JP6011175B2 - Brake control device for vehicle - Google Patents

Description

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

  In the anti-skid control (also referred to as ABS control) that individually adjusts the brake fluid pressure of the wheels that are opposite to the left and right in Patent Document 1, for the purpose of preventing the left and right wheels from falling into a deep locked state at the same time, “ABS control threshold is set for each of the left and right wheels, and when ABS control is started for only one of the left and right wheels, the slip ratio of the target wheel is reduced for the other wheel.” It is described. As an effect of this, “when the control of the brake fluid pressure on one wheel is started, the control of the brake fluid pressure is started before the lock tendency set in advance as the control start condition is determined on the other wheel. Even if one of the wheels falls into a relatively deep locked state with the start of ABS control, both wheels do not fall into the deep locked state at the same time, and the running stability of the vehicle is ensured. Is described.

  Patent Document 2 discloses a vehicular brake device that performs an electrically braking operation by changing an energization amount to an actuator (electric motor) for generating a braking force in accordance with a depression state of a brake pedal. `` Calculate the command current according to the depression state of the brake pedal, add a positive sign compensation current to the command current at the rise of the command current, and before the transition to the steady state after the command current falls It is described that the compensation current with a negative sign is added and the brake driving actuator is driven based on the command current with the compensation current added. As an effect, “the time delay of the braking torque due to the moment of inertia, damping loss, and friction loss of the actuator for driving the brake can be eliminated, and the overshoot caused by these can be reduced”. Have been described.

JP-A-9-254664 JP 2002-225690 A

  In ABS control as described in Patent Document 1, excessive wheel slip is suppressed, and vehicle stability can be maintained by ensuring lateral force of the wheels. Here, in the hydraulic brake device using the brake fluid (brake fluid), the inertia of the fluid is negligibly small. Therefore, when a pressure reduction instruction (instruction for reducing braking torque) is given, the braking torque can be immediately reduced. On the other hand, in an electric / mechanical braking device (so-called electric brake, referred to as EMB (Electro-Mechanical Brake)) that controls braking torque using an electric motor as described in Patent Document 2. Because of the inertia of the electric motor, speed limitation (maximum rotational speed), etc., it becomes difficult to immediately reduce the braking torque in response to the braking torque reduction instruction.

  Hereinafter, this point will be described in detail with reference to FIG. In the upper diagram of FIG. 13, an example of a time series change of the operation amount Bpa of the braking operation member (brake pedal) by the driver and the target value Fbu and the actual value Fba of the pressing force of the friction member (brake pad) is shown. ing. The lower diagram of FIG. 13 shows a target value Imt of the energization amount to the electric motor in this example.

  In this example, the driver suddenly started the braking operation member at time t0. At this time, in order to compensate for the influence of the inertia of the electric motor and the like, the target value Imt of the energization amount is “the compensation current with a positive sign was added to the value corresponding to the depression” between the time points t1 and t2. Inertia compensation control calculated to “value” is executed. By this inertia compensation control, the actual value Fba is rapidly increased following the target value Fbu of the pressing force. At time t3, the wheel slip increased and slip suppression control (anti-skid control) was started. That is, after the time point t3, in order to suppress excessive wheel slip, the pressing force target value Fbu is rapidly decreased. However, until the time t3, the electric motor moves (rotates) at a high speed in order to increase the pushing force rapidly. Therefore, after the time point t3, due to the influence of the inertia of the electric motor, the actual pushing force Fba cannot be rapidly decreased immediately, but starts to decrease after the time point t3. Furthermore, the decreasing slope (time variation) of Fba is limited by the maximum speed of the electric motor. As a result, the problem of increased wheel slip can arise.

  The present invention has been made to cope with the above-described problem, and an object of the present invention is to provide a vehicle that generates a braking torque by an electric motor with respect to an electric braking wheel that is a part or all of four wheels of the vehicle. Brake control device, when starting execution of slip suppression control such as anti-skid control for electric braking wheel, slip of electric braking wheel becomes excessive due to the influence of inertia (inertia moment, inertial mass) of electric motor It is in providing what can be suppressed.

  The vehicle braking control apparatus according to the present invention generates braking torque for an electric braking wheel (WH [**]), which is a part or all of four wheels of the vehicle, via an electric motor (MTR). Electric braking means (BRK) for causing the vehicle to move, wheel speed obtaining means (VWA) for obtaining the speed (Vwa [**]) of the four wheels (WH [**]) of the vehicle, speed of the four wheels ( Vwa [**]) based on Vwa [**]), a slip state amount calculating means (SLP) for calculating a slip state amount (Slp [**]) representing the degree of slip of the four wheels of the vehicle, and slipping of the electric braking wheel Based on the state quantity (Slp [**]), a target energization amount (Imt) of the electric motor (MTR) is calculated in order to execute slip suppression control that suppresses slipping of the electric braking wheel, and the target energization The electric braking wheel based on the quantity (Imt) Wherein provided for controlling the electric motor (MTR) and (decreasing the braking torque of the electric braking wheel (pressing force)) control means (CTL), the.

  A feature of the present invention is that the control means (CTL) is based on a slip state quantity (Slp [**]) of a first wheel (WH [**]) that is one of the four wheels. Adjusting the target energization amount (Imt) to execute a sudden stop control for suddenly stopping (rapidly decelerating) the rotational motion of the electric motor (MTR) (in the direction of increasing the braking torque of the electric braking wheel); The electric motor (MTR) is controlled for the electric braking wheel based on the adjusted target energization amount (Imt).

  Here, the sudden stop control may be started on the condition that the slip suppression control of the electric braking wheel is not executed. In addition, when the slip degree of the first wheel represented by the slip state quantity (Slp [**]) of the first wheel exceeds the first degree (vsq1, dvq1), the sudden stop control is started. It can be configured to determine.

  As the sudden stop control, when the start of the sudden stop control is determined, a target energization amount (Imt) of the electric motor (MTR) is set to a preset energization limit corresponding to the deceleration direction of the electric motor. Control to change stepwise to the value (imm) is executed. Thereby, a large torque in the deceleration direction acts on the electric motor, and the electric motor is suddenly decelerated and stopped. In this case, the energization limit value (imm) may be determined based on the maximum value of current that can be energized to at least one of the electric motor (MTR) and the drive circuit (DRV) of the electric motor. .

  According to the above feature of the present invention, the sudden stop control of the electric motor for adjusting the braking torque of the electric braking wheel is started and executed based on the slip state quantity of the first wheel. Therefore, when the driver suddenly operates the braking operation member, the sudden stop control causes the electric braking wheel to rotate at a high speed in a direction that rapidly increases the braking torque (pushing force) due to the sudden operation. The rotating motion of the electric motor can be decelerated and stopped early. As a result, even when the slip suppression control of the electric braking wheel is started immediately after that, the electric motor can be immediately rotated in the reverse direction to immediately reduce the braking torque (pushing force) of the electric braking wheel. As a result, excessive slip of the electric braking wheel can be reliably suppressed.

  Here, the first wheel and the electric braking wheel may be different or the same. As the first wheel, among the four wheels, a “wheel having the largest slip degree represented by the slip state amount of the wheel” may be selected. Thereby, compared with the case where another wheel is selected as the first wheel, the sudden stop control can be started earlier. Therefore, the rotational motion of the electric motor that is rotating at high speed in the direction of rapidly increasing the braking torque (pushing force) of the electric system wheel (due to the sudden operation of the braking operation member by the driver) is decelerated earlier.・ Can be stopped.

  In the above-described braking control device according to the present invention, in the case of including an operation amount acquisition unit (BPA) that acquires an operation amount (Bpa) of the braking operation member (BP) by the driver of the vehicle, the control unit (CTL) The electric braking wheel may be configured to adjust a target energization amount (Imt) of the electric motor (MTR) to a value corresponding to the operation amount (Bpa).

  In this case, the control means (CTL) determines whether or not to execute inertia compensation control for compensating the influence of the inertia of the electric braking means (BRK) for the electric braking wheel based on the operation amount (Bpa). If it is determined and execution of the inertia compensation control is determined (Ijt> 0 or FLj ← 1), the target energization amount (Imt) of the electric motor is increased from a value corresponding to the operation amount (Bpa). It can be configured to execute inertia compensation control. The control means (CTL) stops the inertia compensation control and executes only the sudden stop control when it is determined that the sudden stop control is started during the execution of the inertia compensation control. Can be configured. Here, it may be configured to determine the start of the sudden stop control on condition that the inertia compensation control is being executed.

  In the slip suppression control of the electric braking wheel, as a typical example in which the influence of the inertia of the electric motor becomes a problem, the driver suddenly brakes on the road surface having a high road surface friction coefficient (for example, a dry asphalt road surface), and the inertia There is a case where slip suppression control of the electric braking wheel is required while the electric motor is accelerated by the compensation control.

  The above configuration is a configuration obtained in consideration of such a typical scene. The inertia compensation control is a control in a direction that prompts the “rotational motion in the direction of increasing the braking torque of the electric braking wheel” of the electric motor. According to the above configuration, in the typical scene, the inertia compensation control is stopped and only the sudden stop control is executed. Therefore, the rotational motion of the electric motor (in the direction of increasing the braking torque of the electric braking wheel) can be decelerated and stopped earlier than when the inertia compensation control is continued.

  In the braking control device according to the present invention, when provided with motor speed acquisition means (DMK) for acquiring the speed (dMk) of the electric motor (MTR), the speed (dMk) of the electric motor is set to a first predetermined speed (dmk1). ) On the condition that it is the above, it may be configured to start the sudden stop control. In this case, the rapid stop control may be terminated based on the fact that the speed (dMk) of the electric motor is less than a second predetermined speed (dmk2) smaller than the first predetermined speed (dmk1). . These configurations are based on the fact that the influence of the inertia of the electric motor increases as the speed of the electric motor increases.

  The braking control device according to the present invention includes hydraulic braking means (MC, HU, BRH) for generating braking torque for the front wheels (WH [f *]) of the vehicle via braking hydraulic pressure, In addition, it is assumed that the electric braking wheel provided with the electric braking means (BRK) is a rear wheel (WH [r *]) of the vehicle. In addition, when braking the vehicle, the ratio of the braking force generated on the front wheel to the vertical load acting on the front wheel is the ratio of the braking force generated on the rear wheel to the vertical load acting on the rear wheel. It is assumed that the braking torque applied to the electric braking wheel (rear wheel) is adjusted to be larger.

  In this case, the control means (CTL) is configured to determine the start of the sudden stop control based on a slip state quantity (Slp [f *]) of the front wheel as the first wheel. Is preferred.

  Generally, when braking the vehicle (that is, during deceleration), the braking load of the front wheels (the ratio of the braking force to the vertical load at the wheel, that is, the braking force generated on the wheel is divided by the vertical load acting on the wheel). The braking torque of the four wheels is set on the basis of the specifications and the like so that the value) is larger than the braking load of the rear wheels. In this case, the slip degree (slip degree) of the front wheels is larger than the slip degree of the rear wheels. Therefore, when the driver suddenly operates the braking operation member, the slip degree of the front wheels increases before the slip degree of the rear wheels. According to the above configuration, the sudden stop control of the electric motor for adjusting the braking torque of the rear wheel is started and executed based on the slip state amount of the front wheel. Therefore, compared with the case where the sudden stop control is started and executed based on the slip state amount of the rear wheel, the braking torque (pressing force) of the rear wheel is reduced (due to the sudden operation of the braking operation member by the driver). It is possible to decelerate and stop the rotary motion of the electric motor that is rotating at high speed in the direction of rapid increase at an earlier stage. As a result, even when the rear wheel slip suppression control is started immediately thereafter, the braking torque (pushing force) of the rear wheel can be rapidly decreased by immediately rotating the electric motor in the reverse direction. As a result, excessive slip of the rear wheel can be reliably suppressed.

  As described above, when hydraulic braking means (MC, HU, BRH) for generating a braking torque for the front wheels (WH [f *]) of the vehicle via the braking hydraulic pressure is provided, Based on the slip state quantity (Slp [f *]), the brake fluid pressure of the front wheel may be reduced in order to execute the slip suppression control of the front wheel that suppresses the slip of the front wheel.

  In this case, the control means (CTL) performs the sudden stop control when the front wheel slip degree represented by the front wheel slip state quantity (Slp [f *]) exceeds the first degree (vsq1, dvq1). And the slip degree of the front wheel represented by the slip state quantity (Slp [f *]) of the front wheel exceeds a second degree (vsb1, dvb1) greater than the first degree (vsq1, dvq1). It is preferable that the front wheel slip suppression control is started.

  According to this, when the driver suddenly operates the braking operation member, the sudden stop control is performed at a stage before the front wheel slip suppression control is started, that is, at a stage where the slip degree of the front wheel slightly increases. Can be started. As described above, the slip degree of the rear wheels has not yet increased at this stage. Therefore, the rotational motion of the electric motor that is rotating at high speed in the direction of rapidly increasing the braking torque (pushing force) of the rear wheels can be surely decelerated and stopped early. As a result, even when the rear wheel slip suppression control is started immediately thereafter, the electric motor can be immediately rotated in the reverse direction, and excessive slip of the rear wheel can be more reliably suppressed. . In addition, as a typical pattern when the driver suddenly operates the braking operation member, “First, the sudden stop control of the electric motor of the rear wheel is started, then, the slip suppression control of the front wheel is started, Next, a pattern in which rear wheel slip suppression control is started can be assumed.

1 is a schematic configuration diagram of a vehicle equipped with a braking control device according to an embodiment of the present invention. It is a figure for demonstrating the structure of the braking means (brake actuator) of the wheel shown in FIG. FIG. 3 is a drive circuit diagram showing an example of drive means for the electric motor (brush motor) shown in FIG. 2. FIG. 3 is a drive circuit diagram showing an example of drive means for the electric motor (brushless motor) shown in FIG. 2. It is a functional block diagram of the control means shown in FIG. FIG. 6 is a functional block diagram for explaining a first embodiment of an inertia compensation control block shown in FIG. 5. It is a functional block diagram for demonstrating 2nd Embodiment of the inertia compensation control block shown in FIG. It is a functional block diagram for demonstrating embodiment of the slip suppression control block shown in FIG. 5, and a sudden stop control block. It is a 1st time chart for demonstrating the effect | action and effect of sudden stop control. It is a 2nd time chart for demonstrating the effect | action and effect of sudden stop control. It is a schematic block diagram of the vehicle carrying the braking control apparatus which concerns on other embodiment of this invention. It is a functional block diagram for demonstrating embodiment of the slip suppression control block and sudden stop control block about the braking control apparatus shown in FIG. It is a time chart for demonstrating the problem of the conventional braking control apparatus.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a vehicle braking control apparatus according to the present invention will be described with reference to the drawings. The subscript [**] attached to the end of various symbols, etc. indicates whether the various symbols are related to any of the four wheels, [fl] is the left front wheel, and [fr] is the right front wheel , [Rl] indicates the left rear wheel, and [rr] indicates the right rear wheel. The subscript [f *] indicates that it relates to any of the front wheels, and the subscript [r *] indicates that it relates to any of the rear wheels. In addition, various symbols relating to four wheels, and when the subscript is [**], a generic name of the four wheels is shown including the case where [**] is omitted and there is no subscript. For example, VWA [**] and VWA are generic names of four-wheel wheel speed acquisition means.

<Configuration of Entire Vehicle Equipped with Embodiment of Brake Control Device for Vehicle according to Present Invention>
As shown in FIG. 1, in this vehicle, each wheel WH [**] of the vehicle is operated according to the operation of braking operation members (for example, brake pedals) BP and BP operated by the driver to decelerate the vehicle. An electronic brake unit (electric brake actuator) BRK, which controls the braking torque to generate a braking force on the wheels, an electronic control unit ECU for controlling the BRK, and a storage battery BAT as a power source for supplying electric power to the BRK, ECU, etc. It is installed.

  In addition, the vehicle includes a braking operation amount acquisition means (for example, a stroke sensor, a pedal force sensor, a master cylinder pressure sensor) BPA that detects the operation amount Bpa of the BP, and a steering that detects the operation angle Saa of the steering wheel SW by the driver. Angle detection means SAA, yaw rate detection means YRA for detecting the yaw rate Yra of the vehicle, longitudinal acceleration detection means GXA for detecting the longitudinal acceleration Gxa of the vehicle, lateral acceleration detection means GYA for detecting the lateral acceleration Gya of the vehicle, and each wheel WH Wheel speed detection means VWA for detecting the rotation speed (wheel speed) Vwa of [**] is provided. Each detected value can be obtained from another system (another electronic control unit) via a communication bus.

  The electric braking means BRK is provided with an electric motor MTR (not shown), and the braking torque of the wheel WH [**] is controlled by the MTR. In addition, in BRK, the energizing amount detection for detecting the energizing amount (for example, current value) Ima of the pressing force detecting means (for example, axial force sensor) FBA, MTR for detecting the force Fba for the friction member MSB to press the rotating member KTB. Position detecting means (for example, rotation angle sensor) MKA for detecting the position (for example, rotation angle) Mka of the means (for example, current sensor) IMA, MTR is provided.

  The detection signals (Bpa and the like) from the various detection means described above are processed by a noise removal (reduction) filter (for example, a low-pass filter) and supplied to the ECU. In the ECU, a braking control calculation process according to the present invention is executed. That is, a control means CTL described later is programmed in the ECU, and a target energization amount (for example, target current value, target duty ratio) Imt [r *] for controlling the electric motor MTR is calculated based on Bpa or the like. . In the ECU, arithmetic processing such as anti-skid control (ABS), traction control (TCS), and vehicle stabilization control (ESC) is executed based on Vwa [**], Yra, and the like.

<Configuration of electric braking means (brake actuator)>
In the embodiment of the braking control device according to the present invention, generation and adjustment of the braking torque of the vehicle wheel WH [**] is performed by the electric motor MTR.

  As shown in FIG. 2, the electric braking means BRK includes a brake caliper CPR, a rotating member KTB, a friction member MSB, an electric motor MTR, a driving means (electric circuit for driving the MTR) DRV, a speed reducer GSK, a rotation / direct motion. The dynamic conversion mechanism HNK, the pressing force acquisition means FBA, the position detection means MKA, and the energization amount acquisition means IMA are configured. Here, the wheel provided with the electric braking means BRK is referred to as “electric braking wheel”.

  The electric brake actuator BRK is provided with a known brake caliper CPR and a friction member (for example, a brake pad) MSB, similarly to a known braking device. When the MSB is pressed against a known rotating member (for example, a brake rotor) KTB, a frictional force is generated, a braking torque is generated on the wheel WH [**], and a braking force is generated.

  The drive means (drive circuit for the electric motor MTR) DRV controls the energization amount (finally the current value) to the electric motor MTR based on the target energization amount (target value) Imt. Specifically, a bridge circuit using a switching element (a power transistor, for example, a MOS-FET) is configured in the driving unit DRV, and the switching element is driven based on the target energization amount Imt. The output of the motor MTR is controlled.

  The output (output torque) of the electric motor MTR is transmitted to the rotation / linear motion conversion mechanism HNK via a reduction gear (for example, a gear) GSK. Then, the rotating motion is converted into a linear motion by HNK, and the piston PSN is advanced toward the rotating member (brake disc) KTB. And since piston PSN pushes friction member (brake pad) MSB toward KTB, friction member MSB is pressed against rotation member KTB. KTB is fixed to the wheel WH [r *], and braking torque is generated in the wheel WH [**] and adjusted by friction between the MSB and KTB.

  As the rotation / linear motion conversion mechanism HNK, a slide screw (for example, a trapezoidal screw) that performs power transmission (slip transmission) by “slip” is used. The screw HNJ rotates, and the nut HNT screwed with the screw HNJ moves forward or backward as a linear motion with respect to KTB. As the HNK, a ball screw that performs power transmission (rolling transmission) by “rolling” may be used.

  The motor drive circuit DRV includes an energization amount acquisition unit (for example, a current sensor) IMA that detects an actual energization amount (for example, an electric current that actually flows through the electric motor) Ima. Further, the electric motor MTR is provided with position acquisition means (for example, an angle sensor) MKA for detecting the position (for example, rotation angle) Mka of the rotor. Further, a pressing force acquisition means (for example, a pressing force sensor) FBA is provided to detect a force (actual pressing force) Fba that the friction member MSB actually presses the rotating member KTB.

  In FIG. 2, a configuration of a so-called disc type braking device (disc brake) is illustrated as the electric braking unit BRK, but the braking unit BRK may be a drum type braking device (drum brake). In the case of a drum brake, the friction member MSB is a brake shoe, and the rotating member KTB is a brake drum. Similarly, the force (pressing force) by which the brake shoe presses the brake drum is controlled by the electric motor MTR. An electric motor MTR that generates torque by rotational motion is shown, but a linear motor that generates force by linear motion may be used.

<Configuration of drive means DRV (brush motor)>
FIG. 3 shows an example of driving means (driving circuit) DRV when the electric motor MTR is a motor with a brush (also simply referred to as a brush motor). DRV is an electric circuit that drives the MTR, and includes a pulse width modulation block PWM that performs pulse width modulation (PWM) based on the switching elements S1 to S4 and Imt, and a duty ratio determined by the PWM. Based on the switching control block SWT for controlling the energized / non-energized states of S1 to S4.

  The switching elements S1 to S4 are elements that can turn on / off a part of the electric circuit, and for example, MOS-FETs can be used. By S1 to S4, the forward direction of MTR (the direction in which the MSB approaches KTB and increases the braking torque) and the reverse direction (the direction in which the MSB is separated from the KTB and decreases the braking torque) ) Is configured. In the forward direction, the switching control block SWT controls S1 and S4 to be in an energized state (ON state) and S2 and S3 to be in a non-energized state (OFF state). In the reverse direction, S1 and S4 are controlled to be in a non-energized state (OFF state), and S2 and S3 are controlled to be in an energized state (ON state).

  In PWM, the duty ratio of the pulse width (ratio of ON / OFF time) is determined based on the magnitude of Imt, and the rotation direction of the MTR is determined based on the sign of Imt (positive sign or negative sign). Is done. For example, the rotation direction of the MTR can be set such that the forward rotation direction is a positive (plus) value and the reverse rotation direction is a negative (minus) value. Since the final output voltage is determined by the input voltage (BAT voltage) and the duty ratio, the rotation direction and output torque of the MTR are controlled by DRV.

<Configuration of driving means DRV (3-phase brushless motor)>
FIG. 4 is an example of drive means (drive circuit) DRV when the electric motor MTR is a brushless motor. DRV is an electric circuit that drives the MTR, and includes switching elements Z1 to Z6, a pulse width modulation block PWM that performs pulse width modulation based on Imt, and Z1 to Z6 based on a duty ratio determined by PWM. The switching control block SWT controls the energized / non-energized state.

  In the brushless motor, the position acquisition unit MKA acquires the rotor position (rotation angle) Mka of the MTR. Based on Mka, the directions of the coil energization amounts of the U-phase, V-phase, and W-phase (that is, the excitation directions) are sequentially switched by Z1 to Z6 controlled by the SWT, and the MTR is driven. The rotation direction (forward rotation or reverse rotation) of the brushless motor is determined by the relationship between the rotor and the excitation position.

  In a brushless motor, similarly to the brush motor, the duty ratio of the pulse width is determined by PWM based on the magnitude of Imt, and the rotation direction of the MTR is determined based on the sign (value sign) of Imt. The Then, based on the target energization amount Imt, the switching elements Z1 to Z6 are controlled by signals from the SWT, whereby the rotation direction and output torque of the MTR are controlled.

<Overall configuration of control means>
As shown in FIG. 5, the control means CTL includes a target pushing force calculation block FBT, a target pushing force correction calculation block FBU, an instruction energization amount calculation block IST, a pushing force feedback control block IPT, an inertia compensation control block INR, a wheel slip state. The amount calculation block SLP, the slip suppression control block FAE, the sudden stop control block QTC, and the energization amount adjustment calculation block IMT are configured. The control means CTL is programmed in the electronic control unit ECU.

  An operation amount Bpa of the braking operation member BP (for example, a brake pedal) is acquired by the braking operation amount acquisition means BPA. The operation amount (braking operation amount) Bpa of the braking operation member is calculated based on the MC pressure (master cylinder pressure). Further, it can be calculated based on at least one of an operation force (for example, brake pedal force) of a braking operation member by a driver and a displacement amount (for example, a brake pedal stroke). Bpa is subjected to arithmetic processing such as a low-pass filter, and noise components are removed (reduced).

  In the target pushing force calculation block FBT, the target pushing force Fbt of each wheel is calculated based on the operation amount Bpa by using a preset target pushing force calculation characteristic (calculation map) CHfb. The “pressing force” is a force (pressing force) that the friction member (for example, brake pad) MSB presses the rotating member (for example, brake disc) KTB in the electric braking means (brake actuator) BRK. The target pushing force Fbt is a target value of the pushing force.

  In the calculation map CHfb, the braking force distribution of the front and rear wheels is compared to the so-called “ideal braking force distribution”, the degree of the braking force with respect to the vertical load of the front wheels (vertical force, vertical force received from the road surface) is The characteristic is set to be larger than the degree of the braking force with respect to the vertical load. When the vehicle is braked, a vertical load (also referred to as a ground load) moves from the rear wheel to the front wheel. That is, the vertical load on the rear wheel decreases and the vertical load on the front wheel increases. “Ideal braking force distribution” takes into account this vertical load movement, the ratio of the front wheel braking force to the front wheel vertical load (referred to as front wheel braking load) and the ratio of the rear wheel braking force to the rear wheel vertical load (referred to as rear wheel braking load). ) Is the same characteristic. In CHfb, the front wheel braking load is set to be larger than the rear wheel braking load. Therefore, CHfb can be set as two different characteristics, a front wheel characteristic CHfbf and a rear wheel characteristic CHfbr. For example, CHfbf can be set such that Fbt is “convex downward” as Bpa increases. Further, CHfbr can be set such that Fbt is “convex upward” as Bpa increases.

  In the target pressing force correction calculation block FBU, the target pressing force Fbt is corrected based on the calculation result (Fae and the like) of a slip suppression control block FAE described later. In FAE, slip suppression control such as anti-skid control is executed. Then, based on the corrected pressing force Fae, the target pressing force Fbt calculated based on the driver's operation of the brake pedal BP is cut off, and corrected to suppress excessive wheel slip (wheel locking tendency). A target pushing force Fbu is calculated.

  In the command energization amount calculation block IST, the command energization amount Ist is calculated based on the target pressing force Fbu corrected by Fae using preset calculation maps CHs1 and CHs2. The command energization amount Ist is a target value of the energization amount to the electric motor MTR for driving the electric motor MTR of the braking means BRK and achieving the corrected target pushing force Fbu. The calculation map (the calculation characteristic of the command energization amount) is composed of two characteristics CHs1 and CHs2 in consideration of the hysteresis of the brake actuator. The characteristic (first instruction energization amount calculation characteristic) CHs1 corresponds to the case where the pushing force is increased, and the characteristic (second instruction energization amount calculation characteristic) CHs2 corresponds to the case where the pushing force is reduced. Therefore, compared with the characteristic CHs2, the characteristic CHs1 is set to output a relatively large command energization amount Ist.

  Here, the energization amount is a state amount (variable) for controlling the output torque of the electric motor MTR. Since the electric motor MTR outputs a torque approximately proportional to the current, the current target value of the electric motor can be used as the target value of the energization amount. Further, if the supply voltage to the electric motor MTR is increased, the current is increased as a result, so that the supply voltage value can be used as the target energization amount. Furthermore, since the supply voltage value can be adjusted by the duty ratio in pulse width modulation (PWM), this duty ratio can be used as the energization amount.

  In the pressing force feedback control block IPT, the pressing force feedback energization amount Ipt is calculated based on the target pressing force (target value) Fbu and the actual pressing force (actual value) Fba. The command energization amount Ist is calculated as a value corresponding to the target pressing force Fbu, but an error (steady error) between the target pressing force Fbu and the actual pressing force (actual pressing force) Fba due to fluctuations in the efficiency of the brake actuator. ) May occur. The pushing force feedback energization amount Ipt is calculated based on a deviation (pushing force deviation) ΔFb between the target pushing force Fbu and the actual pushing force Fba and a calculation characteristic (calculation map) CHp, and the above error (steady error). ) To be reduced. Note that Fba is acquired by the pressing force acquisition means FBA.

  Inertia compensation control block INR compensates for the influence of the inertia of BRK (particularly, electric motor MTR) (inertia, inertia moment in rotational motion, or inertia mass in linear motion). In the inertia compensation control block INR, target values Ijt and Ikt of the energization amount for compensating for the influence of the BRK inertia (moment of inertia or mass of inertia) are calculated. When the electric motor is stopped or the motion (rotational motion) is accelerated from a state where the electric motor is moving at a low speed, it is necessary to improve the responsiveness of generating the pushing force. The acceleration inertia compensation energization amount Ijt corresponding to this case is calculated. Ijt is a target value of the energization amount of the acceleration control in the inertia compensation control.

  In addition, when the electric motor is decelerated and stopped from the state of motion (rotational motion), it is also necessary to suppress the overshoot of the pushing force and improve the convergence. A deceleration inertia compensation energization amount Ikt corresponding to this case is calculated. Ikt is a target value of the energization amount in the deceleration control in the inertia compensation control. Here, Ijt is a value that increases the energization amount of the electric motor (a positive sign value that is added to Ist), and Ikt is a value that decreases the energization amount of the electric motor (a negative sign value that is added to Ist). It is.

  In the wheel slip state quantity calculation block SLP, the slip state quantity Slp [**] of each wheel is calculated based on the wheel speed Vwa [**] of each wheel acquired by the wheel speed acquisition means VWA [**]. Is done. Slp is a state quantity representing the slip degree of each wheel. For example, as Slp, the difference between the wheel speed Vwa and the vehicle speed (body speed) Vso is calculated as the wheel slip speed Vsl. Further, the wheel acceleration dVw, which is the amount of time change of Vwa, can be calculated as Slp.

  In the slip suppression control block FAE, slip suppression control for each wheel is executed based on the slip state amount Slp [**] of each wheel. The slip suppression control is control for suppressing excessive slip of the wheel, and is anti-skid control (ABS control) or braking force distribution control (EBD control). ABS control is typically control that reduces braking torque applied to a wheel when the slip degree of the wheel exceeds a predetermined degree. The EBD control is typically control for maintaining braking torque applied to a wheel when the slip degree of the wheel exceeds a predetermined degree.

  In the slip suppression control block FAE, a corrected pressing force (corrected value) Fae for correcting the target pressing force Fbt determined based on Bpa is calculated. When the wheel slip increases (when the wheel tends to lock), the corrected pushing force Fae is cut off from the influence of Fbt (independent of the driver's braking operation in calculating the target pushing force). The subsequent target pressing force (target value) Fbu is calculated to decrease. Further, when the wheel slip decreases due to the decrease in Fbu (when the grip of the wheel is restored), the calculation is performed to increase Fbu.

  In the sudden stop control block QTC, a target value (abrupt stop energization amount) Iqt of the energization amount for the sudden stop control is calculated based on the slip state amount Slp [**] of the wheel. In the sudden stop control, in order to suppress an excessive slip (wheel lock tendency) due to a delay in following the actual value Fba with respect to the target value Fbu, the electric motor MTR rapidly decelerates at the maximum, This is a control to stop the rotational movement. Therefore, in QTC, the rotation of the electric motor in the direction in which the friction member MSB moves away from the rotating member KTB (the direction in which the braking torque decreases) is used as the target value (abrupt stop energization amount) Iqt of the sudden stop control. In the direction (reverse direction), the maximum amount of current that can be energized (energization limit value) imm is indicated in a stepwise manner (in a stepwise manner and instantly discontinuous from the previous Imt). The energization limit value imm is set in advance based on a value corresponding to the maximum current of MTR or DRV.

  In the energization amount adjustment calculation block IMT, a target energization amount Imt that is a final target value of the MTR is calculated. The command energization amount Ist is adjusted by the pressing force feedback energization amount Ipt, the inertia compensation energization amount Ijt (acceleration), Ikt (deceleration), and the sudden stop energization amount Iqt, and the target energization amount Imt is calculated.

  The IMT includes a priority calculation block YSN and prioritizes inertia compensation control and sudden stop control. In the priority calculation block YSN, Iqt is output with priority over Ijt and Ikt. That is, when Iqt is input simultaneously with Ijt and Ikt, Ijt and Ikt are set to zero, and the sudden stop energization amount Iqt is output.

  Specifically, in the energization amount adjustment calculation block IMT, the feedback energization amount Ipt is added to the command energization amount Ist, and any of the inertia compensation energization amounts Ijt and Ikt and the sudden stop energization amount Iqt One of them is added and the sum is calculated as the target energization amount Imt. Here, Iqt is a value (a negative sign value added to Ist) that decreases the energization amount of the electric motor. The target energization amount Imt is a final energization amount target value for controlling the output of the electric motor MTR. The direction of rotation of the MTR is controlled based on the sign of Imt (the sign of the value), and the output of the MTR is controlled based on the magnitude of Imt.

  The embodiment in which the “pressing force”, which is the pressing force of the friction member MSB against the rotating member KTB, is used as the control variable (state quantity to be controlled) has been described above. BRK specifications (CPR stiffness, GSK gear ratio, HNK lead, etc.) are known. Therefore, as a control variable, instead of the pressing force (target value Fbu, actual value Fba), “a pressing force equivalent value Fbs (target value) which is a value corresponding to the force (pressing force) by which the friction member MSB presses the rotating member KTB. Value Fst, actual value Fsa) ".

  The pressing force equivalent value Fbs can be determined based on a state quantity related to “force” representing an operating state of the movable member located in the power transmission path from the electric motor MTR to the friction member MSB. For example, the actual output torque (or target value) of the electric motor, the actual output torque (or target value) of GSK, the actual thrust (or target value) in HNK, the actual thrust (or target) in PSN Value) and the actual pressing force Fba (or target pressing force Fbu) of the MSB can be adopted as Fbs related to “force (torque)”.

  Since the rigidity (spring constant) of the entire BRK such as the brake caliper CPR is known, the state quantity related to “position” can be set to Fbs instead of the state quantity related to “force”. For example, the actual position Mka (or target position Mkt) of the electric motor, the actual position (or target position) of GSK, the actual position (or target value) in HNK, the actual position (or target) in PSN Value) and the actual position (or target value) of the MSB can be adopted as Fbs related to the “position”.

  Further, a final pressing force equivalent value Fbs can be determined based on the Fbs of the plurality of movable members. Accordingly, the “pushing force equivalent value Fbs (target pushing force equivalent value Fst, actual pushing force equivalent value Fsa)” is a movable force in the power transmission path from the MTR output torque to the MSB pushing force against KTB. It can be determined based on at least one of the state quantities related to the “force” or “position” of the member.

<Configuration of First Embodiment of Inertia Compensation Control Block>
A first embodiment of the inertia compensation control block INR will be described with reference to FIG. In the first embodiment of the inertia compensation control block INR, inertia compensation control is performed to improve the responsiveness of the pressing force due to inertia such as MTR (the inertia of the entire BRK including the inertia of the MTR) and the convergence. . The inertia compensation control block INR includes a target position calculation block MKT, a time constant calculation block TAU, a delay element calculation block DLY, a target acceleration calculation block DDM, and a coefficient storage block KSK.

  In the target position calculation block MKT, a target position (target rotation angle) Mkt is calculated based on the target pressing force Fbu and the target pressing force calculation characteristic (calculation map) CHmk. The target position Mkt is a target value for the position (rotation angle) of the electric motor MTR. The calculation map CHmk is a characteristic corresponding to the rigidity of the brake caliper CPR and the friction member (brake pad) MSB, and is stored in advance in the electronic control unit ECU as a non-linear characteristic of “upwardly convex”.

  In the time constant calculation block TAU, the time constant τm is calculated based on the corrected target pressing force (target value of the pressing force) Fbu and the time constant calculation characteristic (calculation map) CHτm. When Fbu is less than the predetermined operation amount (predetermined value) fb1, τm is calculated as a first predetermined time constant (predetermined value) τ1 (≧ 0). When Fbu is equal to or greater than the predetermined value fb1 and less than the predetermined value fb2, τm is calculated so as to sequentially increase from the first predetermined time constant τ1 to the second predetermined time constant τ2 as Fbu increases. When Fbu is greater than or equal to the predetermined value fb2, τm is calculated as a second predetermined time constant (predetermined value) τ2 (> τ1).

  In the delay element calculation block DLY, the target position (target rotation angle) Mkf after the delay element calculation processing is calculated based on the target position Mkt of the electric motor MTR. Specifically, the delay element calculation process including the time constant τm corresponding to the response of the brake actuator BRK (that is, the response of the electric motor MTR) is executed for the target position Mkt of the electric motor, and the delay element process is performed. The subsequent target position Mkf is calculated. Here, the delay element calculation is an operation of an nth order delay element (“n” is an integer equal to or greater than “1”), for example, a first order delay calculation. When the delay element process is performed at Mkt, the response of the brake actuator BRK (the state of the output change with respect to the input change) is considered as a transfer function using a time constant, and the target value Mkf corresponding to the response is obtained. Can be computed.

  In the target acceleration calculation block DDM, the target acceleration ddMkf after the delay element processing is calculated based on the target position Mkf after the delay element processing. ddMkf is a target value for the acceleration (angular acceleration) of the electric motor MTR. Specifically, Mkf is second-order differentiated and ddMkf is calculated. The ddMkf is calculated to a positive sign value when the electric motor MTR is accelerated (when starting from a stopped state), and is calculated to a negative sign value when the MTR is decelerating (toward stopping).

  The coefficient storage block KSK stores a coefficient (gain) ksk for converting the target acceleration ddMkf into the target energization amount of the electric motor. The coefficient ksk corresponds to a value obtained by dividing the inertia (constant) mtj of the electric motor by the torque constant tqk of the electric motor. Then, inertia compensation control energization amounts (target values) Ijt and Ikt are calculated based on ddMkf and ksk. Specifically, ddMkf is multiplied by ksk to calculate Ijt and Ikt.

<Configuration of Second Embodiment of Inertia Compensation Control Block>
Next, a second embodiment of the inertia compensation control block INR will be described with reference to FIG. In the inertia compensation control block INR, inertia compensation control for improving the responsiveness and convergence of the pressing force caused by inertia such as MTR (inertia of the entire BRK including inertia of MTR) is executed. The inertia compensation control block INR is a control necessity determination calculation block FLG that determines whether or not inertia compensation control is necessary, an inertia compensation energization amount calculation block IJK that calculates a target energization amount of inertia compensation control, and a selection calculation block SNT. Composed.

  In the control necessity determination calculation block FLG, it is determined whether the inertia compensation control needs to be executed or not. The control necessity determination calculation block FLG includes an acceleration determination calculation block FLJ that determines whether or not the electric motor is accelerated (for example, when the electric motor is started and accelerated), and when the electric motor is decelerated ( For example, it includes a deceleration determination calculation block FLK that determines whether or not it is necessary when the electric motor decelerates and stops.

  From the control necessity determination calculation block FLG, necessity determination flags FLj (acceleration) and FLk (deceleration) are output as determination results. In the necessity determination flags FLj and FLk, “0” represents a case where inertia compensation control is not required (unnecessary state), and “1” represents a case where inertia compensation control is necessary (necessary state).

  The control necessity determination calculation block FLG includes a time constant calculation block TAU, a delay element calculation block DLY, a second-order differentiation calculation block DDF, an acceleration determination calculation block FLJ, and a deceleration determination calculation block FLK.

  As in the first embodiment, in the time constant calculation block TAU, the time constant τm is calculated based on the corrected target pushing force (target value of pushing force) Fbu and the time constant calculation characteristic (calculation map) CHτm. Calculated. Then, in the delay element calculation block DLY, the target push force Fbf after the delay element calculation process is calculated based on the target push force Fbu. The delay element calculation block DLY is the same as that in the first embodiment, and the response of the brake actuator BRK (particularly, the electric motor MTR) is taken into consideration by a transfer function (for example, first-order delay calculation). In the second-order differential calculation block DDF, the target pushing force Fbf after the delay element processing is second-order differentiated, and ddFbf is calculated. The ddFbf is calculated as a positive sign value when the electric motor MTR is accelerated (when starting from the stopped state), and is calculated as a negative sign value when the MTR is decelerating (when moving toward the stop).

  In the acceleration determination calculation block FLJ, the inertia compensation control when the electric motor MTR accelerates based on the second-order differential value ddFbf of the target pushing force Fbf after the delay element calculation is “necessary state” and “unnecessary state”. It is determined which state is in the house. The determination result is output as a necessity determination flag (control flag) FLj. According to the calculation map DFLj, when the ddFbf exceeds the first predetermined acceleration (predetermined value) ddf1 (> 0), the necessity determination flag FLj for acceleration control is changed from “0 (unnecessary state)” to “1 (necessary). State) ”(FLj ← 1). Thereafter, when ddFbf becomes less than a predetermined acceleration (predetermined value) ddf2 (<ddf1), FLj is changed from “1” to “0” (FLj ← 0). Note that FLj is set to “0” as an initial value when a braking operation is not performed.

  In the decrease determination calculation block FLK, the inertia compensation control when the electric motor MTR decelerates based on the second-order differential value ddFbf of the target pushing force Fbf after the delay element calculation is “necessary state” and “unnecessary state”. It is determined which state is in the house. The determination result is output as a necessity determination flag (control flag) FLk. When the ddFbf falls below the second predetermined acceleration (predetermined value) ddf3 (<0) according to the calculation map DFLk, the deceleration necessity determination flag FLk is changed from “0 (unnecessary state)” to “1 (necessary). State) ”(FLk ← 1). Thereafter, when ddFbf becomes equal to or greater than a predetermined acceleration (predetermined value) ddf4 (> ddf3, <0), FLk is changed from “1” to “0” (FLk ← 0). Note that FLk is set to “0” as an initial value when a braking operation is not performed.

  Information regarding the necessity determination flags FLj and FLk for inertia compensation control is transmitted from the control necessity determination calculation block FLG to the inertia compensation energization amount calculation block IJK.

  In the inertia compensation energization amount calculation block IJK, the inertia compensation energization amount (target value) in the case where it is determined by the FLG that the inertia compensation control is necessary (when FLj = 1 or FLk = 1) is calculated. . The inertia compensation energization amount calculation block IJK includes an acceleration energization amount calculation block IJT that calculates an inertia compensation energization amount Ijt when the electric motor is accelerated (for example, when the electric motor starts and accelerates), and It includes a deceleration energization amount calculation block IKT that calculates an inertia compensation energization amount Ikt during deceleration (for example, when the electric motor decelerates and stops).

  In the acceleration energization amount calculation block IJT, the acceleration inertia compensation energization amount Ijt is calculated based on the necessity determination flag FLj and the acceleration calculation characteristic (calculation map) CHj. The acceleration calculation characteristic CHj is stored in advance in the ECU as a characteristic (calculation map) of Ijt with respect to the elapsed time T from the time when the necessity state of acceleration inertia compensation control is determined. In the calculation characteristic CHj, Ijt is sharply increased from “0” to a predetermined energization amount (predetermined value) ij1 as time elapses from the time T is “0”, and then Ijt is predetermined energization as time elapses. The amount (predetermined value) is gradually decreased from ij1 to “0”. Specifically, CHj is a time tdn that is required for Ijt to be increased from “0” to the predetermined energization amount ij1, and that is required for Ijt to be decreased from the predetermined energization amount ij1 to “0”. Is set shorter.

  In the deceleration energization amount calculation block IKT, the deceleration inertia compensation energization amount Ikt is calculated based on the necessity determination flag FLk and the deceleration calculation characteristic (calculation map) CHk. The deceleration calculation characteristic CHk is stored in advance in the ECU as an Ikt characteristic (calculation map) with respect to the elapsed time T from the point in time when the deceleration inertia compensation control is determined. CHk is abruptly decreased from “0” to a predetermined energization amount (predetermined value) ik1 as time elapses since time T is “0”, and thereafter, Ikt is reduced to a predetermined energization amount (elapsed time). The predetermined value) is gradually increased from ik1 to “0”. Specifically, CHk is the time ten required for the time tvp required for Ikt to decrease from “0” to the predetermined energization amount ik1, and the time ten required for Ikt to increase from the predetermined energization amount ik1 to “0”. Is set shorter.

  In the selection calculation block SNT, any one of the output of the inertia compensation energization amount Ijt when the electric motor is accelerated, the output of the inertia compensation energization amount Ikt when the electric motor is decelerated, and the control stop (output of the value “0”) One of them is selected and output. In the selection calculation block SNT, when the deceleration inertia compensation energization amount Ikt (<0) is output while the acceleration inertia compensation energization amount Ijt (> 0) is being output, Ikt is replaced with Ikt. It can be preferentially output.

<Configuration of Embodiments of Wheel Slip State Amount Calculation Block, Rear Wheel Slip Suppression Control Block, and Sudden Stop Control Block>
An embodiment of the wheel slip state amount calculation block SLP, the slip suppression control block FAE, and the sudden stop control block QTC will be described with reference to FIG.

<Embodiment of Wheel Slip State Quantity Calculation Block>
The wheel slip state amount calculation block SLP includes a vehicle speed calculation block VSO, a wheel slip speed calculation block VSL, and a wheel acceleration calculation block DVW. When braking torque is applied to the wheel, the wheel slips (slip between the road surface and the wheel), and braking force is generated. In the SLP, the wheel speed Vwa [**] is acquired through the wheel speed sensor VWA [**] or the communication bus, and the wheel slip state quantity Slp [indicating the degree of slip in the rotational direction of each wheel (the degree of slipping of the wheel). **] is calculated.

  In the vehicle speed calculation block VSO, the vehicle speed (body speed) Vso is calculated based on the wheel speed Vwa [**] of each wheel and a known method. For example, the fastest wheel speed Vwa [**] can be selected and calculated as the vehicle speed Vso.

  In the wheel slip speed calculation block VSL, the slip speed Vsl [**] of each wheel is calculated based on the vehicle speed Vso and the wheel speed Vwa. Vsl [**] is calculated as a negative sign (minus) value by subtracting Vso from Vwa [**].

  In the wheel acceleration calculation block DVW, the wheel acceleration dVw [**] is calculated based on the wheel speed Vwa [**] of each wheel and a known method. For example, Vwa [**] can be time differentiated to calculate dVw [**]. The wheel slip state quantity Slp [**] is a value (variable) based on at least one state quantity of the slip speed Vsl [**] and the acceleration dVw [**].

<Embodiment of slip suppression control block>
In the slip suppression control block FAE, a corrected pushing force Fae required for anti-skid control (ABS control) or braking force distribution control (EBD control) for suppressing wheel slip is calculated. The corrected pressing force Fae is a target value for correcting a target pressing force Fbt calculated based on Bpa and calculating a target pressing force Fbu for suppressing wheel slip. The slip suppression control block FAE includes an anti-skid control calculation map CHab, a braking force distribution control calculation map CHeb, and a selection calculation block SNU. The braking force distribution control is a slip suppression control dedicated to the rear wheels.

[Calculation of target push force correction value (correct push force) Fab by anti-skid control]
First, anti-skid control (ABS control) will be described. In the rear wheel slip suppression control block FAE, anti-skid control via the electric braking means BRK is executed based on the slip state amount Slp [**] of the wheel and the calculation map CHab of anti-skid control. The ABS control calculation map CHab shown in the slip suppression control block FAE is referred to, and the control mode is selected based on the magnitude relationship between Vsl [**] and dVw [**], and the corrected pushing force Fab [** ] Is determined.

  Specifically, first, the slip speed Vsl [**] of the wheel is compared with predetermined values vsa1 and vsa2. The predetermined values vsa1 and vsa2 are preset values and have a relationship of vsa1 <vsa2 <0. As the wheel slip speed is smaller, the slip degree is larger. Therefore, the value vsa1 has a higher degree of slip than the value vsa2. Further, the wheel acceleration dVw [**] is compared with predetermined values dva1 and dva2. The predetermined values dva1 and dva2 are preset values and have a relationship of dva1 (deceleration) <0 <dva2 (acceleration). Similar to the wheel slip speed, the smaller the value of the wheel acceleration, the larger the slip degree. Therefore, the value dva1 has a higher degree of slip than the value dva2.

  The ABS control mode is determined based on Vsl [**], dVw [**], and CHab. The ABS control mode includes a decrease mode in which the braking torque is reduced and an increase mode in which the braking torque is increased. The reduction mode is displayed as “decrease” in the computation map CHab, and the pressing force is reduced. Further, the increase mode is displayed as “increase” in the calculation map CHab, and the pushing force is increased.

  For example, when Vsl [**] is less than vsa1 and dVw [**] is less than dva1, the decrease mode is selected, and Vsl [**] is greater than or equal to vsa1 and less than vsa2. , DVw [**] is greater than or equal to dva1 and less than dva2, the increase mode is selected.

  In the decrease mode, the corrected pushing force Fab by the ABS control is calculated so that the target pushing force Fbu is reduced in order to reduce the wheel slip and prevent the wheel lock. In the increase mode, the corrected pressing force (corrected value) Fab is calculated so that the target pressing force Fbu is increased in order to increase the wheel slip and recover the braking force.

[Calculation of Target Push Force Correction Value (Correction Push Force) Feb by Braking Force Distribution Control]
Next, braking force distribution control (EBD control) will be described. In the braking force distribution control, the ratio between the braking force generated on the front wheels and the braking force generated on the rear wheels is adjusted by adjusting the braking torque of the rear wheels. In the slip suppression control block FAE, the braking force distribution via the rear wheel electric braking means BRK [r *] based on the rear wheel slip state quantity Slp [r *] and the braking force distribution control calculation map CHeb. Control is executed. The calculation map CHeb for EBD control shown in the slip suppression control block FAE is referred to, and the control mode is selected based on the magnitude relationship between Vsl [r *] and dVw [r *], and the corrected pushing force Feb [r * ] Is determined.

  Specifically, first, the slip speed Vsl [r *] of the rear wheel is compared with predetermined values vse1 and vse2. vse1 and vse2 are preset values and have a relationship of vse1 <vse2. The value vse1 has a higher degree of slip than the value vse2. Further, the wheel acceleration dVw [r *] is compared with predetermined values dve1 and dve2. dve1 and dve2 are preset values and have a relationship of dve1 <dve2. Similar to the slip speed, the value dve1 has a greater degree of slip than the value dve2.

  A control mode of EBD control is determined based on Vsl [r *], dVw [r *], and CHeb. Control modes for EBD control include a decrease mode in which the braking torque is reduced, a holding mode in which the braking torque is held, and an increase mode in which the braking torque is increased. The decrease mode is displayed as “decrease” in the calculation map CHeb and the pressing force is decreased, and the hold mode is displayed as “hold” in the calculation map CHeb and the pressing force is held. The increase mode is displayed as “increase” in the calculation map CHeb, and the pushing force is increased.

  For example, when Vsl [r *] is less than vse1 and dVw [r *] is less than dve1, the decrease mode is selected, and Vsl [r *] is greater than or equal to vse1 and less than vse2. , DVw [r *] is greater than or equal to dve1 and less than dve2, the hold mode is selected, Vsl [r *] is greater than or equal to vse2, and dVw [r *] is greater than or equal to dve2. The increase mode is selected.

  In the reduction mode, in order to reduce the wheel slip and secure the lateral force, the corrected pushing force Feb by the EBD control is calculated so that the target pushing force Fbu is reduced. In the holding mode, the corrected pushing force Feb is calculated so that the target pushing force Fbu is maintained. In the increase mode, in order to increase the wheel slip and increase the braking force, the corrected pressing force Feb is calculated so that the target pressing force Fbu is increased.

[Priority order of ABS control and EBD control]
In the selection calculation block SNU, in order to prevent interference between the ABS control and the EBD control, Fae output as the final correction value (corrected pressing force) is selected. When both ABS control and EBD control are not executed, the corrected push force Fae is output as “0 (the target push force Fbt is not corrected)” from the SNU. When the ABS control is executed and the EBD control is not executed, Fab is output from the SNU as the corrected pushing force Fae. On the contrary, when ABS control is not executed and EBD control is executed, Feb is output from the SNU as the corrected pushing force Fae. When the Fab based on the ABS control and the Fab based on the EBD control interfere (calculated simultaneously), the Fab is preferentially output from the selection calculation block SNU as the final corrected pressing force Fae.

<Embodiment of sudden stop control block QTC>
In the sudden stop control block QTC, sudden stop control is performed in which the MTR is suddenly decelerated and moved to stop based on the wheel slip state amount Slp [**]. The sudden stop control is a control in which the electric motor is urgently decelerated at the maximum (limit) of its capacity (performance) and the rotational motion is stopped. The QTC includes a calculation map CHqt, a start determination calculation block HJM, and an end determination calculation block OWR.

[Calculation of sudden stop energization Iqt]
In the calculation map CHqt for the sudden stop control, an energization target value (abrupt stop energization amount) Iqt [**] for the sudden stop control is calculated based on the slip state amount Slp [**] of the wheel. The calculation map CHqt is a characteristic for determining whether or not the sudden stop control is executed based on the slip state amount Slp [**]. Here, the slip state quantity Slp [**] is a state quantity based on at least one of the wheel slip speed Vsl [**] and the wheel acceleration dVw [**].

  Specifically, as shown in the calculation map (determination map) Chqt, the sudden stop control is executed (“ON” based on the mutual relationship between the slip speed Vsl [**] of the wheel and the acceleration dVw [**]. ”) Or non-execution (indicated by“ OFF ”). That is, when the condition indicated by “ON” in the figure is satisfied for the first time, the execution of the sudden stop control is started, and the sudden stop energization amount Iqt is “0 (no control is executed,“ OFF ”in the calculation map). Is immediately switched from the energization limit value (predetermined predetermined value) imm.

  That is, Iqt is a limit amount (predetermined value) that can be energized to the maximum in the direction of rotation of the electric motor (reverse direction) in the direction in which the friction member MSB moves away from the rotating member KTB (direction in which the braking torque is reduced) imm is instantly indicated (step output). Here, the energization limit value imm is a value set in advance based on the specifications of the MTR and DRV, and is a value corresponding to the maximum current that can energize the MTR or DRV. For example, the energization limit value imm is the maximum current of the winding (coil) of the electric motor MTR or the maximum current of the switching element (power transistor, etc.) constituting the drive circuit DRV of the electric motor (for example, thermally energized). It is a value corresponding to the maximum (limit) current amount to be obtained.

  The start of the sudden stop control can be determined based on the individual slip state quantities Slp [**] regardless of the mutual relationship between Vsl [**] and dVw [**]. Specifically, when the slip speed Vsl [f *] becomes a predetermined value vsq1 or less and / or when the wheel acceleration dVw [**] becomes a predetermined value dvq1 or less, Iqt is changed from “0”. The energization limit value (limit value beyond which this value is not energized) is immediately switched to imm.

[Conditions for permission to start sudden stop control]
In the start determination calculation block HJM, it is further determined whether or not Iqt calculated (determined) based on the calculation map CHqt can be output from the sudden stop control block QTC. When “control permission” is determined, Iqt determined to be the energization limit value imm is actually output at CHqt. However, if “control prohibited” is determined, even if Iqt = imm is calculated in CHqt, Iqt is not actually output (Iqt = 0 is output).

Specifically, “control permission” is determined when all of the following (condition 1) to (condition 7) are satisfied. Among (Condition 1) to (Condition 7), at least one condition may be omitted. If “control permission” is not determined, “control prohibition” is determined.
(Condition 1):
In a series of braking operations, the slip suppression control is not started before the sudden stop control is started.
The “continuous braking operation” refers to an “operation from when the driver starts the braking operation to when the operation ends”.
This condition can be determined based on Bpa and the corrected pressing force Fae.
(Condition 2):
The speed dMk of the electric motor is not less than a predetermined speed (predetermined value) dmk1.
dMk is calculated based on the position (rotation angle) Mka of the electric motor acquired by the position acquisition means (rotation angle acquisition means) MKA. Specifically, in the motor speed calculation block (angular speed calculation block) DMK, Mka is time-differentiated and dMk can be calculated.
(Condition 3):
The vehicle speed (vehicle speed) Vso is equal to or higher than a predetermined speed (predetermined value) vso1.
Vso can be calculated based on Vwa acquired by VWA.
(Condition 4):
In a series of braking operations, inertia compensation control at the time of increase is started before the start of sudden stop control.
This condition can be determined based on Ijt or FLj (see FIGS. 6 and 7).
(Condition 5):
The braking operation speed dBp is not less than a predetermined value dbp1.
dBp can be calculated based on Bpa acquired by BPA. Specifically, in the braking operation speed calculation block DBP, Bpa is time-differentiated and dBp can be calculated.
(Condition 6):
The road surface friction coefficient μm is not less than a predetermined value mu1.
μm can be acquired by the friction coefficient acquisition means MU based on a known method. Further, μm calculated by another system can be used via a communication bus in the vehicle.
(Condition 7):
The actual pressing force Fba is not less than a predetermined pressing force (predetermined value) fba1.
Fba can be obtained at FBA.

  Since the sudden stop control is intended to reduce the rotation speed of the electric motor before the start of the wheel slip suppression control, (Condition 1) can be set as the permission condition. Further, since the influence of the inertia of the electric motor correlates with the speed, (Condition 2) can be set as the permission condition. Further, since the wheel slip suppression control is not required when the vehicle speed is low, (Condition 3) can be set as the permission condition. Furthermore, as a typical example in which the influence of the inertia of the electric motor is a problem in the wheel slip suppression control, the driver is suddenly braked on a road surface having a high road surface friction coefficient (for example, a dry asphalt road surface) to accelerate the vehicle. In some cases, the wheel slip suppression control is required while the electric motor is being accelerated by the inertia compensation control at the time. Therefore, (condition 4) and (condition 6) can be permitted conditions. In addition, since inertia compensation control is necessary at the time of sudden braking, (condition 5) can be a permission condition. Furthermore, when the road surface friction coefficient is high, since the reaction force from the road surface is ensured, the actual pushing force Fba when the wheel slip increases is large. Therefore, (Condition 7) can be a permission condition.

[Termination conditions for sudden stop control]
In the end determination calculation block OWR, it is determined whether the sudden stop control is continued or ended. If “control continuation” is determined, Iqt is continuously output, but if “control end” is determined, Iqt is not output (Iqt = 0 is output).

Specifically, “control end” is determined when one of the following (condition A) to (condition D) is satisfied. Among (Condition A) to (Condition D), at least one condition may be omitted. When “control end” is not determined, “control continuation” is determined.
(Condition A):
The speed dMk of the electric motor is less than a predetermined speed (predetermined value) dmk2.
The relationship dmk2 <dmk1 is established.
(Condition B):
The vehicle speed Vso is less than a predetermined speed (predetermined value) vso2.
The relationship of vso2 <vso1 is established.
(Condition C):
After the start of the slip suppression control, the pressing force deviation ΔFb (= Fbu−Fba) is less than a predetermined deviation (predetermined value) hfb2.
(Condition D):
The duration Tqt from the start of the sudden stop control has exceeded a predetermined time (predetermined value) tqt2.
Tqc is counted and calculated by a timer from the time when Iqt is switched from “0” to the value imm.

  Since the increase in slip due to the inertia of the electric motor occurs when the speed is high, (Condition A) can be the end condition. Moreover, since slip suppression control is complete | finished when vehicle speed falls, (Condition B) can be made into an end condition. Further, if the actual value Fba follows the target value Fbu, the sudden stop control becomes unnecessary, so (Condition C) can be set as the end condition. Furthermore, since the sudden stop control is an emergency control of the electric motor, (Condition D) can be set as the end condition.

  When the calculation cycle is different for each state quantity, when the resolution of the detection value for calculating each state quantity is low, or when the values of multiple calculation periods are compared to prevent errors in the detection value or calculation value, etc. In some cases, the computation processing for compensating for the inertial effect of MTR takes time. For example, in inertia compensation control during deceleration, after a calculation process (a process with a long calculation period or a process that requires a plurality of periods for calculation) that requires more time than the calculation process of the wheel slip state quantity is performed. If the inertia compensation energization amount Ikt (absolute value thereof) is gradually increased, there may be a time delay when the MTR suddenly decelerates. On the other hand, in the sudden stop control, the energization amount that is physically possible is instructed stepwise to the MTR, so that the MTR is rapidly decelerated immediately without causing a time delay. Therefore, wheel slip can be suppressed efficiently and reliably.

  Execution (ON) / non-execution (OFF) of the sudden stop control can be performed based on the slip state amount Slp [**] of the target electric braking wheel (wheel equipped with BRK). This may be performed based on the slip state amount Slp [**] of a wheel that is different from the target electric braking wheel. For example, execution / non-execution of the sudden stop control can be determined based on the smallest state quantity among the slip state quantities Slp [**] of each wheel. That is, the execution start of the sudden stop control is determined based on the slip state amount of the wheel having the largest slip degree among the four wheels of the vehicle. In addition, when the start of the sudden stop control is determined at one of the plurality of electric braking wheels, the sudden stop control is performed even when the start of the sudden stop control is not determined at the other wheels. Can be started. The termination of the sudden stop control can be performed separately for each wheel. Thereby, compared with the case where the execution of the sudden stop control is determined based on the slip state amount of the wheels other than the wheel having the largest slip, the sudden stop control can be started earlier, and the increase of the wheel slip is increased. It can be more reliably suppressed. Further, since the end of the sudden stop control is independently determined for each wheel, a reliable transition to slip suppression control (such as anti-skid control) can be performed.

  Further, when a value obtained by dividing a braking force generated on a certain wheel by a vertical load (vertical force) acting on the wheel is called a “braking load”, in a general vehicle, the braking load on the front wheel The front / rear braking force is distributed so that is larger than the braking load of the rear wheels. In other words, with respect to the so-called “ideal braking force distribution” (front / rear braking force distribution in which the front and rear wheels are simultaneously locked), the ratio of the braking force to the front wheel vertical load is The ratio of the braking force between the front and rear wheels is determined so as to be larger than the ratio of the braking force. The braking force of the wheel is generated by a slip (slip between the road surface and the wheel) resulting from the braking torque applied to the wheel. Therefore, if the deceleration is the same, the slip degree of the front wheels is greater than the slip degree of the rear wheels. In other words, the rear wheel slip state that will increase thereafter can be predicted by the front wheel slip state amount Slp [f *]. Further, in order to maintain the vehicle stability, it is necessary to suppress the increase in slip of the rear wheel and sufficiently secure the lateral force of the rear wheel. Based on the above knowledge, in the present embodiment, it is possible to determine whether or not it is necessary to execute the sudden stop control for the rear wheel based on the slip state amount Slp [f *] of the front wheel. For this reason, compared with the aspect in which the necessity of executing the sudden stop control for the rear wheel is determined based on the slip state amount Slp [r *] of the rear wheel, the rear wheel sudden stop control is started earlier, An increase in rear wheel slip can be more reliably suppressed.

  The sudden stop control can be started based on this value by selecting the smaller state quantity among the slip state quantities Slp [f *] of the left and right front wheels. That is, the start of the sudden stop control of the rear wheel is determined based on the slip state amount of the wheel having the largest slip degree among the front wheels. In addition, when the start of the sudden stop control is determined at the rear wheel on one side among the left and right rear wheels, even if the start of the sudden stop control is not determined at the rear wheel on the other side The sudden stop control can be started. The termination of the sudden stop control can be performed separately for the left and right rear wheels. Since the execution of the sudden stop control of the rear wheel is determined based on the slip state amount of the wheel having the largest slip degree, the sudden stop control can be started earlier, and the increase in the slip of the rear wheel is more reliably suppressed. Can be done. Further, since the end of the sudden stop control is independently determined for each wheel, a reliable transition to slip suppression control (such as anti-skid control) can be performed.

<Action and effect>
Next, functions and effects of the present invention will be described with reference to FIGS. 9 and 10. FIG. 9 is an example of a time-series waveform of “when the sudden stop control is executed after the inertia compensation control during acceleration”, and FIG. 10 shows “the sudden stop control is executed during the execution of the inertia compensation control”. It is an example of a time-series waveform of “when to be performed”.

  As shown in FIG. 9, in this example, the braking operation is started by the driver at time t0, and the braking operation amount Bpa starts to increase. The target pushing force (target value) Fbu increases as Bpa increases. At time t1, inertia compensation control at the time of acceleration is started, and the target energization amount Imt of the electric motor that increases is equal to the inertia compensation control energization amount (target value) Ijt from the value based on Fbu. It is increased in the forward rotation direction (direction in which the pushing force increases). By this inertia compensation control, the actual value Fba of the pushing force also increases. Then, when the wheel slip state amount Slp [**] falls below a predetermined value (for example, vsa1, dva1), the sudden stop control is not performed at the time t4 (when the slip degree of the wheel becomes larger than the predetermined state). The execution state is switched to the execution state. At this time t4, the sudden stop control is started, and the target energization amount Imt is decreased stepwise in the reverse direction of the electric motor (the direction in which the pushing force decreases) to the energization limit value imm by the sudden stop energization amount Iqt. Is done. Here, the energization limit value imm is based on the maximum value of the current that can be energized to at least one of the electric motor MTR (for example, the motor winding) and the drive circuit DRV (for example, the element) of the electric motor, It is a preset value. By this sudden stop control, the electric motor is decelerated as much as possible in performance, and the overshoot of the actual pushing force Fba is suppressed.

  The sudden stop control is continued until the above end condition is satisfied. For example, if the end condition is satisfied before the wheel slip suppression control is started, the sudden stop control is ended at that point (t5), and Imt is returned to the value based on Fbu. If the end condition is not satisfied even when the wheel slip suppression control is started, the sudden stop control is continued. For example, in the example shown by the alternate long and short dash line in FIG. 9, the slip suppression control start determination is made at time t3. However, since the execution of the sudden stop control is maintained, the target energization amount Imt is still maintained at the energization limit value imm. Then, Imt is returned to a value based on Fbu at time t6 when the termination condition of the sudden stop control is satisfied.

  As shown in FIG. 10, when the inertia compensation control and the sudden stop control are executed simultaneously, the execution of the sudden stop control has priority. For example, when the inertia compensation control is calculated by increasing Imt from the value based on Fbu by Ijt, when the sudden stop control is started (time point u1), the inertia compensation control is set to a non-execution state. , Imt are decreased stepwise to the current limit value imm. By this sudden stop control, the MTR is instructed as much as possible in the performance of the electric motor MTR (limit value imm). As a result, an increase in wheel slip due to the inertia of the electric motor can be efficiently and reliably suppressed, and the stability of the vehicle can be ensured.

<When hydraulic braking means is provided on the front wheel and electric braking means is provided on the rear wheel>
FIG. 11 shows the configuration of the entire vehicle equipped with another embodiment of the vehicle braking control apparatus according to the present invention. The difference from the overall configuration of the vehicle shown in FIG. 1 is that the braking torque for the front wheels is applied using the braking hydraulic pressure. Hereinafter, differences will be described.

  Note that a suffix [**] or the like added to the end of various symbols indicates whether the various symbols relate to any of the four wheels. Various symbols related to four wheels, where the subscript is [**] (including the case where [**] is omitted and there is no subscript), it indicates the generic name of the four wheels. Various symbols related to the front wheel, where the subscript is [f *] (including the case where [f *] is omitted and there is no subscript), it indicates the generic name of the front wheel. In addition, various symbols relating to the rear wheel, where the subscript is [r *] (including the case where [r *] is omitted and there is no subscript) indicates the generic name of the rear wheel. For example, Vwa [**] and Vwa indicate generic names of the wheel speeds of four wheels, Svt [f *] and Svt indicate generic names of front wheel control instruction signals, Imt [r *], and Imt Indicates a general term for the target energization amount of the rear wheels. A wheel braked by the hydraulic braking means is referred to as “hydraulic braking wheel”, and a wheel braked by the electric braking means is referred to as “electric braking wheel”.

  In this vehicle, a master cylinder MC (a part of hydraulic braking means BRH described later) that generates a braking hydraulic pressure in response to an operation of a braking operation member (for example, a brake pedal) BP, a generated hydraulic pressure of the master cylinder MC ( In accordance with the master cylinder pressure), the braking torque is adjusted by the braking fluid pressure of the wheel (front wheel) WH [f *] in front of the vehicle to generate a braking force on the front wheel. (Hydraulic brake actuator) BRH and a hydraulic unit HU (part of hydraulic braking means BRH) for adjusting the braking hydraulic pressure of the front wheels independently of the master cylinder pressure are mounted. The MC is provided with a pressure sensor (one of the braking operation amount acquisition means) for detecting the master cylinder pressure Pmc, and Pmc can be used as Bpa.

  The front wheel hydraulic braking means BRH [f *] is provided with a known brake caliper CPR, wheel cylinder WCR, and friction member (for example, brake pad) MSB. When the MSB is pressed against a known rotating member (for example, a brake rotor) KTB by the braking hydraulic pressure, a frictional force is generated, a braking torque is generated on the front wheel WH [f *], and a braking force is generated on the front wheel.

  The hydraulic unit HU (a part of the hydraulic braking means BRH) includes a solenoid valve, a hydraulic pump, and an electric motor (not shown). Then, based on instruction signals (solenoid valve and electric motor drive signals) Svt [f *] for anti-skid control, traction control, vehicle stabilization control, etc. calculated by the electronic control unit ECU, the liquid for the front wheels The wheel cylinder pressure (pressure for pushing the MSB) of the pressure braking means BRH is controlled.

<Anti-skid control via hydraulic braking means for front wheels>
Next, an embodiment of slip suppression control for the front wheels will be described with reference to FIG. Since braking force distribution control (EBD control) is control limited to the rear wheels, the slip suppression control for the front wheels is anti-skid control for preventing the tendency of the wheels to lock. Based on the wheel slip speed Vsl [**] and the wheel acceleration dVw [**] calculated by the wheel slip state quantity calculation block SLP in the front wheel slip suppression control block SVT, the front wheel hydraulic braking means BRH Anti-skid control of the front wheels is performed via the (hydraulic pressure unit HU). In SVT, an instruction signal Svt [f *] for driving the solenoid valve constituting the hydraulic unit HU and the hydraulic pump / electric motor is calculated.

  Based on the front wheel slip state amount Slp [f *] (Vsl [f *], dVw [f *]) and the anti-skid control calculation map CHfa, the anti-skid control of the front wheels via the front wheel braking means BRH is performed. Executed. Specifically, first, the slip speed Vsl [f *] of the front wheels is compared with predetermined values vsb1 and vsb2. The predetermined values vsb1 and vsb2 are preset values and have a relationship of vsb1 <vsb2 <0. The smaller the wheel slip speed value, the greater the slip degree. The value vsb1 is more slippery than the value vsb2. Further, the acceleration dVw [f *] of the front wheels is compared with predetermined values dvb1 and dvb2. The predetermined values dvb1 and dvb2 are preset values and have a relationship of dvb1 (deceleration) <0 <dvb2 (acceleration). Similar to the wheel slip speed, the smaller the wheel acceleration value, the greater the slip degree. The value dvb1 is more slippery than the value dvb2.

  Then, the control mode of the ABS control is determined based on Vsl [f *], dVw [f *], and CHfa. The ABS control mode includes a decrease mode in which the braking torque is reduced and an increase mode in which the braking torque is increased. The decrease mode is displayed as “decrease” in the calculation map CHfa, and the brake fluid pressure is decreased. Further, the increase mode is displayed as “increase” in the calculation map CHfa, and the brake fluid pressure is increased. For example, if Vsl [f *] is less than vsb1 and dVw [f *] is less than dvb1, the decrease mode is selected, and Vsl [f *] is greater than or equal to vsb1 and less than vsb2. , DVw [f *] is greater than or equal to dvb1 and less than dvb2, the increase mode is selected.

  In the decrease mode, the instruction signal Svt for the electric motor that drives the solenoid valve in the HU and the hydraulic pump is reduced so that the brake hydraulic pressure is reduced to reduce wheel slip and prevent wheel lock. Calculated. In the increase mode, the instruction signal Svt is calculated so as to increase the brake fluid pressure in order to increase the wheel slip and recover the braking force.

<Slip suppression control via electric braking means for rear wheels>
In the rear wheel slip suppression control block FAR, slip suppression control (anti-skid control, braking force distribution control) using the electric braking means BRK [r *] is executed. Similarly to the FAE described with reference to FIG. 8, Vsl [r *] is compared with the predetermined values vsc1 and vsc2, and dVw [r *] is compared with the predetermined values dvc1 and dvc2, thereby reducing the braking torque. The “mode” and “increase mode” are determined, and the corrected pushing force Fac is calculated. Also, Vsl [r *] is compared with the predetermined values vse1 and vse2, and dVw [r *] is compared with the predetermined values dve1 and dve2, so that the braking torque “holding mode”, “decreasing mode”, and “increasing” The mode "is determined, and the corrected pushing force Feb is calculated. Then, in the selection calculation block SNU, any one of control non-execution (Far = 0), a corrected pushing force Fac by anti-skid control, and a corrected pushing force Feb by braking force distribution control is output.

<Execution of sudden stop control of rear wheel based on front wheel slip state quantity Slp [f *]>
In the sudden stop control block QTC, it is determined whether or not the sudden stop control can be performed based on the slip state amount Slp [f *] of the front wheels. That is, sudden stop based on the front wheel slip state quantity Slp [f *] (a state quantity based on at least one of the front wheel slip speed Vsl [f *] and the front wheel acceleration dVw [f *]). A control energization target value (abrupt stop energization amount) Iqt is calculated. As shown in the calculation map (determination map) Chpt similar to FIG. 8, the sudden stop control is executed ("ON") based on the mutual relationship between the front wheel slip speed Vsl [f *] and the acceleration dVw [f *]. Or non-execution (indicated by “OFF”). When the condition indicated by “ON” in the figure is satisfied for the first time, the execution of the sudden stop control is started, and the sudden stop energization amount Iqt is indicated as “0” (control is not executed, “OFF” in the calculation map) .) ”Is instantaneously switched from the current limit value (predetermined value) imm.

  Further, the start of the sudden stop control can be determined based on the individual slip state quantities Slp [f *] regardless of the mutual relationship between Vsl [f *] and dVw [f *]. Specifically, when the slip speed Vsl [f *] becomes a predetermined value vsp1 or less and / or when the wheel acceleration dVw [f *] becomes a predetermined value dvp1 or less, Iqt is changed from “0”. The energization limit value (limit value beyond which this value is not energized) is immediately switched to imm.

  Both the front wheel anti-skid control and the rear wheel sudden stop control are controlled based on the front wheel slip state quantity Slp [f *]. In the relationship between the two, the sudden stop control can be started earlier than the front wheel anti-skid control. Specifically, the slip speed start threshold value vsp1 for sudden stop control is set to a value larger than the slip speed start threshold value vsb1 for front wheel anti-skid control (vsp1> vsb1). The smaller the wheel slip speed value is, the larger the slip degree is, and the larger the value is, the smaller the slip degree is. Therefore, the sudden stop control is started with a “front wheel slip degree” smaller than the front wheel anti-skid control. Similarly, the wheel acceleration start threshold value dvp1 for the sudden stop control is set to a value larger than the wheel acceleration start threshold value dvb1 for the front wheel anti-skid control (dvp1> dvb1). The smaller the wheel acceleration value is, the larger the slip degree is, and the larger the value is, the smaller the slip degree is. Therefore, the sudden stop control can be started with a “front wheel slip degree” smaller than the front wheel anti-skid control. Therefore, the sudden stop energization amount Iqt is calculated and output before the brake fluid pressure of the front wheels is reduced. Since the MTR suddenly stops with a slight increase in slip, an increase in rear wheel slip can be reliably suppressed.

  The sudden stop control can be started based on this value by selecting the smaller state quantity among the slip state quantities Slp [f *] of the left and right front wheels. That is, the start of the sudden stop control of the rear wheel is determined based on the slip state amount of the wheel having the largest slip degree among the front wheels. In addition, when the start of the sudden stop control is determined at the rear wheel on one side among the left and right rear wheels, even if the start of the sudden stop control is not determined at the rear wheel on the other side The sudden stop control can be started. The termination of the sudden stop control can be performed separately for the left and right rear wheels. Since the execution of the sudden stop control of the rear wheel is determined based on the slip state amount of the wheel having the largest slip degree, the sudden stop control can be started earlier, and the increase in the slip of the rear wheel is more reliably suppressed. Can be done. Further, since the end of the sudden stop control is independently determined for each wheel, a reliable transition to slip suppression control (such as anti-skid control) can be performed.

  In a configuration in which the front wheel is a hydraulic braking wheel and the rear wheel is an electric braking wheel, the target pushing force Fbt [r *] of the rear wheel is determined based on Bpa based on Bpa in consideration of vertical load fluctuations during braking of the vehicle. The braking load (a value obtained by dividing the braking force by the vertical load, which represents the load state of the wheel) is determined to be larger than the braking load of the rear wheel. Specifically, the target pushing force Fbt [r *] is calculated using a characteristic CHfb (see FIG. 5) in which the front wheel braking load is larger than the rear wheel braking load. Here, CHfb can be set such that Fbt is increased “convex upward” as Bpa increases. A wheel having a large braking load (a ratio between a vertical force and a braking force) is likely to have a higher degree of slip than a wheel having a small braking load. Since the rear wheel sudden stop control is executed based on the slip state amount of the front wheel having a large braking load, the sudden stop control can be started earlier and the increase in the rear wheel slip can be more reliably suppressed.

<Other embodiments>
[Other Embodiments in Sudden Stop Control (Dynamic Brake)]
Hereinafter, a second embodiment of the sudden stop control block QTC will be described with reference to FIGS. 3 to 5, FIG. 8, and FIG.

  In the first embodiment of the QTC, as the sudden stop control, the target energization amount Imt of the electric motor is switched stepwise to the energization limit value imm by the sudden stop energization amount Iqt (FIGS. 5, 8, and FIG. 12). In the second embodiment, instead of this, when the execution of the sudden stop control is started, Imt is set to “0”, and the terminals of the electric motor are short-circuited via an electric resistance (for example, a resistor). . The electric motor MTR is suddenly decelerated by a so-called dynamic brake (also referred to as a dynamic brake) to stop its movement. Here, since an electrical resistance exists in the short circuit, a resistor (resistor) is not necessarily required. The control flag FLqt [**], which will be described later, is output from the QTC, the Imt is set to “0”, and the terminals of the electric motor are short-circuited, and the first described with reference to FIGS. 5 and 8 Since it is the same as that of embodiment, description is abbreviate | omitted.

  As a result of comparing the wheel slip state amount Slp [**] (or the front wheel slip state amount Slp [f *]) with a predetermined value (vsa1, etc.), the calculation characteristic CHqt shown in FIG. 8 (or FIG. 12) is obtained. When the condition indicated by “ON” is satisfied, the execution start of the sudden stop control is determined. At this time, “1 (execution of control)” is output from the QTC as the control flag FLqt. When Slp [**] (or Slp [f *]) is in a state indicated by “OFF” in CHqt (when it is determined that the sudden stop control is not executed), the control flag FLqt "0 (non-execution of control)" is transmitted (FLqt = 0). Then, in the switching control block SWT, the switching element is received so that the sudden stop control execution flag FLqt is “1” and the terminals of the electric motor are short-circuited via an electric resistance. Is driven and the target energization amount Imt is reduced to “0”.

  In the configuration of the driving means DRV shown in FIG. 3 (driving circuit for the brush motor), the execution start of the sudden stop control is determined, and the control flag FLqt is changed from “0 (non-execution state)” to “1 (execution state). ) ", The switching elements S1 and S2 are energized, the switching elements S3 and S4 are de-energized, and the terminals Ts and Tb of the electric motor are short-circuited. The Alternatively, the switching elements S3 and S4 can be energized, the switching elements S1 and S2 can be de-energized, and the terminals of the electric motor MTR (between Ts and Tb) can be short-circuited. Here, at the same time that the terminals of the electric motor are short-circuited via the electric resistance, the target energization amount Imt of the MTR is reduced to “0 (non-energized state)”.

  In the configuration of the driving means DRV shown in FIG. 4 (driving circuit for brushless motor), at the time when execution of the sudden stop control is determined (FLqt ← 1), two or more of the switching elements Z1 to Z3 are used. The elements are energized, all the switching elements Z4 to Z6 are de-energized, and at least one of the terminals Tu, Tv and Tw of the electric motor is short-circuited (short-circuited). Is done. In addition, two or more elements among the switching elements Z4 to Z6 are energized, all the elements of the switching elements Z1 to Z3 are deenergized, and at least one set of the three terminals is short-circuited. obtain. As in the case of DRV in FIG. 3, the target energization amount Imt is set to “0” at the same time as the terminals of the electric motor are short-circuited via the electric resistance.

  Further, an individual switching circuit (for example, a relay circuit) may be provided between the terminals of the electric motor. In this case, the terminals of the electric motor can be short-circuited via an electric resistance (resistor) without using the switching element (S1 or the like). Similarly to the above, the switching circuit is driven by a signal from the switching control block SWT based on the control flag FLqt indicating execution / non-execution of the sudden stop control. That is, based on the signal, the relay between terminals of the electric motor can be switched to an energized (ON) state or a non-energized (OFF) state.

  Electric power generated using the electric motor as a generator is consumed by the electric resistance by a dynamic brake that short-circuits the terminals of the electric motor via an electric resistance (for example, a resistor). As a result, braking torque is applied to the electric motor MTR, and the electric motor MTR is decelerated. That is, the regenerative electric power generated by the kinetic energy (rotational energy) of the MTR is consumed by the electric resistance inside the electric motor including the drive circuit DRV, so that the MTR can be stopped quickly. In addition, since an electrical resistance may exist in the circuit formed by the short circuit between terminals of an electric motor, an individual resistor may not be provided.

[Other Embodiments of Inertia Compensation Control]
In the first embodiment of the inertia compensation control block INR (see FIG. 6), Mkt is calculated based on Fbu, and Ijt and Ikt are finally determined. For the same reason as described above for the “pushing force equivalent value Fbs”, the state quantity related to the “force” of the movable member in the power transmission path from the output of the MTR to the pushing force of the MSB, There is a correlation with the state quantity related to “position”. For example, Fbu and Mkt can be calculated based on CHmk with correlation. Therefore, instead of Mkt, the value Fsf after the delay processing of the target value (target equivalent force value) Fst of Fbs is second-order differentiated, and Ijt and Ikt can be calculated based on the second-order derivative value ddFsf.

  Similarly, in the second embodiment of INR (see FIG. 7), FLj and FLk are calculated based on the second-order differential value ddFbf of Fbu, but ddFsf (target pressing force equivalent value delayed by DLY) FLj, FLk can be calculated on the basis of the second-order differential value).

  BRK: Electric braking means, BRH: Hydraulic braking means, ECU: Electronic control unit, MTR ... Electric motor, VWA ... Wheel speed acquisition means, SLP ... Slip state amount calculation means, CTL ... Control means, MKA ... Rotation position acquisition means DMK: rotational speed acquisition means, BPA: operation amount acquisition means

Claims (4)

Electric braking means for generating a braking torque via an electric motor for an electric braking wheel which is a part or all of four wheels of the vehicle;
Wheel speed acquisition means for acquiring the speeds of the four wheels of the vehicle;
A slip state amount calculating means for calculating a slip state amount representing a slip degree of the four wheels of the vehicle based on the speeds of the four wheels;
Based on the slip state amount of the electric braking wheel, a target energization amount of the electric motor is calculated to execute slip suppression control that suppresses slipping of the electric braking wheel, and the electric braking is performed based on the target energization amount. Control means for controlling the electric motor for wheels;
In a vehicle braking control apparatus comprising:
The control means includes
Based on the slip state amount of the first wheel which is one of the four wheels, the target energization amount is adjusted to execute the sudden stop control for suddenly stopping the motion of the electric motor, and the adjusted Configured to control the electric motor for the electric braking wheel based on the target energization amount,
As the sudden stop control,
When the start of the sudden stop control is determined, the target energization amount of the electric motor is configured to change stepwise to a preset energization limit value corresponding to the deceleration direction of the electric motor ,
The control means includes
A braking control device for a vehicle configured to determine the start of the sudden stop control on the condition that the slip suppression control of the electric braking wheel is not executed . Electric braking means for generating a braking torque via an electric motor for an electric braking wheel which is a part or all of four wheels of the vehicle;
Wheel speed acquisition means for acquiring the speeds of the four wheels of the vehicle;
A slip state amount calculating means for calculating a slip state amount representing a slip degree of the four wheels of the vehicle based on the speeds of the four wheels;
Based on the slip state amount of the electric braking wheel, a target energization amount of the electric motor is calculated to execute slip suppression control that suppresses slipping of the electric braking wheel, and the electric braking is performed based on the target energization amount. Control means for controlling the electric motor for wheels;
In a vehicle braking control apparatus comprising:
The control means includes
Based on the slip state amount of the first wheel which is one of the four wheels, the target energization amount is adjusted to execute the sudden stop control for suddenly stopping the motion of the electric motor, and the adjusted Configured to control the electric motor for the electric braking wheel based on the target energization amount,
As the sudden stop control,
When the start of the sudden stop control is determined, the target energization amount of the electric motor is configured to change stepwise to a preset energization limit value corresponding to the deceleration direction of the electric motor,
The control means includes
A vehicle braking control device configured to determine the start of the sudden stop control when the slip degree of the first wheel represented by the slip state amount of the first wheel exceeds the first degree . Electric braking means for generating a braking torque via an electric motor for an electric braking wheel which is a part or all of four wheels of the vehicle;
Wheel speed acquisition means for acquiring the speeds of the four wheels of the vehicle;
A slip state amount calculating means for calculating a slip state amount representing a slip degree of the four wheels of the vehicle based on the speeds of the four wheels;
Based on the slip state amount of the electric braking wheel, a target energization amount of the electric motor is calculated to execute slip suppression control that suppresses slipping of the electric braking wheel, and the electric braking is performed based on the target energization amount. Control means for controlling the electric motor for wheels;
In a vehicle braking control apparatus comprising:
The control means includes
Based on the slip state amount of the first wheel which is one of the four wheels, the target energization amount is adjusted to execute the sudden stop control for suddenly stopping the motion of the electric motor, and the adjusted Configured to control the electric motor for the electric braking wheel based on the target energization amount,
As the sudden stop control,
When the start of the sudden stop control is determined, the target energization amount of the electric motor is configured to change stepwise to a preset energization limit value corresponding to the deceleration direction of the electric motor,
The vehicle braking control device further includes an operation amount acquisition means for acquiring an operation amount of a braking operation member by a driver of the vehicle,
The control means includes
The electric braking wheel is configured to adjust the target energization amount of the electric motor to a value corresponding to the operation amount,
The control means includes
Based on the operation amount, it is determined whether to execute inertia compensation control for compensating the influence of inertia of the electric braking means for the electric braking wheel, and when the execution of the inertia compensation control is determined, An inertia compensation control for increasing a target energization amount of the electric motor from a value corresponding to the operation amount;
The control means includes
A braking control device for a vehicle configured to stop the inertia compensation control and execute only the sudden stop control when it is determined that the sudden stop control is started during the execution of the inertia compensation control . Electric braking means for generating a braking torque via an electric motor for an electric braking wheel which is a part or all of four wheels of the vehicle;
Wheel speed acquisition means for acquiring the speeds of the four wheels of the vehicle;
A slip state amount calculating means for calculating a slip state amount representing a slip degree of the four wheels of the vehicle based on the speeds of the four wheels;
Based on the slip state amount of the electric braking wheel, a target energization amount of the electric motor is calculated to execute slip suppression control that suppresses slipping of the electric braking wheel, and the electric braking is performed based on the target energization amount. Control means for controlling the electric motor for wheels;
In a vehicle braking control apparatus comprising:
The control means includes
Based on the slip state amount of the first wheel which is one of the four wheels, the target energization amount is adjusted to execute the sudden stop control for suddenly stopping the motion of the electric motor, and the adjusted Configured to control the electric motor for the electric braking wheel based on the target energization amount,
As the sudden stop control,
When the start of the sudden stop control is determined, the target energization amount of the electric motor is configured to change stepwise to a preset energization limit value corresponding to the deceleration direction of the electric motor,
The vehicle braking control device further includes motor speed acquisition means for acquiring the speed of the electric motor,
The control means includes
A vehicle braking control device configured to determine the start of the sudden stop control on condition that the speed of the electric motor is equal to or higher than a first predetermined speed .

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