JP6473646B2 - Brake hydraulic pressure control device for vehicles - Google Patents

Description

  The present invention relates to a vehicular brake hydraulic pressure control device that controls a brake hydraulic pressure of a wheel brake that applies a braking force to a wheel, and relates to a vehicle brake hydraulic pressure control device that is suitable for application to a vehicle such as a two-wheeled vehicle or a four-wheeled vehicle. .

  For example, Patent Document 1 discloses a vehicle brake fluid pressure control apparatus capable of controlling brake fluid pressure, such as anti-lock brake control (ABS control) that suppresses wheel lock, in order to accurately control the brake fluid pressure. In addition, there is disclosed a configuration in which a normally open proportional solenoid valve capable of freely changing the valve opening amount is employed as an inlet valve communicating with the master cylinder.

  In the vehicle brake hydraulic pressure control device disclosed in Patent Document 1, the difference in brake hydraulic pressure between the upstream side and the downstream side of the inlet valve is determined according to the magnitude of the drive current that flows through the electromagnetic coil of the inlet valve. Is adjusted.

  Patent Document 2 discloses a vehicle brake hydraulic pressure control device having a configuration in which a regulator is provided between the master cylinder and the inlet valve.

JP 2009-23468 A JP 2007-76528 A

  By the way, in the technique disclosed in Patent Document 1, the valve opening amount of the normally open proportional solenoid valve is set, and the difference between the brake fluid pressure in the upstream fluid passage and the brake fluid pressure in the downstream fluid passage of the inlet valve is set. When adjusting the pressure, the difference between the brake fluid pressure in the upstream fluid passage (master cylinder pressure) detected by the pressure sensor and the estimated brake fluid pressure in the downstream fluid passage (brake fluid pressure in the wheel brake) is detected. The pressure is calculated ([0033] of Patent Document 1).

  However, since the pressure sensor is a relatively expensive and large component as a circuit component, there is a problem that this is an obstacle to downsizing and cost reduction of the entire vehicle brake hydraulic pressure control device.

  The present invention has been made in consideration of such a problem, and it is possible to accurately estimate the brake fluid pressure in the upstream fluid passage of the control valve unit without using a pressure sensor. An object is to provide a pressure control device.

  A brake fluid pressure control device for a vehicle according to the present invention is provided in a brake fluid fluid path from a fluid pressure source that generates brake fluid pressure by operation of an operator to a wheel brake, and acts on the wheel brake. A control valve unit that switches to a state of reducing, increasing, or holding the pressure, a reservoir that stores the brake fluid released from the wheel brake through the control valve unit during the pressure reduction, a motor, and a motor driven by the motor A brake fluid pressure control device for a vehicle, comprising: a pump that sucks the brake fluid from the reservoir side and discharges the brake fluid to an upstream fluid passage of the control valve unit; and when the motor is driven, When the drive current flowing through the motor is gradually increased, and when the drive current increases, the motor changes from a stopped state to a rotating state. Detecting a rotation start driving current, based on the detected rotation start drive current, to estimate the brake fluid pressure of the upstream liquid passage.

  The higher the brake fluid pressure (upstream brake fluid pressure) in the upstream fluid passage of the control valve unit on the pump brake fluid discharge side, the greater the load on the motor that starts the pump operation. The current increases. According to this invention, even if no pressure sensor is provided, the brake fluid pressure in the upstream fluid passage of the control valve unit can be accurately estimated based on the value of the rotation start drive current. Further, since the estimation is made from the value of the drive current at the time of starting the rotation of the motor, the brake fluid pressure in the upstream fluid passage can be estimated at an early stage. As a result, it becomes possible to reduce costs such as unnecessary parts cost, management cost, and assembly cost of the pressure sensor.

  In this case, it is preferable that the drive current is increased with a gentler slope until the start of rotation of the motor than after the start of rotation of the motor.

  Thus, by increasing the drive current at a gentler slope than after the start of rotation of the motor until the start of rotation of the motor, the rotation start point of the motor can be accurately detected.

  When estimating the brake fluid pressure of the upstream fluid passage, the brake of the upstream fluid passage is preliminarily associated with the brake fluid pressure characteristic of the upstream fluid passage with respect to the rotation start drive current. It is preferable to estimate the hydraulic pressure.

  In this way, the rotation start detected by estimating the brake fluid pressure in the upstream fluid passage using the characteristic of the brake fluid pressure in the upstream fluid passage with respect to the rotation start drive current that is associated in advance. The brake fluid pressure in the upstream fluid passage can be easily estimated from the drive current. The characteristics can be obtained in advance by experiments, simulations, or the like.

  According to this invention, the higher the brake fluid pressure (upstream brake fluid pressure) in the upstream fluid passage of the control valve unit that is the discharge side of the brake fluid of the pump, the greater the load applied to the motor that starts the operation, Considering that the rotation start drive current of the motor is increased, the brake fluid pressure in the upstream fluid passage of the control valve unit is accurately determined based on the value of the rotation start drive current even if no pressure sensor is provided. The effect of being able to estimate well is achieved.

1 is a schematic configuration diagram of a vehicle brake hydraulic pressure control device according to an embodiment. It is a flowchart used for the estimation process of the upstream brake fluid pressure by the brake fluid pressure control apparatus for vehicles. FIG. 6 is a characteristic diagram showing a correspondence relationship between motor rotation start drive current and upstream brake fluid pressure. It is a time chart used for operation | movement description of the estimation process of an upstream brake fluid pressure. 5 is a time chart schematically showing the relationship between the motor drive signal before and after the start of rotation of the motor and the motor rotation state in the time chart of FIG. 4 on the time axis.

  Hereinafter, preferred embodiments of a vehicle brake hydraulic pressure control device according to the present invention will be described in detail with reference to the accompanying drawings.

  A brake fluid pressure control device for a vehicle is mounted on a vehicle, ABS control that suppresses wheel locking according to the behavior of the vehicle, the road surface condition, the brake operation condition, and the like, and a skid that stabilizes the behavior of the vehicle Control, traction control (hereinafter referred to as behavior stabilization control), etc. are executed.

  FIG. 1 shows a schematic configuration of a vehicle brake hydraulic pressure control device 10 according to this embodiment.

  In FIG. 1, four wheel brakes (wheel brake FR on the right side of the front wheel, wheel brake RL on the left side of the rear wheel, wheel brake FL on the left side of the front wheel, and right side of the rear wheel are shown for convenience of understanding and for convenience. The brake system K1 for applying braking force to the two wheel brakes FR and RL is shown. The brake system K2 that applies braking force to the remaining two wheel brakes FL and RR (not shown) is substantially the same in configuration and is not shown. Hereinafter, the brake system K1 will be mainly described. K2 will be described as appropriate.

  As shown in FIG. 1, the vehicular brake hydraulic pressure control device 10 basically has a master cylinder 12 as a hydraulic pressure source, brake systems K1, K2, and a control unit that controls the brake systems K1, K2. ECU (Electronic Control Unit) 16.

  The master cylinder 12 has a pedaling force applied to the brake pedal 20 (operator) in each upstream liquid passage 104, 103 communicating with each output port 24a, 24b provided corresponding to the two brake systems K1, K2. A brake fluid pressure (referred to as a master cylinder pressure) Pmc corresponding to In practice, the pedaling force applied to the brake pedal 20 is increased in pressure via the booster 22 and is applied to the master cylinder 12. The output ports 24a and 24b of the master cylinder 12 are connected to the actuator 14 via piping.

  The brake system K1 includes an actuator 14 and wheel brakes FR and RL. Each wheel brake FR, RL is connected to the actuator 14 via a pipe.

  The actuator 14 basically includes an upstream fluid passage 104 communicated with the master cylinder 12, wheel brake fluid passages (also referred to as wheel cylinder fluid passages) 106a and 106b communicated with the wheel brakes FR and RL, and brake fluid passages. The control valve unit 30 provided between the escape liquid passage 108, the reservoir 34 communicating with the escape liquid passage 108, the pump 70 provided between the suction liquid passage 110 and the discharge liquid passage 118 of the pump 70, And a motor 72 for driving the pump 70. The discharge liquid path 118 of the pump 70 communicates with the upstream liquid path 104 of the control valve unit 30.

  Wheel brake fluid passages 106a and 106b, which are downstream fluid passages of the control valve unit 30, communicate with wheel cylinders 18a and 18b constituting the wheel brakes FR and RL, respectively. The wheel brake FR is composed of a wheel cylinder 18a and a brake member such as a brake disk, and the wheel brake RL is composed of a wheel cylinder 18b and a brake member such as a brake disk.

  A relief fluid passage 108 for allowing the brake fluid to escape from the wheel brake fluid passages 106 a and 106 b through the control valve unit 30 communicates with the reservoir 34 via the suction fluid passage 110.

  The control valve unit 30 includes inlet valves 51 and 61 that are normally open proportional solenoid valves, outlet valves 52 and 62 that are normally closed solenoid valves, and check valves 53 and 63. In the inlet valves 51 and 61, the valve opening amount can be freely adjusted by the energization amount to the electromagnetic coil from the ECU 16. As known, the inlet valve 51, the outlet valve 52, and the check valve 53, and the inlet valve 61, the outlet valve 62, and the check valve 63 may be replaced with one three-position solenoid valve. .

  The control valve unit 30 is provided at the intersection of the upstream fluid passage 104, the wheel brake fluid passages 106a and 106b, and the escape fluid passage 108, and the upstream fluid passage 104 and the wheel brake fluid passages 106a and 106b. Pressure increase state in which the relief fluid passage 108 is shut off by communicating (opening), the decompression state in which the upstream fluid passage 104 and the wheel brake fluid passages 106a and 106b are shut off and the escape fluid passage 108 is communicated (opened), and the wheel The brake fluid passages 106 a and 106 b have a function of switching a holding state in which the brake fluid passages 106 a and 106 b are blocked from the upstream fluid passage 104 and the escape fluid passage 108. In other words, the control valve unit 30 increases the brake fluid pressure of the wheel brake fluid passages 106a and 106b acting on the wheel cylinders 18a and 18b, in other words, the state in which the wheel cylinder pressures Pwca and Pwcb are increased, the state in which the pressure is reduced, and the state in which the pressure is maintained. Switch. In the following description, the wheel cylinder pressures Pwca and Pwcb are representatively referred to as wheel cylinder pressures Pwc, unless they need to be described separately.

  The check valves 53 and 63 are provided in parallel to the inlet valves 51 and 61, respectively, and allow only the inflow of the brake fluid from the wheel brake fluid passages 106a and 106b to the upstream fluid passage 104.

  The inlet valves 51 and 61 are provided between the upstream side fluid passage 104 and the wheel brake fluid passages 106a and 106b, respectively. When the inlet valves 51 and 61 are open at the normal time when the fluid pressure control is not performed (normally open), The brake fluid pressure is allowed to be transmitted from the cylinder 12 to the wheel brakes FR and RL.

  On the other hand, the inlet valves 51 and 61 are closed when the wheel is about to be locked during the hydraulic pressure control, thereby blocking the brake hydraulic pressure transmitted from the brake pedal 20 to the wheel brakes FR and RL. To do. Further, during the hydraulic pressure control, the inlet valves 51 and 61 are controlled by the ECU 16 so as to have a predetermined valve opening amount, thereby increasing the brake hydraulic pressure in each wheel brake FR and RL with a predetermined inclination. Let

  The outlet valves 52 and 62 are provided between the wheel brake fluid passages 106a and 106b and the escape fluid passage 108, respectively. When the valve is in a closed state, the outlet valves 52 and 62 supply brake fluid from the wheel cylinders 18a and 18b to the reservoir 34. Block inflow and allow when valve is open.

  The reservoir 34 is provided in the suction fluid passage 110 and passes through the escape fluid passage 108 and the suction fluid passage 110 from the wheel cylinders 18 a and 18 b and the wheel brake fluid passages 106 a and 106 b through the outlet valves 52 and 62 of the control valve unit 30. It has a function of temporarily storing the released brake fluid.

  The pump 70 is provided between the suction liquid path 110 and the discharge liquid path 118, is driven by the rotational force of the motor 72, and sucks the brake fluid temporarily stored in the reservoir 34 through the suction liquid path 110 to generate a pressure. Is discharged to the discharge liquid passage 118. Thus, the brake fluid stored in the reservoir 34 is returned to the discharge fluid passage 118 communicated with the upstream fluid passage 104, whereby the brake fluid is returned to the master cylinder 12 side.

  The ECU 16 is a CPU (central processing unit), a ROM (including EEPROM) as a memory, a RAM (random access memory), and other input / output devices such as an A / D converter, a D / A converter, and a drive circuit. And a timer or the like as a time measuring unit, and the CPU reads and executes a program recorded in the ROM based on an input signal or the like, so that various function realizing units (function realizing means), for example, a control unit, an arithmetic unit, etc. And function as a processing unit or the like. These functions can also be realized by hardware. In that case, the term “˜unit” in the “function realization unit” is replaced with “˜circuit”, “˜device”, or “˜device”.

  More specifically, the ECU 16 according to this embodiment sets the current value related to the energization amount that excites the electromagnetic coils that drive the valve bodies of the inlet valves 51 and 61 that are normally open proportional solenoid valves from 0 to the maximum value. Or, it is adjusted to near the maximum value, adjusted to a predetermined amount of valve opening (predetermined opening amount) between the fully opened state of the valve with the maximum valve opening amount and the valve closed state, and opened by demagnetizing. Set the valve to the fully open state. Further, the solenoid coil that drives the valve bodies of the outlet valves 52 and 62 that are normally closed solenoid valves is energized to be opened, and demagnetized to be closed.

  The motor 72 is a common power source for the pumps 70 in the brake systems K1 and K2, and operates based on a motor drive signal Sd from the ECU 16. In this case, the ECU 16 takes in the terminal voltage (motor voltage) Vm of the motor 72 generated according to the drive signal Sd as a voltage signal.

  The ECU 16 also rotates a wheel rotation speed (wheel speed) Nw from a wheel speed sensor 19 provided on each of four wheels (not shown), and a rotation speed (motor rotation) from a rotation speed sensor (not shown) of the motor 72. Number) Each detection signal such as Nm, a motor current Im from a current sensor (not shown) of the motor 72, and the motor voltage Vm from a voltage sensor (not shown) of the motor 72 is fetched.

  Further, the ECU 16 takes in each detection signal from a brake pedal operation amount (brake pedal stroke amount) detected by a stroke sensor 21 provided at a fulcrum of the brake pedal 20 and a pedal operation switch (not shown).

  The ECU 16 estimates the master cylinder pressure Pmc based on each captured detection signal, and controls the control valve unit 30 (electromagnetic valves including the inlet valves 51 and 61 and the outlet valves 52 and 62), the motor 72, and the like. To do.

  In FIG. 1, in order to avoid complication, wiring between the ECU 16 and each electromagnetic valve, between the ECU 16 and the motor 72, and between the ECU 16 and various sensors is omitted.

  The operation of the vehicular brake hydraulic pressure control apparatus 10 according to this embodiment basically configured as described above will be described next in the order of [basic operation] and [master cylinder pressure estimation processing]. .

[Basic operation]
The basic operation of the vehicular brake hydraulic pressure control device 10 is the same as that of this kind of well-known and well-known brake control device.

  For example, when the brake pedal 20 is operated to apply a brake, a detection signal corresponding to the operation is input to the ECU 16 by a pedal operation switch (not shown).

  At this time, brake fluid having a hydraulic pressure corresponding to the operation of the brake pedal 20 is supplied from the master cylinder 12 to the wheel cylinders 18a and 18b through the control valve unit 30, and braking force is applied to the wheel brakes FR and RL. In this case, the master cylinder pressure Pmc and the wheel cylinder pressure Pwc are the same pressure because the upstream side fluid passage 104 and the fluid passage of the wheel brake fluid passage 106a (106b) communicate with each other.

  When the ECU 16 determines that the hydraulic pressure control such as the ABS control is necessary, for example, if the ECU 16 determines that the brake hydraulic pressure should be reduced, the outlet valves 52 and 62 are excited by the ECU 16 to be in the open state. Fluid pressure control is started by exciting the inlet valves 51 and 61 and closing them instantaneously. As a result, the brake fluid in the wheel cylinders 18a, 18b is discharged to the reservoir 34 through the relief fluid passage 108 and the suction fluid passage 110 through the outlet valves 52, 62, and the brake fluid pressure in the wheel brake fluid passages 106a, 106b, that is, the wheel cylinder. The pressure Pwc is reduced.

  The ECU 16 excites the outlet valves 52, 62 and simultaneously drives the motor 72, whereby the brake fluid stored in the reservoir 34 is sucked in through the suction liquid passage 110 by the pump 70, and upstream through the discharge liquid passage 118. The liquid is recirculated to the side liquid passage 104, in other words, to the master cylinder 12 side.

  When the ECU 16 determines that the brake fluid pressure should be maintained, the outlet valves 52 and 62 are demagnetized and closed. As a result, the wheel brake fluid passages 106a and 106b are disconnected from the upstream fluid passage 104 and the escape fluid passage 108, and the wheel cylinder pressure Pwc is kept constant.

  When the ECU 16 determines that the brake fluid pressure should be increased, the outlet valves 52 and 62 are demagnetized and closed, and the inlet valves 51 and 61 are gradually lowered from a higher current value to be lower. As a result, the wheel cylinder pressure Pwc is gradually increased.

  Hereinafter, until it is determined that fluid pressure control such as ABS control is unnecessary, such fluid pressure control of pressure reduction, holding, and pressure increase is appropriately selected and executed.

[Master cylinder pressure estimation processing]
During hydraulic pressure control by the ECU 16 such as ABS control, the master cylinder pressure Pmc is used as a control parameter for the ECU 16.

  Then, next, the estimation process of the master cylinder pressure Pmc which is the brake fluid pressure (upstream brake fluid pressure) of the upstream fluid passage 104 of the control valve unit 30 by the vehicle brake fluid pressure control device 10 is shown in FIG. This will be described with reference to a flowchart. The execution subject of the program according to the flowchart described below is the ECU 16 (or its CPU).

  In step S1, the ECU 16 determines whether or not the brake fluid pressure control of the wheel brakes FR and RL is started.

  For example, the ABS control is started when the slip ratio of the vehicle becomes equal to or greater than a predetermined value and a sudden deceleration of the wheel speed Nw from the wheel speed sensor 19 (possibility of wheel lock) is detected. If the start condition of such hydraulic pressure control is satisfied, the determination is affirmative (step S1: YES).

  If the hydraulic pressure control is not being performed (step S1: NO) and the normal state such as during normal braking, the process is terminated. In a normal state where the hydraulic pressure control is not being performed, as is well known, the master cylinder pressure Pmc (in this case, the upstream brake hydraulic pressure Pmu) can be estimated from the amount of change in the estimated vehicle speed or the like.

  When it is determined that the hydraulic pressure control is started (step S1: YES), it is determined in step S2 whether or not the motor 72 needs to be driven.

  If it is not determined that the motor 72 needs to be driven (step S2: NO), the process ends.

  If it is determined that the motor 72 needs to be driven (step S2: YES), the ECU 16 in step S3, for example, a motor that drives the motor 72 so that the motor current Im rises gradually and gradually. The duty ratio D of the drive signal Sd is gradually increased. In this embodiment, the motor drive signal Sd output from the ECU 16 to the motor 72 is a repetitive square wave constant voltage constant cycle {PWM (pulse width modulation) that is switched between a low level (off) and a high level (on). The motor 72 is a DC motor that increases the motor rotation speed Nm by increasing the duty ratio D (D = ON period / PWM period) of the motor drive signal Sd.

  Next, in step S4, the ECU 16 determines whether or not the motor 72 has started rotating from, for example, the motor rotational speed Nm. The rotation state of the motor 72 (motor rotation speed Nm) can also be determined by measuring the motor voltage Vm, which is the voltage across the motor 72 during the OFF period of the motor drive signal Sd, in the PWM control described above. Can do.

  Here, the start of rotation of the motor 72 means the start of operation of the pump 70 in which the master cylinder pressure Pmc is applied to the discharge liquid passage 118 side. Therefore, the motor 72 starts to rotate when the torque generated by the motor 72 (proportional to the magnitude of the motor current Im) increases to a level at which the operation of the pump 70 is started.

  In step S4, if the ECU 16 cannot detect the start of rotation of the motor 72 (step S4: NO), the ECU 16 continues to increase the motor current Im with a gentle gradient in step S3.

  In step S4, the ECU 16 determines that the rotation of the motor 72 has started by detecting an increase in the motor rotation speed Nm from 0 (Nm> 0: Nm has become larger than zero) (step S4: YES).

  At this time, in step S5, the ECU 16 detects the motor current Im at the motor rotation start time as the motor rotation start current Imstart (Im = Imstart).

  Next, in step S6, the ECU 16 estimates the master cylinder pressure Pmc based on the magnitude (value) of the motor rotation start current Imstart detected in step S5.

  FIG. 3 shows a characteristic 200 indicating the relationship between the motor rotation start current Imstart [A] and the master cylinder pressure Pmc [MPa] acquired in advance through experiments or simulations. The master cylinder pressure Pmc is equal to the motor rotation start current Imstart [when the pump 70 is actually discharging brake fluid from the suction fluid passage 110 to the discharge fluid passage 118 with respect to the motor rotation start current Imstart taken into the ECU 16. The master cylinder pressure Pmc [MPa] changes substantially linearly according to the magnitude of A].

  Therefore, the master cylinder pressure Pmc can be estimated with reference to the characteristic 200 by detecting and taking in the motor rotation start current Imstart. Note that the characteristic 200 may be stored in the storage unit as an arithmetic expression for use.

  Thereafter, in step S7, the ECU 16 prepares for hydraulic pressure control by increasing the motor current Im more steeply than before the motor 72 starts rotating.

  Next, in step S8, the master cylinder pressure Pmc estimated in step S6 is immediately applied to the hydraulic pressure control described above.

[Specific operation example of master cylinder pressure estimation processing]
Here, a specific operation example of the process of estimating the master cylinder pressure Pmc that is the brake fluid pressure (referred to as upstream brake fluid pressure) in the upstream fluid passage 104 of the control valve unit 30 by the vehicle brake fluid pressure control device 10. Will be described with reference to the time chart of FIG.

  At time t-1 in FIG. 4, the brake pedal 20 is operated and the master cylinder pressure Pmc starts to increase. At time (hydraulic pressure control start time) t0, hydraulic pressure control is started (corresponding to step S1). ).

  At that time t0, the ECU 16 excites the outlet valves 52 and 62 to open them, and simultaneously excites the inlet valves 51 and 61 to instantly close them. As a result, after time t0, the brake fluid in the wheel cylinders 18a and 18b is discharged to the reservoir 34 through the relief fluid passage 108 via the outlet valves 52 and 62, and the wheel cylinder pressure Pwc is reduced.

  At the time t0, the ECU 16 needs to suck the brake fluid stored in the reservoir 34 through the suction fluid passage 110 by the pump 70, and discharge it to the discharge fluid passage 118 communicating with the upstream fluid passage 104 for reflux. It is determined that the motor needs to be driven (step S2: corresponding to YES).

  Normally (in the comparative example), as shown in the waveform of the motor current Im ′ drawn with a one-dot chain line at t0 in FIG. 4, the motor whose motor rotation speed Nm immediately becomes the target rotation speed from the hydraulic pressure control start time t0. Although the current Im ′ is set, in this embodiment, as shown in the waveform of the motor current Im drawn by a solid line, a motor 72 drive signal (motor motor) is set so that the motor current Im gradually rises after time t0. Drive signal) Sd is controlled.

  FIG. 5 is a time chart showing the relationship between the waveform of the motor drive signal Sd and the motor rotation state on the enlarged time axis from the time point t-1 to the vicinity of the time point t2 in the time chart of FIG. A temporal correspondence relationship between the waveform of the motor drive signal Sd that is pulse width modulated (PWM) at a constant period and the motor rotation state is shown.

  At time t0 in FIG. 5, a slight motor driving current flows through the armature coil of the motor 72 by the motor driving signal Sd having a narrow-width square wave pulse. With this motor drive current, the motor 72 is in a non-rotating state that does not rotate (corresponding to step S4: NO). Thereafter, the time ta, the time tb, the time tc, and the motor current Im are increased with a gentle gradient that gradually increases the duty ratio D of the motor drive signal Sd of the square wave pulse (step S4: NO → step S3 is repeated) (Refer to the increase state of the motor current Im between the time point t0 and the time point t1 with a gentle gradient in FIG. 4). Thereafter, at time t1 after time td (FIG. 5), the motor 72 transitions from the non-rotating state to the rotating state, and rotation starts (corresponding to step S4: YES).

  The ECU 16 that has detected that the rotation of the motor 72 has started by detecting an increase from the zero value of the motor rotation speed Nm at that time t1 increases the duty ratio D abruptly after the time t1, so that the motor As shown in the waveform indicated by the solid line after time t1 in FIG. 4, the current Im is started to increase at a steep slope (corresponding to step S7), and thereafter, after time t3 so that the motor current Im becomes constant. The duty ratio D is also controlled to be constant. The steep increase in the motor drive current Id is set so that the increase in the high-level period in the PWM cycle of the motor drive signal Sd, that is, the duty ratio D increases, as shown after time t1 in FIG. That's fine.

  On the other hand, at the time point t1, the ECU 16 detects the motor rotation start current Imstart (corresponding to step S5), refers to the characteristic 200 (FIG. 3), and determines the brake fluid pressure (upstream brake) in the upstream fluid path 104. Hydraulic pressure), in other words, the master cylinder pressure Pmc is estimated (corresponding to step S6).

  Then, using the estimated master cylinder pressure Pmc as a control parameter, the ABS control or the behavior stabilization control is performed such that the wheel cylinder pressure Pwc is increased from time t2 to time t4 (corresponding to step S8). Furthermore, the hydraulic pressure control of the wheel brakes FR and RL can be performed with high accuracy using the estimated master cylinder pressure Pmc as a control parameter.

[Summary of Embodiment and Modifications]
As described above, the vehicular brake hydraulic pressure control device 10 according to the above-described embodiment is upstream of communicating with the master cylinder 12 as a hydraulic pressure source that generates brake hydraulic pressure by operating an operator such as the brake pedal 20. Provided between the side fluid passage 104, the wheel brake fluid passages 106a, 106b communicating with the wheel brakes FR, RL, and the brake fluid relief fluid passage 108, and acts on the wheel brakes FR, RL during hydraulic pressure control. A control valve unit 30 that switches the brake fluid pressure to a state where pressure is reduced, increased, or maintained, and escapes from the wheel brakes FR and RL through the wheel brake fluid passages 106a and 106b and the control valve unit 30 to the fluid passage 108 when the pressure is reduced. A reservoir 34 for storing the brake fluid generated, a motor 72, and the reservoir 34 driven by the motor 72 The brake fluid, comprising inhaling through the suction fluid passage 110, a pump 70 for discharging the discharge liquid passage 118 which communicates with the upstream side fluid passage 104 of the control valve unit 30.

  The vehicle brake hydraulic pressure control device 10 further includes an ECU 16 as a control unit (hydraulic pressure control unit) that controls the control valve unit 30 and the motor 72 to perform the hydraulic pressure control.

  In this case, when driving the motor 72 after the start of the hydraulic pressure control, the ECU 16 drives the motor current Im flowing through the motor 72 so as to gradually increase from the zero value. During the increase of the motor current Im, The motor rotation start current Imstart when the 72 changes from the stop state to the rotation state (time point t1) is detected, and the upstream side liquid passage is referred to based on the detected motor rotation start current Imstart with reference to the characteristic 200 (FIG. 3). 104 brake fluid pressure (upstream brake fluid pressure), in other words, master cylinder pressure Pmc is estimated.

  The higher the brake fluid pressure (upstream brake fluid pressure) of the upstream fluid passage 104 that is the brake fluid discharge side of the pump 70, that is, the master cylinder pressure Pmc, the greater the load is applied to the motor 72 that starts the pump 70. The rotation start current Imstart of the motor 72 increases. Therefore, even if no pressure sensor is provided, the upstream brake fluid pressure, in other words, the master cylinder pressure Pmc can be accurately estimated based on the motor rotation start current Imstart with reference to the characteristic 200 and the like. . Since the pressure sensor is not necessary, costs such as pressure sensor parts cost, management cost, and assembly cost can be reduced.

  In this case, it is preferable that the ECU 16 increases the motor current Im with a gentler gradient (from time t0 to time t1) than after the rotation of the motor starts (after time t1) until the rotation start time t1 of the motor 72. By increasing the motor current Im with a gentle gradient, the rotation start point of the motor 72 can be detected with high accuracy, and as a result, the accurate motor rotation start current Imstart can be detected.

  As shown in the waveform of the motor current Im from the time point t0 to the time point t1 in FIG. 4, the gradient is not limited to a gentle increase with a linear function, but increases with a gentle gradient along a function other than the linear function. You may make it make it.

  The ECU 16 estimates the master cylinder pressure Pmc using the characteristic 200 (FIG. 3) of the master cylinder pressure Pmc with respect to the motor rotation start current Imstart, which is associated in advance, so that the master cylinder pressure is detected from the detected motor rotation start current Imstart. Pmc can be estimated easily and accurately. The characteristic 200 can be obtained in advance by experiments, simulations, or the like.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various configurations can be adopted based on the contents described in this specification.

[Modification]
For example, in the above-described embodiment, the master cylinder 12 and the control valve unit 30 are configured to communicate with each other via the upstream liquid passage 104, but not limited thereto, as shown in FIG. Provided between the master cylinder 12 and the control valve unit 30 is a regulator composed of a normally open cut valve (switching valve) provided with a relief valve in parallel, and further, an upstream liquid passage 104 and a pump communicating with the control valve unit 30 70 is applied to a brake fluid pressure control device for a vehicle having a configuration in which a normally closed suction valve is provided between the suction fluid passages 110 of 70 and the upstream brake fluid pressure of the control valve unit 30 is estimated. You can also. In the vehicular brake hydraulic pressure control apparatus configured as described above, as is well known, a brake hydraulic pressure larger than the brake hydraulic pressure generated by the operation of the operator such as the brake pedal 20 of the driver is generated. Brake assist control (BA control) becomes possible.

10 ... Vehicle brake hydraulic pressure control device 12 ... Master cylinder (hydraulic pressure source)
DESCRIPTION OF SYMBOLS 16 ... ECU (control part) 30 ... Control valve unit 34 ... Reservoir 70 ... Pump 104 ... Upstream liquid passage 106a, 106b ... Wheel brake fluid passage 108 ... Escape fluid passage 110 ... Intake fluid passage 118 ... Discharge fluid passage FR, FL ... Wheel brake Pmc ... Master cylinder pressure Pwc (Pwca, Pwcb) ... Wheel cylinder pressure

Claims (3)

Control that switches the brake fluid pressure acting on the wheel brake to a reduced, increased, or maintained state provided in the fluid path of the brake fluid from the fluid pressure source that generates the brake fluid pressure by the operation of the operator to the wheel brake A valve unit;
A reservoir for storing the brake fluid released from the wheel brake through the control valve unit during the decompression;
A motor,
A pump that is driven by the motor and sucks the brake fluid from the reservoir side, and discharges the brake fluid to an upstream fluid passage of the control valve unit;
A brake fluid pressure control device for a vehicle comprising:
When driving the motor, it is driven so that the drive current flowing through the motor gradually increases, and the rotation start drive current when the motor transitions from the stop state to the rotation state is detected while the drive current is rising. And
A brake fluid pressure control device for a vehicle, wherein the brake fluid pressure in the upstream fluid passage is estimated based on the detected rotation start drive current. The vehicle brake hydraulic pressure control device according to claim 1,
The vehicular brake hydraulic pressure control device increases the drive current with a gentler gradient until after the start of rotation of the motor. The vehicle brake hydraulic pressure control device according to claim 1 or 2,
When estimating the brake fluid pressure of the upstream fluid passage, the brake fluid pressure of the upstream fluid passage is preliminarily associated with the brake fluid pressure of the upstream fluid passage with respect to the rotation start drive current. A brake fluid pressure control device for a vehicle, characterized in that

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