JP2803591B2 - Wheel brake pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a wheel brake pressure control device for controlling the brake fluid pressure of the wheel of a vehicle.

[0002]

BACKGROUND OF THE INVENTION wheel brake pressure control device for controlling the brake fluid pressure of the wheel for a vehicle, JP-A-6-156249
What is described in the paragraph is known as prior art. This conventional technique aims to detect a predetermined behavior of a vehicle and automatically pressurize a wheel cylinder attached to wheels to suppress unstable behavior of the vehicle and increase the stability of the vehicle. The brake system disclosed in the prior art is characterized in that the brake fluid pre-pressurized by the pre-pressurizing pump is automatically pressurized to a wheel cylinder by hydraulic pressure re-pressurized by a conventional pump. It is carried out.

[0003] However, the prior art requires a preliminary pressurizing pump as a system configuration, and has problems in terms of complexity of the system configuration and cost.

Therefore, prior to the automatic pressurization of the wheel cylinders, a brake system for initial pressurizing the wheel cylinders uses a wheel cylinder pressure of a wheel determined to require the initial pressurization by slipping the corresponding wheel. Hydraulic standby control by a slip ratio servo that performs control so that the ratio becomes the target of the wheel slip ratio for which initial pressurization is not determined to be necessary is also conceivable. It is necessary to apply hydraulic pressure to the wheel cylinder to the extent that
In addition, since the initial pressurizing amount is adjusted after the wheel is slipped by the initial pressurization, a detection error of the wheel speed sensor,
In consideration of the calculation error of the control device, the initial pressurization amount lacks accuracy, the control time is long, and the hydraulic standby control cannot be said to be accurate.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a wheel brake pressure control device which can perform initial pressurization of a wheel cylinder with high accuracy and high response with a simple system configuration. That is.

[0006]

In the present invention described in claim 1 to solve the above problems SUMMARY OF THE INVENTION, a master cylinder for generating a hydraulic pressure in response to depression of the brake operating member of the vehicle, the brake operation A hydraulic pump for generating hydraulic pressure regardless of the operation of the members, a reservoir provided with a brake hydraulic fluid and communicating with the atmosphere, a wheel cylinder mounted on wheels to apply brake hydraulic pressure to the wheels, and a suction port of the hydraulic pump
A non-operating position for shutting off the reservoir from the reservoir;
Switch the suction port of the pump to an operating position that communicates with the reservoir.
A switching valve that switches between a pressure increasing position that connects at least the wheel cylinder to a discharge port of the hydraulic pump , and a pressure reducing position that connects the wheel cylinder to the reservoir; and detects a behavior of the vehicle. a vehicle behavior detection unit, when the vehicle behavior detection means detects that the behavior of the vehicle is in a predetermined first vehicle behavior region, wherein
A wheel brake pressure control device comprising: a brake pressure control unit having an automatic pressurizing mode for switching an on- off valve to an operating position and operating the hydraulic pump to introduce a hydraulic pressure to the wheel cylinder. The brake pressure control device further includes a hydraulic pressure estimating unit that estimates a hydraulic pressure value of the wheel cylinder, and a hydraulic pressure estimating unit that increases the hydraulic pressure value of the wheel cylinder if the hydraulic pressure value of the wheel cylinder is low. with the initial pressing time setting means for setting an inter-short initial pressing time the higher the value, the brake pressure control device, the vehicle behavior detection means, the behavior of the vehicle is the first
When it is detected that the vehicle is in a second vehicle behavior region wider than the vehicle behavior region, the on / off valve is switched to an operating position , and the hydraulic pump is operated to activate the initial pressure set by the initial pressurization time setting means. A wheel brake pressure control device is provided with an initial pressurizing mode for introducing a hydraulic pressure to the wheel cylinder only for a pressurizing time.

Further, in the present invention, the wheel brake pressure control device is further controlled by an electric motor for driving the hydraulic pump and the brake pressure control means. Regulator means for adjusting the power supply voltage of the electric motor, wherein the brake pressure control means adjusts the power supply voltage to the electric motor higher than during the automatic pressurization mode for a predetermined time after the start of the initial pressurization mode. The wheel brake pressure controller satisfies claim 1 wherein the regulator means is controlled. Also, in the present invention described in claim 3,
The modulator valve further selects a holding position at which the wheel cylinder is disconnected from the discharge port of the hydraulic pump and the reservoir , the initial pressurizing mode sets the modulator valve to a pressure increasing position, and sets the open / close valve to a non-pressurized position. 2. A duty holding mode in which a pressure increasing sub-mode in which the operating position is set and a holding sub-mode in which the modulator valve is set in the holding position and the opening / closing valve is set in the operating position are alternately repeated. A wheel brake pressure control device that satisfies the following conditions.

According to the present invention, the vehicle behavior detecting means includes a slip rate detecting means for detecting a wheel slip rate, and the brake pressure control means operates during the initial pressurizing mode. When the slip ratio detecting means detects that the slip ratio of the wheel has become a predetermined value or more, after reducing the hydraulic pressure of the wheel cylinder by a predetermined amount,
The wheel brake pressure control device that satisfies Claim 3 is characterized by shifting to the duty holding mode.

[0009]

According to the first aspect of the present invention, the wheel cylinder is initially pressurized for a time corresponding to the estimated value of the wheel cylinder pressure estimated by the wheel cylinder pressure estimation means. The initial pressurization can be performed with a required amount with high accuracy.

According to the second aspect of the present invention, the power supply voltage of the electric pump for driving the hydraulic pump is increased for a predetermined time after the start of the initial pressurization mode for performing the initial pressurization. The discharge amount of the brake working fluid per unit time of the hydraulic pump in the initial pressurization mode can be increased, and the initial pressurization can be performed in a short time.

According to the third aspect of the invention, since the duty holding mode is provided in the initial pressurizing mode, the brake hydraulic fluid in the wheel cylinder after the initial pressurizing can be efficiently stored.

According to the wheel brake pressure control device of the fourth aspect, when the wheel slip rate becomes larger than a predetermined value during the initial pressurizing mode, the fluid pressure of the wheel cylinder is reduced by a predetermined amount. Since the mode shifts to the duty holding mode, an excessive hydraulic pressure is not generated in the wheel cylinder due to the initial pressurization.

[0013]

1 shows a wheel brake pressure system according to an embodiment of the present invention. FIG. 2 shows various pressures of wheel brakes 51 to 54 to which various solenoid valves and sensors of the wheel brake pressure system are connected. An outline of an electric system for controlling the power supply is shown.

Referring first to FIG. 1, the brake pedal 3
When the driver steps on the vehicle, the tandem-type master cylinder 2 generates a front wheel brake fluid pressure and a rear wheel brake fluid pressure corresponding to the depression pressure. In the state shown in FIG. 1, the hydraulic pressure for the front wheel brake is changed to the electromagnetic switching valves 61 and 62.
Through the wheel brake 51 of the front right wheel FR and the wheel brake 52 of the front left wheel FL. The rear wheel brake fluid pressure is applied to the wheel brake 53 of the rear right wheel RR via the electromagnetic switching valve 63 and the electromagnetic valve 35, and to the wheel brake 54 of the rear left wheel RL via the electromagnetic valve 37.

The pump 21 is driven by the electric motor 24 to suck the brake fluid in the reservoir 70 returned from each of the wheel brakes 51, 52, 53, 54 and return it to the upstream side.

The electromagnetic switching valve 61 includes a front right wheel brake 51
Between the front wheel master cylinder pressure (first pressure) and the discharge pressure of the pump 21 (second pressure). That is, the solenoid-operated switching valve 61 operates as shown in FIG.
As shown in the figure, the front wheel master cylinder pressure is applied to the front right wheel brake 51. If the electric coil is energized simultaneously with the electromagnetic switching valve 64 and the electromagnetic switching valve 66, the electromagnetic switching valve 64 cuts the front wheel master cylinder pressure. Since the pump 21 communicates with the reservoir 4 through the electromagnetic on-off valve 66, the pump 21
Generates a pump pressure (second pressure). Then, the second pressure is communicated with the relief valve 81 to have a relief mechanism, and is applied to the front right wheel brake 51 through the pressure increasing solenoid valve 31. The electromagnetic switching valve 62 switches between the front wheel master cylinder pressure (first pressure) to the front left wheel brake 52 and the discharge pressure (second pressure) of the pump 21. That is, the electromagnetic switching valve 62 applies the front wheel master cylinder pressure to the front left wheel brake 52 as shown in FIG. 1 when the electric coil is not energized. When the power is supplied to the pump, the electromagnetic switching valve 64 cuts the front wheel master cylinder pressure, and the pump 21 is connected to the reservoir 4 by the electromagnetic switching valve 66, so that the pump 21 is driven to generate a pump pressure (second pressure). Then, the second pressure is communicated with the relief valve 81 to have a relief mechanism, and is applied to the front left wheel brake 52 through the pressure increasing solenoid valve 33. The electromagnetic switching valve 63 switches between a rear wheel master cylinder pressure (first pressure) and a second pressure. That is, when the electric coil is not energized, the electromagnetic switching valve 63 supplies the rear wheel master cylinder pressure to the electromagnetic valves 35 and 37 as shown in FIG.
3. If the electric coil is energized at the same time as the electromagnetic on-off valve 65, the rear wheel master cylinder pressure is cut, and the pump 21 is connected to the reservoir 4, so that the pump 21 is driven to generate a pump pressure (second pressure). Then, the second pressure is communicated with the relief valve 80 and provided to the solenoid valves 35 and 37 with a relief mechanism.

The solenoid valves 31, 33, 35 and 37 are energized to close them (valve closed), and the solenoid valves 32, 34, 36
And 38 are energized to open (valve open), the front right wheel brake 51, the front left wheel brake 52,
The pressures of the rear right wheel brake 53 and the rear left wheel brake 54 pass through the solenoid valves 32, 34, 36 and 38 to the reservoir.

A brake pressure transmission system for applying only the output pressure of the brake master cylinder 2 to the wheel brake, a brake pressure transmission system for anti-skid control, a brake pressure transmission system for traction control, and a control system for the brake system shown in FIG. Tables 1 and 2 show elements constituting each of the brake pressure transmission systems during power distribution control for each wheel brake. In these tables, elements constituting each transmission system are extracted and displayed in the direction from the wheel brake to the brake pressure source. In Tables 1 and 2, and in the drawings, “anti-skid control” is described as “ABS control”, and “traction control” is described as “TRC control”. In this document, “ABS” means “anti-skid” and “TRC” means “traction control”. In this embodiment, the braking force distribution control mainly includes "B-STR control" for all-wheel brakes and "2-BDC control" for rear two-wheel brakes. The “B-STR control” further includes “B-STR-OS” control for suppressing oversteer and “B-STR-US” for suppressing understeer.
Control is divided into two.

[0019]

[Table 1]

[0020]

[Table 2]

"2-BDC control", "B-STR control"
In the "TRC control", when the pressure increase is required, the electronic control unit 10 (FIG. 2) controls the solenoid valves 32, 3
4, 36, 38 are de-energized (valve closed), solenoid valves 31, 33,
35, 37 are also de-energized (valve open), and when pressure reduction is required, the solenoid valves 32, 34, 36, 38 are energized (valve open),
The solenoid valves 31, 33, 35, 37 are also de-energized (valve closed), and when hold (maintaining the current brake pressure as it is) is required, the solenoid valves 32, 34, 36, 38 are de-energized (valve closed), The solenoid valves 31, 33, 35, 37 are energized (valve closed).

Referring to FIG. The main component of the electronic control unit 10 is a microcomputer 11, and the main components of the microcomputer 11 are a CPU 14, a ROM 15,
M16 and timer 17. The electronic control unit 10 is further provided with signal processing circuits 18a to 18m for energizing (energizing) the sensors and generating detection signals, and inputting the detection signals to the microcomputer 11.
Circuit for giving the control signals of the above to the drivers 19a to 19o, that is, the input and output interfaces 12, 13,
Motor driver and solenoid driver 19a-19
There is o.

Front right, front left, rear right and rear left wheels 51-51
Each of the wheel speed sensors 41 to 44 detects the rotational speed of each of the 54, and an electric signal (wheel speed signal) representing each wheel speed is generated by the signal processing circuits 18a to 18d and supplied to the input interface 12. Opening the stop switch 45 that is closed while the brake pedal 3 is being depressed (pedal 3
Signal processing circuit 18e generates an electric signal indicating that the pedal is not depressed: off) / closed (the pedal 3 is depressed: on), and supplies it to the input interface 12.

A yaw rate sensor YA detects the yaw rate of the vehicle body.
Is detected, the signal processing circuit 18i generates an electric signal representing the yaw rate (actual yaw rate) γ, and gives it to the input interface 12. The front wheel steering angle sensor θF detects the rotation angle of the steering wheel, and the signal processing circuit 18j
An electric signal representing the front wheel steering angle θf is generated and given to the input interface 12. The rear wheel steering angle is determined by the rear wheel steering angle sensor θ.
When R detects the signal, the signal processing circuit 18k generates an electric signal indicating the rear wheel steering angle θr and supplies it to the input interface 12. The acceleration sensor (GX sensor) detects the longitudinal acceleration gx of the vehicle body, and the signal processing circuit 181 generates an electric signal indicating the longitudinal acceleration and supplies the electric signal to the input interface 12. Acceleration sensor (GY sensor)
The signal processing circuit 18m generates an electric signal indicating the lateral acceleration and supplies the electric signal to the input interface 12.

FIGS. 3 and 4 show an outline of the processing functions of the microcomputer 11 shown in FIG. FIG. 3 shows the processing functions in the form of blocks in the form of hardware, and FIG. 4 shows the same block in the form of a flowchart. FIG.
FIG. 9 shows a flowchart of the entire process repetition.

Referring to FIG. 5, after the engine on the vehicle is started, the electric system on the vehicle is turned on and the voltage of the system is stabilized, the same voltage is applied to the electronic control unit 10 (step in FIG. 3). 1; hereafter, the word "step" is omitted in parentheses, and only the step No. number is described).
When the same voltage is applied, the microcomputer 11 sets the internal register, the input / output port, and the internal timer to the initial state, and sets the input / output interfaces 12 and 13 to the input / read connection and the output signal level during standby (2). ). Then, a timer Δt for determining the processing cycle is started at a substantially predetermined cycle (3), and the processing from “sensor reading” (4) to “output control” (800), that is, the wheel brake pressure control is substantially performed. It is repeatedly executed in the upper Δt cycle.

The process from "sensor reading" (4) to "output control" (800), that is, "sensor reading" in the wheel brake pressure control, which is repeated substantially in the period of .DELTA.t.
In (4), first, all information of input means (sensors, switches, etc.) connected to the input interface 12 is read. The data used for the ABS control, the 2-BDC control (braking force distribution control for the brakes of the two rear wheels), the TRC control, and the B-STR control (braking force distribution control for the four wheels) are described as " Wheel speed calculation & wheel acceleration calculation ”(100) and“ vehicle state quantity estimation ”(200), and based on the prepared data, in“ control mode start / end processing ”(300), start,
The necessity of continuation and termination is determined, and "A
BS control "(400)," 2-BDC control "(50
0), "TRC control" (600) and / or "BS
TR control "(700) to generate wheel brake pressure operation outputs (opening and closing and timing of solenoid valves) for each of these controls, and" output control "(800).
Then, the wheel brake pressure operation output is adjusted based on the priority order of the various controls described above, and set to the output port 13. That is, the solenoid valve is operated.

"Calculation of wheel speed & calculation of wheel acceleration" (10
0) The contents of each of the following processes will be described below. The main ones of the reference information in the present embodiment are listed as follows: Information Information Source Actual yaw rate γ Detected value by yaw rate sensor YA Wheel Speed Vwi, i = FR, FL, RR, RL: Calculated from the detected values of wheel speed sensors 41 to 44 (Wheel speed VwFR Calculated from the detected value of wheel speed sensor 41 Wheel speed VwFL Calculated from the detected value of wheel speed sensor 42 Speed VwRR Calculated from the detected value of wheel speed sensor 43 Wheel speed VwRL Calculated from the detected value of wheel speed sensor 44) Longitudinal acceleration gx Detected value by longitudinal acceleration sensor GX Lateral acceleration gy Detected value by lateral acceleration sensor GY Front wheel steering angle θf Steering angle Detection value by sensor θF Rear wheel steering angle θr Detection value by steering angle sensor θR With / without wheel braking ON / OFF of stop switch 45 Wheel acceleration DVwi, i = FR, FL, RR, RL: Calculated from the detected values of the wheel speed sensors 41 to 44 (Calculated from the detected value of the wheel acceleration DVwFR wheel speed sensor 41 Wheel acceleration DVwFL Calculated from the detected value of the wheel speed sensor 42 Wheel acceleration DVwRR Calculated from the detected value of the wheel speed sensor 43 Wheel acceleration DVwRL Calculated based on the detected value of wheel speed sensor 43) Calculated based on estimated vehicle speeds Vso Vwi and DVwi Calculated based on vehicle accelerations DVso Vwi and DVwi Wheel slip ratio Si, i = FR, FL, RR, RL: Vwi and DVwi (Calculated based on the wheel slip ratio SFR VwFR and VsoFL Wheel Calculated based on the wheel slip ratio SFL VwFL and VsoFL Wheel Calculated based on the wheel slip ratio SRR VwRR and VsoRR Calculated based on the wheel slip ratio SRL VwRL and VsoRL Calculated based on road surface friction coefficient μ DVso and gy Calculated based on vehicle body slip angle β γ, gyc, Vso Car Calculated based on the lateral slip angular velocity Dβγ, gyc, Vso.

(1) "Calculation of wheel speed and calculation of wheel acceleration"
(100): FIG. 6 This content is shown in FIG. In this process, first, the counter P
i (four count registers PFR, PFL, PRR, PRL; hereinafter, i means four FR, FL, RR, RL addressed to each wheel brake, but 2-BDC control and TRC control use the last two wheels In the 2-BDC control and the TRC control, i indicates data for each of the RR and RL wheel brakes).
Clear i. The counter Pi is an electric pulse which is generated by each of the wheel speed sensors 41 to 44 and whose frequency is proportional to the rotation speed (peripheral speed) of each of the front right, front left, rear right and rear left wheels 51 to 54. In response, the number of incoming electric pulses is counted by interrupt processing.
For example, when the sensor 41 generates one pulse, the microcomputer 11 performs counter Pi, i =
Since the content of FR is incremented by one, register P
The content of i, i = FR indicates the number of pulses (a value proportional to the wheel speed) generated by the sensor 41 during Δt. Then, a correction coefficient Ksi corresponding to the tire diameter of the wheel is calculated (determined). Then, each wheel speed Vwi is calculated using the LSB (Least Significant Bit) setting correction coefficient (constant) (102).

The calculation formula is shown in the block of step 102 in FIG.

Next, the acceleration DVwi of each wheel is calculated from each wheel speed Vwi (n) calculated this time and each wheel speed Vwi (n-1) calculated last (before Δt) (103). Then, by filtering processing, time-series smoothed values DVwi and Vwi of the calculated acceleration DVwi and wheel speed Vwi are calculated, and the detected acceleration DVwi and wheel speed Vwi are calculated.
wi is written to the register DVwi (104, 105).

Next, the vehicle speed of each wheel (estimated vehicle speed of each wheel) Vsoi is calculated (106). Here, the current value Vwi (n) of the wheel speed, the wheel body speed Vso calculated last time
From i (n), the deceleration amount αdn · Δ during Δt at the predetermined deceleration
The value Vsoi (n) −αdn · Δt obtained by subtracting t and the wheel body speed Vsoi (n) calculated last time are calculated by Δ at a predetermined acceleration.
Vsoi (n) + αup obtained by adding the speed increase amount αup · Δt during t
Calculate the median value Vsoi of the three of αt, and write it to the register Vsoi as the wheel body speed Vsoi. Next, the maximum value of the vehicle speeds Vsoi of each wheel portion (four in total for each of the four wheels) is represented by the vehicle speed (commonly known vehicle speed) of the entire vehicle.
It is written into the register Vso as Vso (107).

Next, when the vehicle is turning, the speed of each wheel body Vsoi corresponding to the deviation of the direction of the wheel from the direction of travel of the vehicle corresponds to the speed of each wheel relative to the speed of the wheel body in the vehicle travel direction. The deviation Δi of the vehicle body speed Vsoi is calculated as the lateral acceleration gy
(May be the yaw rate γ), and correct the wheel speeds Vsoi of the respective wheels accordingly.
i = Vsoi-Δi is written into the register NVsoi as the normalized wheel body speed (108). Next, the normalized wheel Vsoi calculated this time and the vehicle speed NVsoi (n) are compared with the previous time (before Δt).
From the calculated normalized wheel Vsoi body speed NVsoi (n-1),
Calculate the normalized wheel body acceleration DNVsoi (four in total for each of the four wheels) and indicate the maximum value as the body acceleration (so-called body acceleration) DVso of the entire vehicle in the register DVso.
(109).

(2) "Estimation of vehicle state quantity" (200): FIG. 7 This content is shown in FIG. In this process, first, a true lateral acceleration gyc in which the lateral inclination of the vehicle is corrected is calculated from the lateral acceleration gy detected by the sensor, and this is stored in a register gyc.
(201). Next, the friction coefficient μ of the road surface is estimated and written into the register μ (202). The arithmetic expression is shown in the block of step 202. Next, the sideslip angular velocity Dβ
And the sideslip angle β are calculated as follows, and the calculated D
β and β are written into the registers Dβ and β (203 to 20).
4).

Dβ = (gyc / Vso) −γ (1) β = ∫Dβ (2) (3) “Control mode start / end processing” (300): FIG. Shown in In this process, first, in the "ABS start / end discrimination" 300A, the four wheels FR, FL, RR, R
For each of the L wheel brakes 51 to 54, brake pressure control for preventing wheel lock during wheel braking, that is, ABS control has not been started (ABSFi =
0; ABSF = 0), it is checked whether it is necessary to start it (whether the start condition is satisfied), and if it is determined that the ABS control is necessary even for the one-wheel brake, the register ABS is set.
Write 1 to F. When the ABS control has been started for each of the wheel brakes 51 to 54 (ABSFi = 1), it is checked whether it is necessary to end it (whether the end condition is satisfied), and the ABS control of each wheel brake is checked. If it is determined that it is unnecessary, 0 is written to the register ABSFi, and if it is determined that the ABS control of all the wheel brakes is unnecessary, the register AB
Write 0 to SF (synonymous with clearing register ABSF).

Next, "2-BDC start / end discrimination" 30
0B, when the braking force distribution control for the two-wheel RR and RL wheel brakes 53 and 54, that is, the 2-BDC control is not started (BDFi = 0; BDCF = 0), each of the wheel brakes 53 and 54 respectively. Is checked (whether the start condition is satisfied), and if it is determined that 2-BDC control is necessary, the register BD
Write 1 to CFi and BDCF. Each wheel brake 53,
When the 2-BDC control is started (BDCFi = 1) for each of the 54, it is checked whether or not it needs to be ended (whether the end condition is satisfied), and the 2-BDC control of each wheel brake is checked. Register B
If 0 is written to DCFi, and if it is determined that 2-BD control is not required for both the two-wheel brakes, 0 is written to the register BDCF (same as clearing the register BDCF).

Next, "TRC start / end discrimination" 300C
In each of the two wheel brakes 53 to 54, the wheel brake pressure control for reducing the acceleration slip, that is, the TRC control is not started (TRCF).
When i = 0), it is checked whether or not it needs to be started (whether the start condition is satisfied). When it is determined that the TRC control is necessary for each wheel brake, 1 is set in the register TRCFi.
Is written in the register TRCF when it is determined that the TRC control is necessary even for the one-wheel brake. When the TRC control is started (TRCFi = 1; TRCF = 1), it is necessary to end it (whether the end condition is satisfied)
Is checked, and if it is determined that TRC control is unnecessary for each wheel brake, 0 is written to the register TRCFi, and if it is determined that TRC control is unnecessary for all wheel brakes, the register TRCF is used.
0 (synonymous with clearing register TRCF).

Next, "B-STR-0S start / end discrimination" 300D is executed. This is shown in FIG. Here, first, the braking force distribution control of the four-wheel brake for suppressing oversteer, that is, the B-STR-OS control, is started (STRoF = 1) or not (STRoF = 0).
(301), if it has not started, it is in the oversteer direction (Dβ · γ <0: skid angular velocity Dβ
And yaw rate γ are in the opposite direction & gyc · γ> 0: lateral acceleration g
Check whether yc and yaw rate γ are in the same direction) (30
2,303). If it is determined that the vehicle is in the oversteer direction, that is, if Dβ · γ <0 & gyc · γ> 0, the vehicle speed V
It is checked whether the combination of so and the sideslip angular velocity Dβ is in the start area 1 (shown in the block of step 304 in FIG. 9). That is, the vehicle speed Vso is high (Vso ≧ V _1-
V ₂ ), the sideslip angular velocity Dβ is large (absolute value of Dβ ≧ α)
_{1 to} α ₂ ) (whether there is a tendency to increase oversteer) (304). If so, B-STR-O
It is determined that S control is necessary, and 1 is written to the register STRoF (306). If it is not determined that the oversteer is increasing, it is checked whether the oversteer is already excessive (305). That is, the vehicle speed Vso is high (V
so ≧ V _{3 to} V ₄ ) and the sideslip angle β is large (absolute value of β ≧
α _{3 to} α ₄ ) start area 2 (shown in step 305 in FIG. 9)
Check if it is, and if so, B-STR-O
It is determined that S control is necessary, and 1 is written to the register STRoF (306).

When the B-STR-OS control has already been started (STRoF = 1), the combination of the vehicle speed Vso and the skid angular velocity Dβ is the end area 1 (step 3 in FIG. 9).
(Shown in block 07). That is, the vehicle body speed Vso is low (Vso <V ₅₎ or to check whether the slip angular velocity D.beta smaller (absolute value of _{Dβ <α 5) (307)} . Further as is the case, the vehicle body speed Vso is low (Vso <V ₆ ~V ₇₎ or side slip angle beta is smaller (the absolute value of β <α ₆ ~α ₇₎ Exit area 2 (in step 308 of FIG. 9 (308), and if so, it is determined that B-STR-OS control is unnecessary and the register ST
Write 0 to RoF (309).

Next, "B-STR-US start / end discrimination" 300E is executed. This is shown in FIG. Here, first, the lateral acceleration gye appearing in the current front wheel steering angle .theta.f and the vehicle body speed Vso, calculated as follows: (estimated) (311): gye = Vso 2 · θf / ^{[(1 + Kh · Vso 2)} · N L: (7) N: overall steering ratio L: wheel base Kh: stability factor Next, the front wheel steering angular velocity Dθf = θf (n) −θf
(n-1) is calculated [312]. θf (n) is the front wheel steering angle θf read this time, and θf (n−1) is the front wheel steering angle θf read last time (before Δt). next,
A delay time Tdo corresponding to the steering angular velocity Dθf;
The delay coefficient k ₁ corresponding to the vehicle speed Vso are read from the memory (313, 314), the calculated (estimated) time delay _{td = Tdo × k 1 (315} ). And the delay time t
d, operation (sampling) period Δt, current step 31
Gyea = [Δt / (Δt + td)] · based on the lateral acceleration gye (n) calculated in 1 and the lateral acceleration gye (n−1) calculated previously (before Δt). gyea (n) + [td / (Δt + td) · gye (n−1) —calculated (estimated) by (8) (316). Then, the lateral acceleration gy estimated from the steering angle θf and the vehicle speed Vso
The ratio gyc / gyea of the actual lateral acceleration gyc to ea is a predetermined value k2.
Smaller than the actual lateral acceleration gyc w and a predetermined value k3 (there is an actual lateral acceleration gyc, but the actual lateral acceleration gyc is lower than the lateral acceleration gyea that should be caused by steering:
Understeer) is checked (317). If so, write 1 to the register STRuF, otherwise write 0 to the register STRuF (318, 319).

Referring again to FIG. As described above, "B-
When "STR-US start / end determination" 300E is executed,
Next, the computer 11 executes a “control priority process” 300F. As described above, ABS control, 2-BDC control,
TRC control, B-STR-OS control and B-STR-
The start / end of the US control is determined, and if necessary, the registers ABSF, BDCF, TRCF, and STRo are used.
1 is written to F and STRuF. However, for example, even if the contents of the registers STRoF and STRuF are 1, B-STR control (pressure reduction, hold, pressure increase) is not necessarily performed for all four-wheel brakes.
The wheel brake for performing the STR control is determined by "B-STR control" 700.

In this embodiment, the priority order is "ABS control".
400, “2-BDC control” 500, and “TRC control” 600, and “control priority processing” 300
In F, the “ABS control” 400 is being executed (ABSF =
1) “2-BDC control” 500 and “TRC control”
600 is prohibited (the registers BDCF and TRCF are cleared and their contents are set to 0). “2-BDC control” 50
During the execution of “0” (BDCF = 1), “TRC control” 60
0 is prohibited (the register TRCF is cleared).

The "B-STR control" 700 is executed without any other control.

"ABS control" 400, "B-STR control" 700, "2-BDC control" 500 and "TRC control"
Control 600, the sensors YA, θF, θR, G
X, GY detection values, "wheel speed calculation & wheel acceleration calculation" 1
A control value (wheel brake for controlling the brake pressure) is determined based on the calculated value at 00 and the calculated value at "vehicle state quantity estimation" 200, and the target slip ratio Soi and the actual slip ratio ( Estimated values), and a slip ratio deviation Esoi is calculated based on these values. On the other hand, a deviation (wheel acceleration deviation) ED of the wheel acceleration with respect to the reference acceleration is calculated.
i, and the combination of the slip ratio deviation Esoi and the wheel acceleration deviation EDi is set to a predetermined rapid pressure reduction region,
Determines whether it is in the pulse pressure reduction area, hold area, pulse pressure increase area or rapid pressure increase area, and determines the brake pressure control mode (rapid pressure reduction, pulse pressure reduction, hold, pulse pressure increase, rapid pressure increase) of the control wheel. I do. In addition, the pressure increase / decrease compensation processing for compensating for the delay of the pressure increase / decrease in the brake pressure control, the initial specific mode calculation for smoothing the brake pressure fluctuation at the start of the brake pressure control,
Further, an end specific mode calculation for smoothing the fluctuation of the brake pressure at the end of the brake pressure control is executed. The outline of these processing logics is “ABS control” 400, “B-
STR control "700," 2-BDC control "500, and" TRC control "600 are common, but have different functions. Therefore, in each control, a combination of control wheel selection, slip ratio deviation Esoi and wheel acceleration deviation EDi is used. Are different from each other in the brake pressure control mode, calculation constants, and the like. Since the outline of the processing logic is the same,
Hereinafter, the content of the “B-STR control” 700 will be described in detail.

(4) "B-STR control" (700): FIG. 11 This content is shown in FIG. In this processing, “B-STR
-OS control "700A," B-STR-US control "70
0B and “Slip ratio servo calculation” 100C are executed in this order.

(4A) “B-STR-OS control” 70
OA: FIGS. 12 to 19 First, FIG. 12 is referred to. First, the turning direction of the vehicle is determined with reference to the yaw rate γ, and turning direction data is written into a turning direction register (701 to 704). In this actual example,
The positive (+) polarity of the yaw rate γ indicates a left turn, and the negative (−) indicates a right turn. Next, it is checked whether the ABS control is being performed (ABSF = 1).

When the ABS control is being performed, the wheel (wheel brake) for controlling the brake pressure is controlled according to the magnitude (absolute value) of the side slip angle β and the turning direction (data of the turning direction register) in FIG. The decision is made as shown in the block of step 708. For example, when the turning direction is a left turn, when the absolute value of the side slip angle β is less than 90 °, the wheel RL is determined to be the brake pressure control target wheel (the wheel brake 54 is determined to be the pressure control target), and the absolute value of β is determined. 90 ° or more and 270 °
When the value is less than the wheel FR, the wheel FR is determined as the wheel to be subjected to the brake pressure control (the wheel brake 51 is determined as the pressure controlled object), and when the absolute value of β is 270 ° or more and less than 360 °, the wheel RL is determined as the wheel to be the brake pressure controlled ( The wheel brake 54 is determined as a pressure control target).

If the ABS control is not being performed (ABSF = 0), the wheel (wheel brake) for controlling the brake pressure corresponding to the large (absolute value) of the sideslip angle β and the turning direction (data of the turning direction register). Is determined as shown in the block of step 707 in FIG. For example, when the turning direction is a left turn, the absolute value of the sideslip angle β is 90 °.
If the absolute value of β is less than or equal to 90 ° and less than 270 °, the wheel RL is determined to be the wheel to be subjected to the brake pressure control (if the wheel FR is the wheel to be subjected to the brake pressure control). The wheel brake 54 is determined as a pressure control target), and the absolute value of β is 270 ° or more and 360 °
If less than, the wheel FR is determined as a brake pressure control target wheel (the wheel brake 51 is determined as a pressure control target).

As shown in step 707 of FIG.
° ≦ | β | <90 ° and 270 ° ≦ | β | <360 °
When the vehicle body is in the forward direction with respect to the actual moving direction, the front wheel brakes FR and FL are designated as control target wheels (the wheel brake pressure is increased), and 90 ° ≦ | β | <270 ° (the vehicle body is If it is transverse or backward with respect to the moving direction), the rear wheel brakes RL and RR are designated as control target wheels (increase the wheel brake pressure). 0 ° ≦ | β | <90 °
When 270 ° ≦ | β | <360 °, the spin moment of the vehicle is suppressed in the same manner as in the conventional example (Japanese Unexamined Patent Publication No. 3-500868), which is effective in suppressing abnormal turning or spin of the vehicle. When 90 ° ≦ | β | <270 °, abnormal turning or spin is promoted in the conventional example, but in the present embodiment, the rear wheel brake (the front wheel brake in the actual moving direction of the vehicle body) is increased in pressure. Also, the spin moment is suppressed, which has an effect of suppressing abnormal turning or spin of the vehicle.

In contrast to the above-mentioned control wheel selection (707), the ABS control at the time of braking by the driver has one object to ensure steering performance. BS control during ABS control
Even if a certain wheel brake pressure is applied as the TR-OS control, no further braking force can be obtained on the wheel, which has an adverse effect. Therefore, B-STR-
In the OS control, the brake of one wheel at a diagonal position of the wheel is reduced in pressure instead of the wheel brake to be pressurized.

For example, ABS control is not specified (A
When BSF = 0), at step 707, B-S
Front wheels FR / FL when TR-OS control is performed at 0 ° ≦ | β | <90 ° and 270 ° ≦ | β | <360 °
(Wheel brake), 90 ° ≦ | β | <270
In the case of °, the rear wheel RL / RR is determined. When ABS control is specified (ABSF = 1), 0 ° ≦ | β | <90
And 270 ° ≦ | β | <360 °, rear wheel RL
/ RR is the brake pressure control target wheel, and 90 ° ≦ | β | <
When the angle is 270 °, the front wheel brake FR / FL is set as a control target wheel. Thereby, ABS control and B-STR-OS
Control harmonizes.

Note that "control wheel selection" 705 shown in FIG.
In this example, only the one-wheel brake is determined as the control target brake. However, the “control wheel selection” 705 is replaced with the “control wheel selection” 705A shown in FIG. 13 so that the two-wheel brake is determined as the control target brake. Is also good. In addition, the "control wheel selection" 705 is replaced with a "control wheel selection" 705B shown in FIG. 14, so that one-wheel brake is determined as a control target brake during ABS control, and two-wheel brake is controlled when ABS control is not performed. The target brake may be determined. Further, the "control wheel selection" 705 is replaced with a "control wheel selection" 705C shown in FIG. 15, and the two-wheel brake is determined as the brake to be controlled during the ABS control, and the one-wheel brake is used when the ABS control is not performed. The control target brake may be determined.

Next, reference is made to FIG. When the wheel for controlling the brake pressure is determined, the gain K corresponding to the road surface friction coefficient μ (data of the register μ) is read from the memory and saved in the register (706), and then the absolute value of the sideslip angular velocity Dβ and the sideslip angle It is determined which of the areas A0 to A7 shown in the block of step 707 in FIG. 16 the combination of the absolute values of β is (707). That is, the region Aj, j = 0 to 7, to which the combination of the absolute value of the sideslip angular velocity Dβ and the absolute value of the sideslip angle β belongs is determined. Next, FIG.
, The slip ratio correction amount ΔSi (%) of each wheel allocated to the area Aj is read from the memory (70).
8). The slip rate deviation target value ΔS (%) in “B-STR control” 700 and “2-BDC control” 500 is, as shown in the block of step 708 in FIG. ΔSi (%) is j. In addition, in the block of step 708 in FIG.
Slip rate correction amount Δ assigned to region Aj in “ABC control” 400 and “TRC control” 600
It also shows Si (%).

Next, the computer 11 proceeds to step 706
The slip rate correction amount ΔSi (%) corresponding to the region Aj is multiplied by the μ-corresponding gain K obtained in (FIG. 16) to calculate a slip ratio correction amount ΔSsoi = K · ΔSi for each wheel brake (709).

Next, referring to FIG.
Requires "B-STR-OS control" (STRoF = 1)
(710), and if necessary, referring to the data in the turning direction register, and if it indicates a left turn, the target rudder corresponding to the absolute value of the sideslip angle β shown in the block of step 712. Of the angle δr, the one corresponding to the absolute value of the register β is read from the memory and written into the register δr (712). If the data of the turning direction register indicates a right turn, the data corresponding to the absolute value of the register β in the target steering angle δr corresponding to the absolute value of the side slip angle β shown in the block of step 713 is stored. Is read out and written into the register δr (713).

Data of register SRoF and register δ
The data of r, the yaw rate γ, the front wheel steering angle θf, and the vehicle speed Vso are referred to as “output control” 800 (FIG. 5).
Is transferred to the 4WS controller 70 (FIG. 2). As described later, the 4WS controller 70 controls the rear wheels RR, RR so as to realize the given steering amount δr (direction and amount).
Steer the RL.

Determination of the above-mentioned steering amount δr (710 in FIG. 18)
713), the steering amount δr increases as β increases from 0 ° corresponding to the absolute value | β | of the sideslip angle β, and the steering amount δr increases as | β | approaches 90 °. The steering direction (polarity of δr) with respect to the vehicle front-rear axis X is reversed at 90 °, and the steering amount δr increases as | β | increases from 90 °, and as | β | approaches 360 °, To reduce the steering amount δr.

Thus, the side slip angle from 0 ° | β |
The steering amount is increased with an increase in the steering angle. Therefore, as the amount of change in the unintended direction of the vehicle body increases, the steering amount δr in the direction of suppressing the change increases. As | β | approaches 90 °, at which the direction of the vehicle body is reversed with respect to the actual moving direction, the steering amount δr is reduced, and at 90 °, the steering direction with respect to the vehicle front-rear axis X is reversed. There is no steering that promotes the reverse direction when switching to the opposite direction to the moving direction, and the steering direction (δr
) Is also switched to the direction in which spin is suppressed, so that the effect of suppressing abnormal turning of the vehicle or spin is extremely high.

FIG. 19 shows the configuration of the 4WS controller 70. Simply put, the 4WS controller 70 multiplies the front wheel steering angle θf by a coefficient (gain) corresponding to the vehicle speed Vso to calculate a steering angle corresponding to the main steering, and performs vehicle travel at the time of disturbance (cross wind) or vehicle turn. A steering angle correction amount is calculated corresponding to the yaw rate γ, the front wheel steering angular speed and the vehicle speed in order to suppress the direction fluctuation, and a target steering angle AGLA is determined from the calculated steering angle and steering angle correction amount. Specifically, the front wheel steering angle value θf
Then, the low angle value is reduced to 0 through the conversion units 21AS and 21BS, the excessive angle is converted to a saturation value, the dead zone processing and the limit processing are performed, and the detected steering angle value is converted into a steering angle value required for control calculation. Steering angle value (conversion value) for control calculation by 23S
Is multiplied by a vehicle speed corresponding gain to calculate an auxiliary steering angle (required value) corresponding to the actual steering angle. On the other hand, the yaw rate γ is first converted by the conversion units 51S and 55S to 59S into a calculation yaw rate AYs using the dead zone width 2Wyo corresponding to the front wheel steering angular velocity and the conversion coefficient Ic, and the gain G corresponding to the vehicle speed Vso is obtained.
The conversion unit 52S calculates y, and the multiplication unit 53 multiplies the calculation yaw rate AYs by the gain Gy to calculate a steering angle correction amount. Then, the adder 54S adds a steering angle correction corresponding to the detected yaw rate γ to the auxiliary (rear wheel) steering angle (required value) and outputs the result to the feedback controller 60S as a target steering angle AGLA.

The feedback control unit 60S basically constitutes a PD (proportional / differential) control system, and a deviation ΔAG between the target steering angle AGLA and the detected actual steering angle RAGL.
It is configured to output a control amount according to L. The output DAGLA of the differential control system 61S and the output PAGLA of the proportional control system 52S are added by the adder 35, and the control amount HPI
D, the data of the register SRoF transferred from the computer 11 is 1 (B-STR-OS
In the case of (control required), the target steering angle AGLA is changed to δr transferred from the computer 11.

In the proportional control system 62S, the input value ΔA
The GL is converted to ETH3 through the conversion unit 31BS, and is multiplied by the proportional gain Ga17 in the multiplication unit 36S, and the result becomes the output PAGLA. In this example, the gain Ga17
Is a constant.

In the differential control system 61S, the input value ΔA
The GL is converted into ETH2 through the conversion unit 31AS, and the input value ETH2 (the latest value) and the input value ETH2 (the value before a predetermined time) through the delay unit 32S in the subtraction unit 33S.
Is calculated, thereby obtaining the rate of change of ETH2, that is, the differential value SETH2. In the multiplying unit 34S, the differential value SETH2 and the differential gain YTDIFGAIN
Is obtained as the output DAGLA of the differential control system 61S.

In this example, the differential gain YTDIFGAIN is a variable determined based on the differential value (change speed) of the target steering angle AGLA when SRoF = 0.
When TRoF = 1, it is a variable determined based on the differential value (change speed) of δr. That is, the difference between the input value AGLA (the latest value) or δr (the latest value) and the input value AGLA (the value before Δt) or δr (the value before Δt) passed through the delay unit 37 is calculated by the subtraction unit 38S. Is calculated, whereby the rate of change of AGLA or δr, ie the derivative SA
GLA is obtained, and the result of passing the differential value SAGLA through the converter 39 becomes the differential gain YTDIFGAIN. The graphs shown in the blocks of the converters 31AS, 31BS, and 39S indicate the respective conversion characteristics, with the horizontal axis indicating the input value and the vertical axis indicating the output value.

Control amount HPI output from adder 35S
D passes through the converter 43S to become HPID2, and further passes through the converter 44S to become the duty value DUTY. The conversion unit 43S functions as a limiter. The conversion unit 44S
Has a function of converting a deviation steering angle value into a duty value. The duty value DUTY is a pulse width modulation (PWM)
Input to the unit 45S. The pulse width modulator 45S generates a duty pulse signal corresponding to the input value, and applies the pulse signal to the driver DV1. When the rear wheel steering electric motor M1 rotates, a pulse corresponding to the rotation amount is output from the magnetic pole sensor RS. The steering angle converter 46S identifies the rotation direction from the phases of the three-phase pulses output from the magnetic pole sensor RS, calculates the number of pulses in the addition direction or the subtraction direction according to the direction, and calculates the rear wheel steering angle. . The steering angle converter 46S calculates the actual steering angle R
Outputs AGL. The subtraction unit 47S calculates the target steering angle AGLA
And the actual steering angle RAGL, that is, the steering angle deviation ΔAGL is input to the control unit 30S.

The rear wheel steering electric motor M1 drives a mechanism (not shown) for steering the rear wheels RR and RL. When the data in the register SRoF transferred from the computer 11 is 1 (B-STR-OS control required), 4WS
As described above, since the controller 70 changes the target steering angle AGLA to δr transferred from the computer 11 and energizes the motor M1 to provide this steering angle, when δr changes greatly to suppress oversteer, , The rear wheel steering amount increases, and the 4WS controller 70
Rear wheel steering for securing stability in the vehicle traveling direction acts strongly, and oversteer is strongly suppressed.

Note that "B-STR-OS control" 700A
Is used as an input parameter for the wheel brake pressure control (pressure increase, hold, pressure reduction) in the "slip rate servo calculation" 700C described later, and is reflected in the wheel brake pressure control. You.

(4B) “B-STR-US control” 70
0B: FIG. 20 The computer 11 calculates the reference vehicle speed Vsou as follows (717): Vsou = √ [(1 + Kh · Vso ² ) · N · L · gyc / θf] (9) Deviation Δ of reference vehicle speed Vsou from speed Vso
V = Vsou−Vso is calculated, and each wheel slip ratio correction amount ΔSiu is calculated (718). That is, the larger of the value obtained by multiplying the product of the constants Ki and ΔV assigned to the respective wheels and ΔV and the μ-corresponding gain K (706, FIG. 16) by − (minus) and 0, the larger the wheel slip ratio correction amount ΔSiu And

(4C) “Hydraulic standby control” 700
C: FIG. 26 FIG. 2 shows the contents of the “hydraulic standby control” 700C of FIG.
6 is shown. Here, first, the "B-STR"
-OS start / end determination "300D (FIG. 9), it is checked whether there is a possibility that it is determined that start is necessary (pressure increase is necessary) (901, 902). That is, step 304 in FIG.
In the start area 1 shown in FIG. 26, it is checked whether the combination of Vso and Dβ is included in the start area 3 (step 901 in FIG. 26) in which the vehicle body speed Vso and the skid angular velocity Dβ are shifted to lower values. Then, it is determined that there is a high possibility that “pressure increase” will be performed thereafter (901). When it is not in the start area 3, the start area 2 shown in step 305 in FIG.
In the start area 4 (step 902 in FIG. 26) in which the vehicle speed Vso and the sideslip angle β are shifted to lower values, Vso and β
Is checked, and if it is included, it is determined that there is a high possibility that the pressure will be increased afterwards (90
2). When it is not within the start area 4, it is determined whether there is a possibility that it is determined that start is necessary (pressure increase is required) soon in the “B-STR-US start / end determination” 300E (FIG. 10). Check (903). In “B-STR-US start / end determination” 300E, in step 317, gyc
/ Gyea <k2 and the lateral acceleration gyc> k3 are the conditions for determining that the start is necessary. Therefore, in step 903 (FIG. 26), gyc / gyea ≦ Pk2, Pk2> k2
Also, it is checked whether the lateral accelerations gyc ≧ Pk3 and Pk3 <k3, and gyc / gyea ≦ Pk2 and gyc
If ≧ Pk3, it is determined that there is a high possibility that “pressure increase” will be performed thereafter (903).

Here, there is a relationship shown in FIG. 27 between the slip ratio S of the vehicle wheels to the road surface and the coefficient of friction μ between the wheels and the road surface. Here, the positive region (the right side in FIG. 27) of the horizontal axis corresponds to the braking state of the wheel, and the negative region (the left side in FIG. 27) corresponds to the driving state of the wheel.

B-STR-US control or B-STR
At the start of the OS control, assuming that the wheel state is at point A in FIG. 27, the wheel cylinder attached to the wheel is subjected to B-STR-US control or B-STR-O
The time required to increase the pressure to the point B in FIG. 27 which is the target hydraulic pressure value for the S control: ΔP ** t is represented by the following equation (1).

ΔP ** t ≒ ΔWC ** t + ΔWC0 ** t + ΔWCD ** t (1) ΔWC ** t: Linear region pressure increasing time ΔWC0 ** t: Non-linear region pressure increasing time ΔWCD ** t: Drive region pressure increase time Non-linear region pressure increase time: ΔWC0 ** t is expressed by the following equation (2). (FIG. 28) ΔWC0 ** t = KT * −ΔWC0 ** t0 (2) ΔWC0 ** t0: Pressure increase time until start of hydraulic standby control However, ΔWC0 ** t ≧ 0 KT *: * Pressure increase time until wheel cylinder pressure of wheel rises ΔWC0 ** t0 = Q0 ** t0 / KQt * ... (3) t0: tKQt * at the start of hydraulic standby control: From hydraulic pressure to time Here, the initial hydraulic pressure estimated value: Q0 ** t is estimated by the following means while being distinguished between normal braking and wheel brake pressure control.

[At the time of wheel brake pressure control] It is obtained by the following equation (4).

Q0 ** t = Q0 ** t-1 + KUP * TUP ** Δt−KDOWN * TDOWN ** Δt (4) Q0 ** t-1: Previous calculation of Q0 ** t Value TUP **: Equivalent pressure increase time TDOWN **: Equivalent pressure reduction time KUP *: Pressure increase gradient value KDOWN *: Pressure reduction gradient value Δt: Time interval of t, t-1 [Normal braking] Equation (5) below Is determined by

Q0 ** t = MCt (5) MCt: master cylinder pressure value In the above, Q0 ** t uses the master cylinder pressure sensor, which is the estimated vehicle body acceleration. Or the like.

Here, returning to the above equation (2), the initial pressurizing time required at the time of hydraulic standby control is considered.
Non-linear region pressure increase time: KT * is a unique value determined by the capacity of the wheel cylinder, hydraulic pump, and the like. Therefore, for example, for the front wheel side wheel cylinder, 100 mse
c. For the wheel cylinder on the rear wheel side, it is determined as 70 msec.

Now, for example, if it is determined in FIG. 1 that there is a high possibility of "pressure increase" of the front wheel FR (hydraulic standby wheel), the above-described calculation will first make the initial hydraulic pressure estimated value Q
0FR is calculated by the above equation (4) or (5) depending on whether the time is during the wheel brake pressure control,
From this, ΔWC0 ** t0 is calculated using equation (3). Further, from these calculation results, ΔWC0 *
* t is calculated (step 208 in FIG. 7). At this time, in FIG. 1, the electromagnetic switching valves 61 and 64 and the electromagnetic opening / closing valve 66 are excited and the motor 24 (the pump 21) is turned on.
, And the wheel brake 51 and the pump pressure (second brake pressure) of the front wheel FR, for which it is determined that the possibility of “pressure increase” is high.
And brake hydraulic fluid is introduced for the calculated time ΔWC0 ** t.

Returning to FIG. 26, the description will be continued. If it is determined in step 903 of FIG. 26 that the possibility of “pressure increase” is high, the motor 24 is energized in step 904. At this time, when recognizing the start of the hydraulic standby control, the microcomputer 11 sends a boost signal to the regulator REG in FIG. The regulator REG excited by the boost signal is connected to the motor driver 19a.
The power supply voltage is boosted and introduced. Therefore, although the power supply voltage of 12 V is normally introduced to the motor driver 19 a, the voltage is increased to, for example, 14 V and introduced during the hydraulic standby control. Since the motor 24 is driven by the boosted power supply voltage, the discharge efficiency of the pump 21 can be improved (step 905).

Next, in step 906, the wheel determined to have a high possibility of "pressure increase" is the front wheel, that is, FR.
It is determined whether the wheel is the wheel or the FL wheel. If it is determined in step 906 that the wheel determined to have a high possibility of “pressure increase”, that is, the wheel subjected to the initial pressurization control by the hydraulic standby control is the front wheel, in step 907, the electromagnetic switching valve 64 and The electromagnetic on-off valve 66 is energized, and the suction port of the hydraulic pump 21 communicates with the reservoir 4.

Further, when it is determined in step 908 that the control wheel is the front right wheel, ie, the FR wheel, step 90
At 9, the electromagnetic switching valve 61 is energized, and the FR wheel communicates with the discharge port of the hydraulic pump 21, and the initial pressurization mode for the FR wheel proceeds (step 910).

If the slip ratio of the target wheel falls outside the predetermined control range during the initial pressurizing mode for the FR wheels, for example, becomes 1% or more, the microcomputer 11 starts the initial pressurizing mode. It is determined that the application of the brake fluid pressure to the target wheel by this causes the braking force to be generated (step 911), and the slip ratio is adjusted to set the duty holding mode (step 913).

On the other hand, if the wheel (hydraulic standby wheel) determined to have a high possibility of "pressure increase" is the rear RR wheel or the RL wheel, Steps 906 to 9
19, the electromagnetic switching valve 63 and the electromagnetic on-off valve 65
And the suction port of the hydraulic pump 21 communicates with the reservoir 4 to start an initial pressurizing mode for the rear wheel brake (step 920).

Here, the wheel determined to have a high possibility of "pressure increase", that is, the wheel to be subjected to the initial pressurization mode is, for example, R
In the case of the R wheel, the RL wheel, which is the non-target wheel, uses the same slip ratio as the target wheel as the FR wheel, which is the non-target wheel of the front wheel, as a target value.
The slip ratio servo control is performed, so that the brake pedal 3 can be further depressed.

If the slip ratio of the FR wheel is less than 1% in step 911, the FR wheel proceeds to the duty holding mode (step 913) after the pressurization for ΔWC0FR is completed in step 912. In this mode, both the solenoid valve 31 and the solenoid on-off valve 66 are de-energized,
And the ON mode in which both are energized alternately.

As a result, the cavitation in the brake system by the driving of the hydraulic pump 21 and the hydraulic pump 21 until the pressure increase in the linear region is started by the B-STR-US control or the B-STR-OS control. And the brake pedal 3 can be used to increase the number of uncontrolled wheels.

In FIG. 1, check valves 88 and 89 are provided.
Are electromagnetic switching valves 63 and 64 and electromagnetic switching valves 65 and 6
6 is used as a bypass at the time of failure.

The "hydraulic standby control" described above 7
00C, "B-STR-OS control", ie, before increasing the wheel brake pressure to suppress oversteer, and "B-STR-US control", ie, increasing the wheel brake pressure to suppress understeer. Before driving the pump 21 by the motor 24 is started,
A wheel brake, which is likely to require a pressure increase, is connected to a pump (second brake pressure source) to perform initial pressurization control of the wheel brake. That is, the front brake, which requires pressure increase, and the wheel brake, which is likely to require pressure increase, communicate with the second brake pressure source. As a result, there is no delay in the rise of the pressure increase.

(4D) “Slip ratio servo calculation” 70
0D: FIG. 21 First, whether "B-STR-OS control" is necessary or "B-ST
Check if it is necessary for "R-US control" and check "B-ST
If the R-OS control is necessary (STRoF = 1), the data of the register ΔSio (calculated in step 709) is selected as the slip ratio deviation ΔSi, and the “B-STR-US control” is required (STRuF = 1). And slip rate deviation ΔS
i, the data of the register ΔSiu (step 718)
Is calculated (721 to 726). "B-STR
-OS control "unnecessary (STRoF = 0) and" B-ST "
When the “R-US control” is unnecessary (STRuF = 0), the slip ratio correction amount ΔSi is set to 0 (721 to 72).
6).

Next, assuming that the slip rate target value Soi is the slip rate correction amount ΔSi (727) and that the ABS control is required (ABSFi = 1), the slip rate target value Soi
The slip rate target value SoABSi defined in the “ABS control” is added to oi, and the sum is updated as the slip rate target value Soi (728, 729), and “2-BDE control” is required (BD
CFi = 1), the slip ratio target value Soi is set to “2-
Slip ratio target value SoBDC defined in "BDC control"
i, the sum is updated as the slip rate target value Soi (730, 731), and "TRC control" is required (TRCFi =
1) If the slip ratio target value Soi is "TRC control"
Add the slip rate target value SoTRCi specified in
The sum is updated as the slip rate target value Soi (732),
"B-STR control" required (STRoF = 1 or STRuF
= 1), "B-STR" is added to the slip ratio target value Soi.
The control unit adds the slip rate target value SoSTRi defined in the “control” and updates the sum as the slip rate target value Soi (73
4,735).

In this embodiment, the slip ratio target value SoABS
i, SoBCDi, SoTRCi and SoSTRi are fixed values and So
ABSi = 0.15, SoBCDi = 0.01, SoTRCi = −
0.07 and SoSTRi = 0.

The above-mentioned "control priority processing" 300F
Is executing the “ABS control” 400 (ABSFi = 1)
Executes “B-STR control” 700 (register ST
RoF and STRuF data are not changed)
"2-BDC control" 500 and "TRC control" 600
Is prohibited (the registers BDCF and TRCF are cleared and their contents are set to 0), and while the “B-STR control” 700 is being executed (STRoF = 1 or STRuF = 1), the “ABS control” 400 is executed (register) ABSF is not cleared), but “2-BDC control” 500 and “TRC control” 600 are prohibited (registers BDCF and TRCF are cleared to zero), and “2-BDC control” 5
During the execution of “00” (BDCF = 1), “TRC control” 6
00 is prohibited (the register TRCF is cleared), so that ABSF = 1, SRoF = 1 or STRuF = 1
In this case, BDCF = 0 and TRCF = 0, and the target slip ratio Soi calculated in steps 728 to 735 does not include SoBDCi and SoTRCi. ABSF =
0, STRoF = 0 and STRuF = 0, BDCF
When = 1, BTRC = 0, so the slip ratio target value Soi is the slip ratio correction amount (corresponding to ΔSi) calculated for the “2-BDC control” (by the calculation corresponding to steps 721 to 727). + SoBDCi. When ABSF = 〇, SRoF = 0, STRuF = 0, and BDCF = 0 and TRCF = 1, the slip ratio target value Soi is calculated by the slip calculated by the calculation corresponding to the above steps 721 to 727 for “TRC control”. The rate correction amount (corresponding to ΔSi) + SoTRCi.

ABSF = 1, STRoF = 0 and ST
When RuF = 0, BDCF = 0 and TRCF = 0, and the slip rate target value Soi is the slip rate correction amount (the ΔSi calculated above) calculated for the “ABS control” (by the calculation corresponding to steps 721 to 727). + S)
oABSi. ABSF = 0, SRoF = 1 or ST
When RuF = 1, BDCF = 0 and TRCF = 0, and the slip ratio target value Soi is the slip ratio correction amount ΔSi + SoSTRi calculated by the calculations in steps 721 to 727 for “B-STR control”.

Referring to FIG. After calculating the slip rate target value Soi as described above, the computer 11 calculates the slip rate deviation Esoi and the wheel acceleration deviation EDi of each wheel as follows (736): Esoi = Soi− (reference speed−control wheel). Speed−BVWi) / Reference speed (10) EDi = Reference acceleration−Control wheel acceleration (11) Since the processing here is for B-STR control, the reference speed, control wheel speed, and reference acceleration are used. And the control wheel acceleration are represented by “BS” in the table in the block of step 736.
TR control ".

Next, it is checked whether the absolute value of the slip ratio deviation Esoi is smaller than a predetermined value ε (737A), and the integrated value IEsoi of the slip ratio deviation Esoi that is equal to or larger than the predetermined value ε.
Is calculated (737B). That is, the value obtained by adding the gain GIi × the currently calculated slip rate deviation Esoi to the previously calculated slip rate deviation integrated value IEsoi is defined as the currently calculated slip rate deviation integrated value IEsoi. Gain GIi
Is 1 in this embodiment. The slip ratio deviation integral value IEsoi is set to be equal to or less than the upper limit value IEsoi U and the lower limit value IEsoi L
In order to restrict the above, if IEsoi is equal to or greater than IEsoi U, the slip rate deviation integrated value IEsoi is set to the upper limit IEsoi U
If the value is equal to or smaller than IEsoi L, the value of the slip ratio deviation integrated value IEsoi is updated to the lower limit IEsoi L (738).
７４741). IEsoi is cleared to 0 when | Esoi | <predetermined value ε (737C).

Next, a parameter Y for determining the brake pressure control mode is calculated as follows: Y = Gsoi · (Esoi + IEsoi) (12) Gsoi is a gain, and as shown in FIG. 24, a small value when the absolute value of the sideslip angle β is small,
When it is large, the value is large.

Next, another parameter X for determining the brake pressure control mode is calculated as follows: X = GEDi · EDi (14) GEDi is a constant (fixed value).

Referring to FIG. Next, the computer 11 sets the combination (X, Y) of the parameters X and Y to any of the predetermined rapid pressure reduction region, pulse pressure reduction region, hold region, pulse pressure increase region, and rapid pressure increase region by memory access. (74)
6). For example, if the control wheel is FR (wheel brake 51)
In the case of (1), if it is determined in the subsequent control (“output control” 800) that the region is in the rapid pressure reduction region, the pressure is reduced (the electromagnetic switching valve 61 is energized, the electromagnetic valve 31 is energized (valve closed) and the electromagnetic valve 32 is energized (valve open). ] (Continuation) is set. If it is determined to be in the pulse pressure reduction region, the above-described pressure reduction for a predetermined time and holding for a predetermined time (energization of the electromagnetic switching valve 61, energization of the electromagnetic valve 31 (valve closed), and non-energization of the electromagnetic valve 32 (valve closed)) are repeated. Set. If it is determined that the area is the hold area, the continuation (continuation) of the hold is set. When it is determined that the pressure is in the pulse pressure increasing region, the pressure is increased for a predetermined time (the electromagnetic switching valve 61 is energized,
The solenoid valve 31 is de-energized (valve opened) and the electromagnetic valve 32 is de-energized (valve closed)], and the repetition of the hold for a predetermined time is set. When it is determined that the pressure is to be rapidly increased, the continuation (continuation) of the pressure increase is set.

Here, the oversteer compensation control (B-ST
The process leading to the setting of the increase, decompression, and the like in the R-OS control is summarized as follows.
2 (FIG. 7), a coefficient K corresponding to the friction coefficient μ, that is, a coefficient K having a large value when μ is high, is calculated by a step 706 (“B-STR-OS control”) 700A in “B-STR-OS control” 700A. 16). In the next step 707 (FIG. 16), the sideslip angle β and the sideslip angular velocity D
It is determined which of the areas A0 to A7 the combination of β belongs to, and in the next step 708 (FIG. 17), the slip ratio correction amount ΔS is determined for each area. That is, the slip rate correction amount ΔS is determined to be larger as the side slip angle β is larger and the side slip angular velocity Dβ is larger, corresponding to the side slip angle β and the side slip angular velocity Dβ. And
The product K · ΔS of the coefficient K and the slip ratio correction amount ΔS is defined as each wheel correction amount ΔSi (709 in FIG. 17), and each wheel correction amount Δ
The target slip ratio Soi is the sum of Sio and the target value SoSTRi for B-STR control (723, 725, 727, 734, 73 in FIG. 21).
Five). Then, the slip ratio deviation Esoi and the acceleration deviation ED
i is calculated (736 in FIG. 22), the integrated value IEsoi of the slip ratio deviation Esoi is calculated, and this is set to Y, and the acceleration deviation ED is calculated.
i is X (737 to 745 in FIG. 22), and according to X and Y,
If X and Y are positive and these values are both large, pulse pressure increase or rapid pressure increase is set. If X and Y are not and their absolute values are both large, pulse pressure decrease or rapid pressure decrease is set (FIG. 23). 746).

By setting such wheel brake pressure,
For example, when the sideslip angle β increases, the target slip ratio S
Since oi is set to a large value, the wheel brake pressure is adjusted so as to increase the actual slip ratio (the actual output for performing this pressure adjustment is performed by “output control” 800 (FIG. 5) described later). . As a result, the wheel brake pressure is increased, and a moment opposite to the spin moment generated due to the increase in the side slip angle is generated, and the increase in the side slip angle is suppressed.

When the friction coefficient μ is high, it is expected that the increase in the wheel brake pressure will effectively suppress the increase in the sideslip angle, that is, the spin behavior. In this case, 706 (FIG. 1)
Since the target slip ratio Soi is determined to be a large value according to 6), the vehicle spin suppression effect is high.

On the other hand, if the friction coefficient μ is low, not only is the effect of suppressing the vehicle spin caused by increasing the wheel brake pressure low, but also the yaw motion of the vehicle body may be disturbed. In this case, 7
Since the target slip ratio Soi is determined to be a small value by 06 (FIG. 16), the increase and decrease of the wheel brake pressure are suppressed. Since the friction coefficient μ is used as a parameter of the wheel brake pressure control for oversteer compensation, the stability of oversteer compensation is improved.

On the basis of the vehicle body slip angle β, the friction coefficient μ and the slip angle velocity Dβ, the slip angle velocity Dβ
Is large, a large target slip rate Soi is determined, and the slip rate deviation Esoi = the target slip rate Soi−the actual slip rate, and the acceleration deviation EDi = the acceleration DNVso of the wheel which is not determined to increase, the pressure reduction is determined to increase, the pressure reduction. Wheel acceleration DNV
When the deviations ESoi and EDi are positive and the absolute values thereof are large, the pressure increase is determined, and when the deviations ESoi and EDi are negative and the absolute value is large, the pressure decrease is determined. The slip rate is controlled to the rate Soi retarded. As a result, the slip rate becomes larger than other uncontrolled sums,
An anti-spin moment is created.

Next, understeer compensation control (B-STR)
-US control) to increase or decrease pressure (step 7 in FIG. 23).
To summarize the process leading to 46), the lateral acceleration gyc detected by the lateral acceleration sensor GY (exactly, step 2 in FIG. 7)
The value corrected by 01) is a value corresponding to the actual turning of the vehicle body, and is large when the turning speed is high and small when the turning speed is low. A reference lateral acceleration gye is calculated in step 311 in FIG. 10 in accordance with the steering amount θf and the vehicle speed Vso,
In steps 312 to 316, the reference lateral acceleration gye is subjected to a correction corresponding to a delay in turning with respect to turning, and when the reference lateral acceleration gyea is gyc <k2 · gyea, gy is obtained.
Under the condition of c> k3, 1 is written to the register STRuF (312 to 318 in FIG. 10).

At step 717 in FIG. 20, a reference vehicle speed Vsou at which the lateral acceleration gyc is generated on the vehicle body with the steering amount θf is estimated, and the vehicle speed Vsou relative to the reference vehicle speed Vsou is calculated.
target slip ratio deviation ΔSiu corresponding to deviation ΔV of so
Is determined, and this is added to the reference slip ratio SoSTRi defined in the B-STR-US control, and the sum is set as the target slip ratio Soi (724, 726, 727, 727 in FIG. 21).
732, 735). Then, the actual slip ratio of the wheel is estimated and calculated based on the wheel rotation speed Vwi and the vehicle speed Vso, and the slip ratio deviation Esoi and the acceleration deviation EDi are calculated.
Is calculated (736 in FIG. 22), and the slip ratio deviation Eso is calculated.
The integral value IEsoi of i is calculated, and the slip ratio deviation Eso
The value proportional to the i + integral value IEsoi is increased and used as one parameter Y for pressure reduction determination, and the value proportional to the acceleration deviation EDi is increased and another parameter X for pressure reduction determination is used (737 to 745 in FIG. 23). . Then, in step 746 of FIG. 23, the increase / decrease mode is determined.

By setting such wheel brake pressure,
For example, for the reference lateral acceleration gye, the detected lateral acceleration gy
If c is relatively low, the control sum is increased (the actual output produced by this increase is performed in "output control" 800 (FIG. 5) described later). As a result, if the detected lateral acceleration gyc does not reach the reference lateral acceleration gye, braking is applied to the vehicle body, and the braking reduces the vehicle body speed Vso, thereby causing the reference lateral acceleration gye to turn. When the vehicle speed is high, when the friction coefficient μ is low, or when tire wear is advanced, insufficient turning is likely to occur with respect to the steering amount θf.
This turning (insufficient) appears in the lateral acceleration gyc detected by the vehicle body lateral acceleration detecting means (GY), and is introduced into the wheel brake pressure increase determination, in which case the wheel brake pressure is increased. Therefore, the stability and reliability of the understeer compensation control are improved. Specifically, the detected lateral acceleration gyc is compared with the reference lateral acceleration gyea by correcting the reference lateral acceleration gye corresponding to the turning delay with respect to turning, so that understeer compensation control including an optimal delay corresponding to the steering speed is performed. As a result, its stability and reliability are further improved.

As shown in steps 728 to 734 of FIG. 21, similarly to the ABS control, the target slip ratio for the present understeer compensation control (B-STR-US control) is calculated and added to the target slip ratio for the ABS control. Since the wheel brake is determined to increase or decrease as shown in steps 736 in FIG. 22 to step 746 in FIG. 23 in accordance with the added value, the brake pressure control output does not conflict with each other.
The ABS control and the present understeer compensation control match.

After setting the pressure increase, the pressure reduction, etc. as described above, the computer 11 changes the determined area from the pressure reduction to the pressure increase (pulse pressure increase, rapid increase) corresponding to the area determined this time and the area determined last time. Pressure) or from pressure increase to pressure reduction (pulse pressure reduction, rapid pressure reduction), brake pressure control mode adjustment for smoothing the rise / fall of the wheel brake pressure is performed (747). For example, when changing from a sudden decrease in the ABS time to a pulse pressure increase, the pressure increase duty (pressure increase time / (hold time)) of the pulse pressure increase from 0 to a predetermined value set in the pulse pressure increase region for a predetermined time after that. Start up gradually (set the boost pressure duty to make it).

Next, the computer 11 executes, for example, the B-ST
Start of R control (STRoF = 0 → STRoF = 1 or S
When TRuF = 0 → STRuF = 1), an initial pressurization for increasing the braking force responsiveness is performed (748). Further, for example, the end of the B-STR control (ST
RoF = 1 → STRoF = 0 or STRuF = 1 → ST
When RuF = 0), brake pressure control is performed to match the control oil pressure immediately before the control wheel with the master cylinder oil pressure, the pressure is adjusted, and the control ends.

(5) "ABS control" 400: FIG. 25 Referring to FIG. In the “ABS control” 400, it is checked whether the combination of the sideslip angular velocity Dβ and the vehicle body speed Vso is in the start region 1 or whether the combination of the sideslip angle β and the vehicle body speed Vso is in the start region 2 (304A, 30
4B). The start areas 1 and 2 are referred to in the case of “B-STR-OS control” 700A (304 and 3 in FIG. 9).
05), it is determined that there is a tendency to spin when the vehicle is in the start range 1 or 2, and the target slip ratio SφABSi (i = RL, RR) of the rear wheel at the time of the ABS control is set to SφABSR.
If neither of the start ranges 1 and 2 is present, the target slip ratio SφABSi is set to SφABS (705AA). Here, SφABSR and SφABS are constants, and SφABS is a normal value, but SφABSR is
This is a value at the time of a spin tendency in which SφABSR <SφABS. The target slip ratio SφABSi (i = FR, FL) of the front wheel target slip ratio is a fixed value.

According to the above processing, when the vehicle body spin tendency is detected during turning, the target slip ratio (Soi) of the rear left and right wheels (RR, RL) is set lower than when the vehicle body spin tendency is not detected. (705AA). As a result, the lateral force of the rear wheel is secured,
The vehicle stability is improved, and the tendency of the vehicle to spin during turning braking is suppressed.

The B-STR control (vehicle stability control for suppressing oversteer and understeer) is performed in parallel with the ABS control (when each is determined to be necessary). During the B-STR control, when the brake control is changed to the ABS control state, the control for suppressing the spin tendency during turning of the ABS control is complementarily emphasized,
High vehicle stability is obtained.

(6) “Output control” 800 “ABS control” 400, “2-BDC control” 500,
"TRC control" 600 and "B-STR control" 700
An output (energization / non-energization of the solenoid valve) that realizes the brake pressure control mode determined in each “slip ratio servo calculation” (FIG. 3) is generated and output to the solenoid valve drivers 19b to 19o.

In this embodiment, the brake fluid used for the initial pressurization of the wheel cylinder is sucked from the reservoir 4, but may be sucked from the master cylinder 2.

[0113]

As described above, according to the wheel brake pressure control device of the present invention, the initial pressurization to the wheel cylinder can be performed accurately and with high response with a simple system configuration. The system can be reduced in size and weight, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of one embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of an electronic control device that controls energization of a solenoid valve or the like of a wheel brake pressure system illustrated in FIG.

FIG. 3 is a block diagram showing control functions related to wheel brake pressure control of a microcomputer 11 shown in FIG. 2 in block divisions.

4 is a flowchart showing an outline of the contents of wheel brake pressure control of the microcomputer 11 shown in FIG.

FIG. 5 is a flowchart showing an outline of wheel brake pressure control of the microcomputer 11 shown in FIG. 2, mainly focusing on a braking operation;

FIG. 6 shows “wheel speed calculation & wheel acceleration calculation” shown in FIG.
4 is a flowchart showing the contents of the H.100.

FIG. 7 is a flowchart showing the content of “vehicle state quantity estimation” 200 shown in FIG. 5;

FIG. 8 shows “control mode start / end processing” 3 shown in FIG.
It is a flowchart which shows the content of 00.

FIG. 9 is a flowchart showing the contents of “B-STR-OS start / end determination” 300D shown in FIG. 8;

FIG. 10 is a flowchart showing the content of “B-STR-US start / end determination” 300E shown in FIG. 8;

11 is a flowchart showing the contents of “B-STR control” 700 shown in FIG.

FIG. 12 shows “B-STR-OS control” 7 shown in FIG.
It is a flowchart which shows a part of content of 00A.

FIG. 13 shows a first example of “control wheel selection” 705 shown in FIG.
It is a flowchart which shows a modification.

FIG. 14 shows a second example of “control wheel selection” 705 shown in FIG.
It is a flowchart which shows a modification.

FIG. 15 shows a third example of “selection of control wheel” 705 shown in FIG.
It is a flowchart which shows a modification.

FIG. 16 shows “B-STR-OS control” 7 shown in FIG.
It is a flowchart which shows a part of content of 00A.

FIG. 17 shows “B-STR-OS control” shown in FIG.
It is a flowchart which shows a part of content of 00A.

FIG. 18 shows “B-STR-OS control” 7 shown in FIG.
It is a flowchart which shows a part of content of 00A.

FIG. 19 is a block diagram showing an outline of functions of a 4WS controller 70 shown in FIG. 2;

FIG. 20 shows “B-STR-US control” shown in FIG.
It is a flowchart which shows the content of 00B.

FIG. 21 “Slip ratio servo calculation” 7 shown in FIG.
It is a flowchart which shows a part of content of 00D.

FIG. 22: “Slip ratio servo calculation” 7 shown in FIG.
It is a flowchart which shows a part of content of 00D.

FIG. 23: “Slip ratio servo calculation” 7 shown in FIG.
It is a flowchart which shows a part of content of 00D.

FIG. 24 is a diagram showing a gain G shown in step 743 of FIG.
6 is a graph showing a change tendency of soi with respect to a change in the sideslip angle β.

FIG. 25 is a flowchart showing a part of the contents of step 400 shown in FIG. 5;

FIG. 26: Step “hydraulic standby” shown in FIG. 11
It is a flowchart which shows the content of 700C.

FIG. 27 is a characteristic diagram showing a relationship between a slip ratio between a wheel and a road surface, a friction coefficient, and a wheel brake pressure.

FIG. 28 is a diagram showing a relationship between a pressure increase time and a wheel cylinder pressure.

[Explanation of symbols]

2: Brake master cylinder 3: Brake pedal 4: Brake fluid reservoir 5: Vacuum booster 6: Proportional control valve 10: Electronic control unit 11: Microcomputer 12: Input interface 13: Output interface 14: CP
U 15: ROM 16: RA
M 17: Timer 18a-1
8m: signal processing circuit 19a to 19o: motor driver and solenoid driver 21: pump 24: electric motor 31, 33, 35, 37: solenoid valve for increasing pressure 32, 34, 36, 38: solenoid valve for reducing pressure 41 to 44: wheels Speed sensor 45: stop switch YA: yaw rate sensor θF: front wheel steering angle sensor θR: rear wheel steering angle sensor GX: longitudinal acceleration sensor GY: lateral acceleration sensor 51-5
4: Wheel brake 61, 62, 63, 64: Solenoid switching valve 65, 6
6: solenoid on-off valve 70: small capacity reservoir 80, 8
1: Relief valve 82, 83: Push-in valve 84, 8
7: Check valve 139 to 142: Check valve REG: Regulator MC: Master cylinder sensor

Continuation of front page (56) References JP-A-7-81540 (JP, A) JP-A-8-175364 (JP, A) JP-A-6-183324 (JP, A) JP-A-5-330417 (JP) , A) Special Table Hei 5-502423 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60T 8/58, 8/26

Claims (4)

(57) [Claims] A master cylinder for generating a hydraulic pressure according to claim 1] in response to depression of the brake operating member of the vehicle, a hydraulic pump for generating hydraulic pressure regardless of the operation of the brake operating member,
A reservoir provided with a brake hydraulic fluid and communicating with the atmosphere, a wheel cylinder mounted on the wheel to apply a brake hydraulic pressure to the wheel, and a suction port of the hydraulic pump is shut off from the reservoir.
Between the inoperative position and the suction port of the hydraulic pump.
An on-off valve that switches to an operating position that communicates with a reservoir, a pressure-increasing position that connects at least the wheel cylinder to a discharge port of the hydraulic pump , and a wheel cylinder that is connected to the reservoir.
A modulator valve that switches to a decompression position to be connected ;
A vehicle behavior detecting means for detecting the behavior of the vehicle, and when the vehicle behavior detecting means detects that the behavior of the vehicle is in a predetermined first vehicle behavior area , the on / off valve is switched to an operating position , and the hydraulic pressure A wheel brake pressure control device comprising: a brake pressure control means having an automatic pressurization mode for operating a pump to introduce a hydraulic pressure to the wheel cylinder. The wheel brake pressure control device further comprises: A hydraulic pressure estimating means for estimating a pressure value, and an initial pressurizing time is set to be longer if the hydraulic pressure value of the wheel cylinder estimated by the hydraulic pressure estimating means is lower, and to be shorter if the hydraulic pressure value of the wheel cylinder is higher. An initial pressurization time setting unit, wherein the brake pressure control unit is configured to determine that the vehicle behavior detection unit is configured to determine that the vehicle behavior is wider than the first vehicle behavior area.
When it is detected that the vehicle is in the vehicle behavior area , the on- off valve is turned on.
An initial pressurizing mode for switching to an operating position , operating the hydraulic pump and introducing hydraulic pressure to the wheel cylinder for the initial pressurizing time set by the initial pressurizing time setting means. Characteristic wheel brake pressure control device. 2. The wheel brake pressure control device further includes an electric motor that drives the hydraulic pump, and a regulator that is controlled by the brake pressure control and that adjusts a power supply voltage to the electric motor. The brake pressure control means controls the regulator means to adjust a power supply voltage to the electric motor higher for a predetermined time after the start of the initial pressurization mode than in the automatic pressurization mode. A wheel brake pressure control device that satisfies claim 1. 3. The modulator valve further includes a wheel cylinder connected to a discharge port of the hydraulic pump and the reservoir.
Select the holding position of blocking the said initial pressure mode, the modulator valve and the pressure increasing position, the opening and closing
There is a duty holding mode in which a pressure increasing sub-mode in which the valve is in the non-operating position and a holding sub-mode in which the modulator valve is in the holding position and the on- off valve is in the operating position are alternately repeated. A wheel brake pressure control device that satisfies claim 1. 4. The vehicle behavior detecting means includes a slip rate detecting means for detecting a slip rate of a wheel, and the brake pressure control means determines that the slip rate detecting means determines that a slip rate of a wheel during the initial pressurizing mode. 4. The wheel brake pressure control device according to claim 3, wherein when it is detected that the pressure exceeds a predetermined value, the hydraulic pressure of the wheel cylinder is reduced by a predetermined amount, and then the mode shifts to the duty holding mode.