Brake control device for a vehicle

Abstract

Brake control device for a vehicle configured to generate a force to push a friction element (MSB) against a rotary element (KTB) attached to a wheel (WH) of the vehicle via an electric motor (MTR) controlled by a control device (CTL) according to an actuation magnitude (Bpa) of a brake actuation element (BP) of the vehicle, wherein the brake control device comprises: a pressure force sensor (FPA) configured to capture the pressure force as an actual pressure force value (Fpa); and a rotary angle sensor (MKA) configured to detect an actual rotary angle value (Mka) of the electric motor (MTR), where the control unit (CTL) is configured to determine whether an operating state of the pressure force sensor (FPA) is suitable or not; In a case where the operating state of the pressure force sensor (FPA) is suitable, the control device (CTL) is configured to adjust an output of the electric motor (MTR) based on the actual pressure force value (Fpa), to store a correlation (Fpa-Mka) between the actual pressure force value (Fpa) and the actual rotation angle value (Mka), and to generate a conversion calculation map (CMkt, CFpe) based on the correlation (Fpa-Mka); In a case where the operating state of the pressure force sensor (FPA) is determined to be unsuitable, the control unit (CTL) is configured to adjust the output of the electric motor (MTR) based on the actual rotation angle value (Mka) and the conversion calculation characteristic map (CMkt, CFpe), and the control unit (CTL) is configured: to calculate a compressive force estimate (Fpe) based on the actual rotation angle value (Mka) and the conversion calculation characteristic map (CFpe); and to determine, based on a comparison result (hFp) of the actual pressure force value (Fpa) and the pressure force estimate value (Fpe), whether the operating state of the pressure force sensor (FPA) is suitable or not.

Description

TECHNICAL FIELD

[0001] The present invention relates to a brake control device for a vehicle, STATE OF THE ART

[0002] Patent Literature 1 describes: "Even in a case where a stiffness table T0 stored in a RAM 31 at the start of braking and an actual stiffness characteristic of an electric brake caliper 4 (a position-specific pressing force characteristic) that changes according to a braking circumstance such as braking intervals and braking durations do not match, a pressing force command value and a rotational position-specific characteristic (stiffness table) are updated each time a thrust force estimation value is calculated during braking" to "provide an electric brake device capable of ensuring a braking force corresponding to an operation amount of a brake pedal."She describes that as a result, "a deviation between the pressing force command value and a generated pressing force can be reduced, which in other words means that the followability to a pressing force command can be ensured according to the actual state of the stiffness characteristic of the electric brake caliper 4."

[0003] Furthermore, Patent Literature 1 describes that "a current-feed force conversion processing unit 45 calculates an estimated feed force value, which is information regarding a feed force, from a corrected current output from a current correction processing unit 43. The calculation of the estimated feed force value by the current-feed force conversion processing unit 45 is performed based on a motor torque constant and a mechanical efficiency of the caliper 4 obtained in advance by measurement. A feed force information calculation device is realized with this current-feed force conversion processing unit 45.The calculated estimated feed force value is output from the current-feed force conversion processing unit 45 to a stiffness table update unit 46 and a pressure force command motor rotational position command conversion processing unit 37. The stiffness table update unit 46 generates an updated stiffness table, as described later, using the estimated feed force value, which is the information regarding the feed force obtained by the current-feed force conversion processing unit 45, and a corrected motor rotational position obtained by the current correction processing unit 43 at the time the estimated feed force value is calculated, and changes the stiffness table, which is stiffness characteristic data stored in the RAM 31, to the updated stiffness table.That is, the device described in Patent Literature 1 calculates a pressing force (also called pressing force) calculated based on the current.

[0004] The applicant is developing a device that performs direct detection and control instead of acquiring the pressing force (for example, wheel cylinder fluid pressure) by estimation as described in Patent Literature 2. To improve controllability in a region where the pressing force is extremely low, a highly accurate stiffness table (a relationship between a rotation angle of an electric motor and the pressing force, also called a calculation map) is necessary even in a brake control device that directly detects the pressing force. Furthermore, when the pressing force detecting device becomes faulty, appropriate brake control must be ensured. CITATION LISTPATENT LITERATURE Patent literature 1: JP 2011 - 213 201 A Patent literature 2: JP 2015 - 160 607 A

[0005] JP 2003 063 376 A discloses a braking system that determines whether an abnormality in a pressure force sensor has occurred. The document aims to provide measures by which a vehicle driver can be promptly and reliably alerted to an abnormality in the pressure force sensor. SUMMARY OF THE INVENTION TECHNICAL PROBLEMS

[0006] An object of the present invention is to provide a brake control device configured to directly detect a pressing force, in which accuracy of a conversion calculation map between a rotation angle of an electric motor and a pressing force is improved and appropriate brake control can be performed even when a pressing force sensor becomes faulty. SOLVING THE PROBLEMS

[0007] This object is achieved by a brake control device as defined in claim 1.

[0008] A brake control device for a vehicle according to the present invention is configured to generate a force for pressing a friction member (MSB) against a rotating member (KTB) attached to a wheel of the vehicle via an electric motor (MTR) controlled by a controller (CTL) according to an operation amount (Bpa) of a brake operating member (BP) of the vehicle. Furthermore, the brake control device for a vehicle according to the present invention includes a pressing force sensor (FPA) configured to detect the pressing force as an actual pressing force value (Fpa) and a rotation angle sensor (MKA) configured to detect an actual rotation angle value (Mka) of the electric motor (MTR).

[0009] In the brake control device for a vehicle according to the present invention, the control device (CTL) is configured to determine whether an operating state of the pressing force sensor (FPA) is suitable or not; in a case of determining that the operating state of the pressing force sensor (FPA) is suitable, the control device is configured to adjust an output of the electric motor (MTR) based on the actual pressing force value (Fpa), store a correlation (Fpa-Mka) between the actual pressing force value (Fpa) and the actual rotation angle value (Mka), and generate a conversion calculation map (CMkt, CFpe) based on the correlation (Fpa-Mka); and in the case of determining that the operating state of the pressing force sensor (FPA) is not suitable, the control device is configured to adjust the output of the electric motor (MTR) based on the actual rotation angle value (Mka) and the conversion calculation map (CMkt).

[0010] Furthermore, in the brake control device for a vehicle according to the present invention, the control means (CTL) is configured to calculate a pressing force estimated value (Fpe) based on the actual rotation angle value (Mka) and the conversion calculation map (CFpe), and is configured to determine whether the operating state of the pressing force sensor (FPA) is appropriate or not based on a comparison result (hFp) of the actual pressing force value (Fpa) and the pressing force estimated value (Fpe).

[0011] According to the configuration described above, when the operating state of the pressing force sensor FPA is determined to be appropriate, the output of the electric motor MTR is fine-tuned through pressing force control based on the actual pressing force value Fpa, and the relationship (Fpa-Mka characteristic) of the actual pressing force (actual pressing force value) Fpa and the actual rotation angle (actual rotation angle value) Mka is stored, and the conversion calculation maps CMkt, CFpe are generated based on the stored data. That is, the conversion calculation maps CMkt, CFpe are updated from older to newest. Due to this, the control accuracy is improved in a small operation range where a change in the actual pressing force Fpa is small with respect to a change in the brake operation amount Bpa.

[0012] Furthermore, if the operating condition of the pressure force sensor FPA is determined to be unsuitable, the detection value Fpa of the pressure force sensor is not applied for control, and instead, feedback control is performed based on the actual rotation angle Mka and the stored conversion calculation map CMkt to fine-tune the output of the electric motor MTR. Since the conversion calculation maps CMkt and CFpe are sequentially updated whenever the operating condition of the pressure force sensor FPA is determined to be suitable, the influence of wear in the friction element MSB is compensated for, and brake control accuracy is ensured even when the operating condition of the pressure force sensor FPA is unsuitable.

[0013] In addition, the estimated pressure force value Fpe is calculated based on the latest conversion calculation map CFpe, and the accuracy of the operating state of the pressure force sensor FPA is determined based on the comparison result (for example, a deviation hFp) of the estimated pressure force value Fpe and the actual pressure force value Fpa. As described above, since the accuracy of the conversion calculation map CFpe is ensured, appropriate detection of sensor errors is enabled. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall configuration diagram of a vehicle to which a brake control device for a vehicle according to the present invention is mounted. Fig. 2 shows a functional block diagram to explain processes in a control device. Fig. 3 shows a circuit diagram to explain an electric motor and an associated drive circuit. Fig. 4 shows a flowchart for explaining processes in a suitability determination block and processes in a conversion calculation block. Fig. 5A and Fig. 5B show characteristic diagrams for explaining a generation of conversion calculation maps CMkt, CFpe. Fig. 6A and Fig. 6B are time charts for explaining operations and effects of the brake control apparatus for a vehicle according to the present invention. DESCRIPTION OF EMBODIMENTS <Gesamtkonfiguration einer Bremssteuerungsvorrichtung für ein Fahrzeug gemäß der vorliegenden Erfindung>

[0014] Brake control devices BCS, BCR according to the present invention are described below with reference to an overall configuration diagram of Fig. 1. A difference between the brake control device BCR and the brake control device BCS is whether a parking brake mechanism PKB is provided or not. The brake control device BCR is provided with the parking brake mechanism PKB, and the brake control device BCS is not provided with the parking brake mechanism PKB. Generally, the brake control device BCS is a device for a front wheel WHf, and the brake control device BCR is a device for a rear wheel WHr. In the following description, elements, calculation processes, and signals assigned the same reference numeral have the same function, so overlapping descriptions may be omitted.

[0015] In a vehicle equipped with the brake control devices BCS, BCR, a brake operating element BP, an operating amount sensor BPA, a control device CTL, a master cylinder MCL, a stroke simulator SSM, a simulator cut-off valve VSM, a pressurizing unit KAU, a switching valve VKR, a master cylinder pipe HMC, a wheel cylinder pipe HWC, and a pressurizing cylinder pipe HKC are provided. Each wheel WH of the vehicle is equipped with a brake caliper CRP, a wheel cylinder WC, a rotary element KTB, and friction elements MSB. Furthermore, the vehicle is equipped with a vehicle speed acquisition device VXA and a parking switch SW.

[0016] The brake operating member (e.g., a brake pedal) BP is a member operated by a driver to decelerate the vehicle. When the brake operating member BP is operated, the braking torque of each wheel WH is adjusted, and braking force is generated in each wheel WH. Specifically, each of the wheels WH of the vehicle has the rotating member (e.g., a brake disk) KTB attached thereto. The brake caliper CRP is arranged so that the rotating member KTB is sandwiched therebetween. Furthermore, the brake caliper CRP is provided with the wheel cylinder WC. A pressure of brake fluid in the wheel cylinder WC is increased, thereby pressing the friction members (e.g., brake pads) MSB against the rotating member KTB. The rotating member KTB and the wheel WH are fixed via a fixing shaft DSF to rotate integrally.Due to this, a friction force generated when the friction elements MSB press against the rotating element KTB generates the braking torque (braking force) in the wheel WH.

[0017] The operation amount sensor (operation amount acquisition means) BPA is provided in the brake operating member BP. An operation amount Bpa of the brake operating member BP by the driver is detected (acquired) by the operation amount sensor BPA. Specifically, a fluid pressure sensor configured to detect a pressure in the master cylinder MCL, an operation displacement sensor configured to detect an operation displacement of the brake operating member BP, and / or an operation force sensor configured to detect an operation force on the brake operating member BP are used as the operation amount sensor BPA. That is, the operation amount sensor BPA is a collective expression of the master cylinder fluid pressure sensor, the operation displacement sensor, and the operation force sensor.Thus, the brake application amount Bpa is detected and determined based on a fluid pressure of the master cylinder MCL, an application displacement of the brake application element BP, and / or an application force of the brake application element BP. The application amount Bpa is supplied to the control device CTL.

[0018] The control device (also referred to as control means or controller) CTL is configured from an electrical circuit board on which a microprocessor and the like are implemented, and a control algorithm programmed into the microprocessor. The control device CTL is configured to control the pressurizing unit KAU, the shut-off valve VSM, and the switching valve VKR, described below, based on the brake application amount Bpa. Specifically, signals for controlling the electric motor MTR, the shut-off valve VSM, and the switching valve VKR are calculated based on a control algorithm programmed into the control device CTL and output from the control device CTL.

[0019] When the actuation amount Bpa becomes equal to or greater than a predetermined value bp0, the control device CTL outputs a drive signal Vsm to open the shutoff valve VSM and also outputs a drive signal Vkr to the switching valve VKR to connect the pressurizing cylinder pipe HKC and the wheel cylinder pipe HWC. In this case, the master cylinder MCL is connected to the simulator SSM, and the pressurizing cylinder KCL of the pressurizing unit KAU is connected to the wheel cylinder WC. Here, the value bp0 is a preset value corresponding to a "play" of the brake operating member BP.

[0020] The control device CTL calculates drive signals (Su1, etc., to be described later) for driving the electric motor MTR based on the operation amount Bpa, a rotation angle Mka, and a pressing force Fpa, and outputs them to a drive circuit DRV. Here, the brake operation amount Bpa is a value actually detected by the brake operation amount sensor BPA, the actual rotation angle Mka is a value actually detected by the rotation angle sensor MKA, and the actual pressing force Fpa is a value actually detected by the pressing force sensor FPA. The pressure in the brake fluid in the wheel cylinder WC is controlled (maintained, increased, or decreased) by the pressurizing unit KAU driven by the electric motor MTR.

[0021] The master cylinder MCL is connected to the brake actuator BP via a piston rod PRD. The operating force (brake pedal force) of the brake actuator BP is converted into brake fluid pressure by the master cylinder MCL. The master cylinder pipe HMC is connected to the master cylinder MCL, and when the brake actuator BP is operated, the brake fluid is expelled (pumped) from the master cylinder MCL to the master cylinder pipe HMC. The master cylinder pipe HMC is a fluid passage connecting the master cylinder MCL and the shift valve VKR.

[0022] The stroke simulator (simply referred to as a simulator) SSM is provided to generate the operating force in the brake operating member BP. The simulator cut-off valve (simply referred to as a cut-off valve) VSM is provided between a fluid pressure chamber in the master cylinder MCL and the simulator SSM. The cut-off valve VSM is a two-position electromagnetic valve with an open position and a closed position. When the cut-off valve VSM is in the open position, the master cylinder MCL and the simulator SSM are in a connected state, and when the cut-off valve VSM is in the closed position, the master cylinder MCL and the simulator SSM are in a cut-off (non-connected) state. The cut-off valve VSM is controlled by the drive signal Vsm from the control device CTL.A normally closed electromagnetic valve (NC valve) can be used as the VSM shut-off valve.

[0023] A piston and an elastic body (e.g., a compression spring) are provided within the simulator SSM. The brake fluid is moved from the master cylinder MCL to the simulator SSM, and the piston is pushed by the inflowing brake fluid. The elastic body applies a force to the piston in a direction that prevents the inflow of brake fluid. The elastic body generates the operating force (e.g., the brake pedal force) when the brake operating element BP is operated. <<Druckbeaufschlagungseinheit KAU> >

[0024] The pressurizing unit KAU discharges (pumps) the brake fluid to the pressurizing cylinder pipe HKC using the electric motor MTR as its power source. Furthermore, the pressurizing unit KAU presses (presses) the friction elements MSB against the rotating element KTB with the pumped brake fluid to provide the braking torque (braking force) to the wheel WH. In other words, the pressurizing unit KAU generates the force of pressing the friction elements MSB against the rotating element KTB using the electric motor MTR.

[0025] The pressurization unit KAU is configured from the electric motor MTR, the drive circuit DRV, a power transmission mechanism DDK, a pressurization rod KRD, a pressurization cylinder KCL, a pressurization piston PKC and the pressure force sensor FPA.

[0026] The electric motor MTR is the power source for the pressurizing cylinder KCL (which is part of the pressurizing unit KAU) to adjust (increase or decrease) the brake fluid pressure in the wheel cylinder WC. For example, a brushless three-phase motor can be used as the electric motor MTR. The electric motor MTR has three coils CLU, CLV, and CLW and is driven by the drive circuit DRV. The electric motor MTR is equipped with a rotation angle sensor (rotation angle acquisition device) MKA for detecting (acquiring) the rotor position (rotation angle) Mka of the electric motor MTR. The rotation angle Mka is input to the control device CTL.

[0027] The drive circuit DRV is an electrical circuit board on which switching elements (power semiconductor devices) for driving the electric motor MTR are mounted. Specifically, a bridge circuit BRG is formed on the drive circuit DRV, and an electrical conduction state to the electric motor MTR is controlled based on the drive signal (Su1, etc.). The drive circuit DRV is provided with an electrical conduction quantity acquisition device (a current sensor) IMA for acquiring (detecting) an actual electrical conduction quantity (electrical conduction quantity at each phase) Ima to the electric motor MTR. The electrical conduction quantity (detection value) Ima of each phase is input to the control device CTL.

[0028] The power transmission mechanism DDK decelerates the rotational power of the electric motor MTR, converts it into linear power, and outputs it to the pressure rod KRD. Specifically, the power transmission mechanism DDK is equipped with a reduction gear (not shown), and the rotational power from the electric motor MTR is decelerated and output to a worm gear (not shown). The worm gear then converts the rotational power into linear power for the pressure rod KRD. This means that the power transmission mechanism DDK is a rotation-to-linear conversion mechanism.

[0029] The pressurizing rod KRD has the pressurizing piston PKC attached thereto. The pressurizing piston PKC is inserted into an inner opening of the pressurizing cylinder KCL, and a combination of a piston and a cylinder is formed thereby. Specifically, a sealing member (not illustrated) is provided on an outer periphery of the pressurizing piston PKC, and fluid sealing with the inner opening (inner wall) of the pressurizing cylinder KCL is ensured. That is, a fluid chamber Rkc (referred to as "pressurizing chamber Rkc"), which is defined by the pressurizing cylinder KCL and the pressurizing piston PKC and into which the brake fluid is filled, is thereby formed.

[0030] In the pressurizing cylinder KCL, the volume of the pressurizing chamber Rkc is changed by moving the pressurizing piston PKC in a center-axis direction. This volume change moves the brake fluid between the pressurizing cylinder KCL and the wheel cylinder WC through the brake pipes (tubes) HKC, HWC. The fluid pressure in each wheel cylinder WC is adjusted by the input and output of brake fluid to and from the pressurizing cylinder KCL, thereby adjusting the force by which the friction elements MSB press against the rotating element KTB (pressure force).

[0031] For example, as the pressure force sensor FPA, a fluid pressure sensor configured to acquire (detect) a fluid pressure Fpa of the pressurizing chamber Rkc is provided in the pressurizing unit KAU (specifically, the pressurizing cylinder KCL). The fluid pressure sensor (corresponding to the pressure force sensor) FPA is fixed to the pressurizing cylinder KCL and is configured integrally with the pressurizing unit KAU. A detection value Fpa of the pressure force (i.e., the fluid pressure in the pressurizing chamber Rkc) is input to the control device (control means) CTL. As described above, the pressurizing unit KAU has been set forth.

[0032] The switching valve VKR switches between a state in which the wheel cylinder WC is connected to the master cylinder MCL and a state in which the wheel cylinder WC is connected to the pressurizing cylinder KCL. The switching valve VKR is controlled based on the drive signal Vkr from the control device CTL. Specifically, when no braking operation is performed (Bpa < bp0), the wheel cylinder pipe HWC is in the connected state with the master cylinder pipe HMC through the switching valve VKR, and is in the non-connected (cut-off) state with the pressurizing cylinder pipe HKC. Here, the wheel cylinder pipe HWC is a passage connected to the wheel cylinder WC.When the brake operation is performed (that is, when a state Bpa ≥ bp0 is realized), the switching valve VKR is energized based on the drive signal Vkr, the connection between the wheel cylinder pipe HWC and the master cylinder pipe HMC is cut off, and the wheel cylinder pipe HWC and the pressurizing cylinder pipe HKC are put into the connected state.

[0033] The brake caliper (which may simply be referred to as a caliper) CRP is provided in the wheel WH, supplies the braking torque to the wheel WH, and causes the braking force to be generated therein. A floating type brake caliper can be applied as the brake caliper CRP. The brake caliper CRP is configured such that the rotating element (e.g., a brake disc) KTB is sandwiched between two friction elements (e.g., brake pads) MSB. The wheel cylinder WC is provided in the brake caliper CRP. The fluid pressure in the wheel cylinder WC is adjusted, causing the piston in the wheel cylinder WC to move (advance or retract) with respect to the rotating element KTB. This movement of the piston presses the friction elements MSB against the rotating element KTB, thereby generating the pressing force Fpa.

[0034] The vehicle speed acquisition means VXA acquires a traveling speed Vxa of the vehicle. The vehicle speed Vxa is calculated based on an output rotational speed of a transmission or a change in vehicle position detected by a global positioning system. Furthermore, the vehicle speed Vxa is calculated based on a detection result (a wheel speed) of a wheel speed sensor VWA (not shown) provided in the wheel WH. Furthermore, a result (a traveling speed) Vxa calculated in another device can be acquired through a communication bus. Thus, the vehicle speed acquisition means VXA is a collective expression for the above-described acquisition means (the wheel speed sensor VWA, etc.). The vehicle speed Vxa is input to the control means CTL.

[0035] A parking brake switch (which may simply be referred to as a parking switch) SW is a switch operated by the driver and outputs an on or off signal (parking signal) Swa to the control device CTL. This means that the driver instructs the driver to apply or release the parking brake to maintain a stopped state of the vehicle by operating the parking switch SW. Specifically, the application of the parking brake is instructed with an on state (ON) of the parking signal Swa, and the release of the parking brake is instructed with an off state (OFF) of the parking signal Swa. The parking signal Swa is input to the control device CTL.

[0036] The brake control device BCR is equipped with the parking brake mechanism PKB. The parking brake mechanism PKB (which may also be referred to as a locking mechanism) performs a braking function (so-called parking brake) for maintaining a stopped state of the vehicle, thus it is configured to lock the movement of the electric motor MTR from rotating in a reverse direction. The locking mechanism PKB restricts (limits) the movement of the friction elements MSB in a direction that separates them from the rotating element KTB, thereby maintaining a depressed state of the rotating element KTB by the friction elements MSB. A ratchet mechanism (a mechanism that restricts an operating direction to a single direction) can be used as the locking mechanism PKB.Furthermore, a self-locking screw mechanism (that is, having a reversing efficiency of “0”), a worm gear, and the like may be applied.

[0037] The locking mechanism PKB is omitted from the brake control device BCS. The wheel on which the brake control device BCS is not provided with the locking mechanism PKB is referred to as a "free wheel." Furthermore, the wheel on which the brake control device BCR with the locking mechanism PKB is provided is referred to as a "restricted wheel." In a general vehicle, the front wheel WHf is the free wheel, and the rear wheel WHr is the restricted wheel.

[0038] Fig. Figure 1 shows, as an example, a configuration of a disc-type brake device (disc brake). In this case, the friction elements MSB are brake pads, and the rotating element KTB is a brake disc. Instead of the disc-type brake device, a drum-type brake device (drum brake) can be used. In the case of the drum brake, a brake drum is used instead of the brake caliper CRP. Furthermore, the friction elements MSB are brake shoes, and the rotating element KTB is the brake drum.

[0039] Furthermore, according to Fig. 1. The output of the electric motor MTR is converted into the force by which the friction elements MSB press the rotating element KTB (the pressing force) via the brake fluid. However, a configuration can be adopted in which the friction elements MSB press the rotating element KTB directly without the mediation of the brake fluid. In this configuration, the pressurizing unit KAU is directly attached to the brake caliper CRP instead of the wheel cylinder WC. Furthermore, the friction elements MSB are pressed against the rotating element KTB by the pressurizing piston PKC of the pressurizing unit KAU. The pressing force sensor FPA (the round-clamp pressing force sensor FPA) is arranged between the power transmission mechanism DDK (e.g., the reduction gear, the screw mechanism) and the pressurizing cylinder KCL to obtain the actual pressing force Fpa.In this configuration, the brake fluid is not used, so the pressurizing chamber Rkc is not formed. <Prozesse in der Steuerungseinrichtung CTL>

[0040] With reference to a functional block diagram of Fig. Figure 2 describes processes in the control device (control means) CTL. An example is described in which the brushless motor is used as the electric motor MTR.

[0041] The control device CTL calculates signals Su1, Su2, Sv1, Sv2, Sw1, Sw2 (which may be simply referred to as "Su1 to Sw2") for driving switching elements SU1, SU2, SV1, SV2, SW1, SW2 (which may be simply referred to as "SU1 to SW2") of the drive circuit DRV, which will be described later. The control device CTL is configured from a target pressing force calculation block FPT, an instruction electric line size calculation block IMS, an analog-to-digital conversion processing block ADH, a pressing force control block FFB, a conversion calculation block HNK, a rotation angle control block MFB, a suitability determination block HNT, a composite electric line size calculation block IGH, a parking electric line size calculation block IPK, a target electric line size calculation block IMT, and a switching control block SWT.

[0042] In the target pressing force calculation block FPT, a target pressing force Fpt is calculated based on the brake operation amount Bpa and a calculation map CFpt. Here, the target pressing force Fpt is a target value of the fluid pressure (corresponding to the pressing force) generated by the pressurizing unit KAU. Specifically, in the calculation map CFpt, the target pressing force Fpt is calculated as "0 (zero)" in a range where the brake operation amount Bpa is equal to or greater than "0 (zero, corresponding to a case where the brake operation is not performed)" to less than a predetermined value bp0, and the target pressing force Fpt is calculated to monotonously increase from zero according to an increase in the operation amount Bpa when the operation amount Bpa is equal to or greater than the predetermined value bp0.The predetermined value bp0 is a value that corresponds to the “play” of the brake actuating element BP.

[0043] In the command electric conduction quantity calculation block IMS, a command electric conduction quantity Ims for the electric motor MTR driving the pressurizing unit KAU (a target value of the electric conduction quantity for controlling the electric motor MTR) is calculated based on the target pressing force Fpt and preset calculation characteristics (calculation maps) CIup, CIdw. The calculation map for the command electric conduction quantity Ims is configured from two characteristics by considering the influence of hysteresis by the power transmission mechanism DDK and the like: the CIup characteristic for a case where the target pressing force Fpt increases, and the CIdw characteristic for a case where the target pressing force Fpt decreases.

[0044] Here, the "electric conduction quantity" is a state quantity (state variable) for controlling the output torque of the electric motor MTR. Since the electric motor MTR outputs torque that is substantially proportional to current, a current command value of the electric motor MTR can be used as the command value (electric conduction quantity). Furthermore, since the current increases as a result of an increase in the supplied voltage to the electric motor MTR, a supplied voltage can be used as the command electrical conduction quantity. Furthermore, since the supplied voltage can be modulated with a duty cycle in pulse width modulation, this duty cycle (ratio of an electrically conducting time in one cycle) can be used as the electrical conduction quantity.

[0045] In a case where an analog-type sensor is used as the pressure force sensor FPA, a detection result (analog value) of the pressure force sensor FPA is converted into a digital value in the analog-to-digital conversion processing block ADH. That is, a so-called analog-to-digital conversion (also called AD conversion) is performed in the analog-to-digital conversion processing block ADH. The converted actual pressure force Fpa is read by the control device CTL. At this time, a resolution of the pressure force Fpa (least significant bit, LSB) is determined according to a bit number of the conversion device ADH. For example, in a case where the analog-to-digital conversion processing block ADH is 10 bits, an output of the pressure force sensor FPA is input to the control device CTL as a digital value divided by 2 to the power of 10 within a dynamic range thereof. <<Druckkraftregelungsblock FFB> >

[0046] In the pressure force control block FFB, a command value of the pressure force (for example, a command fluid pressure) Fpt and an actual value of the pressure force (detection value) Fpa are used as control state variables, and a compensation electrical conduction quantity Ifp of the electric motor MTR is calculated based on them. In some cases, an error in the pressure force may occur by simply controlling based on the command electrical conduction quantity Ims. Based on this, the pressure force control block FFB calculates an electrical compensation conduction quantity to compensate for this error and fine-tune the output of the electric motor MTR. The pressure force control block FFB is configured from a comparison calculation block and a block for calculating an electrical pressure force compensation force conduction quantity IPF.

[0047] The comparison calculation compares the target value Fpt and an actual value Fpa of the pressure force. The actual value Fpa of the pressure force is a detection value acquired (detected) by the pressure force sensor FPA (e.g., a fluid pressure sensor). In the comparison calculation, a deviation (pressure force deviation) eFp between the target pressure force (the target value) Fpt and the actual pressure force (the detection value) Fpa is calculated. The pressure force deviation eFp (which is a controlled variable and is related to a physical quantity "pressure") is entered into the block for calculating an electrical pressure force compensation line variable IPF.

[0048] The block for calculating the electrical pressure force compensation line quantity IPF comprises a proportional element block, a differentiating element block, and an integrating element block. In the proportional element block, a proportional gain Kpp is multiplied by the pressure force deviation eFp to calculate a proportional element of the pressure force deviation eFp. In the differentiating element block, the pressure force deviation eFp is differentiated, by which a derivative gain Kpd is multiplied to calculate a differentiating element of the pressure force deviation eFp. In the integrating element block, the pressure force deviation eFp is integrated, by which an integrating gain Kpi ​​is multiplied to calculate an integrating element of the pressure force deviation eFp. The electrical pressure force compensation line quantity Ifp is then calculated by adding the proportional element, the differentiating element, and the integrating element.That is, in the electric pressure force compensation line quantity calculation block IPF, a so-called pressure force-based PID control loop is formed, which is based on a comparison result eFp of the target pressure force Fpt and the actual pressure force Fpa, so that the actual pressure force (the detection value) Fpa matches the target pressure force (the target value) Fpt of the pressure force (that is, the deviation eFp approaches "0 (zero)"). Based on this, the output of the electric motor MTR is adjusted. The pressure force control block FFB has been described above.

[0049] In the conversion calculation block HNK, a conversion from the pressing force to the rotation angle and a conversion from the rotation angle to the pressing force are performed based on the correlation of the pressing force by the pressurizing unit KAU and the rotation angle of the electric motor MTR. This is because the output of the electric motor MTR is converted to the output of the pressurizing unit KAU through known specifications and the like of the power transmission mechanism DDK.

[0050] In the conversion calculation block HNK, the target rotation angle Mkt is calculated based on the target thrust force Fpt and the conversion calculation characteristic (conversion calculation map) CMkt. The target rotation angle Mkt is a target value of the rotation angle of the electric motor MTR. Specifically, it is calculated to increase monotonically with an "upward convex" characteristic of "0 (zero)" in association with an increase in the target thrust force Fpt, according to the conversion calculation map CMkt for the target rotation angle Mkt. The target rotation angle Mkt is calculated as a value corresponding to the target thrust force Fpt.The calculation characteristic CMkt for the target rotation angle Mkt is determined based on stiffnesses (spring constants) of the brake caliper CRP, the friction elements MSB and the like, and specifications of the wheel cylinder WC and the pressurizing cylinder KCL (pressure receiving areas) and the like, and is sequentially updated by a method described later on the basis thereof.

[0051] In the conversion calculation block HNK, an estimated thrust force Fpe is calculated based on the actual rotation angle Mka and the conversion calculation map CFpe. The estimated thrust force Fpe is an estimated value for the thrust force converted from the rotation angle detection value Mka in the electric motor MTR. Specifically, it is calculated to increase monotonically with a "downward convex" characteristic of "0 (zero)" in association with an increase in the actual rotation angle Mka, according to the conversion calculation map CFpe for the estimated thrust force Fpe.Similar to the conversion calculation map CMkt for the target rotation angle Mkt, the conversion calculation map CFpe for the estimated pressing force Fpe is set based on stiffnesses (spring constants) of the brake caliper CRP, the friction elements MSB and the like, as well as the specifications of the wheel cylinder WC and the pressurizing cylinder KCL (the pressure receiving surfaces) and the like, and is sequentially updated based thereon.

[0052] The conversion calculation block HNK includes an approximate function calculation block KNJ. In the approximate function calculation block KNJ, approximate functions (approximate functions Knj, Kni, etc.) that approximate a correlation (Fpa-Mka characteristic) of the actual pressing force Fpa and the actual rotation angle Mka are calculated based on the actual pressing force Fpa and the actual rotation angle Mka. The conversion calculation maps CMkt and CFpe are generated based on the approximate functions Knj and Kni and are updated from the old conversion calculation maps from the past to the most recent. The approximate function Knj (target rotation angle map CMkt) and the approximate function Kni (estimated rotation force map CFpe) are in an inverse function relationship. The processes in the approximate function calculation block KNJ are described below. <<Drehwinkelregelungsblock MFB> >

[0053] In the rotation angle control block MFB, the target rotation angle value (target rotation angle) Mkt and the actual rotation angle value (detection value) Mka are used as control state variables, and an electrical compensation line quantity Imk of the electric motor MTR is calculated based on them. Since a pressing force and a motor rotation angle have a correlated relationship due to the stiffness of the brake caliper CRP and the like, and the dimension of the pressurizing cylinder KCL and the like, the rotation angle control block MFB complements the pressing force control. That is, the rotation angle control block MFB calculates an electrical compensation line quantity for finely adjusting the output of the electric motor MTR, similar to the pressing force control block FFB. The rotation angle control block MFB is configured from a comparison calculation block and a block for calculating an electrical pressure angle compensation line quantity IMK.

[0054] The comparison calculation compares the target value (target angle of rotation) Mkt and the actual value (detection value) Mka of the angle of rotation of the electric motor MTR. The actual value Mka of the angle of rotation is a detection value of the angle of rotation (actual angle of rotation) acquired (detected) by the angle of rotation sensor MKA. For example, the comparison calculation calculates a deviation (angle of rotation deviation) eMk between the target angle of rotation (target value) Mkt and the actual angle of rotation (detection value) Mka. The angle of rotation deviation eMk (controlled variable) is entered into the block for calculating the electrical angle of rotation compensation line variable IMK.

[0055] The block for calculating the electrical angle compensation line quantity IMK comprises a proportional element block, a differentiating element block, and an integrating element block. In the proportional element block, a proportional gain Kmp is multiplied by the angle deviation eMk to calculate a proportional element of the angle deviation eMk. In the differentiating element block, the angle deviation eMk is differentiated, by which a differential gain Kmd is multiplied to calculate a differentiating element of the angle deviation eMk. In the integrating element block, the angle deviation eMk is integrated, by which an integrating gain Kmi is multiplied to calculate an integrating element of the angle deviation eMk. The electrical angle compensation line quantity Imk is then calculated by adding the proportional element, the differentiating element, and the integrating element.This means that in the block for calculating the electric angle compensation line quantity IMK, a so-called PID control loop is formed based on the angle of rotation. This control loop is based on the comparison result eMk of the target angle of rotation Mkt and the actual angle of rotation Mka, so that the actual angle of rotation (detection value) Mka coincides with the target angle of rotation (set value) Mkt (i.e., the deviation eMk approaches "0 (zero)"). Based on this, the output of the electric motor MTR is adjusted. The angle of rotation control block MFB was described above.

[0056] In the suitability determination block HNT, a determination of "suitable or not" is made with respect to the detection signal (actual pressing force value) Fpa of the pressing force sensor FPA. In a case where the actual pressing force Fpa is suitable (i.e., a case where the pressing force sensor FPA is operated appropriately), "0 (zero)" is output as a determination result (determination flag) Hnt, and in a case where the actual pressing force Fpa is not suitable (i.e., a case where the pressing force sensor FPA is not operated appropriately), "1" is output as the determination flag Hnt.

[0057] The determination of whether the compression force sensor FPA is suitable is made based on a comparison of the estimated value (estimated compression force) Fpe that has converted the actual rotation angle Mka into the compression force and the actual value Fpa of the compression force. First, the actual rotation angle Mka is converted into the estimated compression force Fpe based on the conversion calculation characteristic CFpe to be described later. The deviation hFp (absolute value) between the actual compression force Fpa and the estimated compression force Fpe is calculated, and "Hnt = 0 (positive suitability determination)" is output in a case where the deviation hFp is less than a predetermined value hfx. Conversely, "Hnt = 1 (negative suitability determination)" is output in a case where the deviation hFp is equal to or greater than the predetermined value hfx.The threshold value hfx used in the suitability determination is set to a value smaller than a lower value (predetermined value) fps, which will be described later. <<Block zur Berechnung einer zusammengesetzten elektrischen Kompensationsleitungsgröße IGH> >

[0058] In the composite electrical compensation line size calculation block IGH, the electrical pressure force compensation line size Ifp and the electrical rotation angle compensation line size Imk are combined to calculate a composite electrical compensation line size Igh, which is a final electrical compensation line size. As described above, the electrical pressure force compensation line size Ifp and the electrical rotation angle compensation line size Imk are correlated. Due to this, the electrical pressure force compensation line size Ifp is adjusted by a pressure force coefficient Kfp, and the electrical rotation angle compensation line size Imk is adjusted by a rotation angle coefficient Kmk, as a result of which the composite electrical compensation line size Igh is calculated.

[0059] Furthermore, in the composite electrical compensation line size calculation block IGH, the composite electrical compensation line size Igh is determined based on the determination result (determination flag indicating the behavior) Hnt in the suitability determination block HNT. First, a case is described where the determination flag Hnt indicates that "the pressure force sensor FPA is suitable (Hnt = 0)."

[0060] In the composite electrical compensation line size calculation block IGH, a compression force coefficient Kfp for correcting the compression force compensation line size Ifp is calculated based on the target compression force Fpt and a calculation characteristic (calculation map) CKfp of the compression force coefficient. Specifically, in a range where the target compression force Fpt is equal to or greater than "0 (zero)" and less than a lower value fps (under a condition of "0 ≤ Fpt < fps"), the compression force coefficient Kfp is calculated as "0 (zero)". In a range where the target compression force Fpt is equal to or greater than the lower value fps and less than an upper value fpu (under a condition of "fps ≤ Fpt <fpu“), wird der Druckkraftkoeffizient Kfp derart berechnet, dass er sich entsprechend einer Erhöhung der Soll-Druckkraft Fpt monoton von „0“ auf „1“ erhöht.Furthermore, in a case where the target pressing force Fpt is equal to or greater than the upper value fpu (under a condition of "Fpt ≥ fpu"), the pressing force coefficient Kfp is calculated as "1." Where, the lower value fps and the upper value fpu are predetermined values ​​(threshold values) set in advance, and the upper value fpu is a value equal to or greater than the lower value fps. For example, for a smooth transition of pressing force control (for example, transition from control prohibition to control execution), the upper value fpu may be set to a value greater than the lower value by a predetermined value fp0.

[0061] Similarly, in the composite electrical compensation line size calculation block IGH, a rotation angle coefficient Kmk for correcting the electrical rotation angle compensation line size Imk is calculated based on the target pressure force Fpt and a calculation characteristic (calculation map) CKmk of the rotation angle coefficient. Specifically, in the range where the target pressure force Fpt is equal to or greater than "0 (zero)" and less than the lower value fps (under the condition of "0 ≤ Fpt < fps"), the rotation angle coefficient Kmk is calculated as "1". In the range where the target pressure force Fpt is equal to or greater than the lower value fps and smaller than the upper value fpu (under the condition of “fps ≤ Fpt < fpu”), the rotation angle coefficient Kmk is calculated to monotonously decrease from “1” to “0” according to the increase of the target pressure force Fpt.Furthermore, in the case where the target pressing force Fpt is equal to or greater than the upper value fpu (under the condition of "Fpt ≥ fpu"), the rotation angle coefficient Kmk is calculated as "0 (zero)". Similar to the above, the lower value fps and the upper value fpu are predetermined values ​​(threshold values) set in advance, and the upper value fpu is a value equal to or greater than the lower value fps (the lower value fps is a value equal to or less than the upper value fpu). For example, the upper value fpu may be set to a value greater than the lower value fps by the predetermined value fp0 for a smooth transition of the rotation angle control (for example, a transition from a control execution to a control prohibition). Here, a relationship between the pressing force coefficient Kfp and the rotation angle coefficient Kmk is set to a total of "1" (Kfp + Kmk = 1).

[0062] Furthermore, in the composite electrical compensation line size calculation block IGH, the electrical compression force compensation line size Ifp and the electrical rotation angle compensation line size Imk are combined based on the compression force coefficient Kfp and the rotation angle coefficient Kmk to calculate the electrical composite compensation line size Igh as the final result. That is, in the calculation of the composite electrical compensation line size, the degree of influence (also referred to as a contribution) of the electrical compression force compensation line size Ifp is considered by the compression force coefficient Kfp, and the degree of influence of the electrical rotation angle compensation line size Imk is considered by the rotation angle coefficient Kmk.Specifically, the composite electrical compensation line size Igh is calculated by adding "a value at which the compressive force coefficient (degree of influence of the compressive force) Kfp is multiplied by the compressive force compensation line size Ifp" and "a value at which the rotation angle coefficient (degree of influence of the rotation angle) Kmk is multiplied by the rotation angle compensation line size Imk" (Igh = Kfp Ifp + (Kmk Imk)). For example, in the composite electrical compensation line size Igh, in a case of "Kfp = 0.3 and Kmk = 0.7", the degree of influence of the compressive force compensation line size Ifp is 30% and the degree of influence of the rotation angle compensation line size Imk is 70%.

[0063] In the case where the target thrust force Fpt is small and "0 < Fpt < fps" is satisfied, "Kfp = 0 and Kmk = 1 (where the contribution rate of the rotation angle compensation electric line quantity Imk is 100%)" is calculated, so the thrust force compensation electric line quantity Ifp is not applied in the calculation of the composite electrical compensation electric line quantity Igh, and only the rotation angle compensation electric line quantity Imk is applied therein. In the control, the contribution rate of the actual thrust force Fpa is set to zero, and the contribution rate becomes entirely that of the rotation angle Mka. That is, the thrust force control is suspended and only the rotation angle control is performed.

[0064] In the case where the target pressure force Fpt becomes relatively large and “fps ≤Fpt <fpu“ erfüllt ist, wird der Drehwinkelkoeffizient Kmk derart berechnet, dass er von „1“ verringert wird und der Druckkraftkoeffizient Kfp berechnet wird, indem er von „0“ entsprechend der Erhöhung der Soll-Druckkraft Fpt erhöht wird. Aufgrund davon wird die zusammengesetzte elektrische Kompensationsleitungsgröße Igh berechnet, wobei die Grade des Einflusses der elektrischen Drehwinkelkompensationsleitungsgröße Imk (das heißt der Drehwinkel Mka) und der elektrischen Druckkraftkompensationsleitungsgröße Ifp (das heißt der Ist-Druckkraft Fpa) unter Verwendung der Gewichtungskoeffizienten Kfp, Kmk berücksichtigt werden. Das heißt, dass sowohl die Druckkraftregelung als auch die Drehwinkelregelung ausgeführt werden.

[0065] In the case where the target thrust force Fpt is relatively large and "Fpt ≥ fpu" is satisfied, "Kfp = 1, Kmk = 0 (where the contribution rate of the thrust force compensation electric line quantity Ifp is 100%)" are calculated, so that the rotation angle compensation electric line quantity Imk is not applied in the calculation of the composite electrical compensation electric line quantity Igh, and only the thrust force compensation electric line quantity Ifp is applied therein. In the control, the contribution rate of the rotation angle Mka is set to zero, and the contribution rate becomes entirely that of the actual thrust force Fpa. That is, the rotation angle control is prohibited and only the thrust force control is performed.

[0066] As described above, two control loops are adjusted based on the target pressing force Fpt, and only the control loop related to the pressing force (brake fluid pressure) is activated when the target pressing force Fpt is large to ensure matching accuracy of the pressing force amounts. In contrast, when the target pressing force Fpt is small, only the control loop related to the rotation angle is activated, and the detected pressing force Fpa is not applied in the control. Due to this, smooth control with high resolution of the pressing force can be performed. In addition, since the coefficients Kfp, Kmk are gradually changed according to the changes in the target pressing force Fpt, mutual transition of the two controls can be smoothly performed.

[0067] The following describes a case where the determination flag Hnt indicates that "the compression force sensor FPA is not suitable (Hnt = 1)." In the case where the compression force sensor is not operated properly, the compression force coefficient Kfp is calculated as "0 (zero)" based on a calculation characteristic (map) CKfn of the compression force coefficient. Furthermore, the rotation angle coefficient Kmk is calculated as "1" based on a calculation characteristic (map) CKmn of the rotation angle coefficient. That is, in the case where the compression force sensor FPA is not operating properly, the compression force compensation electric line quantity Ifp is not applied in the calculation of the composite compensation electric line quantity Igh, and the rotation angle compensation electric line quantity Imk is output as the composite compensation electric line quantity Igh.In other words, the pressure force control is inhibited and only the angle of rotation control is carried out.

[0068] Since the target pressing force Fpt is calculated based on the brake application amount Bpa, the brake application amount Bpa can be used instead of the target pressing force Fpt in the characteristic curves to calculate the respective coefficients Kfp and Kmk. Here, the brake application amount Bpa and the target pressing force Fpt can each be referred to as the "operation amount corresponding value." This means that the coefficients Kfp and Kmk are calculated based on the operation amount corresponding values. The block for calculating the composite electrical compensation line size IGH has been described above.

[0069] In the parking electric line quantity calculation block IPK, a parking electric line quantity Ipk (an electric line quantity for the electric motor MTR) and a solenoid electric line command Iso (electric line signal for a solenoid SOL) for controlling the parking brake are calculated based on the vehicle speed Vxa, the parking signal Swa, the actual pressing force Fpa, and the actual motor rotation angle Mka. The parking electric line quantity Ipk is a target value of the electric line quantity of the electric motor MTR for parking brake control and is input to the target electric line quantity calculation block IMT. Furthermore, the solenoid actuator (which may be simply referred to as a solenoid) SOL is driven by the solenoid electric line command Iso.

[0070] In the parking electric line quantity IPK calculation block, a timer is started when the parking signal Swa from the parking switch SW transitions from off to on after the vehicle is stopped (in a corresponding calculation cycle). Then, the parking electric line quantity Ipk is output according to a preset pattern based on the time elapsed since the timer was started. Specifically, the vehicle stop is determined based on the vehicle speed Vxa. Then, the parking electric line quantity Ipk is output to show an increase by a time gradient kz0, reaching an upper limit ipm with time when the timer has been started as zero (starting point).The upper limit value is set such that the pressing force fpk required to maintain the stopped state of the vehicle (requested value of the parking brake) can be reliably achieved by taking into account the power transmission efficiency of the brake actuator BRK.

[0071] When the pressing force Fpa reaches the requested value fpk of the parking brake by the parking electric line quantity Ipk, the solenoid actuator SOL is energized based on the solenoid electric line instruction Iso, and a ratchet gear RCH is brought into engagement with an engaging pawl TSU.

[0072] The locking mechanism PKB is provided on the restricted wheel (e.g., the rear wheel WHr). The locking mechanism PKB is configured with the ratchet wheel RCH, the solenoid SOL, and the engagement pawl TSU. The ratchet wheel RCH rotates synchronously with the electric motor MTR.

[0073] For example, the electric motor MTR and the ratchet wheel RCH are coaxially fixed and rotate integrally. The engaging pawl TSU can engage with the ratchet wheel RCH and is moved by the solenoid SOL. Specifically, when the solenoid SOL is energized by the solenoid electrical line command Iso, the engaging pawl TSU is pushed out toward the ratchet wheel RCH by the solenoid SOL. As a result, the engaging pawl TSU and the ratchet wheel RCH are engaged. Unlike ordinary gear teeth, the ratchet wheel RCH has inclined teeth (shaped in a so-called sawtooth shape), and the directionality of rotation is determined by the angle of these teeth.When the engagement pawl TSU and the ratchet wheel RCH are engaged, the state in which the friction elements MSB press the rotary element KTB is maintained even if the electric conduction of the electric motor MTR and the solenoid SOL is stopped, whereby the state in which the parking brake is effective can be maintained.

[0074] From the block for calculating the electric parking line quantity IPK, when the parking switch SW is moved from off to on, the control device CTL increases not only the pressing force of the restricted wheel, but also the pressing force of the free wheel. This means that when the parking brake is activated, the output of the electric motor MTR is increased for the entire pressure application unit KAU, including the free wheel. The increase in the pressing force at the start of the parking brake is used to generate the conversion calculation maps CMkt, CFpe (described later), which also correspond to the free wheel.

[0075] In the command electric conduction quantity calculation block IMT, the command electric conduction quantity Imt, which is the final command value of the electric conduction quantity, is calculated based on the command electric conduction quantity (command value) Ims, the composite compensation electric conduction quantity Igh, and the parking electric conduction quantity Ipk. Specifically, in the case where the parking brake application is not commanded (the parking signal Swa is off and Ipk = 0), the composite compensation electric conduction quantity Igh is added to the command electric conduction quantity Ims, and a sum thereof is calculated as the command electric conduction quantity Imt (i.e., Imt = Ims + Igh). That is, the command electric conduction quantity Imt is determined such that the output of the electric motor MTR is adjusted by the composite compensation electric conduction quantity Igh based on the feedback control.

[0076] When the parking brake application is instructed, the command electric conduction quantity Ims and the parking electric conduction quantity Ipk are compared, and the larger of these is calculated as the target electric conduction quantity Imt. In this case, the composite compensation electric conduction quantity Igh is set to "0 (zero)" (that is, compensation by control is not performed).

[0077] In the case where the determination flag Hnt indicates that "the pressure force sensor FPA is not suitable (Hnt = 1)", "Igh = Imk" is established, so the command electric line quantity calculation block IMT calculates the command electric line quantity Imt, which is the final command value of the electric line quantity, based on the command electric line quantity (command value) Ims, the rotation angle compensation electric line quantity Imk, and the parking electric line quantity Ipk. In the case where the parking brake is not commanded (where the parking signal Swa is off and Ipk = 0), the rotation angle compensation electric line quantity Imk is added to the command electric line quantity Ims, and the sum of these is calculated as the command electric line quantity Imt (that is, Imt = Ims + Imk).When the parking brake is commanded, the command electrical conduction quantity Ims and the parking electrical conduction quantity Ipk are compared, and the larger of these is calculated as the target electrical conduction quantity Imt, similar to the case of "Hnt = 0." In this case, the rotation angle compensation electrical conduction quantity Imk is set to "0 (zero)".

[0078] In the target electric conduction quantity IMT calculation block, a sign of the target electric conduction quantity Imt (a value of which is positive or negative) is determined based on a direction in which the electric motor MTR is to rotate (i.e., an increase or decrease direction of the pushing force). Furthermore, an amount of the target electric conduction quantity Imt is calculated based on rotational power that the electric motor MTR is to output (i.e., an increase or decrease amount of the pushing force). Specifically, the sign of the target electric conduction quantity Imt is calculated as a positive sign (Imt>0) in a case where the brake pressure is increased and the electric motor MTR is driven in a forward direction.In contrast, the sign of the target electric conduction quantity Imt is determined as a negative sign (Imt < 0) in a case where the brake pressure is reduced and the electric motor MTR is driven in a reverse direction. Furthermore, the output torque (rotational power) of the electric motor MTR is controlled to increase as the absolute value of the target electric conduction quantity Imt increases, and the output torque is controlled to decrease as the absolute value of the target electric conduction quantity Imt decreases.

[0079] In the switching control block SWT, drive signals Su1 to Sw2 for performing pulse width modulation of the respective switching elements SU1 to SW2 are calculated based on the target electrical conduction quantity Imt. In the case where the electric motor MTR is a brushless motor, target values ​​Iut, Ivt, Iwt of electrical conduction quantities of the respective phases (U-phase, V-phase, and W-phase) are calculated based on the target electrical conduction quantity Imt and the rotation angle Mka. Duty cycles Dut, Dvt, Dwt of pulse widths of the respective phases (proportion of an on-period in one cycle) are determined based on the target electrical conduction quantities Iut, Ivt, Iwt of the respective phases.Then, the drive signals Su1 to Sw2, which determine whether the respective switching elements SU1 to SW2 configuring the bridge circuit BRG should be in an on state (electrically conductive state) or an off state (electrically non-conductive state), are calculated based on the duty cycles (set values) Dut, Dvt, and Dwt. The drive signals Su1 to Sw2 are output to the drive circuit DRV.

[0080] The six drive signals Su1 to Sw2 individually control the electrically conductive and non-conductive states of the six switching elements SU1 to SW2. The longer the duty cycle, the longer the conduction time per unit time in each switching element, and the larger the current flowing in its coil, the greater the rotational power of the electric motor MTR.

[0081] The drive circuit DRV is equipped with a device for acquiring an electrical conduction quantity (e.g., a current sensor) IMA for each phase, and the actual electrical conduction quantity (all of the respective phases) Ima is thereby acquired (detected). The detected value (e.g., an actual current value) Ima of each phase is input to the switching control block SWT. Then, a so-called current control is performed so that the detected value Ima of the respective phases agrees with the target values ​​Iut, Ivt, Iwt. Specifically, the duty cycles Dut, Dvt, Dwt in the respective phases are modified (fine-tuned) based on deviations between the actual electrical conduction quantity Ima and the target electrical conduction quantities Iut, Ivt, Iwt. High-precision motor control can be achieved through this current control. <Bürstenloser Drei-Phasen-Motor MTR und dessen Antriebsschaltung DRV>

[0082] The example in which the brushless three-phase motor with three coils (windings), namely the U-phase coil CLU, the V-phase coil CLV and the W-phase coil CLW, is applied as the electric motor MTR is explained with reference to a circuit diagram of Fig. 3. In the brushless motor MTR, magnets are arranged on the rotor (rotor) side, and wiring circuits (coils) are arranged on the stator (stator) side. The electric motor MTR is commutated by the drive circuit DRV at timings that coincide with the rotor's magnetic poles and is driven to rotate.

[0083] The electric motor MTR is equipped with the rotation angle sensor MKA, which is configured to detect the rotation angle (rotor position) Mka of the electric motor MTR. A Hall element type is used as the rotation angle sensor MKA. A variable reluctance type resolver can also be used as the rotation angle sensor MKA. The detected rotation angle Mka is input to the control device CTL.

[0084] The drive circuit DRV is an electrical circuit configured to drive the electric motor MTR. The electric motor MTR is driven by the drive circuit DRV based on the drive signals Su1, Su2, Sv1, Sv2, Sw1, SW2 (which may be referred to as "Su1 to Sw2") for the respective phases from the control device CTL. The drive circuit DRV is configured from the three-phase bridge circuit BRG (which may be simply referred to as a bridge circuit) formed by the six switching elements (power transistors) SU1, SU2, SV1, SV2, SW1, SW2 (which may be referred to as "SU1 to SW2") and a stabilizing circuit LPF.

[0085] The rechargeable battery BAT is connected to an input side of the three-phase bridge circuit BRG (which may be referred to as an inverter circuit) via the stabilizing circuit LPF, and the electric motor MTR is connected to an output side of the bridge circuit BRG. In the bridge circuit BRG, a voltage-type bridge circuit with an upper and lower arm configuration connecting the switching elements in series is used for one phase, thereby configuring the three phases (U-phase, V-phase, and W-phase). Upper arms of the three phases are connected to a power line PW1, which is connected to a positive electrode side of the rechargeable battery BAT. Furthermore, lower arms of the three phases are connected to a power line PW2, which is connected to a negative electrode side of the rechargeable battery BAT.In the bridge circuit BRG, the upper and lower branches of the respective phases are connected to the power lines PW1, PW2 in parallel to the rechargeable battery BAT.

[0086] The upper U-phase branch includes a freewheeling diode DU1 connected in reverse parallel to the switching element SU1, and the lower U-phase branch includes a freewheeling diode DU2 connected in reverse parallel to the switching element SU2. Similarly, the upper V-phase branch includes a freewheeling diode DV1 connected in reverse parallel to the switching element SV1, and the lower V-phase branch includes a freewheeling diode DV2 connected in reverse parallel to the switching element SV2. Furthermore, the upper W-phase branch includes a freewheeling diode DW1 connected in reverse parallel to the switching element SW1, and the lower W-phase branch includes a freewheeling diode DW2 connected in reverse parallel to the switching element SW2. Connecting sections PCU, PCV, PCW of the upper and lower branches of the respective phases form output terminals (AC output terminals) of the bridge circuit BRG.The electric motor MTR is connected to these output terminals.

[0087] The six switching elements SU1 to SW2 are elements that can turn part of the electrical circuit on or off. For example, MOSFETs and IGBTs can be used as the switching elements SU1 to SW2. In the brushless motor MTR, the switching elements SU1 to SW2 that configure the bridge circuit BRG are controlled based on the rotation angle (rotor position) Mka. Furthermore, the electrical conduction directions (i.e., excitation directions) of the coils CLU, CLV, CLW of the respective three phases (U-phase, V-phase, W-phase) are sequentially switched, thereby driving the electric motor MTR to rotate. That is, a rotation direction (forward or reverse direction) of the brushless motor MTR is determined by a relationship between the rotor and a position where magnetic excitation occurs.Here, the forward direction of the electric motor MTR is a rotation direction corresponding to the increase in the pressing force Fpa by the pressurizing unit KAU, and the reverse direction of the electric motor MTR is a rotation direction corresponding to the decrease in the pressing force Fpa.

[0088] The device for acquiring the electrical line size IMA for detecting the actual electrical line size Ima (collective expression for the respective phases) between the bridge circuit BRG and the electric motor MTR is provided for each of the three phases.

[0089] For example, a current sensor is provided as the device for acquiring the electric line quantity IMA, and the current value is detected as the actual electric line quantity Ima. The detected electric line quantity Ima of each phase is input to the control device (control means) CTL.

[0090] The drive circuit DRV receives power from a power source (rechargeable battery BAT, generator ALT). To reduce fluctuations in the supplied power (voltage), the drive circuit DRV is equipped with the stabilization circuit LPF (which may also be referred to as a noise reduction circuit). The stabilization circuit LPF is configured by a combination of at least one capacitor (capacitance) and at least one inductor (coil), and is a so-called LC circuit (which may also be referred to as an LC filter).

[0091] As the electric motor MTR, a brushed motor (which may simply be referred to as a brushed motor) can be used instead of a brushless motor. In this case, an H-bridge circuit configured with four switching elements (power transistors) is used as the bridge circuit BRG. This means that in the bridge circuit BRG of the brushed motor, one of the three phases in the brushless motor is omitted. Similar to the case of the brushless motor, the electric motor MTR is equipped with the rotation angle sensor MKA, and the drive circuit DRV is equipped with the stabilization circuit LPF. Furthermore, the drive circuit DRV is equipped with the electrical conductivity sensor IMA. <Prozesse in dem Eignungsbestimmungsblock und Erzeugungsprozesse von Umwandlungsberechnungskennfeldern>

[0092] Processes in the suitability determination block HNT and processes in the conversion calculation block HNK (in particular, generation processes of the conversion calculation maps CMkt, CFpe) are described below with reference to a flowchart of Fig. 4 described.

[0093] First, in step S110, a brake operation amount Bpa is read. After that, the process proceeds to step S120. In step S120, a determination is made as to whether or not braking is being performed based on the brake operation amount Bpa. Specifically, "braking is being performed" is determined in a case where the brake operation amount Bpa is equal to or greater than the predetermined value bp0. Furthermore, "braking is not being performed (no braking)" is determined in a case where the brake operation amount Bpa is less than the predetermined value bp0. In a case where "braking is being performed" is affirmed in step S120 (a case of "YES"), the process proceeds to step S130. On the other hand, in a case where "braking is being performed" is negated in step S120 (a case of non-braking and "NO"), the process returns to step S110.The predetermined value bp0 is a value that corresponds to the “play” of the brake actuating element BP.

[0094] The determination in step S120 may be made based on a signal from a stop switch provided in the brake operating member BP. The determination of braking is made when the stop switch signal is on, and the determination of non-braking is made when the stop switch signal is off. A calculation cycle in which the determination of step S120 is affirmatively determined for the first time is referred to as "brake operation start." That is, in a situation where a "brake operation not being performed" state continues, a time point at which "brake operation is being performed" is the start of brake operation.

[0095] In step S130, the actual rotation angle (actual rotation angle value) Mka and the actual pressing force (actual pressing force value) Fpa are read. The process proceeds to step S140. In step S140, the estimated pressing force (pressing force estimated value) Fpe is calculated based on the actual rotation angle Mka and the conversion calculation map CFpe. The estimated pressing force Fpe is a value corresponding to the actual pressing force Fpa and is estimated from the actual rotation angle Mka.

[0096] In step S150, it is determined whether the actual pressing force Fpa is suitable based on the comparison of the estimated pressing force Fpe and the actual pressing force Fpa. For example, the suitability determination of the actual pressing force Fpa is performed based on whether the absolute value of the deviation hFp between the actual pressing force Fpa and the estimated pressing force Fpe is less than the predetermined value (suitability determination value) hfx. The process proceeds to step S160 in a case where the absolute value of the deviation hFp is less than the predetermined value hfx and the suitability determination condition is affirmative (case of "YES"). On the other hand, in a case where the absolute value of the deviation hFp is equal to or greater than the predetermined value hfx and the suitability determination condition is negated (case of "NO"), the process proceeds to step S200.The predetermined value hfx is the threshold for suitability determination and is a value smaller than the lower value fps.

[0097] In step S160, the actual rotation angle Mka and the actual thrust force Fpa are synchronized and stored. That is, since the actual thrust force Fpa has been determined to be appropriate, the actual rotation angle Mka and the actual thrust force Fpa are stored in a memory of a microprocessor during the calculation cycle to generate the conversion calculation maps CMkt, CFpe. The process proceeds to step S170.

[0098] In step S170, the composite compensation electrical line size Igh is calculated as described above and is transferred from the block for calculating the composite compensation electrical line size IGH to the block for calculating the target electrical line size IMT (see Fig. 2). This means that normal control is performed when the actual pressure force Fpa is in a suitable state.

[0099] In step S180, it is determined based on the brake operation amount Bpa whether or not the brake operation has continued since the start of the brake operation was completed. Specifically, the completion of the brake operation is determined based on whether or not the brake operation amount Bpa is less than a release-side predetermined value bps. Here, the release-side predetermined value bps is a value less than an operation-side predetermined value bp0. In a case where the brake operation amount Bpa is less than the predetermined value bps and the brake operation completion determination condition is met (a case of "YES"), the process proceeds to step S190.In a case where the brake operation amount Bpa is equal to or greater than the predetermined value bps and the brake operation completion determination condition is negated (a case where the brake operation is still continued and “NO”), the process returns to step S110.

[0100] Similar to the determination in step S120, the determination of step S180 may be made based on a signal from the stop switch provided in the brake operating member BP. The determination that braking is continuing is made in a case where the stop switch signal is on, and the determination that braking is completed is made in a case where the stop switch signal is off.

[0101] In step S190, the conversion calculation maps CMkt, CFpe are generated based on the data arrays of the actual rotation angle Mka and the actual pressing force Fpa that have been synchronized and stored. That is, the data of the actual rotation angle Mka and the actual turning force Fpa that have been stored in a braking operation sequence that has continued from the start of the braking operation until its completion are processed after the braking operation is completed, thereby regenerating the conversion calculation maps CMkt, CFpe. Furthermore, past conversion calculation maps CMkt, CFpe are replaced with the new conversion calculation maps CMkt, CFpe.

[0102] In step S200, since the compression force sensor FPA is unsuitable, "Kfp = 0, Kmk = 1" is applied, thereby determining the composite compensation electric line quantity Igh. That is, compression force control is prohibited, and only rotation angle control is performed, and the rotation angle compensation electric line quantity Imk is output as the composite compensation electric line quantity Igh. The process of step S200 is the control for a case where the actual compression force signal Fpa is in an unsuitable state. <Umwandlungsberechnungskennfelder CMkt, CFpe auf der Grundlage von Annäherungspolynomen>

[0103] Processes in the approximate function calculation block KNJ in the conversion calculation block HNK are described below with reference to a characteristic diagram of Fig. 5A, Fig. 5B. The approximate function calculation block KNJ stores the output value Fpa of the analog-to-digital conversion processing block ADH and the detection value Mka of the rotation angle sensor MKA by synchronizing them. The conversion calculation map CMkt (Fpt-Mkt conversion characteristic) for the target rotation angle Mkt and the conversion calculation map CFpe (Mka-Fpe conversion characteristic) for the estimated pressing force Fpe are generated based on the stored time-series data (Fpa-Mka characteristic).

[0104] The conversion calculation maps CMkt and CFpe can be set as initial maps based on the stiffness (spring constant) of the brake caliper CRP, the friction elements MSB, and the like, as well as the dimensions of the wheel cylinder WC and the pressurizing cylinder KCL (the pressure-receiving surfaces). However, the stiffness of the friction elements MSB changes over time due to wear (the stiffness gradually increases). Therefore, the conversion calculation maps CMkt and CFpe store the correlation between the actual pressing force Fpa and the actual rotation angle Mka each time the brake application sequence occurs, and are sequentially updated based on the stored correlation (Fpa-Mka map). The "brake application sequence" refers to the start to the end of the brake application.

[0105] The approximate function calculation block KNJ is formed into the conversion calculation block HNK. In the approximate function calculation block KNJ, the conversion calculation maps CMkt, CFpe are approximated and determined as functions Knj, Kni based on the actual pressing force Fpa and the actual rotation angle Mka. Specifically, the actual pressing force Fpa and the actual rotation angle Mka are measured in chronological synchronism and stored as a time-series data set. With this data set, the actual rotation angle Mka is approximated with respect to the actual pressing force Fpa as a second-order or higher-order polynomial Knj through post-processing (that is, the processes following the sequence of braking operation from the start to the end of braking operation). Similar to the approximate function Knj, the actual pressing force Fpa is approximated with respect to the actual rotation angle Mka as a second-order or higher-order polynomial Kni.The approximate relationships between the actual compressive force Fpa and the actual rotation angle Mka are referred to as the "approximate functions Knj, Kni." The approximate functions Knj, Kni are in a relationship of inverse functions. <<Umwandlungsberechnungskennfeld CMkt für den Soll-Drehwinkel Mkt> >

[0106] First, the conversion calculation map (target rotation angle map) CMkt for the target rotation angle Mkt is described. Since the actual pressing force Fpa is input to the control device CTL after undergoing the processes in the analog-to-digital conversion processing block ADH, it is acquired as a stepwise value for each "1 (unit)" LSB, as shown by a dashed line. Since the relationship between the actual pressing force Fpa and the actual rotation angle Mka is expressed as the polynomial approximation function Knj, the stepwise data generated by the LSB (which is the least significant bit and the signal resolution) is interpolated.

[0107] Furthermore, the influence of disturbance, as indicated by point Q, may be superimposed on a detection signal. The influence of the disturbance can be compensated by a filter. However, when a filter is used, the detection value is chronologically delayed, and it may be difficult to satisfy a relatively fast brake application. Since the stored data is smoothed by the approximation function Knj, the correlation between the actual pressing force Fpa and the actual rotation angle Mka can be accurately obtained even during a fast brake application.

[0108] The approximate function Knj is set as a new conversion calculation map CMkt so that it can be used in subsequent and upcoming braking operations. The actual pressing force Fpa is replaced with the target pressing force Fpt, and the actual rotation angle Mka is replaced with the target rotation angle Mkt, and an updated conversion calculation map CMkt is determined thereby. That is, the target rotation angle Mkt is set as a function map expressed in a second-order or higher polynomial that uses the target pressing force Fpt as its variable and passes through the origin (i.e., Mkt = 0 when Fpt = 0). In the conversion calculation map CMkt, the nonlinearity of the stiffnesses of the brake caliper CRP, the friction elements MSB, and the like is taken into account, and the target rotation angle Mkt is increased with the "upward convex" characteristic with respect to the increase in the target pressing force Fpt.As described above, the approximate function Knj is calculated in the sequence of brake application and is sequentially updated as the conversion calculation map CMkt to be used in the subsequent brake application, so that a deviation in the calculation map caused by the chronological change in the friction elements MSB can be compensated for. Furthermore, since the conversion calculation map CMkt is set as the monotonically increasing function, a situation in which the target rotation angle Mkt decreases despite the increase in the target pressing force Fpt can be appropriately avoided.

[0109] In a case where a third-order or higher polynomial is to be applied as the approximate function Knj, as illustrated by a dot-dash line, there may be a case where the target rotation angle Mkt does not increase monotonically with respect to the increase in the target pressing force Fpt (that is, there may be a case where an inflection point H is included when Fpt = fph is satisfied). In order to prevent the inflection point in the approximate function Knj and set it as the "upward convex" monotonically increasing function, the approximate function Knj can be generated using at least two functions (polynomials) Kj1, Kj2. Specifically, the approximate function Knj for the target rotation angle is approximated as a first approximate function Kj1 in a range A (0 ≤ Fpt < fpv), and is approximated as a second approximate function Kj2 in a range B (fpv ≤ Fpt ≤ fpk).Here, the first approximate function Kj1 and the second approximate function Kj2 are continuous at a point P (Fpt = fpv, Mkt = mkv). Since the predetermined value fpv is a boundary between the first approximate function Kj1 and the second approximate function Kj2, it is referred to as a "boundary value."

[0110] Furthermore, the order of the first approximate function (first polynomial) Kj1 can be set larger than the order of the second approximate function (second polynomial) Kj2. For example, in a case where the first approximate function Kj1 is a third-order polynomial, the second approximate function Kj2 is set as a second-order polynomial. This is because in the stiffnesses (spring constants) of the brake caliper CRP, the friction elements MSB, and the like, in a case where the actual pressing force Fpa (i.e., the target pressing force Fpt) is small, the spring constants are small and the nonlinearity thereof is strong, and in a case where the actual pressing force Fpa is large, the spring constants become larger and the nonlinearity thereof becomes weak (closer to a linear profile).

[0111] The respective predetermined values ​​(lower value fps, etc.) have the relationship described below. The limit value fpv is a value equal to or greater than the upper value fpu (0 < fps ≤ fpu ≤ fpv). Thus, the conversion characteristic in a region where the coefficients Kfp, Kmk gradually change (range of "Fpt < Fpu") is approximated by the first approximation function (the first polynomial) Kj1. When the parking brake is started, the pressing force is increased not only for the restricted wheel but also for the free wheel (see Fig. 2). On this occasion, the actual pressing force Fpa is increased to a predetermined value fpk. The predetermined value fpk is referred to as the "requested value (of the parking brake)." The requested value fpk is set to a value greater than the limit value fpv. With this parking brake operation, the actual pressing force Fpa (i.e., the target pressing force Fpt) from "0" to the requested value fpk is measured and stored even for the free wheel not equipped with the parking brake mechanism PKB. Therefore, a highly accurate conversion calculation map CMkt can be generated. The conversion calculation map (target rotation angle map) CMkt for the target rotation angle has been described above. <<Umwandlungsberechnungskennfeld CFpe für die geschätzte Druckkraft Fpe> >

[0112] The conversion calculation map (estimated pressure force map) CFpe for the estimated pressure force Fpe is described below. Since the generation of the conversion calculation map CFpe is similar to the generation of the conversion calculation map CMkt, its description is brief. Similar to the conversion calculation map CMkt, the conversion calculation map CFpe is also determined based on the correlation (Fpa-Mka characteristic) of the actual pressure force Fpa and the actual rotation angle Mka. The conversion calculation map CFpe is determined by determining the relationship between the actual pressure force Fpa and the actual rotation angle Mka, and the actual pressure force Fpa is replaced by the estimated pressure force Fpe.

[0113] When generating the conversion calculation map CFpe, the approximate function (approximate polynomial) Kni can also be applied to the estimated pressure force. Here, the approximate function Kni is an inverse function of the approximate function Knj (a function obtained by exchanging an independent variable and a dependent variable of another function). That is, the estimated pressure force Fpe is set as a function map expressed as a second-order or higher polynomial that uses the actual rotation angle Mka as its variable and passes through the origin (i.e., Fpe = 0 when Mka = 0).In the conversion calculation map CFpe, the nonlinearity of the stiffnesses of the brake caliper CRP, the friction elements MSB and the like is taken into account, and the estimated pressing force Fpe is increased with a “downward convex” characteristic with respect to the increase in the actual rotation angle Mka.

[0114] To avoid an inflection point in the approximate function Kni and to set it as a "downward convex" monotonically increasing function, the approximate function Kni can be generated using at least two functions (polynomials) Ki1, Ki2. Specifically, the approximate function Kni is approximated as a first approximate function Ki1 in a range C (0 ≤ Mka < mkv) and is approximated as a second approximate function Ki2 in a range D (mkv < Mka < mpk). Here, the first approximate function Ki1 and the second approximate function Ki2 are continuous. Furthermore, the order of the first approximate function (the first polynomial) Ki1 can be set larger than the order of the second approximate function (the second polynomial) Ki2. For example, in a case where the first approximation function Ki1 is a third-order polynomial, the second approximation function Ki2 is set as a second-order polynomial.

[0115] In the respective predetermined values ​​(lower angle mks, etc.), the lower angle mks is a predetermined value corresponding to the lower value fps, the upper angle mku is a predetermined value corresponding to the upper value fpu, the limit angle mkv is a predetermined value corresponding to the limit value fpv, and the requested angle mkk is a predetermined value corresponding to the requested value fpk. Thus, there is a relationship of "0 ≤ mks ≤ mku ≤ mkv < mkp."

[0116] Similar to the target rotation angle map CMkt, for the estimated pressing force map CFpe, the approximate function Kni is calculated in the sequence of brake application and is sequentially updated as the conversion calculation map CFpe for the subsequent brake application. Therefore, deviations in the calculation map caused by chronological changes in the friction elements MSB and the like can be compensated. Since the conversion calculation map CFpe is set as a monotonically increasing function, a situation in which the estimated pressing force Fpe decreases despite the increase in the actual rotation angle Mka can be appropriately avoided.

[0117] The pressing force generated by braking during normal driving (so-called normal braking) is still not that large. In contrast, the pressing force set by the parking brake is extremely larger than in the case of normal braking because sloped roads and the like are taken into account. Thus, the requested value (pre-set and predetermined value) fpk for the parking brake has a range of pressing force used in normal braking. By the parking brake application, the actual pressing force Fpa from "0" of the actual rotation angle Mka to the requested angle mkk by the parking brake is measured and stored for the free wheel that is not equipped with the locking mechanism PKB. As a result, a highly accurate estimated pressing force map CFpe can be generated.Therefore, even if the pressure force sensor FPA is faulty, the estimated pressure force Fpe is calculated with high accuracy based on the actual rotation angle Mka and the conversion calculation map CFpe, and control can be performed by the estimated pressure force Fpe (i.e., the actual rotation angle Mka). The conversion calculation map (estimated pressure force map) CFpe for the estimated pressure force has been described above. <Funktionsweisen und Wirkungen>

[0118] Functions and effects of the brake control devices BCS, BCR according to the present invention are described with reference to time sequence graphs of Fig. 6A, Fig. 6B. Fig. 6A and Fig. 6B shows a comparison of (a) the case where the appropriate state is determined for the pressure force sensor FPA and (b) the case where the inappropriate state is determined for the pressure force sensor FPA.

[0119] At time u0, the driver starts operating the brake operating element BP, and at time u1, the brake operating amount Bpa exceeds the predetermined value bp0. Then, the brake operating amount Bpa is increased until time u4, and from time u4 onward, the brake operating amount Bpa is maintained at the predetermined value bp1.

[0120] First, the case where the appropriate state of the pressure force sensor FPA is determined with reference to Fig. 6A. The target pressing force Fpt is increased based on the brake application amount Bpa, resulting in an increase in the actual pressing force Fpa and the estimated pressing force Fpe. Since the target value and the actual value are controlled to coincide by feedback control, lines of the target pressing force Fpt, the actual pressing force Fpa, and the estimated pressing force Fpe are superimposed.

[0121] As the brake application amount Bpa increases, the target rotation angle Mkt increases based on the target pressing force Fpt and the conversion calculation map CMkt (e.g., the approximate function Knj), and as a result, the actual rotation angle Mka increases. In a case where the target pressing force Fpt increases linearly with the elapse of time T, the target rotation angle Mkt in the "upward convex" profile increases with the elapse of time T due to the nonlinearity of the conversion calculation map CMkt. Similar to the case of the target pressing force Fpt, since the target value and the actual value are controlled to coincide by feedback control, lines of the target rotation angle Mkt and the actual rotation angle Mka are superimposed.

[0122] The weighting coefficients Kfp and Kmk are determined based on the sequentially increased target pressing force Fpt (i.e., the brake application amount Bpa). Until time u2 when the target pressing force Fpt reaches the lower value fps, "Kfp = 0, Kmk = 1" is calculated. Under this condition, when calculating the composite compensation electric line quantity Igh, only the rotation angle compensation electric line quantity Imk is applied, and the pressure force compensation electric line quantity Ifp is not applied. This means that until time u2, only the control based on the rotation angle Mka of the electric motor MTR is performed, and the output of the electric motor MTR is adjusted accordingly.

[0123] In a case where an analog-type sensor is used as the pressure force sensor FPA, the actual pressure force Fpa is acquired by the analog-to-digital conversion processing block ADH. Therefore, the actual pressure force Fpa is affected by the resolution of the analog-to-digital conversion process. In particular, the influence of the resolution is prominent when the actual pressure force Fpa is small. However, in the region where the actual pressure force Fpa is small, only the actual rotation angle Mka is applied in the control, which can suppress the influence of the resolution. Furthermore, since the rotation angle control is performed based on the conversion calculation map CMkt, which is updated every time the brake application sequence occurs, highly accurate brake control can be performed.

[0124] From time u2 to time u3, the pressure force coefficient Kfp is gradually increased from "0" to "1", and the rotation angle coefficient Kmk is gradually decreased from "1" to "0". Since the coefficients Kfp and Kmk are gradually changed according to the change in the target pressure force Fpt, no abrupt change in the state variables is performed in the control, and the switching can be performed smoothly.

[0125] At time u3, when the condition "Fpt ≥ fpu" is met, "Kfp = 1, Kmk = 0" is calculated. Under this condition, when calculating the composite electrical compensation line quantity Igh, only the electrical pressure force compensation line quantity Ifp is applied, and the electrical angle compensation line quantity Imk is not applied. This means that from time u3 onwards, control is performed based on the detection value Fpa of the pressure force sensor FPA. This is because when the actual pressure force Fpa becomes relatively large, the influence of the resolution in the analog-to-digital conversion process has less influence on the control.

[0126] The following is the case where the unsuitable state of the pressure force sensor FPA is determined with reference to Fig. 6B. These are mainly the points that differ from the one described with reference to Fig.6A, the "suitable condition" case is described. In the graph, the target pressure force Fpt and the estimated pressure force Fpe are superimposed, and the target rotation angle Mkt and the actual rotation angle Mka are superimposed.

[0127] The target pressing force Fpt is increased from time u1 when the brake application amount Bpa has exceeded the predetermined value bp0. However, since the pressing force sensor FPA is faulty, the signal of the actual pressing force Fpa remains "0" (is not output). At time uh, when the deviation (comparison result) hFp between the actual pressing force Fpa and the estimated pressing force Fpe exceeds the predetermined threshold value hfx, the suitability determination condition in step S150 is negated, and it is thereby determined as "the pressing force sensor FPA is not in the suitable state." Here, the threshold value hfx for suitability determination is set to a value smaller than the lower value fps. Thus, the suitability determination of the pressing force sensor FPA is performed in the state of "Kfp = 0, Kmk = 1." Therefore, the application of the signal Fpa of the faulty pressing force sensor FPA in the control can be avoided.

[0128] Since the correctness of the pressure force sensor FPA is determined based on the estimated pressure force map CFpe, which is updated with each brake application, sensor fault detection can be reliably performed. Furthermore, when it is determined that "the pressure force sensor FPA is not in the appropriate state," the pressure force coefficient Kfp is determined as "0" according to the coefficient calculation map CKfn, and the rotation angle coefficient Kmk is determined as "1" according to the coefficient calculation map CKmn. This means that pressure force control is inhibited, only rotation angle control is performed, and the output of the electric motor MTR is thereby adjusted.

[0129] In the rotation angle control, at the end of the brake application sequence, the target rotation angle Mkt is calculated based on the latest conversion calculation map CMkt approximated by the second-order or higher-order polynomial (function) Knj, and the electric motor MTR is controlled so that the target rotation angle Mkt and the actual rotation angle Mka coincide. Therefore, even in the case where the pressure force sensor FPA is in the inappropriate state, appropriate braking control can be performed by the rotation angle control. The operations and effects of the brake control devices BCS, BCR according to the present invention have been described above.

[0130] In the embodiments, the configuration with a disc brake using brake fluid pressure was given as an example. Instead of the disc brake, a drum brake can be used. Furthermore, brake fluid pressure does not need to be used, and a configuration in which the friction elements MSB are pressed against the rotating element KTB directly by the power transmission mechanism DDK can be used. The same advantageous effects are also achieved in this configuration.

Claims

[1] A brake control device for a vehicle configured to generate a force for pressing a friction element (MSB) against a rotary element (KTB) attached to a wheel (WH) of the vehicle via an electric motor (MTR) controlled by a control device (CTL) in accordance with an operation amount (Bpa) of a brake operating element (BP) of the vehicle, the brake control device comprising: a pressure force sensor (FPA) configured to detect the pressure force as an actual pressure force value (Fpa); and a rotation angle sensor (MKA) configured to detect an actual rotation angle value (Mka) of the electric motor (MTR), where the control device (CTL) is configured to determine whether an operating state of the pressure force sensor (FPA) is suitable or not; in a case of determining that the operating state of the pressure force sensor (FPA) is suitable, the control device (CTL) is configured to adjust an output of the electric motor (MTR) based on the actual pressure force value (Fpa), store a correlation (Fpa-Mka) between the actual pressure force value (Fpa) and the actual rotation angle value (Mka), and generate a conversion calculation map (CMkt, CFpe) based on the correlation (Fpa-Mka); in a case of determining that the operating state of the pressure force sensor (FPA) is not suitable, the control device (CTL) is configured to adjust the output of the electric motor (MTR) based on the actual rotation angle value (Mka) and the conversion calculation map (CMkt, CFpe), and the control device (CTL) is configured: to calculate a pressure force estimate (Fpe) based on the actual rotation angle value (Mka) and the conversion calculation map (CFpe); and to determine whether the operating condition of the compression force sensor (FPA) is suitable or not based on a comparison result (hFp) of the actual compression force value (Fpa) and the compression force estimated value (Fpe).

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