JP6572685B2 - Electric braking device for vehicle - Google Patents

Description

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

  Patent Document 1 states that “in a brake device that is electrically driven by a motor, a drive control device and an actuator, a vehicle motion control device and a thrust sensor, and three bending cables that connect the vehicle motion control device and a wheel speed sensor. Because it is wired and wasteful in terms of cost, drive control with a communication circuit, a control circuit, and a drive unit that drives the motor is aimed at reducing the cost of the bent cable and providing an inexpensive brake device Install the device on the wheel side, supply power to the drive control device from the vehicle body side by two power lines, receive the braking force signal from the vehicle motion control device by multiplex communication, drive the motor and generate the braking force Is done. " That is, in the electric braking device described in Patent Document 1, a configuration in which a vehicle is provided with a vehicle body side electronic control unit and a wheel side electronic control unit, and these two electronic control units are connected by communication is shown. Yes.

  In Patent Document 2, for the purpose of “demonstrating the function as a parking brake without impairing the function as an electric brake”, a “spindle wheel is provided on the circumferential surface of the rotor of the motor, and the rocker disposed around the rotor is arranged. The moving arm is provided with an engaging pawl biased in one direction by a torsion spring, and the swinging arm is always biased toward the handwheel by a tension spring.When the parking brake is activated, it is controlled by the rotation of the rotor in the braking direction. It is described that the return of the rotor is regulated by the engagement between the engagement pawl and the pawl wheel by interrupting the energization to the motor at the same time as generating the power. That is, Patent Document 2 discloses an electric braking device having two functions of a normal brake (also referred to as a service brake) and a parking brake.

  By the way, a configuration of an electric braking device that includes an electronic control unit ECB on the vehicle body side and an electronic control unit ECW on the wheel side, and further includes a normal brake function and a parking brake function is considered. . In this configuration, the load of communication (for example, serial communication) connecting the ECB and the ECW is increased as compared with the one having only the normal brake function. Specifically, since an instruction signal to an actuator (for example, a solenoid) that exerts a force that opposes the tension spring and a signal for monitoring the operating state of the actuator are required, the amount of communication increases and the communication cycle increases. Can be long. On the other hand, since the electric braking device requires high-responsive control of the electric motor MTR, it is desired to reduce the communication amount (bus load) between the two electronic control units ECU (ECB, ECW). ing.

JP 2003-137081 A JP 2003-042199 A

  An object of the present invention is to provide a vehicle body side electronic control unit ECB, a wheel side electronic control unit ECW, and a communication means TSN for transmitting signals Ssv and Spk calculated by these, and a normal brake function and parking. It is an object of the present invention to provide an electric braking device for a vehicle that exhibits a braking function by an electric motor MTR, in which the load of the communication means TSN is reduced, and control of the electric motor MTR with high accuracy and high response can be achieved.

  The electric braking device for a vehicle according to the present invention applies a braking torque to the wheels (WHL) of the vehicle by an electric motor (MTR) in accordance with a braking operation by a driver of the vehicle, and decelerates and stops the vehicle. Even when there is no normal braking function and no braking operation by the driver of the vehicle, the electric motor (MTR) and the restraining means (LOK) that restricts the movement of the electric motor (MTR) A parking brake function to maintain. The electric braking device for a vehicle according to the present invention is provided on the vehicle body side of the vehicle, and a normal data signal (Ssv) for realizing the normal brake function and a parking for realizing the parking brake function. A vehicle body side electronic control unit (ECB) that forms a data signal (Spk), and provided on the wheel side of the vehicle, the electric data based on the normal data signal (Ssv) and the parking data signal (Spk) Between the motor (MTR) and the wheel side electronic control unit (ECW) for controlling the restraining means (LOK), the vehicle body side electronic control unit (ECB) and the wheel side electronic control unit (ECW). A normal data signal (Ssv, etc.) and a communication means (TSN) for transmitting the parking data signal (Spk).

  The electric braking device for a vehicle according to the present invention is characterized in that the communication means (TSN) transmits the normal data signal (Ssv) every calculation cycle of the normal data signal (Ssv), and the parking data signal (Spk). ) When the result of the previous calculation cycle of the parking data signal (Spk) (Spk (n-1)) and the result of the current calculation cycle of the parking data signal (Spk) (Spk (n)) are different. It is configured to transmit only. Specifically, the normal data signal (Ssv) related to the normal brake function is not only generated when the driver performs the braking operation but also when the driver does not perform the braking operation by the communication means (TSN). It is always transmitted (every calculation cycle) (this communication method is called constant communication). On the other hand, the communication data (Spk) related to the parking brake is not always transmitted by the communication means (TSN), and the communication cycle in which the parking data signal Spk has changed (the previous calculation result Spk (n−1) and the current calculation). The result Spk (n) is transmitted only during the present calculation cycle in which it is determined that the result does not match. In other words, the parking data signal Spk is transmitted only when the parking brake function transition (release → actuation or actuation → release) is instructed, and the signal (Spk) is transmitted only when necessary.

  According to the above configuration, when the electric braking device functions as a normal brake, an unnecessary parking data signal Spk is not transmitted between the vehicle body side electronic control unit ECB and the wheel side electronic control unit ECW. The communication cycle for the parking data signal can be shortened. As a result, the signal processing and calculation processing capacities related to the normal brake function are improved, and control of the electric motor MTR with high accuracy and high response can be achieved.

  In the electric braking device for a vehicle according to the present invention, the communication means (TSN) first parks the parking data signal (Spk) from the vehicle body side electronic control unit (ECB) to the wheel side electronic control unit (ECW). The first parking data signal (Spk1) is transmitted as a second parking data signal (Spk2) from the wheel side electronic control unit (ECW) to the vehicle body side electronic control unit (ECB). The second parking data signal (Spk2) is transmitted from the vehicle body side electronic control unit (ECB) to the wheel side electronic control unit (ECW) as a third parking data signal (Spk3), and the first parking data signal ( When the coincidence between the Spk1) and the third parking data signal (Spk3) is determined (Spk1 = Spk3), the parking brake machine (Operation or release) transition is permitted, and when the discrepancy between the first parking data signal (Spk1) and the third parking data signal (Spk3) is determined (Spk1 ≠ Spk3), the parking brake function (operation Or release) transition is prohibited.

  In the electric braking device for a vehicle according to the present invention, when the electric braking device functions as a parking brake, the parking data signal (Spk) is not always transmitted, but only when the signal (Spk) is required. Is transmitted. That is, irregular communication (also referred to as event communication) is adopted as a communication method for the parking data signal (Spk). In constant communication (also referred to as regular communication), it is possible to check the certainty by comparing data signals in a plurality of communication cycles. However, when irregular communication is employed for data signal transmission, the reliability of the data signal is lower than when regular communication is employed.

  According to the above configuration, data signals are transmitted (transferred) a plurality of times between the vehicle body side electronic control unit ECB and the wheel side electronic control unit ECW, and the accuracy of the data signal Spk is inspected. And when the certainty of parking data signal Spk is certain (Spk1 = Spk3), the transition of a parking brake function is permitted. On the other hand, when the probability of the parking data signal Spk is uncertain (Spk1 ≠ Spk3), the transition of the parking brake function is prohibited. As a result, a reliable parking brake function can be achieved with a configuration in which the amount of communication is reduced. Here, “transition of the parking brake function” is any one of a change from the operation state of the parking brake to the release state and a change from the release state of the parking brake to the operation state.

  In the electric braking device for a vehicle according to the present invention, each of the left and right wheels (WHLr, WHLl) of the vehicle includes the wheel side electronic control unit (ECWr, ECWl) and the communication means (TSNr, TSNl). . Of the left and right wheels (WHLr, WHLl), the communication means (TSNl) of the one wheel (WHLl) includes the first parking data signal (Spk1l) and the one wheel of the one wheel (WHLl). Even when it is determined that (WHLl) does not match the third parking data signal (Spk3l) (Spk1l ≠ Spk3l), the other wheel (WHLr) of each of the left and right wheels (WHLr, WHLl) When the communication means (TSNr) determines a match between the first parking data signal (Spk1r) of the other wheel (WHLr) and the third parking data signal (Spk3r) of the other wheel (WHLr) (Spk1r) = Spk3r) is configured to permit transition of the parking brake function (actuation or release) of the one-side wheel (WHLl).

  The parking brake instruction is not performed independently for the left and right wheels, but is performed simultaneously for the left and right wheels. Therefore, a parking brake instruction (release → activate or actuate → release) is established on one of the left and right wheels of the vehicle (for example, the right rear wheel and the left rear wheel) (for example, the right rear wheel WHLr), If the other wheel (for example, the left rear wheel WHLl) is not established, the communication means (for example, SGLl) between the electronic control unit (for example, ECWl) of the other wheel and the vehicle body side electronic control unit ECB is appropriate. There may be a situation where it is not working properly.

  According to the above configuration, on the basis of the determination result (for example, Spk1r = Spk3r) of the wheel side electronic control unit (for example, ECWr) of the one side wheel, parking is performed in the wheel side electronic control unit (for example, ECWl) of the other side wheel. A brake instruction (Spkl) is issued. For this reason, even if a part of the electric braking device is in an inappropriate state, the parking brake function can be appropriately exhibited as a vehicle.

1 is an overall configuration diagram of an electric braking device for a vehicle according to an embodiment of the present invention. It is the schematic for demonstrating the data signal transmission via the vehicle body side electronic control unit ECB, the communication line SGL, and the braking means BRK. It is a flowchart for demonstrating the process of the activation / release of a parking brake, and the transmission process of the parking data signal Spk. It is the schematic for demonstrating the wheel side electronic control unit ECW, the electric motor MTR, the lock mechanism LOK, and the pressing force acquisition means FBA. It is a functional block diagram for demonstrating the error detection method in transmission of the parking data signal Spk. It is the schematic for demonstrating the structure of the locking mechanism LOK for parking brakes, the action | operation, and cancellation | release. It is a time series diagram for demonstrating the action | operation and cancellation | release of a parking brake.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of an electric braking device for a vehicle according to 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 an electric braking device for a vehicle according to an embodiment of the present invention.

  A vehicle including an 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 PSW, a wheel speed acquisition unit VWA, and a vehicle body side electronic control unit ECB. , Braking means BRK (BRKr, BRKl), communication lines SGL (SGLr, SGLl), and power sources BAT, ALT.

  Here, the suffix “r” at the end of each symbol represents “the one corresponding to the right wheel”, and the suffix “l” represents “the one corresponding to the left wheel”. That is, the suffix “r” is attached to “things provided on the right wheel and those connected to the right wheel”, and “things provided on the left wheel and those connected to the left wheel” are attached. The subscript “l” is added. The left and right wheels are distinguished by subscripts “r” and “l”. For example, the right wheel side braking means BRKr and the left wheel side braking means BRKl are represented. On the other hand, the same configuration is adopted for the vehicle corresponding to the right wheel WHLr and the vehicle corresponding to the left wheel WHLl. Therefore, when it is not necessary to distinguish the left and right wheels, the suffixes “r” and “l” at the end of the symbol are omitted. For example, it is expressed as braking means BRK.

  The braking operation member BP is a member (for example, a brake pedal) that is operated by the driver to decelerate and stop 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 running vehicle is decelerated. The braking operation member BP is provided with a braking operation amount acquisition means BPA. The operation amount (braking operation amount) Bpa of the braking operation member BP by the driver is acquired (detected) by the braking operation amount acquisition means BPA.

  As 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 acquired braking operation amount Bpa is input to the vehicle body side electronic control unit ECB.

  The acceleration operation member AP is a member (for example, an accelerator pedal) that is operated by the driver 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.

  The parking brake switch (also simply referred to as a switch) PSW is a manual switch operated by the driver, and outputs an on / off (on / off) signal Psw of the switch PSW. The driver instructs the operation or release of the parking brake function for maintaining the vehicle stop state by operating the switch PSW. For example, the operation of the parking brake is instructed when the instruction signal Psw is ON (ON), and the release of the parking brake is instructed when the Psw is OFF (OFF).

  The wheel speed acquisition means VWA acquires (detects) the rotational speed Vwa of each wheel of the vehicle. The detection signal (wheel speed) Vwa of the wheel speed acquisition means VWA is used for calculation of the vehicle body speed Vxa. The braking operation amount Bpa, the acceleration operation amount Apa, the wheel speed Vwa, and the instruction signal Psw are input to the vehicle body side electronic control unit ECB.

  A vehicle body side electronic control unit ECB is provided in the vehicle body BDY of the vehicle. The vehicle body side electronic control unit ECB includes a vehicle body side calculation unit ENB and a vehicle body side communication unit CMB. In the vehicle body side calculation unit ENB (particularly, the normal brake calculation block SBR), the target pressure Fbt of the normal brake is calculated based on the braking operation amount Bpa. In the vehicle body side calculation unit ENB (particularly, the parking brake calculation block PBR), the parking data signal Spk is calculated based on the switch signal Psw. The vehicle body side communication unit CMB sends the calculation result (Fbt, Spk, etc.) in the vehicle body side calculation unit ENB via the communication line (also called signal line) SGL (SGLr, SGLl) to the wheel side electronic control unit ECW (ECWr). , ECWl). In addition, the vehicle body side communication unit CMB is connected to the electric motor MTR, the solenoid SOL, and each sensor (FBA, etc.) from the wheel side electronic control unit ECW (ECWr, ECWl) via the communication line SGL (SGLr, SGLl). Receive status. Here, the vehicle body side communication unit CMB is a part of the communication means TSN between the vehicle body side electronic control unit ECB and the wheel side electronic control unit ECW.

  The communication line SGL (SGLr, SGLl) is a communication means between the vehicle body side electronic control unit ECB and the wheel side electronic control unit ECW, and a data signal Ssv described later between the ECB and ECW (ECWr, ECWl). , Spk is transmitted. A serial communication bus is adopted as the communication 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) communication bus can be adopted as the serial communication bus.

  Braking means BRK (BRKr, BRKl) is provided on the left and right wheels WHL (WHLr, WHLl) of the vehicle. The braking means (brake actuator) BRK is composed of a wheel side electronic control unit ECW (ECWr, ECWl), an electric motor MTR, a solenoid SOL, and the like.

  The wheel side electronic control unit ECW includes a wheel side communication unit CMW, a wheel side calculation unit ENW, and a drive unit DRV. The wheel side communication unit CMW is a part of the communication means TSN between the vehicle body side electronic control unit ECB and the wheel side electronic control unit ECW. Specifically, the wheel side communication unit CMW receives the target pressing force Fbt and the parking brake instruction signal Spk from the vehicle body side communication unit CMB of the vehicle body side electronic control unit ECB via the communication line SGL. In addition, the wheel side communication unit CMW transmits the state of the electric motor MTR, the solenoid SOL, and each sensor (FBA, etc.) to the vehicle body side communication unit CMB of the vehicle body side electronic control unit ECB via the communication line SGL. .

  In the wheel side calculation unit ENW, signals S1 to S4 for controlling the switching elements SW1 to SW4 for driving the electric motor MTR are calculated based on the target pressing force Fbt. Further, based on the parking data signal Spk, the signals S1 to S4 for controlling the switching elements SW1 to SW4 for driving the electric motor MTR and the signal Ss for controlling the switching element SS for driving the solenoid SOL. Is calculated.

  The drive unit DRV includes a bridge circuit HBR including switching elements SW1 to SW4 and a switching element SS. The bridge circuit HBR rotates and drives the electric motor MTR based on the drive signals S1 to S4 and adjusts its output. The switching element SS switches between the excitation state and the non-excitation state of the solenoid SOL based on the drive signal Ss.

  During normal braking, the braking torque of the wheels is controlled by adjusting the output of the electric motor MTR, and the deceleration of the vehicle is adjusted. Further, at the time of parking brake, the movement of the electric motor MTR is restricted by the solenoid SOL while the output of the electric motor MTR is increased, and the stopped state of the vehicle is maintained even when the energization of the electric motor MTR is stopped. .

  A storage battery (battery) BAT and a generator (alternator) ALT are provided on the vehicle body BDY side. When the storage amount of the storage battery BAT decreases, the storage battery BAT is charged by the generator ALT. The storage battery BAT and the generator ALT are collectively referred to as a power source. The power source supplies power to the ECB and ECW via the power line PWL. That is, power to the electric motor MTR and the solenoid SOL is supplied by the power source BAT and the like.

  The vehicle body side electronic control unit ECB, the transmission of the data signal via the communication line SGL, and the braking means BRK will be described with reference to the schematic diagram of FIG.

<Car body side electronic control unit ECB>
The vehicle body side electronic control unit ECB includes an electric circuit including a processor, and is fixed to the vehicle body BDY. Here, the “processor” is an electronic circuit that executes arithmetic processing. The vehicle body side electronic control unit ECB includes a vehicle body side calculation unit ENB and a vehicle body side communication unit CMB.

  The vehicle body side calculation unit ENB includes a normal brake calculation block SBR, a vehicle body speed calculation block VXA, a wheel slip suppression control block EWS, and a parking brake calculation block PBR. The normal brake calculation block SBR, the vehicle body speed calculation block VXA, the wheel slip suppression control block EWS, and the parking brake calculation block PBR are control algorithms and are programmed in a processor in the vehicle body side electronic control unit ECB.

  In the normal brake calculation block SBR, a target pressing force Fbs (a so-called target value in the normal brake function) is calculated based on the braking operation amount Bpa. Here, the target pressing force Fbs is a target value of the force (pressing force) by which the friction member (brake pad) MSB presses the rotating member (brake disc) KTB. The target pressing force Fbs is calculated based on the braking operation amount Bpa and a preset calculation map CHfb. Specifically, the target pressing force Fbs is calculated so as to increase as the braking operation amount Bpa increases (characteristic CHfb).

  The vehicle body speed calculation block VXA can be calculated based on the wheel speed Vwa acquired (detected) by the wheel speed acquisition means VWA and a known method. For example, the fastest speed among the rotation speeds Vwa of the wheels WHL can be calculated as the vehicle body speed Vxa.

  In the wheel slip suppression control block EWS, the target pressing force Fbs is adjusted based on the wheel speed Vwa and the vehicle body speed Vxa so that the wheel slip does not become excessive, and the final target pressing force Fbt is calculated. . The wheel slip suppression control block EWS includes an anti-skid control block ABS that suppresses the tendency of wheel locking (excessive deceleration slip) and a traction control block TCS that suppresses the tendency of wheel spin (excessive acceleration slip). .

  In the anti-skid control block ABS, the time change amount (wheel acceleration) dVw is calculated based on the wheel speed Vwa. Further, a deceleration slip Sgs (= Vxa−Vwa) that is a deviation between the vehicle body speed Vxa and the wheel speed Vwa is calculated. Based on the wheel acceleration dVw and the deceleration slip Sgs, the target pressing force Fbs is adjusted so that the deceleration slip of the wheel is reduced, and the final target pressing force Fbt is determined. Specifically, when the wheel acceleration dVw is smaller than a predetermined value dvw1 (negative value) and the deceleration slip Sgs is larger than a predetermined value sgs1 (positive value), the target pressing force Fbs is decreased. By calculating the target pressing force Fbt, the tendency of the wheels to lock is avoided.

  In the traction control block TCS, the wheel acceleration dVw is calculated based on the wheel speed Vwa, and an acceleration slip Sks (= Vwa−Vxa) that is a deviation between the vehicle body speed Vxa and the wheel speed Vwa is calculated. Based on the wheel acceleration dVw and the acceleration slip Sks, the target pressing force Fbs is adjusted and the target pressing force Fbt is determined so that the acceleration slip of the wheel is reduced. Specifically, when the wheel acceleration dVw is larger than a predetermined value dvw2 (positive value) and the acceleration slip Sks is larger than a predetermined value sks1 (positive value), the target pressing force Fbs (vehicle acceleration) As a result, Fbs = 0) is increased and the target pressing force Fbt is calculated, whereby the spin tendency of the wheels is avoided.

  In the parking brake calculation block PBR, a state (necessity) of a parking brake (also referred to as parking brake) for maintaining the stopped state of the vehicle is determined, and a signal Spk for instructing the operation or release of the parking brake is determined. The That is, in the parking brake calculation block PBR, the determination of the operation of the parking brake or the release of the parking brake is executed, and as a result, Spk is calculated. The signal Spk is a signal representing the state of the parking brake. For example, the parking data signal Spk is expressed as “released state” or “operating state”. The parking brake calculation block PBR has a manual mode MPK based on a driver's switch operation and an automatic mode APK based on a vehicle body speed Vxa and the like.

  A switch signal Psw, a vehicle body speed Vxa, and an acceleration operation amount Apa are input to the parking brake calculation block PBR. A parking brake signal Spk is output from the parking brake calculation block PBR. Specifically, when it is determined that “no parking brake is required (release determination)”, an instruction signal Spk indicating the release determination is output. When it is determined that “a parking brake is necessary (operation determination)”, an instruction signal Spk indicating the operation determination is output.

  In the manual mode MPK of the parking brake calculation block PBR, the necessity state of the parking brake is determined based on the operation signal Psw of the manual switch PSW for parking brake operated by the driver. For example, the “parking brake release state” is calculated based on the OFF state of the switch PSW, and the “parking brake operating state” is calculated based on the PSW on state.

  In the automatic mode APK of the parking brake calculation block PBR, 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 PSW. Is determined. Specifically, in the automatic mode APK, the parking brake state is determined based on the vehicle body speed Vxa and the acceleration operation amount Apa.

  For example, when the vehicle is traveling (Vxa> 0), the parking brake release state is determined. When the vehicle stops (that is, when Vxa becomes zero), the operating state of the parking brake is determined, and the parking data signal Spk is switched from the “released state” to the “operating state”. Further, when the driver operates the acceleration operation member AP and the acceleration operation amount Apa exceeds the predetermined value ap1, the release state of the parking brake is determined, and the signal Spk changes from the “actuated state” to the “released state”. Can be switched.

  The target pressing force Fbt, the parking data signal Spk, and the vehicle body speed Vxa calculated in each block are output to the vehicle body side communication unit CMB. The vehicle body side communication unit CMB is connected to a communication line (signal line) SGL, and exchanges data with the wheel side communication unit CMW of the wheel side electronic control unit ECW. In the transmission / reception of the data signal, the vehicle body side communication unit CMB and the wheel side communication unit CMW perform data signal inspection (error check).

<Data signal transmission via communication line SGL>
A serial communication bus (for example, CAN communication) is employed as the communication line SGL. Data signals Ssv and Spk transmitted via the communication line SGL are schematically shown in a balloon in FIG.

  In the transmission of the data signal, the data signal Ssv (Ssvr, Ssvl) related to the normal brake is communicated at a predetermined calculation cycle of the signal (referred to as constant communication and regular communication). Here, the data signal Ssv is referred to as a “normal data signal”. In FIG. 2, the normal data signal Ssvr for the right wheel and the normal data signal Ssvl for the left wheel are alternately transmitted. The normal data signal Ssv includes the target pressing force Fbt, the actual pressing force Fba, the rotation angle Mka, the motor current Ima, the solenoid current Isa, and the vehicle body speed Vxa. In the transmission of the normal data signal, a clump for each signal can be adopted instead of a clump for each wheel (for example, Ssvr). For example, the target pressing force Fbtr for the right wheel and the target pressing force Fbtl for the left wheel can be transmitted for each communication cycle as one lump.

  On the other hand, the data signal Spk regarding the parking brake is not communicated every communication cycle, and is transmitted so as to interrupt the regular communication only when necessary (referred to as irregular communication). The data signal Spk is referred to as a “parking data signal”. Here, “when necessary” is when the parking data signal Spk changes (corresponding calculation cycle). That is, in the calculation cycle (time point) when the parking data signal Spk transits from the “released state” to the “actuated state”, or at the computation cycle when the parking data signal Spk transits from the “operated state” to the “released state” The signal Spk is transmitted toward the wheel side communication unit CMW. Since the parking data signal Spk is transmitted from the vehicle body side communication unit CMB to the wheel side communication unit CMW due to an event (event) of a change in the parking data signal Spk, it is also referred to as “event communication”.

  In the serial communication bus, one group of a plurality of signals is called a “message” or “data frame”. Therefore, the data signals Ssv and Spk correspond to messages. Messages (especially data fields within messages) have capacity limitations (eg, up to 8 bytes). For this reason, as the number of types of signals increases, the number of messages (types) on the serial communication bus increases, and the period for obtaining the necessary signals becomes longer. In particular, when the electronic control units ECB and ECW are connected to other electronic control units (for example, a steering system electronic control unit and a drive system electrical control unit) to form an in-vehicle network, the number of messages increases. Become prominent. Further, when the usage rate (bus load) of the serial communication bus increases, data signals may be retransmitted frequently and communication may not be performed properly. However, in this embodiment, the normal data signal Ssv is always transmitted by communication, and the parking data signal Spk is transmitted by event communication, so that the number of messages on the serial communication bus is reduced and the bus load is suppressed. As a result, even when an in-vehicle network is formed, proper information transmission is performed, and high-response control of the electric motor MTR can be achieved.

<Braking means BRK>
Braking means (brake actuator) BRK is provided on the left and right wheels WHL of the vehicle. For example, it can be provided on the left and right wheels behind the vehicle. The braking means BRK presses the friction member MSB against the rotating member KTB that rotates integrally with the wheel. Due to the frictional force generated at this time, the braking means BRK applies a braking torque to the wheel WHL, generates a braking force, and decelerates the traveling vehicle (functions as a normal brake). Further, while the vehicle is stopped, the braking means BRK functions as a parking brake that maintains the stopped state.

  As the 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.

  The braking means BRK includes a brake caliper CRP, a pressing member PSN, an electric motor MTR, a rotation angle acquisition means MKA, a reduction gear GSK, a shaft member SFT, a screw member NJB, a pressing force acquisition means FBA, a parking brake locking mechanism LOK, and It is comprised by the wheel side electronic control unit ECW.

  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 ECW) are accommodated therein. 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. The PSN has a cylindrical shape and is moved in the direction of its central axis.

  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. The rotational power (torque around the shaft axis) of the shaft member SFT is converted into linear power (thrust in the axial direction of the pressing member PSN) 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. 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.

  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 wheel side electronic control unit ECW.

  The rotation angle 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 rotation angle acquisition unit 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 shaft of the electric motor MTR. The detected position (rotation angle) Mka is input to the wheel-side electronic control unit ECW (specifically, the processor in the ECW).

  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.

  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 wheel side electronic control unit ECW (specifically, a processor in the ECW). 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.

  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.

  The wheel side electronic control unit ECW is an electric circuit that drives the electric motor MTR and the solenoid SOL. The wheel-side electronic control unit ECW drives the electric motor MTR based on the target pressing force Fbt, controls its output, and exhibits the normal braking function. Moreover, the electric motor MTR and the solenoid SOL are controlled by the wheel side electronic control unit ECW based on the instruction signal Spk, and the parking brake function is exhibited. Here, the target pressing force Fbt (part of Ssv) and the parking data signal Spk are transmitted from the vehicle body side electronic control unit ECB to the wheel side electronic control unit ECW via the communication line SGL. The wheel side electronic control unit ECW is disposed (fixed) inside the caliper CRP.

  The wheel side electronic control unit ECW includes a wheel side communication unit CMW, a wheel side calculation unit ENW, and a drive unit DRV. The wheel side communication unit CMW is connected to the communication line SGL, and exchanges data with the vehicle body side communication unit CMB of the vehicle body side electronic control unit ECW. Similar to the vehicle body side communication unit CMB, the wheel side communication unit CMW performs an inspection of data signal errors.

  In the wheel side calculation unit ENW, signals (drive signals) S1 to S4 necessary for driving the electric motor MTR are calculated based on the target pressing force Fbt. Further, in the wheel side calculation unit ENW, the drive signals S1 to S4 of the electric motor MTR and the signal (drive signal) Ss necessary for driving the solenoid SOL are calculated based on the parking data signal Spk.

  The drive unit DRV includes a bridge circuit HBR including switching elements SW1 to SW4 and a switching element SS. The bridge circuit HBR rotates the MTR by switching the energization state of the switching elements SW1 to SW4, and adjusts the output of the electric motor MTR. The switching element SS forms a restrained state (locked state) and an unrestrained state (released state) of the lock mechanism LOK by switching between an excited state and a non-excited state of the solenoid SOL.

<Calculation process of parking brake operation / release and transmission process of parking data signal Spk>
With reference to the flowchart of FIG. 3, the calculation process of parking brake operation / release and the transmission / non-transmission process (event communication described above) of the parking data signal Spk will be described. The parking data signal Spk includes a signal Spkr for the right wheel and a signal Spkl for the left wheel. Since Spkr and Spkl are the same, as described above, the suffix “r” at the end of the symbol, “L” is omitted and represented as a parking data signal Spk. The subscript “(n−1)” represents “thing in the previous computation cycle”, and the subscript “(n)” represents “in the current computation cycle”.

  In step S110, the previous parking data signal (previous calculation value) Spk (n-1) and the current parking data signal (current calculation value) Spk (n) are read. Here, the previous calculation value Spk (n−1) is a parking data signal in the previous calculation cycle, and the current calculation value Spk (n) is a parking data signal in the current calculation cycle. Next, the process proceeds to step S120.

  In step S120, it is determined whether or not the previous calculated value Spk (n-1) matches the current calculated value Spk (n). If the previous calculated value Spk (n−1) and the current calculated value Spk (n) match and the condition of step S120 is affirmed (“YES”), the process proceeds to step S130. On the other hand, if the previous calculated value Spk (n−1) and the current calculated value Spk (n) do not match (if they do not match) and the condition in step S120 is negative (“NO”), Proceed to step S140.

  In step S130, it is determined whether or not the current parking data signal (currently calculated value) Spk (n) indicates an operating state. If the calculated value Spk (n) is an operation instruction this time and the condition in step S130 is affirmed ("YES"), the process proceeds to step S150. On the other hand, if the current calculated value Spk (n) is a release instruction (if it is not an operation instruction) and the condition in step S130 is negative ("NO"), the process proceeds to step S160.

  Similarly, in step S140, it is determined whether or not the current parking data signal (currently calculated value) Spk (n) indicates an operating state. If the calculated value Spk (n) is an operation instruction this time and the condition in step S140 is affirmed (“YES”), the process proceeds to step S170. On the other hand, if the current calculated value Spk (n) is a release instruction (when it is not an operation instruction) and the condition of step S140 is negative ("NO"), the process proceeds to step S180.

  In step S150, the parking data signal Spk is not transmitted to the wheel side electronic control unit ECW in order to continue the operation state of the parking brake. In the calculation processing up to step S150, the previous parking data signal Spk (n-1) and the current parking data signal Spk (n) both indicate the operating state of the parking brake. Since the prior state is continued, the parking data signal Spk (n) is not transmitted in the current calculation cycle.

  In step S160, the parking data signal Spk is not transmitted to the wheel side electronic control unit ECW in order to continue the release state of the parking brake. In the calculation process up to step S160, the previous parking data signal Spk (n-1) and the current parking data signal Spk (n) both indicate the parking brake release state. Since the prior state is continued, the parking data signal Spk (n) is not transmitted in the current calculation cycle.

  In step S170, a parking data signal Spk (operation processing signal) is transmitted toward the wheel side electronic control unit ECW in order to cause the parking brake to transition from the released state to the operating state. Specifically, the parking data signal Spk (n-1) instructed the release state in the previous calculation cycle, but the parking data signal Spk (n) instructed the operating state in the current calculation cycle. Therefore, in order to instruct the start of the parking brake operation process, the parking data signal Spk (n) is transmitted to the wheel side electronic control unit ECW via the communication means TSN.

  In step S180, a parking data signal Spk (release processing signal) is transmitted toward the wheel side electronic control unit ECW in order to cause the parking brake to transition from the operating state to the released state. Specifically, the parking data signal Spk (n-1) instructed the operating state in the previous calculation cycle, but the parking data signal Spk (n) instructed the release state in the current calculation cycle. Accordingly, the parking data signal Spk (n) is transmitted to the wheel-side electronic control unit ECW via the communication means TSN in order to instruct the start of the parking brake release process.

  From step S150, S160, S170, S180, the process proceeds to step S190. In step S190, the parking data signal Spk (n) of the current calculation cycle is stored as the parking data signal Spk (n-1) of the previous calculation cycle. And then. It returns to step S110 again.

  In the above, the calculation process of the operation / release of a parking brake and the transmission form of the parking data signal in that case were demonstrated. In the parking data signal Spk, when the result Spk (n−1) of the previous calculation cycle and the result Spk (n) of the current calculation cycle match, the parking data signal Spk is transmitted via the communication means TSN. Is not transmitted to the wheel side electronic control unit ECW. However, in the parking data signal Spk, when the calculation result Spk (n−1) of the previous cycle is different from the calculation result Spk (n) of the current cycle, the parking data signal Spk (n) in the current calculation cycle is Then, it is transmitted to the wheel side electronic control unit ECW via the communication means TSN. In other words, only when the result Spk (n-1) of the previous calculation period of the parking data signal and the result Spk (n) of the current calculation period of the parking data signal are different, the parking data signal Spk (n) is Communicated. Thereby, since parking data signal Spk is transmitted only when the state transition of a parking brake is required, the load of communication means TSN can be reduced.

  The wheel side electronic control unit ECW, the electric motor MTR, the lock mechanism LOK, and the pressing force acquisition means FBA will be described with reference to the schematic diagram of FIG.

<Wheel-side electronic control unit ECW>
The wheel-side electronic control unit ECW includes a wheel-side communication unit CMW, a wheel-side calculation unit ENW, and a drive unit DRV. The wheel-side electronic control unit ECW adjusts the energization state (finally the magnitude and direction of the current) to the electric motor MTR based on the target pressing force (target value) Fbt, and outputs the electric motor MTR and the rotation direction. To control. Further, the wheel side electronic control unit ECW adjusts the energization state to the electric motor MTR and the solenoid SOL based on the parking data signal Spk, and controls the biting operation of the lock mechanism LOK.

≪Wheel side communication unit CMW≫
The wheel side communication unit CMW is connected to a communication line SGL (a serial communication bus, for example, CAN communication). The wheel side communication unit CMW exchanges data signals Ssv and Spk with the vehicle body side communication unit CMB of the vehicle body side electronic control unit ECW via the communication line SGL. Here, the data signal Ssv is a data signal for realizing a normal brake function, and is referred to as a “normal data signal”. The normal data signal Ssv includes the target pressing force Fbt, the actual pressing force Fba, the rotation angle Mka, the motor current Ima, the solenoid current Isa, and the vehicle body speed Vxa. The data signal Spk is a data signal for realizing a parking brake function, and is referred to as a “parking data signal”.

  In the communication means TSN configured by the vehicle body side communication unit CMB, the communication line SGL, and the wheel side communication unit CMW, the normal data signal Ssv is periodically communicated periodically (that is, at a predetermined timing (that is, The communication is performed every Ssv calculation cycle and is also referred to as constant communication). Further, in the communication means TSN (CMB, SGL, CMW), the parking data signal Spk is performed not by regular communication but by irregular communication (also called event communication). Specifically, when the parking data signal Spk transits from the “released state” to the “actuated state” and when the parking data signal Spk transits from the “operated state” to the “released state”, the parking data signal Spk Is transmitted. That is, the information transmission of the parking data signal Spk is performed only when necessary.

≪Wheel side calculation unit ENW≫
The wheel side calculation unit ENW is a control algorithm and is programmed in a processor in the wheel side electronic control unit ECW. The wheel side calculation unit ENW includes an instruction energization amount calculation block IST, a pressing force feedback control block IBT, a target energization amount 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. Consists of ESL.

  The wheel side calculation unit ENW has control for exerting two functions of a normal brake and a parking brake. In the wheel side calculation unit ENW, one of the two functions is selected by the selection means SNT in the target energization amount calculation block IMT. For this reason, the two functions are not activated simultaneously. For example, when the driver operates the braking operation member BP, the normal brake function is selected, and when there is no operation, the parking brake function is selected.

  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, a target energization amount calculation block IMT, a pulse width modulation block PWM, and a switching control block SWT.

  The command energization amount calculation block IST calculates the command energization amount Ist based on the target pressing force Fbt (one of the normal data signals Ssv) 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.

  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) eFb 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, the command energization amount Ist is determined so as to reduce this error.

  The target energization amount 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 target energization amount 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 as the final target energization amount Imt by the selection means SNT in the target energization amount calculation block IMT and output.

  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.

  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. Based on the deviation eIm between the target energization amount Imt and the actual energization amount Ima, the duty ratio Dut is corrected (finely adjusted). With this current feedback control, highly accurate motor control can be achieved.

  The switching control block SWT outputs drive signals (S1 to S4) to the switching elements (SW1 to SW4) constituting the bridge circuit HBR based on the duty ratio (target value) Dut. This drive signal indicates whether each switching element is energized or not energized. Specifically, when the electric motor MTR is driven in the forward rotation direction based on the duty ratio Dut, SW1 and SW4 are energized (on state), and SW2 and SW3 are de-energized (off state) ) And the energization / non-energization states of SW1 and SW4 are switched in the energization time (energization cycle) corresponding to Dut. Similarly, when the electric motor MTR is driven in the reverse direction, SW1 and SW4 are controlled to be in a non-energized state (off state), and SW2 and SW3 are controlled to be in an 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.

  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 inoperative state. The start and release are determined based on a change in the parking data signal Spk (“release state” → “operation state” or “operation state” → “release state”). The parking brake function includes a parking brake control block IPK, a target energization amount calculation block IMT, a pulse width modulation block PWM, a switching control block SWT, and a solenoid control block ESL.

  In the parking brake control block IPK, the parking brake target energization is based on the parking data signal Spk for instructing the transition of the parking brake function, the pressing force (actual value) Fba, and the rotation angle (actual value) Mka of the electric motor MTR. The amount Ipk and the solenoid energization instruction signal Snd are calculated. When the parking data signal Spk is not input to the parking brake control block IPK (that is, when transition of the parking brake function is prohibited), the state is maintained as it is. Specifically, when Spk is not input, the parking brake operation state or the release state is continued. On the other hand, when the parking data signal Spk is input to the parking brake control block IPK (that is, when the transition of the parking brake function is permitted), the parking brake state is changed (changed). Specifically, if the advance parking brake is in the released state, the operation state is changed, and if the advance parking brake is in the operated state, the operation state is changed to the released state.

  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 command (transition from the “release state” to the “operation state” in the parking data signal Spk). And a solenoid instruction signal Snd for instructing energization of the solenoid SOL. Here, the parking brake target energization amount 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 Snd is a control flag, and “Snd = 0” instructs deenergization of the solenoid SOL, and “Snd = 1” instructs energization of the solenoid SOL.

  Further, in the parking brake control block IPK, a parking brake target energization for controlling the electric motor MTR in response to a parking brake release command (transition from the “operation state” to the “release state” in the parking data signal Spk). The quantity Ipk is output. In the transition from the operating state to the released state of the parking data signal, the parking brake target energization amount Ipk is determined according to a preset characteristic as described above. However, in the transition from the operation state of the parking data signal to the release state, the solenoid SOL is maintained in a non-energized state.

  In the target energization amount 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 target energization amount 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.

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

≪Driver DRV≫
The drive unit DRV is an electric circuit for driving the electric motor MTR and the solenoid SOL. The drive unit (drive circuit) DRV includes a bridge circuit HBR, an HBR energization amount acquisition unit (motor current acquisition unit) IMA, a switching element SS, and a solenoid SOL energization amount acquisition unit (solenoid current acquisition unit) ISA. Is done. FIG. 4 shows an example of a drive unit DRV in the case where a motor with a brush (also simply referred to as a brush motor) is employed as the electric motor MTR.

  The 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 rotation direction or reverse rotation direction) of the electric motor can be controlled. It is. The bridge circuit HBR is configured by switching elements SW1 to SW4. The switching elements SW1 to SW4 are elements that can turn on (energize) / off (non-energize) a part of the electric circuit. The switching elements SW1 to SW4 are driven by the wheel-side arithmetic unit ENW (signals S1 to S4 from the switching control block SWT), and the electric motor MTR rotates by switching the energization / non-energization state of each switching element. Direction and output torque are adjusted. For example, a MOS-FET or IGBT is used as the switching element.

  When the electric motor MTR is driven in the forward direction, SW1 and SW4 are turned on (on state), and SW2 and SW3 are turned off (off state). That is, in the forward rotation driving of the electric motor MTR in which the braking torque is increased, the current flows in the order of “S1 → electric motor MTR (BLC / CMT) → SW4”. On the other hand, when the electric motor MTR is driven in the reverse direction, SW1 and SW4 are turned off (off state), and SW2 and SW3 are turned on (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 “SW2 → electric motor MTR (BLC / CMT) → SW3”.

  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 rotor position (rotation angle) Mka of the electric motor MTR is acquired by the rotation angle acquisition means MKA. 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, and the electric motor MTR is driven. The rotation direction (forward rotation or reverse rotation) of the brushless motor is determined by the relationship between the rotor and the excitation position.

  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 by the motor current sensor IMA as the motor energization amount Ima.

  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 wheel side arithmetic unit ENW (signal Ss from the solenoid control block ESL). The energization / non-energization state of the switching element SS 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.

  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 the solenoid energization amount Isa by the solenoid current sensor ISA.

<Electric motor MTR>
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 rotation angle acquisition means MKA is provided coaxially with the electric motor MTR, and transmits the rotation angle Mka to the wheel side electronic control unit ECW.

  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. The brushless motor has a structure in which the rotor (rotor) is a permanent magnet and the stator (stator) is a winding circuit (electromagnet), and the rotational position Mka of the rotor is detected by the rotation angle acquisition means MKA. When the switching element is switched, the supply current is commutated.

<Parking brake lock mechanism LOK>
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, and is also referred to as “restraint means”.

  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 rotation of the electric motor MTR (that is, 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.

<Pressing force acquisition means FBA>
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 input to the wheel side electronic control unit ECW.

<Error detection of parking data signal Spk>
With reference to the functional block diagram of FIG. 5, a method for detecting an error in transmitting the parking data signal Spk will be described. Here, the suffix “r” at the end of each symbol represents “the one corresponding to the right wheel”, and the suffix “l” represents “the one corresponding to the left wheel”. For example, the right wheel side communication unit CMWr and the left wheel side communication unit CMWl are represented. On the other hand, the same configuration is adopted for the vehicle corresponding to the right wheel WHLr and the vehicle corresponding to the left wheel WHLl. Therefore, if there is no need to distinguish between the left and right wheels, the suffixes “r” and “l” can be omitted. For example, it is expressed as a wheel side communication unit CMW. Further, the vehicle body side communication unit CMB, the communication line SGL, and the wheel side communication unit CMW are collectively referred to as communication means TSN.

  Hereinafter, the communication means TSNr (that is, CMB, SGLr, CMWr) of the right wheel WHLr will be described. Since the communication means TSNl (that is, CMB, SGLl, CMWl) of the left wheel WHLl is the same as the communication means TSNr of the right wheel WHLr, description thereof is omitted.

  The vehicle body side communication unit CMB is provided with an inspection block CHK. The wheel side communication unit CMWr is provided with an inspection block CHK and a comparison block HKK. Here, in the check block CHK, it is checked whether or not the signal is proper (that is, whether there is an error). Specifically, in the check block CHK, signal error detection is performed by a check sum (Check sum: an error detection method when transmitting / receiving data). When an error (error) occurs in the data signal on the communication path, a procedure for retransmitting the data signal (data retransmission request from the CMWr to the CMB) as shown by the broken line is taken.

  Here, the checksum is obtained by considering the data signal of the divided block as a numerical value and calculating the sum thereof, and is transmitted together with the data signal. On the receiving side, the checksum is similarly calculated from the transmitted data signal. Then, an error in the data is determined based on whether or not the checksum sent from the transmission side matches the received checksum. Specifically, when the chuck sums match, it is determined that there is no error in the data signal (the data signal is appropriate), and when the chuck sums do not match, there is an error in the data signal ( Data signal is inappropriate).

  The vehicle body side communication unit CMB and the wheel side communication unit CMWr are connected via a communication line SGLr. When the parking data signal Spk is input to the vehicle body side communication unit CMB, the parking data signal Spk is transmitted as the first parking data signal Spk1r to the wheel side communication unit CMWr via the inspection block CHK. The first parking data signal Spk1r received by the wheel side communication unit CMWr is subjected to error detection by a checksum in the inspection block CHK of the wheel side communication unit CMWr. When it is determined that there is no error in the first parking data signal Spk1r in the inspection block CHK of the wheel side communication unit CMWr, the first parking data signal Spk1r is stored in the comparison block HKK and passes through the inspection block CHK. And it is transmitted to the vehicle body side communication part CMB as 2nd parking data signal Spk2r. If it is determined in the inspection block CHK of the wheel side communication unit CMWr that the first parking data signal Spk1r has an error, the inspection block CHK of the wheel side communication unit CMWr is changed to the inspection block CHK of the vehicle body side communication unit CMB. A request for retransmission of the first parking data signal Spk1r is transmitted. Then, based on the retransmission request, the first parking data signal Spk1r is transmitted again from the inspection block CHK of the vehicle body side communication unit CMB.

  The second parking data signal Spk2r received by the vehicle body side communication unit CMB is detected by a checksum in the inspection block CHK of the vehicle body side communication unit CMB. When it is determined that there is an error in the second parking data signal Spk2r in the inspection block CHK of the vehicle body side communication unit CMB, the first parking data signal Spk1r is transmitted from the inspection block CHK of the vehicle body side communication unit CMB. . When it is determined that there is no error in the second parking data signal Spk2r in the inspection block CHK of the vehicle body side communication unit CMB, the second parking data signal Spk2r passes through the inspection block CHK and the third parking data signal Spk3r. Is transmitted to the wheel side communication unit CMWr.

  The third parking data signal Spk3r received by the wheel side communication unit CMWr is subjected to error detection by a checksum in the inspection block CHK of the wheel side communication unit CMWr. When it is determined in the inspection block CHK of the wheel side communication unit CMWr that the third parking data signal Spk3r has an error, from the inspection block CHK of the wheel side communication unit CMWr to the inspection block CHK of the vehicle body side communication unit CMB A request for retransmission of the first parking data signal Spk1r is transmitted. Then, based on the retransmission request, the first parking data signal Spk1r is transmitted from the inspection block CHK of the vehicle body side communication unit CMB. The above process is repeated. When it is determined in the inspection block CHK of the wheel side communication unit CMWr that the third parking data signal Spk3r has an error, the third parking data signal Spk3r is converted into the first parking data signal Spk1r in the comparison block HKK. And a match / mismatch is determined. When the first parking data signal Spk1r matches the third parking data signal Spk3r, the parking data signal Spkr is output from the comparison block HKK to the parking brake control block IPK. That is, the signal Spkr that permits the transition of the parking brake function is input to the parking brake control block IPK. However, when the first parking data signal Spk1r and the third parking data signal Spk3r do not match, the parking data signal Spkr is not output from the comparison block HKK. That is, the state where the transition of the parking brake function is prohibited is maintained. If “Spk1r ≠ Spk3r” in the comparison block HKK, the vehicle body side communication unit CMB is instructed to retransmit the first parking data signal Spk1.

  The parking data signal Spk passes through the inspection block CHK, and is transmitted and received between the vehicle body side communication unit CMB and the wheel side communication unit CMWr as Spk1r → Spk2r → Spk3r. In the comparison block HKK of the wheel side communication unit CMWr, when the first parking data signal Spk1r and the third parking data signal Spk3r match (Spk1r = Spk3r), the parking data signal Spk is correct (error). The parking data signal Spkr is output to the parking brake control block IPK. That is, the parking brake is activated (actuated or released). On the other hand, when the first parking data signal Spk1r and the third parking data signal Spk3r do not match (Spk1r ≠ Spk3r), there is an error in the information transmission of the parking data signal Spk, so the parking data signal Spkr is not output, The transition of the parking brake function remains prohibited. That is, the state of the previous parking brake (actuated state or released state) is continued.

  The data signals Ssv and Spk are subjected to error detection by checksum in the inspection block CHK of the vehicle body side communication unit CMB and the wheel side communication unit CMWr. However, 100% of data signal errors are not detected by the checksum. That is, an error in the data signal may not be detected with a small probability. For transmission of the signal (normal data signal) Ssv for realizing the normal brake function, since constant communication (periodic communication) is adopted, even if there is an error in the data signal Ssv, it is correct in the next communication cycle. A signal is received. Since the probability that error detection continuously fails is as close to zero as possible, sufficient Ssv reliability can be ensured by error detection using a checksum. On the other hand, event communication (irregular communication) is adopted for transmission of a signal (parking data signal) Spk for realizing the parking brake function. For this reason, the reliability of the parking data signal Spk can be improved by the above method (repeating signal exchange between the vehicle body side communication unit CMB and the wheel side communication unit CMWr). As a result, during normal braking, the amount of information to be transmitted is reduced, and reliable information transmission can be performed when a parking brake is required.

  The parking brake is not actuated or released separately on the left and right wheels. Therefore, when the parking data signal Spk is output to the parking brake control block IPK at one wheel, the parking data signal Spk can be output to the parking brake control block IPK unconditionally at the other wheel. Specifically, when the parking data signal Spkr is output from the comparison block HKK of the one wheel communication unit CMWr, the inspection block CHK of the vehicle body communication unit CMB uses the parking data signal Spkr as the parking data signal Spkl. To the side communication unit CMWl. Here, the parking data signal Spkl is output to the parking brake control block IPK without passing through the comparison block HKK of the wheel communication unit CMWl on the other side. For this reason, even if the first parking data signal Spk1l and the third parking data signal Spk3l do not match in the comparison block HKK of the wheel side communication unit CMWl, the parking brake of the left wheel WHLl has a function transition ( “Activation → Release” or “Release → Activation”) may be performed. That is, even if the information transmission means (communication means) TSNl of the other wheel WHLl is defective, the parking brake of the other wheel WHLl can operate properly based on the parking data signal Spkr from the one wheel WHLr. .

<Parking brake lock mechanism LOK>
With reference to the schematic diagram of FIG. 6, the structure of a parking brake locking mechanism (corresponding to a restraining means, also simply referred to as a locking mechanism) LOK, and its operation and release will be described. FIG. 6A shows a state where the lock mechanism LOK does not restrain the rotation of the electric motor MTR and the parking brake is released (referred to as a released state). FIG. 6B shows a state where the lock mechanism LOK restrains the rotation of the electric motor MTR and the parking brake is operated (referred to as an operating state).

  The parking brake lock mechanism (restraint means) LOK is configured by a solenoid SOL, a pawl member TSU, a guide member GID, a ratchet gear RCH, and an elastic member SPR. The lock mechanism LOK is a ratchet mechanism (also referred to as a pawl brake) and includes a gear (ratchet gear RCH) and a pawl (claw TSU). Unlike a general gear, the ratchet gear RCH has teeth inclined, and the inclination of the teeth provides directionality to the ratchet mechanism. Specifically, when the ratchet gear rotates in one direction (the direction indicated by the arrow Fwd, the direction in which the pressing force increases, the normal rotation direction of the MTR), the pawl can easily get over the teeth and rotate. Permissible. However, when the ratchet gear rotates in the other direction opposite to the one direction (the direction indicated by the arrow Rvs and the pressing force decreases, the reverse direction of the MTR), the pawls bite into the teeth. The ratchet gear RCH is not rotated (rotation in the other direction is restricted). That is, the ratchet mechanism restricts the direction of the rotational operation to one side.

  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 PSB that 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 (operation direction) Ddw in which the push bar PSB approaches the rotation axis Jrc of the ratchet gear RCH. The pawl member TSU is positioned by the guide member GID fixed to the caliper CRP, and is allowed only in the operation direction Ddw and the movement in the opposite direction (release direction) Dup. A parking brake function is exhibited when the pawl member TSU meshes with the ratchet gear RCH. The pawl member TSU is linearly moved by the solenoid SOL and meshed with the ratchet gear RCH. The ratchet gear RCH is fixed coaxially with the MTR and is supported in a state where it can rotate with respect to the caliper CRP.

  The solenoid actuator (simply referred to as a 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, and a push bar PSB. A magnetic field generated by a current flowing through the coil COL causes a magnetic flux to pass 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. The plunger PLN and the push bar PSB are integrated, and the PSB pushes the pawl member TSU according to the suction operation of the PLN.

  The claw member TSU is provided with a protrusion (claw) at one end. This protruding portion is engaged with the ratchet gear RCH. The other end of the pawl member TSU is in contact with the push bar PSB. When the solenoid SOL is energized, the pawl member TSU is pushed by the push bar PSB and moved in a direction toward the ratchet gear RCH (the direction in which the TSU and RCH are engaged and the operating direction) Ddw.

  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 (surface engaged with the RCH) of the pawl member TSU and the operation direction Ddw. 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 of the pawl. 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 is maintained.

  The ratchet gear RCH is fixed to the input member INP (the output shaft of the MTR) and rotates together with the INP. Unlike a general gear, the ratchet gear RCH is formed with directional teeth (sawtooth teeth). That is, the pawl member TSU is provided with an inclination angle β in the ratchet gear RCH so as to correspond to the rake angle α. Due to this “saw tooth” shape, the directionality of the ratchet gear RCH with respect to the rotational motion about the rotation axis Jrc is determined. Occurs. Specifically, even when the ratchet gear RCH and the pawl member TSU are engaged, the movement corresponding to the forward rotation direction of the electric motor MTR (PSN approaches KTB, the actual pressing force Fba increases, and the braking torque increases. Directional motion) Fwd is allowed. On the other hand, when the ratchet gear RCH and the pawl member TSU are engaged with each other, the movement corresponding to the reverse direction of the electric motor MTR (PSN moves away from KTB, the actual pressing force Fba decreases, and the braking torque decreases). Yes, rotation in the Rvs direction) is constrained (locked). That is, the movement of the electric motor MTR in the reverse direction is limited by the engagement of the ratchet gear RCH and the pawl member TSU.

  The pawl member TSU is always pressed in a direction (release direction) Dup opposite to the operation direction Ddw by an elastic member (for example, a return spring) SPR. When the solenoid SOL is energized, the plunger PLN is drawn into the solenoid SOL, and the push bar PSB presses the pawl member TSU in the operation direction Ddw. That is, a force that opposes the elastic member SPR is generated by the solenoid SOL. When the suction force of the solenoid SOL (force that pushes the TSU in the operating direction Ddw) is greater than the spring force (force that pushes the TSU in the release direction Dup) by the elastic member SPR, the position Pts of 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 attractive force (holding force) of the plunger PLN is lost, and the position Pts of the pawl member TSU is 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 (operating position), and the position Pkj is a position where the pawl member TSU and the ratchet gear RCH are not engaged (release position).

≪Transition from parking brake release state to operating state≫
The outline of each member of the lock mechanism LOK has been described above. Next, a case will be described in which the pawl member TSU and the ratchet gear RCH change from a state where they are not engaged (released state) to a state where they are engaged (actuated state).

  FIG. 6A shows a 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 (spring force) of the elastic member (spring) SPR. That is, the position Pts of the pawl member TSU is at the 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. Then, after the actual pressing force Fba reaches a predetermined value, energization to the solenoid SOL (that is, the coil COL) is started. By this energization, the plunger PLN is attracted to the base BAS, and the plunger PLN is drawn in the operation direction Ddw. The push bar PSB fixed to the plunger PLN is engaged by the suction force of the solenoid SOL (that is, the occlusal force that is the force by which the PSB pushes the TSU) becomes larger than the elastic force (spring force) of the elastic member SPR. The member TSU is moved in the Ddw direction.

  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. 6B, 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 coincide with the α. A force (tangential force) from the ratchet gear RCH acts on the pawl member TSU due to the rigidity of the caliper CRP, the friction member MSB, and the like. Since the component of the tangential force due to the rake angle α acts in the operating direction Ddw, even after the energization of the electric motor MTR and the solenoid SOL is stopped, the bite between the ratchet gear RCH and the pawl member TSU The fit is maintained.

≪Transition from operating state of parking brake to released state≫
Next, a case will be described in which the pawl member TSU and the ratchet gear RCH change from a meshed state (operating state) to a non-engaged state (released state). As shown in FIG. 6B, the claw member TSU and the electric motor MTR and the solenoid SOL are not energized by the rake angle α of the TSU and the inclination angle β of the ratchet gear RCH. The state (operating state) in which the ratchet gear RCH is engaged is maintained. 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) Dup 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 release state shown in FIG.

<Dynamics in transition of parking brake function>
The operation and release of the parking brake will be described with reference to the time series diagram of FIG. FIG. 7A shows a dynamic state in which the transition of the parking brake function changes from the released state to the activated state. Moreover, FIG.7 (b) shows the dynamics which the transition of a parking brake function changes from an operating state to cancellation | release operation | movement. 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.

≪Transition from parking brake release state to operating state≫
First, with reference to FIG. 7A, the transition from the released state of the parking brake function (that is, the restraining means LOK) to the operating state will be described. The traveling vehicle is decelerated, and at time t0, the vehicle body speed Vxa becomes zero and the vehicle stops. Thereafter, at time t1, the driver operates the parking switch PSW, and the operation signal Psw is switched from the off state to the on state. Based on the state transition of the signal Psw, a signal (parking data signal) Spk for realizing the parking brake function is transmitted by event communication (irregular communication). That is, at the time point (calculation cycle) t1 when the transition (change) of the parking brake function is requested by the signal Psw, the transition from the released state of the parking brake to the activated state is permitted (instructed) by the signal Bpk of the parking brake function. The When the parking data signal Spk is not transmitted, the state transition of the parking brake is prohibited, and the state before the communication cycle is maintained.

  In the parking brake control block IPK, based on the parking data signal Spk and preset characteristics, the parking brake target energization amount Ipk corresponds to the energization direction corresponding to the normal rotation of the electric motor MTR (that is, the ratchet gear RCH). In the Fwd direction). Here, in the “preset characteristics”, the target energization amount Ipk is increased to an energization amount at which the pressing force Fba becomes a predetermined value fb1 with an increasing gradient (a change amount with respect to time) ki1. In the target energization amount calculation block IMT, the parking energization 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 Snd of the solenoid SOL is “0 (non-energization instruction) at a time point t3 when a predetermined time tx1 elapses from a time point t2 when the target energization amount Imt (accordingly, the actual pressing force Fba and the actual rotation angle Mka) is made constant. To “1 (energization instruction)”. In the solenoid control block ESL, energization to the solenoid SOL is started from time t3 based on the drive signal Snd. By energizing the solenoid SOL, the pawl member TSU is moved toward the ratchet gear RCH (in the Ddw direction). And the front-end | tip part (claw tip) 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.

  When the amount of change (displacement) from the stored value mk1 (the value of the rotation angle Mka at the time t4) is less than the predetermined value hm1 over a predetermined time tx3 from the time t4 to the time t6, the solenoid SOL and the electric Energization of the motor MTR is stopped at time t6. That is, the engagement operation of the parking brake is finished at time t6. Here, the predetermined value hm1 is a value set in advance based on the geometric relationship of the restraining means LOK (such as the pitch of the teeth of the ratchet gear RCH).

  Until time t3, the suction force of the solenoid SOL does not act, and the tip 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 of the pawl member TSU is in the release position Pkj. When energization to the solenoid SOL is started at time t3, the suction force of the solenoid SOL becomes larger than the elastic force of the elastic member SPR (that is, the push bar PSB is larger than the releasing force in the Dup direction that the SPR exerts on the TSU. The biting force in the Ddw direction exerted on the pawl member TSU becomes larger), and the pawl tip is moved in the Ddw direction until it contacts the teeth of the ratchet gear RCH. At time t5, the pawl member TSU and the ratchet gear RCH are completely engaged with each other, and the pawl tip is moved to the operating position Pkm. After time t5, even if the energization to the solenoid SOL and the electric motor MTR is made zero, the pawl is maintained at the operating position Pkm.

≪Transition from operating state of parking brake to released state≫
Next, with reference to FIG.7 (b), the transition from the operating state of a parking brake function (namely, restraining means LOK) to a cancellation | release state is demonstrated. A case where the parking brake is released by the operation of the switch PSW 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 PSW, and the operation signal Psw is switched from the on state to the off state. Based on the state transition of the operation signal Psw, a parking data signal (a signal for realizing the parking brake function) Spk is transmitted by event communication. That is, the transition from the operating state of the parking brake function to the release state is permitted (requested) at the time point (communication cycle) t7 when the parking brake function needs to be changed (changed). When the parking data signal Spk is not received, the state transition of the parking brake is prohibited (that is, Ipk is not calculated), and the state of the parking brake before the communication cycle is continued.

  Based on the parking data signal Spk and the preset characteristics in the parking brake control block IPK at the calculation cycle t7 in which the state transition of the parking brake function is permitted, the parking brake target energization amount Ipk is changed to the electric motor. It is increased in the energization direction corresponding to the normal rotation of the MTR (that is, the Fwd direction of the ratchet gear RCH). In the target energization amount calculation block IMT, the parking energization target energization amount Ipk is selected as the target energization amount Imt and output. At this time, the drive signal Snd of the solenoid SOL is maintained at “0”, and the solenoid SOL is not energized.

  Due to the engagement between the pawl member TSU and the ratchet gear RCH, the actual pressing force Fba and the actual rotation angle Mka are maintained at the values fb2 and mk2, respectively. The value mk2 of the rotation angle Mka at the time point t7 is stored. In the initial stage of starting increase of the target energization amount Imt (time t7 to t8), the actual pressing force Fba and the actual rotation angle Mka are not increased (constant). When the pressing force Fba is increased beyond the value fb2, the pawl member TSU starts to slide on the tooth surface of the ratchet gear RCH. Further, when the target energization amount Imt is increased in the energization 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 disengaged from the ratchet gear RCH, and the elastic member (return) The position Pts of the pawl is returned to the release position Pkj by the spring SPR.

  The target energization amount Imt is returned to zero at time t9 when the amount of change (displacement) from the state where the rotation angle Mka is constant (stored value mk2 at t7) exceeds the predetermined value hm2. Accordingly, the actual pressing force Fba and the actual rotation angle Mka decrease toward zero. Here, the predetermined value hm2 is a value set in advance based on the geometric relationship of the restraining means LOK.

  WHL ... wheel, BRK ... braking means, ECB ... vehicle body side electronic control unit, ECW ... wheel side electronic control unit, TSN ... communication means, MTR ... electric motor, LOK ... restraint means, Ssv ... normal data signal, Spk ... parking data Signal, Spk1 ... first parking data signal, Spk2 ... second parking data signal, Spk3 ... third parking data signal

Claims (3)

A normal braking function for applying braking torque to the wheels of the vehicle by an electric motor in response to a braking operation by a vehicle driver, decelerating and stopping the vehicle;
Even when there is no braking operation by the driver of the vehicle, a parking brake function for maintaining the stopped state of the vehicle by the electric motor and a restraining means for restraining the movement of the electric motor;
In an electric braking device for a vehicle provided with
A vehicle body side electronic control unit which is provided on the vehicle body side of the vehicle and forms a normal data signal for realizing the normal brake function, and a parking data signal for realizing the parking brake function;
A wheel-side electronic control unit that is provided on the wheel side of the vehicle and controls the electric motor and the restraining means based on the normal data signal and the parking data signal;
A communication means for transmitting the normal data signal and the parking data signal between the vehicle body side electronic control unit and the wheel side electronic control unit;
With
The communication means transmits the normal data signal for each calculation cycle of the normal data signal, and the parking data signal is transmitted as a result of a previous calculation cycle of the parking data signal and a current calculation cycle of the parking data signal. An electric braking device for a vehicle configured to transmit only when the result is different. The electric braking device for a vehicle according to claim 1,
The communication means transmits the parking data signal from the vehicle body side electronic control unit to the wheel side electronic control unit as a first parking data signal, and transmits the first parking data signal from the wheel side electronic control unit to the vehicle body side. The second parking data signal is transmitted to the electronic control unit, the second parking data signal is transmitted from the vehicle body side electronic control unit to the wheel side electronic control unit as a third parking data signal, and the first parking data signal and When the coincidence with the third parking data signal is determined, a transition of the parking brake function is permitted, and when the inconsistency between the first parking data signal and the third parking data signal is determined, the parking brake An electric braking device for a vehicle configured to prohibit function transition. An electric braking device for a vehicle according to claim 2,
Each of the left and right wheels of the vehicle includes the wheel side electronic control unit, and the communication means,
Even if the communication means of the one side wheel among each of the left and right wheels determines a mismatch between the first parking data signal of the one side wheel and the third parking data signal of the one side wheel, When the communication means of the other wheel of each of the left and right wheels determines the coincidence between the first parking data signal of the other wheel and the third parking data signal of the other wheel, An electric braking device for a vehicle configured to allow transition of the parking brake function of a side wheel.