JP2014177206A - Electrically-driven braking device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrically-driven braking device that can accurately determine a reference position as a position where a friction member (for example, a brake pad) begins to come into contact with a rotary member (for example, a brake disk).SOLUTION: When a braking manipulated variable is decreased, a rigidity value (Gcq) as the ratio of the amount (Fbh) of change in actual pressing force (Fba) of a friction member to the amount (Mkh) of change in actual position (Mka) of an electric motor is computed in sequence. Once the rigidity value changes from a predetermined value or larger to less than the predetermined value, the actual position at the point of time is stored as a candidate position (Mkk). The candidate position is discarded when a continuance of a state in which the rigidity value is less than the predetermined value is less than a gap equivalent value equivalent to a gap of a transmission member while the candidate position is stored. At the moment when the continuance of the state in which the rigidity value is less than the predetermined value exceeds the gap equivalent value, the stored candidate position is determined as a reference position (pzr) where the friction member and rotary member begin to come into contact with each other.

Description

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

  The following is described in the prior art for the purpose of accurately obtaining a reference position at which a brake disk (also referred to as a brake rotor) and a brake pad start contact.

  In Patent Document 1, “the electric drive brake device is provided with a differential circuit for the output of the press sensor and a circuit for comparing the differential value with the set threshold value, and the position where the differential value of the press sensor output is smaller than the set threshold value is (Reference position) ”.

  Patent Document 2 states that “in the electric brake, when the pressing force applied to the brake pad is decreased, the decreasing gradient of the pressing force (the amount of change in the pressing force with respect to the amount of change in the rotation angle) becomes gentler than the set gradient. The rotational position of the electric motor at that time is defined as a temporary 0 point position, and the position on the reverse side by an amount α corresponding to the non-restoring amount of the brake pad from the temporary 0 point position is defined as a 0 point position (reference position). Is described.

  Patent Document 3 states that “when the brake is released, the position at which the piston is returned to the brake release side by a predetermined amount from the piston position when the piston thrust is less than or equal to a predetermined threshold value greater than 0 is defined as the disc rotor and brake pad. Is set to the contact start position (reference position) ”.

JP 2000-018294 A JP 2001-225741 A JP 2004-124950 A

Electric / mechanical braking device (so-called electric brake, EMB (Electro-Mechanical
(Referred to as “Brake”), the force of the electric motor is transmitted to a friction member (for example, a brake pad) by a power transmission mechanism such as a speed reducer and pressed against a rotating member (for example, a brake disk) (pressing force). ) Is generated. Generally, the detection of the reference position is performed when the electric motor is reversed and the braking torque is reduced (that is, the friction member is gradually separated from the rotating member, and the force by which the friction member presses the rotating member is reduced). Case). Here, the reference position is a boundary position indicating whether or not the friction member and the rotating member come into contact with each other, and is also referred to as a contact start position, a zero point position, or an initial position.

  Hereinafter, the relationship among the reference position, the position (rotation angle) Mka of the electric motor, and the pressing force Fba when the electric motor is reversed and the pressing force is reduced will be described with reference to FIG. When the pressing force Fba is reduced, the contact state in the power transmission is switched by the backlash of the mechanical elements of the power transmission mechanism (backlash of the speed reducer, clearance of the shaft coupling, etc.) (for example, a gear speed reducer is employed) When it is done, the tooth surfaces to be contacted are switched). By this switching of the contact state, a state may occur where “the rotation angle Mka of the electric motor changes, but the pressing force Fba does not change”. That is, due to the play (gap) of the mechanical element, an invalid displacement (invalid rotation angle) occurs in the rotation angle Mka of the electric motor over the displacement mkm. The position where the ineffective displacement occurs (the rotation angle of the electric motor) changes due to wear of the friction member. Furthermore, the width of the ineffective displacement (the magnitude of mkm) also changes due to wear of the mechanical element (expansion of the gap). At the same time, the pressing force Fba is detected by a detection means (sensor), but the detected value includes an error. For example, the detection error is a zero point drift (offset), and is an error in the vertical axis direction (an error of the value fbd at the zero point of Fba) as shown in FIG.

  As described in Patent Documents 1 to 3, “differential value (change rate) of pressure sensor output (Patent Document 1)”, “decreasing gradient of pressing force (Patent Document 2)”, or “piston thrust is predetermined. If the reference position is determined based on the “piston position at the time when the value is equal to or less than the threshold value (Patent Document 3)”, an error may occur in the reference position due to the above-described invalid displacement. Furthermore, in the method described in Patent Document 3, the zero point drift of the pressing force detection means (pressing force sensor) can also affect the accuracy of determining the reference position.

  In general, when the reference position is determined based on the rate of change (differential value) or the decreasing gradient (dF / ds) of the pressing force Fba, it changes at the position mk1 where the value of Fba is constant. The condition of rate or decreasing gradient is satisfied, and the reference position is determined based on this position mk1. As a result, the calculated reference position may deviate from the original zero point position (true value of the reference position) mk0. Further, when the determination is made based on the threshold value of the output value Fba of the pressing force sensor, the reference position is determined based on the position at the time when the pressing force Fba becomes a predetermined value or less. However, in addition to the influence of the above-mentioned invalid displacement mkm, it is affected by the zero point drift fbd of the sensor. Therefore, a method for determining a reference position that can compensate for the effects of invalid displacement, detection error, etc. is eagerly desired.

  The present invention has been made to cope with the above-described problem, and an object of the present invention is to accurately set a reference position which is a position where a friction member (for example, a brake pad) starts to contact a rotating member (for example, a brake disc). It is to provide an electric braking device that can be determined.

  The electric braking device for a vehicle according to the present invention includes a braking operation amount acquisition means (BPA) for acquiring a braking operation amount (Bpa) of a braking operation member (BP) of the vehicle by a driver, and a transmission member (GSK or the like). Then, by transmitting the power of the electric motor (MTR), the friction member (MSB) is pressed against the rotating member (KTB) fixed to the wheel (WHL) of the vehicle, and braking torque is applied to the wheel (WHL). Control means for calculating the target energization amount (Imt) based on the braking means (BRK) to be generated and the braking operation amount (Bpa) and controlling the electric motor (MTR) based on the target energization amount (Imt) (CTL).

  This apparatus is characterized by a pressing force acquisition means (FBA) that acquires an actual pressing force (Fba) that is a force with which the friction member (MSB) actually presses the rotating member (KTB), and the electric motor (MTR). Position acquisition means (MKA) for acquiring the actual position (Mka), and the control means (CTL) changes the actual position (Mka) when the braking operation amount (Bpa) is decreased. The stiffness value (Gcq), which is the ratio (Fbh / Mkh) of the change amount (Fbh) of the actual pressing force (Fba) to the amount (Mkh), is successively calculated, and the stiffness value (Gcq) is a predetermined value (gcqx). ) At the time (t3, t7) when the above changes to less than the predetermined value (gcqx), the actual position (mkat3, mkat7) at that time is stored as a candidate position (Mkk), and the candidate position (Mkk) is In the remembered state, the continuation of the state where the rigidity value (Gcq) is less than the predetermined value (gcqx) is less than the gap equivalent values (skh, skt) corresponding to the gap of the transmission member (GSK, etc.). In a case where the candidate position (Mkk, mkat3) is forgotten and the candidate position (Mkk) is stored, the rigidity value (Gcq) is less than the predetermined value (gcqx). At the time (t8) when the gap equivalent value (skh, skt) is exceeded, the stored candidate position (Mkk, mkat7) is brought into contact with the friction member (MSB) and the rotating member (KTB). A reference position (pzr) to be started is determined, and the target energization amount (Imt) is calculated based on the reference position (pzr).

  According to the above configuration, when the rigidity value (corresponding to the spring constant of the braking means) changes from a predetermined value to less than the predetermined value, the reference position is not immediately determined, but in this state (rigidity value <predetermined value). The reference position is determined only after the value) exceeds the clearance equivalent value (the displacement or time corresponding to the clearance of the transmission member). For this reason, even if there is an ineffective displacement due to the gap between the transmission members such as the speed reducer, the reference position (position where the friction member starts to contact the rotating member) can be accurately determined. Further, since the rigidity value is calculated as a ratio of the pressing force change amount to the position change amount, the influence of the error of the acquiring means (particularly, the zero point drift of the pressing force acquiring means) can be compensated. Note that the gap (clearance) of the transmission member is caused by, for example, a gear backlash, a joint gap, or a bearing gap. Furthermore, these gaps can be enlarged by aging. For this reason, the gap equivalent value may be a value (a predetermined value set in advance) that allows for a gap in the power transmission member including aged wear.

  In the electric braking device for a vehicle according to the present invention, when the rigidity value (Gcq) changes from a predetermined value (gcqx) or more to less than the predetermined value (gcqx) (t3, t7), The actual pressing force (fbat3, fbat7) is stored as a candidate force (Fkk), and the stiffness value (Gcq) is less than the predetermined value (gcqx) when the candidate force (Fkk) is stored. If the continuation is less than the gap equivalent value (skh, skt) corresponding to the gap of the transmission member (GSK, etc.), the candidate force (Fkk, fbat3) is forgotten and the candidate force (Fkk) is stored. In a state where the rigidity value (Gcq) is less than the predetermined value (gcqx), the continuation of the state exceeds the gap equivalent values (skh, skt) at the time (t8), which is stored. Candidate force (Fkk, fbat7) is determined as a corrected pressing force (fzr) corresponding to a zero point drift of the pressing force acquisition means (FBA), and the target energization amount (fzr) is determined based on the corrected pressing force (fzr). Imt) may be configured to calculate.

  In general, the “force” is detected by measuring the strain of the strain generating body. In this distortion detection, drift of the detected value becomes a problem. According to the above configuration, the correction amount (correction pressing force) corresponding to the zero point drift of the pressing force is determined based on the actual pressing force in the “calculation process in which the reference position is determined” described above. For this reason, compensation for the zero point drift of the pressing force acquisition means can be reliably performed.

1 is an overall configuration diagram of an electric braking device for a vehicle according to an embodiment of the present invention. It is a schematic block diagram of an Oldham coupling. It is a functional block diagram for demonstrating the correction | amendment calculation block shown in FIG. It is a functional block diagram for demonstrating the synthetic | combination pressing force calculation block shown in FIG. FIG. 5 is a functional block diagram for explaining a rigidity characteristic calculation block shown in FIG. 4. It is a functional block diagram for demonstrating the stand-by position control block shown in FIG. It is a time chart for demonstrating the effect | action and effect of this invention. It is a figure for demonstrating the error of the reference position determination resulting from an invalid displacement.

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

<Overall Configuration of Electric Brake Device for Vehicle according to Embodiment of the Present Invention>
As shown in FIG. 1, a vehicle equipped with this electric braking device includes a braking operation member BP, an acceleration operation member AP, an electronic control unit ECU, a braking means (brake actuator) BRK, a pressing force acquisition means (pressing force sensor) FBA. , Position acquisition means (rotation angle sensor) MKA and storage battery BAT are provided.

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

  The braking operation member BP is provided with a braking operation amount acquisition means BPA. The operation amount (braking operation amount) Bpa of the braking operation member BP by the driver is acquired (detected) by the braking operation amount acquisition means BPA. As a braking operation amount acquisition means BPA, a sensor (pressure sensor) for detecting the pressure of a master cylinder (not shown), an operation force of the braking operation member BP, and / or a sensor for detecting a displacement amount (a brake pedal depression force sensor, Brake pedal stroke sensor) is adopted. Accordingly, the braking operation amount Bpa is calculated based on at least one of the master cylinder pressure, the brake pedal depression force, and the brake pedal stroke. The braking operation amount Bpa is input to the electronic control unit ECU.

  The acceleration operation member (for example, accelerator pedal) AP is a member that the driver operates to accelerate the vehicle. The acceleration operation member AP is provided with acceleration operation amount acquisition means (for example, a stroke sensor, a throttle opening sensor) APA. The braking means BRK can also be controlled based on the acceleration operation amount Apa. The operation amount (acceleration operation amount) Apa of the acceleration operation member can be calculated based on at least one of the operation force of the acceleration operation member and the displacement amount (for example, the stroke of the accelerator pedal). Further, the throttle opening of the engine can be adopted as Apa. The acceleration operation amount Apa is input to the electronic control unit ECU.

  At least one of the braking operation amount Bpa and the acceleration operation amount Apa is calculated by another electronic control unit (for example, an electronic control unit for steering control, an electronic control unit for powertrain control), or The calculated value (signal) can be transmitted to the ECU via the communication bus.

  The electronic control unit ECU is programmed with control means (control algorithm) CTL for controlling the braking means BRK, and controls the BRK based on the CTL. The storage battery (battery) BAT is a power source that supplies power to BRK, ECU, and the like.

  The position acquisition means (for example, angle sensor) MKA detects the actual position (for example, actual rotation angle) Mka of the rotor (rotor) of the electric motor MTR that is the power source of the BRK. The position acquisition means MKA is provided inside the electric motor MTR. The actual position Mka is input to the electronic control unit ECU (in particular, the control means CTL).

  The pressing force acquisition means FBA acquires (detects) the reaction force (reaction) of the force (pressing force) Fba that the pressing member PSN presses the friction member MSB. Specifically, in the pressing force acquisition unit FBA, the pressing force Fba is based on an electrical change (for example, a voltage change) caused by a displacement (that is, a strain) generated when a force is applied, such as a strain gauge. Detected. The pressing force acquisition means FBA is provided between the bolt member BLT and the caliper CPR. For example, the pressing force acquisition means FBA is fixed to the caliper CRP, and the force received by the pressing member PSN from the friction member MSB is acquired as the pressing force Fba. The pressing force Fba is input to the electronic control unit ECU (particularly, the control means CTL) via an analog / digital conversion means (AD conversion means) ADH. The FBA detection signal is an analog value, but is converted into a digital value by the analog / digital conversion means ADH and input to the electronic control unit ECU. At this time, the resolution (least significant bit, LSB: Least Significant Bit) of the pressing force Fba is determined by the number of bits of the conversion means ADH.

<Control means CTL>
The control means CTL includes a target pressing force calculation block FBT, an indicated energization amount calculation block IST, a correction calculation block HSI, a combined pressing force calculation block FBX, a pressing force feedback control block IPT, a standby position control block ICT, and an energization amount adjustment calculation. It consists of block IMT. The control means (control program) CTL is programmed in the electronic control unit ECU.

  In the target pressing force calculation block FBT, the target pressing force Fbt of each wheel WHL is calculated based on the braking operation amount Bpa and the preset target pressing force calculation characteristic (calculation map) CHfb. The target pressing force Fbt is a target value of the pressing force that is a force with which the friction member (brake pad) MSB presses the rotating member (brake disc) KTB in the electric braking means BRK. When Bpa is “0” or more and less than the predetermined operation amount bp0, Fbt is calculated as “0”, and when Bpa is more than the predetermined operation amount bp0, Fbt is simply increased as Bpa increases. Calculated. The predetermined value bp0 corresponds to “play” of the brake pedal BP. Here, “play” refers to a range provided in an operation mechanism (man-machine interface), in which an operation does not affect an actual operation, or a gap.

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

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

  In the correction calculation block HSI, zero point correction of the pressing force acquisition unit FBA (for example, a pressing force sensor) and the position acquisition unit MKA (for example, a rotation angle sensor) is performed. A signal from the FBA (pressing force Fba) and a signal from the MKA (actual position Mka) are input to the correction calculation block HSI, the zero point is corrected, and the corrected actual pressing force (corrected pressing force) is corrected. Pressure) Fbc and corrected actual position (corrected position) Mkc are output. Here, in the case of the pressing force acquisition means FBA, the zero point represents a detection value (acquisition value) in a state where the pressing force (MSB is a force that presses KTB) is not actually generated. In the case of MKA, it represents a reference position that is a boundary of whether or not a pressing force is generated between MSB and KTB (that is, whether MSB and KTB are in contact). Here, the deviation (deviation) from the zero point of the output value of the FBA is referred to as zero point drift. That is, the FBA zero point drift is a deviation (deviation from the value “0”) in a situation where no pressing force is actually generated.

  In the combined pressing force calculation block FBX, based on the braking operation amount Bpa, the actual position (after correction) Mkc of the electric motor MTR, and the actually generated pressing force (corrected pressing force actual value) Fbc, The combined pressing force Fbx is calculated. Specifically, the estimated value Fbe of the pressing force is calculated based on the rotor position (rotation angle) Mkc of the electric motor, and the actual pressing force value Fbc acquired by the pressing force acquisition unit FBA and the estimated pressing force value Fbe. The combined pressing force Fbx is calculated in consideration of the respective contribution degrees (coefficients for determining the influence degree) Ka1 and Ke2. In other words, the combined pressing force Fbx corresponds to a force (pressing force) that the MSB calculated based on two different detection signals (Fbc, Mkc) is pressed against the KTB.

  The estimated pressing force Fbe is estimated based on the rotor position Mkc (corrected Mka) and the rigidity value Gcp of the braking means BRK (Fbe = Mkc × Gcp). The contribution (first contribution) Ka1 regarding the actual pressing force value Fbc (corrected Fba) and the contribution (second contribution) Ke2 regarding the estimated pressing force Fbe are based on the braking operation amount Bpa. Calculated. The first and second contributions Ka1 and Ke2 are coefficients that determine the influence degree (degree of contribution) of Fbc and Fbe in the calculation of the combined pressing force Fbx. The first contribution Ka1 increases as the braking operation amount Bpa increases, and the second contribution Ke2 decreases as Bpa increases. That is, in the calculation of the combined pressing force Fbx, when the braking operation amount Bpa is small, the influence degree of the estimated pressing force Fbe calculated based on the position Mkc of the electric motor is larger than the influence degree of the actual pressing force value Fbc. As Bpa increases, the influence degree of Fbc increases and the influence degree of Fbe decreases.

  In the pressing force feedback control block IPT, the pressing force feedback energization amount Ipt is calculated based on the target pressing force (target value) Fbt and the combined pressing force Fbx. The command energization amount Ist is calculated as a value corresponding to the target pressing force Fbt, but an error (steady error) may occur between the target pressing force Fbt and the pressing force Fbx due to fluctuations in the efficiency of the electric braking means BRK. is there. The pressing force feedback energization amount Ipt is calculated based on a deviation (pressing force deviation) ΔFb between the target pressing force Fbt and the combined pressing force Fbx, and a preset calculation characteristic (calculation map) CHp, and the above error is calculated. Decided to decrease. That is, based on the calculation map CHp, the pressing force feedback energization amount Ipt is calculated to increase as the pressing force deviation ΔFb (= Fbt−Fbx) increases.

  In the standby position control block ICT, the pressing member when the braking operation member BP is not operated by the driver or when it is operated slightly (the braking torque is not generated enough to decelerate the vehicle). A target energization amount Ict for controlling the position of the PSN is calculated. This PSN position control is referred to as standby position control. In the standby position control, the position of the pressing member PSN during non-braking (ie, the position of the MTR) is controlled, and as a result, the gap between the friction member MSB and the rotating member KTB (ie, the drag state of the MSB) is adjusted. The In the standby position control block ICT, a target energization amount Ict for executing the standby position control is calculated based on the braking operation amount Bpa and the acceleration operation amount Apa. The target energization amount (standby energization amount) Ict of the standby position control is determined so that the pressing member PSN is further away from the rotation member KTB when the acceleration operation amount Apa is large (when the vehicle acceleration is large). Then, after the acceleration operation amount Apa is returned to “0 (non-operation)”, the standby energization amount Ict is determined so that the PSN approaches KTB as the braking operation member Bpa increases.

  In the energization amount adjustment calculation block IMT, a target energization amount Imt that is a final target value of the electric motor MTR is calculated. The command energization amount Ist, the pressing force feedback energization amount Ipt, and the standby energization amount Ict are adjusted to calculate the target energization amount Imt. The target energization amount Imt is a final energization amount target value for controlling the output of the electric motor MTR. The rotation direction of the electric motor MTR (forward rotation direction in which the pressing force increases or reverse rotation direction in which the pressing force decreases) is determined based on the sign of the target energization amount Imt (positive or negative value), and the target energization amount Imt is large. The output (rotational power) of the electric motor MTR is controlled based on the value (absolute value).

  The energization amount adjustment calculation block IMT includes a selection calculation block SNT, and selection (switching) between pressing force feedback control (Ist, Ipt) and position feedback control (Ict) is performed. When the pressing force feedback control is selected (when the driver requests vehicle deceleration), the selection calculation block SNT adds the pressing force feedback energization amount Ipt to the command energization amount Ist, and the target The energization amount Imt (= Ist + Ipt) is calculated. On the other hand, when position feedback control is selected (when the driver does not request vehicle deceleration), the standby energization amount Ict is calculated as the final target energization amount Imt (= Ict) in SNT. .

<Electric braking means BRK>
In the electric braking apparatus according to the embodiment of the present invention, the generation and adjustment of the braking torque of the vehicle wheel WHL is performed by the electric motor MTR. The electric brake means (brake actuator) BRK includes a brake caliper (eg, floating caliper) CPR, a rotating member (eg, brake disc) KTB, a friction member (eg, brake pad) MSB, an electric motor MTR, and a drive means (MTR). Electrical circuit for driving) DRV, joint member (for example, Oldham joint) OLD, reduction gear GSK, rotation / linear motion converter (for example, screw member) NJB, pressing force acquisition means FBA, position acquisition means MKA, and It is comprised by the energization amount acquisition means IMA.

  The brake means BRK is provided with a known brake caliper CPR and a friction member MSB as in the known brake device. When the friction member MSB is pressed against the known rotary member KTB, a frictional force is generated, and a braking torque is applied to the wheel WHL to generate a braking force.

  The brake caliper CPR is a floating caliper and is configured to sandwich a rotating member (brake disk) KTB via two friction members (brake pads) MSB. Within the caliper CPR, the pressing member PSN is slid and moved forward or backward toward the rotating member KTB. The pressing member (brake piston) PSN presses the friction member MSB against the rotating member KTB to generate a frictional force.

  The friction member (for example, a brake pad with a back plate) MSB can be replaced when worn. For this reason, the MSB and PSN are not fixed (not joined together). That is, the friction member (brake pad with back plate) MSB and the pressing member (piston) PSN are separated. When the braking torque is increased, the pressing member PSN presses the back plate portion of the friction member MSB, so that the MSB advances toward the rotating member (brake disc) KTB. When the braking torque is reduced, the MSB moves backward in the direction away from the KTB due to the reaction force generated due to the rigidity of the entire BRK (CPR rigidity and MSB rigidity).

  As the electric motor MTR, a motor with a brush or a brushless motor is employed. In the rotation direction of the electric motor MTR, the forward rotation direction corresponds to the direction in which the pressing member PSN approaches the rotating member KTB (the direction in which the pressing force increases and the braking torque increases), and the reverse rotation direction corresponds to the pressing member PSN. Corresponds to the direction away from the rotating member KTB (the direction in which the pressing force decreases and the braking torque decreases). The output of the electric motor MTR is determined based on the target energization amount Imt calculated by the control means CTL. Specifically, when the sign of the target energization amount Imt is positive (+: plus) (Imt> 0), the electric motor MTR is driven in the forward rotation direction, and the sign of Imt is negative (-: minus). When (Imt <0), the electric motor MTR is driven in the reverse direction. Further, the rotational power of the electric motor MTR is determined based on the magnitude (absolute value) of the target energization amount Imt. That is, the larger the absolute value of the target energization amount Imt, the larger the output torque of the electric motor MTR, and the smaller the absolute value of the target energization amount Imt, the smaller the output torque.

  The drive means (electric circuit for driving the electric motor MTR, drive circuit) DRV controls the energization amount (finally the current value) to the electric motor MTR based on the target energization amount (target value) Imt. Is done. Specifically, the driving unit DRV includes a bridge circuit using a plurality of switching elements (power transistors such as MOS-FETs and IGBTs). These elements are driven based on the target energization amount Imt of the electric motor, and the output of the electric motor MTR is controlled. Specifically, the rotation direction and output torque of the electric motor MTR are adjusted by switching the energization / non-energization state of the switching element.

  The output (rotational power) of the electric motor MTR is transmitted to the pressing member PSN in the order of the joint member OLD, the reduction gear GSK, and the rotation / linear motion converter (screw member) NJB. Then, the pressing member (brake piston) PSN is moved forward / backward toward the rotating member (brake disc) KTB. Thereby, the force (pressing force) by which the friction member (brake pad) MSB presses the rotating member KTB is adjusted. Since rotating member KTB is fixed to wheel WHL, a frictional force is generated between friction member MSB and rotating member KTB, and a braking force is generated on wheel WHL.

  The joint member OLD is a shaft joint for absorbing the eccentricity (axis deviation) between the rotation shaft of the electric motor MTR (hereinafter referred to as the motor shaft) and the rotation shaft (input shaft) of the reduction gear GSK. A joint is adopted. In Oldham coupling, the eccentricity of two shafts (motor shaft and input shaft) with different shaft centers is absorbed by the sliding of the fitting between the disk protrusion (key) and the slider groove (key groove), and the rotational power (Rotational motion) is transmitted.

  The speed reducer GSK reduces the rotational speed of the power of the electric motor MTR and outputs it to the rotary / linear motion converter NJB (specifically, the bolt member BLT). That is, the rotational output (torque) of the electric motor MTR is increased according to the reduction ratio of the reduction gear GSK, and the rotational force (torque) of the bolt member BLT is obtained. For example, the reduction gear GSK is configured by a small diameter gear SKH and a large diameter gear DKH. Further, as the reduction gear GSK, not only a gear transmission mechanism but also a winding transmission mechanism such as a belt or a chain, or a friction transmission mechanism can be adopted.

  The rotation / linear motion converter NJB is a feed screw, and includes a bolt member BLT and a nut member NUT. The bolt member BLT is fixed to the output shaft of the reduction gear GSK (for example, the rotation shaft of the large diameter gear DKH). Then, the rotational power of the bolt member BLT is converted into linear power (thrust) via the nut member NUT and transmitted to the pressing member PSN.

  When the screw member NJB is constituted by a trapezoidal screw (sliding screw in which power is transmitted by “sliding”), the nut member NUT is provided with a female screw (inner screw), and the bolt member BLT is provided with a male screw. (Outside screw) is provided. Then, the female screw of the nut member NUT and the male screw of the bolt member BLT are screwed together. The rotational power (torque) transmitted from the reduction gear GSK is transmitted as linear power (thrust) of the pressing member PSN via the screw member NJB (male screw and female screw screwed together).

  As the screw member NJB, a rolling screw (such as a ball screw) in which power transmission is performed by “rolling” may be employed instead of the sliding screw. In this case, the nut member NUT and the bolt member BLT are provided with a thread groove (ball groove), and a ball (steel ball) is fitted into the thread groove to operate as a rotation / linear motion conversion mechanism.

  The electric motor drive circuit DRV includes an energization amount acquisition unit (for example, a current sensor) IMA that detects an actual energization amount (for example, current that actually flows through the electric motor) Ima. Further, the electric motor MTR is provided with position detection / acquisition means (for example, an angle sensor) MKA that detects an actual position (for example, a rotation angle) Mka of the rotor (rotor). Further, a pressing force acquisition means (for example, a pressing force sensor) FBA is provided in order to acquire (detect) a force (actual pressing force) Fba that actually presses the rotating member KTB by the friction member MSB. The pressing force acquisition means FBA is fixed to the caliper CRP, and the force received by the pressing member PSN from the friction member MSB is acquired as the pressing force Fba.

  In the above configuration, the pressing force acquisition unit FBA directly acquires (detects) the pressing force Fba. Since the specifications of the braking means BRK (for example, GSK gear ratio, NJB lead, etc.) are known, the FBA is the “force” of the movable member existing in the power transmission path from the electric motor MTR to the friction member MSB. The state quantity "can be acquired as the actual pressing force value (actual pressing force) Fba. Specifically, the “state quantity related to the force” is at least one of the output torque of the electric motor MTR, the output torque of the GSK, the thrust of the NJB, the thrust of the PSN, and the pressing force of the MSB. The actual pressing force value Fba can be indirectly obtained (calculated) based on the state quantity (single or plural state quantities) and the specifications of the BRK.

  Similarly, since the specifications of the brake means BRK are known, the position acquisition means MKA determines the “state quantity related to position” of the movable member existing in the power transmission path from the electric motor MTR to the friction member MSB. Actual position) Can be acquired as Mka. Specifically, the “state quantity related to the position” is at least one of the position of the electric motor MTR, the position of the GSK, the position of the NJB, the position of the PSN, and the position of the MSB. The position Mka can be indirectly obtained (calculated) based on the quantity (single or plural state quantities) and the BRK specifications (GSK gear ratio, NJB lead, etc.). That is, the MKA can be obtained indirectly as well as directly obtaining the position Mka of the electric motor.

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

  In the braking means BRK configured as described above, when the pressing force is decreased, there is a section (invalid displacement section) in which a state in which the pressing force does not decrease is generated although the position of the electric motor changes. This invalid displacement is caused by a gap (backlash) of a power transmission member (joint member OLD, reduction gear GSK, etc.) from the electric motor MTR to the pressing force acquisition means FBA. Specifically, the gap is generated in the power transmission member due to switching of the portion (pressure receiving surface) that receives the reaction of the pressing force. In the joint member (Oldham joint), there is a gap between the key (convex portion) and the key groove (concave portion), and in the reduction gear (reduction gear), there is backlash. When the reaction of the pressing force is received, when one surface (the key of the Oldham coupling and the surface of the key groove, the tooth surface of the reduction gear) comes into contact, the friction loss (torque loss) of the electric motor MTR is canceled. Is in contact with the other surface opposite to the one surface (a surface different from the one contact surface). The displacement (change in position) of the electric motor corresponding to the gap where the contact surface is switched corresponds to the invalid displacement.

<Oldham fitting OLD>
Next, with reference to FIG. 2, the clearance gap in Oldham coupling OLD is demonstrated in detail. The Oldham joint OLD is a joint that transmits rotational power by sliding the fitting between the protrusion (key) of the disk and the groove (key groove) of the slider. The Oldham coupling OLD includes an input disk HBM, a slider (intermediate disk) SLD, and an output disk HBI. The protrusions of the disks HBM and HBI slide along the groove of the slider SLD to absorb the eccentricity of two shafts (motor shaft and input shaft) having different shaft centers, and transmit rotational power (rotational motion). Is done.

  As shown in FIG. 2A, the input disk HBM is fixed to the output shaft (motor shaft) of the electric motor MTR. A key (protrusion) is provided on the surface of the input disk HBM opposite to the surface on which the motor shaft is fixed. The slider SLD is provided with a key groove (depression) so as to engage with the key of the input disk HBM. On the opposite surface of the slider SLD where the key groove is provided, another key groove is provided perpendicular to the key groove. The output disk HBI is provided with a key (protrusion) so as to engage with the key groove (depression) of the slider SLD, and is fixed to the shaft (input shaft) of the speed reducer GSK (small-diameter gear SKH) on the back side of the surface having the key. Is done. That is, the HBM, SLD, and HBI are meshed so that the protrusion of the input disk HBM and the protrusion of the output disk HBI are perpendicular to each other. In Oldham coupling OLD, the keys of HBM and HBI slide along the keyway of slider SLD, so that the eccentricity between the output shaft (motor shaft) of electric motor MTR and the input shaft of the speed reducer is absorbed.

  When a relatively large torque is applied to the Oldham coupling OLD, the HBM and HBI keys and the SLD keyway are deformed or worn, increasing backlash (contact surface clearance between machine elements in the direction of motion). There may be cases. FIG. 2B is a cross-sectional view of a fitting portion between the input disk HBM and the slider SLD. When wear or the like has not occurred, the key and the key groove are fitted with a slight gap. However, when the gap increases due to wear or the like, an invalid displacement (invalid rotation angle) occurs in which the GSK input shaft does not rotate even if the motor output shaft rotates in the rotational direction of the Oldham coupling OLD. An invalid displacement in the Oldham coupling OLD is one cause of the occurrence of a state in which “Fba does not decrease even if Mka is reduced” when the pressing force (ie, braking torque) is reduced (the other cause is the back of GSK Rush).

<Correction calculation block HSI>
Next, an embodiment of the correction calculation block HSI will be described with reference to the functional block diagram of FIG. In the correction calculation block HSI, the zero point of the position acquisition unit MKA (for example, a rotation angle sensor) and the pressing force acquisition unit FBA (for example, a pressing force sensor) is corrected. The zero point of the position acquisition means MKA is a reference position that is a boundary of whether or not a pressing force is generated between the MSB and the KTB (that is, whether or not the MSB and the KTB are in contact). Further, the zero point of the pressing force acquisition means FBA is a value representing a state in which the pressing force (the force with which the MSB presses KTB) is not actually generated. Here, the deviation (deviation, offset) from the zero point of the FBA is referred to as zero point drift.

  The correction calculation block HSI includes a position change amount calculation block MKH, a pressing force change amount calculation block FBH, a first stiffness value calculation block GCQ, a candidate position / candidate force calculation block MFK, a reference position calculation block PZR, a position correction calculation block MKC, The correction pressure calculation block FZR and the pressure correction calculation block FBC are used.

  In the position change amount calculation block MKH, the position change amount Mkh is calculated based on the actual position Mka of the electric motor. Specifically, the past value of Mka (value in the past calculation cycle) mka [k] is stored, compared with the current value of Mka (value in the current calculation cycle) mka [g], and the deviation is Calculated as the position change amount Mkh. That is, the position change amount Mkh is calculated according to Mkh = mka [k] −mka [g]. Here, the past value mka [k] is a calculated value one cycle or a plurality of cycles before the current (current) in the calculation cycle, and is a predetermined time from the current value (current value) mka [g]. (Predetermined value) This is the previous calculation value by th0. That is, in the calculation cycle, a predetermined cycle (fixed value) has passed from the past value mka [k] to the current value mka [g].

  In the pressing force change amount calculation block FBH, the pressing force change amount Fbh is calculated based on the pressing force actual value Fba. Specifically, in each calculation cycle, the Fba past value fba [k] corresponding to the Mka past value mka [k] and the Fba current value fba [g] corresponding to the Mka current value mka [g]. Are compared, and the deviation is calculated as the pressing force change amount Fbh. That is, the pressing force change amount Fbh is calculated according to Fbh = fba [k] −fba [g]. mka [k] and fba [k] are values in the same calculation cycle, and mka [g] and fba [g] are values in the same calculation cycle.

  In the first stiffness value calculation block GCQ, a first stiffness value (corresponding to an actual stiffness value) Gcq is calculated based on the position change amount Mkh and the pressing force change amount Fbh. Specifically, the change amount Fbh of the pressing force with respect to the change amount Mkh of the position is calculated as the first rigidity value Gcq (= Fbh / Mkh). The stiffness value (actual value) Gcq is a value corresponding to the caliper CPR and the spring constant of the series spring of the friction member MSB. Therefore, the pressing force change amount (for example, the pressing force time change amount) Fbh is divided by the position change amount (for example, the position time change amount) Mkh to calculate the first stiffness value Gcq.

  In the candidate position / candidate force calculation block MFK, when the electric motor MTR is reversely rotated (that is, Bpa is decreased), based on the actual position Mka, the actual pressing force Fba, and the first rigidity value Gcq, A position (reference position) candidate (candidate position) Mkk serving as a reference for the position (rotation angle) of the electric motor and a candidate (candidate force) Fkk for correcting the pressing force are calculated. Specifically, Mka and Fba at the time of transition from the state where the first stiffness value Gcq is equal to or greater than the predetermined value gcqx (the state before one computation cycle) to the state less than gcqx (the current computation cycle) are candidates. The position Mkk and the candidate force Fkk are respectively stored. That is, in the calculation cycle of Gcq, the previous value (calculation value in the previous calculation cycle) gcq [g-1] is equal to or greater than gcqx, and the current value (calculation value in the current calculation cycle) gcq [g] Is less than gcqx, the current value mka [g] of the electric motor position is calculated as the candidate position Mkk, and the current value fba [g] of the pressing force is calculated and stored as the candidate force Fkk. Therefore, the pressing force corresponding to the candidate position Mkk is stored as the candidate force Fkk.

  In the reference position calculation block PZR, the reference position pzr is determined based on the actual position Mka, the first stiffness value Gcq, and the candidate position Mkk. Specifically, the reference position calculation block PZR monitors whether or not the first stiffness value Gcq is less than a predetermined value gcqx (Gcq <gcqx) from the time when the candidate position Mkk is determined. When the state of “Gcq <gcqx” is continued beyond the displacement (gap equivalent value) skh corresponding to the gap of the power transmission member GSK or the like in Mka (that is, in the corresponding calculation cycle), the candidate position Mkk Is determined as the reference position pzr. However, if the state of “Gcq <gcqx” is not continued beyond the gap equivalent value (displacement) skh, Mkk is forgotten (reset) when Gcq becomes equal to or greater than gcqx.

  In the reference position calculation block PZR, the value at the previous braking is set as the reference position pzr until the reference position pzr is newly updated by the candidate position Mkk. Here, the clearance equivalent value skh is a value corresponding to a mechanical clearance in the power transmission path of the BRK, and is a threshold set in advance as a design value.

  In the position correction calculation block MKC, the Mka acquired by the MKA is corrected by the reference position pzr, and the corrected electric motor position (corrected position) Mkc is calculated. Mka at the time point set as the reference position pzr is set to the zero point, and the correction position Mkc is calculated. In other words, at the corrected position Mkc, the reference position pzr, which is a boundary of whether or not the pressing force is generated between the MSB and KTB, is set as the zero point position of the position acquisition means (rotation angle sensor) MKA. .

  In the corrected pressing force calculation block FZR, the corrected pressing force fzr corresponding to the zero point drift of Fba acquired by the FBA is calculated based on the actual position Mka, the first stiffness value Gcq, and the candidate force Fkk. Similar to the method for determining the reference position pzr, the actual pressing force when the first stiffness value Gcq transitions from a state where the first stiffness value Gcq is equal to or greater than the predetermined value gcqx (a state before one computation cycle) to a state less than gcqx (the current computation cycle). Fba is stored as a candidate force (candidate of corrected pressing force) Fkk, and when the state of “Gcq <gcqx” continues beyond the gap equivalent value skh in Mka, the candidate force Fkk is corrected to the corrected pressing force fzr. Adopted as Therefore, the reference position pzr and the correction pressing force fzr are determined simultaneously (in the same calculation cycle). Therefore, the pressing force corresponding to the reference position pzr is determined as the corrected pressing force fzr. When the state of “Gcq <gcqx” is not continued beyond the gap equivalent value skh, the correction candidate force Fkk is temporarily forgotten (reset) when Gcq becomes equal to or greater than gcqx.

  In the pressing force correction calculation block FBC, the actual pressing force Fba is corrected based on the corrected pressing force fzr, and the corrected pressing force (corrected pressing force) Fbc is calculated. Since the corrected pressing force fzr corresponds to the zero point drift of the pressing force acquisition means FBA, error correction is performed by subtracting the corrected pressing force fzr from the actual pressing force Fba, and the corrected pressing force Fbc is calculated.

  There may be a phase difference between the respective detection signals between Mka and Fba. Therefore, in the correction calculation block HSI, the correction calculation process can be executed only when the Mka changing speed (electric motor speed) dMka is equal to or less than the predetermined speed (predetermined value) dmk1. That is, the reference position pzr and the corrected pressing force fzr can be determined only when the Bpa operating speed dBpa is moderate (less than the predetermined value dbp1).

  When the electric motor MTR is rotated in the reverse direction and Fba is decreased, a speed limit (limit value dmk2) can be provided in the MTR within a predetermined region approaching the reference position pzr. Alternatively, the MTR can be returned toward the zero point at a preset constant speed dmk3. That is, even when Bpa is suddenly returned, the speed can be limited as the PSN approaches the reference position pzr. As a result, the influence of the above phase difference can be compensated.

  Further, since there is a mutual relationship (proportional relationship when the speed of the electric motor is constant) between time and the displacement of the electric motor, the gap equivalent value is replaced with the displacement threshold value skh, A time threshold skt may be employed. That is, it is determined whether or not the state of “Gcq <gcqx” is continued beyond the time skt under the condition related to the gap equivalent value.

  When the rigidity value Gcq (corresponding to the spring constant of BRK) becomes less than the predetermined value gcqx, the reference position pzr is not immediately determined, but this state (Gcq <gcqx state) is the gap equivalent values skh, skt The reference position pzr is determined for the first time. For this reason, the reference position pzr can be accurately determined even if there is an ineffective displacement due to the gap between the power transmission members such as the speed reducer. Further, since the stiffness value (actual value) Gcq is calculated as a ratio of the pressing force change amount Fbh to the position change amount Mkh, the influence of the error of the obtaining means (sensor) (particularly, the zero point drift of the FBA) is compensated. obtain. The gap (clearance) of the power transmission member is caused by, for example, a gear backlash, a joint gap, or a bearing gap. Furthermore, these gaps can be enlarged by aging. For this reason, the clearance equivalent values skh and skt can be values (predetermined predetermined values) that allow for the clearance of the power transmission member including aged wear.

  The “force” is detected by measuring the strain of the strain generating body (displacement that occurs when the force is received). In this distortion detection, drift (offset) of the detected value becomes a problem. The actual pressing force Fba at the candidate position Mkk is stored, and the zero point drift value fzr is determined based on the actual pressing force Fba at the time when the reference position pzr is determined by satisfying the gap equivalent value condition. For this reason, compensation for the zero point drift of the FBA can be reliably performed.

<Composite pressure calculation block FBX>
Next, an embodiment of the combined pressing force calculation block FBX will be described with reference to FIG. The combined pressing force calculation block FBX includes a first contribution calculation block KA1, a second contribution calculation block KE2, and a second stiffness value calculation block GCP.

  In the first contribution calculation block KA1, the first contribution Ka1 is calculated based on the braking operation amount Bpa. The first contribution Ka1 is a coefficient that determines the degree of influence of the actual pressing force value (corrected actual pressing force) Fbc in the calculation of the combined pressing force Fbx. The first contribution Ka1 is calculated based on the braking operation amount Bpa and the calculation characteristic (calculation map) CHka. When Bpa is less than the predetermined value ba1, Ka1 is calculated as “0”, and when Bpa is equal to or greater than the predetermined value ba1 and less than the predetermined value ba2 (> ba1), Ka1 increases according to the increase in Bpa. It is increased (simply increased) from “0” to “1”. When Bpa is greater than or equal to the predetermined value ba2, Ka1 is calculated as “1”. Here, when Ka1 = 0, Fbc is not used in the calculation of Fbx.

  In the second contribution calculation block KE2, the second contribution Ke2 is calculated based on the braking operation amount Bpa. The second contribution degree Ke2 is a coefficient that determines the degree of influence of the estimated pressing force (estimated pressing force) Fbe (the pressing force estimated based on Mkc) in the calculation of the combined pressing force Fbx. The second contribution degree Ke2 is calculated based on the braking operation amount Bpa and the calculation characteristic (calculation map) CHke. When Bpa is less than the predetermined value be1, Ke2 is calculated as “1”. When Bpa is equal to or greater than the predetermined value be1 and less than the predetermined value be2 (> be1), Ke2 increases according to the increase in Bpa. It is decreased (simple decrease) from “1” to “0”. When Bpa is equal to or greater than the predetermined value be2, Ke2 is calculated as “0”. Here, when Ke2 = 0, Fbe is not used in the calculation of Fbx.

  In the second stiffness value calculation block GCP, the second stiffness value Gcp is calculated based on the braking operation amount Bpa. The second rigidity value Gcp corresponds to the rigidity (spring constant) of the entire braking means. That is, Gcp represents a spring constant as a series spring of the caliper CPR and the friction member MSB. The stiffness value (estimated value) Gcp is calculated based on the braking operation amount Bpa and the stiffness characteristic (calculation map) CHgc. Here, CHgc is a characteristic for estimating the rigidity value Gcp based on Bpa. When Bpa is less than the predetermined value bg1, Gcp is calculated as the predetermined value gc1, and when Bpa is equal to or larger than the predetermined value bg1 and less than the predetermined value bg2 (> bg1), Gcp is predetermined as Bpa increases. The value is increased (simply increased) from the value gc1 to a predetermined value gc2 (> gc1). When Bpa is equal to or greater than the predetermined value bg2, Gcp is calculated as the predetermined value gc2.

  Based on the second stiffness value Gcp and the actual position (after correction) Mkc of the electric motor MTR, the estimated pressing force value Fbe is calculated. The estimated pressing force value Fbe is a pressing force estimated from Mkc. Specifically, the second rigidity value Gcp representing the spring constant of the entire braking means is multiplied by the actual position (rotation angle) Mkc of the electric motor MTR to calculate the estimated pressing force Fbe.

  Based on the actual pressing force value (actual pressing force after correction) Fbc and the first contribution Ka1, an actual value component Fbxa that is an Fbc component in the combined pressing force Fbx is calculated. Fbxa is a component of the actual pressing force value Fbc in which the degree of influence is considered by Ka1. Specifically, it is determined by multiplying the actual pressing force value Fbc by the coefficient Ka1 (that is, Fbxa = Ka1 × Fbc). An estimated value component Fbxe, which is an Fbe component in the combined pressing force Fbx, is calculated based on the pressing force estimated value (pressing force estimated based on Mkc) Fbe and the second contribution degree Ke2. Fbxe is a component of the estimated pressing force Fbe in which the degree of influence is considered by Ke2. Specifically, it is determined by multiplying the estimated pressing force Fbe by a coefficient Ke2 (that is, Fbxe = Ke2 × Fbe = Ke2 × Gcp × Mkc). Then, the component (actual value component) Fbxa based on the actual pressing force and the component (estimated value component) Fbxe based on the estimated pressing force are added to calculate the combined pressing force Fbx (that is, Fbx = Fbxa + Fbxe = Ka1). * Fbc + Ke2 * Fbe). Therefore, the combined pressing force Fbx is a pressing force in which the influence degree of Fbc and Fbe is added according to the magnitude of Bpa.

  The actual pressing force (before correction) Fba is detected by an element (strain detection element) that detects “strain (deformation when force is applied)”. In general, an analog signal is transmitted from the strain detection element, and is subjected to analog-digital conversion (AD conversion) and is taken into the electronic control unit ECU. Since the actual pressing force Fba before correction is input to the ECU via the analog / digital conversion means ADH, the resolution (resolution) of pressing force detection depends on the performance (resolution) of AD conversion. On the other hand, the actual position (rotation angle) of the electric motor is taken into the ECU as a digital signal from the Hall IC or the resolver. Further, the output of the electric motor is decelerated by GSK or the like and converted into a pressing force. Therefore, the pressing force estimated value Fbe calculated from the position Mka of the electric motor acquired by the position acquisition means MKA is greater than the pressing force actual value Fba acquired by the pressing force acquisition means FBA. High resolution (resolution). On the other hand, the estimated pressing force Fbe is calculated based on the stiffness (spring constant) Gcp of BRK. Since the second stiffness value Gcp varies depending on the wear state of the friction member MSB, the actual pressing force value Fba is more reliable than the estimated pressing force value Fbe (the error from the true value is small).

  Further, the characteristic of the pressing force Fba with respect to the position Mka of the electric motor (that is, the change in the spring constant of the entire braking device) is non-linear and has a “convex downward” shape (see FIG. 8). For this reason, in the region where the pressing force Fba is large, the detection sensitivity of the pressing force Fba (the amount of change in the pressing force with respect to the displacement) is sufficiently high, so that the actual pressing force value Fba can be used for the pressing force feedback control. However, since the detection sensitivity of the actual pressing force value Fba is low in the region where the pressing force is small, the estimated pressing force value Fbe is used for the pressing force feedback control in addition to (or instead of) the actual pressing force value Fba. It is desirable.

  From the above knowledge, when the braking operation amount Bpa is small, the first contribution Ka1 is calculated to a relatively small value, and the second contribution Ke2 is calculated to a relatively large value. As a result, in the region where the pressing force requiring a small adjustment of the braking torque is small (that is, the region where the braking operation amount is small and the braking torque is small), the resolution of detecting the pressing force (the least significant bit, LSB: Least Significant Bit) is improved, and precise pressing force feedback control can be performed. When the braking operation amount Bpa is large, Ka1 is calculated to a relatively large value, Ke2 is calculated to a relatively small value, and the estimated pressing force estimated from Mkc (that is, Mka) The influence degree of Fbe is decreased, and the influence degree of the actually detected pressing force actual value Fbc (that is, Fba) is increased. As a result, in a region where the pressing force required to have a constant relationship between the vehicle deceleration and the braking operation amount Bpa is large (that is, a region where the braking operation amount is large and the braking torque is large), the reliability is high (that is, The pressing force feedback control (based on the pressing force with a small error from the true value) can be executed.

  Furthermore, when the braking operation amount Bpa is smaller than the predetermined operation amount (predetermined value) ba1, the first contribution Ka1 can be set to “0 (zero)”. When the braking operation amount Bpa is larger than the predetermined operation amount (predetermined value) be2 (> ba1), the second contribution degree Ke2 can be set to “0 (zero)”. As described above, the resolution of the pressing force feedback control in the region where Bpa is small (the braking torque is small) is improved, and the reliability of the pressing force feedback control in the region where Bpa is large (the braking torque is large) is improved. Can be done.

  In the calculation characteristics CHka and CHke of the first and second contributions Ka1 and Ke2, instead of the braking operation amount Bpa (X-axis variable), the target pressing force Fbt, the pressing force actual value Fba, and the actual position Mka Is used (that is, a value corresponding to the braking operation amount). Fbt is calculated based on Bpa, and the control results are Fba (Fbc) and Mka (Mkc).

  In the arithmetic characteristics CHka and CHke, the predetermined values ba1 and be1 can be set equal, and the predetermined values ba2 and be2 can be set equal. In this case, any one of the first contribution calculation block KA1 and the second contribution calculation block KE2 may be omitted. When the first contribution calculation block KA1 is omitted, the combined pressing force Fbx is calculated based on Fbx = (1−Ke2) × Fbc + Ke2 × Fbe, using the second contribution Ke2. When the second contribution calculation block KE2 is omitted, the combined pressing force Fbx is calculated based on Fbx = Ka1 × Fbc + (1−Ka1) × Fbe using the first contribution Ka1. . The estimated pressing force value Fbe is calculated based on the rigidity value Gcp and the electric motor position Mkc (that is, Fbe = Gcp × Mkc).

  Further, in the calculation characteristics of the first and second contributions Ka1 and Ke2, the characteristics CHka and CHke when Bpa increases (indicated by the solid lines at KA1 and KE2) and the case where Bpa decreases (at KA1 and KE2). The characteristics CHkb and CHkbf (shown by broken lines) can be set separately. In the calculation characteristic of the first contribution Ka1, the calculation characteristic CHka when Bpa increases can be set larger than the calculation characteristic CHkb when Bpa decreases. In the calculation characteristic of the second contribution degree Ke2, the calculation characteristic CHke when Bpa increases can be set smaller than the calculation characteristic CHkf when Bpa decreases.

  In the first contribution calculation block KA1, a calculation characteristic CHka when Bpa increases and a calculation characteristic CHkb when Bpa decreases are set separately, and CHkb is a characteristic relatively smaller than CHka. . In CHka, when Bpa is “0” or more and less than a predetermined value ba1, Ka1 is “0”, and when Bpa is more than a predetermined value ba1 and less than a predetermined value ba2 (a value greater than ba1), Bpa is increased. When Bpa is equal to or greater than a predetermined value ba2, Ka1 is set to “1”, respectively, so that Ka1 simply increases according to the above. In CHkb, Bpa is “0” or more, so that Ka1 is simply “1” when Bpa is greater than or equal to predetermined value ba2, and Ka1 is simply decreased as Bpa decreases when Bpa is greater than or equal to predetermined value ba3 and less than predetermined value ba2. When the value is less than the predetermined value ba3, Ka1 is set to “0”. Here, the predetermined value ba3 is a value larger than the predetermined value ba1 and smaller than the predetermined value ba2. For example, in a region where Bpa is larger than ba1 and smaller than ba3, Ka1 is calculated to be larger than “0” when Bpa is increased, but Ka1 is “0” when Bpa is decreased. Is calculated.

  Similarly, in the second contribution calculation block KE2, a calculation characteristic CHke when Bpa increases and a calculation characteristic CHkf when Bpa decreases are set separately, and CHkf is a characteristic that is relatively larger than CHke. It is said. In CHke, when Bpa is “0” or more and less than a predetermined value be1, Ke2 is “1”, and when Bpa is greater than or equal to a predetermined value be1 and less than a predetermined value be2 (a value greater than be1), Bpa is increased. Thus, Ke2 is set to “0” when Bpa is equal to or greater than a predetermined value be2, so that Ke2 simply decreases according to the above. In CHkf, when Bpa is equal to or greater than the predetermined value be2, Ke2 is “0”, and when Bpa is equal to or greater than the predetermined value be3 and less than the predetermined value be2, Bpa is “0” or greater so that Ke2 simply increases as Bpa decreases. When the value is less than the predetermined value be3, Ke2 is set to “1”. Here, the predetermined value be3 is a value larger than the predetermined value be1 and smaller than the predetermined value be2. For example, in a region where Bpa is larger than be1 and smaller than be3, Ke2 is calculated to be smaller than “1” when Bpa is increased, but Ke2 is “1” when Bpa is decreased. Is calculated.

  In the first and second contribution calculation blocks KA1 and KE2, the predetermined values ba3 and be3 are set to values larger than a value fbm corresponding to friction loss of an electric motor or the like. Further, the predetermined values ba1 and be1 can be set to values smaller than the value fbm. Since the values ba3 and be3 are set larger than the friction loss equivalent value fbm, when Bpa is decreased, Fba is not used in the calculation of Fbx before Bpa reaches fbm. Therefore, Fbx is calculated based only on Fbe. As a result, fluctuations in the energization amount due to invalid displacement can be prevented. Further, when Bpa is increased, the effect of ineffective displacement does not occur, so the values ba1 and be1 can be set regardless of the friction loss equivalent value fbm, so that the pressing force resolution in a region where Bpa is small is ensured. obtain. The value fbm is calculated as the same physical quantity as the pressing force, but is converted into the same physical quantity as the equivalent value of Bpa based on the specifications (reduction ratio, lead, etc.) of the braking means, and ba3 and be3 are determined. The

  Further, the value fbm corresponding to the friction loss of the electric motor can be calculated and made variable based on characteristics (relationship between Mkc and Fbc) when the braking operation amount Bpa is reduced. Then, based on the calculated (learned) value fbm, the values ba3 and be3 can be determined. Specifically, when the braking operation amount Bpa is decreased, time series data of the electric motor position Mkc and the actual pressing force value Fbc are stored. Based on the stored time-series data, a region where Fbc does not change (decrease) even though Mkc changes (decreases) is extracted, and a value fbm is calculated based on Fbc of this region. Then, a predetermined value fbo (a positive sign value) is added to the value fbm, and the values ba3 and be3 can be calculated. Although the friction loss of the electric motor or the like varies with aging, the value fbm corresponding to the friction loss is learned at the time of the braking operation by the driver, so that appropriate pressing force feedback control can be executed.

  In the calculation characteristics CHka, CHkb, CHke, and CHkf of the first and second contributions Ka1 and Ke2, instead of the braking operation amount Bpa (X-axis variable), the target pressing force Fbt, the pressing force actual value Fbc, and the actual At least one of the positions Mkc (that is, a value corresponding to the braking operation amount) is used. Fbt is calculated based on Bpa, and the control results are Fbc and Mkc. The predetermined value be3 can be set equal to the predetermined value ba3.

  In the arithmetic characteristics CHka, CHkb, CHke, and CHkf, the predetermined values ba1 and be1 are equal, the predetermined values ba2 and be2 are equal, and the predetermined values ba3 and be3 are equal. In this case, any one of the first contribution calculation block KA1 and the second contribution calculation block KE2 may be omitted. When the first contribution calculation block KA1 is omitted, the combined pressing force Fbx is calculated based on Fbx = (1−Ke2) × Fbc + Ke2 × Fbe, using the second contribution Ke2. When the second contribution calculation block KE2 is omitted, the combined pressing force Fbx is calculated based on Fbx = Ka1 × Fbc + (1−Ka1) × Fbe using the first contribution Ka1. . The estimated pressing force value Fbe is calculated based on the rigidity value Gcp and the electric motor position Mkc (that is, Fbe = Gcp × Mkc).

  In the first contribution calculation block KA1, the second contribution calculation block KE2, and the second rigidity value calculation block GCP, instead of the braking operation amount Bpa, the target pressing force Fbt, the pressing force actual value Fbc, and the actual position At least one of Mkc may be used as a value corresponding to the braking operation amount.

<Second stiffness characteristic calculation block CHGC>
A stiffness characteristic storage processing block CHGC is provided in the second stiffness value calculation block GCP, and learning of the stiffness calculation characteristic CHgc can be performed. FIG. 5 is a functional block diagram of the stiffness characteristic storage processing block CHGC. The stiffness calculation characteristic CHgc is a calculation map for calculating (estimating) the second stiffness value Gcp based on the position Mkc of the electric motor (see FIG. 4).

  In the rigidity characteristic storage processing block CHGC, the characteristic of Gcq with respect to Bpa is continuously determined based on the braking operation amount Bpa and the first rigidity value (actual value) Gcq calculated in the first rigidity value calculation block GCQ. Remembered. That is, the first stiffness value Gcq is sequentially stored in association with the braking operation amount Bpa, and the stored characteristic is output as the stiffness calculation property CHgc. Then, based on CHgc, a second stiffness value (estimated value) Gcp is calculated. In other words, the actual stiffness value (actual stiffness value) Gcq is stored to form the characteristic CHgc, and the stiffness value Gcp is estimated based on CHgc.

  In the rigidity characteristic storage processing block CHGC, learning (memory) of the rigidity calculation characteristic CHgc can be executed every time the driver performs a braking operation. At this time, when the time change amount dBpa of the braking operation amount Bpa is equal to or greater than the predetermined value dbpx, the characteristic CHgc is not stored, and CHgc can be learned when the dBpa is less than the predetermined value dbpx. During sudden braking (when dBpa is large), the phase difference between Bpa, Mka (Mkc), and Fba (Fbc) (that is, the time delay of the calculation result Gcq with respect to Bpa) is excessive. Further, CHgc when the electric motor position (rotation angle) Mka increases (when MTR is rotated forward) is not employed, and CHgc when Mka decreases (when MTR is reversed) can be employed. . At this time, a limit is imposed on the amount of time change of Mka (that is, the speed of the electric motor), and the MTR can be gently reversed. Thereby, the influence of the phase difference can be compensated.

  In the combined pressing force calculation blocks KA1, KE2, and GCP, instead of the braking operation amount Bpa, at least one of the target pressing force Fbt, the pressing force actual value Fbc, and the position Mkc (that is, the braking operation amount). Is used). In this case, the relationship of the second stiffness value Gcq with respect to at least one of the adopted Fbt, Fbc, and Mkc is stored as the stiffness calculation characteristic CHgc. When at least one of Fbc and Mkc is employed, the influence of the above phase difference cannot occur.

  Further, in the stiffness value calculation block GCP, the value fbm corresponding to the torque loss of the above-described electric motor or the like can be calculated. When the braking operation amount Bpa is decreased, the second stiffness value Gcq is calculated based on the position change amount Mkh and the pressing force change amount Fbh. However, after Gcq decreases and becomes approximately “0”. The value fbm can be calculated based on the actual pressing force value Fbc at the time when it increases again. Specifically, after Gcq decreases and becomes less than the predetermined value gcqy, the value fbm is determined on the basis of the actual pressing force value when it becomes equal to or greater than the predetermined value gcqz (a value larger than gcqy). The At this time, the value fbm is calculated as the same physical quantity as the pressing force, but is converted into the same physical quantity as the equivalent value of Bpa based on the specifications (reduction ratio, lead, etc.) of the braking means.

<Stand-by position control block ICT>
Next, an embodiment of the standby position control block ICT (see FIG. 1) will be described with reference to FIG.

  In the standby position control block ICT, when the brake operation member BP is not operated by the driver or when it is operated slightly (the brake torque is not generated to the extent that the vehicle is decelerated), The standby position control of the member PSN is executed. In order to prevent unintentional or unexpected movement of the driver from being reflected in the actual behavior, a range (gap) that is not reflected in the movement (ie, vehicle deceleration) among the operable range is “play” of the BP. Is set as That is, in the standby position control, the position of the pressing member PSN when the driver is accelerating or operating the BP within the range of “play” of the braking operation member BP (that is, the MTR) Is controlled). By the standby position control, the gap (clearance) between the friction member MSB and the rotation member KTB is controlled, and the drag state of the friction member MSB is adjusted.

  The standby position control block ICT includes a stepping speed calculation block DBP, a return speed calculation block DAP, a target standby position calculation block PSB, and a position feedback control block PFB. In ICT, a target energization amount Ict for standby position control is calculated based on the braking operation amount Bpa, the acceleration operation amount Apa, and the electric motor position Mkc.

  In the stepping speed calculation block DBP, the stepping speed dBpa of BP is calculated based on the operation amount Bpa of the braking operation member (brake pedal) BP. Specifically, the stepping speed dBpa can be calculated by differentiating the braking operation amount Bpa with time. Here, when Bpa increases, dBpa is set to a plus sign (+), and the more BP is stepped on, the larger dBpa becomes.

  In the return speed calculation block DAP, the return speed dApa of the AP is calculated based on the operation amount Apa of the acceleration operation member (accelerator pedal) AP. Specifically, the return speed dApa can be calculated by differentiating the acceleration operation amount Apa with time. Here, when Apa decreases, dApa is set to a plus sign (+), and dApa becomes larger as AP is suddenly returned (released).

  In the target standby position calculation block PSB, the braking operation amount Bpa, the stepping speed (time change amount when Bpa increases) dBpa, the acceleration operation amount Apa, and the return speed (time change amount when Apa decreases) dApa. Based on at least one of these, the target standby position Psb is calculated. The target standby position Psb corresponds to the position of the pressing member PSN when the braking operation by the driver is not performed or when the braking operation is slightly performed. Here, the “slight braking operation” means that the driver is stepping on the BP, but is operating within the range of play, and the generation of braking torque (that is, deceleration of the vehicle) is Corresponds to the state you do not expect

  The target standby position Psb is calculated based on the calculation characteristics (calculation map) CHps and the braking operation amount Bpa. When Bpa is “0” (that is, when Bpa is not operated), Psb is calculated to be “0 (that is, reference position pzr)”. Then, the calculation is performed so that the target standby position Psb is increased as Bpa increases (that is, PSN approaches KTB). When Bpa is equal to or greater than the predetermined value bp1, the target standby position Psb can be limited to the predetermined value ps1. Here, the predetermined operation amount bp1 is a value equal to or less than the predetermined operation amount bp0 (a value corresponding to the play of BP) in the target pressing force calculation block FBT (see FIG. 1). Therefore, the predetermined value ps1 corresponds to a state in which MSB and KTB are in slight contact (that is, a state in which MSB and KTB are dragged). The value bp1 can be set equal to the play equivalent value bp0 of BP.

  The target standby position Psb can be calculated larger as the stepping speed dBpa of the braking operation member BP is higher. When the dBpa at the initial stage of braking is large, the driver requests a rapid deceleration of the vehicle. In order to improve the responsiveness of the braking torque, Psb is greatly calculated as dBpa increases, and even when Bpa is approximately “0”, the MSB and KTB can be brought into contact with each other in advance.

  The target standby position Psb can be calculated in consideration of the acceleration operation amount Apa. When Apa is large (represented by an increase in absolute value to the minus side of the X-axis in the computation map CHps), the side where Psb is smaller than the reference position pzr (the side in which the PSN is retracted and away from KTB) ). When the driver is operating the acceleration operation member AP, the target standby position Psb is calculated to be small, contact between the MSB and KTB (that is, dragging) can be avoided, and the fuel efficiency of the vehicle can be improved. In addition, the higher the return speed dApa of the acceleration operation member AP, the higher the probability that sudden braking will be performed thereafter. For this reason, the target standby position Psb can be calculated to a large value (a value in the forward direction of the PSN and close to KTB) for the purpose of ensuring the response of the braking torque.

  In the standby position feedback control block PFB, the standby position of the pressing member PSN is feedback-controlled based on the target standby position Psb and the actual position Mkc. That is, the position feedback energization amount Ict is calculated based on the deviation ΔPs between the target standby position Psb and the actual position Mkc. Here, Ict is a target energization amount to the electric motor MTR for moving the pressing member PSN to the target standby position Psb.

  In the standby position feedback control block PFB, first, a deviation ΔPs (= Psb−Mkc) between the target standby position Psb and the actual position Mkc is calculated. Then, the standby position feedback energization amount Ict is calculated based on the position deviation ΔPs and the calculation characteristic (calculation map) CHic. Here, the calculation map CHic is set so that Ict increases as ΔPs increases.

  The position feedback energization amount Ict is transmitted to the adjustment calculation block IMT and adjusted with another energization target value (Ist or the like). The adjustment calculation block IMT includes a selection calculation block SNT, which switches between an energization target value based on the pressing force (sum of Ist and Ipt) and an energization target value (Ict) based on the position of the PSN. . In other words, the position control of the pressing member (piston) PSN is executed between the standby position Psb where no pressing force can be generated and the reference position pzr, and the PSN is moved forward from the reference position pzr and actually When the pressing force is generated, the control is switched to the pressing force control.

  In order to avoid dragging the MSB, it is assumed that the driver performs a braking operation from the state where the PSN is maintained at a position where the MSB cannot contact the KTR during non-braking. If the pressing force control is executed without performing the standby position feedback control, no pressing force can be generated from the standby position Psb to the reference position pzr. Therefore, the pressing force deviation ΔFb ( = Fbt−Fbx) increases, and the electric motor MTR is accelerated rapidly. Since the MSB starts contact with the KTB in the accelerated state, the pressing force is rapidly increased, and the pressing force may overshoot. Furthermore, originally unnecessary electricity can be applied by the deviation ΔFb. On the other hand, when the standby position feedback control is executed as a previous stage of the pressing force feedback control, the position of the PSN is appropriately controlled from the standby position Psb to the reference position pzr based on the position information (for example, Mkc). For this reason, the pressing force can be raised smoothly without overshooting, and the unnecessary energization of the electric motor can be suppressed.

<Action and effect>
Next, the time series operation and actions / effects of the electric braking apparatus according to the embodiment of the present invention will be described. FIG. 7 is a time-series diagram in the case where the braking operation amount Bpa is decreased toward “0 (a state where the braking operation is not performed)” and the braking torque applied to the wheel WHL is decreased. In addition, each circle mark and square mark have shown the calculation result in each calculation period. Here, the position mkz is referred to as a limit position, and is the position where the pressing member PSN is farthest from the rotating member KTB in the movable range of the screw member NJB (for example, the range in which movement is limited by a stopper or the like).

  At time t1, switching of the power transmission surface (contact surface where power transmission is performed in the power transmission member) starts, and a state in which the electric motor is displaced but the pressing force is not changed (inactive displacement state) is started. . The change amount Fbh of the pressing force with respect to the position change amount (displacement) Mkh of the electric motor is calculated as the first stiffness value Gcq. However, since the pressing force Fba does not change, Gcq is calculated gradually to a small value.

  At time t2, the first stiffness value Gcq is still equal to or greater than the predetermined value (threshold value) gcqx (Gcq ≧ gcqx). At time t3, the state changes from “Gcq ≧ gcqx state” to “Gcq less than gcqx (Gcq <gcqx) state”. The position Mka (= mkat3, square mark) at this time (t3) is stored as the candidate position Mkk, and the pressing force Fba at t3 is also stored as the candidate force Fkk (= fbat3, square mark). Further, at time t3, the count of continuation of “a state where Gcq is less than gcqx (Gcq <gcqx)” is started.

  At time t4, the power transmission surface is completely switched, and the invalid displacement state ends. At time t5, “the state where Gcq is less than gcqx” is resolved. Since the state of “Gcq <gcqx” does not continue beyond the displacement (corresponding to the clearance equivalent value) skh of the electric motor corresponding to the gap of the power transmission member GSK or the like (that is, the displacement hmkt5 from t3 to t5 is skh Therefore, the candidate position Mkk (mkat3) and the candidate force Fkk (fbat3) are forgotten (reset) at the time t5 when Gcq transitions to gcqx or more. Here, the clearance equivalent value skh is a value corresponding to the clearance of the power transmission member (for example, gear backlash, joint clearance, bearing clearance). Since these gaps are enlarged by aging wear, the gap equivalent value skh can be a value (predetermined preset value) that allows for the gap of the power transmission member including aging wear.

  At time t7, the state again transitions from “Gcq ≧ gcqx state” to “Gcq <gcqx state”. The position Mka (= mkat7, square mark) and the pressing force Fba (= fbat7, square mark) at the time point t7 are stored as the candidate position Mkk and the candidate force Fkk, respectively. Then, the continuation of “the state of Gcq <gcqx” starts to integrate the displacement of the electric motor (that is, the displacement of the electric motor starts to be measured). Candidate position at time t8 when displacement (change in motor position from t7 to t8) hmkt8 exceeds a gap equivalent value (displacement equivalent to a gap) skh from a position (candidate position) mkat7 to mkat8 where Mkk is stored Mkk (mkat7) is adopted as the reference position pzr, and the candidate force Fkk (fbat7) is set as the correction pressing force fzr, respectively.

  Then, the actual position Mka of the electric motor acquired by the MKA is corrected by the reference position (corresponding to the contact start position between the MSB and KTB) pzr, and the corrected position Mkc is calculated. Similarly, the pressing force Fba acquired by the FBA is corrected by the corrected pressing force (corresponding to the FBA zero point drift) fzr, and the corrected pressing force Fbc is calculated. Thus, the reference position pzr and the corrected pressing force fzr are not immediately determined when the first stiffness value Gcq becomes less than the predetermined threshold value gcqx (for example, t3). When Gcq <gcqx is satisfied, the candidate position Mkk and the candidate force Fkk are stored, and when the state where Gcq <gcqx is satisfied exceeds the gap equivalent value skh, the candidate position is traced back. Mkk and the candidate force Fkk are formally adopted as the reference position pzr and the correction pressing force fzr. For this reason, the influence of the above-mentioned invalid displacement and detection resolution is compensated, and the correction of the acquired value can be performed accurately.

  When the electric motor MTR is rotated in the reverse direction and Fba is decreased, a speed limit can be provided for the MTR within a predetermined region approaching the reference position pzr. Alternatively, the MTR can be returned toward the zero point at a preset constant speed. That is, even when Bpa is suddenly returned, the speed can be limited as the PSN approaches the reference position pzr. For this reason, the influence of the phase difference between Mka and Fba can be compensated.

  There is a correlation between the displacement of the electric motor and time. For example, if the speed of the electric motor is made constant, the displacement is proportional to time. For this reason, instead of the displacement threshold value skh, the time threshold value skt can be adopted as the gap equivalent value. That is, it is determined whether or not the state of “Gcq <gcqx” has continued beyond the time skt under the condition related to the gap equivalent value.

<Summary of embodiments according to the present invention>
Hereinafter, embodiments of the present invention will be summarized.
The electric braking device for a vehicle according to the present invention includes a braking operation amount acquisition means (BPA) for acquiring a braking operation amount (Bpa) of a braking operation member (BP) of the vehicle by a driver, and a transmission member (GSK or the like). By transmitting the power of the electric motor (MTR) through the friction member (MSB) against the rotating member (KTB) fixed to the wheel (WHL) of the vehicle, the braking torque is applied to the wheel (WHL). And a control unit that calculates a target energization amount (Imt) based on the braking operation amount (Bpa) and controls the electric motor (MTR) based on the target energization amount (Imt). Means (CTL).

  Further, a pressing force acquisition means (FBA) that acquires an actual pressing force (Fba) that is a force with which the friction member (MSB) actually presses the rotating member (KTB), and an actual position of the electric motor (MTR) ( Position acquisition means (MKA) for acquiring Mka). When the braking operation amount (Bpa) is decreased by the control means (CTL), the change amount (Fbh) of the actual pressing force (Fba) with respect to the change amount (Mkh) of the actual position (Mka). The stiffness value (Gcq), which is the ratio (Fbh / Mkh), is sequentially calculated, and when the stiffness value (Gcq) changes from a predetermined value (gcqx) to less than the predetermined value (gcqx) (t3, t7). In the state where the actual position (Mka) at that time is stored as a candidate position (Mkk) and the candidate position (Mkk) is stored, the rigidity value (Gcq) is less than a predetermined value (gcqx) Is less than the gap equivalent values (skh, skt) corresponding to the gap of the transmission member (GSK, etc.), the candidate position (Mkk) is forgotten (reset), and the candidate position Mkk) is stored, and when the continuation of the state where the rigidity value (Gcq) is less than the predetermined value (gcqx) exceeds the gap equivalent values (skh, skt), the candidate (t8) The position (Mkk) is determined as a reference position (pzr) at which the friction member (MSB) and the rotating member (KTB) start to contact each other, and the target energization amount (Imt) is determined based on the reference position (pzr). Calculated. For example, the reference position pzr is set as a zero point in the position information of the electric motor MTR, and feedback control based on the position Mkc is executed.

  When the rigidity value Gcq (corresponding to the spring constant of BRK) becomes less than the predetermined value gcqx, the reference position pzr is not immediately determined, but this state (Gcq <gcqx) continues beyond the clearance equivalent value. Only then is the reference position pzr determined. For this reason, even if there is an ineffective displacement due to a gap between transmission members such as a reduction gear, the reference position (a position where the MSB presses KTR or not) pzr can be accurately determined. Further, since the stiffness value Gcq is calculated as the ratio of the pressing force change amount Fbh to the position change amount Mkh, the influence of the error of the obtaining means (sensor) (particularly, the FBA zero point drift) can be compensated. The gap (clearance) of the power transmission member is caused by, for example, a gear backlash, a joint gap, or a bearing gap. Furthermore, these gaps can be enlarged by aging. For this reason, the clearance equivalent values skh and skt can be values (predetermined predetermined values) that allow for the clearance of the power transmission member including aged wear.

  Similarly, in the electric braking device for a vehicle according to the present invention, when the braking operation amount (Bpa) is reduced by the control means (CTL), the change amount (Mkh) with respect to the change amount (Mkh) of the actual position (Mka). The stiffness value (Gcq) that is the ratio (Fbh / Mkh) of the change amount (Fbh) of the actual pressing force (Fba) is sequentially calculated, and the stiffness value (Gcq) is greater than or equal to a predetermined value (gcqx) to the predetermined value (gcqx). ) At the time (t3, t7) when the value is changed to less than (), the pressing force (Fba) at that time is stored as a candidate force (Fkk), and the stiffness value (Fkk) is stored in the state where the candidate force (Fkk) is stored. When the continuation of the state where Gcq) is less than the predetermined value (gcqx) is less than the gap equivalent value (skh, skt) corresponding to the gap of the power transmission member (GSK, etc.), the candidate force (Fkk) is In the state where the candidate force (Fkk) is stored in the rejected (reset) state, the continuation of the state in which the rigidity value (Gcq) is less than a predetermined value (gcqx) is the gap equivalent value (skh, skt). At the time (t8) when it exceeds, the candidate force (Fkk) is determined as a corrected pressing force (fzr) corresponding to a zero point drift of the pressing force acquisition means (FBA), and based on the corrected pressing force (fzr). Thus, the target energization amount (Imt) is calculated. Specifically, the correction value fzr of the pressing force is subtracted from the acquired value Fba by the pressing force acquisition means FBA, and feedback control based on the pressing force is executed based on the corrected pressing force Fbc.

  The detection of “force” is performed by measuring the strain of the strain generating body, but in this strain detection, the drift of the detected value becomes a problem. As in the case of the electric motor position, the pressing force Fba (candidate force Fkk which is a candidate for the correction amount) is stored, the clearance equivalent value condition is satisfied, and the correction amount (correction) corresponding to the zero point drift of the pressing force is satisfied. The pressing force fzr) is determined. For this reason, compensation for the zero point drift of the FBA can be reliably performed. The reference position pzr and the corrected pressing force fzr are calculated values at the same time point (calculation cycle).

  In the electric braking device for a vehicle according to the embodiment of the present invention, the control means (CTL) is configured such that the braking operation amount (Bpa) corresponds to a free movement of the braking operation member (BP) (bp0). Is greater than)), the pressing force feedback control (IPT) is executed based on the pressing force (Fbc) obtained by correcting the actual pressing force (Fba) by the corrected pressing force (fzr), and the braking operation amount ( When Bpa) is smaller than the predetermined value (bp0), position feedback control (ICT) is executed based on the position (Mkc) obtained by correcting the actual position (Mka) with the reference position (pzr). Can be configured.

  Furthermore, in the electric braking device for a vehicle according to the embodiment of the present invention, an acceleration operation amount acquisition means APA for acquiring the acceleration operation amount Apa of the acceleration operation member AP of the vehicle by the driver is provided, and the control means (CTL) is The position feedback control (ICT) may be executed based on the acceleration operation amount Apa.

  In addition, in the electric braking device for a vehicle according to an embodiment of the present invention, the pressing force acquisition means (FBA) is configured so that the friction member (MSB) presses the rotating member (KTB) as an actual pressing force (Fba). A value based on a digital signal obtained by analog-to-digital conversion of an analog signal output from an element (such as a strain gauge) that detects force can be used. Further, the position acquisition means (MKA) is directly output from an element (Hall IC, reso lever, encoder, etc.) for detecting the position of the electric motor (MTR) as the position (Mka) of the electric motor (MTR). Values based on digital signals may be used.

  As described above, according to the present invention, the MKA and FBA acquisition results Mka and Fba can be accurately corrected (corrected) by the reference position pzr and the correction pressing force fzr. The pressing force feedback control can be executed.

  BPA ... braking operation amount acquisition means, MSB ... friction member, KTB ... rotation member, MTR ... electric motor, BRK ... braking means, CTL ... control means, FBA ... pressing force acquisition means, MKA ... position acquisition means, Fba ... actual press Pressure, Mka: Actual position of electric motor, mkm: Invalid displacement section, Gcq: Rigidity value, Mkk: Candidate position, pzr: Reference position, Fkk: Candidate force, fzr: Corrected pressing force, Bpa: Braking operation amount, Imt ... Target energization amount

Claims (2)

Braking operation amount acquisition means for acquiring a braking operation amount of the braking operation member of the vehicle by the driver;
Braking means for generating a braking torque on the wheel by pressing the friction member against the rotating member fixed to the wheel of the vehicle by transmitting the power of the electric motor via the transmission member;
Control means for calculating a target energization amount based on the braking operation amount and controlling the electric motor based on the target energization amount;
An electric braking device for a vehicle comprising:
A pressing force acquisition means for acquiring an actual pressing force that is a force with which the friction member actually presses the rotating member;
Position acquisition means for acquiring the actual position of the electric motor;
With
The control means includes
When the braking operation amount is reduced,
The rigidity value that is the ratio of the change amount of the actual pressing force to the change amount of the actual position is sequentially calculated,
When the rigidity value changes from a predetermined value or more to less than the predetermined value, the actual position at that time is stored as a candidate position,
In the state where the candidate position is stored, if the continuation of the state where the rigidity value is less than the predetermined value is less than a gap equivalent value corresponding to the gap of the transmission member, the candidate position is forgotten,
In the state where the candidate position is stored, when the continuation of the state where the rigidity value is less than the predetermined value exceeds the gap equivalent value, the stored candidate position is set as the friction member and the friction member. Determine the reference position where the rotating member begins to contact,
An electric braking device for a vehicle configured to calculate the target energization amount based on the reference position. Braking operation amount acquisition means for acquiring a braking operation amount of the braking operation member of the vehicle by the driver;
Braking means for generating a braking torque on the wheel by pressing the friction member against the rotating member fixed to the wheel of the vehicle by transmitting the power of the electric motor via the transmission member;
Control means for calculating a target energization amount based on the braking operation amount and controlling the electric motor based on the target energization amount;
An electric braking device for a vehicle comprising:
A pressing force acquisition means for acquiring an actual pressing force that is a force with which the friction member actually presses the rotating member;
Position acquisition means for acquiring the actual position of the electric motor;
With
The control means includes
When the braking operation amount is reduced,
The rigidity value that is the ratio of the change amount of the actual pressing force to the change amount of the actual position is sequentially calculated,
When the rigidity value changes from a predetermined value or more to less than the predetermined value, the actual pressing force at that time is stored as a candidate force,
In the state where the candidate force is stored, if the continuation of the state where the rigidity value is less than the predetermined value is less than a gap equivalent value corresponding to the gap of the transmission member, the candidate force is forgotten,
In the state where the candidate force is stored, when the continuation of the state where the rigidity value is less than the predetermined value exceeds the gap equivalent value, the stored candidate force is used as the pressing force acquisition means. The correction pressing force corresponding to the zero point drift of
An electric braking device for a vehicle configured to calculate the target energization amount based on the corrected pressing force.

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