JP6183192B2 - Electric braking device for vehicle - Google Patents

Description

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

  In Patent Document 1, for the purpose of “providing a function as a parking brake without impairing the function as an electric brake”, a “pinch wheel” is provided on the peripheral surface of the rotor of the motor. The swinging arm is provided with an engaging pawl biased in one direction by a torsion spring, the swinging arm is constantly biased toward the handwheel by a tension spring, and in the braking direction of the rotor when the parking brake is operated. The braking force is generated by the rotation of the rotor, and then the return of the rotor is regulated by the engagement of the engagement pawl and the pawl wheel by interrupting the energization to the motor. " Further, “when the parking brake is operated, the projecting posture in which the engaging pawl abuts against the projection by the biasing force of the torsion spring is maintained. As a result, the engagement of the engaging pawl and the pawl wheel causes the counterclockwise rotation of the rotor. “Rotation in the direction is restricted and the parking brake is established” (see FIG. 3 of Patent Document 1).

  In the parking brake mechanism of Patent Document 1, the engagement between the ratchet wheel (ratchet gear) and the engagement pawl (claw member) is caused by the biasing force of the torsion spring (specifically, the contact portion between the ratchet gear and the pawl member). (A friction force generated by a friction coefficient and an urging force). On the other hand, it is desired that the meshing state between the ratchet gear and the pawl member be maintained more firmly.

  Further, in the parking brake mechanism of Patent Document 1, a swing arm (lever, Lever) is used to engage the pawl member with the ratchet gear. However, in order to reduce the size of the apparatus, a structure (direct drive structure) in which the pawl member is directly driven by a solenoid actuator (also simply referred to as a solenoid) is desired. In this direct drive structure, even when the energization to the solenoid is stopped, it is required that the engagement state between the ratchet gear and the pawl member is reliably maintained.

JP 2003-042199 A

  The present invention has been made to cope with the above-described problem, and an object of the present invention is an electric braking device for a vehicle including a parking brake mechanism, after energization to a solenoid included in the parking brake mechanism is stopped. Another object of the present invention is to provide a device that can reliably maintain the meshing state of the ratchet gear and the pawl member against disturbances and the like.

  An electric braking device for a vehicle according to the present invention drives a pressing member (PSN) that presses a friction member (MSB) against a rotating member (KTB) that rotates integrally with a vehicle wheel (WHL), and the pressing member (PSN). An electric motor (MTR) that generates power and a parking brake mechanism (LOK) are provided. The parking brake mechanism (LOK) includes a ratchet gear (RCH) fixed to a power transmission member (INP, SFT) that is rotationally driven by the electric motor (MTR) and drives the pressing member (PSN), and the ratchet gear. A claw member (TSU) which is arranged to be movable in a first linear direction with respect to (RCH) and can mesh with the ratchet gear (RCH), and the claw member (TSU) when energized, in the first linear direction. A solenoid (SOL) that pushes in a meshing direction (Dts) in which the pawl member (TSU) approaches the ratchet gear (RCH).

  The vehicle electric braking apparatus according to the present invention is characterized in that an engagement surface (Stm, plane) of the pawl member (TSU) with the ratchet gear (RCH) is the pressing member with respect to the first linear direction. When the pressing force of (PSN) decreases, the ratchet gear (RCH) is inclined in the direction of rotation (Rvs direction, clockwise in FIG. 5), and the pawl member (TSU) and the ratchet gear (RCH) Are engaged with each other (Stm, plane) with the claw member (TSU) in the ratchet gear (RCH), the pressing force of the pressing member (PSN) is in the first linear direction. This is because the ratchet gear (RCH) is inclined in the rotating direction (Rvs direction, clockwise direction in FIG. 5) when decreasing. It is preferable that the two inclination angles are set so that “surface contact” is obtained at the meshing portion (Stm) between the pawl member (TSU) and the ratchet gear (RCH). Hereinafter, an angle at which the meshing surface (Stm) of the pawl member (TSU) is inclined with respect to the first linear direction is referred to as a “rake angle”.

  In a state where the pawl member TSU and the ratchet gear RCH are engaged with each other, the pawl member TSU moves from the ratchet gear RCH to a tangential force (tangential force) along the outer periphery of the ratchet gear RCH due to the elasticity (rigidity) of the electric braking device. ) Here, since the claw member TSU has a rake angle α, the component force of the tangential force acts on the claw member TSU as a force in the biting direction Dts. As a result, after energization to the solenoid SOL is stopped, a force in the meshing direction Dts is always applied to the pawl member TSU from the ratchet gear RCH. Therefore, the meshing state between the ratchet gear RCH and the pawl member TSU can be reliably maintained.

  In the electric braking device according to the present invention, “a first plane (Ms1) including the rotation axis (Jrc) of the ratchet gear (RCH) and parallel to the first linear direction”, and “the pawl member (TSU ) And the ratchet gear (RCH) are engaged with each other, the tooth tip portion (Phs) of the ratchet gear (RCH) in the engagement portion (Stm) between the pawl member (TSU) and the ratchet gear (RCH) The offset distance (Los), which is a distance between the second plane (Ms2) including and parallel to the first linear direction, is set to the radius (Rrc) of the ratchet gear (RCH). ) In the range of 10 to 70% of the value (Rrc · sin α) multiplied by the sine (sin α) of the angle (α) inclined with respect to the first linear direction. It is preferable to be constant.

  The geometrical conditions for the pawl member TSU and the ratchet gear RCH to mesh with each other are the positional relationship between the rotation axis Jrc of the ratchet gear RCH and the pawl member TSU (that is, the offset distance Los), and the teeth of the ratchet gear RCH. Is determined on the basis of the inclination angle (bite angle) β. If the offset distance Los increases, the bite angle β can be set small and the tooth thickness Lrc can be set large. For this reason, when the biting portion Stm is in the vicinity of the first plane Ms1 (see the state [S1] in FIG. 9A), the tooth thickness Lrc becomes the value Lrc1, but the offset distance Los increases. Accordingly, the tooth thickness Lrc increases (see states [S2] and [S3] in FIG. 9A). On the other hand, when the tooth thickness Lrc is increased, the thickness Lts of the pawl member TSU becomes smaller (thin), and the strength of the pawl member TSU decreases.

  According to the above configuration, in the meshed state of the pawl member TSU and the ratchet gear RCH, the offset distance Los (the distance between the first plane Ms1 and the second plane Ms2) is “the radius Rrc of the ratchet gear RCH. It is set within a range of 10 to 70% of a value Rrc · sin α multiplied by a sine sin α of the rake angle α. By setting the position of the biting portion Stm within this range, the strength of the ratchet gear RCH and the strength of the pawl member TSU can be compatible.

  In the electric braking device according to the present invention, the width (Wts) of the pawl member (TSU) at the meshing portion (Stm) between the pawl member (TSU) and the ratchet gear (RCH) is the ratchet. It is preferable that it is larger than the width (Wrc) of the gear (RCH).

  The ratchet gear RCH has a plurality of teeth, while the pawl member TSU has a single biting portion. Therefore, in terms of fatigue strength, the ratchet gear RCH is more advantageous than the pawl member TSU. In this regard, according to the above configuration, the width Wts of the pawl member TSU is set to be larger than the width Wrc of the ratchet gear RCH, so that the strength of the pawl member TSU which is disadvantageous with respect to fatigue strength can be ensured.

  Further, in the electric braking device according to the present invention, the pawl member (so that the relative position of the pawl member (TSU) with respect to the ratchet gear (RCH) in the meshing direction (Dts) does not exceed a predetermined limit position). A stopper mechanism for restricting movement of the TSU in the biting direction (Dts) is provided, the relative position of the pawl member (TSU) is at the predetermined limit position, and the pawl member (TSU) and the In a state where the ratchet gear (RCH) is engaged, the tip portion (Pts) of the claw member (TSU) and the ratchet at the engagement portion (Stm) of the claw member (TSU) and the ratchet gear (RCH) A gap may be formed between the tooth bottom portion (Hbm) of the gear (RCH).

  Here, when the electric braking device according to the present invention includes a guide member (GID) that guides the movement of the pawl member (TSU) in the first linear direction, the stopper mechanism has a longitudinal direction. It is preferable that a step portion formed on a side surface of the pawl member (TSU) and a part of the guide member (GID) engaged with the step portion.

1 is an overall configuration diagram of an electric braking device for a vehicle according to an embodiment of the present invention. It is a fragmentary sectional view for demonstrating the parking brake mechanism (lock mechanism) LOK. It is a functional block diagram for demonstrating the drive circuit DRV etc. FIG. It is a figure for demonstrating the meshing state of the claw member TSU and the ratchet gearwheel RCH. It is a figure for demonstrating the name of each part of claw member TSU and ratchet gearwheel RCH. It is a figure for demonstrating the relative motion of the nail | claw member TSU and the ratchet gearwheel RCH in an engagement start operation | movement. It is a figure for demonstrating the relative motion of the nail | claw member TSU and the ratchet gearwheel RCH in an engagement release operation | movement. It is a time-series diagram for demonstrating 1st Embodiment about the meshing action | operation (start and cancellation | release) of the nail | claw member TSU and the ratchet gearwheel RCH. It is a figure for demonstrating the contact part Stm of the claw member TSU and the ratchet gearwheel RCH, and the appropriate area | region (space sandwiched by the surface Ms1 and the surface Ms2) of the contact part Stm. It is a figure for demonstrating in detail the meshing state of the nail | claw member TSU and the ratchet gearwheel RCH. It is a figure for demonstrating the experimental result about the acceleration which acts on a wheel. When the braking means BRK is provided on the front side of the wheel WHL (front arrangement), it is a diagram for explaining an appropriate arrangement of the central axes Jts (Jtsa, Jtsc) of the pawl member TSU. When the braking means BRK is provided on the rear side of the wheel WHL (rear arrangement), it is a diagram for explaining an appropriate arrangement of the central axes Jts (Jtsb, Jtsd) of the pawl member TSU. It is a figure for demonstrating the acceleration component Gts which acts on the moving direction of the claw member TSU when the center axis Jts of the claw member TSU is arranged in an appropriate range.

  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 is an overall configuration diagram of the electric braking device.

  A vehicle including this electric braking device includes a braking operation member BP, an operation amount acquisition unit BPA, an acceleration operation member AP, an acceleration operation amount acquisition unit APA, a parking brake switch MSW, a wheel speed acquisition unit VWA, a vehicle speed acquisition unit VXA, An electronic control unit ECU, power sources BAT, ALT, braking means (brake actuator) BRK, rotating member KTB, and friction member MSB are provided.

<< braking operation member BP, braking operation amount acquisition means BPA, and braking operation amount Bpa >>
The braking operation member (for example, brake pedal) BP is a member that the driver operates to decelerate the vehicle. The braking torque of the wheel WHL is adjusted by the braking means BRK in accordance with the operation of the braking operation member BP. As a result, braking force is generated on the wheels WHL, and the traveling 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 the brake operation amount acquisition means BPA, a sensor (pressure sensor) for detecting the pressure of the master cylinder, a sensor for detecting the operation force of the brake operation member BP (brake pedal depression force sensor), and a sensor for detecting the displacement amount of the BP ( At least one of the brake pedal stroke sensors) is employed. 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 detected braking operation amount Bpa is input to an electronic control unit ECU (specifically, a central processing unit CPU provided in the ECU).

<< Acceleration operation member AP, acceleration operation amount acquisition means APA, and acceleration operation amount Apa >>
The acceleration operation member (for example, accelerator pedal) AP is a member that the driver operates to accelerate the vehicle. The acceleration operation member AP is provided with acceleration operation amount acquisition means APA. The acceleration operation amount acquisition means APA acquires (detects) an operation amount (acceleration operation amount) Apa of the acceleration operation member AP by the driver. As acceleration operation amount acquisition means APA, a sensor for detecting the throttle opening of the engine (throttle opening sensor), an operation force of the acceleration operation member AP, and / or a sensor for detecting the displacement (accelerator pedal force sensor, accelerator pedal) Stroke sensor) is adopted. Therefore, the acceleration operation amount Apa is calculated based on at least one of the throttle opening, the accelerator pedal depression force, and the accelerator pedal stroke.

≪Parking brake switch MSW and instruction signal Msw≫
A parking brake switch (also simply referred to as a switch) MSW is a manual switch operated by a driver, and outputs a switch MSW ON / OFF signal Msw. The driver instructs the operation or release of the parking brake that maintains the vehicle stop state by operating the switch MSW. That is, the signal Msw is a parking brake instruction signal. For example, the operation of the parking brake is instructed when the instruction signal Msw is on (ON), and the release of the parking brake is instructed when the Msw is off (OFF).

<< Vehicle speed acquisition means VXA, vehicle speed Vxa, wheel speed acquisition means VWA, and wheel speed Vwa >>
The vehicle speed acquisition means VXA acquires (detects) the vehicle speed (vehicle speed) Vxa. The vehicle speed Vxa can be calculated based on the detection signal (wheel speed) Vwa of the wheel speed acquisition means VWA and a known method. For example, the fastest speed among the rotational speeds Vwa of the wheels can be calculated as the vehicle speed Vxa.

  The braking operation amount Bpa, the acceleration operation amount Apa, the vehicle speed Vxa, and the instruction signal Msw are input to the electronic control unit ECU. Note that Bpa, Apa, Vxa, and Msw can be calculated or acquired by another electronic control unit, and the calculated values (signals) can be transmitted to the ECU via the communication bus.

≪Electronic control unit ECU≫
The electronic control unit ECU includes an electric circuit (printed circuit board) including the processor CPUb, and is fixed to the vehicle body BDY. Here, the “processor” is an electronic circuit that executes arithmetic processing, and is “CPU (Central Processing Unit)”, and the “printed circuit board” is an integrated circuit, a resistor, a capacitor, or the like. The electronic component is a plate-like component that constitutes an electronic circuit by being fixed on the surface and connecting the electronic components by wiring.

  A target pressing force calculation block FBT and a parking brake necessity determination block FPK are programmed in the processor CPUb of the electronic control unit ECU. In the target pressing force calculation block FBT, the target pressing force Fbt is calculated based on Bpa. In the parking brake necessity determination block FPK, the necessity for the parking brake is determined based on Msw and the like. Specifically, signal FLpk for instructing the operation or release of the parking brake is determined. Here, the signal FLpk is a control flag, “FLpk = 0” represents a parking brake unnecessary state, and “FLpk = 1” represents a parking brake necessary state. The instruction signal FLpk is transmitted to the drive circuit DRV via the signal line SGL. Further, electric power for driving the electric motor MTR is supplied from the BAT or the like to the drive circuit DRV via the electronic control unit ECU.

<< Target pressing force calculation block FBT and target pressing force Fba >>
Details of the target pressing force calculation block FBT will be described. FBT is a control algorithm and is programmed in the processor CPUb in the ECU. FBT is a control algorithm for calculating a target value Fbt in a so-called normal brake function.

  In the target pressing force calculation block FBT, a target pressing force (target signal) Fbt relating to the force (pressing force) by which the friction member (brake pad) MSB presses the rotating member (brake disc) KTB is calculated. Specifically, Fbt is calculated based on the brake operation amount Bpa and a preset calculation map CHfb. And Fbt is transmitted to the drive circuit DRV fixed to the wheel WHL side via the signal line SGL.

≪Parking brake necessity determination block FPK and instruction signal FLpk≫
Details of the parking brake necessity determination block FPK will be described. In the parking brake necessity determination block FPK, it is determined whether or not a parking brake (also referred to as a parking brake) for maintaining the stop state of the vehicle is necessary. That is, in FPK, the determination of the operation of the parking brake or the release of the parking brake is executed, and the determination result FLpk is calculated. The signal FLpk is a control flag indicating whether or not a parking brake is necessary. For example, FLpk is expressed by “0 (unnecessary determination result)” or “1 (necessary determination result)”.

  The parking brake necessity determination block FPK includes a manual mode based on the driver's switch operation and an automatic mode based on the vehicle speed and the like.

  The switch signal Msw, the vehicle speed Vxa, and the acceleration operation amount Apa are input to the parking brake necessity determination block FPK. The FPK outputs a parking brake control flag FLpk. Specifically, when “no parking brake is required (unnecessary determination)” is determined, FLpk = 0 is output as the instruction signal. When it is determined that “a parking brake is necessary (necessity determination)”, FLpk = 1 is output as an instruction signal. The control flag (instruction signal) FLpk is transmitted to the drive circuit DRV via the communication line SGL.

  In the manual mode of the parking brake necessity determination block FPK, the necessity of the parking brake is determined based on the operation signal Msw of the parking brake manual switch MSW operated by the driver. For example, “unnecessary parking brake state (FLpk = 0)” is selected depending on the switch MSW off state, and “necessary parking brake state (FLpk = 1)” is selected depending on the MSW on state.

  In the automatic mode of the parking brake necessity determination block FPK, whether or not the parking brake is necessary (actuated or released) automatically in conjunction with the operation of the acceleration operation member (accelerator pedal) AP, regardless of the driver's operation of the switch MSW. ) Is determined. Specifically, in the automatic mode, whether or not a parking brake is necessary is determined based on the vehicle speed Vxa and the acceleration operation amount Apa.

  For example, when the vehicle is traveling (Vxa> 0), it is determined that the parking brake is not needed (FLpk = 0). When the vehicle stops (that is, when Vxa becomes zero), the necessity state of the parking brake is determined, and the control flag FLpk is switched from “0” to “1”. Further, when the driver operates the acceleration operation member AP and the acceleration operation amount Apa exceeds the predetermined value ap1, it is determined that the parking brake is not required, and the control flag FLpk is switched from “1” to “0”. It is done.

≪Storage battery BAT and generator ALT≫
The storage battery (battery) BAT and the generator (alternator) ALT supply power to the electronic control unit ECU, the drive circuit DRV, and the electric motor MTR. The storage battery BAT and the generator ALT are collectively referred to as a power source.

  The power sources BAT and ALT are fixed on the vehicle body BDY side. When the storage amount of the storage battery BAT decreases, the BAT is charged by the alternator ALT. The power (current) from the power sources BAT and ALT is supplied to the drive circuit DRV (finally, the electric motor MTR) via the power line PWL.

<< braking means BRK, friction member MSB, and rotating member KTB >>
The braking means (brake actuator) BRK is provided on the wheel WHL, applies braking torque to the wheel WHL, and generates braking force. During traveling, the vehicle is decelerated by BRK (normally functions as a brake). Further, when the vehicle is stopped, it functions as a parking brake that maintains the stopped state.

  As the electric braking means BRK, a so-called disc type braking device (disc brake) is exemplified. In this case, the friction member MSB is a brake pad, and the rotating member KTB is a brake disc. The braking means 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.

  Details of the braking means BRK will be described. Brake means BRK includes brake caliper CRP, pressing member PSN, electric motor MTR, position acquisition means MKA, reduction gear GSK, shaft member SFT, screw member NJB, pressing force acquisition means FBA, drive circuit DRV, connector CNC, and parking It is composed of a brake locking mechanism LOK.

(Brake caliper CRP and pressing member PSN)
A floating caliper may be employed as a brake caliper (also simply referred to as a caliper) CRP. The caliper CRP is configured to sandwich a rotating member (brake disc) KTB via two friction members (brake pads) MSB.

  A part of the caliper CRP has a box-type structure. Specifically, the caliper CRP has a space inside, and various members (such as a drive circuit DRV) are accommodated therein. A portion having a box structure of the caliper CRP is referred to as a case member CAS. That is, the case member CAS is a part of the caliper CRP, and the inside thereof is hollow. In the relationship between the caliper CRP and CAS, a structure in which both are formed integrally or a structure in which those formed separately are combined may be employed.

  Inside the caliper CRP, the pressing member (brake piston) PSN is moved (advanced or retracted) with respect to the rotating member KTB. By the movement of the pressing member PSN, the friction member MSB is pressed against the rotating member KTB, and a frictional force is generated. For example, PSN has a cylindrical shape and a central axis Jps. Therefore, the PSN is moved in the direction of the axis Jps.

  The movement of the pressing member PSN is performed by the power of the electric motor MTR. Specifically, the output of the electric motor MTR (rotational power around the motor shaft) is transmitted to the shaft member SFT via the reduction gear GSK. Then, the rotational power (torque about the shaft axis) of the shaft member SFT is converted into linear power (thrust in the axial direction of the pressing member) by the power conversion member NJB and transmitted to the pressing member PSN. As a result, the pressing member PSN is moved (advanced or retracted) with respect to the rotating member KTB. Here, the central axis Jps of PSN coincides with the rotation axis of SFT.

  By the movement of the pressing member PSN, the force (pressing force) by which the friction member MSB presses the rotating member KTB is adjusted. Since rotating member KTB is fixed to wheel WHL, a frictional force is generated between friction member MSB and rotating member KTB, and the braking force of wheel WHL is adjusted.

(Electric motor MTR)
The electric motor MTR is a power source for driving (moving) the pressing member PSN. For example, a motor with a brush or a brushless motor can be employed as the electric motor MTR. 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). Electric power to the electric motor MTR is supplied through the power line PWL and the connector CNC.

(Position acquisition means MKA and actual position Mka)
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. For example, the position acquisition means MKA is provided inside the electric motor MTR and coaxially with the rotor and the commutator. That is, the MKA is provided on the rotation axis Jmt of the electric motor MTR. The detected position (rotation angle) Mka is input to the drive circuit DRV (specifically, the processor CPUw in the drive circuit DRV).

(Reduction gear GSK, shaft member SFT, and screw member NJB)
The reduction gear GSK, the shaft member SFT, and the screw member NJB are power transmission mechanisms for transmitting the power of the electric motor MTR to the pressing member PSN. The reduction gear GSK reduces the rotational speed of the power of the electric motor MTR and outputs it to the shaft member SFT. The rotational output (torque) of the electric motor 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, GSK is configured by a gear transmission mechanism. Further, 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 screw member NJB is a power conversion mechanism (rotation / linear motion conversion member) that converts the rotational power of the shaft member SFT into linear power. For example, a sliding screw (such as a trapezoidal screw) or a rolling screw (such as a ball screw) can be employed as the NJB.

(Pressing force acquisition means FBA and actual pressing force Fba)
The pressing force acquisition means (for example, a pressing force sensor) FBA acquires (detects) a force (pressing force) Fba that the pressing member PSN presses the friction member MSB. The detected actual pressing force Fba is input to the drive circuit DRV (specifically, the CPUw in the DRV). For example, the pressing force acquisition means FBA is provided between the shaft member SFT and the caliper CRP. That is, it is provided on the rotating shaft of the shaft member SFT and is fixed to the caliper CRP.

(Drive circuit DRV)
The drive circuit (electric circuit) DRV is an electric circuit (printed circuit board) that drives the electric motor MTR and a solenoid actuator (also simply referred to as a solenoid) SOL. The drive circuit DRV is disposed (fixed) inside the case member CAS. The drive circuit DRV is provided with a processor (arithmetic processing unit) CPUw, a bridge circuit HBR, and the like. Control means CTL (control algorithm) is programmed in CPUw.

  The electric motor MTR is driven by the drive circuit DRV based on the target pressing force Fbt, the output is controlled, and the normal brake function is exhibited. Further, the electric motor MTR and the solenoid SOL are controlled by the drive circuit DRV based on the instruction signal (control flag) FLpk, and the parking brake function is exhibited. Fbt and FLpk are transmitted from the CPUb in the ECU to the CPUw in the drive circuit DRV via the signal line SGL and the connector CNC.

(Connector CNC)
Connector CNC is a metal terminal (terminal) fixed with an insulator such as resin, connecting between components, or between wiring (cable) and components, power, and / or , Exchange signals with each other. Specifically, the connector CNC is provided in a CAS (a part of the caliper CRP) on the wheel WHL side so as to relay at least one of the power line PWL and the signal line SGL. The connector CNC can be fixed on the drive circuit DRV. The connector CNC is shared for feeding (relaying PWL) and transmission (relaying SGL), but each may be provided separately.

(Parking brake mechanism (lock mechanism) LOK)
The parking brake mechanism (also referred to as a lock mechanism) LOK is locked so that the electric motor MTR does not rotate in the reverse rotation direction because of the brake function (so-called parking brake) that maintains the stopped state of the vehicle. As a result, the pressing member PSN is restrained from moving away from the rotating member KTB, and the pressing state of the rotating member KTB by the friction member MSB is maintained. Here, the lock mechanism LOK can be provided between the electric motor MTR and the reduction gear GSK (that is, coaxially with the electric motor MTR).

  The lock mechanism LOK includes a ratchet gear (also referred to as a pawl gear) RCH, a pawl member (also referred to as a hook claw) TSU, and a solenoid actuator (also referred to simply as a solenoid) SOL. The ratchet gear RCH is fixed to the input member INP coaxially with the INP. The ratchet gear RCH is different from a general gear (for example, a spur gear), and the teeth have directionality. The claw member TSU is pushed in the direction of the ratchet gear RCH by the solenoid SOL, and the claw member TSU is moved toward the ratchet gear RCH. Then, when the pawl member TSU is engaged with the ratchet gear RCH, the movement of the pressing member PSN is restrained and functions as a parking brake. Here, the solenoid SOL and the pawl member TSU are separate members and are separated from each other.

<Arrangement of lock mechanism LOK for parking brake>
FIG. 2 is a partial cross-sectional view for explaining the shaft configuration of the braking means BRK and the arrangement of the parking brake mechanism (lock mechanism) LOK.

  In the braking means BRK, a so-called multi-axis configuration having at least two different rotation axes (Jin, Jsf, etc.) is adopted. That is, the input part of BRK (axis of electric motor MTR, INP, etc.) and the output part (axis of PSN, NJB, SFT, etc.) are arranged side by side. Here, the input shaft Jin and the output shaft Jsf in the reduction gear GSK are parallel.

  The relationship among the input member INP, the reduction gear GSK, and the shaft member SFT when the multi-axis configuration is adopted will be described. The rotational speed of the power of the input member INP is reduced by the speed reducer GSK and output to the shaft member SFT. At this time, a rotational force (torque) proportional to the GSK reduction ratio is obtained as the output power of the shaft member SFT.

  For example, a two-stage reduction gear can be adopted as the reduction gear GSK. Specifically, the first speed reduction is performed by a set of the first small diameter gear SK1 and the first large diameter gear DK1, and the second speed reduction is performed between the second small diameter gear SK2 and the second large diameter gear DK2. Done by a pair.

  The first small-diameter gear SK1 is fixed to the input member INP and is rotated around the rotation axis Jin together with the INP. The first large-diameter gear DK1 is fixed to the intermediate shaft member CHU, and is rotated around the rotation axis Jch together with the CHU. The bearing of SK1 (INP) and the bearing of DK1 (CHU) are fixed to the caliper CRP. The teeth of SK1 and DK1 are engaged with each other. The pitch circle diameter of the first large gear DK1 is larger than the pitch circle diameter of the first small gear SK1, and the number of teeth of the first large gear DK1 is larger than the number of teeth of the first small gear SK1. That is, the power of the first small diameter gear SK1 is decelerated and output from the first large diameter gear DK1.

  The second small diameter gear SK2 is fixed to the intermediate shaft member CHU, and is rotated around the rotation axis Jch together with the CHU. The second large-diameter gear DK2 is fixed to the shaft member SFT, and is rotated around the rotation axis Jsf together with the SFT. The bearing of SK2 (CHU) and the bearing of DK2 (SFT) are fixed to the caliper CRP. The teeth of SK2 and DK2 are engaged with each other. The pitch circle diameter of the second large diameter gear DK2 is larger than the pitch circle diameter of the second small diameter gear SK2, and the number of teeth of the second large diameter gear DK2 is larger than the number of teeth of the second small diameter gear SK2. That is, the power of the second small diameter gear SK2 is decelerated and output from the second large diameter gear DK2.

  With the above configuration, the rotational power transmitted from the input member INP is input from the first small-diameter gear SK1 to the speed reducer GSK, decelerated in two stages, and output from the second large-diameter gear DK2 to the shaft member SFT. . A one-stage reduction gear can be used as the reduction gear GSK. In this case, power from the input member INP is input to the first small-diameter gear SK1, decelerated by SK1 and DK1, and output from the shaft member SFT. Due to the multi-axis configuration, the BRK can be shortened in the axial direction (PSN Jps direction), and the degree of layout freedom can be increased. Further, the reduction ratio of the reduction gear GSK is set to be relatively large, and the distance between the axes of Jin and Jsf can be shortened.

  An Oldham coupling OLD may be provided between the electric motor MTR and the input member INP. That is, the output part MOT of the electric motor MTR is connected to the input member INP via the Oldham coupling OLD. Here, the Oldham coupling OLD is a coupling that transmits power by sliding the fitting between the protrusion (key) of the disk and the groove (key groove) of the slider. The Oldham coupling OLD absorbs the eccentricity between the rotating shaft (also referred to as the motor shaft) Jmt of the electric motor MTR and the rotating shaft (also referred to as the input shaft) Jin of the input member INP, and the rotational power (rotational motion) of the electric motor MTR is absorbed. ) Is transmitted to the INP.

  A ratchet gear RCH of the lock mechanism LOK is fixed to the input member INP. That is, the ratchet gear RCH is provided on the opposite side to the electric motor MTR side with respect to the Oldham coupling OLD. The transmission torque of the input member INP is not increased by the reduction gear GSK and is equal to the output torque of the electric motor MTR. Since the ratchet gear RCH is fixed to the input member INP, the force acting on the ratchet gear RCH can be relatively reduced, and the lock mechanism LOK can be downsized (for example, the diameter of the ratchet gear RCH can be reduced, and the tooth width of the RCH can be reduced). , The output of the solenoid SOL can be reduced). Further, when torque is repeatedly applied to the Oldham coupling OLD, fitting portions (keys and key grooves) are worn, and backlash (gap between contact surfaces between machine elements in the rotational motion direction) may increase. . The ratchet gear RCH is provided on the input member INP (the RCH is fixed on the opposite side of the MTR from the OLD), thereby avoiding a reduction in pressing force (loose parking brake) caused by OLD wear or the like. obtain.

<Drive circuit DRV>
FIG. 3 is a functional block diagram for explaining details of the drive circuit DRV and the control means CTL programmed in the DRV. FIG. 3 shows an example of a drive circuit 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.

<< Power Line PWL and Signal Line SGL >>
The power line PWL is an electrical path for supplying power from the power sources BAT and ALT to the electric motor MTR and the solenoid SOL. The power line PWL is relayed by the connector CNC provided in the case member CAS. As the power line PWL, a twisted pair cable (Twisted Pair Cable) formed by twisting two electric wires together can be adopted.

  The signal line SGL is a signal transmission path for transmitting (transmitting) signals Fbt and FLpk for controlling the electric motor MTR and the solenoid SOL from the ECU (CPUb) to the drive circuit DRV (CPUw). A serial communication bus can be adopted as the signal line SGL. The serial communication bus is a communication method in which data is transmitted bit by bit in series within one communication path. For example, a CAN (Controller Area Network) bus can be adopted as the serial communication bus.

  The power line PWL and the signal line SGL are relayed by the connector CNC. Here, the connector CNC is provided on the surface of the case member CAS which is a part of the caliper CRP. The power line PWL and the signal line SGL are collectively referred to as wiring (harness).

≪Drive circuit DRV≫
The drive circuit DRV is an electric circuit (printed circuit board) for driving the electric motor MTR and the solenoid SOL. Specifically, the drive circuit DRV adjusts the energization state to the electric motor MTR based on the target pressing force Fbt, and exhibits the normal brake function. Moreover, the drive circuit DRV adjusts the energization state to the electric motor MTR and the solenoid SOL based on the instruction signal FLpk, and exhibits the parking brake function. The drive circuit DRV includes a bridge circuit HBR, an HBR energization amount acquisition unit (first energization amount acquisition unit) IMA, a switching element SS, a solenoid SOL energization amount acquisition unit (second energization amount acquisition unit) ISA, and a control unit. Consists of CTL. The drive circuit DRV is housed and fixed inside a case member CAS that is a part of the caliper CRP.

(Bridge circuit HBR)
The bridge circuit is a circuit in which the energization direction to the electric motor can be changed with a single power source without requiring a bi-directional power source, and the rotation direction (forward direction or reverse direction) of the electric motor can be controlled. It is. The bridge circuit HBR is configured by switching elements S1 to S4. The switching elements S1 to S4 are elements that can turn on (energize) / off (non-energize) a part of the electric circuit. The switching elements S1 to S4 are driven by the control means CTL (signal from the switching control block SWT), and by switching the energization / non-energization state of each switching element, the rotation direction and output torque of the electric motor MTR are changed. Is adjusted. For example, a MOS-FET or IGBT is used as the switching element.

  When the electric motor MTR is driven in the forward rotation direction, S1 and S4 are turned on (on state), and S2 and S3 are turned off (off state). That is, in the forward rotation driving of the electric motor MTR in which the braking torque is increased, a current is passed in the order of “S1 → electric motor MTR (BLC / CMT) → S4”. Conversely, when the electric motor MTR is driven in the reverse direction, S1 and S4 are set in a non-energized state (off state), and S2 and S3 are set in a energized state (on state). That is, in the reverse rotation driving of the electric motor MTR in which the braking torque is reduced, the current flows in the reverse direction from the normal rotation driving in the order of “S2 → electric motor MTR (BLC / CMT) → S3”.

  When a brushless motor is employed instead of the brush motor, the bridge circuit HBR is configured by six switching elements. As in the case of the motor with brush, the energization state / non-energization state of the switching element is controlled based on the duty ratio Dut. In the brushless motor, the position acquisition means MKA acquires the rotor position (rotation angle) Mka of the electric motor MTR. Based on the actual position Mka, the six switching elements constituting the three-phase bridge circuit are controlled. The direction of the coil energization amount of the U-phase, V-phase, and W-phase of the bridge circuit (that is, the excitation direction) is sequentially switched by the switching element to drive the electric motor 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.

(First energization amount acquisition means (for electric motor MTR) IMA)
An energization amount acquisition means (for example, a current sensor) IMA for the electric motor is provided in the bridge circuit HBR. The energization amount acquisition means IMA acquires the energization amount (actual value) Ima of the electric motor MTR. For example, the current value that actually flows through the electric motor MTR can be detected as Ima by the motor current sensor IMA.

(Switching element SS)
The switching element SS controls the energization state to the solenoid SOL. Specifically, the switching element SS is an element that can turn on (energize) / off (non-energize) a part of the electric circuit, and is driven by the control means CTL (signal from the solenoid control block SCT) to switch the switching element SS. The energized / non-energized state of is switched. As a result, generation / release of the suction force of the solenoid SOL is switched. For example, a MOS-FET, IGBT, or relay can be used as the switching element SS.

(Second energization amount acquisition means (for solenoid SOL) ISA)
A solenoid energization amount acquisition means (for example, a current sensor) ISA is provided. The energization amount acquisition means ISA acquires the energization amount (actual value) Isa of the solenoid SOL. For example, the current value that actually flows through the solenoid SOL can be detected as Isa by the solenoid current sensor ISA.

≪Control means CTL≫
Based on the target pressing force (target value) Fbt, the control means CTL adjusts the energization state (finally the magnitude and direction of the current) to the electric motor MTR and controls the output and rotation direction of the electric motor MTR. . Further, the control means CTL adjusts the energization state of the electric motor MTR and the solenoid SOL based on the parking brake necessity determination result FLpk, and controls the biting operation of the lock mechanism LOK. The control means CTL is a control algorithm and is programmed in the processor CPUw in the drive circuit DRV.

  The control means CTL includes an instruction energization amount calculation block IST, a pressing force feedback control block IBT, an energization amount adjustment calculation block IMT, a pulse width modulation block PWM, a switching control block SWT, a parking brake control block IPK, and a solenoid control block SCT. Configured.

  The control means CTL includes control for exerting two functions of a normal brake and a parking brake. In CTL, either one of the two functions is selected by the selection means SNT in the energization adjustment calculation block IMT. For this reason, the two functions are not activated simultaneously. Specifically, the normal brake function is selected when the driver operates the braking operation member BP, and the parking brake function is selected when there is no operation.

[Normal brake function]
First, functional blocks related to normal braking will be described. Here, the normal brake is a brake function according to the driver's operation of the braking operation member BP, such as deceleration of the running vehicle and maintenance of the vehicle stop state. The normal brake function includes an instruction energization amount calculation block IST, a pressing force feedback control block IBT, an energization amount adjustment calculation block IMT, a pulse width modulation block PWM, and a switching control block SWT.

(Instruction energization amount calculation block IST)
The command energization amount calculation block IST calculates the command energization amount Ist based on the target pressing force Fbt determined based on the braking operation amount Bpa and preset calculation characteristics (calculation maps) CHs1 and CHs2. The command energization amount Ist is a target value of the energization amount to the electric motor MTR for achieving the target pressing force Fbt. The calculation map of the command energization amount Ist is composed of two characteristics CHs1 and CHs2 in consideration of the hysteresis of the braking means BRK.

  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 the pulse width modulation, this duty ratio can be used as the energization amount.

(Pressure force feedback control block IBT)
The pressing force feedback control block IBT calculates a pressing force feedback energization amount Ibt based on the target pressing force (target value) Fbt and the actual pressing force (actual value) Fba. The pressing force feedback energization amount Ibt 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) CHb. Although the command energization amount Ist is calculated as a value corresponding to the target pressing force Fbt, there may be an error between the target pressing force Fbt and the actual pressing force Fba due to the efficiency variation of the braking means BRK. Therefore, Ist is determined so as to reduce the error.

(Energization amount adjustment calculation block IMT)
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 case of normal braking, in the energization amount adjustment calculation block IMT, the command energization amount Ist is adjusted by the pressing force feedback energization amount Ibt, and the target energization amount Imt is calculated. Specifically, the feedback energization amount Ibt is added to the command energization amount Ist, and the target energization amount Ims is calculated. Then, the target energization amount Ims is selected and output as the final target energization amount Imt by the selection means SNT in the energization amount adjustment calculation block IMT.

  The direction of rotation of the electric motor MTR is determined based on the sign (the sign of the value) of the target energization amount Imt, and the output (rotational power) of the electric motor MTR is controlled based on the magnitude of the target energization amount Imt. 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 (in the increasing direction of the pressing force), and the sign of Imt is a negative sign. In some cases (Imt <0), the electric motor MTR is driven in the reverse direction (in the pressing force decreasing direction). In addition, the output torque of the electric motor MTR is controlled to increase as the absolute value of the target energization amount Imt increases, and the output torque is controlled to decrease as the absolute value of Imt decreases.

(Pulse width modulation block PWM)
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. Specifically, the pulse width modulation block PWM is based on the target energization amount Imt and a preset characteristic (computation map), and the pulse width duty ratio Dut (in the periodic pulse wave, the pulse corresponding to the cycle). Width (ratio of ON state). In addition, the pulse width modulation block PWM determines the rotation direction of the electric motor MTR based on the sign (positive sign or negative sign) of the target energization amount Imt. 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, in PWM, the rotation direction of the electric motor MTR and the energization amount to the electric motor MTR (that is, the output of the electric motor MTR) are determined. It is determined.

  Further, in the pulse width modulation block PWM, so-called current feedback control can be executed. In this case, the detection value (for example, actual current value) Ima of the energization amount acquisition unit IMA is input to the pulse width modulation block 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.

(Switching control block SWT)
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 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 electric motor 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 a energized state (on state). The state (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 is caused to flow through the electric motor MTR.

[Parking brake function]
Next, functional blocks related to the parking brake will be described. In the parking brake, the stop state of the vehicle is maintained when the driver is not operating the braking operation member BP. The parking brake has two operations, a “starting operation” for switching from the non-operating state of the parking brake to an operating state and a “release operation” for transitioning from the operating state to the non-operating state. The start and release are determined based on a change (0 → 1 or 1 → 0) of the instruction signal FLpk. The parking brake function includes a parking brake control block IPK, an energization amount adjustment calculation block IMT, a pulse width modulation block PWM, a switching control block SWT, and a solenoid control block SCT.

(Parking brake control block IPK)
In the parking brake control block IPK, the parking brake target energization amount Ipk is determined based on the control flag FLpk indicating whether the parking brake is necessary, the pressing force (actual value) Fba, and the rotation angle (actual value) Mka of the electric motor MTR. , And a solenoid energization instruction signal FLs is calculated.

  In the parking brake control block IPK, a parking brake target energization amount Ipk for controlling the electric motor MTR in response to a parking brake operation start command (switching from “0” to “1” in the determination result FLpk), and A solenoid instruction signal FLs for instructing energization of the solenoid SOL is output. Here, Ipk is a target value of the energization amount of the electric motor MTR in the parking brake control, and is determined according to a preset characteristic. The signal FLs is a control flag, and “FLs = 0” instructs deenergization to the solenoid SOL, and “FLs = 1” instructs energization to the solenoid SOL.

(Energization amount adjustment calculation block IMT, pulse width modulation block PWM, and switching control block SWT)
In the energization amount adjustment calculation block IMT, the target energization amount Ims for the normal brake and the target energization amount Ipk for the parking brake are adjusted. The energization amount adjustment calculation block IMT is provided with a selection unit SNT, and one of Ims and Ipk is selected, and the final target energization amount Imt is output. Specifically, the larger one of the normal brake target value Ims and the parking brake target value Ipk is selected as the final target value Imt by the selection means SNT. The selection means SNT can suppress interference between the target energization amount Ims for the normal brake and the target energization amount Ipk for the parking brake. Since the pulse width modulation block PWM and the switching control block SWT are the same as those described above, description thereof is omitted.

(Solenoid control block SCT)
In the solenoid control block SCT, a drive signal for switching between energization and non-energization of the switching element SS is determined based on the solenoid drive command signal (control flag) FLs. Specifically, based on “FLs = 0”, a drive signal for turning off the switching element SS is output. Further, based on “FLs = 1”, a drive signal for turning on the switching element SS is output.

<< Electric motor MTR and rotation angle acquisition means MKA >>
A motor with a brush (also referred to as a brush motor) is employed as the electric motor MTR. In the brush motor, the current flowing through the armature (electromagnet by winding) is switched according to the rotation phase by the mechanical commutator (commutator) CMT and the brush BLC. In the brush motor, 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 the commutator CMT rotates, and current is commutated.

  The electric motor MTR is provided with a rotation angle acquisition means MKA that acquires (detects) the rotation angle (actual value) Mka of the rotor. The MKA is provided coaxially with the electric motor MTR, and transmits the rotation angle Mka to the processor CPUw. For example, MKA is output as a digital value from MKA.

  As the electric motor MTR, a brushless motor may be employed instead of the brush motor. In the brushless motor, current commutation is performed by an electronic circuit instead of the mechanical commutator CMT of the motor with brush. 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.

<< Pressing force acquisition means FBA and analog / digital conversion means ADH >>
The pressing force acquisition means FBA acquires (detects) a force (pressing force) Fba that the pressing member PSN presses the friction member MSB. Specifically, in the pressing force acquisition unit FBA, the pressing force Fba is based on an electrical change (for example, a voltage change) caused by a displacement (that is, a strain) generated when a force is applied, such as a strain gauge. Detected.

  The pressing force acquisition means FBA is provided between the screw member NJB and the caliper CRP. For example, the pressing force acquisition means FBA is fixed to the caliper CRP, and the reaction force (reaction) that the pressing member PSN receives from the friction member MSB is acquired as the pressing force Fba.

  The pressing force (actual value) Fba is transmitted to the processor CPUw via the analog / digital conversion means (AD conversion means) ADH. For example, the FBA detection signal is an analog value, but is converted into a digital value by the analog / digital conversion means ADH and input to the control means CTL. At this time, the resolution (least significant bit, LSB: Least Significant Bit) of the pressing force Fba is determined by the number of bits of the conversion means ADH.

≪Lock mechanism LOK (solenoid SOL, ratchet gear RCH, and pawl member TSU) ≫
The caliper CRP is provided with a parking brake lock mechanism LOK so that the pressing force Fba (the force by which the friction member MSB pushes the rotating member KTB) is maintained even when the electric motor MTR and the solenoid SOL are de-energized. It is done. The lock mechanism LOK includes a solenoid SOL, a pawl member TSU, and a ratchet gear RCH.

  The ratchet gear RCH is supported by the caliper CRP in a rotatable state. The solenoid SOL is fixed to the caliper CRP, and the claw member TSU is pressed toward the ratchet gear RCH at the tip (push bar) thereof. When the pawl member TSU is engaged with the ratchet gear RCH, the rotational movement of the ratchet gear RCH is restricted. As a result, the movement of the pressing member PSN is limited, and the pressing force Fba is maintained and the parking brake function is exhibited even when the energization to the braking means BRK is stopped.

<Parking brake lock mechanism LOK>
FIG. 4 is a schematic diagram for explaining the details of a parking brake locking mechanism (simply referred to as a locking mechanism) LOK. The lock mechanism LOK is configured as a ratchet mechanism (claw brake) and allows rotation in one direction (the direction indicated by the arrow Fwd, in which the pressing force increases), but rotation in the other direction (indicated by the arrow Rvs). Direction in which the pressing force decreases). 4A shows a state where the parking brake is released, and FIG. 4B shows a state where the parking brake is operating. The lock mechanism LOK includes a solenoid SOL, a pawl member TSU, a guide member GID, a ratchet gear RCH, and an elastic member SPR.

  The solenoid SOL is fixed to the caliper CRP. When the lock mechanism LOK transitions from the released state to the activated state, the pawl member TSU is pressed toward the ratchet gear RCH by the push bar PBR which is a part of the solenoid SOL by energizing the solenoid SOL. Specifically, the pawl member TSU receives a force from the solenoid SOL in a direction (intermeshing direction) Dts that is parallel to the central axis Jpb of the push bar PBR and approaches the rotation axis Jrc of the ratchet gear RCH. The pawl member TSU is positioned by a guide member GID fixed to the caliper CRP, and is allowed only in the movement in the biting direction Dts and the opposite direction (release direction) Dtr. Here, the biting direction Dts and the release direction Dtr are collectively referred to as a “first linear direction”. That is, the movement of the pawl member TSU in the direction inclined with respect to the first linear direction is prevented by the guide member GID. A parking brake function is exhibited when the pawl member TSU meshes with the ratchet gear RCH. The pawl member TSU is not rotationally moved around a certain fulcrum, but is linearly moved by the solenoid SOL and meshed with the ratchet gear RCH. The ratchet gear RCH is supported in a state that it can rotate with respect to the caliper CRP.

≪Solenoid actuator SOL≫
A solenoid actuator (simply referred to as a solenoid) SOL is an electromagnetic functional member that converts electrical energy into mechanical linear motion. The solenoid SOL includes a coil COL, a fixed iron core (also referred to as a base) BAS, a movable iron core (also referred to as a plunger) PLN, a push bar PBR, a housing HSG, and an air gap spacer AGS.

  The coil COL and the base BAS are housed in the housing HSG and fixed thereto. The housing HSG is fixed to the caliper CRP. That is, the solenoid SOL is fixed to the caliper CRP.

  The coil COL includes a bobbin, a copper wire, a lead wire, and an exterior tape, and generates a magnetic field when a current is passed through the copper wire (conductive wire). When a magnetic field is generated in the coil COL by energization, the magnetic flux passes through the fixed iron core (base) BAS, and the BAS attracts the movable iron core (plunger) PLN. While the power is being supplied, the plunger PLN is always attracted to the base BAS, but when the current is cut off, this suction force is extinguished. Here, the plunger PLN is a magnetic body and is a mechanical component of the solenoid SOL that reciprocates.

  Push bar PBR is fixed to plunger PLN. Therefore, the plunger PLN and the push bar PBR are integrated, and the operation of the PBR pushing the pawl member TSU is performed according to the suction operation of the PLN. An air gap spacer AGS can be incorporated between the plunger PLN and the base BAS. The air gap spacer AGS can stop the energization of the solenoid SOL and reduce the influence of residual magnetism when the position of the plunger PLN is restored.

≪Nail material TSU≫
The claw member TSU is provided with a protrusion (claw) Tme at one end. This protruding portion Tme is engaged with the ratchet gear RCH. Here, when the pawl member TSU and the ratchet gear RCH are engaged with each other, the contact surface between the protruding portion (claw) Tme of the TSU and the teeth of the RCH is referred to as a contact portion (engagement portion) Stm. The other end of the pawl member TSU is in contact with the push bar PBR. When the solenoid SOL is energized, the pawl member TSU is pushed by the push bar PBR and moved in the direction (engagement direction) Dts toward the ratchet gear RCH. Here, the central axis Jpb of the push bar PBR and the central axis Jts of the pawl member TSU coincide, and the biting direction Dts is parallel to the central axis Jts of the TSU (that is, the central axis Jpb of the PBR), This is a direction approaching the rotation axis Jrc of the ratchet gear RCH.

  In the pawl member TSU, a portion (the other end portion) that contacts the push bar PBR can be formed into a concave shape. Then, the push bar PBR and the recess (dent) of the pawl member TSU are fitted with a gap Spb. Here, the gap Spb is set to be relatively large. The concave portion does not position the claw member TSU and the push bar PBR relative to each other. When the solenoid SOL and the claw member TSU are assembled to the caliper CRP, the concave portion between the push bar PBR and the claw member TSU. This ensures the contact state.

  In the protrusion shape (claw shape) of the claw member TSU, a rake angle α is provided. Here, the rake angle α is an angle formed by the contact portion (meshing surface) Stm of the pawl Tme of the pawl member TSU and the biting direction Dts (first linear direction). As the contact surface Stm of the pawl member TSU (ie, pawl Tme) is closer to the rotation axis Jrc of the ratchet gear RCH due to the rake angle α, it includes the central axis Jts of the pawl member TSU and the rotation axis of the ratchet gear RCH. It is tilted away from a plane (center plane) Mts parallel to Jrc. In other words, the contact surface (engagement surface) Stm of the pawl member TSU is inclined with respect to the first linear direction in the direction (Rvs direction) in which the ratchet gear RCH rotates when the pressing force of the pressing member PSN decreases. Is done. It can also be said that the biting surface (plane) Stm of the TSU is inclined toward the direction in which the pawl member TSU moves away from the rotation axis Jrc of the ratchet gear RCH with respect to the first linear direction. In a state where the pawl member TSU and the ratchet gear RCH are engaged with each other, the pawl member TSU receives a force from the ratchet gear RCH at the contact portion Stm. However, due to the rake angle α, the component of this force is applied in the engagement direction Dts. Works. For this reason, even after the energization to the solenoid SOL is stopped, the positive engagement state between the pawl member TSU and the ratchet gear RCH can be maintained.

≪Guide member GID≫
The guide member GID is fixed to the caliper CRP and guides the movement of the pawl member TSU relative to the ratchet gear RCH (that is, functions as a guide surface). Specifically, the guide member GID is formed so as to surround the pawl member TSU, and the pawl member TSU and the guide member GID are in sliding contact with a relatively narrow gap Sgd. Here, the gap Sgd is set smaller than the gap Spb (Sgd <Spb). The pawl member TSU is allowed to slide only in the biting direction Dts and in the opposite direction (release direction) Dtr (that is, limited in the first linear direction). Since the ratchet gear RCH is positioned on the caliper CRP and the pawl member TSU is positioned by the guide member GID, the relative position between the ratchet gear RCH and the pawl member TSU is determined with high accuracy by the guide member GID. On the other hand, the push bar PBR and the pawl member TSU are loosely fitted, and relative positional accuracy is not required between them.

  In the shape of the guide member GID (of the guide surface), the side opposite to the front side (the back side) than the length Lft in the biting direction Dts on the side (front side) where the projection (claw) Tme of the claw member TSU exists The length Lbk in the side biting direction Dts can be set larger (longer). In a state where the pawl member TSU and the ratchet gear RCH are engaged with each other, the pawl member TSU receives a force from the ratchet gear RCH, and a bending moment acts. By setting the back side dimension Lbk to be relatively long, bending deformation of the pawl member TSU can be suppressed. As a result, sufficient bending strength of the pawl member TSU is ensured, and smooth movement of the pawl member TSU can be maintained.

≪Ratchet gear RCH≫
The ratchet gear RCH is fixed to the input member INP and rotates integrally with the INP. Unlike a general gear, the ratchet gear RCH is formed with directional teeth (sawtooth teeth). This “sawtooth” shape provides directionality to the rotational movement of the ratchet gear RCH about the rotational axis Jrc. Specifically, the movement corresponding to the forward rotation direction of the electric motor MTR (the movement in the direction in which PSN approaches KTB, Fba increases, and the braking torque increases) Fwd is allowed, but the reverse rotation direction of the electric motor MTR. Rvs is restrained (locked) (movement in a direction in which PSN moves away from KTB, Fba decreases, and braking torque decreases).

  In the tooth shape of the ratchet gear RCH, an inclination angle β is provided so that the rake angle α is engaged with the clamming member TSU. The inclination angle β is an angle formed by the plane Mhs formed by the tip (tooth tip) Phs of the ratchet gear RCH and the rotation axis Jrc, and the biting part (contact surface) Stm. Here, since the plane Mhs is a plane that divides the ratchet gear RCH into two in the axial direction, it is referred to as a “divided plane”. Due to the inclination angle β, the contact surface Stm of the ratchet gear RCH is inclined in a direction away from the dividing surface Mhs as it approaches the rotation axis Jrc of the ratchet gear RCH. In other words, when the pawl member TSU and the ratchet gear RCH are engaged, the contact surface (intermeshing surface) Stm of the ratchet gear RCH decreases when the pressing force of the pressing member PSN decreases with respect to the first linear direction. The ratchet gear RCH is inclined in the direction of rotation (Rvs direction). Further, in the occlusal state, it can be said that the meshing surface (plane) Stm of the RCH is inclined toward the direction in which the pawl member TSU approaches the rotation axis Jrc of the ratchet gear RCH with respect to the first linear direction. . When the biting portion Stm exists on a plane parallel to the Dts direction and including the rotation axis Jrc, the inclination angle β coincides with the rake angle α. However, if the central axis Jpb of the push bar PBR (that is, the central axis Jts of the pawl member TSU) is set to be offset in the direction in which the contact portion Stm moves when the ratchet gear RCH rotates in the Rvs direction, the inclination angle is set. β is smaller than the rake angle α.

  When the ratchet gear RCH and the pawl member TSU are engaged with each other, the rotation (Rvs direction) of the input member INP corresponding to the direction in which the pressing member PSN (that is, the friction member MSB) moves away from the rotating member KTB is locked. That is, the reverse rotation of the electric motor MTR is limited.

≪Elastic member SPR≫
An elastic member (for example, a return spring) SPR is provided between the guide member GID (that is, the caliper CRP) and the pawl member TSU in a compressed state. Therefore, the elastic member SPR always presses the pawl member TSU against the guide member GID (caliper CRP) in the direction (release direction) Dtr opposite to the biting direction Dts. When the solenoid SOL is energized, the plunger PLN is drawn into the solenoid SOL, and the push bar PBR presses the pawl member TSU in the engagement direction Dts. That is, the biting force in the biting direction Dts exerted on the pawl member TSU by the movable member PBR of the solenoid SOL is generated. When the suction force (occlusion force) of the solenoid SOL becomes larger than the pressing force (spring force, which is a force that pushes the TSU in the releasing direction Dtr) by the elastic member SPR, the pawl member TSU is moved to the position Pkm. The pawl member TSU and the ratchet gear RCH are engaged with each other. However, when the energization to the solenoid SOL is stopped, the suction force (holding force) of the plunger PLN is lost, and the pawl member TSU and the push bar PBR (plunger PLN) are returned to the position Pkj by the elastic member SPR. Here, the position Pkm is a position where the pawl member TSU and the ratchet gear RCH are engaged with each other (engagement position), and the position Pkj is a position where the pawl member TSU and the ratchet gear RCH are not engaged (release position).

[Transition to engagement state between pawl member TSU and ratchet gear RCH]
The outline of each member of the lock mechanism LOK has been described above. Next, a case where the pawl member TSU and the ratchet gear RCH are changed from a non-engaged state to an engaged state will be described with reference to FIGS.

  FIG. 4A shows the case where the solenoid SOL is not energized and the pawl member TSU and the ratchet gear RCH are not engaged with each other. Here, the pawl member TSU is pressed against the solenoid SOL (or caliper CRP) by the elastic force of the elastic member SPR. The position of the pawl member TSU is referred to as a release position Pkj.

  The electric motor MTR is energized, and the electric motor MTR is driven in the normal rotation direction Fwd. Accordingly, the pressing force Fba is increased. And after Fba reaches | attains a predetermined value, electricity supply to solenoid SOL (namely, coil COL) is started. By this energization, the plunger PLN is attracted to the base BAS, and the plunger PLN is pulled in the biting direction Dts. The suction force of the solenoid SOL (that is, the occlusal force that is the force by which the PBR pushes the TSU) is greater than the elastic force of the elastic member SPR (that is, the release force that is the force that releases the bite between the TSU and RCH). Thus, the push bar PBR fixed to the plunger PLN moves the pawl member TSU in the Dts direction (linear direction). At this time, the movement of the pawl member TSU is guided by the guide member GID, and the movement that causes deviation (tilt) with respect to the linear direction is suppressed.

  The electric motor MTR is driven in the reverse rotation direction Rvs while the pawl member TSU is in contact with the ratchet gear RCH. As a result, as shown in FIG. 4B, the pawl member TSU is reliably engaged with the ratchet gear RCH. After confirming this biting state, energization to the solenoid SOL is stopped, and energization to the electric motor MTR is also stopped.

  The claw member TSU is provided with a rake angle α, and the ratchet gear RCH is provided with an inclination angle β so as to correspond thereto. A force (tangential force) from the ratchet gear RCH acts on the pawl member TSU (particularly, the contact portion Stm) due to the rigidity of the caliper CRP, the friction member MSB, and the like. Since the tangential force component due to the rake angle α acts in the biting direction Dts, the biting state after the energization stop can be reliably maintained.

  When the contact portion Stm (the tip portion (tooth tip) Phs of the tooth meshing with the pawl member TSU) is parallel to the Dts direction and passes through the rotation axis Jrc of the RCH, the rake angle α (first The angle formed by one straight line direction and Stm is equal to the inclination angle β (the plane formed from Jrc to Phs and the angle formed by Stm). That is, when the length (offset distance) Los between the surface passing through the rotation axis Jrc of the ratchet gear RCH and the tooth tip Phs is zero, there is a relationship of α = β. However, the inclination angle β decreases as the offset distance Los increases. Specifically, the relationship α = β + θ is established, where θ is the angle formed by the plane extending from the rotation axis Jrc to the tooth tip Phs and the Dts direction.

[Transition to pawl member TSU and ratchet gear RCH released state (not bite state)]
As shown in FIG. 4B, the state in which the pawl member TSU and the ratchet gear RCH are engaged is maintained even when the electric motor MTR and the solenoid SOL are not energized. In order to release this biting state, the electric motor MTR is energized. At this time, energization to the solenoid SOL remains stopped.

  When the electric motor MTR is driven and rotated in the forward rotation direction Fwd, the pawl member TSU gets over the teeth of the ratchet gear RCH that have been engaged. At this time, the pawl member TSU is moved in the direction (release direction) Dtr away from the ratchet gear RCH by the elastic force (spring force) of the elastic member (compression spring) SPR. As a result, the engagement state between the pawl member TSU and the ratchet gear RCH is canceled, and the state returns to the state shown in FIG.

<Matching operation of pawl member TSU and ratchet gear RCH>
[Description and definition of each part name]
First, with reference to FIG. 5, the name of each part of the claw member TSU and the ratchet gear RCH will be described. Here, although the outer shape of the ratchet gear RCH is formed in an arc, it is expressed as a linear shape for convenience of explanation.

  Since the pawl member TSU is guided by the guide member GID, the pawl member TSU is allowed to move only in the direction of the central axis Jts. Here, a direction in which the pawl member TSU approaches the rotation axis Jrc of the ratchet gear RCH (that is, a direction away from the solenoid SOL) is referred to as an “engagement direction Dts (also referred to as a Dts direction)”. Conversely, the direction away from the rotation axis Jrc (that is, the direction approaching the solenoid SOL) is referred to as the “release direction Dtr (also referred to as Dtr direction)”. The occlusal direction Dts and the release direction Dtr correspond to the “first linear direction” and are opposite directions (reverse directions). Therefore, the biting force in the Dts direction exerted on the pawl member TSU by the solenoid SOL (particularly the push bar PBR) and the release force in the Dtr direction exerted by the elastic member SPR on the pawl member TSU oppose each other.

  The tip portion of the pawl Tme of the pawl member TSU is referred to as “claw tip Pts”. Further, the tip portion of the teeth of the ratchet gear RCH is referred to as “Addendum Phs”. A surface passing through the tooth tip Phs and concentric with the rotation axis Jrc of the ratchet gear RCH is referred to as a “tooth top surface Htp”. Further, the root of the tooth of the ratchet gear RCH is referred to as “Dedendum”, and the surface concentric with the rotation axis of the ratchet gear RCH through the root is referred to as “tooth bottom Hbm”.

  In a state where the pawl member TSU and the ratchet gear RCH are engaged with each other, a contact portion between the TSU and the RCH is referred to as a “contact portion Stm”. For example, in the contact portion Stm, the TSU and the RCH are brought into contact with each other (for example, a plane) (bite by surface contact). That is, the contact portion (engagement surface) Stm is from the tooth tip Pts of the TSU to the tooth tip Phs of the RCH meshing with the pawl member TSU. Furthermore, the angle between the contact portion (contact surface) Stm and the movement direction (linear movement) Dts, Dtr of the pawl member TSU relative to the ratchet gear RCH is referred to as a “rake angle α”.

  The teeth of the ratchet gear RCH have directionality, but the slope with the gentler slope is called “first slope Hs1”, and the slope with the steeper slope is called “second slope Hs2”. The angle of the second slope Hs2 with respect to the plane (divided surface) Mhs formed by the tooth tip Phs and the rotation axis Jrc is referred to as an inclination angle β. There is a predetermined geometric relationship between the rake angle α, the inclination angle β, and the distance (offset distance Los) from the surface parallel to the biting direction Dts and passing through the rotation axis Jrc to the contact portion Stm. To do. Here, the meshing surface (contact portion) Stm of the pawl member TSU with the ratchet gear RCH is “the direction in which the ratchet gear RCH rotates when the pressing force of the pressing member PSN decreases (with respect to the first linear direction ( Rvs direction) ”(in FIG. 5, the first linear direction is rotated clockwise and tilted so as to be parallel). That is, the meshing surface Stm of the Tme of the TSU is closer to the rotation axis Jrc of the ratchet gear RCH so as to be separated from the plane (the center plane of the TSU) Mts including the TSU center axis Jts and parallel to the RCH rotation axis Jrc. Tilted. Further, in a state where the pawl member TSU and the ratchet gear RCH are engaged with each other, the engagement surface Stm (contact portion on the second inclined surface Hs2) of the ratchet gear RCH with the pawl member TSU is “ The ratchet gear RCH is inclined in the direction of rotation (Rvs direction) when the pressing force of the pressing member PSN is reduced (in FIG. 5, similarly to the TSU Stm, the RCH Stm is in the first linear direction. Rotated clockwise and tilted parallel to this). That is, the meshing surface Stm of the RCH Hs2 becomes farther from the plane (RCH splitting surface) Mhs formed by extending the RCH rotational axis Jrc in the tooth tip Phs direction as it approaches the rotational axis Jrc of the ratchet gear RCH. Tilted like that.

  The pitch of the teeth of the ratchet gear RCH is represented by “distance Lpc”. The distance between the tooth tip surface Htp and the tooth bottom surface Hbm is “tooth height (tooth height) Hrc”. An intersection line between the second slope Hs2 and the tooth bottom surface Hbm is referred to as a “corner portion Psm”. The distance from the corner portion Psm to the intersection line between the first slope Hs1 and the tooth bottom surface Hbm is “tooth thickness (tooth thickness) Lrc”. The distance between the tooth tip surface Phs and the corner portion Psm is represented by “distance Lbt”. Here, the tooth tip Phs is an intersection line between the tooth tip surface Htp and the second slope Hs2. The distance Lbt is a displacement (distance) corresponding to the inclination angle β such that the pawl member TSU and the ratchet gear RCH are engaged with each other. Here, the inclination angle β is an angle between a plane (divided surface) Mhs from the tooth tip Phs of the contact portion Stm of the RCH to the rotation axis Jrc of the RCH and the second inclined surface Hs2.

  In the movement direction (rotation direction) of the ratchet gear RCH, the direction corresponding to the normal rotation direction of the electric motor MTR (that is, the direction in which the pressing force increases) is referred to as the RCH normal rotation direction Fwd (also referred to as the Fwd direction). The Conversely, the direction corresponding to the reverse rotation direction of the electric motor MTR (that is, the direction in which the pressing force decreases) is referred to as the reverse rotation direction Rvs (also referred to as the Rvs direction) of the ratchet gear RCH. Note that the Fwd direction and the Rvs direction are opposite directions (reverse directions). In the contact portion Stm of the claw member TSU, the length (distance) in the Rvs direction is referred to as “claw thickness Lts”. Specifically, the dimension of the pawl member TSU in the direction perpendicular to the central axis Jts of the pawl member TSU from the contact point with the tooth tip Phs in the contact portion Stm is the pawl thickness Lts.

(Bite start operation)
With reference to FIG. 6, the operation of starting the engagement between the pawl member TSU and the ratchet gear RCH (the engagement start operation of the lock mechanism LOK) will be described. The bite start operation corresponds to the start of the parking brake. The states [J1] to [J3] illustrate the relative positional relationship between the pawl member TSU and the ratchet gear RCH step by step. As in FIG. 5, the outer shape of the ratchet gear RCH is formed as an arc, but is expressed as a linear shape for convenience.

  The state [J1] indicates a state in which energization of the solenoid SOL is started and the tip portion (claw tip) Pts of the claw Tme of the claw member TSU is in contact with the tooth tip surface Htp of the ratchet gear RCH. In this state, the energization of the electric motor MTR is reduced, so that the ratchet gear RCH is moved in the Rvs direction (movement indicated by a white arrow). At this time, the pawl member TSU is pressed in the Dts direction by the solenoid SOL.

  Further, when the ratchet gear RCH is moved in the Rvs direction, as shown in the state [J2], the pawl member TSU is directed to the tooth bottom surface Hbm along the first inclined surface (the inclined surface having the smaller inclination) Hs1. Slide. Finally, as shown in the state [J3], the pawl member TSU is engaged with the ratchet gear RCH at the contact portion Stm. Thereafter, even when the energization to the solenoid SOL and the electric motor MTR is made zero, this state [J3] is maintained and functions as a parking brake.

  In a state where energization to the solenoid SOL is started, a portion where the pawl tip Pts comes into contact with the ratchet gear RCH changes. However, the moving distance of the ratchet gear RCH required for biting is one tooth of the ratchet gear RCH. Specifically, the maximum value of the distance required for biting is a value (Lpc + Lbt) obtained by adding the tooth thickness Lpc and the distance Lbt.

  A stopper mechanism for restricting the movement of the pawl member TSU in the biting direction Dts may be provided so that the relative position of the pawl member TSU relative to the ratchet gear RCH in the biting direction Dts does not exceed a predetermined limit position. For example, the stopper mechanism includes a step portion formed on the side surface of the pawl member TSU having a longitudinal direction and a part of the guide member GID engaged with the step portion (see FIG. 4). Since the claw member TSU and the ratchet gear RCH are engaged with each other by the stopper mechanism, a gap is formed between the tip (claw tip) Pts of the claw member TSU and the tooth bottom Hbm of the ratchet gear RCH. Deformation and wear of Pts can be suppressed.

(Bite release operation)
With reference to FIG. 7, the operation of releasing the engagement between the pawl member TSU and the ratchet gear RCH (the engagement release operation of the lock mechanism LOK) will be described. The bite release operation corresponds to the release of the parking brake. The states [J4] to [J5] illustrate the relative positional relationship between the pawl member TSU and the ratchet gear RCH step by step. The state [J4] corresponds to the state [J3] of FIG. Similar to FIG. 5, the outer shape of the ratchet gear RCH is expressed as a linear shape.

  The figure shows a situation in which the parking brake is instructed to be released in a state where energization of the electric motor MTR and the solenoid SOL is stopped. As shown in the state [J4], the electric motor MTR is driven to rotate forward while the energization to the solenoid SOL is stopped. Accordingly, the ratchet gear RCH is moved in the Fwd direction (movement indicated by a white arrow). Since the pawl member TSU always receives a force in the Dtr direction by the elastic member SPR, as shown in the state [J5], the pawl member TSU slides on the second inclined surface (the inclined surface having the larger inclination) Hs2 to ratchet gear. Move away from the RCH. When the pawl tip Pts is separated from the tooth tip Phs, the pawl member TSU is returned to the stopper (HSG of the solenoid SOL or caliper CRP) by the elastic member SPR, and the release operation of the parking brake is ended.

(Time series operation at the start of bite)
With reference to the time-series diagram of FIG. 8, the embodiment about the engagement start operation | movement of the locking mechanism LOK and its cancellation | release operation | movement is demonstrated. FIG. 8A shows an engagement start operation for transition from the release state to the engagement state. Further, FIG. 8B shows an engagement release operation in which the state is canceled from the engagement state. In the time-series diagram, when expressing the magnitude relationship of the values and the increase / decrease, considering the sign of the values, they become complicated. For this reason, in the following description, the magnitude / increase / decrease of the value is expressed based on the magnitude (absolute value) of the value.

  First, the engagement start operation of the lock mechanism LOK will be described with reference to FIG. The traveling vehicle is decelerated, stops at time t0, and the vehicle speed Vxa becomes zero. Thereafter, at time t1, the driver operates the parking switch MSW, and the operation signal Msw is switched from “0 (off state)” to “1 (on state)”. At the same time, the parking brake necessity signal FLpk is switched from “0 (necessity determination)” to “1 (necessity determination)” based on the transition of Msw. In the parking brake control block IPK, based on FLpk and preset characteristics, the parking brake target energization amount Ipk corresponds to forward rotation of the electric motor MTR with an increasing gradient (change amount with respect to time) ki1. It is increased in the energization direction (that is, the Fwd direction of the ratchet gear RCH). In the energization amount adjustment calculation block IMT, the parking brake target energization amount Ipk is selected as the target energization amount Imt and output. In response to this, the pressing force Fba and the rotation angle Mka are increased with time gradients kf1 and km1, respectively.

  At time t2 when the pressing force Fba reaches the predetermined value fb1, the target energization amount Imt is set to a constant value im1, and the pressing force Fba and the rotation angle Mka are maintained constant. Here, the predetermined value fb1 is a pressing force necessary for the parking brake, and is a predetermined value set in advance. Further, the predetermined value fb1 can be determined based on the slope of the road. For example, the value fb1 is set to a larger value when the road is inclined in the front-rear direction of the vehicle than when the road is horizontal. The inclination of the road can be acquired (detected) by a longitudinal acceleration acquisition means (for example, a longitudinal acceleration sensor).

  The drive signal FLs of the solenoid SOL is changed from “0 (non-energization instruction)” to “1 (energization) at a time point t3 when a predetermined time tx1 elapses from a time point t2 when the target energization amount Imt (accordingly, Fba, Mka) is made constant. Instruction) ”. In the solenoid control block SCT, energization to the solenoid SOL is started from time t3 based on FLs. By energizing the solenoid SOL, the pawl member TSU is moved toward the ratchet gear RCH (in the Dts direction). And the front-end | tip part (claw tip) Pts of the claw member TSU is contacted with the teeth of the ratchet gear RCH.

  At time t4 when a predetermined time tx2 has elapsed from time t3, the target energization amount Imt is decreased toward zero. Furthermore, an increase in the target energization amount Imt (decrease considering the sign of the energization amount) is started in the energization direction (Rvs direction of the ratchet gear RCH) corresponding to the reverse rotation of the electric motor MTR. In addition, the value (memory value) mk1 of the rotation angle Mka at the time point t4 is stored.

  At time t4, the target energization amount Imt is quickly made zero from the energization amount im1 corresponding to the normal rotation direction of the electric motor MTR. From the time point t4 to the time point t6, the target energization amount Imt is gradually (gradually) increased in the energization direction corresponding to the reverse drive of the electric motor MTR with an increasing gradient (change amount with respect to time) ki2. Specifically, the target energization amount Imt is increased from zero to a predetermined energization amount im2 (<0) corresponding to the reverse rotation of the electric motor MTR at a preset time gradient ki2 (<0). (Decreased from zero, considering the sign of the energization amount). Here, the magnitude (absolute value) of the time gradient ki2 is smaller than the magnitude of the time gradient ki1.

  From time t4 to time t6 (over a predetermined time tx3), when the change amount (displacement) Hm1 from the stored value mk1 (the value of the rotation angle Mka at the time t4) is less than the predetermined value hm1, the solenoid SOL, And energization to the electric motor MTR is stopped at time t6. That is, the engagement start operation of the parking brake is terminated at time t6. Here, the predetermined value hm1 corresponds to “the displacement Lpc corresponding to one pitch of the ratchet gear RCH (the interval between two adjacent teeth) and the tooth inclination angle β of the ratchet gear RCH for meshing with the pawl member TSU. The displacement Lbt is set to a value larger than the value obtained by adding the displacement Lbt (Lpc + Lbt) ”and smaller than the“ displacement corresponding to two pitches of the ratchet gear RCH (2 × Lpc) ”. That is, the threshold hm1 has a relationship of “(Lpc + Lbt) <hm1 <(2 × Lpc)”.

  Until the time t3, the suction force of the solenoid SOL does not act, and the tip portion Pts of the pawl member TSU is pressed against the housing HSG (or caliper CRP) of the solenoid SOL by the elastic member SPR. For this reason, the position Pts of the pawl member TSU is at the release position Pkj (see FIG. 4A). When energization to the solenoid SOL is started at time t3, the suction force of the SOL becomes larger than the elastic force of the SPR (that is, the PBR exerts on the TSU more than the releasing force in the Dtr direction that the SPR exerts on the TSU. The occlusal force in the Dts direction becomes larger) and the pawl tip Pts is moved in the Dts direction until it contacts the teeth of the ratchet gear RCH. The state from time t3 to t4 corresponds to the state of FIG. 6 [J1]. The transition from the time point t4 to the time point t5 corresponds to a transition that finally reaches the state [J3] through the state [J2] in FIG. At time t5, as shown in the state [J3], the pawl member TSU and the ratchet gear RCH are completely engaged with each other, and the pawl tip Pts is moved to the engagement position Pkm. Therefore, after the time t5, even if the energization to the solenoid SOL and the electric motor MTR is made zero, the pawl Pts is maintained at the biting position Pkm.

[Time series operation for bite release]
Next, the engagement release operation of the lock mechanism LOK will be described with reference to FIG. A case where the operation is canceled by the operation of the parking switch MSW by the driver in a situation where the parking brake is operating will be described.

  The stop state of the vehicle is maintained (that is, Vxa = 0). At time t7, the driver operates the parking switch MSW, and the operation signal Msw is switched from “1 (on state)” to “0 (off state)”. At the same time, the parking brake necessity signal FLpk is switched from “1 (necessity determination)” to “0 (unnecessity determination)” based on the transition of Msw. At IPK, based on FLpk and a preset characteristic, Ipk is increased in the energization direction corresponding to the normal rotation of electric motor MTR (that is, the Fwd direction of ratchet gear RCH). In IMT, Ipk is selected as the target energization amount Imt and output. At this time, the drive signal FLs of the solenoid SOL is maintained at “0”, and the solenoid SOL is not energized.

  Fba and Mka are maintained at the values fb2 and mk2 by the engagement of the pawl member TSU and the ratchet gear RCH. The value mk2 of the rotation angle Mka at the time point t7 is stored. Fba and Mka are not increased (constant) in the initial stage of starting increase of the target energization amount Imt (time t7 to t8). When the pressing force Fba is increased beyond the value fb2, the pawl member TSU starts to slide Hs2 of the ratchet gear RCH. Further, when the target energization amount Imt is increased in the energizing direction (ie, the Fwd direction) for forward driving of the electric motor MTR and the pressing force Fba is increased, the pawl member TSU is detached from the ratchet gear RCH, and the elastic member SPR The pawl point Pts is returned to the release position Pkj.

  The target energization amount Imt is returned to zero at time t9 when the amount of change (displacement) Hm1 from the state where the rotation angle Mka is constant (stored value mk2 at t7) exceeds the predetermined value hm2. Accordingly, Fba and Mka decrease toward zero. Here, the predetermined value hm2 is a value larger than the distance Lbt between the tooth tip surface Phs and the corner portion Psm.

<Appropriate area of contact part Stm>
The relationship between the contact portion Stm between the pawl member TSU and the ratchet gear RCH and the inclination angle (inclination angle of the second inclined surface Hs2) β of the ratchet gear RCH will be described with reference to the schematic diagram of FIG.

  As shown in FIG. 9A, a rake angle α is provided at a portion (contact portion Stm) that meshes with the ratchet gear RCH in the pawl member TSU. Here, the contact portion Stm is a flat surface, and is a portion in surface contact from the tooth tip portion Phs (white circle) of the ratchet gear RCH to the tip portion Pts (white square) of the claw member TSU. Further, the rake angle α is an angle formed by the contact portion (biting surface) Stm and the biting direction Dts.

  The arrangement [S1] shows a case where the tooth tip Phs (indicated by the point Qa) of the contact portion Stm exists on the plane Ms1 that passes through the rotation axis Jrc of the ratchet gear RCH and is parallel to the Dts direction. Here, the plane Ms1 is referred to as a “first plane”.

  Next, it is assumed that the tooth tip portion Phs of the ratchet gear RCH is rotated by an angle θ in the Rvs direction around the rotation axis Jrc of the ratchet gear RCH. This state (state where the tooth tip Phs is at the position of the point Qb) is indicated by the arrangement [S2]. In the arrangement [S2], a plane Ms2 that passes through the tooth tip portion Phs of the ratchet gear RCH and is parallel to the Dts direction is referred to as a “second plane”. A distance Los between the first plane Ms1 and the second plane Ms2 is referred to as an “offset distance”. If the radius of the ratchet gear RCH (distance from the rotation axis Jrc to the tooth tip surface Htp) is Rrc, the offset distance Los is obtained by multiplying the radius Rrc by the sine (sin θ) of the angle θ (Los = Rrc · sin θ). ). Note that the sum of the inclination angle β and the angle θ corresponds to the rake angle α (α = β + θ).

  Further, consider a case where the tooth tip Phs is rotated about the rotation axis Jrc in the Rvs direction so that the rotation angle θ coincides with the rake angle α. This state (state where the tooth tip Phs is at the position of the point Qc) is represented by the arrangement [S3]. In this state, the inclination angle β of the ratchet gear RCH is zero, and the offset distance Los is “Rrc · sin α”. Therefore, when the pawl member TSU is configured to mesh with the ratchet gear RCH in the third plane Ms3 separated from the first plane Ms1 by the “distance Rrc · sin α”, the inclination angle β of the ratchet gear RCH is Can be set to zero.

  Since the inclination angle β affects the dimension of the tooth thickness (tooth thickness) Lrc, it affects the strength of the ratchet gear RCH in the rotational direction. For example, as shown by the arrangement [S1], when the inclination angle β is relatively large, the tooth thickness Lrc1 is relatively thin. On the other hand, as shown by the arrangement [S3], when the inclination angle β is relatively small, the tooth thickness Lrc3 (> Lrc1) is relatively large, which is advantageous in the strength of the ratchet gear RCH. Therefore, if the offset distance Los is small, the tooth thickness Lrc is small, but if Los is set to be large, Lrc can be set to be large.

  FIG. 9B summarizes the relationship between the rake angle α, the offset distance Los (specifically, the value Los / Rrc obtained by dividing the offset distance by the ratchet gear radius), and the inclination angle β. For example, considering the case of α = 30 degrees, when Los = 0 (that is, state [S1]), β = α = 30 degrees. Then, as Los / Rrc (= sin θ) increases, the inclination angle β decreases. When Los / Rrc = 0.5, β = 0 degrees.

  When the offset distance Los is increased, the inclination angle β can be decreased and the tooth thickness Lrc can be set large. For this reason, the strength of the ratchet gear RCH is increased. However, when the tooth thickness Lrc of the RCH is increased, the thickness Lts of the pawl member TSU becomes smaller (thin), and the strength of the pawl member TSU is impaired. In order to satisfy this trade-off relationship, the offset distance Los is set within a range of 10 to 70% of Rrc · sin α. That is, the value of Los / Rrc is set in a region sandwiched between the 10% line L10 and the 70% line L70 shown in FIG. 9B. Specifically, L10 represents Los = 0.1 · Rrc · sin α, and L70 represents Los = 0.7 · Rrc · sin α. By setting the offset distance Los within this range (that is, 0.1 · Rrc · sin α ≦ Los ≦ 0.7 · Rrc · sin α), the strength of the pawl member TSU and the ratchet gear RCH is compatible. obtain. For example, if α = 30 degrees, the value of Los / Rrc ranges from 0.05 (ie, 10% of the 30 degree sine) to 0.35 (ie, 70% of the 30 degree sine). (Indicated by a thick line with double arrows).

<Width of pawl member TSU>
Due to wear of the friction member MSB, the meshing position in the ratchet gear RCH changes when the parking brake is operated. That is, in the pawl member TSU, the contact portion (biting surface) Stm is always the same part, whereas in the ratchet gear RCH, as the friction member MSB is worn, biting is performed with different teeth. (The contact portion Stm of the ratchet gear RCH changes sequentially). This phenomenon needs to be considered in the fatigue strength of the pawl member TSU and the ratchet gear RCH.

  FIG. 10 shows the relationship between the pawl member TSU and the ratchet gear RCH when viewed in the A direction (indicated by a white arrow) in FIG. The width (claw width) Wts of the pawl member TSU is set wider (larger) than the tooth width Wrc of the ratchet gear RCH. In the engagement of the lock mechanism LOK, the pawl member TSU is always engaged at the same location (that is, the contact portion Stm). However, in the ratchet gear RCH, the biting position changes as the friction member MSB wears. For this reason, the fatigue durability of the pawl member TSU can be improved by making the pawl width Wts larger than the tooth width Wrc.

  Next, a sliding portion between the pawl member TSU and the guide member GID will be described. A plane Mts including the center axis Jts of the pawl member TSU and parallel to the rotation axis Jrc of the ratchet gear RCH is referred to as a “center plane”. The surface of the claw member TSU where the protrusion (claw tip Pts) of the claw member TSU is present with respect to the center surface Mts of the claw member TSU is referred to as “the front surface Mft (of the claw member TSU)”. The surface of the claw member TSU opposite to the front surface Mft with respect to the center surface Mts is referred to as “the back surface Mbk (of the claw member TSU)”. Accordingly, in the pawl member TSU, the “front surface Mft” can be said to be a surface closer to the pawl Tme (especially the occlusal surface Stm), and the “rear surface Mbk” can be said to be a surface farther from the Tme (particularly Stm).

  When the claw member TSU is divided perpendicularly to the Dts direction, the cross section of the claw member TSU is represented by a quadrangle Mck (P1-P2-P3-P4). The cross section Mck is orthogonal to the center plane Mts, but the intersection line is indicated by line segments P5-P6. The front surface Mft of the TSU is a plane including the line segment P1-P2 and parallel to the central axis Jts. Further, the back surface Mbk of the TSU is a plane including the line segment P3-P4 and parallel to the central axis Jts. Therefore, it is parallel to the front surface Mft, the center surface Mts, the back surface Mbk, and the first linear direction.

  The guide member GID slides with Mft and Mbk to guide the pawl member TSU. Here, in the shape (guide surface) of the guide member GID, the dimension of the part sliding with Mbk (the length on the back Mbk side) Lbk is the dimension of the part sliding with Mft (the length on the front Mft side) Lft. On the other hand, it is set larger in the Dts direction (Lbk> Lft). That is, the length Lbk in the first linear direction of the guide surface on the side farthest from the pawl Tme of the pawl member TSU (back Mbk side) is equal to the length in the first linear direction of the guide surface on the side near Tme (front side Mft side) of TSU. Longer than Lft. At the contact portion Stm, the pawl member TSU receives a force from the ratchet gear RCH toward the back from the front of the drawing (that is, the direction perpendicular to the center plane Mts and extending from the line segment P1-P2 to the line segment P3-P4). This force gives a bending moment to the pawl member TSU. However, since the guide surface on the back Mkb side of the GID is set relatively long in the Dts direction (first linear direction), bending deformation of the pawl member TSU does not occur. It is suppressed. As a result, smooth movement of the pawl member TSU can be ensured.

  Further, the pawl member TSU is arranged with an offset distance Los with respect to the ratchet gear RCH. In this case, in the positional interference with the ratchet gear RCH, although there is a dimensional allowance on the Mbk side, the dimensional allowance is small on the Mft side. For this reason, the dimension Lbk in the first linear direction on the back surface Mbk side is set to be longer than the dimension Lft in the first linear direction on the front surface Mft side, so that the pawl member TSU and the ratchet gear RCH are arranged efficiently. Thus, the entire apparatus can be miniaturized.

  Different materials are employed for the material of the pawl member TSU and the ratchet gear RCH, and the pawl member TSU may employ a material having higher strength than the ratchet gear RCH. For example, a steel material may be employed for the pawl member TSU, and an aluminum material may be employed for the ratchet gear RCH. Further, a combination of an aluminum material for the pawl member TSU and a resin material for the ratchet gear RCH may be employed. This is due to the fatigue strength relationship described above.

<Parking brake mechanism LOK considering vibration due to road surface unevenness>
With reference to FIG. 11 to FIG. 14, an appropriate arrangement of the pawl member TSU with respect to vibration caused by road surface unevenness input to the wheel WHL will be described.

  When the vehicle is traveling (that is, when the parking brake function is not required), the pawl member TSU is moved by the elastic force (spring force) of the elastic member (return spring) SPR to the housing HSG (or the solenoid SOL). , Caliper CRP itself). When the vehicle travels on a traveling road (rough road, level difference, etc.) having unevenness on the surface of the road, vibrations due to road surface unevenness are input to the wheels WHL. Since the pawl member TSU has a mass (self-weight), the pawl member TSU may be moved by this road surface vibration (generated acceleration). That is, a situation may occur in which the pawl member TSU pressed against the housing HSG side by the elastic member SPR is separated from the housing HSG (or caliper CRP). In this case, since unnecessary operation of the parking brake is a concern, the spring constant of the elastic member (return spring) SPR (so that the state in which the pawl member TSU is pressed is reliably maintained against road surface vibration ( Alternatively, the initial load is set to a large value. However, when the elastic member SPR having a large spring constant (or initial load) is employed, the suction force of the solenoid SOL needs to be increased to counter this when the parking brake is operated. As a result, the entire braking device is enlarged. Therefore, in order to reduce the size of the braking device, it is important to suppress the acceleration input in the moving direction of the pawl member TSU.

<Distribution of wheel acceleration Gw when vehicle travels on road with large unevenness>
FIG. 11 shows experimental results obtained by actually measuring the acceleration (wheel acceleration) Gw acting on the wheel WHL when the vehicle travels on a road having a large road surface unevenness. As shown in the upper diagram of FIG. 11A, the wheel WHL advances while rotating and collides with a convex portion of the road surface GRN. At this time, the wheel acceleration Gw is generated by receiving a force from the road surface. An accelerometer GS capable of measuring accelerations Gh (horizontal direction) and Gv (vertical direction) in two axial directions orthogonal to each other was mounted on the wheel WHL, and measurement was actually performed. Specifically, the accelerometer GS was mounted on the suspension arm as close as possible to the rotating member KTB, and the components Gh and Gv of the wheel acceleration Gw were measured.

  The lower diagram of FIG. 11A is an example of a measurement result obtained by actually traveling on a road where random road surface unevenness continues. Here, the acceleration Gh represents a horizontal direction (vehicle longitudinal direction) component, and the acceleration Gv represents a vertical direction (vehicle vertical direction) component. Here, a road on which random road surface irregularities are continuous is referred to as a “bad road”. A road having a step on the road surface is referred to as a “step road”.

  FIG. 11B shows the experimental results of examining the magnitude of the acceleration Gw acting on the wheel WHL and the distribution of the direction when the vehicle travels on the rough road and the step road at various speeds. It is. The magnitude and direction of the wheel acceleration Gw (vector) are calculated based on the measured accelerations Gh and Gv. The horizontal axis (the direction of the wheel acceleration Gw) is expressed by an angle φ with respect to the vertical direction (the vertical direction of the vehicle), and the vertical axis (the size of the wheel acceleration Gw) is divided by the maximum value Gwm of the generated Gw. Value (acceleration index) is adopted. Each point of a circle mark and a square mark is a measurement result at each measurement time point.

  When the wheel WHL of the traveling vehicle collides with the unevenness of the road surface, the wheel WHL receives a force from the road surface. This force acts not only in the vertical direction of the vehicle but also in the longitudinal direction. Then, acceleration Gw is generated in the wheel WHL by the force applied to the wheel WHL. The size and direction of the wheel acceleration Gw depends on the speed of the vehicle, the size (height) of the road surface unevenness, the characteristics of the suspension, and the like.

  As can be seen from the experimental results, in the distribution Bnp of the wheel acceleration Gw, the relatively large wheel acceleration Gw increases as the angle φ increases, and reaches a maximum (peak) at a certain angle. Specifically, the maximum value Gwm of the wheel acceleration Gw occurs at φ≈12.5 degrees (direction Dgm of about 12.5 degrees with respect to the vertical direction Den). Further, as the angle φ increases, the wheel acceleration Gw gradually decreases. Here, the angle (direction) at which the acceleration maximum value Gwm occurs is referred to as a peak direction Dgm. A relatively large wheel acceleration Gw occurs when the road surface is uneven and the vehicle speed is somewhat high. In this case, the force that the wheel WHL receives from the road surface acts not only in the vertical direction of the vehicle but also in the front-rear direction. For example, 90% or more of the maximum value Gwm of the wheel acceleration Gw is distributed in a region where the direction φ is 5 to 20 degrees (near the peak direction Dgm).

<Appropriate arrangement of pawl member TSU against vibration from road surface>
An appropriate arrangement of the central axis Jts of the pawl member TSU will be described with reference to FIG. 12 and FIG. 13 in which the wheel WHL is viewed from the side.

  From the experimental results of FIG. 11 (running results of bad roads, step roads, etc. by the test vehicle), the wheel acceleration Gw that is relatively large (for example, 90% or more of the maximum value of the wheel acceleration Gw) is: It was found that the distribution is in a direction (around the peak direction Dgm) inclined by about 5 to 20 degrees with respect to the vertical direction (vertical direction) Den of the vehicle. In order to reduce the acceleration component input in the moving direction of the pawl member TSU, the central axis Jts of the pawl member TSU is arranged perpendicular to this region (φ = 5 to 20 degrees). Specifically, the claw member TSU is tilted by 5 to 20 degrees with respect to the vehicle front-rear direction Dsh in the horizontal plane SMkt including the rotation axis Jkt of the rotation member KTB (that is, the rotation axis Jwh of the wheel WHL). A central axis Jts (that is, the biting direction Dts) is provided. In other words, the biting direction Dts is the rotation direction of the rotating member KTB when the vehicle moves forward on the horizontal plane SMkt including the rotating axis Jkt of the rotating member KTB around the rotating axis Jkt of the rotating member KTB (white arrow). Is set in a direction opposite to the direction (indicated by) and parallel to the surface (inclined surface) KMts inclined by 5 to 20 degrees and perpendicular to the rotational axis Jkt of the rotating member KTB. Here, the “direction opposite to the rotation direction of the rotating member KTB (ie, the wheel WHL) when the vehicle moves forward” is referred to as “wheel reversing direction”. Therefore, the “wheel reversing direction” can also be said to be “the rotating direction of the rotating member KTB when the vehicle moves backward”.

  The peak direction (direction in which the maximum acceleration value Gwm occurs) Dgm depends on the traveling direction (forward direction) of the vehicle. Specifically, the peak direction Dgm is inclined with respect to the vertical direction (vertical direction of the vehicle) Den around the rotation axis Jwh of the wheel WHL in the direction opposite to the direction in which the wheel WHL rotates. For this reason, it is preferable that the central axis Jts of the pawl member TSU has an inclination of 5 to 20 degrees with respect to the forward direction (horizontal direction) Dsh of the vehicle, but the inclination of the central axis Jts of the pawl member TSU with respect to the horizontal plane. Is different depending on whether the braking means BRK is located in front of or behind the vehicle. For this reason, two cases will be described separately.

  First, with reference to FIG. 12, the case where the braking means BRK is located on the front side with respect to the vehicle traveling direction (when the caliper CRPa is mounted and referred to as “front arrangement”) will be described. Specifically, the caliper CRPa is on the side on which the vehicle moves forward with respect to a plane (vertical plane) perpendicular to the road surface including the rotation axis Jwh of the wheel WHL (coaxial with the rotation axis Jkt of the rotation member KTB) (that is, (Front). The central axes Jtsa and Jtsc of the pawl member TSU are set to the horizontal plane SMkt including the rotational axis Jkt of the rotating member KTB in the direction opposite to the rotational direction of the rotating member KTB when the vehicle moves forward (that is, the wheel reversal direction) by an angle ψ. It is arranged so as to be parallel to the inclined surface (inclined surface) KMts and orthogonal to the rotation axis Jkt of the rotating member KTB. The angle ψ is set within a range of 5 degrees to 20 degrees.

  The relatively large wheel acceleration Gw is distributed in a region inclined by about 5 to 20 degrees backward with respect to the vertical direction Den (near the peak direction Dgm and referred to as a peak region). To do. Accordingly, on the front side of the wheel WHL, the center axes Jtsa and Jtsc of the pawl member TSU are inclined in the direction of reversing the wheel from the horizontal direction Dsh of the vehicle forward by about 5 to 20 degrees (that is, in the peak region). (Vertical direction). For this reason, the Jts direction component (ψ direction component) Gts of the wheel acceleration Gw can be kept relatively small. As a result, the magnitude of the acceleration Gts applied in the moving direction of the pawl member TSU is suppressed, and the solenoid SOL can be downsized.

  The braking means BRK is composed of at least two shafts (see FIG. 2). Specifically, the rotation axis Jmt of the electric motor MTR (coaxial with the rotation axis Jin of the input member INP and the rotation axis Jrc of the ratchet gear RCH) and the central axis Jps of the pressing member PSN (rotation axis Jsf of the shaft member SFT) And the same axis) are configured separately and in parallel. The solenoid SOL is opposite to the intersection points Ktsa and Ktsc between the horizontal plane SMps including the central axis Jps of the pressing member PSN and the central axis Jts of the pawl member TSU with respect to the vertical plane EMps including the central axis Jps of the pressing member PSN. Placed on the side. For example, with respect to the vertical plane EMps, the intersection point Ktsa exists on the right side of the page, but the solenoid SOL (shown by a solid line) is arranged on the left side of the page, which is opposite to the intersection point Ktsa.

  Since it is suitable to press the center of the friction member MSB, the arrangement of the pressing member PSN is limited. Since the center axis Jts of the pawl member TSU is tilted with respect to the horizontal plane SMkt to reduce the vibration input, a spatial restriction may occur in the arrangement of the parking brake mechanism LOK. For example, when focusing on the central axis Jtsa, on the right side of the vertical plane EMps, Jtsa approaches SMkt, so that the arrangement space for the members becomes strict. On the other hand, on the left side of the vertical plane EMps, Jtsa moves away from SMkt, which is advantageous as a member arrangement space. When the solenoid SOL and the pawl member TSU are arranged apart from each other, a relatively long push bar PBR (see FIG. 4) is employed. In this case, it is necessary to consider reduction in transmission efficiency from the solenoid SOL to the pawl member TSU, bending of the push bar PBR, and the like. Since the solenoid SOL is arranged on the opposite side of the intersections Ktsa and Ktsc (intersection of the axes Jtsa and Jtsc and SMkt) with respect to the vertical plane EMps including Jps, the solenoid SOL and the pawl member TSU are close to each other. Can be placed. As a result, a relatively short push bar PBR is employed, and the parking brake mechanism LOK can be efficiently arranged in the caliper.

  The braking means BRK needs to be housed inside the wheel WHL. Since there are a hub bearing unit, a knuckle, a suspension member, and the like around the rotation shaft Jkt of the wheel WHL, the braking means BRK is particularly in the radial direction of the wheel WHL. It is necessary to reduce the dimension (on the side closer to the rotation axis Jwh of WHL). Solenoid SOL is on the opposite side (that is, outside of cylindrical surface Mps) to rotational axis Jkt of rotating member KTB with respect to curved surface (cylindrical surface) Mps that includes central axis Jps of pressing member PSN and is coaxial with rotating member KTB. Be placed. Although Jkt is on the right side of the drawing with respect to the cylindrical surface Mps coaxial with Jkt, including Jps, the solenoid SOL (corresponding to the central axis Jtsa) indicated by the solid line is arranged on the left side of the drawing on the opposite side of Jkt. Since the solenoid SOL is not arranged around the rotation axis Jkt of the wheel WHL, the braking means BRK can be downsized in the radial direction of the wheel WHL. In addition, in the arrangement of the solenoid SOL (corresponding to the central axis Jtsc) indicated by the broken line, the BRK cannot be shortened in the radial direction because it is on the same side as Jkt (that is, inside Mps) with respect to Mps.

  Next, with reference to FIG. 13, the case where the braking means BRK is located on the rear side with respect to the vehicle traveling direction (when the caliper CRPb is mounted and referred to as “rear arrangement”) will be described. . Specifically, the caliper CRPb is opposite to the side on which the vehicle advances with respect to a plane (vertical plane) perpendicular to the road surface including the rotation axis Jwh of the wheel WHL (coaxial with the rotation axis Jkt of the rotation member KTB). It is arranged on the side (ie, rear). As in the case of the forward arrangement, the center axes Jtsb and Jtsd of the pawl member TSU are arranged in a wheel reversal direction (a direction opposite to the rotation direction of the wheel WHL when the vehicle moves forward) including the rotation axis Jkt of the rotation member KTB. Are arranged parallel to the surface (inclined surface) KMts inclined by an angle ψ (= 5 to 20 degrees) and perpendicular to the rotation axis Jkt of the rotating member KTB. As described above, since the central axes Jtsb and Jtsd of the pawl member TSU are tilted so as to be perpendicular to the peak region, the Jts direction component Gts of the wheel acceleration Gw can be kept relatively small. As a result, as in the case of the forward arrangement, the magnitude of the acceleration Gts applied in the moving direction of the pawl member TSU is suppressed, and the solenoid SOL can be downsized.

  As in the case of the forward arrangement, in the braking means BRK configured by at least two axes, the solenoid SOL includes the central axis Jps of the pressing member PSN with respect to the vertical plane EMps including the central axis Jps of the pressing member PSN. It is arranged on the opposite side to the intersections Ktsb and Ktsd between the horizontal plane SMps and the central axis Jts of the pawl member TSU.

  In order to press the center of the friction member MSB, the arrangement of the pressing member PSN is preferentially determined. Furthermore, since the center axis Jts of the pawl member TSU is inclined with respect to the horizontal plane SMkt, there is a spatial limitation on the arrangement of the parking brake mechanism LOK. The solenoid SOL is arranged on the opposite side (space-advantageous side) to the intersections Ktsb and Ktsd (the intersections of the axes Jtsb and Jtsd and SMkt) with respect to the vertical plane EMps including Jps. As in the case of the front arrangement, the solenoid SOL and the pawl member TSU are arranged close to each other, and the push bar PBR can be relatively shortened. For this reason, the parking brake mechanism LOK can be efficiently disposed in the caliper.

  Further, as in the case of the front arrangement, the solenoid SOL (see the one corresponding to the central axis Jtsb) is included in the curved surface (cylindrical surface) Mps including the central axis Jps of the pressing member PSN and coaxial with the rotating member KTB. The rotation member KTB is disposed on the opposite side (outside of Mps) from the rotation axis Jkt. Since the solenoid SOL is disposed relatively away from the rotation axis Jkt of the wheel WHL, the braking means BRK can be downsized in the radial direction of the wheel WHL.

<Effect when center axis Jts of pawl member TSU is properly arranged>
With reference to FIG. 14, the effect of reducing the wheel acceleration (Jts direction component of acceleration) Gts acting in the moving direction of the pawl member TSU when the central axis Jts of the pawl member TSU is set to an appropriate range will be described. 14 assumes an acceleration distribution in which the wheel acceleration Gw is indicated by a one-dot chain line Bnp in FIG. 11B, and the direction of the central axis of the pawl member TSU (the movement direction of the pawl member TSU and the biting direction Dts). Is plotted as an acceleration component Gts. Specifically, FIG. 14 shows the direction φ of the wheel acceleration Gw and the wheel acceleration when the angle ψ formed by the central axis Jts of the pawl member TSU and the vehicle traveling direction (horizontal direction) Dsh on the horizontal plane is changed. The relationship between Gw and the Jts direction component Gts is shown.

  The angle ψ (the angle formed by Dsh and Jts) is set in a range from 5 degrees to 20 degrees (more specifically, the central axis Jts of the pawl member TSU is the rotational axis Jkt of the rotating member KTB). The horizontal plane SMkt that is included is parallel to the plane KMts that is inclined by 5 to 20 degrees in the wheel reversal direction and is disposed at a right angle to the rotation axis Jkt), whereby the acceleration component Gts is relatively small. It can be suppressed within the range. For example, compared to the case where the angle ψ is set to zero (that is, Jts is arranged in the horizontal front-rear direction), by setting ψ = 5 to 20 degrees (the appropriate range shown by hatching), The acceleration component Gts can be reduced by 25%. As a result, the spring constant of the elastic member SPR that presses the pawl member TSU is set small, and the output of the solenoid SOL can be reduced. Furthermore, the overall size of the brake actuator BRK can be reduced.

  Since the approximate value of the rigidity (spring constant) of the braking means BRK is known, the pressing force Fba and the rotation angle Mka of the MTR can be considered as equivalent physical quantities. That is, a value obtained by multiplying the rigidity (predetermined value) of the braking means BRK by the rotation angle Mka corresponds to the pressing force Fba. Therefore, Fba and Mka express a state in which the friction member MSB presses the rotating member KTB, and thus are collectively referred to as a “pressing state quantity”. In other words, at least one of Fba and Mka is the pressed state quantity. Further, FBA and MKA that acquire Fba and Mka are referred to as “pressed state amount acquisition means”.

  In the above embodiment, a pressing state quantity may be employed instead of at least one of the pressing force (actual value) Fba and the rotation angle (actual value) Mka. Moreover, it can replace with the variation | change_quantity (displacement) Hm1 and Hm2, and the variation | change_quantity of a press state quantity can be employ | adopted. Specifically, the rotation angle Mka of the electric motor MTR can be employed instead of the pressing force Fba. In the pressing force Fba, a change amount Hf1 from the value fb1 and a change amount Hf2 from the value fb2 can be employed. In this case, the predetermined values fb1, fb2, mk1, mk2, hf1, hf2, hm1, and hm2 correspond to predetermined values of the pressed state amount.

  The braking means BRK is composed of two or more different shafts (multi-axis configuration), the rotation angle acquisition means MKA is provided on the shaft on which the electric motor MTR is disposed, and the pressing force is acquired on the shaft on which the pressing member PSN is disposed. When the means FBA is provided, the pressing force Fba is adopted as the pressing state amount for adjusting the increase in the target energization amount Imt, and the electric motor MTR is used as the pressing state amount for determining the end of energization of the solenoid SOL. It is preferable that the rotation angle Mka is adopted. Although the rigidity of the BRK slightly changes with the wear of the MSB, since the pressing force (value fb1) necessary for the parking brake is determined based on Fba, a reliable braking torque can be applied. In addition, since the reduction gear GSK is disposed between the rotation axis Jmt of the MTR and the central axis Jps of the PSN, the resolution (resolution) in the pressing state amount is higher than that of the central axis Jps of the PSN. Jmt is higher. For this reason, since the meshing state of TSU and RCH is confirmed based on the displacement Hm1 of the rotation angle Mka, the determination can be surely executed.

  MTR ... Electric motor, MSB ... Friction member, PSN ... Pressing member, RCH ... Ratchet gear, TSU ... Claw member, SOL ... Solenoid, LOK ... Parking brake mechanism, Dts ... Biting direction

Claims (1)

A pressing member that presses the friction member against a rotating member that rotates integrally with the vehicle wheel;
An electric motor that generates power to drive the pressing member;
A ratchet gear fixed to a power transmission member that is rotationally driven by the electric motor and drives the pressing member;
A pawl member arranged to be movable in a first linear direction with respect to the ratchet gear, and capable of meshing with the ratchet gear; and
A parking brake mechanism including a solenoid that pushes the pawl member in energization direction when the pawl member in the first linear direction approaches the ratchet gear when energized;
An electric braking device for a vehicle comprising:
The meshing surface of the pawl member with the ratchet gear is inclined with respect to the first linear direction in a direction in which the ratchet gear rotates when the pressing force of the pressing member decreases,
In a state where the pawl member and the ratchet gear are engaged with each other, the engagement surface of the ratchet gear with the pawl member is the ratchet when the pressing force of the pressing member decreases with respect to the first linear direction. The gears tilt in the direction of rotation ,
The first plane including the rotation axis of the ratchet gear and parallel to the first linear direction, and the claw member and the ratchet gear in a state where the claw member and the ratchet gear are engaged with each other. An offset distance, which is a distance from a second plane including the tooth tip portion of the ratchet gear and parallel to the first linear direction,
An electric braking device for a vehicle, which is set within a range of 10 to 70% of a value obtained by multiplying a radius of the ratchet gear by a sine of an angle at which the meshing surface of the pawl member is inclined with respect to the first linear direction. .

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