JP2008302717A - Anti-lock brake control device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an amount of the consumption of a brake liquid during an anti-lock brake control operation so as to improve a brake operation feeling and to attain stable braking performance while keeping an appropriate slip rate for a long period of time in an anti-lock brake control device for a vehicle in which at least a brake-force reducing mode and a brake-force increasing mode are changed over and an action of a brake actuator is controlled by a brake control means. <P>SOLUTION: This brake control means calculates a desired value of a brake force of a wheel brake according to a difference between a wheel speed detected by a wheel speed detecting means and a desired wheel speed calculated by a desired wheel speed calculating means, defines the desired value as a desired brake force in a brake force increasing mode, defines a lower brake force in the desired brake force set at a previous calculation period and a desired value calculated at a present calculation period as a desired brake force in a brake force decreasing mode, and controls a brake actuator 5 in such a way that the desired brake force may be exhibited by the wheel brake. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a brake actuator capable of adjusting a braking force of a wheel brake mounted on a wheel, and at least a reduction of the braking force of the wheel brake in order to prevent the wheel from being locked when the wheel brake is operated. The present invention relates to an anti-lock brake control device for a vehicle, which includes a brake control means for controlling the operation of the brake actuator by switching between a decrease mode for increasing and an increase mode for increasing the brake force.

When controlling the brake fluid pressure of a wheel brake that operates with hydraulic pressure, the target pressure increase / decrease gradient of the brake pressure is obtained from the rotation state of the wheel and the duration of the pressure increase mode and the pressure decrease mode. An anti-lock brake control device for a vehicle in which the current target brake hydraulic pressure is obtained by adding to the current target brake hydraulic pressure is already known from, for example, Patent Document 1 or the like.
JP 2002-356157 A

  By the way, in the anti-lock brake control for avoiding the wheels from falling into the locked state at the time of braking, the above-mentioned Patent Document 1 controls the increasing / decreasing gradient and repeats increasing / decreasing in a short cycle. Therefore, it is hard to say that the brake operation feeling is excellent. In addition, it is difficult to say that the appropriate slip ratio of the wheel during the anti-lock brake control is continued for a long time, and it is desired to further stabilize the braking performance.

  The present invention has been made in view of such circumstances, and reduces the consumption of brake fluid during anti-lock brake control to improve the brake operation feeling and stabilize the appropriate slip ratio for a long time. An object of the present invention is to provide an anti-lock brake control device for a vehicle that can achieve the braking performance.

  In order to achieve the above object, the present invention provides a brake actuator capable of adjusting a braking force of a wheel brake mounted on a wheel, and at least a avoidance of the wheel falling into a locked state when the wheel brake is operated. An antilock brake control device for a vehicle, comprising: a brake control means for controlling the operation of the brake actuator by switching between a decrease mode for decreasing the brake force of the wheel brake and an increase mode for increasing the brake force. Wheel speed detection means for detecting the vehicle body speed, vehicle speed detection means for detecting the vehicle body speed, and target wheel speed calculation means for calculating the target wheel speed based on the vehicle body speed detected by the vehicle body speed detection means, The brake control means includes the wheel speed detected by the wheel speed detection means and the wheel speed. While calculating the target value of the braking force of the wheel brake based on the deviation of the target wheel speed calculated by the target wheel speed calculating means, the target value is determined as the target braking force in the increase mode, and the previous value in the decrease mode. The lower one of the target brake force determined in the calculation cycle and the target value calculated in the current calculation cycle is determined as a target brake force, and the brake actuator is configured so that the wheel brake exhibits the target brake force. It is characterized by controlling.

  According to the above configuration of the present invention, the target value of the braking force of the wheel brake at the time of the antilock brake control is determined based on the wheel speed detected by the wheel speed detecting means and the deviation of the target wheel speed calculated by the target wheel speed calculating means. Therefore, it is possible to obtain a more stable braking performance by maintaining a proper slip ratio for a long time and to reduce brake fluid consumption during anti-lock brake control. Can be improved. Moreover, in the decrease mode, the lower of the target brake force in the previous calculation cycle and the target value calculated in the current calculation cycle is set as the target brake force so that the wheel brake can exert the target brake force. Since the brake actuator is controlled, the wheel speed can be recovered to the vicinity of the vehicle body speed, the estimation accuracy of the vehicle body speed can be improved, and the vehicle stability can be improved.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on one embodiment of the present invention shown in the accompanying drawings.

  1 to 4 show an embodiment of the present invention, FIG. 1 is a hydraulic system diagram showing a configuration of a vehicle brake hydraulic pressure control device, and FIG. 2 is a block diagram showing a partial configuration of a controller. FIG. 3 is a flowchart showing a target brake force calculation procedure in the brake control means, and FIG. 4 is a timing chart at the time of antilock brake control.

  First, in FIG. 1, a brake operating force generated by a passenger's brake operation is input from the brake pedal 1 to a master cylinder M that outputs a hydraulic pressure corresponding to the brake operation. The master cylinder M is configured in a tandem type, and includes a first output port 3 corresponding to a left front wheel brake BA and a right rear wheel brake BB, and a right front wheel brake (not shown). And a second output port 4 corresponding to a left rear wheel brake (not shown). The first and second output ports 3 and 4 are connected to the wheel brakes BA, BB,. Connected to. Thus, the left front wheel brake BA, the right rear wheel brake BB, the right front wheel brake, and the left rear wheel brake are disc brakes that operate according to the action of hydraulic pressure.

  The part on the first output port 3 side of the brake actuator 5 and the part on the second output port 4 side have the same configuration. Hereinafter, only the part on the first output port 3 side of the brake actuator 5 will be described. A description of the portion of the brake actuator 5 on the second output port 4 side will be omitted.

  The brake actuator 5 includes a hydraulic pressure path 6 common to the left front wheel brake BA and the right rear wheel brake BB, and a regulator valve 7 interposed between the hydraulic pressure path 6 and the first output port 3. A one-way valve 8 connected in parallel to the regulator valve 7 to allow the brake fluid to flow to the hydraulic pressure path 6 side, and an inlet interposed between the hydraulic pressure path 6 and the left front wheel brake BA. A valve 9, an inlet valve 10 interposed between the hydraulic pressure path 6 and the right rear wheel brake BB, and the inlet valves 9, 10 allowing the brake fluid to flow to the hydraulic pressure path 6 side. Between the one-way valves 11 and 12 connected in parallel to each other, a single reservoir 13 common to the left front wheel brake BA and the right rear wheel brake BB, and between the left front wheel brake BA and the reservoir 13. An interposed outlet valve 14; An outlet valve 15 interposed between the rear wheel brake BB and the reservoir 13, a pump 18 whose suction side is connected to the reservoir 13 via a one-way valve 16, and a discharge side of the pump 18 A damper 19, an orifice 20 provided between the damper 19 and the hydraulic pressure path 6, and a suction valve 21 provided between the suction side of the pump 18 and the one-way valve 16 and between the first output port 3. . The pump 18 is driven by an electric motor 17 that is common to a portion on the first output port 3 side and a portion on the second output port 4 side of the brake actuator 5.

  The regulator valve 7 and the inlet valves 9 and 10 are normally open linear solenoid valves, the outlet valves 14 and 15 are normally closed linear solenoid valves, and the suction valve 21 is a normally closed solenoid valve. is there. A master cylinder output hydraulic pressure detecting means 22 for detecting the output hydraulic pressure of the master cylinder M is connected between the first output port 3 and the regulator valve 7, and the inlet valves 9, 10 and the left front wheel wheel brake BA are connected. The brake fluid pressure detecting means 23 and 24 for detecting the brake fluid pressure acting on the left front wheel brake BA and the right rear wheel brake BB are respectively connected between the right rear wheel brake BB and the right rear wheel brake BB. .

  In such a brake actuator 5, by operating the electric motor 17 with the suction valve 21 excited and opened, the pump 18 sucks and pressurizes the brake fluid from the master cylinder M side to the regulator valve 7. And it discharges to the hydraulic path 6 between the inlet valves 9 and 10. At this time, by controlling the operation of the regulator valve 7, the hydraulic pressure in the hydraulic pressure path 6 can be adjusted.

  That is, the pump 18 and the regulator valve 7 apply the hydraulic pressure adjusted to the hydraulic pressure path 6 during non-braking operation, and the hydraulic pressure is controlled by the inlet valves 9 and 10 and the outlet valves 14 and 15. Thus, different brake fluid pressures can be applied to the left front wheel brake BA and the right rear wheel brake BB, thereby executing brake control such as behavior stability control and traction control during vehicle travel. Can do.

  During service braking, the operation of the electric motor 17 is stopped, the regulator valve 7 is opened, and the suction valve 21 is closed to prevent the left front wheel and the right rear wheel from being locked during service braking. When the anti-lock brake control is performed, the braking force of the left front wheel brake BA and the right rear wheel brake BB is reduced by the brake actuator 5 in at least a decreasing mode for decreasing the braking force and an increasing mode for increasing the braking force. In this embodiment, the adjustment is performed by switching between the decrease mode, the holding mode for holding the braking force, and the increase mode.

  Thus, in the decreasing mode in which the braking force exerted by the left front wheel wheel brake BA is reduced, the hydraulic valve 6 and the left front wheel wheel brake BA are closed by closing the inlet valve 9 and opening the outlet valve 14. In the holding mode in which the space between the left front wheel brake BA and the reservoir 13 is connected and the braking force exerted by the left front wheel wheel brake BA is maintained, both the inlet valve 9 and the outlet valve 14 are closed. As a result, the hydraulic pressure path 6 and the reservoir 13 are disconnected from the left front wheel wheel brake BA, and in the increase mode in which the braking force exerted by the left front wheel wheel brake BA is increased, the inlet valve 9 is opened and the outlet is opened. By closing the valve 14, the hydraulic pressure path 6 and the front left wheel brake BA are connected, and the front left wheel brake BA and the reservoir are connected. 3 while it is shut off. Further, in the decrease mode in which the braking force exerted by the right rear wheel brake BB is reduced, the hydraulic valve 6 and the right rear wheel brake BB are closed by closing the inlet valve 10 and opening the outlet valve 15. In the holding mode where the right rear wheel wheel brake BB and the reservoir 13 are connected and the braking force exerted by the right rear wheel wheel brake BB is maintained, both the inlet valve 10 and the outlet valve 15 are connected. In the increase mode in which the hydraulic pressure path 6 and the reservoir 13 are disconnected from the right rear wheel wheel brake BB by closing the valve and the braking force exerted by the right rear wheel wheel brake BB is increased, the inlet valve 10 is opened. And the outlet valve 15 is closed to connect the hydraulic pressure path 6 and the right rear wheel wheel brake BB, and to connect the right rear wheel wheel brake BB and During serial reservoir 13 is cut off.

  The regulator valve 7, the inlet valves 9 and 10, the outlet valves 14 and 15, the electric motor 17 and the suction valve 21 of the brake actuator 5 are controlled by a controller C. The controller C includes a master cylinder output hydraulic pressure. The detection values of the detection means 22 and the brake fluid pressure detection means 23 and 24 are input.

  In FIG. 2, the portion of the controller C that executes antilock brake control of the left front wheel brake BA includes vehicle body speed detection means 28 for detecting the vehicle body speed, and vehicle body speed detected by the vehicle body speed detection means 30. Based on the target wheel speed calculating means 29 for calculating the target wheel speed of the left front wheel, the vehicle body speed detected by the vehicle body speed detecting means 28 and the wheel speed detected by the wheel speed detecting means 25A for detecting the wheel speed. And a brake control means 31 for controlling the brake actuator 5 on the basis thereof.

  When the vehicle is a front wheel drive vehicle, the vehicle body speed detection means 28 calculates the vehicle body speed based on the detection values of the wheel speed detection means 25B and 25D that detect the wheel speeds of the left and right rear wheels, which are driven wheels, respectively. .

  The brake control means 30 controls the brake actuator 5 to change the brake force of the left front wheel brake BA according to the procedure shown in FIG. 3 during the antilock brake control of the left front wheel. In S1, the speed difference Ve is calculated by subtracting the target wheel speed of the left front wheel calculated by the target wheel speed calculating means 29 from the wheel speed of the left front wheel detected by the wheel speed detecting means 25A. Thus, the brake control means 30 is used for the left front wheel based on the wheel speed detected by the wheel speed detecting means 25A and the deviation of the target wheel speed of the left front wheel calculated by the target wheel speed calculating means 29, that is, the speed difference Ve. The target value of the braking force of the wheel brake BA is calculated. In this embodiment, the target value is calculated by PID feedback calculation. Therefore, in steps S2 to S4, the proportional term, the integral term, and the derivative term are calculated, respectively, and in step S5, the integral term is added to the proportional term, and further the derivative term is added to thereby increase the braking force as the feedback amount addition value. Is obtained.

  In step S6, it is determined whether or not the antilock brake control (hereinafter referred to as ABS) is in the decrease mode. Here, when the estimated vehicle body speed Vv, the target wheel speed Vt, and the wheel speed Vw change as shown in FIG. 4A, the threshold value Vg is set as shown in FIG. The ABS reduction mode is selected when Vw <Vg, the wheel acceleration ω obtained by differentiating the wheel speed Vw is ω ≧ 0, and the ABS holding mode is selected, and the wheel speed Vw is estimated vehicle body speed. Returning to Vv and increasing mode is selected when ω <0, and as shown in FIG. 4B, the increasing mode, decreasing mode and holding mode are switched.

  Further, the proportional term, the integral term, and the differential term in the PID feedback calculation change as shown in FIG. 4C, and the feedback amount addition value, that is, the target value α of the braking force is changed as shown in FIG. Change.

  Thus, when it is determined in step S6 that the mode is not the decrease mode, the routine proceeds to step S7, where it is determined whether or not the mode is the increase mode. If the mode is the increase mode, the target value α of the brake force is set to the target brake force in step S8. And When it is determined in step S6 that the mode is not the decrease mode, it is determined in step S9 whether or not the holding mode is set. If it is not the mode, the target brake force is set to “0” in step S11.

  Further, when it is determined in step S6 that the reduction mode is selected, the process proceeds to step S12, and the lower of the target brake force determined in the previous calculation cycle and the target value α calculated in the current calculation cycle is set as the target brake force. Determine. As a result, as shown in FIG. 4 (e), when the feedback amount addition value, that is, the target value increases after decreasing in the decrease mode, the minimum value of the feedback amount addition value is continuously determined as the target braking force. Accordingly, even in the holding mode after the decreasing mode, the minimum value of the feedback amount addition value is continuously held as the target braking force.

  Next, the operation of this embodiment will be described. The brake control means 30 of the controller C is configured such that the wheel speed detection means 25A detects the target value of the brake force of the left front wheel brake BA during the antilock brake control. Based on the deviation of the target wheel speed calculated by the speed and the target wheel speed calculating means 29, for example, the calculation is performed by feedback PID calculation, so that the time for obtaining an appropriate slip ratio is continued for a long time and more stable braking performance is obtained. Can do. Further, it is possible to improve the brake operation feeling by the brake pedal 1 by reducing the amount of brake fluid consumed during the anti-lock brake control. In particular, as in this embodiment, the brake actuator 5 is pumped from the reservoir 13. When the pump 18 for returning the brake fluid to the master cylinder M side is provided, the pulsation of the pump 18 can be reduced.

  Moreover, in the decrease mode, the lower of the target brake force in the previous calculation cycle and the target value of the brake force calculated in the current calculation cycle is set as the target brake force, and the wheel brake BA exhibits the target brake force. Thus, since the brake actuator 5 is controlled, the wheel speed can be recovered to near the vehicle body speed to increase the estimation accuracy of the vehicle body speed, and the vehicle stability can be improved.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims. It is.

  For example, in the above embodiment, the brake actuator 5 adjusts the brake force by adjusting the brake fluid pressure. However, the present invention is not limited to such a brake, and the brake capable of adjusting the brake force. The present invention can be widely applied to an antilock brake control device for a vehicle including an actuator.

1 is a hydraulic system diagram showing a configuration of a vehicle brake hydraulic pressure control device. It is a block diagram which shows the partial structure of a controller. It is a flowchart which shows the target brake force calculation procedure in a brake control means. It is a timing chart at the time of anti-lock brake control.

Explanation of symbols

5 ... brake actuator 25A ... wheel speed detection means 28 ... vehicle body speed detection means 29 ... target wheel speed calculation means 30 ... brake control means BA ... wheel brake BB for left front wheel・ Right wheel brake

Claims (1)

  A brake actuator (5) capable of adjusting the braking force of the wheel brakes (BA, BB) mounted on the wheels, and to prevent the wheels from falling into a locked state when the wheel brakes (BA, BB) are operated. Brake control means (30) for controlling the operation of the brake actuator (5) by switching between at least a decreasing mode for decreasing the braking force of the wheel brakes (BA, BB) and an increasing mode for increasing the braking force. In the vehicle anti-lock brake control device, the wheel speed detection means (25A) for detecting the wheel speed, the vehicle body speed detection means (28) for detecting the vehicle body speed, and the vehicle body speed detection means (28) are detected. Target wheel speed calculation means (29) for calculating a target wheel speed based on the vehicle body speed, Based on the wheel speed detected by the wheel speed detecting means (25A) and the deviation of the target wheel speed calculated by the target wheel speed calculating means (29), the control means (30) is used for wheel braking (BA, BB). In the increase mode, the target value is determined as the target brake force, and in the decrease mode, the target brake force determined in the previous calculation cycle and the current calculation cycle are calculated. The vehicle anti-lock is characterized in that the lower one of the target values is set as a target brake force, and the brake actuator (5) is controlled so that the wheel brake (BA, BB) exhibits the target brake force. Brake control device.

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