG.
Proceeding to step 13 in the figure, the contents of the output register are set in the output port. As a result, the hold shown in Table 1 is output and set.

C. Then go from step 13 to step 3 and step again
When the vehicle enters 210R (right step pressure increase 1 and 2), the process proceeds to step 21-27-30, referring to which of the right pressure increase 1 flag and the right pressure increase 2 flag is set (30), C-1. When the right pressure increase 1 flag is present, the first time t ₁ = 5 mse
Since the pressure increase of c (Table 1) and the subsequent hold of t ₁ = 5 msec (Table 1) have elapsed, pressure increase (Table 4a)
In order to achieve step pressure increase 1 in the figure), output register
Set SR1 to H and output register SR2 to H (35), clear the right pause flag, and then set the contents of the output register in step 13 through the flow shown in FIG.
The procedure returns from step 13 to step 3 through step 14 (waiting for lapse of t ₁ = 5 msec).

C-2. When there is a right pressure increase 2 flag, the first time t ₁ = 5m
After the pressure increase of sec (Table 1) and the subsequent hold of t ₁ = 5 msec (Table 1) have passed, it is still necessary to hold for 5 msec (see step pressure increase 2 in Fig. 4a).
Proceed to 31-32 to set the right pause count 1 flag and keep it held. Then, when it returns to step 210R again, it proceeds to step 21-27-30-31, and at this time, it means that the hold of 5 + 5 msec has been executed. Therefore, in order to increase the pressure again, H is output to the output register SR1 again. The register SR2 is set to H (33), the right pause number 1 flag and the right pause flag are cleared (34), and the contents of the output register are output and set in step 13 through the flow of FIG. Through step 14 (waiting for lapse of t ₁ = 5 msec) to return to step 3.

By the above control operations A, B and C, SFR ≧ 35% and dF
While R> -0.2G continues, when the throttle opening is high, the mode is step pressure increase 1 (high speed brake pressure increase) shown in Fig. 4a, and when the throttle opening is low, In the step pressure increase 2 mode (low speed brake pressure increase) shown in FIG. 4a, the brake control of the front right wheel 10FR is performed.

In the operation mode of (1), the slip ratio is high and the wheels try to rotate at high speed with the engine output, but the brake pressure is correspondingly increased, so that the slip ratio is relatively quickly reduced. Since the increase in the brake pressure corresponds to the throttle opening, the action of the brake pressure is smooth.

Figure 4b shows the wheel slip ratio SFR and wheel acceleration / deceleration dFR.
And the braking operation of the microprocessor 58. The above-mentioned (1) is a region where the SFR is 35% or more in the region shown by the diagonal line to the left in FIG. 4b.

(2) When SFR ≧ 35% and dFR ≦ −0.2G (when slip ratio is high but wheels are decelerating).

First, the presence or absence of the right pressure increase flag (right pressure increase 1 flag or right pressure increase 2 flag) is referred to (37R). That is, it is determined whether the above (1) has changed to this (2). If there is a right pressure increase flag, the acceleration / deceleration dFR is compared with −2G (49
R).

A. When there is a right pressure increase flag and dFR exceeds −2G, that is, in the region shown by the cross-hatched line in FIG. 4b and when there is a right pressure increase flag (the pressure increase state immediately before), The effect of boosting is expected to be a little short now, so in order to continue boosting as it is, right step boosting 1,2 (210
Go to R).

B. When the right pressure increase flag is present and dFR is less than -2G (the deceleration is large), that is, the region of SFR 35% or more in the region shown by the cross-hatched line in Fig. 4b, and the right pressure increase When the pressure flag is present (immediately before, the pressure is increased), the deceleration of the wheel is high, so the right step depressurization of step 380R (38 to 43) is executed. This right step depressurization (contents of 380R are explained in the next section C.).

C. When there is no right pressure boost flag, the wheel condition is SFR ≧ 35%,
dFR ≦ −0.2G, that is, in the region of FIG. 4b or in the region of SFR 35% or more in the region, the wheel is decelerating, and the pressure is not increased immediately before (the deceleration of the wheel is increased. Since it is not a pressure-based deceleration), the step rate is expected to drop relatively quickly, but the slip rate is high, so
Execute 380R step decompression (relatively gentle braking force release: slowing down of braking force is slow).

When proceeding to the right step depressurization (380R), the presence or absence of the right step depressurization flag is first referenced. When the process proceeds to the right step depressurization for the first time, there is no right step depressurization flag, so the right step depressurization flag is set (39), and the output registers SR1 and SR2 are set to reduce the pressure for the first time t ₁ = 5 msec (Table 1).
Set low level L to (40). Next, the right pressure increase flag (right pressure increase 1 flag, right pressure increase 2 flag) and right hold flag are cleared, the right pressure reduction (continuous pressure reduction) time count register RPRT is cleared, and the right pause flag is cleared (41 ). Next, referring to the content of the right step depressurization number register RPRR (the number of times of depressurization of 5 msec + hold of 5 msec is one time) (42), if it is not 100 or more, one step depressurization is executed. Therefore, the content of the right step depressurization number register RPRR is incremented by 1 (43), the process proceeds to the slip response brake control of the left wheel shown in FIG. 3d, and after passing through it, the content of the output register is output to the output port in step 13. After setting, in step 14, wait for the lapse of time t ₁ = 5 msec and return to step 3. When the right step depressurization (380R) is entered again through steps 3 to 37R, the right step depressurization flag is present this time, so the process proceeds from step 38 to step 44 to refer to the presence or absence of the right pause flag. At this point, there is no right pause flag, that is, the pressure reduction of 5 msec (Table 1) has been performed.
To execute the table (see step decompression in Figure 4a), set L in output register SR1 and H in output register SR2 (45) and set the right pause flag (46). Then, it proceeds to the slip response brake control of the left wheel shown in FIG. 3d, passes through it, sets the contents of the output register to the output port in step 13, and sets t ₁ = 5 msec in step 14.
Wait for the passage of time and return to step 3. Step 3-37
When the right step decompression (380R) is entered via R again, this time there is a right step decompression flag and a right pause flag (one step decompression = decompression of 5 msec + hold of 5 msec has been completed), so steps 38-44- Proceeding to step 47, in order to execute the step depressurization once again, at step 47, L is set in the output registers SR1 and SR2 (47), the right pause flag is cleared (48), and it is shown in FIG. 3d. Proceed to the slip response brake control for the left wheel, exit it, and set the contents of the output register to the output port in step 13.
At 14, wait for the time t ₁ = 5 msec and return to step 3.
When the right step depressurization (380R) is entered again through steps 3 to 37R, this time there is the right step depressurization flag but there is no right pause flag, so proceed to step 45 and hold (first
Set the data for the table) in the output register.

By executing this right step pressure reduction (380R), the brake pressure release control of the wheel 10FR is performed in the step pressure reduction mode shown in FIG. 4a.

Now again refer to step 19R (Fig. 3b). When the right step rate SFR is less than 35%, the routine proceeds to the processing shown in FIG. 3c to execute the next processing.

(3) When the right slip ratio SFR> 10% (the right slip ratio is medium).

A. There is a right pressure increase flag, and the acceleration / deceleration dFR is 6G> d.
When FR> -2G. This is when the rotation state of the wheel is in the region of FIG. 4b or when the right pressure increase flag is present (the pressure increase was immediately before). Step 50R-51R-52R-5
Proceed to 3R and execute right hold 540R (54 to 56). That is, the brake pressure immediately before is held (waiting) and the decrease in slip is waited for. When proceeding to the right hold (540R), the right hold flag is set (54), the output register SR1 is set to L and the output register SR2 is set to H (55) to set the hold state, and the right pressure increase flag and The right step depressurization flag is cleared, and the right step depressurization count register RP
RR and right decompression (continuous decompression) time count register RPRT
Clear (56). Next, proceed to the slip response brake control for the left wheel shown in FIG. 3d, exit the control, and set the contents of the output register to the output port in step 13, wait for the lapse of time t ₁ = 5 msec in step 14, and then step Return to 3. Hold right again based on the newly read data 54
When proceeding to 0R, hold processing (540R) is also executed. Therefore, the hold mode in the left vertical column of FIG. 4a is executed.

B. There is a right pressure increase flag, and the acceleration / deceleration dFR is dFR ≧
At −2G. This is when the rotation state of the wheel is in the region of SFR <35% in the region of FIG. 4b and when the right pressure increase flag is present (the pressure increase was immediately before). That is, the wheel deceleration is large, and the wheel rotation braking by the immediately previous pressure increase has a great effect.

In this case, go through Steps 50R-51R-52R-53R to 3b
Proceed to step decompression 380R as shown. That is, since the effect of increasing the pressure is sufficiently exhibited, the brake pressure is gently reduced.

C. There is a right pressure increase flag and the acceleration / deceleration dFR is 6G ≧ d
When FR. This is when the rotation state of the wheel is in the region shown in FIG. 4b or in the region where SFR <35% of the region and there is the right pressure increase flag (the pressure increase was immediately before). Although the pressure is being boosted, the effect is not yet sufficient, so after step 50R-51R-52R, the right step boost pressure 1, 2 (21
0R) to continue increasing pressure (right step increasing pressure 1 or right step increasing pressure 2).

D. When there is no right pressure increase flag, there is no right hold flag, and when dFR ≤ -0.2G. This is when the rotation state of the wheel is in the region of FIG. 4b or in the region of SFR <35% in the region, and the immediately previous state was step decompression or decompression (continuous decompression). At this time, the wheel deceleration is high, but the slip ratio is still relatively high.
Step 50 decompression (380R) shown in Fig. 3b is executed through 50R-51R-57R-58R-59R to reduce the brake pressure at a slow speed.

E. When there is no right pressure boost flag, there is no right hold flag, and when 8G> dFR ≧ −0.2G. This is because the wheel rotation state is the 4th
This is when the region or the region of FIG. b, and the immediately previous state was step decompression or decompression (continuous decompression). At this time, the process proceeds to the right hold (540R) through steps 50R-51R-57R-58R-59R. That is, since the wheel rotation acceleration and the slip ratio are relatively high, the brake pressure is held and the transition of the wheel rotation state is waited.

F. When there is no right pressure increase flag, there is no right hold flag, and when dFR ≧ 8G. This is when the rotation state of the wheel is in the region of SFR> 35% in the region of FIG. 4b, and the immediately previous state was step decompression or decompression (continuous decompression). At this time, since the slip ratio is relatively high but the wheel acceleration is too high, it is expected that the rotation speed of the wheel will start to increase due to the immediately preceding step decompression or decompression, and the slip ratio will increase. Right step pressure increase 1,2
Proceed to (210R).

G. When there is no right pressure increase flag but there is a right hold flag and acceleration / deceleration dFR is dFR ≤ -2G. This is a region where SFR <35% in the region where the wheel rotation state is shown in Fig. 4b,
It was when the last time was a hold. Since the deceleration is high and the wheels are expected to slow down further, step 50R
-51R-57R-60R-61R through step depressurization (38
Go to 0R).

H. When there is no right pressure increase flag but there is a right hold flag and acceleration / deceleration dFR is 8G>dFR> -2G. This is when the wheel is rotating in the region shown in FIG. 4b, or immediately before the hold. Since the deceleration is not high and it is difficult to predict an increase or decrease in the slip of the wheels, to see the transition, proceed to the right hold (540R) via steps 50R-51R-57R-60R-61R.

I. When there is no right pressure increase flag but there is a right hold flag and the acceleration / deceleration dFR is dFR ≧ 8G. This is because the wheel rotation
In the area shown in FIG. 4b, the area where SFR <35%, and immediately before was the hold. Since it is expected that the acceleration will be high and the wheel slip will be even higher, after going through steps 50R-51R-57R-60R, the right step pressure increase in Fig. 3b 1,
Go to 2 (210R).

(4) When the right slip ratio SFR ≤ 10% (the right slip ratio is extremely low).

A. When the right step decompression frequency is 100 or more.

The right slip rate SFR is extremely low, and since the right step decompression has been sufficiently performed immediately before, the gradual decrease in brake pressure has begun. Even if the pressure is reduced (continuous reduction), the slip ratio does not increase and it is expected that there will be no sudden change in brake pressure.
Right decompression (continuous decompression) is performed. Decompression (continuous decompression)
Can be said to reset the slip response brake pressure control state of the brake pressure control mechanical system (return the control piston 74 to the standby position shown in FIG. 2).

Right decompression and continuous decompression) When proceeding to 630R, first, output register SR is set to set decompression mode (continuous decompression in Fig. 4a).
Set L to 1 and SR2 (63), clear right pressure increase flag, right step pressure reduction flag, right hold flag and right step pressure reduction number count register RPRR (64), right pressure reduction (continuous pressure reduction) elapsed time count register The content of is incremented by 1 (65). Next, the slip response brake pressure control of the left wheel shown in FIG. 3d is executed, the process proceeds to step 13, the contents of the output register are set in the output port, and in step 14, wait for the passage of t ₁ = 5 msec. When step 62R is reached, right step depressurization count register
Since RPRR has been cleared, proceed to step 66R. The operation after step 66R will be described below.

B. Right step depressurization count is less than 100.

To do this, immediately before this, if A. is executed to clear the right step depressurization count register RPRR, and
If you have not performed A. above, both are included. In any case, first, the elapsed time of continuous decompression is determined, and if the content of the right continuous decompression time count register RPRT is less than 20, the brake response control system resets the slip response brake pressure control state (control piston 74 Of the second
(Return to the position shown in the figure) is not completed (the brake pressure is applied to the wheel 10FL), and the left pressure increase flag (left pressure increase 1 flag or left pressure increase 2 flag) and the left hold flag are set. Refer to the presence or absence (67R, 68R). When there is a left pressure increase flag or a left hold flag, braking pressure is being applied to the front left wheel 10FL, and the front right wheel 10FR and the front left wheel 10FL are coupled to the output shaft of the transmission 14 by the differential gear 16 Therefore, if the brake pressure of the wheel 10FR is rapidly released, the rotational driving force applied to the front right wheel 10FR increases due to the braking of the front left wheel 10FL, and the rotation speed of the front right wheel 10FR is increased. To increase the slip rate SFR. Therefore, when trying to set the right continuous pressure reduction (630R), refer to the presence or absence of the left pressure increase flag and the left hold flag (67R, 68R), and when neither of them exists (the front left wheel is not in the braking state). ) To step 62R-6
Execute right decompression (continuous decompression) 630R through 6R-67R-68R,
Release brake pressure rapidly. When the left pressure increase flag or the left hold flag is present, the step pressure reduction (380R) shown in FIG. 3b is executed via steps 62R-66R-67R-68R in order to moderate the braking release of the front right wheel 10FR.

By this brake pressure release control of the right wheel 10FR with reference to the brake pressure control state of the left wheel 10FL (steps 62R to 68R), stable wheel rotation slip control is achieved for both wheels with a balanced slip ratio for the left and right wheels.

As described above. In exactly the same manner as the slip response brake pressure control processing of the front right wheel shown in step 16R of FIG. 3a to step 68R of FIG. 3c, the slip response brake pressure of the front left wheel is controlled by the control flow shown in FIG. 3d. The control process is executed, and after passing through the latter, in step 13, the data set in the output register is output set in the output port. Then, in step 14, after a lapse of time t ₁ = 5 msec, similarly, the slip response brake pressure control processing of the front right wheel and the slip response brake pressure control processing of the front left wheel are executed.

Front left wheel slip response brake pressure control processing (Fig. 3d)
In the explanation of the slip response brake pressure control processing for the front right wheel described above, "right" to "left" and "left"
Is replaced with "right". Therefore, the description of the slip response brake pressure control processing (FIG. 3d) for the front left wheel is omitted.

Incidentally, each step of the flow of FIG. 3d showing the slip response brake pressure control processing of the front left wheel is associated with each step of the flow of the slip response brake pressure control processing of the front right wheel described above, and corresponds to the corresponding step. Are denoted by the same numbers, and L is attached to the numbers to indicate the step number.

The embodiment described above is one embodiment of the present invention applied to a front-wheel drive (FF) vehicle. When implementing the present invention on a rear wheel drive vehicle, the slip response brake control system described above is combined with a rear wheel brake.

〔The invention's effect〕

As described above, according to the present invention, the wheel is braked when the slip ratio is large and the wheel acceleration / deceleration is high, and the wheel braking is released when the slip ratio is small and the wheel acceleration / deceleration is low. The pulsation is reduced and the vibration of the vehicle body is also reduced, so that the starting, acceleration performance and steering stability of the vehicle are improved.

In addition, in the case of braking (pressure increasing) as described above, when the power of the prime mover is high (wheel driving force is large), high-speed braking is performed, so the increase in slip is suppressed early,
When the operating power of the prime mover is low (wheel driving force is small), braking is performed at a low speed, preventing wheel overbraking,
These further reduce the pulsation of the vehicle speed and further suppress the vibration of the vehicle body. The starting, acceleration and steering stability of the vehicle are further improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. FIG. 2 is an enlarged vertical sectional view of the left drive wheel brake pressure control valve 28FL shown in FIG. 3a, 3b, 3c and 3d are flow charts showing the braking operation of the microprocessor 58 shown in FIG. FIG. 4a is a time chart showing the contents of each control mode executed by the microprocessor 58 shown in FIG. FIG. 4b is a graph showing control area division according to the rotation state of the wheels. 10FL: front left wheel, 10FR: front right wheel, 10RL: rear left wheel 10RR: rear right wheel, 12: engine (motor), 14: transmission 16: differential gear (14, 16: power transmission mechanism) 18: Accelerator pedal 20: Throttle opening sensor (means for detecting operating power) 22: Brake pedal, 24: Master cylinder (22,24: Brake instruction means), 26FL: Front left wheel brake 26FR: Front right wheel brake, 26RL: Rear left wheel brake 26RR: Rear right wheel brake 28FL: Left drive wheel brake pressure control valve (brake urging means) 28FR: Right drive wheel brake pressure control valve (brake urging means) 30: Motor, 32: Pump, 34: reservoir 36: accumulator, 38: pressure sensor, 40: shutter 42: photo sensor 44FL, 44FR, 44RL, 44RR: wheel rotation speed detector (means for detecting wheel rotation speed 46FL, 46FR, 46RL, 46RR: pulse shaping Circuit, 48: Binarization circuit 50, 52: Amplification circuit, 54: Motor driver 56FL1, 56FL2, 56FR1, 56 FR2: Solenoid driver 58: Microprocessor (reference speed detection means, acceleration / deceleration detection means, slip ratio calculation means, slip response control means) 60: Valve housing (fluid pressurization device) 61: Master cylinder communication port ( Input port) 62: Wheel cylinder communication port (output port) 63: Main piston, 64: Input pressure chamber, 65: Output pressure chamber 66: Compression coil spring, 67: Stopper pin 68: Guide slit, 69: Rod, 70: Spring seat 71: Through hole, 72: Ball valve, 73: Compression coil spring 74: Control piston, 75: Control port 76: Through hole, 77: Groove, 78: Through hole 79: Through hole, 80: Groove, 81: Opening 82: High pressure port, 83: Opening port, 84: Opening port 85: Low pressure port, 86: 1st plunger, 87: 2nd plunger 88, 89: Compression coil spring SLO1: 1st electric coil, SLO2: 2nd Electric coil

Claims (6)

[Claims] 1. A brake mounted on a wheel connected to a prime mover via a power transmission means; a brake instruction means; a control instruction including at least decompression and pressure increase; and a brake pressure instruction from the brake instruction means. Brake energizing means for energizing the brake in response; Means for detecting wheel rotation speed; Reference speed detecting means; Means for detecting wheel acceleration / deceleration; Wheel slip ratio calculated from wheel rotation speed and reference speed Means for detecting the operating power of the prime mover; and, in accordance with the combination of the slip ratio and the acceleration / deceleration of the wheels, an instruction to increase the pressure is issued when the slip ratio and the acceleration / deceleration are large, and the slip ratio and the acceleration / deceleration are When it is small, an instruction to reduce pressure is given to the brake urging means, and when an instruction to increase pressure is given, it is high corresponding to the operating power of the prime mover. The speed of pressure increase in the can, the slip response control means when it is low, to indicate the pressure increase of the low-speed; wheel brake control device comprising a. 2. The control instruction includes a hold; the slip response control means instructs the brake urging means: depressurize when the slip ratio is less than a first set value; If the wheel acceleration / deceleration is less than the first set value, step depressurization is performed if the wheel acceleration / deceleration is less than the second set value, hold if the wheel acceleration / deceleration is less than the first set value and less than the second set value, and step if the wheel acceleration / deceleration is greater than the second set value. Instruct to increase pressure; if the slip ratio is greater than or equal to the second set value, the wheel acceleration / deceleration is set to the third value.
The wheel braking control device according to claim (1), wherein a step depressurization is instructed when the value is less than the set value, and a step pressure increase is instructed when the value is not less than the third set value. 3. The step depressurization is a depressurization during a first predetermined time,
The wheel braking control device according to claim (2), which is a combination of depressurization and hold for holding for a second predetermined time period subsequent thereto. 4. The step increasing pressure is increased during a first predetermined time,
The wheel braking control device according to claim (2), which is a combination of a pressure increase and a hold, which is a hold for a second predetermined time period that follows. 5. A high speed step pressure increase has a large ratio of a first predetermined time to a second predetermined time, and a low speed step pressure increase has a small ratio of a first predetermined time to a second predetermined time. The wheel braking control device according to claim (4). 6. A brake is a fluid pressure brake that applies a braking force corresponding to a fluid pressure to a wheel; a brake instruction means is a brake pedal and a brake master cylinder that generates a brake pressure corresponding to the depression amount of the brake pedal; The urging means includes an input port communicating with the brake master cylinder, an output port communicating with the fluid pressure brake,
Piston working space communicating with the input port and output port,
A main piston which is housed in a piston working space and divides the working space into a space communicating with an input port and a space communicating with an output port, a control piston whose one end abuts on one end of the main piston, and the other end side of the control piston Of the fluid pressurizing / depressurizing device having a control port communicating with the space, a first electromagnetic opening / closing valve for opening / closing between the control port and the high pressure port of the fluid pressure source, and the control port and the low pressure port of the fluid pressure source. A second electromagnetic on-off valve that opens and closes the space between the wheels, according to the claims (1), (2), (3), (4) or (5). Braking control device.