Vehicle braking control system

Abstract

To provide a brake control device which detects an abnormality of a connection part connecting an electric motor with a fluid pump.SOLUTION: A brake control device SC includes: a fluid pump QA which is driven through a connection part CA by an electric motor MA; a differential pressure regulating valve UA which is provided at a fluid passage HK connecting a discharge part Qo with a suction part Qi of the fluid pump QA and increases a pressure of a brake fluid discharged from the fluid pump QA to an output pressure to increase a wheel pressure of a wheel cylinder CW; and a controller ECU which drives the electric motor MA and the differential pressure regulating valve UA. The controller ECU determines whether or not the connection part CA is normal based on change of a state amount related to the electric motor MA when a valve opening of the differential pressure regulating valve UA is reduced in a state where the electric motor MA is driven.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004]

[0001] The present disclosure relates to a braking control device for a vehicle.

Background Art

[0002] In Patent Document 1, in order to determine whether the pump drive by electric motor control is being performed normally while detecting the wheel cylinder pressure, and to perform an abnormality determination of a sensor that detects the wheel cylinder pressure, when the brushless motor 33 is driven with a predetermined control amount, the brake fluid pressure is detected by the pressure sensors 16 to 20, and the brake fluid pressure at this time is compared with a previously calculated fluid pressure generated when the brushless motor 33 is driven with a predetermined control amount, whereby an abnormality determination of the pump unit 50 and the valve unit 51 is performed.

[0003] In Patent Document 1, an abnormality of the brushless motor 33 and the gear pump 34 is determined based on the comparison result between the pressure estimated value estimated from the control amount of the brushless motor and the pressure detected value detected by the pressure sensor. Specifically, the determination is performed by the following processing. (1) With the pressure increasing valves 25 to 28 closed, the brushless motor 33 is driven with a predetermined control amount, and the gear pump 34 sets the discharge pressure in the brake fluid pipe 43 to the pressure estimated value P01. (2) The discharge pressure (internal pressure) of the brake fluid pipe 43 is detected as the pressure detected value P1 by the pressure sensor 16. Then, it is compared with a value having a range above and below the pressure estimated value P01 that should have been generated by the brushless motor 33 and the gear pump 34. (3) When the condition of P01 - ΔP ≦ P1 ≦ P01 + ΔP is satisfied, it is determined that the brushless motor 33 and the gear pump 34 are fully performing their functions. When the condition of P01 - ΔP ≦ P1 ≦ P01 + ΔP is not satisfied, it is determined that an abnormality has occurred in the brushless motor 33 and the gear pump 34 and there is a possibility that they are not operating normally.

[0004] Incidentally, in a pump unit (also called an "electric pump"), the electric motor and the fluid pump are connected by a coupling device. The applicant has developed a coupling device for connecting the electric motor and the fluid pump that has a long lifespan and can transmit rotational force smoothly and quietly, as described in Patent Document 2. When the coupling device (also called a "connecting part") is applied to a braking control device, it is desirable that the braking control device detects any abnormalities in the connecting part. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-067335 [Patent Document 2] Japanese Patent Publication No. 2011-080530 [Overview of the project] [Problems that the invention aims to solve]

[0006] The object of the present invention is to provide a braking control device that can detect an abnormality in the connection between an electric motor and a fluid pump. [Means for solving the problem]

[0007] The vehicle braking control device (SC) according to the present invention comprises, via a connecting portion (CA), a fluid pump (QA) driven by an electric motor (MA), a differential pressure valve (UA) provided in a fluid passage (HK) connecting the discharge portion (Qo) and the suction portion (Qi) of the fluid pump (QA), which increases the wheel pressure (Pw) of the wheel cylinder (CW) by increasing the output pressure (Pq, Pu) of the braking fluid (BF) discharged by the fluid pump (QA), and a controller (ECU) that drives the electric motor (MA) and the differential pressure valve (UA).

[0008] In the vehicle braking control device (SC) according to the present invention, when the controller (ECU) is driving the electric motor (MA) and reduces the opening amount of the differential pressure valve (UA), it makes a determination of whether the coupling portion (CA) is normal or not based on the change in the state quantity (Ma) related to the electric motor (MA).

[0009] In the vehicle braking control device (SC) according to the present invention, when the controller (ECU) controls the rotational speed (Na) of the electric motor (MA) to a constant rotational speed (na) and reduces the opening amount of the differential pressure valve (UA), it determines whether the coupling part (CA) is normal or not based on the increase in the output equivalent value (Tm) corresponding to the output of the electric motor (MA). Specifically, the controller (ECU) determines that the coupling part (CA) is normal when the output equivalent value (Tm) becomes equal to or greater than a determination threshold (ix).

[0010] In the vehicle braking control device (SC) according to the present invention, the controller (ECU) reduces the opening amount of the differential pressure valve (UA) while supplying a constant current (im) to the electric motor (MA), and determines whether the coupling part (CA) is normal or not based on the decrease in the rotational speed (Na) of the electric motor (MA). Alternatively, the controller (ECU) determines whether the coupling part (CA) is normal or not based on the decrease in the rotational speed (Na) of the electric motor (MA) when the differential pressure valve (UA) is completely closed while the electric motor (MA) is being driven. Specifically, the controller (ECU) determines that the coupling part (CA) is normal when the rotational speed (Na) becomes less than or equal to the determination rotational speed (nx).

[0011] The vehicle braking control device (SC) according to the present invention further includes an inlet valve (VI) provided in the hydraulic pressure transmission path (HW) from the output pressure (Pq, Pu) to the wheel pressure (Pw), and a check valve (GA) that allows the discharge of braking fluid (BF) from the fluid pump (QA) in one direction but blocks it in the opposite direction. The controller (ECU) drives the inlet valve (VI). When the electric motor (MA) is driven in the forward rotation direction corresponding to the one direction with the inlet valve (VI) and the differential pressure valve (UA) closed, the controller (ECU) determines whether the coupling portion (CA) is normal or not based on the increase in the rotation angle (Ka) of the electric motor (MA). Specifically, the controller (ECU) determines that the coupling part (CA) is abnormal if the rotation angle (Ka) becomes greater than or equal to the determination angle (kx), based on the state before the electric motor (MA) is driven in the forward direction. Furthermore, the controller (ECU) may drive the electric motor (MA) in the reverse direction opposite to the forward direction before driving it in the forward direction.

[0012] The electric motor MA and the fluid pump QA are connected by a coupling part CA. When the electric motor MA is driven, the brake fluid BF is discharged from the fluid pump QA, and a flow KN (circulating flow) of brake fluid is generated in the fluid passage HK. A differential pressure valve UA is provided in the fluid passage HK, and if the opening amount of this valve is reduced, the brake fluid BF will not flow easily. Therefore, the load on the electric motor MA is large when the coupling part CA is normal and small when it is abnormal. With the above configuration, the suitability of the coupling part CA can be suitably determined based on changes in state variables related to the electric motor MA (for example, output equivalent value Tm, motor rotation speed Na, motor rotation angle Ka). [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram illustrating a first embodiment of the braking control device SC. [Figure 2] This is a block diagram illustrating the general procedure for determining the suitability of the connecting section CA. [Figure 3] It is a time-series diagram for explaining a first processing example of suitability determination. [Figure 4] It is a time-series diagram for explaining a second processing example of suitability determination. [Figure 5] It is a time-series diagram for explaining a third processing example of suitability determination. [Figure 6] It is a time-series diagram for explaining a fourth processing example of suitability determination. [Figure 7] It is a schematic diagram for explaining a second embodiment of the braking control device SC. [Figure 8] It is a schematic diagram for explaining a third embodiment of the braking control device SC.

Mode for Carrying Out the Invention

[0014] <Symbol of a component, etc., and subscript at the end of the symbol> In the following description, components, arithmetic processes, signals, characteristics, and values with the same symbol, such as "CW", have the same function. Also, in the circulation flow KN of the brake fluid BF, the side closer to the discharge part Qo of the fluid pump QA (the side away from the suction part Qi) is referred to as the "upstream side", and the side closer to the suction part Qi of the fluid pump QA (the side away from the discharge part Qo) is referred to as the "downstream side".

[0015] The cylinders CM, CS, the fluid pump QA, the differential pressure valve UA, the inlet valve VI, the wheel cylinder CW, the reservoirs RV, RA, etc. are connected by fluid paths. Here, the "fluid path" is a path for moving the brake fluid BF to transmit hydraulic pressure, and pipes, flow paths in the fluid unit HU, hoses, etc. correspond to it. In the following description, the master path HM, the wheel path HW, the reflux path HK, the reservoir path HR, the pressure reduction path HG, the servo path HV, etc. are fluid paths.

[0016] <First Embodiment of the Braking Control Device SC> Referring to the schematic diagram of FIG. 1, a first embodiment of the braking control device SC will be described. In FIG. 1, as a fluid unit HU constituting the braking control device SC, an actuator 5 (particularly, one set of wheel cylinders CW) of Japanese Unexamined Patent Application Publication No. 2018-069923 is schematically shown.

[0017] The braking control device SC according to the first embodiment is a general-purpose device for performing antilock brake control (also referred to as "ABS control"), skid prevention control (ESC: Electronic Stability Control), and traction control. Further, in the braking control device SC, in addition to these controls, automatic braking control is executed. The automatic braking control automatically decelerates the vehicle based on the required deceleration from the driving support device so as to avoid a collision with an obstacle or reduce the damage at the time of a collision.

[0018] A vehicle equipped with the braking control device SC is equipped with a braking operation member BP. The braking operation member (for example, a brake pedal) BP is a member that the driver operates to decelerate the vehicle. Further, the vehicle is equipped with a braking device (not shown). The braking device is composed of a brake caliper, a friction member (for example, a brake pad), and a rotating member (for example, a brake disk). A wheel cylinder CW is provided in the brake caliper. When a wheel pressure Pw is supplied from the braking control device SC to the wheel cylinder CW, the friction member is pressed against the rotating member fixed to the wheel WH. Thereby, a braking force is generated in the wheel WH. Specifically, a braking torque is applied to the wheel WH by the wheel pressure Pw, and the braking force of the wheel WH is generated by this braking torque.

[0019] The vehicle is equipped with various sensors to perform anti-lock brake control, anti-skid control, traction control, etc. Specifically, a wheel speed sensor VW is provided to detect the rotational speed Vw (wheel speed) of the wheels WH. In addition, a steering operation amount sensor SA is provided to detect the amount of operation Sa (steering operation amount, for example, steering angle) of the steering operation member (not shown). Furthermore, the vehicle (especially the body) is equipped with a yaw rate sensor YR to detect the yaw rate Yr, a longitudinal acceleration sensor GX to detect the longitudinal acceleration Gx, and a lateral acceleration sensor GY to detect the lateral acceleration Gy. These sensor signals are input to the controller ECU. The controller ECU then performs anti-lock brake control, anti-skid control, traction control, etc.

[0020] The vehicle is equipped with a master cylinder CM that generates master pressure Pm in response to the operation of a braking operating member BP. A master piston NM is inserted into the master cylinder CM, forming a hydraulic chamber Rm (referred to as the "master chamber"). The braking operating member BP is connected to the master piston NM, and the master piston NM moves in conjunction with the operation of the braking operating member BP. The master cylinder CM (particularly the master chamber Rm) and the wheel cylinder CW are connected by fluid passages such as a master passage HM, a return passage HK, and a wheel passage HW. As the master piston NM moves, the master pressure Pm is supplied from the master cylinder CM to the wheel cylinder CW as wheel pressure Pw. A braking control device SC is provided between the master cylinder CM and the wheel cylinder CW. The braking control device SC consists of a fluid unit HU and a controller ECU.

[0021] ≪Fluid Unit HU≫ The fluid unit HU of the braking control device SC adjusts (increases or decreases) the master pressure Pm individually for each wheel cylinder CW, and supplies it to the wheel cylinder CW as wheel pressure Pw. The fluid unit HU consists of an electric motor MA, a fluid pump QA, a differential pressure valve UA, a pressure regulating reservoir RA, an inlet valve VI, and an outlet valve VO.

[0022] The fluid pump QA is driven by an electric motor MA. The electric motor MA and the fluid pump QA are connected by a coupling part CA. The rotational power of the electric motor MA is transmitted to the fluid pump QA via the coupling part CA. Specifically, as shown in the outlet part XCA, a plane Mm (referred to as the "motor end plane") parallel to the motor rotation axis Jm is formed at the end of the shaft member JM of the electric motor MA. Also, a plane Mq (referred to as the "pump end plane") parallel to the pump rotation axis Jq is formed at the end of the shaft member JQ of the fluid pump QA. Power is transmitted by contact between the motor end plane Mm and the pump end plane Mq. Alternatively, a buffer member may be provided between the motor end plane Mm and the pump end plane Mq, and power transmission may occur through contact via this buffer member. For example, an elastic material such as rubber or resin may be used as the buffer member.

[0023] The connecting part CA is also called a "coupling" or "shaft coupling." The connecting part CA connects two shaft members (i.e., the motor shaft member JM and the pump shaft member JQ), and power is transmitted through it. For example, Oldham shaft couplings and flexible shaft couplings are used as the connecting part CA. Alternatively, the connecting part CA may be constructed by forming a protrusion at one end of the motor shaft member JM and the pump shaft member JQ, and a recess at the other end, with the protrusion being inserted (for example, press-fitted) into the recess.

[0024] The electric motor MA is equipped with a rotation angle sensor KA to detect the rotation angle Ka of the rotor (also called the "motor rotation angle"). The detected motor rotation angle Ka is input to the controller ECU. The controller ECU then calculates the motor rotation speed Na based on the motor rotation angle Ka. Specifically, the motor rotation speed Na is determined by differentiating the motor rotation angle Ka with respect to time.

[0025] In the fluid pump QA, the suction section Qi and the discharge section Qo are connected by a return channel HK (fluid passage). A normally open differential pressure valve UA is provided in the return channel HK. The differential pressure valve UA is a linear solenoid valve whose opening amount is continuously controlled based on the energized state (e.g., supply current Ia). A check valve GA is provided near the discharge section Qo in the return channel HK. Specifically, the check valve GA is positioned between the discharge section Qo of the fluid pump QA and the differential pressure valve UA in the return channel HK. The check valve GA allows flow in one direction but blocks flow in the other direction (opposite to the first direction). In other words, because the check valve GA restricts the flow of the bremfluid BF in the return channel HK to only one direction, the fluid pump QA can rotate in only one direction (i.e., the fluid pump QA cannot rotate in other directions). A pressure regulating reservoir RA is provided downstream of the fluid pump QA in the return channel HK. More specifically, the pressure regulating reservoir RA is positioned between the differential pressure valve UA and the suction section Qi of the fluid pump QA.

[0026] The return channel HK is connected to the master chamber Rm of the master cylinder CM via the master channel HM (fluid channel) at point Bm between the differential pressure valve UA and the pressure regulating reservoir RA. The return channel HK is also connected to the wheel cylinder CW via the wheel channel HW (fluid channel) at point Bw between the check valve GA and the differential pressure valve UA. A normally open inlet valve VI is provided in the wheel channel HW (corresponding to the "hydraulic pressure transmission path from output pressure Pq to wheel pressure Pw"). The wheel channel HW is connected to the suction section Qi of the fluid pump QA and the pressure regulating reservoir RA via the pressure reducing channel HG (fluid channel) at point Bg between the inlet valve VI and the wheel cylinder CW. In detail, point Bi between the pressure regulating reservoir RA and the suction section Qi of the return channel HK and point Bg of the wheel channel HW are connected by the pressure reducing channel HG. A normally closed outlet valve VO is provided in the pressure reducing channel HG. On / off type solenoid valves are used as the inlet valve VI and outlet valve VO. The inlet valve VI and outlet valve VO are provided for each wheel cylinder CW so that each wheel pressure Pw can be adjusted individually.

[0027] When the fluid unit HU is not driven (i.e., when power is not supplied to the differential pressure valve UA, electric motor MA, and inlet valve VI), the master pressure Pm generated in the master chamber Rm is supplied to the wheel cylinder CW via the hydraulic transmission paths, namely the master path HM, the return path HK, and the wheel path HW. When power is supplied to the electric motor MA and the electric motor MA is driven, a circulating flow KN of "Qo→GA→UA→RA→Qi" is generated in the return path HK, as indicated by the dashed arrow. When the differential pressure valve UA is not powered and is in a fully open state, in the return path HK, the upstream hydraulic pressure Pq (referred to as the "regulating pressure" and corresponding to the "output pressure") and the downstream hydraulic pressure Pm (master pressure) are equal with respect to the differential pressure valve UA (i.e., "Pq=Pm").

[0028] When the current Ia (supply current) supplied to the differential pressure valve UA is increased, the opening amount of the differential pressure valve UA is reduced. As a result, the circulating flow KN (the flow of braking fluid BF circulating in the return channel HK) is restricted by the differential pressure valve UA, and the flow of the circulating flow KN is obstructed. In other words, the flow path of the return channel HK is narrowed by the differential pressure valve UA, and the orifice effect of the differential pressure valve UA is exerted. As a result, the hydraulic pressure Pq (regulating pressure) on the upstream side of the differential pressure valve UA is increased from the hydraulic pressure Pm (master pressure) on the downstream side. In other words, in the circulating flow KN, a hydraulic pressure difference (differential pressure) is generated between the regulating pressure Pq and the master pressure Pm with respect to the differential pressure valve UA. This differential pressure is regulated by the supply current Ia to the differential pressure valve UA. The differential pressure generated by the differential pressure valve UA (resulting in the regulating pressure Pq) is used to perform automatic braking control, traction control, and anti-skid control.

[0029] In the braking control device SC, the inlet valve VI and outlet valve VO are controlled to individually decrease, increase, and maintain the wheel pressure Pw for each wheel cylinder CW. Individual adjustment of the wheel pressure Pw is used to perform anti-lock brake control, traction control, and anti-skid control. If power is not supplied to the inlet valve VI and outlet valve VO and their operation is stopped, the inlet valve VI is opened and the outlet valve VO is closed. In this state, the wheel pressure Pw is equal to the regulated pressure Pq. To decrease the wheel pressure Pw, the inlet valve VI is closed and the outlet valve VO is opened. The inflow of braking fluid BF into the wheel cylinder CW is prevented, and the braking fluid BF in the wheel cylinder CW flows out to the pressure regulating reservoir RA, thus decreasing the wheel pressure Pw. To increase the wheel pressure Pw, the inlet valve VI is opened and the outlet valve VO is closed. The outflow of brake fluid BF to the pressure regulating reservoir RA is prevented, and the regulating pressure Pq is supplied to the wheel cylinder CW, thereby increasing the wheel pressure Pw. However, the upper limit of the increase in wheel pressure Pw is up to the regulating pressure Pq. In order to maintain the wheel pressure Pw, both the inlet valve VI and the outlet valve VO are closed. Since the wheel cylinder CW is fluidically sealed, the wheel pressure Pw is maintained at a constant level.

[0030] ≪Controller ECU≫ The fluid unit HU is controlled by the controller ECU (also called the "electronic control unit"). The controller ECU consists of a microprocessor MP and a drive circuit DR.

[0031] The controller ECU (particularly the microprocessor MP) receives inputs for wheel speed Vw, steering input Sa, yaw rate Yr, lateral acceleration Gy, and motor rotation angle Ka. The controller ECU calculates the vehicle speed Vx based on the wheel speed Vw. Then, based on the signals of vehicle speed Vx, wheel speed Vw, steering input Sa, yaw rate Yr, and lateral acceleration Gy, automatic braking control, anti-lock braking control, traction control, and anti-skid control are executed. Specifically, the controller ECU drives the electric motor MA and various solenoid valves (UA, etc.) that constitute the fluid unit HU. The drive circuit DR of the controller ECU is configured with an H-bridge circuit using switching elements (e.g., MOS-FETs) to drive the electric motor MA based on the motor rotation angle Ka. The drive circuit DR is also equipped with switching elements to drive various solenoid valves (UA, etc.). Based on a control algorithm programmed into the microprocessor MP, the supply current Ia to the differential pressure valve UA (also called the "differential pressure valve current"), the supply current Ii to the inlet valve VI (also called the "inlet valve current"), the supply current Io to the outlet valve VO, and the supply current Im to the electric motor MA (also called the "motor current") are controlled. The drive circuit DR is equipped with a differential pressure valve current sensor IA for detecting the supply current Ia to the differential pressure valve UA, an inlet valve current sensor II (not shown) for detecting the supply current Ii to the inlet valve VI, and a motor current sensor IM for detecting the supply current Im to the electric motor MA.

[0032] Furthermore, the controller ECU (particularly the microprocessor MP) includes a suitability determination block BH to determine whether the coupling section CA is normal or abnormal. This determination is referred to as "suitability determination." The suitability determination block BH (also simply called the "determination block") is programmed with an algorithm for suitability determination. Suitability determination is performed when the vehicle is stopped. For example, suitability determination is performed as an initial check of the braking control device SC when the ignition switch is turned on. Alternatively, it may be performed when the vehicle door is opened for the driver to get in (for example, when the courtesy switch is turned on). Furthermore, suitability determination may be performed before the execution of automatic driving (for example, automatic parking control such as remote parking control). Here, "remote parking control" is a function that automatically parks the vehicle via remote control using a smartphone or the like.

[0033] The pass / fail judgment block BH receives a signal of the state variable Ma related to the electric motor MA. The "state variable Ma related to the electric motor MA" is also referred to as the "motor state variable". For example, the motor rotation angle Ka detected by the motor rotation angle sensor KA is input to the pass / fail judgment block BH as the motor state variable Ma. In addition, the supply current Im (motor current) detected by the motor current sensor IM is input to the pass / fail judgment block BH as the motor state variable Ma. Furthermore, the motor rotation speed Na is input to the pass / fail judgment block BH as the motor state variable Ma.

[0034] In the suitability determination block BH, when the electric motor MA is in steady-state operation and the opening amount of the differential pressure valve UA decreases, a suitability determination of "whether the coupling part CA is normal or not" is made based on the change (increase or decrease) in the motor state quantity Ma. When the electric motor MA starts to operate (i.e., at startup), an inrush current (also called "starting current") flows through the electric motor MA. After that, the motor current Im becomes approximately constant. "Steady-state operation" means that the electric motor MA is driven while maintaining a constant state (for example, a constant state of motor rotation speed Na and motor current Im) after the occurrence of the inrush current. Furthermore, "decrease in the opening amount of the differential pressure valve UA" includes the differential pressure valve UA being completely closed.

[0035] In the suitability determination, components of the fluid unit HU, such as the electric motor MA, differential pressure valve UA, and inlet valve VI, are driven. The series of drives of the electric motor MA and other components in the suitability determination are referred to as "determination mode drive." In other words, in the suitability determination block BH, the suitability (whether it is normal or not) of the coupling section CA is determined from the change in the motor state quantity Ma when the determination mode drive is executed. The determination mode drive is executed when the vehicle is stopped (i.e., when "Vx=0"). In addition, the execution condition may include the state in which the braking operating member BP is not operated (i.e., when "Ba=0").

[0036] When the suitability judgment block BH detects an abnormality in the coupling section CA, the driver is notified of the abnormality by the notification device WG. For example, a notification signal Wg is output from the suitability judgment block BH of the controller ECU to the notification device WG. As a result, the notification device WG informs the driver of the abnormal condition of the coupling section CA through sound, light, etc.

[0037] <Overview of the determination of suitability of connecting section CA> Referring to the block diagram in Figure 2, the suitability determination performed by the suitability determination block BH will be outlined. The processing of the suitability determination block BH is programmed into the controller ECU. In the suitability determination, a load is applied to the electric motor MA, which is the power source that generates the circulating flow KN, by narrowing (or closing) the opening amount of the differential pressure valve UA, etc. The suitability of the coupling section CA is determined based on the change in the state quantity Ma related to the electric motor MA at this time. The suitability determination block BH consists of a determination mode drive block MD, a signal acquisition block SG, and a determination processing block HN.

[0038] In the judgment mode drive block MD, the electric motor MA, differential pressure valve UA, etc., are driven based on a preset pattern. In other words, the judgment mode drive block MD issues instructions to the drive circuit DR. For example, judgment mode driving is performed when the vehicle is stationary and not braking (i.e., when "Vx=0, Ba=0").

[0039] The signal acquisition block SG acquires signals of motor state variables Ma (state variables related to the electric motor MA) in the determination mode drive. Specifically, the motor state variables Ma include motor current Im, motor rotation angle Ka, motor rotation speed Na, etc. The motor current Im is detected by the motor current sensor IM provided in the drive circuit DR. The motor rotation angle Ka is detected by the motor rotation angle sensor KA provided in the electric motor MA. The motor rotation speed Na is determined by differentiating the motor rotation angle Ka with respect to time.

[0040] In the judgment processing block HN, a determination is made as to whether the coupling part CA is normal or not based on the change (increase or decrease) in the motor state quantity Ma during the judgment mode drive. As will be described in detail later, the normal state of the coupling part CA is determined based on whether the judgment conditions are satisfied within the judgment period. If the normal state is not determined within the judgment period, the abnormal state of the coupling part CA is determined at the end of the judgment period.

[0041] The electric motor MA and the fluid pump QA are connected via a coupling section CA. When the electric motor MA is driven, the bremflue BF is discharged from the fluid pump QA, and a circulating flow KN is generated in the return channel HK. A differential pressure valve UA is provided in the return channel HK. When the opening amount of the differential pressure valve UA is reduced (or the differential pressure valve UA is completely closed), the circulating flow KN becomes difficult to flow. Therefore, if the coupling section CA is normal, the load on the electric motor MA increases. Conversely, if there is a problem with the coupling section CA, the increase in the load on the electric motor MA is small (or almost non-existent). In other words, the load on the electric motor MA when the flow path is narrowed by the differential pressure valve UA is large when the coupling section CA is normal and small when it is abnormal. In the judgment processing block HN, based on this event, the suitability of the coupling section CA is determined based on the change in the state quantity Ma related to the electric motor MA. The overview of suitability determination has been explained above. Next, specific processing examples of suitability determination (processing examples 1 to 3) will be explained.

[0042] ≪Example of the first processing step for determining suitability≫ Details of the first example of processing related to the suitability determination will be explained below. In the first processing example, the motor state quantity Ma used for determining suitability is "the state quantity (state variable) from the motor current Im to the output as torque of the electric motor MA." This state quantity is a state quantity related to the torque output of the electric motor MA and is referred to as "the output equivalent value Tm (the value equivalent to the torque output of the electric motor MA)." For example, the output equivalent value Tm is calculated based on the motor current Im (the value detected by the motor current sensor IM). Alternatively, the motor current Im itself may be used as the output equivalent value Tm. In a configuration where a torque sensor for detecting the output of the electric motor MA is provided, the motor torque detected by the sensor may be used as the output equivalent value Tm.

[0043] In the first processing example, the judgment period is set as "from the start of power supply to differential pressure valve UA until the judgment time th has elapsed." The judgment time th is a predetermined value (constant). In other words, when the start of power supply to differential pressure valve UA is taken as "0 (start point)," the judgment period is from "T=0 (start point)" to "T=th (end point)" during the elapsed time T. The judgment period in the first processing example is also referred to as the "output judgment period" to distinguish it from other judgment periods.

[0044] In the first processing example, the judgment condition is "the state in which the output equivalent value Tm is equal to or greater than the judgment threshold ix is ​​maintained for a duration of tj." The judgment threshold ix and the duration tj are predetermined values ​​(constants). The duration tj is set to eliminate the influence of noise, etc. The judgment condition for the first processing example is also referred to as the "first judgment condition" to distinguish it from other judgment conditions. When the first judgment condition is met, the normal state of the coupling section CA is determined. In other words, the first judgment condition is the condition for determining the normal state of the coupling section CA.

[0045] In the first example of the determination mode drive, first, the electric motor MA is driven in the forward direction so that its rotational speed Na becomes a constant rotational speed na. Specifically, the target rotational speed Nt of the electric motor MA is set to a constant rotational speed na (a predetermined value). Then, the torque output of the electric motor MA is controlled so that the motor rotational speed Na matches the target rotational speed Nt (=na). Since the output of the electric motor MA is correlated with the motor current Im, the current Im supplied to the electric motor MA is adjusted by rotational speed feedback control. At this time, the differential pressure valve UA and the inlet valve VI are not energized, so they are in a fully open state. Therefore, as a motor current Im of value ia is supplied to the electric motor MA, the motor rotational speed Na continues to rotate at a constant rotational speed na (i.e., a steady-state drive state of "Im=ia, Na=na (constant rotational speed)"). Next, in the steady state in which the electric motor MA is driven at a constant rotational speed na, power is supplied to the differential pressure valve UA and the inlet valve VI. As a result, the amount the differential pressure valve UA opens is reduced, and the inlet valve VI is closed.

[0046] The pass / fail determination is executed based on the change (especially increase) of the output equivalent value Tm during the determination period. Specifically, within the determination period, if the state of "Tm ≧ ix" continues for a duration tj and the first determination condition is satisfied, it is determined that the connecting part CA is normal. On the other hand, within the output determination period, if the state of "Tm < ix" continues, or "Tm ≧ ix" is achieved but its state does not continue for the duration tj and the first determination condition is not satisfied, it is determined that the connecting part CA is abnormal. When the abnormality of the connecting part CA is determined, a notification signal Wg is output to the notification device WG. The notification device WG notifies the driver of the abnormal state of the connecting part CA.

[0047] The determination mode drive ends at the end of the determination period. When the determination mode drive ends, the power supply to the electric motor MA, the differential pressure valve UA, etc. is stopped. Note that the determination mode drive may end even when the determination condition is satisfied.

[0048] In the determination mode drive, since the inlet valve VI is fully closed, the brake fluid BF does not move toward the wheel cylinder CW. Also, due to the power supply to the differential pressure valve UA, the opening amount of the differential pressure valve UA is decreased, so when the brake fluid BF passes through the differential pressure valve UA, a load is generated on the electric motor MA. The output equivalent value Tm is rotation speed feedback controlled so that the motor rotation speed Na is maintained at a constant rotation speed na. Therefore, when the connecting part CA is normal, the load on the electric motor MA increases and the output equivalent value Tm increases. Thus, when the determination condition is satisfied, the normality of the connecting part CA is determined. On the other hand, when there is an abnormality in the connecting part CA, power is not transmitted from the electric motor MA to the fluid pump QA, and the brake fluid BF is not discharged from the fluid pump QA or the discharge amount is small. When there is an abnormality in the connecting part CA, the output equivalent value Tm does not increase significantly. Therefore, when the first determination condition is satisfied, the normality of the connecting part CA is determined, but when the first determination condition is not satisfied, the abnormality of the connecting part CA is determined.

[0049] In the first processing example, the inlet valve VI does not need to be closed. In this case, the braking fluid BF is moved to the wheel cylinder CW, but since the components of the braking device (wheel cylinder CW, brake caliper, friction member, etc.) have sufficient rigidity, a load is generated on the electric motor MA. In the first processing example, closing the inlet valve VI by energizing it is not a necessary condition for the determination mode drive.

[0050] <Operation of the first processing example> Referring to the time-series diagram in Figure 3 (a diagram showing the transitions of various state variables as time T progresses), the operation of the first processing example related to suitability determination will be explained. There are four possible configurations for the determination mode drive of the first processing example, depending on the combination of the power supply method for the differential pressure valve UA and the inlet valve VI. In the first processing example, regardless of which of these is adopted, the suitability of the coupling section CA is determined according to the output determination period and the first determination condition described above. (1) An embodiment in which the inlet valve VI is fully closed and power is supplied to the differential pressure valve UA in a stepwise manner (referred to as "Embodiment 1a"). (2) A mode in which power is gradually supplied to the differential pressure valve UA while the inlet valve VI remains open (referred to as "mode 1b"). (3) The inlet valve VI is fully closed and power is supplied to the differential pressure valve UA gradually (referred to as "Aspect 1c"). (4) A mode in which power is supplied to the differential pressure valve UA in a stepwise manner while the inlet valve VI remains open (referred to as "mode 1d").

[0051] ≪Operation of [Aspect 1a]≫ The above [Aspect 1a] will be explained with reference to Figure 3(a). In this example of operation, it is assumed that if the coupling part CA malfunctions, it will break and the electric motor MA will spin freely. When the electric motor MA is started, a starting current (inrush current) is generated, and a large current flows temporarily as the motor current Im, but this is omitted in the following diagrams (Figures 3 to 6).

[0052] At time t1, the determination mode drive is initiated. After an inrush current occurs, the electric motor MA is driven steadily in the forward direction. That is, the current Im supplied to the electric motor MA is increased so that the rotational speed Na of the electric motor MA matches the target rotational speed Nt (=na). Consequently, the output equivalent value Tm increases. After the motor rotational speed Na matches the target rotational speed na, the motor current Im is maintained at a constant value ia, and the output equivalent value Tm remains constant.

[0053] At time t2, when the electric motor MA is in steady-state operation, the inlet valve VI and differential pressure valve UA are driven in determination mode. The supply current Ii (inlet valve current) to the inlet valve VI is increased, and the inlet valve VI is completely closed. Also, the supply current Ia (differential pressure valve current) to the differential pressure valve UA is increased, and the opening amount of the differential pressure valve UA is decreased. Note that the differential pressure valve current Ia is less than the closing current ic, so the differential pressure valve UA is not completely closed. The closing current ic is the current value required to completely close the differential pressure valve UA, and is a predetermined value (constant) set in advance. At time t2, the counting of time T related to the determination time th begins. Note that in the diagram, the output determination period is the period (interval) from time t2 to time t5.

[0054] Referring to the characteristic curve ZSa shown by the solid line, the case where the coupling CA is normal will be explained. When the coupling CA is normal, the brake fluid BF becomes difficult to flow in the circulating flow KN due to the closing of the inlet valve VI and the decrease in the opening amount of the differential pressure valve UA. As a result, the load on the electric motor MA increases. The output equivalent value Tm is increased by rotational speed feedback control so that the motor rotational speed Na matches the target rotational speed na. Therefore, at time t3, immediately after time t2, the output equivalent value Tm reaches the judgment threshold ix. From time t3, the time T related to the duration tj is counted. At time t4, the first judgment condition is met, and in the suitability judgment, it is determined that the coupling CA is normal.

[0055] Next, referring to the characteristic curve ZIa shown by the dashed line, we will explain the case where the coupling section CA is abnormal. When the coupling section CA is abnormal, the load on the electric motor MA does not increase, or only increases slightly, so the output equivalent value Tm does not increase. Therefore, the output equivalent value Tm remains below the judgment threshold ix, and the first judgment condition is not met within the output judgment period. For this reason, at time t5, it is determined that the coupling section CA is abnormal.

[0056] At the end of the judgment period t5, the judgment mode drive is terminated, and power is stopped to the electric motor MA, inlet valve VI, and differential pressure valve UA. Alternatively, the judgment mode drive may be terminated at t4 when the first judgment condition is met.

[0057] ≪Operation of [Aspect 1b]≫ Refer to Figure 3(b) to explain [Aspect 1b] above. The differences from [Aspect 1a] are that in the determination mode drive, "the inlet valve VI remains open" and "power is supplied to the differential pressure valve UA gradually". The differences will be explained below in detail.

[0058] At time t6, the determination mode drive is initiated, and the electric motor MA is driven in the forward direction. That is, the current Im supplied to the electric motor MA is increased so that the rotational speed Na of the electric motor MA becomes the target rotational speed Nt (=na). After that, the electric motor MA is driven in a steady state where "Na=na".

[0059] At time t7, when the electric motor MA is in steady-state operation, the differential pressure valve UA is started to operate. In [Aspect 1b], no power is supplied to the inlet valve VI, and the inlet valve VI remains open. From time t7, the differential pressure valve current Ia is gradually increased at a predetermined time gradient da (referred to as the "increase gradient"). When the differential pressure valve current Ia reaches a predetermined current ie (also referred to as the "differential pressure valve predetermined current"), the differential pressure valve current Ia is then maintained at the predetermined current ie. The increase gradient da (the amount of change in the differential pressure valve current Ia with respect to time) and the predetermined current ie (differential pressure valve predetermined current) are predetermined values ​​(constants) set in advance. From time t7, the counting of time T related to the determination time th begins. In [Aspect 1b], the output determination period is from time t7 (start point) to time t10 (end point).

[0060] When the coupling section CA is functioning normally, from time t7 onward, the load on the electric motor MA increases as the opening amount of the differential pressure valve UA decreases. At time t8, the condition that the output equivalent value Tm is greater than or equal to the judgment threshold ix is ​​satisfied for the first time. Then, at time t9, the state of "Tm≧ix" continues for a duration tj (see the characteristic line ZSg shown in solid). As a result, at time t9, the first judgment condition is met, and it is determined that the coupling section CA is functioning normally. When the coupling section CA is abnormal, the load on the electric motor MA does not increase, so the output equivalent value Tm does not increase (see the characteristic line ZIg shown in dashed). The state in which the output equivalent value Tm remains below the judgment threshold ix continues, and the first judgment condition is not met, so at time t10, it is determined that the coupling section CA is abnormal. In [Aspect 1b] as well, the judgment mode drive is terminated at the end of the judgment period t10. When the judgment mode drive is terminated, power is cut off to the electric motor MA and the differential pressure valve UA. The judgment mode drive may also be terminated at time t9 when the first judgment condition is met.

[0061] ≪Example of the second processing method for determining suitability≫ The details of the second example of processing related to the determination of suitability will be explained below. In the second processing example, the motor speed Na is used as the motor state quantity Ma for determining suitability. For example, the motor speed Na is calculated based on the detection result of the motor rotation angle sensor KA (i.e., the motor rotation angle Ka). The determination period in the second processing example is the same as in the first processing example, "from the start of power supply to the differential pressure valve UA until the determination time th (a predetermined value set in advance) has elapsed." The determination period for the second processing example is also referred to as the "rotation speed determination period" to distinguish it from other determination periods.

[0062] In the second processing example, the judgment condition is set as "the state in which the motor rotation speed Na is less than or equal to the judgment rotation speed nx continues for a duration tj." The judgment rotation speed nx and the duration tj are predetermined values ​​(constants). The duration tj is provided to eliminate the influence of noise, etc. The judgment condition in the second processing example is also referred to as the "second judgment condition" to distinguish it from other judgment conditions. When the second judgment condition is met, the normal state of the coupling part CA is determined. In other words, the second judgment condition is the condition for determining the normal state of the coupling part CA.

[0063] The second processing example describes the determination mode drive. In the first processing example, the electric motor MA was driven by rotational speed feedback control, but in the second processing example, rotational speed feedback control is not performed, and a constant motor current Im (value im) is supplied to the electric motor MA. In the determination mode drive, first, a constant current im is supplied to the electric motor MA. The constant current im is a predetermined value (constant) set in advance. At this time, power supply to the differential pressure valve UA and the inlet valve VI is stopped, and they are in a fully open state. The rotational speed Na of the electric motor MA becomes a constant steady state at value nm. Then, in this state, power is supplied to the differential pressure valve UA and the inlet valve VI. As a result, the opening amount of the differential pressure valve UA is reduced, and the inlet valve VI is completely closed.

[0064] The suitability determination is performed based on the change in motor rotation speed Na during the determination period. Specifically, if the state "Na ≤ nx" continues for a duration tj during the rotation speed determination period, and the second determination condition is satisfied, the coupling section CA is determined to be normal. Conversely, if the state "Na > nx" continues during the rotation speed determination period, or if "Na > nx" is achieved but does not continue for a duration tj, and the second determination condition is not satisfied, the coupling section CA is determined to be abnormal. If an abnormality in the coupling section CA is determined, a notification signal Wg is output to the notification device WG. The notification device WG notifies the driver of the abnormal state of the coupling section CA.

[0065] As described above, if the coupling section CA is functioning correctly, a decrease in the opening amount of the differential pressure valve UA will create a load on the electric motor MA. Since the supplied motor current Im is a constant value im, the motor speed Na should decrease as the load increases. If there is an abnormality in the coupling section CA, the motor speed Na will not decrease significantly in the judgment mode drive. Therefore, in the judgment mode drive, if the second judgment condition is satisfied, the coupling section CA is determined to be functioning correctly; however, if the second judgment condition is not satisfied, the coupling section CA is determined to be abnormal.

[0066] In the second processing example, as in the first processing example, the inlet valve VI does not need to be closed. This is because the rigidity of the braking device (CW, brake caliper, friction member, etc.) generates a load on the electric motor MA. Therefore, in the second processing example as well, closing the inlet valve VI by energizing it is not a necessary condition for judgment mode driving.

[0067] <Operation of the second processing example> Referring to the time-series diagram in Figure 4 (a diagram showing the transitions of various state variables as time T progresses), the operation of the second processing example related to suitability determination will be explained. There are four possible configurations for the determination mode drive of the second processing example, depending on the combination of the power supply method for the differential pressure valve UA and the inlet valve VI. In the second processing example, regardless of which of these is adopted, the suitability of the coupling part CA is determined according to the rotation speed determination period and the second determination conditions described above. (1) An embodiment in which the inlet valve VI is fully closed and power is supplied to the differential pressure valve UA in a stepwise manner (referred to as "embodiment 2a"). (2) A mode in which power is gradually supplied to the differential pressure valve UA while the inlet valve VI remains open (referred to as "mode 2b"). (3) The inlet valve VI is fully closed and power is supplied to the differential pressure valve UA gradually (referred to as "Aspect 2c"). (4) A mode in which power is supplied to the differential pressure valve UA in a stepwise manner while the inlet valve VI remains open (referred to as "mode 2d").

[0068] ≪Operation of [Aspect 2a]≫ The above [Aspect 2a] will be explained with reference to Figure 4(a). In this example of operation, it is assumed that if the coupling part CA malfunctions, it will break and the electric motor MA will spin freely. As mentioned above, the starting current when the electric motor MA is started is not shown.

[0069] At time point v1, the determination mode drive is initiated. After the starting current is generated, the electric motor MA is driven in a steady state in the forward direction. In other words, a predetermined current im (a constant value) is supplied to the electric motor MA. As a result, the motor speed Na is driven steadily at a constant speed nm corresponding to the predetermined current im.

[0070] When the electric motor MA is in steady-state drive at time point v2, the inlet valve VI and the differential pressure valve UA are driven. At time point v2, the inlet valve VI is fully closed and the opening degree of the differential pressure valve UA is decreased. Here, since "Ia < ic", the differential pressure valve UA is not fully closed. At time point v2, the counting of the time T related to the determination time th is started. In [Aspect 2a], the rotation speed determination period is between time point v2 and time point v5

[0071] When the connecting part CA is normal, due to the closing of the inlet valve VI and the decrease in the opening degree of the differential pressure valve UA, the load of the electric motor MA increases. Since the motor current Im is constant, the motor rotation speed Na decreases from the value nm (refer to the characteristic line ZSb shown by the solid line). Therefore, at time point v3 immediately after the start of power supply to the differential pressure valve UA, the motor rotation speed Na reaches the determination rotation speed nx. At time point v3, the counting of the time T related to the continuous time tj is started. At time point v4, since the second determination condition is satisfied, it is determined that the connecting part CA is normal.

[0072] When the connecting part CA is abnormal, the load of the electric motor MA either does not increase or only increases slightly. Therefore, during the determination period, the motor rotation speed Na hardly decreases (refer to the characteristic line ZIb shown by the dashed line). Since the state where the motor rotation speed Na is greater than the determination rotation speed nx continues and the second determination condition is not satisfied, at time point v5, it is determined that the connecting part CA is abnormal.

[0073] In the second processing example as well, similar to the first processing example, at the end time point v5 of the determination period, the determination mode drive is ended and the power supply to the electric motor MA, the inlet valve VI, and the differential pressure valve UA is stopped. In addition, when the second determination condition is satisfied, the determination mode drive may be ended at that time point v4.

[0074] ≪Operation of [Aspect 2b]≫ Refer to Figure 4(b) to explain [Aspect 2b] above. The differences from [Aspect 2a] are that in the determination mode drive, "the inlet valve VI remains open" and "power is supplied to the differential pressure valve UA gradually". The differences will be explained below in detail.

[0075] At time v6, the determination mode drive is started, and the electric motor MA is driven in the forward direction. Specifically, the electric motor MA is supplied with "Im=im" and is driven steadily with "Na=nm". At time v7, the differential pressure valve UA is driven in determination mode. In [Aspect 2b], no power is supplied to the inlet valve VI, and the inlet valve VI remains open. From time v7, the differential pressure valve current Ia is gradually increased with an increasing gradient da. When the differential pressure valve current Ia reaches a predetermined current ie, the differential pressure valve current Ia is then maintained at the predetermined current ie. As described above, the increasing gradient da (the amount of change in the differential pressure valve current Ia with respect to time) and the predetermined current ie are predetermined values ​​(constants) set in advance. At time v7, the counting of time T related to the determination time th begins. In [Aspect 2b], the rotational speed determination period is from time v7 to time v10.

[0076] When the coupling section CA is functioning normally, from time v7 onward, the load on the electric motor MA increases as the opening amount of the differential pressure valve UA decreases, causing the motor speed Na to decrease. At time v8, the condition that the motor speed Na is less than or equal to the judgment speed nx is satisfied for the first time. Then, at time v9, the state of "Na ≤ nx" continues for a duration tj (see the characteristic line ZSh shown in solid). As a result, at time v9, the second judgment condition is met, and it is determined that the coupling section CA is functioning normally. When the coupling section CA is abnormal, the load on the electric motor MA does not increase, so the motor speed Na does not decrease (see the characteristic line ZIh shown in dashed). The state in which the motor speed Na remains greater than the judgment speed nx continues, and the second judgment condition is not met, so at time v10, it is determined that the coupling section CA is abnormal. In [Aspect 2b] as well, the judgment mode drive is terminated at time v10, the end of the judgment period. Furthermore, if the second determination condition is met, the process may terminate at point v9.

[0077] ≪Example of the third processing step for determining suitability≫ The details of the third processing example related to the determination of suitability will be explained below. In the third processing example, as in the second processing example, the motor speed Na is used as the motor state quantity Ma for determining suitability. The determination period for the third processing example is the same as in the first and second processing examples, "from the start of power supply to the differential pressure valve UA until the determination time th (a predetermined value set in advance)." The determination period for the third processing example is also referred to as the "rotation speed determination period," as in the second processing example.

[0078] In the third processing example, similar to the second processing example, the determination condition is "the state in which the motor rotation speed Na is less than or equal to the determination rotation speed nx continues for a duration tj." The determination rotation speed nx and the duration tj are predetermined values ​​(constants). For example, the determination rotation speed nx can be set to "0 (stopped state of electric motor MA)." The duration tj is provided to eliminate the influence of noise, etc. The determination condition for the third processing example is also referred to as the "third determination condition" to distinguish it from other determination conditions. When the third determination condition is met, the normal state of the coupling part CA is determined. In other words, the third determination condition is the condition for determining the normal state of the coupling part CA.

[0079] In the third processing example's determination mode drive, the electric motor MA is driven first. In the third determination example, similar to the first determination example, the electric motor MA is controlled by rotational speed feedback control so that the motor rotational speed Na becomes a constant rotational speed na (a predetermined value set in advance). Alternatively, similar to the second determination example, a constant current im (a predetermined value set in advance) may be supplied as the motor current Im to drive the electric motor MA. While the electric motor MA is being driven in a steady state, both the differential pressure valve UA and the inlet valve VI are completely closed. In other words, in the first and second processing examples, the differential pressure valve UA was open, although its opening amount was reduced. In contrast, in the third processing example, the differential pressure valve UA is completely closed, similar to the inlet valve VI.

[0080] The suitability determination for the third processing example is performed based on the change in motor rotation speed Na during the determination period, similar to the second processing example. Specifically, if the third determination condition is satisfied within the rotation speed determination period, the coupling part CA is determined to be normal. Conversely, if the third determination condition is not satisfied, the coupling part CA is determined to be abnormal.

[0081] When the differential pressure valve UA and the inlet valve VI are completely closed, the discharge port Qo of the fluid pump QA is fluidically sealed. Therefore, if the coupling CA is functioning correctly, the electric motor MA and the fluid pump QA will not rotate, or will rotate only slightly due to the rigidity of the fluid path, play in the coupling CA, etc. For example, if the rotational speed Na of the electric motor MA does not occur at all (i.e., "Na=0"), the coupling CA is determined to be in a normal state. On the other hand, if "Na>nx(=0)" and the rotational speed Na of the electric motor MA is generated (i.e., "Na≠0"), the electric motor MA is spinning freely, and the coupling CA is determined to be in an abnormal state. When an abnormality in the coupling CA is detected, a notification signal Wg is output to the notification device WG, and the operator is notified.

[0082] In the third processing example, as in the first and second processing examples, the inlet valve VI does not need to be closed. This is because the rigidity of the braking device (wheel cylinder CW, brake caliper, friction member, etc.) generates a load on the electric motor MA. Therefore, even in the third processing example, closing the inlet valve VI by energizing it is not a necessary condition for the determination mode drive.

[0083] <Operation of the third processing example> Referring to the time-series diagram in Figure 5, the operation of the third processing example related to suitability determination will be explained. There are four possible configurations for the determination mode drive of the third processing example, depending on the combination of power supply methods for the differential pressure valve UA and the inlet valve VI. In the third processing example, regardless of which of these is adopted, the suitability of the coupling part CA is determined according to the rotation speed determination period and the third determination conditions described above. (1) An embodiment in which the inlet valve VI is fully closed and power is supplied to the differential pressure valve UA in a stepwise manner (referred to as "embodiment 3a"). (2) A mode in which power is gradually supplied to the differential pressure valve UA while the inlet valve VI remains open (referred to as "mode 3b"). (3) The inlet valve VI is fully closed and power is supplied to the differential pressure valve UA gradually (referred to as "Aspect 3c"). (4) A mode in which power is supplied to the differential pressure valve UA in a stepwise manner while the inlet valve VI remains open (referred to as "mode 3d").

[0084] ≪[Aspect 3a] Operation≫ [Aspect 3a] described above will be explained with reference to Figure 5(a). At time point s1, the determination mode drive is initiated, and the electric motor MA is driven in the forward direction. From time point s1, the supply current Im to the electric motor MA is increased, and the motor speed Na increases. Subsequently, the motor speed Na is driven in a steady state at a constant rotational speed na.

[0085] At time s2, the inlet valve VI and the differential pressure valve UA are driven in determination mode. At time s2, the inlet valve VI and the differential pressure valve UA are completely closed. The closing of the differential pressure valve UA is achieved by supplying a predetermined current ig to the differential pressure valve UA. The predetermined current ig is a value greater than the closing current ic and is a predetermined value (constant) set in advance. At time s2, the counting of time T related to the determination time th begins. In [Aspect 3a], the rotational speed determination period is from time s2 to time s5.

[0086] If the coupling section CA is functioning correctly, the load on the electric motor MA increases sharply due to the fully closed state of the inlet valve VI and differential pressure valve UA. As a result, the motor speed Na decreases sharply so that the rotation of the electric motor MA stops (see the characteristic curve ZSc shown in solid). At time s3, immediately after the start of power supply to the differential pressure valve UA, the motor speed Na decreases to the judgment speed nx. At time s4, the third judgment condition is met, and it is determined that the coupling section CA is functioning correctly. If the coupling section CA is abnormal (for example, if the coupling section CA is damaged), the load on the electric motor MA does not increase significantly even if the inlet valve VI and differential pressure valve UA are fully closed. Therefore, in judgment mode drive, the motor speed Na does not decrease (see the characteristic curve ZIc shown in dashed). The motor speed Na remains greater than the judgment speed nx, and the third judgment condition is not met, so at time s5, it is determined that the coupling section CA is abnormal. In the third processing example, as in the first and second processing examples, the determination mode is terminated at the end of the determination period s5. Alternatively, the determination mode may be terminated at the time s4 when the third determination condition is met.

[0087] ≪Operation of [Aspect 3b]≫ Refer to Figure 5(b) to explain [Aspect 3b] above. The differences from [Aspect 3a] are that, in the determination mode drive, "power is supplied to the differential pressure valve UA gradually" and "the inlet valve VI is not closed". The differences will be explained below in detail.

[0088] At time s6, the determination mode drive is started, and the electric motor MA is driven in the forward direction. Specifically, the electric motor MA is driven in a steady state where "Na=na". At time s7, the differential pressure valve UA is driven in determination mode. In [Aspect 2b], no power is supplied to the inlet valve VI, and the inlet valve VI remains open. From time s7, the differential pressure valve current Ia is gradually increased at an increasing gradient da. When the differential pressure valve current Ia reaches a predetermined current ig, the differential pressure valve current Ia is then maintained at the predetermined current ig. As described above, the increasing gradient da (the amount of change in the differential pressure valve current Ia with respect to time) and the predetermined current ig are predetermined values ​​(constants) set in advance. At time s7, the counting of time T related to the determination time th begins. In [Aspect 3b], the rotational speed determination period is from time s7 to time s10.

[0089] When the connection CA is functioning normally, the differential pressure valve UA is fully closed when the differential pressure valve current Ia exceeds the closing current ic. This increases the load on the electric motor MA and decreases the motor speed Na. At time s8, the condition that the motor speed Na is less than or equal to the judgment speed nx is satisfied for the first time. Then, at time s9, the state of "Na ≤ nx" continues for a duration tj (see the characteristic curve ZSi shown in solid line). As a result, the third judgment condition is met at time s9, and it is determined that the connection CA is functioning normally. When the connection CA is malfunctioning, even if the differential pressure valve UA is closed, the load on the electric motor MA does not increase, and therefore the motor speed Na does not decrease (see the characteristic curve ZIi shown in dashed line). The state in which the motor speed Na remains greater than the judgment speed nx continues, and the third judgment condition is not met, so at time s10, it is determined that the connection CA is malfunctioning. In [Aspect 3b] as well, the determination mode is terminated at the end of the determination period s10. Alternatively, the determination mode may be terminated at the time s9 when the third determination condition is satisfied.

[0090] ≪Example of the fourth processing step for determining suitability≫ The details of the fourth processing example related to the determination of suitability will be explained below. In the first to third judgment examples, when the electric motor MA is steadily driven in the forward direction and the opening amount of the differential pressure valve UA decreases, a suitability judgment was performed based on the change in the motor state quantity Ma. Conversely, in the fourth processing example, the electric motor MA is driven in the forward direction after power is supplied to the differential pressure valve UA and the inlet valve VI. At this time, both the differential pressure valve UA and the inlet valve VI are set to a completely closed state.

[0091] In the first to third processing examples, the normal state of the coupling part CA was determined based on the change in the motor state variable Ma. If the normal state could not be determined within the determination period, the abnormal state of the coupling part CA was determined. Conversely, in the fourth processing example, the abnormal state of the coupling part CA was determined based on the change in the motor state variable Ma. If the abnormal state could not be determined within the determination period, the normal state of the coupling part CA was determined.

[0092] In the fourth processing example, the determination period is set as "from the moment the electric motor MA is driven in the forward direction until the determination time tm has elapsed." The determination time tm is a predetermined value (constant) set in advance. The determination period in the fourth processing example is also referred to as the "rotation angle determination period" to distinguish it from other determination periods.

[0093] The rotation directions of the fluid pump QA and the electric motor MA are described below. A check valve GA is provided in the return channel HK. Therefore, the fluid pump QA can rotate in only one direction, but rotation in the other direction (opposite to the one direction) is prevented by the check valve GA. In other words, the one direction of the fluid pump QA is the direction in which the fluid pump QA can discharge the brake fluid BF, and the other direction of the fluid pump QA is the direction in which the fluid pump QA cannot discharge the brake fluid BF. In terms of the rotation direction of the electric motor MA, the forward rotation direction corresponds to the one direction of the fluid pump QA, and the reverse rotation direction corresponds to the other direction of the fluid pump QA.

[0094] In the fourth processing example, the motor rotation angle Ka (angular displacement from the zero point) is used as the motor state quantity Ma for determining suitability. In the fourth processing example, the determination condition is that "the motor rotation angle Ka has changed to a determination angle kx or more compared to the state before the determination period (i.e., the state before the electric motor MA is driven in the forward direction), and this state continues for a duration of tk." The determination angle kx and the duration tk are predetermined values ​​(constants). The duration tk is set to eliminate the influence of noise, etc. The determination condition for the fourth processing example is also referred to as the "fourth determination condition" to distinguish it from other determination conditions. If the fourth determination condition is met, an abnormal state of the coupling part CA is determined. In other words, the fourth determination condition is the condition for determining an abnormal state of the coupling part CA.

[0095] As described above, if the differential pressure valve UA and the inlet valve VI are completely closed, and the coupling part CA is normal, the electric motor MA and the fluid pump QA will not be able to rotate. On the other hand, if the motor rotation angle Ka increases from the state before the judgment period, it means that the electric motor MA is spinning freely or that the play (looseness) of the coupling part CA has increased. Therefore, if the fourth judgment condition is satisfied, an abnormal state of the coupling part CA is determined. When an abnormality of the coupling part CA is determined, a notification signal Wg is output to the notification device WG, and the operator is notified.

[0096] In power transmission at the connecting section CA, at least one of the motor end plane Mm and the pump end plane MQ may wear down, and the backlash (gap between members) between them may increase over time. The motor rotation angle Ka when both the differential pressure valve UA and the inlet valve VI are closed corresponds to the backlash at the connecting section CA. In the fourth processing example, since the motor rotation angle Ka is used as the motor state quantity Ma, an increase in backlash at the connecting section CA can be determined.

[0097] <<Variations of the 4th processing example>> In the above judgment example, the motor rotation angle Ka before the start of the judgment period was set as the zero point that serves as the reference for the motor rotation angle Ka. Furthermore, in order to more accurately detect the play in the connecting part CA, it is preferable for the electric motor MA to be driven in the reverse direction once before the judgment mode is activated.

[0098] Because the check valve GA prevents the fluid pump QA from rotating in other directions, when the electric motor MA is driven in the reverse direction, the gap (play) between the motor end plane Mm and the pump end plane MQ is eliminated in that reverse direction. The reverse drive of the electric motor MA before the judgment period is referred to as "play-eliminating drive".

[0099] In the modified version, first, the play in the connecting part CA is eliminated by a play-reducing drive, and the rotation angle Ka generated at that time is set as the zero point (0) related to that change. Then, during the rotation angle determination period, a suitability determination is performed based on the motor rotation angle Ka generated in the forward rotation direction from the zero point (0). Specifically, an abnormal state of the connecting part CA is determined when the motor rotation angle Ka (angular displacement from the zero point) becomes greater than or equal to a predetermined angle kx, using the zero point (0) set by the play-reducing drive as a reference. In the modified version, the play in the connecting part CA is eliminated prior to the determination period, so the accuracy of the abnormality determination of the connecting part CA can be improved to be more precise.

[0100] <Operation of the 4th Processing Example> Referring to the time-series diagram in Figure 6, the operation of the fourth processing example related to the determination of the suitability of the connecting part CA will be explained. In Figure 6, an abnormality of the connecting part CA is assumed to be a situation in which the play in the connecting part CA has increased.

[0101] Referring to Figure 6(a), the method for determining whether the electric motor MA is driven only in the forward direction will be explained. At time u1, the inlet valve VI and the differential pressure valve UA are driven in determination mode. Specifically, the supply current Ii (inlet valve current) to the inlet valve VI is increased, and the inlet valve VI is completely closed. Also, the supply current Ia (differential pressure valve current) to the differential pressure valve UA is increased to a value ig (>ic), and the differential pressure valve UA is also completely closed.

[0102] At time point u2, the judgment period begins, and the electric motor MA is driven in the forward rotation direction. Specifically, the current Im supplied to the electric motor MA is gradually increased to a predetermined current ib. The predetermined current ib is a preset value (constant) corresponding to the forward rotation direction of the electric motor MA. Note that the inrush current of the electric motor MA is not shown in Figure 6.

[0103] If the play in the connecting part CA increases (i.e., if there is an abnormality in the connecting part CA), from time u2, the motor rotation angle Ka increases from zero (0) in accordance with the increase in motor current Im (see characteristic line ZId shown by the dashed line). Here, the motor rotation angle Ka before the start of the judgment period is used as the zero point (0) that serves as the reference for the motor rotation angle Ka. At time u3, the motor rotation angle Ka relative to the zero point (0) (i.e., the amount of change in the motor rotation angle Ka from the zero point) becomes greater than or equal to the judgment angle kx. From time u3, the time count for the state of "Ka≧kx" begins. At time u4, the duration of the state of "Ka≧kx" reaches the duration tk. That is, the state in which the motor rotation angle Ka changes to greater than or equal to the judgment angle kx compared to the state before the electric motor MA was driven in the forward direction continues for a duration tk (a predetermined value). Since the fourth judgment condition is satisfied, an abnormality in the connecting part CA is determined at time u4.

[0104] If the coupling CA is functioning correctly, the play is minimal, and therefore the motor rotation angle Ka does not increase, or increases only slightly, from the state before the judgment period (i.e., the state before time point u2) (see the characteristic curve ZSd shown in solid line). Consequently, the fourth judgment condition is not satisfied within the judgment period (between time point u2 and time point u5). At time point u5, it is determined that the coupling CA is functioning correctly. In the fourth judgment example, the judgment mode drive also terminates when the judgment period ends. Alternatively, the judgment mode drive may terminate at time point u4, when the fourth judgment condition is satisfied.

[0105] ≪Variations≫ Figure 6(b) illustrates a variation of the fourth processing example in which the electric motor MA is initially driven in the reverse direction (opposite to the forward direction) before being driven in the forward direction. In Figure 6(b), the period from time u7 to time u8 is the play-reducing drive period, and the period from time u9 to time u12 is the judgment period.

[0106] In the modified configuration, first, at time u6, the inlet valve VI and the differential pressure valve UA are closed. Then, at time u7, the backlash reduction drive is started, and the electric motor MA is driven in the reverse direction. Specifically, the current Im supplied to the electric motor MA is gradually increased to a predetermined current id (considering the negative sign of the motor current Im, it is gradually decreased to a predetermined current id). The predetermined current id is a predetermined value (constant) that corresponds to the reverse direction of the electric motor MA. The backlash reduction drive continues for a predetermined time tn. The predetermined time tn is a predetermined value (constant) that is set in advance. The backlash reduction drive eliminates the gap between the motor end plane Mm and the pump end plane MQ.

[0107] The motor rotation angle Ka generated by the backlash reduction drive is determined as the reference zero point (0). For example, if the backlash is small, the zero point (0) will be value ka. Conversely, if the backlash is large, the zero point (0) will be value kb. At time u8, the backlash reduction drive is terminated, and the motor current Im is set to "0".

[0108] From time point u9, the motor current Im is gradually increased to a predetermined current ib. This drives the electric motor MA in the forward direction, and the motor rotation angle Ka gradually increases. Time point u9, when the forward rotation of the electric motor MA begins, is considered the start of the rotation angle determination period. From time point u9, the time count for the determination time tm begins. During the determination period, compliance is determined based on the motor rotation angle Ka, with the motor rotation angle Ka before the determination period as the reference (zero point).

[0109] If the play in the connecting part CA increases (i.e., if the connecting part CA is abnormal), the motor rotation angle Ka increases from the zero point (position of value kb) as the motor current Im increases (see characteristic line ZIe shown by the dashed line). At time u10, the motor rotation angle Ka relative to the zero point (value kb) (i.e., the amount of change in the motor rotation angle Ka from the zero point) becomes greater than or equal to the judgment angle kx. From time u10, the time count for the state "Ka≧kx" begins. At time u11, the duration of the state "Ka≧kx" reaches the duration tk. That is, the state in which the motor rotation angle Ka changes to greater than or equal to the judgment angle kx compared to the state before the electric motor MA was driven in the forward direction continues for a duration tk (a predetermined value). Since the fourth judgment condition is satisfied, an abnormality in the connecting part CA is determined at time u11.

[0110] If the coupling CA is functioning correctly, the play is minimal. Therefore, the motor rotation angle Ka does not increase from the zero point (position of value ka), or only increases slightly (see the characteristic curve ZSe shown in solid line). Consequently, the fourth determination condition is not satisfied within the determination period (between time points u9 and u12). At time point u12, it is determined that the coupling CA is functioning correctly. In the fourth determination example, the determination mode drive is terminated when the determination period ends. Alternatively, the determination mode drive may be terminated at time point u11, when the fourth determination condition is satisfied.

[0111] In the modified version, before the judgment period, the backlash of the electric motor MA is eliminated by reverse driving. Then, the electric motor MA is driven in the forward direction, and the judgment period begins. During the judgment period, the zero point (0) of the motor rotation angle Ka set by the backlash elimination drive is used as the reference, and changes in the motor rotation angle Ka are monitored. Since the zero point (0) of the motor rotation angle Ka is determined by the backlash elimination drive of the electric motor MA, abnormal conditions caused by backlash in the connecting part CA can be determined more accurately.

[0112] In the example operation described above, solenoid valves UA and VI were closed at time u6, before the play-reducing period. However, these valves only need to be closed before the start of the judgment period, time u9. In other words, the order could be "close solenoid valves UA and VI" → "play-reducing drive" → "judgment period," or it could be "play-reducing drive" → "close solenoid valves UA and VI" → "judgment period." This is because the reverse drive of the electric motor MA (corresponding to the other direction of the fluid pump QA) is prevented by the check valve GA.

[0113] <Second Embodiment of Brake Control Device SC> A second embodiment of the braking control device SC will be described with reference to the schematic diagram in Figure 7. Figure 7 shows a schematic representation of the fluid unit HU constituting the braking control device SC, as described in Japanese Patent Application Publication No. 2019-059294 (in particular, the pressure regulating unit YC of the upper fluid unit YU, and the portion from the master cylinder CM to the front wheel cylinder CWi for one wheel).

[0114] Vehicles to which the second embodiment of the braking control device SC is applied are provided with a braking operation amount sensor BA that detects the operating amount Ba ("braking operation amount") of the braking operating member BP. For example, as the braking operation amount sensor BA, an operating displacement sensor SP is provided that detects the operating displacement Sp of the braking operating member BP. In addition, a simulator pressure sensor PZ is employed that detects the hydraulic pressure Pz ("simulator pressure") of the stroke simulator SS. In the braking control device SC, the braking operation amount Ba is a general term for signals representing the driver's intention to brake, and the braking operation amount sensor BA is a general term for sensors that detect the braking operation amount Ba. The braking operation amount Ba is input to the controller ECU.

[0115] The braking control device SC is equipped with a stroke simulator SS (also simply called the "simulator"). The simulator SS generates the operating force Fp of the braking operating member BP. Since the braking control device SC is a brake-by-wire type, the operating characteristics of the braking operating member BP (relationship between operating displacement Sp and operating force Fp) are generated by the simulator SS. A simulator pressure sensor PZ is provided to detect the simulator pressure Pz. The simulator pressure Pz is a state variable that represents the operating force Fp of the braking operating member BP.

[0116] The fluid unit HU in the first embodiment was a general-purpose unit for performing anti-skid control and the like. In contrast, the second embodiment of the braking control device SC is a brake-by-wire type service brake device. The braking control device SC consists of the fluid unit HU and the controller ECU.

[0117] The fluid unit HU in the second embodiment is a unit for the service brake (also called the "operational brake"). The fluid unit HU adjusts the wheel pressure Pw of the wheel cylinder CW according to the braking operation amount Ba. Specifically, the wheel pressure Pw is controlled to increase as the braking operation amount Ba increases. Similar to the first embodiment, the fluid unit HU in the second embodiment also includes an electric motor MA, a fluid pump QA, a differential pressure valve UA, and an inlet valve VI.

[0118] The differences from the first embodiment in the second embodiment are that "the fluid pump QA can draw brake fluid BF from the master reservoir RV (also called the "atmospheric pressure reservoir")" and "the hydraulic pressure Pu ("servo pressure") adjusted by the differential pressure valve UA is transmitted to the wheel cylinder CW as wheel pressure Pw via the control cylinder CS and control piston NS." Specifically, in the second embodiment, the hydraulic pressure is transmitted in the order of "Pu → Ps → Pw." As described above, components with the same reference numerals as in the first embodiment have the same function, so the differences will be explained primarily.

[0119] The electric motor MA and the fluid pump QA are connected via a coupling part CA. Power from the electric motor MA is transmitted to the fluid pump QA via the coupling part CA. The electric motor MA is equipped with a rotation angle sensor KA to detect the rotation angle Ka of the rotor. The controller ECU calculates the motor rotation speed Na based on the motor rotation angle Ka.

[0120] In the fluid pump QA, the suction section Qi and the discharge section Qo are connected by a return channel HK. A differential pressure valve UA, which is a normally open linear solenoid valve, is provided in the return channel HK. A check valve GA is provided near the discharge section Qo in the return channel HK. Downstream of the differential pressure valve UA, the return channel HK is connected to the master reservoir RV via a reservoir channel HR (fluid channel) at a point Br (the point between the differential pressure valve UA and the suction section Qi) upstream of the suction section Qi. Furthermore, downstream of the check valve GA, the return channel HK is connected to the servo chamber Ru of the control cylinder CS via a servo channel HV (fluid channel) at a point Bs (the point between the fluid pump QA and the differential pressure valve UA) upstream of the differential pressure valve UA.

[0121] A control piston NS is inserted into the control cylinder CS. The inside of the control cylinder CS is divided into two hydraulic chambers (referred to as "servo chamber Ru" and "control chamber Rs") by the control piston NS. Servo chamber Ru is connected to the servo path HV. Control chamber Rs is connected to the wheel cylinder CW via the wheel path HW. An inlet valve VI, which is a normally open on / off solenoid valve, is provided in the wheel path HW (corresponding to the "hydraulic transmission path from output pressure Pu to wheel pressure Pw").

[0122] When the braking operation amount Ba is "0 (zero)" (i.e., when not braking), the fluid unit HU is not driven. Therefore, power is not supplied to the differential pressure valve UA, the electric motor MA, and the inlet valve VI. When braking, the electric motor MA is driven, and a circulating flow KN of "Qo→GA→UA→Qi" is generated in the return flow path HK, as shown by the dashed arrow. When the differential pressure valve UA is not powered and is in a fully open state, in the return flow path HK, the upstream hydraulic pressure Pu (servo pressure, which corresponds to "output pressure") and the downstream hydraulic pressure (atmospheric pressure) are equal with respect to the differential pressure valve UA (i.e., "Pu=0").

[0123] As the braking force Ba increases, the amount of current Ia (supply current) supplied to the differential pressure valve UA increases, which reduces the opening amount of the differential pressure valve UA. As a result, the circulating flow KN (the flow of breech fluid BF circulating in the return channel HK) is restricted by the differential pressure valve UA, and the flow of the circulating flow KN is obstructed. Consequently, the hydraulic pressure Pu (servo pressure) upstream of the differential pressure valve UA increases from atmospheric pressure.

[0124] The servo pressure Pu is supplied to the servo chamber Ru via the servo path HV. An increase in the servo pressure Pu pushes the control piston NS in the forward direction (increasing the volume of the servo chamber Ru and decreasing the volume of the control chamber Rs). This increases the hydraulic pressure Ps ("control pressure") in the control chamber Rs. Since the control chamber Rs is connected to the wheel cylinder CW via the wheel path HW, the pressure from the control chamber Rs is supplied to the wheel cylinder CW as the wheel pressure Pw. Note that during braking (in the case of service brakes when anti-lock brake control is not being performed), no power is supplied to the inlet valve VI, and the inlet valve VI is in a fully open state.

[0125] In the fluid unit HU according to the second embodiment, the circulating flow KN of the brake fluid BF discharged by the fluid pump QA is throttled by the differential pressure valve UA, thereby generating a servo pressure Pu. The servo pressure Pu is supplied to the servo chamber Ru in the control cylinder CS. The servo pressure Pu is transmitted as a control pressure Ps via the control piston NS. The control pressure Ps is then supplied as a wheel pressure Pw to the wheel cylinder CW via the wheel path HW.

[0126] The fluid unit HU is controlled by the controller ECU. The controller ECU receives the braking operation amount Ba (Sp, Pz, etc.) and the motor rotation angle Ka as input. Based on the signal of the braking operation amount Ba, the controller ECU performs service brake control. "Service brake control" is the control of the wheel pressure Pw according to the braking operation amount Ba in order to realize the function of the service brake. Specifically, the electric motor MA is driven by the controller ECU, and a circulating flow KN is generated in the return flow path HK. The differential pressure valve current Ia is adjusted so that it increases as the braking operation amount Ba increases. In this way, the service brake control is controlled so that the servo pressure Pu (and consequently the wheel pressure Pw) increases as the braking operation amount Ba increases. The controller ECU also performs a suitability check of the coupling part CA in the same manner as above.

[0127] <Third embodiment of the braking control device SC> A third embodiment of the braking control device SC will be described with reference to the schematic diagram in Figure 8. Figure 8 shows a schematic representation of the fluid unit HU constituting the braking control device SC, as described in Japanese Patent Application Publication No. 2019-059294 (in particular, the portion from the pressure regulating unit YC of the upper fluid unit YU to the rear wheel cylinder CWk for one wheel).

[0128] Similar to the second embodiment, the braking control device SC according to the third embodiment is a brake-by-wire unit for the service brake. The difference is that in the second embodiment, the servo pressure Pu is transmitted to the wheel cylinder CW via the control cylinder CS and the control piston NS, whereas in the third embodiment, the servo pressure Pu is transmitted directly to the wheel cylinder CW. Specifically, in the third embodiment, the return passage HK is connected to the wheel cylinder CW via the wheel passage HW at a location Bs (between the fluid pump QA and the differential pressure valve UA) downstream of the check valve GA and upstream of the differential pressure valve UA. As a result, the servo pressure Pu is directly supplied to the wheel cylinder CW as wheel pressure Pw. In the third embodiment as well, the controller ECU performs a suitability determination of the connection part CA.

[0129] <Summary of Embodiments> The following summarizes the embodiments of the braking control device SC. The braking control device SC consists of an electric motor MA, a fluid pump QA, a differential pressure valve UA, an inlet valve VI, and a controller ECU. The electric motor MA and the fluid pump QA are connected (joined) by a coupling part CA. The power from the electric motor MA is transmitted to the fluid pump QA via the coupling part CA, thereby driving the fluid pump QA. A fluid passage HK (recirculation passage) is provided to connect the discharge part Qo of the fluid pump A and the suction part Qi of the fluid pump QA.

[0130] A check valve GA is provided in the fluid passage HK. The check valve GA allows the fluid pump QA to rotate in one direction but not in the other direction (the opposite direction). In terms of rotation, one direction of the fluid pump QA corresponds to the forward rotation direction of the electric motor MA, and the other direction of the fluid pump QA corresponds to the reverse rotation direction of the electric motor MA. Therefore, if the connection CA is functioning correctly, the check valve GA allows the electric motor MA to rotate in the forward direction but not in the reverse direction.

[0131] A differential pressure valve UA is provided in the fluid passage HK. For example, the differential pressure valve UA is a normally open linear solenoid valve. The differential pressure valve UA increases the brake fluid BF discharged by the fluid pump QA to output pressures Pq and Pu. Specifically, in the first embodiment, the regulating pressure Pq corresponds to the output pressure, and the master pressure Pm is increased to the regulating pressure Pq. In the second and third embodiments, the servo pressure Pu corresponds to the output pressure, and atmospheric pressure is increased to the servo pressure Pu. Then, the wheel pressure Pw of the wheel cylinder CW is increased by the output pressures Pq and Pu.

[0132] An inlet valve VI (for example, a normally open on / off solenoid valve) is provided in the hydraulic pressure transmission path (HW, etc.) from the output pressure Pq, Pu to the wheel pressure Pw. Specifically, in the first embodiment, the hydraulic pressure transmission path corresponds to the wheel path HW connecting the section Bw between the differential pressure valve UA and the fluid pump QA to the wheel cylinder CW. In the second embodiment, the hydraulic pressure transmission path corresponds to the wheel path HW connecting the control chamber Rs of the control cylinder CS to the wheel cylinder CW. In the third embodiment, the hydraulic pressure transmission path corresponds to the wheel path HW connecting the section Bs between the differential pressure valve UA and the fluid pump QA to the wheel cylinder CW. In other words, the hydraulic pressure transmission path corresponds to the wheel path HW connected to the wheel cylinder CW. The electric motor MA, differential pressure valve UA, and inlet valve VI are driven by the controller ECU.

[0133] The controller ECU includes a compliance determination block BH to determine whether the coupling section CA is normal or abnormal. The compliance determination in the controller ECU (i.e., the compliance determination block BH) is performed when the vehicle is stopped (i.e., when "Vx=0"). For example, the compliance determination is performed as an initial check of the braking control device SC when the ignition switch is turned on. Alternatively, it may be performed when the vehicle doors are opened and the driver gets in (for example, when the courtesy switch is turned on). Furthermore, the compliance determination may be performed before the execution of automated driving, including automated parking control such as remote parking control.

[0134] When the controller ECU is driving the electric motor MA and the amount of opening of the differential pressure valve UA is reduced, it determines whether the coupling part CA is functioning normally based on the change in the motor state variable Ma related to the electric motor MA. Specifically, when the driving of the electric motor MA is maintained in a constant state (i.e., a steady state), the amount of opening of the differential pressure valve UA is reduced. At that time, the normality of the coupling part CA is determined based on the change in the motor state variable Ma. If the normality of the coupling part CA is not determined, an abnormality of the coupling part CA is determined.

[0135] The controller ECU (particularly in the first processing example) controls the rotational speed Na of the electric motor MA to a constant rotational speed na (i.e., a steady-state operation) and, when the opening amount of the differential pressure valve UA is reduced, performs a suitability determination based on the change (increase) in the output equivalent value Tm, which corresponds to the output of the electric motor MA. Specifically, if the output equivalent value Tm becomes equal to or greater than the determination threshold ix, the coupling section CA is determined to be normal. On the other hand, if the coupling section CA is not determined to be normal, the coupling section CA is determined to be abnormal. The determination threshold ix is ​​a threshold value for determination corresponding to the output equivalent value Tm, and is a predetermined value (constant) set in advance. When the coupling section CA is normal, if the opening amount of the differential pressure valve UA is reduced, the load on the electric motor MA increases. In the electric motor MA, the rotational speed Na is controlled to remain constant at a predetermined rotational speed na, so the motor current Im increases in accordance with the increase in load, so that the output equivalent value Tm increases. Therefore, if the output equivalent value Tm increases to or greater than the determination threshold ix, the coupling section CA is determined to be in a normal state.

[0136] The controller ECU (particularly in the second processing example) supplies a constant current im to the electric motor MA, driving the electric motor MA (i.e., in a steady-state driving condition), and when the opening amount of the differential pressure valve UA is reduced, it performs a suitability determination based on the change (decrease) in the rotational speed Na of the electric motor MA. Specifically, if the motor rotational speed Na becomes less than or equal to the determination rotational speed nx, the coupling section CA is determined to be normal. On the other hand, if the coupling section CA is not determined to be normal, it is determined to be abnormal. The determination rotational speed nx is a threshold value for determination corresponding to the motor rotational speed Na, and is a predetermined value (constant) set in advance. When the coupling section CA is normal, if the opening amount of the differential pressure valve UA is reduced, the load on the electric motor MA increases. Since the motor current Im supplied to the electric motor MA is a constant value im, the motor rotational speed Na decreases in accordance with the increase in load. Therefore, if the motor rotational speed Na decreases to less than or equal to the determination rotational speed nx, the coupling section CA is determined to be in a normal state.

[0137] The controller ECU (particularly in the third processing example) performs a suitability determination based on the change (decrease) in the rotational speed Na of the electric motor MA when the differential pressure valve UA is completely closed while the electric motor MA is driving. Specifically, the coupling section CA is determined to be normal if the motor rotational speed Na becomes less than or equal to the determination rotational speed nx. On the other hand, if the coupling section CA is not determined to be normal, it is determined to be abnormal. The determination rotational speed nx is a threshold value for determination corresponding to the motor rotational speed Na, and is a predetermined value (constant) set in advance. When the coupling section CA is normal and the differential pressure valve UA is fully closed, the load on the electric motor MA increases, and the motor rotational speed Na decreases. Therefore, if the motor rotational speed Na decreases to less than or equal to the determination rotational speed nx, the coupling section CA is determined to be in a normal state.

[0138] The controller ECU (particularly in the fourth processing example) performs a suitability determination based on the increase in the rotation angle Ka of the electric motor MA (specifically, the increase in the forward direction) when the electric motor MA is driven in the forward direction with the inlet valve VI and differential pressure valve UA closed. Specifically, if the motor rotation angle Ka changes to a determination angle kx or more compared to the state before the electric motor MA is driven in the forward direction, the coupling part CA is determined to be abnormal. On the other hand, if no abnormality is determined in the coupling part CA, the coupling part CA is determined to be normal. The determination angle kx is a threshold value for determination corresponding to the motor rotation angle Ka, and is a predetermined value (constant) set in advance. When the coupling part CA is normal, if the differential pressure valve UA and inlet valve VI are fully closed, the electric motor MA will be in a state where it cannot rotate at all. Therefore, if the motor rotation angle Ka increases to a determination angle kx or more, an abnormal state of the coupling part CA is determined. It is preferable that the electric motor MA is driven in the reverse direction opposite to the forward direction before being driven in the forward direction. By reversing the electric motor MA, the play in the coupling section CA is eliminated, which can improve the accuracy of the judgment. [Explanation of symbols]

[0139] SC... Brake control device, WG... Notification device, BP... Brake operating member (brake pedal), CM... Master cylinder, NM... Master piston, CW... Wheel cylinder, CS... Control cylinder, NS... Control piston, SS... Stroke simulator, HU... Fluid unit, ECU... Controller (electronic control unit), MA... Electric motor, QA... Fluid pump, Qi... Suction part of fluid pump, Qo... Discharge part of fluid pump, CA... Coupling (shaft coupling), GA... Check valve, UA... Differential pressure valve, HK... Return channel, HM... Master channel, HW... Wheel Circuit, HV...Servo Circuit, HR...Reservoir Circuit, VI...Inlet Valve, VO...Outlet Valve, Pm...Master Pressure, Pq...Adjustment Pressure (Example of Output Pressure), Pw...Wheel Pressure, Pu...Servo Pressure (Example of Output Pressure), Ps...Control Pressure, Ba...Brake Manipulation Amount, Rm...Master Chamber, Ru...Servo Chamber, Rs...Control Chamber, Im...Motor Current, Tm...Equivalent Output Value (Value equivalent to MA output), Ka...Motor Rotation Angle, Na...Motor Rotation Speed, ix...Judgment Threshold (Predetermined value for suitability determination), nx...Judgment Rotation Speed ​​(Predetermined value for suitability determination), kx...Judgment Angle (Predetermined value for suitability determination).

Claims

1. A fluid pump driven by an electric motor is connected via a coupling section, A differential pressure valve is provided in the fluid passage connecting the discharge section and the suction section of the fluid pump, and increases the wheel pressure of the wheel cylinder by increasing the brake fluid discharged by the fluid pump to an output pressure. The electric motor and the controller that drives the differential pressure valve, In a braking control device for a vehicle equipped with, The aforementioned controller, A vehicle braking control device that, after the electric motor is in a driving state, reduces the opening amount of the differential pressure valve, and then determines whether the coupling portion is functioning correctly based on the change in the state quantity related to the electric motor.

2. A fluid pump driven by an electric motor is connected via a coupling section, A differential pressure valve is provided in the fluid passage connecting the discharge section and the suction section of the fluid pump, and increases the wheel pressure of the wheel cylinder by increasing the brake fluid discharged by the fluid pump to an output pressure. The electric motor and the controller that drives the differential pressure valve, In a braking control device for a vehicle equipped with, The aforementioned controller, A vehicle braking control device that, after controlling the rotation speed of the electric motor to a constant rotation speed, reduces the opening amount of the differential pressure valve, and then determines whether the coupling portion is functioning correctly based on an increase in an output equivalent value corresponding to the output of the electric motor.

3. In the vehicle braking control device described in claim 2, The controller is a vehicle braking control device that determines that the coupling is normal when the output equivalent value is equal to or greater than a determination threshold.

4. A fluid pump driven by an electric motor is connected via a coupling section, A differential pressure valve is provided in the fluid passage connecting the discharge section and the suction section of the fluid pump, and increases the wheel pressure of the wheel cylinder by increasing the brake fluid discharged by the fluid pump to an output pressure. The electric motor and the controller that drives the differential pressure valve, In a braking control device for a vehicle equipped with, The aforementioned controller, A vehicle braking control device that, after supplying a constant current to the electric motor, reduces the opening amount of the differential pressure valve, and then determines whether the coupling is functioning correctly based on the decrease in the rotational speed of the electric motor.

5. A fluid pump driven by an electric motor is connected via a coupling section, A differential pressure valve is provided in the fluid passage connecting the discharge section and the suction section of the fluid pump, and increases the wheel pressure of the wheel cylinder by increasing the brake fluid discharged by the fluid pump to an output pressure. The electric motor and the controller that drives the differential pressure valve, In a braking control device for a vehicle equipped with, The aforementioned controller, A vehicle braking control device that, after the electric motor is in a driving state, completely closes the differential pressure valve and determines whether the coupling portion is functioning correctly based on the decrease in the rotational speed of the electric motor.

6. In a vehicle braking control device according to claim 4 or claim 5, The controller is a vehicle braking control device that determines that the coupling is functioning normally when the rotational speed falls below a predetermined rotational speed.

7. A fluid pump driven by an electric motor is connected via a coupling section, A differential pressure valve is provided in the fluid passage connecting the discharge section and the suction section of the fluid pump, and increases the wheel pressure of the wheel cylinder by increasing the brake fluid discharged by the fluid pump to an output pressure. An inlet valve is provided in the hydraulic pressure transmission path from the output pressure to the wheel pressure, A check valve that allows the discharge of brake fluid from the fluid pump in one direction but blocks it in the opposite direction, The electric motor, the differential pressure valve, and the controller that drives the inlet valve, In a braking control device for a vehicle equipped with, The aforementioned controller, A vehicle braking control device that, when the electric motor is driven in the forward rotation direction corresponding to the one direction with the inlet valve and the differential pressure valve closed, determines whether the coupling portion is normal or not based on the increase in the rotation angle of the electric motor.

8. In the vehicle braking control device described in claim 7, The controller is a vehicle braking control device that determines that the coupling is abnormal when the rotation angle exceeds a determination angle, based on the state before the electric motor is driven in the forward rotation direction.

9. In the vehicle braking control device described in claim 8, The controller is a vehicle braking control device that drives the electric motor in a reverse direction opposite to the forward direction before driving the electric motor in the forward direction.

Images