JP2019156347A - Brake control device for vehicle - Google Patents

Abstract

To provide a vehicle brake control device capable of accurately identifying defect of a front wheel brake lineage.SOLUTION: A brake control device comprises: a liquid pressure modulator for adjusting a brake liquid pressure; a liquid pressure sensor for detecting liquid pressure of a master cylinder as a master cylinder liquid pressure Pm; a wheel speed sensor for detecting wheel speed of a vehicle; deceleration acquisition means for acquiring deceleration Ge, Gx of the vehicle; and a controller for controlling the liquid pressure modulator based on the wheel speed. The controller determines that, the brake lineage related to front wheels is in a defective state, when the deceleration Ge, Gx is less than prescribed deceleration gx when the master cylinder liquid pressure Pm is equal to or greater than prescribed liquid pressure px, and when rear wheel speed Vwr is less than reference speed Vs which is slower than the front wheel speed Vwf by prescribed speed vs.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a braking control device for a vehicle.

  Patent Document 1 states that “the wheel speed of the rear wheel does not exceed the wheel speed of the front wheel during braking” for the purpose of “preventing the braking force of the entire vehicle from being reduced due to the failure of the front wheel brake”. In a vehicle braking force control apparatus having a braking force front / rear distribution means for controlling the braking force of the rear wheels, when the front wheel brake is determined to be in a failed state, the failure determination means for determining the failure of the front wheel brake And a prohibiting unit that prohibits the braking force control of the rear wheels by the braking force front-rear distribution unit ”. Further, Patent Document 1 states that “the failure determination means determines that the front wheel brake has failed when the vehicle deceleration during braking is smaller than a predetermined value” and “the failure determination means It is calculated that the difference between the deceleration of the front wheel and the deceleration of the rear wheel at the time is calculated, and it is determined that the front wheel brake has failed when this difference does not have a maximum value.

  Patent Document 2 states that “behavior stabilization control during turning of the vehicle is in progress and the master cylinder pressure is a predetermined value for the purpose of“ improvement of determination accuracy of front wheel brake system failure determination during rollover suppression control ”. It is determined that there is a risk of failure in the brake system for the front wheels when the vehicle deceleration exceeds the reference determination threshold and the ABS control is not operating on the front wheels. In the failure determination, when the overturning suppression control at the time of turning of the vehicle is performed, the determination threshold compared with the deceleration of the vehicle is made smaller than the reference determination threshold. “Deceleration of the vehicle according to the amount of operation” is described.

  In the device described in Patent Document 1, the failure of the front wheel braking system is determined when the vehicle deceleration is smaller than a predetermined value. However, since the decrease in vehicle deceleration occurs even when the friction coefficient of the road surface is low, it is necessary to distinguish from the situation.

  In the device described in Patent Document 2, the failure of the front wheel braking system is determined as “when the vehicle deceleration is smaller than a reference determination threshold value corresponding to the amount of braking operation performed by the driver. For the failure determination, it is necessary to distinguish whether the brake system that has failed is related to the front wheels or the rear wheels. In particular, in a freight vehicle (also referred to as a “truck”) that loads a load, when a large amount of loads is loaded, the weight of the vehicle increases and the rear wheel load becomes larger than the front wheel load. For this reason, in the loaded vehicle, the ratio of the rear wheel braking force may be larger than that of a general passenger car. From the above viewpoint, it is desired that the failure of the front wheel braking system is accurately identified in the braking control device.

JP-A-8-301092 JP 2014-104834 A

  An object of the present invention is to provide a braking control device that can accurately identify a failure of a front wheel braking system.

  The vehicle braking control apparatus according to the present invention includes a hydraulic pressure modulator (HU) that adjusts the braking hydraulic pressure (Pw), and a fluid that detects the hydraulic pressure of the master cylinder (CM) as a master cylinder hydraulic pressure (Pm). Pressure sensor (PM), wheel speed sensor (VW) for detecting wheel speed (Vw) of the vehicle, and deceleration acquisition means (S130, GE, GX) for acquiring deceleration (Ge, Gx) of the vehicle And a controller (ECU) for controlling the hydraulic modulator (HU) based on the wheel speed (Vw). The vehicle has a braking device (SD) that pumps braking fluid (BF) from a master cylinder (CM) and applies braking fluid pressure (Pw) to the wheel cylinder (CW).

  In the vehicle braking control apparatus according to the present invention, the controller (ECU) is configured such that when the master cylinder hydraulic pressure (Pm) is equal to or higher than a predetermined hydraulic pressure (px), the deceleration (Ge, Gx) is a predetermined deceleration ( gx) and a rear wheel speed (Vwr) that is the wheel speed (Vw) of the rear wheel (WHr) of the vehicle is a front wheel speed (Vw) that is the wheel speed (Vw) of the front wheel (WHf) of the vehicle. The braking system (Rmf, HMf, HWr, CWf) related to the front wheels (WHf) of the braking device (SD) is lost when the speed is less than the reference speed (Vs) that is smaller than the predetermined speed (vs) by Vwf). It is comprised so that it may determine that it is in a state. Further, the controller (ECU) controls the hydraulic modulator to suppress an increase in deceleration slip of the rear wheel (WHr) based on a comparison between the rear wheel speed (Vwr) and the front wheel speed (Vwf). When the braking force distribution control for limiting the increase in the rear wheel hydraulic pressure (Pwr), which is the braking hydraulic pressure for the rear wheel (WHr), is executed via (HU), and the failure state is determined The braking force distribution control is prohibited from being executed.

  According to the above configuration, the occurrence of front wheel failure or rear wheel failure is determined based on the condition of “Pm ≧ px and Ge (or Gx) <gx”. In addition, based on the condition “Vwr <(Vwf−vs)”, it is identified that a failure has occurred in the front wheel braking system. For this reason, the failure of the front wheel braking system can be determined more reliably.

  In the vehicle braking control apparatus according to the present invention, the controller (ECU) is configured to read the “hydraulic modulator so as to suppress lifting of the rear wheel (WHr) of the vehicle based on the deceleration (Ge, Gx) of the vehicle. Lift-up suppression control for limiting an increase in the front wheel hydraulic pressure (Pwf), which is the braking hydraulic pressure with respect to the front wheel (WHf) of the vehicle via (HU), and "the wheel speed of the rear wheel (WHr)" Based on the comparison between the rear wheel speed (Vwr) that is (Vw) and the front wheel speed (Vwf) that is the wheel speed (Vw) of the front wheel (WHf), an increase in deceleration slip of the rear wheel (WHr) is achieved. The braking force distribution control for limiting the increase in the rear wheel hydraulic pressure (Pwr), which is the braking hydraulic pressure for the rear wheel (WHr), is executed via the hydraulic pressure modulator (HU) so as to suppress the braking force distribution control. Then, the controller (ECU) does not execute the lift-up suppression control when the braking device (SD) is in a failure state, and the master cylinder hydraulic pressure (Pm) and the hydraulic pressure modulator The estimated value (Pef) of the front wheel hydraulic pressure (Pwf) is calculated according to the operating state of (HU), the braking force distribution control is executed, and the estimated value (Pef) is the front wheel of the lift-up suppression control. The brake system (Rmf, HMf, HWr, CWf) related to the front wheel (WHf) of the brake device (SD) is in a failed state when the hydraulic pressure (Pwf) is equal to or higher than the upper limit hydraulic pressure (pu). It is configured to determine. The controller (ECU) is configured to end the execution of the braking force distribution control when the failure state is determined.

  According to the above-described configuration, a series of individual algorithms is not necessary for determining the front wheel failure. That is, it is possible to determine the failure of the front wheel braking system by using calculation results such as braking force distribution control, lift-up suppression control, and anti-skid control. For this reason, the memory capacity is reduced in the controller ECU (in particular, the microprocessor MP). Furthermore, since the calculation of the controller ECU is simplified, the processing can be speeded up.

1 is an overall configuration diagram for explaining an embodiment of a vehicle braking control device SC according to the present invention. FIG. It is a control flowchart for demonstrating the 1st process example of a failure determination. It is a functional block diagram for demonstrating the 2nd example of a failure determination. It is a time series diagram for demonstrating the action | operation of the 2nd process example.

<Symbols of components, subscripts at the end of symbols, and movement / movement directions>
In the following description, components, arithmetic processing, signals, characteristics, and values having the same symbol, such as “ECU”, have the same function. The subscripts “i” to “l” attached to the end of the symbol relating to each wheel are generic symbols indicating which of the wheels each relates to. Specifically, “i” indicates a right front wheel, “j” indicates a left front wheel, “k” indicates a right rear wheel, and “l” indicates a left rear wheel. For example, in each of the four wheel cylinders, they are expressed as a right front wheel wheel cylinder CWi, a left front wheel wheel cylinder CWj, a right rear wheel wheel cylinder CWk, and a left rear wheel wheel cylinder CWl. Further, the suffixes “i” to “l” at the end of the symbol can be omitted. When the suffixes “i” to “l” are omitted, each symbol represents a generic name for each of the four wheels. For example, “WH” represents each wheel, and “CW” represents each wheel cylinder.

  The subscripts “f” and “r” attached to the end of various symbols are comprehensive symbols indicating which system the two braking systems are related to. Specifically, “f” indicates a system related to the front wheels, and “r” indicates a system related to the rear wheels. For example, in the two master cylinder fluid paths, they are represented as a front wheel master cylinder fluid path HMf and a rear wheel master cylinder fluid path HMr. Further, the suffixes “f” and “r” at the end of the symbol can be omitted. When the subscripts “f” and “r” are omitted, each symbol represents a generic name for each of the two braking systems. For example, “HM” represents the master cylinder fluid path of each braking system.

<Embodiment of Braking Control Device for Vehicle according to the Present Invention>
An embodiment of a vehicle braking control device SC according to the present invention will be described with reference to the overall configuration diagram of FIG. For example, the vehicle is a freight vehicle (truck) on which luggage is loaded. The vehicle is provided with a braking device SD that pumps the brake fluid BF from the master cylinder CM and applies the brake fluid pressure Pw to the wheel cylinder CW. In the vehicle braking device SD, the master cylinder CM is connected to the wheel cylinder CW via the master cylinder fluid passage HM and the wheel cylinder fluid passage HW. Here, the “fluid path” is a path for moving the brake fluid BF that is the working fluid of the brake device SD and the brake control device SC, and corresponds to a brake pipe, a fluid unit flow path, a hose, and the like. . Each fluid passage is filled with a brake fluid BF. In the fluid path, the side close to the reservoir RV (the side far from the wheel cylinder CW) is called “upstream side” or “upper side”, and the side close to the wheel cylinder CW (the side far from the reservoir RV) It is called “downstream” or “lower”.

  In general vehicles, two fluid paths are employed to ensure redundancy. The front wheel system (system related to the master cylinder chamber Rmf for the front wheels) of the two fluid paths is connected to the front wheel cylinder CWf (= CWi, CWj). Of the two fluid paths, the rear wheel system (the system related to the master cylinder chamber Rmr for the rear wheel) is connected to the rear wheel cylinder CWr (= CWk, CWl). That is, a so-called front and rear type (also referred to as “H type”) is adopted as the two-system fluid path. The failure of the braking device SD occurs due to breakage in the transmission path of the braking fluid BF from the master cylinder CM to the wheel cylinder CW. The failure of the braking device SD is a failure of the front wheel braking system due to damage from the master cylinder CM (in particular, the front wheel master cylinder chamber Rmf) to the front wheel cylinder CWf (also simply referred to as “front wheel failure”). ) And a failure of the rear wheel braking system due to damage from the master cylinder CM (in particular, the rear wheel master cylinder chamber Rmr) to the rear wheel cylinder CWr (also simply referred to as “rear wheel failure”). Exists.

  A vehicle including the braking control device SC includes a braking operation member BP, a wheel cylinder CW, a reservoir RV, a master cylinder CM, and a brake booster BB. The braking operation member (for example, brake pedal) BP is a member that the driver operates to decelerate the vehicle. By operating the braking operation member BP, the braking torque Tq of the wheel WH is adjusted, and a braking force is generated on the wheel WH.

  A rotating member (for example, a brake disc) KT is fixed to the wheel WH of the vehicle. A brake caliper is arranged so as to sandwich the rotating member KT. The brake caliper is provided with a wheel cylinder CW. By increasing the pressure (braking fluid pressure) Pw of the brake fluid BF in the wheel cylinder CW, the friction member (for example, a brake pad) is pressed against the rotating member KT. Since the rotating member KT and the wheel WH are fixed so as to rotate integrally, a braking torque Tq is generated in the wheel WH by the frictional force generated at this time. This braking torque Tq causes a deceleration slip on the wheel WH, resulting in a braking force. The braking device SD is a so-called disc type (disc brake).

  Instead of the disc type braking device SD, a drum type braking device (drum brake) SD may be employed. In the case of a drum brake, a brake drum is employed instead of the caliper. The friction member is a brake shoe, and the rotating member is a brake drum.

  The reservoir (atmospheric pressure reservoir) RV is a tank for working fluid, and the brake fluid BF is stored therein. The interior of the atmospheric pressure reservoir RV is divided into two parts by a partition plate SK. The front wheel master reservoir chamber Ruf is connected to the front wheel master cylinder chamber Rmf, and the rear wheel master reservoir chamber Rur is connected to the rear wheel master cylinder chamber Rmr.

  The master cylinder CM is mechanically connected to the braking operation member BP via a brake rod, a clevis (U-shaped link) or the like. The master cylinder CM is a tandem type, and the interior thereof is divided into front wheel and rear wheel master cylinder chambers Rmf and Rmr by first and second master pistons PA and PB. When the brake operation member BP is not operated, the front wheels and rear wheel master cylinder chambers Rmf and Rmr of the master cylinder CM and the reservoir RV (front wheels and rear wheel master reservoir chambers Ruf and Rur) are in communication with each other. The master cylinder CM receives the supply of the brake fluid BF from the reservoir RV and generates front and rear wheel master cylinder fluid pressures Pmf and Pmr. Front wheel and rear wheel master cylinder fluid passages HMf and HMr are connected to the master cylinder CM.

  When the braking operation member BP is operated, the first and second master pistons PA and PB in the master cylinder CM are pushed and moved forward. By this advance, the master cylinder chamber Rm is disconnected from the reservoir RV (particularly, the master reservoir chamber Ru). When the operation of the brake operation member BP is increased, the volume of the master cylinder chamber Rm decreases, and the brake fluid BF is pumped from the master cylinder CM toward the wheel cylinder CW.

  The brake booster (simply referred to as “booster”) BB reduces the operating force Fp of the braking operation member BP by the driver. A negative pressure type is used as the booster BB. The negative pressure is formed by an engine or an electric negative pressure pump. As the booster BB, an electric motor as a drive source may be employed (for example, an electric booster or an accumulator hydraulic booster).

The vehicle further includes a wheel speed sensor VW, a steering angle sensor SA, a yaw rate sensor YR, a deceleration sensor GX, a lateral acceleration sensor GY, a braking operation amount sensor BA, and an operation switch ST.
Each wheel WH of the vehicle is provided with a wheel speed sensor VW so as to detect the wheel speed Vw. The signal of the wheel speed Vw is used for independent control in each wheel such as anti-skid control for suppressing the tendency of the wheel WH to lock (that is, excessive deceleration slip).

  A steering operation member (for example, a steering wheel) is provided with a steering angle sensor SA so as to detect the steering angle Sa. The vehicle body is provided with a yaw rate sensor YR so as to detect a yaw rate (yaw angular velocity) Yr. In addition, the deceleration sensor GX and the lateral sensor so as to detect the acceleration (deceleration) Gx in the longitudinal direction (traveling direction) of the vehicle and the acceleration (lateral acceleration) Gy in the lateral direction (direction perpendicular to the traveling direction). An acceleration sensor GY is provided. These signals are used for vehicle motion control such as vehicle stabilization control (so-called ESC) that suppresses excessive oversteer behavior and understeer behavior.

  A braking operation amount sensor BA is provided so as to detect an operation amount Ba of the braking operation member BP (brake pedal) by the driver. As the brake operation amount sensor BA, a master cylinder hydraulic pressure sensor PM that detects a hydraulic pressure (master cylinder hydraulic pressure) Pm in the master cylinder CM, an operation displacement sensor SP that detects an operation displacement Sp of the brake operation member BP, and a brake At least one of the operation force sensors FP that detects the operation force Fp of the operation member BP is employed. That is, the operation amount sensor BA detects at least one of the master cylinder hydraulic pressure Pm, the operation displacement Sp, and the operation force Fp as the braking operation amount Ba.

  The brake operation member BP is provided with an operation switch ST. The operation switch ST detects whether the driver has operated the braking operation member BP. When the brake operation member BP is not operated (that is, during non-braking), the brake operation switch ST outputs an off signal as the operation signal St. On the other hand, when the braking operation member BP is operated (that is, during braking), an ON signal is output as the operation signal St. The wheel speed Vw, the steering angle Sa, the yaw rate Yr, the vehicle deceleration Gx, the lateral acceleration Gy, the braking operation amount Ba, and the braking operation signal St detected by each sensor (VW or the like) are input to the controller ECU. In the controller ECU, the vehicle body speed Vx is calculated based on the wheel speed Vw.

≪Electronic control unit ECU≫
The braking control device SC includes a controller ECU and a hydraulic pressure modulator (also referred to as “fluid unit”) HU. The controller (also referred to as “electronic control unit”) ECU is composed of an electric circuit board on which a microprocessor MP and the like are mounted, and a control algorithm programmed in the microprocessor MP. The controller ECU is connected to the network so as to share signals (detected values, calculated values, etc.) with other controllers via the in-vehicle communication bus BS.

  A controller ECU (electronic control unit) controls the electric motor ML of the hydraulic pressure modulator HU and three different types of electromagnetic valves UP, VI, and VO. Specifically, drive signals Up, Vi, and Vo for controlling various electromagnetic valves UP, VI, and VO are calculated based on a control algorithm in the microprocessor MP. Similarly, a drive signal Ml for controlling the electric motor ML is calculated.

  The controller ECU is provided with a drive circuit DR so as to drive the electromagnetic valves UP, VI, VO and the electric motor ML. In the drive circuit DR, a bridge circuit is formed by switching elements (power semiconductor devices such as MOS-FET and IGBT) so as to drive the electric motor ML. Based on the motor drive signal Ml, the energization state of each switching element is controlled, and the output of the electric motor ML is controlled. In the drive circuit DR, the energized states (that is, the excited states) are controlled by the switching elements based on the drive signals Up, Vi, and Vo so as to drive the electromagnetic valves UP, VI, and VO. The drive circuit DR is provided with an energization amount sensor that detects the actual energization amounts of the electric motor ML and the electromagnetic valves UP, VI, and VO. For example, a current sensor is provided as an energization amount sensor, and currents supplied to the electric motor ML and the electromagnetic valves UP, VI, and VO are detected.

  A braking operation amount Ba (= Pm, Sp, Fp), a braking operation signal St, a wheel speed Vw, a yaw rate Yr, a steering angle Sa, a deceleration Gx, a lateral acceleration Gy, and the like are input to the controller ECU. For example, in the controller ECU, the anti-skid control is executed based on the wheel speed Vw so as to suppress excessive deceleration slip (for example, wheel lock) of the wheel WH. The controller ECU executes vehicle stabilization control (so-called ESC) that suppresses unstable behavior (excessive oversteer behavior, understeer behavior) of the vehicle based on the actual yaw rate Yr and the like.

≪Hydraulic modulator HU≫
A hydraulic pressure modulator HU is connected to the front wheel and rear wheel master cylinder fluid passages HMf and HMr. At portions Bwf and Bwr in the hydraulic pressure modulator HU, the master cylinder fluid passages HMf and HMr are branched into wheel cylinder fluid passages HWi to HWl and connected to the wheel cylinders CWi to CWl. Specifically, the front wheel master cylinder fluid passage HMf is branched to the front wheel wheel cylinder fluid passages HWi and HWj at the branch portion Bwf and connected to the front wheel wheel cylinders CWi and CWj. Similarly, the rear wheel master cylinder fluid passage HMr is branched into the wheel cylinder fluid passages HWk and HWl at the branch portion Bwr, and the rear wheel wheel cylinders CWk and CWl are connected.

  The hydraulic pressure modulator HU includes an electric pump DL, a low pressure reservoir RL, a pressure regulating valve UP, a master cylinder hydraulic pressure sensor PM, an inlet valve VI, and an outlet valve VO. The electric pump DL is configured by one electric motor ML and two fluid pumps QLf and QLr. Electric motor ML is controlled by controller ECU based on drive signal Ml. The front wheel and rear wheel fluid pumps QLf and QLr are integrally rotated and driven by the electric motor ML. The brake fluid BF is pumped from the upstream portions Bsf and Bsr of the front and rear wheel pressure regulating valves UPf and UPr by the fluid pump QL. The brake fluid BF pumped up is discharged to the downstream portions Btf and Btr of the pressure regulating valve UP. Here, the electric pump DL is rotated only in one direction. Front and rear wheel low pressure reservoirs RLf and RLr are provided on the suction side of the fluid pump QL.

  A pressure regulating valve UP is provided in the master cylinder fluid passage HM. As the pressure regulating valve UP, a linear solenoid valve (also referred to as “proportional valve” or “differential pressure valve”) whose valve opening amount (lift amount) is continuously controlled based on an energized state (for example, supply current). Is adopted. The pressure regulating valve UP is controlled by the controller ECU based on the drive signal Up. The energization amount (current) to the pressure regulating valve UP is adjusted according to the drive signal Up, and the valve opening amount of the pressure regulating valve UP is adjusted. A normally open solenoid valve is employed as the pressure regulating valve UP.

  In the upstream portion of the pressure regulating valve UP, front wheel and rear wheel master cylinder fluid pressure sensors PMf and PMr are provided so as to detect front wheel and rear wheel master cylinder fluid pressures Pmf and Pmr. Since “Pmf = Pmr”, one of the front wheel master cylinder hydraulic pressure sensor PMf and the rear wheel master cylinder hydraulic pressure sensor PMr can be omitted. Note that when the hydraulic pressure modulator HU (particularly, the solenoid valves UP, VI, and VO) is inactive, the master cylinder hydraulic pressure Pm and the wheel cylinder hydraulic pressure (braking hydraulic pressure) Pw coincide.

  The master cylinder fluid passage HM is branched (divided) into each front wheel cylinder fluid passage HW at a branch portion Bw downstream of the pressure regulating valve UP. The wheel cylinder fluid path HW is provided with an inlet valve VI and an outlet valve VO. As the inlet valve VI, a normally open type on / off solenoid valve is employed. Further, a normally closed on / off solenoid valve is employed as the outlet valve VO. Here, the on / off solenoid valve is a two-port two-position switching type solenoid valve having two positions of an open position and a closed position. The solenoid valves VI and VO are controlled by the controller ECU based on the drive signals Vi and Vo. The brake hydraulic pressure Pw of each wheel can be independently controlled by the inlet valve VI and the outlet valve VO.

  In the inlet valve VI and the outlet valve VO, the configuration relating to each wheel WH is the same. A normally open inlet valve VI is provided in the wheel cylinder fluid passage HW (the fluid passage connecting the portion Bw and the wheel cylinder CW). The wheel cylinder fluid passage HW is connected to the low pressure reservoir RL via a normally closed outlet valve VO at a downstream portion of the inlet valve VI. For example, in the brake control independent of each wheel, the inlet valve VI is closed and the outlet valve VO is opened to reduce the hydraulic pressure Pw in the wheel cylinder CW. The inflow of the brake fluid BF from the inlet valve VI is blocked, the brake fluid BF in the wheel cylinder CW flows out to the low pressure reservoir RL, and the brake fluid pressure Pw is decreased. The brake fluid BF that has flowed into the low-pressure reservoir RL is returned to the upstream portion Bt of the inlet valve VI by the electric pump DL. On the other hand, in order to increase the brake fluid pressure Pw, the inlet valve VI is opened and the outlet valve VO is closed. The brake fluid BF is prevented from flowing out to the low pressure reservoir RL, and the hydraulic pressure adjusted by the pressure regulating valve UP is introduced into the wheel cylinder CW, and the brake hydraulic pressure Pw is increased. In order to maintain the brake fluid pressure Pw, the inlet valve VI and the outlet valve VO are both closed, and the brake fluid BF in the wheel cylinder CW is not moved.

<First determination example of front wheel failure>
With reference to the control flowchart of FIG. 2, a first processing example of front wheel failure determination will be described. This process is programmed in the controller ECU. In step S110, the wheel speed Vw, the master cylinder hydraulic pressure Pm, and the vehicle deceleration Gx are read. The wheel speed Vw, the master cylinder hydraulic pressure Pm, and the deceleration Gx are detected by the wheel speed sensor VW, the master cylinder hydraulic pressure sensor PM, and the deceleration sensor GX, and are input to the controller ECU.

  In step S120, the vehicle body speed Vx is calculated based on the wheel speed Vw. For example, at the time of non-braking including acceleration of the vehicle, the vehicle body speed Vx is calculated based on the slowest (latest wheel speed) of the four wheel speeds Vw. Further, at the time of braking, the vehicle body speed Vx is calculated based on the fastest (fastest wheel speed) of the four wheel speeds Vw. Furthermore, in the calculation of the vehicle body speed Vx, a limit can be set in the amount of change with time. That is, the upper limit value aup of the increase gradient of the vehicle body speed Vx and the lower limit value adn of the decrease gradient are set, and the change of the vehicle body speed Vx is restricted by the upper and lower limit values aup and adn.

  In step S130 (corresponding to “deceleration acquisition means”), the actual vehicle deceleration Ge is calculated based on the vehicle body speed Vx. Specifically, the vehicle body speed Vx is differentiated with respect to time, and an actual deceleration (actual deceleration) Ge is calculated. In step S140, the reference speed Vs is calculated. The reference speed Vs is a value serving as a reference for determining failure of the front wheel braking system. Specifically, the predetermined speed vs is subtracted from the front wheel speed Vwf, and the reference speed Vs is calculated. Accordingly, the reference speed Vs is a value smaller than the front wheel speed Vwf by a predetermined speed vs. Here, the predetermined speed vs is a preset constant (predetermined value).

  In step S150, based on the master cylinder hydraulic pressure Pm and the deceleration Ge (calculated value), “whether one of the front wheel braking system and the rear wheel braking system has failed or not. Is determined. Specifically, based on the relationship between the master cylinder hydraulic pressure Pm and the deceleration Ge, based on the condition that “the master cylinder hydraulic pressure Pm is greater than or equal to px and the deceleration Ge is less than the predetermined deceleration gx”. Determined. When “Pm ≧ px and Ge <gx”, the above-described failure state is determined. Here, the predetermined hydraulic pressure px and the predetermined deceleration gx are predetermined values (constants) set in advance. If step S150 is negative, the process returns to step S110. On the other hand, if step S150 is positive, the process proceeds to step S160.

  The determination in step S150 will be described with reference to the characteristic diagram of block X150. In this determination, a region indicated by “Pm ≧ px” and “Ge <gx” is a failure determination region (see the hatched portion). As the master cylinder hydraulic pressure Pm increases, the braking torque Tq increases and the vehicle deceleration Ge increases. The characteristic Ca corresponds to the case where no failure has occurred. The increase characteristic Ca of the deceleration Ge accompanying the increase in the master cylinder hydraulic pressure Pm does not enter the failure determination region. For this reason, when the braking device SD is in an appropriate state (when no failure has occurred), the determination in step S150 is negative. On the other hand, the characteristic Cb corresponds to a case where any one of the front wheel braking system and the rear wheel braking system has failed. In this case, the increase characteristic Cb of the deceleration Ge accompanying the increase in the master cylinder hydraulic pressure Pm enters the failure determination region. At the time of entering the region (calculation cycle), the determination in step S150 is affirmed, and the failure state is determined.

  In step S160, based on the rear wheel speed Vwr and the reference speed Vs, it is determined whether or not a failure has occurred in the front wheel braking system. Specifically, based on “whether or not the rear wheel speed Vwr is less than the reference speed Vs”, the failure of the front wheel braking system (front wheel failure) is determined. If “Vwr ≧ Vs” and step S160 is negative, the process returns to step S110. In this case, the rear wheel braking system has failed (rear wheel failure). If “Vwr <Vs” and step S160 is affirmed, the failure state of the front wheel braking system is determined.

  The determination in step S160 will be described with reference to the time series diagram of block X160. The braking force is generated by wheel deceleration slip (difference between wheel speed Vw and vehicle speed Vx). Therefore, no braking force is generated on the wheels related to the braking system in which a failure occurs, and no deceleration slip occurs. On the other hand, a deceleration slip is generated and a braking force acts on a wheel related to an appropriate braking system. That is, when the front wheel braking system has failed, the deceleration slip of the front wheel WHf is small and the deceleration slip of the rear wheel WHr is large (that is, the relationship of “Vwr <Vx (= Vwf)” is established). From the above, at the operation start time t0 of the braking operation member BP, the predetermined speed vs (predetermined constant) is subtracted from the front wheel speed Vwf to calculate the reference speed Vs as a reference for the failure determination. (Ie, “Vs = Vwf−vs”). As the braking operation increases, the rear wheel deceleration slip increases, but if “Vwr ≧ Vs”, the front wheel failure is denied. Then, when “Vwr <Vs” at time t1 (corresponding calculation cycle), the front wheel failure is determined.

  In step S170, execution of the braking force distribution control is prohibited. If the execution of the braking force distribution control has already been started, the control is terminated. In the braking force distribution control, based on the comparison between the front wheel speed Vwf and the rear wheel speed Vwr, the rear wheel hydraulic pressure Pwr (the hydraulic pressure of the rear wheel wheel cylinder CWr) is controlled so as to suppress excessive deceleration slip of the rear wheel WHr. Increase is limited. That is, the braking force distribution control limits the braking force of the rear wheel WHr. Details of the braking force distribution control will be described later with reference to FIG. When the front wheel failure is determined, the execution of the braking force distribution control is prohibited (or terminated), so that the rear wheel braking force is secured and sufficient vehicle deceleration is obtained.

  In the above example, the vehicle body speed Vx is differentiated to determine the deceleration Ge. Instead of the deceleration Ge, a deceleration Gx detected by a deceleration sensor GX (corresponding to “deceleration acquisition means”) may be employed. Further, both the deceleration Gx (detected value) and the deceleration Ge (calculated value) may be used for the determination so as to improve the robustness.

  Based on the mutual relationship between the master cylinder hydraulic pressure Pm and the vehicle deceleration (actual values) Ge and Gx, the failure of the braking device SD (occurrence of front wheel failure or rear wheel failure) is determined. Based on the deceleration slip of the wheel, it is specified (identified) that a failure has occurred in the front wheel braking system. Thereby, the front wheel failure can be determined more reliably.

<Second determination example of front wheel failure>
With reference to the functional block diagram of FIG. 3, a second processing example of front wheel failure determination will be described. In the second example, the brake control device SC includes lift-up suppression control, and a braking force distribution control signal Fe (for example, an operation flag) is used for determining the failure of the front wheel braking system. That is, individual determination processing is not performed, but the processing signal of each control already included in the braking control device SC is used to determine front wheel failure.

  As described above, components, operations, signals, characteristics, and values that have the same symbols are of the same function. In the suffixes “i” to “l” at the end of the symbols relating to the wheels, “i” indicates the right front wheel, “j” indicates the left front wheel, “k” indicates the right rear wheel, and “l” indicates the left rear wheel. The subscripts “i” to “l” may be omitted. In this case, each symbol represents a generic name for each of the four wheels. In addition, suffixes “f” and “r” at the end of the symbols related to the braking system indicate that “f” is the front wheel system and “r” is the rear wheel system. The subscripts “f” and “r” may be omitted. In this case, each symbol represents a generic name of the two braking systems.

  The braking control device SC (particularly, the controller ECU) includes a lift-up suppression control block LC and a braking force distribution control block HC. In the lift-up suppression control block LC, lift-up suppression control is executed. The lift-up suppression control is a control that suppresses lifting of the rear wheel WHr during braking. Specifically, in the lift-up suppression control, the rear wheel lift-up state is determined based on the vehicle deceleration Ge (or Gx) and the deceleration change amount dG, and the braking force of the front wheels WHf is suppressed. .

The lift-up suppression control block LC includes a vehicle body speed calculation block VX, a deceleration calculation block GE, a change amount calculation block DG, a threshold value calculation block GS, a lift-up determination block LA, and a front wheel hydraulic pressure suppression block LB. Is done.
In the vehicle body speed calculation block VX, the vehicle body speed Vx is calculated based on the wheel speed Vw by the same method as in step S120. In the deceleration calculation block GE (corresponding to “deceleration acquisition means”), the deceleration Ge is calculated based on the vehicle speed Vx in the same manner as in step S130 (that is, the deceleration Ge is calculated based on the vehicle speed Vx). (Refer to FIG. 2). In the change amount calculation block DG, the time change amount dG of the deceleration Ge is calculated based on the deceleration Ge. Specifically, the vehicle deceleration Ge is differentiated with respect to time, and the deceleration change amount dG is calculated.

  In the threshold calculation block GS, the threshold deceleration Gs is calculated based on the deceleration change amount dG and the calculation map Zgs. The threshold deceleration Gs is a threshold value for determining the start of the lift-up suppression control. According to the calculation map Zgs, the threshold deceleration Gs is determined to be smaller as the deceleration change amount dG is larger. An upper limit value ga and a lower limit value gb are set for the threshold deceleration Gs.

  In the lift-up determination block LA, the start of the lift-up suppression control is determined based on the deceleration change amount dG, the deceleration Ge, and the threshold deceleration Gs. Specifically, when the condition that “the deceleration change amount dG is greater than or equal to the predetermined change amount dx and the deceleration Ge is greater than or equal to the threshold deceleration Gs” is satisfied, the lift-up suppression control is executed. . That is, when at least one of “dG <dx” and “Ge <Gs” is satisfied, the execution is not started, and when “dG ≧ dx and Ge ≧ Gs” is satisfied. Control is started. Here, the predetermined change amount dx is a preset constant (predetermined value).

  Instead of the deceleration Ge, a deceleration Gx can be adopted. Here, the deceleration Gx is detected by a deceleration sensor GX (deceleration acquisition means). Both the deceleration Gx (detected value) and the deceleration Ge (calculated value) may be used for the determination.

  When the start of control execution is determined in the lift-up determination block LA, the front wheel hydraulic pressure suppression block LB limits the front wheel hydraulic pressure Pwf (the hydraulic pressure of the front wheel wheel cylinder CWf). Specifically, in response to an execution command from the lift-up determination block LA, a signal for driving the inlet valve VIf (= VIi, VIj) for the front wheel WHf to the closed position from the front wheel hydraulic pressure suppression block LB to the drive circuit DR. Is sent. As the front wheel inlet valve VIf is repeatedly opened and closed, the actual pressure increase speed of the front wheel hydraulic pressure Pwf (braking fluid) is higher than the pressure increasing gradient corresponding to the operation of the braking operation member BP. The pressure increase restriction is performed so that the time gradient in the increase in pressure is also reduced.

  For example, the pressure increase speed is adjusted by the duty ratio of the front wheel inlet valve VIf. Here, the “duty ratio” is a ratio of energization time (on time) per unit time. Since the front wheel inlet valve VIf is a normally open solenoid valve, “0%” of the duty ratio corresponds to the normally open state, and “100% (normally energized)” corresponds to the normally closed state. Accordingly, the duty ratio of the front wheel inlet valve VIf is determined to be a value larger than “0%”, and the pressure increasing gradient of the front wheel hydraulic pressure Pwf is adjusted. Further, when the front wheel hydraulic pressure Pwf reaches the upper limit value pu of the lift-up suppression control, the front wheel hydraulic pressure Pwf is limited so as not to exceed the upper limit hydraulic pressure pu. Here, the upper limit hydraulic pressure pu is a preset constant (predetermined value). Lifting up of the rear wheel WHr is suppressed by lift-up suppression control that restricts an increase in the front wheel hydraulic pressure Pwf by the hydraulic pressure modulator HU based on the vehicle deceleration Ge, Gx.

  When at least one of the threshold value (predetermined change amount) dx and the calculation map Zgs related to the execution determination of the lift-up suppression control has a failure in either the front wheel system or the rear wheel system ( That is, it is set so that the control is not executed when the braking device SD has failed (also referred to as “braking failure”). For example, the predetermined value dx is set so that the deceleration change amount dG does not become equal to or greater than the predetermined change amount dx (determination threshold value) when braking fails. Alternatively, the lower limit gb is set so that the deceleration Ge, Gx at the time of braking failure at “Pm = pu” is less than the lower limit gb of the calculation map Zgs (calculation characteristic of the threshold deceleration Gs). Therefore, the lift-up suppression control is not executed when braking fails.

  In the braking force distribution control block HC, braking force distribution control (also simply referred to as “distribution control”) is executed. In the distribution control, the front wheel speed Vwf and the rear wheel speed Vwr are compared, and based on the comparison result, the rear wheel hydraulic pressure Pwr is limited so that the deceleration slip of the rear wheel WHr does not increase. As a result of the braking force of the rear wheel WHr being suppressed, the lateral force of the front wheel WHf is ensured and the stability of the vehicle is improved. The braking force distribution control block HC includes a rear wheel slip determination block EA and a rear wheel hydraulic pressure suppression block EB.

  In the rear wheel slip determination block EA, it is determined based on the wheel speed Vw whether or not the deceleration slip of the rear wheel WHr is excessive. For example, in this determination, the predetermined speed ve is subtracted from the front wheel speed Vwf to calculate the threshold speed Ve (that is, “Ve = Vwf−ve”). The threshold speed Ve is a value serving as a reference for execution of distribution control, and the predetermined speed ve is a preset constant (predetermined value). When the rear wheel speed Vwr is equal to or higher than the threshold speed Ve, the distribution control is not executed. The distribution control is started when the rear wheel speed Vwr becomes lower than the threshold speed Ve (calculation cycle). That is, in the distribution control, an excessive decrease in the rear wheel speed Vwr (that is, an increase in the rear wheel deceleration slip) is suppressed based on the comparison between the front wheel speed Vwf and the rear wheel speed Vwr.

  From the rear wheel slip determination block EA, an operation flag Fe indicating the execution state of the braking force distribution control is output. The operation flag Fe is set to “0” when the distribution control is not executed, and is set to “1” when the distribution control is executed. Therefore, the operation flag Fe is switched from “0” to “1” at the start time (calculation cycle) of the distribution control.

  In response to the execution command from the rear wheel slip determination block EA, a signal for driving the inlet valve VIr (= VIk, VIl) related to the rear wheel WHr to the closed position is transmitted from the rear wheel hydraulic pressure suppression block EB to the drive circuit DR. Is done. By periodically repeating the open position and the closed position in the rear wheel inlet valve VIr, the actual pressure increase gradient of the rear wheel hydraulic pressure Pwr is greater than the pressure increase gradient corresponding to the operation of the braking operation member BP. The pressure increase is limited such that the rear wheel hydraulic pressure Pwr is maintained at a constant hydraulic pressure.

  Similar to the front wheel inlet valve VIf, the pressure increasing speed (pressure increasing gradient) is adjusted by the duty ratio of the rear wheel inlet valve VIr (ratio of energization time per unit time). Since the rear wheel inlet valve VIr is also a normally open type electromagnetic valve, the duty ratio of the rear wheel inlet valve VIr is determined to be larger than “0%”, and the pressure increase gradient of the rear wheel hydraulic pressure Pwr is adjusted. . For example, the duty ratio of the rear wheel inlet valve VIr is determined to be “100%”, and the rear wheel hydraulic pressure Pwr is maintained (that is, the pressure increasing speed is “0”). The rear wheel speed Vwr does not become lower than the front wheel speed Vwf by exceeding the predetermined speed ve (that is, the rear wheel speed Vwr does not become less than the value Ve obtained by subtracting the predetermined speed ve from the front wheel speed Vwf). Braking force distribution control for limiting an increase in the rear wheel hydraulic pressure Pwr is executed by the modulator HU. By this control, the generation of the braking force of the rear wheel WHr is suppressed, and the lateral force is ensured. As a result, vehicle stability can be improved.

  For example, the execution block of anti-skid control that suppresses excessive deceleration slip (for example, wheel lock) of the wheel WH includes a hydraulic pressure estimation calculation block PE. In the hydraulic pressure estimation calculation block PE, based on the master cylinder hydraulic pressure Pm and the operating state of the hydraulic pressure modulator HU (that is, the driving state of the inlet valve VI and outlet valve VO in the driving circuit DR), The estimated hydraulic pressure Pe is calculated.

  In the front wheel failure determination block HN, a failure (front wheel failure) of the front wheel braking system is determined based on the operation flag Fe and the estimated hydraulic pressure Pe (particularly, the estimated front wheel hydraulic pressure Pef). Specifically, when the braking force distribution control is being executed (in the state of “Fe = 1”), the front wheel estimated hydraulic pressure Pef (corresponding to “estimated value”) reaches the upper limit hydraulic pressure pu. The front wheel failure is determined. The execution of the braking force distribution control means that a braking force is generated on the rear wheels. Further, when no failure has occurred in the braking device SD, lift-up suppression control is executed, and the front wheel braking hydraulic pressure Pwf should be limited. However, when the estimated front wheel hydraulic pressure Pef reaches the upper limit hydraulic pressure pu of the lift-up suppression control, the lift-up suppression control is not executed, and thus there is a failure in the braking device SD (that is, two braking systems). The occurrence of a failure in one of the systems) is determined. That is, based on the fact that “rear wheel braking force is generated (information from distribution control)” and “braking failure has occurred (information from lift-up suppression control)”, front wheel braking is performed. System failure is determined.

  When the front wheel failure determination block HN determines that the rear wheel braking system has failed (front wheel failure), the rear wheel slip determination block EA indicates that control is prohibited (prohibition). Signal) is transmitted. In response, the braking force distribution control block HC ends the execution of the braking force distribution control. Since the restriction of the rear wheel braking force is released, the vehicle deceleration can be improved.

  In the second determination example, the individual determination algorithm (see FIG. 2) is not adopted, and the failure of the front wheel braking system is determined based on the calculation results of the braking force distribution control, the lift-up suppression control, and the anti-skid control. Is determined. For this reason, in the controller ECU (particularly, the microprocessor MP) of the braking control device SC, the memory capacity can be reduced and the calculation processing speed can be improved.

<Operation of Second Determination Example>
The operation of the second determination example will be described with reference to the time series diagram of FIG. The diagram assumes a vehicle with a front wheel failure.

  At the time point u0, the operation of the braking operation member BP is started, and the increase in the master cylinder hydraulic pressure Pm is started. The estimated hydraulic pressure Pe is calculated based on the master cylinder hydraulic pressure Pm and the operating state of the hydraulic pressure modulator HU (particularly, the inlet valve VI and the outlet valve VO). For example, the calculation of the estimated hydraulic pressure Pe is included in the anti-skid control. When the lift-up suppression control is not executed, the front wheel inlet valve VIf is normally open (non-energized), and thus the estimated front wheel hydraulic pressure Pef and the master cylinder hydraulic pressure Pm coincide.

  During braking, the threshold speed Ve is determined by subtracting the predetermined speed ve from the front wheel speed Vwf for execution of the braking force distribution control. As the master cylinder hydraulic pressure Pm increases, the vehicle deceleration Ge (or Gx) increases. However, because of the failure of the front wheels, vehicle deceleration is based only on the rear wheel braking force. Accordingly, the increase in the deceleration Ge is small as compared with the normal state of the braking device SD indicated by the broken line.

  At the time point u1, the rear wheel speed Vwr becomes lower than the threshold speed Ve, and execution of the braking force distribution control is started. Thereby, the operation flag Fe of the braking force distribution control is changed from “0” to “1”. By executing the braking force distribution control, an increase in the rear wheel hydraulic pressure Pwr is limited, and a decrease in the rear wheel speed Vwr (that is, an increase in deceleration slip of the rear wheel WHr) is suppressed. At the time point u2, the front wheel estimated hydraulic pressure Pef becomes equal to or higher than the upper limit hydraulic pressure pu, and the front wheel failure is determined. According to the determination result, the braking force distribution control is terminated at time point u2.

<Action and effect>
Hereinafter, actions and effects of the braking control device SC according to the present invention will be summarized.
The vehicle (for example, a cargo-carrying vehicle) has a braking device SD that pumps the brake fluid BF from the master cylinder CM and applies the brake fluid pressure Pw to the wheel cylinder CW. The braking device SD has two braking systems, one braking system is connected to the front wheel cylinder CWf, and the other braking system is connected to the rear wheel cylinder CWr (that is, a braking device for front and rear pipes). SD). The braking control device SC according to the present invention is provided in the vehicle. The braking controller SC includes a hydraulic pressure modulator HU that adjusts the braking hydraulic pressure Pw, a hydraulic pressure sensor PM that detects the hydraulic pressure of the master cylinder CM as the master cylinder hydraulic pressure Pm, and a wheel speed that detects the vehicle wheel speed Vw. A sensor VW, deceleration acquisition means S130, GE, GX for acquiring vehicle deceleration Ge, Gx, and a controller ECU for controlling the hydraulic pressure modulator HU based on the wheel speed Vw.

In the controller ECU, when the following two conditions are satisfied, the braking system related to the front wheel WHf of the braking device SD is in a failed state (for example, the front wheel master cylinder chamber Rmf, the front wheel fluid paths HMf, HWf, and A failure of at least one of the front wheel cylinders CWf) is determined.
Condition A (Condition regarding the mutual relationship between the master cylinder hydraulic pressure Pm and the deceleration Ge, Gx):
The master cylinder hydraulic pressure Pm is equal to or higher than the predetermined hydraulic pressure px, and the decelerations Ge and Gx are less than the predetermined deceleration gx.
Condition B (Conditions related to wheel deceleration slip):
The wheel speed (rear wheel speed) Vwr of the rear wheel WHr is less than the reference speed Vs which is smaller than the wheel speed (front wheel speed) Vwf of the front wheel WHf by a predetermined speed vs.

  Based on the condition A, the occurrence of a front wheel failure or a rear wheel failure is determined, and based on the condition B, it is identified that a failure has occurred in the front wheel braking system. For this reason, the failure of the front wheel braking system can be determined more reliably.

In the braking control device SC, lift-up suppression control and braking force distribution control are executed.
In the lift-up suppression control, an increase in the front wheel braking hydraulic pressure (hydraulic pressure in the front wheel cylinder CWf) Pwf is limited (suppressed) based on the vehicle deceleration Ge and Gx so as to suppress the lifting of the rear wheel WHr. In the lift-up suppression control, a threshold value, a calculation map, and the like are set so as not to be executed when a failure of the braking device SD occurs.

  In the braking force distribution control, the rear wheel braking hydraulic pressure (hydraulic pressure of the rear wheel wheel cylinder CWr) Pwr is controlled so that the increase in the rear wheel deceleration slip is suppressed according to the comparison result between the front wheel speed Vwf and the rear wheel speed Vwr. Is limited (suppressed). For example, in the braking force distribution control, the rear wheel hydraulic pressure Pwr is limited so that the rear wheel speed Vwr does not become less than a value (threshold speed) Ve that is smaller than the front wheel speed Vwf by a predetermined speed ve.

In the controller ECU, when the following two conditions are satisfied, the braking system (for example, the front wheel master cylinder chamber Rmf, the front wheel fluid passages HMf, HWf, and the front wheel wheel cylinder CWf) related to the front wheel WHf of the braking device SD has failed. It is determined that
Condition C (conditions relating to braking force distribution control):
The braking force distribution control is executed (that is, “Fe = 1”).
Condition D (conditions related to lift-up suppression control):
The estimated fluid pressure (estimated fluid pressure) Pef of the front wheel cylinder CWf is equal to or higher than the upper limit fluid pressure pu of the front wheel fluid pressure Pwf for lift-up control. Here, the front wheel estimated hydraulic pressure Pef is estimated and calculated according to the master cylinder hydraulic pressure Pm and the operating state of the hydraulic pressure modulator HU.

  Calculation results such as braking force distribution control, lift-up suppression control, and anti-skid control are used instead of individual determination algorithms to determine the failure of the front wheel braking system. For this reason, the memory capacity is reduced in the controller ECU (particularly, the microprocessor MP) of the braking control device SC. Further, since the calculation of the controller ECU is simplified, the processing can be speeded up.

SD ... brake device, SC ... brake control device, BP ... brake operation member, BF ... brake fluid, CM ... master cylinder, CW ... wheel cylinder, HU ... hydraulic pressure modulator, HM ... master cylinder fluid path, HW ... wheel cylinder fluid Road, UP ... pressure regulating valve, VI ... inlet valve, VO ... outlet valve, ML ... electric motor, QL ... fluid pump, ECU ... controller, PM ... master cylinder hydraulic pressure sensor, VW ... wheel speed sensor, GX ... deceleration sensor , Pm: master cylinder hydraulic pressure, Vw: wheel speed, Gx: deceleration (detected value), Ge: deceleration (calculated value), Vx: body speed, Pe: estimated hydraulic pressure.

Claims (4)

In a vehicle braking control device provided in a vehicle having a braking device that pumps braking fluid from a master cylinder and applies braking fluid pressure to a wheel cylinder,
A hydraulic modulator for adjusting the braking hydraulic pressure;
A hydraulic pressure sensor for detecting a hydraulic pressure of the master cylinder as a master cylinder hydraulic pressure;
A wheel speed sensor for detecting a wheel speed of the vehicle;
Deceleration acquisition means for acquiring the deceleration of the vehicle;
A controller for controlling the hydraulic modulator based on the wheel speed;
With
The controller is
When the master cylinder hydraulic pressure is equal to or higher than a predetermined hydraulic pressure, the deceleration is less than a predetermined deceleration;
When the rear wheel speed that is the wheel speed of the rear wheel of the vehicle is less than a reference speed that is smaller than the front wheel speed that is the wheel speed of the front wheel of the vehicle by a predetermined speed, the rear wheel speed of the braking device A vehicle brake control device configured to determine that a braking system is in a failed state. The vehicle braking control device according to claim 1,
The controller is
Based on a comparison between the rear wheel speed and the front wheel speed, the rear wheel hydraulic pressure, which is the braking hydraulic pressure for the rear wheel, is controlled via the hydraulic modulator so as to suppress an increase in deceleration slip of the rear wheel. Execute braking force distribution control to limit the increase,
A braking control apparatus for a vehicle configured to prohibit execution of the braking force distribution control when the failure state is determined. In a vehicle braking control device provided in a vehicle having a braking device that pumps braking fluid from a master cylinder and applies braking fluid pressure to a wheel cylinder,
A hydraulic modulator for adjusting the braking hydraulic pressure;
A hydraulic pressure sensor for detecting a hydraulic pressure of the master cylinder as a master cylinder hydraulic pressure;
A wheel speed sensor for detecting a wheel speed of the vehicle;
“Lift-up suppression that restricts an increase in front-wheel hydraulic pressure, which is the braking hydraulic pressure with respect to the front wheels of the vehicle, via the hydraulic pressure modulator so as to suppress lifting of the rear wheels of the vehicle based on the deceleration of the vehicle Control ", and" to suppress an increase in deceleration slip of the rear wheel based on a comparison between a rear wheel speed that is the wheel speed of the rear wheel and a front wheel speed that is the wheel speed of the front wheel, " A controller that executes “braking force distribution control for limiting an increase in rear wheel hydraulic pressure that is the brake hydraulic pressure with respect to the rear wheel via a hydraulic modulator”;
With
The controller is
When the braking device is in a failure state, the lift-up suppression control is not executed,
Calculate the estimated value of the front wheel hydraulic pressure according to the master cylinder hydraulic pressure and the operating state of the hydraulic pressure modulator,
When the braking force distribution control is executed and the estimated value is equal to or higher than the upper hydraulic pressure of the front wheel hydraulic pressure of the lift-up suppression control, the braking system related to the front wheels of the braking device is in a failed state. A vehicle braking control device configured to determine. The vehicle brake control device according to claim 3,
The controller is
A vehicle braking control device configured to end execution of the braking force distribution control when the failure state is determined.