JP2018114901A - Brake control device of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device capable of controlling in cooperation with regeneration brake and ensuring fail-safe in a case of a failure of the device.SOLUTION: A brake control device is provided with an input rod RDI, an output rod RDO, first and second electric motors MTF, MTS, and first and second racks RKF, RKS. Outputs of the first and second electric motors are controlled to independently control operation force of the input rod and a displacement of the output rod. The first rack is constituted by an input part connected to the input rod and an assisting energization part connected to the first electric motor. Assisting energization force in a forward movement direction corresponding to an increase of an operation amount of a brake operation member is given from the assisting energization part to the input part, but force in a rearward movement direction opposite to the forward movement direction is not given. For example, An assisting energization part Pjs has an assisting energization surface facing the forward movement direction, the input part has a pressure receiving surface facing the rearward movement direction, and a surface contact between the assisting energization surface and the pressure receiving surface gives the assisting energization force.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a braking control device for a vehicle.

  Patent Document 1 discloses that “a brake operation member (10); a first piston-cylinder unit (12), which is operated by a brake operation member (10) operated at least by a specified minimum operation amount. The first piston (14) of the cylinder unit (12) is displaceable, and the brake operation member (10) is disposed so that the first internal pressure of the piston-cylinder unit (12) can be increased. One piston-cylinder unit (12); at least one wheel brake cylinder, the increased first internal pressure in the first piston-cylinder unit (12) being able to increase the brake pressure of at least one wheel brake cylinder At least one hydraulically connected to the first piston-cylinder unit (12) A brake system for a vehicle comprising: an air brake cylinder; and a first brake booster (24), wherein the second piston-cylinder unit (26) is provided by the first brake booster (24). The second piston (28) of the unit (26) is displaceable, whereby the first brake booster (24) is moved so that the second internal pressure in the second piston-cylinder unit (26) can be increased. 2 piston-cylinder unit (26) and at least one so that the brake pressure of at least one wheel brake cylinder can be increased by the increased second internal pressure in the second piston-cylinder unit (26). A second piston-cylinder unit (26) with two wheel brake cylinders connected hydraulically Obtain "It has been described.

  Patent Document 1 describes a braking control device configured by two piston-cylinder units that are driven by two electric motors in order to perform braking in cooperation with a regenerative brake. Since this apparatus is provided with two piston-cylinder units, it is difficult to reduce the size of the entire apparatus. Therefore, a brake control device that can be miniaturized is desired.

  In order to solve this problem, the applicant has developed a braking control device as described in Patent Document 2. In the brake control device of Patent Document 2, a case member (also referred to as a “housing”) fixed to the master cylinder, a first electric motor fixed to the case member, and a case member are fixed separately from the first electric motor. The second electric motor, the input rod that is mechanically connected to the braking operation member and moves linearly, and presses the piston in the master cylinder to be parallel to the central axis of the input rod and can move linearly The differential mechanism built in the case member allows the relative movement between the input rod and the output rod by inputting the output rod, the output of the first electric motor, and the output of the second electric motor. And a controller that independently controls the force acting on the input rod and the displacement of the output rod by controlling the output of the first electric motor and the output of the second electric motor. That. In this braking control device, the function is achieved by the cooperation of the two electric motors. For example, when one of the electric motors malfunctions, it is necessary to ensure fail-safety. is there.

Special table 2013-53604 gazette US Patent Application No. 15 / 281,820

  An object of the present invention is to provide a braking control device that can be controlled in cooperation with a regenerative brake and that can ensure fail-safe when the device is malfunctioning.

  The vehicle braking control apparatus according to the present invention pumps braking fluid from the master cylinder (MC) to the wheel cylinder (WC) in response to an operation of the braking operation member (BP) of the vehicle, and the vehicle wheel (WH). ) Generates braking torque. The vehicle braking control device is movable in parallel with an input rod (RDI) connected to the braking operation member (BP) and a central axis (Jin) of the input rod (RDI), and the master cylinder (MC ) Of the output rod (RDO) that presses the piston (PNA) in the inside), the first electric motor (MTF) that generates the assisting force (Fjs) for the input rod (RDI), and the output rod (RDO) A second electric motor (MTS) for adjusting the displacement (Sro), “a first transmission mechanism (PNF & Gfa) for transmitting the output of the first electric motor (MTF) to the input rod (RDI), the second electric motor A second transmission mechanism (PNS & Gsa, PNO & Gsb) that transmits the output of (MTS) to the output rod (RDO), and the output of the input rod (RDI) A differential mechanism (DFR) that is configured by a third transmission mechanism (PNO & Gfb) that transmits to the output rod (RDO) and adjusts the relative movement between the input rod (RDI) and the output rod (RDO). And the first electric motor (MTF) and the second electric motor (MTS) are controlled so that the operating force (Fbp) acting on the input rod (RDI) and the displacement (Sro) are independent. And a controller (ECU) for controlling. In the vehicle braking control device, the assisting force (Fjs) is generated in the forward direction (Hff) corresponding to the increase in the operation amount (Bpa) of the braking operation member (BP), but the forward direction It is configured not to be generated in the reverse direction (Hrf) opposite to (Hff).

  The vehicle braking control apparatus according to the present invention is movable in parallel with an input rod (RDI) connected to the braking operation member (BP) and a central axis (Jin) of the input rod (RDI). , An output rod (RDO) that presses the piston (PNA) in the master cylinder (MC), a first electric motor (MTF) that generates an assisting force (Fjs) for the input rod (RDI), and the output rod A second electric motor (MTS) for adjusting a displacement (Sro) of (RDO), a first pinion gear (PNF) connected to the first electric motor (MTF), and a connection to the second electric motor (MTS) The second pinion gear (PNS), the first input rack gear portion (Gfa) meshing with the first pinion gear (PNF), and the first input rack gear portion (Gfa) A first rack (RKF) having a different first output rack gear portion (Gfb), a second input rack gear portion (Gsa) meshing with the second pinion gear (PNS), and the second input rack gear portion (Gsa) Is a second rack (RKS) having a different second output rack gear portion (Gsb), is rotatably supported by the output rod (RDO), the first output rack gear portion (Gfb), and the second output rack gear. An operation force (acting on the input rod (RDI) by controlling the output pinion gear (PNO) meshing with the portion (Gsb), the first electric motor (MTF), and the second electric motor (MTS). Fbp) and a controller (ECU) that independently controls the displacement (Sro). In the vehicle braking control device, the assisting force (Fjs) is generated in the forward direction (Hff) corresponding to the increase in the operation amount (Bpa) of the braking operation member (BP), but the forward direction It is configured not to be generated in the reverse direction (Hrf) opposite to (Hff).

  In the vehicle braking control apparatus according to the present invention, the first rack (RKF) is connected to the input rod (RDI), and has an input part (Pin) having the second input rack gear part (Gsa), and the input. An assisting portion (Pjs) having a first input rack gear portion (Gfa) that is movable in parallel to the central axis (Jin) with respect to the portion (Pin). The assisting force (Fjs) is applied from the assisting unit (Pjs) to the input unit (Pin). For example, the assisting portion (Pjs) has an assisting surface (Mjs) facing the forward direction (Hff), and the input portion (Pin) is a pressure receiving surface (Min) facing the retracting direction (Hrf). The assisting force (Fjs) is applied by surface contact between the assisting surface (Mjs) and the pressure receiving surface (Min).

  Furthermore, the vehicle braking control device according to the present invention includes an elastic body (SPF) that applies a force in the backward direction (Hrf) to the assisting portion (Pjs). In the vehicle braking control apparatus according to the present invention, the controller (ECU) determines whether or not the first electric motor (MTF) is malfunctioning, and the first electric motor (MTF) is malfunctioning. When it is determined that the power supply to the first electric motor (MTF) is stopped.

  According to the above configuration, when the first electric motor MTF is malfunctioning or when the braking operation member BP is suddenly operated, the first electric motor MTF is prevented from becoming a resistance of the braking operation. For this reason, an unnecessary increase in the operating force Fbp by the driver is suppressed, and good operating characteristics can be ensured. In addition, even when the first electric motor MTF is malfunctioning (for example, when energization is stopped), the assisting portion Pjs reliably responds to the initial position (when braking is not performed) by the applying force in the backward direction Hrf by the elastic body SPF. Position).

1 is an overall configuration diagram showing an embodiment of a vehicle braking control apparatus according to the present invention. It is a control flow figure for explaining the drive processing of electric motors MTF and MTS. It is the schematic for demonstrating the differential mechanism DFR of the brake actuator BAC. It is the schematic for demonstrating the 1st rack RKF of the differential mechanism DFR.

<Symbols of components, subscripts at the end of symbols, and moving directions>
An embodiment of a vehicle braking control apparatus according to the present invention will be described with reference to the drawings. In the following description, components, arithmetic processing, signals, characteristics, and values having the same symbol, such as “ECU”, have the same function. A subscript (such as “fr”) added to the end of each symbol is a comprehensive symbol indicating which wheel it relates to. Specifically, “fr” indicates the right front wheel, “fl” indicates the left front wheel, “rr” indicates the right rear wheel, and “rl” indicates the left rear wheel. For example, in each wheel cylinder, they are expressed as a right front wheel wheel cylinder WCfr, a left front wheel wheel cylinder WCfl, a right rear wheel wheel cylinder WCrr, and a left rear wheel wheel cylinder WCrl.

  In the moving direction of each component (particularly linear motion), the “forward direction” corresponds to the direction in which the hydraulic pressure Pwa of the wheel cylinder WC increases and the braking torque of the wheel WH increases. Conversely, the “reverse direction” corresponds to a direction in which the hydraulic pressure Pwa of the wheel cylinder WC decreases and the braking torque of the wheel WH decreases. In the rotationally moving component, the “forward rotation direction” corresponds to the direction in which the hydraulic pressure Pwa of the wheel cylinder WC increases and the braking torque of the wheel WH increases. On the other hand, the “reverse direction” corresponds to a direction in which the hydraulic pressure Pwa of the wheel cylinder WC decreases and the braking torque of the wheel WH decreases. Therefore, in a state where each component is assembled, the “forward direction” corresponds to the “forward rotation direction”, and the “reverse direction” corresponds to the “reverse direction”.

<Embodiment of Braking Control Device According to the Present Invention>
A vehicle including an embodiment of a braking control device according to the present invention will be described with reference to the overall configuration diagram of FIG. The vehicle includes an electric drive device EDS, a braking operation member BP, an operation amount sensor BPA, a braking actuator (simply referred to as “actuator”) BAC, an electronic control unit (also referred to as “controller”) ECU, a tandem master cylinder (simply, MC (also referred to as “master cylinder”), and fluid passages (braking piping) HKA and HKB (also simply referred to as “HK”) are provided.

  Each wheel WHfr, WHfl, WHrr, WHrl (simply referred to as “WH”) of the vehicle has brake calipers CPfr, CPfl, CPrr, CPrl (simply referred to as “caliper”, also referred to as “CP”), A wheel cylinder WCfr, WCfl, WCrr, WCrl (also simply referred to as “WC”) and a rotating member KTfr, KTfl, KTrr, KTrl (also simply referred to as “KT”) are provided. The master cylinder MC, the fluid passage HK (generic name for HKA and HKB), and the wheel cylinder WC are in a liquid-tight state.

≪Electric drive EDS≫
The vehicle is equipped with an electric drive device EDS. That is, the vehicle is an electric vehicle or a hybrid vehicle. The electric drive device EDS includes a drive electric motor MTD and a drive electronic control unit ECD. For example, a driving electric motor MTD is provided on the front wheels WHfr, WHfl of the vehicle via a drive shaft DS. The vehicle is a so-called front wheel drive.

  When the vehicle is accelerated, an electric motor for driving (also simply referred to as “driving motor”) MTD functions as an electric motor and generates driving force for the front wheels WHfr and WHfl. On the other hand, when the vehicle is decelerated, the drive motor MTD functions as a generator and generates regenerative braking force on the front wheels WHfr and WHfl. At this time, the kinetic energy of the vehicle is converted into electric power by the generator MTD and stored in the on-board secondary battery BAT. The drive motor MTD functions not only as a so-called driving force generator, but also as a regenerative braking device.

  The drive electric motor MTD is controlled by the drive electronic control unit ECD. The drive electronic control unit ECD adjusts the output torque of the drive motor MTD according to the operation amount of an acceleration operation member (for example, an accelerator pedal) (not shown). Further, at the time of braking, the regenerative braking force Rga is controlled by the drive electronic control unit ECD based on the operation amount Bpa of the braking operation member BP via the drive motor MTD which is also a generator. In the electronic control unit ECD, the state of charge of the storage battery BAT is monitored, and based on this, the maximum regenerative braking force Rgm that can be generated is calculated. The maximum regenerative braking force Rgm is transmitted from the electronic control unit ECD to the electronic control unit ECU via the communication bus CMB. The braking electronic control unit ECU determines a friction braking force, a regenerative braking force, and respective target values. The target value Rgt of the regenerative braking force is transmitted from the braking electronic control unit ECU to the driving electronic control unit ECD via the communication bus CMB, and the electronic control unit ECD uses the actual value Rga based on the target value Rgt. Is controlled. The electric drive device EDS has been described above.

  The braking operation member (for example, brake pedal) BP is a member that the driver operates to decelerate the vehicle. The braking operation member BP is fixed to the vehicle body BD in a state where it can rotate. An operation displacement sensor SBP is provided at a fixed portion between the braking operation member BP and the vehicle body BD. The operation displacement Sbp is detected by the operation displacement sensor SBP. By operating the braking operation member BP, the braking torque of the wheel WH (that is, each wheel WHfr, WHfl, WHrr, WHrl) is adjusted, and a braking force is generated on the wheel WH.

  Specifically, a rotating member (for example, a brake disc) KT is fixed to the vehicle wheel WH. The caliper CP is arranged so as to sandwich the rotating member KT (KTfr, KTfl, KTrr, KTrl). The caliper CP (that is, CPfr, CPfl, CPrr, CPrl) is provided with a wheel cylinder WC (that is, each wheel cylinder WCfr, WCfl, WCrr, WCrl). By increasing the pressure (hydraulic pressure) of the brake fluid in the wheel cylinder WC, the friction member (for example, a brake pad) is pressed against the rotating member KT. Since the rotating member KT and the wheel WH are fixed so as to rotate integrally, a braking torque (resulting braking force) is generated on the wheel WH by the frictional force generated at this time.

  The operation amount sensor BPA is provided on the braking operation member BP. The operation amount sensor BPA acquires (detects) an operation amount (braking operation amount) Bpa of the braking operation member BP by the driver. Specifically, among the operation amount sensor BPA, among “operation displacement sensor SBP for detecting operation displacement Sbp of braking operation member BP” and “operation force sensor FBP for detecting operation force Fbp of braking operation member BP” At least one of the above is adopted. That is, the operation amount sensor BPA is a general term for the operation displacement sensor SBP and the operation force sensor FBP. Accordingly, the brake operation amount Bpa is determined based on at least one of the operation displacement Sbp of the brake operation member BP and the operation force Fbp of the brake operation member BP. The braking operation amount Bpa is input to an electronic control unit (controller) ECU.

≪Brake actuator BAC≫
The brake actuator BAC independently establishes the relationship between the operation force Fbp acting on the brake operation member BP (ie, the force acting on the input rod RDI) and the piston displacement of the master cylinder MC (ie, the displacement Sro of the output rod RDO). Control. The actuator BAC includes a housing HSG, a first electric motor MTF, a second electric motor MTS, an input rod RDI, an output rod RDO, and a differential mechanism DFR.

  The housing HSG is a box-shaped member having a space inside, and is also referred to as a “case (container)”. Inside the housing HSG, members constituting the actuator BAC such as a differential mechanism DFR are accommodated. The housing HSG is fixed to the vehicle body BD of the vehicle by mounting bolts BLT and nuts NUT. Then, the master cylinder MC is fixed to the housing HSG on the side opposite to the fixing portion for the vehicle body BD.

  A first electric motor MTF and a second electric motor MTS are fixed inside the housing HSG. The first electric motor MTF and the second electric motor MTS are separate electric motors. Therefore, two electric motors MTF and MTS are built in the housing HSG. The output of the first electric motor MTF (first rotation shaft Shf) and the output of the second electric motor MTS (second rotation shaft Shs) are input to the differential mechanism DFR.

  The input rod RDI is mechanically connected to the braking operation member BP via the connection rod RDC. Specifically, the connecting rod RDC is mechanically connected to the braking operation member BP, and the connecting rod RDC and the input rod RDI are mechanically connected. The braking operation member BP (brake pedal) rotates about the attachment portion with respect to the vehicle body BD, but this rotational motion is absorbed by the connecting rod RDC and converted into a linear motion (forward or backward) of the input rod RDI. Is done.

  An operation force sensor FBP is provided at an attachment portion (connection portion) between the connection rod RDC and the brake operation member BP. The operating force Fbp is detected by the operating force sensor FBP. The input rod RDI is assembled to the housing HSG so as to be linearly movable in the direction of the central axis Jin. Here, the central axis Jin is also referred to as “input axis”. The input rod RDI is input to the differential mechanism DFR at a portion opposite to the mounting portion between the input rod RDI and the brake operation member BP.

  Similar to the input rod RDI, the output rod RDO is assembled to the housing HSG so as to be linearly movable in the direction of the central axis Jot. The output rod RDO is an output member of the actuator BAC, and presses the piston PNA in the master cylinder MC at its end.

  The input and output rods RDI and RDO are two different rod members, and are assembled to the housing HSG so as to be movable relative to each other. In the geometric relationship, the central axis Jin of the input rod RDI and the central axis Jot of the output rod RDO are parallel and separated by a distance greater than “0 (zero)”. That is, the axis Jin and the axis Jot are different axes and are not coaxial. Further, the output rod RDO, the cylindrical inner wall of the master cylinder MC, the first piston PNA, and the second piston PNB are arranged coaxially. Therefore, the central axis of these members is the axis Jot. The central axis line “Jot” is also referred to as “output axis line”.

  In the differential mechanism DFR, the output of the first electric motor MTF and the output of the second electric motor MTS are individually controlled. As a result, the force acting on the input rod RDI (that is, the operating force of the braking operation member BP) Fbp and the displacement of the output rod RDO (that is, the displacement of the piston PNA) Sro are independently adjusted. Here, the outputs of the first and second electric motors MTF and MTS (also collectively referred to as “MT”) are the rotation direction (normal rotation or reverse rotation) of each electric motor and the magnitude of torque. That's it.

  The differential mechanism DFR is built in the housing HSG. The differential mechanism DFR allows relative movement between the input rod RDI and the output rod RDO (ie, the relative movement is adjustable). The outputs of the first and second electric motors MTF and MTS are input to the differential mechanism DFR. Then, a force (an assisting force Fjs described later) is applied to the input rod RDI by the first electric motor MTF through the differential mechanism DFR. Further, the displacement Sro of the output rod RDO is controlled (adjusted) by the second electric motor MTS via the differential mechanism DFR. Therefore, the differential mechanism DFR is a power transmission mechanism having two inputs (three inputs if the input rod RDI and the first electric motor MTF are separate inputs) and one output. Details of the differential mechanism DFR will be described later.

  The electronic control unit (controller) ECU controls the first and second electric motors MTF and MTS based on the operation amount Bpa (generic name such as the operation displacement Sbp). Specifically, the microprocessor MPR of the controller ECU is programmed with a control algorithm for controlling two electric motors MT (a general term for the first and second electric motors MTF and MTS). A signal for control is calculated. In the controller ECU, a first drive circuit DRF that drives the first electric motor MTF and a second drive circuit DRS that drives the second electric motor MTS are provided. The first and second drive circuits DRF and DRS (collectively referred to as “DR”) are electric circuits configured by a plurality of switching elements, and are controlled by the microprocessor MPR.

  The controller ECU independently controls the relationship between the force Fbp acting on the input rod RDI and the displacement Sro of the output rod RDO (resulting in piston displacement in the master cylinder) by controlling the electric motor MT. That is, the relationship between the operation characteristics of the braking operation member BP (the relationship between the operation displacement Sbp and the operation force Fbp) and the friction braking force can be arbitrarily set. For example, the controller ECU increases the displacement Sbp (that is, the operation amount) of the input rod RDI when the drive motor MTD generates the regenerative braking force Rga (that is, when the drive motor MTD functions as a generator). As the force Fbp acting on the input rod RDI increases with the increase in Bpa), the output of the first electric motor MTF and the output of the second electric motor MTS are maintained so that the displacement Sro of the output rod RDO is maintained at zero. Control the output. This control is referred to as “regenerative cooperative control”. By the regenerative cooperative control, sufficient electric power regenerated by the drive motor MTD can be secured, and the operation characteristics of the brake operation member BP can be optimized. The actuator BAC has been described above.

  Master cylinder MC is mechanically connected to output rod RDO. Two first and second fluid paths (braking pipes) HKA and HKB (also simply referred to as “HK”) are fluidly connected to the master cylinder MC. When the brake operation member BP is operated, the brake fluid (brake fluid) is discharged (pumped) from the master cylinder MC to the fluid passage HK, and the brake fluid in the four wheel cylinders WC is pressurized. The components from the master cylinder MC to the wheel cylinder WC are fully filled with braking fluid and are in a liquid-tight state.

  In the master cylinder MC, two first and second hydraulic chambers Kma and Kmb are formed by the inner wall and the two pistons PNA and PNB. The master cylinder MC is a so-called tandem master cylinder. In the configuration of the diagonal fluid path, the first hydraulic chamber Kma of the master cylinder MC is fluidly connected to the wheel cylinders WCfr and WCrl through the first fluid path HKA. The second hydraulic chamber Kmb of the master cylinder MC is fluidly connected to the wheel cylinders WCfl and WCrr through the second fluid passage HKB. The configuration related to the first hydraulic chamber Kma and the configuration related to the second hydraulic chamber Kmb are basically the same.

  The first and second pistons PNA and PNB are pressed against the output rod RDO by two elastic members (for example, compression springs) PSA and PSB. Specifically, the second piston spring PSB is compressed and provided between the bottom of the inner cylinder of the master cylinder MC and the second piston PNB, and the first piston spring is provided between the second piston PNB and the first piston PNA. PSA is compressed and provided. Therefore, the output rod RDO and the first piston PNA are separable. However, since it is pressed against the output rod RDO by the first and second piston springs PSA and PSB, they are moved together during braking.

  When the braking operation member BP is operated, the input rod RDI is moved in the forward direction Hff. When the regenerative cooperative control is not executed, the output rod RDO is moved in the forward direction Hfp as the input rod RDI moves forward, and the first and second pistons PNA and PNB are pressed by the output rod RDO. When the first and second pistons PNA and PNB are moved in the forward direction Hfp, first, the fluid path to the reservoir RSV is blocked by the first and second pistons PNA and PNB. Further, when the first and second pistons PNA and PNB are advanced, the volumes of the first and second hydraulic pressure chambers Kma and Kmb are reduced, and the hydraulic pressure Pwa in the four wheel cylinders WC is increased.

  When the braking operation member BP is returned toward the initial position (the position corresponding to the non-braking state), the input rod RDI is moved in the reverse direction Hrf. When the regenerative cooperative control is not executed, the output rod RDO is moved in the backward direction Hrp as the input rod RDI is retracted, and the first and second pistons PNA and PNB are the first and second piston springs PSA, Pushed in the backward direction Hrp by PSB. Accordingly, the first and second pistons PNA and PNB are retracted, and the volumes of the first and second hydraulic pressure chambers Kma and Kmb are increased. As a result, the brake fluid returns to the master cylinder MC, and the hydraulic pressure Pwa in the four wheel cylinders WC is reduced.

  In the movement of the input rod RDI along the input axis Jin, the “forward direction Hff (left direction in the figure)” is a direction in which the wheel cylinder hydraulic pressure Pwa (that is, the braking torque of the wheel WH) increases. The forward direction Hff is also a direction in which the operation amount Bpa of the braking operation member BP increases. Conversely, the “reverse direction Hrf (right direction in the figure)” of the input rod RDI is a direction in which the wheel cylinder hydraulic pressure Pwa (that is, the braking torque of the wheel WH) decreases. The reverse direction Hrf is also a direction in which the operation amount Bpa of the braking operation member BP decreases.

  In the movement along the output axis Jot of the output rod RDO and the first and second pistons PNA and PNB, the “advance direction Hfp (left direction in the figure)” is the first and second hydraulic chambers Kma and Kmb. In this direction, the brake fluid is pumped from the master cylinder MC. Therefore, the movement of the first and second pistons PNA and PNB in the forward direction Hfp is a direction in which the wheel cylinder hydraulic pressure Pwa (that is, the braking torque of the wheel WH) increases. Conversely, the “retracting direction Hrp (rightward in the figure)” of the output rod RDO and the first and second pistons PNA and PNB is a direction in which the volumes of the first and second hydraulic chambers Kma and Kmb increase. Yes, the brake fluid is absorbed by the master cylinder MC. Accordingly, the movement of the first and second pistons PNA and PNB in the reverse direction Hrp is a direction in which the wheel cylinder hydraulic pressure Pwa (that is, the braking torque of the wheel WH) decreases.

  First and second hydraulic pressure sensors PMA and PMB are provided so as to detect the hydraulic pressures Pma and Pmb of the first and second hydraulic pressure chambers Kma and Kmb (resulting hydraulic pressure Pwa in the wheel cylinder WC). The first and second hydraulic pressures Pma and Pmb are input to the electronic control unit ECU.

<Driving process of electric motors MTF and MTS>
With reference to the control flow diagram of FIG. 2, an example of drive processing of the first and second electric motors MTF and MTS will be described. In the actuator BAC, by adjusting the outputs of the two electric motors MTF and MTS input to the differential mechanism DFR, the force Fbp acting on the input rod RDI (that is, the operating force Fbp of the braking operation member BP) and the output The displacement Sro of the rod RDO (that is, the operation displacement Sbp of the braking operation member BP) is controlled independently.

  First, in step S110, the braking operation amount Bpa and the regenerative braking force (actual value) Rga are read. In step S120, based on the braking operation amount Bpa, it is determined whether or not the operation amount Bpa is increasing. When the operation amount Bpa is increasing and step S120 is affirmed (in the case of “YES”), the process proceeds to step S130. On the other hand, if step S120 is negative (in the case of “NO”), the process proceeds to step S140.

  In step S130, based on the regenerative braking force Rga, it is determined whether or not regenerative braking is being performed. If regenerative braking is being performed with the regenerative braking force Rga being generated and step S130 is affirmed (in the case of “YES”), the process proceeds to step S170. On the other hand, when step S130 is negative (in the case of “NO”), the process proceeds to step S160.

  In step S140, based on the braking operation amount Bpa, it is determined whether or not the operation amount Bpa is constant. When the brake operation member BP is held and step S140 is affirmed (in the case of “YES”), the process proceeds to step S180. On the other hand, if the operation amount Bpa is decreasing and step S140 is negative ("NO"), the process proceeds to step S150.

  In step S150, based on the regenerative braking force Rga, it is determined whether or not regenerative braking is being performed. If the regenerative braking force Rga is being generated and step S150 is affirmed ("YES"), the process proceeds to step S190. On the other hand, when step S150 is negative (in the case of “NO”), the process proceeds to step S200.

  When the manipulated variable Bpa is increased and the regenerative braking force Rga is not generated, in step S160, the first electric motor MTF and the second electric motor MTS are both driven in the normal rotation directions Rff and Rfs. The Accordingly, the output rod RDO (resulting piston PNA) is moved in the forward direction Hfp by the first electric motor MTF and the second electric motor MTS, and as a result, a friction braking force is generated.

  When the operation amount Bpa is increased and the regenerative braking force Rga is generated, in step S170, the first electric motor MTF is driven in the forward rotation direction Rff, and the second electric motor MTS is driven in the reverse rotation direction Rrs. The Therefore, since the movement of the first electric motor MTF is suppressed (partially or entirely canceled out) by the second electric motor MTS, the output rod RDO (result, the first and second pistons PNA and PNB) , Slightly moved in the forward direction Hfp, or maintained in a movement stopped state (holding state). As a result, the friction braking force by the friction member MSB is slightly generated or not generated.

  When the braking operation member BP is held and the operation amount Bpa is kept constant, in step S180, the first electric motor MTF and the second electric motor MTS are both stopped. Accordingly, the output rod RDO (resulting pistons PNA and PNB) is not moved. When the operation amount Bpa is reduced, but the regenerative braking force is still generated, in step S190, the first electric motor MTF is driven in the reverse rotation direction Rrf, and the rotation of the second electric motor MTS is stopped. The When the operation amount Bpa is decreased and no regenerative braking force is generated, in step S200, the first electric motor MTF is driven in the reverse rotation direction Rrf. At this time, the second electric motor MTS is driven in the forward rotation direction Rfs by the amount driven in the reverse rotation direction Rrs in step S170, and then driven in the reverse rotation direction Rrs.

  When the first electric motor MTF is driven in the forward rotation direction Rff, the assisting portion Pjs of the first rack RKF receives a force in the forward direction Hff. Conversely, when the first electric motor MTF is driven in the reverse rotation direction Rrf, the assisting portion Pjs of the first rack RKF receives a force in the reverse direction Hrf. Further, when the second electric motor MTS is driven in the forward rotation direction Rfs, the second rack RKS receives a force in the forward direction Hfs. Conversely, when the second electric motor MTS is driven in the reverse rotation direction Rrs, the second rack RKS receives a force in the backward movement direction Hrs.

  The processing in step S170 and step S200 corresponds to the above-described regenerative cooperative control. In regenerative cooperative control, the output of the first electric motor MTF and the second electric motor MTS is adjusted so that the input rod RDI and the output rod RDO depend on each other in the “relationship between force and displacement”. Without being controlled independently. As a result, in the braking operation member BP, the characteristic (operation characteristic) of the operation force Fbp with respect to the operation displacement Sbp is always maintained at an appropriate characteristic. For this reason, even when the three states of “only the regenerative braking force is generated”, “the regenerative braking force and the frictional braking force are generated in cooperation” and “only the frictional braking force is generated” are transitioned. In each state transition, the operation characteristics are not changed suddenly, and smooth operation characteristics can be ensured.

  For example, when the drive motor (generator) MTD generates the regenerative braking force Rga (Rga> 0), “the displacement of the input rod RDI (that is, the operation displacement Sbp of the brake operation member BP increases). On the other hand, the state in which the force acting on the input rod RDI (that is, the operating force Fbp of the braking operation member BP is increased) and the state that the displacement Sro of the output rod RDO (that is, the displacement of the piston PNA) is zero (That is, a state in which no friction braking force is generated) can be achieved. For this reason, in a state where the operation characteristics of the braking operation member BP (relationship of the operation force Fbp with respect to the operation displacement Sbp) are appropriately maintained, the coordination between the regenerative braking force and the friction braking force (the braking force of the entire vehicle Contribution) can be adjusted as appropriate. As a result, since the regenerative braking force is used effectively, the kinetic energy at the time of vehicle deceleration can be efficiently recovered. That is, the power that can be regenerated is maximized, and the characteristic (operation characteristic) of the operation force Fbp with respect to the operation displacement Sbp can be suitably maintained.

  In the drive processing examples of the first and second electric motors MTF and MTS described above, the actual value Rga of the regenerative braking force is adopted. Instead, the target value Rgt of the regenerative braking force calculated in the driving controller ECD can be adopted. In any case, the regenerative cooperative control is executed according to the braking operation amount Bpa based on the presence or absence of the regenerative braking force.

<Differential mechanism DFR>
The configuration and operation of the differential mechanism DFR provided in the actuator BAC will be described in detail with reference to the schematic diagram of FIG. Since the differential mechanism DFR is employed for the brake actuator BAC, the force and the displacement are separated by the first and second electric motors MTF and MTS and are independently controlled independently. For this reason, the brake control device capable of regenerative cooperative control can be configured with one master cylinder MC without adopting two master cylinders as in Patent Document 1.

<< Configuration of differential mechanism DFR >>
First, the configuration of the differential mechanism DFR will be described. The differential mechanism DFR is formed by a rack and pinion mechanism (a conversion mechanism between rotational motion and linear motion). In the rack-and-pinion mechanism, a “circular gear called a pinion gear” and a “rack in which teeth (rack gear) are provided on a flat rod so as to mesh with the pinion gear” are combined. The differential mechanism DFR includes “first and second pinion gears PNF and PNS”, “first and second racks RKF and RKS”, “input and output rods RDI and RDO”, and an output pinion gear PNO. The Here, “first and second pinion gears PNF and PNS”, “first and second racks RKF and RKS”, and output pinion gear PNO are output (power) of “first and second electric motors MTF and MTS”. ).

  The differential mechanism DFR is composed of three transmission mechanisms. The output of the first electric motor MTF is transmitted to the input rod RDI by the “first transmission mechanism”. Specifically, the combination (rack and pinion mechanism) of the first pinion gear PNF and the first input rack gear portion Gfa of the first rack RKF, which will be described below, corresponds to the first transmission mechanism. The output of the second electric motor MTS is transmitted to the output rod RDO by the “second transmission mechanism”. The combination of the second pinion gear PNS and the second input rack gear part Gsa of the second rack RKS and the combination of the output pinion PNO and the second output rack gear part Gsb of the second rack RKS correspond to the second transmission mechanism. The output of the input rod RDI is transmitted to the output rod RDO by the “third transmission mechanism”. The combination of the output pinion gear PNO and the first output rack gear portion Gfb of the second rack RKF corresponds to the third transmission mechanism. The relative movement between the input rod RDI and the output rod RDO is adjusted by the differential mechanism DFR.

  The first and second electric motors MTF and MTS are fixed inside the housing HSG by a fixing member KTE. A first pinion gear PNF is fixed to the output shaft portion Shf of the first electric motor MTF. Similarly, the second pinion gear PNS is fixed to the output shaft portion Shs of the second electric motor MTS. In addition, between the rotating shaft (first rotating shaft) Shf of the first electric motor MTF and the first pinion gear PNF, and between the rotating shaft (second rotating shaft) Shs of the second electric motor MTS and the second pinion gear PNS. A reduction gear may be provided in at least one of the intervals.

  A connecting rod RDC is rotatably connected to the braking operation member BP by a clevis (U-shaped link). In the connecting rod RDC, the opposite side of the clevis portion is processed into a spherical shape and mechanically connected to the input rod RDI. That is, the input rod RDI and the braking operation member BP are mechanically connected via the connection rod RDC. Although the braking operation member BP rotates at the attachment portion of the vehicle body BD, the rotation motion of the braking operation member BP is effectively converted into the linear motion of the input rod RDI by the connecting rod RDC. The front end portion of the input rod RDI (the side opposite to the end portion connected to the braking operation member BP) is fixed to the first rack RKF.

  The first rack RKF can move smoothly along the input axis Jin (the central axis of the input rod RDI) with respect to the housing HSG. The first rack RKF is composed of two members, an input part Pin and an assisting part Pjs. This configuration is referred to as a “split configuration”. The input portion Pin and the assisting portion Pjs are formed such that relative displacement is possible along the input axis Jin. An input rod RDI is fixed to the input portion Pin, and a first output rack gear Gfb is formed. The first output rack gear Gfb is engaged with the output pinion gear PNO. In addition to the first output rack gear Gfb, a first input rack gear Gfa is formed in the assisting portion Pjs, and the first input rack gear Gfa is engaged with the first pinion gear PNF. Accordingly, the rotational power of the first electric motor MTF is input to the assisting portion Pjs via the first pinion gear PNF. In the first rack RKF, the first output rack gear Gfb is located on the back side of the first input rack gear Gfa (opposite side across the input axis Jin).

  The input rod RDI is fixed to the first rack RKF (in particular, the input part Pin). Accordingly, the output of the first electric motor MTF is converted from rotational motion to translational motion (movement in the parallel direction) via the power transmission mechanism (first pinion gear PNF, first rack RKF) and transmitted to the input rod RDI. Is done.

  The input portion Pin is provided with a step perpendicular to the input axis Jin, and a pressure receiving surface Min facing the backward direction Hrf is formed. Similarly, the assisting portion Pjs is provided with a step perpendicular to the input axis Jin, and an assisting surface Mjs facing the forward direction Hff is formed. And the force Fjs of the advancing direction Hff is provided by the surface contact of the assistance surface Mjs and the pressure receiving surface Min. Here, the force Fjs acting on the input portion Pin from the assisting portion Pjs is referred to as “assistance force”.

  Power transmission (that is, power transmission) between the input part Pin and the assisting part Pjs has directionality. The assisting part Pjs transmits power to the input part Pin in the forward direction Hff, but does not transmit power to the backward direction Hrf. On the other hand, the input part Pin transmits power to the assisting part Pjs in the backward direction Hrf but does not transmit power in the forward direction Hff. In other words, the force is transmitted in the direction in which the assisting portion Pjs approaches the input portion Pin, but the force is not transmitted in the direction in which the assisting portion Pjs moves away from the input portion Pin. Therefore, in the first rack RKF, the assisting force Fjs generated by the first electric motor MTF is transmitted in the forward direction Hff due to the configuration of the input part Pin and the assisting part Pjs, but the backward direction Hrf (forward) (The direction opposite to the direction Hff) is not transmitted.

  The housing HSG is provided with a first stopper STF so as to prevent the movement of the first rack RKF in the backward direction Hrf. The assisting portion Pjs of the first rack RKF is pressed in the backward direction Hrf by the first rack elastic body SPF (for example, a compression spring). When the first rack elastic body SPF is provided between the housing HSG and the assisting portion second end face Mjp of the assisting portion Pjs, and the first electric motor MTF is not energized, the assisting portion first of the assisting portion Pjs. The end face Mje is pressed against the first stopper STF provided in the housing HSG. When the braking operation member BP is not operated by the first rack elastic body SPF (that is, when “Bpa = 0”), the assisting portion first end face Mje is in contact with the first stopper STF.

  Similarly, the input portion Pin of the first rack RKF is pressed in the backward direction Hrf by the return elastic body SPI (for example, a compression spring). A return elastic body SPI is provided between the housing HSG and the input portion second end face Mip of the input portion Pin. In a normal case, the input portion Pin and the assisting portion Pjs are moved together. Here, “normal case” means “when the first electric motor MTF operates properly and its power can be generated”, and “the operation of the braking operation member BP is not sudden, and the first electric motor This is a case where the response of the MTF can sufficiently follow the operation ".

  Similar to the first rack RKF, two rack gears Gsa and Gsb are formed in the second rack RKS. The output pinion gear PNO is meshed with the first output rack gear Gfb of the first rack RKF and also meshed with the second output rack gear Gsb of the second rack RKS. In the second rack RKS, a second input rack gear Gsa is formed on the back side of the second output rack gear Gsb, separately from the second output rack gear Gsb. The second input rack gear Gsa is engaged with the second pinion gear PNS. Accordingly, the output of the second electric motor MTS is converted from rotational motion to translational motion and transmitted to the output rod RDO via the power transmission mechanism (second pinion gear PNS, second rack RKS, output pinion gear PNO).

  The housing HSG is provided with a second stopper STS so as to prevent the movement of the second rack RKS in the forward direction Hfs. The second rack RKS is pressed in the forward direction Hfs by a second rack elastic body SPS (for example, a compression spring). A second rack elastic body SPS is provided between the housing HSG and the first end face Msp of the second rack RKS. When the braking operation member BP is not operated (that is, when “Bpa = 0”), the second end surface Mse of the second rack RKS is provided in the housing HSG by the second rack elastic body SPS. 2 Pressed against and in contact with the stopper STS. Therefore, this position is the initial position of the second rack RKS corresponding to the state where the braking operation member BP is not operated. Further, when the second electric motor MTS is not energized, the second rack RKS is moved in the forward direction Hfs by the second rack elastic body SPS, and the second end face Mse is pressed against the second stopper STS.

  A regenerative stopper STR is provided in the housing HSG on the opposite side of the second stopper STS with respect to the second rack RKS so as to prevent the second rack RKS from moving in the backward direction Hrs. The movement of the second rack RKS is limited to a predetermined displacement hrg by the second stopper STS and the regenerative stopper STR. In other words, the range in which the second rack RKS can move is from its initial position (contact position with the second stopper STS corresponding to non-braking) to the predetermined displacement hrg. The movement of the second rack RKS in the reverse direction Hrs corresponds to the regenerative cooperative control so as not to generate the friction braking force. For example, it may be set in advance as a value corresponding to a vehicle deceleration (for example, 0.2 to 0.3 G) that can be generated by the electric drive device EDS (that is, the regenerative braking device). Here, the vehicle deceleration that can be generated in the regenerative braking device EDS is determined based on the capacity of the generator MTD, the energization amount of the controller ECD, and the like. Even when the controller ECU or the second electric motor MTS has malfunctioned due to the displacement limit hrg, the friction braking force can be reliably generated with the operation of the braking operation member BP.

  The output pinion gear PNO is fixed to the output rod RDO so as to be rotatable by the rotary shaft SFO. The output rod RDO can move smoothly along the output axis Jot (center axis of the output rod RDO) with respect to the housing HSG. The central axis Jin and the central axis Jot are separate axes that are parallel to each other, and are referred to as “different axis configurations”. The first and second racks RKF, RKS and the output rod RDO can be smoothly moved along the center axis Jin (center axis Jot) with respect to the housing HSG. That is, in the differential mechanism DFR, the first and second racks RKF, RKS, and the output rod RDO can each move in parallel and linearly (in other words, relative movement can be prevented). Permissible).

  When a tandem master cylinder is employed as the master cylinder MC, two hydraulic chambers Kma and Kmb are arranged in series. For this reason, the dimension of the center axis direction Jot of the master cylinder MC becomes long. However, since the differential mechanism DFR having a different shaft configuration is employed, the axial dimension is shortened and the structure is simplified. As a result, downsizing of the entire apparatus can be achieved. The configuration of the differential mechanism DFR has been described above.

≪Operation of differential mechanism DFR≫
Next, the operation of the differential mechanism DFR will be described. As described above, in the movement of each element (such as the first rack RKF) constituting the differential mechanism DFR, the movement in the “forward direction Hff, Hfs, Hfp” corresponds to an increase in the hydraulic pressure Pwa of the wheel cylinder WC. . The linear motion in the forward direction corresponds to the rotational motion in the “forward rotation directions Rff, Rfs” of the first and second electric motors MTF, MTS. The movement in the “reverse direction Hrf, Hrs, Hrp”, which is the direction opposite to the forward direction Hff, Hfs, Hfp, corresponds to a decrease in the hydraulic pressure Pwa of the wheel cylinder WC. The rectilinear motion in the reverse direction corresponds to the rotational motion in the “reverse rotation directions Rrf, Rrs” of the first and second electric motors MTF, MTS.

  When the braking operation amount Bpa is increased and the input rod RDI is moved in the forward direction Hff (corresponding to the increase in the operation amount Bpa), the first electric motor MTF is driven in the forward rotation direction Rff. Thereby, the rotational power of the first electric motor MTF is transmitted to the assisting part Pjs of the first rack RKF via the first pinion gear PNF. Since the power from the assisting part Pjs to the input part Pin is transmitted in the forward direction Hff, the assisting part Pjs presses the input part Pin in the forward direction Hff.

  The assisting force Fjs is generated when the output of the first electric motor MTF is transmitted to the input rod RDI by the transmission mechanism (first pinion gear PNF, first rack RKF). The assisting force Fjs helps the driver to operate the braking operation member BP, and the operation force Fbp of the braking operation member BP is reduced. That is, the boost function can be achieved by the first electric motor MTF, the first pinion gear PNF, and the first rack RKF.

  The movement of the input rod RDI in the forward direction Hff is transmitted to the output rod RDO via the input portion Pin of the first rack RKF and the output pinion gear PNO. As a result, the output rod RDO also tends to move in the forward direction Hfp. However, the movement of the output rod RDO depends on the movement (displacement) of the second rack RKS driven by the second electric motor MTS.

  When the driving electric motor (generator) MTD generates the regenerative braking force Rga and the regenerative braking force Rga is sufficient for deceleration of the vehicle, it is not necessary to generate the friction braking force. Therefore, even if the input rod RDI is moved in the forward direction Hff by the braking operation member BP, the output rod RDO is not moved forward Hfp, and the generation of the brake fluid pressure is prevented. Specifically, the second electric motor MTS is driven in the reverse rotation direction Rrs, and the second rack RKS is moved in the reverse movement direction Hrs. As a result, power transmission from the first rack RKF is canceled out, so that the occurrence of displacement of the output rod RDO is avoided, and sufficient energy regeneration can be performed by the drive motor (generator) MTD.

  When the rotational speed of the wheel WH decreases and the regenerative braking force is insufficient for the required deceleration of the vehicle, a friction braking force (that is, an increase in the braking hydraulic pressure Pwa) is required. In this case, the second electric motor MTS is stopped or driven in the forward direction Rfs, and the second rack RKS is stopped or moved in the forward direction Hfs. Thereby, the output rod RDO is moved in the forward direction Hfp, and the regenerative braking force and the friction braking force can be controlled in cooperation. Further, when the regenerative braking force is not generated, the second electric motor MTS is driven in the forward rotation direction Rfs, the output rod RDO is moved in the forward movement direction Hfp, and the friction braking force increases according to the braking operation amount Bpa. Is done.

  When the first electric motor MTF or the first drive circuit DRF is malfunctioning, the first electric motor MTF is not energized. Specifically, in the controller ECU, signals from each sensor (for example, the rotation angle of the first electric motor MTF and the current value of the first drive circuit DRF) are taken into consideration, and the first electric motor MTF and the first At least one malfunctioning state of the drive circuit DRF is determined. When the malfunction state is not determined (that is, when the first electric motor MTF and the first drive circuit DRF are in proper operation), the first electric motor MTF is energized, but when the malfunction condition is determined. The power supply to the first electric motor MTF is stopped. Therefore, in the malfunctioning state, the first electric motor MTF does not generate rotational power and does not generate the assisting force Fjs.

  In the above malfunctioning state, when the braking operation member BP is operated and the input rod RDI is moved in the forward direction Hff, the input portion Pin does not exert a force on the assisting portion Pjs due to the divided configuration. The assisting part Pjs is not moved, and only the input part Pin is moved in the forward direction Hff. In this case, since the assisting portion Pjs is pressed by the first rack elastic body SPF, the assisting portion Pjs remains in a position where it comes into contact with the first stopper STF.

  When the first rack RKF has an integral structure, the first electric motor MTF is rotated by the movement of the first rack RKF as the input rod RDI moves. For this reason, the operating force Fbp of the braking operation member BP increases by the amount by which the first electric motor MTF is rotated. That is, the first electric motor MTF serves as a resistance for the braking operation. In order to solve this problem, the first rack RKF is divided into “two members Pin, Pjs, and the power transmission between the input portion Pin and the assisting portion Pjs is advanced from the assisting portion Pjs to the input portion Pin. A division configuration is adopted that is achieved only in the direction Hff and in the backward direction Hrf from the input part Pin to the assisting part Pjs. In other words, in the split configuration, power transmission is not performed in the backward direction Hrf from the assisting part Pjs to the input part Pin and in the forward direction Hff from the input part Pin to the assisting part Pjs. As a result, it is possible to suppress the operation force Fbp from being unnecessarily increased when the first electric motor MTF or the like is malfunctioning.

  The above-described divided configuration of the first rack RKF is effective even when the braking operation member BP is suddenly operated. The output response of the first electric motor MTF is limited. When the braking operation member BP is operated extremely quickly, the response of the first electric motor MTF may not be in time, and the first electric motor MTF may become a resistance in the braking operation. When the first electric motor MTF is designed so as to cope with the situation, the first electric motor MTF is very large. However, since the first rack RKF has a divided configuration, even when the braking operation member BP is operated at a very high speed, the first electric motor MTF does not become a resistance, and suitable braking is performed. Operating characteristics can be ensured.

  When the braking operation member BP is returned and the input rod RDI is moved in the backward direction Hrf (corresponding to the decrease in the operation amount Bpa), the first electric motor MTF is driven in the reverse direction Rrf. Further, the assisting portion Pjs is pressed in the backward direction Hrf by the first rack elastic body SPF, and the input portion Pin is pressed in the backward direction Hrf by the return elastic body SPI. If a malfunction occurs in the second electric motor MTS or the like while the braking operation member BP is being returned, the input portion Pin and the assisting portion Pjs are moved backward by the return elastic body SPI and the first rack elastic body SPF. It is moved in the direction Hrf. Even in the malfunctioning state, the first rack RKF is in a state where both the “input portion Pin is in contact with the first stopper STF and the input portion Pin is in contact with the assisting portion Pjs” and the non-braking position (also referred to as “initial position”). Until it says).

  When the movement of the second rack RKS is locked, when the input portion Pin of the first rack RKS is moved in the forward direction Hff, the output rod RDO is moved along the output axis Jot via the output pinion gear PNO. It is moved in the forward direction Hfp. As a result, hydraulic pressures Pma and Pmb are generated in the master cylinder MC. When the second electric motor MTS is driven in the reverse rotation direction Rrs and the second rack RKS is moved in the reverse movement direction Hrs in a state where the input portion Pin is moved in the forward movement direction Hff, the output by the first output rack gear portion Gfb Since the rotation of the pinion gear PNO is absorbed by the movement of the second output rack gear portion Gsb, the movement amount of the output rod RDO in the forward direction Hfp is reduced compared to the movement amount when the second rack RKS is locked. For example, when the moving speed in the forward direction Hff of the input part Pin (that is, the first output rack gear part Gfb) and the moving speed in the backward direction Hrs of the second rack RKS (that is, the second output rack gear part Gsb) are the same. Occurs in the idle state of the output pinion gear PNO (the output rod RDO is not moved even if the input rod RDI is moved), and the hydraulic pressures Pma and Pmb of the master cylinder MC are not generated. As described above, regenerative cooperative control (control in which regenerative braking force and friction braking force are coordinated by relative movement (displacement) between the first rack RKF (particularly, the input unit Pin) and the second rack RKS. ) Can be achieved.

  Similarly to the first electric motor MTF, when at least one of the second electric motor MTS and the second drive circuit DRS is out of order, the second electric motor MTS is not energized. Specifically, in the controller ECU, the signals of each sensor (for example, the rotation angle of the second electric motor MTS and the current value of the second drive circuit DRS) are taken into consideration, and the second electric motor MTS and the second At least one malfunctioning state of the drive circuit DRS is determined. When the malfunction state is not determined (that is, when the second electric motor MTS and the second drive circuit DRS are in proper operation), the second electric motor MTS is energized, but when the malfunction condition is determined. The power supply to the second electric motor MTS is stopped. Accordingly, in the malfunctioning state, the second electric motor MTS is freely rotated and is not locked, so that the locked state of the second rack RKS cannot be maintained. For this reason, the moving amount of the output rod RDO may be reduced from a desired amount, and the increase of the hydraulic pressures Pma and Pmb of the master cylinder MC may be prevented.

  In order to solve this problem, the distance that the second rack RKS can move is within the range of the predetermined displacement hrg by the second stopper STS and the regeneration stopper STR (that is, the regeneration from the contact position with the second stopper STS). The range up to the contact position with the stopper STR). In this case, when the input rod RDI is moved in the forward direction Hff, the second rack RKS is moved in the reverse direction Hrs by the output pinion gear PNO. After the second rack RKS comes into contact with the regenerative stopper STR, the movement of the second rack RKS is restricted and is not moved any further. As a result, the second rack RKS is locked, the output rod RDO is moved in the forward direction Hfp, and the hydraulic pressures Pma and Pmb of the master cylinder MC are increased.

  When the braking operation amount Bpa is equal to or less than the predetermined amount bpx, the second rack RKS is in contact with the second stopper STS even when the second electric motor MTS is not energized (the initial position of the second rack RKS). ) Is maintained, the load at the time of mounting the second rack elastic body SPS can be set larger than the predetermined load fsx. Here, the predetermined load fsx is set based on the spring constant and the mounting height. When the input rod RDI is moved in the forward direction Hff, a force is applied to move the second rack RKS in the reverse direction Hrs via the output pinion gear PNO. The second rack RKS is prevented from moving by applying an elastic force (load at the time of mounting) of the second rack elastic body SPS to the second rack RKS so as to counteract this force, and the second rack RKS is blocked by the second stopper. The state in contact with the STS is maintained.

  In the above configuration, when the input rod RDI is moved in the forward direction Hff, the second rack RKS receives a force in the reverse direction Hrs by the output pinion gear PNO. However, since the force in the forward direction Hfs by the second rack elastic body SPS is larger than the force in the reverse direction Hrs received from the output pinion gear PNO, the second rack RKS remains in contact with the second stopper STS. As a result, the output rod RDO is moved in the forward direction Hfp, and the hydraulic pressures Pma and Pmb of the master cylinder MC are increased. When the hydraulic pressures Pma and Pmb of the master cylinder MC gradually increase, the output rod RDO receives a force in the reverse direction Hrp from the piston PNA, and the force in the reverse direction Hrs of the second rack RKS increases. When the operation amount Bpa reaches the predetermined amount bpx, the force in the reverse direction Hrs received from the output pinion gear PNO becomes larger than the force in the forward direction Hfs by the second rack elastic body SPS, and the second rack RKS is moved in the reverse direction. Moved to Hrs. Since the position of the output rod RDO is constant over the distance hrg until the second rack RKS contacts the regenerative stopper STR, the hydraulic pressures Pma and Pmb of the master cylinder MC are maintained. After the second rack RKS hits the regenerative stopper STR, the locked state of the second rack RKS is achieved again, so that the output rod RDO is displaced in the forward direction Hfp, and the hydraulic pressure Pma of the master cylinder MC , Pmb is increased.

  For example, the predetermined amount bpx is set as a value corresponding to the deceleration (about 0.3 G) of the vehicle generated during general braking. In this case, the contact state between the second rack RKS and the second stopper STS is maintained until the vehicle deceleration reaches a set value (for example, 0.3 G). The two racks RKS and the second stopper STS are separated. Since the predetermined amount bpx is set as a value that does not easily occur in a general braking operation, the operation characteristics when the second electric motor MTS is malfunctioning can be ensured satisfactorily.

<First rack RKF>
The first rack RKF of the differential mechanism DFR will be described with reference to FIG. The first rack RKF is composed of two members Pin and Pjs. This configuration is referred to as a “split configuration”. FIG. 4A shows a case where the first electric motor MTF operates properly and the input part Pin and the assisting part Pjs are moved together. FIG. 4B shows a case where the operation of the first electric motor MTF is inappropriate and only the input portion Pin is moved.

  The input part Pin has two surfaces Mia and Mib parallel to the input axis Jin (center line of the input rod RDI). The distance between the input portion front half surface Mia and the input axis Jin is shorter than the distance between the input portion rear half surface Mib and the input axis Jin. That is, the input portion front half surface Mia is closer to the input axis Jin than the input portion rear half surface Mib, and there is a step at the boundary between the input portion front half surface Mia and the input portion rear half surface Mib to form the pressure receiving surface Min. The pressure receiving surface Min faces the backward direction Hrf. The input rod RDI is fixed to one end (input unit first end surface) Mie of the end surface (surface orthogonal to the input axis Jin) of the input unit Pin. A return elastic body SPI is provided on the other end face (input section second end face) Mip opposite to the input section first end face Mie, and is pressed by the return elastic body SPI.

  Similar to the input part Pin, the assisting part Pjs has two surfaces Mja and Mjb parallel to the input axis Jin. The distance between the front half surface Mja of the assisting portion and the input axis Jin is shorter than the distance between the rear half surface Mjb of the assisting portion and the input axis Jin. That is, the assisting portion front half surface Mja is closer to the input axis Jin than the assisting portion latter half surface Mjb, and there is a step at the boundary between the assisting portion first half surface Mja and the assisting portion latter half surface Mjb, thereby forming the assisting surface Mjs. The assisting surface Mjs faces the forward direction Hff. The assisting surface Mjs of the assisting portion Pjs contacts the pressure receiving surface Min of the input portion Pin on the surface. For example, the pressure receiving surface Min and the assisting surface Mjs are orthogonal to the input axis Jin. One of the end surfaces of the assisting portion Pjs (surface orthogonal to the input axis Jin) (the assisting portion first end surface) Mje can contact the first stopper STF. A first rack elastic body SPF is provided on the other end face (assistance portion second end face) Mjp opposite to the assisting portion first end face Mje, and is pressed by the first rack elastic body SPF.

  Transmission of force between the input portion Pin and the assisting portion Pjs is performed by surface contact between the pressure receiving surface Min and the assisting surface Mjs. Since the pressure receiving surface Min faces the backward direction Hrf and the assisting surface Mjs faces the forward direction Hff, force transmission has directionality. Specifically, the force is transmitted in the direction in which the pressure receiving surface Min and the assisting surface Mjs approach each other, but the force is not transmitted in the direction in which the pressure receiving surface Min and the assisting surface Mjs separate from each other. Accordingly, the assisting portion Pjs transmits power to the input portion Pin in the forward direction Hff, and the input portion Pin transmits power to the assisting portion Pjs in the backward direction Hrf. On the other hand, the assisting part Pjs does not transmit power in the backward direction Hrf to the input part Pin, and the input part Pin does not transmit power in the forward direction Hff to the assisting part Pjs.

  A case where the operation of the first electric motor MTF is appropriate will be described with reference to FIG. When the operation of the braking operation member BP (that is, the braking operation amount Bpa) is increased, the input portion Pin is moved in the forward direction Hff by the input rod RDI. Further, the assisting portion Pjs is moved in the forward direction Hff by the first pinion gear PNF by the first electric motor MTF driven based on the operation amount Bpa. In this case, the rotational power of the first electric motor MTF is applied from the assisting surface Mjs to the pressure receiving surface Min and acts as the assisting force Fjs. As a result, the driver's operating force Fbp is adjusted to be reduced by the assisting force Fjs. In addition, when the pressure receiving surface Min and the assisting surface Mjs are formed as a plane perpendicular to the input axis Jin, the assisting force Fjs is transmitted along the input axis Jin, so that the transmission efficiency is high. .

  When the operation of the braking operation member BP is reduced, the input rod RDI is pulled back by the pedal return spring SPB. The input part Pin is moved in the backward direction Hrf by the input rod RDI. Further, the assisting portion Pjs is moved in the backward direction Hrf by the first electric motor MTF while maintaining the assisting force Fjs. When the operation of the braking operation member BP is canceled by the return elastic body SPI and the first rack elastic body SPF (that is, when “Bpa = 0”), the input portion Pin and the assisting portion Pjs are reliably The pressure receiving surface Min and the assisting surface Mjs can be brought into contact with each other, and the assisting portion first end surface Mje can be brought into contact with the first stopper STF.

  A case where the operation of the first electric motor MTF is inappropriate will be described with reference to FIG. When the operation of the braking operation member BP is increased, the input part Pin is moved in the forward direction Hff, but the first electric motor MTF remains stopped, so that the assisting part Pjs is not moved and the assisting part first The state where the first end face Mje is in contact with the first stopper STF is maintained. That is, since power transmission in the forward direction Hff from the input part Pin toward the assisting part Pjs is not performed, the surface contact between the input part Pin and the assisting part Pjs is released. In this case, since the assisting force Fjs is not applied, the input part Pin is moved only by the driver's operating force Fbp. However, since the first electric motor MTF is not rotated by the input rod RDI, an increase in the operating force Fbp can be suppressed. When the operation of the braking operation member BP is decreased, the input portion Pin is moved in the backward direction Hrf by the input rod RDI and the return elastic body SPI.

  As described above, since the first rack RKF has a split configuration, the power from the first electric motor MTF to the input rod RDI is transmitted in the forward direction Hff, but the backward direction Hrf (forward direction). It is not transmitted in the opposite direction to Hff. Specifically, the assisting portion Pjs has an assisting surface Mjs that faces the forward direction Hff, and the input portion Pin has a pressure receiving surface Min that faces the backward direction Hrf. Therefore, the force from the assisting surface Mjs to the pressure receiving surface Min is applied in the forward direction Hff by surface contact between the assisting surface Mjs and the pressure receiving surface Min. However, since the assisting surface Mjs is separated from the pressure receiving surface Min, the assisting surface Mjs is not applied in the backward direction Hrf. For this reason, the first electric motor MTF is not rotated by the input rod RDI in a malfunctioning state of the first electric motor MTF. For this reason, the driver's operating force Fbp is not consumed for rotating the first electric motor MTF. As a result, it is possible to suppress the operation force Fbp from being unnecessarily increased when the first electric motor MTF or the like is malfunctioning.

  In addition, the divided configuration of the first rack RKF has the same effect even when the braking operation member BP is suddenly operated. Although there is a limit to the output of the first electric motor MTF, when the braking operation member BP is operated very quickly, the surface contact between the input portion Pin and the assisting portion Pjs is released. For this reason, even in the case of a very fast braking operation, it is possible to avoid the first electric motor MTF from becoming a resistance and to ensure good operating characteristics.

<Other embodiments>
Hereinafter, other embodiments (modifications) will be described. Also in these cases, the brake actuator BAC has the same effect as described above (ensurement of operation characteristics when the first electric motor MTF or the like is malfunctioning or suddenly operated).

  In the above embodiment, the disk-type braking device is exemplified as the device that applies the braking torque to the rotating member KT (that is, the wheel WH). Instead, a drum type braking device (drum brake) may be employed. In the case of a drum brake, a brake drum is employed instead of the caliper CP. The friction member is a brake shoe, and the rotating member KT is a brake drum.

  In the above-described embodiment, a diagonal type (also referred to as “X type”) is exemplified as the two systems of hydraulic circuits (configuration of the braking pipe). Instead, a front-rear type (also referred to as “H type”) configuration may be employed. In this case, the first fluid path HKA is fluidly connected to the front wheel cylinders WCfr, WCfl, and the second fluid path HKB is fluidly connected to the rear wheel cylinders WCrr, WCrl.

  In the above embodiment, an example in which an electric motor for driving is employed as the generator MTD has been described. However, as the generator MTD, one that does not function for driving and has only a power generation function may be employed. Even in this case, the generator MTD is mechanically connected to the wheel WH, and at the time of vehicle deceleration, the kinetic energy of the vehicle is regenerated as electric power. At this time, a regenerative braking force is applied to the wheel WH.

  In the above embodiment, the three stoppers STF, STS, and STR are exemplified as being fixed to the housing HSG. However, the stoppers STF, STS, STR may be any ones that can restrain the displacement of the first and second racks RKF, RKS. Therefore, at least one of the stoppers STF, STS, and STR can be fixed to other components instead of the housing HSG. Even in this case, the movement can be prevented by the stopper so that the racks RKF and RKS are not displaced.

  In the embodiment described with reference to FIG. 3, the first pinion gear PNF is fixed to the output shaft Shf of the first electric motor MTF, and the second pinion gear PNS is fixed to the rotation shaft Shs of the second electric motor MTS. At least one of the first pinion gear PNF and the second pinion gear PNS can be mechanically connected to the rotation shafts (output shafts) Shf and Shs of the electric motors MTF and MTS via a reduction gear. Even in this case, the first pinion gear PNF is mechanically connected to the rotation shaft Shf of the first electric motor MTF, and the second pinion gear PNS is mechanically connected to the rotation shaft Shs of the second electric motor MTS.

  In the above embodiment, the displacement of the second rack RKS is limited within the range of the predetermined displacement hrg. Instead, the movement of the constituent members of the second transmission mechanism in the backward direction Hrs can be limited within the range of the predetermined displacement hrg. Power is transmitted from the second electric motor MTS to the output rod RDO in the order of “PNS → Gsa → Gsb → PNO” by the second transmission mechanism. For example, in the second pinion gear PNS, the rotational displacement in the reverse direction Hrs (that is, the reverse direction Rrs) is limited within the range of the predetermined displacement hrg.

BP ... braking operation member, WC ... wheel cylinder, MC ... master cylinder, BAC ... braking actuator, MTF / MTS ... first and second electric motors, DFR ... differential mechanism, RDI / RDO ... input / output rod, RKF. RKS: first and second racks, PNF / PNS: first and second pinion gears, PNO: output pinion gear, Pin: input unit, Pjs: assisting unit, Fjs: assisting force, ECU: controller.

Claims (6)

A vehicle braking control device that generates braking torque on wheels of the vehicle by pumping braking fluid from a master cylinder to a wheel cylinder in response to an operation of a braking operation member of the vehicle,
An input rod connected to the braking operation member;
An output rod that is movable parallel to the central axis of the input rod and presses a piston in the master cylinder;
A first electric motor for generating a supporting force for the input rod;
A second electric motor for adjusting the displacement of the output rod;
A first transmission mechanism for transmitting an output of the first electric motor to the input rod; a second transmission mechanism for transmitting an output of the second electric motor to the output rod; and an output of the input rod to the output rod. A differential mechanism configured with a third transmission mechanism for transmitting, and adjusting a relative movement between the input rod and the output rod;
A controller that controls the first electric motor and the second electric motor to independently control the operating force acting on the input rod and the displacement;
With
The braking control device for a vehicle, wherein the assisting force is generated in a forward direction corresponding to an increase in an operation amount of the braking operation member, but is not generated in a reverse direction opposite to the forward direction. A vehicle braking control device that generates braking torque on wheels of the vehicle by pumping braking fluid from a master cylinder to a wheel cylinder in response to an operation of a braking operation member of the vehicle,
An input rod connected to the braking operation member;
An output rod that is movable parallel to the central axis of the input rod and presses a piston in the master cylinder;
A first electric motor for generating a supporting force for the input rod;
A second electric motor for adjusting the displacement of the output rod;
A first pinion gear connected to the first electric motor;
A second pinion gear connected to the second electric motor;
A first input rack gear portion meshing with the first pinion gear, and a first rack having a first output rack gear portion different from the first input rack gear portion;
A second input rack gear portion meshing with the second pinion gear, and a second rack having a second output rack gear portion different from the second input rack gear portion;
An output pinion gear supported rotatably on the output rod and meshing with the first output rack gear portion and the second output rack gear portion;
A controller that controls the first electric motor and the second electric motor to independently control the operating force acting on the input rod and the displacement;
With
The braking control device for a vehicle, wherein the assisting force is generated in a forward direction corresponding to an increase in an operation amount of the braking operation member, but is not generated in a reverse direction opposite to the forward direction. The vehicle braking control device according to claim 2,
The first rack is
An input unit connected to the input rod and having the second input rack gear unit;
The input portion is movable in parallel with the central axis, and includes an assisting portion having the first input rack gear portion,
A braking control device for a vehicle configured to apply the assisting force from the assisting unit to the input unit. The vehicle brake control device according to claim 3,
The assisting portion has an assisting surface facing the forward direction,
The input unit has a pressure receiving surface facing in the backward direction,
A braking control device for a vehicle configured to apply the assisting force by surface contact between the assisting surface and the pressure-receiving surface. A braking control device for a vehicle according to claim 3 or 4,
A braking control device for a vehicle, comprising: an elastic body that applies a force in the backward direction to the assisting portion. The vehicle braking control device according to any one of claims 2 to 5,
The controller is
Determining whether the first electric motor is malfunctioning;
A vehicle braking control device configured to stop energization of the first electric motor when it is determined that the first electric motor is malfunctioning.