JP6082945B2 - Electric braking device for vehicle - Google Patents

Description

  The present invention relates to an electric braking device for a vehicle.

  Patent Document 1 states that “it is mounted on a vehicle body for the purpose of providing a vehicle power supply device capable of supplying required electric power to each in-vehicle electrical device even when one power source fails”. A first system for supplying the first electrical energy to the first predetermined vehicle-mounted electrical device from the one power source that has been connected, and a second power source mounted on the vehicle body to the second predetermined vehicle-mounted electrical device. A second system for supplying the second electrical energy, and conversion supply means for converting the second electrical energy into the first electrical energy and supplying the first electrical energy to the first system ”. ing.

  Further, in Patent Document 1, “the remaining energy detecting means for detecting the remaining electric energy of each of the one power source and the other power source, and the one power source or the above based on the remaining electric energy of each power source, And a power supply selection unit that selects any one of the conversion supply units and connects to the first system ”.

  In Patent Document 2, “communication circuit, control circuit, and motor are driven” for the purpose of “reducing the cost of the power line for electrically connecting the vehicle body side and the wheel side and providing an inexpensive brake device”. A drive control device equipped with a drive circuit is installed on the wheel side, and power is supplied from the vehicle body side to the drive control device via two power lines to drive a motor mounted on the wheel to generate a braking force. Is described.

  In a vehicle having a plurality of power sources exemplified in Patent Document 1, when the electric braking device exemplified in Patent Document 2 is adopted, two power lines are required for the device. Even when power corresponding to the maximum output of the device is supplied via the power line, a power line that is somewhat thick (having a large cross-sectional area) is required to minimize the voltage drop across the power line. It becomes. If the power line is thick, the power line is difficult to bend. The wheel is displaced relative to the vehicle body via the suspension. Therefore, in the electric braking device, a configuration in which a power line that electrically connects the vehicle body side and the wheel side is easily bent is desired.

JP 2000-31444 A Japanese Patent No. 4154833

  The present invention has been made to cope with the above problem, and an object thereof is to provide an electric braking device in which a power line that electrically connects the vehicle body side and the wheel side is easily bent.

  An electric braking device for a vehicle according to the present invention includes a rotating member (KTB) fixed to a vehicle wheel (WHL), an electric motor (MTR) provided on the wheel (WHL) side, and the electric motor (MTR). ) Is applied to the vehicle body (BDY) side of the vehicle, and the friction member (MSB) that presses the rotating member (KTB) using the driving torque of the wheel (WHL) to generate braking torque. An energization target value (Imt) of the electric motor (MTR) is calculated based on a vehicle body power supply (BBD, ALT) that supplies power to the electric motor (MTR) and a braking operation by the driver of the vehicle, and the energization target value ( Control means (CTL) for controlling the electric motor (MTR) based on Imt).

  The device is characterized in that it is provided on the wheel (WHL) side and includes a wheel power source (BWH) for supplying electric power to the electric motor (MTR). The control means (CTL) has a current supply target value (Imt) of the first. When it is less than one threshold value (imx), the electric motor (MTR) is driven using only the vehicle body power supply (BBD, ALT), and the energization target value (Imt) is the first threshold value (Imt). In the case of imx) or more, the electric motor (MTR) is driven using the vehicle body power supply (BBD, ALT) and the wheel power supply (BWH).

  According to this, at the time of a normal braking request where the response of the braking torque is not so necessary (Imt <imx), electric power is supplied only from the vehicle body power supply BBD, and the electric motor MTR is driven. On the other hand, when sudden braking is required (Imt ≧ imx) where braking torque response is required, electric power is supplied from the wheel power source BWH in addition to the vehicle body power source BBD, and the electric motor MTR is driven. In other words, when a large amount of electric power is required for the electric motor MTR, electric power is assisted from the wheel power source BWH. Therefore, it is not necessary to assume a situation in which a large amount of power from the vehicle body power supply BBD is supplied to the electric motor MTR via the “power line that electrically connects the vehicle body side and the wheel side”. As a result, a relatively thin wiring (a conducting wire having a small cross-sectional area) can be adopted as the power line. As a result, the flexibility of the power line (wiring) can be ensured.

  In this apparatus, the control means (CTL) compensates for the influence of inertia of the “force transmission mechanism that moves in relation to generation of braking torque from the electric motor (MTR) to the friction member (MSB)”. A compensation energization amount (Ikt) may be calculated, and the energization target value (Imt) may be calculated based on the inertia compensation energization amount (Ikt). In this case, the control means (CTL) determines that the energization target value (Imt) is “after that, when the energization target value (Imt) reaches the first threshold value (imx) while increasing the energization target value (Imt)”. From the time point (t3) when the second threshold value (imy) smaller than the first threshold value (imx) is reached while decreasing, until the time point (t5) when a predetermined time (tx) has passed " It is preferable that the electric motor (MTR) is driven using a power source (BBD, ALT) and the wheel power source (BWH).

  It is assumed that control for compensating the inertia of the force transmission mechanism (in particular, the electric motor MTR) (hereinafter referred to as “inertia compensation control”) is executed. Details of the inertia compensation control will be described later. In this case, when the condition of Imt ≧ imx is satisfied, after the inertia compensation control is completed (that is, after Imt <imy (<imx)), the condition of Imt ≧ imx is satisfied again. (See FIG. 5A described later). The above configuration is based on such knowledge. In the above configuration, power supply assistance from the wheel power supply BWH is not terminated at the time point (t3) when Imt <imy, and power supply assistance from the wheel power supply BWH at a time point (t5) when the predetermined time tx is continued from that time point. Is terminated. As a result, complicated switching of the power source serving as the power supply source can be suppressed. Since the second threshold value imy is set to a value smaller than the first threshold value imx, the determination hunting (disturbance) when the target energization amount Imt slightly changes near the value imx is also performed. Can be suppressed.

1 is an overall configuration diagram of an electric braking device for a vehicle according to an embodiment of the present invention. FIG. 2 is an overall configuration diagram of an electronic control unit, a vehicle body power supply, and braking means illustrated in FIG. 1. It is a functional block diagram of a drive means in case a motor with a brush is adopted, and an electric circuit diagram. It is a figure for demonstrating supply of the electric power to an electric motor. It is a time chart for demonstrating the electric power feeding assistance by a wheel power supply.

  Hereinafter, an electric braking device for a vehicle according to an embodiment of the present invention will be described with reference to the drawings.

<Overall Configuration of Electric Brake Device for Vehicle according to Embodiment of the Present Invention>
FIG. 1 shows a state where an electric braking device according to an embodiment of the present invention is mounted on a vehicle. The electric braking device generates a braking force on the wheel by applying a braking torque to the wheel according to an operation amount of a braking operation member (for example, a brake pedal) by the driver, and decelerates the traveling vehicle.

  A vehicle body power supply (first power supply) BBD is provided (fixed) to the vehicle body BDY. The vehicle body power supply (storage battery) BBD supplies electric power to the electronic control unit ECU and the braking means (brake actuator) BRK. Further, an alternator ALT is provided on the vehicle body BDY. The vehicle body power supply BBD is charged by the alternator ALT.

  An electronic control unit ECU is provided (fixed) on the vehicle body BDY. In the electronic control unit ECU, the drive signal of the electric motor MTR is calculated based on the braking operation amount Bpa, and the drive means (electric circuit for driving the MTR) in the BRK via the signal line (for example, serial communication bus) SCB. Sent to DRV. Electric power for driving the electric motor MTR is supplied from the vehicle body power supply BBD to the DRV via the ECU and the vehicle body power line PBD.

  Driving means DRV is provided (fixed) in the caliper CPR. The drive means DRV is a drive circuit (electric circuit) for driving the electric motor MTR, and includes a control means CTL, a bridge circuit HBR composed of switching elements (for example, MOS-FET), a noise reduction circuit NIZ, and And wheel power source BWH. In the control means CTL programmed in the DRV, the switching element is driven based on the MTR drive signal (for example, the target pressing force Fbt) transmitted from the ECU, and the rotational direction and rotational power of the MTR are controlled. The

  At the time of normal braking request (when Imt <imx described later), electric power for driving the electric motor MTR is supplied from the vehicle body power supply (first power supply) BBD to DRV (that is, MTR via the switching element). Supplied. This power supply is performed via the ECU and the vehicle body power line PBD. Further, when sudden braking is requested (when Imt ≧ imx described later), electric power is supplied to the electric motor MTR by the wheel power source (second power source) BWH in addition to the vehicle body power source BBD.

  The wheel power source (second power source) BWH is charged during normal running (when braking is not required) by energization from the vehicle body power source (first power source) BBD. This charging (power feeding from BBD to BWH) is performed through the ECU and the vehicle body power line PBD. The signal line (for example, serial communication bus) SCB and the vehicle body power line PBD are collectively referred to as “wiring (wire harness)”.

  Power line communication in which the vehicle body power line PBD is also used as a signal line (communication line) SCB may be employed. In this case, the SCB is integrated into the PBD (that is, the SCB is omitted), and the electric motor drive signal is superimposed on the PBD and transmitted to the DRV. Here, power line communication is also referred to as power line communication (PLC). By adopting power line communication, a communication system that performs high-speed data communication using the power supply wiring PBD can be obtained.

  One side of the suspension arm (for example, the upper arm UAM, the lower arm LAM) is attached to the vehicle body BDY of the vehicle, and the other side is attached to the knuckle NKL. The coil spring SPR and the shock absorber SHA are attached to a suspension arm or a knuckle NKL. The wheel WHL is suspended from the vehicle body BDY by the coil spring SPR and the shock absorber SHA. The suspension arm, SPR, NKL, and SHA are members constituting a known suspension device.

  The hub bearing unit HBU is fixed to the knuckle NKL. The wheel WHL is supported by a hub bearing in the hub bearing unit HBU. A rotating member (brake disc) KTB is fixed to the wheel WHL, and the KTB is rotated integrally with the WHL (that is, the rotating shaft of the KTB and the rotating shaft of the WHL are coaxial).

  The mounting bracket MTB is fixed to the knuckle NKL by fastening members (for example, bolts) TK1 and TK2 (not shown). A caliper CPR is attached to the MTB via slide pins GD1, GD2 (not shown). The brake caliper CPR is a floating caliper and is configured to sandwich a rotating member (brake disk) KTB via two friction members (brake pads) MSB. Specifically, the slide pins GD1 and GD2 are fixed to the mounting bracket MTB, and the pressing member (piston) PSN in the caliper CRP is slid by the electric motor MTR along the GD1 and GD2 toward the rotating member KTB. .

<Whole structure of electronic control unit ECU, vehicle body power supply BBD, and braking means BRK>
As shown in FIG. 2, a vehicle including this electric braking device includes a braking operation member BP, an electronic control unit ECU, a vehicle body power supply (storage battery, etc.) BBD, and a braking means (brake actuator) BRK. Here, the ECU and BRK are connected by a signal line (signal line) SCB and a vehicle body power line (power line) PBD via an ECU side connector CNB and a BRK side connector CNC. The BRK is supplied with an MTR drive signal and electric power from the ECU.

  The braking operation member (for example, brake pedal) BP is a member that the driver operates to decelerate the vehicle. Based on the operation amount of BP, the braking means (brake actuator) BRK adjusts the braking torque of the wheel WHL, the braking force is generated on the wheel WHL, and the running vehicle is decelerated.

  The braking operation member BP is provided with a braking operation amount acquisition means BPA. The operation amount (braking operation amount) Bpa of the braking operation member BP by the driver is acquired (detected) by the braking operation amount acquisition means BPA. As a braking operation amount acquisition means BPA, a sensor (pressure sensor) for detecting the pressure of a master cylinder (not shown), an operation force of the braking operation member BP, and / or a sensor for detecting a displacement amount (a brake pedal depression force sensor, Brake pedal stroke sensor) is adopted.

  Accordingly, the braking operation amount Bpa is calculated based on at least one of the master cylinder pressure, the brake pedal depression force, and the brake pedal stroke. The braking operation amount Bpa is input to the electronic control unit ECU. Bpa is calculated or acquired by another electronic control unit, and the calculated value (signal) can be transmitted to the ECU via the communication bus.

  The vehicle body power supply (first power supply) BBD is a power supply fixed to the vehicle body BDY. The vehicle body power supply BBD supplies power to the electronic control unit ECU provided on the vehicle body side. As the vehicle power source BBD, a rechargeable secondary battery (also referred to as a storage battery or a rechargeable battery) may be employed. Here, the secondary battery is one of batteries (chemical battery) that converts chemical energy of a substance into direct-current power by a chemical reaction, and can store electricity by charging and can be used repeatedly.

  Specifically, in the secondary battery, the internal chemical energy is converted into electrical energy during the discharge process, and the current is passed in the opposite direction to that during discharge, thereby converting the electrical energy into chemical energy and storing the energy. Is done. The body power supply BBD is charged by an alternator (generator) ALT when the amount of stored electricity (accumulated energy) decreases.

  The electronic control unit ECU outputs a target value (drive signal) Fbt for driving the electric motor MTR to the drive means DRV. In addition, electric power for driving the MTR is supplied to the DRV via the ECU. Specifically, the ECU is provided with a connector CNB, and the serial communication bus SCB and the vehicle body power line PBD are connected to the driving means DRV via the CNB. Then, a target value (target pressing force) Fbt is calculated by target calculation means TRG programmed in the electronic control unit ECU, and Fbt is transmitted to the DRV through the SCB. Further, electric power (current) from the vehicle body power supply BBD is supplied to the drive means DRV through the vehicle body power line PBD via the ECU.

[Target calculation means TRG]
Target calculation means TRG (control algorithm) for calculating the target value (target pressing force) Fbt of the braking means BRK is programmed in the electronic control unit ECU.

  The target calculation means TRG is a control algorithm and includes an instruction pressing force calculation block FBS, an anti-skid control block ABS, a traction control block TCS, a vehicle stabilization control block ESC, and a target pressing force calculation block FBT. .

  In the command pressure calculation block FBS, the command pressure Fbs of each wheel WHL is calculated based on the braking operation amount Bpa and the command pressure calculation characteristic (calculation map) CHfb set in advance. Fbs is a target value of a pressing force that is a force with which the friction member (brake pad) MSB presses the rotating member (brake disc) KTB in the electric braking means BRK.

  In the anti-skid control block ABS, a target pressing force Fabs for executing a known anti-skid control is calculated based on an acquisition result (wheel speed) of a wheel speed acquisition means (not shown). The That is, the anti-skid control target pressing force Fabs is a target value of the pressing force for preventing wheel lock.

  In the traction control block TCS, a target pressing force Ftcs for executing known traction control (Traction Control) is calculated based on an acquisition result (wheel speed) of a wheel speed acquisition means (not shown). That is, the traction control target pressing force Ftcs is a target value of the pressing force for suppressing wheel spin (overspeed).

  In the vehicle stabilization control block ESC, based on the acquisition result (yaw rate) of the vehicle behavior acquisition means (for example, yaw rate sensor, not shown), a target push for executing the well-known vehicle stabilization control (Vehicle Stability Control) is performed. The pressure Fesc is calculated. That is, the vehicle stabilization control target pressing force Fesc is a target value of the pressing force for suppressing excessive vehicle understeer and / or oversteer.

  In the target pressing force calculation block FBT, the final target pressing force Fbs, the anti-skid control target pressing force Fabs, the traction control target pressing force Ftcs, and the vehicle stabilization control target pressing force Fesc are used. The pressure Fbt is calculated. Specifically, one of Fabs, Ftcs, and Fesc is selected, Fbs is corrected by the selected one, and Fbt is calculated. The selection order of Fabs, Ftcs, and Fesc is determined based on the running state of the vehicle and the state of the wheels. Note that Ftsc is not calculated when the corresponding wheel is not a drive wheel (when not connected to the drive train).

  The target pressing force (signal) Fbt calculated by the target calculating means TRG is applied to the braking means BRK (specifically, driving) fixed to the wheel via the ECU side connector CNB and the signal line (serial communication bus) SCB. Circuit DRV).

[Brake means BRK]
The braking means (brake actuator) BRK includes a brake caliper (floating caliper) CPR, a pressing member (brake piston) PSN, an electric motor (brush motor or brushless motor) MTR, a position detection means MKA, a reduction gear GSK, and a shaft member. The SFT includes a screw member NJB, a pressing force acquisition unit FBA, and a driving unit (MTR driving circuit) DRV.

  The brake caliper CPR is a floating caliper and is configured to sandwich a rotating member (brake disk) KTB via two friction members (brake pads) MSB. Within the caliper CPR, the pressing member PSN is slid and moved forward or backward toward the rotating member KTB. In the caliper CPR, the keyway KYM is formed so as to extend in the direction of the rotation axis (shaft axis Jsf) of the shaft member SFT.

  The pressing member (brake piston) PSN presses the friction member MSB against the rotating member KTB to generate a frictional force. The key member KYA is fixed to the pressing member PSN. When the key member KYA is fitted into the key groove KYM, the pressing member PSN is restricted from rotating around the shaft axis, but linear movement in the direction of the shaft axis (longitudinal direction of the key groove KYM) is allowed. Is done.

  The electric motor MTR generates power for pressing the friction member MSB against the rotating member KTB. That is, the electric motor MTR drives the pressing member PSN. Specifically, the output of the electric motor MTR (rotational power around the motor shaft Jmt) is transmitted to the shaft member SFT via the reduction gear GSK, and the rotational power of the SFT (torque around the shaft axis Jsf) It is converted into linear power (thrust in the direction of the pressing shaft Jps) by the conversion member (for example, screw member) NJB and transmitted to the pressing member PSN. Then, the pressing member (brake piston) PSN is advanced or retracted toward the rotating member (brake disc) KTB. By the movement of the PSN, the force (pressing force) Fba that the friction member (brake pad) MSB presses the rotating member KTB is adjusted. Since the rotating member KTB is fixed to the wheel WHL, a frictional force is generated between the friction member MSB and the rotating member KTB, and the braking force is adjusted to the wheel WHL, for example, the traveling vehicle is decelerated. As the electric motor MTR, a motor with a brush or a brushless motor is employed.

  In the rotation direction of the electric motor MTR, the forward rotation direction corresponds to the direction in which the friction member MSB approaches the rotation member KTB (the direction in which the pressing force increases and the braking torque increases), and the reverse rotation direction corresponds to the friction member MSB. Corresponds to the direction away from the rotating member KTB (the direction in which the pressing force decreases and the braking torque decreases). The output of the electric motor MTR is determined based on the target energization amount Imt calculated by the target calculation means TRG. Specifically, when the sign of the target energization amount Imt is a positive sign (Imt> 0), the electric motor MTR is driven in the forward rotation direction, and the sign of Imt is a negative sign (Imt <0). The electric motor MTR is driven in the reverse direction. Further, the rotational power of the electric motor MTR is determined based on the magnitude (absolute value) of the target energization amount Imt. That is, the larger the absolute value of the target energization amount Imt, the larger the output torque of the electric motor MTR, and the smaller the absolute value of the target energization amount Imt, the smaller the output torque.

  The position acquisition means (for example, rotation angle sensor) MKA acquires (detects) the position (for example, rotation angle) Mka of the rotor (rotor) of the electric motor MTR. The position acquisition means MKA is disposed inside the electric motor MTR and coaxially with the rotor and the commutator (that is, coaxial with the MTR and provided on the motor shaft Jmt).

  The reduction gear GSK reduces the rotational speed of the power of the electric motor MTR and outputs it to the shaft member SFT. That is, the rotational output (torque) of the MTR is increased according to the reduction ratio of the reduction gear GSK, and the rotational force (torque) of the shaft member SFT is obtained. For example, the GSK is composed of a small diameter gear SKH and a large diameter gear DKH. As GSK, instead of the gear transmission mechanism, a winding transmission mechanism such as a belt or a chain, or a friction transmission mechanism may be employed.

  The shaft member SFT is a rotating shaft member and transmits the rotational power transmitted from the reduction gear GSK to the screw member NJB. The end of the shaft member SFT is processed into a spherical shape and functions as a universal joint. This universal joint compensates for the influence of the swing (swinging motion) of the pressing member PSN that occurs when the friction member MSB slides.

  The screw member NJB is a power conversion member that converts the rotational power of the shaft member SFT into linear power. That is, the screw member NJB is a rotation / linear motion conversion mechanism. The screw member NJB includes a nut member NUT and a bolt member BLT. The screw member NJB has reversibility (has reverse efficiency) and can transmit power in both directions. That is, when the braking torque is increased (when the pressing force Fba is increased), power is transmitted from the shaft member SFT to the pressing member PSN through the screw member NJB. Conversely, when the braking torque is reduced (when the pressing force Fba is reduced), power is transmitted from the pressing member PSN to the shaft member SFT via the screw member NJB (reverse efficiency is less than “0”). large).

  The screw member NJB is configured by a sliding screw (such as a trapezoidal screw) that transmits power by “sliding”. In this case, the nut member NUT is provided with a female screw (inner screw) MNJ. The bolt member BLT is provided with a male screw (outer screw) ONJ and is screwed to the MNJ of the NUT. The rotational power (torque) transmitted from the shaft member SFT is transmitted as linear power (thrust) of the pressing member PSN via the screw member NJB (ONJ and MNJ).

  Further, instead of the above-described sliding screw, a rolling screw (such as a ball screw) in which power is transmitted by “rolling” may be employed for the screw member NJB. In this case, a ball groove is provided in the nut member and the bolt member. Power is transmitted through a ball (steel ball) fitted in the ball groove. In place of the screw member NJB, a conversion mechanism such as a ball ramp member, a rotary wedge member, a rack and pinion member, or the like may be employed as a power conversion member for converting a rotational motion into a linear motion.

  The pressing force acquisition means FBA acquires (detects) the reaction force (reaction) of the force (pressing force) Fba that the pressing member PSN presses the friction member MSB. A strain generating body is formed in the FBA, and the strain is detected by a strain detection element, and Fba is acquired. For example, as a strain detection element, a device using a change in electrical resistance (strain gauge), a device using ultrasonic waves, or the like can be used. The FBA is provided between the shaft member SFT and the caliper CPR, and is fixed to the caliper CRP. The detected pressing force Fba is input to the driving means DRV.

  The driving means DRV is fixed in the caliper CPR, and drives and controls the electric motor MTR based on the target pressing force Fbt. The DRV is composed of a control means CTL, a wheel power supply BWH, a bridge circuit HBR, and the like. Details of DRV will be described later.

[Connectors CNB, CNC, and wiring SCB, PBD]
A connector CNC is provided on the surface of the caliper CPR. From here, the drive power of the electric motor MTR and the drive signal (target pressing force Fbt) of the MTR are taken into the drive means DRV. The target signal Fbt is supplied to the BRK side connector (wheel side connector) CNC by the signal line SCB and the electric power by the vehicle body power line PBD, respectively.

  Similar to the drive means DRV, the connector CNB is provided in the electronic control unit ECU. The signal line SCB and the power line PBD are connected to the ECU via the ECU side connector (vehicle body side connector) CNB. That is, the electronic control unit ECU (vehicle body BDY is connected to the vehicle body BDY) via wiring (signal line SCB and power line PBD) relayed by the ECU side connector (vehicle body side connector) CNB and the BRK side connector (wheel side connector) CNC. Arrangement) and the drive circuit DRV (arranged on the wheel WHL) are connected. In other words, the signal line SCB transmits the target pressing force Fbt from the ECU to the DRV via the connectors CNB and CNC. Further, the power line PBD supplies power for driving the electric motor MTR from the ECU to the DRV through the connectors CNB and CNC at normal times. As the PBD, a twisted pair cable formed by twisting two electric wires may be employed.

<Driving means DRV>
Next, details of the driving means (driving circuit) DRV will be described with reference to FIG. Based on the target pressing force Fbt, the driving unit DRV controls the energization state of the electric motor MTR and adjusts the output of the MTR (that is, the braking torque generated by the braking unit BRK). FIG. 3 shows an example of drive means DRV in the case where a motor with a brush (also simply referred to as a brush motor) is employed as the electric motor MTR. The driving means DRV includes a wheel power source BWH, a control means CTL, a bridge circuit HBR formed by a plurality of switching elements (power transistors) S1 to S4, a noise reduction circuit NIZ, an energization amount acquisition means IMA, and a connector CNC. The

  As the electric motor MTR, a motor with a brush (also simply referred to as a brush motor) is employed. A motor with a brush is also called a commutator motor. In the electric motor, a current flowing through an armature (electromagnet by winding) is rotated by a mechanical commutator (commutator) CMT and a brush BLC. It is switched according to the phase. That is, the commutator CMT and the brush BLC constitute a mechanical rotation switch, and the current to the winding circuit is alternately inverted. In a motor with a brush, the stator (stator) side is constituted by a permanent magnet, and the rotor (rotor) side is constituted by a winding circuit (electromagnet). The brush BLC is in contact with the commutator CMT so that electric power is supplied to the winding circuit (rotor). The brush BLC is pressed against the commutator CMT by a spring (elastic body), and a current is commutated by rotating the CMT.

[Wheel power supply BWH]
The driving means DRV is provided with a wheel power source (second power source) BWH. That is, the wheel power source BWH is a power source provided on the wheel side (inside the braking means BRK) separately from the vehicle body power source (first power source) BBD. The wheel power supply BWH is connected to the bridge circuit HBR (that is, the electric motor MTR) by the wheel power line PWH. Since BWH and HBR are adjacent to each other, a bus bar (Bus Bar, a metal bar that functions as a conductor) is adopted as the wheel power line PWH. For this reason, the voltage drop by wiring resistance is slight, and the electric motor MTR can be driven efficiently. Further, since the bus bar does not require an insulating coating, the heat dissipation is high and it is possible to easily cope with a large current.

  The wheel power supply BWH assists the power supply to the DRV when there is a possibility that the power supply state from the vehicle body power supply BBD to the driving means DRV is insufficient (Imt ≧ imx). Since the BWH is an auxiliary power source, an energy capacity (storage capacity) smaller than that of the BBD is adopted. There are two types of power supply patterns to the electric motor MTR when the BBD is normal: a power supply pattern based on the BBD alone and a power supply pattern based on the BBD and BWH. That is, the MTR is not driven by being fed only from the BWH (there is no BWH single feeding pattern). The BWH is charged by the BBD (or the alternator ALT of the vehicle) at the time of non-braking request. The non-braking request time is a case where no braking torque is applied to the wheel, for example, when the braking operation member BP is not operated by the driver (that is, when Bpa = 0).

  As the wheel power supply BWH, an electric double layer capacitor (also referred to as an ultra capacitor or a super capacitor) may be employed. In an electric double-layer capacitor (EDLC), when an electric potential is applied to a system in which charged particles move relatively freely, the charged particles are generated according to the electric field. As a result of the movement, a pair of positive and negative charged particles forming a pair at the interface is used. An electric double layer capacitor is suitable for BWH because its internal resistance is small and charging and discharging are performed rapidly.

[Control means CTL]
The control means CTL controls the actual energization amount (finally the magnitude and direction of the current) to the electric motor MTR based on the target pressing force (target value) Fbt. Part of the control means CTL is a control algorithm, which is programmed into a CPU (Central Processing Unit) in the DRV. The CTL includes an instruction energization amount calculation block IST, a pressing force feedback control block IFT, an energization amount adjustment calculation block IMT, a pulse width modulation block PWM, a switching control block SWT, and power management means DGK.

  The command energization amount calculation block IST calculates the command energization amount Ist based on the target pressing force Fbt (transmitted from TRG) and preset command energization amount calculation characteristics (calculation maps) CHs1 and CHs2. Ist is a target value of the energization amount to the electric motor MTR for the electric braking means BRK to achieve the target pressing force Fbt. The calculation map of Ist is composed of two characteristics CHs1 and CHs2 in consideration of the hysteresis of the electric braking means BRK. The characteristic CHs1 corresponds to the case where the pressing force is increased, and the characteristic CHs2 corresponds to the case where the pressing force is decreased. 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 substantially proportional to the current, the current target value of the electric motor MTR 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.

  The pressing force feedback control block IFT calculates the pressing force feedback energization amount Ift based on the target pressing force (target value) Fbt and the actual pressing force (actual value) Fba. The command energization amount Ist is calculated as a value corresponding to the target pressing force Fbt, but an error (steady error) occurs between the target pressing force Fbt and the actual pressing force Fba due to the efficiency variation of the electric braking means BRK. There is. The pressing force feedback energization amount Ift is calculated based on a deviation (pressing force deviation) ΔFb between the target pressing force Fbt and the actual pressing force Fba and a preset calculation characteristic (calculation map) CHp, and the above error is calculated. Decided to decrease. The actual pressing force Fba is acquired (detected) by a pressing force acquisition unit FBA described later.

  The inertia compensation energization amount calculation block IKT, based on the target pressing force Fbt, “a force transmission mechanism that moves in relation to the generation of the braking torque from the electric motor MTR to the friction member MSB” (braking means BRK. In particular, the electric motor. The inertia compensation energization amount (target value) Ikt for compensating for the influence of inertia (inertia) of MTR) is calculated. Here, the inertia is an inertia moment in a rotational motion or an inertia mass in a linear motion. Specifically, the inertia compensation energization amount Ikt is determined when the electric motor is stopped or is moving at a low speed, when the movement (rotational movement) is accelerated, and when the electric motor is moved (rotational movement). It is calculated when the vehicle decelerates suddenly and stops. With Ikt, when MTR is accelerated, the responsiveness of the generation of the pressing force is improved, and when MTR is decelerated, the overshoot of the pressing force is suppressed, and the convergence can be improved.

  In the inertia compensation energization amount calculation block IKT, the inertia compensation energization amount Ikt is calculated based on the second-order differential value of the target pressing force Fbt. Fbt is proportional to the rotation angle Mka of the MTR, and the torque for starting the MTR is proportional to the second-order differential value of Mka. In addition, Ikt can be calculated based on the amount of time variation of Fbt and a preset calculation map. Ikt is calculated so as to increase the energization amount when the MTR is accelerated and decrease the energization amount when the MTR is decelerated.

  The energization amount adjustment calculation block IMT calculates a target energization amount Imt that is a final target value for the electric motor MTR. In the IMT, the command energization amount Ist is adjusted by the pressing force feedback energization amount Ift and the inertia compensation energization amount Ikt, and the target energization amount Imt is calculated. Specifically, when the MTR is accelerated, the feedback energization amount Ift and the inertia compensation energization amount Ikt are added to the command energization amount Ist, and this is calculated as the final target energization amount Imt (Imt = Ist + Ift + Ikt). On the other hand, when the MTR is decelerated, the feedback energization amount Ift is added to the command energization amount Ist, the inertia compensation energization amount Ikt is subtracted, and the final target energization amount Imt is calculated (Imt = Ist + Ift). -Ikt). Then, based on the sign (value sign) of the target energization amount Imt, the rotation direction of the electric motor MTR (forward rotation direction in which the pressing force increases or reverse rotation direction in which the pressing force decreases) is determined, and the target energization amount Imt. The output (rotational power) of the electric motor MTR is controlled based on the size of the motor.

  The pulse width modulation block PWM calculates an instruction value (target value) for performing pulse width modulation (PWM) based on the target energization amount Imt (normally). Specifically, the pulse width modulation block PWM determines the pulse width duty ratio Dut (ON / OFF time ratio) based on the target energization amount Imt and a preset characteristic (computation map). . In addition, the PWM determines the rotation direction of the MTR based on the sign of Imt (positive sign or negative sign). For example, the rotation direction of the electric motor MTR is 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 (power supply voltage) and the duty ratio Dut, the rotation direction of the MTR and the energization amount to the MTR (that is, the output of the MTR) are determined in PWM.

  In the pulse width modulation block PWM, so-called current feedback control can be executed. In this case, a detection value (actual current supply amount to the electric motor MTR, for example, an actual current value) Ima of the current supply amount acquisition unit IMA is input to the PWM. Then, the duty ratio Dut is corrected (finely adjusted) based on the deviation ΔIm between the target energization amount Imt and the actual energization amount Ima. With this current feedback control, highly accurate motor control can be achieved.

  The switching control block SWT outputs a drive signal to the switching elements (S1 to S4) constituting the bridge circuit HBR based on the duty ratio (target value) Dut. This drive signal indicates whether each switching element is energized or not energized. Specifically, when the electric motor MTR is driven in the forward rotation direction based on the duty ratio Dut, S1 and S4 are energized (ON state), and S2 and S3 are de-energized (OFF state) ) And the energization / non-energization states of S1 and S4 are switched in the energization time (energization cycle) corresponding to Dut. Similarly, when the MTR is driven 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), and the energized state of S2 and S3 ( ON / OFF switching cycle) is adjusted based on the duty ratio Dut. As the Dut increases, the energization time per unit time is lengthened, and a larger current flows through the MTR. For example, when Dut = 100% is instructed, the corresponding switching element is always energized, and when Dut = 0% is instructed, it is in a non-energized state.

  The power management means DGK manages the power supply state to the electric motor MTR, monitors the state of the wheel power source BWH, and properly maintains the state of charge. The power management means DGK includes switching means (switch group) SWX, charge state quantity acquisition means JDA, and determination calculation block HNT. The switching means SWX (a part of the electric circuit) includes a plurality of switches (such as SWc) for switching the connection state in the electric circuit. The charge state amount acquisition unit JDA acquires (detects) an actual value Jda (for example, an actual voltage value) of the charge state of the BWH. The determination operation block HNT (control algorithm) controls the power supply state to the bridge circuit HBR and manages the charging state of the BWH by adjusting the connection state of the SWX based on various state quantities (Imt, Jda, etc.). .

  Based on the target energization amount Imt, the determination calculation block HNT switches the switching unit SWX to adjust the power supply source (that is, the MTR power supply source) to the bridge circuit HBR. Specifically, when the target energization amount Imt is less than the first threshold value (predetermined value) imx (Imt <imx) by HNT, “HBR is connected to BBD, When the electric circuit connection is configured such that “not connected to BWH” and Imt is equal to or greater than imx (Imt ≧ imx), SWX is switched so that “HBR is connected to both BBD and BWH”. That is, in the normal braking state (when Imt <imx), the electric motor MTR is supplied with power only by the vehicle body power supply BBD (single power supply by BBD), but when power supply to the MTR is predicted to be insufficient due to sudden braking (Imt When ≧ imx), power supply (combined power supply using BBD and BWH) is performed by the vehicle body power supply BBD and the wheel power supply BWH.

  The target energization amount Imt instructs forward / reverse rotation of the electric motor MTR by its sign, but the magnitude relationship becomes complicated when the sign of Imt is considered. For this reason, in the description, the magnitude relationship is expressed by its absolute value (value magnitude). Therefore, the determination condition of “Imt <imx (imy)” is equal to “Imt is within ± imx (imy)”. Similarly, the determination condition of “Imt ≧ imx (imy)” is “Imt is ±±. It is equivalent to “out of imx (imy)”.

  The power management means DGK monitors the power storage state of the wheel power supply BWH by the charge state amount acquisition means JDA, and charges the wheel power supply BWH when the power storage state decreases. For example, the charging state quantity acquisition unit JDA detects the voltage Jda of the wheel power supply BWH, and when the Jda falls below a voltage threshold value (a predetermined value set in advance), charging to the BWH is started. . As a condition for starting charging, “the braking operation member BP is not operated (the non-braking state is affirmed)” is added as a condition. This condition is determined based on “the braking operation amount Bpa is less than the predetermined value bpx”. Alternatively, a stop switch STP (ON / OFF switch) is provided in the braking operation member BP, and determination can be made based on the signal Stp (by indicating that the Stp is in the ON state). The wheel power supply BWH is charged by power supply from the BBD (or the alternator ALT of the vehicle) when the driver is not performing a braking operation (when non-braking is requested).

[Bridge circuit HBR and noise reduction circuit NIZ]
The switching elements S1 to S4 are elements that can turn on (energize) / off (non-energize) a part of the electric circuit. For example, a MOS-FET or IGBT is used as the switching element. A switching circuit S1 to S4 constitutes a bridge circuit HBR. Here, the bridge circuit does not require a bi-directional power supply, the energization direction to the electric motor is changed with a single power supply, and the rotation direction (forward rotation direction or reverse rotation direction) of the electric motor is controlled. A circuit that can be made. This bridge circuit is also referred to as an H bridge circuit or a full bridge circuit. The switching elements S1 to S4 are driven by the control means CTL (signal from the switching control block SWT). By switching the energization / non-energization state of each switching element, the rotation direction (forward rotation direction, reverse rotation direction) and output torque (magnification amount) of the electric motor MTR are adjusted. Here, the forward rotation direction of the MTR is a rotation direction in which the friction member MSB is brought closer to the rotation member KTB, the braking torque is increased, and the deceleration of the running vehicle is increased. The reverse rotation direction of the MTR is MSB In the rotational direction in which the braking torque is reduced and the deceleration of the running vehicle is reduced.

  When a large output is required for the electric motor MTR, a large current is passed through the switching elements S1 to S4. At this time, since heat is generated in the switching elements S1 to S4, a heat radiating plate (heat sink) can be provided in S1 to S4. Specifically, a metal plate (for example, an aluminum plate) with good thermal conductivity can be fixed to S1 to S4.

  The drive circuit DRV is provided with a noise reduction circuit (stabilization circuit) NIZ for stabilizing supply power (that is, reducing voltage fluctuation). The noise reduction circuit NIZ is a so-called LC circuit (also referred to as an LC filter), and includes a combination of at least one inductor (coil) IND and at least one capacitor (capacitor) CND. For example, as the NIZ, the first and second capacitors CND1, CND2 and the inductor IND are combined to form a low-pass filter (π-type filter). Specifically, the π-type low-pass filter is a so-called Chebyshev low-pass LC filter, which is a filter including two capacitors CND1 and CND2 parallel to the line and one series inductor. In general, an inductor is more expensive than a capacitor (capacitor). Therefore, by adopting a π-type filter, component costs are suppressed, and good performance can be obtained. Further, as the noise reduction filter NIZ, a T-type low-pass filter (configured by two series inductors and one parallel capacitor) may be employed instead of the π-type low-pass filter.

  The drive circuit DRV is provided with energization amount acquisition means (for example, a current sensor) IMA. The energization amount acquisition means IMA acquires (detects) an actual energization amount (for example, current that actually flows through the electric motor MTR) Ima to the electric motor MTR.

[Electric motor MTR]
As the electric motor MTR, a brushless motor may be employed instead of the brush motor. The brushless motor is also called a brushless direct current motor (Brushless Direct Current Motor). In the electric motor, current is commutated by an electronic circuit instead of the mechanical commutator CMT of the brushed motor. . In the brushless motor, the rotor (rotor) is a permanent magnet, and the stator (stator) is a winding circuit (electromagnet). The rotor rotation position Mka is detected, and the switching element is switched according to Mka. As a result, the supply current is commutated. The rotor position Mka is detected by position acquisition means MKA provided inside the electric motor MTR.

  When a brushless motor is employed, the bridge circuit HBR of the driving unit DRV is configured by six switching elements. As in the case of the motor with brush, the energization state / non-energization state of the switching elements constituting the bridge circuit HBR is controlled based on the duty ratio Dut determined by the pulse width modulation block PWM.

  In the brushless motor, the position acquisition means MKA acquires the rotor position (rotation angle) Mka of the electric motor MTR. In the switching control block SWT, the six switching elements constituting the three-phase bridge circuit are controlled based on the actual position Mka. The switching elements sequentially switch the direction of the energization amount of the U-phase, V-phase, and W-phase coils of the bridge circuit (that is, the excitation direction) to drive the MTR. The rotation direction (forward rotation or reverse rotation) of the brushless motor is determined by the relationship between the rotor and the excitation position.

<Body power supply BBD, wheel power supply BWH, and power management means DGK>
Next, the electrical connection between the vehicle power supply BBD and the wheel power supply BWH, and the power management means DGK (a part of the control means CTL) for managing the power supplies BBD and BWH will be described with reference to FIG.

  A vehicle body power supply (first power supply) BBD is provided in the vehicle body BDY. Further, the BDY is provided with an alternator ALT that generates electric power and charges the BBD. The alternator ALT is a generator and is driven by a power source such as an engine. When the power storage amount (charge amount) of the vehicle body power supply BBD decreases, the power generated by ALT is supplied to the BBD via the diode Da, and the BBD is charged. Further, power (current) from ALT and BBD is constantly supplied to the drive circuit DRV via the diode Db. Therefore, the alternator ALT is a part of the vehicle body power supply. When the alternator ALT is generating electric power, this electric power is also supplied to the DRV. Therefore, the BBD and the ALT serve as a supply source (vehicle power source) of electric power (current) to the DRV.

  Power supply from the vehicle body power supply BBD or the like to the drive means DRV is performed by a vehicle body power line (power line) PBD. Here, as the power line PBD, a twisted pair cable (a twisted pair cable, an electric wire twisted in two pairs) may be employed. The PBD is connected to the drive means DRV via a connector (vehicle body side connector) CNB provided in the ECU.

  Driving means (driving circuit) DRV is provided in a caliper CPR fixed to the wheel WHL. The drive means DRV is provided with a connector (wheel side connector) CNC, and electric power (current) is introduced into the DRV via the CNC. The drive means DRV is programmed with a control means CTL, a noise reduction circuit NIZ, a bridge circuit HBR (S1 to S4), a wheel power supply BWH, a DC-DC converter (also simply referred to as a converter) DCC, and Power management means DGK (a part of CTL) for management is provided. All of these are provided in the CPR (fixed on the wheel side).

  The wheel power source BWH supplies power to the MTR via a wheel power line (power line) PWH. For example, an electric double layer capacitor (also simply referred to as a capacitor) is employed as the BWH. Since the capacitor has a lower internal resistance than a secondary battery (storage battery), it can be charged and discharged in a short time. A bus bar can be adopted as the wheel power line PWH, which is a power supply path from the BWH to the MTR. The use of a bus bar eliminates the need for complicated terminal processing, facilitates assembly, and is suitable for supplying a large current.

  The DC-DC converter DCC controls a direct current voltage, and converts a direct current of a certain voltage into a direct current of a different voltage (steps up or down). That is, the output voltage of the wheel power supply BWH is changed to a voltage suitable for driving the electric motor MTR by the converter (voltage conversion means) DCC. As the DC-DC converter DCC, any one of a chopper control type, a switching control type, and a series regulator type may be employed.

  The power management means DGK controls the connection state between each power supply (BBD, ALT, and BWH) and the bridge circuit HBR. The power management means DGK is composed of switching means SWX (a general term for switches SWc and SWe), a determination calculation block HNT, and a charge state amount acquisition means JDA. The switching means SWX (SWe, SWc) are ON / OFF switches. The switching means (switch) SWe is for power assistance to the bridge circuit HBR, and the switching means SWc is for charging the wheel power source BWH. Each is used. The switching means SWX switches between a closed state (energized state) and an open state (non-energized state) based on the calculation result (signals Csc, Cse) in the determination calculation block HNT. Note that the switch SWc is in a closed state (connected state) when the wheel power supply BWH is charged, but is in an open state (unconnected state) in other cases.

  At the time of normal braking request (when sudden braking described later is not required), the bridge circuit HBR (electric motor MTR) is supplied only from the power supply source (at least one of the vehicle power supply BBD and the alternator ALT) on the vehicle body side. Power is supplied to a circuit that supplies power to the circuit. In the determination calculation block HNT, based on the target energization amount Imt transmitted from the target energization amount calculation block IMT, the drive signal Cse of the switch SWe and the drive signal Csc of the switch SWc are output, and the connection of the switches SWe and SWc The state is controlled. Specifically, when the target energization amount Imt is less than the energization threshold imx, the switch SWe is in the open position (non-energized state), and the connection between the wheel power source BWH and the bridge circuit HBR is interrupted. In this case, power supply to the HBR is performed by a power supply (BBD, ALT) provided in the vehicle body via the vehicle body power line PBD. When normal braking is required as in the case of Imt <imx (for example, when the deceleration of the vehicle is less than 0.3 G), the power supply amount to the MTR is not so large. Is not used, and power is supplied only by the power sources BBD and ALT on the vehicle body side.

  On the other hand, when sudden braking is required, the power source on the wheel side is used in addition to the power supply source on the vehicle body side to supply power to the bridge circuit HBR. Specifically, when the target energization amount Imt is equal to or greater than the energization threshold value (predetermined value) imx, the switch SWe is in the closed position (energization state), and the wheel power supply BWH and the bridge circuit HBR are connected. That is, by adjusting the voltage by the converter DCC, power is supplied from the BWH to the HBR via the diode Dc and the switch SWe. At this time, the switch SWc is opened (non-energized state), and current from the BBD or the like is prevented from flowing into the wheel power source BWH. When it is assumed that the power supply to the bridge circuit HBR is limited to the vehicle body power line PBD, when sudden braking is requested (for example, when the deceleration of the vehicle is 0.3 G or more, or when the amount of time change in deceleration is large) Requires a large current to flow through the vehicle body power line PBD. Since the PBD has a slight resistance, when a large current is passed, an influence of a voltage drop appears and a resistance increase due to heat generation may occur. For this reason, at the time of a sudden braking request, the power supply from the vehicle power source BBD through the vehicle power line PBD is supplemented (supplemented) by the power supply from the wheel power supply BWH through the wheel power line PWH. As a result, it is not necessary to increase the cross-sectional area of the vehicle body power line PBD, and the flexibility of the PBD can be ensured.

  The state-of-charge obtaining unit JDA obtains (detects) a state amount (charge state amount) Jda representing the state of charge (power storage state) of the wheel power source BWH. For example, the state of charge acquisition means JDA acquires the voltage of the wheel power source BWH as the state of charge Jda. Furthermore, JDA acquires the temperature of BWH as Jda. Further, the elapsed time from the time when charging is started can be acquired as Jda.

  The power management means DGK charges the wheel power source BWH based on the charge state amount Jda. The amount of electricity stored in the BWH is lost over time due to self-discharge. Therefore, the determination calculation block HNT (part of DGK) is BBD (or ALT) when the driver is not operating the braking operation member BP (for example, determination is made based on the condition of Bpa <bpx (predetermined value)). Current is supplied from B to BWH, and electric charge is accumulated (charged) in BWH. Specifically, the switches SWe and SWc are closed (connected state) by the drive signals Cse and Csc from the HNT, and the wheel power source BWH, the vehicle body power source BBD, and the alternator ALT are connected. And HNT complete | finishes charge, when it will be in the state (full charge) in which the electric charge was fully stored in BWH. That is, the connection between BWH and BBD and ALT is cut off by switching SWc from the closed position (connected state) to the open position (cut off state) by HNT.

  The timing of the end of charging (full charge) is determined based on the state of charge Jda of the wheel power source BWH. For example, as the state of charge Jda, the voltage of BWH is detected, and the fully charged state can be detected based on the change in the voltage of BWH. Further, based on the capacity of BWH and the charge / discharge time, full charge can be determined by calculation processing programmed in the determination calculation block HNT. Furthermore, in the power supply management means DGK, as the charging method, at least one of -ΔV method charging, temperature control method charging, dT / dt control method, pulse charging, and trickle charging can be adopted. In the −ΔV system charging, a phenomenon in which the voltage of the battery slightly decreases when the battery is charged exceeding the fully charged state is charged based on this voltage change. In the temperature control method, the temperature of the wheel battery BWH is detected as the charge state quantity Jda, and charging is performed based on the temperature rise of the battery. In dT / dt control type charging, a differential value (time variation dJda of Jda) of the temperature (increase) of the battery BWH is detected, and charging is performed based on dJda. In the pulse charging method, after reaching a predetermined voltage by constant current charging, charging is continued by a pulse current. In the pulse charging, the cell voltage is allowed to exceed a predetermined voltage for a very short time, and the cell voltage is closely monitored, so that overcharging can be suppressed and rapid charging can be performed. In the trickle charging method, a fully charged state is maintained by constantly supplying a weak current that does not affect or affect the battery characteristics.

  The wheel power supply BWH supplies power to the electric motor MTR when the power supply state of the vehicle body power supply BBD becomes inappropriate. The power management means DGK monitors the supply voltage to the bridge circuit HBR, and determines the malfunctioning state of the vehicle body power supply BBD when the voltage falls below a predetermined voltage. The determination operation block HNT switches the switch SWe from the open state to the closed state, and starts supplying power from the wheel power source BWH to the bridge circuit HBR. The current from the wheel power supply BWH to the vehicle body power supply BBD is cut off by the diode Db. The wheel power supply BWH supplementarily supplies power in an emergency situation where the power supply capability of the vehicle body power supply BBD is reduced.

<Time-series operation of the present invention>
Next, with reference to FIG. 5, assuming the two situations (inertia compensation control and anti-skid control), the operation in the time series of the present invention and the effects thereof will be described.

  FIG. 5A is a time-series diagram in a case where sudden braking is performed by the driver. At time t0, the driver starts a braking operation, and the command energization amount Ist calculated based on the braking operation amount Bpa starts to increase. In response to Ist, the electric motor MTR is energized from the vehicle body power supply BBD. At this time, the switch SWe is in an open state (non-energized position), and the wheel power source BWH is not connected to the bridge circuit HBR. That is, the electric motor MTR is supplied with power only by the vehicle body power supply BBD.

  At time t1, it is determined that the inertia compensation control is necessary, and the target energization amount Imt is rapidly increased by adding the inertia compensation energization amount Ikt (represented by a hatched portion) to the command energization amount Ist. Here, the inertia compensation energization amount Ikt is a target value of the energization amount for compensating the inertia (moment of inertia) of the braking means BRK (particularly, MTR). At time t2, Imt satisfies a condition (imt is outside the range of ± imx) that is equal to or greater than the energization threshold value (first threshold value) imx, and the switch SWe changes from the open state (non-energized position) to the closed state (energized state). Position). Here, the first threshold value imx is a threshold value for switching the SWe from the open position to the closed position. By switching the SWe from the open position to the closed position, the bridge circuit HBR receives energy supply from two power sources (BBD and BWH). Since the power supply from the BBD is assisted by the power supply from the BWH, even if a thin wiring (high flexibility but limited power supply capacity) is adopted as the vehicle body power line (power line) PBD, the target power supply amount A sufficient energization amount can be ensured according to Imt. A bus bar may be employed as a power line (wheel power line) PWH from the wheel power supply BWH to the bridge circuit HBR. Since the bus bar has a small electric resistance, a larger amount of current can flow.

  At time t3, the target energization amount Imt satisfies the condition (Imt is within ± imy) less than the energization threshold (second threshold) imy, but SWe immediately changes from the closed position to the open position. Cannot be switched. Here, the second threshold value imy is a predetermined value that is smaller than the first threshold value imx, and is a threshold value for switching the closed state from the closed state to the open state. The switching of the SWe from the closed position to the open position is performed at time t5 when a predetermined time tx elapses from time t3 when the condition of Imt <imy is satisfied. At time t3, power supply assistance is not immediately terminated, but power supply assistance is terminated at time t5 when a predetermined time tx is continued from that time (t3). In sudden braking in which inertia compensation control is executed, after inertia compensation control is terminated, there is a high probability that Imt again exceeds imx. After SWe has been switched from the open position to the closed position, since a predetermined time tx has elapsed from the time Imt becomes smaller than imy, the power supply is returned from the closed position to the open position. Can be suppressed. Further, since the second threshold value imy is preset to a value smaller than the first threshold value imx, the determination hunting in the case where the target energization amount Imt slightly changes in the vicinity of the value imx. (Phenomenon in which ON / OFF is repeated) can be suppressed.

  FIG. 5B is a time series diagram when anti-skid control for suppressing wheel slip is executed. It can be assumed that anti-skid control is started when the electric motor MTR is rapidly accelerated by inertia compensation control due to sudden braking by the driver. In this case, in order to reduce the braking torque, it is required that the MTR accelerated in the forward rotation direction is rapidly decelerated and further driven in the reverse rotation direction.

  At time t0, the driver starts operating the braking operation member BP, and the target energization amount Imt is increased from zero (non-braking state). At time t1, inertia compensation control is started. Since the target energization amount Imt does not exceed the threshold value imx, the switch SWe is maintained in the open position (non-energized state). At time t6, anti-skid control is started, and Imt is increased in the minus direction to drive the electric motor MTR from the forward rotation direction to the reverse rotation direction. At this time, the condition that Imt is equal to or greater than imx (Imt is out of the range of ± imx considering the sign) is satisfied, and SWe is switched from the open position to the closed position. Since the power supply from the wheel power supply BWH is supplemented in addition to the power supply from the vehicle power supply BBD, an increase in wheel slip caused by the return delay of the electric motor MTR (braking torque overshoot) can be suppressed. Switching to the open position of SWe is performed after a predetermined time tx has elapsed from the point in time when Imt falls within the range of ± imy, as described above. In addition, for anti-skid control, SWe is maintained in the closed position, and can be switched to the open position after the control ends.

  When anti-skid control is performed using the electric motor MTR, it is necessary to once stop the MTR during normal rotation and drive in the reverse direction, so that a large current is required. Also in this case, when the switching unit SWe is switched from the open position to the closed position, power is supplied to the bridge circuit HBR from the two power sources of the vehicle body power supply BBD and the wheel power supply BWH. Furthermore, electric power can be supplied from the wheel power supply BWH to the bridge circuit HBR via the bus bar PWH having a small electric resistance value. For this reason, even when the thin vehicle body power line PBD is employed, a sufficient current can be supplied to the electric motor MTR.

  In the above embodiment, the switching of the switch SWe is executed based on the target energization amount Imt. However, since Imt is calculated based on the braking operation amount Bpa, another state amount is employed instead of Imt. obtain. That is, in the calculation process, switching of the switch SWe can be executed based on at least one state quantity among the state quantities (for example, Fbt, Imt) from the braking operation quantity Bpa to the target duty ratio Dut. .

  MSB ... friction member, KTB ... rotating member, MTR ... electric motor, BBD ... body power supply, BWH ... wheel power supply, CTL ... control means, Imt ... energization target value, Ikt ... inertia compensation energization amount

Claims (2)

A rotating member fixed to a vehicle wheel;
An electric motor provided on the wheel side of the vehicle;
A friction member that presses the rotating member using a driving torque of the electric motor to generate a braking torque on the wheel;
A vehicle body power source provided on the vehicle body side of the vehicle for supplying power to the electric motor;
A wheel power source provided on the wheel side of the vehicle for supplying power to the electric motor;
Control means for calculating an energization target value of the electric motor based on a braking operation by a driver of the vehicle, and controlling the electric motor based on the energization target value;
An electric braking device for a vehicle, comprising:
The control means includes
When the energization target value is less than the first threshold value, the electric motor is driven using only the vehicle body power supply,
An electric braking device for a vehicle configured to drive the electric motor using the vehicle body power source and the wheel power source when the energization target value is equal to or greater than the first threshold value. The electric braking device for a vehicle according to claim 1,
The control means includes
An inertia compensation energization amount that compensates for the influence of inertia of a force transmission mechanism that moves in relation to generation of braking torque from the electric motor to the friction member is calculated, and the energization target value is calculated based on the inertia compensation energization amount. Configured to operate,
The control means includes
It is predetermined from the time when the energization target value reaches the first threshold while increasing, and thereafter when the energization target value decreases and reaches the second threshold smaller than the first threshold. An electric braking device for a vehicle configured to drive the electric motor using the vehicle body power source and the wheel power source until a time has elapsed.

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