JP3446048B2 - Wheel brake pressure control device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, in order to ensure the running stability and steering performance of a vehicle body, prevents the wheel rotation from being completely stopped (wheel lock) during braking by a driver (driver). Regarding the anti-skid control (ABS control) in which the brake pressure is reduced, then the pressure is increased so that the braking distance is shortened as much as possible, and then the pressure is increased and decreased as necessary, in particular, the intention is to be limited to this. However, depending on the driving state or running state of the vehicle such as steering, acceleration / deceleration, road slope, unevenness, etc., the front / rear and left / right wheel brakes can be used to ensure running stability and steerability even if they exist. The present invention relates to a wheel brake pressure control device suitable for combined use with braking force distribution control for calculating braking force distribution and individually increasing or decreasing each wheel brake pressure according to the distribution.

[0002]

2. Description of the Related Art Generally, a brake master cylinder applies a brake pressure (first pressure) corresponding to the pushing pressure of a brake pedal operated by a driver. The moving speed (reference speed) of the vehicle body is estimated and calculated from the rotational speeds of a plurality of wheels, and the slip rate of the wheel or the friction coefficient μ of the road surface is calculated or estimated from the reference speed and the rotational speed of the wheel, and the vehicle body moves. Despite this, the wheel brake pressure is reduced so as to prevent the wheel rotation from completely stopping (wheel lock), and then the braking distance is increased so that the braking distance is shortened as much as possible. Wheel brakes for anti-skid control (ABS control) that repeatedly decreases and increases pressure.
A pressure increasing / decreasing valve for reducing and increasing the pressure and a pressure source consisting of a fluid pump and an electric motor for driving the pressure increasing / decreasing valve that gives a pressure (second pressure) higher than the first pressure to the first pressure line. When the electronic control unit for executing ABS control determines that the wheel brake pressure needs to be changed (automatic intervention), the second pressure is applied from the pressure source to the pressure increasing / decreasing valve, and the pressure increasing / decreasing valve is used. The wheel brake is selectively switched between a low pressure (drain pressure) and a second pressure. The low-pressure supply reduces the wheel brake pressure, and the second pressure supply increases the wheel brake pressure. 1 of this kind of wheel brake pressure control
One is disclosed in Japanese Patent Laid-Open No. 2-38175.

Recently, not only the wheel brake pressure is controlled by focusing on the slip ratio and the braking distance of the wheel when the vehicle is being braked, but also according to the driving and running conditions of the vehicle and the load distribution on the vehicle. The electronic control unit calculates the braking force distribution of the front, rear, left, and right wheel brakes to ensure the directional stability of the vehicle during braking, and the wheel brakes are used by using the pressure increasing / decreasing valve so as to satisfy this distribution. Braking force distribution control for adjusting pressure has been proposed. The present inventors have, for example, disclosed in Japanese Unexamined Patent Publication No.
No. 85327, Japanese Patent Application Laid-Open No. 5-85340, and Japanese Patent Application Laid-Open No. 5-85336.

According to Japanese Patent Publication No. 3-500868 (Patent Application Publication Number), the side slip angle of a vehicle is detected, and when there is side slip, the front wheel brake is intensified to cause high slip (for example, wheel lock) of the front wheel. A proposal to do so is disclosed.
Further, in JP-A-5-221300, the lateral slip angular velocity Dβ is calculated by Dβ = Gy / Vso−γ Gy: lateral acceleration, Vso: estimated vehicle body velocity γ: yaw rate, and the lateral slip angular velocity Dβ is calculated. If the absolute value is equal to or greater than a predetermined value, the brake pressure on the rear left wheel is increased when the value is positive, and the brake pressure on the right rear wheel is increased when the value is negative depending on the polarity of the angular velocity Dβ. -Brake pressure control for suppressing ing is disclosed. Also, the sideslip angular velocity Dβ is integrated to calculate the sideslip angle β, and the sideslip angle β is set as a parameter.
There is also a proposal to control an excessive yaw as a computer.
The side slip angle β is an angle formed by the advancing direction of the vehicle body with respect to the longitudinal axis X of the vehicle body, but its value is usually small, and the above side slip angular velocity calculation formula Dβ = Gy / Vso−γ is β≈Vy
/ Vx and further approximation with Vx≈Vso, assuming β≈Vy / Vso → Dβ≈DVy / Vso, the equation of lateral slip motion Gy = DVy + Vso · γ → DVy / Vso = Gy
From / Vso-γ and Dβ≈DVy / Vso, Dβ≈Gy / Vso−
This is an approximate calculation with γ. Note that Gy is lateral acceleration, Vy is lateral velocity, Vx is longitudinal X-direction velocity, and DVy is lateral acceleration.

Initially, the ABS control was only for the rear two wheels, but recently, with the intention of improving the ABS control effect,
The mainstream is to control the brake pressure of each of the four wheel brakes. Also in the four-wheel control, in consideration of the vehicle stability, the rear wheels are normally subjected to the select-low control, and substantially operate as three channels. However, if the select low control is always performed, the braking performance may be deteriorated when the vehicle turns. Therefore, the ABS control device disclosed in Japanese Patent Laid-Open No. 63-49577 switches the wheel brake pressure control for all four wheels from select low control to select high control when the lateral acceleration is large. However, in this case, the control is focused on braking performance, and vehicle stability is not particularly considered.

[0006]

Normally, the ABS control keeps braking performance and steering performance by preventing the wheels from being locked, and the known yaw control control considers a part of the vehicle motion. In the limit state, for example, the vehicle stability is not sufficiently ensured when the limit turning braking is performed.

It is an object of the present invention to normally secure a high braking performance and, if necessary, to maintain vehicle stability.

[0008]

According to the present invention, the vehicle body speed is calculated from the wheel rotation speed detecting means (41 to 44, 11) and the wheel rotation speed (Vwi).
(Vso) for estimating and calculating vehicle speed detecting means (11), means for estimating and calculating the wheel slip rate based on wheel rotation speed (Vwi) and vehicle speed (Vso), and wheel blur when the wheel slip rate is high. -Information processing means for determining the pressure reduction, and
In a wheel brake pressure control device provided with a brake pressure operating means (11, 19b to 19m, 31 to 64) for reducing the wheel brake pressure according to the determination, a means (11) for detecting a vehicle body spin tendency;
Side slip angle detection to estimate (207) vehicle side slip angle β
Means (11); Estimate and calculate (203) the vehicle side slip angular velocity Dβ
Side slip angular velocity detecting means (11); When the vehicle body spin tendency is detected, the target slip ratios (Soi) of the rear left and right wheels (RR, RL) are set lower than when the vehicle body spin tendency is not detected (70
5AA) for side slip angle β and side slip angular velocity Dβ
Then, the larger the respective values, the lower the target slip ratio is set (709
A～709d) to the target slip ratio setting means (11); and,
Information processing means (11) for determining increase or decrease in wheel brake pressure for matching the wheel slip ratio to the target slip ratio;
It is characterized by including.

For the sake of easy understanding, reference numerals are given in parentheses to corresponding elements or corresponding matters of the embodiment shown in the drawings for reference.

[0010]

[Operation] Normal ABS when the vehicle body spin tendency is not detected
As a control, when the wheel slip ratio is higher than the target slip ratio, the wheel brake pressure is reduced.

In response to the detection of the vehicle body spin tendency during turning, the target slip ratio setting means (11) causes the rear left and right wheels (RR,
The target slip ratio (Soi) of (RL) is set lower (705AA) than when the vehicle body spin tendency is not detected. This ensures lateral forces on the rear left and right wheels (RR, RL) and improves vehicle stability.
Therefore, the tendency of the vehicle body spin during the turning braking is suppressed.

In an embodiment described later, B-STR control (vehicle stability control for suppressing oversteer and understeer) is performed concurrently with ABS control. When the ABS control state is brought about by the brake operation during the B-STR control, the control for suppressing the spin tendency during the applied braking of the ABS control complementarily cooperates with each other, resulting in high vehicle stability. Sex is obtained.

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

[0014]

1 shows a wheel brake pressure system according to an embodiment of the present invention, and FIG. 2 shows a wheel brake 51 to which various electromagnetic valves and sensors of the wheel brake pressure system are connected. 5 shows an outline of an electric system for controlling each pressure of ~ 54.

Referring first to FIG. 1, the brake pedal 3
When the driver (driver) steps on, the single-type master cylinder 2 generates front wheel brake fluid pressure corresponding to the stepping pressure, and the hydro booster 5 rear wheel brake proportional to the stepping pressure.
Generates fluid pressure for g. In the state shown in FIG. 1, the fluid pressure for the front wheel brake is applied to the wheel brake 51 of the front right wheel FR and the wheel brake 52 of the front left wheel FL through the electromagnetic switching valves 61 and 62. The fluid pressure for the rear brake is
The rear right wheel R via the electromagnetic switching valve 63 and the electromagnetic valve 35.
It is added to the wheel brake 53 of the R wheel and to the wheel brake 54 of the rear left wheel RL via the solenoid valve 37.

The pump 21 is driven by an electric motor 24 to suck the brake liquid of the reservoir 4 and check valve 25.
Through the accumulator 22. Accumulation
The high pressure of the motor 22 is supplied to the hydro booster 5 and the electromagnetic switching valve 64. The pressure of the brake fluid in the accumulator 22 is detected by the pressure sensor 46. When the pressure of the accumulator 22 falls below the lower limit value, the low pressure switch 47 is closed. A relief valve 23 is interposed between the reservoir 4 and the accumulator 22.
When the pressure of 2 reaches the upper limit value, the relief valve 23 discharges the brake liquid of the accumulator 22 to the reservoir 4 until the pressure becomes less than the upper limit value. The electronic control unit 10 shown in FIG. 2 and described later monitors the closing (pressure exceeds the lower limit value) / opening (pressure is below the lower limit value) of the low pressure switch 47 and reads the pressure detected by the pressure sensor 46. , Low voltage switch 4
When 7 is open (pressure is below the lower limit), electric motor 24
When the pressure detected by the pressure sensor 46 reaches a set value, the electric motor 24 is stopped to keep the pressure of the accumulator 22 at a substantially constant pressure (range between the lower limit value and the set value). .

The pressure of the accumulator 22 is hydro-blow.
Applied to the star 5, the hydro booster 5 applies the pressure to
The pressure is adjusted to a pressure proportional to the pushing force of the brake pedal 3 and applied to the electromagnetic switching valves 63 and 64. This is the booster pressure, which is about 120% of the pressure output from the brake master cylinder 2.

An accumulator pressure and a booster pressure are applied to the electromagnetic switching valve 64. The electromagnetic switching valve 64 increases the booster pressure when the electric coil is not energized by increasing the booster pressure of the front right wheel brake 51 and the front left wheel brake 52, as shown in FIG. It is applied to the input port of the pressure solenoid valve 33, but when the electric coil is energized, the accumulator pressure is applied to the input ports of the pressure increase solenoid valves 31 and 33 instead of the booster pressure. The booster pressure and the output pressure of the proportional control valve 6 are applied to the electromagnetic switching valve 63. The electromagnetic switching valve 63 applies a booster pressure to the electromagnetic valves 35 and 37 as shown in FIG. 1 when the electric coil is not energized, but when the electric coil is energized, it is replaced by the booster pressure. The output pressure of the proportional control valve 6 is applied to the solenoid valves 35 and 37.

The solenoid valves 31, 33, 35 and 37 are energized to close them (valve closed), and the solenoid valves 32, 34, 36 are closed.
And 38 to energize them and open them (valve open), the front right wheel brake 51, the front left wheel brake 52, respectively.
The pressure of the rear right wheel brake 53 and the rear left wheel brake 54 escapes to the reservoir 4 through the solenoid valves 32, 34, 36 and 38.

In the brake pressure system shown in FIG. 1, a brake pressure transmission system that applies only the output pressure of the brake master cylinder 2 to the wheel brakes, a brake pressure transmission system during anti-skid control, and traction. Tables 1 and 2 show the elements constituting each of the brake pressure transmission system under control and the brake pressure transmission system under braking force distribution control for each wheel brake. In these tables, the elements constituting each transmission system are extracted and displayed in the direction toward the brake pressure source with the wheel brake as the starting point. Further, in Tables 1 and 2 and 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 is roughly classified into "B-STR control" for all-wheel brakes and "2-BDC control" for two rear-wheel brakes. "B-STR control" for wheel brakes
"B-STR-OS" control for suppressing basteer and "B-STR-US" for suppressing under-steer
It is divided into two, control.

[0021]

[Table 1]

[0022]

[Table 2]

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

Referring to FIG. The main body of the electronic control unit 10 is a microcomputer 11, and the main elements of this microcomputer 11 are a CPU 14, a ROM 15, and an RA.
M16 and timer 17. The electronic control unit 10 is further provided with signal processing circuits 18a to 18m for energizing (energizing) the sensor to generate a detection signal and an input of the detection signal to the micro computer 11, and the micro computer 11
An electric circuit, that is, input / output interfaces 12, 13 for giving the control signals of the above to the drivers 19a to 19m,
Motor driver and solenoid driver 19a-19
There is m.

Front right, front left, rear right and rear left wheels 51-
The wheel speed sensors 41 to 44 detect the respective rotation speeds of 54, and the signal processing circuits 18a to 18d generate electric signals representing the wheel speeds (wheel speed signals) and apply them to the input interface 12. The stop switch 45, which is closed while the brake pedal 3 is being depressed, is opened (pedal 3
The signal processing circuit 18e generates an electric signal representing "no depression: off" / closed (pedal 3 depression: on) and gives it to the input interface 12. The pressure sensor 46 detects the hydraulic pressure of the accumulator 22, and the signal processing circuit 18
f generates an electric signal (pressure signal) representing the detected pressure and supplies it to the input interface 12. Accumulator 2
Low pressure switch 47 that opens when the hydraulic pressure of 2 is below the lower limit
Closed (pressure below the lower limit: ON) / Open (below the lower limit:
An electric signal representing "OFF" is generated by the signal processing circuit 18g and given to the input interface 12.

A yaw rate sensor YA is provided for the yaw rate of the vehicle body.
Is detected by the signal processing circuit 18i, and the signal processing circuit 18i detects the yaw rate (actual yaw rate).
Rate) An electrical signal representative of .gamma. Is generated and provided 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 input to the input interface.
Give to face 12. The steering angle of the rear wheels is the rear wheel steering angle sensor θ
The signal processing circuit 18k detects the signal R and generates an electric signal representing the rear wheel steering angle θr and supplies it to the input interface 12. An acceleration sensor (GX sensor) detects the longitudinal acceleration gx of the vehicle body, and a signal processing circuit 18l generates an electric signal representing the longitudinal acceleration and applies it to the input interface 12. The lateral acceleration gy of the vehicle body is measured by an acceleration sensor (GY sensor).
Is detected by the signal processing circuit 18m, and the signal processing circuit 18m generates an electric signal representing the lateral acceleration and applies it to the input interface 12.

3 and 4 show the outline of the processing functions of the microcomputer 11 shown in FIG. FIG. 3 shows the processing functions in block form in hardware form, and FIG. 4 shows the same block form in flow chart form. Figure 5
The flowchart of the entire process is shown in FIG.

Referring to FIG. 5, the operating voltage is applied to the electronic control unit 10 after the engine on the vehicle is started and the electric system on the vehicle is turned on to stabilize the voltage of the system (step of FIG. 3). 1; hereinafter, the word “step” is omitted in parentheses, and only the step No. and number are described).
When the operating voltage is applied, the microcomputer 11 sets the internal register, the input / output port and the internal timer to the initial state, and the input / output interfaces 12 and 13 are connected to the input reading connection and the output signal during standby. Set to level (2). Then, the electric motor 2 is attached to the motor driver 19a.
4 (pump 21) is instructed to drive the accumulator 2
The hydraulic pressure control of No. 2 is started, and in parallel with this hydraulic pressure control, a timer Δt for determining the processing cycle is started at a substantially predetermined cycle (3), and "sensor reading" (4). To the "output control" (800), that is, the wheel brake pressure control is repeatedly executed substantially in a cycle of Δt. In the hydraulic pressure control of the accumulator, when the pressure detected by the pressure sensor 46 reaches the upper limit value, the electric motor 24 (pump 21) is stopped and the low pressure switch 47 is opened (the hydraulic pressure is below the lower limit value). Then, the electric motor 24 (pump 21) is driven.

"Sensor reading" in the processing from "sensor reading" (4) to "output control" (800), that is, wheel brake pressure control, which is repeated substantially in Δt cycles.
In (4), first, all the information of the input means (sensor, switch, etc.) connected to the input interface 12 is read. Then, the ABS control, the 2-BDC control (braking force distribution control for the brakes of the rear two wheels), the TRC control and the B-STR control (braking force distribution control for the four wheels) are used. Data is adjusted by "wheel speed calculation & wheel acceleration calculation" (100) and "vehicle state amount estimation" (200), and based on the adjusted data, "control mode start / end processing" (300) ), The start of the various controls described above,
Whether or not continuation and termination are necessary 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 (open / close and timing of solenoid valves) for each of these controls, and" output control "(800).
Then, the wheel brake pressure operation output is adjusted and set in the output port 13 based on the priority order of the various controls described above. That is, the solenoid valve is operated.

"Wheel speed calculation & wheel acceleration calculation" (10
0) The contents of each of the following processes will be described below, and the main ones of the reference information in this embodiment will be listed as follows: Information Information Source Actual Yaw Rate γ Yokele -Detected value by the sensor YA Wheel speed Vwi, i = FR, FL, RR, RL: Calculated from the detected value of the wheel speed sensors 41 to 44 (Wheel speed VwFR Calculated from the detected value of the wheel speed sensor 41 Wheel speed VwFL Wheel speed sensor Calculated from the detected value of 42. Wheel 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 by lateral acceleration sensor GY Value Front wheel steering angle θf Detection value by steering angle sensor θF Rear wheel steering angle θr Detection value by steering angle sensor θR Wheel braking Yes / No Stop switch 45 on / off Wheel acceleration DVwi, i = FR, FL, RR, RL: Wheel speed Calculated from the detected values of the sensors 41 to 44 (Wheel acceleration DVwFR Calculated from the detected value of the 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 Wheel Calculated from the value detected by the speed sensor 44) Calculated based on estimated vehicle speeds Vso Vwi and DVwi Calculated based on vehicle accelerations DVso Vwi and DVwi Wheel slip rates Si, i = FR, FL, RR, RL: Based on Vwi and DVwi Calculated based on wheel slip rate SFR VwFR and VsoFR Calculated based on wheel slip rate SFL VwFL and VsoFL Wheel slip rate SRR Calculated based on VwRR and VsoRR Wheel slip rate SRL Calculated based on VwRL and VsoRL Calculated based on the friction coefficient μ DVso and gy Calculated based on the vehicle side slip angle β γ, gyc, Vso Ri angular velocity Dβ γ, gyc, calculated on the basis of the Vso.

(1) "Wheel speed calculation & wheel acceleration calculation"
(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 for wheel brakes FR, FL, RR, RL, but 2-BDC control and TRC control are Since two wheels are subject to control, in 2-BDC control and TRC control, i indicates data for each of the RR and RL wheel brakes.)
Clear i. The counter Pi is an electric pulse whose frequency is proportional to the rotational speed (peripheral speed) of each of the front right, front left, rear right, and rear left wheels 51 to 54 generated by the wheel speed sensors 41 to 44. In response, it counts the number of incoming electric pulses by interrupt processing.
For example, when the sensor 41 generates one pulse, the microcomputer 11 causes the counter Pi, i =
Since the contents of FR are incremented by one, register P
The content of i, i = FR represents the number of pulses (value proportional to the wheel speed) generated by the sensor 41 during Δt. Then, the correction coefficient Ksi corresponding to the tire diameter of the wheel is calculated (determined) (101). Then, the LSB of the wheel speed (Least
Each wheel speed Vwi is calculated using the correction coefficient (constant) for setting Significant Bit) (102). The calculation formula is shown in the block of step 102 in FIG.

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

Next, the vehicle body speed Vsoi of each wheel portion (each wheel portion estimated vehicle body speed) is calculated (106). Here, the current value Vwi (n) of the wheel speed, the previously calculated wheel body speed Vsoi
From (n), the deceleration amount αdn · Δ during Δt at the predetermined deceleration
A value obtained by subtracting t from Vsoi (n) −αdn · Δt, and the wheel body speed Vsoi (n) calculated last time, at a predetermined acceleration.
Value Vsoi (n) + αup obtained by adding the acceleration amount αup · Δt during t
The intermediate value Vsoi of the three of Δt is calculated, and this is written in the register Vsoi as the wheel body speed Vsoi. next,
The maximum value of the vehicle body speed Vsoi of each wheel (four wheels in total) is shown as the vehicle speed of the entire vehicle (commonly known as vehicle speed) Vso
Is written in the register Vso (107).

Next, when the vehicle is turning, each wheel of the wheel body speed Vsoi corresponding to the deviation of the direction of the wheel from the traveling direction of the vehicle with respect to the speed of the wheel body in the vehicle traveling direction. The deviation Δi of the vehicle body speed Vsoi is calculated as the lateral acceleration gy.
The value NVsoi is calculated corresponding to the yaw rate γ, and the vehicle body speed Vsoi of each wheel is corrected by that amount to obtain the corrected value NVsoi.
= Vsoi-Δi is written in the register NVsoi as the normalized wheel body speed (108). Next, the normalized wheel body acceleration DNVsoi is calculated from the normalized wheel body speed NVsoi (n) calculated this time and the normalized wheel body speed NVsoi (n-1) calculated last time (before Δt) ( (4 wheels in total, 4 each)
The one indicating the maximum value is written in the register DVso as the vehicle body acceleration (commonly called vehicle body acceleration) DVso of the entire vehicle (1
09).

(2) "Vehicle state quantity estimation" (200): FIG. 7 This content is shown in FIG. In this process, first, the 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 calculated by the register gyc.
Write in (201). Next, the friction coefficient μ of the road surface is estimated and calculated and written in the register μ (202). The arithmetic expression is shown in the block of step 202. Next, the lateral slip angular velocity Dβ
And the sideslip angle β were calculated as follows, and the calculated D
Write β and β in registers Dβ and β (203 to 20)
4).

Dβ = (gyc / Vso) −γ (1) β = ∫Dβ (3) (3) “Control mode start / end processing” (300): FIG. 8 It shows in FIG. In this process, first of all, the "ABS start / end determination" 300A is performed for the four wheels FR, FL, RR, R.
L For each of the wheel brakes 51 to 54, the brake pressure control for preventing the wheel lock during the wheel brake, that is, the ABS control is not started (ABSFi =
0; ABSF = 0), it is checked whether it is necessary to start it (whether the start condition is satisfied), and if ABS control is necessary even for a one-wheel brake, the register ABS
Write 1 to F. When the ABS control is 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 performed. If it is determined that it is not necessary, 0 is written to the register ABSFi, and if it is determined that ABS control of all-wheel brakes is not required, the register AB is registered.
Write 0 to SF (synonymous with clearing register ABSF).

Next, "2-BDC start / end determination" 30
At 0B, the braking force distribution control for the two-wheel brakes 53, 54 of the two wheels RR, RL, that is, 2-BDC control is not started (BDCFi = 0; BDCF = 0), the wheel brakes 53, 54 are not started. For each of the above, it is checked whether it is necessary to start it (whether the start condition is satisfied), and if it is determined that 2-BDC control is required, the register BD
Write 1 to CFi and BDCF. Each wheel brake 53,
When 2-BDC control is started for each of 54 (BDCFi = 1), it is checked whether it is necessary to end it (whether an end condition is satisfied), and 2-BDC control of each wheel brake is performed. If it is determined to be unnecessary, register B
When 0 is written in DCFi and it is determined that 2-BDC control is not required for both two-wheel brakes, 0 is written in register BDCF (synonymous with clearing register BDCF).

Next, "TRC start / end determination" 300C
Thus, the wheel brake pressure control, that is, the TRC control for reducing the acceleration slip is not started for each of the two-wheel RR and RL wheel brakes 53 to 54 (TRCF).
When i = 0), it is checked whether it is necessary to start it (whether the start condition is satisfied), and if it is determined that TRC control is required for each wheel brake, 1 is set in the register TRCFi.
Is written into the register TRCF when it is determined that TRC control is required even for a one-wheel brake. When the TRC control is started (TRCFi = 1; TRCF = 1), is it necessary to end it (whether the end condition is satisfied)
If it is determined that TRC control is not required for each wheel brake, 0 is written to the register TRCFi and all wheels are braked.
If it is determined that TRC control is not necessary, the register TRCF
Write 0 to (synonymous with clearing register TRCF).

Next, "B-STR-OS start / end determination" 300D is executed. This content is shown in FIG. First, here is a four-wheel brake to suppress oversteering.
Whether or not the braking force distribution control, that is, the B-STR-OS control is started (STRoF = 1) (STRoF = 0)
Is checked (301), and if not started, it is in the oversteer direction (Dβ · γ <0: lateral slip 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 to be in the oversteer direction, that is, if Dβ · γ <0 & gyc · γ> 0, the vehicle body speed Vs
It is checked whether the combination of o and the lateral slip angular velocity Dβ is in the start area 1 (shown in the block of step 304 in FIG. 9). That is, the vehicle body speed Vso is high (Vso ≧ V ₁ ~
V ₂ ) and the lateral slip angular velocity Dβ is large (absolute value of Dβ ≧
α _{1 to} α ₂ ) (whether it tends to increase oversteer)
Is checked (304). If so, B-STR-
It is determined that OS control is required, and 1 is written in the register STRoF (306). When it is not judged that the oversteer is increasing, it is checked whether the oversteer is already excessive (305). That is, the vehicle body speed Vso is high (V
so ≧ V _{3 to} V ₄ ) and the side slip angle β is large (absolute value of β ≧
α _{3 to} α ₄ ) Start area 2 (shown in step 305 of FIG. 9)
Check if there is, and if so, B-STR-O
It is determined that S control is required, and 1 is written in the register STRoF (306).

When the B-STR-OS control has already been started (STRoF = 1), the combination of the vehicle body speed Vso and the lateral slip angular velocity Dβ is set in the end region 1 (step 3 in FIG. 9).
(Indicated 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)} . If so, the vehicle speed Vso
Is low (Vso <V _{6 to} V ₇ ) or the sideslip angle β is small (absolute value of β <α _{6 to} α ₇ ), the end region 2 (step 3 in FIG. 9).
(Shown in 08) (308), and if so, it is determined that B-STR-OS control is not necessary, and 0 is written in the register STRoF (309).

Next, "B-STR-US start / end determination" 300E is executed. This content is shown in FIG. Here, first, the lateral acceleration gye that appears at the current front wheel steering angle θf and the vehicle body speed Vso is calculated (estimated) as follows (311): gye = Vso ² · θf / [(1 + Kh · Vso ² ) · N・ L] (7) N: Overall steering ratio L: Wheelbase Kh: Stability factor Next, 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 body speed Vso is read from the memory (313, 314) and the delay time td = Tdo × k ₁ is calculated (estimated) (315). And this delay time t
d, calculation (sampling) cycle Δt, current step 31
Lateral acceleration gye (n) calculated in 1 and the previous time (before Δt)
Based on the calculated lateral acceleration gye (n-1), the current certain lateral acceleration gyea is calculated as gyea = [Δt / (Δt + td)] · gye (n) + [td / (Δt + td)] · gye (n- 1) Calculate (estimate) by (8) (316). Then, the lateral acceleration g estimated from the steering angle θf and the vehicle body speed Vso.
The ratio of the actual lateral acceleration gyc to yea gyc / gyea is a predetermined value k
It is smaller than 2 and the actual lateral acceleration gyc exceeds a predetermined value k3 (While there is the actual lateral acceleration gyc, the actual lateral acceleration gyc is lower than the lateral acceleration gyea that should occur due to steering: Understeer) ( 317). If so, write 1 to the register STRuF, otherwise write 0 to the register STRuF (318, 31).
9).

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

In this embodiment, the priority order is "ABS control".
400, “2-BDC control” 500, and “TRC control” 600 in this order, and “control priority processing” 300
In F, “ABS control” 400 is being executed (ABSF =
1) is "2-BDC control" 500 and "TRC control"
600 prohibits (registers BDCF and TRCF are cleared and the contents are set to 0). "2-BDC control" 50
During execution of 0 (BDCF = 1), “TRC control” 60
0 is prohibited (register TRCF is cleared). "B
The "STR control" 700 is executed independently of other controls.

"ABS control" 400, "B-STR control" 700, "2-BDC control" 500 and "TRC"
Control 600, any of the sensors YA, θF, θR, G
Detected values of X and GY, "Wheel speed calculation & Wheel acceleration calculation" 1
The control wheels (wheel brakes that control the brake pressure) are determined based on the calculated value of 00 and the calculated value of the "vehicle state quantity estimation" 200, and the target slip ratios Soi and The actual slip rate (estimated value) is calculated, and the slip rate deviation Esoi is calculated based on these, while the deviation of the wheel acceleration from the reference acceleration (wheel acceleration deviation) ED
i is calculated, and the combination of the slip ratio deviation Esoi and the wheel acceleration deviation EDi is calculated as
The brake pressure control mode (rapid pressure reduction, pulse pressure reduction, hold pressure) of the control wheel is discriminated by determining whether it is in the pulse pressure reduction region, the hold region, the pulse pressure increase region, or the rapid pressure increase region.
Field, pulse pressure boost, and rapid pressure boost). In addition, an increase / decrease compensation process for compensating the delay of increase / decrease in the brake pressure control, and an initial specific mode for smoothing the brake pressure fluctuation at the start of the brake pressure control. De arithmetic,
Also, 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-
The STR control ”700, the“ 2-BDC control ”500, and the“ TRC control ”600 are common, but since the functions are different, the control wheel selection, the slip ratio deviation Esoi, and the wheel acceleration deviation EDi are combined in each control. The brake pressure control mode associated with, the calculation constants, etc. are different. Since the outline of the processing logic is the same,
The details of the “B-STR control” 700 will be described below in detail.

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

(4A) "B-STR-OS control" 70
0A: FIGS. 12 to 19 First, refer to FIG. First, the turning direction of the vehicle is determined by referring to the yaw rate γ, and the turning direction data is written in the turning direction register (701 to 704). In this example,
The + (positive) of the polarity of the yaw rate γ is a left turn, and the − (negative) is a right turn. Next, it is checked whether ABS control is in progress (ABSF = 1).

During the ABS control, the magnitude (absolute value) of the side slip angle β and the turning direction (the turning direction register data
The wheel for controlling the brake pressure (wheel brake) is determined as shown in the block of step 708 of FIG. For example, when the turning direction is a left turn and the absolute value of the side slip angle β is less than 90 °, the wheel RL is determined as the brake pressure control target wheel (the wheel brake 54 is determined as the pressure control target), and β Absolute value of 90 ° or more and 270 °
When the absolute value of β is 270 ° or more and less than 360 °, the wheel FR is set as the brake pressure when the wheel FR is under the brake pressure control. The control target wheel is determined (the wheel brake 54 is determined as the pressure control target).

When the ABS control is not in progress (ABSF = 0), 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). The wheels (wheel brakes) are determined as shown in the block of step 707 of FIG. For example, when the turning direction is left, the absolute value of the sideslip angle β is 90 °.
When the absolute value of β is 90 ° or more and less than 270 °, the wheel FR is determined as the brake pressure when the wheel FR is under the brake pressure control. Determined as the control target wheel (determining the wheel brake 54 as the pressure control target), and the absolute value of β is 270 ° or more and 360 °
When it is less than the above, the wheel FR is determined to be the brake pressure control target wheel (the wheel brake 51 is determined to be the pressure control target).

As shown in step 707 of FIG. 12, 0
° ≦ | β | <90 ° and 270 ° ≦ | β | <360 °
When the vehicle body is facing forward 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 ° When the vehicle body is sideways or rearward with respect to its actual movement direction, the rear wheel brakes RL and RR are designated as control target wheels (the wheel brake pressure is increased). 0 ° ≦ | β | <90 °
And 270 ° ≦ | β | <360 °, the spin moment of the vehicle is suppressed as in the conventional example (Japanese Patent Laid-Open No. 3-500868), and it is effective in suppressing the abnormal turn or spin of the vehicle. . When 90 ° ≦ | β | <270 °, abnormal turning or spin is promoted in the conventional example, but in this embodiment, the rear wheel brake (the front wheel brake in the actual moving direction of the vehicle body) is increased. Since the pressure is applied, the spin moment is also suppressed, which is effective for suppressing the abnormal turn or spin of the vehicle.

In contrast to the above-described control wheel selection (707), ABS control during braking by the driver has one purpose to ensure steering performance. During ABS control, BS
Even if a certain wheel brake pressure is applied as the TR-OS control, no further braking force is obtained at that wheel, and the opposite effect is obtained. Therefore, B-STR- during ABS control
In the OS control, instead of the wheel brake that pressurizes, the brake of one wheel at the diagonal position of the wheel is depressurized.

For example, ABS control is not specified (A
When BSF = 0), in step 707, BS
The target wheel for TR-OS control is the front wheel FR / FL when 0 ° ≦ | β | <90 ° and 270 ° ≦ | β | <360 °.
(Wheel brake of), 90 ° ≦ | β | <270
When the angle is °, the rear wheel RL / RR is determined. When ABS control is designated (ABSF = 1), 0 ° ≦ | β | <90
And 270 ° ≤ | β | <360 ° rear wheel RL
/ RR is the brake pressure control target wheel, and 90 ° ≦ | β | <
At 270 °, the front wheel brake FR / FL is set as the control target wheel. This allows ABS control and B-STR-OS
The controls are in harmony.

The "control wheel selection" 705 shown in FIG.
Then, only the one-wheel brake is determined as the control target brake, but the "control wheel selection" 705 is replaced with the "control wheel selection" 705A shown in FIG. 13, and the two-wheel brake is controlled. -You may decide to decide. Further, the “control wheel selection” 705 is replaced with the “control wheel selection” 705B shown in FIG. 14, and the one-wheel brake is determined as the control target brake during the ABS control, and 2 is set when the ABS control is not performed. The wheel brake may be determined as the control target brake. Further, "control wheel selection" 705 is replaced with "control wheel selection" 705C shown in FIG. 15 to determine the two-wheel brake as the control target brake during ABS control, and when ABS control is not performed. The one-wheel brake may be determined as the control target brake.

Next, referring to FIG. When the wheel that controls 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 ( 709a ), and then the lateral slip angular velocity Dβ.
It is determined which one of the areas A0 to A7 shown in the block of step 709b in FIG. 16 has a combination of the absolute value of the above and the absolute value of the sideslip angle β ( 709b ). That is, the area Aj, j = 0 to 7, to which the combination of the absolute value of the lateral slip angular velocity Dβ and the absolute value of the lateral slip angle β belongs, is determined. next,
Referring to FIG. 17, the slip ratio correction amount ΔSi (%) of each wheel assigned to the area Aj is read from the memory ( 709c ). "B-STR control" 700 and "2-
BDC control "500 slip ratio deviation target value ΔS
(%) Indicates the slip ratio correction amount ΔSi for the area Aj, as shown in the block of step 709c in FIG.
(%) Is j. Note that in the block of step 709c in Fig. 17, "AB S Control" 400 and "TRC
The slip ratio correction amount ΔSi (%) assigned to the area Aj in the “control” 600 is also shown.

Next, the computer 11 proceeds to step 709.
a The gain K corresponding to μ obtained in FIG. 16 is multiplied by the slip ratio correction amount ΔSi (%) corresponding to the area Aj to calculate the slip ratio correction amount ΔSio = K · ΔSi of each wheel brake ( 709 d ).

Next, referring to FIG. 18, the computer 11
Requires "B-STR-OS control" (STRoF = 1)
It is checked (710) whether or not it is necessary, the data of the turning direction register is referred to, and if it indicates a left turn, the absolute value of the sideslip angle β shown in the block of step 712 is determined. The target steering angle δr corresponding to the absolute value of the value of the register β is read from the memory and written in the register δr (712). When the data of the turning direction register indicates a right turn, the value corresponding to the absolute value of the value of the register β in the target steering angle δr corresponding to the absolute value of the sideslip angle β shown in the block of step 713. Is read from the memory and written in the register δr (713).

Data of register STRoF and register δ
The data of r, the yaw rate γ, the front wheel steering angle θf, and the vehicle speed Vso are “output control” 800 (FIG. 5) after that.
Then, it is transferred to the 4WS controller 70 (FIG. 2). As will be described later, the 4WS controller 70 rear wheel RR, so as to realize a given steering amount δr (direction and amount).
Steer the RL.

Determination of the above steering amount δr (710 in FIG. 18)
˜713), the steering amount δr is increased with an increase of | β | from 0 °, and the steering amount is increased with an increase of | β | to 90 °, corresponding to the absolute value | β | of the sideslip angle β. By reducing δr, the steering direction (δ
The polarity (r) of r is reversed, the steering amount δr is increased with an increase of | β | from 90 °, and the steering amount δr is decreased with β approaching 360 °.

In this way, the steering amount is increased with an increase in the absolute value | β | of the side slip angle β from 0 °, so that the steering amount is suppressed as the amount of change in the unintended direction of the vehicle body increases. The steering amount Δr of is increased. The steering amount δr is reduced as | β | approaches 90 ° at which the direction of the vehicle body reverses with respect to the actual movement direction, and the steering direction with respect to the vehicle front-rear axis X is reversed at 90 °. When switching to the opposite direction to the moving direction, there is no steering that promotes the reverse direction, and when switching to the reverse direction, the steering direction (polarity of δr) also switches to the direction that suppresses spin. The effect of suppressing turning or spin is extremely high.

The structure of the 4WS controller 70 is shown in FIG. In brief, the 4WS controller 70 calculates the steering angle corresponding to the main steering by multiplying the front wheel steering angle θf by a coefficient (gain) corresponding to the vehicle speed Vso, and at the time of disturbance (cross wind) or vehicle turn. In order to prevent fluctuations in the traveling direction of the vehicle, the steering angle correction amount is calculated corresponding to the yaw rate γ, the front wheel steering angular velocity and the vehicle speed, and the target steering angle AGLA is calculated from these calculated steering angle and steering angle correction amount. Determine. Specifically, the front wheel steering angle value θf
In addition, the low angle value is converted to 0 through the converters 21AS and 21BS, the excessive angle is converted to the saturated value, the dead zone process and the limit process are performed, and the detected steering angle value is converted to the steering angle value for control calculation. The steering angle value (converted value) for control calculation by 23S
Is multiplied by the vehicle speed corresponding gain to calculate the auxiliary steering angle (required value) corresponding to the actual steering angle. On the other hand, the yaw rate .gamma. Is calculated in the converters 51S and 55S to 59S using the dead zone width 2Wyo corresponding to the front wheel steering angular velocity and the conversion coefficient Ic.
Gain G corresponding to vehicle speed Vso converted to rate AYs
y is calculated by the conversion unit 52S, and the calculation yaw is calculated by the multiplication unit 53.
The rate AYs is multiplied by the gain Gy to calculate the steering angle correction amount. Then, in the adding section 54S, a steering angle correction amount corresponding to the detected yaw rate γ is added to the auxiliary (rear wheel) steering steering angle (required value) to obtain a target steering angle AGLA, which is fed to the feedback control section 60S. Output.

The feedback control unit 60S basically constitutes a PD (proportional / derivative) 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 addition unit 35, and the control amount HPI is added.
The data of the register STRoF transferred from the computer 11 is 1 (B-STR-OS).
Control), the target rudder angle AGLA is calculated.
Data to be transferred to δr.

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

In the differential control system 61S, the input value ΔA
The GL is converted to ETH2 through the conversion unit 31AS, and the subtraction unit 33S inputs the input value ETH2 (latest value) and the input value ETH2 passed through the delay unit 32S (value before a predetermined time).
Is calculated, and the rate of change of ETH2, that is, the differential value SETH2 is obtained. In the multiplication unit 34S, the differential value SETH2 and the differential gain YTDIFGAIN
The value multiplied by 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 STRoF = 0, and S
When TRoF = 1, it is a variable determined based on the differential value (change speed) of δr. That is, in the subtraction unit 38S, the difference between the input value AGLA (latest value) or δr (latest value) and the input value AGLA (value before Δt) or δr (value before Δt) passed through the delay unit 37 is calculated. Calculated, thereby changing rate of AGLA or δr, that is, derivative SA
GLA is obtained, and the result of passing the differential value SAGLA through the conversion unit 39 is the differential gain YTDIFGAIN. The graphs shown in the blocks of the conversion units 31AS, 31BS, and 39S show the respective conversion characteristics, and the horizontal axis shows the input value and the vertical axis shows the output value.

Control amount HPI output from the adder 35S
D passes through the conversion unit 43S to become HPID2, and further passes through the conversion unit 44S to become the duty value DUTY. The conversion unit 43S functions as a limiter. In addition, the conversion unit 44S
Has a function of converting the deviation steering angle value to the duty value. Duty value DUTY is pulse width modulation (PWM)
It is input to the section 45S. The pulse width modulator 45S generates a pulse signal of a duty corresponding to the input value and applies it 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 conversion unit 46S identifies the rotation direction from the phases of the three-phase pulses output by the magnetic pole sensor RS, counts 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 conversion unit 46S is the actual steering angle R
Output AGL. The subtraction unit 47S determines 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 of the register STRoF transferred from the computer 11 is 1 (B-STR-OS control is required), 4WS
As described above, the controller 70 changes the target rudder angle AGLA to δr transferred from the computer 11 and urges the motor M1 to bring about this rudder angle, thus suppressing the oversteer. Therefore, when δr changes significantly, the rear wheel steering amount increases and the 4WS controller 70 causes
The rear wheel steering strongly acts to secure the stability in the vehicle traveling direction, and the oversteer is strongly suppressed.

Incidentally, "B-STR-OS control" 700A
The slip ratio correction amount ΔSio calculated for each wheel is used as an input parameter for wheel brake pressure control (pressure increase, hold, pressure reduction) in a "slip ratio servo calculation" 700C described later. , Is reflected in the wheel brake pressure control.

(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) .

Next, the reference vehicle speed V with respect to the vehicle body speed Vso
The deviation of sou ΔV = Vsou−Vso is calculated, and each wheel slip ratio correction amount ΔSiu is calculated (718). That is,
Constant Ki assigned to each wheel, ΔV, and μ corresponding gain K
The value obtained by multiplying the product of ( 709a , FIG. 16) by-(minus) and 0 is the larger one, and the larger one is the slip ratio correction amount ΔSiu
And

(4C) "Slip ratio servo calculation" 70
0C: FIG. 21 First, whether "B-STR-OS control" is required or "B-ST"
Check if "R-US control" is required, and check "B-ST".
If the R-OS control is required (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 selected.
If it is necessary (STRuF = 1), the data of the register ΔSiu (calculated in step 718) is selected as the slip ratio deviation ΔSi (721 to 726). "B-STR-O
S control "unnecessary (STRoF = 0) and" B-STR-
When "US control" is not necessary (STRuF = 0), the slip ratio correction amount ΔSi is set to 0 (721 to 726).

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

In this embodiment, the slip ratio target value SoABS
i, SoBDCi, SoTRCi and SoSTRi are fixed values, and S
oABSi = 0.15, SoBDCi = 0.01, SoTRCi =-
0.07 and SoSTRi = 0.

The above-mentioned "control priority processing" 300F
Then, "ABS control" 400 is being executed (ABSFi = 1)
Executes "B-STR control" 700 (register ST
(The data of RoF and STRuF are not changed.)
"2-BDC control" 500 and "TRC control" 600
Is disabled (registers BDCF and TRCF are cleared to 0), and “B-STR control” 700 is being executed (STRoF = 1 or STRuF = 1), “ABS control” 400 is being executed (register). "ABSD is not cleared", but "2-BDC control" 500 and "TRC control" 600 are prohibited (registers BDCF and TRCF are cleared and the contents are set to 0), and "2-BDC control" 5
During execution of 00 (BDCF = 1), “TRC control” 6
00 is prohibited (register TRCF is cleared), so ABSF = 1, STRoF = 1 or STRuF = 1
, BDCF = 0 and TRCF = 0, and the slip ratio target value Soi calculated in steps 728 to 735 does not include SoBDCi and SoTRCi. ABSF =
0, STRoF = 0 and STRuF = 0, BDCF
Since BTRC = 0 when = 1, the slip ratio target value Soi is the slip ratio correction amount (corresponding to ΔSi above) calculated for the “2-BDC control” (by the calculation corresponding to the above steps 721 to 727). What you do) + SoBDCi. When ABSF = 0, STRoF = 0, STRuF = 0, and BDCF = 0 and TRCF = 1, the slip ratio target value Soi is the slip calculated for the “TRC control” (by the calculation corresponding to the above steps 721 to 727). Supplement
R> positive amount (corresponding to the above ΔSi) + SoTRCi.

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

Referring to FIG. When the slip ratio target value Soi is calculated as described above, the computer 11 calculates the slip ratio 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, The control wheel speed, the reference acceleration, and the control wheel acceleration are “BS” in the table in the block of step 736.
This is shown in the column of "TR control".

Next, it is checked whether the absolute value of the slip ratio deviation Esoi is less than a predetermined value ε (737A), and if it is more than the predetermined value ε, the integrated value IEsoi of the slip ratio deviation Esoi is checked.
Is calculated (737B). That is, the value obtained by adding the gain GIi × the slip ratio deviation Esoi calculated this time to the slip ratio deviation integrated value IEsoi calculated last time is set as the slip ratio deviation integrated value IEsoi calculated this time. The gain GIi is 1 in this embodiment. This slip ratio deviation integrated value IE
In order to limit soi to the upper limit value IEsoiU or less and the lower limit value IEsoiL or more, the value of the slip ratio deviation integral value IEsoi is updated to the upper limit value IEsoiU when IEsoi is IEsoiU or more, and the slip ratio deviation integral is equal to or less than IEsoiL. Value IEs
Update the value of oi to the lower limit value IEsoiL (738-74)
1). IEsoi is cleared to 0 when | Esoi | <predetermined value ε (737C).

Next, the parameter Y for judging the brake pressure control mode is calculated as 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, it is a large value.

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

Referring to FIG. The computer 11 then uses memory access to determine the combination (X, Y) of the parameters X and Y as a predetermined rapid decompression region, pulse decompression region, hold region, pulse pressure increase region and It is determined which one of the rapid pressure increase regions is (74
6). Note that, for example, the control wheel is FR (wheel brake 51).
In the case of, the subsequent control (“output control” 800) determines that the pressure is in the sudden depressurization region. ] (Continuous) is set. When it is determined that the pressure is in the pulse depressurization region, the depressurization for a predetermined time and the hold for a predetermined time (electromagnetic switching valve 61 energized, solenoid valve 31 energized (valve closed) and solenoid valve 32 deenergized (valve closed)) are performed. Set repeat. If it is determined to be in the hold area, the continuation (continuous) of the hold is set. If it is determined that the pressure is in the pulse pressure increasing region, pressure increase for a predetermined time [electromagnetic switching valve 61 energization,
Solenoid valve 31 non-energized (valve open) and solenoid valve 32 non-energized (valve closed)] and repetition of the above-mentioned hold for a predetermined time are set. When it is determined that the pressure increase region is set, the pressure increase is set to be continued (continuous).

Here, oversteer compensation control (B-ST
To summarize the process leading to the setting of the increase / decrease in R-OS control), step 20 of “Vehicle state quantity estimation” 200
2 (FIG. 7), the friction coefficient μ is calculated, and the coefficient K corresponding to this friction coefficient μ, that is, the coefficient K having a large value when μ is high, is calculated in step 709a (B-STR-OS control) 700A. It is calculated in FIG. 16). In the next step 709b (FIG. 16), it is determined which region of A0 to A7 the combination of the side slip angle β and the side slip angular velocity Dβ is, and in the next step 709c (FIG. 17), the slip ratio correction is performed corresponding to the region. The amount ΔS is determined. That is, the slip ratio correction amount ΔS having a larger value is determined correspondingly to the side slip angle β and the side slip angular velocity Dβ, as the side slip angle β is larger and the side slip angular velocity Dβ is larger. Then, the product K · [Delta] S factor K and the slip ratio correction amount [Delta] S and each wheel correction amount ΔSio (709 d in FIG. 17), the target sum of the target value SoSTRi of each wheel correction amount DerutaSio and B-STR control The slip ratio Soi is used (723,725,72 in FIG. 21).
7,734,735). Then, the slip rate deviation Esoi and the acceleration deviation EDi are calculated (736 in FIG. 22), and the slip rate deviation E
The integrated value IEsoi of soi is calculated and set as Y, and the acceleration deviation EDi is set as X (737 to 745 in FIG. 22). According to X and Y, if X and Y are positive and both of them are large, the pulse increase will occur. The pressure or the sudden pressure increase is set, and when X and Y are negative and their absolute values are both large, the pulse pressure reduction or the rapid pressure reduction is set (746 in FIG. 23).

By setting the wheel brake pressure in this way,
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 that the actual slip ratio becomes large (the actual output for performing this pressure adjustment is described later in "output control" 800 (FIG. 5). Do). As a result, the wheel brake pressure rises, the side slip angle increases, and an opposite moment to the spin moment is generated, which suppresses the increase in the side slip angle.

When the coefficient of friction μ is high, it is expected that the increase of the wheel brake pressure effectively suppresses the increase of the sideslip angle, that is, the suppression of the spin behavior. In this case, 709a (Fig. 1
Since the target slip ratio Soi is set to a large value by 6), the vehicle spin suppressing effect is high. On the other hand, if the friction coefficient μ is low, not only the effect of suppressing the vehicle spin by increasing the wheel brake pressure is low, but also the yaw motion of the vehicle body may be disturbed. In this case, since the target slip ratio Soi is set to a small value by 709a (FIG. 16), excessive increase of the wheel brake pressure is suppressed. Since the friction coefficient μ is used as a parameter for controlling the wheel brake pressure for oversteer compensation, the stability of oversteer compensation is improved.

Based on the vehicle side slip angle β, the friction coefficient μ and the side slip angular velocity Dβ, the side slip angular velocity Dβ is obtained.
Is large, a large target slip rate Soi is determined, slip rate deviation ESoi = target slip rate Soi-actual slip rate, and acceleration deviation EDi = wheel acceleration not determined to increase / decrease DNVso-increase / decrease. Wheel acceleration DNV
Corresponding to soi, the pressure increase is determined when the deviations ESoi and EDi are positive and their absolute values are large, and the pressure reduction is determined when they are negative and their absolute values are large. The slip rate is controlled to be close to the rate Soi. As a result, the slip ratio becomes larger than other non-controlled wheels,
An anti-spin moment is created.

Next, understeer compensation control (B-STR
-US control) to increase or decrease pressure (step 7 in FIG. 23)
46), the lateral acceleration gyc detected by the lateral acceleration sensor GY (to be exact, 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. The reference lateral acceleration gye is calculated in step 311 of FIG. 10 corresponding to the steering amount θf and the vehicle body speed Vso,
In steps 312 to 316, the reference lateral acceleration gye is corrected by a turning delay with respect to the turning, so that gyc <k2 · gyea when gyc <k2 · gyea, as a reference lateral acceleration gyea.
On condition that c> k3, 1 is written in the register STRuF (312 to 318 in FIG. 10).

In step 717 of FIG. 20, the reference vehicle body speed Vsou that causes the lateral acceleration gyc in the vehicle body with the steering amount θf is estimated and calculated, and the vehicle body speed V with respect to the reference vehicle body speed Vsou is calculated.
Target slip ratio deviation ΔSiu corresponding to deviation ΔV of so
Is determined and added to the reference slip rate SoSTRi defined in the B-STR-US control, and the sum is set as the target slip rate Soi (724, 726, 727 in FIG. 21).
734, 735). Then, the actual slip ratio of the wheel is estimated and calculated based on the wheel rotation speed Vwi and the vehicle body 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 integrated value IEsoi of i is calculated, and the slip ratio deviation Eso is calculated.
A value proportional to i + integrated value IEsoi is increased and used as one parameter Y for pressure reduction determination, and a value proportional to acceleration deviation EDi is increased as another parameter X for pressure reduction determination (see FIG. 23). 737-745). Then, in step 746 of FIG. 23, the increase / decrease mode is determined.

By setting the wheel brake pressure in this way,
For example, for the reference lateral acceleration gye, the detected lateral acceleration gy
When c is relatively low, the control wheel is boosted (actual output for this boosting is performed by “output control” 800 (FIG. 5) described later). As a result, when the detected lateral acceleration gyc does not reach the reference lateral acceleration gye, the vehicle body is braked, and the vehicle body speed Vso is reduced by this braking, and the reference lateral acceleration gye is turned. When the vehicle body speed is high, the friction coefficient μ is low, or the tire wear is advanced, insufficient turning easily occurs with respect to the steering amount θf.
This turning (insufficiency) appears in the lateral acceleration gyc detected by the vehicle body lateral acceleration detecting means (GY) and is introduced to the determination of the increase in the wheel brake pressure, in which case the wheel brake pressure is increased. Therefore, the stability and reliability of the understeer compensation control are improved. Specifically, the reference lateral acceleration gye is corrected by a correction corresponding to the turning delay with respect to the turning, and the detected lateral acceleration gyc is compared with the reference lateral acceleration gyea. Therefore, the understeer compensation including the optimum delay corresponding to the steering speed is performed. Since the control is performed, its stability and reliability are further improved.

As shown in steps 728 to 734 of FIG. 21, the target slip ratio for the understeer compensation control (B-STR-US control) of the present case is calculated as in the ABS control, and the target slip ratio for the ABS control is calculated. 22 and the increase / decrease of the wheel brake is determined according to the added value as shown in step 736 of FIG. 22 to step 746 of FIG. 23, so that the brake pressure control outputs do not contradict each other.
The ABS control and the understeer compensation control of the present case match.

When the pressure increase or pressure reduction is set as described above, the computer 11 then determines whether the determined region corresponds to the region determined this time and the region determined last time from the pressure reduction to the pressure increase (pulse pressure increase). , Rapid pressure increase), or switching from increased pressure to pressure reduction (pulse pressure reduction, rapid pressure reduction), a brake pressure control mode for smoothing the rise / fall of the wheel brake pressure. Make an adjustment (747). For example, when changing from a sudden decrease at ABS to a pulse pressure increase, the pressure increase duty (pressure increase time / (hold time)) of the pulse pressure increase is set to 0 for a predetermined time from then to the pulse pressure increase region. Gradually start up to a specified value (set the boosting duty for that).

Next, the computer 11 uses, for example, a B-ST.
Start of R control (STRoF = 0 → STRoF = 1 or S
When TRuF = 0 → STRuF = 1 is switched), initial pressurization for increasing the responsiveness of the braking force is performed (748). Also, for example, the end of the B-STR control (ST
RoF = 1 → STRoF = 0 or STRuF = 1 → ST
When there is a change (RuF = 0), the brake pressure control is performed in order to match the control hydraulic pressure immediately before the control wheel with the master cylinder hydraulic pressure, the pressure is adjusted, and the control is terminated.

(5) "ABS control" 400: FIG. 25 Referring to FIG. In the "ABS control" 400, it is checked whether the combination of the side slip angular velocity Dβ and the vehicle body speed Vso is in the start range 1 or the combination of the side slip angle β and the vehicle body speed Vso is in the start range 2 (304A, 304A, Thirty
4B). The start areas 1 and 2 are those referred to when the "B-STR-OS control" 700A (304 and 3 in FIG. 9).
It is the same as in (05), and it is determined that there is a spin tendency when in the start range 1 or 2, and the target slip ratio SφABSi (i = RL, RR) of the rear wheel during ABS control is set to SφABSR,
If it is not in either of the start regions 1 and 2, the target slip ratio SφABSi is set to SφABS (705AA). Here, SφABSR and SφABS are constants, respectively, and SφABS is a normal value, but SφABSR is
It is a value at the time of the spin tendency where SφABSR <SφABS. Regarding the target slip ratio of the front wheels, the target slip ratio SφABSi (i = FR, FL) is a fixed value. With the above processing, when the vehicle body spin tendency is detected during steering, the target slip ratio (Soi) of the rear left and right wheels (RR, RL) is detected.
Is set lower than when the vehicle body spin tendency is not detected (7
05AA). Thereby, the lateral force of the rear wheels is secured, the vehicle stability is improved, and the tendency of the vehicle body spin during turning braking is suppressed.

B-STR control (over-steering, under-steering)
Vehicle stability control for suppressing steering is performed concurrently with ABS control (when it is determined that each is required). When the ABS control state is brought about by the brake operation during the B-STR control, the control for suppressing the spin tendency during the steering of the ABS control is complementarily coordinated,
High vehicle stability is obtained.

(6) "Output control" 800 "ABS control" 400, "2-BDC control" 500,
"TRC control" 600 and "B-STR control" 700
Outputs (energizing / non-energizing) of the brake pressure control mode determined by each "slip rate servo calculation" (Fig. 3) are generated and output to the solenoid valve drivers 19b to 19m. To do.

[0092]

In response to the detection of the vehicle body spin tendency during turning, the target slip ratio setting means (11) causes the rear left and right wheels (RR,
The target slip ratio (So) of (RL) is set to be lower (705AA) than when the vehicle body spin tendency is not detected. As a result, the lateral force of the rear wheels is secured, the vehicle stability is improved, and the tendency of the vehicle body to spin during rotational braking is suppressed.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a schematic configuration of an electronic control unit that controls energization of solenoid valves and the like of the wheel brake pressure system shown in FIG.

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

FIG. 4 is a flowchart showing an outline of the contents of wheel brake pressure control of the microcomputer 11 shown in FIG. 2, mainly showing the flow of information.

FIG. 5 is a flowchart showing an outline of wheel brake pressure control of the microcomputer 11 shown in FIG.
It is a chart.

[Fig. 6] "Wheel speed calculation & wheel acceleration calculation" shown in Fig. 5
It is a flowchart showing the contents of 100.

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

[FIG. 8] “Control mode start / end processing” 3 shown in FIG.
It is a flowchart showing the contents of 00.

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

10 is a flowchart showing the contents of "B-STR-US start / end determination" 300E shown in FIG.

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

[FIG. 12] “B-STR-OS control” 7 shown in FIG.
It is a flowchart showing a part of the contents of 00A.

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

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

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

16 is a "B-STR-OS control" 7 shown in FIG.
It is a flowchart showing a part of the contents of 00A.

FIG. 17 shows “B-STR-OS control” 7 shown in FIG.
It is a flowchart showing a part of the contents of 00A.

FIG. 18 is a “B-STR-OS control” 7 shown in FIG. 11.
It is a flowchart showing a part of the contents of 00A.

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

[FIG. 20] “B-STR-US control” 7 shown in FIG.
It is a flowchart showing the contents of 00B.

21 is a "slip ratio servo calculation" 7 shown in FIG.
It is a flowchart showing a part of the contents of 00C.

22 is a "slip ratio servo calculation" 7 shown in FIG.
It is a flowchart showing a part of the contents of 00C.

23 is a "slip ratio servo calculation" 7 shown in FIG.
It is a flowchart showing a part of the contents of 00C.

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

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

[Explanation of symbols]

2: Brake master cylinder 3: Brake
Key pedal 4: Break liquid reservoir 5: Hydro booster 6: Proportional control valve 10: Electronic control unit 11: Micro computer 12: Input interface 13: Output interface 14: CP
U 15: ROM 16: RA
M 17: Timer 18a-1
8m: Signal processing circuits 19a to 19m: Motor driver and solenoid driver 20: High pressure source 21: Pump 22: Accumulator 23: Relief valve 24: Electric motor 25: Check valve 31, 33, 35, 37 : Pressure increasing solenoid valves 32, 34, 36, 38: Pressure reducing solenoid valves 41 to 44: Wheel speed sensor 45: Stop switch 46: Pressure sensor 47: Low pressure switch YA: Yaw rate sensor θF: Front wheel steering angle sensor θR : Rear wheel steering angle sensor GX: longitudinal acceleration sensor GY: lateral acceleration sensors 51-54: wheel brakes 61, 62, 63, 64: electromagnetic switching valves 139-1
42: Check valve

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Mihara 2-1-1 Asahi-cho, Kariya city, Aichi Prefecture Aisin Seiki Co., Ltd. (72) Yoshiharu Nishizawa 2-1-1 Asahi-cho, Kariya city, Aichi prefecture In Aisin Seiki Co., Ltd. (72) Inventor Shingo Sugiura, 2-1-1 Asahi-machi, Kariya city, Aichi Prefecture In Aisin Seiki Co., Ltd. (56) Reference JP-A 1-208256 (JP, A) JP JP 4-287754 (JP, A) JP-A-6-247269 (JP, A) JP-A-3-279063 (JP, A) JP-A-4-362471 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60T 8/00 B60T 8/32-8/96

Claims (3)

(57) [Claims] 1. A wheel rotation speed detecting means, a vehicle body speed detecting means for calculating a vehicle body speed from the wheel rotating speed, a means for estimating and calculating a wheel slip ratio based on the wheel rotating speed and the vehicle body speed, and a wheel when the wheel slip ratio is high. In a wheel brake pressure control device including information processing means for determining the reduction of the brake pressure and brake pressure operating means for reducing the wheel brake pressure according to the determination, a means for detecting a tendency of vehicle body spin A side slip angle detecting means for estimating and calculating a vehicle side slip angle β; a side slip angular velocity for estimating and calculating a vehicle side slip angular velocity Dβ
Detecting means: When the vehicle body spin tendency is detected, the target slip ratios of the rear left and right wheels are set lower than when the vehicle body spin tendency is not detected, and correspond to the sideslip angle β and the sideslip angular velocity Dβ.
And a target slip ratio setting means for setting a lower target slip ratio as each of them is larger ; and an information processing means for determining increase / decrease of wheel brake pressure for matching the wheel slip ratio to the target slip ratio. A wheel brake pressure control device comprising: 2. The wheel brake pressure control device according to claim 1, wherein the vehicle body spin tendency detecting means detects a vehicle body spin tendency when the sideslip angle β and the vehicle body speed Vso are respectively larger than a predetermined value. 3. A means for detecting the vehicle spin tendency, when slip angular velocity Dβ and the vehicle body speed Vso is greater than the respective predetermined value to detect the vehicle spin tendency, according to claim 1 or
The wheel brake pressure control device according to claim 2 .